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Biogeochemistry Laboratory

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.

  • Olivia Ventresca, Ashley Acevedo, Kristina Nicholas, Jonathan Craig, Sophia Carpenter, Christia Fisher, Madeleine Danzberger, Cassidy Williams, Barbara Balestra and Stephen MacAvoy. 2024. Concentration and distribution of specific siloxanes (D5 and D6) and PAHs in the Anacostia and Potomac Rivers, USA. Water16Ìý16, 2059.

  • Davey E, Meiller J, Kontana K, Fox D, Landaverde N, MacAvoy SE, Balestra B. (2023). Microplastics and polycyclic aromatic hydrocarbons: abundance, distribution, and chemical analyses in the Nash Run, an urban tributary to the Anacostia River (Washington, DC). Water, Air and Soil Pollution 234: 493.

  • Malik, S, Cohen A, MacAvoyÌýSE, Connaughton VP. (2023). The importance of assessing water quality in tributaries: A case study in an urban waterway using zebrafish (Danio rerio). Water 15: 2372.

  • Jessup, WH, Wiegand J, Delbridge-Perry M, MacAvoyÌýSE, Connaughton VP. (2022). Development effects of siloxane exposure in zebrafish: a comparison study using laboratory-mixed and environmental water samples. Journal of Applied ToxicologyÌý1-19 DOI: 10.1002/jat.4369Ìý

  • MacAvoy SE and Lunine A. Ìý(2022).Ìý. ÌýWater 14(9): 1330Ìý(doi.org/10.3390/w14091330).

  • Jessup, WH, Wiegand J, Delbridge-Perry M, MacAvoy SE, Connaughton VP. 2022. . ÌýJournal of Applied Toxicology 1-19 (doi.org/10.1002/jat.4369).

Sky Chaus

Sky Chaus is a senior majoring in Environmental Science and Leadership and Ethical Development. She/They are working on a project to quantify the concentration of Bisphenol A (BPA) in Anacostia and Potomac River sediments. Sky will be testing to see if there is a greater concentration of the chemical in urban or suburban areas.

Margaret Golembiewski

Margaret Golembiewski is a senior majoring in environmental science. She is working on extracting and characterizing Siloxanes and polycyclicÌýaromatic hydrocarbonsÌý(PAHs) in soil samples from urban and suburban sites along the Anacostia river and tributaries.
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Daniel Punales

Daniel Punales is a senior at American University pursuing a dual degree in Environmental Science (BS) and Political Science (BA). Focusing on the intersection of quantitative analysis and policy research, Daniel is working with Professor MacAvoy to analyze the spatial distribution of organic contaminants across the Anacostia and Potomac rivers in Washington, DC. With these findings, he intends to determine viable paths to improve stormwater management in the District, and more broadly, across urban areas in the United States.Ìý

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