NOAA Status and Trends Mussel Watch Project

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

NOAA STATUS AND TRENDS
Mussel Watch Project
Technical Report
Year IX

The Geochernical and
Environmental Research Group
Texas A&M Research Foundation

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NOAA NATIONAL
STATUS AND TRENDS

Mussel Watch Project

Year 9 Technical Report

property of CSC Library
Prepared by

The Geochemical and Environmental Research
Group (GERG)
Texas A&M University
833 Graham Road
College Station, Texas 77845

Submitted to

U.S. Department of Commerce
National Oceanic & Atmospheric Administration
1305 East-West Hwy.
Silver Spring, MD 209 10
U,S, DFPARTMFNT nr COMMERCE NOAA
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September 1994
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TABLE OF CONTENTS

Introduction ........................................................................................... 1

Reprint 1: Accumulation and Depuration of Organic
Contaminants by the American Oyster (Crassostrea
virginica) ............................................................................................ 10

Reprint 2: Toxicological Significance of Non-, Mono- and Di-
ortho-Substituted Polychlorinated Biphenyls in Oysters
fTom Galveston and Tampa Bays ........................................................ 35

Reprint 3: Distribution and Sources of Organic Contaminants
in Tidal River Sediments of the Washington, DC Area .......................... 43

Reprint 4: Distribution and Sources of Trace Metals to Tidal
River Sediments of Washington, DC .................................................... 89

NOAX 8 NATIONAL STATUS AND TRENDS (NS&T) MUSSEL WATCH
PROGRAM - GULF OF MEXICO

The purpose of the NOAA National Status and Trends (NS&T)
Mussel Watch Project is to determine the long-term temporal and spatial
trends of selected environmental contaminant concentrations in bays
and estuaries. The key questions in this regard are:

(1) What is the current condition of the nation's coastal zone?
(2) Are these conditions getting better or worse?

This report represents the Year 9 Technical Report from this multi-
year project. These questions have been addressed in detail as evidenced
by the scientific papers and reports that have resulted from the
Geochemical and Environmental Research Group's (GERG)
interpretations of the Gulf Coast data (Table 1). Publications not
included in GERG's previous Technical Reports are contained in this
technical report.

This report is an update on the current condition of the Gulf of
Mexico coastal zone, based on results from Years 1 through 9 of the
NOAA NS&T Mussel Watch Project. Following is a brief sampling survey
of these years:

Year 1 - 49 sites (147 stations) of the original 51 sites were
successfully sampled. Sediments and oysters were
analyzed at triplicate stations from all sites.
Year 2 - 48 sites (144 stations) of the original 51 sites were
successfully sampled. Sediments and oysters were
analyzed at triplicate stations from all sites.
Year 3 - Twenty (20) sites were added to the original list of 51
sites for a total of 71 sites. Sixty-four (64) sites (192
stations) of the 71 sites were sampled (only 19 of the
new sites were sampled). Oysters were analyzed at
triplicate stations from all sites. Sediments were
analyzed at only the new sites (three stations analyzed
per site).
Year 4 - Seven (7) new sites were added (only six of the new sites
were successfully sampled). Sixty-seven (67) sites (201
stations) of the 78 total sites were sampled. Oysters
were analyzed at triplicate stations from all sites.
Sediments were analyzed at only the new sites (three
stations analyzed per site).
Year 5 - Three (3) new sites were added to the sampling project
(only two of these sites were successfully sampled;
79:MBDR and 80:PBSP). Sixty-eight (68) sites (204
stations) of the 80 total sites were sampled. Oysters
were analyzed at triplicate stations from all sites.

Sediments were analyzed at only the new sites (three
stations analyzed per site).
Year 6 - Two (2) new sites were added to the sampling project
(81:BHKF in Bahia Honda Key, FL and 63:LPGO in
Lake Pontchartrain, LA). Sixty-four (64) sites (192
stations) were sampled. Oysters were analyzed at
triplicate stations from all sites. Sediments were
analyzed at only the new sites (three stations analyzed
per site).
Year 7 - Five new sites were established including three new
sites in Puerto Rico (Sites 86 to 88) and two new sites
in Choctawhatchee Bay (Sites 84 and 85). Sixty-seven
(67) sites were analyzed. Only one oyster analysis was
conducted at each of the old sites on a composite from
the three stations. Sediments were analyzed at the five
new sites and one site in Florida (PBPH) (three stations
analyzed per site).
Year 8 - Sixty-eight (68) existing sites were sampled. Only one
oyster analysis was conducted at each of the existing
sites on a composite from the three stations.
Sediments were not collected at any sites.
Year 9 - A total of 55 sites were visited and 51 of them were
successfully sampled. Four of the originally scheduled
sites were devoid of any live oysters. Two new sites
were established in Florida Bay (Flamingo Bay, FBFO;
and Joe Bay, FBJB). At these Is these new sites both
triplicate sediments and oysters were sampled. No
other sediment samples were taken this year. Only one
oyster analysis was conducted at each of the existing
sites on a composite from the three stations.

Details of the sample collection and location of field sampling sites are
contained in a separate report titled "Field Sampling and Logistics in
Year 9".

The oyster and sediment samples were analyzed for contaminant
concentrations [trace metals, polynuclear aromatic hydrocarbons (PAH),
pesticides and polychlorinated biphenyls (PCBs)], and other parameters
that aid in the interpretation of contaminant distributions (grain size,
oyster size, lipid content, etc.). The analytical procedures used and the
QA/QC Project Plan are detailed in a separate report titled "Analytical
Methods". The data that were produced from the sample analyses for
Year 9 are found in a separate report titled "Analytical Data".

A complete and comprehensive interpretation of the data from the
National Status and Trends Project for oyster data coupled with the
sediment data is an on-going process. We have begun and are
continuing that process as evidenced by this report and the scientific
manuscripts that we have published or submitted for publication (Table
1). As part of the data interpretation and dissemination, over 40

presentations of the NOAA NS&T Gulf Coast Mussel Watch Project were
given at national and international meetings. With eight years of data,
the question of temporal trends of contaminant concentrations has been
addressed. A general conclusion found for most contaminants measured
is that the concentrations have remained relatively constant over the
nine year sampling period. This general trend, however, is not observed
at all sites. Some sites show significant changes (both increases and
decreases) among the years. Continued sampling is addressing the
frequency and rates of these changes.

Exceptions to this general txend are found for DDTs and TBT.
When historical data for DDT in bivalves is compared to current NS&T
data, a decrease in concentration is apparent. Also based on TBT data
collected as part of the NOAA NS&T Mussel Watch Project, a decline in
TBT concentration in oysters is apparent. Both declines may be in
response to regulatory actions.

During Year 3 of this project, 20 new sites were added. These sites
were chosen to be closer to urban areas, and therefore, to the sources of
contaminant inputs. These new sites were not, however, located near
any known point sources of contaminant input. These sites were added
to better represent the current status of contaminant concentrations in
the Gulf of Mexico. Over the subsequent years of the project (Years 4
through 9) additional sites have been added to increase the
representative coverage of the Gulf of Mexico and U.S. Caribbean
territories.

While sampling sites for this project were specifically chosen to
avoid known point sources of contamination, the detection of coprostanol
in sediment from all sites indicates that the products of man's activities
have reached all of the sites sampled. However, when compared to
known point sources of contamination, all of the contaminant
concentrations reported are, in most cases, many orders of magnitude
lower than obviously contaminated areas. The lower concentrations in
Gulf of Mexico samples most likely reflect the fact that the sites are
further removed from point sources of inputs, a condition which is
harder to achieve in East and West Coast estuaries. In fact, new sites
added in Years 3 through 7 are closer to urban areas and generally had
higher contaminant concentrations. An important conclusion derived
from the extensive NS&T data set is that contamination levels in Gulf
Coast near shore areas remain the same or are getting better, and most
areas removed from point sources are not severely contaminated.

This document represents one of three report products as part of
Year 9 of the NS&T Gulf of Mexico projects. The other two reports are
entitled:

Analytical Data, Year 9
Field Sampling and Logistics, Year 9

Table 1. GERG/NOAA NS&T PUBLICATIONS Included in
Year Report

Wade, T.L., B. Garcia-Romero and J.M. Brooks (1988)
Tributyltin contamination of bivalves from U.S. coastal
estuaries. Environmental Science and Technology, 22:
1488-1493. IV

Wade, T.L., E.L. Atlas, J.M. Brooks, M.C. Kennicutt H, R.G. Fox,
J. Sericano, B. Garcia-Romero and D. DeFreitas (1988)
NOAA Gulf of Mexico Status and Trends Program:
Trace organic contaminant distribution in sediments
and oysters. Estuaries, 11: 171-179. IV

Wade, T.L., B. Garcia-Romero and J.M. Brooks (1988)
Tributyltin analyses in association with NOAA's
National Status and Trends Mussel Watch Program. In:
OCEANS '88 Conference Proceedings, Baltimore, MD, 31
Oct. - 2 Nov. 1988, pp. 1198-1201. IV

Wade, T.L., M.C. Kennicutt, II and J.M. Brooks (1989) Gulf of
Mexico hydrocarbon seep communities: M: Aromatic
hydrocarbon burdens of organisms from oil seep
ecosystems. Marine Environmental Research, 27: 19-30. IV

Wade, T.L. and J.L. Sericano (1989) Trends in organic
contaminant distributions in oysters from the Gulf of
Mexico. In: Proceedings, Oceans '89 Conference, Seattle,
WA, pp. 585-589. IV

Wade, T.L. and B. Garcia-Romero (1989) Status and trends of
tributyltin cont=dnation of oysters and sediments from
the Gulf of Mexico. In: Proceedings, Oceans '89
Conference, Seattle, WA, pp. 550-553. IV

Wade, T.L. and C.S. Giam (1989) Organic contaminants in the
Gulf of Mexico. In: Proceedings, 22nd Waterfor Texas
Conference, Oct. 19-21, 1988, South Shore Harbour Resort
and Conference Center, League City, TX (R. Jensen and C.
Dunagan, Eds.), pp. 25-30. V

Craig, A., E.N. Powell, R.R. Fay and J.M. Brooks (1989)
Distribution of Perkinsus marinus in Gulf coast oyster
populations. Estuaries, 12: 82-91. IV

Presley, B.J., R.J. Taylor and P.N. Boothe (1990) Trace metals
in Gulf of Mexico oysters. The Science of the Total
Environment, 97/98: 551-553. IV

Sericano, J.L., E.L. Atlas, T.L. Wade and J.M. Brooks (1990)
NOAA's Status and Trends Mussel Watch Program:
Chlorinated pesticides and PCB's in oysters
(Crassostrea virginica) and sediments from the Gulf of
Mexico, 1986-1987. Marine Environmental Research, 29:
161-203. IV

Wade, T.L., B. Garcia-Romero and J.M. Brooks (1990) Butyltins
in sediments and bivalves from U.S. coastal areas.
Chemosphere, 20: 647-662. IV

Brooks, J.M., M.C. Kennicutt II, T.L. Wade, A.D. Hart, G.J.
Denoux and T.J. McDonald (1990) Hydrocarbon
distributions around a shallow water multiwell
platform. Environmental Science and Technology, 24:
1079-1085. IV

Sericano, J.L., T.L. Wade, E.L. Atlas and J.M. Brooks (1990)
Historical perspective on the environmental
bioavailability of DDT and its derivatives to Gulf of
Mexico oysters. Environmental Science and Technology,
24: 1541-1548. IV

Wade, T.L., J.L. Sericano, B. Garcia-Romero, J.M. Brooks and
B.J. Presley (1990) Gulf coast NOAA National Status &
Trends Mussel Watch: the first four years. In: MTS'90
Conference Proceedings, Washington, D.C., 26-28
September 1990, pp. 274-280. IV, V

Brooks, J.M., T.L. Wade, B.J. Presley, J.L. Sericano, T.J.
McDonald, T.J. Jackson, D.L. Wilkinson and T.F. Davis
(1991) Toxic contamination of aquatic organisms in
Galveston Bay. In: Proceedings Galveston Bay
Characterization Workshop, February 21-23, pp. 65-67. VI

Wade, T.L. J.M. Brooks, J.L. Sericano, T.J. McDonald, B. Garcia-
Romero, R.R. Fay, and D.L. Wilkinson (1991) Trace
organic contamination in Galveston Bay: Results from
the NOAA National Status and Trends Mussel Watch
Program In: Proceedings Galveston Bay Characterization
Workshop, February 21-23, pp. 68-70. VI

Presley, B.J., R.J. Taylor and P.N. Boothe (1991) Trace metals
in Galveston Bay oysters. In: Proceedings Galveston Bay
Characterization Workshop, February 21-23, pp. 71-73. VI

Sericano, J.L., T.L. Wade and J.M. Brooks (199 1) Transplanted
oysters as sentinel organisms in monitoring studies. In:
Proceedings Galveston Bay Characterization Workshop,
February 21-23, pp. 74-75. VI

McDonald, S.J., J.M. Brooks, D. Wilkinson, T.L. Wade and T.J.
McDonald (1991) The effects of the Apex Barge oil spill
on the fish of Galveston Bay. In: Proceedings Galveston
Bay Characterization Workshop, February 21-23, pp. 85-
86. VI

Wade, T.L., J.M. Brooks, M.C. Kennicutt H, T.J. McDonald, G.J.
Denoux and T.J. Jackson (1991) Oysters as biomonitors
of oil in the ocean. In: Proceedings 23rd Annual Offshore
Technology Conference, No. 6529, Houston, TX, May 6-
9,, pp. 275-280. V

Brooks, J.M., M.A. Champ, T.L. Wade, and S.J. McDonald
(1991) GEARS: Response strategy for oil and
hazardous spills. Sea Technology, April 1991, pp. 25-32. V

Sericano, J.L., T. L. Wade and J.M. Brooks (1991) Chlorinated
hydrocarbons in Gulf of Mexico oysters: Overview of
the first four years of the NOAA's National Status and
Trends Mussel Watch Program (1986-1989). In: Water
Pollution: Modelling, Measuring and Prediction. Wrobel,
L.C. and Brebbia, C.A. (Eds.), Computational Mechanics
Publications, Southampton, and Elsevier Applied Science,
London, pp. 665-681. V, VI

Wade, T.L., B. Garcia-Romero and J.M. Brooks (1991)
Bioavailability of butyltins. In: Organic Geochemistry -
Advances and Applications in the Natural Environment.
Manning, D.A.C. (Ed.), Manchester University Press,
Manchester, pp. 571-573. V

Wilson, E.A., E.N. Powell, M.A. Craig, T.L. Wade and J.M.
Brooks (1991) The distribution of Perkinsus marinus in
Gulf coast oysters: its relationship with temperature,
reproduction and pollutant body burden. Int. Reuve der
Gesantan Hydrobioligie, 75: 533-550. IV

Sericano, J.L., A.M. El-Husseini and T.L. Wade (1991) Isolation
of planar polychlorinated biphenyls by carbon column
chromatography. Chemosphere, 23(7): 915-924. V, V1

Wade, T.L., B. Garcia-Romero and J.M. Brooks (1991) Oysters
as biomonitors of butyltins in the Gulf of Mexico.
Marine Environmental Research, 32: 233-241. IV, V

Wilson, E.A., E.N. Powell, T.L. Wade, R.J. Taylor, B.J. Presley
and J.M. Brooks (1991) Spatial and temporal
distributions of contaminant body burden and disease
in Gulf of Mexico oyster populations: The role of local
and large-scale climatic controls. Helgolander
Meeresunters, 46: 201-235. V, V1

Powell, W.N., J.D. Gauthier, E.A. Wilson, A. Nelson, R.R. Fay
and J.M. Brooks (1992) Oyster disease and climate
change. Are yearly changes in Perkinsus marinus
parasitism in oysters (Crassostrea virginica) controlled
by climatic cycles in the Gulf of Mexico? PSZNI: Marine
Ecology, 13: 243-270. IV

Hofmann, E.E., E.N. Powell, J.M. Klinck E.A. Wilson (1992)
Modeling oyster populations Ill. critical feeding
periods, growth and reproduction. J. Shellfish
Research, 2: 399-416. V

Sericano, J.L., T.L. Wade, A.M. El-Husseini and J.M. Brooks
(1992) Environmental significance of the uptake and
depuration of planar PCB congeners by the American
oyster (Crassostrea virginica). Marine Pollution Bulletin,
24: 537-543. VI

Wade, T.L., E.N. Powell, T.J. Jackson and J.M. Brooks (1992)
Processes controlling temporal trends in Gulf of Mexico
Oyster health and contaminant concentrations. In:
Proceedings MTS '92, Marine Technology Society, Oct. 19 -
2 1, Washington, D.C. pp. 223-229. VI

Tripp, B.W., J.W. Farrington, E.D. Goldberg and J.L. Sericano
(1992) International mussel watch: the initial
implementation phase. Marine Pollution Bulletin, 24:
371-373. VI

Sericano, J.L., T.L. Wade and J.M. Brooks (1993) The
usefulness of transplanted oysters in biomonitoring
studies. In: Proceedings of The Coastal Society Twetfth
International Conference, Oct. 21-24, 1990, San Antonio,
TX, pp. 417-429. V, VH

Wade, T.L., J.L. Sericano, J.M. Brooks and B.J. Presley (1993)
Overview of the first four years of the NOAA National
Status and Trends Mussel Watch Program. In:
Proceedings of The Coastal Society Twelfth International
Conference, Oct. 21-24, 1990, San Antonio, TX, pp. 323-
334. V, VH

Sericano, J.L., T.L. Wade, E.N. Powell and J.M. Brooks (1993)
Concurrent chemical and histological analyses: Are
they compatible? Chemistry and Ecology, 8: 41-47. V, VI

Sericano, J.L., T.L. Wade, J.M. Brooks, E.L. Atlas, R.R. Fay and
D.L. Wilkinson (1993) National Status and Trends
Mussel Watch Program: chlordane-related compounds
in Gulf of Mexico oysters: 1986-1990. Environmental
Pollution, 82: 23-32. V, VI

Wade, T.L., T.J. Jackson, J.M. Brooks, J.L. Sericano, B. Garcia-
Romero and D.L. Wilkinson (1993) Trace organic
contamination in Galveston Bay oysters: results from
the NOAA National Status and Trends Mussel Watch
Program. In: Proceedings, The Second State of the Bay
Symposium, Galveston, TX, February 4-6, pp. 109-111. Vil

Presley, B.J. and K.T. Jiann (1993) Indicators of trace metal
pollution in Galveston Bay. In: Proceedings, The Second
State of the Bay Symposium, Galveston, TX, February 4-6,
pp. 127-13 1. VII

Wade, T.L., T.J. Jackson, T.J. McDonald, D.L. Wilkinson, and
J.M. Brooks (1993) Oysters as biomonitors of the APEX
barge oil spill. In: Proceedings, 1993 International Oil
Spill Conference, Tampa, FL, March 29-April 1, pp. 127-
131. V111

Palmer, S.J., B.J. Presley, R.J. Taylor and E.N. Powell (1993)
Field studies using the oyster Crassostrea virginica to
determine mercury accumulation and depuration rates.
Bulletin Environmental Contamination Toxicology, 51:
464 470. VII

Morse, J.W., B.J. Presley and R.J. Taylor (1993) Trace metal
chemistry of Galveston Bay: water, sediment and biota.
Marine Environmental Research, 36: 1-37. VII

Sericano, J.L. (1993) The American oyster (Crassostrea
virginica) as a bioindicator of trace organic
contamination. Ph.D. Dissertation, Department of
Oceanography, Texas A&M University, 242 p. V11

Palmer, S.J. and B.J. Presley (1993) Mercury bioaccumulation
by shrimp (Penaeus aztecus) transplanted to Lavaca
Bay, Texas. Marine Pollution Bulletin, 26(10): 564-566. VII

Garcia-Romero, B., T.L. Wade, G.G. Salata, and J.M. Brooks
(1993) Butyltin concentrations in oysters from the Gulf
of Mexico during 1989-1991. Environmental Pollution,
81: 103-111. vi, VII

Ellis, M.S., K.-S. Choi, T.L. Wade, E.N. Powell, T.J. Jackson and
D.H. Lewis (1993) Sources of local variation in
polynuclear aromatic hydrocarbon and pesticide body
burden in oysters (Crassostrea virginica) from Galveston
Bay, Texas. Comparative Biochemistry and Physiology,
106C: 689-698. VI, VEII

Kennicutt, M.C. 11, T.L. Wade, B.J. Presley, A.G. Requejo, J.M.
Prooks and G.J. Denoux (1993) Sediment contaminants
in Casco Bay, Maine: inventories, sources and potential
for biological effects. Environmental Science and
Technology, 28(l): 1-15. VIII

Jackson, T.J., T.L. Wade, T.J. McDonald, D.L. Wilkinson and J.M.
Brooks (1994) Polynuclear aromatic hydrocarbon
contaminants in oysters from the Gulf of Mexico (1986-
1990). Environmental Pollution, 83: 291-298. V1, VIE[, VM

Sericano, J.L., T.L. Wade, B. Garcia-Romero and J.M. Brooks
(1994) Environmental accumulation and depuration of
tributyltin by the American Oyster, Crassostrea
Wrginica. Marine Environmental Research (in press). IV

Hofmann, E.E., J.M. Klinck, E.N. Powell, S. Boyles, M. Ellis
(1994) Modeling oyster populations H. Adult size and
reproductive effort. Journal of Shelyish Research, 13(l):
165-182. V, Vul

McDonald, S.J., M.C. Kennicutt I[[, J.L. Sericano, T.L. Wade, H.
Liu, and S.H. Safe (1994) Correlation between bioassay-
derived P450 1A 1 -Induction activity and chemical
analysis of clam (Laternuld elliptica) extracts from
McMurdo Sound, Antarctica. Chemosphere, 28(12):
2237-2248. VIII

Sericano, J.L., T.L. Wade and J.M. Brooks (1994) Accumulation
and depuration of organic compounds by the American
oyster (Cassostrea virginica). Science of the Total
Environment (in press). IX

Sericano, J.L., S.H. Safe, T.L. Wade, and J.M. Brooks (1994)
Toxicological significance of non-, mono-, and di-ortho
substituted polychlorinated biphenyls in oysters from
Galveston and Tampa Bays. Environmental Toxicology
and Chemistry, 13(11): x-xx (in press). ix

Velinsky, D.J., T.L. Wade, C.E. Schlekat, B.L. McGee, and B.J.
Presley (1994) Tidal river sediments in the Washington,
D.C. area. I. Distribution and sources of trace metals.
Estuaries, 17: 305-320. IX

Wade, T.L., D.J. Velinsky, E. Reinharz, and C.E. Schlekat (1994)
Tidal river sediments in the Washington, D.C. area. H.
Distribution and sources of organic contaminants.
Estuaries, 17: 321-333. IX

Reprint I

Accumulation and Depuration. of Organic
Contaminants by the American Oyster
(Crassostrea virginica)

Jose L. Sericano, Terry L. Wade and James M.
Brooks

Sericano et al. - I

ACCUMULATION AND DEPURATION OF ORGANIC CONTAMINANTS

BY THE AMERICAN OYSTER (CRASSOSTREA VIRGINICA)

JOSE L. SERICANO, TERRY L. WADE and JAMES M. BROOKS

Geochemical and Environmental Research Group

College of Geosciences and Maritime Studies

Texas A&M University

833 Graham Rd., College Station, Texas 77845, U.S.A.

Sericano et al. - 2

ABSTRACT

Oysters and other bivalves are widely used to assess the levels of environmental

contamination; however, very little actual field calibration of bivalves has been done. The

purpose of this research, therefore, has been to evaluate the uptake and depuration of

selected PCBs and PAHs in transplanted American oysters, Crassostrea virginica, under

field conditions in Galveston Bay, Texas. Transplanted oyster were found to bioaccumulate

contaminants and reach concentrations nearly equal to those of indigenous oysters for PAI-Is

and low molecular weight PCBs within 30 to 48 days. In contrast, high molecular weight

PCBs did not reach equivalent concentrations. When returned to a clean environment,

oysters significantly depurated PAHs and low molecular weight PCBs. There were,

however, differences in depuration rates when newly contaminated oysters were compared

to chronically contaminated oysters. Oysters are useful tools in biomonitoring studies but

have their limitations. Transplant studies help to establish these limitations on the use of

oysters as sentinel organisms to avoid misleading interpretation of the oyster contaminant

concentrations.

