MA1 Large-Scale Investigations of Contaminated Sediments
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() Effect of spatial scale on relationships between sediment quality guidelines and toxicity.

Bay, S1, Vidal, D1, Field, L2, Myre, P3, 1 Southern California Coastal Water Research Project, Westminster, CA, USA2 National Oceanic and Atmospheric Administration, Seattle, WA, USA3 EXA Data and Mapping Services, Port Townsend, WA, USA

ABSTRACT- A correspondence between sediment quality guideline (SQG) values and the incidence of toxicity has been demonstrated for several datasets and provides evidence for the predictive ability of SQGs. Site-specific or regional differences in habitat or contamination characteristics may affect the performance of SQGs, however, creating uncertainty regarding their suitability or application. The availability of synoptic sediment quality data from regional monitoring and other assessment programs provides the opportunity to evaluate SQG performance on a regional level and identify the best SQGs for specific applications. A dataset consisting of matched coastal southern California sediment chemistry and acute amphipod toxicity measurements for 1100 samples was developed using regional monitoring data and dredge material characterization information. This dataset was used to evaluate the performance of several SQG approaches, including the effects range-median (ERM), apparent effects threshold (AET), and logistic regression model (LRM). The efficiency, sensitivity, and specificity of each SQG was determined at three spatial scales: entire study area, bays and harbors only, and Los Angeles region harbors only. The efficiency of the mean ERM quotient varied from 85% to 35% depending upon the spatial scale of the dataset. Comparisons with datasets from locations outside of California also indicated differences in SQG performance. A variety of factors may have been responsible for these regional differences in SQG performance, including differences in contamination patterns or magnitude among the regions, as well as differences in toxicity test sensitivity.

Key words: sediment, sediment quality guideline, toxicity, chemistry

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