From acenaphthene to zirconium, more than 1,000 toxic substances have been detected in, released into, or applied to the water, soil, and air of the Chesapeake Bay basin.
These substances have been detected in the water or sediments, sampled in finfish or shellfish tissue, found in atmospheric deposition, documented as having been released through industrial or municipal discharges, monitored in urban runoff, spilled from ships, or applied as pesticides.
They can be lumped into two broad categories: metals, which occur naturally, and organics, which are manmade chemicals. In great enough quantities — and under the right conditions — they can kill. In lesser amounts, they may cause sublethal effects such as reproduction problems or tumors — or they may have no impact at all.
Have those metals and organics caused a toxics problem in the Bay?
Certainly they have, at least in some areas. But the verdict may not fully be in as to the extent or magnitude of the problem.
The best attempt at answering that question comes in the soon-to-be-published “Chesapeake Bay Basinwide Toxics Reduction Strategy Reevaluation Report.” It documents the findings of a nearly two-year effort by the Bay Program’s Toxics Subcommittee to reexamine the 1989 Chesapeake Basinwide Toxics Reduction Strategy.
Information gathered from the reevaluation will help guide the development of a new toxics reduction strategy which will be put together this year and is to be approved by the policy-setting Chesapeake Executive Council this fall.
The reevaluation report is the most comprehensive effort so far to examine the amounts of toxics reaching the Bay (loads), their sources, and their impacts. The near-final draft is 2 inches thick and filled with tables and charts depicting estimated toxic loads and where they come from, trends in fish contamination, estimates of pesticide applications, summaries of major studies relating to toxics in the Bay, and overviews of state programs to control toxics.
What all this says is that the Chesapeake Bay appears to be better off than many other major waterbodies. Contaminant levels in fish and shellfish, as well as toxic concentrations in sediments, are almost uniformly lower than those found in places such as Puget Sound or the Great Lakes. And, many of those contaminant levels appear to be declining.
Unlike the case with nutrients, the report concludes the Bay does not appear to have a severe systemwide problem with toxics. Problems linked to excess nutrients can be found throughout the Bay: reduced oxygen levels in the water and large-scale declines in Bay grasses. By contrast, the most severe problems with toxics — those with the clearest impacts — seem to be limited to a few localized areas near major urban or industrial areas.
But the report does not give the rest of the Bay a clean bill of health: Some levels of toxics can be found almost anywhere. And some examples of impacts — ranging from abnormal development to mortality — have been documented even in areas previously thought to be unaffected. These problems raise “significant concerns” about other parts of the Bay, the report said, but because of a lack of data, the extent of those problems is uncertain.
A 1991 survey by the University of Baltimore’s Schaefer Center for Public Policy found that 77 percent of those polled thought industrial dumping caused a “great deal” of pollution while 68.5 percent thought their own activities had “very little” impact on the environment.
But new information gathered during the reevaluation paints a different picture. A newly developed “Chesapeake Bay Basin Toxics Loading and Release Inventory” indicates that stormwater runoff is the largest source of metals entering the Bay. That runoff from city streets and urban areas also contributes almost as many organics as do “point sources” — industries and municipal sewage treatment plants.
The inventory was a first-ever attempt to estimate the total annual loadings (estimates of actual discharges to the water) and releases (toxics released into the environment, such as pesticides, but not necessarily into the water) throughout the watershed.
The inventory is not complete: For many of the 1,000 chemicals, no information is kept about use or discharges. Many sources, such as urban stormwater runoff, are not strictly regulated; estimates are based on calculations and studies with a wide margin of error. But the inventory does allow for broad comparisons between different kinds of toxic sources.
Estimates of toxics loads are generally divided into two categories: Above fall line, and below fall line. The fall line is the geological boundary between the softer sediments of the Coastal Plain and the harder rock of the Piedmont, and is usually marked by waterfalls. Running through Richmond, Washington, and Baltimore, it is the upper limit of the Bay’s tidal influence. For toxics, the demarcation separates those which originate from the bulk of the Bay’s 64,000-square-mile watershed and are carried downstream, and those which are discharged directly into the Bay and its tidal tributaries.
Above the fall line, stormwater contributes an estimated 1.4 million pounds of metals and about 62,000 pounds of organics; point sources from the same area contribute about 765,000 pounds of metals and about 64,000 pounds of organics. Below the fall line, stormwater contributes roughly 1 million pounds of metals and about 69,620 pounds of organics while point sources contribute about 809,433 pounds of metals and roughly 129,180 pounds of organics.
