Sediment contaminants in Casco Bay, Maine: inventories, sources, and potential for biological impact

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Environmental Science and Technology


An inventory-based approach to environmental assessment that determines concentrations of sedimentary contaminants, defines their origins, and assesses the potential for biological impact is illustrated in Casco Bay, ME. The most widespread contaminants in Casco Bay are petroleum and petroleum byproducts. The highest concentrations of contaminants are associated with population centers, effluent outfalls, and spills. The majority of PAH in sediments are the product of high-temperature combustion processes. PAH concentrations at sites in close proximity to Portland exceed values believed to produce toxic responses in marine benthic organisms. In contrast, PCB, DDTs, and chlordane concentrations in the sediments are below concentrations thought to produce toxic effects in marine organisms. Metal concentrations in sediments are also below those that elicit biological responses. The geographic distribution of contaminants is initially controlled by the proximity to sources, and the regional differences in concentrations are the result of sediment accumulation patterns. Detrital (terrestrial), autochthonous marine, pyrogenic, and petroleum sources for PAH, alkanes, and trace metals are defined.


This project has been funded wholly or in part by the United States Environmental Protection Agency as part of the Casco Bay Estuary Project underAassistance Agreement CE-001553-01 to the New England Interstate Water Pollution Control Commission. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. We would also like to thank the National Oceanic and Atmospheric Administration (Contract 50-DGNC-5-00262), National Status and Trends Program, for providing baseline data for comparison.


Sediments; Toxics; Monitoring Water Quality; Casco Bay


Casco Bay