United States
Environmental Protection
Agency
Research and Development
Environmental Research
Laboratory
Gulf Breeze FL 32561
Middle Atlantic Region 3
6th and Walnut Sts
Philadelphia PA 19106
Chesapeake Bay Program
TOXIC SUBSTANCES IN THE
CHESAPEAKE BAY
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903R811O8
TECHNICAL INFORMATION CLEARANCE
1 DATE PREPARED
3/81
2 LAB/OFFICE DRAFT NO.
CBP-TP-002
3. COPYRIGHT PERMISSION
(/one)
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5 PRESENT TITLE
Toxic Substances in the Chesapeake Bay
Estuary
a TECHNICAL INFORMATION PLAN TITLE AND REFERENCE
FY'81 Tech Info Plan, ERL-Narragansett
'(NOT ON FY'81 TIP as submitted)
6 AUTHOR. ORGANIZATION. AND ADDRESS
Owen P. Bricker
EPA, Chesapeake. Bay Program
Annapolis, Md. 21401
(Currently: US. Dept of Interior, Geologica
Survey. Water Resources Piv.. Reston. Va.
EPA PROJECT DOCUMENTATION
7 SERIES
9 CONTRACT/GRANT/lAG NUMBER
e \
10. TYPE OF MATERIAL (/ one)
SPECIFY (WHERE NECESSARY)
D RESEARCH REPORT
D PROJECT REPORT AND PROJECT SUMMARY
O JOURNAL PUBLICATION (include journal name)
O UNPUBLISHED REPORT
" O AUDIO VKSHAL
Q MEETING/PUBLICATION*
a APPLICATIONS GUIDE
Q SUMMARY/SYNTHESIS
D RESPONSE REPORT
* Other - Speeches/Paper
11 PROJECT OFFICER/fi^-HOU^E AUTHOR
a. SIGNATURE
Owen P. Bricker
\uAr-
b DATE
4/81
c. TYPED NAME AND ADDRESS ^
Owen P. Bricker (EPA, Ches. Bay Program)
(current) U. S. Dept of Interior, Geological Survey,
Water Resources Div., Reston, Va.
d. FTS TELEPHONE NO
928-6957
12 TECHNICAL INFORMATION (PROGRAM) MANAGER
a SIGNATURE
Dorothy Van Doren
c TYPED NAME AND ADDRESS
Dorothy Van Doren
Chesapeake Bay Program
2083 West St.
Annapolis, Md.' 21401
b DATE
4/81
d FTS TELEPHONE NO.
922-3912
13 COMMENTS
Paper prepared for Forty Sixth North American Wildlife & Natural Resources ?
Conference & Related Meetings, March 21-25* Shoreham Hotel, Wash. D. C.
Sponsored by Wildlife Management Institute. Paper used as reference for
speech.
CPA
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3/81
2 LAB/OFFICE DRAFT NO
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TOXIC SUBSTANCES IN THE CHESAPEAKE BAY ESTUARY
OWEN P. BRICKER*
ENVIRONMENTAL PROTECTION AGENCY
i
CHESAPEAKE BAY PROGRAM
»
ANNAPOLIS, MARYLAND
INTRODUCTION
»
The Chesapeake Bay is a geologically young estuarine system, born less
than 10,000 years ago when the Atlantic Ocean, rising in response to
"W-"- if-
meltwaters from receding Pleistocene glaciers, began'to flood the valleys
of the rivers draining the east coast of the North American continent. By
approximately 3,000 years ago, tidal waters were beginning to encroach on
the present mouth of the Susquehanna River at Havre de Grace and the
estuarine geometry was probably quite similar to that which we observe
today. The flooding process did not stop then, but the rate of sea level
rise decreased. Even today, the flooding continues at approximately 1.6
*
mm/yr. in the Chesapeake Bay area (Nichols, 1972). This rate of sea level
rise is larger than the world-wide average and reflects a local tectonic
component in addition to that caused by the increase in volume of sea
waters from melting ice caps. ' . .
<
Estuaries form a buffer zone between fresh water rivers and the sea.
