Magnitude and extent of contaminated sediment and toxicity in Chesapeake Bay

Original publisher: [Silver Spring, Md.?]: U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, National Ocean Service, [2007] OCLC Number: (OCoLC)85847602 Subject: Water quality bioassay -- Chesapeake Bay (Md. and Va.). Excerpt: ... assure collection of recently deposited materials. Amphipod mortality, sea urchin fertilization impairment, Microtox ® luminesence, and cytochrome P450 Human Reporter Gene System ( HRGS ) tests were carried out by contract laboratories on sediment samples or extracts. A broad suite of chemicals were analyzed at each station, including 13 metals, butyl-tins, PAHs, chlorinated compounds ( PCBs, chlorinated pesticides, furans and dioxins ). In addition several physicochemical measures of sediment properties ( e.g. grain size, TOC, etc. ) were determined. Quantitative benthic community characterizations included enumeration of species composition and calculation of density, species richness, evenness, and diversity indices. Correlation coefficients were calculated between all chemical, toxicological and biological metrics. Regressions were calculated to assess relationships between toxicological, community, contaminant, and habitat attributes. Regressions of toxicity, community, contaminant and habitat indices against % silt clay content were calculated and the residuals were used to assess regression relationships between them in the absence of the influence of grain size. Multivariate cluster analysis was used to group site and species data. A nodal analysis routine was then applied to those results combining the cluster analyses in a graphical array. The objective of the nodal analysis was to produce a coherent pattern of association between results for sites and species clusters. Principal component analysis ( PCA ) was used to group the sampling sites using benthic community, contaminant, and toxicity metrics. Calculation of a Sediment Quality Triad ( SQT ) index was developed to quantify impact, and results w...