[From the U.S. Government Publishing Office, www.gpo.gov]





                                                                                                  OCS Study
                                                                                                   MMS 99-0060


              Coastal Marine Institute

              Effect of Produced-Water Discharge
              on Bottom Sediment Chem istry

              Final Report







                                    '
                                                 "s       a
                                     7
                                                               na-,-





                                       Gu4f of Mexico


              TO
              195
              T4
              Ell
              1999





                              U:S. Deppriment of the Interior                        Cooperative Agreement
               AM             Minerals management Service                            Coastal Marine Institute
                             Gulf of Mexico OCS Region                               Louisiana State University







                                                                                                 OCS Study
                                                                                                 MMS 99-0060


             Coastal Marine Institute

             Effect of Produ'ded-W a"tor'- Discharge
             on Bottom Sediment Chemistry

             Final Report





             Editors


             Ronald D. DeLaune
             Charles W. Lindau
             and
             Robert P. Gambrell








             November 1999







             Prepared under MIVIS Contract
             14-35-0001-30660-19907
             by
             Wetland Biogeochemistry Institute
             Louisiana State University
             Baton Rouge, Louisiana 70803






             Published by


             U:S. Depprtment of the Interior                                       Cooperative Agreement
             Minerals management Service                                           Coastal Marine Institute
             Gulf of Mexico OCS Region                                             Louisiana State University









                                        US Department of Commerce
                                    NOAA Coastal Services Center Library
                                          2234 South Hobson Avenue
                                          Charlestor4 SC 29405-2413











                                                   DISCLAIMER


           This report was prepared under contract between Louisiana State University Coastal Marine
           Institute and the U.S. Dept. of the Interior, Minerals Management Service (MMS). This report
           has been technically reviewed by the MMS and it has been approved for publication. Approval
           does not signify that the contents necessarily reflect the views and policies of MMS, nor does
           mention of trade names or commercial products constitiute endorsement or recommendation for
           use. It is, however, exempt from review and compliance with the MMS editorial standards.



                                             REPORT AVAILABILITY


           Extra copies of this report may be obtained from the Public Information Office (Mail Stop 5034)
           at the following address:

                                         U.S. Department of the Interior
                                         Minerals Management Service
                                         Gulf of Mexico OCS Region
                                         Public.Information Office (M[S 5034)
                                         1201 Elmwood Park Boulevard
                                         New Orleans, Louisiana 70123-2394

                                         Telephone:    (504) 736-2519 or
                                                        1-800-200-GULF



                                                     CITATION


           Suggested citation:

           DeLaune, R.D., C.W. Lindau, and R.P. Gambrell, eds. 1999. Effect of Produced-Water
                   Discharge on Bottom Sediment Chemistry. U.S. Dept. of the Interior, Minerals
                   Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS
                   99-0060. 47 pp.











                                             EXECUTIVE SUMMARY


                    Petroleum hydrocarbons, metals and radionuclides can enter the environment as the result
            of petroleum extraction and recovery operations. Produced water discharge associated with oil
            recovery has in the past introduced these compounds into Louisiana aquatic environment,
            including the sediment column.      Investigations were conducted to determine the factors
            determining solubility and mobility of these pollutants in sediment.

                    The effect of sediment redox conditions on the solubility of Fe, Pb, Ni, Ba, and Cu in
            bottom sediment collected from a produce water discharge site was invested using kinetics and
            chemical fractionation procedures. Under oxidizing sediment conditions, the behavior of Fe, Pb
            and Ni were governed by Fe(M) and Mn(IV) oxides; Ba by insoluble complexation with humic
            compounds, Cu by carbonates and humic complexation. Under reducing sediment condition, the
            behaviors of Fe and Cu were controlled by the formation of insoluble. sulfides, carbonates and
            humic complexes.

                    Kinetics and chemical fractionation procedures were also used in quantifying the effects
            of sediment redox (Eh) condition on the behaviors of As, Cd, Cr and Zn in the bottom sediment.
            Under oxidizing conditions, As, Zn and Cr behavior were governed by redox chemistry of Fe(IH)
            and Mn(M oxides. Cd transformations were controlled by both Fe(1111), Mn(M oxides and
            carbonates. Under reducing condition, the behaviors of Zn and Cr was controlled primarily by
            insoluble large molecular humic material and sulfides; the behavior of Cd was controlled by
            carbonates. When sediment redox potential increased, the affinity between Fe(HI), Mn(IV)
            oxides and As. Cd, Cr, and Zn increased. Results suggest reducing conditions in bottom
            sediment sites of produced water discharge would limit heavy metal availability.

                    Sediment collected from a produced water discharge site and in waste pit was extracted
            into various chemical fractions and analyzed for radium-226 (fractions included water-soluble,
            exchangeable, forms associated with carbonates, reducible, or organic/sulfide).           It was.
            determined that 95 percent of the radium present was tied up in an unavailable form that could be
            extracted only with very strong acids. Radium in this fraction would be released very slowly
            into the environment. Results showed that less than 5% of the radium in sediment was in
            potentially available forms.

                    Petroleum hydrocarbon degradation in sediment collected from a low energy brackish
            wetland site which had been exposed for a number of years to produced water discharge was also
            studied. Recalcitrant or higher molecular weight compounds were the primary hydrocarbon
            fractions found in the sediment. Oxidized sediment conditions resulted in a higher rate of
            degradation for most hydrocarbons fractions as compared to degradation in reduced sediment
            following addition of South Louisiana Crude oil. Nutrient amendments to contan-tinated
            sediments significantly increased rate of hydrocarbon degradation.

                    The effect of chromium (Cr) and lead (Pb) on degradation added South Louisiana Crude
            oil in sediment showed that metal concentration normally found at produced water discharge
            sites would not influence degradation of hydrocarbon in the sediment profile.




                                                            v













                                                                   TABLE OF CONTENTS



                                                                                                                                                      PAGE


                            List of Figures      ................................................................................                     ix
                            List of Tables      ..................................................................................                    xi


                1.0         Introduction      ..............................................................................................................I


                2.0         Materials and Methods             ............................................................................................3

                            2.1        Effect of Sediment Redox Conditions on Heavy Metal Chemisty                                   ..............   3
                            2.2        Radium Chemistry            ........................................................................................6
                            2.3        Effect of Heavy Metal Content of Sediment on Petroleum
                                       Hydrocarbon Degradation               .............................................................................6
                            2.4        Degradation of Petroleum Hydrocarbons in Sediment Receiving
                                       Produced Water Discharge                ...........................................................................8

                                       2.4.1      Experiment I - Degradation of Residual Hydrocarbons                             ................... 8
                                       2.4.2      Experiment 11 - Effect of Oxidizing Sediment Conditions
                                                  on Degradation of South Louisiana Crude                       .......................................8
                                       2.4.3      Experiment III - Nutrient Influence on Hydrocarbon
                                                  Degradation        .....................................................................................9

                3.0         Results and Discussion             ............................................................................................. I I

                            3.1        Effect of Sediment Redox Condition on Heavy Metal Chemistry                                    ............... 11
                            3.2        Radium Chemistry             ........................................................................................ 23
                            3.3        Effect of Heavy Metal on Petroleum Hydrocarbon Degradation                                   .................. 26
                            3.4        Degradation of Petroleum Hydrocarbons in Sediment Receiving Produced
                                       Water Discharge           ............................................................................................ 33
                                       3.4.1 Degradation of Residual Hydrocarbons (Exp. 1)                               .............................. 33
                                       3.4.2 Effect of Oxidized Sediment Conditions on Degradation of South
                                                  Louisiana Crude (Exp. 11)              ................................................................. 37
                                       3.4.3 Nutrient Influence on Hydrocarbon Degradation (Exp. 111)                                   ............. 37

                 4.0        Summary        ................................................................................................................... 41

                 5.0        References        ......................I.........................  ................................................................. 43










                                                                                       Vii












                                                                  LIST OF FIGURES


                 Figure                                                                                                                          PAGE

                 I                   Location of Lirette (LRT) site from which sediment samples were
                                     collected  ................................................................................                 4
                 2.1                 The effect of Eh on the distribution of Fe in the chemical fractions                     ...............    12
                 2.2                 The effect of Eh on the percentage of Fe in the various chemical fractions                        ....      12
                 3.1                 The effect of Eh on the distribution.of Pb in the chemical fractions                     ..............     14
                 3.2                 The effect of Eh on the percentage of Pb in the various chemical
                                     fractions  ..................    ...............................................................            14
                 4.1                 The effect of Eh on the distribution of Ni in the chemical fractions                     ................   15
                 4.2                 The effect of Eh on the percentage of Ni in the various chemical fractions                        ....      15
                 5.1                 The effect of Eh on the distribution of Ba in the chemical fractions                     ...............    17
                 5.2                 The effect of Eh on the percentage of Ba in the various chemical
                                     fractions  .................................................................................                17
                 6.1                 The effect of Eh on the distribution of Cu in the chemical fractions                     ..............     18
                 6.2                 The effect of Eh on the percentage of Cu in the various chemical ,,
                                     fractions  .................................................................................                18
                 7                   The effect of Eh on the distribution of As in the chemical fractions............ 20
                 8                   The effect of Eh on the percentage (expressed as g/kg) of As in the
                                     various chemical fractions         .............................................................................. 20
                 9                   The effect of Eh on the distribution of Cr in the chemical fractions                     ................   21
                 10                  The effect of Eh on the percentage (expressed as g/kg) of Cr in the
                                     various chemical fractions         ................................................................................ 21
                 I I                 The effect of Eh on the distribution of Cd in the various chemical fractions                                .... 22
                 12                  The effect of Eh on the percentage (expressed as g/kg) of Cd in the
                                     various chemical fractions         ................................................................................. 22
                 13                  The effect of Eh on the distribution of Zn in the various chemical fractions                                .... 24
                 14                  The effect of Eh on the percentage (expressed as g/kg) of Zn in the
                                     various chemical fractions         ................................................................................. 24
                 15                  226Ra activity in various chemical fractions in Humble Canal sediment
                                     incubated under aerobic and anaerobic conditions                   ............................................ 25
                 16                  226Ra activity in various chemical of waste pit sediment incubation under
                                     aerobic and anaerobic conditions             .........................................................      25
                 17                  Chromium and lead effects on total hydrocarbon degradation in oxidized
                                     and reduced sediment suspensions               ................................................................... 27
                 18                  Chromium and lead treatment effects on changes in total petroleum
                                     hydrocarbon (percent) in oxidized and reduced sediment suspensions
                                     during 91 days of incubation            ........................................................................... 29
                 19                  Effect of chromium on changes in percent of hydrocarbon degraded in
                                     oxidized and reduced sediment suspensions receiving 0 mglkg (0), 250
                                     mg/kg (11), 1000 mg/kg (V) and 5000 mg/kg (A) Cr added                         ............................. 31
                 20                  Effect of lead on changes in percent of hydrocarbon degraded in oxidized
                                     and reduced sediment suspensions receiving 0 mglkg (0), 100 mg/kg (0),
                                     500 mg1kg (V) and 2500 mg/kg (A) Pb added                     .......................................       32



                                                                                 ix











          21             Change in selected hydrocarbon fraction with time under oxidized
                         conditions ................................................................................ 34
          22             Change in selected hydrocarbon fractions with time under reduced
                         conditions .............................................................................. 35
          23             Degradation of selected fractions of South Louisiana Crude under
                         oxidized conditions (+450 mV)  ....................................................................... 38
          24             Linear regression degradation rates of selected hydrocarbon fractions as
                         affected by redox and fertilizer additions (C = Control, R = Reduced,
                         0    Oxidized, LF   Low Fertilization, BF   High Fertilization) .................... 39









































                                                           X













                                                               LIST OF TABLES


              Table                                                                                                                PAGE


              I                 Sediment characterization         .............................................................................. 10
              2                 Hydrocarbon compounds analyzed                ............................................................... 10
              3                 The rate constants K (mglkg/d) of the pseudo-zero-order reaction
                                involving Fe     ..........................................................................            13
              4                 Water soluble plus exchangeable chromium and lead concentrations in
                                oxidized and reduced suspensions             .............................................................. 26
              5                 Chromium and lead effect on total hydrocarbon degradation (total of all
                                alkane fractions) as affected by oxidized and reduced soil suspensions
                                (91 days of                                                                                            28
              6                 Effect of chromium and lead treatments on the percent total
                                petroleum hydrocarbons degraded (after 91 days) in oxidized and reduced
                                sediment suspensions         ................................                            ........      30
              7                 Degradation of residual hydrocarbons in produced water sediment                        ................ 36

































                                                                             xi










                                 EFFECTS OF PRODUCED WATER DISCHAR                       GE
                                       ON BOTrOM SEDII"NT CHENUSTRY


                                                     Project Personnel:
                     T.Z. Guo, B.C. Banker, 1. Devai, R.D. DeLaune, C.W. Lindau, C. Mulbah
                                                     and R-P. Gambrell


                                                Louisiana State University
                                           Wetland Biogeochemistry Institute



