EPA 903-R-96-00:
CBP/TRS 145/96
May 1996
Contaminants in
Chesapeake Bay Sediments
1984-1991
Chesapeake Bay Program
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Contaminants in
Chesapeake Bay Sediments
1984-1991
•'•V
TA
Richard A. Eskin, PhD.
Kathryn H. Rowland
Diana Y. Alegre ,
May 1996
_o:'ttuition HesOUTO86CSfllBf
jS EB\ (3404)
40iMStreei,SW
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
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ACKNOWLEDGMENTS
Many scientists and managers from various universities, state, federal, and regional
agencies involved in the Chesapeake Bay Program's restoration and protection
activities contributed data to this report and/or provided insightful comments that
improved the report. In alphabetical order, those agencies are:
Interstate Commission on the Potomac River Basin
6110 Executive Boulevard, Suite 300
Rockville, MD 20852-39.09
Maryland Department of the Environment
2500 Broening Highway
Baltimore, MD 21224
US Environmental Protection Agency
Chesapeake Bay Program Office
410 Severn Avenue, Suite 109
Annapolis, MD 21403
Virginia Department of Environmental Quality
P.O. Box10009
Richmond, VA 23240-0009
Virginia Institute of Marine Science
College of William and Mary
Gloucester Point, VA 23062
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Table of Contents
I. Introduction
II. Methods
III. Mainstem Data Collection and Analysis
IV. Tributaries
V. Baltimore Harbor and Back River
VI. Elizabeth River
VII. Anacostia River and the Potomac River Near Washington, D.C.
VIII. Interpretation of Trace Metal Concentrations in Chesapeake Bay Sediments
IX. Discussion and Conclusions
Appendices
A. Chesapeake Bay sedimentation rates
B. Quality assurance/quality control data for the Virginia Institute of Marine Science
Laboratory
C. Quality assurance/quality control data for sediment metals analysis at the
Maryland Department of Health and Mental Hygiene
D. Quality assurance/quality control data for sediment total organic carbon
measurements of the Chesapeake Biological Laboratory
E. Sediment grain size composition analysis methods
F. Quality assurance/quality control data for the Maryland Department of
Agriculture
References
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Introduction
The 1987 Chesapeake Bay Agreement committed the signatories to the development and adoption of
a strategy to reduce chemical contaminants in the Bay to levels that will ensure the "protection of
human health and living resources" (Chesapeake Executive Council, 1987). The Chesapeake
Basinwide Toxics Reduction Strategy, signed in January 1989, included a long-term commitment to
"design and implement a long-term sediment monitoring program to identify the location and extent of
contaminated sediments within the Bay and its tidal tributaries and to track multiple-year trends in
sediment concentrations of toxics" (Chesapeake Executive Council, 1989).
This report presents data on sediment chemical contaminant concentrations in the Chesapeake Bay
and its tidal tributaries collected between 1984 and 1991. The majority of this data collection was
coordinated by Maryland and Virginia with support from the Chesapeake Bay Program. Data collected
by the U.S. Environmental Protection Agency, National Oceanic and Atmospheric Administration, and
the Interstate Commission on the Potomac River Basin are also presented for purposes of comparison
and to provide supplementary data to that collected by Maryland and Virginia.
The primary objectives of this report are to describe the spatial patterns in the distribution of sediment
chemical contaminants in Chesapeake Bay and to compare sediment chemical contaminant
concentrations in Chesapeake Bay to sediment quality guidelines in order to identify areas where
sediment chemical contaminants may adversely impact aquatic biota. Trends and year-to-year
differences in concentrations of sediment chemical contaminants evident from the monitoring program
are discussed to the extent possible with limited data. Where possible, the recently collected data are
compared with data available from the 1970s and early 1980s to determine whether there is any
evidence that sediment chemical contaminant concentrations in Chesapeake Bay sediments are
changing.
Following this introductory chapter, Chapter 2 provides information on the methods used in gathering
the data discussed throughout the remainder of the report. Discussion of the sediment chemical
contaminant concentration data is organized into several chapters which deal separately with distinct
geographic regions of the Bay. namely the mainstem Bay (Chapter 3), the tidal tributaries (Chapter 4),
Baltimore Harbor and the Back River (Chapter 5). the Elizabeth River (Chapter 6), and the Anacostia
and upper Potomac rivers (Chapter 7). Each of these chapters begins with a description of the
sampling program and the sediment characteristics in that area, followed by a brief summary of the
data with respect to each class of chemical contaminants. This summary is followed by discussion of
the data with respect to individual chemical contaminants. Following the presentation of data for each
of these geographic areas. Chapter 8 provides a preliminary analysis of sediment trace metal
concentrations in Chesapeake Bay sediments and identifies stations at which sediment concentrations
of one or more trace metals are probably elevated due to anthropogenic activities. Chapter 9
discusses baywide patterns in sediment chemical contaminant concentrations and ranks areas of the
Bay according to the potential risk to aquatic biota posed by exposure to the measured sediment
concentrations of chemical contaminants.
Sediments as a Habitat
Many aquatic organisms live in or on bottom sediments. Animals and other lesser organisms that live in
or on the sediment are called benthic organisms or just "benthos." Examples include clams, oysters,
clarnworms, and bloodworms used for fish bait, crabs, small shrimp-like organisms called amphipods,
and bottom fish such as flounder.
Benthic organisms modify the characteristics of the sediment they live in by building tubes and burrows,
by binding sediment particles together with mucus, and by ingesting the sediment itself and egesting it
after its nutrients have been removed (Jones and Jago, 1993). Tubes and burrows, along with the
filtering activities of benthic organisms during feeding, can enhance the exchange of materials between
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the sediment and the overlying water, and can create zones of oxygenated sediment in layers that
would otherwise be anoxic i.e., completely without oxygen. Burrowing and feeding activities also mix the
sediment, causing "bioturbation" which may bury or release contaminants bound to sediment.
Bioturbation may also homogenize the top 20 cm of bottom sediments. Because bioturbation has the
effect of mbdng recently deposited sediments with older, previously deposited sediments, bioturbation
makes it difficult to determine when a given layer of sediment was deposited.
The particle size of sediments plays an important role in determining which benthos can exist in a
particular benthic habitat. For instance, benthic organisms which feed on organic deposits in the
sediment tend to be found in areas with siltier sediments, while organisms which feed by filtering
suspended particles from the water column are typically predominant in sandier sediments (Day et a!.,
1989). Thus the percentage of the finest particles in the sediment, the silt and clay particles, is an
important sediment characteristic. Depending on the percentage of each size class of particles, a
sediment may be categorized as sand, muddy sand, sandy mud, or mud (Table 1.1).
Other environmental characteristics are typically associated with specific types of sediment. For
example, muddy sediments are generally found in areas where the overlying water currents are
minimal, since fast currents will not allow fine particles to settle. The large surface area of sediments
composed predominantly of fine particles can support large bacterial populations, and fine sediments
consequently often have high rates of decomposition of organic material and high respiration rates.
This rapid sediment metabolism combined with slow water movement often results in fine, muddy or
silty sediments being low in oxygen or "reduced".
Table 1.1 Categorization of sediments by grain size composition
Category
Sand
Muddy Sand
Sandy Mud
Mud < 15
Percentage Sand
(Particles 62-1 000 urn)
290
>50
sSO
285
Percentage Mud
(Particles ,62 urn)
<10
<50
>50
Source: Scott et a/. 1988
Types of Sediment Associated Chemical Contaminants
Sediment chemical contaminants include trace metals, polycyclic aromatic hydrocarbons, and
chlorinated organic compounds and pesticides. Each of these categories is discussed briefly below.
The Chesapeake Bay Program has designated several toxic substances from these categories as
Chesapeake Bay Toxics of Concern (Chesapeake Bay Program. 1991 a) due to toeir significant
potential to be deleterious to the Chesapeake Bay. The Chesapeake Bay Program has also identified a
list of chemicals which are being considered for designation as Chesapeake E jy Program Toxics of
Concern, but for which more information on toxicity and abundance in the Chesapeake Bay basin is
needed (Chesapeake Bay P/ogram, 1991 a).
Trace Metals
Trace metals are naturally present in sedimentsf. Trace metals are also] released to the environment
through municipal and industrial wastewater, the burning of fossil fuels, [the weathering and corrosion]
oxidation of metals, and leaching from landfills (MacDonald, 1993). Some trace metals are used in
wood preservatives, paints, and pesticides, and may be released into the environment from these
sources as well (Macdonald, 1993). Eight trace metals have been routinely monitored in Chesapeake
Bay sediments: arsenic, cadmium, chromium, copper, lead, mercury, nickel and zinc.
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Cadmium, chromium, copper, lead, mercury, and tributyl tin are Chesapeake Bay Toxics of Concern
(Chesapeake Bay Program, 1991 a). Arsenic and zinc are on the list of chemicals under consideration
for inclusion on the Toxics of Concern list, but for which more information is being sought (Chesapeake
Bay Program, 1991 a).
Polycyclic Aromatic Hydrocarbons
Polycyclic aromatic hydrocarbons (PAHs) are organic compounds composed of two or more fused
aromatic rings (Macdonald, 1993). PAHs are produced by the high temperature combustion of organic
matter such as fossil fuel combustion occurring in automobile engines, coal-fired electric power plants,
and wood fires (MacDonald, 1993). PAHs may also enter the aquatic environment via oil refinery
effluents and spills of petroleum or petroleum-based products (Macdonald, 1993). The anthropogenic
inputs of PAHs have greatly increased environmental PAH concentrations and PAHs are now
ubiquitous in the environment (Menzie et a/., 1992). Many individual PAHs have been monitored in
Chesapeake Bay sediments, including anthracene, benzo[a]pyrene and fluoranthene.
Polycyclic aromatic hydrocarbons which have been designated as Chesapeake Bay Toxics of Concern
are benzo[a]anthracene, benzo[a]pvrene, chrysene, fluoranthene and naphthalene (Chesapeake Bay
Program, 1991 a). No PAHs are on the list of compounds for which more information is being sought.
Chlorinated Organic Compounds and Pesticides
Chlorinated organic compounds include many pesticides, polychlorinated biphenyls (PCBs), dioxins
and furans. Several organochlorine pesticides were previously widely used, but are either no longer
registered for use in the U.S., or their uses have been narrowly restricted, e.g., DDT and chlordane,
(MacDonald, 1993). These compounds are still of concern, however, because they are extremely
persistent in the environment (MacDonald, 1993). Other less persistent organic compounds containing
chlorine or other halogens are still used as pesticides in the Chesapeake Bay area, e.g., alachlor, while
other commonly-used pesticides, such as carbofuran, do not contain chlorine or other halogens
(Chesapeake Bay Program, 1994).
PCBs are extremely persistent man-made compounds that have been widely used in electrical
transformers and various industrial applications (Chesapeake Bay Program, 1991b). The U.S. banned
production of PCBs in the late 1970s, but poor operating and disposal practices involving products and
equipment containing PCBs can lead to environmental contamination (MacDonald, 1993). PCBs can
exert chronic, sublethal effects on aquatic organisms (Kennish et a/., 1992). PCBs are also of concern
because they have considerable potential to accumulate in the tissues of aquatic organisms (Kennish
et al., 1992).
Chlorinated dioxins and furans are two families of compounds with a basic structure consisting of two
benzene rings linked by one or two oxygen atoms (MacDonald, 1993). These compounds are
generally produced unintentionally, either during chemical manufacturing, the incomplete combustion
of materials containing chlorine atoms and organic compounds, or during the bleaching process at pulp
and paper manufacturing plants (MacDonald, 1993).
The PCBs and the pesticides alachlor, atrazine and chlordane have been designated Chesapeake Bay
Toxics of Concern (Chesapeake Bay Program, 1991a) while aldrin, dieldrin, fenvalerate, metolachlor
and permethrin are nominees for inclusion. (Chesapeake Bay Program, 19915).
Sediments as a Source or Sink for Chemical Contaminants
The fate of chemical contaminants in the aquatic ecosystem is determined by a complex combination
of biological, geochemical, and physical processes associated with the sediment environment
Chemical contaminants initially associated with sediments may be taken up by aquatic organisms,
released to the overlying water, or permanently buried within the sediments. Chemical contaminant
adsorption to sediment particles, precipitation of insoluble metal compounds, colloidal flocculation and
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biological uptake all play a role in depositing chemical contaminants in the sediments. Thus, sediments
can act as a "sink" for many chemical contaminants and concentrations of metals and organic
contaminants are typically much higher in sediments than in the overlying water column (Helz et at.,
1975).
Chemical contaminants associated with sediment particles may become buried as they are covered by
additional sediment The burial of contaminated sediments may be slowed by disturbance of the
sediments caused by bioturbation or storms or dredging operations which move or remove more
recently deposited sediments. Sediment-associated chemical contaminants may also be transported
from one area to another by tide and wind-driven currents.
The adherence of chemical contaminants to sediment particles is dependent upon the chemistry of the
surface sediments and that of the overlying water. While chemical conditions usually favor the removal
of chemical contaminants from the water column through binding to sediment particles, changes in
physical or chemical characteristics of the sediment environment or the overlying water column can
convert the sediment from a "sink" to a "source" of toxic substances to the water column, or vice versa,
often on a seasonal basis. For example, changes in oxygen availability, physical disturbance such as
dredging, or bacterial or geochemical decomposition of organic matter may effect the release of
sediment-associated chemical contaminants.
Both metals and organic contaminants can be removed from the water through adherence to iron and
manganese oxides or organic material which frequently coat the surfaces of sediment particles
(Luoma, 1990). Since finer sediments have a greater surface area for a given mass than coarser
sediments, fine sediments generally have a greater capacity to adsorb chemical contaminants. Thus,
the concentrations of chemical contaminants are often higher in fine sediments than in coarser
sediments.
Bioavailability of Chemical Contaminants in the Sediment
Exposure of organisms to sediment-associated chemical contaminants can occur through the ingestion
of sediment or interstitial water, direct physical exposure of the gills or body wall to sediment or
interstitial water, and the partitioning of the chemical contaminant between sediment, water, and
organism. Biological availability from each of these exposure pathways will vary with the chemical and
physical characteristics of the chemical contaminant as well as wfth the characteristics of the organism
and sediment. Significant uptake of chemical contaminants from sediments has been found, for
example, for cadmium by polychaete worms and amphipods (Kratzenburg and Boyd, 1992; Ankley et
at., 1991; Mac eta!., 1990; Tay, 1989) and for polycyctic aromatic hydrocarbons (PAHs) by chironomids
(Clements, e/. a/, 1994).
The bioavailabilrty of metals is often affected by oxygen availability (Luoma. 1990). When the
concentration of oxygen is low, sulfur becomes reduced and divalent metals may precipitate as sulfides
and be less bioavailable. In oxygenated sediments, trace metals may bind to iron and manganese
hydroxides and organic matter (Luoma, 1990). The properties of the trace metal and the availability of
various potential binding sites in the sediment will determine the bioavatlability of a given trace metal.
The concentration of total organic carbon in sediments has significant effects on the bioavailabilrty of
non-ionic organic contaminants in sediments (DiToro et a/., 1991).
Sediment Accumulation Rates
Knowledge of sedimentation rates helps to determine potential areas of accumulation of potentially
toxic substances and the period over which sediment-associated chemical contaminants may have
been deposited (Brush etal., 1982). Officer era/. (1984) used Pb-210 to date sediments from cores
and estimated average sedimentation rates of 0.76 cm/year and 0.35 cm/year for the Maryland and
Virginia portions of tine mainstem Bay, respectively. However, because sedimentation rates vary widely
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in space and in time, average sediment accumulation rates for large areas are of limited value. Since
sediment accumulation rates were not determined as part of the various sediment contaminant
monitoring programs conducted in Chesapeake Bay. sedimentation rates from the scientific literature
are reported in Appendix A. Average sediment accumulation rates are used for regions when site-
specific data are not available.
Sediment accumulation rates estimated using pollen dating techniques (Brush, 1990) reveal a pattern
similar to that found by Officer et al. (1984). The highest sedimentation rates were in the upper
mainstem Bay (probably as a result of high sediment loads from the Susquehanna River), with the
lowest rates in the middle mainstem Bay. Sedimentation rates in the lower mainstem Bay were
midway between sedimentation rates estimated for the upper and middle mainstem Bay. Brush
(1984a) found that within the tidal tributaries the highest sediment accumulation rates occurred in upper
and middle tributary reaches, with the lowest accumulation rates observed in tributary lower reaches.
The two methods which have been used to measure sediment accumulation rates (Pb-210 and pollen)
in Chesapeake Bay reveal similar spatial patterns and result in estimates of sedimentation rates in
reasonable agreement. However, pollen dating produces sediment accumulation rates that are
consistently lower than rates determined by Pb-210, Part of the error may result from difficulties in
determining the exact dates corresponding to sedimentary horizons (Brush et al., 1982).
Management Applications of Sediment Chemical Contaminant Data
Knowledge of the concentrations and spatial distributions of sediment-associated chemical
contaminants is helpful in focusing management actions. However, assessing the environmental risks
of contaminated sediments is a very complicated matter, especially since some chemical contaminants
(notably trace metals) are naturally present in sediments. Extremely elevated concentrations of
chemical contaminants in sediment are usually worthy of increased attention, and concentrations at
natural background levels almost certainly pose an insignificant risk. Determining the environmental
significance of sediment contaminant concentrations between these extremes is more problematic.
No final federal sediment quality criteria have been published, and draft criteria exist for only five
substances (U.S. Environmental Protection Agency, 1991a. 1991b, 1991c. 1991d). However,
regulatory sediment quality criteria developed and adopted for use in the Puget Sound area of
Washington state (Washington State Department of Ecology, 1991), and various informal sediment
quality guidelines, e.g., Long and Morgan, 1990; MacDonald, 1993, are available to suggest what
sediment concentrations may result in adverse effects to aquatic biota. The U.S. Environmental
Protection Agency is currently developing a contaminated sediment management strategy which will
has wider applicability (U.S. Environmental Protection Agency, 1992a).
Upon finding elevated concentrations of chemical contaminants in sediments, field investigations may
be conducted to assess the toxicity of the sediments to resident organisms, as well as the potential for
bioaccumulation of the sediment contaminants. Managers can determine the historic and current
potential sources of these chemical contaminants and methods to reduce current sources. The costs
and benefits of various action (or of taking no action) can be evaluated to develop a sound
management strategy.
The presence of elevated concentrations of chemical contaminants in sediments does not necessarily
imply that the sediments pose significant environmental or human health risks. Goldberg (1992) draws
a helpful distinction between contamination and pollution of the environment. By Goldberg's definition,
pollution is "an alteration in the composition of the marine environment with a consequential loss of
resources such as seafoods, healthy ecosystems..." etc. To establish a pollution event, a cause and
effect relationship between the pollutant and the affected resource must be established.
Contamination, in contrast, is defined as an alteration in the composition of the environment without the
consequent losses of resources associated with pollution.
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Evaluation of data presented at the Chesapeake Bay Contaminated Sediment Critical issues Forum
suggested that sediment pollution by trace metals and anthropogenic organic compounds in
Chesapeake Bay is minimal and localized, although contamination is widespread (Chesapeake Bay
Program, 1993). This localization of pollution to restricted areas has important implications for
management strategies.
Approaches to the Development of Sediment Quality Criteria and Guidelines
Evaluation of the toxicrty of various concentrations of chemical contaminants in sediments is
complicated because different organisms, and even different life stages of the same organism, may
react differently to the same concentration of a chemical contaminant in the sediment. While
substantial information is available regarding the sediment concentrations of chemical contaminants
which cause harmful effects to resident organisms during acute {short-term) exposures, information
regarding the sediment concentrations of chemical contaminants which would be harmful in chronic
(long-term), exposures is limited to relatively few substances. Synergistic or antagonistic interactions
between individual chemical contaminants are even less well understood.
The binding of chemical contaminants to various sediment components, such as organic carbon or
sulfides, may render them unavailable to biota. As the amount of these sediment components may
differ among different sediments, two sediment samples with the same concentration of a given
chemical contaminant may have differing portions of the chemical in a biologically available form, and
thus exhibit different levels of toxicity.
Ideally, sediment quality criteria or guidelines will provide benchmarks useful in evaluating the potential
for toxic effects, and thus be useful in the assessment of sediment quality, identification of problem
areas for remedial action, evaluation of dredge spoil for disposal, and the design and evaluation of
monitoring programs (Chapman, 1989). Several methods have been developed to determine whether
contaminated sediment is likely to be toxic and whether or not some type of action, e.g., regulation or
remediation, may be required. Chapman (1989) divides the approaches into two categories: those that
provide sediment quality guidelines or criteria on a chemical-by-chemical basis only and those that can
also address mixtures of chemicals by directly measuring site-specific biological effects.
Chemicat-by-Chemical Sediment Criteria and Guidelines
These criteria or guidelines are typically numeric, relatively easy to apply and interpret, and can be
modeled effectively. They also have lower data requirements than the other category of criteria since
they do not require the collection of information on site-specific biological effects. However, these
approaches do not explicitly take into account the potential for interactions in mixtures of chemical
contaminants or the presence of unmeasured chemical contaminants, and cannot predict biological
availability or biological effects.
The background sediment chemistry approach compares sediment contaminant concentrations in the
area of interest to reference sediments that are assumed to be uncontaminated. It has minima! data
requirements, but assumes that biological effects are not influenced by grain size, organic carbon, or
other sediment characteristics. It does not specifically address biological effects or bioavailabtiity, but
can be combined with bioassay results to address those issues. Chapman (1989) considers this
approach inappropriate for criteria development because it does not make allowance for biological
effects and bioavailability.
The water quality criteria approach compares chemical contaminant concentrations in interstitial water
with EPA water quality criteria intended for application to water column measurements. Its major
advantage is that it uses a well-established toxicological data base. Its disadvantages are the lack of
water quality criteria for many chemical compounds and the lack of a standardized method for
measuring [the concentration of] chemical concentrations in the interstitial water of sediments
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(Chapman, 1989). This method also implicitly assumes that interstitial water is the route of exposure of
aquatic organisms to sediment contaminants.
In the sediment/water equilibrium partitioning approach, which is currently favored by EPA for
development of sediment criteria for nonpolar organic compounds, contaminant concentrations are
normalized for organic carbon content and equations are used to predict the resulting concentrations in
the interstitial water (Shea, 1988). These predicted concentrations are then compared to applicable
water quality criteria. This method assumes that organic contaminants are in equilibrium with sediment
organic carbon and interstitial water. Under these conditions, the activity of the contaminant will be
equal in both the water and sediment phase, and thus this method does not assume that interstitial
water is the only route of exposure. The only field measurements that are required are sediment
concentrations of chemical contaminants and organic carbon. A disadvantage of this approach is the
limited number of chemicals for which water quality criteria are available and, for some chemicals,
uncertainty in the estimates of the partition coefficients which are used to predict contaminant
concentrations in interstitial water (MacDonald, 1993).
Sediment Criteria and Guidelines Applicable to Mixtures of Chemical Contaminants
These approaches address the issue of adverse biological effects due to chemical mixtures and the
presence of unmeasured chemical contaminants. They can be used with any toxic substance and
require no assumptions about interactions between the chemical contaminants and organisms.
However, these criteria are more difficult to interpret and it can be difficult to demonstrate that a
particular contaminant has caused a biological effect. They also are much more data intensive, since
they require measurements of biological effects in addition to chemical measurements.
The bulk sediment bioassay approach generally follows that used to develop water quality criteria.
Chemical analyses and bioassays can be conducted on field-collected sediments from contaminated
and reference areas and quantitatively compared to determine the extent of contamination and what
potential effects it may have on benthic organisms. This approach has the advantage of providing a
direct, integrated measurement of toxicity resulting from one or several chemicals present at a
particular site, and uses relatively simple and inexpensive procedures. This approach is routinely used
for assessing the suitability of ocean or freshwater disposal of dredge spoil. A disadvantage of this
approach is that bioassays of field sediment do not provide chemical-specific results. Thus, attempts to
determine what sediment concentrations of a specific chemical will likely result in biological effects
could be confounded by the presence of unmeasured or covarying chemical contaminants. Changes
in physical and/or chemical characteristics in the sediments may also reduce the relevance of the
laboratory results to field conditions (Chapman, 1989).
in the spiked sediment toxicity test method a dose-response relationship for a particular toxic substance
can be determined by spiking sediments with that substance. The major advantage of this approach is
that it can be used to develop chemical-specific criteria (Chapman, 1989). The major disadvantage of
this test is that it assumes that the experimental conditions created in the laboratory adequately
simulate conditions in the field, an assumption that has not been confirmed for an array of chemicals
(Adams et a/., 1992). tn addition, criteria developed using one sediment type may not be applicable to
another sediment with differing chemical or physical properties.
The screening level concentration approach estimates the highest level of a sediment associated
contaminant that can be tolerated by 95 percent of the species of benthic organisms living in the
sediment in an area. It requires matching data on sediment chemical concentrations and benthic
invertebrate distributions. Disadvantages of this method include the sensitivity of the derived criteria to
the range and distribution of contaminant concentrations and the suite of species used in developing
the criteria (Chapman, 1989).
The sediment quality triad approach uses three measurements: (1) sediment chemistry to determine
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the degree of contamination, (2) sediment bioassays to determine toxictty, and (3) changes in benthic
community structure or presence of fish pathology to determine the biological effects of sediment
contamination and toxicrty (Chapman, 1989). This approach may be the most comprehensive and
realistic, but it is difficult to apply because of the extensive data requirements (Alden, 1992).
The apparent effects threshold (AET) utilizes matching field data on sediment chemical concentrations
and at least one indicator of bioeffects from a number of sites (Chapman, 1989). The AET for a given
chemical is the sediment concentration of the contaminant above which statistically significant biological
effects are always found in the data set This approach was used by the state of Washington in
developing te sediment management standards for use in the Puget Sound area (MacDonald, 1993).
The criteria fora particular chemical developed from data on sites within one area may be invalid if
chemical contaminant concentrations among these sites covary strongly. Thus, AET criteria should be
based on lexicological information collected from a set of sites within the area in which the criteria are
to applied (AJden and Rule, 1992). There is a risk of under-protection of biological resources in
adopting AETs as sediment guidelines, since by definition they are based on the concentration at which
toxic effects will always be expected to occur, although effects may sometimes be observed at lower
concentrations (Chapman, 1989).
Numeric Sediment Criteria and Guidelines
Numeric sediment quality standards and guidelines have been developed for many chemical
contaminants, but they remain controversial (Lee and Jones-Lee. 1993). Despite this controversy, the
need for an evaluative tool for sediment quality has led various governmental agencies in North
America to develop and use such criteria (Table 1.2).
Long and Morgan (1990) collected the results of eighty-five studies using equilibrium partitioning
calculations, spiked sediment bioassays, and various types of bioeffects/sediment contaminant
concentration co-occurrence analyses such as the screening level approach and apparent effects
threshold. The only observations included in the analysis for a given chemical contaminant were those
for which adverse biological effects were found and believed to be related to the presence of the
chemical contaminant in the sediment. The data are all from marine and estuarine studies.
For each chemical contaminant, these observations were ordered by the bulk sediment concentration
of the chemical contaminant. The lower 10th percentile of ordered observations in which biological
effects were found was used to define the Effects Range-Low (ER-L) concentration for the chemical
contaminant. This ER-L is considered to be an estimate of the low end of the sediment contaminant
concentration range at which adverse effects may begin or are predicted to occur among sensitive life
stages or species. The Effects Range-Median (ER-M) concentration was defined as the 50th percentile
of ordered concentrations for which toxicrty was observed. The ER-M is considered an estimate of the
sediment concentration above which toxic effects would be "frequently or always observed or predicted
among most species" (Long and Morgan, 1990). These ER-L and ER-M values were intended to serve
only as informal sediment quality guidelines, and were originally developed to aid the National
Oceanographic and Atmospheric Administration (NOAA) in identifying sites at which chemical
contaminants in the sediment had the greatest potential for causing adverse biological effects (Long
and Morgan, 1990).
The data set used to generate the ER-L and ER-M values has subsequently been expanded, and the
estimates of values comparable to the ER-L and ER-M values have been revised (MacDonald, 1993).
In this effort, initiated by the state of Florida, the data base used by Long and Morgan (1990) was
updated, with a special emphasis on adding more studies from the southeastern U.S., which was poorly
represented in the original data set In addition, the methods used to develop the lower limit of toxic
concentrations (termed the No Observable Effect Level or NOEL) and the concentration at which toxic
effects occur frequently (termed the Probable Effects Level or PEL) were revised. Unlike the method
used to determine ER-L and ER-M values, the methodology for determining the NOEL and PEL utilized
both observations in which toxicrty was found and observations in which toxicrty was not found.
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The NOEL concentration was developed by applying a safety factor of two to the upper range of
concentrations at which the majority (approximately 75 percent) of observations found no adverse
biological effects of the chemical contaminant. The safety factor of two was applied because the data
base was biased towards acute (short-term exposure) toxicity data. The PEL concentration was
similarly defined as the concentration above which most observations (approximately 75 percent) found
adverse biological effects. In MacDonald's (1993) terminology, sediment contaminant concentrations
below the NOEL concentration are expected to only rarely be associated with toxic effects to aquatic
biota. At sediment contaminant concentrations above the NOEL value but below the PEL value,
MacDonald (1993) considered toxic effects to aquatic biota "possible". At sediment contaminant
concentrations above the PEL, toxic effects to aquatic biota are considered "probable" (Figure 1.1).
These NOEL and PEL guidelines are intended to apply to marine and estuarine waters only
(MacDonald, 1993).
For both the Long and Morgan (1990) ER-L and ER-M values and the NOEL and PEL values of
MacDonald (1993), the level of confidence the authors place in the validity of the sediment quality
guidelines varies among different chemical contaminants, depending on the amount and consistency of
toxicity data available for each chemical contaminant. For several contaminants for which ER-L and
ER-M guidelines are available, MacDonald (1993) did not develop NOEL and PEL guidelines because
he believed insufficient data were available to adequately determine the concentration ranges likely to
be associated with adverse biological effects. Neither the ER-L and ER-M guidelines nor the NOEL
and PEL guidelines address the potential for bioaccumulation of persistent chemical contaminants and
resultant potential adverse effects on higher levels of the food chain.
The state of Washington has developed regulatory sediment quality criteria based on the apparent
effects threshold approach applied to matching biological effects and sediment chemistry data from the
Puget Sound area (MacDonald, 1993). The criteria were designed to meet a goal of no adverse acute
or chronic effects on biological resources and no significant health risk to humans. The numeric criteria
are used initially to identify sediments which meet or fail to meet the goal of no adverse effects.
Biological testing may be used to confirm or reverse the initial designation based on chemical criteria
(Washington State Department of Ecology, 1991).
The EPA has published draft criteria for five nonpolar organic compounds based on the equilibrium
partitioning approach (Environmental Protection Agency, 1991 a, 1991 b, 1991 c, 1991 d, 1994). Several
other jurisdictions have also published sediment guidelines or criteria. The province of Ontario has
developed sediment quality guidelines for ten metals, total PCBs, and nine organochlorine pesticides
utilizing a combination of the background chemistry approach (metals only), the equilibrium partitioning
approach (non-polar organic compounds only), and a modification of the traditional screening level
concentration approach (Persaud et a/., 1990; Jaagumagi 1990a. 1990b).
Application cf Sediment Quality Guidelines to Chesapeake Bay Sediment Contaminant Data
There are no generally accepted methods for the difficult task of assessing the biological significance
of the concentrations of chemical contaminants in sediments. This report compares sediment
contaminant concentrations from various monitoring programs conducted in the Chesapeake Bay to
the No Observable Effect Level (NOEL) and the Probable Effects Level (PEL) concentrations
developed by MacDonald (1993). The MacDonald (1993) NOEL and PEL values provide sediment
quality guidelines for evaluating the potential for biological impacts of the measured concentrations of
most of the chemical contaminants monitored in the Chesapeake Bay. In addition, these guidelines are
based on a large data base consisting of data from throughout the U.S., rather than one focusing on a
limited geographic area.
Throughout this report, toxic effects are considered likely only at stations where average sediment
chemical contaminant concentrations are in excess of MacDonald's (1993) PEL values. The NOEL
1-9
-------
values (MacDonald, 1993) are listed, but interpretation of the biological significance of sediment
chemical contaminant concentrations between the NOEL and PEL values is left to the reader. Where
NOEL and PEL values (MacDonald, 1993) are not available, sediment contaminant concentrations may
be compared to other sediment quality guidelines or standards. Table 1.2 lists the values provided in
several sets of sediment quality guidelines or criteria to assist the reader in making more detailed
comparisons between data on sediment chemical contaminants and various sediment quality
guidelines and criteria.
MacDonald (1993) notes that toxicrty from sediment chemical contaminant concentrations between the
NOEL and PEL values may be dependent on site-specific conditions, and that it is difficult to reliably
predict the occurrence of toxic effects associated with sediment contaminant concentrations in this
range based solely on data on sediment chemistry. Because of the greater level of uncertainty
associated with these intermediate concentrations of sediment-associated chemical contaminants, the
authors believe that interpreting their potential for exerting toxic effects requires more information than
can be provided in this survey.
In comparing the data on sediment contaminant concentrations with NOEL and PEL concentrations,
the intended applications of these sediment quality guidelines should be kept in mind. The NOEL and
PEL concentrations were developed to use in determining the potential for sediment contaminants to
induce toxic effects; the values cannot be used by themselves to identify sediments that are
exerting toxic effects on local biota. We recommend that these guidelines be used in conjunction
with other tools and protocols to provide comprehensive evaluation of sediment quality (MacDonald,
1993).
The NOEL and PEL concentrations are derived from a wide variety of studies using diverse measures
of adverse biological impacts and involving contaminated sediments from many different geographic
areas contaminated from a wide variety of sources. Because of differences in sediment characteristics,
the sensitivities of resident species, and the mix of contaminants which may be present at a given site,
the guidelines cannot be expected to always accurately predict the range of concentrations at which a
given chemical contaminant may exert toxic effects in the sediments of Chesapeake Bay and its tidal
tributaries.
In some cases, the NOEL and PEL concentrations are strongly influenced by the results of chemical-
biological co-occurrence analyses such as the apparent effects threshold and screening level
concentration approaches. As discussed previously, a weakness of this type of study is that covariance
of measured or unmeasured sediment associated chemical contaminants may affect the validity of their
findings.
Finally, the sediment quality guidelines are not expressed in terms of factors that are thought to control
the bidavailability of sediment associated chemical contaminants, such as acid volatile sulfide for
divalent metals and total organic carbon for non-ionic organic compounds and some trace metals.
Since the toxicity of a sediment with a given concentration of a chemical contaminant will vary
fstrongly]s/gn/ffcanfly depending on a variety of chemical and physical characteristics of the sediment,
the presence of other chemical contaminants, and the sensitivity of the suite of organisms which are
exposed to the sediment, it is difficult to determine how well the NOEL and PEL concentrations may
apply at a given site.
In Table 12 the sediment quality criteria published by various jurisdictions in North America is
presented. The Effects Range - Low(ER-L) and Effects Range - Median(ER-M) values are from Long
and Morgan. 1990. The sediment management standards for the state of Washington are from the
Washington Department o Ecology, 1991. Criteria for protection of benthic organisms in freshwater
(EPA-F) and saltwater (EPA-S) habitats is from that agency's publication, 1993. No-effect level(O-NE),
Low-effects level(O-LE), and Severe-effects level(O-SE) come from Province of Ontario sediment
criteria(Persaud era/, 1990).
MO
-------
The superscripts, L, M, and H denote low, medium, and high confidence in ER-L.ER-M, NOEL, and
PEL values as assigned by Long and Morgan (1990) for ER-L and ER-M, and by MacDonald (1993) for
NOEL, and PEL
1-11
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Table 1.2a Revised ER-Ls and ER-Ms. In th final editing stages of
this report an update to these guidelines was published.
CHEMICAL CONTAMINANT
ER-L
ER-M
Trace Metals
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
8.2
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PAHs
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Chrysene
Dibenzo(a ,h)-anthra cene
Fluoranthene
Naphthalene
Phenanthrene
Pyrene
Total PAHs
16
85.3
261
430
384
63.4
600
600
240
665
4,022
500
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1.600
1,600
2,800
260
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Pesticides and PCBs
p,p'-DDE
Total DDT
Total PCBs
2.2
1.58
22.7
27
2.2
1.58
Long, E.R., D.D. MacDonald, Sherri L. Smith, and Fred D. Calder. 1995. Incidence of adverse biological effects
within ranges of chemical concentrations in marine and estuarine sediments. Environmental
Management 19(1): 81-97.
1-14
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Methods
Data from several monitoring programs have been included or compared in this report. As one would
expect, different methods have often been used for the different programs, thus comparisons between
programs must be made with care. Quality assurance data are included in the appendix.
Design of Sediment Contaminant Monitoring Programs
Sediment contaminant monitoring in the Chesapeake Bay and its tidal tributaries has been conducted
by several jurisdictions (Maryland, Virginia, National Oceanic and Atmospheric Administrations (NOAA),
Environmental Protection Agency (EPA)), each addressing a separate Bay region or concern. Thus,
the frequency and timing of sample collection, the collection methods and the analytical protocols often
differ among the monitoring programs. Details of the monitoring program design (i.e.. location of
stations, frequency of sample collection) in each region of the Bay are presented at the beginning of the
chapter presenting data for that region. The following section describes the methods used for sample
collection and sample analysis in the monitoring programs which provided the data discussed in the
following chapters.
Data from sediment contaminant monitoring programs conducted by Maryland, Virginia, the EPA
Chesapeake Bay Program, and the Interstate Commission on the Potomac River Basin (ICPRB) are
the primary focus of this report and the following discussion of methods focuses on these programs.
The sediment contaminant monitoring programs conducted by the Environmental Protection Agency's
Environmental Monitoring and Assessment Program (EMAP) and the National Oceanic and
Atmospheric Administrations's (NOAA) National Status and Trends Program used methods similar to
those employed by the ICPRB and are described below. See Environmental Protection Agency (1993)
for further information on the methods used in the EMAP sediment contaminant monitoring program.
MacLeod etal. (1985) and National Oceanic and Atmospheric Administration, (1991) provide complete
information on the methods employed in the NOAA National Status and Trends monitoring program.
Sample Collection
Sediment samples collected from the Maryland tidal tributaries by the Maryland Department of the
Environment (MDE) and from the Bay mainstem as part of the joint EPA Chesapeake Bay Program-
MDE- Virginia Department of Environmental Quality (VADEQ) mainstem monitoring program were
surface samples (top 2 cm) of sediments collected using acid and methanol-rinsed stainless steel Van
Veen (Maryland) or Smith-Maclntyre (Virginia) dredges. The upper 2 cm were removed from three
grabs at each station location and mixed in a solvent-rinsed stainless steel bucket to produce a
composite sample. Each grab sample was taken while the boat was anchored at the same location.
This composite sample was homogenized and then dispensed into three pre-cleaned jars with teflon
lids. In the Virginia sampling program, all jars were of glass and one sample was used for the analysis
of organic contaminants; the second jar for the analysis of metals, sediment grain size composition,
and acid- volatile sulfide (AVS) and total organic carbon (TOC); and the third jar for duplication in case
of sample loss (Unger etal., 1991). In the Maryland sampling program, two glass jars were used, the
first for metals analysis and the second for grain size composition, AVS, and TOC measurements. A
third Teflon jar was used for analysis of organic contaminants. In both sampling programs, samples
were stored on ice in the field and immediately frozen when returned to the laboratory.
Sediment samples from the upper Potomac and Anacostia rivers were collected with an acetone-
rinsed, stainless steel petite-Ponar grab sampler. The top 2-3 cm of sediment not in contact with the
sides of the sampler were removed and placed into a pre-cleaned pyrex bowl. This process was
repeated until sufficient sediment had been collected. The grab samples were mixed until
11-1
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homogeneous and then aliquots were placed into separate containers. Samples for organic analysis
were placed in pre-baked glass mason jars capped with pre-baked aluminum foil-lined caps and stored
on ice while in the field. Samples for grain size and trace metals analysis were placed into pre-cieaned
glass jars and sealed with Teflon-lined caps and stored on ice in the field. Sediment samples for AVS
were placed in a 50 ml plastic centrifuge tube which was then quick frozen in the field using dry ice.
Once on shore, sediment samples for organic and metal analyses were placed in a freezer at -20°C,
while samples for grain size analysis were kept at 4'C (Velinsky ef a/., 1992).
Metals
All metal extractions from sediments collected from the Maryland tidal tributaries by MDE and the Bay
mainstem as part of the joint Chesapeake Bay Program-Maryland-Virginia mainstem monitoring
program were done by a "total recoverable" method using hydrochloric and nitric acids to extract
metals from the sediment. Metal analyses of sediment samples from the James River collected by the
VADEQ were also analyzed by the "total recoverable" method. This method generally yields the
majority of metals from the sediment but does not recover metals tightly bound within the mineral lattice
(Horowitz, 1985).
Trace metal analyses of mainstem sediments were conducted by the EPA Region 111 laboratory in
Annapolis, Maryland in 1984 and 1985, and by the Virginia Institute of Marine Science (VIMS)
laboratory in 1991. Maryland tributary sediments in all years were analyzed for trace metal content by
the Maryland DHMH laboratory. Quality assurance/quality control (CWQC)data for the VIMS and
DHMHs lab are shown in Appendices B and C respectively. Analyses of the James River sediment
samples collected by VADEQ were conducted by the Division of Consolidated Laboratories Services in
Richmond, Virginia.
The NOAA National Status and Trends Program, the EPA's Environmental Monitoring and Assessment
Program (EMAP). and the study by the Interstate Commission on the Potomac River Basin (ICPRB) of
the Anacostia and upper Potomac rivers used the "total" method of trace metal analysis of sediments.
In this method, hydrofluoric acid is used to completely dissolve the silica matrix in sediment. This
method of metal extraction is more rigorous than the "total recoverable" method described above.
Analyses of sediment metals in samples collected by MDE and VAOEQ used atomic absorption
spectrophotometry using atomic absorption spectrophotometry with a graphite furnace for arsenic, cold
vapor for mercury and inductively coupled plasma (ICP) for all other trace metals. The ICPRB utilized
atomic absorption spectrophotometry with cold vapor for mercury, and graphite furnace for all other
trace metals (Velinsky et a/., 1992).
Acid-Volatile Sulftdes
Acid-volatile sulfide (AVS) concentrations were measured in the 1991 mainstem sediment samples and
in samples from the upper Potomac and Anacostia rivers. The analyses of AVS in mainstem
sediments was performed by the Virginia Institute of Marine Science (QA/QC data are in Appendix BH)
and the Maryland Department of Health and Mental Hygiene according to trie EPA draft Method 376.3.
In this method, sulfide in the sample is converted to hydrogen sulfide by aodifcaion with hydrochloric
acid at room temperature. The hydrogen sulfide is purged from the sample and trapped in a solution of
silver nitrate. The silver sulfide precipitate is filtered and weighed. Analysis of AVS in sediment
samples collected in the upper Potomac and Anacostia rivers by the ICPRB was performed using the
method of Cutter and Oatts (1987).
