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Our Work

We examine organic contaminants and general geochemistry of freshwater systems, especially locally impacted ones such as the Anacostia River.ÌýÌýUrban rivers are beset with environmental problems associated with land use and human infrastructure development.ÌýWe examine altered geochemistry in the river, try to determine causes and look for signs of change as regional efforts to improve the river's water quality proceed. The biogeochemical lab also examines fatty acid profiles in sediments to characterize bacterial community members. Profiles give clues to bacterial types as well as algae and diatom species.ÌýÌýThe lab also characterizes food web structure and climate resilience using field and laboratory stable isotope studies.Ìý

Active Projects

Assessing seep amphipod and isopod resilience to environmental warming by metabolic plasticity proxy Funded by the Cave Conservancy of the Virginias

Invertebrates which inhabit perched aquifers and seepage springs have limited mobility and are likely to be exposed to rising temperatures as soil environments warm in response to climate change. This proposal will investigate the resilience of two commonly observed seep invertebrates to climate change; the isopod, Caecidotea kenkiÌýand the amphipod, Gammarus minus. It will examine theirÌýresilience to warming by determining the "plasticity" of metabolic activity at different temperatures using isotope geochemical techniques.

Investigation into the concentration and distribution of bisphenol A (BPA) in Anacostia and Potomac River sediments
Funded by the Water Resources Research Institute/USGS

Recent investigations into contaminants in the Anacostia River and its tributaries have revealed the widespread occurrence of microplastics.ÌýOne of the reasons that microplastics are receiving so much attention lately has been the realization that the additives are likely to leach from the hydrocarbon plastic they are associated with and may become reactive contaminants. One chemical that was not tested for, but likely to occur in the Anacostia (since the plastics are so widespread), is bisphenol A (BPA). BPA, a compound derived from polycarbonate plastics where it is used as a plasticizer, is endocrine disrupting for vertebrates and potentially lethal for phytoplankton. This project will investigate the occurrence and concentration of bisphenol A in sediments at 4 locations within the Anacostia watershed and 3 locations in the Potomac and test the hypothesis that BPA should be higher in the more urban areas of the Anacostia relative to suburban areas or the Potomac River sites.