- » *
They behave as very efficient sediment traps for particulate material
carried by the rivers and by the inflow of saline marine bottom waters
through their mouths. The sediment that accumulates in estuaries is
commonly a mixture of river bourne terrestrial debris derived from
^Current address: United States Department of the Interior, Geological
Survey, Water Resources Division, Reston, Va. 22092
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weathering and erosion of the tributary watersheds and coastal marine
sediment derived from the continental shelf (Mead, 1969; Hathaway, 1972).
From a geologic perspective, estuaries are very ephemeral features, quickly
filling with sediment from these sources. The lifespan of an estuary is a
function of the rate of change in sea level vs. the rate of accumulation of
sediment. In the Chesapeake Bay, the continuing rise of sea level
partially compensates for the rate of accumulation of sediments and the net
^
effect is a prolongation of the lifespan of the system. The estuary,
however, is a dynamic system, undergoing continuous evolutionary changes
which will ultimately'lead to its destruction^through infilling with
sediment.
The Chesapeake Bay began to experience impacts, in addition to those
caused by natural processes, from the time of first European settlement
along its shores. Clearing of land for agriculture and development has
greatly accelerated the rate of erosion in the adjacent land areas and
increased the amount of sediment delivered to the estuary by its tributary
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rivers. Perhaps an even more serious impact is related to the tremendous
technological advances that have been made through the years. Man has been
exceedingly ingenious in synthesizing and producing a miriad of new
chemical compounds, and in finding uses for an increasing variety of metals
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and, more recently, radionuclides. These substances enter the environment
through waste discharges and other disposal practices (e.g., industrial .
discharges, sewage effluents, land fills) by direct applications for
specific purposes (e.g., herbicides, pesticides, fertilizers) and via
atmospheric pathways (e.g., automotive exhausts, combustion of oil, coal
and wood, incineration of refuse, fugitive dusts from storage or disposal
sites, bomb testing). It is now clear that many of the substances that
were either purposely or inadvertently released to the environment are
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displaying unanticipated adverse affects on the biosphere. Historically,
estuaries have been favored localities for siting industries, power plants
and sewage treatment facilities. They provide an abundant supply of water
I
for industrial processes and for cooling power plants, they are a
convenient conduit for the disposal of a broad spectrum of wastes, and they
provide direct accessibility to marine transportation of raw materials and
1 "
finished products. As a consequence, estuaries have bourne the brunt of
man's activities. The Chesapeake Bay is no exception.
Toxic substances represent an obvious threat to the stability and
*^f j** * . «*
continued use of Chesapeake Bay resources. Recognition of the role these
substances play in determining the environmental quality and ecological
health of the Bay system requires a thorough understanding of chemical,
physical, and biological dynamics that constitutes the total estuarine
system. Definitive information on the sources, pathways, and fate of toxic
substances is scarce and, where available, usually limited to specialized
problems in restricted areas. In 1976, the Environmental Protection Agency
s
initiated a special program, the Chesapeake Bay Program, to begin to
address the role of toxic substances in the estuary in a comprehensive and
integrated fashion. The following discussion is a brief description of the
Chesapeake Bay Program toxic substances investigation including some of the
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< ^..T
findings that are beginning to emerge. . . - - ':
Two classes of materials, toxic substances and sediment, pose the
greatest threat to the environmental well being of the estuarine system.
These materials are intimately related in that many toxic substances,
»
inorganic and organic, associate strongly with sediment via
physico-chemical mechanisms. As a consequence, the sediment accumulating
on the bottom is the largest reservoir of toxic materials in the estuary
(Bricker and Troup, 1975).
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Sediments
The sediments that accumulate in Chesapeake Bay are important for a
number of reasons. From a physical- standpoint, sediments tend to fill in
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channels and harbours and thus create a need for periodic dredging in order
to maintain these facilities for their intended purpose. Dredging, in
turn, requires disposal sites for placement of the material removed.
Appropriate handling techniques and disposal site characteristics depend
%
upon the chemical components and physical properties of the spoil.
