3O3-R"
CBP/TRS 87/93
February
Chesapeake Bay
Contaminated Sediments
Critical Issue Forum
Proceedings
Basinwide Toxics Reduction Strategy Reevaluation Report
Chesapeake Bay Program
t Printed on recycled paper
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Proceedings of the
Chesapeake Bay Program
Toxics Subcommittee
Sponsored
Chesapeake Bay Contaminated Sediments
Critical Issue Forum
December 10,1992
Produced under contract to the U.S. Environmental Protection Agency
Contract No. 68-WO-0043
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
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PROCEEDINGS OF THE CHESAPEAKE BAY PROGRAM
TOXICS SUBCOMMITTEE SPONSORED
CHESAPEAKE BAY CONTAMINATED SEDIMENTS CRITICAL ISSUE FORUM
U.S. EPA Chesapeake Bay Program Office
Chesapeake Bay Information and Conference Center
December ,10,1992 3
1. CRITICAL ISSUE FORUM OBJECTIVES/PROCESS
Dave Velinsky convened the forum and described the forum objectives and process. A written
summary of the forum proceedings, discussions and findings will be prepared by the Chesapeake Bay
Program Office and the forum co-chairs and distributed for review by the forum speakers. The forum
findings will be presented to the Toxics Subcommittee in January.
As an integral part of the ongoing revaluation, the Chesapeake Bay Contaminated Sediment
Critical Issue Forum was structured to seek a technical consensus on the following series of questions:
o From the critical review of available data, have we defined/can we define the relative magnitude
(concentration) and extent (geographical distribution) of contaminated sediments within
Chesapeake Bay?
o
o
Does this definition of the magnitude and extent of contaminated sediments within the Bay give
us reason to,belieye this identified (potential) toxics issue is causing or can cause an impact (e.g.
bioaccumulation, toxicity) on Chesapeake Bay system, on either aBaywicle, regional1 dr local
""'' ' :''' " " '"'"'''''"'••'"••••••-••-^
How does'the magnitude and extent of contaminated sediments wittihiChesapeakefBay compare
with other coastal systems (e.g. Puget Sound) or large water bodies (e.g. Great Lakes)?!
•»••-•:•' :,:,> •'•:-..•• ..-••" :-•• - ;. .-"' •,.••.'>--,••.'••"••<- . . rt-f
What direction should the Toxics Subcommittee recommend the Chesapeake Bay Program
agencies take with regards to addressing contaminated sediments?^
.... Jj . • .-., . :••', • ;•.,-,.,•.
Denoting Regions of Concern (with contaminated sediments as one of the parameters for
delineation)
Recommending to the jurisdictions general/specific source reduction/remediation actions
Undertaking a structured set of applied anil basic studies in specific Regions of Concern
.to determine the source, fate and effects of sedimentary metals and organics
Other directions... '
/' , • • - • ' •:'.)"-•
If there is insufficient data or information to answer the above questions, identify the additional
data/research required to answer the questions.
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2. EPA CONTAMINATED SEDIMENTS MANAGEMENT STRATEGY
Tom Armitage described the events leading up to development of EPA's Contaminated Sediment
Management Strategy. He explained that national EPA surveys in 1985 and 1987, concerned mostly with
bioaccumulative toxic compounds such as PCBs, pesticides, PAHs, and metals, showed that the extent
of sediment contamination might be national in scope. A 1989 National Academy of Sciences report,
"Contaminated Marine Sediments - Assessment and Remediation", recommended the EPA take specific
actions to address sediment contamination issues.
A map from the "Overview of Sediment Contamination in the U.S." report showed sites across
the country where available data show levels of sediment contamination which may be harmful to benthic
and other aquatic communities. The sites displayed were associated with drinking water restrictions, fish
kills, fish advisories and recreation use restrictions. The Great Lakes region shows a proliferation of
these sites, which may be indicative of sediment contamination problems in that region but is probably
due to a greater amount of sediment contaminant data.
Based on present data, sources of contaminants in sediments have been identified as: industrial
discharges, municipal waste water treatment plants, combined sewage overflows, stormwater runoff,
hazardous waste disposal sites, and atmospheric deposition.
Tom Armitage pointed out that efforts to develop a national "Contaminated Sediments
Management Strategy" were initiated in 1989 by then EPA administrator Lee Thomas. Testimony on the
scope of contaminated sediment problems was presented at a number of Congressional hearings
throughout 1989-1991 as a result of increased legislative interest in the issue. EPA's proposed sediment
management approach was presented at national conferences in 1991 and a draft strategy outline was
released for public review in March 1992. Three national forums on the proposed strategy were also held
in April-June, 1992. The forums proceedings were published in September 1992. A revised strategy will
be distributed for comment in March 1993 with a final strategy to be available in late summer or early
fall 1993.
The goals of the draft "Contaminated Sediment Management Strategy" are to:
• prevent future contamination of sediments;
• manage existing sediment contamination using:
pollution prevention
source controls
natural recovery where appropriate (Natural recovery refers to limiting
bioavailability of contaminants through processes such as natural sedimentation.
Active remediation may be preferable to natural recovery when toxics are moving
off site. Criteria are being established for determination of when to use active
remediation.);
• remediate high-risk sites where natural recovery is not acceptable; and
• ensure environmentally sound management of sediment dredging and the disposal of
dredged materials.
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Specific elements of the strategy include:
• Assessment: a national inventory to identify and rank geographical areas for targeted
pollution prevention, source controls and remediation, coupled with consistent tiered
testing methodologies employed as part of expanded sediment monitoring programs.
• Research: the EPA Office of Research and Development has a
contaminated sediment research plan which encompasses development of sediment
assessment methods, sediment quality criteria, and new remediation technologies.
• Prevention: applications of existing authorities to prevent point and nonpoint sources of
sediment contamination and prevent introduction of new compounds which may
contaminate sediments.
• Remediation: use existing authority and statutory provisions under CWA, CERCLA
(superfund), RCRA, and TSCA, which can be focused on sediment quality.
• Dredged material: A new testing manual for dredged material is being developed which
will reduce the list of test species to include only the most sensitive ones, and will
provide mixing zone models for use in shallow water. The applicability of RCRA to
dredged material and the appropriate use of sediment quality criteria in dredged material
assessment and management is also being addressed.
Outreach activities concerning contaminated sediments include a quarterly newsletter,
"Contaminated Sediment News", and publication of the national Sediment Strategy Forums proceedings.
Tom Armitage distributed a handout from the EPA Office of Water's Office of Science and Technology
which outlined the responsibilities of various EPA program offices for sediment toxicity testing.
Tom Armitage described the results of the most recent EPA Science Advisory Board review of
the proposed sediment quality criteria for 3 PAHs and 2 pesticides. The Science Advisory Board
recommended EPA provide guidance on how each program office will apply the sediment quality criteria
in their regulatory processes. EPA is performing an economic impact analysis for the application of the
criteria. Sediment quality criteria for 4 metals - nickel, lead, zinc, and cadmium - are also being
developed and the metals criteria development methodology will undergo a Science Advisory Board
review this summer.
Results of EPA Sponsored Workshop on Tiered Sediment Toxicity Testing Protocols
Beverly Baker summarized the results from the September 16-18 workshop on Tiered Sediment
Toxicity Testing Protocol held in Washington D.C. The workshop, co-sponsored by the Office of Water
and the Office of Research and Development, was held to provide an opportunity for experts in sediment
toxicology and staff from EPA's Regional and Headquarters program office to discuss and prioritize the
development of standardized freshwater and marine sediment bioassay procedures. As part of EPA's
Contaminated Sediment Strategy, EPA's program offices have agreed to use consistent tests for the
assessment of sediment quality. As a result of the workshop, the following test organisms have been
selected for development of standardized sediment toxicity test methods in FY93:
• Freshwater acute toxicity tests - Hyalella azteca, and Chironomus tenfans.