Total Organic Carbon
Sediment total organic carbon (TOC) for the Maryland tributary samples collected by MDE were
analyzed by the Chesapeake Biological Laboratory using a Leeman CHN analyzer and the
II-2
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Environmental Protection Agency's Method 440 {Environmental Protection Agency, 1992). Detection
limit development is shown in Appendix D. The mainstem Bay and Virginia tributary samples collected
in 1991 were analyzed for TOC by VIMS using a Carlo Erban Analyzer, following acidification of those
samples for which effervescence was noted following treatment of a subsample with 10% hydrochloric
acid (Unger era/., 1992). Total organic carbon concentrations in sediment samples from the Anacostia
River and upper Potomac River collected by the ICPRB were determined by infra-red absorption after
combustion in an O2 stream using a LECO WR-12 Total Carbon system. The sediments were acidified
prior to analysis (Velinsky et al., 1992).
The acidification step in sediment total organic carbon measurements has the effect of removing
carbonates. This step was not used in Maryland tributary sediments, but since the majority of carbon in
Chesapeake Bay sediments is organic (Hennessee et al.. 1986), the differences in estimates of total
organic carbon obtained by the two methods are probably minor.
Grain size
Grain size analysis methods for samples from the Maryland and Virginia tributaries and the mainstem
Bay collected by the Maryland and Virginia monitoring programs followed Plumb (1981) and are
described in Appendix E. The silt fraction was distinguished from the clay fraction only in Virginia. For
consistency, silt and clay (the fraction less than 63 urn) were combined for all presentations of grain
size data in this report. Grain size analyses in the ICPRB study of the Anacostia and upper Potomac
Rivers followed the method of Folk (1980).
Ranges for general categories of grain size distribution that have proven useful in differentiating benthic
community habitats are listed in Table 1.1. These categories are used throughout the report to
describe the grain size distribution typical of sediments from various areas of Chesapeake Bay and its
tidal tributaries.
Organic Compounds
Organic contaminants in all mainstem Bay and Virginia tributary sediment samples were analyzed by
the Virginia Institute of Marine Science (VIMS). Maryland tributary sediment samples from 1986 and
1987 were analyzed for organic contaminants by the Maryland Department of Health and Mental
Hygiene following VIMS' methods (VIMS Division of Chemistry and Toxicology, 1991). Maryland
tributary sediment samples from 1991 were analyzed for organic contaminants by the State Chemist
Laboratory in the Maryland Department of Agriculture (MDA).
The VIMS' methodology for analysis of organic compounds included a 48 hour soxhfet extraction with
dichloromethane, followed by the use of gel permeation chromatography and silica gel
chromatography to remove large biogenic molecules and isolate an aromatic fraction containing most
of the anthropogenic compounds of interest. Polycyclic aromatic hydrocarbons and related
compounds were analyzed by gas chromatography with (lame ionization. Chlorinated organic
compounds were analyzed by gas chromatography with electrolytic conductivity detection, a detector
highly selective for chlorinated compounds and less likely to be affected by interfering compounds than
the typically used electron capture detector (Unger et al., 1991). QA/QC data are presented in
Appendix B.
The method followed by the MDA in the analysis of organic compounds in Maryland tributary sediments
was somewhat different than the VIMS' method. Samples were extracted by mixing with methylene
chloride in a blender, removal of the methylene chloride fraction, and then re-mixing of the aqueous
and solid portions, with the mixing procedure repeated a total of three times. A sulfur cleanup (EPA
method 366A) was applied to the extract prior to subsequent analysis. Pesticides and polychlorinated
biphenyls (PCBs) were analyzed with a gas chromatograph with an electron capture detector while
II-3
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polycyclic aromatic compounds (PAHs) were analyzed by reverse phase chromatography with
fluorescence detection. QA /QC data is presented in Appendix F.
Organic contaminants in sediment samples from the Anacostia and Upper Potomac rivers were
analyzed following a method adapted from MacLeod et at. (1985). Samples were soxhlet extracted
and the extracts fractionated by alumina:si!ica open column chromatography. Aliphatic hydrocarbons
were analyzed by gas chromatography using a flame ionization detector. Aromatic hydrocarbons were
separated and quantified by gas chromatography-mass spectrometry. Pesticides and PCBs were
quantified by gas chromatography and an electron capture detector (Velinsky et a/., 1992).
The VIMS laboratory uses a "fingerprint method" of analysis of organic contaminants in sediment
samples which is designed to provide a reasonable level of confidence in identifying and quantifying
those anthropogenic PAHs and chlorinated organic compounds which are of greatest interest and are
most likely to be found in environmental samples. The "fingerprint method" analytical technique utilized
by VIMS has evolved during over twenty years of experience analyzing environmental samples for
hazardous organic chemicals at VIMS. Because of this use of the "fingerprint method", a list of organic
chemical analytes is not available for sediment samples from the mainstem and Virginia tributaries.
Because VIMS' methods were followed in the analysis of Maryland tributary samples from 1986 and
1987, a list of organic chemical analytes is also not available for these samples. A list of organic
chemical analytes for the analysis of Maryland tributary samples in 1991 by the Maryland State Chemist
Laboratory is provided in Appendix F.
The method detection limits for organic contaminants typically vary among sediment samples due to
differences in the volume of solvent used in extracting the contaminants of interest and differences in
the concentrations of potentially interfering chemicals in the sediment samples. The nominal detection
limit for organic contaminants at the VIMS' laboratory was 0.01 ppb (linger etal., 1991).
Quality Assurance and Quality Control
Quality assurance and quality control procedures in each laboratory consisted of internal standards,
laboratory duplicates and spike analyses and/or analyses of standard reference materials. Quality
assurance/quality control (QA/QC) data for each of the three laboratories performing analyses for the
Virginia and Maryland monitoring programs are provided in Appendices as listed above. Quality
assurance/quality control information for the 1CPRB study can be found in Velinsky era/., 1992.
Normalization of Sediment Concentration Data
The data contained in this report are reported both as "measured" concentrations (bulk concentration
by dry weight), and as "normalized" concentrations, in which the bulk concentration is normalized with
reference to grain size composition for trace metals and to sediment organic carbon for organic'
contaminants.
Trace Metals
The percentage of fine material in sediments, in particular the proportion of sediment passing through a
63 um sieve, usually correlates well with concentrations of trace metals in the sediment (Horowitz,
1985). This is believed to occur because fine particles have a greater surface area per unit mass than
do large particles and consequently adsorb more metals than the same mass of larger particles
(Horowitz, 1985). In addition, larger particles adsorb only small quantities of metals and thus act to
dilute the metal concentration of sediments (Horowitz, 1985). Thus, data tables for sediment trace
metal concentrations include data normalized by dividing the bulk metal concentration of the sediment
by the fraction of the sediment consisting of particles less than 63 um. (Horowitz, 1985). Grain size
normalization is often used to reduce natural variation in sediment trace metal concentrations that are
II-4
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The normalized sediment concentrations of organic compounds presented in this report were
determined by dividing the sediment concentration by the fraction of organic carbon in the sediment.
Nonpolar organic contaminants have an affinity for organic carbon, and thus organic contaminants in
sediments tend to be located in organic coatings which surround sediment particles (Long and Morgan,
1990). Thus, a sediment with a high concentration of organic carbon will generally have a greater
concentration of a particular organic contaminant than will a sediment with a low organic carbon
concentration receiving a similar loading of the contaminant (Long and Morgan, 1990).
Sediments may have different concentrations of organic carbon due to both natural factors or
differences in anthropogenic loadings of organic carbon or nutrients which stimulate primary production
(Long and Morgan, 1990). In some sediment contaminant monitoring programs, total organic carbon is
considered a sediment contaminant (National Oceanographic and Atmospheric Administration, 1991).
Thus, in some cases, normalizing sediment concentrations of organic contaminants eliminates variation
in contaminant concentrations due to differences in sediment organic carbon content. However, since
elevated sediment total organic concentrations may be the result of anthropogenic inputs, carbon
normalization does not strictly control for only natural variations in organic contaminant concentrations.
It has frequently been observed that the correlation between the sediment concentration of non-ionic
organic compounds and the toxicity of sediments is relatively low (DiToro et a/., 1991). The relationship
between observed toxic effects and sediment organic contaminant concentrations in different
sediments is much improved by normalizing sediment concentrations based on organic carbon content
(DiToro et al. 1991). These results are due to the fact that for sediments with greater than 0.2%
organic carbon by weight, organic carbon is the predominant phase for chemical sorption of non-ionic
organic compounds (Di Toro et al.. 1991).
II-S
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Mainstem Data Collection and Analysis
Data on concentrations of chemical contaminants in mainstem sediments have been obtained from
monitoring programs of the Virginia Department of Environmental Quality, the Maryland Department of
the Environment, and the U.S. EPA Chesapeake Bay Program Office. Data on mainstem sediment
trace metal concentrations are available for 1984,1985, (Maryland stations only) and 1991. Data on
mainstem sediment concentrations of polycyclic aromatic hydrocarbons, PAHs, are available (from] for
the years 1934,1985,1986, and 1991. The only available data on chlorinated organic compounds are
from 1991.
Data on sediment concentrations of potentially toxic chemicals in the Chesapeake Bay mainstem are
presented for aggregations of stations representing various segments of the Bay mainstem (Table 3.1).
The aggregations of stations, for the mainstem segments {Figure 3.1 and Figure 3.2) generally follow
the Chesapeake Bay segmentation scheme described in Heasly, eta!. (1989). Data from four river
mouth stations (at the Potomac, Rappahannock, York, and James Rivers), and from the station in
Mobjack Bay (north of the York River mouth) are presented individually to indicate sediment-associated
contaminant concentrations at the interface between the major t'dal tributaries and the Bay mainstem.
For trace metals, data are available for four linear arrays of stations which transect the Bay across the
deep trough (segments three and four). The data for these stations are included in the summary
statistics for these segments, but are also presented as longitudinal aggregates to compare middle
mainstem Bay sediments from west to east. This longitudinal aggregation is supported by the
observations of Helz and Valette-Silver (1992) which suggest that western flank sediments may be
derived from the Susquehanna River, while eastern flank sediments may have been transported from
the south.
All available data were combined for the analyses. Medians, quartiles, and the minimum and
maximum values of bulk concentrations of each chemical contaminant are presented in tables and
displayed graphically. This presentation provides measures of central tendency (median and mean),
dispersion (quartiles), and range. Statistics are also provided for trace metal concentrations normalized
by the fraction of silt and clay particles in the sediment and for PAH concentrations normalized by the
fraction of total organic carbon in the sediment. However, grain size distribution and/or total organic
carbon data were not available for all samples. Note that the scale may differ for graphs of measured
(bulk) concentrations and normalized concentrations of the same contaminant.
Analysts of variance (ANOVA) was used to test for statistically significant differences in mean sediment
contaminant concentrations among the different years during which sediment contaminant data were
collected, if the ANOVA was significant, a Duncan multiple-range test was used to determine which
years had significantly different mean sediment contaminant concentrations.
111-1
-------
Table 3.1 Segment location, grain size, and sedimentation rates for mainstem stations. The asterisk
(*) indicates stations sampled for organic compounds and metals; other stations sampled for metals
only. (M=mud; MS=muddy sand; SM-sandy mud. See Table 1.1 for details.)
Segment No. or
Region
1
2
3
4
5
7
8
West
Center
East
Potomac
Rappahanock
Mobjack Bay
York
James
Stations
MCB1.1*
MCB2.1.MCB2.2'
MCB3.1,MCB3.2',MCB3.3W.MCB3.3C>1MC83.3E
MCB4.1W,MCB4.1C',MCB4.1E,MCB4.2W,MCB4.2C>
MCB4.2E,MCB4.3W,MCB4.3C',MCB4.3E.MCB4.4
MCB5.f.MCB5.2,MCB5.3.CB5.2(1984),CB5.4(1991)
CB7.5E (1984), CB7.1S* (1984, 91), CB7.3E* (1991)
CB8.1E'
MCB3.3W, MCB4.1W. MCB4.2W. MCB4.3W
MCB3.3C. MCB4.1C. MCB4.2C, MCB4.3C'
MCB3.3E, MCB4.1E, MCB4.2E. MCB4.3E
MISS-
IES .6'
WE4.1'
WE4.2*
LE5.5*
Grain
Size
MS
SM
M
SM
SM
SM
MS
SM
M
SM
M
M
M
MS
Approx. Sed.
Rate
cm/yr
0.6-0.38
0.12-1.0
0.09-0.54
0.007-0.07
0.13-0.28
0.12-0.26
0.08-0.12
0.08
0.14
Sources: Goldberg, era/. 1973; Schube! and Hirschberg, 1977; Brush, 1989; Brush 1990.
Hl-2
-------
Figure 3.1 Chesapeake Bay mainstem segments.
III-3
-------
Figure 3.2 Sediment Contaminant Monitoring Stations
in Chesapeake Bay Mainstem
• Trace metals only
"•] Trace metals and organic contaminants
MCB1.1
MCB2.1
MCB2.2
MCB3.1
MCB3.2
MCB3.3 W.C.E
MCB4.1 W.C.E
MCB4.2 W.C.E
MCB4.3 W.C.E
MCB4.4
MCB5.1
MCB5.2
MCB5.3
CB5.4
LE3.6
CB7.1S
WE4.1
WE4.2
CB7.3E
LE5.5
CB8.1
-------
Data from the recent sampling program were also compared with data from a 1970s study of the sediment
concentrations of trace metals in Bay sediments {Helz, et a/., 1983). This study used a "total recoverable" type of
metals analysis, as was the case in the recent sampling program. In the study of Helz, et a/. (1983) metals were
extracted from the sediment in a 9:1 mixture of hot concentrated nitric and hydrochloric acids. The extracts were
analyzed by atomic absorption flame spectrophotometry. with background correction used for cadmium (Helz, et
al. .1983).
Differences in sediment trace metal concentrations between sampling events at a given location could be
attributable partly to differences in the proportion of silt and clay between the two samples; therefore, both
comparisons between bulk ("measured") trace metal concentrations from the two studies and comparisons of
grain-size normalized trace metal concentrations from 1991 and analyses of the silt-clay fraction made in the late
1970s are presented. In interpreting these data, it is important to keep in mind that the upper approximately 20
cm of sediment can be well-mixed and can represent deposition from the fast 2.5 to more than 40 years
(Goldberg, ef a/., 1978). Thus, the 1991 data may not always be derived from the most recently deposited
sediments.
Loadings of Trace Meals and Organic Contaminants to the Chesapeake Bay
Several studies have estimated the loadings of trace metals and organic contaminants to Chesapeake Bay from
various sources, including fall line loadings from the major tributaries, point sources and urban stormwater runoff
below the fall line, and direct atmospheric deposition to Bay waters (Table 3.2).
Estimated fall line loadings of trace metals are much higher than loadings from below fall line point sources,
urban stormwater, and direct atmospheric deposition to tidal waters (Table 3.2). However, fall line loads are
reduced during transit to Bay tidal waters, whereas below fall line loads are delivered directly to the mainstem
Bay (Chesapeake Bay Program, 1994a). Groundwater loadings of metais and organic contaminants to the Bay
are unknown, but are probably of most significance at local scales close to sources of contamination
(Chesapeake Bay Program, 1994a).
In contrast, estimated fall line loadings of most organic contaminants were similar to below fall line urban
stormwater toads and below fall line point source loads (Table 3.2). The estimates for direct atmospheric
deposition of trace metals and organic contaminants to Chesapeake Bay waters were based on measurements
made at stations which probably were not influenced by the air plume from the highly industrialized and
urbanized area around Baltimore, Maryland (Baker, etal.. 1992). Thus, the figures for atmospheric loadings in
Table 3.2 probably underestimate the actual loadings to the Bay from atmospheric deposition. Atmospheric
deposition is a significant source of many pollutants to major water bodies (Table 3.2 and Table 3.3). Note,
however, that the relative importance of atmospheric loadings varies among different water bodies (Table 3.2 and
Table 3.3).
The magnitude of below fall line loadings from point sources and urban stormwater varies considerably among
different portions of the Bay watershed (Table 3.4). The highest loadings are found in the West Chesapeake and
Potomac regions of the Bay watershed, with intermediate loadings in the James and Patuxent regions and the
lowest loadings from the Rappahannock, York, and Eastern Shore regions.
III-5
-------
Table 3.2 Estimated mean annual loadings of selected trace metals and polycyclic aromatic hydrocarbon
(PAHs) to Chesapeake Bay from various sources. Loads are in pounds per year.
Chemical
Fall line Below fall line loadings Atmospheric
loadings1 Urban Stormwater2 Point Sources2 Deposition3
Trace Metals
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Zinc
PAHs
Benzo[a]anthracene
Benzojajpyrene
Chrysene
Fluoranthene
Naphthalene
PCBs
Alachtor
Aldrin
Atrazine
Chlordane
Dieldrin
Metalochlor
54.000
51,000
270,000
450,000
540,000
7,600
1,900.000
320
370
NE
650
970
410
58
6000
320
65
3,100
25,000
6,200
36.000
100,000
22.000
1.100
570.000
210
190
520
780
990
NE
NE
NE
NE
NE
NE
1.400
1.300
44,000
83,000
13.000
510
360.000
NE
100
20
50
1.400
NE
NE
NE
NE
NE
NE
3,800
2,700
7.500
24,000
32,000
NE
91,000
300
280
710
1.400
NE
5.600
NE
1.700
170
NE
2.700
NE = no estimate
Sources:
' Chesapeake Bay Program, 1994a. Loadings are based on the sum of estimated loadings from the S^
These two tributaries together contribute approximately 64% of the total river flow Mo tr* Bay
River and James River.
* Chesapeake Bay Program, 1994b. Loadings are based on the sum of estimated loadings from me s<.-io.«*uvj Rrver. Potomac River, and
James River. These three tributaries together contribute approximately 84% ol the total over flow u-.:: n- EJ ,
* Chesapeake Bay Program. 1994b. Estimates are for direct loadings to tidal surface waters.
III-6
-------
Table 3.3 Estimates of atmospheric deposition as percent of the total load for select trace metals and organic
contaminants in various water bodies.
Pollutant
Jamaica Bay1 Lake Erie' Mediter.Sea* North Sea* Chesapeake Bay3
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
Total PAHs
Total PCBs
Benzo[a]pyrene
Fluoranthene
28
_
6
30
—
_
17
_
_
—
—
8
59
17
_
23
22
—
—
21
26
66
—
80
—
12
16
-
9
—
—
-
-
—
_
0-10
—
0-10
20-50
10-20
10-20
0-10
20-50
>50
—
-
4.7
4.6
2.1
3.8
5.6
—
—
3.2
—
—
42
95
Sources:
'Seidemann. D.E.. 1991.
'Kelly, af at.. 1991.
1 Guieu and Martin, at al., 1991. (note that variances from flux measurements were approximately equal to the mean).
'Warmenhoven, era/.. 1989.
* Estimated from data in preceding table.
Table 3.4 Estimated below fall line loadings of trace metals and organic contaminants to Chesapeake Bay from
various portions of the Bay watershed. Loads are in pounds per year.
Urban storm water loads
Trace metals1
PAHs2
Point source loads
Trace metals1
PAHs2
West
Chesapeake
280.000
1,400
West
Chesapeake
290,000
1.4004
Patuxent
100,000
100
Patuxent
NE
NE
Potomac
170.000
620
Potomac
134.6501
NE
Rapp.
17.000
0
Rapp.
NE
NE
York
17.000
160
York
NE
NE
James
120,000
260
•
James
70.000
150*
Eastern
Shore
69,000
160
Eastern
Shore
6,300
NE
1 Trace metals include arsenic, cadmium, chromium, copper, lead, mercury, and zinc.
2 PAHs include benzofajpyrene, chrysene, fluoranthene and naphthalene.
3 Does not include arsenic, for which no estimate was available.
4 Estimate does not include chrysene and fluoranthene, for which data were not available.
* Estimate does not include naphthalene, for which data were not available.
Sources: Chesapeake Bay Program, 1994a and Chesapeake Bay Program, 1994b
-------
Sediment Characteristics
Average deposition rates of sediment vary among regions of the mainstem Bay (Table 3.1). The highest
deposition rates are observed in segments three and four in the middle mainstem Bay. Relatively high
sedimentation rates are also observed at most of the river mouth stations, with the exception of the
Rappahannock River, a relatively fast flowing river.
Most sampled areas in the mainstem Bay had sediments classified as sandy mud, with the percentage of silt and
clay between 50 and 85 percent (Table 3.5). River mouth stations (except for the mouth of the James River) and
stations in the deep channel in the middle mainstem Bay had sediments of mud, with silt and clay greater than 85
percent. Sediments in segments one and eight at the extreme upper and lower end of the mainstem Bay,
respectively, had coarser sediments (silt and clay between 10 and 50 percent). Grain size composition of
sediments within the different segments varied substantially (Table 3.5 and Figure 3.3). Median percent silt and
clay were similar on the western, central, and eastern portions of the transects across the deep trough of the
midbay. However, the range of percentage silt and clay was greater among samples from the eastern flank of
the midbay.
Median sediment total organic carbon (TOC) concentrations increased from about 2.5 percent at the extreme
upper end of the mainstem Bay in segment one to a peak of approximately 4 percent in segment two, and then
gradually declined towards the mouth of the Bay, with markedly lower concentrations in segments seven and
eight, where TOC concentrations were about 0.5 percent (Table 3.6 and Figure 3.4). Total organic carbon
concentrations are somewhat lower in the eastern portion of the midbay than in the central and western portions.
The Potomac River mouth station had average TOC concentrations of about 3.5 percent, while the other river
mouth stations had lower TOC concentrations, ranging from 1 to 2.5 percent. The mainstem Bay average TOC
concentration was 2.55 percent. The maximum TOC concentration, 7.74 percent, was found in segment two.
In 1986, Hennessee, etal. reported an average sediment total organic carbon concentration of total organic
carbon of 2.1 percent for the Maryland portion of the mainstem Bay. Total organic carbon was significantly
correlated with the mud content of the sediment. In the northern portion of the mainstem Bay (above the Bay
bridge) the average sediment TOC concentration was 3.3 percent and in the middle portion of the Bay (from the
Bay bridge to the Maryland border), sediment TOC averaged 1.7 percent.
Most of the carbon in the upper Bay is terrestrial in origin and largely carried by the Susquehanna River. Some of
this carbon is refractory, originating from coal, plant detritus, and anthropogenic sources. In the middle mainstem
Bay, (below the Bay Bridge) algal production contributes the largest portion of organic carbon (Hennessee, etal.,
1986)'.
llt-8
-------
Table 3.5 Summary statistics (or percent silt and clay in Chesapeake Bay rnainstem sediments. Statistics are
presented for all mainstem stations; Chesapeake Bay Program segments which divide the Bay into latitudinal
segments with segment 1 at the mouth of the Susquehanna River and segment 8 at the Bay mouth; groups of
stations within and adjacent to the deep trough of the midbay; and for stations located at the mouths of the
Potomac, Rappahannock, York and James Rivers, and in Mobjack Bay, near the mouth of the York River.
Area
Mainstem
Segment 1
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Segment 8
Mid bay
Center
East
West
River mouths
Potomac R.
Rapp. River
Mobjack Bay
York River
James River
Mean
75
14
79
86
83
72
51
19
94
71
84
94
94
95
89
37
Median
67
3
5
12
21
9
4
2
10
8
8
3
2
2
2
2
N
28
14
13
24
13
27
35
8
3
28
6
5
0.2
0.6
10
40
SD
3
3
60
10
49
19
5
13
89
10
75
89
94
95
82
9
Min
87
10
87
93
86
81
61
19
93
80
85
95
94
95
89
37
Max
100
30
90
100
98
99
79
25
99
96
91
98
94
96
96
66
ill-9
-------
Table 3.6 Summary statistics for total organic carbon in mainstem Chesapeake Bay sediments.
Concentrations are in per cent dry weight.
Area
Mainstem
Segment 1
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Segments
Mean - p
2.55
2.49
4.03
3.20
2.46
2.33
0.56
0.43
Median
2.55
2.24
4.20
3.47
2.50
2.60
0.48
0.43
N
88
4
7
17
31
11
4
2
SD- o
1.37
2.22
2.16
1.34
0.86
0.87
0.31
0.38
Min
0.10
0.10
1.20
0.30
0.50
0.23
0.30
0.16
Max
7.74
5.40
7.74
4.70
3.91
3.15
1.00
0.70
Midbay
Center
East
West
2.84
t.93
3.00
3.05
2.11
3.28
14
12
12
0.88
1.03
0.76
1.40
0.30
1.60
4.40
3.24
4.00
River Mouths
Potomac
Rappahannock
Mobjack Bay
York
James
3.41
2.37
1.45
1.59
1.11
3.47
2.37
1.45
1.59
1.11
4
2
2
2
2
0.29
0.33
0.06
0.01
1.26
3.00
2.13
1.40
1.58
0.22
3.68
2.60
1.49
1.60
2.00
IH-10
-------
General Patterns in the Spatial Distribution of Trace Metals
Trace metals such as arsenic, cadmium, and lead are naturally present in the earth's crust, and their presence in
the sediment does not necessarily indicate contamination from human activities. Some trace metals are
essential to organisms in minute quantities, but may become toxic if present in high concentrations.
In addition to natural sources such as shoreline erosion and sediments from the watershed, trace metals reach
Chesapeake Bay from anthropogenic sources. Trace metals from wood preservatives, the combustion of fossil
fuels, pesticides, automobile tires and batteries, building materials such as pipes, roofing material and galvanized
gutters all may become components of stormwater runoff. Trace metals are involved in numerous industrial
processes, including electroplating and the manufacture of metal alloys, and thus are frequently found in
industrial effluents. Trace metals also may reach Chesapeake Bay through municipal effluents and atmospheric
deposition.
III-11
-------
Figure 3.3 Percentage silt and clay
in mainstem sediments
Segments
1 OO
SEC1 SCC2 SEG3 SEC-* SEGS
II. Transects
seoa
1 OO
CEIMTEW
III. FUver
EA.ST
too
SO
Figure 3.3 Summaiy statistics for percent silt-clay in Chesapeake Bay mainstem sediments.
The box and whisker plots illustrate the median (central horizontal line), the quartiles (extent of
the rectangle), and ranges (extent of vertical lines) of the data. If there are less than four
values, the rectangle's bottom and top represent the range. A dash indicates only a single
value is available. The stations are aggregated by: I. Chesapeake Bay Program mainstem
segments; II. transects across the midbay deep trough; and III. stations at the mouth of the
Potomac, Rappahannock, York and James Rivers, and in Mobjack Bay.
111-12
-------
Figure 3.A Reroontag© total organic carbon
in mainstem sediments
I. rs/Isunsst©m Segments
1 O.O
•y.a
s.o
O.O
SEG1 SCC2 SEOJS SEC* SEO2> SCC7 SEGQ
II. Transects
AO.O
2.S
O.O
WEST
III. River (X/Ioutris
1O.O
S.O
o.o-U
VORK
Figure 3.4 Summary statistics for percent total organic carbon in Chesapeake Boy mainstem
sediments. The box and whisker plots illustrate the median (central horizontal line), the quartiles
(extent of the rectangle), and ranges (extent of vertical lines) of the data. If there are tess than
four values, the rectangle's bottom and top represent the range. A dash indicates only a
single value is available. The stations are aggregated by: I. Chesapeake Bay Program
mainstem segments; II. transects across the midbay deep trough; and III. stations at the mouth
of the Potomac, Rappahannock, York and .James Rivers, and in MobjackBay.
11-13
-------
In the mainstem Bay sediment contaminant monitoring program, sediments were analyzed for eight trace metals:
arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc. Of these, cadmium, chromium, copper,
lead and mercury are Chesapeake Bay Toxics of Concern, while arsenic and zinc are on the list of compounds
for which additional information is being sought (Chesapeake Bay Program, 1991 a).
The spatial distribution of trace metal concentrations in mainstem Bay sediments displayed a consistent pattern of
low concentrations in segment one at the mouth of the Susquehanna River, markedly higher average
concentrations in segments two through five in the region from Turkey Point to just below the Potomac River
mouth, and then markedly lower average concentrations in segments seven and eight in the lower portion of the
Bay southeast of the mouth of the Rappahannock River (Figures 3.5 through 3.12). The highest concentrations
and the greatest variability in trace metal concentrations were observed in segment three.
This spatial pattern changed when trace metal concentrations were normalized by the fraction of fine particles in
the sediment, indicating that the pattern in measured sediment concentrations of some trace metals may reflect
differences in grain size composition among stations (Tables 3.1 and 3.5) more than differences in metal
loadings. Normalized sediment trace metal concentrations were fairly uniform throughout the length of the
mainstem Bay for arsenic, cadmium, chromium, and mercury, while for copper, lead, nickel and zinc, the highest
values occurred in the extreme upper Bay with concentrations generally declining towards the mouth of the Bay
(Figures 3.5-3.12). This down-Bay decrease in the concentration of these trace metals suggests that the
Susquehanna River may represent the major source of these metals to the Bay. Helz, et al. (1983) found a
down-Bay decrease in the concentration of several trace metals in the silt and clay fraction of sediment samples
consistent with this finding. The large differences between bulk and normalized trace metal concentrations in the
extreme upper and lower Bay (segments one and eight) are due to the high percentage of sand in the sediments
in these segments.
In the middle mainstem Bay (segments three and four), the average measured concentrations of most trace
metals decreased from west to east, with the exception of mercury, which reaches its highest concentration in the
center of the mid-Bay (Figures 3.5-3.12). This gradient in trace metal concentrations is reduced somewhat when
sediment concentrations are normalized for grain size, but the western middle mainstem Bay stations still have
higher normalized sediment concentrations of most trace metals than do those in the east. This finding suggests
that the east-west pattern in sediment trace metal concentrations may be partly due to differences in the
magnitude of inputs from the two shores and/or to differences in sediment origin. This decreasing gradient in
trace metal concentrations from west to east was also evident in the analyses of the silt and clay fraction of
sediments conducted by Hetz, etal. (1983). At the river mouths and in Mobjack Bay, both measured and
normalized concentrations of most trace metals are fairly similar among stations and comparable to the
concentrations in the lower portion of the Bay. However, the average cadmium and mercury concentrations are
markedly higher at the mouth of the Potomac River than at the other river mouth stations (Figures 3.5-3.12).
The pattern of trace metal loadings, as estimated by the Chesapeake Bay Program (1994a), seems fo
correspond more closely to the pattern of normalized sediment metals concentrations than to that of the
measured sediment metal concentrations. Fall line loads to the Susquehanna River are often the highest
loadings of the various basins of the Chesapeake Bay (Chesapeake Bay Program (1994b). Below fall line loads
to the West Chesapeake and Potomac regions are relatively high, with relatively small loads to the
Rappahannock, York and Eastern Shore regions, and moderately increased loads to the James region (Table
3.4).
Median sediment concentrations of arsenic, chromium, copper, lead and zinc exceeded the No Observable
Effects Level (NOEL) concentrations in the more metal-rich regions of the mainstem (the western and central
portions of segments three and four, as well as segments two and five for some metals) (Tables 3.7a-3.14a).
The median concentrations of cadmium did not exceed the NOEL concentration in any region of the mainstem,
and median concentrations of mercury exceeded the NOEL only in segment two. Only zinc was found at
concentrations above the Probable Effects Level (PEL), the concentrations above which toxic effects to aquatic
biota are considered probable (MacDonald. 1993 and Table 3.14a). Current sediment quality guidelines are
111-14
-------
inadequate for assessing the likelihood of toxicity due to sediment concentrations of nickel. Toxic effects to
aquatic biota due to the measured sediment trace metal concentrations are unlikely in most sampled locations in
the mainstem Bay. Toxic effects due to sediment zinc concentrations are probable in some areas within
segments two through five. However, the potential for toxic effects due to sediment trace metal concentrations
may be reduced by the presence of significant quantities of acid-volatile sulfide in much of the middle portion of
the mainstem (Table 3.15). The quantity of acid volatile sulfide in the sediment is not considered in the PEL
guidelines (MacDonald. 1993).
Temporal Trends in Trace Metal Concentrations
There were few instances in which the mean measured concentrations of trace metals in 1991 were consistently
significantly higher or lower than both the 1984 and 1985 concentrations. For most trace metals, mean
concentrations in mainstem regions in 1991 tended to be lower than those observed in earlier years. This trend
was particularly evident for cadmium. Arsenic was the only trace metal to show consistently higher mean
sediment concentrations within mainstem regions in 1991 than in 1984 and 1985, but no potential source or
cause for the apparent increase has been identified.
A review of the latitude and longitude of the mainstem Bay stations sampled in 1977-79 (Helz, et a/., 1983),
identified eleven stations which were near a station sampled as part of the recent monitoring program.
Comparison of the 1977 data from these eleven stations with the 1991 data shows that sediment concentrations
of most trace metals in the mainstem were generally lower in 1991 than in the late 1970s. Sediment cadmium
concentrations have shown a rather large reduction, while other metals show more modest decreases.
Sediments were not analyzed for arsenic and mercury concentrations in the 1977-79 study.
General Patterns in the Spatial Distribution of Pol/cyclic Aromatic Hydrocarbons
Polycyclic aromatic hydrocarbons (PAHs) are composed of two or more fused aromatic rings. PAHs are
naturally produced by volcanos and forest fires, and some PAHs may also be formed from other natural sources
such as plant pigments (Bouloubassi and Saliot, 1993). Anthropogenic sources of PAHs include spills of
petroleum products, which typically release lower molecular weight PAHs, and the incomplete combustion of
fossil fuels, generally resulting in the formation of higher molecular weight PAHs (National Oceanic and
Atmospheric Administration, 1991). Polycyclic aromatic hydrocarbons are also released into the aquatic
environment via oil refinery effluents (MacDonald, 1993). Anthropogenic fossil fuel combustion has greatly
increased environmental PAH concentrations (Menzie, et a/.. 1992). '
Although complete data have not been assembled, at least eight PAHs are considered possible or probable
carcinogens: benzo[a]anthracene, chrysene, benzo[b]fluoranthene. benzo[k]fluoranthene, benzo'ajpyrene,
indeno[1,2,3-ctfJpyrene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene (Menzie, era/., 1992). Other PAHs
display no carcinogenic, teratogenic, or mutagenic activity. PAHs can be highly toxic to aquatic organisms,
although the bioavailability of PAHs, as with many nonpolar organic compounds, ts known to depend on the
concentration of total organic carbon in the sediment (MacDonald, 1993).
The suspected carcinogens listed above are commonly found in PAH mixtures, as are many compounds which
may be present in smaller amounts, or which are not consistently detected or identified. Total PAHs is an
unspecified mixture of compounds which can vary widely in toxicity, depending on its specific composition.
Several individual PAHs were measured and are discussed below, but some mixtures of PAHs resulting from
combustion or petroleum products have been shown to be carcinogenic, and thus total PAHs was also
measured. 6enzo[a]pyrene, chrysene, fluoranthene, and naphthalene are PAHs that are Chesapeake Bay
Program Toxics of Concern (Chesapeake Bay Program, 1991a).
Fewer stations were sampled for organic contaminants than for trace metals (Table 3.1). The three river mouth
stations and Mobjack Bay and one or two stations in each of the mainstem segments (except segment six) were
111-15
-------
sampled for organic contaminants (Table 3.1 and Figure 3.1). The sediment concentrations of many individual
polycyclic aromatic hydrocarbons (PAHs) were measured , e.g., anthracene, benzo[a]anthracene,
benzofajpyrene, etc., as well as total PAHs.
The concentrations of polycyclic aromatic hydrocarbons in mainstem Bay sediments show a somewhat different
spatial pattern than that observed for trace metals. Instead of a broad peak in the middle mainstem Bay,
concentrations of PAHs peak in a more narrow region within segments two and three, with the highest
concentrations in segment two, between Turkey Point and the mouth of the Middle River (Tables 3.17-3.29).
Median sediment concentrations of polycyclic aromatic hydrocarbons are similar among the river mouth stations,
and generally comparable to the lower concentrations observed in the mainstem outside of segments two and
three (Table 3.17-3.29). No sediment concentrations of any of the PAHs were in excess of the relevant PEL
concentration (Macdonald, 1993 and Tables 3.17-3.29). Toxic effects to aquatic biota due to the measured
sediment concentrations of PAHs are not likely at the monitored locations in the mainstem Bay.
This spatial distribution of sediment concentrations of PAHs is similar to that displayed by sediment total organic
carbon (TOC) (see Table 3.6 and Figure 3.4). However, the pattern in the distribution of PAHs cannot be entirely
attributed to patterns in TOC, concentrations, since for most PAHs a similar pattern is evident when the sediment
PAH concentrations are carbon-normalized , i.e., divided by the fraction of TOC in the sediment (Tables 3.17-
3.29).
Due to the small number of samples and high variability, no statistically significant differences in sediment
concentrations were found among the different years of the monitoring program for any of the measured or
normalized concentrations of PAHs analyzed.
General Patterns in the Spatial Distribution of Chlorinated Organic Compounds
The chlorinated organic compounds identified in mainstem Bay sediment samples included polychlorinated
biphenyl (PCB) congeners, chlorinated hydrocarbons such as organochlorine pesticides, and one dioxin
compound. Information on a suite of individual PCB congeners was also used to estimate the concentration of
total PCBs in sediment samples.
Many of the organochlorine pesticides detected were previously widely used, but are either not currently
registered for use in the U.S., or their uses have been narrowly restricted (MacDonald, 1993). Similarly, the uses
of PCBs were curtailed in the U.S. in 1971. However, most of these compounds tend to accumulate in sediments
and some may persist there for long periods (MacDonald, 1993). In addition, many of these chemicals can
become concentrated in wildlife tissue (MacDonald. 1993).
Sediment samples were analyzed for a suite of chlorinated pesticides and other chlorinated organic compounds
in 1984 and 1985. However, the detection limits for all compounds were too high to provide meaningful
information on the distribution and concentration of these compounds in mainstem Bay sediments. The analysis
of sediment samples conducted by the Virginia Institute of Marine Science in 1991 was sufficiently sensitive to
provide a realistic picture of the levels of these compounds in mainstem Bay sediments. Only data from 1991 are
discussed below (Tables 3.30 and 3.31).
Although several chlorinated organic compounds were found at many of the stations, concentrations in all cases
were very low (Table 3.30). Measured concentrations were all below ER-M or PEL values for compounds for
which these sediment guidelines are available. Toxic effects to aquatic biota due to the measured sediment
concentrations of chlorinated organic compounds are not likely at the sampled locations in the mainstem Bay.
111-16
-------
Spatial and Temporal Distributions of Individual Trace Metals
Arsenic
Arsenic is not listed as a Chesapeake Bay Toxic of Concern, but is a' substance for which more information is
being sought (Chesapeake Bay Program 1991a, 1991b). It may be released into the environment naturally
through volcanic activity or the weathering of arsenic-rich rocks. Anthropogenic sources include fossil fuel
combustion, the production of metal alloys, pesticides, fertilizers made from phosphate rock rich in arsenic, and
wood preservatives (Long and Morgan. 1990; MacDonald, 1993; Chesapeake Bay Program 1991b).
The median sediment arsenic concentration in the mainstem was 8.5 ppm. The maximum value of 282 ppm
(Table 3.7a and Figures 3.5) was found at station MC84.1 W in the lower mid-Bay in 1991. The No Observable
Effect Level for arsenic (8.0 ppm) was equalled or exceeded by median concentrations in segments two, three,
four, five, and at the stations located at the mouth of Mobjack Bay (Table 3.7a). The maximum measured
arsenic concentration of 28.2 ppm was well below the Probable Effect Level value of 64 ppm (MacDonald, 1993
and Table 3.7a). Toxic effects to aquatic life due to the measured concentrations of arsenic in mainstem
sediments are not likely at any of the monitored areas of the mainstem Bay.
When significant differences in sediment concentrations of arsenic were found among different years of
sampling, sediment arsenic concentrations in 1991 were generally higher than those found in earlier years.
However, with so few samples, no conclusion as to a trend can be drawn. Historical data on sediment arsenic
concentrations were not available for comparison with the more recently collected data.
111-17
-------
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Table 3.7b Temporal variability in arsenic concentrations in Chesapeake Bay mainstem sediments. Means for
years not connected by the underline are significantly different (p=0.05) as determined by ANOVA followed by a
Duncan's multiple range test. The means indicated by the year are ordered from high to low. NS = no significant
differences. There were insufficient data to perform the test in segments one and eight and the river mouth
stations and Mobjack Bay.
Area
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Normalized
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Segment 3
Segment 4
Segment 5
Segment 7
Center
East
West
NS
91 84 85
91 84 85
91_84 85
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91 84 85
91 85 84
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91 84 85
NS
£1 M 85
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9J. 85
111-19
-------
Figure 3.5 Arsenic concentrations (ppm)
in mainstem sediments
20
10
Measured
la. IVIalnstem Segments
ao
eo
Silt-Clay Normalized
It3. rs/Iainstem Segments
SEG1 SEC2 SEC3 SEC* SEC9 SECT SeCS SEC1 SEC2 SEC3 SEC-* SECS SCC7 see 9
ao
r 20
10
Ha. Transects
eo
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ao
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ROT
MBJX
VORK JAMES
POT
MBJK VORK
Figure 3.5 Summary statistics for measured and silt-clay normalized sediment concentrations
of arsenic in the Chesapeake Bay mainstem. The box and whisker plots illustrate the median
(central horizontal line), the qualifies (extent of the rectangle), and ranges (extent of vertical
lines) of the data. If there are less than four values, the rectangle's bottom and top show the
range. A dash indicates only a single value is available. The stations are aggregated by: I.
Chesapeake Bay Program mainstem segments; II. transects across the midbay deep trough;
and III. stations at the moulh of the Potomac, Rappahannock, York and James Rivers, and in
Mobjack Bay. The NOEL and PEL values for measured sediment arsenic concentrations are 8
ppm and 64 ppm, respectively (MacDonald, 1993).
111-20
-------
Cadmium
Cadmium, a Chesapeake Bay Toxic of Concern, (Chesapeake Bay Program 1991 a and b), has numerous
industrial uses and is found in tires and gasoline. Primary cadmium sources to the Bay are industrial and
municipal effluents, landfills, and nonpoint sources (Chesapeake Bay Program, 1991b). In addition, cadmium is
a natural element found in soils and rocks.
The median measured sediment cadmium concentration in the mainstem Bay was 0.40 ppm (Table 3.8a). The
maximum value of 2.9 ppm (Table 3.8a) was found six times in 1984 at stations MCB3.1, MCB3.2, MCB3.3W,
MCB3.3C, MCB4.2W and MCB4.3W in segments three and four (Table 3.8b and MacDonald, 1993), The NOEL
for cadmium (1.0 ppm) was not exceeded by median concentrations except at the mouth of the Potomac River
(Table 3.8a). All measurements were well below the PEL concentration of 7.5 ppm (Table 3.8a and
MacDonald, 1993). Toxic effects to aquatic life due to the measured concentrations of cadmium in mainstem
sediments are not likely at any of the mainstem Bay stations sampled.
The mean sediment measured and normalized concentrations of cadmium in 1991 were consistently lower than
mean concentrations observed in 1984 and 1985. (Table 3.8b). Concentrations from 1991 were also much lower
than those observed at nearby locations in 1977 by Helz, et al. (1983) (Figures 3.6b-c).
u
111-21
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years not connected by the underline are significantly different (p=0.05) as determined by ANOVA followed by a
Duncan multiple range test The means are ordered from high to low. NS = no significant differences. There
were insufficient data to perform the test in segments one and eight, at the river mouth stations, and Mobjack
Bay.
Area
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Normalized
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Segment 4
Segment 5
Segment 7
Center
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West
NS
84 85 91
84 85 91
84 85 9J.
