|Lerch, Robert - Bob|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/11/2006
Publication Date: 11/11/2006
Citation: Wu, S.H., Goyne, K.W., Lerch, R.N., Lin, C.H., Anderson, S.H. 2006. Adsorption of isoxaflutole degradates to aluminum and iron hydrous oxides [abstract]. In: ASA-CSSA-SSSA Annual Meeting Abstracts. ASA-CSA-SSSA Annual Meeting, November 12-16, 2006, Indianapolis, Indiana. p.87-3. Interpretive Summary:
Technical Abstract: Isoxaflutole (IXF) is sold under the trade names Balance(TM), Balance Pro(TM), and Epic(TM). IXF rapidly hydrolyzes to the degradate diketonitrile (DKN), the active herbicide principle, after field application. Subsequently, DKN may be biologically degraded to a benzoic acid (BA) derivative and other inactive herbicide degradates. DKN is phytotoxic to non-target organisms. IXF, DKN, and BA are classified as probably carcinogens by the USEPA. There is little consensus regarding soil physical and chemical properties most important for DKN and BA sorption and retention. It has been hypothesized that DKN may form strong chelate complexes between the anionic enol form of DKN and cations within clay interlayers, structural cations, and cations adsorbed to organic matter. However, DKN does not adsorb to pure 2:1 layer silicates, suggesting that variable-charge minerals (e.g., hydrous aluminum and iron oxides) may be involved in DKN and BA retention. Thus, the objectives of this research were to: 1) quantify DKN and BA adsorption and retention by hydrous aluminum and iron oxides (HAO and HFO, respectively); 2) assess changes in DKN and BA adsorption as a function of aqueous chemical composition (i.e., pH and initial degradate concentration); and 3) establish the mechanism(s) through which DKN and BA bind to HAO and HFO surfaces.