Armbrust K L
University of Georgia-Georgia Station, Department of Crop and Soil Science, Griffin 30223-1797, USA.
Environ Toxicol Chem. 2001 Dec;20(12):2699-703. doi: 10.1897/1551-5028(2001)020<2699:pohias>2.0.co;2.
Hydroxychlorothalonil is the principal degradation product of the fungicide chlorothalonil in soil, and it is routinely detected in leachate from golf course greens at concentrations as high as 2 ppm. However, it is not detected in receiving waters of shallow ponds. Irradiation with simulated sunlight degraded hydroxychlorothalonil in distilled-deionized water, phosphate buffer, and pond water with half-lives of approximately 30 min. Slower degradation was observed in solutions of NaCl and NaCN, suggesting photonucleophilic substitution reactions may be responsible for the degradation. Hydroxylated products resulting from the displacement of chlorine and cyano groups were detected within the first hour of irradiation but were subsequently degraded to small aliphatic acids (succinic, oxalic, and malonic acid) within 96 h. Simulations of aquatic dissipation of the chemical using the U.S. Environmental Protection Agency standard pond scenario in the exposure analysis modeling system indicate that the 30-min half-life measured in the laboratory would equate to a half-life of 2.6 d in a 2-m-deep pond and as much as 3.4 d in seawater. Although hydroxychlorothalonil is moderately stable and mobile in soil, these data suggest that, in surface water, it should be rapidly degraded by sunlight to small aliphatic acids on transport into aquatic systems.
羟基百菌清是杀菌剂百菌清在土壤中的主要降解产物，在高尔夫球场果岭渗滤液中常可检测到，浓度高达2 ppm。然而，在浅池塘的接纳水体中未检测到。用模拟阳光照射可使蒸馏去离子水、磷酸盐缓冲液和池塘水中的羟基百菌清降解，半衰期约为30分钟。在氯化钠和氰化钠溶液中观察到降解较慢，这表明光亲核取代反应可能是降解的原因。在照射的第一小时内检测到由氯和氰基取代产生的羟基化产物，但随后在96小时内降解为小的脂肪族酸（琥珀酸、草酸和丙二酸）。在暴露分析建模系统中使用美国环境保护局标准池塘情景对该化学品的水生消散进行模拟表明，实验室测得的30分钟半衰期在2米深的池塘中相当于2.6天的半衰期，在海水中则高达3.4天。尽管羟基百菌清在土壤中具有一定的稳定性和流动性，但这些数据表明，在地表水中，它在进入水生系统时应会被阳光迅速降解为小的脂肪族酸。