84 91
111-23
-------
Figure 3.$b Measured Cadmium Concentrations in Main&tem Sediments
1977 v. 1991
~MC*T 1
K'CB3 3 vc:i?4.> V.C35.S CB7.2
MCB3..3 MCB-1-2 MCIU: 4 C
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a
1971
Figure 3.&c Normalized Cadmium Concentrations In Matostent Sadlmants
1977v. 1981
1.5
0.5
MCB21
MCB5.2
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VCB4.1 Mns.l CH/ IS
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n
1991
Comparison of Cadmium concentrations in mainstem sediments in 1977 and 1991. Station designation refer to
the Chesapeake Bay Program monitoring stations. Data in 3.6b are measured sediment cadmium
concentrations while the data in 3.6c are normalized, that is deivided, by the silt-clay fraction of the sediment
samples.
III-24
-------
Figure 3.6a Cadmium concentrations (ppm)
in mainstem sediments
Measured
la. Mainstem Segments
Silt-Clay Normalized
lt>. IVIainstem Segrments
SEC2 sees sec* sees sec? SECS SECI SEGZ SEC 3 SEC* sees SECT seca
"Transects
Transects
WEST
CENTER
EAST WEST
EAST
Ilia. River Mouths
Ml to. River fvlouthis
»»OT
MOOK
VORK
JAMES
VORK
Figure 3.6a Summaiy statistics for measured and sitf-clay normalized sediment concentrations
of cadmium in the Chesapeake Bay mainstem. The box and whisker plots illustrate the
median (central horizontal line), the quartiles (extent of the rectangle), and ranges (extent of
vertical lines) of the data. If there are less than four values, the rectangle's bottom and top
show the range. A dash indicates only a single value is available. The stations are aggregated
by: I. Chesapeake Bay Program mainstem segments; II. transects across the midbay deep
trough; and III. stations at the mouth of the Potomac, Rappahanncck. York and James Rivers,
and in Mobjack Boy. The NOEL and PEL values for measured sediment cadmium
concentrations are 1.0 ppm and 7.5 ppm, respectively (MacDonald, 1993).
-------
Chromium
Chromium, a Chesapeake Bay Toxic of Concern, is used in the manufacture of paint pigments, stainless steel
and other electroplated metals, and enters the environment primarily through industrial sources, although it is
also present naturally in rocks and soils (Chesapeake Bay Program 1991a and 1991b).
The mainstem median sediment chromium concentration was 35.6 pprn (Table 3.9a). The maximum value of
62.8 ppm (Table 3.9a) was found in 1991 at station MCB3.3W in segment three (Table 3.9a and Figure 7a). The
median concentration of chromium exceeds the NOEL (33 ppm) in segments three, four, and five at the river
mouth stations and Mobjack Bay, except for the James (Table 3.9a and MacDonald, 1993). However, all
measured mainstem Bay chromium concentrations were well below the PEL of 240 ppm (Table 3.9a and
MacDonald, 1993). Toxic effects to aquatic biota due to the measured sediment chromium concentrations are
not likely at the monitored mainstem Bay stations.
There were few significant differences between annual mean sediment concentrations of chromium from 1984-
1991 (Table 3,9b). At most stations where data were available, the measured and/or normalized chromium
concentrations were somewhat lower in 1991 than in 1977 (Helz, et al. 1983), but differences in concentrations
were generally not large (Figures 3.7b-c).
Nl-25
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-------
Table 3.9b Temporal variability in chromium concentrations in Chesapeake Bay mainstem sediments. Means
for years not connected by the-underline are significantly different (p=0.05) as determined by ANOVA followed by
a Duncan multiple range test. The means indicated by the year are ordered from high to low. NS = no significant
differences. There were insufficient data to perform the test in segments one and eight and the river mouth
stations and Mobjack Bay.
Area
Measured
Normalized
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Center
East
West
84 91 85
NS
84 91 85
NS
NS
NS
NS
84 91
84 91 85
NS
91 85
III-28
-------
Figure 3.7a Chromium concentrations (ppm)
in mainstem sediments
100
SO
Measured
la. Mainstorn Segments
200
ISO
1 OO
Silt-Clay Normalized
>. rviainstem
SEC1 SEG2
100
SEC-* SCGS SEC7 SECO
Ha. Transects
200
ISO
100
90
SEC2 sees sec-* sees SECT- seca
lit). Transects
WEST CENTER
TOO
Ilia. River Mouths
EAST WEST
2OO
1 SO
1OO
SO
CENTER
I lib. River
EAST
ROT
YORK
POT
VORK
Fgure 3.7a Summary stcstistics for measured and silt-clay normalized sediment concentrations
of chromium in the Chesapeake Bay mainstem. The box and whisker plots illustrate the
median (central horizontal line), the quartiles {extent of the rectangle), and ranges {extent of
vertical lines) of the data. If there are less than four values, the rectangle's bottom and top
show the range. A dash indicates only a single value is available. The stations are aggregated
by: I. Chesapeake Bay Program mainstem segments; II. transects across the midbay deep
trough; and III. stations at the mouth of the Potomac, Rappahannock, York and James Rivers,
and in Mobjack Bay. The NOEL and PEL values for measured sediment chromium
concentrations are 33 ppm and 240 ppm, respectively (MacDonald, 1993).
-------
Figuru 3.7b Measured Chromium Concentrations in Mainstem
1977v, 1991
c
£
•§2.
£
so-
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40 ••
20 -•
n iraJt4aJ|BU|riJii i|UU]n i|
MCKl.l MCH3.3 MCB4.?
1977
a
MCHS2
CB7.S
Station
3.7c Normallzjed Cnfomium Concentrations in Mainstem Sediments
1977V. 1991
80 f n
60
40
20 f
1977
n
1991
"MCT..1 .VC83.2 VCB4.2 VC65.2 CD/J
MCP.1 K1C6S.5 MCBJ2 MCI35.J C
WC3/..I MC55.1 CB7-1S
Motion
Comparison of Chromium concentrations in mainstem sediments in 1977 and 1991. Station desig
ion refer t<
the Chesapeake Bay Program monitoring stations. Data in 3.7b are measured sediment cadmium
concentrations while the data in 3.7c are normalized, that is deivided, by the silt-clay fraction of the sediment
samples.
III-29
-------
Copper
Marine and esfuarine organisms are very sensitive to copper, a Chesapeake Bay Toxic of Concern
(Chesapeake Bay Program 199 la, 1991b). Natural sources of copper include the weathering or solution of
copper-bearing minerals, copper sulfides, and native copper. Copper is frequently used in anti-fouJing paint,
wood preservatives, algicides, and fungicides (MacDonald, 1993). Copper is also widely used in the
electrical industry and plumbing, roofing and building construction, and is present in effluents from smelting,
refining, and metal plating industries (Chesapeake Bay Program. 199Ib). Leaching from power plant pipes
has caused locally high concentrations of copper in shellfish in the Chesapeake Bay in the past (Roosenburg
1969).
The median copper concentration in mainstem sediments was 23.6 ppm, with a maximum concentration of
56 ppm (Table 3.lOa) measured in 1984 at station MCB3.2 in segment three (Table 3.1 Oa and Figure 3.8a).
Median copper concentrations in segments two, three, and four were above the NOEL concentration (28
ppm), with the NOEL also exceeded several times in segment five (Table 3.10aand MacDonald, 1993).
Among the river mouth stations, only one observation was above the NOEL, and this observation at the
Potomac River mouth only exceeded the NOEL by a very small margin (Table 3.10a and MacDonald, 1993).
All observations were below the PEL concentration of 170 ppm (Table 3. lOa and MacDonald, 1993). Toxic
effects to aquatic life due to the measured sediment copper concentrations are not likely at the mainstem Bay
stations sampled.
There were few significant differences between annual mean sediment concentrations of copper. Where
differences were found, concentrations in 1991 were lower than in preceding years (Table 3,10b). Sediment
copper concentrations in 1977 (Heiz, et al 1983) were generally higher than those observed at nearby areas
in 1991 (Figures 3.8b-c).
111-30
-------
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Table 3.1 Ob Temporal variability in copper concentrations in Chesapeake Bay mainstem sediments. Means for
years not connected by the underline are significantly different (p=0.05) as determined by ANOVA followed by a
Duncan multiple range test. The means indicated by the year are ordered from high to low. NS = no significant
differences. There were insufficient data to perform the test for segments one and eight and the river mouth
stations and Mobjack Bay.
Region
Measured
Normalized
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Center
East
West
NS
NS
NS
84 85 91
NS
84 85 91
NS
84 85 91
NS
NS
NS
NS
NS
84 85 91
NS
85 91
III-32
-------
Figure 3.8a Copper concentrations (ppm)
in mainstern sediments
1OO
SO
Measured
la. Mainstem Segments
i eo
1 20
ao
Silt-Clay Normalized
!fc>. Mainstem Segments)
e
o
SCG1 SEC2 SCC3 SEC* SECS SCC7 SECO SEC t SEC2
1OOt ISO
Ha. Transects
1 20
BO
SEC-* SEC3 SCC7 2 ECO
IIt>. Transects
WEST
WCST
1OO
SO
Ilia.. River IVJouths
ICO
120
ao
CENTER
lllt>. Fllver
| AST
f»OT
JAMES
VORK
UAI
-------
Figure 3,8b Measured Copper Concentrations in Ma in stem Sediments
1977 v. 1991
'MCHi.l
WCP2.1
MC83.1
MC841
1977
D
C56.I
Siotlon
Figure 3.8c Normalized Copper Concentrations In Ma Ins tern Sediments
1977 v. 1991
ou •
1 40-
2
5
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T:
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1977
a
Comparison of Copper concentrations in mainstem sediments in 1977 and 1991. Station designation refer to the
Chesapeake Bay Program monitoring stations. Data in 3.8b are measured sediment cadmium concentrations
while the data in 3.8c are normalized, that is dervided, by the silt-clay fraction of the sediment samples.
III-34
-------
Lead
Lead, a Chesapeake Bay Toxic of Concern, has many industrial applications, including use in tank linings and
piping, petroleum refining, paint pigments, batteries, ceramics, plastics, electronic devices, and the
manufacture of steel and other metals (Chesapeake Bay Program, 199 la, 1991b). It was previously added to
gasoline, but this use has been discontinued with a few exceptions (Chesapeake Bay Program, 1991b). Lead
is generally more toxic in the form of organolead compounds (Long and Morgan, 1990) than in the elemental
forms.
The median sediment lead concentration in the mainstem Bay was 35 ppm, with the maximum value of 86
ppm (Table 3.1 la and Figure 3.9a) measured in 1984 at stations MCB3.2 and MCB3.3W in segments two
and three, respectively. The NOEL concentration for lead (21 ppm) is equalled or exceeded by the median
measured sediment concentrations in segments two, three, four, and five and at all the river mouth stations
and Mobjack Bay except for James River (Table 3.1 la and MacDonald, 1993). However, the PEL
concentration of 160 ppm is well above all measured concentrations (Table 3.1 la and MacDonald, 1993).
Toxic effects to aquatic life due to the measured sediment lead concentrations are not likely at the sampled
mainstem Bay stations.
There were some significant differences between annual mean sediment concentrations of lead. Where
differences were found, sediment lead concentrations in 1991 were lower than in preceding years (Table
3.1! b). Comparison of 1977 data (Helz, et al. 1983) with 1991 data shows that sediment lead
concentrations were higher in 1977 than in 1991 in most of the upper and middle Bay, but lower than 1991
concentrations in the extreme upper Bay and the lower portion of the mainstem Bay (Figures 3.9b-c).
111-35
-------
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Table 3.1 Ib Temporal variability in lead concentrations in Chesapeake Bay mainstem sediments. Means for years not connec ed bvl
the underline are significantly different (pO.05) as determined by ANO VA followed by a Duncan multiple range test. The mi ans
indicated by the year are ordered from high to low. • NS ~ no significant differences. There were insufficient data to perform tl e test I
for segments one and eight, the river mouth stations, and Mobjack Bay.
Area
Measured
Normalized
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Center
East
West
NS
NS
84 91 85
NS
NS
NS
NS
84 85 91
NS
NS
NS
NS
NS
NS
NS
NS
III-37
-------
Figure 3.9a Lead concentrations (ppm)
in mainstem sediments
too
SO
Measured
la. IVIainstern Segments
eoo
soo
-*oo
2OO
1OO
Silt-Clay Normalizecf
lt>. IVIainstem Segments
seci SE02 seca sec-* sees sec? seca
SEGl SCO2 SEG.3 SCO*
SEG7 SEGO
1OO
I la. Transects
eoo
soo
*oo
soo
200
100
111> - Transects
WEST
CEMTER
CAST
WEST
100
so
2S
Ilia.. River rs/louithis
soo
300
2OO
too
. River Mouths
MBJK YORK JAMES
ROT
VORK
JAMES
Figure 3.9a Summary statistics for measured and silt-clay normalized sediment concentrations
of lead in the Chesapeake Bay mainstem. The box and whisker pbts illustrate the median
(central horizontal line), the quartiles (extent of the rectangle), and ranges (extent of vertical
lines) of the data. If there are less than four values, the rectangle's bottom and top show the
range. A dash indicates only a single value is available. The stations are aggregated by: I.
Chesapeake Bay Program mainstem segments; II. transects across the midbay deep trough;
and III. stations at the mouth of the Potomac. Rappahannock, York and James Rivers, and in
Mobjack Bay. The NOEL and PEL values for measured sediment tead concentrations are 21
ppm and 160 ppm, respectively (MacDonald, 1993).
111-38
-------
I
o
Figure 3.9b Measured Lead Concentration? in Mainst&m Sediments
1977 v. 1991
60 ••
40-
20-
Figure 3.9c Normalized Lead Concentrations in Mafnsiem
1977 v. 1931
80-r
1977
d
1991
W77
n
Stafion |
Comparison of Lead concentrations in mainstem sediments in 1977 and 1991. Station designation refer to the
Chesapeake Bay Program monitoring stations. Data in 3.9b are measured sediment cadmium concentrations wf ile the
data in 3.9c are normalized, that is dehrided, by the silt-clay fraction of the sediment samples.
III-39
-------
Mercury
Mercury, a Chesapeake Bay Program Toxic of Concern, can exist as inorganic mercury (mercury II) or as organic
mercury (Chesapeake Bay Program. 1991 a and 1991 b). Organic mercury, especially methylmercury, is generally more
toxic than inorganic mercury. Mercury is a natural component of sediment, and is used in the chemical, paint, and put'
and paper industries. Mercury-based pesticides were once used in agriculture, but the use of such pesticides has bet
restricted (MacDonald, 1993).
The median concentration in the mainstem Bay was 0.08 ppm (Table 3.12a). The maximum mercury concentration of
0.80 ppm (Table 3.12a and Figure 3.10) was found at station MCB3.3C in segment three in 1984. Median sediment
mercury concentrations in segments two and three and the Rappahannock River mouth stations equalled or exceeded
the NOEL concentrations of 0.10 ppm. and the maximum concentration at the Potomac River mouth station was also
well above this concentration (Table 3.12a and MacDonald, 1993). All measurements of sediment mercury
concentrations were well below the PEL of 1.4 ppm (Table 3.12a and MacDonald, 1993). Toxic effects to aquatic life
due to the measured mercury concentrations in the sediment are not likely at the mainstem Bay stations sampled.
There were few significant differences between annual mean measured or normalized sediment concentrations of
mercury. Where differences were found, sediment mercury concentrations in 1991 were lower than in preceding years
(Table 3.12b). Historical data on mercury concentrations were not available for comparison with the recently collected
data.
III-40
-------
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Table 3.12b Temporal variability in mercury concentrations in Chesapeake Bay mainstem sediments. Means for years
not connected by the underline are significantly different (p<0.05) as determined by ANOVA followed by a Duncan
multiple range test. The means indicated by the year are ordered from high to low. NS = no significant differences.
There were insufficient data to perform the test for segments one and eight, the river mouth stations and Mobjack Bay.
Area
Measured
Normalized
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Center
East
West
84 85 91.
84 85 91
84 91 85
84 91 85
84 91
84 91 85
84 91 85
84 85 91
84 85 91
84 85 91
84 91 85
NS
NS
84 91 85
NS
NS
III-42
-------
Figure 3.1O Mercury concentrations (ppm)
in mainstern sediments
.00
o.ao
0.2S
o.oo
Measured
la. Mainstem Segments
Silt-Clay Normalized
lt>. rvlainstem Segments
I I ,
seci sees sees sec* SECS SEGV seca
.00
O.7S
_ o.so
O.2S
o.oo
1.00
I la. Transects
SCC1 SEC2 SEC .3 SEC* SECS SCG7 SEC S
lib. Transects
o.so
O.SCS
o.oo
CENTER
Ilia. River IS/louths
WEST
B
Illto. River Ivlouths
1
OOT
VORK
UAME S
Figure 3.10 Summcuy statistics for measured and silt-clay normalized sediment concentrations
of mercury in the Chesapeake Bay mainstern. The box and whisker plots illustrate the median
(central horizontal line), the quartiles (extent of the rectangle), and ranges (extent of vertical
lines) of the data. If there are less than four values, the rectangle's bottom and top show the
range. A dash indicates only a single value is available. The stations are aggregated by: I.
Chesapeake Bay Program mainstem segments; II. transects across the midbay deep trough;
and III. stations at the mouth of the Potomac, Rappanannock, York and James Rivers, and in
Mobjack Boy. The NOEL and PEL values for measured sediment mercury concentrations are
0.1 ppm and 1.4 ppm, respectively (MacDonald. 1993).
111-43
-------
Nickel
Nickel is not listed as a Chesapeake Bay Toxic of Concern (Chesapeake Bay Program, 1991 a). Nickel is used
primarily in the manufacture of stainless steel, nickel plating, and other nickel alloys. It is also used as a catalyst in
industrial processes and in oil refining (MacDonald, 1993). Nickel, like other trace metals, is naturally present in
soils, rocks, and sediments. The principal anthropogenic sources of nickel are fossil fuel combustion, nickel ore
mining, and the smelting, refining, and electroplating industries.
The median mainstem sediment nickel concentration was 26.9 ppm (Table 3.13a). The maximum value of 80 ppm
(Table 3.13aand Figure 3.lla) was found at MCB3.2 in segment three in 1984.
The biological significance of nickel concentrations in sediment are difficult to evaluate due to the low level of
confidence that can be placed in existing sediment quality guidelines. Long and Morgan (1990) placed onJy a
moderate level of confidence in their ER-L and ER-M guidelines for nickel, since the only data available to develop
the guidelines were from matching chemical and biological analyses performed on field samples from areas on the
West Coast MacDonald (1993) believed there were insufficient data available to develop NOEL and PEL
concentrations. Subsequent analyses of the data set used by MacDonald (1993) showed no evidence of increasing
incidence of toxicity with increasing sediment concentrations of nickel (Long, etal, 1995). Thus, current sediment
guidelines do not provide an adequate basis for evaluating the likelihood of toxic effects to aquatic organisms due
to sediment nickel concentrations.
There were some significant differences between annual mean measured and normalized sediment concentrations
of nickel. Where differences were found, concentrations in 1991 were lower than in preceding years (Table 3.13b).
Comparisons of 1991 sediment nickel concentrations with 1977 data (Helz, eta!., 1983) show only moderate
declines compared to those exhibited by some of the other trace metals (Figures 3.1 Ib-c).
I1U4
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Table 3.13b Temporal variability in nickel concentrations in mainstem Chesapeake Bay sediments. Means for years
not connected by the underline are significantly different (p<0.05) as determined by ANOVA followed by a Duncan
multiple range test. The means indicated by the year are ordered from high to low. NS = no significant differences.
There were insufficient data to perform the test for segments one and eight and the river mouth stations and Mobjack
Bay.
Region
Segment 2
Segment 3
Segment 4
Measured
NS
NS
84 85 91
Normalized
NS
NS
NS
Segment 5
Segment 7
Center
East
West
NS
NS
NS
UI-46
-------
Figure 3.11 a Nick©! concentrations (ppm)
in mainstem sediments
100
BO
eo
20
Measured
la. Mainstorn Segments
soo
•*oo
300
200
too
Silt-Clay Normalized
lt>. Mainstem Segments
1 I . , -.
seoi sees seca SEC* sees SEC? sees
TOO
BO
eo
20
Ha. Transects
SECl SEC2 SEG3 SEG* SEGS SEC 7 S£> ;B
IIt>. Transects
3OO
2OO
1 OO
WEST
too
ao
eo
20
CEMTER
Ilia. River IN/louths
EAST WEST
SOOi
4OO
3OO
aoo
1 OO
CENTER
lllt>. River Mouths
ST
I»OT
VORK
JAMES
POT
MBJK
JAM rs
Figure 3.11 a Summary statistics for measured and sitt-clay normalized sediment
concentrations of nickel in the Chesapeake Bay mainstem. The box and whisker pbts illustrate
the median (central horizontal line), the quartiles (extent of the rectangle), and ranges (extent
of vertical lines) of the data. If there are less than four values, the rectangle's bottom and top
show the range. A dash indicates only a single value is available. The stations are aggregated
by: I. Chesapeake Bay Program mainstem segments; II. transects across the midbay deep
trough; and 111. stations at the mouth of the Potomac, Rappahannock, York and James Rivers,
and in Mobjack Bay. The NOEL and PEL values for measured sediment nickel concentrations
are not available due to insufficient data (MacDonald, 1993).
111-47
-------
Figure 3.11b Measured Nickel Concentrations in Ma in stem Sediments
1977V,
80
1977
MCB3.J
MCB2 'i
MCB42 .-v./- -i
O MCB5J C67.1-5
Station
c
a
a.
Figure 3.7c WormalJiod Nickel Concentrations in Ma in stem Sediments
•5977v. 1991
120 -•
100 -•
0*H"-H
MCS1.1
C67/S
StCtOP
a
1991
Comparison of Nickel concentrations in mainstem sediments in 1977 and 1991 . Station designation refer to the
Chesapeake Bay Program monitoring stations. Data in 3.11 b are measured sediment cadmium concentrations while
the data in 3.1 1c are normalized, that is deivided, by the silt-clay fraction of the sediment samples.
IIM8
-------
-------
Zinc
Zinc is not on the Chesapeake Bay Toxics of Concern list but is a substance for which more information is being sou<
(Chesapeake Bay Program, 1991 a). Zinc is used in coatings to protect iron and steel, in brass, batteries, roofing and
exterior fittings for buildings, and in some printing processes. Zinc is a natural element found in soils and sediments.
Anthropogenic sources of zinc to aquatic ecosystems include industrial and municipal wastewater effluents, urban
stormwater, waste incineration, iron and steel production, and atmospheric emissions {MacDonald, 1993). Zinc is ofU
found at relatively high concentrations in urban stormwater (Olsenholler, 1991).
The median sediment zinc concentration in the mainstem Bay was 136 ppm (Table 3.14a). The maximum zinc
concentration of 495 ppm was found at MCB3.2 in segment three in 1985 (Table 3.14a and Figure 3.12a). The NOEL
concentration for zinc (68 ppm) was exceeded by the median sediment concentrations in segments 2 through 5, at
Mobjack Bay, and at all river mouth stations except the James River mouth (Table 3.14a and MacDonald, 1993).
Maximum sediment zinc concentrations above the NOEL concentration were found in all areas except segments 7 an<
8 (Table 3.14a and MacDonald, 1993). The PEL concentration (300 ppm) was exceeded by individual measurement.
only in segments two, three, four and five (Table 3.14a and MacDonald, 1993a). Toxic effects to aquatic organisms di
to measured sediment zinc concentrations may occur in portions of the middle mainstem Bay.
There were some significant differences between annual mean sediment concentrations of zinc. Where differences
were found, sediment zinc concentrations in 1991 were lower than in preceding years (Table 3.14b). The
concentrations of zinc observed in sediment samples collected from the mainstem in 1977 (Helz, era/., 1983) are
generally higher than those found in nearby locations in 1991, especially in the middle region of the mainstem Bay
(Figures 3.12b-c).
II-49
-------
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Table 3.14b Temporal variability in zinc concentrations in Chesapeake Bay mainstem sediments.
Means for years not connected by the underline are significantly different (p=0.05) as determined by
ANOVA followed by a Duncan multiple range test. The means indicated by the year are ordered from
high to low. NS = no significant differences. There were insufficient data to perform the test for
segments one and eight, the river mouth stations, and Mobjack Bay.
Area
Measured
Normalized
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Center
East
West
NS
NS
85 84 91
85 84 91
NS
NS
NS
84 85 91
NS
85 84 91
85~9? 84
85 84 91
NS
NS
NS
85 91
11-51
-------
Figure 3.12a Zinc concentrations (ppm)
in mainstem sediments
BOO
200
ISO
Measured
la. IvTainstern Segment©
200
BOO
eoo
.aoo
Silt-Clay Normalized
lt>. rv/I. Transeots
WEST
CEf-JTER
WEST
CENTER
eoo
•*so
300
ISO
Ilia. River Mouths
i 200
eoo
eoo
30O
Hlfc>. River Ivlouths
MB-IK
VORK JAMES
POT
MBJK
JAMES
Figure 3.12a Summary statistics for measured and sift-clay normalized sediment
concentrations of zinc in the Chesapeake Bay mainstem. The box and whisker plots illustra'e
the median (central horizontal line), the quartiles (extent of the rectangle), and ranges (exte -it
of vertical lines) of the data, tf there are less than four values, the rectangle's bottom and tc p
show the range. A dash indicates only a single value is available. The stations are aggregah .d
by: I. Chesapeake Bay Program mainstem segments; II. transects across the midbay de< -p
trough; and III. stations at the mouth of the Potomac, Rappahannock. York and James Rive s,
and in Mobjack Bay, The NOEL and PEL values for measured sediment zinc concentrations c re
68 ppm and 300 ppm, respectively (MacDonald, 1993).
1-52
-------
Figure 3.12b Measured Zinc Concentration* In Mamstem Sediments
1977v. 1991
1977
n
1991
MCil.l
MCB?.l
MC&0.2 MCB5-?
MC1HS.3 VCB4.2 VCH54
Stctop
15
Figure 3.12c Normalized Zinc Concentrations in Mainstem Sediments
1977 v. 1991
400 4
300 t
£ 200 4
100 t
MCB3.3 MCB12
VCB3 * VCH1 '
". -1 C:Rft
CH.MS
S-aflon
Comparison of Zinc concentrations in mainstem sediments in 1977 and 1991. Station designation refer to the
Chesapeake Bay Program monitoring stations. Data in 3.l2b are measured sediment cadmium concentrations while
the data in 3.12c are normalized, that is deivided, by the silt-clay fraction of the sediment samples.
II-53
-------
Ratio of Trace Metals to Acid-Volatile Sulfides
Under anaerobic (oxygen deficient) conditions in sediments, bacterial oxidation of organic carton
reduces dissolved sulfate (SO/*) to sulfide (HS") (Hennessee, et a/., 1986). The sulfide typically reacts
with iron and precipitates (Urban and Brezonik, 1993). The portion of this solid phase sulfide which can
be extracted from the sediment with cold hydrochloric acid is operationally defined as "acid-volatile"
sulfide or AVS (Leonard, etat., 1993). The divalent metals cadmium, copper, lead, mercury, nickel,
and zinc are thought to be able to displace iron and react with the sulfide, forming a sulfide precipitate
which is believed to be unavailable to biota (DiToro. etal.. 1992).
In order to evaluate the amount of divalent metal present in a potentially bioavailable form (i.e., not
bound to AVS), the sum of the molar concentrations of the divalent trace metals cadmium, copper,
lead, mercury, nickel and zinc is compared to the molar concentration of AVS. The amount of divalent
metal present in excess of the amount of AVS is thought to be bioavailabfe. The remaining portion of
divalent metal is presumed to be bound to the sulfide and unavailable to the biota. The concentration
of AVS in the sediment has been shown to influence the toxicity and/or bioavailability of cadmium,
nickel, lead and copper (DiToro, etal., 1990; Ankley. et a/., 1991; Bourgoin, etal., 1991; Carlson, etal.,
1991; DiToro, etal., 1992; Ankley. et. a/. 1993; and Casas and Crecelius, 1994).
The metal-AVS relationship is properly examined as the ratio of the sum of the molar concentrations of
the simultaneously extracted divalent trace metals (SEM) to the molar concentration of AVS.
Simultaneously extracted metals (SEM) is the concentration of metals measured when the sediment
sample is treated with a weak hydrochloric acid solution i.e., 1 molar, in order to volatilize sulfide during
the measurement of sediment AVS. Analysis for SEM had not been performed as part of the mainstem
monitoring program during the period covered by this report. As a first approximation to the results of
such analyses, the results of the strong acid digestion used by the monitoring program in measuring
metals, i.e., " total recoverable" metals, were substituted for SEM. Since metals may be more
thoroughly extracted by the "tola! recoverable" procedure, this procedure may overestimate SEM, and
thus overestimate the bioavailabilrty of divalent trace metals in these samples.
There is another reason why the metal-AVS data presented below may overestimate bioavaiiabilrty of
the divalent trace metals in mainstem sediments. In oxic sediments where AVS concentrations are very
low (i.e., less than 0.1 uM) other constituents of the sediment may act as the principal partitioning phase
for divalent metals and prevent their uptake by biota (Di Toro, et a/., 1990; Ankley, etal., 1993). In
addition, for at least one divalent metal (copper), the sediment concentration of AVS has not been
found to account for the full binding capacity of the sediment for metal, and organic carbon may act as
an important additional source of sediment binding capacity even in the presence of significant
quantities of AVS (Ankley, etal., 1993 and Casas and Crecelius, 1994). Thus, the sediment divalent
trace metal:AVS ratios presented below will indicate only when divalent trace metals are not
bioavailable due to binding with AVS. If the data shows sediment divalent trace metal AVS ratio is
greater than one, indicating that there is divalent metal present in excess of the quantity of AVS
available to bind with it, then one can conclude that a portion of the divalent metals in the sediment ts
potentially bioavailable, but a definitive determination of divalent trace metal bioavailability cannot be
made in these instances.
The determination of trace metal and AVS concentrations in mainstem samples from the Maryland and
.Virginia portion of the mainstem were conducted by two different laboratories. However, the two
laboratories used the same analytical methods to measure both trace metal and acid volatile sulfide
concentrations in the sediment samples (see Chapter 2 for details on analytical methods). However,
the detection limit for sediment AVS concentrations was higher in the Maryland samples than in the
Virginia samples (Table 3.15).
Sediment concentrations of AVS were less than 3.13 uM in segment one, two, and the upper portion of
segment three (Table 3.15). Much higher sediment AVS concentrations were observed in the middle
-------
mainstem Bay in the lower portion of segment three and segment four (Table 3.15 and Table 3.16).
Sediment AVS concentrations decreased towards the mouth of the Bay below the middle mainstem,
and the sediment AVS concentration in segment eight at the mouth of the Bay was less than 0.06 pM
(Table 3.15 and Table 3.16). In the region of the middle mainstem Bay encompassing the central deep
trough, sediment samples from stations to the west of the central deep trough had lower sediment AVS
concentrations on average than those stations located within the trough and those east of the trough
(Table 3.16). Sediment AVS concentrations ranged from 1.38 uM to 13.0 uM among the river mouth
stations and the station at Mobjack Bay (Table 3.15 and Table 3.16).
With the exception of the station at CB8.1 at the mouth of the Bay, divalent trace metaLAVS ratios were
less than one (the ratio above which divalent metals are presumed to be bioavailable) at all of the
stations located below station MCB3.2 in the upper portion of the middle mainstem Bay. This indicates
divalent trace metals in the sediment are bound to sulfide in this region of the mainstem, and thus are
not bioavailable. In the upper portion of.the Bay from the mouth of the Susquehanna River through the
upper portion of segment three in the middle mainstem Bay, only minimum divalent trace metal AVS
ratios could be determined, as sediment AVS concentrations in the sediment samples from this region
were below detection limits. However, these minimum divalent trace metal:AVS ratios approached or
exceeded one, indicating that divalent trace metals in the sediments in this portion of the mainstem are
potentially bioavailable.
Trace metal concentrations in the sediment are most likely to cause toxic effects to aquatic organisms
when the sediment divalent trace metal:AVS ratio is greater than one and the sediment concentration
of divalent trace metals is high. Sediment trace metal concentrations at sampling stations in segment
two and the upper portion of segment three are high relative to those located elsewhere in the
Chesapeake Bay mainstem. In addition, sediment trace metal:AVS ratios in this region are greater than
one, indicating that a portion of the trace metals in these sediments are not bound to sulfide. Thus, the
potential bioavailability of sediment trace metals are of concern in this region of the mainstem. The
western portion of the middle mainstem Bay (segments three and four) also have relatively high
divalent trace metal concentrations in the sediment. However, there is sufficient AVS present in the
sediments in this region to bind the metal and render it unavailable to biota, and thus sediment trace
metal concentrations in this region are not of concern. The sediment AVS concentration was less than
the very low detection limit in segment eight, indicating that the divalent trace metals in these areas are
not bound by sulfide, and thus potentially bioavailable. However, as concentrations of divalent trace
metals in the sediment in this area are low, the bioavailability of divalent trace metals is not of concern
in this area, despite the low concentrations of sediment AVS.
The measurements of AVS presented here provide a "snapshot" of sediment AVS concentrations.
However, AVS concentrations in both freshwater and estuarine sediments can vary substantially
between seasons pi Toro, etat., 1990; Zarba, 1991; Leonard, etal.. 1993 and Urban and Brezonik,
1993). Sediment sulfide concentrations are typically highest in midsummer when temperature and
sediment concentrations of organic carbon are high, creating optimal conditions for the microbial
activity which produces sulfide (Leonard, et al., 1993). A recent study in the m.ddie mainstem Bay
showed that sediment AVS concentrations reached their highest levels
-------
provide measurements of sediment AVS concentrations for a time period when metal contaminants
could potentially have a large adverse impact on benthic communities, it is possible that ongoing and
planned reductions in nutrient inputs to the Bay will decrease the supply of organic carbon to the
sediments in the mainstem Bay, and this, in turn, may reduce the concentration of AVS in the
sediments in the middle and lower portions of the Bay, since AVS formation in this region is thought to
be limited by the availability of organic carbon (Hennessee. et a/., 1986}.
II-56
-------
Table 3.15 Molar concentrations of the sum of divalent metals, acid volatile sulfide (AVS) and, the
divalent trace metal:AVS ratio in Chesapeake Bay mainstem sediments. Molar concentrations are in
micromoles per gram sediment. Divalent trace metals include cadmium, copper, mercury, nickel, lead,
and zinc. Data are from 1991 only. Metal concentrations were determined by EPA's total recoverable
method, rather than as simultaneously extracted metals (SEM). Therefore, the SEM:AVS ratio and the
sum of divalent metals are probably overestimated, but should provide a relative indicator of potential
metal bioavaliability. SUM = sum of molar concentrations of the six divalent metals; AVS=molar
concentration of AVS; RATIO=ratio of SUM to AVS.
Station
MCB1.1
MCB2.1
MCB2.2
MCB3.1
MCB3.2
MCB3.3C
MCB3.3E
MCB3.3W
MCB4.1C
MCB4.1E
MCB4.1W
MCB4.2C
MCB4.2E
MCB4.2W
MCB4.3C
MCB4.3E
MCB4.3W
MCB4.4
MCB5.1
MCB5.2
MCB5.3
CB5.4
CB7.1S
CB7.3E
CB8.1E
MLE2.3
LE3.6
WE4.2
WE4.1
LE5.5
Region
Segment 1
Segment 2
Segment 2
Segment 3
Segment 3
Segment 3
Segment 3
Segment 3
Segment 4
Segment 4
Segment 4
Segment 4
Segment 4
Segment 4
Segment 4
Segment 4
Segment 4
Segment 4
Segment 5
Segment 5
Segment 5
Segment 5
Segment 7
Segment 7
Segment 8
Potomac River Mouth
Rappahann'ock R. mouth
Mobjack Bay
York River mouth
James River mouth
SUM
2.97
4.25
5.42
4.71
4.60
3.47
3.21
4.30
2.43
1.77
4.66
2.37
2.33
4.15
1.79
2.35
4.23
2.22
2.07
1.43
1.30
0.98
1.07
0.85
0.52*
2.43
2.30
1.81
2.06
0.232
AVS
<3.13'
<3.13'
<3.13'
<3.13'
<3.13'
30.42
15.42
6.81
20.72
41.56
9.89
24.9
12.06
23.20
9.19
31.96
19.32
43.70
28.14
11.31
6.45
3.56
1.49
1.63
<0.063
13.00
11.97
2.49
10.56
1.38
RATIO
>0.95'
>1.361
>1 .731
>1.5V
>1.47'
0.11
0.21
0.63
0.12
0.04
0.47
0.10
0.19
0.18
0.19
0.07
0.22
0.05
0.07
0.13
0.20
0.28
0.72
0.52
*
0.19
0.84
0.73
0.-19
0.16
Sediment AVS concentrations were below the detection limit of 100 ppm for samples from the Upper portion of the Maryland
mainstem. Values for AVS and RATIO listed are those obtained with AVS set to equal the detection limit.
Sediment cadmium concentrations below the detection limit were set to equal the detection limit to calculate the sum of divalent
metals.
Sediment AVS concentration below the lowest detection limit (2 ppm) for samples from the Virginia portion of the mainstem.
Values for AVS listed is that obtained with AVS set to equal the detection limit.
METAUAVS ratio not calculated, as the AVS concentration was below the lower limit of applicability of AVS normalization,
approximately 1 pM/g (OiToro, era/.. 1990)
Sediment AVS concentration below the lowest detection limit (2 ppm) for samples from the Virginia portion of the mainstem.
Values for AVS listed is that obtained with AVS set to equal the detection limit.
METAUAVS ratio not calculated, as the AVS concentration was below the lower limit of applicability of AVS normalization.
approximately 1 uM/g (DiToro. ef al.. 1990)
III-57
-------
Table 3.16 Average molar concentrations of divalent metals, AVS. and the divalent metalAVS ratio in
Chesapeake Bay mainstem segments. Concentrations are in micromoles per gram sediment.
Divalent metals include cadmium, copper, mercury, nickel, lead, and zinp. Metal concentrations were
determined by the total recoverable method, rather than as simultaneously extracted metals (SEM).
Therefore, the metal AVS ratio and the sum of divalent metals are probably overestimated, but should
provide a relative indicator of potential meta! bioavariability. All data are from 1991.
Number of
observations
Segment 1
Segment 2
Segment 3
Segment 4
Segment 5
Segment 7
Segment 8
Center Midbay
East Midbay
West Midbay
Potomac River Mouth
Rapp. R. mouth
Mobjack Bay
York River mouth
James River mouth
1
2
5
10
3
2
1
4
4
4
1
1
1
1
1
Sum of
divalent metals
2.97
4.83
4.06
2.83
1.44
0.96
0.522
2.52
2.42
4.33
2.43
2.30
1.81
2.06
0.23'
Average metal:Segment
AVS AVS ratio
<3.132
<3.132
11. 78*
23.62
12.37
1.56
<0.063
21.31
25.25
14.81
13.00 .
11.97
2.49
2.42
1.38
>0.952
>1.552
0.792
0.16
0.17
0.62
*
0.13
0.13
0.38
0.19
0.19
0.73
0.85
0.16
1 Sediment AVS concentrations were below the detection limit of 100 ppm for some samples from the
Maryland portion of the mainstem. Values for AVS and RATIO listed are those obtained with AVS
set to equal the detection limit.
2 Sediment cadmium concentrations below the detection limit were set to equal the detection limit to
calculate the sum of divalent metals.
3 Sediment AVS concentration was below the lowest detection limit (2 ppm) for samples from the
Virginia portion of the mainstem. Value for AVS listed is that obtained with AVS set to equal the
detection limit.
* METAL7AVS ratio not calculated, as the AVS concentration was below the lower limit of applicability
of AVS normalization, approximately 1 uM/g (DiToro, etal., 1990)
lli-58
-------
Spatial Distribution of Individual Polycyclic Aromatic Hydrocarbons
Total Polycyclic Aromatic Hydrocarbons (TOTAL PAHs)
Total PAHs is not listed as a Chesapeake Bay Toxic of Concern. Total PAHs data are
available from the monitoring program for 1991 only {Table 3.17 and Figure 3.13). The
median sediment concentration of total PAHs in the mainstem Bay was 1,524 ppm. The
maximum value of 14,854 ppb was found at station MCB2.2 in segment two in 1991. The
NOEL and PEL guidelines for total PAHs are based on the sum of thirteen specific
compounds (MacDonald, 1993), while the monitoring program data includes all PAHs
detected (Unger; personal communication).
Median concentrations in segments two and three and at the mouth of the Potomac exceed
the NOEL for total PAHs of 2,900 ppb, but all measurements are significantly less than the
PEL of 28,000 ppb (Table 3.17 and MacDonald, 1993). Toxic effects to aquatic biota due to
the measured concentrations of total PAHs in the sediments are not likely at the mainstem
Bay stations sampled.
III-59
-------
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Figure 3.13 Total PAHs concentrations (ppb)
in mainstem sediments
2OOOO
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Figure 3.13 Summary statistics for measured and total organic carbon normalized sediment
concentrations of total PAHs in the Chesapeake Bay mainstem. The box and whisker plots
illustrate the median (central horizontal line), the quamies (extent of the rectangle), and ranges
(extent of vertical lines) of the data. If there are less tnan four values, the rectangle's bottom
and top represent the range. A dash indicates only a single value is available. Stations are
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mouth of the Ftrtomac, Rappahannock, York and James Rivers, and in Mobjack Bay. The NOEL
and PEL values for measured sediment total PAHs concentrations are 2900 ppb and 28000
ppb, respectively (MacDonald, 1993).
111-61
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Figure 3.14 Summa^ statistics for measured and total organic carbon normalized sediment
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Figure 3.15 Summary statistics for measured and total organic carbon normalized sediment
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1-65
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Figure 3.16 Summafy statistics for measured and total organic carbon normalized sediment
concentrations of benzo(g,rxi)perylene in the Chesapeake Bay mainstem. The box and
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I!, stations at the mouth of the Potomac, Rappahannock. Yorv a.-x: James Rivers, and in
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Figure 3.17 Benzo(a)pyrene concentrations (ppb)
in mainstem sediments
32O
2»O
ao
Measured
la. Ivlalristem Segments
§
TOC Normalized
It>. Ivlaiinstem Segments
seci seca sees SEC* sees SCOT SECO SECY sec2 seoa SEO* sees SECT SECS
32O
2*0
BO
8O
11 a. River Mouths
I Its. River IS/louths
F»OT
f»OT
VORK OA.MCS
Figure 3.17 Summary statistics for measured and total organic carbon normalized sediment
concentrations of benzo{a)pyrene in the Chesapeake Bay mainstem. The box and whisker
plots illustrate the median (central horizontal line), the quartites (extent of the rectangle), and
ranges (extent of vertical lines) of the data. If there are less than four values, the rectangle's
bottom and top represent the range. A dash indicates only a single value is available.
Stations are aggregated by: I. Chesapeake Bay Program mainstem segments; and 'II. stations
at the mouth of the Potomac, Rappahannoclc York and James Rivers, and in Mobjack Bay. The
NOEL and PEL values for measured sediment benzofajpyrene concentrations are 230 ppb and
1700 ppb, respectivety (MacDonald, 1993).
