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Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Procedures for the Determination of the Freely Dissolved Interstitial Water Concentrations of Nonionic Organics
U.S. EPA. Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Procedures for the Determination of the Freely Dissolved Interstitial Water Concentrations of Nonionic Organics. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-02/012, 2012.
This equilibrium partitioning sediment benchmark (ESB) document was prepared by scientists from the Atlantic Ecology Division, Mid-Continent Ecology Division, and Western Ecology Division, the Office of Water, and private consultants. The document describes procedures to determine the interstitial water concentrations of nonionic organic chemicals in contaminated sediments. Based on these concentrations, guidance is provided on the derivation of toxic units to assess whether the sediments are likely to cause adverse effects to benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it is based on the concentrations of chemical(s) that are known to be harmful and bioavailable in the environment. This document, and five others published over the last nine years, will be useful for the Program Offices, including Superfund, and Regions in conducting contami¬nated sediment assessments. The documents represent approximately 20 years of research and development by scientists working within EPA’s Office of Research and Development (ORD), as well as the Office of Water, and review of the scientific approach by the Agency’s Science Advisory Board (SAB). Originally, these documents were to be published by the Office of Water as a series of formal sediment quality criteria (SQC), but the decision was made approximately ten years ago for ORD to publish the ESBs as technical information. Consequently, the document is being published purely to aid in conducting sediment assessments.
This document describes procedures to determine the concentrations of nonionic organic chemicals in sediment interstitial waters. In previous ESB documents, the general equilibrium partitioning (EqP) approach was chosen for the derivation of sediment benchmarks because it accounts for the varying bioavailability of chemicals in different sediments and allows for the incorporation of the appropriate biological effects concentration. This provides for the derivation of benchmarks that are causally linked to the specific chemical, applicable across sediments, and appropriately protective of benthic organisms.
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