多菌灵在水稻及土壤中的消解动态和残留规律研究

采用田间试验方法,研究了多菌灵在稻田水、土壤和稻秆中的消解动态,测定了多菌灵在水稻和土壤中的最终残留量。样品采用甲醇和稀盐酸的混合溶液提取,经液-液分配净化,HPLC紫外分析测定。结果表明,田水、土壤、稻秆、谷壳、糙米中多菌灵添加浓度为0.05~1.0mg·kg-1时,平均回收率为83.16%~95.44%,变异系数在1.23%~5.32%之间,方法的最低检测浓度为：田水0.005mg·L-1,土壤0.005mg·kg-1,稻秆0.050mg·kg-1,谷壳0.050mg·kg-1,糙米0.025mg·kg-1。多菌灵在田水、土壤和稻秆中的消解动态均符合一级动力学方程,半衰期分别为2.53~3.41d、6.20~7.27d、3.27~3.91d,原始沉积量与施药量、施药次数密切相关。以231g·hm-2和346.5g·hm-2间隔7d施用多菌灵2次和3次,末次施药21d后多菌灵的最高残留量为：土壤未检出（≤0.005mg·kg-1）,稻秆0.524mg·kg-1,谷壳0.528mg·kg-1,糙米未检出（≤0.025mg·kg-1）。多菌灵在稻秆和谷壳中的残留量相对较高,以该稻秆和谷壳作为饲料有一定的风险;多菌灵在糙米中的残留量低于我国和食品法典委员会（CAC）及日本的最大残留限量（MRL）标准。

Residue and Degradation of Carbendazim in Rice and Soil

This paper studied the residue dynamics of carhendazim in paddy water, soil and rice, and determined its final residue in paddy and soil with the method of field test. Samples which were extracted with the mixed solution of methanol and rare hydrochloric acid were cleaned up by liquid to liquid separation, and determined by HPLC-UV. The results showed that while the spiked concentration of carhendazim in paddy water, soil, rice straw, rice shell and brown rice ranged from 0.05 mg.kg-1 to 1.0 mg.kg-1, the average recovery from 83.16% to 95.44% with the variation coefficient of 1.23% to 5.32%, the minimum detectable mass fraction in paddy water, soil, rice straw, rice shell and brown rice samples were 0.005, 0.005, 0.050, 0.050, 0.025 mg-kg-1. Degradation of earbendazim in paddy water, soil and rice conformed to chemical kinetic equation. The half-life was 2.53-3.41 days in paddy water, 6.20-7.27 days in soil and 3.27-3.91 days in plant. The original deposition was closely related to application rate and spraying frequency. Carbendazim was sprayed twice or three times at a 7 days interval with the application dose of 231 g. hm-2 and 346.5 g.hm-2, the final maximum residue of carbendazim after 21 days were ND （not detected ） in soil, 0.524 mg.kg-1 in rice straw, 0.528 mg.kg-1 in rice shell and ND in brown rice, respectively. The residue of carbendazim in rice straw and rice shell was higher than the standard, so there might be some risk in using the straw and shell as feeds. But the residue in brown rice could be lower than the MRL（Maximum Residue Limit） in China, CAC and Japan.