Suspended sediment creates turbidity which decreases the depth of light
penetration and may also affect its spectral distribution. The decrease in
intensity and shift in spectral qualities may adversely affect aquatic
plants. Large concentrations of suspended sediment tend to clog the gills
and filtering apparatus of filter feeders causing impairment or death.
Rapid sedimentation may cause burial and smothering of benthic fauna and
flora.
In the absence of sediments, however, the estuary would not be the
X
fertile and productive environment that it is. Sediments form a substrate
upon which rooted aquatic plants grow; they provide a habitat for burrowing
benthic organisms; they are a source of nutrients for benthic flora and
fauna. Sediments also carry with them metals derived from natural
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weathering and erosional processes and those introduced by man. Many of
these metals are essential to maintain a healthy biota, but if present in
excess are toxic. In addition, sediments are a vehicle for the transport
and localization of a large number of the anthropogenic organic compounds
that enter the -aquatic environment (Olsen, 1979). Both inorganic and
organic toxic substances have a great affinity for particulate matter of
small size and large surface area. Sites of accumulation of sediments
possessing these physical characteristics usually contain a significantly
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higher concentration of metals and organic compounds than sites of
accumulation of sediments of sand size or larger. Sediments thus play a
major role in the transport and distribution of toxic materials in the
i
estuary.
No systematic study of toxic materials in the Chesapeake Bay had been
attempted until the Environmental Protection Agency Chesapeake Bay Program
was initiated in 1976. In planning that program, it was concluded that any
^
toxic substances discharged into the Bay and its tributaries could have
direct impact during their residence time dissolved in the water; however,
"^y IP j»- ' . '.r* »
because of the rapid -water movement and concomitant dilution, these effects
Af ,
would be short lived. The most serious potential problems were identified
as those associated with toxic substances that accumulate in the sediment
and/or biota. These substances have a much longer residence time in the
system and may also build up to very high concentrations through sediment
sorption mechanisms or bioaccumulation. For these reasons, knowledge of
the distribution, amount, and physical characteristics of the recent
s
sediments in the Bay is fundamental to understanding the behavior and fate
of toxic substances in the estuary. In addition to the physical
characteristics, the content of organic carbon and sulphur play an
important role in determining the oxidation/reduction state of the "'
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<
sediments after deposition. The water content correlates with the
stability and ease of resuspension of the bottom and with the rate at which
dissolved substances diffuse through the sediment. The mineralogy of the
sediment provides information on the reactivity of the inorganic
«
particulate constituents. These parameters together form the framework
into which the chemical and biological pieces of the system fit.
The most basic data concerning sediments in the estuary are:
1. location in the system
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2. morphology of deposits
3. physical characteristics
4. rate of addition to the system
t
5. sources
6. sites and rates of present accumulation
In Chesapeake Bay, geophysical methods have been used to examine the
thickness and morphology of the bottom sediment (Maryland Geological
%
Survey, Virginia Institute of Marine Science open file reports). These
methods also provide information on some other sediment properties in that
sand and shell layersv-can be differentiated fjcom finer silty and muddy
sediments.
The physical characteristics of the surface sediments (particle size
distribution, water content) have been determined for the entire Bay; on a
1 km grid in Maryland waters and on a 1.4 km grid in Virginia waters. In
addition, these same properties have been determined on a selected suite of
meter length cores collected between the Susquehanna River and the Virginia
s
capes. Sediment, on the basis of particle size, displays a relatively
systematic distribution pattern with sand occurring in the shallow shore-
line areas and mud in the deeper mid-Bay regions. Between, there occurs a
zone of mixing of these two sediment types (Byrne, 1980; Kerhin, 1980).
<
This sediment work provides a description of the state of the system rela-
tive to sediments at the present time in history, and it will serve as a.
valuable baseline against which future changes can be measured.
Three major sources contribute sediment to Chesapeake Bay; tributary
rivers, shoreline erosion and marine inflow. The northern part of the Bay
is dominated by sediment carried via the Susquehanna River; the southern
Bay, by sediments transported by inflowing coastal marine waters; and 'the
mid-Say region, by sedl-.ents derived frors shoreline erosior..
