Environmental Biogeochemistry


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.

Staff | Capabilities | Facilities | Selected Projects


Dr. Marie Kurz, Section Leader Biogeochemistry Department and Assistant Research Professor Biodiversity, Earth and Environmental Science, Drexel University
Dr. Kurz an eco-geochemist, is an aqueous geochemist by training with an interest in the interactions between ecology, geochemistry and hydrology in freshwater systems. Her research investigates the geochemical, ecological and hydrologic processes controlling the availability, transport and cycling of solutes in streams, and the reciprocal interactions between these solute dynamics and stream ecosystem functions, such as nutrient uptake and metabolism. Marie started off working in Florida's spring-fed rivers, transitioned to Germany forested streams, and now has moved on to Pennsylvania and the Delaware River watershed. She received a BS from The College of William & Mary in 2007 and a PhD from the University of Florida in 2013.
Dr. David Velinsky, Director and Department Head, Biodiversity, Earth and Environmental Science, Drexel University
Dr. Velinsky is a marine biogeochemist with over 20 years experience in marine and freshwater studies related to nutrient cycling, isotope biogeochemistry, and wetland nutrient and metal geochemistry. He started as an organic geochemist studying the transport of organic compounds in estuaries and from atmospheric transport, and shifted to studies of sulfur and selenium geochemistry. He has published studies related to many aspects of biogeochemistry and has a broad range in the cycling of bioactive elements.
Dr. Bhanu Paudel, Ruth Patrick Post Doctorial Scholar, Patrick Center for Environmental Research, Academy of Natural Sciences
Dr. Paudel is interested in hydrological processes, sediment-water interactions, and trace element cycling in lotic and lentic ecosystems. His current interests include understanding the impact of climate variability on aquatic resources. Bhanu has studied nutrient biogeochemistry at sediment-water interface in Texas and New Jersey estuaries. He also uses statistical modeling technique to understand the roles of environmental parameters in lotic and lentic ecosystem. He received his B.S and M.S in Environmental Science from Tribhuvan University and earned his Ph.D. in Coastal and Marine System Science from Texas A&M University-Corpus Christ.
Mr. Paul Kiry (M.A.; Drexel University)
is our lead Senior Scientist, with over 40 years of experience in all forms of environmental analysis of nutrients and trace metals. Paul, known as the chemistry guru, produces the lowest detection limits and is the point person for any chemistry related question.
Paula Zelanko (M.S. Earth and Environmental Science; Lehigh University)
runs the Elemental and Stable Isotope Mass Spectrometry Facilities. Her research interests include trophic and migratory aspects of bird ecology, subfossil food webs, and biogenic carbonates.
Melissa Bross (M.S. Environmental Science; Drexel University)
manages the chemistry and field coordination aspects of the DRWI project. With background in environmental science and geology, she performs nutrient analyses and maintains field electronics.
Tracey Curran (M.S. Environmental Science; Drexel University),
with degrees in molecular and cell biology and environmental science, provides unmatched laboratory and field experience. Other departments routinely vie for her assistance in the field.
Support Staff
Bill Frezel, M.S, Electrical Engineering
Megan Nyquist, B.S. in Anthropology from Beloit College
Alana Thurston, B.S. in Chemistry from Haverford
Michelle Gannon, Ph.D. candidate in BEES Department
Richard Searfoss, M.S. candidate in BEES Department
Previous Staff
Employees: Linda Zaoudeh, Mike Schafer
Co-op Students: Farzana Rahman, Richard Searfoss
Interns: Laura Korman, Kevin Carpenter, Greg Sidorov, Ally Tarbous, Adnan Kazim 

Tracey Curran taking water quality measurements from Ridge Valley Creek, Pennsylvania.


  • 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 Past and Ongoing Projects

  • Delaware River Watershed Initiative.  Funded by: William Penn Foundation. Webpage
  • Sabine River Monitoring.  Funded by: Eastman Chemical Company Webpage
  • Bioaccumulation of Organic Contaminants in the Delaware River Estuary: Role of Tidal Freshwater Marshes. PIs: D.Velinsky and J. Ashley (Philadelphia University); NOAA Sea Grant.
  • 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. PI: Chris Sommerfield (UDEL) and D. Velinsky. Webpage.

Tinicum Marsh