草甘膦对大型溞的急性和慢性毒性效应研究

选取99.5%草甘膦原药,研究其对大型溞的急性毒性和21 d慢性毒性效应,观察其对大型溞生长和繁殖指标的影响。急性毒性试验结果表明,草甘膦对大型溞的48h-EC50为151.057 mg·L~(-1),其对溞类的毒性为低毒;慢性毒性试验结果表明,草甘膦对大型溞的初次产幼溞时间、产幼溞数量、产幼溞胎数以及存活个体的平均体长都有显著的影响,其中,3.125 mg·L~(-1)的暴露浓度可以显著减少大型溞产幼溞数量和产幼溞胎数。综合考虑各项指标,21 d最低可观测效应浓度(LOEC)值为3.125 mg·L~(-1),无可观测效应浓度(NOEC)值为1.56 mg·L~(-1)。此外,研究还发现在草甘膦暴露浓度为25 mg·L~(-1)时,可以显著延长大型溞首次产卵时间,但未发现草甘膦暴露对大型溞初次蜕壳时间以及蜕壳次数有何显著性影响。研究结果表明,草甘膦在一定程度上对大型溞的生长和繁殖具有抑制效应。

Acute and chronic toxicity of glyphosate to Daphnia magna

Glyphosate is widely used in agriculture as a broad spectrum herbicide.With the increasing of application, it''s effects on aquatic organisms have also been widely concerned. 99.5% glyphosate technical was selected to assess the acute toxicity to Daphnia magna and the chronic effects on the growth and reproduction after 21-d exposure.The results of acute toxicity test showed that glyphosate had low acute toxicity against Daphnia magna, the 48h-EC₅₀ was 151.057 mg·L^-1. The results of chronic test showed that the first reproduction time, the number of total offspring per female, the number of brood per female and the body length of Daphnia magna were significantly affected when exposure to glyphosate at the concentration of 3.125 mg·L^-1, the number of total offspring per female and number of brood per female of Daphnia magna were significantly reduced. Taking into account of each index in this experiment, the 21-d lowest observed effect concentration(LOEC) was 3.125 mg·L^-1 and the no observed effect concentration(NOEC) was 1.56 mg·L^-1. In addition, when exposed to glyphosate at 25 mg·L^-1, the first reproduction time of Daphnia magna could be dramaticlly prolonged. However, the first molting time and the number of molting of Daphnia magna had not been observed during the 21-d glyphosate exposure. The results suggested that glyphosate had inhibiting effects on the growth and reproduction of Daphnia magna.