            1.0 INTRODUCTION


                   During the production of crude oil, condensates or natural gas and water may also be
            brought to the surface. This water is called formation water, produced water or oil field brine.
            Produced waters are one of a variety of wastes generated from oil and gas production wells (Neff
            et al. 1987). The volume ofwater produced may be quite large (Neff et al. 1989). It has been
            estimated that a total of 2 million barrels of oil and gas produced waters are discharged into the
            State waters of Louisiana per day from nearly 700 sites among the 70 oil and gas fields. At the
            time of the study, 23%, 22% and 17% were discharged into fresh, brackish and saline wetland
            environments, respectively, with the remainder discharged into open embayments or nearshore
            Gulf waters (Boesch and RabaWs 1989). Petroleum production and recovery activity in Louisiana
            coastal zone can discharge a considerable amount of produced waters (Boesch and Rabalais 1989).
            The produced waters can contain elevated concentrations of toxic metals radium and petroleum
            hydrocarbons as compared to the receiving water (St. Pe 1990). It is estimated that annually 1.7 to 8.8
            million metric tons of petroleum hydrocarbons are released into the environment (Leahy and Colwell
            1990). Metals in produced water can include bariurn, cadmium, chron-@iurn, iron, mercury, manganese,
            strontium and thallium (Tillery et al. 1981; Koons et al. 1977; Lyssj 1981). As the produced water
            enters wetland environments, toxic metals can enter the sediment column.
                    Produced water discharge can lead to contamination of sediments, streams and wetlands.
            Production waters from oil recovery process are passed through pits for an indeterminate time
            until being discharged into the environment. Petroleum hydrocarbons, metals, and radionuclides
            are prevalent pollutants in produced waters and sediments (Neff et al. 1989; St. Pe' 1990).
            Petroleum components, specifically polycyclic aromatic hydrocarbons, can contain numerous
            carcinogenic and mutagenic compounds. Substantial contamination of fine-grained sediments
            with petroleum hydrocarbons of produced water origin has been observed with distance fi7om
            produced water sites in coastal Louisiana (Rabalais et al. 1991).
                    Analysis of total metal concentration in sediment quantifies the degree of trace metal
            enrichment. Total metal content does not provide infon-nation on transfon-nation and mobilization of
            trace metals. Speciation studies can: 1) provide an insight into metal distribution patterns, 2) identify
            metal bioavailability and toxicity in ecosystems, and 3) explain transformation and mobility of metal
            species. Metal species distribution has been studied in various ways (Gambrell et al. 1991 a; Giblin et
            a . 1986; Giesy et al. 1977; Keller and Vedy 1994). These techniques have included multistep
            extractions in which a chemical solution removes various metal forms. Such fractionation schemes can
            provide information on the general behavior of metals in sediment and provides an estimate of their









              potential mobility (Keller an d Vedy 1994). Metals in sediment are generally considered to be present in
              the following forms: water soluble, exchangeable, carbonate bound, ferric and manganic oxide bound,
              organic matter and sulfide bound, silicate bound and residual.
                     The oxidationlreduction state (redox potential) of sediment is an important parameter affecting
              heavy metal transformation and hydrocarbon degradation. The redox. conditions (Eh) of estuarine
              sediment varies widely from approximately +500 rnV (surface sediments) to approximately -300 mV
              (strongly reducing sediments). Sediment redox levels can greatly affect to)dc metal uptake by plants
              (Gambrell and Patrick 1988; Giblin et al. 1986), leaching losses of toxic metals by runoff or ground
              water (Folson et al. 1988; Palermo et al. 1989), bU there is little information on redox chemistry of
              toxic metals in different geochemistry forms in sediment.
                     Heavy element species kinetics in wetland soil kinetics are influenced by many factors. T'hese
              factors include temperature, organic matter, surface activity of Fe and Mn compounds, microorganism
              activity and other sediment characteristics. Since it is difficult to study these factors individually, the
              factors were combined in this study into one parameter, the rate constant of the assumed zero-order
              reaction. This pseudo-zero-order reaction model was used in this study. When the rate constant is
              positive, the metal content increases in the specific fraction. When the rate constant is negative, the
              metals are removed from the specific fraction. When considering trace elements bound to the organic
              matter and sulfide phase, it was assumed that the formation of insoluble organic matter (complexation
              of insoluble, large molecular weight humic fi7action) and sulfides was independent (Gambrell and
              Patrick 1978; Gambrell et al. 1980). At sediment Eh = -130 mV or Eh> -130 mV, the changes in
              heavy elements in this fraction were due to insoluble, large molecular weight humic substances.
                      Surface of clays, organic matter, and iron oxides in sediment will absorb or desorb heavy

              Gambrell et al. 1980). Significant heavy element content is also associated with sediment carbonates
              elements when the ionic composition or Eh-pH changes (Keller and Vedy 1994; Khalid et al. 1981;

              (Ramos et al. 1994; Gambrell 1994). This fraction would be susceptible to pH change. Iron and
              manganese oxides existing as nodules and concretions, cemented between particles or on particle
              coatings in sediment are excellent scavengers for heavy-elements and are affected by sediment Eh and
              pH change (Feijtel et al. 1988; Levy et al. 1992). Heavy elements are also bound to various insoluble
              organic fon-ns such as living orgar-@isms, detritus, and hurnic material (Gambrell et al. 1980; Ramos et al.
              1994). Sediment redox conditions can affect the degradation and solubility of such organic material
              and then influence the release of heavy elements. Heavy elements can also exist as suffides under
              anaerobic conditions (Gambrell et al. 1980; 1991b) which are susceptible to Eh and pH changes.
              Heavy elements found in primary and secondary minerals are relatively stable in a natural sediment
              environment (Gambrell 1994).
                      Radionuclides in produced waters include naturally occurring radium-226. Produced
              water and drilling muds are commonly stored in waste pits created at the production site. In
              Louisiana alone, an estimated 20,000 oil-production sites are known to have radioactive
              contamination significant enough to require permitting. Produced water brines in the Gulf of
              Mexico region can contain up to 37 Bq L-1 of Radium 226 (Kraemer and Reid 1984), an amount
              ten times the levels found in natural water. Little is known about the fate of radium in sediment
              and waste pits. In order to improve our ability to predict its migration into aquatic environments
              and the food chain, we must understand the physical and chemical processes controlling solubility
              and movement.
                      Cocontaminants (e.g., heavy metals) at sites contaminated with petroleum hydrocarbon has
              raised the question of the reliability of natural detoxification and engineered remediation processes in



                                                                    2









             these complex mixtures. Interactions between the contaminants may inhibit biodegradation processes
             occurring in the site. One example is the inhibition of biodegradation in contaminated sediments by the
             presence of toxic heavy metals such as Cd, Cr, Zn, and Hg. Studies have documented the toxicity of
             metals to microorganisms in culture (Farrell et al., 1990) and in soils and sediments (Capone et al.,
             1980). However, few studies have concentrated on non-lethal effects of heavy metals on microbial
             functions (e.g., biodegradation of orgar:iic chernicals), particularly in sediments.
                     Studies which have been perforined on these processes indicate that effects of metals on
             biodegradation processes are complex and dependent on the type, concentration, and speciation of the
             metals added (Said and Lewis 1991). Understanding metal impact on petroleum hydrocarbon
             degradation is important in the implementation of remediation at waste or spill sites.
                     Hydrocarbon biodegradation is influenced by both physicochemical and biological properties of
             the environment. Extensive research has been carried out on the biodegradation of sludge (Boyd and
             Shelton, 1984; Bossert et al., 1984) and other hydrocarbon compounds (Zhang and NMer, 1992;
             Nfiller and Bartha, 1989; Oberbremer et al., 1990). There is little information on degradation of
             petroleum hydrocarbon in sediment receiving produced water discharge.
                     In this study, the kinetics and transforinations of heavy metals, radiurn, and petroleum
             hydrocarbon degradation in estuarine sediment at a site in Coastal Louisiana receiving produced water
             discharge were examined.       The effects of sediment redox potential (Eh) on the kinetics of
             transfori-nation of toxic metals and radium in sediments are detailed. Petroleum hydrocarbon
             degradation was also studied.


             2.0 MATERIALS AND METHODS


             2.1     Effect of Sediment Redox Conditions on Heavy Metal Chemistry

                     Studies were designed to determine the speciation and solubility of heavy metals in
             sediment receiving produced water discharge. Sediment was collected from a canal (Humble
             Canal) from a waste pit at the point of discharge associated with a petroleum recovery operation
             in the Lirette Oil and Gas field in Terebonne _parish (Fig. 1). The effluent or produced water was
             discharged from the secondary compartment of the pit into the canal (St. Pe, 1990). Five active
             wells contributed produced water to the pit. Average discharge has been reported to be 482
             barrels per day (St. Pe, 1990). The sediment had a pH=7.0 and contained 0.1% Ba, 0.04% Mn
             and 2% Fe. The heavy metal content of the sediment was determined using wet ashing and ICP
             procedures.
                     Two hundred grams of sediment (dry weight equivalent, amended with 0.3% (W/W)
             ground dried plant material) was added to 1.8 L of 5% salinity sea water in laboratory
             microcosms used to control sediment Eh-pH conditions. The microcosm originally described by
             Patrick et al. (1973), equipped with a combination pH electrode, Pt-electrodes and reference
             electrodes, allows for the continuous recording Eh and pH.
                     The sediment suspensions were kept stirring with a magnetic stirrer. The suspensions
             were preincubated at 26 OC under aerobic condition (+430 mV) for 25 days. After the initial
             preincubation, the suspensions were purged with nitrogen gas and maintained under anaerobic






                                                                 3























                                                                                                                                                                                                                                   0
                                                                                                                                                                                                                                   0
                                                                                                                                                                                   @tank
                                                                                                                                                                                   battel'y"'




                                                                                                                                                                                                                     aste
                                                                                                                                                                                                                    P   .t
                                                                                                                                                                                                                                                       Sampfin6:.'
                                                                                                                                                                                                                      outfall


                                                                                                                                                                                                                                                                                                                                                         N


                                                                                                                                                                                                                                                                      Ali








                                                                                                                                                                                                                                                                                            -ILL


                                                                                                                                                                                                                                                                                                                                                                                        to
                                                                                                                                                                                                                                                                                                                                                 F.



                                                                                                                                                                                                                                                              W",
                                                                                                                                                                                                                    14              t
                                                                       Louisiana Costal W011ands
                                                                                                                                                                                                           14





                                                                                                                                                                                                                                                                                                                                                                                        MISSISSIPPI




                                                                                                                                                                                                                                                                                                                                                                .5                                               J-@r





                                                                                                                                                                                                                                                                             city
                                                                                                                                                                                                                                                                                                                                                                              1z
                                                   - - - - - - -                                                                      . . . . . . . ....  .......
                                                                                                        C


                                                                                                                                                                                                                            D,L..

                                                                                                                                                                                                                                                                                                                                                                                        . . . . .. . . . . . .









                                                                                                                                                                                                                                                                                           OF                                                                                           0          12.4 24.6
                                                                                                                                                                                                                                                                                                                                                                                        0           20              46



                                                                                                                                                                              THE LOUISIANA COASTAL ZONE


                                                                  Figure 1.                                                    Location of Lirette (LRT) site from wbich sediment samples were collected
                                                                                                                                (from Guo et al. 1997a, 1997b).


                                                                                                                                                                                                                                                    4












             condition (-170 mV). The suspensions were maintained at pH=7.0, (the normal pH of.sediments
             under flooded conditions), by addition of diluted HCI or NaOH solution as needed during the
             preincubation and anaerobic incubation periods.
                     Metal was added to the sediment suspension at a rate four times of the original heavy
             metal contents of the sediment. The heavy metal contents of the sediment with added metals
             were: Cu--610 mg/kg, Pb--300 mgtkg, Cd=21 mg/kg, Zrt=800 mg/kg, Cr--210 mgtkg, As=370
             mg/kg, and Ni=580 mg/kg. No barium was added to the sediment.
                     Samples from the sediment suspensions were taken at selected intervals. The suspension
             samples were centrifuged and the supernatant filtered through a 0.45 [un membrane filter. This
             supernatant was assumed to be water soluble. The remaining sediment was extracted sequentially as
             described below. The sediment sample was kept under nitrogen or oxygen free atmosphere during
             extraction. Following removal of the water soluble phase, the sediment was sequentially extracted into
             fine fractions (F I to F5) described below.

                     FI-Exchangeable Phase. The solid phase from the water soluble fraction was extracted at
             room temperature for 30 min.-,,with 8 ml 0.5 M Mg(NO3)2/g dry weight sediment, adjusted to pH 7.0
             with nitric acid. The samples were agitated continuously.

                     F2-Bound to Ca-bonale Phase. The sediment residue from F1 was leached at room
             temperature for five hours with 8 ml, IM NaOAc, adjusted to pH 5.0 with acetic acid for I g dry
             weight sediment. These samples, were also agitated continuously.

                     F3-Bound to Iron andMcwganese Oxides Plum. The sediment residue from F2 was extracted
             at 96 T for six hours with 20 rrA 0.08 M NH20H HCI in 25% (v/v) acetic acid for I g dry weight
             sediment. These samples were occasionally agitated.

                     F4-Bound to Organic Matter and Suodes Phase. For I g of dry weight sediment, the
             sediment residue from F3 was extracted at 85 OC for 2 hrs. with 3 n-d 0.02 M HN03 and 5 nil 30%
             H-202 (adjusted to pH = 2.0 with HN03) was added, and extraction continued at 85 T for another 3h.
             The sample was then cooled, 5 nil 3.2 M NILOAc in 2% (V/V) UN03 was added, and the sample was
             diluted to 20 ml with deionized water. The samples were agitated continuously for 30 n-dn. NH40Ac
             was added to prevent adsorption of extracted metals onto the oxidized sediment.

                     F5-Mineral Matrbc Phase. The sediment residue from F4 was extracted with 25 nil
             concentrated EN03 for I g of dry weight sediment at 105 OC, the sediment was digested until 5 ml
             solution was let and the sample was diluted to 25 ml with deionized water.
                     The above sequential extractions were conducted in 250 n-A centrifuge tubes which prevented
             any loss of sediment between the successive extractions. Separation was conducted by centrifuging at
             5000 rpm for 30 min. Supernatants were filtered using 0.45 @irn millipore filters and then analyzed for
             metals. The residues were rinsed with 8 ml deionized water for I g dry weight sediment and
             centrifuged at 5000 rpm for 30 min, These second supernatants were discarded.
                     Metal concentrations in the water soluble phase and the chemical extracts were determined by
             ICP. Quality assurance was conducted by spiking extracts with certified element standards.




                                                                5












              2.2     Radium Chemistry

                      Another set of experiments were conducted to determine the speciation and solubility of
              radium. The primary study site from which sediment was collected was also located in the Lirette
              Oil and Gas field (Humble Canal located in a tidally influenced brackish marsh environment).
              Additional sediment samples were collected from waste pits located in Quarantine Bay. Sediment
              at both sites had been exposed to produced water. Microcosm studies were initiated for studying
              the partitioning of radium as influenced by either oxidized and reduced sediment conditions at the
              two sites.
                      Sediment was incubated in the microcosms in a similar manner as heavy metal studies.
              Two hundred grams of sediment on a dry weight basis (amended with 0.2% (W/W) ground dried
              plant material) was added to 1.8 L deionized water in laboratory microcosms under controlled
              Eh-pH condition. The fticrocosm described by Patrick et al. (1973) originally, equipped with a
              combination pH electrode, Pt-electrodes and reference electrodes, allowed for the continuous
              recording or controlling sediment Eh and pH.
                      The sediment suspensions were kept suspended with a magnetic stirrer. The suspensions
              were preincubated at 260C under aerobic conditions for 25 days. After the initial preincubation,
              the suspensions were purged with nitrogen gas and maintained in anaerobic condition. The
              suspensions were maintained at pH=7.0, the natural pH of the sediments, by addition of diluted
              HCI or NaOH solution as needed during the preincubation and anaerobic incubation periods. Eh
              was maintained at preset conditions ranging from +600 mV (oxidized) to -250 mV (reducing).
                      After incubation and equilibration of sediment under oxidized (+600 mV) and reduced
              250 mV) conditions aliquots were removed from each microcosm and chemically extracted. The
              sequential extraction procedures adopted from R.D. Shannon (1991) as described previously (in
              the metal section) with a minor modification of the residue fraction was used for determining the
              partitioning phase of the radium over time under various sediment redox conditions.
                      Direct y-ray spectrometry of daughter products using a shielded, Ge(Li) detector
              interfaced with a multichannel analyzer was used for determining 22@Ra activity in the fractions
              (Michel et al., 1981). Primary quantification of 226Ra was made by analysis          of 214Bi daughter
              product (energy 609 keV, 43*0 y per 100 disintegrations). The instrument was. calibrated using a
              22@Ra standard from the National Bureau of Standards (NBS), Washington, DC. Extract samples
              were placed in polycarbonate bottles and sealed for daughter in-growth for I month.. Samples
              were counted until at least 1000 counts were detected.


