Abstract：
The presence of undesired agrochemicals residues in soil and water poses risks to both human health and the environment. The behavior of pesticides in soil depends both on the physico-chemical properties of pesticides and soil type. This study examined the adsorption-desorption and leaching behavior of the maize herbicide tembotrione in soils of the upper (UGPZ), trans (TGPZ) and middle Gangetic plain zones of India. Soil samples were extracted using acetone followed by partitioning with dichloromethane, whereas liquid-liquid extraction using dichloromethane was used for aqueous samples. Residues of tembotrione and its metabolite TCMBA, {2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy) methyl] benzoic acid}, were quantified using liquid chromatography-tandem mass spectrometry. The data revealed that tembotrione adsorption decreased with increasing pH and dissolved organic matter but increased with salinity. The maximum adsorption occurred at pH 4, 0.01 m sodium citrate and 4 g/L NaCl, with corresponding Freundlich constants of 1.83, 2.28 and 3.32, respectively. The hysteresis index <1 indicated faster adsorption than desorption. Leaching studies under different flow conditions revealed least mobility in UGPZ soil and high mobility in TGPZ soil, consistent with groundwater ubiquity scores of 4.27 and 4.81, respectively. Soil amendments decreased tembotrione mobility in the order: unamended > wheat straw ash > wheat straw > farm yard manure > compost. The transformation of tembotrione to TCMBA and its mobility in soil columns were also assessed.
摘要：
土壤和水中不需要的农用化学品残留物的存在对人类健康和环境都构成了风险。农药在土壤中的行为取决于农药的理化性质和土壤类型。这项研究检查了玉米除草剂tembotrione在上层（UGPZ）土壤中的吸附-解吸和浸出行为，跨（TGPZ）和印度中部恒河平原地区。使用丙酮提取土壤样品，然后用二氯甲烷分配，而使用二氯甲烷的液-液萃取用于水性样品。tembotrione及其代谢产物TCMBA的残留，{2-氯-4-(甲基磺酰基)-3-[(2,2,2-三氟乙氧基)甲基]苯甲酸},使用液相色谱-串联质谱法进行定量。数据显示，tembotrione吸附随pH和溶解有机物的增加而降低，但随盐度的增加而增加。最大吸附发生在pH4，0.01m柠檬酸钠和4g/LNaCl，相应的Freundlich常数分别为1.83、2.28和3.32。滞后指数<1表明吸附比解吸更快。在不同流动条件下的浸出研究表明，UGPZ土壤中的迁移率最小，而TGPZ土壤中的迁移率高。与地下水普遍性得分分别为4.27和4.81一致。土壤改良剂按以下顺序降低了tembotrione的迁移率：未改>小麦秸秆灰>小麦秸秆>农场肥料>堆肥。还评估了tembotrione向TCMBA的转化及其在土壤柱中的迁移率。