• Freshwater bioaccumulation test - Lwnbriculusvariagatus.
• Marine/estuarine acute toxicity tests - Rhepoxynius abronius, Ampelisca abdita, Echaustorius
estuarius, and Leptocheirus plwnuloms.
• Marine bioaccumulation tests - Neries sp. and Macoma nasuta.
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By the end of FY93, EPA approved protocols on sediment collection and handling and sediment
spiking will be published and sediment toxicity test protocols will be available for the above mentioned
species. As additional funds become available, work will be conducted on chronic toxicity test methods
development and sediment toxicity identification evaluations. Copies of the workshop proceedings are
available through the EPA Office of Science and Technology Resource Center.
Rich Batiuk mentioned that there is a need for chronic as well as acute toxicity tests covering the
full range of Bay salinity. Beth McGee mentioned that chronic toxicity tests had been conducted by the
state of Maryland on Leptocheirus plumulosus and have been recommended for standardization through
the ASTM process.
National Sediment Contamination Data Inventory
Catherine Fox distributed outlines of the "Framework for the Design of the National Inventory
of Contaminated Sediment Sites". A draft of the inventory framework will be available by the end of
December with the final framework available in February 1993. The purpose of the national inventory
is to obtain the best possible near-term assessment of the national extent and severity of sediment
contamination. The inventory will be used to determine whether contaminated sediments are a pervasive
national-scale problem or more of a localized "hot spots" issue. The inventory will also be used by EPA
Program Offices in targeting assessment, pollution prevention, source control, remediation, and dredged
material management activities.
Based on a review of regional sediment contaminant data inventories, EPA decided to include data
from individual samples (as opposed to data averages or summaries) in the national inventory. Individual
data, to be stored on an EPA mainframe computer, will be grouped and rated for quality: high (good
QA/QC), moderate, or no information.
3. NOAA NST/EPA EMAP SEDIMENT CONTAMINANT FINDINGS
Tom O'Connor described findings from the analysis of the combined sediment contamination data
from the NOAA National Status and Trends Program (NS&T) through 1989 and from the 1990 EPA
Environmental Monitoring and Assessment Program (EMAP) for Chesapeake Bay. The NS&T Program
has chemical data from 274 sites distributed throughout the coastal United States. The EMAP Program,
for 1990, has data for 152 sites hi the Virginian Province. There are 17 NS&T sites and 62 EMAP sites
in Chesapeake Bay.
Tom presented the data in several ways, all of which pointed towards three more contaminated
areas in the Chesapeake Bay: Baltimore Harbor, Anacostia River, and Elizabeth River. When combined
data were adjusted for grain-size and compared with "high" concentrations as derived from the national
NS&T data set, those three areas were the only areas in Chesapeake Bay where 3 or more chemicals were
at "high" sediment concentrations.
Concentrations of sediment contaminants above which there is the potential for biological impacts
have been published by Long and Morgan (1990). Effects range-median (ER-M) and effects range-low
(ER-L) values are based on an analysis of data sets containing coincident measures of chemical
concentrations and some biological effect. The ER-M is the median of concentrations for which there
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was a biological effect. The ER-L is the 10th percentile of those values. It should be recognized that
these values are only guidelines because (1) they are based on data from field-collected sediments with
no assurance that a biological effect is caused by any particular chemical, and (2) there are many
instances listed by Long and Morgan where sediments with concentrations in excess of ER-L's had no
corresponding biological effect (this was less so with the ER-M values).
In Chesapeake Bay, there were a number of NS&T/EMAP sites where sediment concentrations
of at least one chemical were hi excess of an ER-L value. However, with one exception, all the sites
with >80% sandy sediments and 21 of the 57 sites with fine-grained sediment had no concentration
exceeding an ER-L value. These sites were almost all in the southern portion of the mainstem Bay.
Exceedances of ER-M values were found only at sites within Baltimore Harbor, the Anacostia River and
the Elizabeth River, and at sites in the northern mainstem Bay.
At the EMAP sites, sediment toxicity was tested using 10-day survival of amphipods. Sediment
at a particular site were considered in the "toxic" category if survival on test sediments was less then 80%
and statistically less (0.05 level) than control survival. Sediments were found to be toxic at 17 of the 142
EMAP sites in the Virginia Province. Four EMAP sites in Chesapeake Bay were characterized as "toxic"
- three hi Baltimore Harbor and one in the Elizabeth River.
A final comparison was made between the NS&T/EMAP sediment contaminant data and the EPA
proposed sediment quality criteria for trace metals and selected neutral organic compounds. The metal
sediment quality criterion assumes toxic conditions if total concentrations of sulfide-insoluble metals
(except iron and manganese) exceed the concentration of acid-volatile sulfide (AVS). If it is assumed that
all sediments have at least 10 fiMfg of AVS, there are only seven Chesapeake Bay sediment samples that
might be toxic due to metals contamination. Even in those samples, all from Baltimore Harbor,
Anacostia River, and the Elizabeth River, the metals criterion may not be exceeded because AVS could
well exceed 10 /*M/g. No Chesapeake Bay sediment samples exceeded proposed criteria for four neutral
organics - dieldrin, phenanthrene, fluoranthene, and acenaphthalene (where the sediment quality criteria
are based on assumed equilibria with pore water and application of water quality criteria to pore water).
In summary, sites in Baltimore Harbor, the Elizabeth River, and the Anacostia River are
distinguished from other sites in Chesapeake Bay in terms of:
• Numbers of chemicals with "high" sediment contaminant concentrations;
• Magnitude of the sediment contaminant concentrations;
• Sediment contaminant concentrations in excess of ER-M values thought to be associated
with sediment toxicity; and
• Measured sediment toxicity (at sites in Baltimore Harbor and Elizabeth River).
Tom stated that there is a connection between toxicity and contaminated sediment in the Elizabeth River
and Baltimore Harbor.
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Sediment Core Analyses
Nathalie Valette-Silver presented a summary of findings from previous contaminant analyses of
Chesapeake Bay sediment cores. She explained that determining temporal trends through sediment core
analyses is useful hi evaluating changes hi contamination due to anthropogenic activities. Trends in
sediment contamination can also be examined through analysis of surface sediments or shellfish tissue data
records.
Sediment cores are used in the determination of long term trends by finding background, or
baseline, concentrations and constructing a chronology of sediment contamination levels over time. The
reconstruction of historical sediment contamination trends requires collection of samples in areas where
sediments have been undisturbed during and after their deposition (i.e. limited or no physical or biological
mixing).
Dating of sediment layers is crucial to insure a reliable chronology of a core. The integrity of
the core must be checked by using x-ray radiography. Slices of the core are then dated using pollen or
radioactive isotopes such as Pb210 and Cs137.
Results from previous sediment core work in the Chesapeake Bay show that there is a peak in
the 1970s hi the concentrations of Cu and Pb hi the southern mainstem Bay, followed by a decrease in
the early 1980s. In the northern mainstem Bay, concentrations of Pb and Zn were still increasing in the
1980s. For the organic compounds, increases were observed through 1982. The sediment core
contaminant data from the early 1980s is the most recent.
The NOAA National Status and Trends Program has been supporting sediment core analysis
studies for the last few years. A sediment core study was initiated in Chesapeake Bay hi 1992 (first year
only). Five of the six study sites are located hi the mainstem of the Bay, and one is located at the mouth
of the York River. When completed, the study will yield information on six sediment core contaminant
chronologies for trace metals and nutrients and three sediment core contaminant chronologiies for organic
compounds.
Nathalie Valette-Silver concluded that some problems exist with sediment core samples. In
particular, chronology of the sediment must be good and several dating tools must be used at the same
tune to achieve this objective. Remobilization of some of the contaminants can occur after deposition
of the sediments due to diagenetic processes. With these problems accounted for, sediment cores can
keep a reliable record of contamination changes over time. This type of study can then be a very useful
tool for managers hi reconstructing the historical contamination in Chesapeake Bay.