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Each of the tributary rivers, with exception of the Susquehanna, is
characterized by an estuarine segment in its lower reaches. A large part
of the sediment carried by these rivers is trapped in their lower estuarine
portions and never reaches the main Bay. As a consequence, infilling of
«
the middle portion of the Bay is occurring at a slower rate than to the
north or the south, with fine particle size sediment that escapes the
tributary estuaries collecting in the deeper areas and coarse sediment
^
derived from shoreline erosion accumulating in the shallow waters adjacent
to the shorelines. The Susquehanna River debouches directly into the upper
~y^5>- m w»
Bay and the bulk of the sediment it carries is deposited there. Sediments
from the continental shelf, carried into the Bay in the saline bottom
waters, dominate the southern segment of the Chesapeake Bay.
It is important to know what changes have occurred in the system in the
past so that predictions can be made concerning future trends. In order to
understand how the system has changed from past to present, and-to identify
impacts related to man's activities, we must rely on information recorded
s
in the sediment. To interpret this record, we must first know the time
interval represented by the record. Three independent methods for
deciphering the time (rate) of sedimentation have been employed in the
Chesapeake Bay: 1) comparison of historical bathymetrie charts, 2) pollen
*" 01 f\
biostratigraphy, and 3) Pb* u geochronology. Parts of the Bay have been
surveyed bathymetrically at irregular time intervals beginning in 1846.
Where these surveys overlap, the change in depth represents the amount of
deposition (or erosion) that has occurred during the time between surveys
(Maryland Geological Survey, Virginia Institute of Marine Science, open
file reports). A second technique is based on pollen biostratigraphy, that
is, the identification of specific time horizons in the sediment recognized
by pollen distribution. For instance, the time of disappearance of
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American chestnut in the 1930 's, in response to the chestnut blight, is
recorded by the absence of chestnut pollen in sediments deposited after
that time. Other identifiable horizons, both older and younger, have been
t
recognized in Chesapeake Bay sediments and are valuable time markers in
«.
this system (Brush, 1980). A third technique employs the decay of a
010 0*^8
radioactive isotope of lead. Fb , a member of the U series, is
continuously being added to the earth's surface environment. It adsorbs
^
strongly onto sediment particles and is deposited with them wherever they
accumulate. Once buried beneath the sediment-water interface, no additional
210
Pb can be added, and that contained in the sediment continues to decay
at a constant rate (half life = 22.5 years). This permits the dating of
sediments back to approximately 100-125 years B.P.(5 x half life) (Setlock
and Helz, 1980). Each of these methods provides an estimate of the rate at
which sediment has accumulated at the site sampled. In areas of the Bay
where sedimentation rates have been determined by either two or all three
of the above techniques, the correspondence is usually quite good. Using
/
this information the age of a particular layer or bed of sediment can be
dated by its depth beneath the surface. If a change in the concentration
of any toxic substance is observed as a function of depth, the rate of
loading of that substance can be inferred and projections made about future
*
c
concentration trends. The time of introduction of various substances into
the system can also be documented. Data about sedimentation rates are
directy useful in planning dredge disposal sites, locating channels to
provide minimum maintenance, and estimating the frequency and volumes of
material that will have to be dredged in order to maintain harbours and
channels in various parts of the system.
Toxic Substances
Along with knowledge of the distribution and physical characteristics
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of bottom sediments in the estuary, it is necessary to know the concentra-
tions of the toxic substances they contain if these materials are to be
effectively managed.
i
Two major classes of toxic materials are particularly important to the
estuarine environment; metals and anthropogenic organic compounds. Metals
are derived from natural weathering and erosion of the metalliferous
Piedmont rocks underlying the watersheds of many of the Bay tributaries,
and from man's activities. Most of the organic compounds of environmental
concern are strictly the product of man's chemical ingenuity. These sub-
"*V \ -3~ * fi** *"
stances enter the system via direct discharges^ in input from the
*3f- *
tributaries, in non point source runoff, and through atmospheric pathways.
