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WP1 Sediment Quality Assessment
() Sediment contamination in the Anacostia River: A pollution history of Washington, D.C.
Riedel, G1, Velinsky, D2, Ashley, J3, Wade, T4, Cornwell, J5, 1 Smithsonian Environmental Research Center, Edgewater, MD, USA2 Academy of Natural Sciences, Philadelphia, PA, USA3 Philadelphia University, Philadelpha, PA, USA4 Texas A&M University, College Station, TX5 University of Maryland Center for Environmental Science, Cambridge, MD
ABSTRACT- Six sediment cores of approximately 5 meters in total length were collected from the lower tidal Anacostia River in Washington D.C. via vibracore in June, 2003. Cores were sampled for grain size, trace elements (Ag, Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn), trace organic compounds (total PCBs, PAHs, and semivolatile organic compounds) as well as 210Pb and 14C dating. Trace elements showed a variety of patterns with depth, but for a large number of metals (e.g., Ag, Cd, Cr, Cu, Hg, Pb and Zn), and trace organics (e.g. total PCBs and total PAHs) there was a distinct three part profile, with low concentrations in the deepest sediments, the highest concentrations in the middle of the cores, and moderate, and generally decreasing, concentrations towards the tops of the cores. The 210Pb data suggests that the lower portion of the cores are from the pre-industrial period, while the higher contaminant region of the cores represent the late 19th and early 20th century period, and the top moderate contaminant portions of the cores are recent sediment, demonstrating the efficacy of recent pollution controls. PAH profiles are dominated by HMW compounds (pyrene, phenanthrene, benzo(e)pyrene) suggesting pyrogenic source and or proximity to current input, while preliminary PCB profiles show a mid-core peak, with concentrations up to 3 ppm-dw. Organic contaminant profiles, especially PCBs, suggest post depositional migration and/or additional sources (groundwater). Pore waters were extracted for As analysis at several down core locations, particularly in coarse sands and gravel deposits capable of permitting the movement of solutes. Evidence for post depositional diagenetic transport of As is supported in some of the cores, and in some instances, As concentrations exceeding the drinking water standard (10 g L-1) were found in sandy aquifer layers.
Key words: sediment cores, Anacostia River, trace elements, organic contaminants
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