              2.3     Effect of Heavy Metal Content of Sediment on Petroleum Hydrocarbon Degradation

                      Sediment used in this study was also collected from a stream in the Lirette Oil and Gas field in
              Terebonne Parish (Fig. 1). Five hundred grams of homogenized wet sediment was placed into each of
              eight 2 L flask microcosms and water added to produce a sediment: water ratio of 1: 10 (on weight
              basis). Each suspension was kept continuously stirred with a magnetic stirrer. The soil pH and
              temperature were maintained at 6.5 and 250C, respectively. Breathing air was continuously bubbled
              through the suspensions for oxidation (redox potentials ranging from +500 mV to +600 mV).
              Nitrogen was bubbled through the reduced microcosms. Two milliliters of South Louisiana Crude oil
              (API Gravity 36.0) was added to each flask and allowed to homogenize for two weeks. South



                                                                  6











              Louisiana Crude was weathered in shallow open pans for four days (for removal of volatile
              hydrocarbons) prior to addition. Weathered loss was I I percent. The addition of weathered oil and
              allowing two weeks of equilibration in microcosms was to eliminate volatilization losses from the study
              which is directed at determining effects of heavy metal concentrations on hydrocarbon degradation.
              Twenty milliliters of each suspension was then removed and placed in Teflon tubes for extraction and
              analysis of hydrocarbons..
                    Next, 50 ml of Cr solution equivalent to 0, 250, 1000 and 5000 @Lg Cr per gram of sediment
              (dry weight) were added to separate flasks. Similarly, 50 ml of Ph solution equivalent to 0, 100, 500
              and 2500 gg added Pb per gram of dry sediment were added to an additional four flasks. Twenty
              milliliters of suspension were removed from the flask two days after metal additions for ICP analysis.
              Ten milliliters were taken for dry matter determinations. Subsequent aliquots were removed over a
              period of 91 days to determine changes in petroleum hydrocarbon levels.
                     Extraction for petroleum hydrocarbons (alkane fractions) was conducted by the addition of a
              solvent (1:1 hexane:acetone) to each 20 ml portion of suspension taken from the rnicrocosms. This
              mixture was shaken for 7 hours to facilitate extraction, The mixture was then centrifuged at 10,000
              rpm for 13 n-dn. to separate the solvent, microbial mat, water and sediment fractions. The top three
              fractions were decanted off into a separatory funnel and the sediment particulates washed -with solvent.
              The microbial mat was rinsed three times and the hydrocarbon laden solvent decanted off The
              decanted solvent was passed through pre-dried anhydrous sodium sulfate to remove water. The final
              solvent-hydrocarbon mix was evaporated down to 10 n-A under the fume hood. One n-d sample was
              placed into a vial and 20 gg mr' of internal standard added for GC/MS analysis.
                     The hydrocarbon analysis will be performed on a gas chromatograph (Hewlett Packard 5890
              Series II Plus) equippedwith an HP-5 high resolution capillary column (30 m, 0.25 prn fihn thickness,
              0.25 mrn i.d.) which will be directly interfaced to a quadrupole mass spectrometer (Hewlett Packard
              5972 Mass Selective Detector). The carrier gas helium of ultra high purity) flow-rate will be 1.0
              ml/min, the injector temperature will be 300 OC, the column temperature will be programed from 50 OC
              to 310 at 9OC/min rate with initial 3.0 min delay and 15.0 min hold at the end. The interface to the
              mass selective detector will be maintained at 280 OC. Injections will be made using a Hewlett Packard
              7673 automatic liquid sampler into a splitless injection port.
                     Hewlett Packard Vectra 486/66)CN4 computer system and Hewlett Packard G1034C Software
              for the MS ChemStation (DOS Series) was used in collecting and analyzirig data. G1033A NIST
              PBM Library was used for the peak identification. ASTM Crude Oil Quantitative Standard (Supelco,
              Inc., Bellefonte, PA) was used for the quantification and Sernivolative Internal Standard Mix (Supelco,
              Inc., Bellefonte, PA) was used as internal standard.
                     At the end of incubation, subsamples of sediment (oxidized and reduced) were removed from
              the microcosms with a syringe. The samples were extracted with NaOA, (pH 4.5) and the extracts
              were analyzed for metals using ICP procedures.
                      All data was subjected to analysis of variance and Duncan's Multiple Range Test (SAS 1995).
              Comparisons were made between two or more regression functions describing changes in percent
              hydrocarbon with time at Cr and Pb rates of 0, 250, 1000, 5000 and 0, 100, 500 and 2500 Ag/g,
              respectively. This analysis used the method of comparison of two or more linear functions (Neter et
              al., 1990).






                                                                 7











             2.4    Degradation of Petroleum Hydrocarbons in Sediment Receiving Produced Water
                    Discharge

                    Studies were also designed to determine (1) residual petroleum degradation, (2)
             degradation of applied South Louisiana Crude and (3) fertilizereffect on hydrocarbon degradation
             in sediment (oxidized and reduced) collected from a produced water discharge site. Sediment
             samples collected were homogenized and air-dried for 3 days. Total salts were calculated from
             electrical conductivity measurements and pH was measured with a combination electrode. Cation
             exchange capacity (CEC) measured the sum of exchangeable K, Na, Ca and Mg. Oil percent was
             determined by gravimetric methods following extraction with petroleum ether. Total petroleum
             hydrocarbon content (TPH) was determined by Freon-113 (1, 1, 2-trichloro-1, 2, 2-
             trifluoroethane) extraction. Twenty grams of wet sediment was extracted with 90 n-d of Freon-
             113 and compared with a calibrated standard to obtain total concentration. Sediment parameters
             and concentrations are summarized in Table 1.
                    Microcosms were also employed to study effects of sediment redox conditions on
             hydrocarbon degradation in sediment suspension (Patrick, et a]., 1973). Wet sediment from the
             point of discharge (0 m) was used in all microcosm experiments. Sediment suspensions were
             prepared in 2,000 " ErIenmeyer flasks by mixing 85 grams of wet homogenized sediment with
             1700 ml distilled water. Suspensions were constantly stiffed using a magnetic stirrer and purged
             with oxygen free nitrogen gas. A period of about two weeks was needed for microcosms to
             attain the desired reduced redox level before petroleum additions. Oxidized conditions were
             maintained by pumping air through the microcosms.
                    The redox control systems maintained sediment redox level within +20 mV of the desired
             potential. This was accomplished with platinum electrodes and a calomel reference electrode
             connected to a millivolt meter which monitored sediment redox potential. The output of the
             millivolt meter was connected to a meter relay which activated an air pump. When sediment
             redox dropped below the set point, a small amount of air was pumped into the apparatus in order
             to maintain the desired potential.

             2.4.1 Experiment I - Degradation of Residual Hydrocarbons

                    A microcosm study was designed to determine rate      of residual hydrocarbon loss from
             sediment collected from the discharge site. Six redox controlled microcosms were set up and
             divided into oxidizing (+450 mV) and reducing (-150 mV) sets. Sediment samples were removed
             at 1, 14, 30, 60 and 103 days and extracted for hydrocarbon components.

             2.4.2 Experiment 11 - Effect of Oxidizing Sediment Conditions on         Degradation of South
                    Louisiana Crude


                    Based upon the results from Exp. 1, a second laboratory study was initiated to determine
             degradation rates of hydrocarbon components of South Louisiana Crude oil added to oxidized
             sediment suspensions. Redox potential was controlled (+450 mV) in three microcosms followed
             by addition of 20 ml of South Louisiana Crude. At 1, 4, 7, 16 and 28 days after oil addition,
             sediment samples were removed and analyzed for hydrocarbon fractions and concentrations.




                                                            8









                   The oil used for this experiment was a low sulfur oil rich in light aromatics, paraff@ns and
            olefins. It is moderately toxic and has been shown to be degraded by indigenous microorganisms
            under aerobic sediment conditions.


            .2.4.3 Experiment III - Nutrient Influence on Hydrocarbon Degrad    ation

            This experiment determined the effects fertilizer and redox conditions had on hydrocarbon
            degradation. Nitrogen and phosphorus were added to. the 1700 n-d sediment slurries in the
            controlled redox microcosms. Four grams of NE4N03 and 2 g of K21HP04 was the high treatment
            and 2 g of NH4N03 and I g of K2HP04 was the low treatment. Twenty n-d of South Louisiana
            Crude oil was added to the controlled redox microcosms (+450 mV and -150 mV) and samples
            were removed at 1, 6, 10, 14, 28 and 42 days after fertilization. Sediment samples were analyzed
            for concentration of C-10 (decane) through C-17 (heptadecane) hydrocarbons. Treatments
            consisted of reduced and oxidized sediment conditions with two levels of fertilizer amendment
            and reduced and oxidized controls (oil only). Treatments were not replicated due to the limited
            number of available microcosm apparatus.
                   Extraction techniques followed EPA Method 8270 and were used for all three petroleum
            degradation experiments, A 20 ml sediment sample was removed from the redox controlled
            microcosm and pipetted into a Teflon tube. Ten H of 1: 1 hexane:acetone solvent was added and
            tubes were shaken for 7 hours followed by centrifugation at 10,000 rpm for 13 minutes. The
            petroleum laden solvent layer was transferred into a separatory funnel and the Teflon tube rinsed
            several times with the hexane:acetone solvent. Anhydrous sodium sulfate removed trace amounts
            of water and the petroleum laden solvent was evaporated to 10 " using dry nitrogen. Samples
            were stored at 50C until GC/MS analysis,could be performed. One n-d of each sample was
            transferred into a LoVial and 0.4 pl of an internal standard added. A Hewlett Packard 5890
            Series 11 plus GUMS was used for analyzing the samples for selected petroleum hydrocarbons. A
            HP-5 high resolution capillary column (30 m x .250 mrn i.d., 0.25 gm film thickness) was used
            and directly interfaced with a quadrapole mass spectrometer (HP 5972 Mass Selective Detector).
            The carrier gas (ultra high pure He) flow rate was 1.0 n-A rr@n-, injection temperature 3000C,
            column temperature programmed from 500C to 3 1 OOC at 80C min ' with an initial 3 minute delay
            and 15 minute hold time at the end. Sample injections were made using a HP 7673 automatic
            liquid sampler into a splitless injection port. A HP Vectra 486/66 computer system equipped with
            HP G1034C software and G1033A NIST PBM Library for the MS ChemStation was used for
            collecting and analyzing mass spectrometer results. Table 2 displays the hydrocarbons analyzed in
            this study. Not all fractions are discussed for each of the three laboratory experiments.
                    Hydrocarbon data were analyzed using the Statistical Analysis System (SAS 1995) to fit
            the simple linear regression model:
                                                      Y=Bo+Blx+E
            where Y and X represent the dependent and independent variables respectively (Freund and
            Wilson 1993). E is the random error term and slope is change in Y(hydrocarbon concentration)
            with respect to change in X(days), which is the degradation rate of selected petroleum
            hydrocarbons. Comparison between redox levels and other treatments utilized the General Linear
            Model and Post-Anova Duncan's Techniques of the SAS programs.





                                                              9














                                                             Table I


                                                   Sediment Characterization


              Location P            Na          K         Ca       Mg            A]       S          B

                          --- - --- - --- - - - - ----------               - --- - -------------- - ----- - - ------
              Outfall     208        24938      423       3217      584          0.4      171        28
              15 m,       335       2905        520       2843      1644         1.5      286        3


                          .Salts           TPH           Oil                     CEC            pH

                                         kg ---------- --                       meq 100 g-1
              Outfall     95260            66510         9.3                     130            6.9
              15m.        8300             2010          1.7                     42             6.7






                                                             Table 2


                                              Hydrocarbon Compounds Analyzed

              n-alkane          C#         Polycyclic aromatic hydrocarbons (PAH)
              decane            10         Naphthalene
              undecane          11         Acenaphthene
              dodecane          12         Fluorene
              tridecane         13         Phenanthrene
              tetradecane       14         Pyrene
              pentadecane       15         Benzo(a)anthracene
              hexadecane        16         Chrysene
              heptadecane       17         Benzo(b)fluoranthene
              octadecan.e       18         Benzo(a)pyrene
              eicosane          20         Benzo(k)fluoranthene
              tetracosane       24         Dibenzo(ah)anthracene
              octacosane        28         Benzo(g,hi)perylene
              dotriacotane,     32         Isoprenoids
              hexatriacotane    36         2, 6, 10 c-trimethyldodecane
                                           2, 6, 10, 14-tetramethylbeptadecane-pristane
                                           2, 6, 10, 14-tetramethylpentadecane-pristane








                                                                 10
















              3.0 RESULTS AND DISCUSSION


              3.1   Effect of Sediment Redox Conditions on Heavy Metal Chemistry

                    Metal kinetics are influenced by many factors. These factors include temperature, organic
              matter, surface activity of Fe and Mn compounds, microorganism species and other sediment
              characteristics. Since it is difficult to individually quantify the variables, in this investigation the
              factors were combined into one parameter - the rate constant of the assumed zero-order reaction,
              the so called pseudo-zero-order reaction model. In our discussion below, the pseudo-zero-order
              reaction model was used. When the: rate constant was positive, the reaction released constituents
              of metals into solution. When the rate constant was negative, the metals are removed from
              solution. When considering metals bound to organic matter and sulfide phase, we assumed that
              the formation of insoluble organic matter (complexation of insoluble, large molecular weight
              hurnic) (Gambrell and Patrick 1978, 1980) and sulfides were independent. At sediment Eh=-130
              mV, (the Eh where sulfate is reduced) and above the changes in metals in this fraction was
              attributed to insoluble, large molecular weight hurnic substances.