Sericano et at. - 3

RiTRODUCTION

Contamination of the coastal marine environment by a number of organic compounds

of synthetic or natural origin has received increasing attention over the last several years.

Biomonitoring of these compounds in the aquatic environment has been well established and

bivalves are generally preferred for this purpose. The rationale for the "Mussel Watch"

approach using different bivalves, e.g. mussel, oysters and/or clams, has been summarized

by different authors (Goldberg et al., 1978; Farrington et al., 1980; Phillips, 1980;

Risebrough et al., 1983) and its concept has been applied to several monitoring programs

during the last decade (Farrington et al., 1983; Martin, 1985; Tavares et al., 1988; Wade et

al., 1988; Sericano et al., 1990; Tripp et al., 1992).

Several studies have examined the dynamics of the uptake and depuration of trace

organic contaminants; however, the information found in the literature is confusing. As an

example, Table I lists a number of studies published over the last two decades that report

the depuration of different hydrocarbon mixtures by bivalves. The contradicting results of

these studies, most of them carried out in laboratories, are obvious. Bivalves need to be

"calibrated" under real environmental conditions to be valuable as bioindicators of organic

contamination. Uptake and depuration rates of organic contaminants, compound selectivity,

interaction between different xenobiotics, seasonal effects on the body concentrations of

xenobiotics and differences between species need to be known to take full advantage of the

"Mussel Watch" concept.

The present study was designed to examine the rate of uptake and depuration of

selected trace organic contaminants, e.g. polynuclear aromatic hydrocarbons (PAHs) and

polychlorinated biphenyls (PCBs), in oysters (Crassostrea virginica) during transplantation
experiments in two locations in Galveston Bay, Texas. Uptake and depuration rates of

selected organic compounds by transplanted oysters were determined. Clearance rates

Sericano et al. - 4

determined for newly contaminated oysters are compared to depuration rates found in

chronically polluted oysters.

MATERIALS AND METHODS

Experimental design

Approximately 250 oysters of similar dimensions were collected from a relatively

uncontaminated area in Galveston Bay, Hanna Reef, and transplanted in 2400 cm net bags,

containing 25-30 individuals per bag, to a new location near the Houston Ship Channel in

the upper part of the Bay (Fig. 1). Composite samples of 20 transplanted and 15

indigenous oysters were collected at 0, 3, 7, 17, 30, and 48 days during the first phase of

the transplantation experiment. The remaining Hanna Reef oysters were then back-

transplanted to their original location in Galveston Bay. At the same time, approximately

150 indigenous oysters from the Ship Channel site were also transplanted to the Hanna Reef

area. Composite samples of 20 oysters from each population were collected at 0, 3, 6, 18,

30, and 50 days after transplantation.

Analytical method

The analytical procedures used during this study are modifications of previously

reported methods (MacLeod et al., 1985) and are fully described elsewhere (Wade et al.

1988; Sericano et al, 1990). Briefly, approximately 10- 15 g of wet tissue are dried with

Na2SO4 and macerated with methylene chloride with a Tissurnizer for 3 minutes after the

addition of internal standards. This extraction is repeated twice more with new additions of

methylene chloride. Combined extracts are concentrated to a final volume of 2 mL in

hexane for silica gel-alumina chromatography clean-up. Silica gel is activated prior to use

by heating at 170'C for 12 hr and then partially deactivated with 5% water. Alumina is

activated at 400*C for 4 hr and then partially deactivated with I% water. The column is

slurry-packed in methylene chloride with 10 g of alumina over 20 g of silica gel. Sample

Sericano et al. - 5

extracts are eluted from the column using 50 mL of pentane (f 1=aliphatic hydrocarbons) and

then with 200 mL of a pentane:methylene chloride (50:50) mixture (f2=chlorinated

hydrocarbons, including PCBs, and PAHs). The f2-fraction is further purified by high

performance liquid chromatography (Krahn et al., 1988).

The PAHs in f2-fraction were separated and quantitated by GC/MS using an HP-

5880-GC interface with an HP5970-MSD. Sample extractss were injected in the splitless

mode on a 30 m x 0.25 mm (0.32 gm film thikness) DB-5 fused silica capillary column at
an initial temperature of 60'C. The oven temperature was programmed at 12'C min-] to

300*C and held at the final temperature for 6 min. The mass spectral data were acquired

using selected ions for each of the PAHs, The instuments were calibrated using a five-point

calibration curve and the calibration was checked by running continuing calibrations

standards with each set of samples with no more than 6 hr between calibrations checks.

Analyte concentrations were calculated using the mean relative response factors for each

analyte relative to the internal standards added before extraction.

Samples were analyzed for PCB congeners by fused-silica capillary column GC-ECD
(Ni63) using a Hewlett-Packard 5880A GC in the splitless mode. The DB-5 capillary

column (30 m x 0.25 mm; 0.25 gm film thikness) was temperature-programmed from
1000C to 1400C at 50C min-1, from 1400C to 250'C at 1.50C min-1, and from 2500C to
3000C at IO'C min'l with I min hold time at the beginning of the program and before each

program rate change. The final temperature was held for 5 min. Injector and detector

temperatures were set at 2750C and 325'C, respectively. These compounds were quantitated

against a set of authentic standards that were injected at four different concentrations to

calibrate the instrument and to compensate for non-linear response of the detector.

Sericano et al. - 6

Quality controllquality assurance (QAIQC)

Interim reference materials as well as spiked blanks, duplicate samples and spiked

samples were analyzed along with each sample set as part of the laboratory

QA/QC program. Evaluation of the analytical methods and possible sources of error

are a continuing and ongoing process in order to assure the realibility of the data.

RESULTS AND DISCUSSION

The concentrations of some of the organic contaminants increased dramatically during

the seven-week exposure period. Comparatively, concentrations of some individual PAHs

and PCBs in indigenous oysters during the first phase of this experiment were fairly

constant. The analyte concentrations in native oysters represent the time-integrated

c n n t a m 1 nant concentrations available to the oysters in solution, adsorbed onto particles and

incorporated with food.

Polynuclear Arornatic Hydrocarbons

Initial concentrations of total PAHs, ie. surn of 24 individual analytes (Sericano et al.,
1993), in transplanted oysters increased from 290 ng g-1 to a final value of 4360 ng g-1. By

the end of 48 days, transplanted oysters accumulated these PAHs to levels that were not

statistically differentiable from the concentrations measured in native individuals (Fig. 2).

Two- and three-ring PAHs were detected in low concentrations in both transplanted and

indigenous oysters while four- and five-ring compounds were detected in high

concentrations. The PAHs accumulated to the highest concentrations by transplanted

oysters were: pyrene >flu oran thene>chry sen e >ben zo (e) pyre ne>benzo(b)anthracen e.

Although in slightly different order, approximately the same PAHs were reported to be

preferentially accumulated by clams and mussels exposed to sediments contaminated with
relatively high PAH concentrations, i.e. pyrene >ben zo(e)pyrene>benzo(b)fluoranthene>

Sericano et al. - 7

benz(a)anthracene (Obana et al., 1983) and chrysene>benzo(b)fluoranthene>fluoranthene>

benzo(e)pyrene>benz(a)anthracene (Pruell et al., 1986), respectively.

Hanna Reef and Ship Channel oysters showed statistically significant depuration

(p<0.05) of four- and five-ring PAHs after relocation to the Hanna Reef area. Depurations

of these aromatic compounds by both groups of oysters were approximately exponential.

This is indicated in Fig. 3 where the concentration of selected PAHs plotted on a semi-log

plot approximate straight lines.

Kinetics parameters describing uptake and release of PAHs can be calculated assuming

the first-order equation

dCddt = ku Cw - kd Ct (1)

where Ct is the PAH concentration in the transplanted oyster at time=t, Cw is the PAB

concentration in the seawater, and ku and kd are the uptake and depuration rate constant,

respectively. If the Cw at Hanna Reef is regarded as zero, i.e. Cw--O, which is considerably

reasonable because of the very low PAH concentrations measured in indigenous oysters,

then equation (1) reduces to

dCddt = -kd Ct (2)

or, after integration,

log Ct = Log Co-(kd/2.301) t (3)

where CO is the PAH concentration in oysters at the time of their relocation to the Hanna

Reef area. Using this equation and the PAH concentrations corresponding to both oyster

populations during the depuration period, values of kd can be calculated.

Statistical analyses, at the a = 0.05 level, of the regression lines of the logarithm of the

concentrations versus sampling time for the depuration period showed significant

Sericano et al. - 8

differences between the slopes, i.e. depuration rates, measured for Hanna Reef and Ship

Channel oysters were significantly different. The biological half-life, tj/2, can be derived

from equation (3)

4/2 = 0-693/kd (4)

The half-lives are reported in Table 2. They ranged from 9 and 10 days for pyrene to

26 and 32 days for fluoranthene in Hanna Reef and Ship Channel oysters, respectively.

Most of the values were, however, between 10 and 16 days. These findings are in

agreement with those of Pruell et al. (1986) who reported half-lives between 14 and 30 days

for selected PAHs in mussels (Mytilus edulis) exposed in the laboratory to environmentally

contaminated sediments. Contrasting with other reports (Table 1), both studies suggest that

bivalves are able to depurate the accumulated hydrocarbons in fairly short periods of time.

The difference in depuration rates between both newly and chronically contaminated

oysters is evident at the end of the 50-day depuration period when the concentrations of

PAHs grouped by number of rings or individually are compared (Fig. 4). At the end of the

depuration period, the total PAH concentration in chronically contaminated oysters were

about 40% higher than the final concentration measured in originally uncontaminated
oysters. Total PAH concentrations decreased from 4,400 to 360 ng g-1 and from 4,400 to
500 ng g-1, respectively. This observation is in agreement with an earlier work by Jackim

and Wilson (1977) who reported that the depuration rates of N' 2 fuel oil compounds

observed in chronically exposed bivalves (Mya arenaria) were considerably lower than those

observed in organisms after an acute exposure.

Polychlorinated Biphenyls

PCB concentrations in transplanted oysters increased from 30 ng g-1 to 850 ng g-1

after the 48-day exposure period. Pentachlorobiphenyls were the compounds accumulated

to the highest concentrations in transplanted and native oysters (Fig. 5). In comparison,

Sericano et al. - 9

practically no octa-, nona- or decachlorobiphenyls were detected in either oyster group.

Contrasting with PAHs, not all the PCB homologs measured in transplanted oysters reached

the concentration encountered in indigenous individuals by the end of the fust phase of this

experiment. While there were no statistically significant differences in the tri- and

tetrachlorobiphenyl concentrations measured in transplanted and native oysters, significant

differences were observed in the total concentrations of penta- and hexachlorobiphenyls. It

seems evident that a longer exposure period is needed for the higher molecular weight PCB,

i.e. congener 110, to reach an steady state concentration (Fig. 6).

Hanna Reef and Ship Channel oysters showed statistically significant depuration

(p<0.05) of low molecular weight PCBs when relocated to the Hanna Reef area. Originally

uncontaminated oysters depurated PCBs at a faster rate than chronically contaminated

oysters. The clearance rates of high molecular weight PCBs were significantly slower in

both oyster populations. This differential PCB depuration can be observed in Fig. 7 where

the concentrations of selected PCBs at the end of the uptake and depuration periods are

shown.

Biological half-lives (BHL) for selected PCB congeners in Hanna Reef and Ship

Channel oysters ranged from 22 to 130 days and from 22 days to >year, respectively (Table

2). These BHL compare well with those observed in previously reported studies using

bivalves. Pruell et al. (1986) reported half-lives for some tri-, tetra-, penta- and

hexachlorobiphenyls in mussels exposed to resuspended contaminated sediments ranging

from 16.3 to 45.6 days. Similar to the present study, the biological half-lives of PCBs

increased with the number of chlorine atoms in the biphenyl rings. Langston (1978) also

reported that the less chlorinated PCB congeners were depurated more rapidly by bivalves

(Cerastoderma edule and Macoma balthica) with half-lives from 5 to 21 days for selected

di-, tri- and tetrachlorobiphenyls. In contrast, the concentrations of hexachlorobiphenyls,

and some of the pentachlorobiphenyls, did not decrease during the 21 -day study. Courtney

Sericano et al. - 10

and Denton (1976) reported that environmentally contaminated clams and clams exposed to

Aroclor 1254 in the laboratory did not depurate PCBs during three months in control

seawater.

From this study, it is clear that oysters will react differently to sudden increases in

environmental concentrations of PAHs or PCBs,.as a consequence of, for example,

accidental spills. While PAHs and low molecular weight PCB concentrations seem to reach

a steady-state within about a month, high molecular PCB congeners might require a much

longer period of time, i.e. over 6 months to reach steady-state concentrations. Similarly, the

period of time needed for oysters to depurate the accumulated organic contaminants after the

spill to accurately represent the actual contamination of a site will be different for PAHs and

lower chlorinated PCB congeners compared to higher molecular weight PCBs.

As a general conclusion oysters can be useful tools in biomonitoring studies but

results differ for different trace organic contaminants. Transplant studies place boundary

conditions on the use of oysters as sentinel organisms. These experimental results can be

used to better understand the PCB and PAH data in oyster samples collected from coastal

U.S. areas during programs such as NOAA's National Status and Trends (NS&T) "Mussel

Watch" Program.

ACKNOWLEDGEMENTS

Funding for this research was provided by the National Oceanic and Atmospheric

Administration Grant Number 50-DGNC-5-00262 (National Status and Trends Program).

Sericano et at. - I I

REFERENCES

Blumer, M., G. Souza and J. Sass, 1970. Hydrocarbon pollution of edible shellfish by an

oil spill. Mar. Biol., 5: 195-202.

Boehm, P.D. and J.G. Quinn, 1977. The persistence of chronically accumulated

hydrocarbons in the hard shell clam Mercenaria mercenaria. Mar. Biol., 44: 227-233.

Courtney, W. A. M. and G. R. W Denton, 1976. Persistence of polychlorinated biphenyls

in the hard-clam (Mercenaria mercenaria) and the effect upon the distribution of these

pollutants in the estuarine environment. Environ. Poll., 10: 55-64.

Farrington, J. W., E.D. Goldberg, R.W. Risebrough, J.H. Martin and V.T. Bowen, 1983.

U.S. "Mussel Watch" 1976-1978: An overview of the trace-metal, DDE, PCB,

hydrocarbon, and artificial radionuclide data. Environ. Sci. Technol., 17: 490-496.

Farrington, J.W., J. Albaiges, K.A. Burns, B.P. Dunn, P. Eaton, J.L. Laseter, P.L.

Parker and S. Wise, 1980. Fossil fuels. In: The International Mussel Watch, Report

of a workshop sponsored by the Environmental Studies Board Commision on Natural

Resources, National Research Council, pp 7-77.

Goldberg, E. D., V.T. Bowen., J.W. Farrington, G. Harvey, J.H. Martin, P.L. Parker,

R.W. Risebrough, W. Robertson, E. Schneider and E. Gamble, 1978. The mussel

watch. Environ. Conserv., 5: 101-126.

Jackim, E. and L. Wilson, 1977. In: Proceedings, 10th Annual National Shellfish

Sanitation Meeting, p. 27.

Krahn, M.M., C.A. Wigren, R.W. Pearce, L.K. Moore, R.G. Bogar, W.D. MacLeod, S-

L Chan and D.W. Brown, 1988. Standard analytical procedures of the NOAA

Sericano et al. - 12

National Analytical Facility. New HPLC cleanup and revised extraction procedures

for organic contaminants. Noaa Tech. Memo, 52 pp.

lAngston, W. J., 1978. Persistence of polychlorinated biphenyls in marine bivalves. Mar.

Biol., 46: 35-40.

MacLeod, W. D., D.W. Brown, A.J. Friedman, D.G. Burrows, 0. Maynes, R.W. Pearce,

C.A. Wigren and R.G. Bogar, 1985. Standard analytical procedures of the NOAA

National Analytical Facility, 1985-1986. Extractable toxic organic components.

Second edition, U.S. Department of Commerce, NOAA/NMFS. NOAA Tech.

Memo. NMFS F/NWC-92.

Martin, M., 1985. State Mussel Watch: Toxic survillance in California. Mar. Poll. Bull.,

16:140-146.

Obana, H., S. Hori, A. Nakamura and T. Kashimoto T, 1983. Uptake and release of

polynuclear aromatic hydrocarbons by short-necked clams (Tapes japonica). Water

Res., 17: 1183-1187.

Phillips, D.J.H. 1980. Quantitative Biological Indicators, Their Use to Monitor Trace

Metals and Organochlorine Pollution; Applied Science, London, 1980.

Pittinger, C.A., A.L. Buikema Jr., S.G. Homor and Young R.W., 1985. Variation in

tissue burdens of polycyclic aromatic hydrocarbons in indigenous and relocated

oysters. Environ. Toxicol. Chem., 4: 379-387.

Pruell, R. J., J.L. Lake, W.R. Davis and J.G. Quinn, 1986. Uptake and depuration of

organic contaminants by the blue mussels (Mytilus edulis) exposed to environmentally

contaminated sediments. Mar. Biol., 91: 497-507.

Sericano et al. - 13

Risebrough, R. W., B.W. DeLappe, W. Walker II, B.T. Simoneit, J. Grimalt, J. Albaiges

and J.A.G. Regueiro, 1983. Application of the Mussel Watch concept in studies of

the distribution of hydrocarbons in the coastal zone of the Ebro Delta. Mar. Poll.

Bull., 14: 181-187.

Sericano, J. L., E.L. Atlas, T.L. Wade and J.M. Brooks, 1990. NOAA's Status and

Trends Mussel Watch Program: Chlorinated pesticides and PCBs in oysters

(Crassostrea virginica) and sediments from the Gulf of Mexico, 1986-1987. Mar.

Environ. Res., 29: 161-203.

Sericano, J.L., 1993. The arnerican oyster (Crassostrea virginica) as a bioindicator of trace

organic contamination. Ph.D. Dissertation, Texas A&M University, College Station,

Texas, U.S.A., 242 pp.

Stegeman, J.J. and J.M. Teal, 1973. Accumulation, release and retention of prtroleum

hydrocarbons by the oyster Crassostrea virginica. Mar. Biol., 44: 37-44.

Tanacredi, J.T. and R.R. Cardenas, 1991. Biodepuration of polynuclear aromatic

hydrocarbons from a bivalve mollusc, Mercenaria mercenaria L. Environ. Sci.

Technol., 25:1453-1461.

Tripp, B.W., J.W. Farrington, E.D. Goldberg and J.L. Sericano, 1992. International

Mussel Watch: the initial implementation phase. Mar. Poll. Bull., 24: 371-373.

Tavares, T.M., V.C. Rocha, C. Porte, D. Barce16 and J. Albaig6s, 1988. Application of

the Mussel Watch Concept in studies of hydrocarbons, PCBs and DDT in the

Brazilian Bay of Todos os Santos (Bahia)Mar. Poll. Bull., 19: 575-578.

Wade, T. L., E.L. Atlas, J.M. Brooks, M.C. Kennicutt II, R.G. Fox, J.L. Sericano, B.

Garcia and D. DeFreitas, 1988. NOAA Gulf of Mexico Status and Trends Program:

Sericano et at. - 14

Trace organic contaminant distribution in sediments and oysters. Estuaries, 11: 171-

179.
Wormell, R.L. (1979). Petroleum hydrocarbons accumulation patterns in Crassostrea
virginica: analyses and interpretations. Ph.D. Dissertation, Rutgers University, NJ,

189 pp.

Table 1. Results of different hydrocarbon uptake/depuration studies with bivalves reported

in the literature.

Bivalve Exposure Observation Reference

Oysters No 2 Fuel Oil Little depuration Blumer et al. (1970)

(60 days) after 180 days

Oysters N* 2 Fuel Oil Nearly complete Stageman and Teal

(49 days) depuration in 28 (1973)

days

Clams Chronically Slight depuration Boehm and Quinn

polluted after 120 days (1977)

Oysters Chronically Nearly complete Wormell (1979)

polluted depuration with
,BHL--4.4 days
Oysters PAHs Analytes below Pittinger et al.

(15 days) detection limits (1985)

after 4 days

Mussels PAHs Depuration with Pruell and Quinn
(40 days) BFUL between (1986)

14-30 days

Clams PAHs No depuration Tanacredi and

(2 days) in 45 days Cardenas (1991)

Table 2. Biological half-lives of selected PAHs and PCBs in transplanted and indigenous
oyster@(-

Analyte Oysters Musselsl
Hanna Reef Ship Channel

PAHs

Phenanthrene - - -
Fluoranthene 26 32 30
Pyrene 10 12 -
Benzo(a)anthracene 13 15 18
Chrysene 12 16 14
Benzo(e)pyrene 12 16 14
Benzo(a)pyrrm 9 10 15
Indeno[1,2,3-c,dlpyrene 10 11 16

PCBs
26 22 22 -
28 - - 16
52 27 45 -
101 55 116 28
110 45 103 -

118 73 299 -
128 76 229 37
149 130 >year -
153 51 102 46

Pruell et al., 1986

Figure Captions

Figure I- Galveston Bay tr-ansplantation sites.

Figure 2- Total and selected individual polynuclear aromatic hydrocarbon concentrations (ng
9-1, dry weight) in Hanna Reef and Ship Channel oysters at the end of the 48-day

uptake period. Error bars represent one standard deviation from the mean (n = 4).
Figure 3- Selected polynuclear aromatic hydrocarbon concentrations (ng g-1, dry weight) in

Hanna Reef and Ship Channel oysters during the uptake and depuration phases of

the study. Error ban represent one standard deviation from the mean (n = 4).