Nathalie Valette-Silver went on to describe results from short term trends analyses of surface
sediment contaminant data collected through the NOAA National Status and Trends Program Benthic
Surveillance Project hi Chesapeake Bay for the period of 1984-1986. These results show almost no
trends except for Zn, which did increase hi the northern mainstem Bay.
She explained that there are some problems associated with the use of surface sediments for
establishing short term trends. In particular, it is difficult to determine the exact age of the surface
sediment collected at a site. Sedimentation rates can vary due to changes in erosional and depositional
processes both temporally and from site to site. The only way to check this is by using a radionuclide
with a short half life, such as Be7 with a half life of 54 days, to determine if the sediment has been
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deposited within the last year.
Another method for evaluating short term temporal trends is to look at trends in bivalve tissue
chemistry. Oysters and mussels are good indicator organisms for detection of short term contamination
trends because their chemical body burden responds rapidly to chemical changes in their environment.
4. BAYWIDE SEDIMENT CONTAMINANT MONITORING PROGRAM FINDINGS
Rich Eskin presented findings from an ongoing effort to synthesize, analyze and interpret
sediment contaminant data from the Maryland and Virginia components of the Chesapeake Bay Sediment
Contaminant Monitoring Program. This baywide monitoring program was established to characterize
sediment contamination hi Chesapeake Bay and its tidal tributaries. A draft report presenting more
detailed descriptions of the findings below will be distributed for review hi late March.
For summary purposes, the station specific sediment contaminant data have been aggregated by
Chesapeake Bay segment. Rich Eskin emphasized that this summary format gives a very broad overview
and that the data need to be reviev/ed hi greater detail before any decisions can be based on it.
Aggregates of the available data, however, are useful hi highlighting geographic areas, focusing on
potential sources, and making comparisons between areas or stations.
General Patterns of Distribution
Rich Eskin presented several graphs with ERM values as reference lines, when relevant, to
indicate areas that need closer examination. ERLs were not used because it was felt they are more
arbitrary and because the report is not attempting to make a strong statement about the relationship of the
ERL and ERM to actual toxicity in the field.
Mainstem
In the Bay Mainstem, metal concentrations are distributed in a pattern similar to that of silt/clay
content. The highest metals concentrations were found, along with the highest silt/clay content, hi
segment CBS. Mainstem patterns of specific metals and organic contaminants were summarized as
follows:
• Organic carbon and organic contaminant concentrations were highest hi segment CB2.
• Lead: Follows the general pattern of silt/clay content with the highest concentrations and
ranges in segment CBS. All values were below the ERM value of 110 ppm. There is
a decrease hi concentrations from west to east with similar median values at river
mouths.
• Nickel: Highest concentrations in segments CB2 and CBS with a wider concentration
range in segment CBS than in segment CB2 (note there are different numbers of
observations in the two segments). Some values exceed the ERM value of 50 ppm.
Concentration ranges were similar across all the river mouths.
• Zinc: Follows the general pattern described for silt and clay with the highest
concentrations found in segment CBS. Some values exceeded the ERM value, indicating
that a closer look would be worthwhile. Concentrations decreased from west to east.
According to published information, zinc levels are naturally high hi the Bay.
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• Chrysene: Follows the pattern of organic carbon with the highest concentrations in
segment CB2. This suggests diffuse sources, and that concentrations occur where natural
physical/chemical conditions are most relevant. All values were well below the ERM
value of 2800 ppm.
• Total PCBs: Not analyzed for in earlier mainstem samples, but may be representative
of chlorinated compounds, which seem to distribute more like metals than PAHs. PCS
concentrations at all locations were well below the ERM value of 400 ppb.
• Arsenic: The only substance with a clear pattern of temporal changes in the mainstem.
The Baywide median for arsenic was 8.5 pp^m. The highest segment median was 13 ppm
hi the aggregated Western mainstem segment, well below the ERM value of 85 ppm.
An apparent increase of arsenic was documented, but it is likely a function of analytical
method differences.
Tributaries
Rich Eskin showed a map of Chesapeake Bay tributary segments, explaining that only the
Maryland tributaries had metals data. Tributary trends of specific metals and other toxic substances were
summarized as follows.
• Chromium: Concentrations were generally below the ERM value. The Sassafras River
and some of the Western Shore tributaries (Back River) have elevated concentrations
relative to other tributaries, but values are still below the ERM. Low levels were
reported in the southern Eastern Shore tributaries.
• Lead: Similar pattern to chromium; elevated concentrations in Back River.
• Zinc: The ERM was exceeded in several locations - Back River, Magothy, Severn and
South rivers. Recent estimates of urban runoff reported relatively large zinc loadings,
but an anthropogenic enrichment factor has not yet been calculated for this data.
• Nickel: Elevated levels were reported for the Back, Elk, and Northeast rivers.
• Benzo(a)anthracene: Concentrations were generally well below the ERM value. Levels
were low in Back River but slightly elevated in the Western Shore tributaries. Low
concentrations were reported in the southern Eastern Shore tributaries.
Pesticides were sampled for at 38 stations hi Maryland. Carbofuran was found in only one
location. Hexachlorobenzene was only found at 6 of the 9 stations in Baltimore Harbor. Curtis Bay and
Back Creek were shown to have high concentrations of pesticides in sediments.
In the Baltimore Harbor, the central channel stations generally show the lowest concentrations.
Rich Eskin suggested that further investigation of sediment contamination from lead, chromium, nickel,
and zinc was warranted by the existing data. Pesticides reported in the Baltimore Harbor sediments were
mostly chlorinated compounds.
Sediment data for the Elizabeth River comes from many different programs with different stations
often monitoring for different purposes. Though the data has been aggregated into five general
geographic regions, final results await further discussions with Virginia. Rich Eskin noted that although
concentration ranges spanning almost 6 orders of magnitude were observed, the median concentrations
are much less variable. Even hi the Southern Branch of the Elizabeth River, which has the highest
concentrations, the median concentrations were often right around the ERM value. These findings have
significant implications for identification of Chesapeake Bay Regions of Concern, suggesting very high
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levels of resolution may be necessary to clearly define "hot spots"
5. UPPER TIDAL POTOMAC RIVER SEDIMENT CONTAMINANT FINDINGS
Dave Velinsky summarized findings from a sediment study of the sections of the Potomac and
Anacostia Rivers within Washington B.C. The objectives of this study were 1) to define the extent of
chemical contamination in the sediments around selected areas of the District of Columbia; 2) to
determine the extent and possible controlling factors of sediment toxicity to the amphipod Hyalellaazteca;
and 3) to elucidate possible source area(s) of organic and inorganic contaminants to sediments in this area.
A total of 54 samples were collected from Potomac River, Anacostia River, Tidal Basin,
Washington Ship Channel and Kingman Lake. Direct sampling of 14 major storm and combined sewer
outfalls in the Tidal Basin, Washington Ship Channel, and the Anacostia River was carried out as well.
In addition, bottom sediment material was collected from inside selected storm and combined sewers mat
directly discharge into these areas. The outfall and sewer sediment samples were used to indicate source
areas for anthropogenic chemicals to river sediments around the District of Columbia. Sediment
chemistry data was combined with benthic macro-invertebrate abundance, diversity, and toxicity data to
identify areas of biological and chemical impacts.