              Iron


                     Figure 2.1 shows the effect of sediment Eh (redox potential) on the content of Fe in the
              various chemical fractions. As Eh decreased, Fe(111) oxides were ri-@icrobialy reduced to soluble
              Fe(11), therefore increasing the soluble Fe concentration (K=42.5 mg/kg/d) in solution. When Eh
              further decreased to -130 mV, a reduction in exchangeable iron was observed which was
              attributed to sulfide formed as a result of sulfate reduction, precipitating dissolved Fe(H) to form
              insoluble FeS. Based on the fractionation data at all redox levels studied, dissolved Fe(Il) was
              also removed through Fe becoming associated with insoluble organic matter (primarily as a result
              of complexation of Fe with insoluble, large molecular humic material). The above two factors
              result in the reduction of soluble Fe concentration in solution (K=-25.8 mg/kg/d). The rate
              constants of the removal reactions for dissolved Fe(11) are 40.7 mg/kg1d and 31.4 mg/kg/d for the
              formation of sulfides and complexation of insoluble, large molecular humic, respectively.
                     Fe(III) oxides in the sediment were reduced to the more soluble Fe(R) during anaerobic
              incubation. Under reducing condition (Eh > -130 mV), the reduction of Fe(M) oxides occurred
              only by direct microbial reduction (K=-42.6 mglkg/d) involving organic carbon turnover. This
              part of Fe(I11) reduction was equivalent to approximately 2071 mg/kg (20% of total reducible
              Fe(Hl)). At sediment (Eh < -130 mV), Fe(III) reducing microorganisms can inhibit sulfate
              reduction by out competing sulfate reducers for electron donors (Lovley and Phillips, 1987). We
              assume that a portion of Fe(RI) reduction occurred by sulfides reducing Fe(HI) oxides. Only a
              small amount of the Fe(M) reduction at this redox level can occur by direct bacteria reduction
              involving organic carbon turnover (Jacobson, 1994). Accordingly, almost 8571 mg/kg (80% of
              total reducible Fe(111)) was reduced by the sulfide oxidation pathway (K=-171.5 mg/kg/d). The
              rate constant of indirected Fe(III) oxide reduction by sulfides is significantly greater than that by
              direct bacteria reduction. The rate constants of the pseudo-zero-order reaction are listed in Table
              3.
















                                                                  12500                                                                                     2000




                                                                  100oo-
                                                                                                                                                             1500                                 F I
                                                                                                             C)- -    0- -
                                                                                                    0-
                                                                    7500-                                       1                                                        -@!  ------ -            F2
                                                                  Ei                                                                                                     Do
                                                                                                                                                                         Ei
                                                                                                                                                                                    0  ----       F3
                                                                                                                                                             1000        .2
                                                                                                                                                                         M
                                                                  U 5000                                                                                                               ----       F4

                                                                                                                                                              500             --- ---             Soluble
                                                                    2500

                                                                                                               0. ......  ------
                                                                         0                .0                                                                       0
                                                                             0           1           20           30           40         50           60          T(day)
                                                                  (a)     430             0        -80              .130       -1,50            -170               Eh(mV)


                                                                        80                                                                                     10


                                                                                                                      IEH I

                                                                                                                    I
                                                                        60-                                                                                   7.5                                 F I
                                                                                         '0                                              EB
                                                                                                                                                                         . ........ 0  ........   F2

                                                                                                                                        -0       EB
                                                                    2i  40-                                                                                        3     _0            ----       F3
                                                                    0
                                                                    U
                                                                                                                                                                                       ----       F4
                                                                    U-                                                                            b
                                                                        20                                                                                    2.5             ---   ER ---        Soluble
                                                                                             ............ 0.,
                                                                                                                       0  ........ ........0

                                                                          0                                                                                        0
                                                                              0           10          20          30           40          50           60               T(day)
                                                                  (b) - 430                0        -80             -130         -150             -170                   Eh(MV)




                                  Figure 2.1                      The effect of Eh on the distribution of Fe in the chemical fi7actions (from
                                                                  Guo et al. 1997a).

                                   Figure 2.2                     The effect of Eh on the percentage of Fe in the various chemical fractions
                                                                  (from Guo et al. 1997a).








                                                                                                                               12












                                                            Table 3


                   The Rate Constants K (mg/kg/d) of the Pseudo-Zero-Order Reaction Involving Fe

                                          soluble        F2             F3             F4


             KI (direct microbial
               reduction)                 42.5           -17.5          42.6           31.4

             K2 (indirect reduction
               by sulfide)                -25.8          124.1          -171.5         72.1


                   Figure 2.2 shows percentage distribution of Fe found in the various chemical fractions.
             During anaerobic incubation approximately half of the reduced Fe(III) was converted to sulfide
             bound Fe(II). The remaining half of the reduced Fe(III) was converted to carbonate bound
             Fe(II). Under oxidizing sediment condition Fe(IH) oxide predominated with Fe behavior was
             controlled by Fe(111) oxides. Under reducing sediment conditions, sulfide and insoluble large
             molecular humic bound Fe(111) was the dominant fraction controlling iron behavior.

             Lead


                    Figure 3.1 shows the effect of sediment Eh on the actual distribution content of Pb in the
             various chemical fractions. As Eh decreased Fe(III) and Mn(IV) oxides were reduced and
             released into solution. Adsorbed Pb decreased (K=- 1. 1 mg/kg/d) with a significant portion of the
             released Pb going into solution (K=17 mglkgld). Continued decrease in Eh resulted in dissolved
             Pb concentration decreases (K=-47 mg/kg/d) as a result of the formation of insoluble lead
             associated with sulfides (K=1.72 mg/kg/d), insoluble complexes of insoluble large molecular
             hun-iic material (K=O. 17 mg/kg/d) and carbonates. As a result of the above processes, most of the
             Pb released by Fe(III) and Mn(IV) reduction was apparently converted to lead sulfide.
                    Figure 3.2 shows the effect of Eh on the percentage of Pb in the various chemical
             fractions. Under oxidizing conditions, Pb was bound to Fe(HI) and Mn( M. oxides. Pb behavior
             in the sediment was apparently controlled by chemical adsorption on Fe(M) and Mn(M oxides.
             Under reducing sediment conditions, Pb behavior was also governed by sediment carbonate and
             sulfide since lead was found in both the carbonate and sulfide fractions.


             Nickel


                    Figure 4.1 shows the effect of Eh on the content of Ni in solution and changes among the
             fraction over the redox range studied. When sediment Eh decreased, Fe(M) and Mn(M oxides
             were reduced to soluble Fe(H) and Mn(II). The Ni adsorbed on Fe(M) and Mn(M oxides
             decreased (K=-3.2 mg/kg/d) resulting in the release of Ni into solution (K=1.5 mg/kg/d). When
             sediment Eh decreased further, dissolved Ni concentration decreases (K=-1.6 mg/kg/d) may be
             attributed to the formation of nickel bound to carbonates (K=3.2 mg/kg/d), sulfides



                                                             13












                                         150                                                3.


                                                                o.

                                                                                          2.5
                                         100

                                       a                                                                  ....... F2
                                                                                               C60
                                                                                              Ei
                                                                                                        0 ----  F3
                                       0
                                       U                                      ID "/,<)
                                                                                               0
                                         50                                   EB                          ----  F4

                                                                                   EB     1.5        --- E9 --- Soluble




                                           0
                                            0      10      20    30      40    50     60      T(day)
                                       (a) 430     0      -80      -130 -150      -170        Eh(mV)


                                         60                                               ).4
                                                                   @o
                                                           0'


                                         50

                                                                                          1.2                 F 1
                                         40-
                                                                                                   ........ ........ F2


                                         30                                                 1           ----  F3
                                       0
                                       U                                         "0
                                       -a                                       11             o
                                                                                                              F4
                                         20-
                                                                          Eb
                                                                                                   ---EEI--- Soluble
                                                                                          0.8

                                         10


                                          0                                               0.6
                                            0      10     20     30      40    50     60         T(day)
                                       N   430     0      -80      -130 -150     -170             Eh(mV)





                  Figure 3.1           The effect of Eh on the distribution -of Pb in the chemical fractions (from
                                       Guo et al. 1997a).

                   Figure 3.2          The effect of Eh on the percentage of Pb in the various chemical fractions
                                       (from Guo et al. 1997a).





                                                                        14
















                                                       300                                                          80




                                                       250

                                                                                                                 -60                          F

                                                       200
                                                                                                                                              F2
                                                Ei              or
                                                       150-                                                       -40               0 ----    F3

                                                0
                                                U                                                                                     ----    F4
                                                7-     100     . .............                                                 --- EB ---     Soluble
                                                                                                                  -20

                                                       50



                                                       0                                                              0
                                                        0        10       20        30       40       so       60          T(day)
                                                (a)    430        0       -80         -130 -150         -170               Eh(mV)


                                                       60                                                           20



                                                       50-

                                                                                                                     15
                                                                          ER
                                                       40-                                                                                    Fl
                                                                                E8
                                                                                  I                                      t          0         F2
                                                                          @O



                                                       30-                                                        -10
                                                       0                                                   A
                                                       U                                                                 -6    ---- 0 ----    F3
                                                                                                                         CIO
                                                       z20      . .. .........                             10                  ---- A ----    F4

                                                       10                                                                      ---  EEI ---   Soluble


                                                       0 F-       I        1                                          0
                                                        0        10       20         30       40      50        60       T(day)
                                                (b)    430      0       -80           -130     -150       -170           Eh(mV)






                      Figure 4.1                The effect of Eh on the distribution of Ni in the chemical fractions (from
                                                Guo et al. 1997a).

                      Figure 4.2                The effect of Eh on the percentage of Ni in the various chemicaffractions
                                                (from Guo et al. 1997a).





                                                                                             15











              (K=1.1 mgtkg/d) and insoluble large molecular hurnic (K--1.1 mg/kg/d). Most of the nickel
              released is transformed into nickel bound to carbonates. A small percentage of the nickel released
              was bound to sulfides and large molecular weight hurnic compounds, making nickel less soluble.
                     Figure 4.2 shows the effect of Eh on the percentage of Ni in the various chemical
              fractions. Under oxidized sediment condition, Ni was bound to Fe(III) and Mn(M oxides.
              Under reducing sediment conditions, the Ni was mainly bound to carbonates. The Ni bound to
              insoluble sulfides only increased slowly as Eh sediment decreased to low levels suggesting that Ni
              was not strongly influenced by sulfide. Similar results have been reported by Griffin et al. (1989)
              for reducing sediment conditions. Ni behavior in sediment in this study was controlled primarily
              by the formation of nickel bound to carbonates.
              Barium Figure 5.1 shows the effect of sediment Eh on .levels of Ba in the various chemicay active
              fractions. Sediment Eh had little effect on dissolved Ba levels in the sediment, since Ba has only
              one valence state and Ba(II) has lower affinity to ferric and manganic oxides than other metals.
              Sediment Eh had little effect on dissolved Ba levels in the sediment since Ba has only one valence
              state. Ba(H) has a lower affinity than other metals to ferric and manganic oxides. As sediment Eh
              decreased the Ba bound to sulfides and insoluble large molecular hurnic fraction did decrease. We
              know that at Eh>-130 mV no sulfide exists. The only possible explanation is that as Eh
              decreased, the Ba bound to insoluble, large molecular hurnic material also decreased. This
              decreased Ba is converted to Ba bound to carbonates. The rate constant of the fon-nation of
              barium bound to carbonates is 0.91 mg/kg/d.
                     Figure 5.2 shows the effect of Eh on the percentage of Ba in the various chemical
              fractions.  It is obvious that under oxidizing conditions, Ba behavior was controlled by
              complexation of Ba with insoluble, large molecular humic compounds.               Under reducing
              conditions, Ba behavior was controlled primarily by Ba bound to carbonates.

              Copper

                     Figure 6.1 shows the effect of sediment Eh on the solubility and distribution of Cu in the
              various chemical fractions. As Eh decreased to 0 mV, dissolved Cu content increased (K=70
              mg/kg/d) apparently as the result of the dissolution of copper associated with Fe(IR) and Mn(IV)
              oxides and carbonates. Continued decrease in sediment Eh resulted further reduction in dissolved
              Cu level (K=-O. 16 mg/kg/d) attributed to the formation of the insoluble complexation of Cu with
              large molecular humic compounds (K=4.3 mg/kg/d) and copper bound to sulfides (K=0.6
              mg/kg/d) . Griffin et al. (1989) also reported that under reducing conditions, Cu behavior was
              controlled by sulfides. Under very reducing sediment conditions, Cu bound to carbonates was
              apparently converted to Cu bound to insoluble sulfides and large molecular humic compounds.
              Paralleling this sediment reduction, Cu bound to Fe(111) and Mn(1V) oxides also decreased
              slightly. The rate constants of the pseudo-zero-order reaction are -2.1 mg/kg/d and -0.67
              mg/kg/d for the dissolution of copper bound to carbonates and Fe(IH), Mn(IV) oxides
              respectively. Upon sediment reduction, Cu solubility decreased, thus reducing Cu toxicity,
                     Figure 6.2 shows the effect of sediment Eh on the percentage distribution of Cu in the
              various chemical fraction. Under oxidizing sediment conditions, copper was bound primarily to



                                                              16
















                                                         100-                                                     1.6




                                                         80 -                                                     1.4
                                                                                                                                             F I


                                                                                                                                   0         F2
                                                         E60-                                                   -1.2   I@i
                                                                                                    0                  to
                                                                                                                       Ei       ....0 ----   F3
                                                         C
                                                         0                                     V
                                                         40                                         0    M                            ----   F4


                                                                                                                               --- ES ---    Soluble
                                                         20         Y4 ... 0.9



                                                         0EP,                                                     0.6
                                                         0      10        20      30       40         50      60       T(day)
                                                         (a) 4300         -80         -130 -150         -170           Eh(mV)


                                                         60                                                            1
                                                                                                    EB

                                                         50-                                                      0.8
                                                                                                                            --13- F I

                                                         40                     0                                      . ........ 0....... F2

                                                                                                                 -0.6             0....    F3

                                                         30-                                                                               F4
                                                         CO

                                                                                                                            --- EB---      Soluble
                                                                                                          0     - 0.4
                                                         20



                                                         10                                                     +-0,2
                                                         0       io-      20       30       40        50        60       T(day)
                                                         (b) 430  0       -80        -130 -150            -170           Eh(mV)






                        Figure 5.1                       The effect of Eh on the distribution of Ba in the chemical fractions (from
                                                         Guo et al. 1997a).

                        Figure 5.2                       The effect of Eh on the percentage of Ba in the various chemical fractions
                                                         (from Guo et al. 1997a).






                                                                                          17

















                                                 400-                                                          4




                                                 300                                                                                  F I
                                                              IObr-) -----                                   -3

                                                                                                                       ...... . 0------ F2
                                             ES

                                             u   200                                                                   ----0  ----    F3
                                             C
                                             0                -0.
                                             U
                                                                                                                              ----    F4
                                             U                                                               -2
                                                 100                                                  133              --- EB---      Soluble

                                                                                         433
                                                                                          0..

