John Wiley & Sons, Ltd.

Active biomonitoring locates pollutant sources in the Anacostia River (MD; DC; USA)

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The freshwater Anacostia River watershed (MD, DC, USA) was surveyed for the sources of bioavailable EPA Priority Pollutants and toxic metals by active biomontoring (ABM) using the freshwater Asiatic clam Corbicula fluminea. The Anacostia River is a 456km2 tributary of the tidal freshwater Potomac River that includes the city of Washington DC where edible fish are highly contaminated with PCBs and chlordane. From 1999 to 2011 Corbicula were collected for ABM from a Potomac reference site and translocated in cages placed at 45 sites in the tidal and nontidal Anacostia watershed. Minimum clam mortality and maximum contaminant bioaccumulation was with two‐week translocation. The clam tissues (28‐50) were combined at sites and analyzed by TestAmerica for 66 EPA Priority Pollutants plus technical chlordane, benz(e)pyrene and six metals (As, Cd, Cr, Cu, Fe, Pb). Tissue contaminants reflected water, not sediment, levels. To compare sites all contaminant data above detection or reference were grouped as Total Metals (TMET) Total Polycyclic Aromatic Hydrocarbons (TPAH), Total PCB congeners (TPCB), Total Pesticides (TPEST) and Total Technical Chlordane (TCHL). Tidal Anacostia ABM found highest TPAH and TCHL upstream at Bladensburg Marina (MD) except for TCHL at site PP near the confluence. Five nontidal MD subtributaries (94% of flow) had 17 sites with bioavailable TPAH, TPCB or TCHL two to five times higher than found at the toxic‐sediment “hotspots” near Washington. The only TMET noted was Fe at one site. TPAH in MD subtributaries was highest near industrial parks and Metro stations. A napthalene spill was detected in Watts Branch. TPCB (low‐molecular‐weight) originated upstream at one industrial park. TCHL (80% of TPEST) was two to five times the USFDA action in four nontidal tributaries where heptachlor indicated legacy chlordane dumpsites. TCHL fell to reference below a stormwater pond, suggesting transport via suspended sediment. Controlling the formation and movement of contaminated TSS in MD should enable the uncontaminated‐sediment capping of Washington DC's toxic‐sediment “hot‐spots” that are presently considered responsible for fish contamination. This article is protected by copyright. All rights reserved

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