Estimates of the Spatial Extent of Sediment Toxicity in Major U.S. Estuaries

Acute laboratory toxicity tests were performed on surficial sediments collected from 1176 locations throughout 22 estuarine areas in the United States. Toxicity was determined with three standardized procedures: 10-day amphipod survival tests with solid-phase (bulk) sediments; 5-min microbial bioluminescence tests with organic solvent extracts of the sediments; and either 1-h sea urchin fertilization tests or 48-h mollusc embryo tests with the porewater of the sediments. Test results were weighted to the sizes (km2) of the geographic strata in which samples were collected. Selected bays and estuaries were sampled along the Atlantic and Gulf of Mexico coasts and in southern California along the Pacific coast of the United States. The individual survey areas ranged in size from