                                                   0
                                                      0       10       20       30       40       50       60      T(day)
                                             (a)    430           0   -80          -130 -150         -170          Eh(mV)


                                                  80-                                                          0.8
                                                              IEB
                                                                                                               0.7

                                                  60                                                                                    F I
                                                                                                               0.6        ........0........ F2

                                                                                                                              0 ----    F3
                                                  40                                                           0.5
                                                 0
                                                 U
                                                 :3                                                                                     F4
                                                 U
                                                                                           0-.-B             - 0.4
                                                                                                , -z".,O                  --- E13---    Soluble
                                                  20-                                          1     ,
                                                                  ------                  -EBI          EB   - 0.3
                                                                                                      .-0

                                                    0                                                        - 0.2
                                                       0          10    20       30       40       50       60         T(day)
                                             N       430          0    -80          -130 -150        -170              Eh(mV)






                      Figure 6.1             The effect of Eh on the distribution of Cu in the chemical fractions (from
                                             Guo et al. 1997a).

                      Figure 6.2             The effect of Eh on the percentage of Cu in the various chemical fractions
                                             (from Guo et al. 1997a).






                                                                                       18











            carbonates and large molecular hurnic material. Under reducing sediment condition, Cu was
            found to be bound to a insoluble sulfides and to some extent humic compounds.


            Arsenic


                    Figure 7 shows the effect of Eh on the level of As in the water soluble chemical fraction. When
            Eh decreased to 0 mV, As(V) was reduced to As(M) (K7-0.21 mg/kg/d). At sediment Eh=O to -100
            mV, dissolved arsenic concentration was essentially zero. This may be due to the fact that the fresh
            AsM which was formed from As(V) reduction became insoluble.
                    Following manganic oxide and ferric oxide reduction, the As bound with these oxides
            decreased OCF-0.88 mg/kgtd). Similar results have been reported by McGeehan and Naylor, (1994).
            Parallel increases in As bound to insoluble large molecular humic compounds correlated with reduction
            of manganese and iron oxide. The rate constant of pseudo-zero-order reaction for the formation of As
            with insoluble large molecular humic substances was 0.97 mg/kg/d. There was no evidence to show
            that As associated with sulfides was formed.
                    At Eh levels between 430 mV to -130 mV, As bound to carbonates decreased (K=-0.51
            mglkg/d). Further decreases in Eh (< -130 mV) caused the As bound to carbonates to increase
            (K=0.59 mg/kg/d).
                    Figure 8 shows the effect of Eh on the percentage of As in the various chemical fractions. The
            dominant active As fraction is As bound to FqIII) and Mn(M oxides.

            Chromium


                    Cr fractions were also affected by sediment redox conditions (Figures 9 and 10). As Eh
            decreased to 0 mV, Fe(M) and Mn(M oxides in the sediment were reduced to more soluble Fe(II)
            and Mn(II) and the Cr adsorbed on Fe(E[I) and Mn(M oxides was apparently released increasing
            dissolved Cr concentration. At Eh<100 mV, soluble Cr(VI) was apparently reduced to insoluble
            Cr(M) (mostly as Cr(OH)3) (Masscheleyn et al. 1992). Cr(IH) also apparently reacted with organic
            matter to forrn dissolved Cr(rV)-organic complexes (Masscheleyn et al. 1992). The above three
            reactions controlled dissolved Cr concentration in the sediment. The combination of these three
            reactions resulted in little difference in dissolved Cr content being measured under the various redox
            conditions studied.
                    As sediment Eh decreased, Cr associated with Fe(M), Mn(M oxides decreased (K=-0.32
            mg/kgtd), while Cr associated with insoluble large molecular hurnic material increased (K=0.81 mg/kgI
            d). There was no evidence to show that any Cr associated with sulfides was formed.
                    Figure 10 shows the effect of Eh on the percentage of Cr in the various chemical fractions.
            Under oxidizing conditions, Cr associated primarily with Fe(IM and Mn(M oxides, with Cr activity
            being controlled by chemical adsorption of Cr on Fe(M) and MnWV) oxides. Under reducing soil
            conditions, Cr was bound to insoluble large molecular burnic substances.

            Cadmium


                    Fig. I I shows the effect of Eh on the levels of water soluble Cd and Cd in the various chenical
            fractions. As sediment Eh decreased, dissolved Cd decreased from 4.6 mg/kg to 0.3 mg/kg (K=-0.09
            mg/kg/d), and Cd associated vAth Fe(M) and Mn(M oxides also decreased (K=-0.01 mg/kg/d).



                                                               19










                                    200                                                             4



                                   150-                               'Ju..   -EEr                -3                         F I
                                                                                     0.%
                                ,a                                                      @..%,
                                I@i                                                        '13          'Q    ---0--- F2
                                                                                                        @O
                                   100 -                                                          -2                0----    F3


                                                                                                                     ----    F4


                                                                                                               --- EH ---    Soluble
                                     50






                                                                                                  -0
                                         0        10       20       30        40       50       60         T(day)

                                       430         0      -80         -130 -150           -170              Eh(mV)



                                   800                                                              15



                                  600-           10"                                                                          F I
                                                                                                    10
                                                                              10.-0... EB                                     F2

                                  400 -E 3                                                                            ----    F3

                                                                                                            0
                                                                                                                      ----    F4


                                   200-                                                                            -E9- - - Soluble

                                                                                           0



                                      0                                                               0
                                        0        10       20        30        40      so        60      T(day)


                                       430        0      -80         -130     -150         -170         Eh(mV)
                   Figure 7.           The effect of Eh on the distribution of As in the chemical fractions (from
                                       Guo et al. 1997b).
                  Figure 8.            The effect of Eh on the percentage (expressed as g/kg) of As in the various
                                       chemical fractions (from Guo et al. 1997b).






                                                                              20










                                    100                                                         0.65


                                    75-                                                           0.6                       FI
                                                                      0,    C@
                                                                                       "0                                   F2
                                                 or                                              0.55
                                bo
                                                                                 "Cor
                                                                                 "1                                0----    F3
                                    50

                                0
                                U                                                   EQ            0.5                       F4

                                U
                                                                                                                   EE---    Soluble


                                                                      '0
                                    25-                                                          0.45


                                          0 41                                                     0.4
                                          0      10       20        30      40       50       60        T(day)
                                          430     0       -80         -130  -150        7170            Eh(mV)



                                    600                                                           4

                                                                                     ----A

                                    500 -
                                                          0-,                                    3.5
                                                                                                                            F I

                                    400
                                                                         ... OL..                                           F2
                                                                                         0

                                CIO
                               -@4                                                                 3                 ----   F3
                                    300                                                                :9
                                                                                                       E
                                                                                                       0
                                    200-                                                                      ---- A  ----  F4
                                                                                                              ---  E13- - - Soluble
                                             Z,                                                   2.5
                                                                             -0-
                                    100               \0
                                                                V,
                                          0-1                                 .......................... . .1-- 12
                                          0       10      20        30      40       50       60      T(day)


                                          430     0       -80         -130   -150         -170          Eh(mV)

                    Figure 9.             The effect of Eh on the distribution of Cr in the chemical fractions (from
                                          Guo et al. 1997b).

                     Figure 10.           The effect of Eh on the percentage (expressed as g/kg) of Cr in the various
                                          chemical fractions (from Guo et al. 1997b).







                                                                             21










                                     12.5-                                                          5
                                           E 3,

                                      10-         EB                                                4



                                 to                                                                                        F I
                                 G    7.5-                                                          -3
                                                                                                        EI                 F2
                                 0
                                        5             ------ 0.
                                                                                                    2            0----     F3
                                                                                                        Cn
                                      2.5-                                                                                 F4
                                                                        EQ %%                               --- EB---      Soluble
                                                                  A-----& "In, @
                                        0                                                           -0
                                           0      10        20      30       40       50         60      T(day)
                                           430     0        -80        -130      -150 -170               Eh(mV)




                                      600-                                                          250


                                      500-                                                          -200
                                                                                                                                   F I
                                      400               %  %%                                       150       z            ------  F 2
                                to
                               -'A    300                   Ct                                                            0----    F3

                                                                                                    100        6           ----    F4
                                                                                            A                 LO
                                      200-
                                                                                                                           ---     Soluble

                                                                                                      so
                                      100-


                                                                              %ER
                                           0                                                            0
                                           0       10       20       30       40       50        60     T(day)

                                           430      0       -80       -130     -150        -170          Eh(mV)



                      Figure 11.           The effect of Eh on the distribution of Cd in the chemical fractions (from
                                           Guo et al. 1997b).

                      Figure 12.           The effect of Eh on the percentage (expressed as g/kg) of Cd in the various
                                           chemical fractions (from Guo et al. 1997b).
                                                            0.-
                                                                                         /&























                                                                              22











              In contrast Cd associated with carbonates QC==0.01 mg/kg/d), and Cd associated with insoluble large
              molecular hurnic substances and sulfides increased as Eh decreased. The rate constants of pseudo-
              zero-order reaction on the formation of Cd associated with insoluble sulfides and large molecular
              humic material were 0.16 mg/kg/d and 0.01 mg/kg/d respectively. These results are similar to the
              findings of Kerner and Wallman (1992) for Cd associated with dissolved and sulfide forms.
                    Fig. 12 shows the effect of Eh on the percentage of Cd in the water soluble and chemical
              fi-actions. Under oxidizing sediment conditions, Cd was associated with Fe(P and MnqV) oxides,
              carbonates, and soluble phase Cd. Soluble Cd accounted for 230 g/kg of the total concentration under
              oxidized conditions. Under reducing sediment conditions, Cd bound to the carbonates fi-action
              accounted for most of the Cd while water soluble Cd accounted for only 15 g/kg of total Cd
              concentration. As Eh decreased, the decreased Cd associated with Fe(Ell) and N4nM oxides and
              soluble phases was transformed into Cd associated with insoluble carbonates and sulfides.

              Zinc


                    Fig. 13 shows the effect of sediment Eh on the distribution of Zn in the water soluble and
              chemical fi7actions. As Eh decreased, dissolved Zn decreased from 100 mg/kg to 0.8 mg/kg OC=-1.78
              mg/kg/d, Fig. 14), Zn associated with Fe(III) and Mn(M oxides also decreased (K=-6.5 mg/kg1d). In
              contras;t, Zn associated with carbonates (K=3.3 mglkg/d) and Zn associated with insoluble large
              molecular humic substances and sulfides increased as sediment Eh decreased. The rate constants of the
              pseudo-zero-order reaction for the formation of Zn associated -,krith insoluble sulfides and large
              molecular hurnic material were 5.4 mg/kg/d and 2.9 mg/kgId respectively. These results are similar to
              that reported by Kerner and WaHman (1992) who determined Zn existed primarily in dissolved and
              sulfide forms.
                     Fig. 14 shows the effect of sediment Eh on the percentage distribution of Zn in the various
              fractions. Under oxidizing conditions, Zn was associated with Fe(IH) and Mn(M oxides and soluble
              phases. Soluble Zn accounted for 140 g/kg of total content of all fractions. Under reducing
              conditions, Zn was found to be associated with insoluble sulfide, large molecular hurnic compounds
              and carbonates. Soluble Zn accounted for I g/kg of the total content found in the fi-actions. As
              sediment Eh decreased, the Zn associated with Fe(M) and MhM oxides and soluble phases was
              transformed into Zn fractions associated with insoluble carbonates, sulfide and large molecular humic
              compounds. The data collected show that Zn becomes less mobile under reducing sediment
              conditions.


              3.2    Radium Chemistry

                     Selective extraction of wastepit and Humb    le Canal sediment exposed to produced water
              showed that greater than 95% of the 226Ra could be detected only in the residual fractions (Figure
              15 and 16). Only a small amount of 226Ra activity was detected in exchangeable or carbonate
              fractions that would indicate the presence of more readily available forms of radium. The
              extraction data suggest that 226Ra solubility may be controlled by the mineral phase. Due to the
              large ionic radius of radium, it is unlikely that 226Ra is incorporated within the clay lattice of the
              sediment.






                                                               23








                                     500                                                           125



                                     400                                                           100
                                            %                                                                                F I
                                              %%                .0
                                                 % 0 ...... <y-, , 1.                     A
                                                                    1.                                                       F2
                               tl@   300-          EH                                              75
                               C4                    %
                               G                     %%%                                                  Ei   ---- 0----    F3
                                                                                      Y.
                                                                             ,A,,,7Z                      `
                                                                       0
                               C
                               0     200-                                                          so                        F4

                                                                                                               --- EB---     Soluble
                                     100 4                                %%              0        25
                                                                             %


                                        0                                                            0
                                          0        10      20       30       40      50       60        T(day)
                                          430        0   -80         -130   -150         -170           Eh(mV)



                                     600                                                           150



                                     500-
                                                           01...
                                              %                                     0
                                               %                                                                             F1
                                                % '01"
                                     400-         % E9                                           -loo                        F2
                                                     %%
                                     300-               %                                                          0         F3
                                                                                          0
                                                           EH *I-I                                                 A ----    R
                                                                                                          0
                                     200-                                                          50     V)    ---
                                                                             -0.,.                                 EEI--- Soluble

                                     100                                   %



                                        0                                                            0
                                          0        10      20       30      40       50       60       T(day)
                                        430        0     -80        -130     -150        -170         Eh(mV)


                      Figure 13.          The effect of Eh on the distribution of Zn in the chemical fractions (from
                                          Guo et al. 1997b).

                      Figure 14.          The effect of Eh on the percentage (expressed as g/kg) of Zn in the various
                                          chemical fractions (from Guo et al. 1997b).






                                                                               24










                                                       Bayou sediment
                          H20                               AEROBIC (+600 mV)
                         EXCH                               ANAEROBIC (-250 mV)



                         CARB



                       REDUCE



                        ORG/S


                        RESID -                          AMR-

                              0          50           100    600         800
                                       22'Ra Activity (pCilgram)


                                                      Waste pit sediment
                           HO                            [ED AEROBIC (+600 mV)
                                                             ANAEROBIC (-250 mV)
                         EXCH



                         CARB



                        REDUCE



                         ORG/S



                         RESID



                               0          50          100    8010        1000
                                        226Ra Activity (pCilgram)

             Figure 15.    226 Ra activity in various chemical fractions in Humble Canal sediment
                           incubated under aerobic and anaerobic conditions.

             Figure 16.    "'Ra activity in various chen-dcal of waste pit sediment incubation under
                           aerobic and anaerobic conditions.





                                                     25











                      The co-precipitation with other minerals such as barite, gypsum and anhydrite has been
              reported (Langmuir and Melchior 1995). The presence of elevated levels of barite in the sediment
              would suggest that precipitation with barite would be the most likely sink for 226Ra as indicated by
              the detection of 226Ra only in the residue.

