Trace Metal-Sediment Dynamics in Estuaries: Pollution Assessment

The concentrations of trace metals vary widely in estuaries worldwide, owing to fluxes of metals from natural sources, pulsed anthropogenic inputs, changes in the extent of weathering, erosion, and runoff, complex biogeochemical processes, and a range of bioaccumulation effects that often differ markedly within these coastal ecotones. Because of large natural inputs of trace metals from the weathering and erosion of rocks, soils, and ore-bearing deposits as well as from volcanic activity and atmospheric fallout, it is difficult to assess the effects of elemental inputs from specific human activities. Historically, trace metal pollution increased most markedly in the United States between 1940 and 1970, largely because of human population development in the coastal zone and rapid industrial growth (Kennish 1992, 1994, 1997; Valette-Silver 1993).