Geographical and spatial trends for trace metals and organics in sediments reveal several specific
areas of concern. High concentrations of lead, cadmium, and zinc, as well as PAHs, PCBs, chlordanes,
and DDT (sum of DDT+DDE+DDD) were observed in many areas. Since DDT was banned 20 years
ago, its presence in the storm and combined sewer samples is of concern. The highest concentrations
were found at sites located close to the Washington Navy Yard in the Anacostia River. The lowest
concentrations (dependent on the constituent) were found either hi the Washington Ship Channel, near
Green Leaf Point, or in one of two Potomac River sites near Hains Point. Trace metals and other
organics often exhibited the same geographical trend:
Analysis of the sediment data suggests that numerous storm and combined sewers are a major
source of sediment contamination to the Anacostia River. This is especially noted at the station near the
Washington Navy Yard. The extreme concentration gradient between the sewer, outfall, and river
sediments at this location (and others) indicates urban runoff as a source. Past and present activities at
the Washington Navy Yard and possibly the U.S. Botanical Gardens could also contribute to the
contamination of the area.
Sediment toxicity testing and macro-invertebrate community analysis results matched with
chemical results in the lower Anacostia River stations (i.e., from the Pennsylvania Arc Bridge to the
South Capital Street Bridge) which exhibited the most severe degree of biological impairment. Two
Kingman Lake stations also exhibited toxicity. Both the Washington Ship Channel and Tidal Basin
stations showed no sediment toxicity, moderate benthic community parameters, and levels of sediment
contamination below levels present hi the Anacostia River. The Potomac River site presented a
perplexing situation in that H. azteca survival was lowest of any site, while benthic community results
were equivocal. Sediment contaminant levels were some of the lowest of any station, however. Sediment
toxicity results may be the result of high concentrations of porewater ammonia.
Sediment concentrations of trace metals and specific organics from the 15 biological stations were
compared to the proposed EPA sediment quality criteria for metals and selected organics. SEM/AVS
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molar ratios at all sites were less than one, indicating that trace metals were not bio-available in the
porewaters of the sediments. Measured sediment concentrations did not exceed the proposed sediment
quality criteria for dieldrin, endrin, acenapthene, flouranthene, and phenanthrene. Sediment
concentrations of total chlordane, normalized to the organic carbon content, exceeded the calculated
sediment quality criterion. These preliminary results suggest that chlordane may be contributing to the
impairment of the benthic community. However, comparisons of the sediment quality criteria of
individual chemicals does not take into account the possible synergistic effects of all organic and inorganic
compounds present.
Sediments of the Anacostia River were substantially enriched for lead, cadmium, and zinc,
compared to the other trace metals - copper, chromium, and mercury. Concentrations of lead, cadmium,
zinc and other trace metals were higher than those found in the mainstem Chesapeake Bay by a factor
of 2-4, depending on the metal. Concentrations of all metals were below concentrations found in
Baltimore Harbor and the Schuylkill River (Philadelphia, PA). Metals concentrations were higher hi the
Washington D.C. area than in the Maryland portion of the tidal Potomac River.
All groups of organics had higher concentrations than those reported in the mainstem Bay, but
were lower than those found in Baltimore Harbor. On a chemical basis alone, it appears that specific
reaches of the Potomac and Anacostia rivers and other tidal systems within the Washington, D.C. area
are contaminated with trace metals and organics (PCBs, DDT, PAH, and chlordane). The most severely
impacted area is the reach of the Anacostia River just downstream of the Washington Navy Yard. Outfall
sediment distribution indicates a diffuse input for total hydrocarbons and PAHs, 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 a point source input to the area sediments through specific
outfalls.
6. CHESAPEAKE BAY SEDIMENT TOXICITY FINDINGS
Ray Alden reviewed previous work on contaminated sediments in the Elizabeth River, presented
the Sediment Quality Triad, gave an overview of the sediment portion of the Chesapeake Bay Ambient
Toxicity Program and presented sediment toxicity issues relevant to future studies. .
The Elizabeth River study evaluated responses of amphipods, urchins, and microtox to sediment
contamination. Transects were evaluated and inferential relationships were made hi the late 1970s and
early 1980s. Two groups were studied; one control group and one group which was close to a lethal
effects area (i.e. an area known to be > 50% lethal). The results for this group were close to those
expected. However, sublethal and chronic effects found further to the south were unexpected. High
levels of phenanthrene, anthracene, and napthalene were found in this area. Chrysene and other 5 ring
compounds related to the break down of creosote from oil spills and power plant activities were also
found. Characteristics of benthic community, i.e. biomass, depth distribution of biomass, species
diversity, etc, with relation to salinity were presented in a series of graphs. Ray Alden stated that the
Elizabeth river species diversity levels were below what was expected, and concluded that the area is
highly impacted.
Ray Alden briefly discussed the Sediment Quality Triad, which is a graphical representation of
the comparison of 3 variables - toxicity, chemistry, and in situ effects - to a reference site. The triad is
useful hi that it displays the interrelation of these variables. However, it does not show cause and effect
relationships and has some statistical problems associated with it.
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Ray Alden gave an overview of the Chesapeake Bay Ambient Toxicity Program, now in its third
year. The objectives of the program are to:
• Develop a survey program to assess ambient toxicity in living resource habitats and other
areas of concern; .
• Assess the feasibility of ambient toxicity surveys
- field test water column toxicity tests, sediment toxicity tests and suborganismal response
measures
- determine the relative sensitivity of these tests to ambient contaminant concentrations;
and
• Develop quantitative toxicity indices based upon multiple endpoints.
The water column testing was carried out by Lenwood Hall and the suborganismal tests conducted by Jay
Gooch.
The sampling sites, which varied over the three years of the study, were selected to provide a
range of sites, including sites with known contamination as well as sites expected to be unimpacted.
Additional tidal freshwater sites were included in year 2 and Hyalella azteca was added. Ray Alden
presented a list of all the organisms used for testing in the three years of the study. For the year three
study, summary indices are being developed to allow more direct comparison of the battery of test results
among sampled systems.
Specific results from all three years of the studies were not presented, however, some general
conclusions were made. Ray Alden suggested that some of the results may be biased because some of
the areas studied were those of concern, i.e. known problem areas. Different tests were performed at
different sites, as well, and the sensitivities of the tests were not always the same. Ray Alden suggested
that a battery of tests is needed to determine actual levels of sediment contamination.
In reference to the Sediment Quality Triad, Ray Alden stated that he had developed a technique
to put confidence limits on the sediment triad plot, noting that problems can occur because there is often
only one sample per site, so confidence of replicated data is needed.
In a brief summary of results of the Ambient Toxicity Testing program, Ray Alden noted that
results for the Wye River station were surprising. This was to be a reference site, but sediment effects
were observed. The Wye River results showed less toxicity hi Year 2 of the study.
Ray Alden stated that sediment toxicity testing is an embryonic field with a great deal of
uncertainty hi quantification, and that several issues should be determined for future studies hi this area.
It is important to determine a "clean." standard for reference sediment criteria, i.e. how uncontaminated
it should be, as well as a standard for contaminated sites, i.e. "how dirty is dirty?". In future studies,
species selection should take into account phylogenic diversity, life-style considerations, and species
availability, as well as possible risks involved in transporting species, and the potential for overharvest
of resident species. Consideration should also be given to factors that might cause confounding effects,
such as particle size, temperature, salinity and the presence of NH4 and sulfides. Factors affecting
bioavailability - total organic carbon, acid volatile sulfates, light, etc. - must be fully factored into any
resultant data analysis.
Other quantification factors to consider for future sediment toxicity testing are: experimental
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design, uncertainty and confidence, and the need for comparability studies. It is also important to
determine how the results of studies are used. Ray Alden suggested results should be viewed in the
context of a broader picture, using EMAP and other available data. Ecological risk assessment factors
are also important. Determination of goals (what to protect), techniques, and weighting factors (how do
you weight toxicity, mortality,) are all important aspects in how the data generated through sediment
toxicity tests will be used hi contaminated sediment management.
Ray Alden presented a risk assessment process which involves four steps of identification through
risk characterization, which then lead to management actions, or intensified directed research. Directed
surveys for damage assessment were also discussed. These should include random stratified surveying
of representative areas, surveys of suspected areas, critical habitat areas, and areas of specialized
management.