Figure 4- Total and selected individual polynuclear aromatic hydrocarbon concentrations (ng
9-1, dry weight) in Hanna Reef and Ship Channel oysters at the end of the 50-day

depuration period. Error bars represent one standard deviation from the mean (n

4).
Figure 5- Total polychlorinated biphenyl@ grouped by level of chlorination, and selected
individual congener concentrations (ng g-1, dry weight) in Hanna Reef and Ship

Channel oysters at the end of the 48-day uptake period. Number in parentheses

indicates level of chlorination. Error bars represent one standard deviation from the

mean (n = 4).
Figure 6- Selected polychlorinated biphenyl concentrations (ng g-1, dry weight) in

Hanna Reef and Ship Channel oysters during the uptake and depuration phases of

the study. Error bars represent on e standard deviation from the mean (n = 4).
Figure 7- Total polychlorinated biphenyy grouped by level of chlorination, and selected
individual congener concentrations (ng g- 1, dry weight) in Hanna Reef and Ship
Channel oysters at the end of the 50-day depuration period. Number in parentheses

indicates level of chlorination. Error bars represent one standard deviation from the

mean (n = 4).

94@O-

TEXA S

LA PORTE
A
fA

<01
@P

0
EAST

29*30'
EO't
SAN L

7:
5z,

TEXAS CITY

4M>:

GALVESTON

Site 1 Hanna Reef

E
w Site 2: Ship Channel

44W END OF UPTAKE PERIOD
z N HR Oysters
0 3000 0 SC Oysters

z 2A0W0

z
0 1000

0
2 3 4 5 6

NUMBER OF RINGS

END OF UPTAKE PERIOD
2500 B IL-Phenanthrene
2-Fluoranthene
z 3-PyTene
0 2000, 4-Senw(a)anthmcene
5-Chrysene
1500 6-Benzo(e)pyrene

z 1000

z
0 500

0
1 2 3 4 5 6

ANALYTE
L

PYRENE
10000 A
HR Oysters
SC Oysters
z
0

11000

(64
z

100.
z
0

UPrAKE DEPURATION
10 ....................I....... . . . ...................... ...........
0 10 20 30 44) 50 60 70 80 90 100
TIME (days)

CHRYSENE
10000
B 0- HR Oysters
0 SC Oysters
z
0

1000

Z loo
0
Q

UPrAKE DEPURATION
10 ....... low I
0 10 20 30 40 50 60 70 80 90 1;0
TIME (days)
u

4W END OF DEPURATION PERIOD
A N HR Oysters
z Im SC Oysters
0
300

200
z

Z 3LOO
100

0 FWIA
2 3 4 5 6

NUMBER OF RINGS

END OF DEPURATION PERIOD
160- B IL-Phenanthrene
z 140- 2-Fluaranthene
3-Pyrene
0 4-Be ne
120 5-Chrysene
loo 6-Benzo(e)pyrene

so
z
60
Z 40
0
20

0
1 2 3 4 5 6

ANALYTE

6w A END OF UPTAKE PERIOD
0 HR Oysters
Z Sw SC Oysters
0

400

300
z
W
0 200
z
0 JLoo
0 RTMM
3 4 5 6 7 8

LEVEL OF CHLORINATION

END OF UPTAKE PERIOD
100- B

z
0 so-

z 40

z
0 20-

0
26(3) 52(4) 110(5) 118(5) 149(6) 187(7)
PCB CONGENER

PCB 52
loomo A
0 HR Oysters
0 SC Oysters
z
0

1100

10
z
0

UPTAKE DEPURATION

0 10 20 30 40 50 60 70 so 90 100
TIME (days)

1000 PCB 110
B HR Oysters
SC Oysters
z
0

100

10,
z
0

UPTAKE DEPURATION

.......... .......... ......... ..........
0 10 20 30 40 50 60 70 so 90 100
TIME (days)

600 END OF DEPURATION PERIOD
A 0 HR Oysters
Z SW 0 SC Oysters
0
4W

300
z
94
ri 200
z
0 100

0
3 4 5 6 7 a

LEVEL OF CHLORINATION

END OF DEPURATION PERIOD
loo B

z
0 80"

z
40

z
0 20
0- WA MW
26(3) 52(4) 110(5) 118(5) 149(6) 187(7)
PCB CONGENER

Reprint 2

Toxicological Significance of Non-, Mono-
and Di-ortho-Substituted Polychlorinated
Biphenyls in Oysters from Galveston and
Tampa Bay

Jose L. Sericano, Stephen H. Safe, Terry L.
Wade and Jame M. Brooks

ETC 192

EnvironmenW Toxicoicigy and Chemistry. Vol. 13. No. 11, pp. 000-", 1994
PeMainon COP.-ght t 1994 SETAC
Printed in ine LSA
0730-'268/9L4 S6.00 - 00
0730-7268(94)00125-1

TOXICOLOGICAL SIGNIFICANCE OF NON-, MONO- AND
DI-ortho-SUBSTITUTED POLYCHLORINATED BIPHENYLS
IN OYSTERS FROM GALVESTON AND TAMPA BAYS

Jost L. SERICANO,*t STEPHINH. SAYE,* TE"y L. WADEt and JAm:Es M. BROOKSt
+Geochemical and Environmental Research Group, College of Geoscience and Maritime Studies,
Texas A&M University, 833 Graham Road., College Station. Texas 77945
:Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine.
Texas A&M University, College Station. Texas -7843

(Received 22 October 1993@ Accepted 14 April 1"4)

Abstr2ct -Concentrations an non-ortho (77, 126, and 169), mono-ortho (105 and 118) and di-ortho 028 and 138) -substituted
PCB congeners were measured in oysters from Galveston and Tampa bays, and reported toxic equivalent factors were used to
assess their toxicity. Most of Elie relative toxicity encountered in the oysters analyzed during this Study was due to the presence
of planar non-ortho-PCBs (53.8-94.307c), particularly congener 126. In contrast. the contribution of di-onho-substituted PCB
congeners to the total relative toxicity of the samples is negligible (< 1076). On average. the contribution of each of these non-.
mono-. and di-ortho-substituted PCB congeners to the total toxicity encountered in oysters from Galveston and Tampa bays
were 126 > 118 a 169 2t 105 > 77 z, 138 > 128 and 126 > 118 > 169 2: 77 > 105 v 138 > 128. respectively. Based on the re-
ported lower clearance rates of non-orEho- and mono-orEho-substituted PCB congeners compared to other congeners within the
same chlorination level. contaminated oysters that are depurated in clean environments will lower their total PCB concentra-
tions. but their original toxicity may not be proportionally reduced.

Keywords-PCBs Toxicity Depuration Oysters Gulf of Mexico

INTRODUCTION toxic but far more abundant mono- (PCB 105 and 118) and
The general concern about the occurrence of PCBs in dif- di-ortho (PCB 128 and 138) congeners.
ferent environmental compartments is associated with their MATERIALS AND METHODS
potential adverse environmental and human health effects. Sampling
The toxicity of individual PCB congeners is structure- These samples were collected from 3 stations at 11 pre-
dependent [1-31, and the most toxic PCB congeners- i.e., the selected sites in Galveston and Tampa bavs (Fig. 1) durine
planar 3.3',4,4'-tetrachlorobiphenvi (7), 3,3',4.4',5-penta- the 6-year sampling activities of the National Oceanic and Al-
chlorobiphenyl (126). and 3.3',4.4",5,5'-hexachlorobiphenN.1
mospheric Administration's (NOAA's) National Status and
(169)- are approximate iscistereomers and potent mimics of Trends -Mussel Watch" Program (December 1990-Januarv
:.3.7,8-telTachlOTodibenzo-p-dioxin (TCDD). TCDD and I"l). Distances between stations within each site varied from
related compounds elicit a diverse spectrum of toxic and bio- 100 to 1,000 m. Depending on water depth. oysters 120 per
chemical responses including body weight loss, dermal dis- station) were collected by hand, tongs. or dred'ge. pooled in
orders, liver damage, thymic atrophy, reproductive toxicity
precombusted jars, and frozen until analysis. More details
and immunotoxicitv, and the induction of CYPIAI and regarding site locations and sample collections for this PTO-
CYPIA2 gene expression [1-41. Although epidemiological gram are given elsewhere [I I)'.
studies on human and animal populations have not revealed
clear evidences of the carcinogenicity of PCBs under envi- F-viraction and initial sample fractionation
ronmental exposure, PCBs are strong promoters of hepatic The analytical procedure used for the extraction. initial
carcinogenesis in laboratory rodents 15). fractionation', and cleanup of oyster tissue samples for the
In recent years there has been considerable interest in analysis of polychlorinated biphenyLs (PCBs), including pla-
studying the occurrence of not only planar PCB congeners nar PCB congeners, is based on a method developed by
but also their mono- and di-ortho derivatives 16- 101. The ob- MacLeod et a]. 1121 with a few modifications. Details of this
jective of this study was to determine the toxicological sig- method and its modifications have been fully described else-
nificance of three highly toxic planar PCB congeners (i.e.. where 1131 and only the important steps will be given here.
PCBs 7. 126, and 169) encountered in oyster samples from Approximately 15 g of wet tissue are extracted. after the
Galveston and Tampa bays compared to the'relatively less addition of anhy'drous Na,SOA, with methylene chloride
using a homogenizer (Tekmar Tissurnizer). A small subsam-
pie is removed from the total volume for lipid determination.
'To whom correspondence may be addressed. Each set of 8 to 10 samples is accompanied by a complete
36

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Significance of toxic PCBs in Gulf of Mexico oil 003

system blank and spiked blank or reference material carried the oven temperature was programmed from 100 to 1500C
through the entire analytical method as part of the labora- at 100C min-' and from 150 to 2700C at VC min-' with
P
ory quality assurance/qualiry control (QA/QQ procedure. I-min hold time at the beginning of the program and before
Before extraction 4,4'-dibromoocmfluorobipheny) (DBOFB), the program rate change. A hold time of 3 min was used at
CB 103, and PCB 198 are added to all samples, blanks, and the final temperature. Total run time was 30 min.
reference material as internal standards. Tissue extracts are In both analyses, injector and detector temperatures were
initially fractionated by partially deactivated silica: alumina set at 275 and 325*C, respectively. Helium -as used as the
column chromatography. The sample extracts are eluted carrier W at anowvelocity of 30.0 cm sec ` at I 00"C. A
from the column using pentane (f I = aliphatic hydrocarbons) mixture of argon/methane (95: 5) was used as the makeup gas
and pentane: methylene chloride (1: 1) M = chlorinated hy- at a flow rate of 20 ml min-'. The volume injected was 2jul.
drocarbons and PAHs). The second fractions are further pu- The PCB congeners were quantitated against a set of stan-
rified by high-performance liquid chromatography to remove dards injected at four different known concentrations to cal-
lipids [14). Finally, sample extracts are concentrated to a ibrate the instrument and to compensate for the nonlinear
olume of I ml, in lexane, for gas chromatographic IGCI response of the elec,ron,cap,ure detector. Te,rachloro-m-
analysis. xylene (TCMX) was used as the GC internal standard to es-
timate the recoveries of the internal standards- The detection
Isolation of planar PCB congeners limits for individual planar and nonplanar PCB congeners -
The extraction, initial fractionation, and cleanup of pla- estimated on the basis of 2.5 g (dry weight) oyster tissue sam-
nar PCBs were performed simultaneously with the bulk of ple sizes, I in) final extract volume, and 2 gl of the extract
the ortho-substituted PCBs. After the final extract concen- injected into the GC-ECD -are 0.25 ng g -' and 0.05 ng
tration to I in], a 0.25-ml fraction was withdrawn for the 9-', dry weight, respectively.
analysis of planar PCB congeners. Because of the low envi-
ronmentaJ concentrations expected for planar PCBs, the ex- RESULTS AND DISCUSSION
tracts Of Oysters collected at the same site were combined as Concentrations of individual planar PCB congeners. as
one sample. Thus, the concentrations of planar PCB conge- well as concentrations of related mono- and di-ortho-
ners represent the analyses of composite samples. Before pro- substituted congeners and total PCBs, in oyster samples from
ceeding to the next step, PCB 81 was added to the extracts 12 sites in Galveston and Tampa bays are shown in Table 1.
as internal standard for planar PCB congeners. These concentrations have been corrected by the recoveries
The methodology used to isolate planar PCBs in tissue of the internal standards -i.e., PCB 103 for orEho-substituted
samples has been published elsewhere (151. Briefly, glass congeners and PCB 81 for planar congeners. In general. re-
chromatographic columns (10 min i.d.) are packed in meth- coveries of the internal standards ranged from 61; to 9207o.
ylene chloride. Two grams of a 1:20 mixture of activated The highest concentrations of planar PCBs in samples
AX-21 charcoal (Super-A activated carbon) and LPS-2 silica from Galveston Bay were found in oysters collected in the
gel (low-pressure silica gel, particle size 37-53,um, 450 m2. area where the Houston Ship Channel enters into Galveston
g-'), are packed between two layers of anhydrous sodium Bay and the concentrations decreased seaward. High planar
sulfate. Oyster Eissue extracts are sequentially eluted from the PCB levels were also encountered in samples from a site near
column with 50 ml of 1:4 methylene chloride and cyclohex- the city of Galveston. In general. the levels of planar PCBs
ane, 30 ml of 9:1 methylene chloride and toluene. and 40 ml in Galveston Bay were clearly highest near population cen-
of toluene. The first two solvent mixtures are collected as one ters. The same correlation was observed in Tampa Ba%.
fraction 1111 and contain the ortho-substituted PCB conge- where the highest planar PCB concentrations were observed
ners. The second fraction M), containing the non-ortho- in samples collected near the city of Tampa.
substituted PCB congeners with four, five and six chlorines The concentrations of congener 77 in different commer-
in meta and para positions, is concentrated to a final volume cial PCB mixtures are I to 2 orders of magnitude higher than
of 0.05 ml, in hexane, for gas chromatography-electron- the concentrations of congener 126 and 3 to 5 orders of mag-
capture detection (GC-ECD) analysis. nitude higher than the concentrations of congener 169 [16-
201. Comparatively, average concentrations of congener -7
Instrumental ana@vsis encountered in oyster samples from Galveston and Tampa
The PCBs. both planar and nonplanar congeners, were bavs were 1.5 to 2 times higher than the concentrations of
analyzed by fused-silica capillary column. 30 in long x PC*B 169 but comparable to the concentrations of congener
0.25 mm i.d. with 0.25 14m DB-5 film thickness, GC-ECD 126. These results suggest that congeners 126 and 169 are en-
(61M) using a Hewlett Packard 5880A GC in the splitiess riched in oyster samples from Galveston and Tampa bays.
mode. Selective enrichment of congener 126 and 169 with respect
For the analysis of ortho-substituted PCB congeners, the to congener 77 is also apparent in mussels and oyster sam-
oven temperature was programmed from 100 to 140*C at ples analyzed by different researchers (Table 2). This selec-
5*C min-', from 140 to 2500C at 1.50C min-', and from tive enrichment might be a consequence of the increasing log
250 to 300*C at 100C min-' with 1-min hold time at the be- K,,. (logarithm of the octanol/water partition coefficient)
ginning of the run and at each program rate change. A hold with the number of chlorines substituted in the biphenyl rings
time of 5 min was used at the final temperature. Total run (6.36, 6.89, and 7.42 for congeners 77. 126. and 169, respec-
time was 94 min. For the analysis of planar PCB congeners tively, Hawkerand Connell 1211). Inaddition, themore highl%

004 I.L. SERICANO Er AL.

Table 1. Non-. mono-, and di-ortho-substituted PCB and total PCB concentrations (ng S-' dry weight = I sD) in oysters
(Cramosiree virginica) from Galveston and Tampa bays

PCB congeners
Non-ortho Mono-ortho Di-ortho Total PCB Total Total
Sample 77 126 169 105 118 128 138 concentrations" TEQs6 TEQs-

Galveston Say
Ship Channel 2.0 2.2 0,79 39 = 4.1 48 = 5.8 4.4 = 0.6 50 = 6.7 1, 100 120 280 370
(20) (220) (40) (39) (48) (0.0 0.0)
Yacht Club 0.33 0.21 0.19 4.1 = 1.7 9.0 = 0.3 1.5 = 0.2 13 = 3.2 210 14 34 47
(3.3) (21) (9.5) (4.1) (9.0) (<0. 1) (0-3)
Todd's Dump 0.14 0. 1 1. 0.05 1.3 = 0.2 5.2 = 1.0 0.6 = 0.2 5.7 = 1. 1 110= Is 16 23
(1.4) (12) (2.7) 0 -3) (5-2) (0.0 (0-1)
Hanna Reef 0.09 0.11 0.09 0.6 = 0.5 1.2 = 0.3 0.6 = 0.2 4.3 = 0.8 50 = -.0 16 18
(0.9) (11) (4.5) (0-6) (1.2) (<O. 1) (0.0
Confederate Reef 0.10 0.09 0.05 0.7 = 0.6 2.8 = 0.2 0.7 = 0.3 3.0 = 1.4 77 = 9.6 13 1-1
0.0) (9.4) (2.6) (0.-) (2.8) (<O. 1) (0.0
Offats Bayou 0.50 0.40 0.09 3.2 = 1.8 10 = 2.' 1.0 0.3 8.7 :t 3.4 160 44 50 63
(510) (40) (4.7) 13-22) (10) (0.2)
Tampa Bay
Old Tampa Say 0.17 0.32 0.28 0.4 = 0.2 -1.4 = 1.6 0.2 0.2 4.0 = 0.8 55 8.5 48 51
0 .'?) (32) (14) (0-4) (2.4) (<O. 1) (0-1)
Knight Airport 1.5 0.33 0.08 7.6 = 3.7 36 = 15 Z.0 = 1.0 30 = 13 580 230 5 97
(15) (33) (4.2) (77.6) (37) (<0.1) (0-6)
Papys Bayou 0.09 0.10 0.05 0.4 = 0.1 3.0 = 0.'? 0.3 = 0.2 6.1 = 2.6 75 27 1.4 1
(0.9) (10) (2.6) (0.4) (3-0) t<0.1) (0.1)
Narvaez Park 0.26 0.14 0.15 1.3 = 0.2 '.3 = 1.8 0.6 = 0.2 8.9 = 3.1 120 31 24 33
(2.6) (14) (7-5) (1.3) (7.3) (<0.0 (0.2)
ockroach Bay 0.20 0.29 0. J0 0.4 = 0.2 3.0 = 1. 1 0.2 = 0.' 2.8 = 1.: 49 20 36 40
(1.0) (29) (5-0) (0.4) (3-0) (< 0. 1) (0-1)
Mullet Key Bayou ;D ND ND 0.3 = 0.2 1.6 1 0.3 0.2 = 0.1 3.3 :t 2.0 38 14 - 1.0
C

(0.3) (1.6) (<0. 1) (0.1)

Total :.3.'%8-TCDD equivalents (TEQs) are expressed in pg g-1 dry weight. Individual 2.3.7.8-TCDD equivalents are given in parentheses.
ND. none detected.
'Equal to the sum of all the measurable individual congeners.
bToW TCDD equivalent@ corresponding to the non-oriho-substituted PCB congeners.
'Total TCDD equivalents corresponding to (he sum of congeners 7, 126. 169, 105. 118, 1_28. and 138.

chlorinated 126 and 169 isomers are more resistant to meta- to 1.40076 of the total PCB load in Galveston and Tampa
bolic and chemical breakdown compared to the lower chlo- bays, respectively.
rinated PCB 77, [1]. On average, the sum of these three highly As expected from the small contributions of planar con-
toxic congeners ranged from 0.26 to 0.62176 and from 0.31 geners to the total commercial PCB mixtures (16-201, these

Table 2. Concentrations of selected non- and mono-ortho-iubstituied PCB congeners
in bivalves reported in the literature

PCB congeners (pg.,& dry wt.)
Non-oriho Mono-ortho Reference
Species Location 77 126 169 105 118 no.

Mussels' Hong Kong 590 <33 <4. 7 (71
(88) (<5.0) (<0.7)
Mussels' Hong Kong 4,700 330 45 (71
(700) (49) (6.8)
Mussels Long Island 400 3.300 8,000 124)
Mussels' Eastern Scheldt 430 87 12 2.900 10,000 110)
(64) (13) (1.8) (430) (1.500)
Oysters' Eastern Scheldt 200 40 7.3 1,900 4,500 1101
(30) (6-0) 0. 1) (280) (680)
Oysters Galveston Bay 530 520 211 8.200 13.000 This studv
Oysters Tampa Bay 370 200 110 1.700 8.900 This studv"

Reported concentrations were recalculated on dry-weight basis usine 15074 dry weight. Original concen-
trations are indicated in parentheses.

Significance of toxic PCBs in Gulf of Mexico oiql 005

congeners were detected at much lower concentrations than as well as their totals are fisted in Table 1. In Tampa and Gal-
some mono- and dqi-ortho-substqituted PCB congeners -e.g., veston bays, the total TE0qQs ranged from 13.5 to 52.qZ qpqg g-'
q105, q1q1q1, q12q1, and 138. Individually, the concentrations of and from 13.0 to 280 pqg qg-, respeqaively. The data indicate
these mono- and di-ortho congeners in oyster samples from that, except for the sample collected near the Houston Ship
Galveston and Tampa bays were I to 2 orders of magnitude Channel in Galveston Say, the TE0qQs in oysters from Tampa
higher than planar PCB concentrations (Table 1). and Galveston bays were similar. Oysters collected near the
Houston Ship Channel in Galveston Bay were clearly the
0qTCDD equivalents most toxic.
In a review, Safe q(3q1 discussed the environmental and Mono- and di-ortho-PCB congeners, derivatives of pla-
mechanistic considerations behind the development of the nar PCB congeners, are relatively less toxic but far more
toxic equivalent factor q(TEqF) concept. Safe proposed pro- abundant in environmental samples than their parent com-
visional TEF values of 0.01, 0. 10. and 0.05 for planar PCB pound and might, therefore. have a significant toxic environ-
congeners 4q7q7. 126, and 169, respectively. Similarly, Safe pro- mental impact. To assess the environmental significance of
posed provisional TqEF values of 0,00q1 and 0.000q12 qfor these congeners in terms oqf TCDD-qIqle effects in oyster am-
mono- and di-ortho-chqlorine-suqbstituted PCB congeners, re- pies from Galveston and Tampa bays. the calculated q2.3,7,8-
spectively. Recently, the validation and limitations of these TCD0qD equivalents corresponding to congeners 105, 118, 12q8,
factors have been discussed q122q). These TEF values are used and 138 were compared to those corresponding to planar
t
o convert the analytical results in TCDD or toxic equivalents congeners (Table 1). Contribution of congeners 105 Plus 118
116q(TEQsq) where to the total TEQs was as high as 45.4016. In contrast, the con-
tribution of di-ortho congeners to the total toxicity of the
TEQ qQPCBq1j - TEF,q) samples is negligible q(< 1 .007cq). The lesser toxicity of the di-
ortho congeners is a consequence of their reduced TC0qDD-
and i represents the individual PCB congener. like activity rather than lower concentrations. Congeners ' '77,
Calculated TEQs for the planar PCB congeners, in pqg g-', 126, 169, 105, and I 18 accounted for over 9q04qMo of the total
in oyster tissues collected from Galveston and Tampa bays TEQs encountered in a variety of biota samples [8, 1 qO.qZ3,-'4q1.