              3-3     Effect of Heavy Metal on Petroleum Hydrocarbon Degradation

                      Water soluble plus exchangeable Cr and Pb concentrations are shown in Table 4. The majority
              of the added metal was sequestered or precipitated by other sediment fractions. Only under reducing
              sediment conditions were significant water soluble plus exchangeable metal concentrations observed.
              At 5,000 mg/kg added Cr only 145 mg/kg remained in the water soluble plus extractable phase. At
              2,500 mg/kg added Pb, 183 mg/kg remained in the more bioavailable water soluble plus exchangeable
              fraction.
                      Figure 17 depicts changes in total hydrocarbon concentration (alkane fractions) under oxidized
              and reduced conditions. The data shows that total hydrocarbon concentration decreased with time in
              all treatments. Total hydrocarbons were greater in suspensions treated with 1000 mg/kg Cr compared
              to suspensions receiving no Cr. Sediment suspensions treated with 5000 mg/kg Cr had higher
              hydrocarbon concentrations remaining than suspensions that received 1000 mg/kg Cr. Since the actual
              amounts of hydrocarbons varied for the oxidized and reduced suspensions, comparisons are difficult to
              make. It was evident that total hydrocarbon concentration measured at the end of the anaerobic
              incubation of suspensions treated with higher Cr levels was greater than the lower Cr treatments.

                                                             Table 4


                                       Water Soluble Plus Exchangeable Chromium and
                                  Lead Concentrations in Oxidized and Reduced Suspensions

              Treatment                                       Amount found
              (mg/kg)                                         (mg/kg)
              Cr                      Oxidized                                        Reduced
              0                          0.59                                             0.99
              250                        1.50                                           22.60
              1000                       2.44                                           61.60
              5000                      32.52                                          145.40


              Pb


              0                         3.85                                              5.90
              100                       4.08                                            16.40
              500                       4.40                                            40.30
              2500                     11.46                                            183.20









                                                                26






                   800                  0 M@kg Cr                         keduced
                                        250 mgtkg Cr
               a                        1000 mgtkg Cr
                   600                    00 mgtkg Cr


                                              Oxidized


                   400





                   200






                        0     20      40    6 0    80 100           0      20     40     60     80 100

                                    Time (days)                          Time (days)


                      500 r       I
                                           0 mgfkgPb                     Reduced
                      400                  100 mgfkg Pb
                                           500 mg(kg Pb
               9                           2500 mglkgPb
               W
               U      300
                                              Oxidized



                      200



                      100




                         0
                           0     20     40     60     80 100         0     20     40     60     80 100
                                          Time (days)                              Time (days)
             Figure 17.     Chron-@iurn and lead effects on total hydrocarbon degradation in oxidized
                            and reduced sediment suspensions (from DeLaune et al. 1998).




                                                        27











                       The change in total hydrocarbon degraded (percent) provides some information on treatment
                effects (Figure 18, Table 5). Little difference in petroleum hydrocarbon degradation existed between 0
                and the 1000 mg/kg Cr treatment levels. However at 5000 mg/kg Cr, percent total hydrocarbon
                remaining was ligher compared to the other treatments, thus showing reduced degradation of the total
                hydrocarbon fractions. The difference was not statistically significant.
                       In the case of the Pb treated sediment suspensions, data (Figure 18, Table 6) shows that under

                kg Pb rates after the third sampling. However, under reducing conditions, remaining hydrocarbons
                oxidized conditions 50 to 601/6 of the added hydrocarbons were still present for the 500 and 2500 mg/

                were even higher (50-801/6) after the third sampling date. This shows that total hydrocarbon
                degradation rates were slower compared to oxidized treatments. At the end of the oxidation
                incubation the highest total remaining hydrocarbon percentage in the Pb treatments was around 10%.
                Total remaining hydrocarbons measured in the Pb treated suspensions under reduced conditions ranged
                from 10 to 55%. The percent degraded (Table 6) shows very little treatment effect. However, unlike
                the Cr treatments, there was a much larger difference between the percent degraded during the
                oxidation and reduction phases for all Pb treatment levels.

                                                                Table 5


                 Chromium and Lead Effect on Total Hydrocarbon Degradation (total of all alkane fractions) as
                           Affected by Oxidized and Reduced Soil Suspensions (91 days of incubation)

                Degradation Rate (mg/kg soil/day)
                Treatment           Oxidized            Duncan               Reduced             Duncan
                (mg/kg)                                 Grouping                                 Grouping

                Chromium
                0                   3.65                A                    2.49                A
                250                 5.28                A                    2.40                A
                1000                7.18                A                    3.20                A
                5000                4.62                A                    1.54                A


                Lead
                0                   3.68                A                    1.68                A.
                100                 3.69                A                    2.96                A
                500                 3.20                A                    2.22                A
                2500                3.69                A                    1.60                A


                Note: Means in columns followed by the same letter are not significantly different.

                        The differences observed may be explained by examining the observed degradation rates (Table
                5). Petroleum hydrocarbon degradation in the oxidized suspensions was faster than that measured
                under reducing conditions. The disparity was observed in all concentration rates in the individual
                flasks.






                                                                    28









                                 O.UgIg Cr
                                 250 pglg Cr
           100 -                                                        Reduced
                                 1000 jig/g Cr
                                 500 #g1g Cr
            80, -

                                        Oxidized
            60



            40


           U
           'W' 20


               0
                0     20    40     60     80 100            0     20    40    60     80 100
                              Time (days)                                 Time (days)




                                   Oxidized                             Reduced
            0100
           .0                          0 pglg Pb
                                       100pg1g Pb
            0
            t-                         500 pg/kg Pb
                80
                                       2500 pg/g Pb

            0   60


            U
                40 -



                20 -



                 0
                   0      20   40     60     80 100         0     20    40     60    80 100
                                 Time (days)                            Time (days)
              Figure 18.    Chrornium and lead treatments effects on changes in total petroleum
                            hydrocarbon (percent) in oxidized and reduced sediment suspensions
                            during 91 days of incubation (from DeLaune et al. 1998).




                                                     29











               Effect of Cr and Pb on Deuadation of Individual Hydrocarbon Fractions in Oxidized and Reduced
               Sediment Suspension

                      Eleven hydrocarbon fractions were quantified but three (pentadecane, hexadecane, and
               octadecane) were individually graphed for analysis of degradation under both oxidized and reduced
               conditions. Since the effects of treatments on the total hydrocarbon degradation result from the
               degradation rates of its individual components, the percent of each fraction is graphically presented in
               Figure 19.
                      The results show that under both oxidized and reduced environments the low molecular weight
               hydrocarbons tend to disappear much faster than heavier hydrocarbons. In generaL the degradation of
               the three hydrocarbon fractions decreased as Cr treatment increased.
                      Under oxidized conditions, the percent of the three individual hydrocarbons in Pb treated
               suspensions decreased quite rapidly with time (Figure 20). Under reduced conditions, less than 20% of
               the original hydrocarbon fraction remained. But there were no visible treatment trends observed from
               this set of data. However, it must be noted that much larger fractions of the original concentrations
               were present at the termination of the study.


                                                              Table 6


                   Effect of Chromium and Lead Treatments on the Percent Total Petroleum Hydrocarbons
                           Degraded (after 91 days) in Oxidized and Reduced Sediment Suspensions

               Compound                 Treatment Rate          Oxidized                Reduced
                                        (mg/kg)                                 %

               Chromium                 0                       82.88                   79.83


                                        250                     88.84                   64.17


                                        1000                    80.48                   78.12


                                        5000                    66.56                   40.43


               Lead                     0                       89.20                   50.85


                                        100                     83.48                   95.51


                                        500                     91.69                   66.74


                                        2500                    89.52                   42.68



                       Following a statistical analysis of Cr. and Pb on the degradation (percent) of three selected
               hydrocarbon fractions (pentadecane, hexadecane and octadecarie), we could only show a significant
               difference of Cr on octadecane degradation. Chromium only sh    owed degradation under reducing



                                                                  30















                             Oxidized                                           Reduced


                100                                                     100

                 80  -
                                                                        80  -
            Cd
            C)   60  -
            CU                                                          60  -
            10                                                    Cd
                 40
                                                                        40

                 20
                                                                        20
                   0                                                        0



                100  -                                                  100


                 80  -                                                  80

                                                                  Cd
                 60  -                                                  60
                                                                  Cl

                 40  -
                                                                        40  -


                 20  -                                                  20  -


                   0                                                        0



                120  -                                                  120

                100                                                     100

                 80  -                                                  80

            0    60  -                                            0     60  -

                 40                                                     40  -


                 20                                                     20


                   0                                                        0
                     0    20     40     60     80     100                   0    20     40     60     80     100
                               Time (days)                                             Tune (days)


               Figure 19.     Effect of chromium on changes in percent of hydrocarbon degraded in
                              oxidized and reduced sediment suspensions receiving 0 mglkg (0), 250
                              mg/kg (0), 1000 mg/kg (V) and 5000 mg/kg (A) Cr added (from DeLaune
                              et al. 1998).




                                                          31








                       %Octadecane   %Hcxadecane    %Pentade


                     K) IN 0)  co C) K) a)  C"0
                       0 0  CD0   0 0   0 0  0
           CD          1
           .C)


                  0

        CD
        Q


           C)

                Cl.
          CD @3*w
          1:4w
        <


           C,
          (D      co
           zs

           CD


          CD      0
          :z blZI 0
   w      4- CD
        m 011
           0


           0                                       %Pentadecaj
                       %Octadecane   %]Efexadecane

        CL
        CL             4- cr)  co0         w 0         C)
        0  0                        0 0 C 0  0
        CL 00


        0
          1@

           (D




        CD        0
        CD      m

           o

           cl.
           rq
        00
                  00











              conditions at 5,000 mg/kg added Cr. There were no significant differences in degradation as influenced
              by metal content for the oxidized treatments (cv-- 0.05). The slope of octadecane degradation of the
              reduced 5000 mglkg Cr treatment was significantly different than the 0 and 250 mg/kg Cr treatments
              (a7- 0.05). There was no statistical influence of Cr and Pb on degradation of pentadecane and
              hexadecane.
                    Chromium and Pb at the levels used in this study had no significant impact on degradation of
              South Louisiana Crude oil. The Cr and Pb added was bound by the sediment into insoluble or
              unavailable forms. Results suggest that heavy metals would not influence degradation of petroleum
              hydrocarbon in sediment at the produced water discharge site. Data presented should not be
              extrapoled to sites containing sandy substrates in which heavy metals were not sequestered or removed
              from the solution or exchangeable fractions.

              3.4    Degradation of Petroleum Hydrocarbons in Sediment Receiving Produced Water
                     Discharge

              3.4.1  Degradation of Residual Hydrocarbons (Exp. I

                     Initial residual sediment concentrations of hexadecane, heptadecane, eicosane,
              tetradecane, tridecane and hexatriacotane in the oxidized and reduced nidcrocosms were similar
              and averaged (6 replications) 88.4, 87.5, 65.5, 50.3, 28.6, 1.6 pg/g dry sediment, respectively.
              (Figs. 21 and 22). Hgh concentrations (day 1) of octadecane (82. 1), pentadecane (78.0) and 2, 6,
              10, 14 tetramethylpentadecane (70.5 pg/g) were also measured but not graphed.                   Initial
              concentrations of tetracosane and the remaining isoprenoids ranged from about 20 to 35 pg/g and
              decane, undecane, dodecane and dotriacotane concentrations were less than 10 Pg/g. At the end
              of the study (103 days), initial concentrations of residual hexadecane, heptadecane, eicosane,
              tetradecane and tridecane were reduced an average of 87% under oxidized sediment conditions
              compared to only 54% reduction under reducing conditions. Hexatricotane concentrations were
              reduced only 41% under oxidizing conditions and no change in concentration was measured under
              reduced sediment conditions. Remaining hydrocarbons investigated (not graphed) averaged 77%
              reduction under oxidizing conditions and 44% reduction under reducing conditions over the 103
              day experiment.
                     Degradation rates were faster under oxidizing conditions (Fig. 21) compared to a reducing
              environment (Fig. 22). All other alkanes analyzed (see Table 2) displayed similar rates of
              degradation. Degradation rates under oxidized sediment conditions ranged from a low of 0.029
              (decane) to a high of 0.721 pg/g/d for hexadecane.             Higher degradation rates (oxidized
              conditions) were also observed for tetradecane, pentadecane, heptadecane, octadecane, eicosane
              and 2, 6, 10, 14 tetramethyl pentadecane (Table 7). Degradation of residual hydrocarbons under
              controlled reducing conditions was slower.         Rates ranged from 0.012 (decane) to 0.351
              (hexadecane) pg/g/d. Degradation rates (reducing conditions) of all investigated hydrocarbon
              fractions averaged 58% (ranged from 30 to 96%) slower compared to corresponding rates
              measured under oxidizing conditions (Table 7).
                      Significant differences in degradation rates of hydrocarbon fractions were observed as
              affected by sediment redox conditions. All petroleum fractions displayed a significantly (P<0.05)
              greater loss from the oxidized treatment compared to the reduced treatment.




                                                                33












                                                100


                                                80
                                         Z                                                                          Tridecane
                                                                                                                    Tetradecane
                                                60    --                                                            Hexadecane
                                                                                                                    Heptadecane
                                                40                                                                  Eicosane
                                         Z
                                         @4                                                                         Hexatriacontane
                                         U      20
                                         Z

                                                                                Q
                                                   0                             1           f -           I
                                                      1           14           3.0          60          103

                                                                            DAYS



                                         Figure 2 1.   Change in selected hydrocarbon fraction writh.time under oxidized conditions.












                                       100   -


                                        80
                                z                                                                            Tridecane
                                        60                                                                   Tetradecane
                                                                                                         A Hexadecane
                                        40                                                               x Heptadecane
                                                                                                         a Eicosane
                                                                                                      I --*-Hexatriac@ @ane
                                        20
                                z
                                          0
                                             1           14           30           60          103

                                                                   DAYS



                                  Figure 22.    Change in selected hydrocarbon fractions with time under reduced conditions.