Sediment Toxicity in the Maryland Portion of the Bay
Beth McGee presented sediment toxicity data for the Maryland portion of the Bay. She first
emphasized that historical data has helped to characterize sediment contamination, showing that the
highest levels of contaminants are found in sediments from urban industrial areas - Baltimore Harbor area
including the Inner Harbor, Curtis Creek, Bear Creek, etc. - as well as some areas surrounding
Washington D.C. Beth McGee also mentioned that benthic community data collected as part of the long
term monitoring of Chesapeake Bay yields some estimate of potential biological effects of sediment
contamination. However, because other factors influence the condition of benthic communities, and
because of the inherent variability of the estuarine system, it is often difficult to interpret benthic data.
The recent use of sediment toxicity tests to quantify biological effects of sediment contamination in the
Bay region was used to evaluate the question, "Are contaminated sediments causing a biological impact
on a Baywide, regional or local scale?".
The following laboratories were acknowledged for their contribution to this presentation: EPA-
ERL Narragansett and Newport, EPA EMAP-Near Coastal (Naragansett), Maryland Department of the
Environment, and VERSAR. Most of the data were 10 day amphipod sediment toxicity tests with
mortality as the endpoint.
This presentation focused on two different spatial scales: 1) the distribution of sediment toxicity
on a broad geographical scale, using EMAP data, and 2) local impacts using other data sets from the
Patapsco River and Baltimore Harbor. On a broad scale, the goal is to determine how widespread
toxicity is hi the Chesapeake Bay, and where, if any, are the toxic "hot spots". On die local scale, the
goal is to determine the within-system distribution of toxicity.
In evaluating sediment toxicity data, several questions arise:
how do toxic sites compare?
can sediment toxicity tests be used to discriminate among sites?
do we need sediment toxicity tests, i.e., are they providing additional information?
Beth McGee displayed a map depicting the broad distribution of EMAP stations hi the Maryland
portion of Chesapeake Bay. The acceptable data (as indicated by mean control survival of >90%)
summarized for these sites shows significant toxicity (a significant difference from control and >20%
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mortality) for 3 stations in the Patapsco River/Baltimore Harbor sites #81, #82, and #134. Several other
stations exhibited between 15 and 20% mortality, but did not fall within the EMAP designation for
exhibiting acute toxicity. Beth McGee suggested that because EMAP's tests are conservative, these
stations - #130 in the Pocomoke River, #88 in the Anacostia, and #63 hi the Chesapeake - may also be
of concern. As a case in point, she noted the data presented on the Anacostia River (by D. Velinsky)
indicated there is a sediment contamination problem in portions of that river. In addition, EMAP toxicity
tests measure only acute lethality as an endpoint, very little is known about the potential sublethal effects
of sediment contamination in Chesapeake Bay.
Beth McGee next focused on presenting data for the Patapsco River/Baltimore Harbor system.
Bear Creek Study
Historic data in Bear Creek and surrounding Bethlehem Steel indicate sediments hi this area are
enriched with metals. Hence, this area was chosen by the EPA Environmental Research Laboratoryr
Narrangansett as area in which to attempt field validation of the AVS/SEM theory for bioavailability of
cationic metal. The EPA lab conducted sediment toxicity tests with the amphipod Amphettsca abdita and
the clam Mullnia lateralis.
The Maryland Department of the Environment conducted tests with the estuarine amphipod
Leptocheirus plumidosus on samples from a subset of the total stations sampled by EPA. Benthic
community structure was also evaluated at select sites. Chemical analyses included measurement of trace
metal concentrations in sediments and porewater, as well as acid volatile sulfide determination. Data for
Leptocheirus plumulosus obtained from a VERSAR study conducted hi Bear Creek were also presented.
Though the sample locations differed slightly from those of the EPA study, these data were included as
an illustration of the relative comparability of the test results.
Results and conclusions for the Bear Creek Study:
• At most sites, results of the sediment toxicity tests were comparable (split samples between MDE,
EPA as well as VERSAR data). Mulinia lateralis was observed to be generally less sensitive than
the two amphipod species.
• On a fine scale, sediment toxicity has a patchy, heterogenous distribution. This.observation may
be important hi the interpretation of the problem. In addition, distribution patterns may give
clues as to what the sources of toxicity may also be. It is important to note that vertical
distribution of toxicity may be important. Whether underlying sediments are "cleaner" or
"dirtier" is important if the purpose of the assessment is for dredging, determining remediation
options, etc.
• Predictions of bioavailability have not worked well, i.e., SEM/AVS ratios are > 1 at some sites
with no significant mortality observed. Whereas at other sites, ratios are < 1 and significant
mortality is observed, indicating that unmeasured organic chemicals may play a role in toxicity.
Porewater concentrations of metals were also less than predicted, suggesting that other sediment
components, hi addition to AVS, are binding metals.
• Inconsistencies exist between sediment toxicity results and benthic community analysis. This
suggests that chemical and benthic community data are not supplying all the information needed
to -accurately assess the biological impact of sediment contamination.
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Curtis Creek
The Maryland Department of the Environment has observed consistent, reproducible, acute
toxicity in sediments from a site in Curtis Creek. In fact, dilutions of Curtis Creek sediment, created by
mixing Curtis Creek sediment with "clean" sediment, have also elicited toxic effects. Other researchers
have indicated the utility of using sediment dilutions to evaluate relative toxicity of contaminated
sediments. Data from sediment toxicity test on Curtis Creek dilutions conducted by several laboratories
(MDE, EPA-Newport, ODU, and VERSAR) were presented to illustrate the extreme toxicity of these
sediments.
Chemical concentrations in sediment from the Curtis Creek site were compared to chemical data
from Commencement Bay and Elliot Bay hi Puget Sound to evaluate relative levels of contamination.
Curtis Creek sediments contained concentrations of metals and PAHs comparable to sediments from Puget
Sound, an area well known for contaminated sediment problems.
In summary:
• EMAP sediment toxicity data identified some definitive areas of concern hi Baltimore Harbor and
the Patapsco River, and some "potential" areas of concern - Pocomoke River (possible pesticide
problems), Anacostia River, and the mouth of the Patuxent River.
• Sediments from Baltimore Harbor and the Patapsco River exhibited persistent high toxicity, which
had a patchy distribution on a small scale.
• Results of the Bear Creek study to field validate SEM/AVS theory of metals bioavailability
suggested deviations from the theory's predictions.
• Sediment toxicity tests may be useful hi identifying sources and assessing vertical distribution of
sediment contamination. Testing sediment solutions may be used to identify and prioritize sites.
For these reasons, and because toxicity tests yield information not attainable through sediment
chemistry or benthic community analyses, it is recommended that sediment toxicity tests be
incorporated into future monitoring efforts.
• More research involving sublethal effects of sediment contamination hi Chesapeake Bay is
needed. Existing methods for partial life cycle tests with the amphipods Ampelisca dbdita and
Leptocheirus plumidosus are currently being refined and standardized by EPA and could be used
to estimate chronic toxicity.
Note on EMAP and Bear Creek data: "Although the data described in this article has been funded
wholly or hi part by the U.S. Environmental Protection Agency it has not been subjected to Agency
review, and therefore does not necessarily reflect the views of the Agency and no official endorsement
should be inferred."
Aquatic Sediment Quality Guidelines
Harriette Phelps presented a summary of the report entitled "Guidelines for the Protection and
Management of Aquatic Sediment Quality hi Ontario." The report seeks to provide the basis for
determining when sediments are clean, what levels of contaminants are acceptable in the short-term and
when contamination is severe enough to warrant significant remedial action. It suggests acute sediment
bioassays where sediment concentrations exceed Significant Effect Level (SEL) guidelines. SEL is the
sediment concentration of a compound that would be detrimental to the majority of benthic species.
