Ismail B S, Eng O K, Tayeb M A
School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.
PLoS One. 2015 Oct 5;10(10):e0138170. doi: 10.1371/journal.pone.0138170. eCollection 2015.
Triazine-2-(14)C metsulfuron-methyl is a selective, systemic sulfonylurea herbicide. Degradation studies in soils are essential for the evaluation of the persistence of pesticides and their breakdown products. The purpose of the present study was to investigate the degradation of triazine-2-(14)C metsulfuron-methyl in soil under laboratory conditions. A High Performance Liquid Chromatograph (HPLC) equipped with an UV detector and an on-line radio-chemical detector, plus a Supelco Discovery column (250 x 4.6 mm, 5 μm), and PRP-1 column (305 x 7.0 mm, 10 μm) was used for the HPLC analysis. The radioactivity was determined by a Liquid Scintillation Counter (LSC) in scintillation fluid. The soil used was both sterilized and non-sterilized in order to observe the involvement of soil microbes. The estimated DT50 and DT90 values of metsulfuron-methyl in a non-sterile system were observed to be 13 and 44 days, whereas in sterilized soil, the DT50 and DT90 were 31 and 70 days, respectively. The principal degradation product after 60 days was CO2. The higher cumulative amount of (14)CO2 in (14)C-triazine in the non-sterilized soil compared to that in the sterile system suggests that biological degradation by soil micro-organisms significantly contributes to the dissipation of the compound. The major routes of degradation were O-demethylation, sulfonylurea bridge cleavage and the triazine "ring-opened."
三嗪 - 2 -（14）C 甲磺隆是一种选择性内吸性磺酰脲类除草剂。土壤中的降解研究对于评估农药及其分解产物的持久性至关重要。本研究的目的是在实验室条件下研究三嗪 - 2 -（14）C 甲磺隆在土壤中的降解情况。配备紫外检测器和在线放射化学检测器的高效液相色谱仪（HPLC），加上 Supelco Discovery 柱（250×4.6 mm，5μm）和 PRP - 1 柱（305×7.0 mm，10μm）用于 HPLC 分析。放射性通过液体闪烁计数器（LSC）在闪烁液中进行测定。为了观察土壤微生物的作用，所使用的土壤既有经过灭菌的，也有未灭菌的。在非无菌系统中，甲磺隆的估计 DT50 和 DT90 值分别为 13 天和 44 天，而在灭菌土壤中，DT50 和 DT90 分别为 31 天和 70 天。60 天后的主要降解产物是二氧化碳。与无菌系统相比，非灭菌土壤中（14）C - 三嗪中（14）CO2 的累积量更高，这表明土壤微生物的生物降解对该化合物的消散有显著贡献。主要降解途径是 O - 去甲基化、磺酰脲桥断裂和三嗪“开环”。
