Circulation and Contaminant Transport in Massachusetts Coastal Waters

U.S. Geological Survey studies show that the concentrations of metals in surface sediments of Boston Harbor are decreasing with time. This conclusion is supported by analysis of (1) surface sediments collected at monitoring stations in the outer harbor between 1977 and 1993, (2) sediment cores from depositional areas of the harbor, and (3) historical data from a contaminated-sediment data base, which includes information on metal and organic contaminants and sediment texture. During the 16 years of the continuing study, chromium, lead, mercury, silver, and zinc concentrations in surface sediments have decreased by about 50 percent. Although these trends are indeed encouraging, concentrations of some metals in harbor sediments are still above levels considered toxic to certain bottom-dwelling organisms. Type: Bay Waterbody or Watershed Names: Boston Harbor