SPATIAL AND TEMPORAL ASPECTS OF SEDIMENTARY TRACE-METAL CONCENTRATIONS IN MID-COAST MAINE

The concentrations of Cd, Cr, Cu, Ni, Pb, Sn and Zn in the surface sed iments of 41 stations in the mid-coast Maine region of the Gulf of Mai ne were determined. The 14 stations located in Casco Bay had previousl y been surveyed in 1980. Metal concentrations were distributed heterog eneously between subregions of the study area, and generally exceeded pre-industrial levels. Highest levels occurred in Booth Bay, where com parisons with the National Status and Trends Program database conserva tively placed Cd, Cu and Pb levels in the top quadrile of sites nation wide. Spatial distributions were consistent with transport from the la rge Kennebec-Androscoggin watershed, supplemented by localized inputs. Within Casco Bay, Cd, Cr, Pb and Zn appeared to have declined since 1 980, while Ni was unchanged and Cu increased throughout the entire Bay .