|Lerch, Robert - Bob|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/3/2003
Publication Date: 11/3/2003
Citation: LIN, C.H., LERCH, R.N., GARRETT, H.E., GEORGE, M.F. 2003. IMMOBILIZATION AND DETOXIFICATION OF ATRAZINE AND BALANCE (ISOXAFLUTOLE) BY SELECTED FORAGE SPECIES [abstract] [CD-ROM]. ASA-CSSA-SSA ANNUAL MEETING ABSTRACTS. Interpretive Summary:
Technical Abstract: Six different forage treatments (bare ground, orchardgrass, tall fescue, timothy, smooth bromegrass, and switchgrass) were established on 1 m wide X 0.5 m deep lysimeters to evaluate their bioremediation capacity for atrazine (ATR) and Balance (isoxaflutole). Herbicides were uniformly applied to each lysimeter by irrigating with 3 L solutions containing either ATR (500 ug/L) or isoxaflutole (IXF) (80 ug/L). Soil and above ground plant tissue were collected 25 days following herbicide application and analyzed for parent and metabolite compounds. The results suggested that forage treatments, especially those with switchgrass, significantly enhanced the degradation of ATR in the soil by N-dealkylation and/or hydroxylation. Approximately 80.7% of atrazine in the soil was degraded into less toxic forms by switchgrass. Smooth bromegrass, timothy, orchardgrass, and tall fescue also showed promising atrazine degradation capacity (66.5 to 74.7% converted to metabolites) compared to the control. In contrast, the degradation of diketonitrile (DKN), the first degradation product and biologically active form of Balance, in soil was not affected by any of the forage treatments. The results also indicated that the total uptake of Balance residue strongly correlated with the transpiration rates of the selected forages species. The capacity of forages to convert DKN to a nonphytotoxic benzoic acid metabolite was strongly associated with their tolerance to this new herbicide. In a bioremediation system utilizing the forages tested here, the enhanced biological degradation by the forage will play an essential role in the removal of ATR. On the other hand, the abiotic nature of DKN degradation in the soil implies that physical trapping is likely to be the primary remediation mechanism for Balance removal.