ES&T Series: Assessing Contaminated Aquatic Sediments

Technol. , 1992, 26 (10), pp 1862–1863. DOI: 10.1021/es00034a613. Publication Date: October 1992 ... Environmental Science & Technology. Adams, Kime...
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T SERIES PA recently released its proposed contaminated sediment management strategy ( 1 ) . The agency is refocusine water 001lution control efforts-from point sources to nonpoint sources of pollution, and contaminated sediments-one nonpoint source-are thought to be one of the largest risks to the aquatic environment. Recent studies by the National Academy of Sciences and EPA have shown that hundreds of sites across the country are severely contaminated, and aquatic life and its consumers are being harmed. Several regulatory statutes-such as the Clean Water Act; the Toxic Substances Control Act; the Federal Insecticide, Fungicide and Rodenticide Act; Superfund and the Resource Conservation and Recovery Act-give EPA the authority to address and manage contaminated sediments. The EPA programs that implement these statutes are now finalizing their mediaspecific program actions to reduce ecological and human health risks from contaminated sediments. During the past three years, a number of hills have been presented in Congress as well as research initiatives aimed at assessing, remediating, and controlling sediment contamination. Unfortunately, the true extent and significance of the problem are not well defined, and the scientific approaches for defining and correcting the problem are relatively new and unproven. As a result, there has been a flurry of research on assessing and remediating sediments. Sediments by nature are difficult to deal with. Many synthetic organics and metals tend to sorb to particulates that eventually end up as bottom deposits. Once there, they may become unavailable to the overlying ecosystem, they may be transformed into more or less toxic forms, or they may migrate from the sediment into benthic organisms or into overlying waters. Ultimately, they can be taken up in the food chain, contaminating fish, wildlife, and humans. Whether or not the contaminants will remain in place or contaminate the ecosystem is difficult to determine. No single answer will suffice for all sites. A number of promising methods have been developed in recent years for assessing the extent and severity of sediment contamination.




In our first article of a two-part series, William Adams, Richard Kimerle, and James Barnett, Jr., present the strengths and weaknesses of the methods that have been successfully used in ecosystem assessments. They present a tiered test strategy that combines multiple approaches, ensuring that study conclusions are reliable and based on weight of evidence. In Part 2 of the series, John Scott and I focus on one sediment contamination approach toxicity testing. Toxicity testing of sediments is a relatively new science which has developed rapidly into a reliable

1862 Enviran. Sei. Technoi.. Voi. 26. No. 10 1992

and efficient tool for evaluating the biological risk of contaminants in sediments. Based on the effectiveness of toxicity testing in EPA's National Pollutant Discharge Elimination System permitting, it appears that this approach will he a useful regulatory tool in the near future. The ecological hazard and risk assessment process is rapidly growing and improving [see ESbT series beginning in the Feb. 1992 issue). Contaminated sediments are only one component of the ecosystem assessment, but in some aquatic ecosystems that may be the major source of stress to ecosystem health.

0013-936w92/0926-1862$03.00/00 199.2 American Chemical Societv

Because sediments and their interactions with ecosystem processes are equally complex, assessment of their role will always be a challenge. Despite this complexity, effective tools exist for assessing the problem.

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Reference E.; Kravitz. M.; Wall, T. In Sediment Toxicity Assessment; Burton, G.A,, Jr., Ed.; Lewis Publishers: Boca Raton. FL. 1992; pp. 341-70.

(1) Southerland.


G. Allen Burton. Ir.. is on associate professor and director of the Environmental Health Sciences Program at Wright State University in Dayton, OH. A graduate of the University of Texas at l h i i m hc, hi!., ilorked for EPA and was u visiting feiint(. with the Cooperative Institute f o r Rrseurch in Environmental Sciences at the University of Colorado. He serves an several committees of professional societies and state and federal agencies. He has wriiten or coauthored more than 50 scientific publications dealing with aquatic systems.

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Technol.. Vol. 26. No. 10, 1992