Stormwater runoff — caused when rainfall flushes residue of city and suburban streets, roofs, parking lots, and lawns — contains a wide variety of metals and organics. Some — chromium, cadmium, chrysene, copper — are among the largest toxic problems in the Bay, according to a 1991 “Toxics of Concern” report that identified the 14 substances with the most potential to impact Bay resources.
The inventory also indicates that a major source of toxics to the water is actually air pollution. Airborne deposition of toxics — resulting from automobile exhaust, fossil fuel combustion at power plants or factories, incinerators, and other sources — seem to contribute an amount of toxics similar to those originating from below fall line point sources.
Other potential sources of toxics include pesticides, an estimated 13.2 million pounds of which are used annually in the Bay watershed. Unlike point and nonpoint sources which are discharged into the water, pesticides are applied on the land and the amount that actually makes it to waterways is uncertain. Elevated amounts of some widely used pesticides — such as atrazine and alachlor — are often detected by water quality monitoring programs during the spring and summer application periods, usually after storm events. But airborne deposition appears to carry slightly more pesticides to the Bay than runoff.
Toxics also result from ship spills and dumping from recreational boats, groundwater, and even pressure-treated wood used in the construction of docks, pilings, and bulkheads, but which contain high levels of copper, chromium, and arsenic, which can leach directly into the water. Each of these could pose the potential of significant impacts in certain areas.
Exactly what these loads mean for the Bay — and the fish, shellfish, benthics, and wildlife that depend on it — is veiled in uncertainty. Although the loads entering the Bay seem large, they are small compared to the overall volume of the Bay. As a result, actual concentrations are usually small — often below common detection limits. “We cannot yet equate loadings with exposure levels in Bay habitats,” the report noted.
Toxics may be quickly deposited — even buried — in the sediment, though under some conditions they may be released back into the water. They may break down into other substances, or mix with other chemicals which make them either more or less harmful. They may be consumed by algae and other micro-organisms, which then may be consumed by larger predators, thereby working their way through the food chain.
To determine the extent of the potential impact of toxics on Bay organisms, concentrations of substances measured in water and sediment are generally compared with thresholds associated with adverse effects seen either in the laboratory or in field studies.
Chesapeake Bay studies have looked at toxic concentrations in three areas: The water column, sediments, and the microlayer.
The microlayer is the thin layer where the water surface meets the air — a millimeter or less in thickness. But it serves as a concentration point for toxic substances. Recent studies have found concentrations of metals, pesticides and organic compounds in the microlayer that often exceed levels in the water below. This may present an important source of exposure to surface-dwelling organisms and to eggs of some fish species that float on the surface.
Elsewhere in the Bay’s water, concentrations of metals rarely exceed the EPA’s water quality criteria or state standards. But the concentrations of metals are elevated in some portions of the tidal and non-tidal tributaries. Still, only a “limited number” of samples have been found to exceed water quality criteria, the report said.
Measurable concentrations of organic compounds in surface waters are rare. Throughout the Bay, concentrations are generally below conventional detection limits. Most organics appear to attach to particles and become embedded in the bottom sediments or are taken up by algae or other biota. The report noted, though, that data for organic compounds in much of the Bay is “very limited” because of the expense of analyzing data for organics.
Levels of contaminants in sediments are closely related to the proximity to pollution sources. The highest sediment concentrations are found near major urban areas and industrial areas in the Bay and its tidal tributaries where stormwater runoff or point sources are concentrated — or combined — to create large contaminant loads. Those areas include the industrialized zones of the Back, Patapsco, and Elizabeth rivers, and the heavily urbanized or rapidly growing areas along the northern western and eastern shores.
Meanwhile, the large amount of toxics that originate from above fall line stormwater runoff are spread over a wider area when they are washed down the rivers and into the Bay. The huge loads from the Susquehanna River, for example, have resulted in higher than normal metal concentrations on the western side of the upper Bay from the Gunpowder River to the Patuxent River. But because the metals are distributed over a wider area, their concentrations do not generally reach those associated with major impacts on resources, such as mortality. While the report said those levels, found in a “relatively high” number of sites primarily in the upper Bay and near the mouths of major tributaries, are not high enough to cause obvious impacts as is the case in some of the industrial areas, they may be great enough to “cause effects of a more subtle nature.”
Trying to clearly link such subtle impacts with low-to-moderate elevations in toxic concentrations is hard. “Elevated concentrations of a toxic substance do not necessarily equal toxicity,” the report said. “The toxicity of that substance to a particular organism is determined by the concentration, frequency, and duration of exposure of the organism to the available form of that toxic substance.”
Many other factors come into play as well, the report noted. Salinity, temperature, pH, and the presence of multiple chemicals in the water can all affect the toxicity of a substance and cloud conclusions about its impact. As a result, determining the “cause-and-effect” relationship between a substance and toxic impacts — from mortality to sublethal effects to loss of diversity in a biologic community — is “exceedingly difficult in most cases.”