3 A

4 PCs 77 0

Pqa lie
-Z 5- Ica I= 0 - q-

6
0.00 0.01 0.02 0.03 0.04 0.05

k* (days

3. B

4q, q0 qPqCqa q7q7

qWq2 its
q% 5q. qP8qM q&4qW
PCs Ica

0 20 q40 q6q0 so 100 120 1q40

qSHL (days)

Fig. 4q2q. Depuraqtqion constant q(kd) and biological half-lives qtBHLq) of planar congeners compared to ranges qaqf qvaluqcq@ calculated for nonpqla-
nar PCBs. V4qiqluqeqs for selected mono-orqtqho-q@chlorine-subsqtituted congeners relevant to this quudqy are also q@hownq.

Most of Elie relative PCB toxicity encountered during this vironmental Toxicology. Springer- Vqerlag, New York, NY, pp.
study was associated with the presence of planar PCBs, par- 77-95.
cuqlarqly congener 126. In a recent study, Sericano et al. 1251 6. de Voogi, P., D.E. Wells. L. Rettlerqgardill and qU.A. Th. Brink.
man. 1990. Biological activity, determination and occurrence of
reported that planar PCBs 77q7 and 126 were depurated from planar, mono- and di-orLho PCBS. qInif. qJ. qEirviron. Anal. Chem.
the oyster tissue at a significantly lower rate than other PCB 40:1-46.
congeners within the same level of chlorination. That report 7. qKannan. N.. S. Tanabe. R. Tausqkaws and D.J.H. Phillips.
confirmed the findings of a previous study with transplanted 1989. Persistence of highly toxic coplanar PCBs in aquatic eco.
systems: Uptake and release kinetks of coplanar PCBs in green-
mussels M. However, not only the planar PCB congeners but lipped mussels (Perna viridis Linnaeus). qEnviron. Poqfqtr. 55:
also their mono-ortho derivatives show slower depuration 65-76.
rates than the bulk of PCB congeners in the corresponding 8. Schwartz. T.R.. D.E. Tiqdqlitt. qK.P. Feltz and P.H. Peterman.
Level of chlorination (Fig. 2). This might be of significant im- 1993. Determination of mono- and non-o,o'-chqlonne substituted
portance in projects such as the Mississippi oyster relaying poqlychlorinated biphenyls in Arocqlors and environmental sam-
ples. Chemosphere q26:1443-1460.
effort designed to transplant oysters from polluted to clean 9. Wells, D.E. and 1. qEcharri. 1992. Determination of individual
waters for a period oqf time before harvesting them for hu- chlorobiphenvis (CBsq), including non-ortho, and mono-oriho
man consumption [26]. Bohern and Quinn [27q1 reported that chloro substituted CBs in marine mammals from Scottish wa-
transplanting of shellfish from polluted to cleaner envqiron- ters. Int. qJ. qEnviron. Anal. Chem. 47:75-97.
10. de Boer. J.. C.J.qN. Stroack. W.A. Tmag and qJ. van der Meer.
ments has been used as a means of increasing harvestable 1993. Non-ortho and mono-ortho substituted chiorobiphenyis
yields of the hard-shell clam q(Mercenarqza mercenaria) in Nar- and chlorinated diqbenzo-p-0qdoxins and dibenzofurans in marine
ragansett Bay, Rhode Island. However, oysters that are al- and freshwater fish and shellfish from the Netherlands. Chemo-
lowed to depurate in a clean environment might show lower sphere q26:1823-1842.
concentrations of PCBs but still may retain significant 11. Serkano. J.L.. T.L. Wade. J.M. Brooks. E.L. Atlas. R.R. Fay
and D.L. Wilkinson. 1993, National Status and TrendsqMussel
amounts of the highly toxic congeners. Watch Program: Chlordane-related compounds in Gulf of.4qMex-
ico oysters, 1986-90. Environ. Pollut. q82:q23-32.
SUMMARY AqND CONCLUSIONS 12. MacLeod. W.D.. el al. 19q8q5. Standard analytical procedures of
the NOAA National AnaJytqicaq) Facility, 1985-1986. Extractable
The total TEQs in oyster samples from the Gulf of Mex- 7oxic Organic Components, 2nd ed. NOAA Technical Memo-
ico were estimated from the concentrations of planar PCB randum NMFS F/NWC-92. U.S. Department of Commerce,
congeners-i.e., 7q7, 126, and 169-and two mono-ortho- Washington. DC.
substituted PCB congeners - i.e., 10q5 and I 18 - using pub. 13. Sericano. J.L.. E.L. Atlas. T.L. Wade and J.M. Brooks. 1990.
NOAA's Status and Trends Mussel Watch Program: Chlorinated
qlished TEF values. As it has been discussed in previous pesticides and PCBs in oysters (qCrassostrea virginica) and sed-
studies for a variety of biota samples, most of the relative iments from the Gulf of mexico. 1986-1987..0qWor. Environ. Res.
PCB toxicity detected in oyster tissues was associated with 29:161-203.
14. qKrahn.0qM.M., et W. 1988. Standard analytical procedures of the
these congeners. The slower depuration rates reported for NOAA National Analytical Facility. 198'8. New qHPLC cleanuc
these congeners compared to other PCBs within Elie same and revised extraction procedures for organi Ic contaminants ..
level of chlorination suggest that most of the toxicity would Technical qMernorandurn. National Oceanic and Atmospheric
be retained by depurating oysters even though the total PCB Administration. Seattle. WA.
concentrations might have si'qgnqifqicantqly decreased. This might 1q5. qSericano. J.L.. A.M. EI-Husseini and T.L. Wade. 1991. Isola-
tion of planar polychlorinated biphenvis by carbon column chro-
have a significant effect on the applicability of some of the matography. Chemosphere q23:1541-1548.
shellfish industry practices such as oyster relaying. 16. Huckins. J.qN.. D.L. Suilling and J.D. Pett). 1980. Carbon-foarn
Chromatographic separations of non-o.o'-chlorine substituted
PCBs from Aroclor mixtures. qJ. Assoc. Off. Anal. Chem. 63:
REFERENCES 750-75q5.
17. qKannan. N., S. Tanabe. T. Wkirnoto and R. Tatsukawa. 198-
1 Safe, S.H. 1984. PoiN chlorinated biphenyls q(PCBs) and poly- Coplanar PCBs in Aroclor and Kanechlor mixtures. qJ. Assoc.
brominated biphenyls (PBBs): Biochemistry, toxicology and Off, Anal. Chem. 70:451-454.
mechanisms of action. CqRC Crit. Rev. qToqncol. 13:319-393. 18. Duinker. J.C.. D.E. Schutz and G. Petrick. 1988. .14ultidimeri-
Goldstein. J.A. and S.H. Safe. 1989. Mechanism of action and sional gas chromatography with electron capture detection for
struc(ure-activity relationships for the chlorinated dibcnzo-p- the determination of toxic congeners in polychlorinated biphe-
dioxins and related compounds. In R.D. Kqimbrough and A.A. nyl mixtures. AriaL Chem. 60:47q8-482.
Jensen. eds.. Halogenated Bqipqheqiqtqyqlqs, 0qTeqrpqhenyqiqs, Naphthalenesq. q19. Schulz. D.E., G. Petrick and J.C. Duinkqer. 1989. Compqlqeqtqtq.
Dqi0qbqeqnzodioxins and Related Products. Elsevier, New York. NY. characterization of polqychqlorqinqated bqiphqenqyl congeners in com-
pp. 239-293. mercqiaqJ Aqroc0qlor and Clorphqen mixtures by multidimensional gas
3. Safe. Sq.H. 1990. Poqlyqch0qloqrinated biphenvqiqs (4qPC8qBsq). dibqeqnzoq-p- c0qhromaqtographyq-eqlecqtron capture detection. 2qEqnqvqiroqn. Scqiq. Tech-
dioxin, 8q1PCDDq,qlq, dibqenzoluran, 0qIqPCDFq,0q), qand related qcom, not. 23:0q152q-0q159q,
pounds: Environmental and mechanistic considerations which 20. Anderson. J.W. 1991. Determination of congeners of poqlvcqhqloq-
support the development of toxic equivalency factors (TEFqs). rinatqed bipherqyqis in reference materials. 0qJ. High 4qRqe5oiq. Chro-
C0qRC Cqrqit. Rey. 4qToxqicoql. 21:4q51-88q. mqaqrogrq. 370:369-372.
4. Safe. Sq.H. 194q86. Comparative toxicology and mechanisms of 21. Hawker. D.W. and D.W. Coqnqsqiqell. 104q"8. Octqaqnoql-waqter Parti-
action of poqlycqh0qlorinated dibenzo-pq-dioxins and dqiqbqeqnzofurans. tion coefficients oqfq'poqlychlor0qinaqted bqiphqeny0ql congeners. 0qEqnvq,-
Annu. Rey. Pqhqarmqaco0ql. 4qToxicoql. 26:3q71-399. qrqoqn. Set. 0qTecqhqnoqlq. 0q22:382-387.
5. Hayes. M.A. 1987. Carcinogenic and muqLagenic effects of q22. Safe. Sq.H. 1992. Development. validation and lqimqitaqtqiorqiqb of
PCBs. In S. Safe and 0q. Hutzqingqer, eds.. Environmental Toxin toxic equivalency factors. Chemoqspqhqerqe q25:61-6q4.
4qSeqnqeqs q1, Pqo6q@qycqhql . .... wed qBipqhqnyqlqs q1PCqB:sq)q.q-,6qWqaqnq7mqaqlqian qaqnd Eqn- 23q, Smith, L,Mq*q, T.R, Schwartz and Kq. qFeftzq. q10q904qw, Dqetem,n q1, 'on

and occurrence of A4qHH-active polychlorinated biphenyls. 1992. Environmental significance of the uptake and depuration
2,3.7,q1q1-qmtrachloro-p-dioxin and 2.3.7,q8-teirachlorodibenzofu- of planar PCB congeners by the American oyster (Crassostrea
ran in Lake Michigan sediment and biota The question of their virginica), Mar. Pollut. Bull. q24:537-543.
reistive toxicological significance. Chemosphere 21:1063-1085. 26. Skupien. 8qL 1990. The great Mississippi oyster relay. Gulqfwalch
24. Hoag, C.S.. qB. Bush and J. Mao. 1992. Coplanar PCB in fish 2:4-5.
mussels from manne and estuarine waters of New York State. 27. Boehm. P.D. and J.G. 4qQuiq". 19177. Tqhe persistence of chroni-
qEcotoxicoL Environ. qSaqf. q23:q)18-131. cally accumulated hydrocarbons in the hard sheqfql claqmqWerce-
2q3. Swienw, J.4qL. T.L Wak, A.M. EqI-qHosseqmi and qI4qM. Brooks. naria mercenaria. Mar. Biol. 44:227-233.

Reprint 3

Distribution and Sources of Organic
Contaminants in Tidal River Sediments
of the Washingtong D*C* Area

Terry L. Wade,, David J. Vennsky, Eli
Reinharz and Christian E. Schlekat

Distribution and Sources of Organic Contaminants in Tidal River Sediments of the Washington,
D.C. Area.

Terry L. Wade

Geochemical and Environmental Research Group, 833 Graham Road, Texas A&M University,

College Station, TX 77845 (Tel: 409-690-OW5),

David J. Velinsky

Interstate Commission on the Potomac River Basin, Suite 300, 6110 Executive Blvd., Rockville, MD

20852 (Tel: 301-984-1908),

and

Eli Reinharzl, Christian E. SchlekatF

Maryland Department of the Environment, Toxics Registries and Analysis Program, Baltimore, MD

21224.

Present Addresses:

'National Oceanic and Atmospheric Administration, Damage Assessment Group, Washington, D.C.

20852 ( 'rel: 202-606-8000)

'Science Application International Corporation, 165 Dean Knauss Drive, Narragansett, RI, 02882

(Tel: 401-782-1900)

I
I Wade et al.
I Running head:
T.L Wade et al. Organic contaminants in tidal river sediments
I
I
I
I
I
I
I
I
I
I
I
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I

10
I

Wade et al.

Abstract

Concentrations of aliphatic, aromatic and chlorinated hydrocarbons were determined from 45

surface-sediment samples taken from the Tidal Basin, Washington Ship Channel, and the Anacostia

and Potomac rivers in Washington, D.C. In conjunction with these samples, selected storm sewers

and outfalls also were sampled to help elucidate general sources of contamination to the area.

All of the sediments contained detectable concentrations of aliphatic and aromatic

hydrocarbons, DDE, DDD, DDT, PCBs, and chlordanes (oxy, cf, and 'y-chlordane and cis+ trans-

nonachlor). Sedimentary concentrations of most contaminants were highest in the Anacostia River

just downstream of the Washington Navy Yard, except for total chlordane which appeared to have

ppstream sources in addition to storm and combined sewer runoff. This area has the highest

concentration of storm and combined sewer outfalls in the river. Potomac River stations exhibited

lower concentrations than other stations. Total hydrocarbons (THQ, normalized to the fine grain

fraction (clay+sUt, < 63 gm), ranged from 120 to 1900 ;Lg g7l fine grain. Ile hydrocarbons were

dominated by the unresolved complex mixture (UCK with total polycyclic aromatic hydrocarbons

(PAHs) concentrations ranging from 4 to 33 jug g" fine grain. Alkyl-substituted compounds (e.g., Cl

to C4 methyl groups) of naphthalene, fluorene, phenanthrene+anthracene, and chrysene series

dominated the polycyclic aromatic hydrocarbons (PAHs). Polycyclic aromatic hydrocarbons,

saturated hydrocarbons, and the unresolved complex mixture (UCM) distributions reflect mixtures of

combustion products (i.e. pyrogenic sources) and direct discharges of petroleum products, Total PCB

concentrations ranged from 0.075 to 2.6 Ag g-I fine grain, with highest concentrations in the

Anacostia River. Four to six Cl-substituted biphenyls were the most-prevalent PCBs. Variability in

Wade et al.

the PCB distribution was observed in different sampling are-as, reflecting differing proportion of

Arochlor inputs and degradation. The concentration of all contaminants was generally higher in

sediments closer to imown sewer outfalls, with concentrations of THC, PAHs, and PCBs as high as

6900, 620, and 20jug g-1 fine grain, respectively. Highest PCB concentrations were observed from

two outfalls that drain into the Tidal Basin. Concentrations of organic contaminants from sewers

draining to the Washington Ship Channel and Anacostia River had higher concentrations than

sediments of the mid-channel or river. Sources of PCBs appear to be related to specific outfalls,

while hydrocarbon inputs, especially PAHs, are diffuse, and may be related to street runoff.

Whereas most point souice contaminant inputs have been regulated, the importance of non-

point source inputs must be assessed for their potential addition of contaminants to aquatic

ecosystems. This study indicates that in large urban areas, non-point sources deliver substantial

amounts of contaminants to ecosystems through storm and combined sewer systems, and control of

these inputs must be addressed.

Wade et al.

Introduction

Currently existing National Oceanic and Atmospheric Administration (NOAA National

status and Trends (NS&T), and Environmental Protection Agency (EPA) Environmental Monitoring

and Assessment-Near Coastal (EMAP-NQ programs are concerned with determining current

contaminant status of coastal areas of the United States. These programs are designed to provide an

overview of the current status and long-term trends for relatively large geographical areas. However,

there remains a need for specific studies to address questions of a more local concern. In order to

reduce the input of contaminants to aquatic systems, such as the tidal system around Washington,

D.C., regulations of point sources have been implemented. With the reduction of point source inputs,

non-point sources such as storm water runoff now must be assessed as input sources of contaminants

to aquatic systems.

The paper describes one portion of a study (see Velinsky et al. and Schlekat et al., this issue)

to determine the distribution of sedimentary organic contaminants on a local scale in the Washington,

D.C. area, employing validated analytical methods. Also, an important objective of this study was

to establish the importance of combined and storm sewers as sources of contaminants to the sediments

of the area. To accomplish this objective, selected storm and combined sewers were sampled, and

organic contaminant distributions compared between sewer and river sediments.

Sampling and Analytical Methods

The study area (Fig. 1) and sampling design has been described in detail in Velinsky et al.

(1993). Sediment samples were obtained from the Tidal Basin (TB), Washington Ship Channel

(WSC), Kingman Lake (KL), Potomac River (PR) and Anacostia River (AR) in June 1991 (Fig. 1).

Sediments taken directly in front of storm and combined sewer outfalls were also collected from the

Wade et al.

Anacostia River, Washington Ship Channel, and Tidal Basin. In addition, selected sewers were

sampled up-pipe Cl.e. entering the sewer line via street manholes) from the outfall in these locations

(Velinsky et al. 1993). To accomplish this, D.C. Department of Public Works sewer maps were used

to select specific sewer lines that drain into each area. Also, at one station in the Tidal Basin and

Potomac and Anacostia rivers, three separate samples of three grabs each were taken within a radius

of approximately 5 m to assess small-scale spatial variabflity.

In the Potomac River, four stations were sampled from the mouth of Rock Creek to the

confluence of the Anacostia and Potomac Rivers and the Washington Ship Channel (Fig. 1). We did

not obtain samples from sewers that drain into the Potomac River. In the Washington Ship Channel,

five stations were sampled along the eastern side of the channel. Seven stations were sampled in the

Anacostia River, all on the northwestern side of the river outside the center channel.

Sediments were collected with a stainless steel petite-Ponar grab sampler (0.023 mF) rinsed

with acetone at the beginning of each day. ne upper 2 to 3 centimeters of sediment not in contact

with the sides of the sampler were placed into a pre-cleaned pyrex-glass bowl. Ibis process was

repeated three times. Sediments were mixed with a pre-cleaned stainless steel spoon until

homogeneous in both texture and color, placed into pre-baked (420 OC for 12 hours) glass jars, and

covered with pre-baked aluminum M. Between collections, the sampler was cleaned of any sediment

and rinsed with ambient water at each station.

Grain size and total organic carbon determination are described in Velinsky et al. (1993).

Sediments were extracted using the methods described in Wade et al. (1988). All internal standards

(surrogates) were added to the samples prior to extraction and were used for quantification.

Approximately 10 grams of freeze-dried sediment were soxhlet-extracted with methylene chloride.

Wade et al.

The solvent was concentrated to approximately 20 ml in a flat-bottomed flask equipped with a

three-ball Snyder column condenser. Ile extract was then transferred to Kuderria-Danish tubes,

which were heated in a water bath (6(rQ to concentrate the extract to a final volume of 2 ml.

During concentration of the solvent, dichloromethane was exchanged for hexane.

The extracts were fractionated by alumina:silica gel (80-100 mesh) open column

chromatography. Silica gel was activated at 17(rc fbr 12 hours and partially deactivated with 3%

(y/w) distilled water. Twenty grams of silica gel were slurry packed in dichloromethane over 10

grams of alumina. Alumina was activated at 400*C for four hours and partially deactivated with I %

(v/w) distilled water. The dichloromethane was replaced with pentane by elution, and the extract was

applied to the top of the column. ne extract was sequentially eluted from the column with 50 ml of

pentane (aliphatic fraction) and 200 ml of 1: 1 pentane- dichloromethane (aromatic-pesticide fraction).

The fractions were then concentrated to 1 ml using Kuderna-Danish tubes heated in a water bath at

60-C. Each set of ten samples included a procedural blank and a spiked sample that were carried

through the entire analytical procedure.

Aliphatic hydrocarbons were analyzed by gas chromatography in the splitless mode using a

flame ionization detector (FM). A 30-m x 0.32-mm I.D. fused silica column with DB-5 bonded

phase Q&W Scientific Inc. or equivalent) was used, with the chromatographic conditions providing

baseline resolution of the n-C,.,/pristane and n- C@s/phytane peak pairs. Ile five calibration solutions

were in the range of 1.25 to 50 ;Lg mr. Ile internal standard,s (surrogates) for the aliphatic

hydrocarbon analysis were deuterated n-alkanes with 12, 20, 24 and 30 carbons, and were added at

approximate 10 times the method detection limit.

Aromatic hydrocarbons were separated and quantified by gas chromatography-mass

wade et al.

spectrometry (GC-MS) aM890-GC and HP5970-MSD). The samples were injected in the splitless

nwde onto a 0.25 mm x 30 ni (0.32 Am film thickness) DB-5 fused silica capillary column Q&W

Scientific Inc. or equivalent) at an initial temperature of 6(rC and temperature programmed at 12*C

min7l to 3WC and held at the final temperature fbr 6 minutes. Ite mass spectral data were acquired

using selected ions for each of the PAH analytes. IMe GC-MS was calibrated by injection of a

standard component mixture at five concentrations ranging from 0.01 ng/jul to I ng/;d. Sample

component concentrations were calculated from the average response factor for each analyte. Analyte

identifications were based on correct retention time of the quantitation ion (molecular ion) for the

specific analyte and confirmed by the ratio of the confirmation ion.

A calibration check standard was run three times during the sample runs (beginning, middle

and end), with no more than 6 hours between calibration checks. The calibration check was

confirmed to maintain an average response factor within 10% for all analytes, with no one analyte

greater than 25% of the known concentration. With each set of samples, a laboratory reference

sample (oil solution) was analyzed to confirm GC-MS system performance. The internal standards

(surrogates) for the PAH analysis were ds-naphthalene, dIO-acenaphthene, d,.-phemthrene, d,27

chrysene, and d,2-perylene, and were added at concentrations similar to that expected for the analytes

of interest.

The pesticides and PCBs were separated by gas chroma graphy in the splidess mode using an

electron capture detector (ECD). A 30-m. x 0.32-mm I.D. fused silica column with DB-5 bonded

phase (J&W Scientific or equivalent) was used. Four calibration solutions containing the pesticides

and the PCBs were used to generate a non-linear line fit with calibration standards in the range of 5 to

200 ng m171. 7be internal standards (surrogates) for pesticide and PCB analysis, added prior to

Wade et al.

extraction, were DBOFB (dibromooctafluorobiphenyl), PCB-103, and PCB-198. Ile

chromatographic conditions for the pesticide-PCB analysis were 100*C for I min, then 5*C Milo to

140*C, hold for I min, then 1.5C min7' to 2500C, hold for I min, and then 10*C min7l to 300*C and
a final hold of 5 min. Results and Discussions

Sediment= hydrocarbo

Sedimentary hydrocarbons concentrations were variable throughout the study area, probably

due to transport processes, biological and chemical differences between individual compounds (i.e.,

water solubility, volatility, and weathering and microbial degradation rates), and the differences in

input sources of these compounds. Total hydrocarbons concentrations (THQ in the Potomac River

sediments ranged from 110 to 167 jig g7' (Table 1). The highest concentration was at station PR-1

which is located near the mouth of Rock Creek (Fig. 1). In the Potomac River, the UCM was the

dominant THC component, averaging 84 � 0.04% of the THC. The polycyclic aromatic

hydrocarbon (PAHs) concentration are of particular interest because they have been shown to have a

significant effect on the mortality, abundance, and diversity of benthic organisms (Landrum et al.

