期刊
WATER RESEARCH
卷 41, 期 8, 页码 1781-1789出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2007.01.009
关键词
sulcotrione; photolysis; natural waters; photoproducts; toxicity; marine micro-organisms
Photochemical behaviour of sulcotrione, a triketone herbicide, was studied in a variety of aqueous solutions including natural waters (sea and river) under laboratory conditions. Photodegradation experiments were carried out under two irradiation systems (UV-B and simulated solar radiation) in order to evaluate kinetics of active ingredient. The degradation kinetics, more rapid under UV-B radiation than solar simulator, followed a first-order reaction (photolysis half-lives ranged between 3 and 50h) and appeared strongly dependent on water origin, pH value and molecular structure of the herbicide. Dissolved organic matter showed a retarding effect while low concentrations of nitrate ions had no effect on photolysis rate. Identification of photoproducts indicated that hydrolysis, a pH-dependent process (no degradation at pH > 6 but at pH = 3, k = 0.0344 h(-1)), could be photoassisted. These results were compared to those of mesotrione, another triketone herbicide, which appeared more stable under UV-B irradiation. Toxicological studies on two marine heterotrophic bacteria and one cyanobacterium showed absence of effects up to 100 mu g L-1 for both sulcotrione and its photoproducts. (c) 2007 Elsevier Ltd. All rights reserved.
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