111-69
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1 James
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Figure 3.18 Ghrysene concentrations (ppb)
in mainstem sediments
too
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300
1OO
Measured
la. Malnstern Segments
i e
1 3
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& a
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llo. Mainstern Segments
scc2 seca see* sees seo7 scce SEGI SEGZ sees sec* sees seer
300
200
100
Ma. Ftiver Mouths
1 3
llo. River Mouths
f»OT
VORK JAMES
"VORK .JA.MCS
Figure 3.18 Summary statistics for measured and total organic carbon normalized sediment
concentrations of chrysene in the Chesapeake Bay mainstem. The box and whisker plots
illustrate the median (central horizontal line), the quartiles (extent of the rectangle), and ranges
(extent of vertical lines) of the data. If there are less than four values, the rectangle's bottom
and top represent the range. A dash indicates only a single value is available. Stations are
aggregated by: I. Chesapeake Bay Program mainstem segments; and II. stations at the
mouth of the Potomac, Rappahannock, York and James Rivers, and in Mobjack Bay. The NOEL
and PEL values for measured sediment chrysene concentrations are 220 ppb and 1700 ppb,
respectively (MacDonald, 1993).
111-71
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Figure 3.19 Diben2o. Ivlainstem Segments
_ : O.oJ ... .,_
o- 'SCC1 SEC2 SEC 3 SCG« SECS SECT SECa SEC 1 SEG2 SEG3 SEC* SEGS SEG7 SECQ
v*
2O
Ha- River Mouths
o.o
lo.e
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o.ol
lib. River
VORK
Figure 3.19 Summary statistics for measured and total organic carbon normalized sediment
concentrations of dibenzo{a,h)anthracene in the Chesapeake Bay mainstem. The box and
whisker plots illustrate the median (central horizontal line), the quartiles (extent of the rectangle),
and ranges (extent of vertical lines) of the data. If there are less than four values, the
rectangle's bottom and top represent the range. A dash indicates only a single value is
available. Stations are aggregated by: I. Chesapeake Bay Program mainstem segments; and
II. stations at the mouth of the Potomac, Rapponannock, York and James Rivers, and in
Mobjack Bay. The NOEL and PEL values for measured sediment dibenzo(a,h)anthracene
concentrations are 31 ppb and 320 ppb, respectively (MacDonald, 1993).
Ml-73
-------
Fluoranthene
Fluoranthene, a high molecular weight PAH among the Chesapeake Bay Toxics of Concern, is
currently being reviewed by EPA for carcinogenicity (Chesapeake Bay Program, 1991a, 199lb).
Fluoranthene is produced by the high temperature combustion of coal and petroleum, and is
ubiquitous in the environment (Environmental Protection Agency, 1993d). The median concentration
of fluoranthene in mainstem Bay sediments was 52 ppb (Table 3.24). The maximum value of 472
ppb was found at station MCB3.2 in segment three in 1984 (Table 3.24 and Figure 3.20).
The NOEL and PEL concentrations for fluoranthene are 380 and 3200 ppb, respectively
(MacDonald, 1993). Median fluoranthene concentrations in all segments and at all river mouth
stations were less than the NOEL concentration of 380 ppb (Table 3.24 and MacDonald, 1993).
Only the maximum sediment fluoranthene concentrations measured in segments two and three and the
James River exceeded the NOEL concentration. No measurements exceeded the PEL concentration
(Table 3.24 and MacDonald, 1993). Toxic effects to aquatic biota due to the measured
concentrations of fluoranthene in mainstem Bay sediments are not likely at the sampled locations.
11-74
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Figure 3.2O Fluoranthene concentrations (ppb)
in rnainstem sediments
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ao
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eoo
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so
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-VORK
cs
Figure 3.20 Summary statistics for measured and total organic carbon normalized sediment
concentrations of fluoranthene in the Chesapeake Bay mainstem. The box and whisker plots
illustrate the median (central horizontal line), the quartiles (extent of the rectangle), and ranges
(extent of vertical lines) of the data. If there are less than four values, the rectangle's bottom
and top represent the range. A dash indicates only a single value is available. Stations are
aggregated by: I. Chesapeake Bay Program mainstem segments; and II. stations at the
mouth of the Potomac, Rappahannock, York and James Rivers, and in Mobjack Bay. The NOEL
and PEL values for measured sediment fluoranthene concentrations are 380 ppb and 3200
ppb, respectively (MacDonald, 1993).
111-76
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Figure 3.21 Indeno(1,2,3-cd)pyrene concentrations (ppo)
in mainstem sediments
3SO
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Measured
la.. IVla.lnst®rn Segments
e.o
8 3.1
1.S
o.o
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lt>. IS/lalnstom Segments
seci secs seca SEC-* sees sec7 seca SEO-I seoa sees sec* sees SCOT seca
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aoo
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100
so
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e.o
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o.o
lib. River
>OT R
VORK JA ««ES
Figure 3.21 Summaiy statistics for measured and total organb carbon normalized sedimen'
concentrations of indeno(l ,2,3-cd)pyrene in the Chesapeake Boy mainstem. The box anc
whisker plots illustrate the median (central horizontal line), the quartiles (extent of the rectangle),
and ranges (extent of vertical lines} of the data. If there are less than four values, the
rectangle's bottom and top represent the range. A dash indicates only a single value is
available. Stations are aggregated by: I. Chesapeake Bay Program mainstem segments; anc
II. stations at the mouth of the Potomac, Rappahannock. York and James Rivers, and ir
Mobjack Bay. The NOEL and PEL values for measured sediment indeno(1 ,2,3-cd)pyrene
concentrations are not available due to insufficient data (MacDonald, 1993),
ill-78
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Figure 3.22 Summary statistics for measured and total organic carbon normalized sediment
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mouth of the Potomac, Rappahannock, York and James Rivers, and in Mobjack Bay. The NOEL
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Figure 3.23 Perylene concentrations (ppb)
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BOO
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SEC1 SEC2 SEGJ SEC* SCG» SCG7 SEOO SC01 SEC2 SCC3 SEC* SEOS SECT SE 5O
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Figure 3.23 Summary statistics for measured and total organic carbon normalized sediment
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and top represent the range. A dash indicates only a single value is available. Stations are
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mouth of the Potomac, Rappahannock. York and James Rivers, and in Mobjack Bay. The NOEL
and PEL values for measured sediment perylene concentrations a-e not available due to
insufficient data (MacDonald, 1993).
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Figure 3.24 Summary statistics for measured and total organic carbon normalized sediment
concentrations of phenanthrene in 1he Chesapeake Bay mainstem. The box and whisker plots
illustrate the median (central horizontal line), the quartiies (extent of the rectangle), and ranges
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and top represent the range. A dash indicates only a single value is available. Stations are
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mouth of the Potomac, Rappanannock, York and James Rivers, and in Mobjack Bay. The NOEL
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Figure 3.2S Pyrene concentrations (ppb)
in mainstem sediments
eoo
soo
tao
Measured
la. MeUnstem Segments
«*o
30
§
& ao
10
TOC Normalized
lt>. Is/Ialnstem Segments
SCG1 SCG2 SEC3 SEC* SEOS SEO7 SECO SEOI SEC2 SEC3 SEC<« SECS SEO7 SE C8
eoo
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list. River IVIouthts
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ICS
Figure 3.25 Summary statistics for measured and total organic carbon normalized sediment
concentrations of pyrene in the Chesapeake Bay mainstem. Tne box and whisker plots
illustrate the median (central horizontal line), the quartiles (extent of the rectangle), and ranges
(extent of vertical lines) of the data. If there are less than four values, the rectangle's bottom
and top represent the range. A dash indicates only a single value is available. Stations are
aggregated by: I. Chesapeake Boy Program mainstem segments; and 11. stations at the
mouth of the Potomac, Rappahannock. York and James Rivers, and in Mobjack Bay. The NOEL
and PEL values for measured sediment pyrene concentrations are 290 ppb and 1800 ppb,
respectrvery (MacDonald, 1993).
111-87
-------
Spatial Distribution of Individual Chlorinated Hydrocarbons
DDT and its metabolites and various PCB congeners were widely detected in mainstem Bay sediments
(Table 3.30). However, most other chlorinated hydrocarbon compounds detected in the mainstem Bay
were found at only a few stations (Table 3.30). Thus, individual tables of summary statistics are presented
only for DDT and PCBs. Information is presented on the frequency of detection and range of measured
concentrations for each chlorinated hydrocarbon detected in mainstem sediments. The compounds found
at each mainstem station are also listed by station in Table 3.31.
Table 3.30 Frequency of detection and range of observed concentrations of pesticides, PCB congeners,
and other chlorinated organic compounds detected in mainstem Chesapeake Bay sediments in 1991.
Units are parts per billion (ppb), dry weight. The total number of stations sampled was 16. The nominal
detection limit for all compounds was 0.01 ppb.
Compound
Frequency
Min.(ppb) Max.(ppb)
2,2>,3,5',6 pentachlorobiphenyl (PCB-95)
2.2',3,4.4',5' hexachlorobiphenyl (PC8-138)
2,2',4.4',5.5' hexachlorobiphenyl (PCB-153)
2,2',3v4,4',5,5' heptachlorobiphenyl (PCB-180)
2,2',314',5,5',6 heptachlorobiphenyl (PCB-187)
2,2',3,4>,5 pentachlorobiphenyl/
2,2'.4,5,5' pentachlorobiphenyl (PCB-90/101)
2,3',4,4',5 pentachlorobiphenyl/
2,2',3,4',5',6 hexachlorobiphenyl (PCB-118/149)
2,2',3,3',4,4',5 heptachlorobiphenyl/
2,3,31,4,4>,5,6 heptachlorobiphenyl (PCB-170/190)
9
12
8
9
8
10
11
6
0.04
0.02
0.12
0.01
0.06
0.03
0.13
0.01
1.12
1.64
2.32
0.82
0.50
1.10
2.34
0.19
4-4'-DDD
4-4'-DDE
4-4-DDT
trans-Nonachlor
cis-Nonachlor
Chlordane(l)
Chlordane(S)
Chlordane(S)
Chlordane(7)
cis-Chlordane
trans-Chlordane
Dicofol
Dieldrin
Octochlorodibenzo-p-dioxin (OCDD)
12
14
10
4
1
1
1
2
4
2
1
4
2
13
0.04
0.02
0.10
0.06
0.20
0.45
0.14
0.10
0.08
0.72
0.15
0.12
0.27
0.01
2.10
2.30
1.60
0.25
0.20
0.45
0.14
0.16
0.23
0.75
0.15
0.32
0.31
2.67
Source: PCB congeners number equivalent from McFarland. V.A. and J.U. Clarke, 1989.
HI-88
-------
Table 3.31 Pesticides, PCB congeners, and other chlorinated organic compounds detected at each
Chesapeake Bay mainstem station sampled for organic chemical contaminants in 1991.
Location
Compound
Concentration (ppb)
Segment 1
MCB1.1
Segment 2
MCB2.1
MCB2.2
Segment 3
MCB3.1
PCB-95
PCB-90/101
PCB-118/149
PCB-153
PCB-138
PCB-187
PCB-180
PCB-170/190
trans-Nonachlor
PCB-95
PCB-90/101
PCB-118/149
PCB-153
PCB-138
PCB-187
PCB-180
Chlordane(S)
PCB-95
PCB-90/101
PCB-118/149
PCB-138
PCB-187
PCB-180
PCB-170/190
Chlordane{7)
PCB-95
PCB 90/101
PCB-118/149
PCB-153
PCB-138
PCB-187
PCB-180
PCB-170/190
4~4'-DDD
4-4'-DDE
4-4-DDT
Dicofol
OCDD
0.11
0.16
0.89
1.24
1.25
0.22
0.82
0.19
0.17
0.41
0.35
1.29
1.42
0.61
0.16
0.32
0.10
0.84
0.70
1.64
1.45
0.26
0.78
0.09
0.12
0.43
0.28
1.41
1.79
1.63
0.22
0.56
0.11
1.95
1.55
1.30
0.32
0.20
III-89
-------
Table 3.31 (continued)
Location
MCB3.2
MCB3.2
MCB3.3C
Segment 4
MCB4.1C
Compound
PCB-95
PCB-90/101
PCB-118/149
PCB-153
PCB-138
PCS- 187
PCB-180
PCB-170/190
4^l'-DDD
4-4'-DDE
4-4-DDT
Dicofol
OCDD
PCB-95
PCB-90/101
PCB-118/149
PCB-153
PCB-138
PCB-187
PCB-180
PCB-170/190
4^-DDD
4-4--DDE
4-4-DDT
trans-Nonachlor
cis-Nonachlor
Chlordane(l)
Chlordane(3)
Chlordane{5)
Chlordane(7)
cis-Chlordane
trans-Chlordane
Dicofol
Dieldrin
OCDD
PCB-90/101
PCB-118/149
PCB-153
PCB-138
4-4-DDD
4-4-DDE
OCDD
Concentration (ppb)
0.71
0.61
1.60
1.75
1.52
0.14
0.45
0.02
1.70
1.20
0.50
0.17
1.04
1.03
2.28
2.28
1.41
0.49
0.57
0.18
1.70
2.30
0.35
0.24
0.20
0.45
0.14
0.16
0.20
0.73
0.15
0.12
0.29
0.53
0.09
0.24
0.12
0.02
0.10
0.10
0.73
MCB4.3C
OCDD
2.67
iu-90
-------
Table 3.31 (continued)
Location
Compound
Concentration (ppb)
Segment 5
CB5.1
CB5.4
Segment 7
CB7.3E
CB7.1S
Segment 8
PCB-138
OCDD
4-4--DDE
OCDD
0.03
0.63
0.02
0.33
CB8.1E
Potomac River Mouth
MLE2.3
Rappahannock River Mouth
LE3.6
PCB-118/149
PCB-138
OCDD
PCB-95
PCB-90/101
PCB-118/149
PCB-138
PCB-187
PCB-180
4-4'-DDD
4-4-DDE
4-4--DDT
OCDD
PCB-95
PCB-90/101
PCB-118/149
PCB-153
PCB-138
4-4'-DDD
4-4-DDE
OCDD
0.13
0.01
0.02
0.66
0.40
1.05
1.50
0.09
0.03
0.70
1.00
0.90
2.14
0.04
0.03
0.10
0.02
0.03
0.04
0.03
0.46
Mobiack Bav
111-91
-------
WE4.1
James River Mouth
LE5.5
York River Mouth
WE4.2
4-4'-DDE
OCDD
PCB-95
PCB-90/101
PCB-118/149
PCB-153
PCB-138
PCB-187
PC B- 180
PCB-170/190
4-4-DDE
4-4-DDT
OCDD
0.60
0.82
0.10
0.10
0.25
0.33
0.43
0.06
0.04
0.01
0.30
0.10
0.80
0.49
III-92
-------
Total Polychlorinated Biphenyls
Polychlorinated biphenyls (PCBs) are a class of organic compounds containing two linked hydrocarbon
rings with various numbers of chlorine atoms, usually from two to nine. PCBs are extremely persistent
anthropogenic compounds that have been widely used in electrical transformers. The U.S. banned
production of PCBs in the late 1970s, but poor operating and disposal practices involving products and
equipment containing PCBs still lead to environmental contamination (Latimer et. at. 1990). Surveys such
as the EPA Mussel Watch Program, and the NOAA National Status and Trends Program show no clear
evidence of a large-scale, nationwide decrease in the concentration of these compounds in aquatic
environments (Kennish et. el. 1992).
Total PCBs is on the list of Chesapeake Bay Toxics of Concern (Chesapeake Bay Program, 1991 a). The
EPA considers PCBs probable human carcinogens, although there is conflicting evidence regarding
cartinogenicrty (Chesapeake Bay Program, 1991 b). PCBs can pose both acute toxic effects to estuarine
organisms and are also known to produce chronic, sublethal effects such as reproductive deficiencies
(Kennish. et. al, 1992). PCBs are also of concern because they have considerable potential to accumulate
in the tissues of aquatic organisms (MacDonald, 1993).
PCBs, like PAHs, are a variable mixture of compounds. In the method used in 1991 to monitor sediment
contaminants in the mainstem of Chesapeake Bay, the quantity of total PCBs present was estimated based
on the assumption that a suite of eight of the PCB congeners that were quantified accounted for 44.9% of
total PCBs. This assumption was based on analysis of a mixture of Aroclor 1254 and 1260 (commercial
mixtures of PCBs) which most closely matched the patterns of congener abundance observed in the
sediment samples (Unger, era/., 1992).
The concentrations of total PCBs were much higher in the upper Bay (segments one, two, and three) than
in the lower Bay (segments four through eight) (Table 3.32 and Figure 3.26). The median mainstem Bay
concentration was 7.6 ppb. The maximum value of 15.5 ppb was found at station MCB3.3C in segment
three. Even the maximum measured concentration does not exceed the PEL concentration of 260 ppb or
the NOEL concentration of 24 ppb (MacDonald, 1993). Toxic effects to aquatic biota are not likely to result
from the measured sediment concentrations of PCBs measured at the monitored stations in the mainstem
Bay.
1-93
-------
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Figure 3.26 Total PCBs concentrations (ppfc>)
in mainstem sediments
10
Measured
la. Mainstem Segments
o.e
§
o.a
o.o
TOC Normalized
Ito. ivIaJnstem Segments
SCC1 SCC2 SE03 SEC-* SETGS SCO? SECB SEO1 SEC2 SCC9 SCC« SECS SCOT ! SEOI
20 o.e
I la. River IS/louths
§
O.2
O.O
Ht>. River N/loutn;
VORK
-I S.MCS
Figure 3.26 Summaiy statistics for measured and total organic carbon normalized sedimer?
concentrations of total PCBs in the Chesapeake Bay mainstem. The box and whisker plot;
illustrate the median (central horizontal line), the quartiles (extent of the rectangle), and range»
(extent of vertical lines) of the data. If there are less than four vaiies. the rectangle's botton i
and top represent the range. A dash indicates only a single value is available. Stations art >
aggregated by: I. Chesapeake Bay Program mainstem segmenTs. and II. stations at th?
mouth of the Potomac, Rappahannock. York and James Rivers, ana r. f.'obpck Bay. Ihe NOE.
and PEL values for measured sediment total PCBs concentration: ere 2-: ppb and 260 ppl:,
respectively (MacDonald, 1993).
H-95
-------
DDT and its metabolites
DDT «s a broad spectrum organochlorine insecticide which was previously used extensively in agricultural
applications, although it is no longer registered for use in North America (MacDonald, 1993). DDT is still of
concern because residues of DDT and its metabolites (DDE and ODD) are highly toxic and persistent in the
environment and have a high potential to bioaccumulate. DDT has not been identified as a Chesapeake
Bay Toxic of Concern (Chesapeake Bay Program, 1991 a).
The highest sediment concentrations of DDT. DDE, and DDD were found at the mouth of the York River
(Table 3.33). Elsewhere within the mainstem Bay, concentrations were generally the highest in segment
three in the middle mainstem Bay and declined towards the mouth of the Bay. Sediment DDT
concentrations were below detection limits in most of the lower mainstem Bay.
MacDonald (1993) lists NOEL and PEL values of 1.7 ppb and 130 ppb for DDE, and 4.5 ppb and 270 ppb
for total DDT. MacDonald (1993) determined that there were insufficient data for the determination of
NOEL and PEL values for DDE and DDT. Long and Morgan (1990) provide ER-L and ER-M values of 2
ppb and 20 ppb for DDD and 1 ppb and 7 ppb for DDT. Comparison of the data with these sediment
quality guidelines indicate that the measured sediment concentrations of DDT and its metabolites were
generally below their respective ER-L or NOEL values, although these values were sometimes slighly
exceeded in segments two through four (Table 3.33). All measured concentrations were well below ER-M
and PEL guidelines (Table 3.33). The measured concentrations of DDT are overestimates, as there was
interference from PCB and chlordane congeners in measuring the concentration of p-DDT (Unger, etal.,
1992). Toxic effects to aquatic biota due to the measured concentrations of DDT in sediment are not likely
at the monitored stations in the mainstem Bay.
Aldrin/Dieldrin
Aldrin is an organochlorine pesticide previously used to control a broad spectrum of pests in both domestic
and agricultural applications (MacDonald. 1993). Aldrin is quickly biotransformed into dieldrin in aquatic
ecosystems (MacDonald, 1993). Dieldrin was formerly one of the more widely used domestic pesticides,
but, like aldrin, its use is currently restricted (MacDonald. 1993). Both aldrin and dieldrin are listed with a
secondary group of toxic substances under consideration for inclusion on the Chesapeake Bay Toxics of
Concern List (Chesapeake Bay Program, 1991 a).
Dieldrin was only detected at one station. MCB3.3C in the central trough in the middle mainstem Bay, at a
concentration of 0.29 ppb (Table 3.31). MacDonald (1993) felt there were insufficient data to use in
developing NOEL and PEL concentrations for dieldrin. and Long and Morgan (1990) placed a low level of
confidence in their ER-L and ER-M values of 0.002 ppb and 8 ppb, respectively. The measured dieldrin
concentration is well below the ER-M concentration, but above the ER-L concentration. Toxic effects due to
the measured dieldrin concentrations in sediments are unlikely at the mainstem Bay stations sampled.
III-96
-------
Table 3.33 Concentrations of DOT, ODD, and DDE in Chesapeake Bay mainstem sediments.
Concentrations are in ppb dry weight.
Station
MCB1.1
MCB2.1
MCB2.2
MCB3.1
MCB3.2
MCB3.3C
MCB4.1C
MCB4.3C
MCB5.1
CB5.4
CB7.1S
CB7.3E
CB8.1E
MLE2.3
LE3.6
WE4.1
WE4.2
LE5.5
Location
Segment 1
Segment 1
Segment 2
Segment 3
Segment 3
Segment 3
Segment 4
Segment 4
Segment 5
Segment 5
Segment 7
Segment 7
Segment 8
Potomac R. Mouth
Rapp. River Mouth
Mobjack Bay
York River Mouth
James River
Mouth
p-DDE
0.90
1.5
1.8
1.8
1.2
2.3
2.3
0.10
<0.01
0.02
<0.01
<0.01
<0.01
1.00
0.03
0.6
0.10
<0.01
p-DDD
0.70
1.5
1.9
2.1
1.7
1.7
1.7
0.1 .
<0.01
<0.01
<0.01
<0.01
<0.01
0.70
0.04
<0.01
0.30
<0.01
Station
0.90
0.1
1.4
1.6
"0.5
0.3
0.4
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
0.90
<0.01
<0.01
0.80
<0.01
ltl-97
-------
Chlordane
Chlordane, a Chesapeake Bay Toxic of Concern, is a broad-spectrum chlorinated hydrocarbon pesticide
which was used prior to 1980 in a wide variety of applications, including termite control, wood preservatives,
home and garden insecticides, and pesticides for use on livestock (Chesapeake Bay Program, 1991a,b;
MacDonald, 1993). in 1978 ite use was severely restricted, and its sale and distribution has been prohibited
since 1988. Although its use has been discontinued, it is of concern because it is a persistent compound
with a tendency to accumulate in sediments and bioaccumulate in biota (MacDonald, 1993).
Technical chlordane, which was the mixture used as an insecticide, consists of approximately 60%
chlordane isomers (primarily cis and trans chlordane) and 40 percent related compounds such as
heptachlor, heptachlor epoxide, cis and trans nonachlor, and various chlordenes (MacDonald, 1993; Ney,
1990). Chlordane can degrade under natural environmental conditions to photoisomers which may have
greater toxicity and bioaccumulation potential than the original compounds (Chesapeake Bay Program,
1991b).
Chlordane isomers or related compounds were detected at only 4 of the 18 mainstem stations (Table
3.31). The maximum observed sum of all chlordane compounds detected at a station was less than 2 ppb.
Long and Morgan (1990) list the ER-L and ER-M of total chlordane at 0.5 and 2 ppb, but placed low
confidence in these values due to a relative scarcity of data. MacDonald (1993) did not develop NOEL and
PEL chlordane concentrations due to the scarcity of data.
Other Chlorinated Pesticides
The cis or trans form of nonachlor was found at 2 of the 18 mainstem stations sampled, with maximum
values of 0.20 ppb and 0.21 ppb respectively, both of which occurred at station MCB3.3C in the center
trough of the middle mainstem Bay (Table 3.31). No sediment quality guidelines or criteria relating to this
compound were found in the literature.
Dicofol, an acaricide (Windholz, eta!.. 1983), was detected at three of the mainstem stations, with a
maximum concentration of 0.32 ppb at station MCB3.1 in the middle mainstem Bay (Table 3.31). No
sediment quality guidelines or criteria could be found for this compound in the literature.
Dioxins and furans
Polychlorinated di-p-dioxins (PCDDs) and polychlorinated difurans (PCDFs) consist of two benzene rings
linked by one (PCDDs) or two (PCDFs) oxygen atoms. There are 75 possible chlorinated dion'n congeners
and 135 possible chlorinated difuran congeners. These compounds are generally produced
unintentionally, either during chemical manufacturing, the production of bleached paper products, or during
the incomplete combustion of materials containing chlorine atoms and organic compounds. The most
significant sources of dioxins include the wood preservative pentachlorophenol, municipal incinerators, and
pulp and paper mills utilizing chlorine. PCBs are the most significant source of furans. These substances
have been associated with acute and chronic toxicity and cancer (MacDonald, 1993).
The only member of this class of compounds detected at concentrations above the detection limit of 0.01
ppb in the mainstem was octochlorodibenzo-p-dioxin (OCDD), which was detected at low concentrations at
13 of the 18 mainstem samples, all within the middle and lower mainstem Bay. Concentrations ranged
from 0.01 ppb to 2.67 ppb. The maximum value was found at station MCB4.3C in the central trough of
segment four (Table 3.31). No sediment guidelines or criteria relating to this compound were found in the
literature. Many compounds in this class commonly occur in the environment at concentrations in the range
of parts per billion or lower. The methods used in the monitoring program were not specifically designed to
detect such small concentrations of these compounds, as such analyses are very costly.
I1I-97
-------
Comparison With Data From NOAA Sediment Sampling Programs
Various programs conducted by the National Oceanic and Atmospheric Administration (NOAA). including
the National Status and Trend Program, Mussel Watch, and the Benthic Surveillance Project, collected
data on sediment contaminant concentrations at several stations in Chesapeake Bay between 1984-1987
(National Oceanographic and Atmospheric Administration, 1991; Figure 3.27). The median data from each
station are listed in Table 3.34, alongside comparable data collected by Maryland and Virginia with the
support of the EPA Chesapeake Bay Program. All NOAA data for both trace metals and organic
compounds were normalized for grain size by dividing measured sediment chemical contaminant
concentrations by the fraction of silt and clay in the sediment. Samples consisting of less than 20 percent
silt and clay were not included in the analysis. All the data from the Chesapeake Bay Program monitoring
program presented here have been normalized in the same way as the NOAA data facilitate comparison
between the two sets of data.
The data on sediment trace metal concentrations from NOAA and the Chesapeake Bay Program
monitoring programs are generally similar (Table 3.34). The markedly higher chromium concentrations in
the NOAA data are probably due to the stronger sediment digestion used by NOAA in analyzing trace metal
concentrations, as NOAA performed a "total" metal type of analysis and the states' used a "total
recoverable" type of metal analysis. The large differences in the estimates of the concentration of total
PCBs between the two data sets may also reflect different methods, as there is a degree of subjectivity in
determining how data on individual PCB congeners are used to estimate total PCBs. The large differences
in estimates of total DOTs are not easily attributable to differences in analytical methods.
II-98
-------
Figure 3.27 Location of stations in the mainstem Chesapeake Bay monitored for sediment contaminants by
the National Oceanic and Atmosphenc Administration. Source: National Oceanographic and AtmosDeric
Administration, 1991. H
CSMP
CSHP
CBHG
CBIB
CBCC
CBDP
III-99
-------
Table 3.34 Mean sediment trace metal and organic contaminant concentrations from NOAA and
MarylandA/irginia/CBP sediment monitoring programs in the Chesapeake Bay mainstem. Station names
and codes refer to stations sampled by NOAA. The segment refers to the approximate location of the
NOAA sediment stations in the segmentation scheme used by Chesapeake Bay Program (see Figure 3.1)
Units are ppm for trace metal concentrations and ppb for organic contaminant concentrations. All data are
normalized with respect to fraction silt and clay, with samples less than 20% silt and clay excluded from
analysis. NOAA data are from NOAA, 1991.
NOAA Station
Arsenic
Upper Ches. Bay MO
Ches. Bay MD
Ches. Bay MO
Mid. Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Low. Ches. Bay VA
Code
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
Seg.
3
3
4
5
5
7
8
7
NOAA
18
23
17
32
16
13
13
12
CBP
24.4
24.4
16.4
11.7
11.7
6.7
nd "
6.7
Cadmium
Upper Ches. Bay MD
Ches. Bay MO
Ches. Bay MD
Mid. Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Low. Ches. Bay VA
Chromium
Upper Ches. Bay MD
Ches. Bay MD
Ches. Bay MD
Mid. Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Low. Ches. Bay VA
Copper
Upper Ches. Bay MO
. Ches. Bay MD
Ches. Bay MO
Mid. Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
UCB
CBMP
CBHP
MCB
CBIB
CBCC
3
3
4
5
5
7
8
7
3
.3
4
5
5
7
8
7
3
3
4
5
5
7
0.87
0.60
0.59
1.00
0.51
0.47
0.47
0.50
180
120
110
170
63
86
54
130
65
53
49
42
29
25
0.48
0.48
0.42
0.42
0.43
0.20
nd
0.20
40
40
43
42
42
32
nd
32
32
32
28
22
22
15
IIMOO
-------
Table 3.34, continued
NOAA Station
Code
Seg.
NOAA
CBP
Ches. BayVA
Low. Ches. Bay VA
Lead
Upper Ches. Bay MD
Ches. Bay MD
Ches, Bay MD
Mid. Ches. BayVA
Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Low. Ches. BayVA
Mercury
Upper Ches. Bay MD
Ches. Bay MD
Ches. Bay MD
Mid. Ches. BayVA
Ches. Bay VA
Ches. BayVA
Ches. BayVA
Low. Ches. Bay VA
Nickel
Upper Ches. Bay MD
Ches. Bay MD
Ches. Bay MD
Mid. Ches. BayVA
Ches. BayVA
Ches. Bay VA
Ches. BayVA
Low. Ches. Bay VA
Zjnc
Upper Ches. Bay MD
Ches. Bay MD
Ches. Bay MD
Mid. Ches. BayVA
Ches. Bay VA
Ches. BayVA
Ches. BayVA
Low. Ches. Bay VA
Total PAHs
Upper Ches. Bay MD
Ches. Bay MD
Ches. Bay MD
CBDP
LCB
UCB
CBMP
CBHP
MCB
CBiB
CBCC
CBDP
LCB
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
UCB
CBMP
CBHP
8
7
3
3
4
5
5
7
8
7
3
3
4
5
5
7
8
7
3
3
4
5
5
7
8
7
3
3
4
5
5
7
8
7
3
3
4
22
24
70
74
68
85
28
36
36
33
0.29
0.23
0.21
0.10
0.12
0.082
0.13
0.086
75
66
56
. 67
36
35
33
33
320
390
300
320
120
120
80
140
3800
6400
4300
nd
15
49.8
49.8
37.4
30.9
30.9
13.5
nd
13.5
0.06
0.06
0.06
0.06
0.06
0.07
nd
0.07
46.9
46.9
33.2
26.7
26.7
15.2
nd
15.2
224
224
226
188
188
73
nd
73
5058
5058
2201
111-101
-------
Table 3.34, continued
NOAA Station
Code
Seg.
NOAA
CBP
Mid.Ches. BayVA
Ches. Bay VA
Ches. Bay VA
Ches. Bay VA
Low. Ches. Bay VA
Ches. Bay
MCB
CBIB
CBCC
CBDP
LCB
5
5
7
8
7
610
740
120
680
530
2139
2139
595
nd
595
Total DDT
Upper Ches. Bay MO
Ches. Bay MD
Ches. Bay MD
Mid.Ches. BayVA
Ches. BayVA
Ches. Bay VA
Ches. BayVA
Low. Ches. Bay VA
Total PCB
Upper Ches. Bay MD
Ches. Bay MD
Ches. Bay MD
Mid. Ches. Bay VA
Ches. Bay VA
Ches. BayVA
Ches. Bay VA
Low. Ches. Bay VA
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
UCB
CBMP
CBHP
MCB
CBIB
CBCC
CBDP
LCB
3
4
5
5
7
8
7
3
3
4
5
5
7
8
7
14
4.1
14
14
1.2
2.6
2.4
7.1
2.7
270
92 •
110
13
6.3
1.3
20
54
4.1
0.012
0.03
0.03
0.03
nd
0.03
12
0.85
0.85
0.08
0.008
bdl
nd
bdl
111-102
-------
-------
Tributaries
This chapter discusses data from sediment contaminant monitoring programs in the b'da! tributaries of
Chesapeake Bay, excluding the Elizabeth River, Baltimore Harbor (Patapsco River), Back River, the
Anacostia and upper Potomac Rivers. Information on sediment contamination in the listed areas is
presented separately because focused studies or data in addition to the State monitoring programs is
available and because these areas are widely regarded as having the highest levels of sediment
contamination in the Chesapeake Bay.
Sediment Contaminant Monitoring Programs in the Tidal Tributaries of Chesapeake Bay
The Maryland Department of Environment (MDE) conducts a sediment contaminant monitoring
program in the tidal tributaries of the Chesapeake Bay within the state of Maryland. The stations
selected for monitoring of sediment contaminants are a subset of the Chesapeake Bay Program's
water quality monitoring stations (Magnien ef a/., 1990). Sediments have generally been sampled at
Maryland tributary monitoring stations annually since 1986, although only a few of the stations were
sampled in the first year of the monitoring program. Data on sediment concentrations of metals and
total organic carbon and sediment grain size distribution are available for each year of sampling (1986 -
1991). Data on sediment concentrations of polycyclic aromatic hydrocarbons are available for
sediment samples collected in 1986,1987, and 1991. Data on sediment concentrations of pesticides
and PCBs are available from 1991 only. In 1986,13 of the Maryland tributary stations were sampled in
October and December. In 1987, four of Maryland's eastern tributary stations (MET.1. MET2.2,
MET2.3, AND MET3.1), all in the region called "Northeast Rivers," were sampled in November. All
other samples, in all years, were collected between March and July.
In Virginia, sediment contaminant monitoring programs have been coordinated by the Virginia
Department of Environmental Quality (VADEQ). In 1985 and 1986, many of the Chesapeake Bay
Program water quality monitoring stations in the Rappahannock, York, and James rivers were analyzed
only for sediment organic chemical contaminants with the support of the Chesapeake Bay Program
(Fig. 4.1 b). One station in each of these tributaries was again sampled for organic chemical
contaminants in 1991 in conjunction with that year's mainstem sediment contaminant monitoring
program.
The VADEQ has collected monitoring data on sediment trace metal concentrations only in the James
River (Fig. 4.1c). Data on sediment trace metal concentrations and percent silt and clay particles is
available from single samples collected in 1985 and 1986 (except for one sample collected in 1990)
from 29 stations located above and below selected wastewater treatment outfalls throughout the tidal
portion of the James River and some of its tributaries. These samples were collected as part of a study
of the effects of industrial, municipal, and federal facility wastewater effluents on the concentrations of
toxic organic compounds and metals in nearby sediments and shellfish tissue (deFur et a/., 1987).
While the sediment samples are identified as "ambient" samples, the focus of sampling effort towards
point sources of potentially toxic chemicals probably biases the data toward higher concentrations of
sediment contaminants compared to what would be collected from stations which are selected to be
representative of the general area in which they are located.
Data Analysis
The MDE and VADEQ sediment contaminant monitoring stations were assigned to "regions" based on
expectations of similar sources of chemical contaminants, e.g., the Potomac River or the Southeastern
Rivers and Bays region on the lower eastern shore of Maryland. With the exception of the VADEQ data
on sediment trace metal concentrations in the James River, results for each tributary station are shown
graphically within the context of adjacent tributaries assigned to the same region. The MDE and
IV-1
-------
VADEQ monitoring station designations are listed in Table 4.1 to facilitate comparisons to water quality
data available in other reports, e.g., Magnien etal.. 1990; Magnien etaL, 1992. The locations of the
monitoring stations are shown in Figures 4.1 a-c.
Medians, quartiles and the minimum and maximum values of bulk concentrations of each chemical
contaminant are presented in tables and displayed graphically. The graphical presentation provides a
measure of centra! tendency (median), dispersion {quartiles), and range. Statistics are also presented
for trace metal concentrations normalized by the fraction of silt and clay particles in the sediment and
for PAH concentrations normalized by the fraction of total organic carbon in the sediment. Because of
the much higher density of stations in the James River sampled for trace metals compared to that in
other tributary regions, statistics on these stations were calculated separately from the Maryland
stations and the Virginia stations sampled for organic contaminants.
Sediment Characteristics
Information on grain size, salinity range, and sedimentation rates is available for most stations and is
provided in Table 4.1. More details on sediment accumulation rates are listed in Appendix A. Excluding
the stations in the James River sampled for trace metal concentrations, muddy sand (silt and clay
between 10 percent and 50 percent; Table 1.1} is the most common sediment type among the tributary
stations (Table 4.2 and Figure 4.2), and was found at 64 percent of 64 stations. Stations classified as
mud and sandy mud comprised 22 percent and 14 percent of these stations, respectively, with no
stations that would be classified as sand (silt and clay less than 10 percent) (Table 4.2 and Figure 4.2).
The stations in the James River sampled for trace metal concentrations had a much lower average
percentage of silt and clay particles compared to the Maryland tributary stations and the stations in the
Rappahannock, York, and James Rivers sampled for organic contaminants in 1991 (Table 4.2).
Almost 18 percent of the James River trace metal stations are sand, 53 percent are muddy sand, with
sandy mud and mud constituting about 9 percent and 12 percent of the stations, respectively.
Median concentrations of total organic carbon were roughly three to four percent in the northeastern,
northwestern, and western tributaries (Table 4.3 and Figure 4.3). Tributary stations on the eastern
shore including the Chester and Choptank Rivers and stations further south had lower total organic
carbon content, with median concentrations of approximately two to two and a half percent. Total
organic carbon concentration data from the Virginia tributaries were based on a single measurement in
each tributary.
IV-2
-------
Figure 4.1 a Maryland Tributary Sediment Contaminant]
Monitoring Stations and Regions
Northwsst
Rivers
Northeast
Rivers
Baltimore
Harbor
Chester &
Choptank
Rivers
Eastern
Bays
fc_ >-, L. Nanticoke >
^~ /^ /^^
utheasQ
Ri fers &
Biys
Potomac
IV-3
-------
Figure 4.1b. Virginia tributary stations monitored for sediment concentrations of polycyclic aromatic
hydrocarbons. Stations RET3.1, RET4.1 and TF5.5 were also monitored for chlorinated hydrocarbons
in 1991 .Figure 4.1 c. Stations in the James River monitored for sediment concentrations of trace metals
by the Virginia Department of Environmental Quality. Stations apparently off of the river are properly
located on tributaries to the James River but exceed the river boundaries of the Geographic Information
System.
TF3.1
TF3.2
Rappahannock
IV-4
-------
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Table 4.2. Summary statistics for percent silt and clay in tributary sediments.
Area
Mean Median
N
SD
VIRGINIA SEDIMENT SAMPLES FOR TRACE METALS
James River 37 26 32
Min
26
Max
All
Maryland*
Northwestern Rivers
Western Rivers
Patuxent River
Potomac River
Northeastern Rivers
Chester & Choptank
Eastern Bays
Southeastern Rivers
VIRGINIA SEDIMENT
Rappahannock R.
York River
James River
69
75
86
73
87
84
76
71
79
65
SAMPLES FOR
91
73
46
79
81
90
77
90
88
80
79
89
67
ORGANIC
97
95
47
240
181
13
27
15
16
19
22
23
21
COMPOUNDS
19
35
36
27
20
12
19
12
33
38
14
12
18
37
6
2
2
12
66
22
49
88
80
79
89
67
97
95
47
99
99
98
99
97
97
99
94
99
99
99
97
99
99
lV-5
-------
Figure 4.2. Summary statistics for the percentage of silt and clay in sediment samples from
Chesapeake Bay tributaries. Virginia samples are single samples taken in 1991 for organic
contaminants. The box and whisker plots illustrate the median (central horizontal line), quartiles
(extent of rectangle), and ranges (extent of vertical lines) in data collected from individual
Maryland tributary station between 1986 and 1991. The box and whisker plots for the James
River represent statistics for groups of stations aggregated by segment, (continued)
100
ao
eo
•
I
1 OO
ao
ao
York
rra
uei «_ca uea i_c«
uei uea
James River (by salinity zones)
oo
00
ao
-*o
ao
o
O T
OOO
OO
Transition Zone
1OO
8O
eo
•*o
20
o
.
D F
3 E
O O
o o
1 1
A A
F H
E w
A O
2 O
A
V
O
1
1
A
100
BO
eo
20
oC
Lower Estuarlne Zone
C H
B A
O O
O O
2 1
A A
J
O
O
1
A
H H
N S
O O
O O
11
A A
N S S
N C Nl
O O O
I O 7
719
A A A
S
N
O
B
IV-6
-------
Figure 4.2 Percentage silt and clay
in tributary sediments
OO
ao
oo
AO
o
81
1 OO
BO
20
fslorthiwest Rivers
1 00
BO
ISlorthieast Rigors
K4IDD
Western Rivers
0
2O
1 00
BO
BO
BOM
CD h ester
EUK
100
80
BO
2O
MAO SEV SOUTd FtlHODE WEST
F"atux:ent River
o
LJC
I 00
BO
BO
AO
20
TlOP"*^
1 OOi
eo
BO
AO
20
TRANS
ts^ESO
oo
BO
BO
AO
20
CQAY C»-IOF>C»><« I.ITC
Southeast Rivers
TRAMS
IV-7
-------
Table 4.3 Summary statistics for total organic carbon in tributary sediments.
Concentrations are in per cent dry weight
AREA
All
Northwestern Rivers
Western Rivers
Petuxent River
Potomac river
Northeastern Rivers
Chester & Choptank
Eastern Bays
Southeastern Rivers
Rappahannock River
York River
James River
MEAN-p
3.32
3.47
4.06
3.48
3.14
3.77
3.66
2.31
2.92
2.92
4.02
4.21
MEDIAN
3.18
3.68
3.68
3.47
3.21
3.67
2.65
1.97
2.65
2.92
4.02
4.21
N
184
13
27
15
19
20
19
16
52
1
1
1
SD-o
1.25
0.59
1.32
0.74
0.41
0.90
1.77
0.80
1.37
MIN
0.67
2.60
2.18
1.99
2.44
1.57
1.39
1.50
0.67
2.92
4.02
4.21
MAX
6.80
4.21
6.52
4.67
3.84
4.99
6.39
3.72
6.80
2.92
4.02
4.21
IV-8
-------
Figure 4.3. Summary statistics for the percentage of total organic carbon in sediment samples
from Chesapeake Bay tributaries. The box and whisker plots illustrate the median (central
horizontal line), quartiles (extent of rectangle), and ranges (extent of vertical lines) in data
collected from each tributary station, (continued)
10
1 O
NortHwest Rivers
MortHeast Rivers
HJSM OtJ**f»
Western Rivers
MIDO Hf
1O
aot-t - CI_K
Chester &. CDr»op)t£i.r>l<
o
^
•>
Q.
MAO
1O
sev
nt-
-------
Figure 4.3 Percentage total organic carbon
in tributary sediments
(continued)
to
Rap>p>stria.nnock: River
TF1 TF-2 TF3 R1 R2 I.C 1 l_E2 UE3
"Yfc>rk River
o
i
1 O
R1 R2 UE1 UE2 UE3
James River
T
T
r
C
L.
2
L.
