Sediment quality in Los Angeles Harbor, USA: A triad assessment

Sediment quality in the Los Angeles and Long Beach Harbor area of southern California, USA, was assessed from 1992 to 1997 as part of the California S tate Water Resources Control Board's Bay Protection and Toxic Cleanup Progr am and the National Oceanic and Atmospheric Administration's National Statu s and Trends Program. The assessment strategy relied on application of vari ous components of the sediment quality triad, combined with bioaccumulation measures, in a weight-of-evidence approach to sediment quality investigati ons. Results of bulk-phase chemical measurements, solid-phase amphipod toxi city tests, pore-water toxicity tests with invertebrate embryos, benthic co mmunity analyses (presented as a relative benthic index), and bioaccumulati on measures indicated that inner harbor areas of this system are polluted b y high concentrations of a mixture of sediment-associated contaminants and that this pollution is highly correlated with toxicity in laboratory experi ments and degradation of benthic community structure. While 29% of sediment samples from this system were toxic to amphipods (Rhepoxynius abronius or Eohaustorius estuarius), 79% were toxic to abalone embryos (Haliotis rufesc ens) exposed to 100% pore-water concentrations. Statistical analyses indica ted that amphipod survival in laboratory toxicity tests was significantly c orrelated with the number of crustacean species and the total number of spe cies measured in the benthos at these stations. Triad measures were incorpo rated into a decision matrix designed to classify stations based on degree of sediment pollution, toxicity, benthic community degradation, and, where applicable, tissue concentrations in laboratory-exposed bivalves and feral fish.