title: Dissipation of the herbicide [14C]dimethenamid under anaerobic conditions in flooded soil microcosms.
abstract: The objective of this research was to investigate the dissipation of the herbicide dimethenamid under anaerobic redox conditions that may develop in the soil environment. Soil-water biometers were prepared with a saturated soil and made anaerobic by either glucose pretreatment (according to the Environmental Protection Agency registration study for anaerobic fate) or N2 sparging. Treatments included glucose pretreatment, NO3- + SO42- amendment, unamended, and autoclaved. Volatile, aqueous, extractable, and bound (unextractable) 14C-residues were quantified and characterized. The redox potential decreased over time, and evidence of denitrifying, iron-reducing, sulfate-reducing, and methanogenic conditions was observed, depending on the amendments. Anaerobic degradation of 14C-dimethenamid occurred in all treatments, and the time observed for 50% disappearance (DT50) was 13-14 days for nonautoclaved treatments. 14C-metabolites accumulated to up to 20% of applied 14C. At least two major metabolites were observed in nonautoclaved treatments, whereas only one was observed in autoclaved microcosms. More than 50% of the applied 14C was eventually incorporated into soil-bound residue.
authors.affiliation: Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, Illinois 61801, USA. jcrawfor@uiuc.edu
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Crawford
authors.forename: Gerald K
authors.initials: GK
authors.lastname: Sims
authors.forename: F William
authors.initials: FW
authors.lastname: Simmons
authors.forename: Loyd M
authors.initials: LM
authors.lastname: Wax
authors.forename: David L
authors.initials: DL
authors.lastname: Freedman
mesh_terms: D000083:Acetanilides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D000693:Anaerobiosis; D002250:Carbon Radioisotopes; D004190:Disasters; D005947:Glucose / Q000494:pharmacology; D006540:Herbicides / Q000032:analysis*; D009566:Nitrates / Q000494:pharmacology; D010084:Oxidation-Reduction; D011891:Rain; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D013431:Sulfates / Q000494:pharmacology
chemical_list: D000083:Acetanilides; D002250:Carbon Radioisotopes; D006540:Herbicides; D009566:Nitrates; D012987:Soil; D013431:Sulfates; C120861:dimethenamid; D005947:Glucose