商品氯氰菊酯对斜生栅藻生长的影响及其生理生化效应

研究了商品氯氰菊酯对斜生栅藻(Scenedesmus obliquus)生长及生理生化指标的影响,以了解除虫菊酯农药对水生态系统的影响.在氯氰菊酯暴露下,藻细胞生长受到明显抑制,氯氰菊酯对斜生栅藻生长的72h半效应浓度(EC50)为2.37mg/L.藻细胞所有生理生化指标对氯氰菊酯响应迅速,12h到达最大促进或者抑制效果,48h后趋于平稳.其中12h处理,可溶性糖和可溶性蛋白含量上升,中等浓度组的促进作用最强;超氧化物歧化酶(SOD)活性则呈现出低浓度促进、高浓度抑制效应.氯氰菊酯能促进藻细胞膜脂氧化产物丙二醛(MDA)的产生,且呈现出明显的剂量—效应关系,MDA含量可以作为监测氯氰菊酯污染的生物标记指标之一.研究结果表明,SOD活性抑制以及膜脂氧化是氯氰菊酯对斜生栅藻的重要致毒机理,但自然环境中的氯氰菊酯水平不会对淡水水体浮游藻类的生长产生抑制作用.

Effects of commercial cypermethrin on the growth of Scenedesmus obliquus and its physiochemical responses

The effects of commercial cypermethrin on growth and physiochemical parameters of Scenedesmus obliquus were investigated by 72 h growth tests in a batch-culture system.The purpose was to understand influences of commercial pyrethroid insecticides on aquatic ecosystem.The growth of algal cells was inhibited by cypermethrin in a dose-dependent pattern.The 72 h median effect concentration(EC50) was 2.37 mg/L.All biochemical parameters varied significantly within 12 h exposure,and were stable after 24 h exposure.Cellular contents of soluble protein and sugar were enhanced under the stress of cypermethrin,and the maximum magnification occurred at the moderate concentrations.Activity of superoxide dismutase(SOD) was stimulated at low concentrations and inhibited at high concentrations.However,content of f lipid peroxidation(malondialdehyde,MDA) increased significantly with the increasing of concentration,indicating the potential of using MDA as the biomarker for cypermethrin pollution.The results from this study suggest that the inactivation of SOD activity and consequent lipid peroxidation may be crucial toxic mechanism for cypermethrin to algal cell;however background levels of cypermethrin in natural waters will not inhibit the growth of phytoplankton.