Environ Monit Assess. 2014 Feb;186(2):1083-99. doi: 10.1007/s10661-013-3440-8.
The increasing application of pesticides in the uplands of northern Thailand has increased the transfer of pesticides to surface water. To assess the risk of pesticide use for stream water quality, we monitored the concentrations of seven pesticides (atrazine, dichlorvos, chlorpyrifos, dimethoate, chlorothalonil, (α-, β-) endosulfan, cypermethrin) frequently used in the Mae Sa watershed (77 km(2)) in water and sediment samples over a period of one and a half years (2007-2008). All investigated pesticides were recorded in the river. Chlorpyrifos was detected most often in water samples (75% at the headwater station), while cypermethrin was most often found in riverbed (86%) and in all suspended sediment samples. The highest concentrations of the pesticides were detected during the rainy season. About 0.002 to 4.1% by mass of the applied pesticides was lost to surface water. The risk assessment was based on the risk characterization ratio (RCR). The RCRs of dichlorvos in water, (α-, β-) endosulfan, and cypermethrin in water and sediments were higher than unity indicating that they are likely to pose a threat to aquatic ecosystem. Finally, we discuss the role of sampling design on ecotoxicological risk assessment. Our study shows that pesticide contamination of surface waters is an environmental issue in the Mae Sa watershed and that measures need to be undertaken to reduce the loss of pesticides from soil to surface waters.
泰国北部高地不断增加的农药使用量增加了农药向地表水的转移。为了评估农药使用对溪流水质的风险，我们在一年半的时间内（2007-2008 年）监测了 Mae Sa 流域（77 平方公里）水中和沉积物样本中七种经常使用的农药（莠去津、敌敌畏、毒死蜱、乐果、百菌清、（α-，β-）硫丹、氯氰菊酯）的浓度。在所研究的河流中均记录到了所有被调查的农药。在水样中最常检测到氯蜱硫（75%在源头站），而在河床（86%）和所有悬浮沉积物样本中最常发现氯氰菊酯。农药浓度最高出现在雨季。大约有 0.002 到 4.1%的施用量的农药流失到地表水。风险评估是基于风险特征比值（RCR）。水样中的敌敌畏、（α-，β-）硫丹和水及沉积物中的氯氰菊酯的 RCR 高于 1，表明它们可能对水生生态系统构成威胁。最后，我们讨论了采样设计在生态毒理学风险评估中的作用。我们的研究表明，农药对地表水的污染是 Mae Sa 流域的一个环境问题，需要采取措施减少农药从土壤向地表水的流失。