E
"Figure 4.3 Summary statistics for percentage total organic carton in Chesapeake Bay
tributaries. The box and whisker plots illustrate the median (central horizontal line), the quartiles
(extent of the rectangle), and ranges (extent of vertical lines) in data collected for each station.
If there are less than four values, the rectangle's bottom and top show the range. A dash
indicates only a single value is available. Data presented are for individual stations. See Table
4.1 for interpretation of station name abbreviations.
IV-10
-------
General Patterns in the Spatial Distribution of Trace Metals
Spatial distribution patterns within and among the Chesapeake Bay tidal tributaries were similar for
most of the trace metals measured. The highest sediment concentrations of trace metals in tributarie:
examined in this chapter were generally found in the tributaries located in the urbanized area around
Baltimore within the Western, Northwestern, and Northeastern Rivers regions (Figures 4.3-4.10). The
only exception to this spatial pattern was cadmium, a metal for which the tidal fresh station of the
Patuxent River had the highest median concentration of any station (Figure 4.5). For many trace
metals (i.e., copper, lead, nickel, and zinc), the Western shore tributaries showed a gradient of
decreasing concentration from north to south, with the Magothy and Severn rivers often having much
higher metal concentrations than those seen in the Rhode and West rivers (Figures 4.6-4.7,419-4.10).
The Patuxent, Potomac, Chester, and Choptank Rivers generally had intermediate sediment
concentrations of most trace metals, while stations in the Eastern Bays and Southeastern Rivers and
Bay regions in Maryland generally had the lowest sediment concentrations of most trace metals
{Figures 4.3-4.10). Again, cadmium concentrations did not follow this distribution, as some samples
from the Southeastern Rivers and Bays Region had sediment cadmium concentrations which were
considerably above those from some of the more populated areas such as Potomac River and
Northeast Rivers regions.
Trace metal concentrations in the James River were generally within the range found in the group of
Maryland tributary regions with the lowest trace metal concentrations. However, one or both of the
stations in the tower estuarine portion of the James River near Sewells Point Naval Complex (SN79 an i
SN81) exhibited sediment concentrations of all the trace metals which were markedly higher than thos ;
observed elsewhere in the James River, and which were comparable to, or higher than, the highest
concentrations found in the Maryland tributaries. The Virginia Water Control Board concluded that
there was evidence of the accumulation of trace metals in the sediments at these stations near the
Sewells Point Naval Complex wastewater outfalls (deFur et at.. 1987).
Among the Maryland tributary stations, the major trends in measured (bulk) trace metal concentrations
generally also apply to trace metal concentrations normalized to the fraction of the sediment consisting
of clay and silt particles. Thus, the spatial pattern in measured sediment trace metal concentrations
probably largely reflects differences in metal loadings among the different tributaries, and does not
result solely from differences in sediment grain size distributions. The spatial pattern in sediment trace
metal concentrations also generally parallels differences in population density in the different
watersheds.
In the James River, in contrast, median normalized trace metal concentrations were generally among
the highest of all the tributary regions, whereas median measured (bulk) metal concentrations were
among the lowest of all tributary regions. This may be because of higher trace metal loadings to these
stations, most likely due to their proximity to wastewater outfalls. Alternately, a substantial fraction of
the trace metals in the James River sediments may be associated w;tn sa-.i carjcles. It is generally
difficult to draw conclusions regarding sediment contaminant concenirai: -: ^.nen the sediment
samples have a high proportion of sand (National Oceanographic arc1 A:-r.c:;^enc Administration,
1991), as was the case with many of the James River sediment sample:, a--i .red for trace metals.
Within all but the most and least contaminated tributary stations in Maryland, average sediment
concentrations of most trace metals were within the range bracketed by the No Observable Effect Leve
(NOEL) and the Probable Effects Level (PEL) concentrations determined by f/acDonald (1293). The
NOEL concentration for arsenic was exceeded by the median measured concentrations at all tributary
stations. In contrast, the NOEL concentration for cadmium was exceeded by the average measured
cadmium concentration at only about 25 percent of the Maryland monitoring stations. Average
sediment concentrations of the other trace metals (chromium, copper, lead, mercury, and zinc)
exceeded the NOEL concentrations at about 72, 28, 56,42, and 89 percent respectively of the
Maryland monitoring stations.
IV-11
-------
The average sediment trace metal concentrations in Maryland tributary sediments exceeded the PEL
concentration only in the case of zinc in the Magothy and Severn rivers, tributaries located in heavily
urbanized areas. Current sediment quality guidelines for nickel are inadequate for assessing the
likelihood of toxicity due to sediment concentrations of this trace metal {Long et a/., 1995). Based on
measured sediment contaminant concentrations compared to the PELs, toxicity to aquatic biota is not
likely at most of the Maryland tributary stations sampled, with the exception of the stations in the
Magothy and Severn rivers, where toxicity due to sediment concentrations of zinc is likely.
Among the stations sampled in the James River, sediment concentrations of all trace metals except
arsenic were below NOEL concentrations at the majority of stations. The NOEL concentration of 8 ppm
was exceeded at most of the James River stations. At station SN79 and SN81 near the Sewells Point
Naval facility, sediment concentrations of all trace metals exceeded their respective NOEL
concentrations, and the concentrations of lead, mercury, and zinc exceeded PEL concentrations.
Toxicity to aquatic biota due to the measured sediment concentrations of trace metals is not likely at the
James Rfver stations sampled, with the exception of the stations near Sewells Point Naval Complex
where toxicity due to sediment concentrations of lead, mercury, and zinc is likely.
Refer back to the section of Chapter 3 covering the mainstem metals for a description-of the sources of
each metal and information on which metals are on the Chesapeake Bay Program Toxics of Concern
list and to Table 1.2 for sediment quality guidelines and criteria.
General Patterns in the Spatial Distribution of Polycyclic Aromatic Hydrocarbons
Higher concentrations of most polycyclic aromatic hydrocarbons (PAHs) were found in sediments from
the Northwestern, Western, and Northeastern Rivers regions than in the other tributary regions. The
maximum sediment concentration of the majority of the PAH compounds measured occurred in the
Sassafras River in 1987. The maximum concentrations of many of the PAHs found at this station were
usually over twice as high as maximum concentrations at other tributary stations. However, sediment
PAH concentrations found at this location in 1991 were dramatically lower than those found in 1987,
and the same was true for sediment PAH concentrations found in 1992 (Maryland Department of the
Environment, preliminary data), and thus the 1987 data may not be representative of typical conditions
in the Sassafras River. The sampling station in the Sassafras River is located in a region of intensive
recreational boating. The Middle, Magothy, Severn, and Potomac rivers were also notable for relatively
high concentrations of PAHs. Concentrations of most PAHs were much lower in the Eastern Bays and
Southeastern Rivers and Bays regions than in other tributary regions.
Instances of the average sediment concentrations of PAHs at tributary stations exceeding their NOEL
concentration were relatively rare, and no station had an average concentration of any PAH in excess
of the PEL concentration, although PEL concentrations were approached in the 1987 sample from the
Sassafras River. Thus, toxicity to aquatic biota due to the measured sediment concentrations of PAHs
is unlikely in the monitored areas of the tidal tributaries.
Pesticides and Chlorinated Hydrocarbons
The data on pesticides and chlorinated organic compounds are all from 1991 samples. Data is
available for twenty-seven stations in the Maryland tributaries and three stations in the Virginia
tributaries.
Few pesticides and other chlorinated organic compounds were detected at any one station, with the
exception of the many different congeners of PCBs detected in the James River. The biological
significance of the sediment concentrations of many of the pesticides and PCBs detected in the
tributary sediments is difficult to assess, since sediment quality guidelines or criteria are not available for
most of these compounds. For trie few compounds for which sediment quality guidelines are available,
most measured sediment concentrations were slightly above their respective NOEL concentration, but
IV-12
-------
well below their respective PEL concentration. Thus, toxicity to aquatic biota due to the measured
sediment concentrations of pesticides and PCBs is not likely at the stations monitored in the t'dal
tributaries. For those pesticides still in use, it is not known whether their sediment concentrations at the
time of sediment sampling in the spring (often during the period of maximum pesticide applications)
persist throughout the year or diminish as the pesticides degrade.
Spatial Distribution of Individual Trace Metals
Arsenic
The median sediment arsenic concentration among Maryland tributary stations was 21 ppm, and the
maximum sediment concentration was 73 ppm in the lower Patuxent River in 1988 (Table 4.4 and
Figure 4.4). The median sediment arsenic concentration among the James River stations was 9 ppm,
with a maximum of 37 ppm (Table 4.4 and Figure 4.4).
The analyses of James River sediments for arsenic had a relatively high detection limit (2 to 15 ppm
compared to 0.01 ppm for the analyses used for the Maryland samples), and sediment arsenic
concentrations were below the detection limit for 11 of the 29 samples from the James River. These
samples were excluded from the statistical analyses, and thus the minimum, mean, and median
sediment arsenic concentrations in the James River are overestimated in Table 4.4.
Sediment arsenic concentrations in tributary sediments showed less geographic variation than was the
case for most other trace metals. Average sediment arsenic concentrations at various stations or
regions differed by only about 2-3 times compared to the 4-6 fold variation commonly observed for
other trace metals. The pattern of spatial distribution followed the pattern typical of other trace metals,
however, with higher concentrations in the Northwestern, Northeastern, and Upper Western Shore
tributaries closest to Baltimore; intermediate concentrations in the Patuxent and Potomac Rivers and
stations in and near the Chester and Choptank Rivers, and the lowest concentrations at stations on the
Maryland lower eastern shore and within the James River (Table 4.4 and Figure 4.4).
Median sediment arsenic concentrations at all of the tributary stations in Maryland and within each
region of the James River were above the NOEL of 8 ppm (MacDonald 1993; Table 4.4). Median
concentrations at all stations were below the PEL of 64 ppm (MacDonald, 1993), although the PEL was
exceeded by individual measurements in the Patuxent and Sassafras (Northeast region) Rivers.
Toxicity to aquatic biota due to the measured sediment arsenic concentrations is not likely at the
monitored locations in the tidal tributaries.
Figure 4.4. reports summary statistics for concentrations of arsenic in Chesapeake Bay tributary
sediments, in parts per million. The box and whisker plots illustrate the median (central
horizontal line), quartiles (extent of rectangle), and ranges (extent of vertical lines) in data
collected from each station or river segment. Data are for bulk sediment concentrations. Data
are presented for individual stations in the Maryland tributaries. The box and whisker plots for
the James River represent statistics for groups of stations aggregated by segment. See Table 4.1
for interpretation of station abbreviations. The NOEL and PEL concentrations for sediment
arsenic concentrations are 8 ppm and 64 ppm, respectively (MacDonald, 1993).
IV-13
-------
Table 4.4. Summary statistics for arsenic in tributary sediments. Concentrations are in ppm dry weight.
Normalized concentrations are dry weight concentrations divided by the fraction silt and clay sized
particles in the sediment..
Measured
Normalized
Area Mean
Ail
MD stations
N.W. Rivers
Western R.
Patuxent R.
Potomac R.
N.E. Rivers
21
22
29
27
29
20
32
Ches. & Chop22
E. Bays
S.E. Rivers
21
15
N
210
181
13
27
15
19
20
19
16
52
SD
12
12
13
9
14
8
16
13
13
5
Min Median
0.3
0.3
12.3
11.8
13.0
7.0
8.6
3.7
0.3
3.2
19
21
28
28
27
20
28
21
18
15
Max
73
73
57
43
73
32
67
48
50
32
Mean
35
32
35
43
33
26
44
32
31
24
N
210
181
13
27
15
19
20
19
16
52
SD
26
20
19
27
14
12
25
14
27
13
Min Median Max
0.5
0.5
14.7
12.7
17.9
8.0
14.3
7.5
0.5
9.7
28 236
28 149
33 86
35 149
29 76
28 52
36 116
33 55
25 120
21 84
James River 11 29
8
2.0
37
49 29 49 8.0 28 236
IV-14
-------
Figure 4.4a Arsenic concentrations (ppm)
in Maryland tributary sediments
ao
ISJortf-iwest Rivers
00
ao
Nortrieast Rivers
OUSM
MIOO UK
eo
Western Rivers
301
SCV SOOTt-l RI-4OOC WEST
eo
T MAIM 9
Potomac River
I I
ao
o
c
ao
eo
ao
East Bays
Southeast Rivers
I '
TlOF-«
MCSO
< rx A
Figure 4.4a Summary statistics for bulk sediment concentrations of arsenic in Maryland's Chesapeake Bay
tributaries, in parts per million. The box and whisker plots illustrate the median (central horizontal line),
quartiles (extent of rectangle), and ranges (extent of vertical lines) in data collected from each station or
river segment. The NOEL and PEL concentrations for sediment arsenic concentrations are 8 ppm and
64 ppm, respectively (MacDonald 1993). The PEL is represented in the graphs as a dotted line, if it is within
the range of concentration values.
IV-15
-------
Figure ^.-*t> /Vrsenic concentrations (ppm)
in James River sediments
so
20
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o
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O
O
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20
Lower EEstLisiring
C
8
O
0
2
A
H
A
O
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1
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n
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O
O
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rsi
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Figure 4.4b Summary statistics for bulk sediment concentrations of arsenic in the James River. Data
presented are for individual stations. The NOEL and PEL values for sediment arsenic concentrations are
8 ppm and 64 ppm, respectively (MacDonald 1993). The PEL is represented in the graphs as a dotted line,
if it is within the range of concentration values.
IV-15.1
-------
Cadmium
The median sediment cadmium concentration for all Maryland tributary stations was 0.6 ppm,
and the maximum concentration was 3.5 ppm at the tidal fresh station of the Patuxent River in
1990 (Table 4.5 and Figure 4.5). The median cadmium concentration in the James River was
0.20 ppm. Sediment cadmium concentrations at the two stations (SN79 and SN81) located near
Sewells Point Naval complex were 4.0 and 6.0 ppm, several times higher than concentrations
found at any other station in the James River.
The analyses of James River sediments for cadmium had relatively high detection limits (0.2-0.7
ppm compared to 0.01 ppm for the analyses used for the Maryland samples), and sediment
cadmium concentrations were below the detection limit for 21 of the 29 samples from the James
River. These samples were excluded from the statistical analyses, and thus the minimum and
median sediment cadmium concentrations in the James River given in Table 4.4 are probably
overestimated.
The spatial pattern of sediment cadmium concentrations differed from that shown by the other
trace metals. For the other trace metals, the highest sediment concentrations were typically
found in the Upper Western, Northwestern, and Northeastern Rivers regions, whereas for
cadmium, the highest sediment concentrations were found in the Patuxent River and were also
relatively high at some of the Southeastern Rivers and Bays stations.
Median sediment cadmium concentrations were above the NOEL of 1.0 ppm (MacDonald, 1993)
at several of the Maryland tributary stations, including the tidal fresh and mesohaline stations in
the Patuxent River, and the stations in the Middle, Magothy, South and Upper Nanticoke rivers
(Table 4.5). The NOEL was also exceeded by individual measurements at one or more stations
from every other tributary region in Maryland. The NOEL was exceeded in the James River
only at the two Sewells Point Naval Complex stations. The maximum observed concentrations in
the Maryland tributaries and in the James River were both well below the PEL of 7.5 ppm.
Toxicity to aquatic biota due to the measured sediment concentrations of cadmium is not likely at
the monitored stations in the tidal tributaries.
IV-16
-------
-------
Table 4.5. Summary statistics for cadmium in tributary sediments. Concentrations are in ppm dry weight. Nornalized
concentrations are dry weight concentrations divided by the fraction silt and clay sized particles in the sediment.
Measured
Normalized
Area
Mean N SO
Min Median Max Mean N SO Min Median Max
All
MD stations
0.7
0.7
210
181
0.7
0.6
0.01
0.01
0.6
0.6
6.0
3.5
1.5
1.2
210
182
3.3
1.3
0.01
0.01
0.8 44.0
0.8 9.9
N.W. Rivers
Western R.
Patuxent R.
Potomac R.
0.7
0.9
1.4
0.8
13
27
15
19
0.5
0.6
1.2
0.4
0.01
0.01
0.01
0.18
0.5
0.8
1.5
0.7
1.4
2.1
3.5
2.0
0.8
1.5
1.7
1.1
13
27
15
19
0.6
1.9
1.4
0.9
0.01
0.02
0.01
0.33
0.5 1.8
1.0 9.9
1.6 3.9
0.8 4.1
N.E. Rivers 0.5
Ches. & Chop. 0.5
E. Bays 0.5
S.E. Rivers 0.7
James River 0.7 29 1.2 0.20 0.20 6.0
20
19
16
52
0.3
0.4
0.3
0.6
0.01
0.01
0.10
0.01
0.5
0.4
0.5
0.5
1.0
1.6
1.2
2.9
0.7
0.8
12
12
20
19
16
52
0.4
0.8
2.3
12
0.02
0.02
0.11
0.01
0.8
0.6
0.6
0.8
1.6
3.1
9.5
6.2
3.63 29 8.0 0.23 1.4 44.0
IV-17
-------
Figure 4.5a Cadmium concentrations (ppm)
in Maryland tributary sediments
•>
CL
s
« .
a
BU
e1
0
9
;
M>
a
i
e
TIC
i
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i
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a
i «
1 I n
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e
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i i 1 :
to SEN" SOUTM «>-»ooe WEST «^r>t River
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a .
. , i :
p
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East Bays
' 4 I
Southeast Rivers
*
1 1 1 I 1 1 .
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Figure 4.5a Summary statistics for concentrations of cadmium in Chesapeake Bay tributary sediments, in
parts per million. The box and whisker plots illustrate the median (centra! horizontal line), quartiles (extent
of rectangle), and ranges (extent of vertical lines) in data collected from each station or river segment.
Data are for bulk sediment concentrations. The NOEL and PEL concentrations for sediment cadmium
concentrations are 1 ppm and 7.5 ppm, respectively (MacDonald 1993).
IV-18
-------
Figure -4.5b Cadmium concentrations (ppm)
in James River sediments
Tlciail
2
1
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Figure 4.5b Summary statistics for bulk sediment concentrations of cadmium im the James River. Data
presented are for individual stations. The NOEL and PEL values for sediment cadmium concentrations are
1 ppm and 7.5 ppm, respectively (MacDonafd 1993).
IV-19
-------
Chromium
The median chromium sediment concentration for Maryland tributary stations was 50 ppm, with a
maximum concentration of 172 ppm at the Severn River in 1990 (Table 4.6 and Figure 4.6). Within the
James River, the median chromium concentration was 20 ppm, and the maximum concentration was 136
ppm at station SN81 (Table 4.6 and Figure 4.6). This concentration was much higher than that at any
other James River station.
Median sediment chromium concentrations exceeded the NOEL concentration of 33 ppm (MacDonald,
1993) in all Maryland tributary regions except the Southeastern Rivers region, where the NOEL was
exceeded at most stations by one or two individual measurements. Median sediment chromium
concentrations were below the NOEL within all three segments of the James River. Measured
concentrations of chromium never exceeded the PEL concentration of 240 ppm. Toxic effects to aquatic
biota due to the measured sediment chromium concentrations are not likely at the monitored locations in
the tidal tributaries.
Table 4.6. Summary statistics for chromium in tributary sediments. Concentrations are in ppm dry weight. Normalized
concentrations are dry weight concentrations divided by fraction of silt and clay particles in the sediment.
Measured
Normalized
Area
Mean N SO Min Median Max Mean N SD
Min Median Max
All
MD stations
54 209
58 181
34
34
5
6
45
50
172
172
87
84
209
181
71
65
17
17
66
65
484
468
N.W. Rivers 69 13 13
Western R. 109 27 28
PatuxentR. 75 15 20
Potomac R. 46 19 7
N.E. Rivers 80 20 34
Ches. & Chop42 19 15
E.Bays 37 16 9
S.E. Rivers 31 52 15
James R. 26 28 24
46
60
51
36
69
103
68
45
86
172
120
62
82
165
86
60
13
27
15
19
21
84
20
33
48
65
58
40
83
146
82
52
125
468
134
190
30
15
23
6
64
40
36
29
158
76
56
79
110
65
70
52
20
19
16
52
54
30
104
29
60
33
28
17
93
58
42
41
286
140
458
181
20
136
107 28 102
20
74 484
IV-20
-------
Figure 4.6a Chromium concentrations (ppm)
in Maryland tributary sediments
3:WC7
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Figure 4.6a Summary statistics for bulk sediment concentrations of chromium in Maryland's Chesapeake
Bay tributaries, in parts per million. The box and whiske; plots illustrate the median (central horizontal line),
quartiles (extent of rectangle), and ranges (extent of vertical lines) in data collected from each station or
river segment. The NOEL and PEL concentrations for sediment chromium concentrations are 33 ppm and
240 ppm, respectively (MacDonald 1993). The PEL is represented in the graphs as a dotted line, if it
within the range of concentration values.
. if it is
IV-21
-------
Figure -4.6fc> Chromium concentrations (ppm)
in James River sediments
soo
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Figure 4.6b Summary statistics for bulk sediment concentrations of chromium in the James River. Data
presented are for individual stations. The NOEL and PEL values for sediment chromium concentrations are
33 ppm and 240 ppm, respectively (MacDonald 1993). The PEL is represented in the graphs as a dotted
line, if it is within the range of concentration values.
IV-22
-------
Copper
The median sediment copper concentration among Maryland tributary stations was 25 ppm and the maxii mm
concentration was 112 ppm at the Magothy River in 1990 (Table 4.7 and Figure 4.7). The median copp r
concentration in the James River was 19 ppm and the maximum copper concentration in the James River was 26j
ppm at station SN79. Stations SN81, SG001, and HP001 also had sediment copper concentrations sever; 1 times'
higher than the median concentration for the James River.
The median copper concentrations in the Northwestern, Western, Potomac and Northeastern River regioi s were
above the NOEL of 28 ppm (Table 4.7). Maximum concentrations in all Maryland tributary regions exct pt the
Southeastern Rivers regions also exceed the NOEL. Median copper concentration were below the NOEI in the
James River. The PEL of 170 ppm is above the highest measurements in Maryland but below the maxim am
value in the James River. Toxic effects to aquatic biota due to the measured sediment copper concentrat ons are ]
not likely at any of the monitored tributary stations except for the highest concentrations in the James Riv :r.
Table 4.7. Summary statistics for copper. Concentrations are in ppm dry weight. Normalized concentrations ai 2 dry
weight concentrations divided by the fraction silt and clay particles in the sediment.
Measured
Normalized
Area
Mean N SO Min Median Max Mean N SO
Min Median Max
All
MD stations
31 210
30 181
28
21
i
3
3
24
25
263
112
71
43
210
181
219
45
8
10
36
33
2890
460
N.W. Rivers 55 13 19
Western R. 61 27 21
PatuxentR. 24 15 6
Potomac R. 35 19 5
N.E. Rivers 40 20 13
Ches.&Chop16 19
E. Bays 20 16
S.E. Rivers 11 52
James River 38 29 53
34
35
12
28
45
51
23
36
95
112
34
43
3
7
7
4
14
3
12
3
42
15
17
11
61
31
32
22
67
96
27
45
13
27
15
19
28
79
5
15
36
46
23
32
60
76
26
41
126
460
38
99
54
25
39
19
20
19
16
52
21
14
59
10
29
13
15
10
53
20
24
17
127
70
257
67
19 263
240 29 557
57 2890
IV-23
-------
200
•> so
oo
2OO
1 SO
1 OO
xiHIhfff!!!!!
Transition
aoo
so
•> oo
so-I
Lower
rin
Figure 4.7b Summary statistics for bulk sediment concentrations of copper in the James River. Data
presented are for individual stations. The plots represent statistics for groups of stations aggregated by
segment. The NOEL and PEL values for sediment copper concentrations are 28 ppm and 270 ppm,
respectively (MacDonald 1993). The PEL is represented in the graphs as a dotted line, if it is within the
range of concentration values.
IV-25
-------
Figure 4.8a Lead concentrations (ppm)
in Maryland tributary sediments
r-Jortf-iwest Rivers
Nortriosist Rivers
aoo
\A/o stern Rivers
.
' '
MAO SCV BOUTM MMOOC WC«T UCMCS «.CMC»
Chester & OhoptanK
1
1 *
»_ SOD
200
l=atui»
-------
Mercury
The median sediment mercury concentration among Maryland tributary stations was 0.08 ppm and the maximum
concentration was 0.36 ppm, found in 1989 at both the Sassafras River and the Middle River stations (Table 4,9 and
Figure 4.9). The median sediment mercury concentration in the James River was 0.16 ppm and the maximum was
4.66 ppm at station SN79, This maximum concentration was several times higher than that observed at any other
station in the James River. Ten of the James River stations had sediment mercury concentrations below the method
detection limits, and thus the minimum and median concentrations presented in Table 4.9 are overestimates.
Median sediment mercury concentrations in the Northwestern Rivers, Western Rrvers, Potomac River, Northeastern
Rivers, and James River regions exceeded the NOEL of 0.1 ppm. No measurements in Maryland exceeded the PEL of
1.4 ppm. In the James River, one observation (at SN79) exceeded the PEL. Toxic effects to aquatic biota due to the
measured sediment concentrations of mercury are not likely at any of monitored stations, with the exception of a station
in the vicinity of the Sewells Point Naval Complex in the James River.
Table 4.9. Summary statistics for mercury in tributary sediments. Concentrations are in ppm dry weight. Normalized
concentrations are dry weight concentrations divided by the fraction silt and clay particles in the sediment.
Measured
Normalized
Area Mean
N SD
Min Median Max
Mean N SD Min Median Max
All
0.15 210 0.33 0.009 0.10 4.66
MO stations 0.12 181 0.08 0.009 0.08 0.36
N.W. Rivers 0.22 13 0.07 0.099 0.23 0.36
Western R. 0.17 27 0.08 0.038 0.16 0.31
PatuxentR. 0.07 15 0.02 0.038 0.06 0.11
Potomac R. 0.17 19 0.08 0.050 0.15 0,31
N.E. Rivers 0.18 20 0.10
Ches. & Chop. 0.08 19
0.33
E.Bays 0.06 16 0.02 0.047 0.05 0.11
S.E. Rivers 0.06 52 0.03 0.009 0.05 0.18
James River 0.38 29 0.85 0.08 0.16 4.66
0.050 0.17 0.36
0.03 0.034 0.07
0.56
0.18
0.26
0.28
0.08
0.22
0.27
0.15
0.12
011
210
181
13
27
15
19
20
0.13
16
52
3.69
0.17
0.09
0.26
0.03
0.14
0.21
19
0.20
0.10
0.012
0.012
0.148
0.041
0.041
0.056
0.052
0.09
0.053
0.012
0.15 51.21
0.13 1.31
0,25 0.46
0.21 1.31
0.07 0.14
0.17 0.56
0.19 0.92
0.054 0.10
0.06 0.87
0.09 0.63
3.07 29 9.44 0.12 0.65 51.21
IV-29
-------
Figure 4.9b Mercury concentrations (ppm)
in James River sediments
.00
0.-7&
o.so
0.25
o.oo
"Tidal
AAAAOF"F~H4 I F»F>F»F*F%
OTOPPPPPOPPPPO
O
OOOOOOOO
ooooooooooooo
1 .OO
o.2s
o.oo
"Transition Zone
o
o
1
o
o
1
w
o
O
1
o
1
1
1 .00
o.so
O.2S
O.OO
Lower
IZIon©
c
B
0
O.
2
A
1-1
A
O
O
1
A
M
^j
O
O
1
A
M
p*j
O
o
1
A
M
S
0
o
1
A
IM
IS4
O
^
A
S
G
O
0
1
A
S
O
•7
0
A
S
r-j
O
e
A
Figure 4.9b Summary statistics for bulk sediment concentrations of mercury in the James River. Data
presented are for individual stations. The plots represent statistics for groups of stations aggregated by
segment. The NOEL and PEL values for sediment mercury concentrations are 0.1 ppm and 1.4 ppm,
respectively (MacDonald 1993). The PEL is represented in the graphs as a dotted line, if it is within the
range of concentration values.
IV-31
-------
Figure 4.1 Oa Nickel concentrations (ppm)
in Maryland tributary sediments
o
00
90
00
Northwest Rivers
eo
fvlorthieaist Rivers
f»K
Western Rivers
C^riester & CJhiop>taril<
O
we
1 30
O
TI
*ao
F»&tuxent Rlvor
30
F»ot<»m&c River
O
K
120
•0
East Bays
Southeast Rivera
I I I ' • | I * I I
MATWMN TIO^M
Figure 4,lOa Summary statistics for bulk sediment concentrations of nickel in Maryland's Chesapeake Bay
tributaries, in parts per million. The box and whisker plots illustrate the median (central horizontal line),
quart'les (extent of rectangle), and ranges (extent of vertical lines) in data collected from each station or
river segment There were insufficient data for development of NOEL and PEL concentrations for sediment
concentrations of nickel. Long and Morgan (1990) ER-L and ER-M concentrations for sediment nickel
concentrations are 30 ppm and 50 ppm, respectively.
IV-33
-------
Zinc
The median sediment zinc concentration among Maryland tributary stations was 146 ppm and the maximum
concentration was 525 ppm at the Magothy River station in 1986 (Table 4.11 and Figure 4.11). Within the Jame; River,]
the median and maximum zinc concentrations were 103 and 364 ppm, respectively (Table 4.11 and Figure 4.11 r As
for most trace metals, the highest sediment concentrations of zinc were found at the two stations in the vicinity o
Sewells Point Naval complex, but the difference between the concentrations at these two station and the other J imes
River stations was not as great as with many of the other trace metals.
All Maryland tributary stations had median zinc concentrations near or above the NOEL of 68 ppm. In Maryland
median zinc concentrations exceeded the PEL of 300 ppm in the Magothy and Severn Rivers, and individual
measurements above the PEL were also observed in the Northeast, Middle and South rivers. Median sediment dnc
concentrations in all three segments of the James River were above the NOEL, but the PEL was exceeded only at the
two stations near Sewells Point Naval Complex. Toxictty to aquatic biota due to the measured sediment zinc
concentrations is not likely at the tributary stations monitored, except for the Magothy and Severn River stations, is well
as the stations in the James River near the Sewells Point Naval Complex.
Table 4.11. Summary statistics for zinc in tributary sediments. Concentrations are in ppm dry weight.
Normalized concentrations are dry weight concentrations divided by fraction silt and clay particles in thi
sediment..
Measured
Normalized
Area
Mean N SD Min Median Max
Mean
N
SD Min Median Max
All
158 209 92 18
139
MD stations 162 180 92 24 146
525
525
N.W. Rivers
Western R.
Patuxent R.
Potomac R.
N.E. Rivers
Ches. & Chop.
E. Bays
S.E. Rivers
232
306
150
192
204
117
108
80
13
27
14
19
20
19
16
52
49
92
27
34
60
34
30
28
173
184
99
131
87
29
64
24
216
289
146
192
192
114
101
77
315
525
193
272
354
174
170
160
James River 128 29 88 18
103
364
299 209 403 48 203 4000
240 180 224 59 192 2431
279
491
174
244
277
180
203
134
665
13
27
14
19
20
19
16
52
81
419
23
97
77
83
295
61
182
213
144
146
174
93
76
59
281
386
168
217
249
156
123
117
438
2431
221
581
461
463
.1297
410
29 851
48
413 4000
IV-35
-------
Figure 4.11 b Zinc concentrations (ppm)
in James River sediments
eoo
200
Tida.l
A A A A D F F
C C l-l T S C F
O T O O O O O
O O O O O O O
1 O 1 1 1 11
A 1 A A A A A
8OOOOO
O O O O O
O
O
O
O
eoo
- aoo
0.
I/I
Transition
o
o
O
O
1
w
o
o
1
o
1
1
eoo
-too
200
Lower Estuarine
lone
C
e
0
o
2
A
n
A
O
O
1
A
H
.J
O
O
A
1— I
r>j
O
o
1
A
n
S
o
o
1
A
CM
IM
o
1
•7
A
S
C
o
o
*
S
rvl
O
e
A
S
IM
O
1
A
Figure 4.11 b Summary statistics for bulk sediment concentrations of zinc in the James River. Data
presented are for individual stations. The plots represent statistics for groups of stations aggregated by
segment. NOEL and PEL values for sediment zinc concentrations are 68 and 300 ppm, respectively. The
PEL is represented in the graphs as a dotted line, if it is within the range of concentration values.
IV-37
-------
NORTHWEST RIVER
90
91
Bush River
89
90
91
Gunpowder
River
87 88 89 90 91
Middle River
CHROMIUM
Yearly measurements
of chromium concentration
in sediments (ppm).
PEL=240
Chromium in Sediment
-------
NORTHWEST RIVERS
70-
60
50
40r
30,r
20:
10;
0
n
70-
60}
50;
40
20f
10
86 89 90 91
Bush River
n n
88 89 90 91
Gunpowder
River
87 88 89 90 91
Middle River
ARSENIC
Yearly measurements
of arsenic concentration
in sediments (ppm).
PEL=64
Arsenic Sediment
-------
NORTHWEST RIVERS
0.4
0.3
0.2
0.1
0
n n
88 89 90 91
Gunpowder
River
MERCURY
Yearly measurements
of mercury concentration
in sediments(ppm).
PEL= 1.4
Mercury in Sediment
-------
NORTHWEST RIVERS
100
80
60
40
20
0
100
80
60
40
20
88
89
90
91
11 n I
Bush River
88
89
90 91
Gunpowder
River
87 88 89 90 91
Middle River
COPPER
Yearly measurements
of copper concentration
in sediments(ppm).
PEL=270
Copper in Sediment
-------
Figure 4.13 Distribution of metals in the Southeastern Rivers and bays. (Next 8 pages)
A. Arsenic
B. Cadmium
C. Chromium
D, Copper
E. Lead
F. Mercury
G. Nickel
H. Zinc.
A/-38.1
-------
SOUTHEASTERN
RIVERS & BAYS
88
Upper
Nanticoke
River
89 90 91
30[
25
20
15'
10
mil
Lower
Nanticoke
River
ARSENIC
Yearly measurements
of arsenic concentration
in sediments (ppm).
PEL=64
(Mean
• •!
Anenc m StOmrt
86 87 88 89 90 91
Fishing Bay
North Tangier Sound
X*
35
30
25
20
15
10
5
0
mm
86 87 88 89 90 91
South Tangier Sound
35r
30
25
20
Wicomico
River
87 88 89 90 91
Big Annemesex River
35;
30
2
Pocomoke River
15!
1
n
86 87
89 90 91
8E 87 88 89 SO
86 89 90 91
-------
-------
SOUTHEASTERN
RIVERS & BAYS
100.
NX
80
60
40
80
CO
40
20
Ill
89 90 91
CHROMIUM
Yearly measurements
of chromium concentration
in sediments (ppm).
PEL=240
li i
= :B i
!•-"-• i-
Chfontum m Sediment
86 87 88 89 $0 91
100
80
60
40
Upper
Nanticoke
River
11 n m
86 87 88 89 90 91
Lower
Nanticoke
River
Fishing Bay
Wicomico
River
North Tangier Sound
100
80
60
40
20
0
86 87 BS 89 90 91
Big Annemesex
River
rmn
86 87 88 89 90 91
100.
South Tangier Sound
Pocomoke River
86 87 88 83 90 91
100
80
60
40
i-run
86 S3 90 91
10ft-
80
60
40-
20
Pocomoke Sound
mn
66 67 88 83 90 91
100
80
GO
40
20
n n
-------
SOUTHEASTERN
RIVERS & BAYS
LEAD
Yearly measurements
of arsenic concentration
m sediments (ppm)
PEL=160
Manokin f liver
^*
North Tangier Sound
zoo
150
100
so
87 88 89 90 91
BigAnnemese> River
n
200.
150|
100
86 87 88 89 90 91
South Tangier Sound
87 88 89 :0 91
\
\ Pocomoke Sound
BE 87 88 89 90 91
"these values ma> have
resulted from con!; Tiinaton,
-------
SOUTHEASTERN
RIVERS & BAYS
NICKEL
Yes
Of r
in s
|
i
$
m
rfy measurements
ickel concentration
ediments (ppm).
ER-M=51.6
Itlttn
-" - .
Nttel in Segment
50
88 89 SO 91
Upper
North Tangier Sound
/*
66 B? 88 89 90 91
-------
Figure 4.14 Distribution of metals in the Northeast Rivers. (Next 8 pages)
A. Arsenic
B. Cadmium
C. Chromium
D. Copper
E. Lead
F. Mercury
G. Nickel
H. Zinc.
IV-38.2
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
Figure 4.15 Distribution of metals in the Eastern bays. (Next 8 pages)
A. Arsenic
B. Cadmium
C. Chromium
D. Copper
E. Lead
F. Mercury
G. Nickel
H. Zinc.
'V-38.3
-------
-------
EASTERN BAYS
86 87 88 89 90 91
8? 88
90 91
60
50
40
30
Choptank Embayment
Little
Choptank
River
m n
87 88 89 90 91
ARSENIC
Yearly measurements
of arsenic concentration
in sediments (ppm).
PEL=64
Arsenic in Sediment
-------
EASTERN BAYS
86 87 88 89 90 91
Choptank Embayment
Little
Choptank 5
River
88
89
90
91
CADMIUM
Year!
ofca
inse
1
1
•
y measurements
dmium concentration
diments (ppm),
PEL=7.5
IMean
. ..
Cadmium in Sediment
-------
EASTERN BAYS
86 87 88 89 90 91
88 89 90
91
Choptank Embayment
Little
Choptank
River
88
89
90 91
CHROMIUM
Yearly measurements
of chromium concentration
in sediments (ppm).
PEL=240
1
-------
EASTERN BAYS
35
86 87 88 89 90 91
30
25
20
15
10
87
88
89
90
91
87
COPPER
Yearts
ofcoi
in sec
I
s
i
I
•
> measure-rents
>per concentration
iments{ppni).
PEL=170
§...- .
- ..
&»««••> Mmm
-------
EASTERN BAYS
86 87 88 89 90 91
50
40
30
"I
10,
87 88 89 90 91
Choptank Embayment
Little
Choptank
River
87 88 89 90 91
LEAD
Yearly measurements
of lead concentration
in sediments (ppm).
PEL=160
1
Lead in Sedimerx
-------
EASTERN BAYS
86 87 88 89 90 91
0.12
0.10
0.08
0.06
0.041
0.021
o'
87 88 89 90 91
0.12
0.10
0.08
0.06
0.04J
0.02
0
Choptank Embayment
Little
Choptank
River
87
88
89
90
91
MERCURY
Year
of mi
inse
1
s
I
I
m
ly measurements
ereury concentration
diments (ppm).
PEL=1.4
|Me*n
- --
Mercury in Se«menl
-------
EASTERN BAYS
86 87 88 89 30 91
Choptank Embayment
87 88 89 $0 91
NICKEL
Yea
o'n
in si
s
•m
2
8
!
•
fly measurements
ickel concentration
idiments(ppm).
ER-M=51.6
|....^n
- ..
N
-------
EASTERN BAYS
86 87 88 89 90 91
87 88 89 90 91 Choptank
SO
200
150
100
so
87 88 89 90 91
Yearly measurements
of zinc concentration
in sediments (ppm).
PEL=300
Zinc tn Sediment
-------
Figure 4.16 Distribution of metals in the Patuxent River. (Next 8 pages)
A. Arsenic
B. Cadmium
C. Chromium
D. Copper
E. Lead
F. Mercury
G. Nickel
H. Zinc.
IV-38.4
-------
PATUXENT
N
^
80
60
40
20
I I
PI
87 88 89 90 91
ARSENIC
Yearly measurements
of arsenic concentration
in sediments (ppm).
PEL=64
Arsenic in Sediment
-------
PATUXENT
/
CADMIUM
Yearly measurements
of cadmium concentration
in sediments (ppm).
87 88 89 90 91
87 88 89 90 91
87 88 89 90 S1
-------
r
PATUXENT
CHROMIUM
Yearly measurements
of copper concentration
in sediments (ppm).
88 89 90 91
Illll
87 88 89 90 91
88 89 90 91
-------
PATUXENT
COPPER
Year
of cc
in se
1
If
I
€
S.
m
ly measurements
ipper concentration
diments (ppm).
PEL=170
• Mean
Copper in Sediment
87 88 89 90
-------
PATUXENT
87 88 89 90 91
LEAD
Yearly measurements
of lead concentration
in sediments (ppm).
PEL=160
c
o
Lead in Sediment
88 89 90 91
88 89 90 91
-------
PATUXENT
n
87 88 89 90 91
MERCURV
Yearly measurements
of mercury concentration
in sediments (ppm).
PEL=1.4
Mercury in Sediment
m n
87 88 89 90 91
0.20
0.15
0.10
0.05
0
87 88 89 90 91
-------
PATUXENT
s
NICKEL
Yea
of n
in s
i
i
I
£-
S
m
rty measurements
ickel concentration
ediments(ppm).
ER-M=51.6
|Me*n [
_ »!"
Nickel in Sediment
-------
PATUXENT
88 89 90 91
87 88 89 90 91
ZINC
Yea
of z
in se
1
a-
€
£
•
riy measurements
nc concentration
jdiments{ppm).
PEL=300
• Mean
i^IjUL
Zinc in Sediment
87 88 89 90 91
-------
Figure 4,17 Distribution of metals in the Potomac River. (Next 8 pages)
A. Arsenic
B. Cadmium
C. Chromium
D. Copper
E. Lead
F. Mercury
G. Nickel
H. Zinc.
'V-36.5
-------
-------
POTOMAC
RIVER
ARSENIC
Yearly measurements
of arsenic concentration
in sediments (ppm).
PEL=64
• Arsenic in Sediment
35
30
25
20
15
10
5
0
86 87 86 89
-------
POTOMA
RIVERl
2.0
1.5
1.0
89 90
87 88 89 90 91
87 88 89 90 91
CADMIUM
Yearly measurements
of cadmium concentration
in sediments (ppm).
PEL=7.5
Cadmium in Sediment
2.0
1.5
1.0
0.5
0
rrn
86 87 88 89 90 91
-------
POTOMAC
RIVER
87 88 89 90 91
87 66 89 90 91
CHROMIUM
Yearly measurements
of chromium concentration
in sediments (ppm).
PEL=240
Chromium in Sediment
87 88 69 89 90 91
-------
POTOMA
RIVER
•V
-/:
87 88 89 90 91
87 88 89 90 91
COPPER
Yearly measurements
of copper concentration
in sediments (ppm).
PEL=170
Copper in Sediment
86 87 88 89 90 91
-------
80
60
40.
20
0
87 88 89 90 91
LEAD
Yearly measurements
of lead "concentration
in sediments (ppm).
PEL=160
Lead in Sediment
POTOMAC
RIVER
nra
86 87 SB 89 90 91
87 88 89 90 91
-------
POTOMAC
RIVER
MERCURY
Yearly measurements
of mercury concentration
in sediments (ppm).
PEL=1.4
Mercury in Sediment
1.0
0.8
0.6
0.4
0.2
0
86 87 88 89 90 91
-------
POTOMAC
RIVER
87 88 89 90 91
87 88 89 90 91
NICKEL
Yearly measurements
of nickel concentration
in sediments (ppm).
ERM=51.6
Nickel in Sediment
-------
-------
Figure 4,18 Distribution of metals in theChester and Choptank Rivers. (Next 8 pages)
A. Arsenic
B. Cadmium
C. Chromium
D. Copper
E. Lead
F. Mercury
G. Nickel
H. Zinc.
'V-38.6
-------
-------
CHESTER AND CHOPTANK
86 87 88 89 90 91
ARSENIC
Yearly measurements
of arsenic concentration
in sediments (Ppm).
