104 



BIOLOGICAL REPORT 31 



sediments in the harbor and the restricted circula- 

 tion inland of the hurricane barrier at the mouth of 

 the harbor, most of the PCB's will remain in harbor 

 sediments and be buried by natural accretion. At 

 present, the major source of PCB's to the bay 

 proper appears to be by atmospheric deposition 

 (Mayer 1 982; Farrington and Capuzzo 1 990; SAIC 

 1991). 



In 1 982, New Bedford Harbor was selected 

 by the EPA for inclusion on the National Priorities 

 List of the Nation's worst hazardous waste sites, 

 making it eligible for Superfund cleanup funds. The 

 site of contamination is large (over 400 ha), with 

 the most serious contamination occurring near the 

 head of the estuary, where PCB concentrations 

 approach 30,000 ppm in the sediments. PCB's have 

 been detected in the tissues of shellfish, lobster, and 

 flounder, indicating mobilization of this contaminant 

 through the food chain, primarily through the inges- 

 tion of contaminated sediments or contaminated 

 prey (Fig. 6.3). Although the highest tissue concen- 

 trations are found nearest the site of greatest con- 

 tamination, elevated concentratioas have been found 



Fig. 6.3. Average PCB concentrations for lobsters and 

 winter flounder collected at various stations around 

 Buzzards Bay Note the high concentration at New 

 Bedford Data from J Schwartz Massachusetts Di- 

 vision of Marine Fisheries, and Buzzards Bay Project 

 (1987) 



throughout the bay. The PCB's migrate from the 

 highly contaminated bottom sediments into the over- 

 lying water column primarily through desorption, 

 sediment resuspension by boundary layer currents, 

 and through sediment reworking by benthic organ- 

 isms. PCB contamination will be a hazard to the 

 ecological health of New Bedford and Buzzards 

 Bay for a long time. 



Trace Metals. New Bedford Harbor is also 

 the primary location for trace metal contamination 

 within Buzzards Bay. Metals, including cadmium, 

 chromium, lead, mercury, copper, silver, nickel, and 

 arsenic, can enter bay waters through industrial 

 waste discharge, boat paint, sewage effluent, and 

 dredged material, as well as through atmospheric 

 deposition and natural rock weathering. Industrial 

 activities and the wastewater treatment facility in 

 New Bedford, however, are dominant sources of 

 these contaminants. Although industrial use of cop- 

 per for metal plating, historically a large industry in 

 the New Bedford area, is no longer prevalent, the 

 use of copper-containing antifouling paints and cop- 

 per pipes for water lines continues to input low lev- 

 els of copper to the bay. Elevated concentrations 

 of metals have been found in mussels, mummichogs, 

 and winter flounder in New Bedford Harbor, as 

 well as in ring-billed gulls and mice, indicating 

 biomagnification of metals may be occurring through 

 the food chain (IEP, Inc. 1988). Elevated levels of 

 metals are found in the adjacent saltwater wetlands 

 and in the detritivores and their predators living and 

 feeding in these wetlands. As with PCB's, tissue 

 concentrations are generally highest in areas near- 

 est the areas of direct contamination (New Bedford 

 Inner Harbor and near the outfall); nevertheless, mo- 

 bilization of these metals is believed to be occurring 

 through food chain transfer within the New Bedford 

 Harbor system, as well as potentially to Buzzards 

 Bay (Farrington and Capuzzo 1 990; SAIC 1 99 1 ). 



6.1.5. Nutrients and Cultural 

 Eutrophication 



Although the basic ecology of much of the Buz- 

 zards Bay system remains relatively healthy and 