And linking more subtle things, such as population changes in a community, to contaminants is even more difficult. The impact of a substance must be sorted out from the effects of predation, fishing, habitat loss, and other water quality parameters — such as low oxygen levels — all of which can affect populations. Despite the uncertainty, research in recent years has lead to some generalized conclusions.
Many studies have shown the effects of water column contamination on organisms in areas known to have high levels of contamination, the Elizabeth, Patapsco, and Anacostia rivers. These effects on fish include liver tumors, cataracts, lesions on the kidney and skin, reduced respiratory ability, impacts on the immune system, and mortality.
Other studies have observed toxic impacts in areas thought to be relatively free of contamination. Menhaden with severe skin ulcers have been sampled in the Rapahhannock, York, and James rivers as well as in the Bay. Liver pathology has been detected in fish taken from the Choptank, Potomac, Susquehanna, Back, and Severn rivers, as well as the Chesapeake and Delaware Canal. Adverse effects on fish gills have been documented on striped bass yearlings from the Chesapeake and Delaware Canal, and the Nansemond, Choptank, Potomac, Susquehanna, Elk, and Sassafras rivers.
What is uncertain is the extent and magnitude of those problems; most research has been focused on areas with known problems. Nonetheless, the report said, this “raises concerns about other regions of the Bay generally not regarded as problem areas.”
Another gauge of impact is the level of contaminants found in finfish and shellfish sampled in the Bay. Generally, contaminant concentrations in the Bay are not as high as the maximum concentrations observed in other parts of the country, such as the Great Lakes or the Northeast states.
Levels have declined enough that past restrictions related to certain contaminants in certain areas — Kepone in the James River and dioxin in the Potomac River within Maryland — have been lifted as contaminant levels fell below health advisory standards. But the report notes that there are many areas where tissue samples have not been studied.
Information available suggests that toxics are not posing a major threat to wildlife around the Bay. Though use of pesticides such as DDT once nearly drove birds such as the bald eagle and the osprey into extinction, their populations rebounded after those chemicals were banned. For other animals, available information shows little adverse impact on populations of mammals, reptiles, and amphibians, though the report notes that little information has been collected about those animals.
Overall, the findings of the re-evaluation supported the observations and conclusions made by Bay researchers in a 1987 review of Chesapeake contaminant issues.
“No matter where we look in the Bay, we find evidence of some chemical contamination,” that review stated. “Many of the contaminants found in highly impacted areas are also now found in remote areas, but at much lower concentrations. There are probably no pristine, truly uncontaminated sites left in Chesapeake Bay.” The review went on to conclude: “In highly impacted areas, such as the Elizabeth River and Baltimore Harbor, evidence of adverse impacts upon aquatic organisms and reduced biological diversity exists. It is likely that toxic materials are responsible for those effects. However, pervasive low level contamination occurring in the mainstem of the Bay has not been equivocally linked to any biological deterioration.”
While reaffirming those basic conclusions, the reevaluation also shed new light on sources and amounts of toxics reaching the Bay. It identified a few additional areas with highly elevated amounts of contaminants — notably portions of the Anacostia — and provided more evidence of toxic impacts for areas other than those with known problems.
Based on its findings, the report makes several management and research recommendations that would help direct future efforts and fulfill the original toxic reduction strategy’s commitment to eliminate toxic impacts in the Bay:
- Adopt a regional focus. The most severe toxics contamination problems are limited to areas with known adverse impacts — the Patapsco, Anacostia, and Elizabeth rivers — often located near urban centers closest to the Bay. Other areas have lower levels of toxics but evidence suggests the contaminants may be having non-lethal impacts, such as reduced growth or reproduction. The reevaluation suggests that problem areas be geographically targeted as “Regions of Concern” — for the most impacted sites — and “Areas of Emphasis” for other potential problem sites. Once designated, these sites would become the focus of multiagency efforts that would include monitoring, research, toxic load reductions, pollution prevention, and other efforts that would ultimately minimize or eliminate adverse impacts on living resources.
- Better assess impacts from low levels of toxics. Traditional monitoring programs sample for particular contaminants and compare the levels detected with water quality standards or criteria to determine whether there is a likely impact on resources. Methods need to be developed to better assess the cumulative impact of exposure to low levels of contaminants on entire biological communities rather than individual species. Signs of stress in the community — such as loss of diversity or reduced reproduction — then might be linked back to particular sources of exposure.