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Harriette Phelps compared the advantages and shortcomings of current measures of sediment
toxicity (sediment background approach, equilibrium partitioning, apparent effects threshold and sediment
quality triad) to the two-step screening level concentration approach used by the Ontario Ministry of the
Environment. This method is based on co-occurrence in sediments of species and contaminants and does
not require a reference site, bioassays, accounting or other environmental factors and it includes the
synergistic effects of multiple contaminants. She also presented a case-study and critique of the sediment
quality triad approach used in the Netherlands.
7. BAY TOXICS RESEARCH PROGRAM SEDIMENT RELATED FINDINGS
Findings from the sediment related investigations supported under the jointly funded Toxics
Subcommittee/NOAA Chesapeake Bay Toxics Research Program were presented. Jeff Cornwell
presented findings to date from the ongoing sediment transport flux processes research projects (Appendix
A). Linda Schaffner presented findings from the ongoing sediment benthic mixing processes/community
effects research projects (Appendix B).
Sediment Transport/Flux Processes
Jeff Cornwell explained that the Chesapeake Bay Toxics Research Program uses an ecosystem
approach to looking at toxics. The research emphasis was built on a predecessor program which focused
on the effects of low dissolved oxygen on Chesapeake Bay living resources and ecosystem processes.
The Chesapeake Bay Environmental Effects Committee decided to keep the ecological processes focus
in the initial phases of the toxics research program, but recognized that as the program progresses, more
resources will have to be invested hi projects dealing with biological effects. The initial goals of the
Chesapeake Bay Toxics Research Program were to understand how Chesapeake Bay ecosystem processes
influence the transport, fate and effects of toxicants, and to understand the effects that representative toxic
substances have upon ecological processes, including trophic dynamics, hi the bay.
Jeff Cornwell made several introductory observations. He stated that physical and biogeochemical
processes are major controls on the distribution, transformation, and flux of contaminant at the sediment-
water interface. Resuspension is also a major source of contaminant particulates in the water column.
Redox processes, both chemical and microbial, can have a major impact on contaminant fate. Metal
cycling, through mineralization, precipitation as sulfides, and adsorption to oxides, may be strongly
affected by redox; organic degradation pathways may be redox-dependent.
Jeff Cornwell briefly reviewed the following ongoing projects:
• Role of plankton hi controlling the partitioning and transport of hydrophobic organic
contaminants in Chesapeake Bay - Investigators: J.E. Baker, H.R. Harvey and R.
Dawson.
• Resuspension and transport of sediment associated toxics in the northern Chesapeake Bay
- Investigators: L. Sanford, J Halka, J. Hill.
• Microbial degradation of chlorinated hydrocarbons under alternating redox conditions hi
Chesapeake Bay. investigators: D. Capone and J. Baker
• Direct measurements and biogeochemical controls of sediment-water flux of trace metals
from estuarine sediments. Investigators: J. Cornwell, D. Burdige, W. Boynton
Major findings of several studies were then presented.
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Initial Flux Studies at Mid-Bay Sampling Sites (Sanford et ah, Baker er ah, Cornwell)
Measurements:
• physical parameters: current velocity, direction, salinity, temperature;
• water/particulate chemistry: suspended sediment, organic carbon, hydrophobic organic
compounds (HOCs), metals;
• sediment chemistry: organic carbon, HOCs, metals, pore water solutes, 210Pb
Results:
• total resuspended mass generally represents less than 1mm of surficial sediment;
• the sedimentation rate is ~ 2100 g/m2/yr;
• burial delay tune is ~ 4-17 days;
• small (< 10 urn) particles account for the largest fraction of organic carbon, lipids and
suspended solids in all seasons;
• lipid distribution among particle size fractions reflects the biological contribution which
varies seasonally;
• partitioning of HOCs into particles does not correlate well with organic carbon content;
• neutral lipids may provide better indices of HOC partitioning into particles than either
organic carbon or total lipids alone.
Sediment Biogeochemical Transformation — Organics (Capone, Baker)
The objectives of this study were to characterize the chlorinated hydrocarbon spectra in surficial
sediments at one site in the mid-Bay and a heavily contaminated tributary site, and to examine the effect
of increasing periods of anoxia on the subsequent aerobic degradation and mineralization of several model
chlorinated hydrocarbons in batch sediment slurries.
Measurements:
• chlorinated hydrocarbon concentrations hi surficial sediment;
• degradation rates under variable redox conditions.
Results:
• direct evidence that anoxic incubation can enhance degradation under subsequent oxic
conditions;
sulfate reduction appears to be a necessary process for 2,4 dichlorophenol degradation;
sediments stored for 3 months exhibit complete disappearance of 2,4 DCP in aged,
sulfate depleted sediments in less than one month;
• acetate enhanced degradation rates.
Sediment Biogeochemical Transformation — Metals (Cornwell, Burdige, Boynton)
Measurements:
• rates of microbial/chemical transformation of sulfate, manganese, iron, pore water and
16
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•
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not inert; they can be returned to the water column and the ecosystem by a variety of
processes including direct flux and trophic transfer.
Selected results from the work of Riedel et al. with trace metals arsenic and copper (also
investigated effects of various oxygen conditions).
Copper flux was highest from oxic sediments and sediments with organisms.
Arsenic flux was high from sediments with anoxic overlying water column, slight
with oxic water and organisms and zero or negative in oxic sediment without
organisms
Effects are trace metal and organism specific.
Flux rates, averaged annually over the depth of the water column and the area
of the bay, are approximately enough to supply all the metals found in the water
column; therefore, fluxes likely to be important factor in trace element
concentrations in Chesapeake Bay.
Preliminary Findings from the work of Schaffner and Dickhut with organic contaminants PAHs
and PCBs.
Macrofauna enhance loss of compounds from the sediment; effect is greatest for .
compounds with low K^ (relatively less hydrophobic).
Possible mechanisms include bioaccumulation and transformation and
bioturbation and biosuspension which may directly remove sediments or alter the
geochernical environment in a way that enhances desorption processes.
Biosuspension is a potentially important process - resuspension by polychaete
Loimla medusa (common in lower bay) is of the same order of magnitude as flux
reported for sediment trap studies.
Resuspended material is depleted in the PCB 2-CB, the more hydrophilic
compound, but not benzo(a)pyrene, the more hydrophobic compound.
Organisms also enhance burial, e.g. benzo(a)pyrene profiles.
This rapid burial is associated with biogenic activity; at depth within the sediment
column burrow walls contain high concentrations of compounds while ambient
sediments contain no compounds (following a pulsed tracer).
Bioaccumulation and biotransformation are also likely to be of importance.
Organisms exhibit rapid uptake (via ingestion, adsorption, bioaccumulation) of
compounds deposited at the sediment-water interface —> this will increase
trophic transfer.
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Major findings of this research to date are as follows:
• Under 'average' conditions, bioturbation dominates sediment reworking throughout a significant
portion of Chesapeake Bay subtidal region - above the pycnocline hi upper bay, most of lower
bay, high mesohaline and polyhaline tributaries. This means that benthic organisms will have
major impacts on the transport, flux and burial of contaminants.
• Benthic organisms influence the cycling and fate of both metals and organic contaminants.
Especially important are direct and indirect processes that enhance flux, thereby increasing
contaminant residence tune within the Chesapeake Bay ecosystem. .Direct flux is enhanced via
activities such as bioturbation and burrow irrigation. Flux is enhanced indirectly via trophic
transfer.
* Mechanisms governing bioaccumulation and biotransformation of organic contaminants are poorly
understood, but are presently being investigated. Furthermore, bioaccumulation and
biotransformation are highly variable among benthic organisms. 'Model* organisms used in
laboratory studies are unlikely to present a representative view of benthic communities which
include numerous species comprising various phyla.
• Contaminant exposure increases disease susceptibility in the eastern oyster Crassostrea virginica.
Linda Schafmer explained the objectives of several individual projects and described the major
findings to date.
