Abstract
The prevalent use of chloroacetanilide herbicides has resulted in nonpoint contamination of some groundwater and surface water. We determined the efficacy of dithionite-treated sediment and soils to transform chloroacetanilides. When used alone, dithionite rapidly dechlorinates chloroacetanilides in water, with the following order of reactivity: propachlor > alachlor > acetochlor > metolachlor. Stoichiometric release of chloride occurs during reaction with dithionite. and thiosulfate herbicide derivatives are produced. Treating aquifer sediment with dithionite reduces native Fe(III), creating a redox barrier of Fe(II)-bearing minerals and surface-bound Fe(II). Washing the reduced sediment (buffered with citrate-bicarbonate) with oxygen-free water removed Fe(II) and excess dithionite and no alachlor transformation was observed. In contrast, a dithionite-treated surface soil, rich in clay and iron, effectively dechlorinated alachlor after washing. Exposing alachlor to aquifer sediment treated with dithionite in potassium carbonate buffer (pH 8.5-9.0) produced dechlorinated alachlor as the major degradation product. Our results provide proof-of-concept that dechlorination of chloroacetanilide herbicides by dithionite and dithionite-treated aquifer sediment and soil is a remediation option in natural environments where iron-bearing minerals are abundant.
Original language | English (US) |
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Pages (from-to) | 3043-3049 |
Number of pages | 7 |
Journal | Environmental Science and Technology |
Volume | 40 |
Issue number | 9 |
DOIs | |
State | Published - May 1 2006 |
ASJC Scopus subject areas
- Chemistry(all)
- Environmental Chemistry