丁草胺及其复配剂对水生生物的急性毒性与安全性评价

丁草胺及其复配剂是防治稻田杂草的重要农药品种,为明确此类农药对水生生物的毒性,在稻区进行杂草防治时避免和减轻对水生生物的毒害,分别测定了50%丁草胺乳油、70%丁草胺·异噁草松·吡嘧磺隆乳油、75%丁草胺·噁草酮·乙氧氟草醚乳油、78%丁草胺·噁草酮乳油对斜生栅藻、大型溞和斑马鱼的急性毒性。结果显示4种制剂对斜生栅藻72 h的EC_(50)分别为4.143×10~(-3), 3.207×10~(-3), 1.936×10~(-4)和1.144×10~(-3) mg a.i.·L~(-1),且均为高毒;大型溞48 h的EC_(50)分别为1.576、2.165、1.284和1.595 mg a.i.·L~(-1),且均为中毒;斑马鱼96 h的LC_(50)分别为0.440、0.407、0.871和0.445 mg a.i.·L~(-1),且均为高毒。结果表明,丁草胺单剂及3种复配剂对大型溞的安全风险性较低,但对斜生栅藻和斑马鱼的安全风险性很高,因此在施用农药时应注意对藻类的危害,避免在雨天或鱼类敏感水区及保护区附近施用。

Acute toxicity and safety evaluation of butachlor and its compound agents on aquatic organisms

Butachlor and its composite agents are important pesticides that are widely used to control weeds in rice fields. The aim of this investigation was to clarify the toxicity of Butachlor and its composite agents to aquatic organisms, to both avoid and reduce the toxicity of rice fields. The acute toxicity of 50% butachlor EC, 70% butachlor·clomazone pyrazosulfuron-ethyl EC, 75% butachlor oxadiazon oxyfluorfel EC , 78% butachlor oxadiazon EC to Desmodesmus subspicatus, Daphnia magna, and Brachydanio rerio were determined. The results showed that the 72 h-EC50 values of acute oral toxicity to Desmodesmus subspicatus were 4.143×10-3, 3.207×10-3, 1.936×10-4 and 1.144×10-3 mg a.i.·L-1, respectively, and they were all highly toxic. The 48 h-EC50 values of acute oral toxicity to Daphnia magna were 1.576, 2.165, 1.284, and 1.595 mg a.i.·L-1, respectively, and they were all moderately toxic. The 96 h-LC50 values of acute oral toxicity to Brachydanio rerio were 0.440, 0.407, 0.871 and 0.445 mg a.i.·L-1, respectively, and these were all were highly toxic. The results showed that the butachlor agent and its 3 joint compounds had lower safety risks to Daphnia magna, but the safety risk to Desmodesmus subspicatus and Brachydanio rerio were very high. Therefore, attention should be paid to algae when applying pesticides as they may be hazardous, and applications should be avoided on rainy days or near sensitive areas of fish and protected areas.