5种杀虫剂在水-人工底泥系统中对大型溞的急性毒性及其比较

建立了包含＂水＂和＂底泥＂两相的水蚤毒性测试系统（水相为全人工培养液,＂底泥＂为OECD配方标准化人工土）,并通过该系统测得毒死蜱（chlorpyrifos）、氟虫腈（fipronil）、氰戊菊酯（fenvalerate）、氟氯氰菊酯（cyfluthrin）、联苯菊酯（bifenthrin）对大型溞（Daphnia magna）的急性毒性（48 h-LC50）分别为9.01、88.1、0.142、0.097 6、0.050 4μg.L-1。对比水相的急性毒性测定结果发现,在有底泥的条件下,所测得的联苯菊酯、氟氯氰菊酯、毒死蜱的大型溞毒性低于水相的测定结果,而氰戊菊酯、氟虫腈的毒性则比水相中的测定结果要高。研究结果反映出药剂和受试生物在＂水-底泥＂系统内相互作用的复杂性和难以预见性,从而在为相关农药生态安全评价提供科学依据的同时,为在更接近实际暴露状态下开展评价试验提供了一种简便有效的方法。

Acute Toxicity of Five Insecticides to Daphnia magna in Water-sediment System

A water-sediment system consisting of culture medium of M4 and artificial soil was established in this study.Acute toxicity of five insecticides,i.e.chlorpyrifos,fipronil,fenvalerate,cyfluthrin,and bifenthrin,towards water flea,Daphnia magna,was tested with this system.The insecticides were added by spiking stock solution of the standard or the technical materials into the water columns and the daphnia were introduced thereafter.Result of the study showed that 48 h-LC50 values for the five insecticides were determined to be 9.01,88.1,0.142,0.097 6 a.i.μg·L-1,and 0.050 4 a.i.μg·L-1.The corresponding values of 48 h-LC50 derived from sediment-free systems were determined to be 3.31,238,0.459,0.050 7 a.i.μg·L-1 and 0.030 4 a.i.μg·L-1.To compare the LC50 values from the two systems,we could see that toxicity of chlorpyriflos,cyfluthrin,and bifenthrin enhanced in water-sediment system,whereas the toxicity of fipronil and fenvalerate declined.It seems that pattern of change of LC50 did not accord well with fluctuation of lg Kow values among the insecticides involved.This study revealed that it was difficulty to predict toxicity declination for pesticides being applied in water-sediment system merely by hydrophobic nature because the declinations were determined by multi factors.