Environmental Biogeochemistry

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The Environmental Biogeochemistry Section in the Patrick Center is concerned with the influence of organisms on the sources, fate, and transport of chemicals in the aquatic systems. Within the Environmental Biogeochemistry Section many studies deal with the cycling of bioactive elements (carbon, nitrogen, and phosphorus) as well as trace elements (e.g., lead, copper, mercury, and zinc) and organic contaminants such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs).

Recent and ongoing studies include the study of nutrient cycling within tidal freshwater wetlands in the Delaware and Anacostia rivers, impact of sea-level rise on C and P cycling in tidal freshwater wetlands, contaminant uptake and food-web dynamics in the Anacostia River, nutrient cycling in tidal wetlands, ponds and riparian zones of free flowing rivers, the effects of stormwater runoff to the water quality of the Anacostia and Potomac rivers, and historical changes in nutrients and contaminants and their impact to the ecology of an estuary.

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  • Nutrient cycling in tidal wetlands, rivers and estuaries
  • Whole stream metabolism and related metrics of ecosystem function in stream and river systems
  • Stable isotope biogeochemistry of organic carbon, nitrogen, sulfur, oxygen, and hydrogen
  • Stable isotope biogeochemistry of inorganic carbon and oxygen
  • Fate and transport of trace elements in aquatic systems
  • Reactive and conservative solute transport in stream systems
  • Food chain transfers of organic compounds
  • Mass balance modeling of trace elements and bioactive elements
  • Non-point sources of anthropogenic chemicals in aquatic systems


The Environmental Biogeochemistry Section has a broad range of laboratory and field equipment to conduct a full range of basic and applied studies. Instrumentation includes:

  • ThermoFinnigan Delta Plus Stable Isotope Ratio Mass Spectrometer coupled with a Conflo111 and Carlo Erba NA 2500 Elemental Analyzer for bulk organic carbon and nitrogen stable isotope analysis
  • Elementar Americas Isoprime100 coupled with a Vario Cube for bulk organic carbon, nitrogen, sulfur, oxygen, and hydrogen stable isotope analysis and a Multiflow for inorganic carbon and oxygen stable isotope analysis
  • Flash 1120 Elemental Analyzer for carbon, nitrogen, and sulfur quantitative analysis
  • O I Analytical Aurora 1030 Wet Oxidation TOC Analyzer
  • SmartChem 200 (Discrete Analyzer) and Alpkem (Autoanalyzer) for nutrients, with low detection limits.
  • ICS-300 Dionex ion chromatography set up for anion analysis
  • cold vapor Hg analyzer
  • GC-Electron Capture Detector for chlorinated hydrocarbons
  • UV-Vis spectrophotometer
  • Fluorometers
  • Microwave digester
  • numerous in-situ water quality meters for pH, dissolved oxygen, salinity/conductivity, and turbidity

Field sampling equipment is generally tailored for the specific project and includes an all plastic Soutar box-corer, Ekman and Ponar sediment grab sampler, Niskin and Van Dorn water bottles, and water pumping systems for trace metal clean methods. SonTek FlowTracker and River Surveyor for discharge measurements. 

Selected Projects

Delaware River Watershed Initiative
More than 50 leading nonprofits have joined together, aligning priorities for land protection and restoration projects and assessing water quality impacts using standardized methods. Partners are focusing on reducing agricultural runoff and urban stormwater in areas of lesser water quality, and they are protecting headwaters, forests, and groundwater reserves where water quality is high. Coordination among the many partners will allow the first-ever collection, synthesis, and analysis of data from sites across the basin, generating critical information on what works in river protection and restoration.
Sabine River Monitoring
The Sabine River Basin is approximately 300 miles long and extends from northeastern Texas to Sabine Lake and on to the Gulf of Mexico. The Sabine River and watershed provide a wide variety of recreational opportunities, such as fishing, boating, hiking and hunting to many residents and visitors each year. Since 1982, Eastman Chemical Company, Texas Operations (TXO) has sponsored a series of biological and water quality surveys on the Sabine River near Longview, TX, by the Patrick Center for Environmental Research of the Academy of Natural Sciences of Drexel University. The present study was conducted in October of 2015; previous studies were completed in 1982, 1987, 1995, 2000, 2005 and 2010.
Impact of Sea Level Rise on the Cycling of Carbon and Phosphorus in Tidal Freshwater Marshes
Funded by US EPA Star Program. PIs, Dr. Melanie Vile (Villanova Univ.), David Velinsky, and Scott Neubaur (Univ. South Carolina). US EPA STAR
Distribution of Sediment Contaminant History in the tidal freshwater Potomac River
Washington, DC. Funded by: District of Columbia, PI: D. Velinsky, G. Riedel (SERC) and J.Ashley; District of Columbia.
Historical Changes in Sedimentation and Chemical Loading in Tidal Marshes of the Delaware Estuary
Funded by Delaware River Basin Commission. PIs: Chris Sommerfield (UDEL) and D. Velinsky.