Hormone disruption and environmental pollutants in Anacostia and Potomac river fish, Washington DC : District of Columbia Water Resources Research Institute

The Anacostia River in Washington, D.C. is among the 10 most contaminated rivers in the USA, containing sewage, metals, PAHs, and PCBs. The biogeochemical characteristics of tidal freshwater urban rivers, including the Anacostia, remain largely unstudied. The effects of organic chemicals on fishes in urban rivers has been of increasing concern. This study examined base-flow geochemistry and nutrients dynamics over a 1.5 year period (April 2010- Sept 2011), concentrating on inorganics (Ca, Mg, Na, S, K, P, NO3, NH4, PO4, B, Ba, Ni, Co), organic hydrocarbons, sediment and water column particulate C and N stable isotopes and total organic carbon. The study also examined organic compounds in fish tissues from one site in the Anacostia. Water and sediment were sampled from three tidal freshwater sites along the Anacostia River approximately every 8 weeks. 15N values of sediment and water column particulates ranged from 2 to 9‰, with the most enriched values occurring downstream (4 to 9‰). While these values may not reflect sewage inputs, an overall enrichment was observed between spring and late summer, which may indicate microbial activity. 13C values exhibited slightly more variation and ranged from -30 to -25‰. All sites showed relative depletion in early summer compared with spring or late summer/fall. C/N ratios were generally between 13-19 in sediments, indicating autochthonous origins. Water nutrients (NO3 and NH4) demonstrated seasonal fluxes; all sites showed a peak in nutrients during early summer (May/June) and subsequent decline. Overall, NO3 ranged from about 0.2 to 3.3 mg/L and NH4 ranged from 0 to 1.7 μg/L. Principle Component Analysis (PCA) of aqueous geochemical data from the three sites suggests the strongest control of water chemistry (31-39%) is a Ca/Mg component that was also strongly associated with NO3 and Na (although Na was not correlated at the middle site). High concentrations and co-variance of Na, Mg and Ca indicate that cement is a strong driver of river chemistry. A suspected endocrine disrupting chemical was isolated from the middle site only. Possible disrupters were not detected in the Anacostia Fundulus heteroclitus tested (from Bladensburg). Other hydrocarbons were characterized from sediment samples at all three sites.