Sediment Quality

Organic Compounds and Trace Elements in Freshwater Streambed Sediment and Fish from the Puget Sound Basin
By Dorene E. MacCoy and Robert W. Black
(Adapted from the National Water-Quality Assessment Program's Puget Sound Basin NAWQA Study, U.S. Geological Survey Fact Sheet 105-98, September 1998)

As part of the National Water-Quality Assessment (NAWQA) Program, the U.S. Geological Survey (USGS) is investigating contaminants in streambed sediment and aquatic organisms and their relation to land use. One such study is being done in the Puget Sound Basin, which is located in northwestern Washington State and includes streams and rivers that drain to the Puget Sound, the Strait of Georgia, and the Strait of Juan de Fuca, but does not include marine waters. The basin encompasses 13,700 square miles; forest, urban, and agriculture are the principal land uses.

Summary of Findings

Organochlorine compounds
Highest concentrations of organochlorine compounds in streambed sediment were at an urban site on Thornton Creek near Seattle, where total chlordane, DDT, DDD, and DDE were found to exceed Canadian sediment quality guidelines. Concentrations are compared to Canadian guidelines because there are no sediment quality guidelines for organochlorine compounds in the State of Washington (in 1998).

Highest concentrations of organochlorine compounds in sculpin (a bottom-feeding fish) were also found at the Thornton Creek site. Data for concentrations in fish are compared to New York State criteria because there are no criteria for protection of fish-eating wildlife in the State of Washington. PCBs and total DDT (DDT+DDD +DDE) exceeded New York State criteria for protection of fish-eating wildlife at Thornton Creek, and total PCBs exceeded these criteria at the West Branch of Kelsey Creek at Bellevue, another urban site.

Effects
Elevated levels of organochlorine compounds such as DDT and PCBs are toxic to all animals and can bioconcentrate in tissue, cause tumors, and cause hormonal and behavioral problems. They can also suppress the immune and respiratory systems and cause abnormal development in aquatic species. The primary effect on aquatic communities is to reduce numbers of sensitive species, allowing species that are more resistant to contaminants to become dominant (Harte and others 1991).

PAHs
Polycyclic aromatic hydrocarbon concentrations in streambed sediment exceeded Canadian guidelines in most urban streams and were highest at the West Branch of Kelsey Creek at Bellevue.

Effects
Many PAHs, such as benzo(a)anthracene, benzo(a)pyrene, and chrysene, are carcinogenic, causing tumors in fish and other animals, and are acutely toxic to some organisms. Noncarcinogenic PAHs, such as fluoranthene, phenathrene, and pyrene, are also toxic to some organisms. The effects on aquatic organisms of the PAHs found in sediment at Kelsey Creek are unknown, but concentrations of benzo(a)pyrene as high as those observed in this study can cause precancerous tumors in fish (Eisler 1987).

Trace elements
Concentrations of arsenic, cadmium, lead, mercury, and zinc frequently exceeded forest and reference conditions in streambed sediment and sculpin in urban streams.

Effects
Elevated levels of arsenic, cadmium, lead, mercury, and zinc may not be of concern in a naturally metal-rich region such as Puget Sound because the aquatic system has adapted to this type of environment, but excessive amounts of these elements can affect the nervous, respiratory, circulatory, and reproductive systems of aquatic organisms, as well as affect their development and feeding habits (Rand and Petrocelli 1985).

Data Collection and Analysis

Streambed sediment and whole sculpin tissue were analyzed to assess the occurrence and distribution of contaminants and to better understand the fate of contaminants in the environment (See Table 1). We collected samples in September 1995 from 18 sites, which were characterized on the basis of the predominant land use in the stream's basin – 4 agricultural sites, 9 urban sites, 2 forest sites, and 3 reference sites, which are mostly forested and receive minimal impact from humans. At each site we collected the top 2-3 centimeters of streambed sediment in depositional areas; predatory bottom-feeding fish (sculpin) were collected from 17 of these sites. (See Crawford and Luoma 1994, and Shelton and Capel 1994, for a more complete description of the methods used.)

Table 1. Contaminants analyzed for sediment in streambed and whole sculpin tissue from the Puget Sound Basin.

Fine-grained sediment and tissue accumulate trace elements and organic compounds associated with anthropogenic (human-related) activities. Sculpin are bottom-feeding fish that are not usually consumed by humans but are eaten by other fish and fish-eating wildlife. Organic compounds analyzed for were organochlorine pesticides, total PCBs, and other organic compounds; of the other organic compounds, only PAH values that exceeded Canadian guidelines are reported because they may have the most potential to harm aquatic and related organisms.

Evaluation of Data

We compared our data to guidelines and criteria for organic compounds to show possible adverse effects to aquatic organisms and fish-eating wildlife, and to local forest and reference conditions for selected trace elements to show possible effects of land use.

Organic compounds
We compared levels of organochlorine compounds and PAHs detected in sediment to draft interim freshwater sediment quality guidelines developed by the Canadian Council of Ministers of the Environment (CCME). These guidelines were developed from toxicity and species abundance data for benthic organisms from studies throughout North America and represent total concentrations in sieved and unsieved sediment samples (CCME 1995). The guidelines used are the threshold effects level (TEL), below which adverse effects to aquatic organisms are expected to occur rarely, and the probable effects level (PEL), above which adverse effects are predicted to occur frequently. Concentrations that exceed these guidelines may or may not have adverse effects on aquatic organisms; the comparisons should be used to indicate potential sediment quality problems that may warrant further study.

