Contaminants in the Coastal Ocean

The environmental health of Boston Harbor and Massachusetts Bay is of public concern. Massachusetts Bay, Cape Cod Bay, and the adjacent Gulf of Maine (fig.1) are used for transportation, fishing, recreation, and waste disposal and are an important habitat for endangered marine animals. Elimination of the discharge of sewage sludge to the harbor, improved sewage treatment, and pollution source control have significantly reduced contaminant loads to the harbor. However, there remains concern about the effects of moving the discharge of treated sewage effluent from Boston Harbor into Massachusetts Bay scheduled to begin in 1998. Understanding this coastal system and long-term monitoring are essential in order to assess environmental change.

Figure 1. Perspective map of Massachusetts Bay and Cape Cod Bay illustrating the complex underwater topography. The region is approximately 100 km long and 40 km wide. Stellwagen Bank rises to within about 20 m of the sea surface and partially isolates Massachusetts Bay from the Gulf of Maine. Beginning in 1998, the discharge of treated sewage effluent from the Boston metropolitan area will be relocated from Boston Harbor to a new site 15 km offshore (approximately 35-m water depth) in Massachusetts Bay. The location of the Deer Island Treatment Plant (red dot), the future outfall, the Massachusetts Bay disposal site (MBDS), and the Stellwagen Bank National Marine Sanctuary (SBNMS) are also shown. Note that the MBDS is located outside the SBNMS. Vertical exaggeration is 100X.

Many contaminants introduced into the coastal ocean are associated with particles. After repeated cycles of transport, deposition, resuspension, and biological and chemical interactions, contaminants on particles eventually may be buried in bottom sediments. U.S. Geological Survey (USGS) studies in Boston Harbor and Massachusetts Bay are designed to provide an understanding of how sediments and associated contaminants are transported and where they accumulate in the Massachusetts Bay system.