Adsorption of Isoxaflutole Degradates to Aluminum and Iron Hydrous Oxides.
Si Hyun Wu1, Keith Goyne1, Robert Lerch2, Chung-Ho Lin1, and Stephen Anderson1. (1) Univ. of Missouri, Dept. of Soil, Environmental, and Atmospheric Sciences, 302 ABNR Bldg, Columbia, MO 65211-7250, (2) USDA-ARS, Univ. of Missouri, 265 Ag. Eng. Bldg., Columbia, MO 65211-7250
Isoxaflutole, sold under thetrade names BalanceTM, Balance ProTM and EpicTM, is a relatively new herbicide that rapidly hydrolyzes to the degradate diketonitrile (DKN) after field application. Subsequently, DKN may be biologically degraded to form a benzoic acid (BA) derivative and other inactive degradates. There is, however, little consensus in the scientific literature regarding soil solid phase components and aqueous chemical composition most important for DKN and BA sorption and retention. Al and Fe hydrous oxides (HAO and HFO, respectively) in soil may be important sorbents for DKN and BA due to their variable-charge properties, high specific surface areas, and reactive functional groups. To enhance our understanding of DKN and BA interactions in the pedosphere, studies are being conducted to (1) assess the influence of soil mineral chemical composition (HAO and HFO) on DKN and BA sorption and retention, (2) determine the influence of aqueous chemical composition (pH and organic compound concentration) on DKN and BA uptake and sequestration, and (3) elucidate the mechanism(s) of DKN and BA binding to metal hydrous oxide surfaces. Findings from sorption isotherm, sorption edge, and FTIR spectroscopic investigations will be presented and discussed.