PEL=64
Arsenic in Sediment
-------
CHESTER AND CHOPTAN
II
87 88 89 90 91
CADMIUM
Yearly measurements
of cadmium concentrate >n
in sediments(ppm).
PEL-7.4
Cadmium in Sediment
-------
Nickel
The median sediment nickel concentrations in Baltimore Harbor and Back River were 46 pprn and 113
ppm, respectively (Table 5.9 and Figure 5.10a). The maximum sediment nickel concentration in the region
was 127 ppm in Back River observed in 1987 (Table 5.9). Due to a relative lack of data on the toxicity of
sediment nickel concentrations, reliable sediment quality guidelines for nickel are not available (Long, et at.,
1990)
There has been little change in the past two decades in sediment nickel concentrations in the Harbor
(Figures 5.10b-c). This suggests that either nickel loads to the Harbor area have not declined substantially
in this period or that the behavior of nickel in sediments differs from that of the other trace metals. Nickel
concentrations did not show as much spatial variability as the other trace metals in the 1973 study (Villa and
Johnson, 1974), suggesting diffuse rather than point source inputs.
Table 5.9 Summary statistics for nickel in Baltimore Harbor region sediments. Concentrations are in ppm
dry weight. Normalized values are dry weight values divided by percent fine grained sediment. Statistics on
data from the nine stations within the Baltimore Harbor were calculated with the stations aggregated in
terms of the three arrays of stations which lie across the channel and parallel to the Key Bridge (zero, one,
and two transects). These stations were also aggregated based on whether they are north of the central
dredged channel (NORTH), adjacent to the channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SO Min Median Max Mean N SO Min Median Max
Baltimore Harbor
All 49 41 13
Center
North
South
Zero
One
Two
49 15 17
47 13 10
53 13 12
46 13 12
49 16 11
54 12 16
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
42
42
55
50
48
48
55
52
57
5
4
4
6
5
5
4
4
4
12
3
15
14
12
8
25
11
12
Back River
MWT4.1
113 5
30
30
37
36
34
30
39
34
37
44
30
37
36
39
39
49
104
46
43
43
51
43
48
50
37
42
49
50
42
50
44
52
52
113
93
93
65
78
78
70
93
64
45
78
70
64
58
93
65
74
127
63 41 19
56 15 18
61 13 20
73 13 18
56 13 17
68 16 23
64 12 15
47
52
72
61
67
76
59
63
70
5
4
4
6
5
5
4
4
4
13
11
17
17
29
24
23
10
14
138 5 36
37
37
44
50
37
44
46
37
44
50
44
47
52
46
54
60
111
56 118
49
56
68
49
56
63
41
47
75
56
56
83
49
62
65
93
118
109
90
118
93
68
68
90
87
118
109
93
75
91
120 198
V-29
-------
Figure 5.1Oa Nickel concentrations (ppm)
in Back River and Baltimore Harbor Sediments
I. OeUtimoi-e Harfc>or Stations
1 OO
I j } f
o
«M
1
JM
2
rsi
II.
1 S>0
1OO
III- Transocrts XKc^rcass
oo
Two
Figure 5.Ida Nickel concentrations in sediment in Baltimore Harbor and Back River. The box
and whisker plots illustrate the median (central horizontal line), the quartiles (extent of the
rectangle), and ranges (extent of vertical fines) of the data. The Baltimore Harbor stations in I.
are aggregated by their location relative to the central dredged channel in II. and III. The
NOEL and PEL values for sediment nickel concentrations are unavailable due to insufficient
data {MacDonald, 1993).
V-30
-------
Figure 5.1 Ob Nickel in Baltimore Harbor Sediments
1973v. 1991
OC ON
IS 1C IN
Station Location
2S 2C 2N
1973 pill991
Figure 5.1 Ob Nickel concentrations in Baltimore Harbor sediments in 1991 (this report)
compared to concentrations found in 1973 at nearby locations (Villa and Johnson, 1974).
V-31
-------
Figure 5.1 Oc Nickel in Baltimore Harbor Sediments
1981 v. 1991
o
£
80
60
40
20
Increasing distance from mouth of Patapsco R.
1981 OH 1991
Figure 5.10c Nickel concentrations in Baltimore Harbor sediments in 1991 (this report;
compared to concentrations found in 1981 at nearby locations as well as other stations withtr
the dredged channel {Helz et al.. 1983).
V-32
-------
Zinc
The median sediment zinc concentrations in Baltimore Harbor and Back River were 413 ppm and 682 ppm,
respectively. The maximum concentration in the region, found in 1987 at station MWT5.1N in Baltimore
Harbor in 1987, was 937 ppm (Table 5.10 and Figure 11 a). Although the maximum zinc concentration was
found in Baltimore Harbor, the median concentration of zinc was higher in the Back River than at any of the
Harbor stations. All stations had median zinc concentrations which exceeded both the NOEL and PEL
concentrations of 68 and 300 ppm, respectively. Toncrty to aquatic biota due to the measured sediment
zinc concentrations is likely at all monitored stations in the Baltimore Harbor region, and is most likely at the
Back River station.
Comparison'of appropriate 1991 data with that from earlier studies shows that zinc concentrations in the
Baltimore Harbor have declined significantly in the past two decades (Figures 5.9b-c). The average zinc
concentration in 1973 in the Outer Harbor was 710 ppm, and average concentrations were several times
higher than this in Colgate Creek, Bear Creek and Old Road Bay (Villa and Johnson, 1974).
Table 5.10 Summary statistics for zinc in Baltimore Harbor region sediments. Concentrations are in ppm
dry weight. Normalized values are dry weight values divided by percent silt and clay. Statistics on data
from the nine stations within the Baltimore Harbor were calculated with the stations aggregated in terms of
the three arrays of stations which fie across the channel and parallel to the Key Bridge (zero, one, and two
transects). These stations were also aggregated based on whether they are north of the central dredged
channel (NORTH), adjacent to the channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SO Min Median Max Mean N SO
Min Median Max
Baltimore Harbor
All 451 41 133
Center
North
South
Zero
One
Two
Back River
MWT4.1
359 15 64
483 13 165
524 13 99
404 13 82
443 16 152
510 12 138
256
256
328
377
256
297
311
413
343
413
497
413
405
531
937
492
937
750
497
937
750
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
353
381
492
372
499
473
346
565
620
5
4
4
6
5
5
4
4
4
86
43
5
63
245
97
43
57
94
256
328
484
297
369
377
311
523
527
343
388
493
353
399
422
336
543
601
492
418
497
454
937
594
401
649
750
589 41 262 268 535 1722
417 15 93 268
649 13 354 365
727 13 179 522
504 13 184 268
634 16 336 357
621 12 217 334
391 654
562 1722
686 1047
450 980
557 1722
601 1021
393
476
672
464
742
730
379
707
778
5
4
4
6
5
5
4
4
4
98
130
214
108
551
185
31
145
173
268
365
522
357
423
559
334
587
611
361
438
593
454
556
686
389
676
740
526
664
980
654
1722
1047
404
887
1021
681 5 27
638 682
708
831 5 210
684
735 1197
V-33
-------
Figure S.*I1ai Zinc concentrations (ppm)
in Back River and Baltimore Harbor Sediments
I. Baltimore I—larfc>or Stations
t OOO
soo
2SO
_J. JLJ i
O
rsi
1 1
C S
2
C
II
1 OOO
Trans
->oo
2 SO
IMOFRTM
III.
1 OOO
T~rs»ns^crts XXcross
soo
29O
Two
Figure 5.1 la Zinc concentrations in sediment in Baltimore Harbor and Back River. The box ar d
whisker plots illustrate the median (central horizontal line), the quartiles (extent of the rectangk •),
and ranges (extent of vertical lines) of the data. The Baltimore Harbor stations in I. ae
aggregated by their location relative to the central dredged channel in II. and III. The NO -L
and PEL values for sediment zinc concentrations are 68 ppm and 300 ppm, respectiv« fy
(MacDonald, 1993). The PEL is represented in the graphs as a dotted line, if it is within tie
range of concentration values.
V-34
-------
Figure 5.11 b Zinc in Baltimore Harbor Sediments
1973v. 1991
1600
o 1200
£
IS 1C IN
Station Location
2N
1973 RH 1991
Figure 5. lib Zinc concentrations in Baltimore Harbor sediments in 1991 (this report) compared
to concentrations found in 1973 at nearby locations (Villa and Johnson. 1974).
V-35
-------
Figure 5.1 Ic Zinc in Baltimore Harbor Sediments
1981 v. 1991
c
o
700
600
500
400
300
200
100
0
Increasing distance from mouth of Patapsco R.
198lHIl991 I
1
Figure 5.1 Ic Zinc concentrations in Baltimore Harbor sediments in 1991 (this report) compared
to concentrations found in 1981 at nearby locations as well as other stations within the
dredged channel (Hefe et al., 1983).
V-36
-------
Summary of Sediment Trace Metal Concentrations in Baltimore Harbor and Back River
Sediment trace metal concentrations at the sediment contaminant monitoring stations in Baltimore Harbor
and Back River were generally markedly higher than those observed elsewhere in the Bay, except for the
Anacostia and Elizabeth Rivers. The Baltimore Harbor region had the highest measurements of sediment
concentrations of chromium, lead, and zinc, and the region's maximum sediment concentrations of the
other trace metals approached the maximum concentrations found Baywide. Annual measurements of
trace metal concentrations in this region are shown in Figures 5.12a-h.
Within Baltimore Harbor, median sediment zinc concentrations exceeded the PEL concentration at all nine
stations, and average sediment chromium concentrations exceeded the PEL concentration at six of nine
stations (Figure 5.l2c). Median sediment lead concentrations were above the PEL concentration at one
station (Figure 5.12e). All trace metals, with the exception of cadmium, occurred at average concentrations
exceeding the NOEL concentrations at some or all of the Baltimore Harbor stations.
Mean sediment concentrations of cadmium, lead, and nickel were markedly higher at the Back River station
compared to the Baltimore Harbor stations, and markedly lower for arsenic, while for most other trace
metals, mean concentrations in the Back River and Baltimore Harbor were comparable to one another
(Figures 5.l2a-h). In Back River, four metals— chromium, lead, and zinc —were found at average
sediment concentrations exceeding their PEL values (Figures 5.12c-e and 5.12h).
V-37
-------
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-------
Spatial Distribution of Individual Polycyclic Aromatic Hydrocarbons
Anthracene
The median sediment anthracene concentrations in Baltimore Harbor and Back River were 170 ppb and 82
ppb, respectively (Table 5.11). The region's maximum concentration of 926 ppb was found at station
MWT5.2N in Baltimore Harbor in 1991 (Table 5.11 and Figure 5.13).
The median concentration exceeded the NOEL concentration of 85 ppb at seven of the nine stations in
Baltimore Harbor, but only the single measurement at station MWT5.2N in Baltimore Harbor was in excess
of the PEL of 740 ppb (Table 5.11). Note that only one measurement is available for six of the nine
stations. Toxic effects to aquatic biota due to the measured concentrations of anthracene in the sediment
are not likely at the monitored areas in the region, with the exception of station MWT5.2N in Baltimore
Harbor.
Tabie 5.11 Summary statistics for anthracene in Baltimore Harbor region sediments. Normalized
concentrations are measured concentrations divided by the sediment's fraction total organic carbon.
Concentrations are in parts per billion. Statistics on data from the nine stations within the Baltimore Harbor
were calculated with the stations aggregated in terms of the three arrays of stations which lie across the
channel and parallel to the Key Bridge (zero, one, and two transects). These stations were also
aggregated based on whether they are north of the central dredged channel (NORTH), adjacent to the
channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SD
Min Median Max
Mean N SD
Min Median Max
Baltimore Harbor
All 221 13
Center
North
South
Zero
One
Two
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
Back River
MVVT4.1
172
352
144
192
121
458
181
263
143
160
119
31
190
926
257
82
6
4
3
4
6
3
2
1
1
3
2
1
1
1
1
2
243
154
393
113
91
156
407
131
225
87
27
27
47
31
88
27
190
170 926
139
217
143
203
40
257
419
926
257
273
419
926
88
263
143
27
47
31
190
926
257
181
263
143
33
109
31
190
926
257
273
263
143
419
170
31
190
926
257
5590 13 7180 810 4420 28060
3650 6 2830 810
10180 4 12170 1120
3340 3 2510 820
5270 4 2790 2450
2100 6 1840 810
13000 3 13040 5110
5290 2 4020 2450
7140 1 . 7140
3360 1 . 3360
2070 3 2110 810
2770 2 2330 1120
. 820
. 5110
. 28060
. 5850
3480 8130
5780 28060
3360 5850
5250 8130
1110 4520
5850 28060
820 1
5110 1
28060 1
5850 1
5290
7140
3360
900
2770
820
5110
28060
5850
8130
7140
3360
4520
4420
820
5110
28060
5850
8
76
82
88
1440 2 80 1380 1440 1490
V-48
-------
Figure 5.13 Anthracene concentrations (ppb)
in Daek River and Baltimore Harbor Sediments
I. BeUtlmoro
1 OOOi
Msartoor Stations
soo
a: so
o
M
Oil
SMC
5t 2
IM C
II. Transects Along Channel
1 OOO-
soo
III. Treir-is^ots XVc=ross Otianrtol
ooo<
soo
290
OINE
TWO
Figure 5.13 Anthracene concentrations in sediment in Baltimore Harbor and Back River. The
box and whisker plots illustrate the median (central horizontal line), the quartiles (extent of the
rectangle), and ranges (extent ot vertical lines) of the data. If there are less than four values,
the rectangle's bottom and top show the range. A dash indicates only a single value is
available. The Baltimore Harbor stations in I. are aggregated by their location relative to the
central dredged channel in II. and III. The NOEL and PEL values for sediment anthracene
concentrations are 85 ppb and 740 ppb, respectively (MacDonald, 1993). The PEL is
represented in the graphs as a dotted line, if it is within the range of concentration values.
-------
Benzofajanthracene
Benzo[ ajanthracene is a Chesapeake Bay Toxic of Concern (Chesapeake Bay Program, 1991 a). The
median sediment concentrations of benzo[a]anthracene were 271 ppb and 229 ppb in Baltimore
Harbor and Back River, respectively (Table 5.12). The maximum sediment concentration, found in
Baltimore Harbor at station MWT5.2N in 1991, was 1902 ppb (Table 5.12 and Figure 5.14).
Sediment concentrations of benzo[ajanthracene above the NOEL concentration of 160 ppb were
observed at all but one station in the Baltimore Harbor region (Table 5.12). Measured concentrations
exceeded the PEL concentration of 1300 ppb only at station MWT5.2N in Baltimore Harbor. Toxic
effects to aquatic biota due to the measured concentrations of benzo[a]anthracene in the sediment are
not likely at the monitored areas in the Baltimore Harbor region with the exception of station
MWT5.2N in Baltimore Harbor.
Table 5.12 Summary statistics for benzo[a]anthracene in Baltimore Harbor region sediments. Normalized
concentrations are measured concentrations divided by the fraction total organic carbon in the sediment.
Concentrations are in parts per billion. Statistics on data from the nine stations within the Baltimore Harbor
were calculated with the stations aggregated in terms of the three arrays of stations which lie across the
channel and parallel to the Key Bridge (zero, one, and two transects). These stations were also
aggregated based on whether they are north of the central dredged channel (NORTH), adjacent to the
channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SO
Min Median Max
Mean N SD
Min Median Max
Baltimore Harbor
All 504 13 528
Center 419 6 428
North 808 4 771
South 268 3 174
Zero 337 4 137
One 430 6 475
Two 874 3 894
201
635
436
MWT5.0C
MWT5.0N
MWTS.OS
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
336
428
250
524
452
104
271
1902
450
2
1
1
3
2
1
1
1
1
Back River
MWT4.1 229 2
93 271 1902 12360 13 14520 2770 7300 57630
93 249 1253 8230 6 4620 2780 6730 14230
144 594 1902 23100 4 23960 3440 15670 57630
104 250 450 6290 3 3750 2770 5880 10230
194 339 478 9280 4 4340 5400 8730 14230
93 185 1253 8060 6 7020 2770 4800 19740
271 450 1902 25050 3 28250 7300 10230 57630
194
429
250
93
144
104
271
1902
450
336
428
250
226
452
104
271
1902
450
478
428
250
1253
760
104
271
1902
450
9820
11590
5880
7480
11590
2770
7300
57630
10230
2
1
1
3
2
1
1
1
1
6240
.
5470
11520
.
f
r
_
5400
11590
5880
2780
3440
2770
7300
57630
10230
9820
11590
5880
6160
11590
2770
7300
57630
10230
14230
11590
5880
13490
19740
2770
7300
57630
10230
73
178 229
281
3990 2 1080 3230 3990 4750
V-50
-------
Figure 5.1-4 Benzo(a)anthraoene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
I. Baltimore I—lartoor
2OOO'
1 BOO
1 OOO
SOO
A
O
tsi
O
c
II. Transects Along
zooo-
soo
„ 1 OOO
III. Trt
2 OOO.
1 600
CENTER
isects Across
nooo
soo
orsie
TWO
Figure 5.14 Benzo(a}anthracene concentrations in sediment in Baltimore Harbor and Back
River. The box and whister plots illustrate the median (central horizontal line), the quartites
(extent of the rectangle), and ranges (extent of vertical lines) of the data. If there are less than
four values, the rectangle's bottom and top show the range. A dash indicates only a single
value is available. The Baltimore Harbor stations in I. are aggregated by tneir location relative
to the central dredged channel in II. and III. The NOEL and PEL values for sediment
benzo(a)anthracene concentrations are 160 ppb and 1300 ppb. respectively (MacDonald.
1993). The PEL is represented in the araphs as a dotted line, if it is within the range of
concentration values.
V-51
-------
Benzo[b]fluoranthene
The median sediment concentrations of benzo[b]fluoranthene were 543 ppb and 313 ppb in Baltimore
Harbor and Back River, respectively (Table 5.13 and Figure 5.15). The maximum concentration of
3003 ppb was found at the MWT5.2N station in the Baltimore Harbor in 1991. There were
insufficient data available for the development of NOEL and PEL guidelines for benzo[b]fluoranthene
(MacDonald, 1993).
Table 5.13 Summary statistics for benzo[b]fluoranthene in Baltimore Harbor region sediments.
Normalized concentrations are measured concentrations divided by the fraction total organic carbon in the
sediment. Concentrations are in parts per billion. Statistics on data from the nine stations within the
Baltimore Harbor were calculated with the stations aggregated in terms of the three arrays of stations which
lie across the channel and parallel to the Key Bridge (zero, one, and two transects). These stations were
also aggregated based on whether they are north of the central dredged channel (NORTH), adjacent to the
channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SO
Min Median Max
Mean N SD
Min Median Max
Baltimore Harbor
All 759
Center 595
North 1221
South 472
Zero
One
Two
560
558
1428
Back River
MWT4.1
13 777 172 543 3003 18970 1322520 4680 14590 91000
6 525
41216
3 283
4 180
6 576
31367
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
508
724
499
671
580
176
543
3003
740
2
1
1
3
2
1
1
1
1
248
.
.
801
439
.
f
t
172 437 1594 12200 66100 5150 1192020330
269 807 3003 35040 437990 6440 21370 91000
176 499 740 11080 36090 4680 1175016810
332 591 724 15240 4 5570 9250 15680 20330
172 258 1594 10540 6 7710 4680 6570 23120
543 740 3003 40800 343490 14590 16810 91000
332
724
499
172
269
176
540
3003
740
508
724
499
246
580
176
543
3003
740
683
724
499
1594
890
176
543
3003
740
14790
19620
11750
9670
14780
4680
14590
91000
16810
2
1
1
3
21
1
1
1
1
7840
6530
1800
9250
19620
11750
5150
6440
4680
14590
S1000
15510
14790
19620
11750
6700
14780
4680
14590
91000
16810
20330
19620
11 750
17160
'23120
4680
14590
91000
16810
313
2 83 . 254
313
372 5450 21190 4510 5450 6290
V-52
-------
Figure 5.16 Benzo(k)fluoranthene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
I. Baltimore* I—Isart^or Stations
i eoo-
1 200
000
.4.00
eoo
A IM C
K
fsi C S
S 2
II. Tra.nsocts Along Channel
oo-
200
aoo
too
SOUTM
III. Trsu-isocts /Vcross
i eoo-
n 200
eoo
ONE
TWO
Figure 5.16 Benzo{k)fluoranthene concentrations in sediment in Baltimore Harbor and Back
River. The box and whisker plots illustrate the median (central horizontal line), the quartites
(extent of the rectangle}, and ranges (extent of vertical lines) of the data. If there are tess than
four values, the rectangle's bottom and top show the range. A dash indicates only a single
value is available. The Baltimore Harbor stations in I. are aggregated by their location relative
to the central dredged channel in II. and III. The NOEL and PEL values for sediment
benzo(k)fluoranthene concentrations are not available due to insufficient data (MacDonaJd,
1993).
V-53
-------
Benzo[k]fiuoranthene
The median sediment concentrations of benzolkjfluoramhene in Baltimore Harbor and Back River
were 303 ppb and 89 ppb, respectively (Table 5.14). The region's maximum concentration of 1351
ppb was found at station MWT5.2N station in Baltimore Harbor in 1991 (Table 5.14 and Figure
5.16). There were insufficient data available for the development of NOEL and PEL guidelines for
benzo[k]fluoranthene (MacDonald, 1993).
Table 5.14 Summary statistics for benzofkjfluonuitbene in Baltimore Harbor region sediments. Normalized
concentrations are measured concentrations divided by the fraction total organic carbon in the sediment.
Concentrations are in parts per billion. Statistics on data from the nine stations within the Baltimore Harbor were
calculated with the stations aggregated in terms of the three arrays of stations which lie across the channel and
parallel to the Key Bridge (zero, one, and two transects). These stations were also aggregated based on whether they
are north of the central dredged channel (NORTH), adjacent to the channel (CENTER), or south of the channel
(SOUTH). A ".* means no data is available for that station.
Measured
Normalized
Area
Mean N SD
Min Median Max
Mean N SD Mb Median Max
All
Center
North
South
Zero
One
Two
489
414
688
303
274
614
621
8 394
3
3
2
318
582
26
3 11
2 232
3 636
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
273
263
285
778
450
^
1
1
1
1
1
0
190
190
263
285
263
450
190
303
273
450
303
273
614
322
1351
778
1351
322
285
778
1351
11930
7210
19920
7010
7330
10030
17790
8 11880 5110 7720 40950
3 1820 5110
3 18350 7140
273
263
285
778
450
273
263
285
778
450
273
263
285
778
450
8130
7140
6710
8380
11690
8130 8380
11690 40950
2 420 6710 7010 7310
3 730 6710 7140 8130
2 2340 8380 10030 11690
3 20090 5110 7310 40950
. 8130 8130 8130
. 7140 7140 7140
. 6710 6710 6710
. 8380 8380- 8380
. 11690 11690 11690
MWTS.2C
MWT5.2N
MWT5.2S
Rafl- PIv»T
MWT4.1
190
1351
322
89
190 190 190 5110 1 . 5110 5110 5110
1351 1351 1351 40950 1 . 40950 40950 40950
321 322 322 7310 1 . 7310 7310 7310
89 89 89 1610 1 . 1610 1610 1610
V-54
-------
Figure G.I 5 Benzo(b)fluoranthene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
I. Baltimore* Hsartoor Stations
•*ooo-
.3OOO
2000
1 OOO
p o o i i i 2 ;»a~
"CSNCSNCS
II.
t-OOO
— 3OOO
«,. 2OOO
i i ooo
Transects Along Cnannot
cerwrcR
III. Tr^ns^cts X\cross
SOLJTM
3OOO
2OOO
1000
ZERO
TWO
Figure 5.15 Benzo(b)fiuoranthene concentrations in sediment in Baltimore Harbor and Back
River. The box and whisker plots illustrate the median (central horizontal line), the quartlles
(extent of the rectangle), and ranges (extent of vertical lines) of the data. If there are less than
four values, the rectangle's bottom and top show the range. A dash indicates only a single
value is available. The Baltimore Harbor stations in I. are aggregated by their location relative
to the central dredged channel in II. and III. The NOEL and PEL values for sediment
benzo(b)fluofanthene concentrations are not available due to insufficient data (MacDonald,
1993).
V-55
-------
Benzo[g,h,i]perylene
The median sediment concentration of benzo[g,h,i]perylene were 733 ppb and 291 ppb in Baltimore
Harbor and Back River, respectively (Table 5.15). The maximum^concentration of 4004 ppb was
found at the MWT5.2N station in the Baltimore Harbor in 1991 (Table 5.15 and Figure 5.17). There
were insufficient data available for the development of NOEL and PEL guidelines for
benzo[g,h,ijperylene (MacDonald, 1993).
Table 5.15 Summary statistics for benzo[g,h,j]perylene in Baltimore Harbor region sediments. Normalized
concentrations are measured concentrations divided by the fraction total organic carbon in the sediment.
Concentrations are in parts per billion. Statistics on data from the nine stations within the Baltimore Harbor
were calculated with the stations aggregated in terms of the three arrays of stations which lie across the
channel and parallel to the Key Bridge (zero, one, and two transects). These stations were also
aggregated based on whether they are north of the central dredged channel (NORTH), adjacent to the
channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SO
Min Median Max Mean N SO
Min Median Max
Baltimore Harbor
All • 896 13 1075
53 733 4004 22430 13 31430 1590 19700 121330
Center 632
Norm 1456
South 675
6 700
4 1736
3 527
4 376
6 740
3 1809
53
129
69
144
53
733
438
846
927
809
100
1029
1836
4004
1029
957
1836
4004
12580
42280
15680
18260
9030
54800
6 11510
4 53560
3 12020
1590 11860
3090 22350
1840 21820
Back River
MWT4.1 291
4 10330 4010 20270
6 10910 1590 2510
3 57640 19700 23390
4010 16240
18730 18730
21820 21820
1590 1930
3090 14530
1840 1840
19700 19700
.121330 121330
. 23390 23390
2 164 175 291 406 5170 2 3120 2960 5170
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
550
691
927
653
565
69
733
4004
1029
2
1
1
3
2
1
1
1
1
575
.
.
1024
616
t
t
t
t
144
691
927
53
129
69
733
4004
1029
550
691
927
70
560
69
733
4004
1029
957
691
927
1836
1000
69
733
4004
1029
16240
18730
21820
7760
14530
1840
19700
121330
23390
2
1
1
3
2
1
1
1
1
17290
,
.
10390
16180
.
f
t
.
28470
121330
23390
28470
25970
121330
28470
18730
21820
19760
25970
1840
19700
121300
23390
7380
V-56
-------
Figure 5.17 Benzo(g,h,i)perylene concentrations (ppfc>)
in Back River and Baltimore Harbor Sediments
I. BaJtimoro Hartoor Stations
jsooo-
•*ooo
JOOO
2000
1 OOO
BOO
A IM G
K
rvl C
2
II. "Trsn&otrts
.- .4.000
3OOO
2OOO
1 OOO
SOLJTW
HI
BOOO
sooo
2OOO
1 OOO
ZERO
OME
TWO
Figure 5.17 Benzo(g,h,i)perylene concentrations in sediment in Baltimore Harbor and Back
River. Tne box and whisker plots illustrate the median {central horizontal line), the quartiles
(extent of the rectangle), and ranges (extent of vertical lines) of the data. If there are less than
four values, the rectangle's bottom and top show the range. A dash indicates only a single
value is available. The Baltimore Harbor stations in I. are aggregated by their location relative
to the central dredged channel in II. and III. The NOEL and PEL values for sediment
benzo(g,h,i}perylene concentrations are not available due to insufficient data (MacDonald,
1993).
V-57
-------
Benzo[a]pyrene
Benzo[a]pyrene, a Chesapeake Bay Toxic of Concern, is considered a probable human carcinogen by
EPA (Chesapeake Bay Program, 199la). The median sediment concentrations of benzofajpyrene
were 527 ppb and 153 ppb in Baltimore Harbor and Back River, respectively (Table 5.16). The
maximum sediment concentration of 3003 ppb was found in Baltimore Harbor at station MWT5.2N
in 1991 (Table 5.16 and Figure 5.18).
Sediment concentrations of benzol ajpyrene above the NOEL concentration of 230 ppb were found at
eight of the stations in Baltimore Harbor region, but only the maximum measurement exceeded the
PEL concentration of 1700 ppb (Table 5.16 and MacDonald, 1993). Toxic effects to aquatic biota
due to the measured concentrations of benzo[a]pyrene in the sediment are not likely in the Baltimore
Harbor region, with the exception of station MWT5.2N in Baltimore Harbor.
V-58
-------
Table 5.16 Summary statistics for benzo[a]pyrene in Baltimore Harbor region sediments. Normalized
concentrations are measured concentrations divided by fraction total organic carbon in the sediment.
Concentrations are in parts per billion. Statistics on data from the nine stations within the Baltimore Harbor were
calculated with the stations aggregated in terms of the three arrays of stations which lie across the channel and
parallel to the Key Bridge (zero, one, and two transects). These stations were also aggregated based on whether
they are north of the central dredged channel (NORTH), adjacent to the channel (CENTER), or south of the
channel (SOUTH).
Measured
Normalized
Area
Mean
N
SD
Min
Median
Max
Mean
N
SD
Min
Median
Max
Baltimore Harbor
All
Center
North
South
Zero
One
Two
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
Back Rrver
MWT4.1
685
494
1117
488
471
481
1376
394
527
571
608
469
123
353
3003
772
153
13
6
4
3
4
6
3
2
1
1
3
2
1
1
1
1
2
802
550
1279
332
154
587
1425
215
,
832
398
t
t
1
123
125
187
123
242
123
353
242
527
571
125
187
123
353
3003
772
152
527
297
638
571
537
159
772
394
527
571
131
469
123
353
3003
772
153
3003
1569
3003
772
571
1569
3003
547
527
571
1569
750
123
353
3003
772
153
16930
9450
32300
11410
12680
8570
39340
11500
14270
13430
8070
11980
3270
9480
91000
17540
2680
13
6
4
3
4
6
3
2
1
1
3
2
1
1
1
1
2
23030
5940
39620
7340
4130
7500
44920
6740
7640
10610
f
.
•
130
3270
3570
4470
3270
6740
3270
9480
6740
14270
13430
3570
4470
3270
9480
91000
17540
2590
13430
8110
16870
13430
13850
4110
17540
11500
14270
13430
3740
11980
3270
9480
91000
17540
2680
91000
16890
91000
17540
16270
19480
91000
16270
14270
13430
16890
19480
3270
9480
91000
17540
2770
V-59
-------
-------
Chrysene
Chrysene is a Chesapeake Bay Toxic of Concern (Chesapeake Bay Program, 199la). Chrysene was detected
in the sediments at four of the nine Baltimore Harbor stations and at the Back River station (Table 5.17 and
Figure 5.19). The median measured sediment concentrations were 200 ppb and 374 ppb in Baltimore Harbor
and Back River, respectively. The maximum concentration of 374 ppb was found at the Back River station
in 1987.
Median sediment concentrations of chrysene equal to or exceeding the NOEL concentration of 220 ppb were
observed at the Back River station and at two stations in Baltimore Harbor (Table 5.17). All measured
sediment concentrations of chrysene were well below the PEL concentration of 1700 ppb. Toxic effects to
aquatic biota due to the measured sediment concentrations of chrysene are not likely at any of the sampled
locations in the Baltimore Harbor region.
Table 5.17 Summary statistics for chrysene in Baltimore Harbor region sediments. Normalized concentrations are
measured concentrations divided by the fraction total organic carbon in the sediment. Concentrations are in parts
per billion. Statistics on data from the nine stations within the Baltimore Harbor were calculated with the stations
aggregated in terms of the three arrays of stations which lie across the channel and parallel to the Key Bridge (zero.
one, and two transects). These stations were also aggregated based on whether they are north of the central
dredged channel (NORTH), adjacent to the channel (CENTER), or south of the channel (SOUTH). A"." means the
value(s) for that station is/are less than the detection limit.
Measured
Normalized
Area
Mean N SD
Min Median Max
Mean N SD
Min Median Max
Baltimore Harbor
All 223 5
Center 244 3
North 200 1
South 180 1
Zero
One
Two
291 1
206 4
. 0
68 146 200 296 6020 5 1890 4370 4790 8110
85 146 291 296 6850 3 2140 4370 8070 8110
200 200 200 4780 1 . 4780 4780 4780
180 180 180 4790 1 . 4790 4790 4790
291 291 -291 8110 1 . 8110 8110 8110
64 146 190 296 5500 4 1720 4370 4790 8070
... . . 0
MWT5.0C 291
MWT5.0N
MWT5.0S
MWT5.2N
MWT5.2S
Back River
MWT4.1 374
1
0
291 291
MWT5.1C 221 2 106
MWT5.1N 200 1
MWT5.1S 180 1
MWT5.2C . 0
0
0
146
200
180
221
200
180
291
296
200
180
8110
6220
4780
4790
1
0
8110 8110 • 8110
374 374
374
6330
2 2610 4370 6220 8070
1 . 4780 4780 4780
1 . 4790 4790 4790
0
0
0
1 . 6330 6330 6330
V-61
-------
Figure 5.19 Ghrysene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
I. Baltimore I—laroor Stations
too
J3OO
2OO
1 OO
c
K
o
c
2 2
rst C
II. "Transocrts Along
4-00
i aoo
i oo
MORTl-l
III
oo
9OO
aoo
1 OO
. "Transect© .Across Cnannel
ZEPtO
ONE
TWO
Figure 5.19 Chrysene concentrations in sediment in Baltimore Harbo; and Back River. The box
and whisker plots illustrate the median (central horizontal line], the quartiles (extent of the
rectangle), and ranges (extent of vertical lines) of the data. If there are less than four values,
the rectangle's bottom and top show the range. A dash indicates only a single value is
available. The Baltimore Harbor stations in I. are aggregated by their location relative to the
central dredged channel in II. and 111. The NOEL and PEL values for sediment chrysene
concentrations are 220 ppb and 1700 ppb, respectively (MacDonald, 1993). The PEL is
represented in the graphs as a dotted line, if ft is within the range of concentration values.
V-62
-------
Dibenzo[a,h]anthracene
Dibenzo[a,h]anthracene was detected at five of the nine Baltimore Harbor stations as well as the Back River station
(Table 5.18 and Figure 5.20). The median sediment concentrations of dibenzo[a,h]anthracene were 68 ppb and 75
ppb in Baltimore Harbor and Back River, respectively. The maximum sediment concentration of
dibenzo[a,h]anthracene, found at station MWT5.2N in Baltimore Harbor in 1991, was 2227 ppb.
All median sediment concentrations of dibenzo[a,h]anthracene in the region exceeded the NOEL of 31 ppb, except
at the MWT5.0C station, although this single sample, observed in 1987, was only one ppb below the NOEL The
PEL concentration of 320 ppb was exceeded at three Baltimore Harbor stations—MWT5.1 C, MWT5.1 S, and
MWT5.2N. Toxic effects to aquatic biota due to the measured sediment concentrations of dibenzo[a,h]anthracene
are possible at all monitored stations in the Baltimore Harbor, and likely to occur at three of these stations.
Table 5.18 Summary statistics for dibenzo[a,h]anthracene in Baltimore Harbor region sediments. Normalized
concentrations are measured concentrations divided by the fraction total organic carbon in the sediment.
Concentrations are in parts per billion. Statistics on data from the nine stations within the Baltimore Harbor were
calculated with the stations aggregated in terms of the three arrays of stations which lie across the channel and
parallel to the Key Bridge (zero, one, and two transects). These stations were also aggregated based on whether
they are north of the central dredged channel (NORTH), adjacent to the channel (CENTER), or south of the
channel (SOUTH). A"." means the value(s) for that station is/are less than the detection limit.
Measured
Normalized
Area
Mean N SO
Min Median Max
Mean N SD
Min Median Max
Baltimore Harbor
All 501
Center
North
South
Zero
One
Two
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C 362
MWT5.1N 249
MWT5.1S 31
MWT5.2C
801 30
251
908
31
30
250
2227
30
.
3
3
1
1
5
1
1
0
366
1156
289
•
.
30
68
31
30
31
2227
30
2
2
1
0
MWT5.2N 2227 1
MWT5.2S . 0
442
256
49
68
31
68 2227 12930 7 24380 820 1630 67490
49
430
31
30
68
2227
30
362
249
31
674
2227
31
30
674
2227
30
3140 3 3570 840 1340 7260
26760 3 35590 1630 11170 67490
820 1 . 820 820 820
840 1
4440 5
67490 1
840 1
. 0
. 840 840 840
4580 820 1630 11170
.67490 67490 67490
. 840 840 840
674
430
31
4300
6400
820
2
2
1
0
4190
6750
1340
1630
820
4300
6400
820
7260
11170
820
.
. 2227 2227 2227
67490 1
. 0
.67490 67490 67490
Back River
MWT4.1
75 1
75
75
75 1270 1
. 1270 1270 1270
V-63
-------
Figure S.2O Dibenzo(a,h)anthracene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
I. Baltimore h-J arbor Stations
2SOO-
2OOO
n soo
i ooo
&OO
o
(M
O
S
S
II. Tr
2SOO
2OOO
1 SOO
1 OOO
eoo
arisects Along Channel
SOUTl-l
III. Transoots XX.cross
2 OOO
1 SOO
1 OOO
C.OO
o orsic
Figure 5.20 Dibenzo(a,h)anthracene concentrations in sediment in Baltimore Harbor and Back
River. The box and whisker piots illustrate the median (central horizontal line), the quartiles
(extent of the rectangle), and ranges (extent of vertical lines) of the data. If there are (ess than
four values, the rectangle's bottom and top show the range. A dash indicates only a single
value is available. The Baltimore Harbor stations in I. are aggregated by their location relative
to the central dredged channel in II. and III. The NOEL and PEL values for sediment
dibenzo(a,h)anthracene concentrations are 31 ppb and 320 ppb, respectively (MacDonald,
1993). The PEL is represented in the graphs as a dotted line, if it is within the range of
concentration values.
V-64
-------
Fluoranthene
Fluoranthene is a Chesapeake Bay Toxic of Concern (Chesapeake Bay Program, I991a). The median
sediment concentrations of fluoranthene were 814 ppb and 465 ppb in Baltimore Harbor and Back River,
respectively {Table 5.19). The maximum sediment concentration of fluoranthene, found in Baltimore Harbor
at station MWT5.2N in 1991, was 4004 ppb (Table 5.19 and Figure 5.21).
Median sediment fluoranthene concentrations above the NOEL concentration of 380 ppb were found at eight
of nine stations in Baltimore Harbor and at Back River. The PEL concentration of 3200 ppb was exceeded
only at station MWT5.2N in Baltimore Harbor. Toxic effects to aquatic biota due to the measured sediment
concentrations of fluoranthene are likely at station MWT5.2N in Baltimore Harbor, but unlikely at the other
sampled locations in the Baltimore Harbor region.
Table 5.19 Summary statistics for fluoranthene in Baltimore Harbor region sediments. Normalized concentrations
are measured concentrations divided by the fraction total organic carbon in the sediment. Concentrations are in
parts per billion.Statistics on data from the nine stations within the Baltimore Harbor were calculated with the
stations aggregated in terms of the three arrays of stations which lie across the channel and parallel to the Key
Bridge (zero, one, and two transects). These stations were also aggregated based on whether they are north of the
central dredged channel (NORTH), adjacent to the channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SD
Min Median Max
Mean N SO
Min Median Max
Baltimore Harbor
AH 993 13 1090
Center 867 6 861
North 1507 4 1692
South 561 3 355
Zero 741 4 344
One 711 6 902
Two 1895 3 1826
136 814 4004 24460 13 30530 4070 19730121330
136 598 2471 17340
244 891 4004 43620
172 642 868 13140
307 782 1093 20290
136 313 2471 12300
814 868 4004 54320
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
700
921
642
996
552
172
814
4004
868
2
1
1
3
2
1
1
1
1
556
t
1283
436
.
,
307
921
642
136
244
172
814
4004
868
700
921
642
382
552
172
814
4004
868
1093
921
642
2471
860
172
814
4004
868
20540
24970
15110
13690
14090
4570
21890
121330
19730
2
1
1
3
2
1
1
1
1
16960
.
11620
11670
.
.
6 11300 4070 16150 32530
4 52500 5840 23650121330
3 7770 4570 15110 19730
4 10590 8550 20040 32530
6 9780 4070 8120 26600
3 58040 19730 21890121330
8550 20540 32530
24970 24970- 24970
15110 15110 15110
4070 10410 26600
5840 14090 22340
4570 4570 4570
21890 21890 21890
.121330 121330 121330
19730 19730 19730
47 432 465
498
8130 2 420 7840 8130 8430
V-65
-------
Figure 5.21 F"luorgmthene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
i.
sooo
4.000
aooo
20OO
1OOO
Baltimore I—la.rfc>or Stertions
& O O O
A ISI C 5
K
222
IM c: s
II. Transocrts Along Channel
SOOOi
4-000
3000
2000
i ooo
CEfMTS**
SOUTI-I
III.
sooo
•4-OOO
3OOO
2000
1 OOO
OrslE
TWO
Figure 5.21 Fluoranfriene concentrations in sediment in Baltimore Harbor and Back River. The
box and whisker plots illustrate the median (central horizontal line), the quartiles (extent of the
rectangle), and ranges (extent of vertical lines) of the data. If there are less than four values,
the rectangle's bottom and top show the range. A dash indicates only a single value is
available. The Baltimore Harbor stations in I. are aggregated by their location relative to the
central dredged channel in II. and III. The NOEL and PEL values for sediment fluoranthene
concentrations are 380 ppb and 3200 ppb, respectively (MacDonald, 1993). The PEL is
represented in the graphs as a dotted line, if it is within the range of concentration values.
V-66
-------
lndeno[1,2,3-cd]pyrene
The median measured sediment concentrations of indeno[1,2,3-cd]pyrene were 100 ppb and 170 ppb in Baltimore
Harbor and Back River, respectively (Table 5.20). The maximum sediment concentration, found at station
MWT5.1 N in Baltimore Harbor in 1991, was 1100 ppb (Table 5.20 and Figure 5.22). There are no NOEL or PEL
concentrations for indeno[1,2,3-cdJpyrene concentrations in sediment due to insufficient data (MacDonald, 1993).
Table 5.20 Summary statistics for indeno[1,2,3-cd]pyrene in Baltimore Harbor region sediments. Normalized
concentrations are measured concentrations divided by the fraction total organic carbon in the sediment.
Concentrations are in parts per billion. Statistics on data from the nine stations within the Baltimore Harbor were
calculated with the stations aggregated in terms of the three arrays of stations which lie across the channel and
parallel to the Key Bridge (zero, one, and two transects). These stations were also aggregated based on whether
they are north of the central dredged channel (NORTH), adjacent to the channel (CENTER), or south of the
channel (SOUTH). A"." means the value(s) for that station is/are less than the detection limit.
Area
Measured
Mean N SD
Min Median Max
Normalized
Mean N SD
Min Median Max
Baltimore Harbor
All 255
Center
North
South
Zero
One
Two
6 415
802 3 42
609 2 694
66 1
123 1
281 5
. 0
459
40 100 1100
40
118
66
123
40
80
610
66
123
82
120
1100
66
123
1100
6670 6 10760 1200 2530 28570
2290 3 1120 1200 2230 3430
15700 2 18210 2820 15700 28570
1760 1 . 1760 1760 1760
3430 1 . 3430 3430 3430
7320 5 11900 1200 2230 28570
. 0
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
123
61
609
66
1
0
2
2
1
0
123 123
123
3430
1
0
3430 3430 3430
30
694
f
.
