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Using a weight of evidence approach for assessing remediation of contaminated sediments using biological indicators, food web tissue contamination, biotic condition and DNA damage
Citation:
Lazorchak, Jim, J. Meier, K. Fritz, M. Mills, P. Wernsing, H. Haring, D. Walters, J. Kraus, AND B. Armstrong. Using a weight of evidence approach for assessing remediation of contaminated sediments using biological indicators, food web tissue contamination, biotic condition and DNA damage. SETAC Europe, Nantes, FRANCE, May 22 - 26, 2016.
Impact/Purpose:
Present most recent findings on using a weight of evidence approach for assessing remedy effectiveness. This is a presentation on a Cross ORD effort over a number of years assessing pre and post remedy effectiveness.
Description:
The Ottawa River lies in extreme northwest Ohio, flowing into Lake Erie’s western basin at the City of Toledo. The Ottawa River is a component of the Maumee River AOC as defined by the International Commission. The Ottawa River is approximately 45 miles long; however, the 2009-2010 remediation project took place in the lower 8.8 miles of the river where urban and industrial activities have had a detrimental impact on the river as a beneficial resource. The primary COCs at the site are PCBs, PAHs, inorganics (principally lead), and oil and grease. Approximately 260,000 yd3 of contaminated sediments were removed from the study reach. Removal was accomplished through dredging in targeted areas within 3 reaches of the river where COCs exceeded a target level. The overall objectives of this research effort are twofold: 1) Develop chemical, physical, and biological tools and approaches to evaluate the quantity and sources of post-dredge residuals; and 2) Develop an approach to quantify remedial effectiveness using chemical, physical, and biological tools and approaches. This presentation will focus on 2 of the biological tools: assessing response of various trophic levels to changes in tissue concentrations of PCBs and PAHs and DNA damage in Brown Bullheads. From 2009-2013, pre- and post-remedy sampling of fishes representative of different trophic levels was conducted via electroshocking and fyke net sampling. Fishes collected were largemouth bass, brown bullhead, white suckers, sunfish (e.g., pumpkinseed), gizzard shad, and small short-lived adult fish (SSLAF); including bluntnose minnows and emerald shiners. Our hypothesis was that SSLAF would show changes in tissue concentrations of PCBs sooner than higher trophic levels due to their short life cycles of 2-3 years. Results for the entire project area (across 3 reaches) indicate that tissue concentrations at all trophic levels and DNA damage in brown bullheads increased during-dredging then declined in subsequent years. Wet weight PCB concentrations indicated that, after 3 years post-dredging, gizzard shad and emerald shiners showed lower tissue concentrations compared to pre-dredging; tissue concentrations for Largemouth Bass and white suckers showed no change tissue concentrations compared to pre-dredging. There were differences in tissue concentrations among the 3 reaches studied, as well as year to year differences in the percent lipids by species and by reach. PAH data is currently being analyzed and will also be presented.
