Sediment Contaminants of the Gulf of Mexico

Abstract

Contaminants in coastal sediments are compared with continental shelf/slope and abyssal sediments. Early introductions of contaminants to sediments were due to agricultural pesticide use, increased populations in, and industrialization of, coastal areas, and oil and gas exploration and production post-World War II. Coastal estuaries were judged to be in good to poor condition with concentrations of metals and pesticides in more than 40 % and concentrations of PAHs and PCBs in less than 1 % of coastal sediments exceeding levels suspected of causing biological effects. Within bay systems, steep gradients in contaminant concentrations were observed near population centers, agricultural activities, and industrial complexes. Highest concentrations of DDT, PCBs, PAHs, Ag, As, Cd, Hg, Pb, Sn, and Zn were found in sediments near population centers, agricultural lands, and industrial/military complexes. Natural petroleum seepage is the major source of hydrocarbons in north central Gulf of Mexico continental shelf/slope sediments.