• Field studies of benthic boundary layers sediment resuspension processes and bioturbation in
Chesapeake Bay (e.g. Wright et al., Sanford et al.) demonstrate that:
'Average' physical conditions result in relatively little sediment resuspension, but the
resulting flux can be many times higher than inputs of 'new' material.
For lower Bay, critical shear stress for sediment entrainment is only exceeded when
strong currents interact with moderate waves; currents alone do not resuspend sediments.
Critical shear stress is reduced hi summer by biological activity.
For most of lower bay and many areas of upper bay mainstem regions, bed roughness
is predominantly biological and bioturbation dominates sediment mixing processes on
long and short tune scales.
In other areas of the estuary (low salinity regions of tributaries, areas affected by anoxia
or high levels of contaminants) the relative importance of bioturbation is less well
understood. Available data records often lack evidence of bioturbation, but this does not
preclude potential importance of bioturbation on shorter time scales (which may be erased
by erosional events) or the potential importance of things like burrow irrigation that alter
the biogeochemistry of sediments.
Laboratory studies (e.g. Riedel et al., Schafmer and Dickhut) are being used to evaluate
macrofauna effects on toxicant fate and transport.
- An important finding of both series of studies is that contaminants in the sediments are
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not inert; they can be returned to the water column and the ecosystem by a variety of
processes including direct flux and trophic transfer.
Selected results from the work of Riedel et al. with trace metals arsenic and copper (also
investigated effects of various oxygen conditions).
Copper flux was highest from oxic sediments and sediments with organisms.
Arsenic flux was high from sediments with anoxic overlying water column, slight
with oxic water and organisms and zero or negative in oxic sediment without
organisms
Effects are trace metal and organism specific.
Flux rates, averaged annually over the depth of the water column and the area
of the bay, are approximately enough to supply all the metals found in the water
column; therefore, fluxes likely to be important factor hi trace element
concentrations in Chesapeake Bay.
Preliminary Findings from the work of Schaffner and Dickhut with organic contaminants PAHs
andPCBs.
Macrofauna enhance loss of compounds from the sediment; effect is greatest for
compounds with low K^ (relatively less hydrophobic).
Possible mechanisms include bioaccumulation and transformation and
bioturbation and biosuspension which may directly remove sediments or alter the
geochemical environment in a way that enhances desorption processes.
Biosuspension is a potentially important process - resuspension by polychaete
Loimia medusa (common in lower bay) is of the same order of magnitude as flux
reported for sediment trap studies.
Resuspended material is depleted in the PCB 2-CB, the more hydrophilic
compound, but not benzo(a)pyrene, the more hydrophobic compound.
Organisms also enhance burial, e.g. benzo(a)pyrene profiles.
This rapid burial is associated with biogenic activity; at depth within the sediment
column burrow walls contain high concentrations of compounds while ambient
sediments contain no compounds (following a pulsed tracer).
Bioaccumulation and biotransformation are also likely to be of importance.
Organisms exhibit rapid uptake (via ingestion, adsorption, bioaccumulation) of
compounds deposited at the sediment-water interface — > this will increase
trophic transfer.
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Biotransformation of PAHs is being
biotransformation of a simple PCB (2-CB,
especially in polychaetes
observed in numerous taxa;
1 chlorine) also being observed,
Experiments to evaluate the mechanisms governing bioaccumulation (e.g.
equilibrium partitioning theory vs. sorption-desorption processes) are planned
for 1993.
Mechanisms governing uptake for a benthic suspension feeder, the eastern oyster, Crassostrea
virginica, are being investigated by Weston et al. through work in progress.
Other research focuses on effects on organisms. For example, Chu and Hale are examining
relationships between disease susceptibility and exposure to environmental contaminants for the oyster
Crassostrea virginica. They are finding a dose-related response where higher levels of contaminants lead
to increased rates of infection by Perldnsus marinus. Effects were also observed at toxicant
concentrations an order of magnitude lower than acutely toxic concentrations.
8. DISCUSSION
Rich Eskin led a discussion of the results presented in the forum in an effort to reach a consensus
on findings to be reported back to the Toxics Subcommittee for their consideration during the ongoing
reevaluation of the Basinwide Toxics Reduction Strategy. The discussion followed the format of the
questions outlined in the introduction to the forum.
• From the critical review of available data, have we defined/can we define the relative
magnitude and extent of contaminated sediments within Chesapeake Bay?
Rich Eskin began by saying that data is available to determine what areas need to be looked at
more closely. However, contradictory responses are obtained by different methods. The question arose
as to whether we have enough data to determine 3 categories: hot spots, medium intensity spots, and
areas that need further identification.
There was general consensus on three "hot spots" - Baltimore Harbor, Elizabeth River, and the
Anacostia River. There was also general agreement that there is not a ubiquitous contaminated sediment
problem in the Bay. Joel Baker noted, however, that the unexpected case of sediment contamination in
the Wye River suggests that problems do exist in areas other than the accepted "hot spots".
• Does this definition of the magnitude and extent of contaminated sediments within the Bay
give us reason to believe this identified (or potential) toxics issue is causing or could cause
and impact (e.g. bioaccumulation, toxicity) on Chesapeake Bay systems, on either a
Baywide, regional or local scale?
Determination of scale is another important issue for management and research decisions. The
scale of toxics problems will be much different than for the Bay's eutrophication related problems. The
spatial scale of resolution is extremely important from a management perspective, i.e., how big does it
need to be before it is of concern? Ray Alden suggested that management decisions should be made on
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a segment by segment basis. Variability of contamination levels even within highly impacted areas must
be addressed.
Another management concern is whether or not there is an overall benefit in reducing
contaminated sediments in a given contaminated site. The amount of cleanup that is actually beneficial
may vary from one site to the next.
There was general agreement among forum participants that management decisions must start at
the broad scale. The presence of different degrees of contamination was reiterated and the question was
raised whether there is enough data to characterize sites with varying degrees of sediment contamination
appropriately. It was suggested that an effective means of determining where to do future sampling is
to overlay grain size content data and critical habitat areas over existing sediment contaminant data.
Overlaps of where there are contaminated sediments in habitat areas is where further sampling is
required.
• Comparison of the magnitude and extent of contaminated sediments within Chesapeake bay
with other coastal systems (e.g. Puget Sound) or large water bodies (e.g. Great lakes).
Forum participants agreed mat this comparison was not worthwhile.
• What direction should the Toxics Subcommittee recommend the Chesapeake Bay Program
agencies take with regards to addressing contaminated sediments? Denoting Regions of
Concern (with contaminated sediments as a parameter for delineation), etc?
There is a need to incorporate biological effects, including benthic diversity, into the chemical
data in determining which areas are impacted. Human health issues also must be examined and a
thorough evaluation of bioaccumulation should be done. Joel Baker suggested that another possible way
to look at sediment contamination is through the water column into fish tissue and other food chain
contamination and resultant human health effects.
The suggestion was made that enhanced monitoring for toxics in the tributaries is required (e.g.
collection of metals data from the Virginia rivers). Others expressed that this is unnecessary because
effects on the mainstem would not be elucidated in this way. However, it's possible that effects from
tributary contamination are not seen in the mainstem because contaminants are being absorbed by the
sediments and therefore being retained with the tributary. Rich Eskin suggested that tributary health in
itself is important. There may be numerous small tributaries that have not yet been investigated. The
effect to living resources is unknown.
The idea emerged that there is a need to focus research and sampling, because of financial and
resource limitations, in areas where a known problem exists. This must be balanced with the need to
consider areas of critical habitat. Some areas already have biomonitoring stations in place. Direct
sampling for localized effects through directed research should target critical habitat areas that are known
depositional areas.
There was a consensus among the forum participants that it is too early to recommend to the
jurisdictions general/specific source reduction or remediation actions for contaminated sediments.