                                                         Table 7


                          Degradation of Residual Hydrocarbons in Produced Water Sediment

            Compound                                Oxidized Rate             Reduced Rate
                                                    (pg/g/d)                  (pg/g/d)
            decane                                  0.029                     0.012
            undecane                                0.050                     0,022
            dodecane,                               0.128                     0.070
            tridecane                               0.294                     0.150
            tetradecane                             0.449                     0.235
            pentadecane,                            0.649                     0.340
            hexadecane                              0.721                     0.351
            heptadecane                             0.715                     0.326
            octadecane                              0.620                     0.175
            eicosane                                0.533                     0.237
            tetracosane                             0.279                     0.058
            octacosane                              0.106                     0.014
            dotriacontane                           0.067                     0.022
            Hexatriacontane                         0.18                      0.006
            2, 6, 10trimethyl-dodcane               0.153                     0.075
            2, 6, 10, 14tetramethyl heptadecane     0.253                     0.149
           -2, 6, 10, 14tetramethyl pentadecane     0.400                     0.281

























                                                             36











           3.4.2 Effect of Oxidized Sediment Conditions on Dep-radation of South Louisiana Crude (Exp.
                   M

                   Degradation of selected South Louisiana Crude hydrocarbons under controfled redox
           conditions (+450 mV) is graphed in Figure 23. Initial concentrations (day 1) of tridecane,
           dodecane, undecane, dotricotane, phenanthrene and pyrene were 299.4, 292.6, 182.7, 25.0, 9.3
           and 0.6 pg/g, respectively. Initial concentrations of remaining hydrocarbons analyzed (not
           graphed) ranged from 66.9 (octacosane) to a high of 240.5 Pg1g for octadecane. Starting
           concentrations of heptadecane, hexadecane and pentadecane averaged 195.1 [tg/g dry sediment.
           After 28 days of laboratory incubation, initial concentrations of undecane, dodecane and tridecane
           were reduced an average of 81% with the largest reduction (96%) observed for the shortest n-
           alkane (undecane, C-11). Dotriacotane and ph6nanthrene concentrations were reduced 51.5%
           and pyrene 28% under oxidizing conditions.
                   Degradation rates of shorter n-alkanes; undecane (3.01), dodecane (4.41) and tridecane
           (3.58 pg/g/d) were much faster than the longer n-alkane; dotriacotane (0.20) and polycyclic
           aromatic hydrocarbons; phenanthrene (0.09) and pyrene (0.002 pg/g/d).              Degradation of
           tetradecane (2.62), pentadecane (2.12), hexadecane (1.71), heptadecane (0.89), octadecane
           (2.18), eisocane (1.80), tetracosane (0.86), octacosane (0.61) and naphthalene (0.22 pg/g/d) are
           not graphed in Figure 23. All compounds investigated showed significant (P<0.05) degradation
           over the 28 day study except pyrene (P=0.233).

           3.4.3 Nutrient Influence on Llydrocarbon Degradation (Exp. 111).

                   Linear regression degradation rates for undecane, tridecane, pentadecane and heptadecane
           as affected by redox and fertilizer are graphed in Figure 24. A general overview shows
           degradation rates in oxidized sediments amended with fertilizer were much higher (except
           undecane) compared to the reducing sediment treatments. Hghest degradation rates were
           observed for tridecane, pentadecane and heptadecane (4.4 to 5.1 pg/g/d) in sediments amended
           with the high rate of fertilizer. Undecane's highest, degradation rate occurred in reduced sediment
           plus high fertilizer (3.9 pg/g/d). In most cases, hydrocarbon degradation rates decreased as level
           of fertilizer decreased and lowest rates were observed for the control treatments (oil only). Under
           reducing conditions, many treatments showed an increase (production) in tridecane, pentadecane
           and heptadecane over the 42 day experiment (Fig. 24). Net production rates ranged from 0. 1
           (tridecane) to 0.6 (pentadecane) pg/g/d. An increase in sediment heptadecane concentration was
           also observed for the oxidized control (0.2 pg/g/d). The observed net increases were thought to
           be due to faster production rates from higher molecular weight compounds compared to slower
           degradation rates of the hydrocarbons.
                   Degradation and production rates of decane, dodecane, tetradecane and hexadecane (not
           graphed) followed the same general distribution as undecane, tridecane, pentadecane and
           heptadecane. High degradation rates were calculated for dodecane, tetradecane and hexadecane
           (4.6 to 5.0 gg/g/d) in oxidized sediment amended with high fertilization. Net production of
           dodecane, tetradecane and hexadecane (0.3 to 0.5 pg/g/d) was observed in some reduced
           sediment treatments.
                   Averaged over the eight hydrocarbons (C-10 through C-17) degradation rates (net
           production included) for the control, low and high fertilization (oxidizing conditions) were 1.0,



                                                            37












                               350

                               300
                               250                                                                   Undecane
                                                                                                     Dodecane
                               200                                                                   Tridecane
                               150                                                                   Dotriacontane
                                                                                                     Pyrene
                               100    -                                                              Phenanthrene
       CO                 U
                          Z       50
                          U         0              7          -Ir           T
                                       1           4            7           16          28

                                                           DAYS


                        Figure 23.    Degradation of selected fractions of South Louisiana Crude under oxidized conditions (+450 mV).









                                                                FERTILIZER EFFECT

                                     "/C3   6
                                     '-6b
                                     '@b    5
                                                                                                                    ED CR
                                            4--                                                                        CO
                                            3
                                                                                                                    0 LFR
                                     Z      2 -                                                                         LFO
                                                                                                                    M HIR
                                     r-)    0                                                                       E:i HFO
                                            -1     Undecane       Tridecane       Pentadecane     Heptadecane
                                            -2
                                                        HYDROCARBON FRACTION



                    Figure 24. Linear regression degradation rates of selected hydrocarbon fractions as affected by redox and fertilizer addition (C
                                 Control, R = Reduced, 0    Oxidized., LF = Low Fertilization, HF = High Fertilization).









             2.7 and 4.3 gg degraded g7' dry sediment d_', respectively. Under controlled reducing conditions,
             degradation rates averaged 0.3, 0.8 and 1. 1 pg g-' d-, respectively. Initial concentrations of the
             eight n-alkanes investigated were reduced approximately 25, 67 and 99% over 42 days for the
             control, low fertilizer and high fertilizer treatments, respectively, under oxidized sediment
             conditions.   Reducing conditions reduced initial concentrations approximately (production
             included) 27, 3 and 13%, respectively.
                     A general linear statistical model was used to test the interaction of the main effects (redox
             and fertilization), sorted by individual hydrocarbon compound. Additional analysis used the entire
             model, grouping all hydrocarbon fractions (C-10 through C-17) together. Analysis revealed
             fertilizer amendment had a greater effect on degradation rates of decane, undecane, tridecane and
             tetradecane than sediment redox. A post-analysis of variance technique was used to check for
             significant differences between redox and fertilizer effects. Duncan's Multiple Range Test for
             variable concentration of petroleum hydrocarbons found redox effects produced significant
             differences (P<0.05) in degradation rates. The two fertilizer treatments and control were also
             significantly different. These studies support previously published research showing fertilization
                                       or enhancing degradation of crude oil (Wright et al. 1997).
             can be used as a method f
                     Multiple regression was performed with both main effects and interactions.                The
             interaction of fertilizer and redox had the greatest effect on change in hydrocarbon concentration
             over time. The most significant main effect was time followed by redox and fertilization. None of
             the main effects or interactions were found to be insignificant compared to controls.
                     Oxygen concentration has been reported to be a critical rate lin-fting factor in
             biodegradation of hydrocarbons (Atlas and Cerniglia 1995). In this study, oxidation status or
             sediment redox condition was also shown to govern hydrocarbon degradation at the wetland site
             impacted by produced water discharge. Hgh concentrations of recalcitrant isoprenoids were
             encountered in sediment gathered at the outfall from a produced water pit. Degradation of these
             more resistant hydrocarbons was slow but showed a response to sediment redox condition.
             Oxidized sediment conditions showed a significant increase in the degradation rate for all
             compounds studied at the site compared to reducing sediment conditions. Even the recalcitrant
             isoprenoids showed appreciable degradation rates under oxidizing conditions.
                     South Louisiana Crude oil was added to sediment to determine rate of degradation of
             lighter hydrocarbon crude oil fractions. Oxidizing conditions resulted in an increased degradation
             rate of added South Louisiana Crude. This was especially true for the shorter n-alkane (<C-14).
             Concentration of some of the longer n-alkanes showed an increase with time, apparently caused
             by stripping of methyl groups during biodegradation, resulting in formation of n-alkanes. The
             oxidizing conditions increased the susceptibility of the branched long-chained hydrocarbons
             (isoprenoids), that are more difficult to degrade than the n-alkanes.













                                                               40












             4.0 SUMMARY


                   The effect of sediment redox conditions on the solubility behavior of Fe, Pb, Ni, Ba, and
             Cu in bottom sediment collected from a produced water discharge site was investigated using
             kinetics and chemical fi-actionation procedures. Sediment collected was composited and
             subsamples incubated in laboratory microcosm's under controlled Eh-pH conditions. Sediment
             was sequentially extracted for determining metals in five fractions (exchangeable, carbonate,
             bound to iron and manganese oxide, bound to organic matter and sulfide, mineral matrix or
             residue). Metal distribution in the fractions indicate that under oxidizing sediment conditions, the
             behavior of Fe, Pb and Ni were governed by FeQH) and Mn(IV) oxides; Ba by insoluble
             complexation with hurnic compounds, Cu by carbonates and humic complexation. Under reducing
             sediment condition, the behaviors of Fe and Cu were controlled by the formation of insoluble
             sulfides and humic complexes; the behaviors of Ni and Ba by carbonate and Pb behavior by
             sulfides, carbonates and humic complexes. With increases in sediment redox potential, the affinity
             between Fe(III), Mn(IV) oxides and Fe, Pb, Ni, Cu increased, affinity between insoluble large
             molecular humic and Ba increased, and the affinity between carbonates and Cu increased. With
             decreasing sediment redox potential, the affinity between carbonates and Fe, Ni, Ba increased,
             affinity between sulfides, humic substances and Fe, Pb, Ni, Cu also increased. Upon Fe(III) oxide
             reduction, it is estimated 20% of total reducible Fe(III) oxide were reduced by direct bacterial
             reduction (k--42.6 mg/kg/d), 80% of total reducible Fe(III) oxides was associated with chemical
             fractions attributed to sulfide oxidation (K=-171.5 mg/kg/d). The rate constants (mg/kg/d) for
             dissolved Ni (Eh < 0 mV), Pb (Eh < -80 mV) and Cu (-80 mV < Eh < 0 mV) are - 1.6, -0.047 and
             -0. 16 respectively. In our incubation period, the rate constants (mg/kg/d) for Ni bound to Fe(1111)
             and Mn(IV) oxides, Ba bound to carbonates and Cu bound to insoluble large molecular humic
             are -3.2, 0.91 and 4.3 respectively.
                    Kinetics and chemical fractionation procedures were also used in quantifying the effects of
             sediment redox (Eh) condition on the behaviors of As, Cd, Cr and Zn in the bottom sediment collected
             from a Louisiana Coastal site receiving produced water discharge. Sediment samples were incubated
             in rnicrocosms in which Eh-pH conditions were controlled. Sediment was sequentially extracted for
             determining metals in various chemical fractions (water soluble, exchangeable, bound to carbonates,
             bound to iron and manganese oxides, bound to insoluble organic and sulfides) and chemical inactive
             fraction (mineral residue). Under oxidizing conditions, As, Zn and Cr behavior were governed by
             redox chemistry of Fe(IH) and WON) oxides. Cd transformations were controlled by both Fe(M),
             Mn(M oxides and carbonates. Under reducing condition, the behaviors of Zn and Cr was controlled
             primarily by insoluble large molecular hun-@c material and sulfides; the behavior of Cd was controlled
             by carbonates. When sediment redox potential increased, the affinity between Fe(M), Mn(M oxides
             and As, Cd, Cr, and Zn increased. When sediment redox potential decreased, the affinity between
             carbonates and Cd and Zn increased; the affinity between insoluble sulfides, large molecular humic
             matter and As, Cd, Cr, Zn increased; the soluble Cd and Zn decreased; the soluble As and Cr remained
             constant. Results suggest reducing sediment conditions would reduce Cd and Zn toxicity. Under
             reducing or anaerobic conditions, the solibilization rate constants (mg/kg/d) for As, Cr, Cd, Zn bound
             to Fe(E11) and Mn(M oxides were -0.88, -0.32, -0.01, -6.5 respectively, the rate constants (mg/kg/d)
             for dissolved Cd and Zn were -0.09 and -1.78 respectively.
                     Sediment from oil recovery pit and stream bottom sediment receiving produced water
             discharge were incubated in laboratory microcosm under oxidized and reduced sediment conditions.



                                                               41











                The sediment was then extracted into various fractions and analyzed for radium-226. The                  results
                                                                                                                            orm
                indicated that very fittle (5 percent) of the total radium in the sediment material was present in a f
                that was extractable or otherwise available from the waste-pit material and/or bottom sediment (such
                forms include water-soluble, exchangeable, associated with carbonates, reducible, or organictsulfide).
                Approximately 95 percent of the radium present was tied up in a residual form that could be extracted
                only with very strong acids. Radium in this fraction would be released very slowly into the
                environment from the contaminated sediment,
                        Rate of petroleum hydrocarbon degradation was measured in sediment collected from a low
                energy brackish wetland site which had been exposed for a number of years to produced water
                discharge. Recalcitrant or higher molecular weight compounds were the primary hydrocarbon
                fractions found in the sediment. Degradation rates were determined by measuring loss of selected
                petroleum hydrocarbons components with time in laboratory incubation. South Louisiana Crude oil
                was added to the sediment to measure degradation rates of soluble hydrocarbons which were too low
                in concentration in the original sediment. Oxidized sediment conditions resulted in a higher rate of
                degradation for most hydrocarbon fractions as compared to reduced sediment. Fertilizer or nutrient
                amendments to contaminated sediments significantly increased the rate of hydrocarbon degradation.
                Fertilizer enhanced the degradation of the lower and more soluble molecular weight fiWfions as
                compared to the higher molecular weight fractions.
                        The effect of chromium (Cr) and lead (Pb) on degradation of South Louisiana Crude oil in
                sediment collected from a produced water discharge site was measured in laboratory microcosms
                under oxidized and reduced conditions.            Metal content had no impact on total hydrocarbon
                degradation content based on changes in concentration. Even on a percentage basis, which normalizes
                for differences in hydrocarbon concentrations, no statistical influence of Cr (5,000 pg/g) and Pb (2,500
                gg/g) on degradation could be measured under reducing conditions. A more sensitive analysis of metal
                impact on degradation depicted by an analysis of reduction of selected alkane fractions also showed
                little effect on degradation. Only degradation of octadecane was shown to be statistically inhibited at
                5,000 pg/g of added Cr and only under reducing conditions. The sediment due to the clay content,
                sequested much of the added metals. Under reducing conditions, 25 percent of water soluble and
                exchangeable Cr and Pb remained in solution at the highest Pb (2,500 Vg1g) and Cr (5,000 gg/g) levels
                compared to oxidized sediments. The amount in solution was not great enough to impact hydrocarbon
                degradation. The study demonstrates that Cr and Pb entering sediment at this produced water site
                would have minimal impact on petroleum hydrocarbon degradation.
                        In sunu-nary, heavy metal solubility was shown to be low in anaerobic and neutral pH
                estuarine sediment found at a coastal Louisiana produced water discharge sties. Solubility of Ba
                found in barite was low under alkaline and either anaerobic or aerobic sediment conditions. Over
                95% of radium found in contaminated sediment existed as an unavailable form which could be
                extracted only with strong acids. Typical heavy metal pollution levels found in the surface
                sediment environment at produced water discharge sites would not impact microbial degradation
                of petroleum hydrocarbons in the sediment column. Oxidized sediment conditions resulted in a
                faster rate of petroleum hydrocarbon degradation as compared to reducing sediment conditions in
                a produced water impacted sediment column.