The distribution of these materials in surface sediments (upper few
centimeters) is a result of recent deposition and accumulation in the
estuary. Dated cores provide information on how the concentrations of
these materials have changed with time in the sediment. Because metal
behavior is better understood and analytical methods for metals are more
s
straightforward and less expensive than those for organic compounds, the
data for metals in the estuarine environment is much more detailed than
that for organic compounds. Emerging evidence over the past decade
suggests, however, that synthetic organic compounds may be of greater
»
* -
concern than metals from the standpoint of environmental degradation of
aquatic systems. * ~ -
The similarity in behavior between metals and many organic pollutants
with respect to sorption behavior on fine particle size sediment suggest
that metals may be used as surrogates for predicting the transport and
accumulation of many organic pollutants. A limited number of samples of
surface sediment from the main stem of the Chesapeake Bay have been
analyzed for organic compounds using glass capillary gas chroraatography/
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mass spectrometry and corroborate this hypothesis. Preliminary inspection
of both the metals data and the organics data show that the highest
concentrations of these substances occur in samples from tributary mouths,
t
suggesting that the tributaries act as sources of these materials to the
main Bay (Huggett, 1980). Not surprisingly, the highest concentrations
were observed at the mouths of the Susquehanna, Patapsco, and James Rivers.
The technical complexity and expense of analyzing estuarine samples for
"*
organic compounds led to the development of a strategy for maximizing the
output of data of the -type that would be most useful to identify potential
problems with these compounds. Instead of trying to identify each peak
(compound) on GC/MS traces, a process that would be inordinately time
consuming and expensive, the complete GC/MS output from each sample is
stored on the computer. Subsequent sampling at the same localities using
the same analytical procedures can disclose changes in peak height
(concentration) for the organic compounds. If there has been a significant
increase in any peak from one sampling period to the next, the compound
represented by that peak can be identified and evaluated with respect to
its toxicity and potential impact on the system. Possible sources of the
compound can be identified by concentration gradients provided by a more
detailed sampling grid in that particular area of the Bay, and appropriate
f
<
regulatory measure instituted. The chances of associating a particular
compound with its source are increased by performing identical analytical
work on industrial, municipal sewage treatment plant and power plant
discharges into the Bay (Monsanto Research Corporation, 1980). By
periodically analyzing effluent discharges, it may be possible to stop a
potential toxic problem at a very early stage before the substance has been
discharged into the environment in large quantities. The frequency of
sampling, however, must be appropriate to correspond to changes in process
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or treatment in the plants. One serious drawback is that the direct
discharge analysis may not detect some toxic substances present in very
small concentrations, yet if these "substances are strongly sorbed by
sediment or bioaccumulated by organisms, they may build up to dangerously
high levels in the environment. By emphasizing the sediment and biota
sampling in the estuary, and supplementing this with periodic sampling of
effluent discharges, it may be possible to manage toxic substances from
point sources in a much more effective manner than is presently being done.
An up-to-date inventory of raw materials, processes and finished products
VV^- if"
from all dischargers into the- estuary would aid greatly in assessing the
loading of toxic materials in the Bay system.
Coupling the data on toxic subtances in the sediment with the
compositions and volumes of industrial discharges and the type of inventory
data described above, it will be possible to identify those substances that
accumulate in the environment and permit estimates of mass-balance budgets
for specific toxic substances of concern. Combining this information with
s
the distribution and physical characteristics of the sediment will disclose
specific toxic substance-sediment associations. Extending this type of
work to dated core samples will provide estimates of changes in loading of
toxic substances with time.