1991; Kennish 1992). Sediment concentrations were highest at PR-1 (29 ;Lg S71 ) compared to other

river, basin, or channel sediments (excluding outfall or sewer sediment). Stations PR-2, PR-3, and

PR-4(a,b,c) had uniform PAH concentrations, averaging 3.6 � 0.4 Ag g7l (n=5, station PR-4 was

sampled in triplicate). The higher concentrations of both PAHs and the UCM indicate a greater

amount of anthropogenic hydrocarbons at PR-1, most likely due to runoff from Rock Creek, which

drains through the more residential center of Washington, D.C.

In the Tidal Basin, THC and PAH ranged from 169 to 613 Ag g' and from 0.4 to 11.6jug g7l

Wade et al.

respectively. The higher concentrations of PAH at TB-1 and TB-1.5 were associated with large

storm sewer and vehicular traffic on Kutz Bridge near TB-1.5. THC concentrations ranged from 120

to 467 ;Lg g' in Washington Ship Channel (WSC) sediments. The highest sediment concentrations

were at stations WSC-I, WSC-2, and WSC-3, located at the upper end of the channel. As in the

other areas, THCs were dominated by the UCM (UCM/THC a 95%), suggesting that the THCs

were composed mainly of weathered petroleum products (Farrington 1980). Sediment PAH

concentrations were fairly uniform throughout the channel with an overall average of 7.0 � 1.0 ug g-I

(n = 5).

To assess geographical trends of hydrocarbons in the Anacostia River, concentrations of

organic compounds are presented along a transect from KL-5, at the entrance to Kingman Lake in the

AR, to PR-4, which is located at the confluence of the Anacostia and Potomac rivers (Fig. 1; Table

1). 7bis transect includes WSC-6, located at the confluence of the AR and the WSC. Along the

river, at AR4, which is located just upstream of the South Capitol Street Bridge (Fig. 2),

concentrations of THC and PAHs reached a maximum of 1600,ug r' and 28 ;Lg g-' , respectively.

From AR4 to PR4, a substantial decrease occurred in the concentrations of both THC and PAHs.

At the most downstream station (PR4A), concentrations of THC and PAHs, 126 jug g' and 4.4 ;tg g-

I , respectively, were some of the lowest measured in this study. Similar trends also were fbund for

trace metals (e.g., Pb and Cd; Velinsky et al. 1993), indicating a substantial local source of sediment

contamination near the Washington Navy Yard and the South Capital Street Bridge (Fig. 1).

Several stations were sampled and analyzed in triplicate to assess the small-scale spatial

variability. Triplicate samples of three grabs each were taken within approximately 5 m of each

other. Tbe percent relative standard deviation (%RSD; � SD/mean X 100) for THC, SHC, and the

Wade et al.

UCM was all generally < � 15 % fbr the Potomac River (PR-4) and the Anacostia River (AR-5). In

the Tidal Basin (TB-5), total PAH concentrations agreed to within � 5% RSD (n-3); however,

concentrations of THC, SHC and UCM had higher concentrations for sample TB-5b. It is unclear

why the THC, SHC, and UCM were elevated in TB-5b. Trace metals, TOC, and grain size data

(Velinsky et al. 1993) were not elevated for TB-5b compared to TB-5a,c. Due to the close agreement

between TB-5a and TB-5c for both the SHC and UCM, the data for TB-5b is not included in the

average and fin-ther discussions. These results, along with the TOC and grain size data (Velinsky et

al. 1993), indicate that the variability of the "local" area is smaller than some of the geographic trends

between the various study areas.

One of the objectives of this study was to evaluate sources of organic contaminants to river

sediments in the Washington, D.C. area. Sediment samples were collected at the outfalls of selected

storm and combined sewers (1Ds with the prefix 0; Table 1) in the Tidal Basin, Washington Ship

Channel, and Anacostia River. Sediments also were taken from combined and storm sewers (IDs

with the prefix S; Table 1) that drain into these areas. Sediment hydrocarbons concentrations for

rivers, outfalls, and sewers were divided by the fraction of fine grain sediment (< 63 jLm) in each

sample (Velinsky et al. 1993).

Total hydrocarbons and total PAHs concentrations from outfall and sewer sediments from the

Tidal Basin and Washington Ship Channel were substantially elevated compared to sediments collected

away from the outfalls (Fig. 3). The PAH concentrations in outfall. samples ranged from 10 to 620

Ag 9*1 fine grain, with highest concentrations from one site in the WSC. These concentrations were

substantially higher than those found in mid-basin or channel sediments. Ibis suggests that a

dominant source of hydrocarbons to the basin and channel is runoff from numerous streets and

Wade et al.

highways in the area via the storm sewer system (there are no combined sewers in these areas). The

distribution of THC and PAHs at the outfalls indicated no specific storm sewer as the predominate

source of hydrocarbons to these areas, as opposed to the trace metal dam, notably Pb, which did

indicate specific outfalls (e.g., OTB-3&4, OAR-3) as major sources (Velinsky et al. 1993). It

appears that the input of hydrocarbons to the basin is diffuse, and may be related to the overall

vehicular traffic in the surrounding area.

While the gradients between outfall and sediment samples indicate the source of hydrocarbons

is from street runoff, the numerous marinas that border the eastern side of the WSC could also

contribute hydrocarbons to channel sediments. The input of hydrocarbons would be related to boating

activities, fuel spills, and engine exhaust, as well as from creosote-treated pilings used for the

construction of these marinas (Vouldrias and Smith 1986; McGee et al 1993).

In the Anacostia River (AR), five outfall and four sewer samples were obtained, allowing a

more comprehensive analysis of the sediment hydrocarbon distribution (Fig. 4). Of the four sewers

sampled, two are storm sewers (SAR-5 and SAR-6), and two are combined sewers (SAR-2 and SAR-

3); all were sampled as close to the river as possible. In most cases, the concenmations of THCs and
PAHs were highest in the sewer samples co'mpared to either the outfall or sediment samples (Fig. 4).

A comparison was made between hydrocarbon concentrations of three groups of river, outfall, and

sewer samples within the AR (Fig. 4). The material collected in the sewer is a possible source of

hydrocarbons at the outfall, and thus would most directly affect the sediments in the river at the

station closest to the outfafl. Total hydrocarbons and PAH concentrations were higher from all sewer

samples compared to their respective river samples (Fig. 4). This trend is particularly evident in the

series located near the Washington Navy Yard (i.e., series AR4, OAR-3, and SAR-5).

Wade et al.

Concentrations of THC decreased from 4500 at SAR-5 to approximately 2000,ug g*' fine grain at

both OAR-3 and AR4 (Fig. 4), while PAH concentrations decreased by a factor of 5 between SAR-5

and AR4. Ile decrease in THC and PAH concentrations in river sediments compared to sewer

samples may be due to both degradation and dilution with sediments having lower hydrocarbon

concentrations.

These results indicate that a major source of hydrocarbon contamination to the sediments of

the Anacostia River may be street runoff through the combined and storm sewer system of the area.

Gavens et al. (1982) showed that in an urban catchment basin near London (G.B.), up to a 3 fold

increase in sedimentary PAHs occurred due to urban runoff. Street dust, including material from

tires, road asphalt, and crankcase oils, are possible sources of hydrocarbons in this runoff. Wakeham

et al. (1980) compared the PAH content of various lake sediments in Switzerland to various urban

source materials, and concluded that street dust (e.g., asphalt and tire, and crankcase drippings) was a

major source of hydrocarbons to the sediments. Other sources, such as atmospheric deposition and

direct oil spills to the river, may be important, but the extreme concentration gradient between river,

outfall, and sewer sediment samples suggests that urban runoff is a major source. Samples taken

around station AR4, near the Washington Navy Yard, indicate that this may be the most severely

impacted area in the Anacostia River, and may be the most affected by runoff from the urban area of

Washington, D.C.

Molecular DutHbution of H)*ocarbons

Total sedimentary hydrocarbons consist of saturated hydrocarbons (SHC), polycyclic aromatic

hydrocarbons (PAH), and the unresolved complex mixture (UCM). Ile UCM contains co-eluting

Wade et al.

compounds that are not resolved by current capillary gas chromatographic techniques, and are thought

to be mainly alicyclic: hydrocarbons. Saturated hydrocarbons are the sum of normal alkanes from a-

C1. to n-Cu including the isoprenoids pristane and phytane, and PAHs are the sum of 44 individual or

groups of aromatic hydrocarbons. While PAHs are potentially more harmful to aquatic organisms

than SHC or UCM, the molecular distribution and abundance of the UCM, SHC, and PAH provides

information concerning the sources and transformations of hydrocarbons (Farrington 1980; Hites et

al. 1980; Wakeharn et al. 1980; Boehm and Farrington 1984; Boehm 1984; Pruell and Quinn 1985).

The UCM accounted for the majority of THC in sediments, outfall and sewer samples, with

minor contributions of both SHCs and PAHs. For most sediments the UCM accounted for a 95% of

the THC with little variation between sites. The abundance of the UCM at all collection sites indicates

that weathered petroleum products are a major component of hydrocarbon contamination in this area.

In the Potomac River however, the UCM comprised :9 90% of the SHC, indicating less of a

contribution of weathered petroleum hydrocarbons. The source of thd.UCM in all areas is most
likely runoff from streets and highways, although direct discharge of oil (i.e., small spills) cannot be

ruled out (Eganhouse and Kaplan 1981a; 1981b; Hoffman et al. 1983; 1984; Brown et al. 1985).

While the concentration and presence of the UCM indicates a weathered-petroleum hydrocarbon

source, the molecular distribution of PAHs can give an indication of the relative contribution of

hydrocarbons from petroleum versus combustion sources.

Low versus high molecular weight PAHs (i.e., LMW and HMW PAHs) are indicative of the

input sources of hydrocarbons (Farrington 1980; Boehm and Farrington 1984). Low molecular

weight PAHs are defined as 2 to 3 benzene ring compounds, including naphthalenes, anthracenes,

phenanthrenes, and dibenzothiophenes. High molecular weight PAHs, with 4 to 5 benzene rings,

Wade et al.

include compounds such as fluoranthenes, chrysenes, benzo[a]pyrene and dibenz[ah]anthracene. A

predominance of LMW over HMW PAHs indicates an oil source of hydrocarbons (Farrington 1980;

Boehm and Farrington 1984). Due to weathering and degradation processes, with time LMW PARs

would decrease in abundance relative to HMW PAHs. Also, the combustion of petroleum yields

PAHs with more HMW compounds.

In most sediments from this study, LMW PAH accounted for approximately 35% of the total

PAH (Velinsky et al 1992). In the Anacostia River, at stations AR-4 and SAR-5 however, LMW

PAH accounted for 60% and 90% of the total PAHs, respectively . Storm sewer SAR-5 empties into

the river near station AR-4 at the outfall OAR-3. Low molecular weight hydrocarbons accounted fbr

only 40% of the total PAHs; at station OAR-3. These results indicate a distinct source of petroleum-

derived hydrocarbons (e.g., oil) to the area just south of the Washington Navy Yard near the South

Capitol Street Bridge.

Substantial quantities of unsubstituted PAHs were found in all river, outfall, and sewer

sediments analyzed. Major compounds include alkylated phenanthrene-andiracene, fluoranthene,

pyrene, benz(a]anthracene, and benzopyrenes. Concentrations of alkylated fluoranthene-pyrene

ranged from 0.56 to 5.3 ILg g7, benz[alanthracene from 0.11 to 0.93 #g g-, and benzo[a+e]pyrenes

from 0.23 to 1.7 ;Lg g7' for all river sediment samples. Higher concentrations were found in outfall

and sewer samples (Velinsicy et al. 1992). The abundance of individual HMW PAH compounds in

most samples suggests that combustion products are also a source of the PAHs to the sediments of

this area (Youngblood and Blumer 1975).

The variations in individual PAH compounds reflect a mixture of combustion products (i.e.,

pyrogenic sources) and direct discharge of petroleum products. These distributions are similar to

Wade et al.

other urban areas (Farrington and Quinn 1973; Wakeham et al. 1980; Hoffman et al. 1983; 1984;

Eganhouse and Kaplan 1981b; Brown et al. 1985). Specific areas that indicate increased combustion

inputs of hydrocarbons include station PR-I near Rock Creek, stations WSC-1, 2, and 3, and the area

around AR-4 (Velinsky et al. 1992). Only in the Anacostia River, near the Washington Navy Yard

(i.e., AR-4), are direct inputs of petroleum a more significant component of the sediments.

Chlorinated Hydrocarbons

The concentration of a selected suite of chlorinated hydrocarbons were determined as part of

this study. Sediment concentrations of total chlordane (sum of oxy-, -f-, and a-chlordane and

cis +trans-nonachlor), total DDT (sum of 2,4'+ 4,4' forms of DDT, DDD, and DDE), and total

PCBs ranged from 5 to 150, 7 to 160, and 70 to 2200 ng gl, respectively, for river, basin or channel

sediments (Table 2). The highest sedimentary total chlordane levels from the Potomac River (43 ng

91 were near Rock Creek at station PR-I, with lower concentrations downstream. This site also
exhibited high concentrations 'of total DDT and PCBs compared to the other sampling sites in the

Potomac River. The highest concentrations of total chlordane, total DDT, and PCBs in the Tidal

Basin were found at stations TB-I and TB-1.5. These sites are located near the large storm sewer

oudWI that drains along Constitution Avenue and the Mall of the Smithsonian Institution. The

sediment concentrations of total DDT at these stations, 160 and 170 ng g', were some of the highest

measured in this study.' Concentrations of total chlordane, DDT, and PCBs in the Washington Ship

Channel were intermediate compared to the other study areas, with no distinct geographical

distribution (Table 2).

Higher concentrations of total chlordane were determined in the Kingman Lake area (e.g.,

Wade et al.

maximum at KL4 of 150 ng 91 and upper Anacostia River (Fig. 2) compared to farther

downstreauL Concentrations decreased to approximately 27 ng g*1 at PR-4A, located just south of

Hains Point in the Potomac River. This distribution, suggests a possible input source within or

upstream of the Kingman Lake area. In contrast, concentrations of both total DDT, PCBs, and

hydrocarbons reached maximum levels farther downstream in the Anacostia River at station AR-4.

Sediment concentrations of total DDT and PCBs were 124 and 2200 ng fl, respectively, at AR-4.

Numerous storm and combined sewers drain into this area, and these levels are probably a result of

these sources (see below). This location also has elevated concentrations of trace metals (Velinsky et

al. 1993), THCs, and PAHs. Below the South Capital Street Bridge and the Washington Navy Yard

(i.e., AR-4), concentrations of all sediment contaminants decreased to baseline levels. The distribution

of total chlordane indicates different input sources to the Anacostia River compared with other organic

and inorganic contaminants.

Concentr-ations of total chlordane, DDT, and PCBs in outfalls of the Tidal Basin and

Washington Ship Channel reached levels of 260, 4200 and 18000 ng g-I fine grain respectively, and

are substantially higher than those determined in the mid- basin or channel sediments (Fig. 5).

Outfalls OTB-3 and OTB-4 had extremely elevated concentrations in the Tidal Basin. The sewer

(STB-2), taken on two separate occasions, had concentrations of total chlordane, DDT, and PCBs

only slightly elevated compared to basin sediments. This sewer is a sanitary sewer running along

15th St., S.W., servicing the Bureau of Engraving and Printing and the Department of Agriculture.

The material in this sewer line would most likely not impact the Tidal Basin, and would eventually be

sent to Blue Plains Wastewater Treatment facility fbr treatment and disposal. Total chlordane, DDT,

and PCB outfall sediment concentrations in the Washington Ship Channel were is high as, WO, 2100,

Wade et al.

and 5200 ng g"' fine grain, respectively. Highest total chlordane and DDT concentrations were fbund

at OWSC-3, while total PCB concentrations were highest at all three upstream outfWls (i.e., OWSC-2

to OWSC-Rl; Fig. 5).

A substantial concentration gradient between sewers, outfalls and sediments of the Anacosda

River was observed for total chlordane, DDT, and PCBs (Fig. 6). Concentrations in this series were

as high as 660, 400, and 6400 ng g` fine grain for total chlordane, DDT, and PCBs, respectively.

As with non-chlorinated hydrocarbons, a large decrease in concentrations was found between the

sewer, outfall, and sediments near station AR-4 (i.e., SAR-5 > > OAR-3 > > AR-4) (Fig. 6).

Similar decreases were observed in varying degrees for the other river, outfall, and sewer sediment

series within Anacostia River (Fig. 6). These data indicate that street and land runoff, as well as

possible combined sewer overflows, are sources of total chlordane, DDT,and PCBs to the sediments

of the Anacostia River.

Persistence of PCBs in aquatic sediments is due to their slow rate of degradation and

vaporization, low water solubility, and partitioning to particles and organic carbon (Kennish 1992).

Bacteria degrade PCBs, with the rate dependent on the position and degree of chlorination of the

biphenyl ring (Reutergardh 1980; Abramowicz et al. 1993; Rhee et al. 1993). Interestingly, the PCB

congener distribution patterns are not similar among sediments of this study area (Velinsky et al.

1992). In the Tidal Basin and Potomac River, congeners with six and seven chlorine substitutions

dominated, while congeners with four to six chlorines were the major component of the PCBs of

Washington Ship Channel and Anacostia River sediments. These results suggest two distinct sources

of PCB contamination in this study area. However, the selective degradation of PCBs with lower

chlorine contents can not be ruled out as the cause of the different distributions (Reutergardh 1980

Wade et al.

and others).

Sources of the pesticide DDT measured in the present study are elusive. Banned in 1972, and

with an approximate environmental half-life of 10 to 20 years (NOAA 1989; Woodwell et al. 1971;

Sericano et al. 1990), its detection, along with its breakdown products (i.e., DDE+DDD) in

sediments, is to be expected. Generally, (2,4'+ 4,4) DDE accounted for the greatest abundance of

the three forms of DDT, with approximately 70 to 90% of the total DDT in sediments as the sum of

DDE and DDD (2,4' + 4,4') forms. This distribution indicates an active degradation of DDT in the

sediments and/or inputs of already degraded DDT to the area. DDT can be degraded to DDD by

micro-organisms and phytoplaakton or to DDE via dehydrochlorination produced by biotic or abiotic

decomposition reactions (Fries 1972; Addison 1976; Gerlach 1981).

In all outfalls and sewers sampled in the Anacostia River, along with specific ones in the

Tidal Basin and Washington Ship Channel, (2,4'+ 4,4') DDT accounted for approximately 40 to

60% of the total DDT, and with the extreme concentrations measured at these sites, detrimental

biological effects could occur. Ile large sedimentary concentrations of (2,4+ 4,4') DDT at outfalls.

and in sewers is interesting given the apparent lack of any definitive recent inputs. It might be

expected that DDT would have been flushed through the sewer system 20 years after its ban. Schmitt

et al. (1985) suggested that DDT may be a contaminant in other pesticide mixtures; however, the

study of Schmitt et al. (1985) was conducted in cotton farming areas in the southwest U.S. and may

not be applicable to the District. Alternatively, it is possible that re-exposed soils from construction

projects could introduce DDT to the environment.

Technical chlordane is a pesticide, used fbr termites and cutworms, that is a mixture of

approximately 140 compounds. Due to its known health effects, sale of technical chlordane was

Wade et 9.

halted in 1988 after step-wise control of its uses. Alpha (ct)- and gamma (,y)-chlordane are the two

main components of technical chlordane. The different fbrms and breakdown products of technical

chlordane were fbund at all locations with the exception of oxy-chlordane, which was found in only

nine samples. Generally, oxy-chlordane was found in detectable concena-ations in specific outfall and

sewer sediment samples in the Tidal Basin, Washington Ship Channel, and Anacostia River, and

accounted for 3 to 14% (n=9) of the total chlordane. Oxy-chlordane is a breakdown product of

chlordane and is thought to be more toxic than the other forms of chlordane. Throughout the DC

area, y-chlordane was the major chlordane found in this study area with lesser amounts of a-

chlordane and cis+trans-nonachlor (Velinsky et al. 1992).

Co=arisons to other Studies

Comparisons of the data from this study to other studies is not straightforward. The variable

nature of the sediments (i.e., grain size, organic carbon, etc.) are often ignored or can not be

accounted fbr from other studies that did not report bulk sediment characteristics. Also, the selection

of specific studies can bias the interpretation between data sets. For this reason, only data from the

Chesapeake Bay and Delaware Bay will be utilized to give a regional assessment of sediment

contamination.

Concentrations of selected organics from the mid-Adantic region are compared in Table 3. In

the present study, station AR-4 in the Anacostia River exhibited the highest concentrations, while the

Potomac River sediments have some of the lower concena-ations (excluding outfall or sewer sediment

samples). Ile concentration of total PCBs in the Baltimore Harbor and Schuykill River (Philadelphia,

PA.) are much higher than the Washington, D.C. area. For all groups of organics, concentrations

Wade et al.

measured in this study are higher than those from the mainstem Chesapeake Bay, again reflecting the

effect of urban environments on adjacent sediments. Compared to other studies, the sediments of the

tidal freshwater Washington, D.C., area are moderately to highly contaminated, with the most severely

impacted area located in the Anacostia River near station AR-4.

Summary and Conclusions

7be geographic and spatial trends for sedimentary organic reveal specific areas of concern

within the tidal freshwater section of the upper Potomac estuary. 17hese locations are show increased

sediment concentrations of organic contaminants relative to adjacent locations, and within the entire

study area of the Potomac and Anacostia rivers. In many cases, both trace metals (see Velinsky et al.

1993) and organics exhibit the same geographic trend. Substantial concentrations of organics such as

hydrocarbons (e.g., PAHs), PCBs, and DDTs were observed in many areas, such as near the

Washington Navy Yard (AR-4), near the mouth of Rock Creek in the Potomac River (PR-1), and

upper Washington Ship Channel (WSC-I to WSC-3). Concentration gradients between sewer, outfall,

and river sediment samples strongly suggest that urban runoff is a major non-point source of these

contaminants to the sediments. For certain constituents like THC and PAH, the outfall sediment

concentrations indicate a diffuse distribution related to the ubiquitous nature of their sources (I.e.,

fossil fuel combustion, crankcase oils etc.), while other contaminants, such as PCBs, have

distributions that suggest more of a source input through specific outfalls. 7be distribution of total

chlordane, which was markedly different than other organic contaminants, suggests inputs upstream of

the Washington, D.C. area. Also, the analyses of a limited number of benthic: clams (Corpicula sp.)

from selected sites indicates that the contaminants found in the sediments are bioavailable (Velinsky

Wade et al.

et.al. 1992) and may cause a biological response (Schlekat et al. 1993).

Large urban areas are non-point sources and deliver substantial amounts of organic

contaminants to ecosystems through their sewer system runoff. With the decrease in point source

contaminant inputs due to effective regulation, non-point source inputs must be assessed for their

potential addition of contaminants to aquatic systems. Also, the toxicity of these sediments must be

considered when making management decisions that might release or redistribute these contaminants.