40
118
66
61
609
66
82
1100
66
f
1720
15700
1760
2
2
1
0
730 1200 1720 2230
2 18210 2820 15700 28570
. 1760 1760 1760
0
0
Back River
MWT4.1
170
170 170
170 2880 1
. 2880 2880 2880
V-67
-------
Figure 5.22 lndeno(1 ,2,3-od)pyrene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
I. Baltlmoro Hsirfc»or Stations
i 200
ooo
aoo
.300
aoo
A 1st C
111
r*t C S
II. Transects /Mong
i 200
ooo
eoo
III.
1 200
OOO
Across
ZC.RO
OfME
TWO<
Figure 5.22 IndenoH ,2,3-cd)pyrene concentrations in sediment in Baftimore Harbor and Back
River. The box and whisker plots illustrate the median (central horizontal line), the quartiles
(extent of the rectangle), and ranges (extent of vertical lines) of the data. If there are less than
four values, the rectangle's bottom and top show the range. A dash indicates only a single
value is available. The Baltimore Harbor stations in I. are aggregated by their location relative
to the central dredged channel in II. and HI. The NOEL and PEL values for sediment
indeno(l ,2,3-cd)pyrene concentrations are not available due to insufficient data (MacDonald,
1993).
V-68
-------
Naphthalene
Data on sediment concentrations of naphthalene, a Chesapeake Bay Toxic of Concern {Chesapeake Bay Program,
1991 a) are only available for 1986 and 1987. The median sediment concentration among the stations for which
data exists was 188 ppb in Baltimore Harbor and 175 ppb in Back River (Table 5.21). The maximum sediment
concentration of naphthalene was 347 ppb at station MWT5.0C station in Baltimore Harbor in 1987 (Table 5.21 and
Figure 5.23).
Median sediment concentrations of naphthalene in excess of the NOEL concentration of 130 ppb were observed at
the Back River station and at all of the four stations in Baltimore Harbor with measured concentrations. All
measurements were below the PEL concentration of 1100 ppb. Toxicity to aquatic biota due to the measured
sediment concentrations of naphthalene are not likely at any of the monitored stations in the Baltimore Harbor
region.
Table 5.21 Summary statistics for naphthalene in Baltimore Harbor region sediments. Normalized concentrations
are measured concentrations divided by the fraction total organic carbon in the sediment. Concentrations are in
parts per billion. Statistics on data from the nine stations within the Baltimore Harbor were calculated with the
stations aggregated in terms of the three arrays of stations which lie across the channel and parallel to the Key
Bridge (zero, one, and two transects). These stations were also aggregated based on whether they are north of the
central dredged channel (NORTH), adjacent to the channel (CENTER), or south of the channel (SOUTH). A"."
means no data is available for that station.
Measured
Normalized
Mpgn M fin
Min
May
M»an
Min
May
Banimore
All
Center
North
South
Zero
One
Two
naroor
224
266
188
133
347
193
5
3
1
1
1
4
t
88
89
.
-
63
0
133
170
188
133
347
133
188
281
188
133
347
179
f
347
347
188
133
347
281
6150
7570
4500
3540
9670
5270
5
3
1
1
1
4
0
2710
2620
•
2150
3540
4630
4500
3540
9670
3540
4630
8410
4500
3540
9670
4560
9670
9670
4500
3540
9670
8410
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MWT5.1N
MWT5.1S
MWTS2C
MWT5.2N
MWT5.2S
347
226
188
133
1
0
2
1
1
0
0
0
347 347 347
78
170
188
133
225
188
133
281
188
133
9670 1
. 0
6520
4500
3540
2
1
1
. 0
. 0
. 0
9670 9670 - 9670
2670 4630 6520 8410
. 4500 4500 4500
. 3540 3540 3540
Back River
MWT4.1
175 1
175 175
175
2960 1
. 2960 2960 2960
V-69
-------
Figure 5.23 Naphthalene concentrations or Stations
-••oo
300
20O
1 OO
B O O O 1 1 1 22
ArsiCSIMCShMC
^2
K
II.
«*oo
c=
o
— 30O
^ 20O
100
SOOTM
III. Traosecrts -Across
oo-
2OO
1OO
re«o
Two
Figure 5.23 Naphthalene concentrations in sediment in Baltimore Hartxsr and Back River. The
box and whisker plots illustrate the median {central horizontal fine), the quartiles (extent of the
rectangle), and ranges (extent of vertical lines) of the data. If there are less than four values,
the rectangle's bottom and top show the range. A dash indicates only a single value is
available. The Baltimore Harbor stations in I. are aggregated by their location relative to the
central dredged channel In II. and III. The NOEL and PEL values for sediment naphthalene
concentrations are 130 ppb and 1100 ppb, respectively (MacDonald, 1993). The PEL is
represented in the graphs as a dotted line, if it is within the range of concentration values.
V-70
-------
Phenanthrene
The median sediment phenanthrene concentrations were 133 ppb and 315 ppb in Baltimore Harbor and Back
River, respectively (Table 5.22). The region's maximum concentration of 315 ppb was found at the Back
River station in 1987 (Table 5.22 and Figure 5.24).
AH median sediment phenanthrene concentrations were below the NOEL concentration of 140 ppb. Toxic
effects to aquatic biota due to the measured sediment concentrations of phenanthrene are not likely at any of
the monitored stations in the Baltimore Harbor region.
Table 5.22 Summary statistics for phenanthrene in Baltimore Harbor region sediments. Normalized concentrations
are measured concentrations divided by the fraction total organic carbon in the sediment. Concentrations are in
parts per billion. Statistics on data from the nine stations within the Baltimore Harbor were calculated with the
stations aggregated in terms of the three arrays of stations which lie across the channel and parallel to the Key
Bridge (zero, one, and two transects). These stations were also aggregated based on whether they are north of the
central dredged channel (NORTH), adjacent to the channel (CENTER), or south of the channel (SOUTH). A ".*
means the value(s) for that station is/are less than the detection limit.
Measured
Normalized
Area
Mean N SD Min Median Max Mean N SD
Min Median Max
Baltimore Harbor
All 130 5
Center 138 3
North 135 1
South 104 1
Zero
One
Two
199 1
113 4
. 0
44
59
26
81
81
135
104
199
81
133
133
135
104
199
119
199 3520 5 1220 2430 3230 5540
199
135
104
199
135
3860 3 1570 2430 3620
3230 1
2770 1
5540 1
3010 4
. 0
5540
3230 3230 3230
2770 2770 2770
. 5540 5540 5540
520 2430 3000 3620
MWT5.0C 199 1
MWT5.0N . 0
199 199
199
MWT5.0S
MWT5.1C 107
MWT5.1N 135
MWT5.1S 104
MWT5.2C
MWT5.2N
MWT5.2S
2
1
1
0
37
5540 1
. 0
81
135
104
107
135
104
133
135
104
3020 2
3230 1
2770 1
. 0
. 0
. 0
. 5540 5540 5540
650 2430 3020 3620
3230 3230 3230
2770 2770 2770
Back River
MWT4.1 315
315 315
315
5330 1
5330 5330 5330
V-71
-------
Pyrene
The median sediment concentrations of pyrene were 678 ppb and 486 ppb in Baltimore Harbor and Back River,
respectively (Table 5.23). The maximum sediment pyrene concentration, found at MWT5.2N in Baltimore Harbo in
1991, was 7007 ppb (Table 5.23 and Figure 5.25).
Median sediment pyrene concentrations in excess of the NOEL concentration of 290 ppb were observed at sever
monitored stations in the region. One station in Baltimore Harbor (MWT5.2N) had a median concentration well
above the PEL concentration of 1900 ppb. Toxic effects to aquatic biota due to the measured sediment
concentrations of pyrene in the Baltimore Harbor region are likely only at one of the stations in Baltimore Harbor.
Table 5.23 Summary statistics for pyrene in Baltimore Harbor region sediments. Normalized concentrations are
measured concentrations divided by the fraction total organic carbon in the sediment Concentrations are in part'
per billion. Statistics on data from the nine stations within the Baltimore Harbor were calculated with the stations
aggregated in terms of the three arrays of stations which lie across the channel and parallel to the Key Bridge (zi ro,
one, and two transects). These stations were also aggregated based on whether they are north of the central
dredged channel (NORTH), adjacent to the channel (CENTER), or south of the channel (SOUTH).
Measured
Normalized
Area
Mean N SO
Min Median Max
Mean N SD
Min Median Max
Baltimore Harbor
All 1125 13 1808
Center 552
North 2365
South 617
Zero
One
Two
717
540
2836
Back Rh/er
MWT4.1
6 371
4 3130
3 350
MWT5.0C
MWT5.0N
MWT5.0S
MWT5.1C
MVYT5.1N
MWT5.1S
MWT5.2C
MWT5.2N
MWT5.2S
700
790
678
446
831
241
570
7007
933
2
1
1
3
2
1
1
1
1
177 678 7007 30660 1355500 5300 15320212320
177 439
262 1095
241 678
4 324 308 734
6 497 177 266
3 3616 570 933
555
389
805
1093 13120
7007 69090
933 14520
1093 19620
1400 11880
7007 82950
6 10090 5300
4 96280 6270
3 7490 6410
4 10090 8580
6 12080 5300
3112080 15320
9090 32530
28880 212320
15950 21190
18670 32530
6880 36360
21190212320
308
790
678
177
262
241
570
7007
933
700
790
678
270
831
241
570
7007
933
1093
790
678
892
1400
241
570
7007
933
20560
21400
15950
7420
21320
6410
15320
212320
21190
2
1
1
3
2
1
1
1
1
16940
2150
21280
8580
. 21400
. 15950
5300
6270
. 6410
. 15320
212320
. 21190
20560
21400
15950
7360
21320
6410
15320
212320
21190
32530
21400
15950
9600
36360
6410
15320
212320
21190
486
41 457 486
515
8510 2 290 8300 8510 8710
V-73
-------
Figure S.2S Ryrene concentrations (ppb)
in Back River and Baltimore Harbor Sediments
I. Baltimore Harbor Stations
SOOOO-
1 SOOO
1 OOOO
SOOO
BOO
A IM C
11133
rw e S isi c
II. "Trsnsecrts Along Orisinn©!
2OOOO-
— ieooo
^ ioooo
aooo
SOUTH
HI. "Transects X^cross
2OOOO-
i aooo
t oooo
»ooo
TWO
Figure 5.25 Pyrene concentrations in sediment in Baltimore Harbor and Back River. The box
and whisker plots illustrate the median (central horizontal line), the quartiles (extent of the
rectangle), and ranges (extent of vertical lines) of the data. If there are less than four values,
the rectangle's bottom and top show the range. A dash indicates only a single value is
available. The Baltimore Harbor stations in I. are aggregated by their location relative to the
central dredged channel in II. and III. The NOEL and PEL values for sediment pyrene
concentrations are 290 ppb and T900 ppb, respectively (MacDonald, 1993). The PEL is
represented in the graphs as a dotted line, if it is within the range of concentration values.
V-74
-------
Spatial Distribution of Chlorinated Hydrocarbons
A list of pesticides and PCBs analyzed for in the Baltimore Harbor and Back River sediments, the number of
stations at which each compound was detected, and the range in measured concentrations found for each
compound are shown in Table 5.24. Table 5.25 lists the compounds detected and the concentrations at whi :h a-
were found for each station. All data are from 1991.
Pesticides: Alachlor, Chlordane, Heptachlor, Dieldrin, and DOT
The herbicide alachlor was found in the sediment at only one station. A concentration of 1.4 ppb was found < t
MWT5.1C in the Baltimore Harbor fTables 5.24 and 5.25)
Chlordane, a Chesapeake Bay Program Toxic of Concern (Chesapeake Bay Program, 1991 a), was one of th 5 most
commonly detected pesticides in the Baltimore Harbor and Back River (Tables 5.24 and 5.25). The alpha foi n was
found at seven locations and the gamma form at one location. The median concentrations for alpha- and ga, nma-
chlordane at stations where these compounds were detected, was approximately 1.9 ppb for both compound :.
Heptachlor was found at one Baltimore Harbor station at a concentration of 3.3 ppb (Tables 5.24 and 5.25).
Concentrations of total Chlordane (alpha plus gamma forms) measured in the Baltimore Harbor stations were
mostly between the Long and Morgan (1990) ER-L and ER-M concentrations of 0.5 ppb and 6.0 ppb, respecti rely.
The ER-M concentration for total Chlordane was exceeded at two stations in the region—the Baltimore Harboi
station, MWT5.0C, had a total Chlordane concentration of about 6.9 ppb, while the Back River station had
approximately 22.4 ppb. Toxic effects to aquatic biota due to the measured sediment concentrations of chlorc ane
are not likely at the stations monitored in Baltimore Harbor region except for MWT5.0C and the station in the E ack
River.
Dieldrin was found at four of the Baltimore Harbor stations at a range of measured concentrations from 5.7 to 5.1
ppb (Tables 5.24 and 5.25), well below the ER-M concentration of 20 ppb (Long and Morgan, 1990). The ER-. for
dieldrin is 0.02 ppb (Long and Morgan, 1990). Due to the relatively small amount of data available, the degree of
confidence in these ER-L and ER-M concentrations is low (Long and Morgan, 1990). Toxic effects to aquatic I iota
due to the measured sediment concentrations of dieldrin are not likely at the stations monitored in Baltimore H; irbor
or the Back River.
DDT decomposed during the analysis and could not be measured directly in the sediment samples, but the
measured concentrations of DDD and DDE were converted into "DDT equivalents" for comparison with sedirm nt
guidelines relating to Total DDT. Total DDT was measured at three of the Baltimore Harbor stations, with a
maximum concentration of 22.3 ppb total DDT (Tables 5.24 and 5.25). approximately an order of magnitude b< low
the MacDonald (1993) PEL concentration of 270 ppb. The two other stations with detectable levels of DDT hac
concentrations slightly above the MacDonald (1993) NOEL concentration of 5.0 ppb for total DDT. Toxic effect, to
aquatic biota due to the measured sediment concentrations of DDT are not likely at the stations monitored in th> >
Baltimore Harbor region.
V-75
-------
Triazines
Of the three triazine herbicides—atrazine, cyanazine, simazine—measured in sediment samples, only cyanazine
was detected (Tables 5.24 and 5.25). It was found at two stations in the Baltimore Harbor and at the Back River
station (Tables 5.24 and 5.25). The highest measured concentration was 11.4 ppb (Table 5.24 and Table 5.25).
Sediment quality guidelines relating to cyanazine were not found in the literature.
Hexachlorobenzene
Hexachlorobenzene is used in chemical manufacturing and as a fungicide (Windhoiz, era/., 1983).
Hexachlorobenzene was found at seven of the nine stations in Baltimore Harbor, but was not detected at the Back
River station (Tables 523 and 5.24). Measured concentrations varied from 2.4 ppb to 68.9 ppb (Table 5.25).
Sediment quality guidelines relating to hexachlorobenzene were not found in the literature.
Table 524 Frequency of detection and range of observed concentrations for pesticides and PCBs analyzed in
Baltimore Harbor sediments. The total number of stations was 10.
Compound
Frequency
Minimum
Maximum
2,2',3,5'-TetrachIorobiphenyl
2,2',4,5'-Tetrachlorobiphenyl
2,3',5-Trichlorobiphenyl
2,4',5-Trichlorobiphenyl
Alachlor
Alpha chlordane
Atrazine
Carbofuran
Chlorpyrifos
Cyanazine
ODD
DDE
DDT/DDT Equivalent
Dieldrin 4
Fenvalerate
Gamma chlordane
Heptachlor
Heptachlor epoxkle
Hexachlorobenzene
Lindane
Metolachlor
Permethrin
Simazine
0
0
0
0
1
7
0
0
0
3
*
*
3
5.7
0
1
1
0
7
0
0
0
1.4
1.4
0.6
•
*
9.1
6.1
10.2
3.3
2.4
0
1.4
12.2
11.4
*
*
22.3
10.2
3.3
68.9
* DDT decomposed during the sediment analysis and thus its breakdown products DDD and DDE cannot be
reported separately.
V-76
-------
Table 5.25 Pesticides and PCBs found at each sediment monitoring station in Baltimore Harbor and the Back
River.
Location
Compound
Concentration (ppb)
ONE COMPOUND DETECTED = 1 station
MWT5.0S
Hexachlorobenzene
TWO COMPOUNDS DETECTED = 3 stations
MWT5.2C Cyanazine
Hexachlorobenzene
MWT5.2S
MWT5.0N
Alpha chlordane
Heptachlor
Alpha chlordane
Dieldrin
14.0
11.4
10.9
1.4
3.3
1.5
5.9
THREE COMPOUNDS DETECTED
MWT5.1S
MWT5.1N
MWT5.2N
MWT5.0C
Back R.
: 5 stations
Alpha chlordane
Dieldrin
Hexachlorobenzene
Alpha chlordane
DDT Equivalent
Hexachlorobenzene
DDT Equivalent
Dieldrin
Hexachlorobenzene
Alpha chlordane
DDT Equivalent
Hexachlorobenzene
Alpha chlordane
Cyanazine
Gamma chlordane
FIVE COMPOUNDS DETECTED = 1 station
MWT5.1C Alachlor
Alpha chlordane
Cyanazine
Dieldrin
Hexachlorobenzene
1.4
5.7
68.9
1.6
9.1
4.4
9.9
6.1
2.4
6.9
22.3
7.0
12.2
7.6
10.2
1.4
1.9
0.6
5.7
22.8
V-77
-------
Summary of Sediment Organic Compounds in Baltimore Harbor and Back River
Based on the exceedences of the PELs, organic compounds generally pose less of a threat than metals, except
possibly for station MWT5.2N. At that station the PELs for anthracene, benzo{ajanthracene,
benzo[a]pyrene, dibenzo[a,h]anthracene, fluoranthene, and pyrene were exceeded. There is a lower level of
risk at the other stations with the NOEL being exceeded at two to eight of the stations for the other
compounds and the PEL was exceeded at two stations only for one compound. However, the data for
organic compounds in Baltimore harbor are few, with no detectable concentrations at some stations for some
compounds. In many cases, only a single measurement is available per station. Also, most areas of the
Harbor are not monitored.
For the chlorinated compounds, available data indicate that several compounds are present at concentrations
indicating possible impacts. Alpha chlordane and hexachlorobenzene were found most frequently.
V-78
-------
Elizabeth River
Recent data on sediment contaminant concentrations in the Elizabeth River are available from Phase I of
the Elizabeth River Long-Term Monitoring Program (Virginia Water Control Board, 1991 and Greaves,
1990). As part of this program, the Applied Marine Research Laboratory at Old Dominion University
conducted analyses of sediment metal concentrations and the Virginia Institute of Marine Science
conducted analyses of sediment concentrations of organic compounds, including tributyttin. Data were also
gathered on sediment toxicity, the concentrations of organic compounds in blue crab tissue, water column
concentrations of inorganic and organic pollutants, and plankton and benthic communities.
In 1989. sediment samples were collected from four regions within the Elizabeth River and the Lafayette
River, a tributary to the Elizabeth River (Figure 6.1). Three samples, one each from the central channel
and either side of the channel, were collected at each site within the Southern Branch of the Elizabeth
River. At all other sites, one sediment sample was collected.
Summary information on sediment contaminant concentrations obtained in this program is presented and
briefly discussed below. Further information is available from Virginia Water Control Board (1991) and
Greaves (1990).
Trace Metals
Mean and maximum sediment concentrations of copper, lead, mercury, tributyltin and zinc were sometimes
markedly higher in the Eastern Branch, Southern Branch, and Western Branch of the Elizabeth River than
those found in the Lafayette River or the Main Branch of the Elizabeth River. The Western Branch had a
sediment cadmium concentration over twice as great as at any other monitoring station, while the Southern
Branch, Eastern Branch and Main Branch had intermediate sediment cadmium concentrations, and the
Lafayette River had the lowest sediment cadmium concentrations (Table 6.1). The two stations in the
Eastern Branch and the stations with the highest metal concentrations in the Southern Branch (SBE2 and
SBE3) are all adjacent to or near large shipyards (Virginia Water Control Board, 1991).
Mean sediment meta! concentrations above the appropriate NOEL concentrations, but below PEL
concentrations were observed for chromium and zinc in all areas sampled (Table 6.1). Sediment metal
concentrations exceeded the respective NOEL concentrations for cadmium, copper, and mercury in all
areas except the Lafayette River, but no mean concentrations in excess of PEL values were observed.
Sediment concentrations of zinc in excess of the PEL of 300 ppm were found in the Eastern Branch,
Southern Branch, and Western Branches of the Elizabeth River. Mean lead concentrations in the sediment
in the Eastern Branch were above the PEL of 160 ppm. Toxic effects to aquatic biota due the measured
sediment concentrations of zinc and/or lead are likely in the Eastern Branch, Western Branch, and
Southern Branch of the Elizabeth River, but are unlikely at the other sampled locations.
Insufficient data were judged to be available for development of sediment guidelines for tributyltin (Long
and Morgan, 1990; MacDonald, 1993), but sediment concentrations as low as 10 ppm have been
associated with high mortality of grass shrimp, a species generally considered insensitive to most toxic
chemicals (MacDonald, 1993). Tributyltin concentrations in the sediments sampled in the Elizabeth Rrver
ranged from 0.04 ppm to 2.8 ppm. The major use of tributyltin (TBT), a Chesapeake Bay Toxic of Concern
(Chesapeake Bay Program, 1991 a), is as an additive to boat bottom paint to inhibit biofouling. The Federal
Organotin Antifouling Paint Control Act of 1988 prohibits the use of TBT antifouling paints on all non-
aluminum vessels under 82 feet and the sale, distribution, and use of existing stocks of tributyltin products is
prohibited in the U.S. (Chesapeake Bay Program, 1991b).
Vl-1
-------
Anacostia River and the Potomac River Near Washington, D.C.
A comprehensive study of sediment contaminant concentrations in the Anacostia River and the upper
Potomac River near Washington, D.C. was recently conducted by Velinsky et al. (1992) for the Interstate
Commission on the Potomac River Basin. In this study, data were gathered on ambient sediment
contaminant concentrations in the Anacostia River and upper Potomac River, as well as sediment
contaminant concentrations in front of and within major storm and combined sewer outfalls discharging to
these areas. Sediment toxicity tests and benthic community analyses were also conducted at a subset of
stations at which sediment contaminants were analyzed.
Sediment samples not associated with stormwater or combined sewer outfalls were collected in 1991 from
six stations in the Anacostia River and four stations in the upper Potomac River between Rock Creek and
the Anacostia River (Figure 7-1). Summary statistics for sediment concentrations of selected sediment
contaminants from these two areas are presented below and briefly discussed. For further information on
these two areas, as well as data collected on sediments in the Tidal Basin, Washington Ship Channel, and
Kingman Lake, see Velinsky e/a/., 1992.
Trace Metals
Sediment concentrations of trace metals were higher in the Anacostia River than in the upper Potomac
River (Table 7.1). Within the Anacostia River, markedly higher sediment trace metal concentrations were
observed at station AR-4, located just downstream of the Washington Navy Yard (Table 7.1 and Figure
7.1). Within the upper Potomac River, higher trace metal concentrations were consistently found at station
PR-1 (Table 7.1), located below the mouth of Rock Creek, a tributary draining the northwest section of the
District of Columbia (Velinsky et al., 1992).
Sediment concentrations of lead, mercury, and zinc were above their respective NOEL concentrations at all
stations in both the Anacostia River and upper Potomac River (Table 7.1 and MacDonald, 1993). Sediment
trace metal concentrations above the NOEL concentration were observed at at least one station in the
Anacostia River for copper and at at least one station in both the Anacostia River and upper Potomac River
for chromium (Table 7.1, MacDonald, 1993). Sediment concentrations in excess of the appropriate PEL
concentration were observed only in the Anacostia River for lead and zinc (Table 7.1, MacDonald, 1993).
Toxicity to aquatic biota due to the measured sediment concentrations of lead and zinc would ordinarily be
considered likely at a minority of the sampled locations in the Anacostia River; however, measurements of •
acid volatile sulfide in these areas indicate that these metals may not be in a form which is available to the
biota and thus not likely to cause toxic effects (Velinsky et al., 1992).
VII-1
-------
Table 6.1. Summary statistics for sediment trace metal concentrations in various portions of the Elizabeth
Rrver. Concentrations are in ppm dry weight.
Cadmium
min.
mean
max.
Chromium
min.
mean
max.
Copper
min.
mean
max.
Lead
min.
mean
max.
Mercury
min.
mean
max.
Nickel
min.
mean
max.
Tributyltin
min
mean
max
Zinc
min.
mean
max.
Eastern
Branch
0.8
1.2
1.5
38
52
65
150
161
172
169
235
300
0.72
0.99
1.25
17
21
24
0.220
0.660
1.100
467
483
499
Lafayette
Branch
0.6
0.6
0.6
50
50
50
23
23
23
41
41
41
0.08
0.08
0.08
21
21
21
0.150
0.150
0.150
102
102
102
Main
River
1.3
1.6
1.8
32
44
56
22
33
39
34
57
82
0.13
0.16
0.2
13
18
23
0.032
0.056
0.099
116
205
267
Southern
Branch
0.6
1.4
2.8
28
55
76
28
118
229
38
127
186
0.20
-. 0.52
1.02
11
22
29
0.043
0.951
2.800
86
369
624
Western
Branch
6.3
6.3
6.3
54
54
54
70
70
70
129
129
129
0.34
0.34
0.34
18
18
18
0.190
0.190
0.190
666
666
666
VI-2
-------
Polycyclic Aromatic Hydrocarbons and Polychtorinated Biphenyls
Mean and maximum sediment concentrations of polycyclic aromatic compounds (PAHs) and total
polychlorinated biphenyls (total PCBs) were much higher in the Eastern and Southern Branches of the
Elizabeth River than in the other regions sampled. Sediment concentration of PAHs and total PCBs were
higher in the Western Branch and Main Branch than at the Lafayette River station (Table 6.2).
Sediment concentrations of all of the PAH compounds included in Table 6.2 were above their respective
NOEL concentrations in the Southern and Eastern Branches of the Elizabeth River. Mean sediment
concentrations in excess of the appropriate NOEL concentration were also found in the Western Branch
and Main Branch of the Elizabeth River for phenanthrene and total PCBs, and in the Main Branch for
pyrene (Table 6.2). Sediment concentrations of total PCBs and all the PAH compounds listed in Table 6.2
except naphthalene exceeded their respective PEL concentration at one or more stations in both the
Eastern Branch and Southern Branch of the Elizabeth River. Toxic effects to aquatic biota due to the
measured sediment concentrations of total PCBs and several PAHs are likely only in the monitored
locations in the Eastern Branch and Southern Branch of the Elizabeth River.
Vl-3
-------
Table 6.2. Summary statistics for sediment concentrations of selected polycyclic aromatic compounds and
total PCBs in various portions of the Elizabeth River. Concentrations are in ppb dry weight.
Anthracene
min.
mean
max.
Eastern
Branch
310
593
877
Lafayette
River
9
10
11
Main
Branch
20
42
55
Southern
Branch
161
548
2505
Western
Branch
43
43
43
Benzo(a)anthracene
min.
mean
max.
Benzo(a)pyrene
min.
mean
max.
Chrysene
min.
mean
max.
Fiuoranthene
min.
mean
max.
Naphthalene
min.
mean
max.
Phenanthrene
min.
mean
max.
Pyrene
min.
mean
max.
Total PCBs (ppb)
min.
mean
max.
735
1289
1842
906
1415
1924
1154
1785
2417
2401
3876
5350
151
300
449
892
484
077
2577
4860
7143
400
530
660
36
40
45
34
35
36
54
59
63
92
103
115
3
5
7
36
38
41
91
96
102
56
74
91
39
93
150
38
99
151
82
153
224
114
279
390
73
80
88
87
151
196
120
286
457
24
72
120
323
970
2029
637
1362
2519
• 511
1822
3768
823
2974
6029
99
240
491
413
838
892
1459
3426
8138
19
538
2400
143
143
143
161
161
161
196
196
196
375
375
375
33
33
33
170
• 170
170
397
397
397
240
240
240
VI-4
-------
ta*. of the
Measured values
Normalized values
Cadmium
min.
mean
max.
Chromium
min.
mean
max.
Anacostia
River
0.92
1.87
3.18
90.3
116.3
155.5
Potomac
River
0.52
0.66
0.99
63.4
73 g
I v. U
Qfi •)
Copper
min.
mean
max.
Lead
min.
mean
max.
Mercury
min.
mean
max.
Zinc
min.
mean
max.
63.8
91.7
126.9
83.2
177.7
408.9
0.29
0.49
1.04
279
387
512
34.2
41.8
59.7
32.0
58.2
127.7
0.13
0.25
0.56
168
223
365
Anacostia
River
0.93
2.00
3.70
91.1
123.8
180.8
64.4
97.6
147.5
83.9
193.0
475.4
0.29
0.53
1.21
281
412
595
Potomac
River
0.58
0.77
1.27
70.1
85.8
123.1
39.4
46.8
76.4
36.9
69.8
163.4
0.14
0.30
0.72
189
262
467
Vlf-2
-------
Polycyclic Aromatic Hydrocarbons
Sediment concentrations of select polycyclic aromatic compounds were generally higher at the stations in
the Anacost'a River than at the stations in the upper Potomac River. However, station PR-1 in the upper
Potomac River had the highest sediment concentrations among all stations for all of the select PAH
compounds (Table 7.2). As with trace metals, within the Anacostia River, station AR-4 below the
Washington Navy Yard had markedly higher sediment concentrations of selected PAH compounds
compared to the other Anacostia River stations, and station PR-1 in the upper Potomac River downstream
of Rock Creek had markedly higher sediment concentrations of selected PAHs than did other stations in
the upper Potomac River (Table 8.2 and Velinsky etal., 1992).
Sediment PAH concentrations above the appropriate NOEL concentration were observed in both the
Anacostia and upper Potomac rivers for all of the compounds listed in Table 12. Sediment concentrations
above the appropriate PEL concentration were only found at station PR-1 in the upper Potomac River for
phenanthrene and pyrene. Toxic effects to aquatic biota due to the measured sediment concentrations of
PAHs are likely among the sampled areas of the upper Potomac and Anacostia rivers only at station PR-1
below Rock Creek in the upper Potomac River.
Pesticides and other Chlorinated Organic Compounds
Sediment concentrations of total chlordane, total PCBs, and, to a lesser extent, total PCBs were generally
higher in the Anacostia River than in the upper Potomac River (Table 7.3). Sediment concentrations of all
three of these contaminants exceeded their respective NOEL concentrations at all stations within both
rivers. Sediment concentrations in excess of the respective PEL concentrations were found in the
Anacostia River for total chlordane and total PCBs, but not for total DDT. Toxicfty to aquatic biota due to
the sediment concentrations of total chlordane and total PCBs are likely at some of the monitored locations
in the Anacostia River, but are not likely at any of the monitored locations in the upper Potomac River.
Vll-3
-------
Table 7.2. Summary statistics for sediment concentrations of selected polycyclic aromatic hydrocarbons in
the Anacostia and upper Potomac Rivers. Concentrations are in ppb dry weight. Normalized values are
measured concentrations divided by the fraction of total organic carbon in the sediment
Measured values
Normalized values
Anthracene
min.
mean
max.
Benzo(a)anthracene
min.
mean
max.
Benzo(a)pyrene
min.
mean
max.
Chrysene
min.
mean
max.
Fluoranthene
min.
mean
max.
Naphthalene
min.
mean
max.
Phenanthrene
min.
mean
max.
Pyrene
min.
mean
max.
Anacostia
River
35
80
138
169
397
607
212
431
586
253
595
817
482
1265
1867
30
58
130
189
545
1040
478
1166
1811
Potomac
River
28
104
322
106
323
933
124
345
970
135
426
1183
372
975
2781
27
162
554
184
630
1959
312
875
2533
Anacostia
River
971
2201
3677
4742
10764
15490
5949
11799
16860
7074
16279
23652
13509
34790
54301
748
1594
3477
5295
14965
27741
13397
32203
49998
Potomac
River
683
2812
8337
2715
8753
24161
3165
9338
25132
4327
11451
30642
8982
26534
72054
650
4304
14346
4587
16940
50757
7958
23757
65617
VIM
-------
Table 7.3. Summary statistics for sediment concentrations of selected organochlorine compounds in the
Anacostia and upper Potomac Rivers. Concentrations are in ppb dry weight. Normalized values are
measured concentrations divided by the fraction of total organic carbon in the sediment.
MEASURED
NORMALIZED
Anacostia
Potomac
Anacostia
Potomac
Total Chlordane
min.
mean
max.
Total DDT
min.
mean
max.
Total PCBs
min.
mean
max.
28
87
139
29
71
124
218
820
2203
5
16
42
7
33
103
68
123
265
774
2361
3741
803
1877
2879
6118
21304
51242
134
439
1077
177
889
2674
1870
3402
6855
VII-5
-------
Interpretation of Trace Metal Concentrations in Chesapeake Bay
Sediments
Introduction
Trace metals are a natural component of sediment. However, natural concentrations among different
sediments vary by as much as a factor of 100 (Windom era/., 1989) making it difficult to determine how
much of a measured concentration is natural and how much is due to anthropogenic input. There are two
major sources of natural variation. The first is the origin of the sediment. For example, if a sediment is
eroded from a source rich in zinc, then it will also have relatively high levels of that metal. The second
source of variation is the concentration of trace metals in fine-grained material. Thus, sediments with a
greater proportion of fine-grained materials , generally have higher concentrations of trace metals than
areas where coarse-grained materials, such as sands, predominate. This is believed to occur because fine
particles have a greater surface area per unit mass than large particles and consequently adsorb more
metals than the same mass of larger particles. Larger particles adsorb only small quantities of metals and
thus act to dilute the metal concentration of sediments (Horowitz, 1985).
One approach to separating natural from anthropogenic variation in sediment trace element concentrations
is to "normalize" trace metal concentrations to another element, such as aluminum or iron. The
normalizing element is selected so that trace metal;normalizing element ratios are relatively constant in
uncontaminated areas. This may occur because the normalizing element is present in very high
concentrations relative to trace metals and/or because the sediment concentration of the normalizing
element is not affected by human activities. Among the elements that have been used to normalize
sediment trace metal concentrations are lithium (Loring, 1990 and 1991), rubidium (Grant and Middle ton.
1990). iron (Trefey, era/., 1976; Sinex and Helz, 1981; Helz etal., 1983; Rule, 1988; Sinex and Wright.
1988), and aluminum (Windom et a/., 1989; Environmental Protection Agency, 1991). Sediment samples
with an ususually high trace metalrnormalizing element ratio are said to be "enriched" with this trace metal,
presumably due to anthropogenic inputs.
Often, the determination of what constitutes enrichment is based on the average trace metal-normalizing
element ratio in the earth's crust (Rule, 1988; Sinex and Wright, 1988). However, assuming an average
crustal composition may not be appropriate for a relatively limited geographic area such as the
Chesapeake Bay, since local geology may result in different trace metal:normaiizing element ratios than
those obtained from average crustal composition. An alternative is to develop a more site-specific ratio by
using trace metal:normalizing element ratios from sediments from areas within the region that are relatively
unaffected by anthropogenic inputs of trace metals (Windom et a/.. 1989). This method has the
disadvantage of requiring the identification of areas believed to be relatively uncontaminated with trace
metals, which may introduce an element of subjectivity into the analysis.
The use of trace metal:normalizing element ratios for interpreting the trace metal concentrations discussed
. in this report is hampered by several factors. The first is that an analytical method which completely
dissolves the sediment sample, i.e. a "total concentration" of metals should be used in this type of analysis
(Windom et a/., 1989). However, the majority of the data discussed in this report were obtained using a less
rigorous technique for extracting the metals from the sediment, i.e., "total recoverable" concentrations,
which does not completely dissolve the sediment matrix. There are advantages and disadvantages to both
methods of determining sediment metal concentrations; however, data obtained from the two methods may
not be directly comparable.
The second factor complicating the analysis is that areas in the study region that would a priori be assumed
to have very low levels of trace metal contamination because they are in more pristine areas and not
influenced by currents from populated areas, e.g., the Southeastern Rivers and Bays region in Maryland,
also differ from other areas of Chesapeake Bay in other ways. Sediments on the lower eastern shore of
VIII-1
-------
Chesapeake Bay are generally coarser than those located elsewhere in the Bay, and thus would be
expected to have lower trace metal concentrations than other areas in the Bay for that reason alone.
However, dividing sediment trace metaf concentrations by the concentration of a normalizing element
generally accounts for much of the variability in trace metal concentrations which can be accounted for by
variations in grain size (Luoma, 1990).
In addition, the presumably less contaminated sediments on the lower eastern shore may have a different
geological origin than sediments on the western shore. The sediments along the eastern flank of the Bay
are thought to have been transported from the south, while sediments from the western flank of the Bay are
believed to be derived from the Susquehanna River (Helz and Valette-Siiver, 1992). Finally, the trace
mefal.-normalizing element ratios obtained from reference areas may be based on data with a smaller
range in normalizing element concentrations than that found in the data as a whole, thus requiring the
assumption that the trace metal:normalizing element ratios are the same at higher concentrations of the
normalizing element (Schropp and Windom, 1988).
Methods
The majority of areas in the Chesapeake Bay have data available on sediment trace metal concentrations
measured by the "total recoverable" method. These include the matnstem Bay, its tidal tributaries in
Maryland, and the Elizabeth River. A "total recoverable" method of metals analysis was also applied to
sediment samples from the James River analyzed by the Virginia Department of Environmental Quality.
However, data on the major metals typically used as normalizing elements were not available for these
samples, and thus these data were not included in the analyses. Because of the use of the "total" method
of sediment trace metaf concentrations in data from the Anacostia River and Potomac Rivers near D.C.
(Velinsky era/., 1992) and the EMAP program in the Virginia tributaries, these data were also excluded from
the analysis. Thus, all data used in the analysis were obtained with the same analytical method.
The assumption inherent in using trace metalrnormalizing element ratios to identify areas impacted by
anthropogenic inputs of trace metals is that in uncontaminated areas, the trace metai:normafizing element
ratio will be relatively constant, and thus the majority of the variation in trace metals concentrations will be
accounted for by variations in sediment concentrations of the normalizing element. To select the
normalizing element, a correlation analysis was performed to determine the strength of the relationship
between the concentrations of the various trace metals and the two major metals, iron and aluminum,
which could potentially be used as normalizing elements. Data on the percentages of total organic carbon
and silt and clay in the sediment were also included in this correlation analysis, since variation in these
sediment characteristics have been found to be significantly correlated with the concentration of some trace
metals (Windom era/., 1989; Horowitz etal., 1989; Luoma, 1990). Data from stations known to be
influenced by point sources of trace metals were excluded from this correlation analysis.
The results of the correlation analysis showed that of the two major metals most commonly used for
normalization of sediment trace metal concentrations, the concentrations of five of the eight trace metals
were more strongly correlated with iron concentrations than with aluminum concentrations (Table 8.1). For
all trace metals, correlation coefficients with iron concentrations were highly significant, and ranged from
0.214 in the case of lead to 0.774 for chromium.
Mercury and arsenic both had slightly higher correlation coefficients with aluminum than with iron. For
mercury, the correlation coefficients with iron and aluminum were very close, with correlation coefficients of
0.484"and 0.508 for iron and aluminum, respectively. For arsenic, the correlation coefficient with aluminum
(0.650) was somewhat higher than that for iron (0.515) (Table 8.1). For consistency, and for the reasons
discussed below, iron was used as the normalizing element for all trace metals.
iron is a reasonable candidate to use in normalizing trace metal concentrations in Chesapeake Bay
sediments, since anthropogenic inputs of iron are small relative to natural sources (Tippie, 1984). Helz et
VIII-2
-------
a/. (1983) found that despite large inputs of iron (o Baltimore Harbor in the past, the ratio of aluminum to
iron in Harbor sediments was not anomalous, suggesting that the relatively high iron concentrations found
in Baltimore Harbor are probably a consequence of the predominance of fine-grained sediments in the
area, rather than past anthropogenic inputs. Several studies of trace metal enrichment of Chesapeake Bay
sediment which used sediment metal concentration data obtained from a "total recoverable" type of
analysis have used iron as the normalizing element (e.g., Sinex and Wright, 1988; Rule, 1988).
The higher correlations of sediment trace metals with iron as compared to aluminum may be partially due
to the type of extraction used in measuring the metal concentrations. The "total recoverable" method used
in this study would have measured primarily metals associated with the surface of sediments, and iron
oxides are one of the principal binding sites for metals on the surfaces of oxic sediments (Luoma, 1990). A
relatively large proportion of trace metals associated with aluminum, in contrast, are located in the matrix of
the sediment, and thus are not released unless a complete dissolution of the sediment is used to extract the
metals. Use of aluminum as a normalizing element for trace metal concentrations is not recommended
unless a "total metal" extraction technique is used (Schropp and Windom, 1988). Quality assurance and
quality control data (Appendix C) indicate that the difference in metal concentrations obtained from the total
metal technique versus that obtained from the total recoverable metal technique was much greater for
aluminum than it was for iron and the trace metals measured.
To identify trace metal.iron ratios which are high enough to indicate enrichment (i.e., possible anthropogenic
trace metal contamination), the average trace metal:iron ratio for each metal at each station was compared
to a threshold value. For each trace metal, the threshold was the approximate upper 95% confidence limit
of the Baywide mean trace metal:iron ratio for that trace metal (the mean ratio plus two standard errors of
the mean ratio). The Back River, Elizabeth, Magothy, Severn, and Sassafras Rivers, Baltimore Harbor, and
mainstem segments 1 and 2 were excluded from the calculations of threshold values because these
stations were thought to be more heavily affected by anthropogenic trace metal contamination. Regions
with trace metal.lron ratios above the threshold are listed in Table 8.2. These procedures for identifying
stations enriched with trace metals were used by Morse et al. (1993) in the Galveston Bay area.
In addition, enrichment factors relative to the earth's crust were calculated for each trace metal at each
station by dividing the observed average trace metab'ron ratio by the trace metal;iron ratio in the average
composition of the earth's crust. Sinex and Wright (1988) suggested that enrichment factors greater than
two are probably indicative of elevated levels of trace metals, although they presented no support for this
statement Table 8,3 lists average enrichment factors in each region relative to crustal composition.
Results and Discussion
Table 8.2 presents, for each trace metal, a list of the regions which were identified as enriched with that
metal by the threshold criteria discussed above. Back River was is enriched with all trace metals except
arsenic; Baltimore Harbor sediments are enriched with all of the listed metals except cadmium and nickel.
There are no arsenic data for the Elizabeth River, but that area is enriched with all of the other metals
except nickel. Other regions are enriched with varying combinations of metals. Copper is found to be
enriched in 14 of the 23 listed areas; zinc in 13; and lead, mercury, and nickel in nine each.
Comparison of the trace metal.'iron ratios with that expected based on average crustal composition (Taylor,
1964) rather than Chesapeake Bay ratios present a different-picture using double the crustal ratio as the
threshold for enrichment (Sinex and Wright, 1988) (Table 8.3). All stations were enriched for arsenic and
most for cadmium, as opposed to 5 of 23 regions for both metals using the Chesapeake Bay ratios and
indicated thresholds. Crustal ratios indicate a low frequency of enrichment for chromium, copper, lead, and
mercury whereas Chesapeake Bay ratios indicate more frequent enrichment (between 9 and 14 of the 23
listed regions) for those metals. Crustal ratios indicated enrichment at 20 of 23 regions for nickel while
Chesapeake Bay ratios indicated enrichment at 9 of 23. Zinc was enriched at 20 of 23 regions by crustal
ratios and at 13 of 23 regions by Chesapeake Bay ratios.
