毒死蜱对南方稻区水域生态效应的室内微宇宙模拟研究

Indoor microcosms study on ecological effects of rice paddy applied with chlorpyrifos on zooplankton in south China

利用浙江诸暨稻田附近池塘底泥和池塘水构建了体积为100 L的室内微宇宙系统,分别以质量浓度为50和5μg/L的毒死蜱在排沟和池塘中进行单次施药模拟试验,研究了其对水生浮游动物的影响及生态效应。结果表明:浮游动物种群对毒死蜱的敏感性依次为枝角目>桡足类>轮虫类;高浓度处理组中枝角目种群数量在实验结束时未能恢复;桡足类种群数量有所下降,但在施药14 d后开始恢复;轮虫对毒死蜱最不敏感,且由于节肢动物减少,处理组轮虫数量反而出现明显的上升。PRC分析结果表明,毒死蜱对水生浮游动物群落的生态毒性效应与其在微宇宙体系中的浓度相关,且在35 d实验周期内,微宇宙体系中部分生物种群尚难以恢复到正常水平。

Indoor freshwater microcosms were constructed to mimic pond ecosystem near paddy rice area in Zhuji, Zhejiang Province, southeast of China. Single application of chlorpyrifos at 50 μg/L and 5μg/L to study insecticidal effects at ecological level. Result of the study indicated that the zooplankton community was seriously affected at both concentrations. The order of sensitivity of the zooplanktons towards chlorpyrifos was Cladocera sp. 〉 Copepoda sp. 〉 Rotifer sp.. The most sensitive group was Cladocera sp.. Abundance of the Cladocera sp. did not recover at high concentration till the end of experiments. Chlorpyrifos produced little effect on the Copepoda sp.. The population decreased immediately after application but it increased after 14 days. The Rotifer sp. was the most insensitive one to chlorpyrifos, and due to the removal of the competitive stresses, the abundance of the treated groups rose beyond controls. Result of the PRC analysis showed that the ecological impact of chlorpyrifos was concentration-dependent, and the microcosms did not recover in 35 days after application.