Organic contaminant concentrations found in this urban area are moderate to high, and may exert

adverse effects on local ecosystem (see Schlekat et al. 1"3).

Wade et al.

Acknowledgments

We thank Carlton Haywood (ICPRB), Beth McGee (MDE), and Tom Jackson (GERG) for

technical assistance and help with the field sampling. Bob Cuthberson of the Marylod Geological

Survey provided the vessel and support during sampling. 717his project was funded by the Department

of Consumer and Regulatory Affairs, Water Hygiene Branch, of the District of Columbia and

additional support was provided by the Interstate Commission on the Potomac River Basin. C.

Dalpra provided helpful editorial comments. T'he opinions expressed are those of the authors and do

not necessarUy represent the opinions or polices of ICPRB and MDE.

Wade et al.

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Dearth, M.A. and R.A. Hites. 1991. Complete analysis of technical chlordane using negative

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Gerlach, S.A. 198 1. Marine Pollution: Diagenesis and '17herapy. Springer-Verlag, New York, 218 p.

Hites, R.A., R.E. Laflamme, I.G. Windsor, J.W. Farrington, and W.G. Deuser 1980. Polycyclic

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Hoffman, E.J., G.L. Mills, J.S. Latimer, and J.G. Quinn. 1983. Annual input of petroleum

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Hoffman, E.J., G.L. Mills, J.S. Latimer, and I.G. Quinn. 1984. Urban runoff as a source

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MD.

Kennish, M.J. 1992. Ecology of Estuaries: Anthro22genic Effects, CRC Press, Boca Raton, FL,

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Landrum, P.F., BT Eadie, and W.R. Faust. 1991. Toxicokinetics and toxicity of a mixture of

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Pruell, RJ. and J.G. Quinn. 1985. Geochemistry of organic contaminants in Narragansett Bay

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Sawhney, B.L., C.R. Frink, and W. Glowa. 1991. PCBs in the Housatonic River: Determination and

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Schlekat, C.E., B.L. McGee, D.M. Boward, D.J. Velinsky, and T.L. Wade 1993. Biological effects

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D.C. area. Estuaries (Submitted).

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of ft= metals to tidal river sediments of Washington, D.C. Estuari (submitted).

Wade et aL

Voudrias, E.A. and C.L. Smith. 1986.'Hydrocarbons pollution from marinas in estuarine sediments.

Estuarine Coastal and Shelf Scienc , 22: 271-284.

Wade, T.L., E.L. Atlas, J.M. Brooks, M.C. Kennicutt 11, R.G. Fox, J. Sericano, B. Garcia-Romero, and

D. DeFreitas. 1988. NOAA Gulf of Mexico Status and Trends Program: Trace organic contaminant

distribution in sediments and oysters. Estuaries, 11: 171-179.

Wakeham, S.G., C. Schaffner and W. Giger. 1980. PAHs in recent lake sediments 1. Compounds having

anthropogenic origins. Geochimica Cosmochimica Act , 44: 403-413.

Woodwell, G.M., P.P. Craig, and A.J. Horton 1971. DDT in the biosphere: Where does it go.. Scienc ,

174: 1101-1107.

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homologous series in soUs and recent marine sediments. Geochimica Cosmochimica A , 39: 1303-1314.

Wade et al.

Table 1. Sedimentary concentrations of hydrocarbons from the various study areas*.

Sta. M. PAH SHC UCM THC

King= Lake

KL-I 16.1 17.7 911 944

KL-2 15.3 14.9 1000 1030

KL-3 14.2 15.2 2090 2120

KL-4 10.3 15.9 1270 1300

KL-5 9.8 27.9 952 890

Awcosda River

AR-I 14.4 12.7 902 929

AR-2 15.1 22.1 1370 1410

AR-3 13.2 12.1 856 981

AR-4 28.3 31.0 1540 1590

AR-5A 9.6 10.7 794 804

AR-6 5.7 6.2 350 362

OAR-I 23.7 26.2 1460 1510

OAR-2 28.6 21.6 876 926

Wade et al.

ShL ID. PAH SHC ucm THC

OAR-3 23.6 14.8 394 432

OAR-4 19.1 15.5 1190 1230

OAR-6 36.9 6.1 117 160

OAR-Rl 11.5 7.5 581 600

SAR-2 32.1 9.7 469 511

SAR-3 5.8 2.2 393 401

SAR-5 39.6 25.4 901 966

SAR-6 8.7 7.5 500 516

Washington ship QMDCI

WSC-1 7.2 8.4 385 400

WSC-2 7.2 8.8 451 467

WSC-3 6.3 6.2 430 443

WSC-5 8.7 6. 1 106 121

WSC-6 5.6 17.3 281 304

OWSC-1 9.9 66.2 604 680

OWSC-2 44.2 36.1 952 1030

OWSC-3 130.0 6.6 293 430

Wade et al.

St& ED. PAH SHC ucm THC

OWSC-RI 78.3 54.5 4080 42 10

SWSC-2 4.4 3.7 555 563

Potomac River

PR-l 29.1 5.9 132 167

PR-2 3.6 13.5 110 127

PR-3 3.7 13.4 93 110

PR4A 3.6 13.0 109 126

TiM Buin

n-l 11.6 3.7 380 395

TB-1.5 9.8 14.8 595 620

TB-2 3.8 3.5 162 169

TB-3 8.7 19.3 300 327

TB-4 4.9 12.2 439 456

TB-5A 4.8 19.5 954 978

TB-6 3.8 3.9 171 179

OTB-I-l 6.9 1.2 86 94

OTB-1-2 8.0 10.7 285 304

Wad' e et al.

Sta. ID. PAH SHC uCM THC
OTB-2 10.6 3.0 143 177

OTB-3 5.0 5.9 449 460

OTB-4 11.6 22.1 629 663

OTB_5 10.6 22.0 739 771

STB-2-1 9.0 12.1 1490 1500

STB-2-2 8.6 11.3 %5 985

*Concentrations inag per gram dry weight. PAH-polycyclic aromatic hydrocarbons; SHC-

saturated hydrocarbons; UCM-unresoIved complex mixtm; THC-total hydrocarbons.

Station Ms. Akr6ng with the prefix (0) indicate samples that were taken directly in-front

of an sewer outfall, while the prefix (S) indicates samples that were taken in a sewer.

Stations AR-5, PR-4 and TB-5 were sampled and analyzed in triplicate and the average

value is reporte&

Wade et al.

TaWe 2. Conamtrations of total cWordane, DDT, and PCEs from the various study

SbL M. Chlordane DDT PCB

King= lAke

KL-I % 36 650

KL-2 110 65 530

KL-3 120 61 460

KL-4 ISO 76 520

KL-S 140 78 .660

Anacostia Rim

AR-I 140 78 710

AR-2 91 56 510

AR-3 110 77 770

AR-4 89 120 2200

AR-5A 58 55 490

AR-6 28 29 220

OAR-I 120 110 390

Wade et al.

ShL M. Chlordane DDT PCB

OAR-2 120 100 1300

OAR-3 33 44 940

OAR-4 93 261 480

OAR-6 38 320 340

OAR-RI 23 54 140

SAR-2 5 58 89

SAR-3 26 23 75

SAR-S 140 69 790

SAR-6 17 26 1500

EASAJ922100 Shi2 ChAuncl

WSC-1 14 42 390

WSC-2 19 36 330

WSC-3 18 30 310

WSC-5 28 36 300

WSC-6 17 15 140

OWSC-1 39 51 m

OWSC-2 64 58 3200

Wade et al.

Sta. M. CWordane DDT PCB

OWSC-3 130 450 880

OWSC-RI 30 150 2800

SWSC-2 5 7 260

Potomac Riv
'PR-1 42 100 270

PR-2 7 10 68

PR-3 5 7 73

PR-4A 9 11 70

Tidal Basin

TB-l 25 160 610

TB-i.5 17 170 500

TB-2 6 23 110

73-3 14 88 250

TB-4 8 76 240

TB-SA a 39 190

Tj" 7 29 150

OTB-1-1 4 58 110

Wade et al.

SUL M. Chlordane DDT PCB

OTB-1-2 14 120 400

OTB-2 7 150 240

OTB-3 10 75 1300

OTB-4 50 goo 3400

OTB-5 15 so 380

STB-2-1 10 43 730

STB-2-2 38 91 290

*Concentrations in ng per S= dry weight. Station Ms. starting with the

prefix (0) indicate samples that were taken directly in-front of an outfall,

while the prefix (S) indicates samples taken in a sewer. Stations AR-5, PR-4,

and TB-5 were sampled and analyzed in triplicate, these data are the average.

Chlordane is the E of a + -f-chlordane and cis + traw + nonachlordane;

DDT is the E of DDD + DDE + DDT (2,4'+ 4,4' forms); PCB is the E of

77 congeners.

Wade et al.

Table 3. Comparison of adected organic data frons various shmes in the region.!

PCBS PAIb DDT Chlordanes lAcation Sow

68-2203 4-29 7-160 5-155 Washington, 15T. '17his Stu y9

4.80000 NW ND ND Baltimore Harbor EPA (1987)

< 100 - 2400 ND < 10 - too 0-70 Schuykill River, PA. EPA (1987)

ND ND ND ND Potomac Estuary MDE (unpub. datar

7-96 0.03-1.11 0.2-4.8 0.2-2.4 Lower Ches. Bay NOAA (1991)

1-100 0.04-0.93 0.2-6.2 0.1-10 Middle Ches. Bay NOAA (1991)
OD
I-W 1-450 0.07-5.3 4.9-21.7 0.6-8.1 Upper Ches. Bay NOAA (I"l)

Concentrations of PCBs, DDTs. and chlordane are in ng per gram, and PAHs am in #g per gram dry weight. "Only river or basin sediment samples are
presented for this study. *ND - No data. 'Maryland Department of die Environment.

Wade et al.

Figure Captions:

Figure 1. General study area indicating the locations of Tidal Basin, Washington Ship

Channel, Kingman Lake, and the Potomac and Anacostia rivers. Arrows located around the

shoreline indicate locations of outfall and sewer samples.

Figure 2. Hydrocarbons and chlorinated-hydrocarbons in sediments of the Anacostia River.

Transect is from the mouth of Kingman Lake (KL-5) to the confluence of the Anacostia and

Potomac rivers (PR-4).

Figure 3. Outfall, sewer, and basin or channel sediment series of the Tidal Basin and

Washington Ship Channel: Total PAH and Hydrocarbons.

Figure 4. OutfWl, sewer, and river sediment series in the Anacostia River: Total PAH and

Hydrocarbons. The bottom panel highlights specific sewer and outfall series of the river.

Figure 5. Outfall, sewer, and basin or channel sediments of the Tidal Basin and Washington
Ship Channel: Total chlordanes', DDTs, and PCBs.

Figure 6. Outfkll, sewer, and river sediments of the Anacostia River: Total chlordanes,

DDTs and PCBs. Ile bottom panel highlights specific sewer and outfO series of the river.

9EORGETC

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A Anacostia River (AR)
o Kingman Lake (KL)
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Scale:
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40 2000
[M PAH ED THC E]UCMI

30 1500

20 --1000

10 ..500

0 0
5 AR-1 AR-21'AR-3 AR4'AR-S'AR-6 WSC-d PR-4

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40 - -

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10 400

09 5 200

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20 Washington Ship Channel 800
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Ft@
88

Reprint 4

Pistribution and Sources of Trace Metals
in Tidal River Sediments of Washington,
D.C,

David J. Velinsky, Terry L. Wade, Christian E.
Schlekat, Beth L. McGee and B.J. Presley

Distribution and Sources of Trace Metals to Tidal River Sediments of Washington, D.C.

David 1. Velinsky,

Interstate Commission on the Potomac River Basin, Suite 300, 6110 Executive Blvd. Rockvule, MD

20852 (Tel: 301-994-1908)

Terry L. Wade

Geochemical and Environmental Research Group, Texas A&M University, College Station, TX

77845 (Tel: 409-690-0095)

Christian E. Schlekat', Beth L. McGee2

Maryland Department of the Environment, Toxics Registries and Analysis Program, Baltimore, MD

21224, and

B.J. Presley

Department of Oceanography, Te xas A&M University, College Station, TX 77845

(Ttl:409-945-5136)

Present Addresses:

'Science Application International Corporation, 165 Dean Knauss Drive, Narragansett, RI 02882

(Tel: 401-782-1900)

2EJniVersity of Maryland, Wye Research & Education Center, Box 169, Queenstown, MD 21658

(Tel: 410 -827-8056)

Abstract Velinsky et al.

Fifty-four bottom sediments were collected from the Potomac and Anacostia rivers, Tidal

Basin, and Washington Ship Channel in June 1991 to define the extent of trace metal contamination

and elucidate source areas of sediment contaminants. Sediment samples also were collected directly

in front of and within major storm and combined sewers that discharge directly to these areas. Trace

metals (e.g., Cu, Cr, Cd, Hg, Pb and Zn) exhibited a wide range in values throughout the study area.

Sediment concentrations of Pb ranged from 32.0 to 3630 Ag Pb g-1, Cd from 0.24 to 4.1 Ag Cd g-1,

and Hg from 0.13 to 9.2 jug Hg g-1, with generally higher concentrations in either outfall or sewer

sediments compared to river bottom-sediments. In the Anacostia River, concentration differences

among sewer, outfall, and river sediments, along with downriver spatial trends in trace metals suggest

that numerous storm and combined sewers are major sources of trace metals. Similar results were

observed in both the Tidal Basin and Washington Ship Channel. Cadmium and Pb concentrations are

higher in specific sewers and outfalls, whereas the distribution of other metals suggest a more diffuse

source to the rivers and basins of the area. Cadmium and Pb also exhibited the greatest enrichment

throughout the study area with peak values located in the Anacostia River, near the Washington Navy

Yard. Enrichment factors decrease in order of Cd > Pb > Zn > Hg > Cu > Cr. Between 70 and 96 %

of sediment-bound Pb and Cd were released from a N27purged IN HC1 ]each. On average, :9 40%

of total sedimentary.Cu was liberated, possibly due to the partial attack of organic components of the

sediment. Sediments of the tidal freshwater portion of the Potomac estuary reflect a moderate to

highly contaminated area with substantial enrichments of sedimentary Pb, Cd and Zn. Ile sediment

phase the contains these metals indicates the potential mobility of the sediment-bound metals if they

are reworked during either storm events or dredging.

Velinsky et al.

Introduction

Sediment contamination problems have been documented for an increasing number of marine

and freshwater areas in the U.S. (Lyman et al. 1987; NAS 1989; NOAA 1990). Sediments are a

major reservoir fbr anthropogenic contaminants (e.g., trace metals) due to the particle-reactive

behavior and low water solubility of many pollutants (Young et al. 1985; Olsen et al. 1982). Trace

metals in sediments can affect aquatic life as well as recreation and human health by entering the food

chain (i.e., animal and plant life). Also, restrictions on the handling and disposal of contaminated

sediments may raise the cost of dredging navigational waters to prohibitive levels. It is therefore

imperative to have an accurate assessment of the extent of sediment contamination in a given location

and imowledge of the source(s) of the pollutants.

There are few published data on the distribution and sources of potentially toxic inorganic and

organic chemicals in the tidal freshwater rivers of the Washington, D.C. area. Studies by Pheiffer

(1972) and Martin et al. (1981) indicated that the concentration of trace metals were highest around

the District of Columbia and decreased downstream. Recent studies in the urban Potomac and

Anacostia rivers have shown a wide range in organic and inorganic contaminant concentrations with

limited areas of higher metal concentrations OCPRB 1990).

Direct dumping, urban runoff, atmospheric deposition, and industrial and municipal

discharges, as well as upstream runoff are some possible sources that contribute to the loadings of

anthropogenic chemicals to riverine and coastal sediments. River runoff includes contributions from

chemical weathering and erosional processes as well as upstream anthropogenic sources. While the

extent of direct dumping is difficult to assess, 01senholler (1991) estimated that urban runoff (e.g.,

sava runoff) represents a major source of trace metals to the tidal Anacostia and Potomac rivers. In

Velinsky et al.

older cities like the District of Columbia, a major source of trace metals and other contaminants is

runoff from combined sewer outfalls (00s). Ilerefore, runoff and overflows through CSOs may

have a substantial impact on the sediment quality in the Anacostia and Potomac rivers.

Ille spatial distribution of anthropogenic chemicals may help identify their source areas.

C;ertain chemicals, for example, may have diffuse sources yielding distributions with no consistent

geographical trend. Other chemicals, however, may have a specific source (i.e., point source) from

either an industrial or municipal facility or chemical spill that would be indicated by higher

sedimentary concentrations in a specific area. Different geographical trends may be reflected not just

in concentration gradients but also by the distribution within certain groups of metals. The objectives

of this study are to determine geographical trends, elucidate possible source areas, and discuss the

sediment speciation of trace metals around the District of Columbia. To accomplish this, sedimentary

.concennflons, of trace metals will be compared to concentrations in sediments sampled from sewers

lboth combined and storm) that drain into each respective area.

General Study Area

The District of Columbia (DQ lies along the fall line at the boundary between the Atlantic

Coastal Plain and the Piedmont Plateau, and is at the head of navigation of the Potomac estuary (Fig.

1). 7be western and northern sections of the DC area are part of the Piedmont, which is underlain by

deformed meta-sedimentary and meta-igneous rocks. From the mid-section of the city to the south is

the Coastal Plain which contains unmetamorphosed fluvial and marine sediments (Reed and

Obermeier 1989).

Presently, there are three major rivers or streams in the DC area: the Potomac and Anacostia

rivers, and Rock Creek, which drains into the Potomac River just south of Georgetown (Fig. 1).

Velinsky et al.

Average yearly flows for the Potomac River at Chain Bridge, Anacostia River, and Rock Creek are

1.03 X 1010, 1.16 X 101, and 5.5 X 10" ml yr', respectively. Even though the drainage areas of the

Anacostia River (310 km@ and Rock Creek (160 km@ are small compared to the Potomac River (e.g.,

at Chain Bridge, 29600 km@, both water bodies drain predominantly urban environments.

During the past 200 years, the DC riverscape has been altered by sedimentation, dredging,

and filling (Williams 1989). The Tidal Basin (surface area of 0.4 km@, with an average depth of

approximately 2 m, receives inputs from the Potomac River as well as storm water runoff and

atmospheric deposition. The Washington Ship Channel, located in the southeastern section of DC, is

connected to the Tidal Basin in the north section via a floodgate and to the Anacostia River at the

southern end (Figure 1). The center of this channel has been dredged in the past with bottom depths

rw&g from < I m to approximately 8 m. The Washington Ship Channel is bordered by a park on

the western side and residentiallcommercial development on the eastern side.

The flow of the Anacostia River is controlled by streamflow of the Northeast and Northwest

branches, which join at Bladensburg (MD). The tidal waters in the lower Anacostia River, South of

Bladensburg, have a long residence time (e.g., 35 days) due to the large volume relative to the runoff

)of the river. Therefore, it resembles a lake more th an a river (Scatena 1987), and allows suspended

sediments to settle within the tidal portion of the river. Sedimentation rates are reported to be 3.2 g

cm:* yr' or 1.9 cm yrI on a dry-sediment basis (Scatena 1987). While the center channel of the

Anacostia River has been dredged in the past, depths outside the channel generally range from 0.5 to

5 m.

7bere is potential for historical contamination of the sediments in the study area due to past

shipping and boating uses, and inputs via combined and storm sewer runoff. Approximately 30 storm
and six combined sewers discharge into the lower Anacostia River (i.e., south of the Kingman Lake

Velinsky et al.

area to Greenleaf Point at the mouth of the Washington Ship Channel). These sewers drain an area of

approximately 14 1=2, or 22% of the drainage area of the Anacostia River within the District of

Columbia. Approximately 54% of the total drainage area of the Anacostia Basin is urban (lCPRB

1988).

Numerous storm sewers (no combined) drain into the Tidal Basin and Washington Ship

Channel. Of the six outfalls at the Tidal Basin, the largest drains the Constitution Ave. and

Smithsonian Mall areas. The nine storm sewers that empty into the Washington Ship Channel drain

an area from approximately Independence Avenue (Smithsonian Institution), 13th Street, and 4th

Street, in southwest Washington, D.C. Numerous marinas also line the upper Washington Ship

Channel.

Sampling and Analytical Methods

River and outfall sediment samples were obtained from the Tidal Basin (TB), Washington

Ship Channel (WSQ, Kingman Lake (U), Potomac River (PR) and Anacostia River (AR) in June,

1991 (Fig. 1). In the Tidal Basin, six stations were sampled with six additional samples taken at the

mouth of specific outfalls (OTB) that enter the basin. At one station (TB-5), three separate samples

of three grabs each were taken within a radius of approximately 5 m to assess small scale spatial

variability.

In the Potomac River, four stations were sampled from the mouth of Rock Creek to the

confluence of the Anacostia and Potomac rivers and the Washington Ship Channel (Fig. 1). No

samples were obtained from sewers that drain into the Potomac River. In the Washington Ship

Channel, five stations were sampled along the eastern side of the channel. Seven stations were

occupied in the Anacostia River. Anacostia River samples were taken on the northern side of the

Velinsky et al.

river outside the main center channel. As in the Tidal Basin, one station from the Potomac and

Anacostia rivers (PR-4 and AR-5, respectively) was sampled in triplicate (i.e., 3 separate samples of

3 grabs each).

Outfall and sewer sediment samples also were obtained from both the Anacostia River and

Washington Ship Channel (Fig. 1). In the Washington Ship Channel, four outfall sediment samples

(OWSC) were obtained in conjunction with one sample from a sewer (SWSC) that drains along Maine

Ave., S.W. In the Anacostia River, six outfall sediment samples (OAR) were obtained as well as

fbur (one combined and three storm) sewer samples (SAR) from various locations along the river. In

Kingman Lake, a total of four sediment samples were obtained (Fig. 1), but no storm or combined

sewer samples or outfall samples.

A Hydrolab Surveyor H was used to collect dissolved oxygen, temperature, condudivity, pH,

and water depth just above the sediment surface. Sediments were collected with a stainless steel

petite-Ponar grab sampler (0.023 ml) that was acetone rinsed at the beginning of each day. The

sampler was inspected for possible cross-contamination (i.e., sediment from previous station) and

rinsed with ambient water at each station. The top 2 to 3 centimeters of sediment not in contact with

the sides of the sampler were removed and placed into a pre-cleaned Pyrex-glass bowl. This process

was repeated three times until sufficient sediment was obtained.

Sediments were mixed with a pre-cleaned stainless steel spoon until homogeneous in both

texture and color. Trace metal and grain size samples were placed into separate Zip-loc plastic bags.

Sediment aliquots for acid-volatile sulfur (AVS) were sampled first'and placed into 50 ml plastic

centrifuge tubes and quickly frozen using dry ice (-78*C). All other samples were placed in coolers at

approximately 4"C while in the field. Once on shore, sediment samples for metal and AVS analyses

were placed in a freezer at -209C, whil e samples for grain size were kept at VC.

Velinsky et al.

