Nutrient Cycling in Shallow Coastal Aquatic Ecosystems: Role of Photochemistry

EPA Grant Number: U915407
Title: Nutrient Cycling in Shallow Coastal Aquatic Ecosystems: Role of Photochemistry
Investigators: Buffam, Ishi D.
Institution: University of Virginia
EPA Project Officer: Michaud, Jayne
Project Period: January 1, 1998 through January 1, 2001
Project Amount: $56,068
RFA: STAR Graduate Fellowships (1998) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems


The objectives of this research project are to: (1) place photodegradation of dissolved organic matter (DOM) into a whole-system model of nutrient (C and N) cycling; (2) compare the relative importance of fluxes from photochemistry with other ecosystem processes in shallow coastal waters along the eastern shore of Virginia; and (3) evaluate the relative importance of various sources of labile N (including the photodegradation of DOM) in the development of coastal ecosystems at several sites on the Atlantic Coast of North America, while comparing anthropogenic sources to "natural" sources.


The following approach will be taken, with sites in several estuaries and lagoons along the eastern shore of Virginia at the Virginia Coast Reserve/Long-Term Ecological Research site and possibly extending to other sites along the Atlantic Coast of North America: (1) using sterile in situ assays, determine the magnitudes and rates of photochemical consumption of oxygen and DOM, with concomitant production of inorganic carbon (CO and CO2), inorganic nitrogen [ammonium], and smaller organic matter byproducts; (2) using laboratory/in situ bioassays, determine the importance of photochemical oxidation byproducts, including inorganic N and altered DOM (which may still contain labile DON), to bacterial secondary production, and phytoplankton and macroalgal primary production; (3) place photochemical oxidation processes in the context of the rest of the system by comparing them with rates of metabolism (photosynthesis and respiration), mineralization, and breakdown of organic matter occurring by other mechanisms; (4) construct a conceptual model of C and N cycling in shallow coastal waters; and (5) use this model to identify the critical sources of labile nutrients to these systems.

Supplemental Keywords:

fellowship, dissolved organic nitrogen, DON, urea, ammonium, nitrate, amino acids, photochemistry, photodegradation, UV-A, UV-B, nutrient, nutrient cycling, aquatic ecosystems, photochemistry, dissolved organic matter, DOM., RFA, Scientific Discipline, Geographic Area, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, State, Aquatic Ecosystem, Aquatic Ecosystems, Biochemistry, Ecology and Ecosystems, coastal ecosystem, dissolved organic matter, nutrient dynamics, estuaries, Virginia (VA), UV, ecosystem monitoring, coastal environments

Progress and Final Reports:

  • 1998
  • 1999
  • Final