title: Pesticide photolysis in prairie potholes: probing photosensitized processes.
abstract: Prairie pothole lakes (PPLs) are glacially derived, ecologically important water bodies found in central North America and represent a unique setting in which extensive agriculture occurs within wetland ecosystems. In the Prairie Pothole Region (PPR), elevated pesticide use and increasing hydrologic connectivity have raised concerns about the impact of nonpoint source agricultural pollution on the water quality of PPLs and downstream aquatic systems. Despite containing high dissolved organic matter (DOM) levels, the photoreactivity of the PPL water and the photochemical fate of pesticides entering PPLs are largely unknown. In this study, the photodegradation of sixteen pesticides was investigated in PPL waters sampled from North Dakota, under simulated and natural sunlight. Enhanced pesticide removal rates in the irradiated PPL water relative to the control buffer pointed to the importance of indirect photolysis pathways involving photochemically produced reactive intermediates (PPRIs). The steady-state concentrations of carbonate radical, hydroxyl radical, singlet oxygen, and triplet-excited state DOM were measured and second-order rate constants for reactions of pesticides with these PPRIs were calculated. Results from this study underscore the role of DOM as photosensitizer in limiting the persistence of pesticides in prairie wetlands through photochemical reactions.
authors.affiliation: Department of Civil Engineering, University of Minnesota, 500 Pillsbury Drive Southeast, Minneapolis, Minnesota 55455, United States.
authors.forename: Teng
authors.initials: T
authors.lastname: Zeng
authors.forename: William A
authors.initials: WA
authors.lastname: Arnold
mesh_terms: D002254:Carbonates / Q000032:analysis; D017665:Hydroxyl Radical / Q000032:analysis; D060106:Lakes; D010575:Pesticides / Q000737:chemistry / Q000528:radiation effects*; D010782:Photolysis; D026082:Singlet Oxygen / Q000032:analysis; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects*
chemical_list: D002254:Carbonates; D010575:Pesticides; D014874:Water Pollutants, Chemical; D026082:Singlet Oxygen; D017665:Hydroxyl Radical