- Expand the focus on the Toxics of Concern List. The original Toxics of Concern list identified 14 substances which are either adversely affecting the Bay or have high potential to do so. The report suggests the list be revised as a risk-based ranking system. In addition, the list should be expanded to include “emerging compounds of concern” — substances which are of concern because of increased use or potential increased loadings — so agencies can find ways to address the chemical through pollution prevention and other actions before it becomes a problem.
- Target pollution prevention actions. The report identified two areas where pollution prevention activities, the preferred way of reducing toxic discharges, could be targeted. The first was expanding the use of integrated pest management which promote techniques that reduce the need for pesticide use. The second was the industrial and commercial sectors, particularly near the regions of concern, which could be reached through chambers of commerce or other existing business organizations.
- Get better estimates of Bay basin toxics loadings and releases. Much of the information used to develop the Chesapeake Bay Basinwide Toxics Loading and Release Inventory Report came from available data which was not collected specifically for estimating toxics loads and releases. The inventory, therefore, presents only a rough, and incomplete, picture. The report outlines a number of tasks — such as changes in monitoring programs and better studies of various toxics sources — that would help to make better estimates. Without a good baseline, the report notes, it will be difficult to measure reductions in toxic loadings to the Bay.
Common contaminants in urban runoff
- Copper — from brake linings, corrosion of copper pipes, and electroplating wastes.
- Cadmium — from motor oil and the corrosion of alloys.
- Zinc — from automobile tires and road salt.
- Chromium — from paints and stains.
- Chrysene, fluoranthene, phenanthrene, and pyrene — from the incomplete combustion of fossil fuels, particularly from wood and coal burned in residential home heating units; and many other substances.
- Arsenic — from fossil fuel combustion.
- Pentachlorophenol — commonly used in wood products, such as telephone poles, to prevent microbial and fungal decay.
- Cyanides — anti-caking ingredients in road salts.
Highlights of Regional Toxics Reduction Efforts
The 1989 Basinwide Toxics Reduction Strategy established two broad goals:
- “The long-term goal of this strategy is to work towards a toxics free Bay by eliminating the discharge of toxic substances from all controllable sources.”
- “By the year 2000, the input of toxic substances from all controllable sources to the Chesapeake Bay will be reduced to levels that result in no toxic or bioaccumulative impacts on the living resources that inhabit the Bay or on human health.”
- The report cites several examples of progress to reduce toxics since the strategy was written:
- The Bay basin states have identified 68 facilities as dischargers of toxic substances in quantities that exceed water quality standards or criteria and have taken actions necessary to reduce toxics loadings from these facilities.
- The EPA’s national Toxics Release Inventory has reported significant decreases in Bay basin industrial releases of toxic substances to air, land, and water since 1988.
- Virginia began implementation of the Elizabeth River Toxics Initiative in 1988 with investigations of the sources of toxics loadings and ambient concentrations. The state has also allocated resources for permit writing and inspection of the Elizabeth River facilities.
- Maryland has documented substantial reductions in toxics discharged into Baltimore Harbor and the Patapsco River. The reductions resulted in significant improvements in the number and diversity of bottom-dwelling organisms.
- Mainstem Bay sediment concentrations of metals have declined significantly since the late 1970s, and organic compounds have declined since the late 1940s.
- Basinwide decreases in organochlorine pesticide concentrations in Bay water birds have resulted in steadily increasing populations of bald eagles and osprey.
- Thousands of acres of agricultural land in the Bay watershed have been brought under a system of integrated pest management.
- Counties and municipalities in Pennsylvania, Maryland, and Virginia collect a wide range of potentially hazardous household products from thousands of residents through innovative collection programs.
Toward a New Toxics Strategy
The Executive Council last fall directed that a new Basinwide Toxics Reduction Strategy be developed for it to approve when it meets this fall. The new strategy, the council directed, should:
- Emphasize pollution prevention as the preferred approach to reducing risks posed to humans and the Bay’s living resources;
- Be consistent with the requirements of the federal Clean Water and Clean Air acts, and go beyond those requirements where needed to benefit the Bay’s resources;
- Develop a regional focus to target comprehensive pollution reduction and restoration efforts in the areas with the worst problems;
- Gather additional information about the impacts of toxics on Bay resources, especially impacts from low -level concentrations of contaminants in Bay habitats.
Representatives from state, federal, and local governments, along with business representatives, environmentalists, and scientists recently met as part of a “toxics summit” to begin drafting broad goals for the new strategy as well as specific implementation objectives by which to meet those goals.
A draft strategy is expected to be available for comment in the late spring or summer.
The Alliance for the Chesapeake Bay is producing a “white paper” dealing with issues related to toxics in the Bay and the development of a new strategy. The paper will be available this spring.
Also, the Bay Journal will be publishing a series of articles on toxics issues, along with information about the new strategy, throughout the spring and summer.