All materials coming in contact with the samples were either glass or metal. All glass bowls

were soaked in 0.5N HCI overnight, rinsed with distilled deionized water (DDW) and solvent rinsed

with methanol, dichloromethane, then hexane (Burrick and Jackson, Inc.) and allowed to air dry in a

bood. All metal utensils were washed similarly but without using the dilute acid rinse.

SedimeW= trace metals. Analyses for trace metals were identical to NOAA Status and Trends

techniques (Brooks et al. 1988) and are briefly outlined. Samples were digested in 50 ml closed

all-teflon *bombs* (Savillex Co.). Accurately weighed sediment aliquots (ca. 200 mg) were digested

at 13M in a mixture of nitric, perchloric and hydrofluoric acids. A saturated boric acid solution was

then added to complete dissolution of the sediment and the digest was brought to a known volume.

Standard reference materials and blanks were digested and analyzed with every batch of samples.

Concentrations of iron (Fe) and zinc (Zn) were determined by flame atomic absorption

spectrometry (AAS), while sediment concentrations of cadmium (Cd), chromium (Cr), copper (Cu),

and lead (Pb) were determined by a Perkin-Elmer Zeeman 3030, equipped with an HGA-6W furnace

and AS-60 autosampler. Standard reference materials (e.g., NIST and NRCQ and spiked samples

were used to evaluate analytical performance. Based on 10 separate analyses of the reference

materials over the course of the project, the accuracy and precision of the analyses are approximately

10 % for all metals.

Mercury (Hg) was determined by cold vapor AAS on an aliquot of the same digest used to

determine other trace elements following a "head space" sampling procedure (Brooks et al. 1988). A

Laboratory Data Control Co. UV monitor with a 30 cm path length cell was used for Hg

amin2tionS.

Glassware, plasticware, and reaction vessels were cleaned first by soaking in Micro cleaning

solution for 24 hrs and then rinsed with distilled water. Glassware and the reaction vessels were then

Velinsky et al.

soaked in an acid bath (50%v/v HN03) for 24 hrs, rinsed with distilled deionized water (DDW), and

air dried in a laminar flow hood in a dust free environment. Other plasticware used in these

procedures were either used only a single time or reused after washing with Micro solution,

appropriate acids (i.e., either HCl or HNO@, depending upon resistance to attack) and DDW.

Acid Extractable Metals. Frozen sediment samples were quickly thawed and homogenized, with

aliquots (ca. 1-2 grams) placed into pre-cleaned and tared 50 ml centrifuge tubes. Samples were

accurately weighed and rapidly frozen using liquid nitrogen then stored at -2M until extraction. Wet

and dry weights were determined from separate aliquots of the sediment mix.

For extraction, samples were placed in a 112-purged glove bag and allow ed to thaw. De-

aerated IN HCl (Baker Intra-analyzed grade) was added to a volume of 25 ml and the centrifuge

tubes were tightly capped. Ile samples were removed from the glove bag and mixed on a Vortex

mixer fbr one hour. After centrifugation and filtration to separate the solids, samples were

transferred to pre-cleaned screw cap polyethylene bottles and the metals analyzed by AAS.

While this leaching technique is not specific for a given sediment phase (Tessier et al. 1979),

it should provide an indication as to the potential mobility (Forstner 1979) and possible biological

avaflabUity of the trace metals (Luoma and Jenne 1976; Luoma 1983; Di Toro et al. 1990). Trace

metals released under the conditions used in this study may derive from the exchangeable, carbonate,

amorphous Fe/Mn oxides, and metal sulfide sediment phases along with a fraction of the organic

component of the sediment (Tessier et al. 1979; Pickering 1981). Malo (1977) showed that a cold

0.3N HCI solution extracted a significant fraction of the metals from surface coatings and only

minimml structural components are attacked. In this regard, a cold IN HCI solution was shown to

dissolve only natural and synthetic hydrous amorphous iron oxides, whHe leaving more crystalline

oxides (e.g., magnetite, goethite, and hematite) intact (Chao and Zhou 1983). During this study,

Velinsky et al.

sampling and extraction (i.e., in a N2-purged glovebag), exposure of the sediments to air was kept to

M*n*M11m. Furthermore, field experiments showed no loss of acid-volatile sulfur (AVS) during

sampling in the field (Velinsky unpublished data). Therefore, the contribution of metals that are

bound or precipitated to the monosulfide phase should also be extracted using IN HCl (Rapin et al.

1986).

To monitor precision and recovery of metals, several replicates of an in-house sediment

standard (HS-2, collected from the Mississippi River Delta) were included in the preparation. Two

unspiked replicates were analyzed, along with four replicates that were spiked with known amounts of

analytes prior to sample processing. Two blanks were included to evaluate contamination which was

insignificant compared to the concentrations observed.

Acid Volatile Sulfur. Acid volatile sulfur, predominantly iron sulfide, was determined by the method

of Cutter and Oatts (1997). In brief, 20-80 mg of frozen sediment (wet/dry weight ratio determined

-on a separate aliquot) was extracted using 0.5N HCI and the evolved hydrogen sulfide (H2$) was

purged from the solution and trapped in a glass U-tube filled with Porapak QS, immersed in liquid

nitrogen. After 15 min of purging and trapping, the U-tube was removed from the liquid nitrogen to

volatilized the H2S, which was chromatographically separated from other volatile compounds prior to

detection by a photoionization detector. Detector signals were processed by a HP-3390A digital

integrator/plotter.

Calibration of the detector was accomplished using a known quantity of anhydrous sodium

sulfide (Alfa Products). Samples were run in either duplicate or triplicates and precision was

generally beau than 10% as relative standard deviation.

Q=ic Carbon and Grains Size, Total organic carbon (OC) was determined by infra-red absorption

after combustion in an 02stream, using a LECO WR-12 Total Carbon System. Sediment grain size

Velinsky et al.

was determined by the procedure of Folk (1974), utilizing sieving to separate gravel and sand

Mwtions from the clay and silt fractions. The latter fractions were subsequently separated by the

pipette (settling rate) method. Detailed descriptions of the methods utilized in measuring OC, CaC03

and grain size are reported in Brooks et al. (1988).

Results

Sediment Organic Carbon and Grain Siz

Organic carbon (OC) concentrations ranged between 2.5 and 6.4% on a dry-weight basis (dw)

fbr all river and basin sediment samples with an average. of 4.0 � 0.9 % OC (� standard deviation;

Table 1). Highest concentrations were observed in Kingman Lake and the Tidal Basin. Outfall

sediment samples exhibited a greater range in OC concentrations than bottom sediments, with

concentrations ranging from 0.7 to I I% OC. This wide range most likely reflects both the different

ible sources of OC and the physical sorting of particles (both size and composition) during runoff
possi

events.

The grain size distribution in the study area was fairly uniform, with river sediments

predominately in the clay and silt size fractions (< 63 Am; Table 1). At a few stations, the sand

fraction accounted for between 25 and 30% (e.g., WSC-5, PR-I and TB-3) of the total sediment.

These locations may be areas of stronger currents in which fine-grain sediments do not settle. Outfall

and sewer sediment samples exhibited a greater range in grain size, reflecting the physical sorting of

particles in these often high-flow environments (rable 1).

Sewer sediment samples exhibited lower concentrations of OC than either river or outfall

sediments, with concentrations averaging 1.0 � 0.9% OC (n=5) for both storm and combined sewer

sediments. The lower concentrations of OC also were reflected in the grain size distribution of these

samples in which approximately 80% of the samples were in the sand-sized fraction. However, there

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Velinsky et al.

was no iignificant relationship (p > 0.01, n=50) between %OC and the fraction of fine-grain

sWiment for the entire data set.

M"ribution and GeogrVlic Trends of Sedimentaa Trage Metals

Ile distribution of individual trace metals, presented on a whole-sediment basis (i.e., weight

of metal per weight of dry whole-sediment), exhibited similar geographic trends within each river or

basin (Table 2). In the Potomac River, highest trace metal concentrations were found at station PR-1

(Table 2). Downstream from this station, sedimentary concentrations of all trace metals decreased,

with station PR-4 exhibiting some of the lowest concentrations throughout this study. While no

samples were taken upstream of Rock Creek as part of this study, previous studies (Pheiffer 1972;

JCPRB 1991) revealed lower concentrations in the upstream area (i.e., from Little Falls to

Georgetown).

.Concentrations of trace metals in Tidal Basin sediments were similar at all sites except for Cu

and Pb at station 7B-1 (Table 2). Sediment concentrations of Cu and Pb at TB-I were 120 and 204

pg g-I compared to 56.1 � 8.0 and 93.8 � 12.9'ag g' (average of five stations) in the basin,

respectively. Grain size variations were small and do not account for the differences between TB-I

and the other stations (Table 1).

Within the Washington Ship Channel, the distribution of all sedimentary trace metals reveal

highest values at the head of the channel (i.e., stations WSC-I, 2, and 3) with decreasing

concentrations downstream (Table 2). Lead concentrations decreased from elevated values of 183 and

125 ;tg Pb g-I at WSC-I and WSC-3, respectively, to a low of 48.3 ;Lg Pb g-I at WSC-5. At station

WSC-6, located at the confluence of the Washington Ship Channel and the Anacostia River, all trace

metals incriased in concentration from those at WSC-5.

Results from the Anacostia River are presented as a transect from KL-5, located outside

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Velinsky et al.

Kingman Lake in the river, to PR-4, located just south of Hains Point at the confluence of the

Potomac and Anacostia rivers (Fig. 1). This transect includes WSC-6, located at the confluence of

ibe Anacostia River and the Washington Ship Channel. From station KL-5 to AR-3 Oust upstream of

the Washington Navy Yard), concentrations of Hg, Pb, Zn, and Cd were fairly constant, while

concentrations of Cr and Cu increased slightly (Table 2; Fig. 2). Sediment concentrations of all trace

metals were highest at station AR-4. The increase in trace metal concentrations from KL-5 and AR-3

to AR-4 was greatest for Hg, Pb and Cd with increases of 206%, 179% and 60%, respectively.

Sedimentary concentrations of all trace metals decreased downstream of AR-4. The largest decreases

were exhibited by Hg, Pb and Cd; concentrations decreased 600%, 1000% and 450%, respectively,

from AR-4 to PR-4. The general decrease in trace metal concentrations was not related to grain size,

as 90% of the sediment from stations between AR-5 and PR-4 was composed of silt and clay.

Triplicate sediment sample analyses revealed little variability in the distribution of all trace

metals in the Iocal" area (i.e., within a 5 m radius). Relative standard deviations (� SD/mean X

100; n = 3) for all metals, TOC, and grain size were below 10%. Due to modest variations in grain

size, these results suggest that local-scale spatial variations in concentrations are small compared with

larger geographical changes observed in the Potomac and Anacostia rivers, and the Tidal Basin. This

may not be the case where sediment grain size and other bulk characteristics vary substantially.

Comparison between Sediments. Outfalls. and Sewers

For comparison of sedimentary trace metal concentrations between river, outfall and sewer

sediment samples, concentrations were divided by the fraction of fine-grain sediment in each sample
(i.e., sediment particles _-5 63,um). This Do;nwization procedure assumes that no contaminants are

associated with the sand-sized material, which only dilutes the level of contamination fbr a given

sample (NOAA 1991). Due to grain size differences between river, outfall, and sewer samples,

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Velinsky et al.

normalization of the data resulted only in small changes of river or basin sediment trace metal

wncentrations, but significant concentrations increases from the outfall and sewer samples.

Samples collected at five storm sewer outfaHs draining the Tidal Basin area had elevated trace

ontal concentrations compared with basin sediments (Fig. 3). Material collected at OTB-4 and OTB-

3 had the highest trace metal concentrations of the study (Fig. 3), with concentrations of Pb and Hg at

station OTB4 of 1.9% Pb (i.e., 19400 jLg Pb g` fine-grain) and 50 Ag Hg g` fine-grain, respectively.

As a comparison, sedimentary concentrations in the Tidal Basin ranged from 80 to 210jug Pb g" fine-

grain and 0.3 to 0.5 ;&g Hg gl fine-grain, respectively. Elevated concentrations of Cu, Cd, and Zn

also were evident at stations OTB-4 and OTB-3, compared with Tidal Basin sediments (Fig. 3). Two

sediment samples (STB-2) collected from a sanitary sewer that drains the area along 15th Street,

S.W., had extremely elevated concentrations of most metals (Table 2). Concentrations of Pb and Cd

ranged from I to 8 % Pb (fine-grain) and 5.5 to 24 jug Cd g" fine-grain, respectively. This location

was sampled twice during the study and concentrations of most metals exhibited substantial variation

(Fig. 3).

Trace metal concentrations of outfall sediment samples surpassed those in the sediments of the

Washington Ship Channel (Fig. 4). Concentrations of most trace metals increased from station

OWSC-1 to OWSC-3 then decreased slightly at OWSC-Rl. For example, Pb concentrations ranged

from 190 to 2400jug Pb g-I fine-grain between OWSC-I and OWSC-3, respectively, with highest

concentrations at station OWSC-3. One storm sewer was sampled in the Washington Ship Channel

area (SWSC-2). This sewer drains a small area between 9th and 10th Streets on Maine Avenue in

amthwest Washington D.C.. The runoff from this area eventually feeds a larger storm sewer line

dma flows into the Washington Ship Channel near it's head. Sewer-sediment trace metal

concentrations were greater than the channel sediments, but not as high as some of the outfall

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Velvinsky et al.

concentrations (Fig. 4). However, the concentration of Cd (17 Ag Cd g-1 fine-grain) in this sewer

sediment sample was substantially higher than samples from the outfall or channel (overall range

0.7 to 5.4 jLg Cd g" fine-grain).

As with the other sites, sediment concentrations of most trace metals decreased from sewer

and outfall samples to the river sediments within the Anacostia River (Fig. 5). This is most evident

between the storm sewer SAR-5 and its outfall OAR-3, and the river station AR-4. Station SAR-5 is

located "up-pipe" from the outfall OAR-3 which is slightly upstream from station AR-4. Within this

series, the concentration of Pb decreased from 970 ;Lg Pb g-' fine-grain at SAR-5 to 780 ;Lg Pb g"I

fine-grain at OAR-3. The concentration of sedimentary Pb decreased further to 480 ;&g Pb g" fine-

grain at AR-4. Sediment collected at station OAR-3 could be a mixture of outfall material and river

sediments, reflecting the lower concentrations found in the river. Similar trends at these stations are

noted for the trace metals Hg, Cd, and Zn (Fig. 5).

Dilute Acid-Leachable Metals

To obtain a better understanding of the sediment phase(s) that controls the distribution and

cycling of trace metals, 15 river and basin sediment samples were extracted with a IN HCI solution

under a N2-purged atmosphere.

A substantial fraction of sediment-bound Cd and Pb and to a lesser extent Zn and Cu, were

released from the acid leach (Table 3). For all sediments, between approximately 70 and 96% of the

total Cd and Pb was extracted, with an average of 84 � 8 % Cd and 83 � I I % Pb (n = 15), wh il e

overall only 63 � 8% of the total.sedimentary Zn was present in the IN HCI fraction. On average,

:9 40% of the total sedimentary Cu was liberated, possibly due to the partial attack of the organic

component of the sediment. Copper has been shown to be strongly complexed or bound to organic

nwter' nd the IN HCI solution may only partially release the Cu bound to this fraction. Oxidizing

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Velinsky et al.

acids or hydrogen peroxide would be better suited to release trace metals bound in the organic

fraction (Tessier et al. 1979; Martin et al. 1987). Only 25 � 4% of the total sedimentary Fe was

released by this technique indicating that a significant fraction of the Fe is either more crystalline

oxides, pyrite, or lattice bound. The Fe liberated from the sediments is most likely a combination of

both amorphous iron oxides and iron monosulfide phases (i.e., Fes).

Discussion

Information on the sources and geochemistry of trace metal contamination are critical to

management of the problem in the District of Columbia as well as other urban tidal freshwater

environments. In the following sections, these topics are discussed to help determine the fate of

contaminated sediments in urbanized estuaries.

Sources of trace metals in the Washineton. D.C.. area

The geographical distributions observed in this study indicate that sources located within the
Washington, D.C., area are major contributors to the levels of trace metals fbund in the sediments.

Land and street runoff through the area's storm and combined sewer system are major sources. Also,

drainage from stream flowing through the District of Columbia also can account for elevated levels

of metals in various sections of the Potomac and Anacostia rivers. In this regard, runoff from Rock

Creek to the Potomac River is the likely source of metals concentrations of the sediments around the

confluence (Fig. 1). Studies by Phieffer (1972) and 1CPRB (1990) in the area upstream of the

confluence revealed lower or similar concentrations of metals compared to downstream of Rock

Creek. The drainage area of Rock Creek is approximately 60% urban, with numerous storm water

disdbarges into the creek. These discharges are most likely the source of the higher concentrations

Axwd at the confluence.

The Tidal Basin sediments are most likely influenced by storm water sewers that empty into it

105

Velinsky et al.

(Fig. 1). The elevated concentrations observed at OTB-3 and 4 suggest that runoff through these

pipes is a major source of metals to the basin. These sewers drain the street area around 15th and D

Street, and. near Interstate 395, in southwest Washington, D.C. Because these pipes are storm

sewers, runoff from the numerous streets and highways in this area are a probable source. However,

the elevated concentrations of metals, especially Pb, in the sanitary sewer line adjacent to the basin

indicates an additional source. Prior to approximately 1990, the Bureau of Engraving and Printing
(BEP) discharged approx'imately 5 kg Pb day-' to the sanitary system. While this material was sent to

the Blue Plains Wastewater Treatment Plant (WWTP) for treatment and disposal, overflows into the

storm sewer system have been reported. (Friebele 1991). These overflows could be a possible source

of Pb to the Tidal Basin and other waterbodies within the District of Columbia. In 1990, a

pretreatment facility was completed to collect Pb and other contaminants before discharge to Blue

Plains WWTP. Although it is impossible to estimate the flux of trace metals to the basin from this

zdata set, the concentration gradients suggest that material flowing through these outfalls (i.e., samples

were taken directly in front of an outfall in the basin) are a dominant source of trace metal

contamination to the basin. Once the contaminants are introduced into the basin, dispersal of the fine-

grain material and associated trace metals yield the observed concentrations measured in the basin.

The upper end of the Washington Ship Channel is a semi-enclosed embayment in which the

water is partially flushed once per tidal cycle from water stored in the Tidal Basin. Numerous

bridges, both automotive and railroad, cross the upper end of the waterbody as well as four storm

sewers that drain into the upper end of the channel. As in the Tidal Basin, the concentration

differences between outfall and channel sediments, indicate that runoff from storm sewers is a major

source of trace metals. The higher concentrations of sedimentary trace metals at stations WSC-1,

WSC-2, and WSC-3 (Fig. 4) correspond to the higher concentrations at the outfall stations -OWSC-

106

Velinsky et a].

RI, OWSC-3, and to a lesser extent OWSC-2. Station OWSC-3 is near a storm sewer that drains the

area between 12th and 13th Streets, S.W. (Fig. 4). This area was the site of a railroad yard and is

the site of numerous construction projects.

Trace metals distributions in the Anacostia River suggests a substantial source between

stations AR-3 and AR-4 and that runoff through OAR-3, is a source of trace metal contamination to

this section of the Anacostia River. Ile concentration differences between sewer, outfall and river

sediment samples at SAR-2, OAR-2 and AR-2 also indicate a source of trace metals from the sewer

system (Fig. 5). Concentrations of Pb and Zn at SAR-2, for example, are 37000 and 2300,ug g-I

fine-grain, respectively. Concentrations decreased at OAR-2, the outfall of the combined sewer from

which SAR-2 was taken. This decrease is most likely related to the mixing of river sediments with

outfall material. Station AR-2 is located slightly upstream of the outfall, and has concentrations lower

than, or similar to, the outfall sediments.

The gradual increase in sediment concentration of Cr, Cu, and Zn from KL-5 to AR-4

suggests a more diffuse input for these metals. Runoff from the numerous combined and storm

sewers that empty into this area, along with upstream transport are possible sources. Also, the river

width increases in this segment of the Anacostia as it approaches the Potomac River. This increase,

along with the tides, may extend the residence time of the water, enabling particulate material and

associated-metals to settle to the bottom and incorporate into the sediments (Scatena 1987).

Trace metal concentration gradients between sewer, outfall, and river sediment samples

suggest that runoff from the stormwater and combined sewer system is a major source of

Cnntizninan to the Anacostia River, Washington Ship Channel and Tidal Basin (Figs. 3, 4, and 5).

In all areas, highest sediment concentrations of trace metals were measured ftm either the sewer or

outfall sediments. Concentrations of Pb, Hg, and Cd, fbr example, were as high as 37000, 50, and

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Velinsky et al.

24 #g g" fine-grain, respectively, in either the outfall or sewer samples. The trends in concentration

between sewer, outfall and river sediments are especially noted at station AR-4 in the Anacostia

River. While this data set indicates that runoff through the sewer system is a major source of trace

nutals to the area, the magnitude of this source compared to other sources (e.g., atmospheric

deposition, direct runoff, dumping) can not be quantified directly. Also, due to the nature and types

of samples taken it impossible to pinpoint a specific source of trace metals. However, these results

indicate specific areas of concern that warrant further investigation.

Dilute acid-leachable metals

Results indicate that the mobility of trace metals in these sediments may be substantial. As a

result of dredging or storm events, the redox environment of the surface sediment can change,

liberating weakly-associated trace metals. These changes can be the result of oxidation of reducing

sediment, and possible pH changes in weakly-buffered pore waters of freshwater sediments. These
metals could then be potentially more available for biological uptake and transpoirt via water. For

example, sediments in the rivers or basin contained a substantial amount of acid-volatile sulfur (AVS)

which only exists in reducing conditions (Table 1; Goldhaber and Kaplan 1975). This sulfide fraction

in these sediments is most likely metal monosulfides (e.g., XS, where X can be Fe, Cd, Cu, Pb, and

Zn). Aeration of the sediment could release metals into the pore waters until they are bound into

other phases such as Fe/Mn oxides (Lion et al. 1982). 71e oxidation of AVS (and pyrite) also could

lower the pH of the sediments enhancing the release of mews to the pore waters. These results

indicate that a substantial fraction of sedimentary metals could be released during events that rework

or u2nsport the sediments (i.e., bioturbation, storm events, and dredging).

Excess metals in the sediments around WasbingLQn. D.C.

A useful toot in expressing the degree to which a sediment is impacted from anthropogenic

108

Velinsky et al.

sources of trace metals is the enrichment factor (EF) (Trefrey and Presely 1976; Sinex and Heiz

1981; Helz et al. 1985; Windom et al. 1989). Normalization of the sediment to a reference element

wt associated with anthropogenic influences is a convenient approach to determine the degree of

sWiment contamination. Elements such as aluminum (Al) (Windom et al. 1989; Schropp et al. 1990),

lithium (M) (Loring 1990) and iron (Fe) (Trefrey and Presely 1976; Sinex and Helz 1981; Helz et al.

