斯里兰卡土壤和沉积物中草甘膦及降解产物的分析及污染特征

Analysis and Occurrences of Glyphosate and Its Degradation Product in Soil and Sediment Samples from Sri Lanka

不明原因慢性肾病(CKDu)是斯里兰卡北部稻农高发的肾脏疾病,其中,除草剂草甘膦的接触暴露被认为是重要诱因之一。制备了草甘膦-钙络合物,分析了不同pH下络合物的性质和形态,发现酸性条件能够有效消除草甘膦-钙络合物对于草甘膦的提取和化学衍生的影响,在此基础上优化并建立了草甘膦及其降解产物在斯里兰卡土壤中的萃取和衍生前处理-GC-MS分析方法。利用该方法对斯里兰卡土壤及沉积物中草甘膦及其降解产物进行了测定。土壤中草甘膦及其降解产物的浓度分别为26~340μg·kg^-1和0~427μg·kg^-1,沉积物中2种物质的浓度分别为45~152μg·kg^-1和ND。北部CKDu高发区的稻田未处于耕种季,但其土壤中草甘膦浓度却高于南部耕种季的土壤,这可能是因为北部井水的硬度高,草甘膦与水中钙离子的络合导致其部分失效,从而使北部稻田草甘膦的施用量增加,增大了当地农民的草甘膦暴露,这是当地稻农CKDu疾病高发的潜在环境因素之一。

Chronic kidney disease of unknown etiology(CKDu)is a kidney disease with high incidence in rice farmers in northern Sri Lanka.Exposure to the herbicide glyphosate is considered to be one of the important factors associated with the disease.In this study,we prepared the glyphosate-calcium complex,and assessed its properties in solutions with different pH.It is found that acidic conditions can effectively remove the complex,which could interfere the analysis of glyphosate during the extraction and chemical derivatization processes.Based on the results,an analytical method was established for glyphosate and its degradation product by derivatization-GC-MS and applied to soil and sediment samples from Sri Lanka.Concentrations of glyphosate and its degradation product in the soil were in the range of 26~340μg·kg^-1 and 0~427μg·kg^-1 respectively,and concentrations of the two substances in sediments were 45~152μg·kg^-1 and ND respectively.In the northern area with high CKDu incidence,the paddy fields are not in the cultivation period when sampling,but the levels of glyphosate in the soil samples in this area are still higher than those in samples from south area.This is possibly due to the high hardness of the well water in the northern area.The complexation of glyphosate with calcium ions in the water increased the amounts of glyphosate used and the exposure risk of local farmers to glyphosate,which is one of the potential environmental factors for the high incidence of CKDu in local rice farmers.