VIJI-3
-------
This could indicate that arsenic, cadmium, nickel, and zinc may be somewhat elevated naturally in
Chesapeake Bay area sediments, as well as enriched due to anthropogenic inputs in localized areas within
the region. It might also be indicative of widespread contamination, suggesting that diffuse atmospheric
sources are, or have been, a significant proportion of the total loadings for these metals. High
arsenic:aluminum ratios relative to those based on average crustal composition have also been found in
Florida estuarine sediments (Windom etal., 1989).
Comparisons with Other Studies of Trace Metal Enrichment in Chesapeake Bay Sediments
Sinex and Wright (1988) calculated enrichment factors relative to average crustal composition for
Chesapeake Bay sediments. These authors used iron as the normalizing element and the same source of
data for average crustal composition as was used in the analysis presented above. The sources of data for
Baltimore Harbor sediment metal concentrations they cite are from 1981 and 1982, and thus most likely
reflect measurements made in the late 1970s. The results of their analysis are similar to the results
discussed above with respect to widespread enrichment of zinc in the Baltimore Harbor and upper and
middle regions of the mainstem and marked chromium enrichment in Baltimore Harbor.
Sinex and Wright (1988) also found widespread enrichment of zinc relative to average crustal composition
in mainstem Chesapeake Bay sediments, and suggested this was consistent with a large atmospheric
source of zinc to the Bay. In the past, high concentrations of zinc were reported in rainwater from storms in
the region (Environmental Protection Agency, 1982). Zinc has been found to be enriched relative to
average crustal composition in the upper portion of cores from the mainstem, but not in the bottom portion,
suggesting an increase in zinc loadings to the Bay in the past 100 years (Sinex and Wright, 1988). Thus,
the available evidence suggests that a considerable portion of the zinc concentration in Chesapeake Bay
sediments is probably due to anthropogenic inputs, at least in the urbanized areas showing the highest
levels of enrichment with zinc.
However, the enrichment of lead in mainstem sediments found by Sinex and Wright is not evident in the
current analysis. Sinex and Wright (1988) noted that atmospheric sources (presumably from the use of
leaded gasoline) were an important source of lead to the mainstem. The decline in the use of leaded
gasoline which occurred from 1979 to 1989 has been estimated to have reduced the concentration of lead
in urban runoff by 95% (Olsenholler, 1985), and a similar decrease has probably occurred in direct
atmospheric loadings of lead. Thus, the decline in enrichment in lead in mainstem sediments may reflect
the switch to unleaded gasoline. Sinex and Wright (1988) also found enrichment of copper in the
sediments in the upper portion of the mainstem and enrichment with zinc in lower mainstem sediments.
Neither of these areas were identified as enriched with these elements in the analysis based on more
recent data.
Velinsky, et a/.(1992) found marked enrichment of cadmium and, to a lesser degree, lead, in the sediments
from the lower Anacostia and upper Potomac rivers in the vicinity of Washington, D.C. The lower Anacostia
River was more enriched with these two metals than the upper Potomac River. Copper and zinc showed
more modest enrichment than cadmium and lead, and the levels of enrichment of these trace metals were
similar for the two rivers. Enrichment factors for mercury varied considerably among the stations in the
lower Anacostia and upper Potomac rivers. Mercury was not enriched at most of the stations sampled, but
some stations in the lower Anacostia River (station AR-4 below the Washington Navy Yard) and upper
Potomac River (station PR-1 below the confluence with Rock Creek) were enriched with mercury.
Chromium was generally not enriched at the stations sampled in these two rivers.
VIIW
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Discussion and Conclusions
Baywide Spatial Patterns in Sediment Concentrations of Trace Metals
The distribution of the various trace metals generally show similar spatial patterns within the Chesapeake
Bay and its tidal tributaries. The areas discussed in this report can be placed into one of four broad groups
with regard to median sediment trace metal concentrations. These groups are listed and discussed below
in order of decreasing sediment trace metal concentrations.
1. Baltimore Harbor and Back River, the Anacostia River, and the Eastern and Western Branches of
the Elizabeth River
Baywide, the highest median sediment concentrations of all the monitored trace metals were found in one
of these areas (Table 9.1). For cadmium, chromium, lead and zinc, the sediment concentrations in these
areas were markedly higher than those found elsewhere in the Chesapeake Bay mainstem or tidal
tributaries. All of these areas had median sediment concentrations of zinc which exceeded the Probable
Effects Level (PEL) values. Concentrations of cadmium, chromium, and lead in Back River, chromium in
Baltimore Harbor, and lead in the East Branch of the Elizabeth River xceeded the respective PELs.
Back River had the highest median sediment concentrations of cadmium, copper, nickel, and zinc.
Baltimore Harbor had the highest median concentrations of chromium and arsenic, however, arsenic
concentrations were not available for the Anacostia River or Elizabeth River. The highest sediment
concentrations of mercury and lead were in the Eastern Branch of the Elizabeth River, while the highest
sediment cadmium concentration was in the Western Branch of the Elizabeth River.
2. Tidal tributaries in the Northwestern, Western, and Northeastern Rivers regions in Maryland, the
upper Potomac River near Washington, O.C., and the Southern Branch of the Elizabeth River.
Sediment contaminant monitoring stations in these areas generally had median trace metal concentrations
less than those found in the areas listed above, but higher than those observed at stations in other tidal
tributaries and the mainstem Bay.
Within these areas, zinc was the only trace metal for which average sediment concentrations exceeded
PEL values.
3. Tidal tributaries on the lower western shore (Patuxent and Potomac) and upper eastern shore of
Maryland (Chester and Choptank), the Main Branch of the Elizabeth River, and the stations in the
upper, western and central portions of the mainstem midbay.
Monitoring areas in the Patuxent, Potomac, Chester, and Choptank Rivers in Maryland, the main branch of
the Elizabeth River, and the western flank and central portion of the midbay had sediment trace metal
•concentrations in the third highest category Baywide. Median sediment trace metal concentrations at these
stations were generally below those found in the more highly industrialized and/or urbanized areas in the
categories above, but were somewhat higher than those found in less urbanized tributaries on the lower
western and eastern shores and elsewhere in the mainstem. None of these areas had average sediment
trace metal concentrations in excess of PEL values.
The lower estuarine portion of the James River has higher concentrations than the upper portion, and the
lower areas and the Lafayetter River could be placed within this group.
4. Tributaries on the lower eastern shore of Maryland, the Rappahannock and York rivers, the upper
portions of the James River, and the stations on the eastern flank of the midbay and the extreme
upper and lower portions of the mainstem Bay.
IX-1
-------
These stations generally had the lowest sediment trace metal concentrations found in the mainstem or tidal
tributaries of the Chesapeake Bay (Table 9.1).
There were a few exceptions to the spatial distribution of trace metals in Chesapeake Bay sediments
described above. The tidal fresh station of the Patuxent River and some stations from the Southeastern
Rivers and Bays Region on Maryland's eastern shore had sediment cadmium concentrations which were
considerably above those from stations located near more populated areas, such as those in the Potomac
River and Northeast Rivers regions. Although the spatial distribution of sediment arsenic concentrations
was similar to that of the other trace metals, the arsenic concentrations found in Baltimore Harbor, the
Anacostia and Back Rivers were not as high relative to those found elsewhere in the Chesapeake Bay as
was the case for most other trace metals.
In general, the above patterns still held when trace metal concentrations were normalized to take into
account differences in the proportions of silt and clay, or iron, in the sediment. The one major exception to
this pattern was the station at the mouth of the Susquehanna River, which had relatively high trace metal
concentrations for an area with a low percentage of fine-grained sediments and relatively low iron
concentrations. In general, however, the spatial patterns in sediment trace metal concentrations probably
reflect, in at least a broad way, the spatial distribution of trace metal loadings to the Bay, and do not result
primarily from differences in sediment grain-size distribution.
Baywide Spatial Patterns in Sediment Concentrations of Polycyclic Aromatic Hydrocarbons
The Baywide pattern in the sediment concentrations of polycyclic aromatic hydrocarbons (PAHs) differed
from that exhibited by the trace metals. Three broad categories of sediment concentrations of these
compounds are discussed below in order of decreasing concentrations.
1. The Southern and Eastern Branches of the Elizabeth River.
These two tidal tributaries had median sediment concentrations of most PAHs which far exceeded those
found elsewhere in the Chesapeake Bay and its tidal tributaries (Table 9.2). The sediment concentrations
of phenanthrene, fluoranthene, pyrene. and chrysene exceeded the PEL concentrations in the east branch;
only pyrene exceeded the PEL in the south branch.
2. Baltimore Harbor, Back River, Anacostia River, Northwestern, Western, Northeastern, Upper
PotomacRiver Regions, West and Main Branches of the Elizabeth River, and Chesapeake Bay
segments 2 and 3.
These areas had median sediment concentrations of most PAHs less than those in the Southern and
Eastern Branches of the Elizabeth River, but greater than the rest of the Chesapeake Bay tidal tributaries
and mainstem Bay. Within the Baltimore Harbor, sediment concentrations of most PAHs were markedly
higher at station MWT5.2N near Sparrows Point than at the other monitoring stations (Chapter 5). Within
the Anacostia River, sediment concentrations of most PAHs were markedly higher at station AR-4 below
the Washington Navy Yard compared to other stations in the river (Chapter 7). Sediment PAH
concentrations in these areas did not exceed PEL concentrations.
3.
All other monitored areas.
Stations in these areas generally had sediment concentrations of PAHs which were generally lower than
those observed elsewhere in the Chesapeake Bay mainstem and tidal tributaries.
IX-2
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Potential Risk to Aquatic Biota Due to Sediment Contaminant Concentrations
To summarize the large amount of data on sediment contaminant concentrations in Chesapeake Bay and
its tidal tributaries, a procedure was developed to rank stations or regions according to the likelihood that
the concentrations of sediment contaminants at these locations would be associated with adverse effects to
aquatic biota.
In the ranking procedure, all locations were initially assigned a score of one. For each location the average
sediment concentration of each contaminant included in the ranking procedure (selected trace metals,
polycyclic aromatic hydrocarbons, PCBs, and pesticides) was then compared to the appropriate Probable
Effects Level (MacOonald, 1993). Two points were added to a location's score for each contaminant for
which the average sediment concentration was above its PEL. One point was added to a station's score for
each contaminant for which the average sediment score approached the PEL, i.e, was between 80 and 100
percent of the PEL. No points were added to a location's score for those contaminants for which the
average sediment concentration did not exceed or approach the PEL, i.e, were less than 80 percent of the
PEL. A location's scores for all contaminants (Table 9.3) were then added together to produce a single
numerical score for that location. The higher a location's score, the higher its sediment contaminant
concentrations relative to the concentrations which may be associated with adverse effects to aquatic
organisms, and thus the higher the probability of sediment contamination at that location resulting in
adverse effects to its aquatic biota.
The contaminants included in the ranking process are listed in Table 9.3. The criteria for inclusion of a
sediment contaminant in the ranking process were the availability of sediment concentration data for all or
most of the Chesapeake Bay and its tidal tributaries and the availability of relevant sediment quality
guidelines. Data on sediment concentrations of nickel were not included in the analysis because current
sediment quality guidelines are not predictive of an increasing incidence of toxic effects (Long etal., 1995).
A special effort was made to include those contaminants on the Chesapeake Bay Toxics of Concern List
(Chesapeake Bay Program. 1991 a).
For the Maryland tidal tributary stations, data on sediment concentrations of both trace metal and organic
chemical contaminants were available, and thus the ranking process was applied to these individual
stations. Within the Virginia tidal tributaries and the mainstem of Chesapeake Bay, data on both trace
metals and organic chemical contaminants were not available from all stations or were collected from
different locations within these areas. Thus, within these areas, sediment contaminant data were
aggregated by Chesapeake Bay Program segment, with the tributaries divided into tidal fresh, estuarine
transition, and lower estuarine segments. In areas which have been sampled more intensively, such as the
Anacostia River, the upper Potomac River in the vicinity of Washington, D.C., the Baltimore Harbor, and the
various branches of the Elizabeth River, data from several stations were aggregated and a single score for
each of these areas was obtained by applying the ranking procedure to these average sediment
contaminant concentrations.
The data used in the ranking process were primarily from the Virginia and Maryland sediment contaminant
monitoring programs, since these two programs utilized similar analytical methods and provided good
spatial coverage of the area of interest. Data from Velinsky et al. (1992) were utilized for the Anacostia and
the upper Potomac rivers near Washington, D.C. No data were available on sediment concentrations of
arsenic in these two areas, so the average sediment arsenic concentration at the tidal fresh station in the
Potomac River was used as proxy data for these two locations. There were no data on sediment
concentrations of trace metals in the York and Rappahannock rivers from Virginia's sediment monitoring
program, so in these two areas data from the Environmental Protection Agency's Environmental Monitoring
and Assessment Program (EMAP) were utilized in the ranking process. The EMAP data available for this
report did not include arsenic and mercury concentrations, so average concentrations from the Virginia
portion of the mainstem were utilized as proxy data for these areas.
IX-5
-------
Table 9.3. Contaminants included in the procedure used to rank locations within Chesapeake Bay and its
tidal tributaries according to the potential risk of toxic effects to aquatic biota posed by sediment
concentrations of contaminants. Contaminants marked with two asterisks are on the Chesapeake Bay
Toxics of Concern List (Chesapeake Bay Program, 1991 a); contaminants marked with a single asterisk are
on the secondary list of compounds being evaluated for inclusion on the list of Chesapeake Bay Toxics of
Concern (Chesapeake Bay Program, 1991b).
TRACE METALS
Arsenic'
Copper"
Cadmium"
Chromium"
Lead"
Mercury"
Zinc'
POLYCYCLIC AROMATIC HYDROCARBONS
Anthracene
Benzofajanthracene"
Benzofajpyrene"
Chrysene"
FJuoranthene"
Naphthalene"
Phenanthrene
Pyrene
-"•
CHLORINATED ORGANIC COMP DUNDSi
__ |
Total PCBs 1
(or sum of measured congeners) 1
Total DDT |
JotaJ chlordane
Data on trace metal concentrations from the EMAP study were also used in the ranking process for the
James River, since these.data were more recent than that from the Virginia Department of Environmental
Quality (VADEQ) monitoring program, in addition, the EMAP stations were located randomly, whereas
those sampled by VADEQ were intentionally located near wasfewater outfalls. For these reasons, the data
from the EMAP stations were thought to be more representative of sediment trace metal concentrations in
most of the James River. Data on sediment arsenic concentrations were unavailable for the Elizabeth
River, so the average arsenic concentration in the lower estuarine portion of the James River was used as
proxy data.
The data on sediment trace metal concentrations used in the ranking process were obtained with a "total
recoverable" extraction procedure in the Maryland tributaries and the mainstem Bay, while a more rigorous
"total" extraction procedure was used to obtain the data from the James, York, Rappahannock and
AnacosBa Rivers, as well as the upper Potomac River in the vicinity of Washington, D.C. The "total
recoverable" method of sediment trace metal analysis may underestimate sediment trace metal
concentrations compared to what would be obtained using the more rigorous "total" method of trace metal
analysts.
The current level of scientific understanding of the effects of sediment contaminants does not allow for
consistently accurate predictions of the probability of adverse effects on aquatic biota based solely on
information on the sediment concentrations of contaminants. Thus, this ranking procedure, like any other
based on current knowledge, cannot be expected to provide an accurate estimate of the relative risk to
aquatic biota due to sediment contamination in all instances. Some of the shortcomings of the ranking
procedure are discussed below.
The ranking procedure does not take into account differences among locations in sediment characteristics
such as the concentration of acid volatile sulfide (AVS) or total organic carbon (IOC) which may strongly
influence sediment contaminant bioavailability and toxicity. Bulk sediment contaminant concentrations were
used in the ranking process because the PEL concentrations to which the sediment concentrations were
fX-6
-------
compared are based on bulk sediment contaminant concentrations. In addition, data on AVS
concentrations were not available from the Mary/and Department of Environment's monitoring program in
the Maryland tidal tributaries or the Virginia Department of Environmental Quality - EPA Chesapeake Bay
Program sediment contaminant monitoring program in the Virginia tidal tributaries.
Comparison of sediment contaminant concentrations in Chesapeake Bay to PEL concentrations should, on
average, make reasonable predictions of the probability of adverse biological effects, assuming the
sediments are generally similar to the sediments used to derive the PEL values. With respect to sediment
from any one location, however, sediment characteristics may result in the PEL providing an inaccurate
prediction of the likelihood of impacts to aquatic biota.
Differences in the concentrations of other sediment contaminants may also affect the applicability of the
PEL guideline to sediments at a given location. The ranking procedure implicitly assumes that sediment
contaminants present in concentrations at or above the PEL concentrations have additive effects, an
assumption with some support in the literature (Okamura and Aoyama, 1994), However, in some
instances, groups of similar sediment contaminants have been found to interact in a synergistic manner
(Enserink etal., 1991 and Okamura and Aoyama, 1994). Thus, it is possible that a suite of sediment
contaminants, none of which are present at concentrations near or above its PEL concentration, may in
concert adversely effect the biota. However, the relationship of interactions among multiple sediment
contaminants to the overall degree of sediment toxicity has not progressed sufficiently for such interactions
to be modeled and included in the ranking process.
Because of the limitations of the ranking process discussed above, the ranking must be viewed as only a
rough estimate of the relative probability of sediment toxicity to aquatic biota at various locations in
Chesapeake Bay. As additional information on sediment characteristics such as the concentrations of acid-
volatile sulfide and total organic carbon, and the results of sediment bioassays, studies of benthic and fish
tissue contaminant concentrations, and benthic community condition at each location become available,
our estimates of the relative risk to aquatic biota from sediment contamination for various locations may be
altered.
The distribution of location scores is positively skewed, with a few stations showing much higher scores than
those of the majority of locations (Figure 9.1). This indicates that at most locations in the Chesapeake Bay
and its tidal tributaries the biota are not likely to be impacted by sediment contaminant concentrations.
However, there are some locations where, due to natural concentertating factors (the two msinstem Bay
segments), or to historical industrial activity (Patapsco and Elizabeth Rivers), or urbanization (Anacostia
River) where adverse impacts are more likely.
The eastern branch of the Elizabeth River had the highest score of all ranked locations, followed by Back
River and the Southern Branch of the Elizabeth River. The Patapsco River (Baltimore Harbor), according
to these scores, is impacted less than the three threatened sites. Anacostia River, and the western branch
of the Elizabeth River are just a little better than the Patapsco. The high scores of the eastern and southern
. branches of the Elizabeth River were due to the much higher sediment concentrations of polycyclic
aromatic hydrocarbons (PAHs) in these areas compared to Baltimore Harbor, Back River, Anacostia River,
and the western branch of the Elizabeth River. Back River, for instance, had several trace metals in excess
of their PEL, but no PAHs exceeded the relevant PEL. In contrast, the Elizabeth, Anacostia, and Baltimore ,
Harbor had somewhat lower sediment trace metal concentrations than Back River, but higher sediment
PAH concentrations.
The Magothy, and Severn rivers received the next highest scores, followed by Bay segments 2 and 3, the
South Northeast, Sassafras, and Middle rivers. With the exception of the Sassafras River, sediment trace
metal concentrations contributed more heavily to these areas' overall scores than did sediment
concentrations of PAHs. Segment two in the upper Bay and segment three in the upper midbay had the
highest overall rankings among locations in the mainstem of Chesapeake Bay. This was due to having
concentrations of zinc at 80% of the PEL. Zinc tends to be high in many areas of the Bay. In addition,
segments two and three are areas where organic carbon and fine sediment tend to accumulate, further
IX-7
-------
In general, sediment contaminant concentrations above the PEL occurred more frequently for trace rnetals
than for PAHs and in all but some of the most contaminated areas, trace metals appear to pose greater
environmental risks to aquatic biota than do polycyclic aromatic hydrocarbons and other organic
contaminants. There is less data available on sediment concentrations of chlorinated organic compounds
such as pesticides and PCBs in Chesapeake Bay than there is regarding trace metafs and PAHs. In
addition, there are no sediment guidelines for many chlorinated organic compounds. However, where
available, sediment concentrations of chlorinated organic compounds did not exceed their Probable Effects
Levels in the vast majority of monitored areas of the Chesapeake Bay, and thus are not likely to exert
negative impacts to aquatic biota.
In conclusion, comparison of sediment contaminant levels with available sediment quality guidelines
indicate that the risk to aquatic biota from sediment contamination varies widely throughout the Chesapeake
Bay and its tidal tributaries. A few restricted areas of the Bay which are heavily industrialized and/or
urbanized, specifically the Baltimore Harbor, Back River, Anacostia River, and Elizabeth River, have
sediment concentrations of several contaminants which are high enough to adversely impact aquatic
organisms. Estimates of the relative risk to aquatic biota due to sediment contamination at these areas are
much higher than for areas elsewhere in the Bay.
Areas in and near the heavily urbanized or rapidly growing areas in the northern and western shores of the
Chesapeake Bay have the next highest estimates of risk to aquatic biota from sediment contamination. A
relatively large area of the Bay has sediment concentrations of toxics that are not high enough to be
considered likely to cause adverse biological effects to aquatic organisms.
IX-8
-------
RISK TO AQUATIC BIOTA DUE TO
SEDIMENT CONTAMINANT CONCENTRATIONS
tO
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Sediment Score
8
17
Figure 9.1 Distribution of scores of sites in the Chesapeake Bay based on the risk to
aquatic biota due to sediment contaminant concentrations. Most sites have sediment
contaminant concentrations well below the levels at which adverse effects to aquatic
biota are likely to occur. However, a few sites have much higher levels of sediment
contaminants which may represent a significant risk of adverse effects to aquatic biota.
IX-9
-------
Table 9.4. Substitutions for missing data to allow complete index values to be calculated (in addition to
those mentioned in the text). Note that virtually all of the substituted values were well below the PEL and
did not effect the score.
Station
Proxy Station
Naphthalene
Upper ChesterRrver
Upper Choptank River
Bush River
Gunpowder River
Mattawoman Creek
South Tangier Sound
Pocomoke River
Upper Nanticoke River
Manokin River
Big Annemessex River
Lower Chester River
Lower Choptank River
Middle River
Middle River
Potomac Transition
North Tangier Sound
Wicomico River
Lower Nanticoke River
Wicomico River
Wicomico River
Phenanthrene
Upper ChesterRrver
Upper Choptank River
James R. Transition
Bush River
Gunpowder River
Mattawoman Creek
Upper Nanticoke River
Lower Chester River
Lower Choptank River
James River Tidal Fresh
Middle River
Middle River
Potomac Transition
Lower Nanticoke River
Anthracene
Upper Choptank River
Lfttle Choptank River
James River Transition
Mattawoman Creek
North Tangier Sound
Pocomoke Sound
Upper Nanticoke River
Manokin River
Big Annemessex River
Lower Choptank River
Lower Choptank River
James River Tidal Fresh
Potomac Transition
South Tangier Sound
Pocomoke River
Lower Nanticoke River
Wicomico River
Wicomico River
Chrvsene
Upper Chester River
Upper Choptank River
Bush River
Gunpowder River
Lower Chester River
Lower Choptank River
Middle River
Middle River
Benzofa)pvrene
Mattawoman Creek
North Tangier Sound
Pocomoke River
Upper Nanticoke River
James River Transition
Potomac Transition
South Tangier Sound '
Wicomico River
Lower Nanticoke River
James River Tidal Fresh
IX-10
-------
Appendices
A. Chesapeake Bay sedimentation rates
B. Quality assurance/quality control data for the Virginia Institute of Marine Science
Laboratory
C. Quality assurance/quality control data for sediment metals analysis at the
Maryland Department of Health and Mental Hygiene
D, Quality assurance/quality control data for sediment total organic carbon
measurements of the Chesapeake Biological Laboratory
E. Sediment grain size composition analysis methods
F. Quality assurance/quality control data for the Maryland Department of
Agriculture
-------
-------
Appendix A: Chesapeake Bay sedimentation rates
Below is a listing of selected sediment accumulation rates for various regions of
Chesapeake Bay found in the literature. Where estimates of laboratory precision were
available, the standard deviation of the estimate is expressed as mean ± standard
deviation unless otherwise noted.
Original
Station
ApproxSedimentationDepthin
IVlLJf*" Dr%4_. ft ,,
Sediment
(equiv. yrs.) Year
Furnace B. No e_
UB-1 (Turkey Pt.) -MCB2 1
GS-2 i,**,
GS-2
GS-3
GS-3
CHSP1416
GIWX1II
GIWXIV
GS-4
MCB2.2
MCB3.1
MCB3.1
MCB3.3C
MCB3.3C
MCB3.3C
-MCB3.3W
-MCB3.3W
1C
-.
(Choptank)~MCB4.2C
-MCB4.2C
t .
StabonC -MCB4.2E
Schubel &
Hirschberg, 1977
Cr-> MCB43C
-7 (Parker Cr.) MCB4.3C
-A MCB5.1
MCB5-1
MCB5.2
MCB5.2
LE3.6
D Brush- 1
Rapp.R.SpftCB61
0.96
0.38'
0.06
0.12
0.22
3.1
I.1
1.'
0.13
0.72
0.15
0.54
0.28
0.26
0.21
0.08
0.10
0.09-0
12
Mainstem
0-2(80-78)1980
0-2(88-55)1988
0-1 (88-80)1988
1-2(80-75)1988
— 1975
~ 1972
— 1972
0-1 (88-80) 1988
1-2(80-79)1988
0-1 (88-81) 1988
1-2(81-79)1988
0-3(85-75)1985
0-10 (85-18)1985
0-2 (85-76) 1985
0-1 (88-75) 1988
1-2(75-65)1988
Method Corer Author
Pollen
Pollen
Pollen
Pollen
Pollen
Pb-210
Pb-210
Pb-210
Pollen
Pollen
Pollen
Pollen
Pollen
Pollen
Pollen
Pollen
Pollen
—
Gray.
Grav.
Grav.
Grav.
Box
Grav.
Grav.
Grav.
Grav.
Grav.
Grav.
Grav.
_
Grav.
Grav.
Pb-210
0.12
0.12
0.07
0.06
0.007
0.005
>0.32
0-1 (88-80) 1988
1-2(80-71)1988
-57)1988
0-1 (88-45) 1988
Po|,en
° *
Grav.
Grav.
post-European 1988
-..
Rapp.R.SpitCB6.1
v .r, ,
YorkR.Spft CB6 3
GS:21 York R. Spit CB6 3
GS-21 York R. Spft CB6.3
Brush, 1990
2 Cape Charles CB7
GS-22 Cape Charles CB7
Brush, 1990
0.08
0.15
0.10
0.14
0.14
0.04
0.15
0.15
0.09
t-European
1988
post-European
Po,,en
1988
Pollen
pol,en
1988
1988
European
1988
Grav.
Pollen
Grav.
Grav.
Pollen
Grav.
Grav.
Pollen
Grav.
Grav.
Pollen
Brush, 1989
Brush, 1990
Brush, 1990
.Brush, 1990
Brush, 1990
Goldberg etal. 1973
Goldberg etaJ. 1973
Goldberg etal. 1973.
Brush, 1990
Brush, 1990
Brush, 1990
Brush. 1990
Brush. 1990
Brush, 1990
Brush, 1990
Brush, 1990
Brush, 1990
Grav.
Brush. 1990
Brush, 1990
Brush. 1990
Brush. 1990
Brush. 1990
Brush, 1990
Grav.
Brush. 1990
Brush, 1990
Grav.
Brush. 1990
Brush, 1990
Grav.
Brush, 1990
Brush, 1990
Grav
App-i
-------
Maryland Tributaries
Back R.
Back R.
MWT4.1
Above STP
0.93'
0.771.08"
(80-58)
1980
(74-30)
Pollen
1974
Pollen
Brush,
Piston
,1989
c.
Brush, 1984 b
Back R.
Middle R.
Mouth (MWT4
.1) 0.2'
(74-1780) 1974
Head of River 0.1510.2'
(74-1780)
Pollen
1974
Piston c.
Pollen
Brush,
Piston
, 1984b
c.
Brush, 1984b
Magothy
Magothy
Nanticoke
Western Shore
Upstream*
Midstream2
Downstream2
Magothy
Magothy
Nanticoke
i
0.23
0.14
0.20
0.30*
D.391.031
0.371.031
0.17±.02J
(80-1 700J
(80-1700)
(80-1700)
(80-1700)
Pollen
Pollen
Pollen
Pollen
—
—
—
Brush
Brush
Brush
Brush
, 1984a
, 1934 a
, 1984 a
, 1984a
Potomac
Approx.Sedimentabon
Original
Station
1
1
3
3
4
4
7
9
9
10
10
11
11
14
14
15
15
MDE
Equiv.
MLE2.3
MLE2.3
MLE2.2
MLE2.2
MLE2.2
MLE2.2
XDA1177
XDA1177
XDA1177
XDA1177
XDA1177
XDA1177
XEA6596
XEA6596
XEA6596
XEA6596
XEA6596
XEA6596
Rate
Depth in
Sediment
(cm/yr) (equiv. yrs.)
0.211.02
0.171.02
0.561.05
0.701.04
0.561.05
0.791.09
>0.81
1.461.06
0.481.04
0.671.06
0.401.03
0.471.04
>0.72
1.091.14
0.221.02
0.431.05
0.671.06
1.741.12
78-1840
78-1878
78-1840
78-1878
78-1840
78-1878
78-1840
78-1878
78-1840
78-1878
78-1840
78-1878
78-1840
78-1878
78-1840
78-1878
78-1840
78-1878
Year
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
Method
Pollen
Pb-210b
Pollen
Pb-210
Pollen •
Pb-210
Pollen
Pb-210
Pollen
Pb-210
Pollen
Pb-210
Pollen
Pb-210
Pollen
Pb-210
Pollen
Pb-210
Corer
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Divers
Author
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
Brush
etal. 1982
era/. 1982
et al. 1982
etal. 1982
etal. 1982
etal. 1982
etal. 1982
etal. 1982
etal. 1982
etal. 1982
etal. 1982
et al. 1982
etal. 1982
etal. 1982
etal. 1982
etal. 1982
etal. 1982
etal 1982
•GS-23 Hog Is., James R,
Brush, 1990
Virginia Tributaries
LE5.2 >0.30 post-European
1988
Pollen Grav.
* average of several cores.
6 for all Pb-210 values for Brush et al., 1982 the uncertainty is the uncertainty associated with indrvdual
activities; as the measured activity approaches background levels, the uncertainty increases.
1 39 cores in 10 western shore tributaries (Middle, Magothy. St. Mary's. Ware, Gunpowder, Back, Patapsco,
Patuxent, and Potomac rivers, and Furnace Bay).
z based on samples for western shore.
App-ii
-------
Appendix B: Quality assurance/quality control data for the Virginia Institute of Marine Science
laboratory
The Virginia Institute of Marine Science (VIMS) laboratory performed analyses for sediment concentrations
of mainstem metals and organic compounds, and organic compounds for Virginia tributaries. All data
presented below is QA/QC information which covered their report of data from 1991 (Unger etal., 1992).
I. Metals.
A. Comparison of mean VIMS analytical values to certified values of Standard Reference materials SRM
1646 (estuarine sediment).
n is the number of samples (1991) used to calculate the mean; CV is the NIST certified value; Range is the
95% tolerance range for the certified materials. Recovery is the percent of certified value recovered in
analysis. All values rounded to the nearest tenth. Data from Unger etal. (1992).
Estuarine Sediment SRM 1646 (Al and Fe in % dry weight, all others in ppm)
Metal Mean n CV Range
Al
As
Cd
Cr
Cu
Fe
Pb
Mn
Ni
Zn
0.77
9.7
0.30
39
19
2.96
23.7
268
26
118
3
3
3
3
3
3
3
3
3
3
6.25
11.6
0.36
76
18.0
3.35
28.2
375.0
32.0
138
.7-.89
9.5-10
•233-.331
38.2-39
18.3-20.4
2.88- 3.15
23.1-24.5
244.0 -288 0
20.7-31.6
110-134
Recovery (%)
12
84
83
51
106
88
64
71
81
86
Af
As
Cd
Cr
Cu
Fe
Pb
Mn
Ni
Zn-
95
90
92
115-124
102
89
97
107
101
110
2
2
2
2
2
2
2
2
2
2
91-98
86-94
85-100
120
96-108
85-94
91-103
106-108
99-103
109-110
App-iii
-------
II. Acid-volatile sulfide
The method used to measure acid-volatile sulfide (AVS) in mainstem sediments in 1991 was tested using
laboratory fortified blanks from freshly prepared sodium sulfide standard solutions over a range of expected
sulfide concentrations. Results are presented below. Data are from Linger et at.. 1992.
Sample
{mg sulfide)
Recovered
(mg sulfide)
%
Recovery
0.497
0.499
0.933
10.15
9.923
99.23
100.1
Mean Recovery, p
Std. Dev, 0
Control limit, u±3o
0.512
0.485
0.946
9.991
9.375
94.16
94.58
97.2
3.6
86.4-108
103.2
97.2
95.2
98.4
94.5
94.9
94.5
Recovery from sulfide fortified sediment samples. Data from Unger etal, 1992.
Sample % Recovery
CB5.4 88.7
LE3.6 99.9
WE4.1 89.2
The detection limits for AVS was 2 ppm.
III. Polycyclic aromatic hydrocarbons
1. Analysis of Standard Reference Material 1941. Concentrations as ppb (ng/g dry weight) as determined
by gas chromatography with a flame ionization detector. CV is NIST certified value. Measured value is the
value determined by the VIMS laboratory. Data are from Unger et a/., 1992.
Compound
CV
Measured
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo(a)anthracene
Chrysene
Benzo(a)pyrene
Perylene
Benzo(g,h,i)perylene
lrideno(g.h,i)perylene
59714
202±6
1116120
1008116
538112
577112
566112
41518
478114
572128
643
237
1366
1426
422
431
431
194
339
151
'Twelve samples analyzed in triplicate by NIST
Replicate analyses of two of the 1991 samples demonstrated good precision in measurement of individual
.PAHs.
App-iv
-------
IV. PCBs
The following is a summary of information in linger, et a/. 1992, and more detailed information on analysis
of the individual PCB congeners is available in that report.
Analysis of NIST Standard Sediment {SRM 1941)
Sample
Congener Subtota I*
Total PCBs*
NIST reported value
VIMS measured vale
111.3
143.9
247
320
* total of the eight congeners used in estimating total PCBs
** estimated total PCBs based on the assumption that the congener subtotal represent 44.9% of the total
PCBs. This percentage is based on the average percentage in a mixture of ArochJors 1254 and 1260.
which were thought to most closely match the mix of conngeners found in the sediment samples.
A recovery of 80.2% of estimated total PCBs was found for a spiked sand sample. Detection limits for
individual PCB conceners were 0.01
V. Other chlorinated hydrocarbons
Unger et ai. , (1 992) report that two of the mainstem samples were analyzed in duplicate, and that good
agreement of results was observed between replicate samples.
App-v
-------
Appendix C: Quality assurance/quality control data for sediment metals analysis at the Maryland
Department of Health and Mental Hygiene.
The Maryland Department of Health and Mental Health and Mental Hygiene (OHMH) laboratory performed
measurements of sediment metal concentrations for sediment samples from Maryland tributaries.
I. Instrument detection levels for metals.
Element
AJ
As
Cd
Cr
Cu
Fe
Hg
Mn
Ni
Pb
Zn
GF AA' (ppm)
. r
0.001
—
—
—
—
—
—
—
—
—
ICP2 (ppm)
0.05
—
0.01
0.01
0.01
0.01
—
0.01
0.01
0.10
0.01
Cold Vapor (ppm)
_
—
—
—
—
0.05
—
—
—
—
1 Graphite furnace atomic absorption
2 Inductively coupled plasma
II. Comparison of mean DHMH analytical values to certified values of Standard Reference materials SRM
1645 (river sediment) and SRM 1646 (estuarine sediment), n is the number of samples (1987 to 1991)
used to calculate the mean; CV is the NIST certified value; Range is the 95% tolerance range for the
certified materials. Units are ppm (pg/g) dry weight.
River Sediment
SRM 1645
Estuarine Sediment
SRM 1646
Metal
As
Cd
Cr
Cu
Fe
Pb
Mn
Hg
Ni
Zn
Mean
47.16
9.1
2.8
101.6
10.8
659.6
711.3
0.753
43.6
1746.8
n
5
6
6
3
5
5
2
4
5
CV
661
10.2
3.0
109.0
11.3
714
785
1.1
45.6
1720
Range
N/A1
8.7-11.7
2.7-3.2
90.0-128.0
10.1-12.5
686.0-742.0
688.0-882.0
0.6-1.6
42.9-48.7
1550-1890
Mean
12.1
0.383
55.6
16.6
3.1
25.1
316.0
0.066
28.9
134.6
n
5
5
5
4
4
4
3
5
4
CV
11.6
0.36
76.0
18.0
3.4
28.2
375.0
0.063
32.0
138
Range
10.3-12.9
0.29-0.43
73.0-79.0
15.0-21.0
3.3-3.5
26.4-30.0
355.0 -395.0
0.051 0.075
29.0-35.0
132.0-144.0
As
Cd
Cu
Fe
Pb
SRM 1648
81.0
584.0
4.0
4.01-4.21
0.62
75
609
3.9
8-82
582 -636
3.8-4.0
SRM 2704
4.3
4.1
0.66 0.58 - 0.74
App-vi
-------
885.0
Mn
Ni
Zn 0.457
1 860
1 0.476
'No certified value available. Arsenic
ss pait „, Suppl8men,a, ^^
App-vii
-------
III. Summary statistics for laboratory duplicates (1987-1991). N is the number of paired
samples; Percent is the average percent of the mean represented by the standard deviation
(o/M*100). The range indicates the highest and lowest analytical results to show the range of
values for which the standard deviations were calculated.
Metal
Al
As
Cd
Cr
Cu
Fe
Hg
Mn
Ni
Pb
Zn
11
12
11
20
21
18
5
22
22
17
22
Percent
2.7
5.2
9.9
4.0
3.8
2.8
4.7
1.7
7.1
9.7
2.2
Minimum
11,166
6.4
0.5
18
7
15,520
0.009
228
10.1
5.2
52
Maximum
41,042
64.7
3.34
558
198
67,026
0.283
2,669
59.8
204.7
683.5
App-viii
-------
Appendix O: Quality Assurance/Quality Control data for sediment total organic carbon
measurements of the Chesapeake Biological Laboratory.
The Chesapeake Bay Biological Laboratory performed determinations of total sediment organic carbon
content for sediment samples from Maryland tributaries.
The detection limit for percent sediment carbon was established as three times the standard deviation of
seven repeated analyses. Inorganic carbon in Chesapeake Bay samples is insignificant and was ignored.
Three samples were chosen for the determination, representing low, medium, and high ranges, as
determined by the initial analyses.
Table 1: Samples chosen for determination of percent sediment carbon detection limits.
Year Station Listed TOCS value
1988
1991
1991
MET7.1
XDE5339
MWT5.1C
0.67
3.47
9.29
In addition, standard reference estuarine sediment supplied by the National Research Council of Canada
(BCSS-1) was analyzed. The certified value for this material was 2.19 •*•/- 0.09%
Table 2: Results of replicate analyses for determination of percent sediment organic carbon
detection limits.
Replicate
MET7.1
XCE5339
MWT5.1C
BCSS-1
1
2
3
4
5
6
7
Mean
Sid.
MDL
Dev.
0.99
1.34
1.48
0.79
0.74
1.02
0.94
1.04
0.274
0.82
3.53
3.60
3.50
3.50
3.64
3.50
3.46
3.53
0.064
0.19
6.48'
4.5.5
4.53
4.86
5.05
5.15
5.26
5.13
0.660
1.98
2.11
2.14
2.11
2.14
2.20
2.10
2.20
2.14
0.042
0.13
The method detection limit of the least variable Chesapeake Bay sample (XDE5339) is accepted
as the general method detection limit for this test.
App-ix
-------
Appendix E: Sediment grain size composition analysis methods
The method for the measurement of sediment grain size distribution generally followed those of Plumb
(1981) as described briefly below.
Detergent (sodium hexametaphosphate) was added to sediment samples to prevent flocculation. Samples
were wet sieved sequentially through 1000 urn and 62 urn screens. Each size fraction was dried at 50°C
and weighed to determine the gravel (>1000 pm), sand (62-1000 urn), and mud (<62 urn) fractions.
Results are expressed as percent of dry weight. Percent moisture is the difference between wet and dry
weights after drying unmodified sediment at 5D*C.
This method, without organic digestion, determines the "apparent" particle size, which is more repesentative
of the sediment's actual exposed surface than is the particle size determined after organic digestion.
App-x
-------
Appendix F: Quality assurance/quality control data for the Maryland Department of Agriculture
The Maryland Department of Agriculture performed the analysis of organic compounds in sediments
samples from the Maryland tributaries in 1991. The following information is the quality assurance/quality
control (QA/QC) data for the analyses of these 1991 samples. Quality control procedures consisted of
spiked samples for PAHs and pesticides and spiked samples and analysis of NIST reference material 1939
for PCBs.
I. List of Analytes
PAHs
Anthracene
Acenaphthylene
Acenaphthene
2-Methylnaphthalene
Benzo(a)anthracene
Benzo(a)pyrene
Chrysene
Fluoranthene
3,4-Benzofluoranthene
Benzo(k)fluoranthene
Napthalene
Perylene
Benzo(ghi)perylene
Fluorene
Phenanthrene
Pyrene
Dibenzo(ah)anthracene
lndeno(1.2,3-cd)anthracene
Phenol
PCBs
Total PCBs
Pesticides
Alachlor
Afdrin
Atrazine (and other triazines, e.g., cyanazine, simazine)
Carbofuran
Chlordane (oxychlordane, heptachlor, heptachlor epoxide)
Chlorpyrifos (Dursban)
DDTs
Oieldrin
Heptachlor
Hexachiorobenzene
Undane (alpha-BHC)
Metolachlor
Permethrin
App-xi
-------
If. Polycyclic Aromatic Hydrocarbons
A. Percentage recovery from spiked samples
Compound
N
Phenanthrene
Anthracene
Benzofajanthracene
Benzojajpyrene
5
5
5
5
70.6
702
88.1
772
15.7
3.3
10.2
18.1
N is the number of samples. Std. Oev. is the standard deviation of the percentage recovery for the spiked
samples.
B. Analysts of standard materials
No Analysis of NIST reference materials were performed for the PAHs.
II. Pesticides and PCBs
A. Percentage recoveries from spiked samples
Compound
2,3,5-Trichloro-
biphenyi
Heptachlor
Dieldrin
Cyanazine
Carbofuran
N
4
4
5
5
5
P
73.6
69.8
84.1
85.3
91.8
a
18
11.2
5.7
27.5
19
B. Analysis of NIST reference material for PCBs
Compound
NIST Value
(u±o)
Measured Value
(u±o) -
2,3,5-Trichlorobiphenyl
2,2'3,5-Tetrachloro-
biphenyi
4.20 ± 0.29 ppm
1.07 ± 0.12 ppm
3.70 ± 0.29
1.07 ±0.08
App-xii
-------
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^/
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