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Biogeochemistry Laboratory

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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.

  • 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).

Hana Bahlawan.

Hana Bahlawan

Hana Bahlawan is a senior majoring in Environmental Science. She is also a member of the US Air Force ROTC (Lt. Col. AFROTC)! Hana is examining the concentration and distribution of a novel PAH (polycyclic aromatic hydrocarbon) called Bibenzyl which is used in flame retardants, electronics, and textile production. She is looking at both suburban and urban steam sediments that may receive different degrees of sewage input and will test for differences.
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Laura Dudek Headshot

Laura Dudek

Laura Dudek is a junior majoring in Environmental Studies and minoring in Sociology. She is focusing on analyzing sediments collected from three sites along the Anacostia River. She will identify notable compounds and calculate the percent of organic matter and bacterial counts foundÌýwithin the samples.

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Mia Fanuzzi.

Mia Fanuzzi

Mia Fanuzzi is a junior majoring in Biology. This semester she is assisting in Dr. MacAvoy’s project comparing and contrasting sediment fatty acids from sites in suburban Anacostia and Potomac. I am working on extracting and separating fatty acids and characterizing them with a GC/MS to see what these fatty acid profiles show about the different sites (bacterial species, algae, diatoms, etc).Ìý

Christia Fisher, AU Biogeochemistry Lab.

Christia Fisher

Christia Fisher is a 5-year BS/MS student working on characterizing PAHs and siloxanes from urban sites on the Anacostia River, Washington, DC.
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Photo of Megan Godfrey

Megan Godfrey

Megan Godfrey is a senior undergraduate student at Â鶹¹û¶³´«Ã½, majoring in Environment Science and minoring in Public Health. She came to DC from the US Virgin Islands in 2017 and after graduating in May 2021, she hopes to work for an environmental organization that focusses on the intersections between human and environmental health and environmental justice. She’s currently working on a research project in coordination with Dr. Stephen Macavoy and several other students to test the toxicity of organic contaminants in urban and suburban areas of the Anacostia and the Potomac rivers in Washington DC, using gas chromatography and a mass spectrometer to identify isolated fatty acids and study the geochemistry of the urban rivers.

Photo of Kristina Nicholas

Kristina Nicholas

Kristina Nicholas is an Environmental Science MS student entering her second year at Â鶹¹û¶³´«Ã½. She received a Bachelor’s in Earth and Environmental Science from UCLA. Her research focuses on analyzing concentrations of polycyclic aromatic hydrocarbons (PAHs) and siloxanes of the Anacostia and Potomac rivers. In addition to her research work, she is a TA for an undergraduate class in the department.ÌýÌý

Olivia Ventresca

Olivia Ventresca

Olivia is responsible for extracting sediments from suburban sites in Maryland and characterizing siloxanes (emerging aquatic contaminants derived from building materials, cosmetics and industrial lubricants. She will also calculate % organic carbon and culture fecal coliform bacteria from the same sites.Ìý