水环境中低浓度溴氰菊酯的降解规律及其动力学研究

Residual Elimination and Kinetics of Low Concentration of Deltamethrin in Water

采用改进的液相色谱检测方法,用于水环境中溴氰菊酯的痕量提取及检测。该方法的平均回收率为96.92%,变异系数小于3.75%,溴氰菊酯在0.02～10μg·L-1浓度范围内有良好的相关性,相关系数大于0.9960,最低检测浓度为0.02μg·L-1。利用该方法分别测定了溴氰菊酯在灭菌淡水、灭菌淡水底泥、天然淡水、天然淡水底泥、灭菌海水、灭菌海水底泥、天然海水、天然海水底泥中的降解动态,建立了其在各样品中的降解方程。各方程均符合一级动力学Ct=C0e-kt,半衰期分别为5.99、1.60、5.28、1.31、4.29、2.10、4.45、1.34d。研究结果表明,溴氰菊酯在水体中的消除半衰期均少于6d,底泥、pH、微生物对其降解都有一定影响,其中底泥吸附是加快溴氰菊酯降解的最主要因素,pH值越高溴氰菊酯降解半衰期越短,微生物的作用也加快了溴氰菊酯在水体中的消除。

Deltamethrin has been widely used in aquaculture; however, few researches about its influence on environmental water have been reported. An improved HPLC method was used for the determination of dehamethrin in water. Deltamethrin was extracted with Hexyl hydride and the average recovery rate was 96.92%, with C.V less than 3.75%. In the concentration of 0.02～10 μg·L^-1, the correlation coefficient was 0.996 0. The detection limit was 0.02 μg·L^-1. The concentration of dehamethrin was determined in sterile freshwater, sterile freshwater and mud, freshwater, freshwater and mud, sterile seawater, sterile seawater and mud, seawater, seawater and mud respectively. The degradation of dehamethrin in environmental water could be described by first-order dynamics equation Ct=C0e-kt, with the half lives of these samples being 5.99 d, 1.60 d, 5.28 d, 1.31 d, 4.29 d, 2.10 d, 4.45 d, 1.34 d, respectively, showing that the half lives of dehamethrin in water were less than 6 d. The elimination trend was affected by mud, pH and microorganism. The absorption of mud was the dominating factor, the half life of dehamethrin decreased with the increasing of pH, and microorganism quickened the elimination of dehamethrin in water.