Undertaking of a structured set of applied and basic studies hi specific Regions of Concern to determine
the source fate and effects of sedimentary metals and organics follow directly after the identification of
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Chesapeake Bay Regions of Concern. Other directions suggested include the collection and synthesis of
existing data with an in-depth analysis of current status. Basic research to evaluate recovery tunes, and
formation of predictive models were also suggested.
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Ongoing Studies
Sediment Transport/Flux Processes
Appendix A
R/CBT-8 Investigators: I.E. Baker, H.R. Harvey and R. Dawson
Project Title: Role of plankton in controlling the partitioning and transport of
hydrophobic organic contaminants in Chesapeake Bay
Objectives: Determine the concentration and distribution of hydrophobic organic
contaminants in suricial sediments, sediment traps and 4 size fractions of suspended
particles
R/CBT-9 Invesigators: Larry Sanford, Jeff Halka and Jim Hill
Project Title: Resuspension and transport of sediment associated toxics in the northern
Chesapeake Bay
Objectives: 1) to investigate the resuspension and transport of fine sediments in the
northern Chesapeake Bay, characterizing temporal and spatial variability in resuspension
processes, 2) to invesigate the influence of resuspension on the tune varying flux of
toxics across the sediment-water interface, and to examine how resuspension affects
partitioning of toxics between continuously suspended particulates, bottom sediments and
dissolution and 3) to relate resuspension and transport of sediment associated toxices to
mor easily measurable or predictable sediment and physical forcing characteristics.
R/CBT-11 Investigators: Doug Capone and Joel Baker
Project Title: Microbial degradation of chlorinated hydorcarbons under alternating redox
conditions in Chesapeake Bay
Objectives: 1) to characterize the chlorinated hydrocarbon spectra in surficial sediments
at one site hi the mid-Bay and a heavily contaminated tributary site and 2) examine the
effect of increasing periods of anoxia on the subsequent aerobic degradation and
mineralization of several model chlorinated hydrocarbons hi batch sediment slurries.
R/CBT-12 Investigators: Jeff Cornwell, David Burdige and Walter Boynton
Project Title: Direct measurements and biogeochemical controls of sediment-water flux
of trace metals from estuarine sediments
Objectives: To determine 1) direct sediment-water exchange of dissolved trace elements
using box fluxes, 2) porewater and solid phase profiles of trace elements, organic carbon,
Mn, Fe, S and 3) measure rates of Mn, Fe and S reduction, Soxideation and trace
element production using radiotracers and incubation techniques.
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Appendix B
• ' Ongoing Studies on Benthic Community Effects
R/CBT-3 Investigator: D. P. Swift , •, •
Project Title: Particle-reactive pollutants in Southern Chesapeake Bay: accumulation,
resuspension and flux into the bottom
Objectives: to develop computational schemes that will allow estimation of the potential
flux of particle-reactive pollutants into the shallow seabed, based on the analysis of
hydraulic climate, and on measures of biological activity
R/CBT-4 Investigators: L. D. Wright, J. D. Boon, J. P.-Y. Maa and L; C. Schaffher
Project Title: Dynamics of sediment resuspension: bay-stem plains of lower Chesapeake
Bay
Objectives: to improve the ability to model the resuspension of bayfloor sediments by:
(a) determining the appropriate, tune-varying roughness lengths; (b) determining the
corresponding values of the resuspension coefficients; (c) establishing the appropriateness
of existing models to the Chesapeake Bay and determining the relative contributions of
physical as opposed to biological processes in resuspending sediments
R/CBT-5 Investigators: F.-L. Chu and R. Hale
Project Title: Relationship ,of pollutants to the onset of disease in the Eastern oyster,
Crassostrea virginica
• •• • , • "''•".'*,•' H; ' •"-: . • . " • '? '•.',".••••.,•'
Objectives: to examine the influence, of anvenvironmentally relevant complex mixture of
pollutants on the onset of the disease Perldnsus marinus in the eastern oyster, Crassostrea
virginica . .">.•;••• * • ,-* •:_.•.•,.&.•.• :„•.:,• ,,si,i • •;,*...:3.:
R/CBT-7 Investigators:'G.'Riedelj J. G. Sanders, R. W. Osman and C, C. Gilmour
Project Title:. The role of benthic infauna and fluctuating oxygen concentrations in the
flux of toxic trace elements from Chesapeake Bay sediments
Objectives: to understand the processes by which trace elements are transported into and
out of sediments, how benthic organisms or activities regulate the transport of such
elements between the sediments and the remainder of the ecosystem, and how these
processes are altered by periodic changes in the oxygen concentrations of bottom waters
R/CBT-15 Investigators: L. C. Schaffner and R. M. Dickhut
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Project Title: Role of benthic communities in sediment-associated toxic organic chemical
fate and transport in lower Chesapeake Bay
Objectives: to identify and quantify the role of macrobenthic organisms in sediment-
associated organic contaminant (PAH, PCB) transport and fate, including seasonal
variation; to evaluate .the rates of organic pollutant sorption/desorption and equilibrium
distribution on Chesapeake Bay sediment and relate these physical-chemical properties
to the uptake and bioaccumulation of organic contaminants
R/CBT-16 Investigators: D. P. Weston, D. L. Penry, R. I. E. Newell and J. Baker
Project Title: Uptake of dissolved and particle-associated toxicants by the eastern oyster
Objectives: to determine how the partitioning of toxic substances among dissolved and
particulate phases (including both organic and inorganic paniculate matter) affects
bioaccumulation by a benthic suspension feeder, and how quantification of this phase-
dependent bioavailability could be applied hi environmental risk assessment
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ROSTER OF ATENDEES
CONTAMINATED SEDIMENT CRITICAL ISSUE FORUM
December 10, 1992
Chesapeake Bay Program Office
Annapolis, Maryland
PARTICIPANT
Richard Eskin (Co-chair)
David Velinsky (Co-chair)
Ray Alden
Tom Armitage
Beverly Baker
Joel Baker
Rich Batiuk
DeanBaudler
Jeffrey Cornwell
Cece Donovan
Dan Fisher
Bob Foley
Dana Frye
Mary Jo Garreis
Ian Hartwell
Bob Huggett
Clay Jones
John Kennedy
Edward Krueger
Robin Laird
Beth McGee
Deirdre Murphy
Tom O'Connor
Harriette Phelps
Fred Pinkney
Chuck Prorok
Ted Ringger
Jackie Savitz
Linda Schaffner
Lydia Schlosser
Debra Trent
Allyson Ugarte
Mike Unger
Nathalie Valette-Silver
Elizabeth Watkins
Durwood Willis
AFFILIATION
• v • J •
Maryland Department of the Environment
Interstate Commission for the Potomac River Basin
Old Dominion University Applied Marine Research Laboratory
U.S. EPA Office of Science and Technology
U.S. EPA Office of Science and Technology
University of MD, Chesapeake Biological Lab
U.S. EPA Chesapeake Bay Program Office
Computer Science Corporation/CBPO
Univ...of Maryland/Horn Point Environmental Lab
Univ. of Maryland/Eastern Shore
Univ. of Maryland/Wye
U.S. Fish atfd Wildlife Service, Annapolis
Chesapeake Research Consortium/CBPO
Maryland Department of the Environment
Maryland Department of Natural Resources
Virginia Institute of Marine Sciences
Chesapeake Bay Commission
Virginia Water Control Board/CBO
Potomac Electric Power Company
U.S. Corps of Engineers, Baltimore District
U.S. EPA Office of Watershed, Oceans and Wetlands
Maryland Department of the Environment
NOAA National Status and Trends Program
University of the District of Columbia
Versar, Inc.
Computer Science Corporation/CBPO
Citizens Advisory Commission
Chesapeake Bay Foundation
Virginia Institute of Marine Sciences
USDA Soil Conservation Service
Virginia Water Control Board
U.S EPA OSW PSPD
Virginia Institute of Marine Sciences
NOAA National Status and Trends Program
Chesapeake Research Consortium
Virginia Water Control Board
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