1985) have been used in the past. For this study, Fe was chosen as a normalizing element because 1)

it is the fburth most abundant metal in the earth with a crustal average of 3.5 % (Wedepohl 197 1); 2)

in most cases, anthropogenic sources are small compared to the amount of Fe naturally present; and

3) the ratio of metal to Fe is fairly constant in the Earth's crust. The enrichment factor is defined as:

EF = (X/Fe).A... /(X/Fe).j.. where X/Fe is the ratio of the trace metal (X) to the amount

of Fe in the sample.

In using the EF, a comparison to a sediment that is unimpacted by anthropogenic sources is

necessary [i.e., (X/Fe)...pj. Critical in this analysis is the choice of metal to Fe ratio for

"unimpacted" sediments. Past studies have compared sediments to the distribution of trace metals in

the earth's crust (Sinex and Helz 1981; Helz et al. 1985). While this approach is useful, it may not

account fbr natural variations in sediment types of different geological regions. One way to account

for this variability is to derive a ratio from munimpacted" sediments in the general area of interest

(Windom et al. 1989; Schropp et al. 1990). In the present study, all samples have the potential to be

impacted above natural levels. Therefore, data from samples taken in the Chesapeake Bay drainage

area (including the Potomac River) were used to derive metal abundances in the general area Q40AA
1991). Sixteen stations* in Chesapeake Bay that are relatively remote from such anthropogenic sources

as Baltimore Harbor and Elizabeth River were used. Ile ratios obtained from the regression of the

NOAA (1991) data are presented in Table 4 along with data from other areas. The ratios derived

109

Velinsky et al.

from Helz et al. (1985) are from the average composition of coastal plain deposits from northern

Chesapeake Bay, while the data from core 1314 (Goldberg et A. 1978) are from a location just south

of the mouth of the Potomac River. These data, along with values from average continental crust and

soils, are similar in magnitude (Table 4). Therefore, the average values were used to calculate the EF

fbr each metal.

The degree to which sediments in the study area are enriched in trace metals vary from metal

to metal. These variations can be due to a number of factors including 1) choice of (X/Fe).-ip.., 2)

biogeochemistry of the metal, and 3) sources of metals to the study area. While these calculations

use the average (X/Fe).*.,
,,, these values can vary. For example, the Cd/Fe value ranges from

0.01 to 0.09 while the Pb/Fe value ranges from 4.0 to 9.4. While these values may change the

magnitude of the EF, the geographic trends should not change. In light of these factors some general

trends and features are obtained ftom the EF data (Table 5).

The EFs are generally highest for Cd and lowest for Cr and Hg (Table 5), with intermediate

values for Pb and Zn. Except for Hg,. all trace metals are enriched in Kingman Lake and the upper

Anacostia River (KL-1 to AR-4). This is especially evident at station AR-4, which has the highest EF

in the study area for all trace metals. The EF decreases in order of Cd > Pb > Zn > Hg > Cu > Cr at

station AR-4. Other stations also indicate higher enrichments (and possible sources) of trace metals.

These include WSC-I, 2, and 3 in the upper end of the Washington Ship Channel; station PR-I at the

mouth of Rock Creek in the Potomac River; and TB-I in the northern embayment of the Tidal Basin.

The order of enrichment (i.e., Cd > Pb > Zn > Hg > Cu > Cr) for these stations are similar to AR-4

with some small variations between Hg and Cu.

The El's indicate potential anthro pogenic sources for trace metals in the sediments of the

Washington, D.C., area. These source materials are enriched in Cd and Pb relative to the other

110

Velinsky et al.

metals (Table 5). Areas that are impacted more by anthropogenic sources include the mouth of Rock

Creek, the northern embayment of the Tidal Basin, the upper end of the Washington Ship Channel,

md the upper Anacostia River and Kingman Lake. The enrichment in the Tidal Basin is likely due to

the large storm sewer that drains the area around the Mall of the Smithsonian and Constitution Ave.

In the Anacostia River, increased levels of enrichment at AR-4, just downstream of the Washington

Navy Yard, are proba bly due to the storm and combined sewers located just above this station. The

degree to which stations above AR-4 are enriched may be due to multiple sources and a net deposition

of sediment in this area. From KL-I to AR-4 there are numerous storm and combined sewers that

drain into this area, while in the Kingman Lake area (KL-l to KI-4), runoff from RFK Stadium and

the surrounding environment could be a major source of trace metals.

One of the goals of this study was to describe the extent and degree of contamination in this

area. -.Enrichment factors provide a geochemical basis for this description, while a more-subjective

description is obtained by comparing these data to concentrations in other areas. In this regard, the

selection of studies can bias the interpretation of the degree of contamination between locations. For

this reason, only data from the Chesapeake Bay and Delaware Bay will be utilized.

The ranges presented in Table 6, fbr the present study are for river and basin sediments only.

Sewer and outfall sediment samples are not included. Sediment concentrations of Cd, Cu, Hg, and

Ph in this study are higher than those found in the mainstem, Chesapeake Bay by a factor of 2 to 4,

dependent on the metal (Table 6). Concentrations of all metals are well below those found in

Baltimore Harbor and the Schuykill River (Delaware River basin). Compared with the estuarine

portion of the Potomac River Ci.e., MDE stations MLE2.2, XDA 11, and XEA659; MDE,

=published data), sediment concentrations of all metals are higher in the Washington, D.C. area,

reflecting its proximity to the urban runoff source.

Velinsky et al.

Summary and Conclusions

The geographic and spatial trends for trace metals in sediments reveal specific areas of

concern within the Washington, D.C. area. These locations are indicated by increased sediment

concenwations of trace metals relative to adjacent locations within the study area. In many cases,

most trace metals exhibited the same spatial concentration gradient with elevated concentrations

observed in many areas, such as near the Washington Navy Yard (AR-4), at the confluence of Rock

Creek and the Potomac River (PR-1), and in the upper Washington Ship Channel (WSC-1 to WSC-3).

Furthermore, concentration gradients between sewer, ourfall, and river sediment samples strongly

suggest urban runoff as the major source of these contaminants. Ilis is especially noted at station

AR-4 located just downstream of the Washington Navy Yard, near the South Capitol Street Bridge.

While the extreme gradient between the sewer, outfall, and river sediments at this location indicates

urban runoff as a source, past and present activities at the Washington Navy Yard could also

contribute to the. contamination of the area. 7be net result of all these possible sources are

substantially higher concentrations of all contaminants at AR-4. The large concentration decrease

downstream from this area suggests a possible higher source function at AR-4 and/or a greater

retention of upstream sources (i.e., fine-grain sediments) in this section of the river.

7be sediment of the urban Potomac and Anacostia rivers reflect a moderate to highly
contaminated location with substantial enrichments of sedimentary Pb, Cd, Zn,*and possible Hg. 7be

source of these metals is most likely urban runoff, however upstream sources and atmospheric

deposition can not be ruled out. 7be sediment phase or phases that contain these metals indicate a

potential mobility of these sediment-bound metals if the sediments are disturbed during, fbr example,

storm events and dredging.

112

Velinsky et al.

Admowledgernents

We thank Carlton Haywood (ICPRB) and Eli Reinharz (NOAA) fbr technical assistance and

belp with field sampling. Bob Cuthberson of the Maryland Geological Survey provided the vessel

ad support during sampling. 7banks to Marilyn Fogel (Geophysical Laboratory) and Greg Cutter

(Old Dominion University) for the use of laboratory and equipment during part this study. Jeff

Cornwell (University of Maryland) provided helpful comments on earlier versions of this manuscript.

lbanks to C. Dalpra for his editorial review and comments. 7bis project was funded by the

Department of Consumer and Regulatory Affairs, Water Hygiene Branch of the District of Columbia

with additional support provided by ICPRB. Ile opinions expressed are those of the authors and do

not represent the opinions or polices of ICPRB.

113

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Table 1. Bulk sediment characteristics for the various study arme.

Sta. M. TOC SAND SILT Clay AVS

M M M (pmol S e-dw)

Kinffman LAM

KL-1 4.05 12.8 50.3 36.9 12.9

KL-2 4.02 3.0 68.8 28.3 11.8

KL-3 4.06 0.20 67.1 32.7 12.7

KL-4 4.95 12.9 54.3 32.8 9.2

KL-5 6.08 11.1 54.6 34.3 4.8

Anacostia Riv

KL-5 6.08 11.1 54.6 34.3 10.8

AR-1 3.89 13.9 53.4 32.7 7.5

AR-2 3.99 0.54 63.2 36.2 7.5

AR-3 2.98 0.53 70.9 28.6 26.4

AR-4 4.30 14.0 59.2 26.9 17.0

AR-5A 3.75 0.69 71.4 27.9 ND

AR-6 3.57 0.86 67.7 31.4 ND

OAR-I 4.89 9.7 61.6 28.7 ND

OAR-2 3.44 9.0 68.2 22.8 ND

OAR-3 2.62 77.7 20.2 2.2 ND

OAR-4 4.68 10.7 61.3 28.0 ND

OAR-6 6.08 16.8 52.9 30.3 ND

OAR-RI 0.66 44.9 33.9 21.2 ND

120

Velinsky et al.

Sta. M. TOC SAND SILT Clay AVS
M M M M (stmol S s'-dw)

SAR-2 1.02 78.2 21.4 U.48 ND

SAR-3 0.28 95.6 14.2 0.15 ND

SAR-5 2.50 78.6 19.9 1.5

SAR-6 0." 77.4 20.9 1.7

Washin2ton Shi2 Channel

Wsc-I 3.21 1.5 72.2 26.3 83.0

WSC-2 2.89 0.42 $0.2 19.4 ND

WSC-3 3.37 0.33 94.2 15.4 47.6

Wsc-5 2.54 31.5 50.7 17.8 ND

WSC-6 3.74 0.71 69.8 29.5 ND

owsc-I 3.30 15.1 72.9 12.0 ND

OWSC-2 11.1 38.5 51.5 10.0 ND

OWSC-3 2.87 78.6 20.4 1.1 ND

owsc-Ri 8.76 39.3 23.3 37.4 ND

SWSC-2 0.37 75.5 24.0 0.55 ND

Potomac River

PR-1 3.86 21.9 45.8 32.3 ND

PR-2 2.41 13.2 51.9 35.1 ND

PR-3 3.92 9.6 55.0 35.4 ND

PR-4A 4.14 5.9 59.9 34.3 4.2

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Velinsky et al.

Sta. M. TOC SAND SILT Clay AVS
M M M (pmol S e-dw)

Tidal Basin

TB-1 6.37 2.9 69.9 27.2 1.0

TB-1.5 4.13 1.3 73.6 25.1 ND

TB-2 3.02 0.69 35.1 35.1 ND

TB-3 4.70 21.3 46.6 32.1 20.4

TB-4 3.30 0.45 76.5 23.1 ND

TB-5a 3.10 1.2 67.7 31.1 ND

TB-6 3.37 0.63 73.5 25.9 ND

OTB-1-1 ND ND ND ND ND

OTB-1-2 3.00 19.4 71.4 9.1 ND

OTB-2 1.98 $0.1 18.6 1.4 ND

OTB-3 1.99 $6.6 12.5 0.94 ND

OTB-4 1.88 81.3 16.5 2.2 ND

OTB-5 2.34 77.4 21.0 1.6 ND

M-2-1 9.69 60.7 33.5 5.8 ND

STB-2-2 11.0 49.6 47.9 3.6 ND

'Station IDs. starting with the prefix (0) indicate samples that were taken directly in front of

a wwor outfaU, while M's starting with the prefix (S) indicat samples that were taken in a

nwer. Stations AR-5., PR-4 and TB-5 wen sampled and analyzed in triplicate and the

average value is reported. AVS is acid-volatfle sulfur. ND - Not Determined.

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Velinsky et al.

Table 2. Concentrations of trace metals in the sediments of the vaHous study arear.

Sta. M. Cd Cr Cu Fe Bg Pb ZU

)Gngm LAkc

XL-I 1.53 106 63.8 4.07 0.29 134 348

KL-2 2.21 134 92.3 5.04 0.43 194 466

KL-3 2.19 118 100 4.73 0.39 177 450

KL-4 1.92 106 %.6 4.19 0.46 199 462

KL-5 2.01 107 76.1 4.39 0.35 144 418

Anscostia River

AR-i 1.72 103 75.6 3.91 0.34 139 355

AR-2 1.93 118 91.9 4.56 0.29 148 401

AR-3 1.% 124 102 4.82 0.37 157 406

AR-4 3.18 156 127 4.19 1.04 409 512

AR-SA 1.48 108 90.2 5.23 0.36 131 367

AR-6 0.92 90.3 63.8 4.82 0.54 83.2 279

OAR-I 1.72 11 73.4 4.01 0.30 164 420

OAR-2 1.75 116 145 4.25 1.21 195 450

OAR-3 0.90 58.0 69.9 1.54 0.72 175 215

OAR-4 1.43 109 86.9 4.08 0.30 151 382

OAR-6 0.50 74.0 94.7 3.73 1.16 111 208

123

Velinsky et al.

ShL ED. Cd Cr Cu A Hg Pb Zn

OAR-RI 0.29 31.0 19.9 1.79 0.17 40.0 90.0

SAR-2 0.79 634 328 3.63 0.18 8140 512

SAR-3 0.37 163 20.5 2.38 0.01 102 224

SAR-5 1.68 133 97.4 1.64 2.02 207 271

SAR-6 0.45 122 47.9 1.43 0.22 96.0 164

Washington Ship Channel

WSC-1 1.19 94.3 103 5.06 0.74 183 356

WSC-2 1.03 95.5 99.9 4.99 0.58 147 332

WSC-3 1.09 .90.7 92.6 5.24 0.52 126 339

WSC-5 0.45 51.1 33.4 2.92 0.23 48.3 137

WSC-6 0.79 96.8 52.6 4.76 0.25 61.9 247

OWSC-1 1.25 83.0 102 3.33 0.164 163 400

OWSC-2 3.31 105 251 3.56 0.63 425 1090

OWSC-3 0.95 63.0 112 1.51 0.20 515 406

OWSC-RI 3.05 167 348 4.11 0.97 2100 750

SWSC-2 4.07 44.0. 27.6 1.16 0.05 72.0 200

Potomac River

PR-1 0.99 96.2 59.7 4.45 0.56 128 365

PR-2 0.55 66.6 34.2 3.99 0.15 32.0 168

PR-3 0.52 63.4 35.6 3.76 0.13 33.9 171

PR-4A 0.59 69.0 37.8 4.06 0.15 39.0 189

124

Velinsky etd.

SUL M. Cd Cr Cu Fe 49 ft Zn

7"idal Basin

TB-i 1.67 97.4 120 4.89 0.45 204 385

n-1*5 ND ND ND ND ND ND ND

TB-2 0.94 91.1 55.1 4.55 0.25 84.5 255

TB-3 0.74 75.9 44.5 3.89 0.24 109 216

TB-4 0.97 %.9 66.7 5.09 0.29 104 292

TB-5A 0.83 87.0 55.3 4.67 0.27 79.3 260

TB-6 0.93 92.3 59.1 4.88 0.27 91.4 285

OTB-1-1 0.24 41.0 19.7 0.89 0.07 36.0 62.0

OTB-1-2 0.83 30.0 47.9 1.67 0.15 120 235

OTB-2 0.43 28.0 13.7 1.91 o.o6 320 112

OTB-3 0.89 167 25.9 2.50 0.09 1020 180

OTII-4 0,94 176 102 2*19 9,22 3630 527

OTB-5 0.73 149 39.4 2.32 0.13 465 197

STB-2-1 9.46 3060 1780 7.07 7.03 31300 12Q
Sn-2-2 2.81 518 ;1 0 1.89 4.96 5020 6M

-All concentrations am in Ag per gram dry-weight, ex cept for Fe which is %- Station I]Ds- starting with

the prefix (0) indicate samples that were taken directly in front of a sewer outfall, while ID's starting

with the prefix (S) indicates samples that were taken in a sewer. Stations AR-5, PR4 and TB-5

met sampled and analyzed in triplicate, these data am the average. ND - Not Determined.

125

Velinsky et al.

Table 3. Ratio of Acid Extractable to Total Sedimentary Metals from

Selected Statio&.

ShL ED. Cd Cu Fe Pb Zn

KL-1 0.94 0.35 0.21 0.80 0.69

KL-2 0.91 0.47 0.27 0.98 0.72

KL-3 0.99 0.47 0.24 0.90 0.57

KL-4 0.91 0.38 0.24 0.78 0.72

KL-5 0.79 0.55 0.21 0.79 0.52

AR-I 0.88 0.39 0.26 0.91 0.74

AR-2 0.92 0.51 0.24 0.93 0.73

AR-3 0.92 0.56 0.25 0.94 0.73

AR-4 0.74 0.13 0.27 0.85 0.67

AR-5 0.87 0.48 0.24 0.84 0.60

WSC,I 0*92 0*40 0*33 0*96 0*62

WSC-3 0.77 0.34 0.37 0.88 0.58

PR4A 0.77 0.43 0.19 0.67 0.50

TB-I 0.70 0.43 0.24 0.70 0.53

TB-3 0.72 0.23 0.25 0.59 0.60

Average 0.84 0.41 0.25 0.93 0.63

:E SD 0.08 0.11 0.04 0.11 0.08

'ILL-Kingnian Lake, AR-Anscostia River, WSC-Washington Ship =Cl'

PR-Potomac River, TB-Tidal Basin.

126

Velinsky et al.

Table 4. Metal to Iron Ratios used for the Calculation of Enrichment Factors (EFr.

Cd Cr Cu Bg Pb Zn Location

0.03 20.0 8.5 0.01 4.2 17.0 Continental Crus&

ND 18.8 9.2 ND 9.4 25.0 Soile

0.01 11.8 3.6 ND 4.4 14.1 St. Mary's County Coastal Deposie

0.01 24.0 2.1 ND 3.9 14.5 Ann Arundal County Deposite

0.09 9.4 8.1 0.06 NS NS Chesapeake Bay Sediments!

0.05 23.0 8.1 ND NS NS Core 1314s, Mouth of Potomac River

0.04 17.8 6.6 0.04 5.5 17.7 Average

0.03 6.0 3.0 2.6 5.1 :k Standard Deviation (lar)

'Values am the ratio of total metal (jig g') to total Fe (%). INVedepohl 1971; 'Martin and

Meybeck 1979; "Holz et al. 1985; *NOAA 1991; 'Goldberg et al. 1978. ND - No Data;

NS - regression between meW and iron was not significant at p <0.05, whereas other

metals were significant at p <0.01 (n = 50).

127

Velinsky et al.

Table S. Trace metal esuichment factors OEF) for the sed;-ents of the Washinston, D.C. area'.

Sta. ID. Cd Cr Cu H9 Pb zn

KL-1 9.4 1.5 2.4 1.7 6.0 4.8

XL-2 11.0 1.5 2.8 2.1 6.7 5.2

KL-3 11.6 1.4 3.2 2.1 6.8 5.3

KL-4 11.5 1.4 3.5 2.7 8.7 6.2

KL-I 11.5 1.4 2.6 2.0 6.0 5.4

Anacostia Riv

AR-I 11.0 1.5 2.9 2.2 6.5 5.1

AR-2 10.6 1.4 3.1 1.6 5.9 4.9

AR-3 10.2 1.4 3.2 1.9 5.9 4.8

AR-4 19.0 2.1 4.6 6.2 17.7 6.9

AR-SA 7.1 1.2 2.6 1.7 4.5 4.0

AR-6 4.8 1.1 2.0 2.8 3.1 3.3

Wasbiurtge Shig Channel

WSC-1 5.9 1.0 3.1 3.7 6.6 4.0

WSC-2 5.2 1.1 3.0 2.9 5.3 3.8

WSC-3 5.2 1.0 2.7 2.5 4.4 3.7

WSC-5 3-9 1.0 1.7 1.9 3.0 2-7

WSC-6 4.1 1.0 1.7 1.2 1.4 2.0

128

Sta. IID. Cd Cr CU Hg Pb Zu Velinsky et al.

-Potomac give

PR-1 5.6 1.2 2.0 3.2 5.2 4.6

PR-2 3.5 1.0 1.3 1.0 1.5 2.4

PR-3 3.5 0.9 1.4 0.9 1.6 2.6

PR-4A 3.6 1.0 1.4 0.9 1.8 2.6

Tidal jas

TB-1 8.5 1.1 3.7 2.3 7.6 4.5

TB-1.5 ND ND ND ND ND ND

TB-2 4.6 1.1 1.8 1.4 3.4 3.2

TB-3 4.8 1.1 1.7 1.6 5.1 3.1

TB4 4.8 1.1 2.0 1.4 3.7 3.2

TB-5A 4.5 1.0 1.8 1.4 3.1 3.1

TB-6 4.8 1.1 1.8 1.4 3.4 3.3

sEnrichment factor (X/Fe).a./(X/1Fe).w,.w, where X is the ft-ace, metal of interest and the

(X/Fe).w,...j values are taken from Table 4. ND - No data.

129

Velinsky et.al.

Table 6. Range of tram metal frorn various studies in the Nd-Atlantic regiort.

Cd Cr CU Hg Ph Zn Location Source

0.45-3.2 51-155 33-126 0.2-1.0 32-409 137-512 Washington, D-C- This Studf

<I - 650 60-5750 60-2930 0.1-10 130-13890 350 -6040 Baltimore Harbor Lyman et &1. (1997)

NlY 10-990 10-3000 <0.01 - 0.9 20-19000 30-1400 Schuykill River, PA. Lyman et &1. (1987)

0.2-1.3 39-62 29-43 0.07-0.3 15-73 134-270 Potomac Estuary MDE' (unpub. data)

0.09-0.60 90-237 15-30 0.1-0.2 11-23 42-86 Lower Ches. Day NOAA (199 1)

0.09-0.40 77-647 20-75 0.1-0.4 8.5-27 57-115 Middle Ches. Bay NOAA (I"l)

0 0.2S-0.96 109-280 56-79 0.2-0.5 is-so 93-380 Upper Chas. Bay NOAA (I"l)

Txmcentfations are in ItS per gram dry-weight. 'Only river or basin sediment samples are pfesented for this study. 'ND - No data. 'MDE - Maryland

Departnent of the Environment

Velinsky et al.

list of Figures:

Figure 1. General study area showing the locations of the Tidal Basin, Washington Ship Channel,

Kingman Lake and the Potomac and Anacostia rivers. Arrows located around the shoreline indicate

approximate location of outfall and sewer samples.

Figure 2. Sediment trace metal distribution: Anacostia River. Transect is from the southern portion of

Kingman Lake (KL-5) to the confluence of the Anacostia and Potomac rivers and the Washington

Ship Channel at station PR-4.

Figure 3. Distribution of selected trace metals in outfall, sewer, and basin sediments of the Tidal

Basin. Concentrations of Pb are in %.

Figure 4. Distribution of selected trace metals in outfall, sewer, and channel sediments of the

Washington Ship Channel.

Figure 5. Distribution of selected trace metals in outfall, sewer, and river sediments of the Anacostia

River. Concentrations of Pb are in %.

131

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136

DATE DUE

GAYLORDINo. 2333 PR.::!F@ U 5 A

3 6668 14106 7506