*
Perhaps as important as knowledge of the identities and spatial
distribution of toxic substances in the estuary is an understanding of how
these substances behave in the environment. After deposition and burial in
the bottom, sediments and associated toxic substances are exposed to an
anoxic reducing environment. This leads to changes in speciation,
desorption, dissolution and remobilization of many elements (Elderfield and
Hepworth, 1975). Three major mechanisms lead to the re-introduction of
these materials at the sediment surface and to the water column:
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1) transport in the dissolved state in the interstitial water via diffusion
and/or advection, 2) physical transport of sediment and interstitial water
by benthic infauna (bioturbation, irrigation, ventilation), and 3) physical
*
disturbance of the sediment by storms and by man's activities (dredging,
propeller wash, etc.). Investigation of the metal and organic content of
the sediment areally and with depth provides information which permits
prediction of the chemical impacts of re-exposure of sediments at the
1 ^
surface. Sampling and analysis of interstitial waters provides a data base
from which flux of metals and nutrients- into the water column can be
calculated. Available data disclose that the sediment behaves as an
important source of nutrients to the estuary (Maryland Geological Survey,
open file reports). At certain times of the year, a significant flux of
dissolved manganese and iron into the deep bottom waters is also observed.
Data for other metals are not yet available. In addition to nutrient and
metals flux calculations, the interstitial water chemistry provides
critical information on the reactions that occur within the sediment and
J
the composition of the aqueous environment in which the benthic infauna
live.
Examination of the benthic fauna, particularly the infauna, is
providing a picture of the distribution of organisms in the estuary as a
»
< ' "
function of salinity, sediment type, and depth beneath the sediment-water
interface (Maryland Geological Survey, Virginia Institute of Marine
Science, open file reports). These studies document the effects of the
benthic communities on the disturbance and mixing of the sediment
(bioturbation), the stabilization-destabilization of the bottom sediments
relative to erosion and resuspension, and the role of burrows and other
biogenic structures on physical and chemical processes occurring in the
sediments. Benthic organisms are restricted in their mobility and
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therefore must adapt to any changes that occur in the local environment.
For this reason, benthic organisms may be good early warning indicators of
environmental degradation. Investigations in the main Bay have disclosed
cycles of colonization and extermination of benthic fauna in the deep
trough along the Eastern Shore, apparently in response to the yearly summer
development of anoxia in the bottom waters (Reinharz and Diaz, 1980).
Systematic examination of benthic communities Baywide, and particularly in
the tributaries, may identify areas subject to environmental stress. These
areas would be prime targets for detailed investigations of the causes of
the stress. The response of organisms; distribution, abundance, species
diversity, histopathologic features, genetic effects and other biologic
effects could be used as indicators of the state of health of the particu-
lar segment of the system in which the organisms live. The foundation for
developing an assessment strategy based on biologic criteria is a thorough
description of the estuarine benthic organism communities in conjunction
with the physical and chemical characteristics of the environment in which
s
t
they live.
Present Status of Toxics in the Chesapeake Bay
The past decade has witnessed disturbing changes in the ecosystem
of the Chesapeake Bay. Among the more widely publicized of these have
been the decline and virtual disappearance of rooted aquatic plants
from much of the Bay, the steady decrease in the abundance of striped
bass and oysters, the cessation of the spring shad runs in the upper Bay,
poor yields of clams and fluctuating, but generally declining catches of
crabs. Individually, any one of these could be attributed to a biological
cycle or some other natural phenomenon. Taken together, however, the
implications are more ominous. Over the years, however, the Bay has
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been under increasing pressures from a variety of man's activities. The
harvesting of shellfish and finfish by commercial watermen and sports
fishermen has not been effectively regulated from the standpoint of pre-
11
serving the resource. An expanding population on the shores of the Bay and
in the watersheds of the Bay tributaries, has tremendously increased the
volume of sewage effluent delivered to the estuary. Increasing need for
»
energy has led to the siting of conventional and nuclear power plants on
^
the shores of the Bay and along its tributary rivers. Continued indus-
trial development in the Bay area has burdened the estuary with increased
volumes of chemically^omplex discharges. Clearing land for agriculture
and for development has greatly increased the loads of suspended sediment
carried to the estuary. Chemicals in runoff from agricultural areas and in
storm drainage from city streets, parking lots and highways ultimately end
up in the Bay. Only recently has it been recognized that many toxic sub-
stances, including metals and organic compounds, are transported atmospheri-
cally and enter the surface environment via precipitation and by dry fall-
>
out. The sources of these pollutants are often far removed from where they
impact the earth's surface. Each of these insults takes its toll on the
finite assimilative capacity and resiliance of the estuarine environment.
