Grantee Research Project Results
The Influence of Surface Water Constituents on the Photochemical Transformation of Nonpoint Source PollutantsEPA Grant Number: U915177
Title: The Influence of Surface Water Constituents on the Photochemical Transformation of Nonpoint Source Pollutants
Investigators: Miller, Penney L.
Institution: Ohio State University - Main Campus
EPA Project Officer: Jones, Brandon
Project Period: January 1, 1997 through January 1, 2000
Project Amount: $68,000
RFA: STAR Graduate Fellowships (1997)
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Chemistry and Materials Science
The overall objective of this research project is to ascertain the potential for the transformation of nonpoint source (NPS) pollutants by photochemical processes in shallow surface waters. The specific objectives of this research project are to: (1) evaluate the direct photolytic contribution of pollutant transformation in water samples from wetlands and a eutrophic lake; and (2) characterize photochemical properties of water constituents, and determine how these properties may influence indirect photochemical degradation.Approach:
Two wetland sites in Ohio were selected for study: Old Woman Creek Estuarine Reserve (OWC) and Olentangy River Wetland Research Park (ORWRP). A third site, Pony Lake (PL), Ross Island, a shallow Antarctic lake also was chosen. NPS contamination occurs in the wetland sites from runoff and from atmospheric transport at the latter site. Identification (e.g., UV/VIS, fluorescence, gas chromatography/mass spectrometry [GC/MS], inductively coupled plasma/mass spectrometry, high performance liquid chromatography [HPLC], total organic carbon) and isolation (e.g., ultrafiltration) of photoreactive constituents (e.g., natural organic matter [NOM]) will be attempted. Target compounds were chosen on the basis of their ubiquity in Ohio (carbaryl and alachlor) or detection in Antarctic water/soil (chlorinated aromatics). Target compounds will be irradiated in either the raw water or reconstituted isolates (NOM obtained from the OWC, ORWRP, PL, or an IHSS standard) using either a mercury or xenon arc lamp in a "merry-go-round" reactor or sunlight. Light intensity will be measured with chemical actinometers. Samples will be withdrawn periodically from reactions, and pollutant concentration will be monitored via HPLC, gas chromatography with dual electron capture detection, or GC/MS. The relative and overall degradation rate constants will be determined through kinetic analysis. The contribution to reactions from different indirect processes will be probed using transient specific quenchers. Anoxic experiments will determine the role of dissolved oxygen as a transient precursor. Reaction pathways will be elucidated from identification and quantification (GC/MS) of daughter products. Finally, in situ (OWC) photochemical reactions are planned to assess the potential for these reactions to occur within a wetland under natural conditions.Supplemental Keywords:
fellowship, nonpoint source pollutants, photodegradation, natural organic matter, NOM, nitrate.