                                                                       42













            5.0 REFERENCES


            Atlas, R.M. and Cerniglia@ C.E. 1995. Bioremediation of petroleum pollutants:   Diversity and
                    environmental aspects of hydrocarbon degradation. BioScience, (45)5:332-338.

            Boesch, D.F. and N.N. RabaWs, ed. 1989. Produced waters in sensitive coastal habitats:
                    An analysis of impacts, central coastal Gulf of Mexico. OCS Report/MMS89-0033 1, U.S.
                    Dept. of Interior, Minerals Management Service, Gulf of Mexico OCS Regional Office,
                    New Orleans, Louisiana, pp. 157.

            Bossert, I., M. Kachel, and R. Bartha. 1984. Fate of Hydrocarbons During Oily Sludge Disposal in
                    Soil. App). Environ. Microbiol, pp. 763-767.

            Boyd, S.A- and D.R- Shelton. 1984. Anaerobic Biodegradation of Chlorophenols in Fresh and
                    Acclimated Sludge. Appl. Environ. Microbiol, pp. 763-767,

            Capone, D.G., D.D. Reese, and R.P. Keine. 1980. Effects of Metals on Methanogenesis, Sulfate
                    Reduction, Calbon Dioxide Evolution, and Microbial Biomass in Anoxic Salt Marsh
                    Sediments. Appl. Environ. Microbiol, 45:1586-1591.

            DeLaune, R-D., C. Mulbah, 1. Devai, and C.W. Lindau. 1998. Effect of Chromium and Lead on
                    Degradation of South Louisiana Crude Oil in Sediment. J. Environ. Sci. Health. A33(4):527-
                    540.


            Farrell, R.E., J.J. Germida, and P.M. Huang. 1990. Biotoxicity of Mercury as Influenced by Mercury
                    (H) Speciation. Appl. Environ. Microbiol 56:3006-3016.

            Feijtel, T.C., R.D. DeLaune, and W.H. Patrick, Jr. 1988. Biogeochemical controls on
                    metal distribution and accumulation in Louisiana sediments. J. Environ. Qual. 17: 88-94.

            Folson, B.L., Jr., J.G. Skogerboe, M.R- Palermo, J.W. Simmers, SA Pranger, and R-A- Shafer.
                    1988. Synthesis of the results of the field verification program upland disposal alternative.
                    Tech. Rep. D-8 8-7. U.S. Arrny Corps of Eng. Waterways Exp. Stn., Vicksburg, MS.

            Freund, R.J. and W.J. Wilson. 1993. Statistical Methods. Academic Press, San Diego, CA.

            Gambrell, R.D. 1994. Trace and toxic metals in wetlands - A review. J. Environ. Qual.
                    23: 883-891.


            Gambrell, R.P., R.D. DeLaune, and W.H.- Patrick, Jr. 1991 a. Redox processes in soils
                    following oxygen depletion. p. 10 1 - 117. In: M.B. Jackson et a]. (ed.), Plant life under
                    oxygen deprivation. SPB Acaden-@c Publishing, The Hague, The Netherlands.






                                                           43









              Gambrell, R.P., J.B. Wiesepape, W.H. Patrick, Jr., and M.C. Duff. 1991b. The effects of
                     pH, redox, and salinity on metal release from a contaminated sediment. Water Air Soil
                     Pollut. 57-58: 359-367.


              Gambrel], R.P. and W.H. Patrick, Jr. 1988. The influence of redox potential on the
                     environmental chemistry of contaminants in soils and sediments. p. 319-333. In: D.D.
                     Hook (ed.) The ecology and management of wetlands. Vol. 1. Timber Press, Portland,
                     OR.


              Gambrel], R.P., R.A. Khalid, and W.H. Patrick, Jr. 1980. Chemical availability of
                     mercury, lead and zinc in Mobile Bay sediment suspension as affected by pH and
                     oxidation-reduction conditions. Environ. Sci. Technol. 14: 431436.


              Gambrell, R.P. and W.H. Patrick, Jr. 1978. Chemical and microbiological properties of
                     anaerobic soils and sediments. p. 375-423. In: D.D. Hook and R.M.M. Crawford (ed.),
                     Plant life in anaerobic environments. Ann Arbor Science, Ann Arbor, MI.

              Giblin, A.E., G.W. Luther 111, and 1. Valiela. 1986. Trace metal solubility in salt marsh
                     sediments contaminated with sewage sludge. Estuar. Coast. Shelf Sci. 23: 477-498.

              Giesy, J.P., G.L. Leversee, and D.R. William. 1977. Effects of naturally occurring aquatic
                     organic fractions on cadm@iurn toxicity to simocephalus serrulatus (daphnidae) and
                     Gambusia a nis(Polciludae). Water Res. 11: 1013-1020.
                                rff,

              Griffin, T.M., M.C. Rabenhorst, and D.S. Fanning. 1989. Iron and trace metals in some
                     tidal marsh soils of the Chesapeake Bay. Soil Sci. Soc. Am. J. 53: 1010-1019.

              Guo, T., R.D. DeLaune, and W.H. Patrick, Jr. 1997a. The Effect of Sediment Redox Chemistry
                     on Solubility/Chemically Active Forrns of Selected Metals in Bottom Sediment Receiving
                     Produced Water Discharge. Spill Science Technology. 4(3):165-175.

              Guo, T., R.D. DeLaune, and W.H. Patrick, Jr. 1997b. The Influence of Sediment Redox
                     Chemistry on Chemically Active Forms of Arsenic, Cadium, Chromium and          Zinc in
                     Estuarine Sediment. Environmental International. 32(3):305-316.

              Jacobson, M.E. 1994. Chemical and biological mobilization of Fe(111) in marsh sediments.
                     Biogeochemistry, 25, 41-60.

              Keller, C., and J.C. Vedy. 1994. Distribution of copper and cadmium fractions in two
                     forest sofls. J. Environ. Qua]. 23: 987-999.

              Kerner, M. and K. WaUman. 1992. Remobilization events mivolving Cd and Zn from intertidal flat
                     sediments in the Elbe Estuary during the tidal cycle. Estuar. Coast. Shelf Sci. 35: 371-393.





                                                            44









            Khalid, R.A., R.P. Gambrel], and W.H. Patrick, Jr. 1981. Chemical availability of
                    cadmium in Mississippi River sediment. J. Environ. Qual. 10: 523-529.

            Koons, C.B., C.D. McAuliffe, and F.T. Weiss. 1977. Effects of produced waters on the
                    marine environment. Oceans.


            Kraemer, T.F. and D.F. Reid. 1984. The occurrence and behavior of radium in saline formation water
                    of the U.S. Gulf Coast region. Isotope Geoscience 2:153-174.

            Langinuir, D. and D. Melchior. 1985. The geochemistry of Ca, Sr, Ba and Ra sulfates in some deep
                    brines from the Palo Duno Basin Texas. Geochen-iica Cosmochemica Acta- 49:2423-2432.


            Leahy, J.G. and R_R_ Colwell. 1990. Microbial Degradation of Hydrocarbons in the Environment.
                    Microbial. Rev 54:305-315.


            Levy, D.B., K.A. Barbarick, E.G. Siemer, and L.E. Sommers. 1992. Distribution and
                    partitioning of trace metals in contaminated soils near Leadville, Colorado, J. Environ.
                    Qual. 21: 185-195.

            Lovley, D.R. and E.J.P. Phillips. 1987. Competitive mechanisms for inhibition of sulfate
                    reduction and methane production in the zone of ferfic iron reduction in sediment. Appl.
                    Environ. Microbiol. 53: 2636-2641.


            Lyssj, 1. 198 1. Oil and gas extraction operations, Report to EPA Municipal Environmental
                    Research Laboratory, Cincinnati.

            Masscheleyn, P.H., J.H. Pardue, R-D. DeLaune, and W.H. Patrick, Jr. 1992. Chromium redox
                    chemistry in a Lower Mississippi valley bottornland hardwood wetland. Environ. Sci.
                    Technol. 26(6): 1217-1226.

            McGeehan, S.L. and D.V. Naylor. 1994. Sorption and redox transformation of arsenite and arsenate
                    in two flooded sods. Sod Sci. Soc. Am. J. 58: 337-342.


            Michel, J., W.S. Moore, and P.T. King. 1981. Gamma-ray spectrometry for determining radium-228
                    and radium-226 in natural waters. Analytical chemistry 53:1885-1889.

            Miller, R.M. and R_ Bartha. 1989. Evidence from Liposome Encapsulation for Transport-Limited
                    Microbial Metabolism of Solid Alkanes. Appl. Environ. Microbiol 55:269-274.

            Neff, J.M., N.N. Rabalais, and D.F. Boesch. 1987. Offihore oil and gas development
                    activities potentially causing long-term environmental effects. Pages 149-173 in D.F.
                    Boesch and N.N. Rabalais (eds.), Long-Term Environmental Effects of Offshore Oil and
                    Gas Development, Elsevier Apphed Science Publishers Ltd., London, 696pp.





                                                            45











            Neff, J.M., T.C. Sauer, and N. Maciolek. 1989. Fate and Effects of Produced Water
                   Discharges in Nearshore Marine Waters. API Publication No. 4472, American
                   Petroleum Institute, Washington, D.C., 300pp.

            Neter, J., H. Wasserman, and M.H. Kunter. 1990. Applied Statistical Models 3rd Edition, Burr,
                   Illinois, IRWIN.

            Oberbremer, A_, R_ MuUer-Hurtig, and F. Wagner. 1990. Effect of the Addition of Microbial
                   Surfactant on Hydrocarbon Degradation in a Soil Population in a Stiffed Reactor. Appl.
                   Environ. Microbiol 32:485-489.


            Palermo, M.R_, R_A_ Shafer, J.M. Brannon, T.E. Myers, C.L. Truitt, and M.E. Zappi. 1989.
                   Evaluation of dredged material disposal alternatives for US Navy homeport at Everett,
                   Washington. Tech. Rep. EL-89-1. U.S. Army Corps of Eng. Waterways Exp. Stn.,
                   Vicksburg, MS.

            Patrick, W.H., Jr., B.G. WiAliarns, and J.T. Moraghan. 1973. A simple system for controlling redox
                   potential and pH in soil suspension. Soil Sci. Am. J. 32: 331-332.

            Rabalais, N.N., B.A. McKee, D.J. Reed, and J.C. Means. 1991. Fate and Effects of
                   Nearshore Discharges of OCS Produced Waters. Volume 11. Technical Report. OCS
                   Study/MMS91-000x. U.S. Dept. of the Interior, Minerals Management Service, Gulf of
                   Mexico OCS Regional Office, New Orleans, Louisiana.

            Ramos, L., L.M. Hernandez, and M.J. Gonzalez. 1994. Sequential firaction of copper,
                   lead, cadmium and zinc in soils from or near Donana National Park. J. Environ. Qua]. 23:
                   50-57.


            Said, W.A_ and D.L. Lewis. 1991. Quantitative Assessment of the Effects of Metals on Microbial
                   Degradation of Organic Chemicals. Appl. Environ. Microbiol 57:1498-1507.

            Shannon, R.D. 1991. The selectivity of a sequential extraction procedure for the determination
                   of iron oxyhydroxides and iron sulfides in lake sediment. Biogeochem. 14:193-201.

            SAS. 1995. Statistical Analysis Systems version 6. 10, SAS Institute, Cary, NC.

            St. Pe, K. 1990. An assessment of produced water impacts to low-energy brackish
                   water systems in south east Louisiana. Report by Louisiana Department of Environmental
                   Quality. Water Pollution Control Division.

            Tillery, J.B., R.E. Thomas, and H.L. Windom. 1981. Trace metal studies in sediment and
                   fauna. In: Ecological investigation of petroleum production platforms in the Central Gulf
                   of Mexico, prepared by Southwest Research Institute, San Antonio, TX., for the Bureau
                   of Land Management: New Orleans OCS; Vol. 1, Part 4.




                                                          46












           Wright, A.L., R.W. Weaver, and J.W. Webb. 1997. Oil bioremediation in salt marsh
                   mesocosms as influenced by N and P fertilization, flooding and season. Water, Soil and
                   Air Pollution, 95:179-191.

            Zhang, Y., and R-M. Miller. 1992. Enhanced Octadecane Dispersion and Biodegradation of a
                   Pseudomonas rhamnolipid Surfactant (Biosurfactant). Appl. Environ. Microbiol 58:3276-
                   3282.





























































                                                           47
 













                                    US Department of Commerce
                               NOAA Coaital Services Center Library
                                     2234 South Hobson Avenue
                                     Charlestoin4 SC 29405-2413





                                                                                                                                                     0
                                                                                              llnffilnn@
                                                                                                 3 6668 14101 4

                                                                                                                                                     01





























                                   The Department of the Interior Mission

                                   As the.Nation's principal conservation agency, the Department of the Interior has responsibility for
                             0
                                   most of our nationally owned public lands and natural resources. This includes fostering sound use
                                   of our land and water resources; protecting our fish, wildlife, and biological diversity; preserving the
                                   environmental and cultural values of our national parks and historical places; and providing for the
                                   enjoyment of life through outdoor recreation. The Department assesses our energy and mineral
                                   resources and works to ensure that their development is in the best interests of all our people by
                                   encouraging stewardship and citizen participation in their care. The Department also has a major
                                   responsibility for American Indian reservation communities and for people who live in island territories
                                   under U.S. administration.

                                   The Minerals Management Service Mission
                     or r
                                   As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary
                             76    responsibilities are to manage the mineral resources located on the Nation's Outer Continental Shelf
                             -     (OCS), collect revenue from the Federal OCS and onshore Federal and Indian lands, and distribute
                                   those revenues.

                                   Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program
                                   administers the OCS competitive leasing program and oversees the safe and environmentally sound
                                   -exploration and production of our Nation's offshore. natural gas, oil and other mineral resources. The
                                   MMS Royalty Management Program meets its responsibilities by ensuring the efficient, timely and
                                   accurate collection and disbursement of revenue from mineral leasing and production due to Indian
                                   tribes and allottees, States and the U.S. Treasury.

                                   The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being
                                   responsive to the public's concerns and interests by maintaining a dialogue with all potentially affected
                                   parties and (2) carrying out its programs with an emphasis on working to enhance the quality of life for
                                   all Americans by lending MMS assistance and expertise to economic development and environmental
                                   protection.