ABSTRACT
Surface water quality has improved in the United States because of better regulation and treatment, but sediments remain as sinks for historical releases of metals and organic contaminants. Sediment contamination is present in more than 70% of U.S. watersheds, with a total estimated surficial volume of more than 1 billion m3 [U.S. Environmental Protection Agency (USEPA), 1997]. Both point and nonpoint pollution sources contribute to this problem. Metals, including arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn), are often found in the sediments of harbors and other areas that are affected by anthropogenic activities. Sediments containing these contaminants act as secondary sources of contamination, posing significant direct and indirect environmental risks through bioaccumulation in aquatic organisms and incorporation into aquatic food webs that may ultimately lead to humans [National Research Council (NRC), 2003]. Episodic physical redistribution of contaminated sediments within dynamic waterways can disperse such environmental risks, potentially affecting biological and water quality conditions and moving contaminated sediment far from the original source (Admiral et al., 2000).