Cumulatively, they may have reached the stage at which they exceed the
+
regenerative capacity of certain parts of the resource. In turn, this may
have led to the decline and/or disappearance of some of the more sensitive
biota. - .
What can be done to halt the degradation and reverse these trends? The
tendency in the past has been to look for a single cause of the problem,
such as toxic substances or excess nutrients and, thus far, the search has
been less than successful. The estuarine system is very complex and each
of the diverse activities mentioned above has an impact on the system; some
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greater than others. We observe the net integrated effect of all of these
factors acting in concert, and it is thus not surprising that no simple
answers have been found. Only two areas of the Bay, the Elizabeth River
i
and Baltimore Harbor, show serious environmental degradation that can be
directly attributed to toxic substances (Villa and Johnson, 1974; Johnson
and Villa 1976; Chu-fa Tsai et al, 1979). Even in these localities it is
not possible, at present, to identify the specific effects of individual
%
toxic elements or compounds. Over most of the Bay the effects are much
more subtle and no direct cause and effect relationships have yet been
demonstrated.
Effective management of toxic substances in the estuarine environment
requires regulation of the amount of each toxic substance delivered to the
system from all sources in order to keep environmental concentrations below
the level at which adverse impacts can potentially occur. This regulation
must be based on a firm understanding of the behavior and fate of natural
and anthropogenic toxic substances introduced into the system; the effects
of these toxic substances on estuarine biota; the identification of the
sources contributing toxic substances; and quantification of the load of
each substance delivered by each source. At the present time, there is no
comprehensive inventory of loadings to the system and there is only frag-
*
<-
mentary information concerning the types and concentrations of toxic sub-
stances already in the environment. There is a moderate body of informa-
tion relative to the behavior and fate of metals in the estuarine environ-
ment; however, similar information about toxic organic compounds is
difficult or impossible to find. Perhaps the largest gap is in our under-
standing of the effects of toxic substances, both metals and organic
compounds, on the estuarine biota.
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The Environmental Protection Agency Chesapeake Bay Program represents a
beginning effort to address these questions; however, research of this
nature must be intensified and expanded if it is to provide the data
t
necessary to develop an effective program for the management of toxic sub-
stances in the estuarine environment. Future ^Federal and state programs
should make every attempt to build on. this data and expand our understanding
of toxic substances in the Chesapeake Bay system.
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REFERENCES
BRICKER, O.P., TROUP, B.N. (1975) Sediment-water exchange in Chesapeake Bay.
In Estuarine Research, Cronin, L.E., ed, Academic Press, N.Y., 1, 3-27
BRUSH, G. (1980) Report on Pollen Biostratigraphy to EPA/Chesapeake Bay
Program
BYRNE, R. (1980) Report on Sediment Distribution in Virginia Waters to EPA/
Chesapeake Bay Program
CHU-FA TSAI, Welch, J., KWEI-YANG CHANG, SHAEFFER, J., CRONIN, L.E., (1979)
Bioassay of Baltimore Harbor Sediments/ Estuaries 2_, 141 - 153.
ELDERFIELD, H., HEPWORTH, A. (1975) Diagenesis, Metals and Pollution in
Estuaries. Marine Pollutions Bull. 6, 85 - 87.
HATHAWAY, J.C., 1972, Regional Clay-Mineral Facies in the Estuaries and
Continental Margin of the United States East Coast, in Nelson, B.W., ed.,
Symposium on estu.aries: Geol. Soc. Am. Mem. 133, p 293 - 316.
f£~
tg^
HUGGETT, R. (1980) Report on Organic Compounds to EPA/Chesapeake Bay
Program.
JOHNSON, P.G., VILLA, 0. (1976) Distribution of Metals in Elizabeth River
Sediments. EPA Technical Report No. 61, Annapolis Field Office
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9
*
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