Spatial and temporal aspects of sedimentary trace metal concentrations in mid-coast Maine

Abstract

The concentrations of Cd, Cr, Cu, Ni, Pb, Sn and Zn in the surface sediments of 41 stations in the mid-coast Maine region of the Gulf of Maine were determined. The 14 stations located in Casco Bay had previously been surveyed in 1980. Metal concentrations were distributed heterogeneously between subregions of the study area, and generally exceeded pre-industrial levels. Highest levels occurred in Booth Bay, where comparisons with the National Status and Trends Program database conservatively placed Cd, Cu and Pb levels in the top quadrile of sites nationwide. Spatial distributions were consistent with transport from the large Kennebec-Androscoggin watershed, supplemented by localized inputs. Within Casco Bay, Cd, Cr, Pb and Zn appeared to have declined since 1980, while Ni was unchanged and Cu increased throughout the entire Bay.