We compared concentrations of organochlorine compounds in sculpin to New York State Department of Environmental Conservation (NYSDEC) criteria (Newell and others 1987). These criteria were determined from laboratory experiments using fish-eating wildlife and are considered one of the best sets of criteria for evaluating the effects of contaminated fish tissue on wildlife.

Definitions of organic compounds found in the Puget Sound Basin

DDT (dichlorodiphenyltrichloroethane) is an organochlorine insecticide banned from use in the U.S. in 1972. Total DDT refers to the sum of DDT and its breakdown products DDE and DDD.

Chlordane is an organochlorine insecticide banned from use in the 1980s. Total chlordane refers to the sum of cis-chlordane, trans-chlordane, cis-nonachlor and trans-nonachlor.

HCB (hexachlorobenzene) is a fungicide used as a seed and soil treatment, restricted from use in the 1980s.

Dieldrin is an organochlorine insecticide with restricted use in the U.S. since the1970s.

Heptachlor epoxide is a breakdown product of the organochlorine insecticide heptachlor. It was used in the U.S. until the1970s.

PCBs (polychlorinated biphenyls) are by-products of a variety of industrial products. Manufacture was stopped in the 1970s. There are over 209 breakdown products of PCBs, and total PCB refers to the sum of all forms detected.

PAHs (polycyclic aromatic hydrocarbons) are natural by-products of forest fires. Other sources include the steel and petroleum industry, the manufacture of coal tar and asphalt, power generation, burning trash, and vehicle emissions. Tons are emitted to the atmosphere and introduced to aquatic environments through oil spills and sewage discharge.

Trace elements
We compared concentrations of selected trace elements in streambed sediment and sculpin tissue to median concentrations from the forest and reference sites. Land-use impacts may cause concentrations from the agricultural and urban sites to exceed these medians.

Table 2. Organic compounds that exceed Canadian probable effects levels (PEL) and New York State Department of Environmental Conservation (NYSDEC) criteria, and trace elements that exceed median of forest and reference conditions at sampling sites in the Puget Sound Basin.

Organic Compounds Detected in Streambed Sediment

Organochlorine pesticides were detected at 3 of the 18 sites sampled for streambed sediment: an agricultural site on Fishtrap Creek in the northern part of the basin, an urban site on Thornton Creek near Seattle, and a reference site on Rock Creek near Maple Valley. The highest concentrations were found at the urban site on Thornton Creek.

PAHs were most frequently detected in streambed sediment samples from urban streams. Data for Fishtrap Creek, an agricultural site, is available in Table 3.

Table 3. Concentrations of polycyclic aromatic hydrocarbons (PAHs) in Fishtrap Creek streambed sediment that exceed Canadian guidelines [values in micrograms per kilogram, dry weight; nd means not detected or below 50 micrograms per kilogram method detection limit]

Organochlorine Compounds Detected in Tissue

Organochlorine compounds in whole sculpin tissue from selected creeks in the Puget Sound Basin were compared to New York State Department of Environmental Conservation (NYSDEC) criteria.

Total PCBs and or at least 1 of 26 organochlorine pesticides were detected in tissue at 2 agricultural sites (Bertrand and Fishtrap Creeks). The Bertrand site detected Total DDT at a level of approximately 30 micrograms per kilogram wet weight. The Fishtrap site detected Total DDT at approximately 55 micrograms per kilogram, along with Chlordane at a level of approximately 40 micrograms per kilogram.

Trace Elements Detected in Streambed Sediment and Whole Sculpin Tissue

Concentrations of arsenic, cadmium, chromium, lead, mercury, nickel, and zinc were elevated in streambed sediment and sculpin from agricultural and urban sites compared to concentrations from the forest and reference sites. Arsenic and the heavy metals cadmium, lead, mercury, and zinc had the highest concentrations and the greatest range of concentrations at urban sites compared to those from the agricultural and the combined forest and reference sites, indicating possible enrichment of these elements in the urban areas. The concentrations detected do not necessarily have negative impacts on the environment, but do suggest that land use may have led to increased levels of these elements.

References Cited

CCME (Canadian Council of Ministers of the Environment). 1995. "Protocol for the derivation of Canadian sediment quality guidelines for the protection of aquatic life." CCME EPC-98E, Task Group on Water Quality Guidelines Report. Winnipeg, Manitoba.

Crawford, J. Kent, and Luoma, Samuel N. 1994. "Guidelines for studies of contaminants in biological tissues for the National Water-Quality Assessment Program." U.S. Geological Survey Open-File Report 92-494.

Eisler, R. 1987. "Polycyclic aromatic hydrocarbon hazards to fish, wildlife, and invertebrates – a synoptic review." Patuxent Wildlife Research Center, U.S. Fish and Wildlife Service, Biological Report 85. Laurel, MD.

Harte, John, Cheryl Holdren, Richard Schneider, and Christine Shirley. 1991. Toxics A to Z--A Guide to Everyday Pollution Hazards. University of California Press. Berkeley, CA.

Newell, Arthur J., David W. Johnson, and Laurie K. Allen. 1987. "Niagara River biota contamination project – Fish flesh criteria for piscivorous wildlife." New York State Department of Environmental Conservation, Division of Fish and Wildlife, Bureau of Environmental Protection, Technical Report 87-3.

Rand, G.M., and S.R. Petrocelli. 1985. Fundamentals of Aquatic Toxicology: Methods and Applications. Hemisphere. New York.

Shelton, L.R., and P.D. Capel. 1994. "Guidelines for collecting and processing samples of stream bed sediment for analysis of trace elements and organic contaminants for the National Water-Quality Assessment Program." U.S. Geological Survey Open-File Report 94-458.

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