LC-MS/MS法研究甲磺隆和氯磺隆在不同条件土壤中的残留行为

在建立液相色谱三重串联四极杆质谱（LC-MS/MS）检测技术的基础上,采用PVC材料的圆柱形盆钵栽培方法,研究了不同土壤环境条件下甲磺隆和氯磺隆的残留特性。结果表明,甲磺隆和氯磺隆在水稻根际和非根际土壤中的残留量均呈不断下降趋势。处理后15d,根际和非根际土壤中两种农药残留量分别下降了44.7%和41.5%（甲磺隆）及38.7%和40.1%（氯磺隆）,根际和非根际的残留差异不显著（P〉0.05）;处理后31d,残留量分别下降了77.7%和64.8%（甲磺隆）及62.7%和50.1%（氯磺隆）,差异达极显著水平（P〈0.01）;处理后63d,残留量分别下降了96.4%和85.1%（甲磺隆）及90.0%和79.4%（氯磺隆）,残留差异达极显著水平（P〈0.01）。甲磺隆的降解趋势和氯磺隆基本一致,但下降幅度比氯磺隆大。二者在水稻根际和非根际土壤中的残留量均符合一级动力学方程式C=C0e-λ（tC代表浓度;C0代表初始浓度;t时间）,决定系数范围在0.9342～0.9957之间。在种植水稻的条件下,下层土的农药残留量呈先上升后下降的趋势,处理后数日内达最高点,之后不断下降,122d后低于检测限。水稻下层土残留的从无到有说明农药在土壤中的淋溶可能是水田环境农药残留降解的原因之一。干旱土壤条件下,土壤的淋溶作用不明显。说明水旱轮作有利于农药残留在土壤环境中的降解。

Residue Behaviors of Metsulfuron-methyl and Chlorsulfuron Under Different Soil Environment by LC-MS/MS

Based on the liquid chromatography-tandem triple quadrupole mass spectrometric（LC-MS/MS）method developed for the determination of metsulfuron-methyl and chlorsulfuron,the residue behaviors of both herbicides under different soil environment were then studied.The results indicated that residues of metsulfuron-methyl and chlorsulfuron in rhizosphere and non-rhizosphere paddy soil decreased with time prolonged.Residues of two herbicides in rhizosphere and non-rhizosphere soil decreased by 44.7%,41.5%（metsulfuron-methyl） and 38.7%,40.1%（chlorsulfuron）respectively in the 15th day of treatment,decreased by 77.7%,64.8%（metsulfuron-methyl）and 62.7%,50.1%（chlorsulfuron）respectively in the 31st day of treatment,and 96.4%,85.1%（metsulfuron-methyl）and 90.0%,79.4%（chlorsulfuron） respectively in the 63rd day of treatment.Degradation behavior of chlorsulfuron was similar to metsulfuron-methyl,but the rate of degradation was lower.The residues of two herbicides in both rhizosphere and non-rhizosphere soil were non-significantly different（P0.05）in the 15th day of treatment,but significantly different（P0.01）in the 31st and the 63rd day of treatment.The residue behavior of two herbicides in both rhizosphere and non-rhizosphere paddy soil were fitted to first-order kinetic equation（C=C0e-λt,C：concentration,C0：the initial concentration,t：time after treatment）,and the coefficient of determination（R2）were ranged from 0.934 2 to 0.995 7（P0.01）.In rice planting season,residues of herbicides in subsoil increased for a short period and then decreased,and were undetectable after 122 days of treatment.It suggested that the leaching effect of paddy water should be one of the modes of pesticide degradation.Leaching effect was no-obvious in drought soil condition.Rotation of paddy and dry farming should be facilitated to the degradation of pesticide under soil environment.