AI Article Synopsis
- * The study found that in the presence of oxygen, the herbicide mostly degrades through a direct reaction involving a singlet-excited state, while under low oxygen levels, a triplet-excited state speeds up the breakdown.
- * Different concentrations of dissolved organic matter (DOM) affect degradation rates, with fulvic acid leading to faster breakdown compared to solutions with both humic and fulvic acids, indicating a complex interaction between degradation enhancement and competition for light.
Article Abstract
Imazosulfuron, a sulfonylurea herbicide used in rice cultivation, has been shown to undergo photodegradation in water, but neither the photochemical mechanism nor the role of indirect photolysis is known. The purpose of this study was to investigate the underlying processes that operate on imazosulfuron during aqueous photodegradation. Our data indicate that in the presence of oxygen, most photochemical degradation proceeds through a direct singlet-excited state pathway, whereas triplet-excited state imazosulfuron enhanced decay rates under low dissolved oxygen conditions. Oxidation by hydroxyl radical and singlet oxygen were not significant. At dissolved organic matter (DOM) concentrations representative of rice field conditions, fulvic acid solutions exhibited faster degradation than rice field water containing both humic and fulvic acid fractions. Both enhancement, via reaction with triplet-state DOM, and inhibition, via competition for photons, of degradation was observed in DOM solutions.
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| http://dx.doi.org/10.1021/acs.jafc.7b00134 | DOI Listing |
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