异丙甲草胺与锌共存对斜生栅藻毒性手性差异影响

为评价重金属与手性农药共存的生物选择性毒性,采用毒性试验标准方法研究了Rac-、S-异丙甲草胺单独及与锌共存对斜生栅藻的手性毒性差异.结果表明,Zn2+存在条件下Rac-、S-异丙甲草胺对斜生栅藻的生长趋势影响与除草剂单独作用时的趋势基本相同,Zn2+的存在降低了高浓度除草剂对斜生栅藻的生长抑制作用,处理初期(24 h)0.30 mg·L-1Rac-和S-异丙甲草胺单独对斜生栅藻生长的抑制率分别为49.61%和59.73%,与Zn2+联合作用其抑制率分别为38.41%和42.52%.Zn2+的存在增加了Rac-和S-异丙甲草胺对斜生栅藻的立体选择性毒性差异,使S-异丙甲草胺急性毒性增大的程度大于Rac-异丙甲草胺毒性的增加;与Zn2+的联合毒性作用类型表现为除草剂在低浓度下为部分相加作用,高浓度下为拮抗作用;除草剂单独及与Zn2+联合作用处理96 h后的斜生栅藻叶绿素含量变化与其生长趋势基本一致.

Influence of the Coexistence of Zn2+ on the Enantioselective Toxicity of Metolachlor to Scenedesmus obliquus

To evaluate the enantioselective toxicity of chiral pesticide coexisting with heavy metal, the enantioselective toxicity of Rac-, S-metolachlor alone and coexisting with Zn²⁺ on Scenedesmus obliquus was studied by using standard toxic testing method. The results showed that the trend of the enantioselective toxicity of Rac- and S-metolachlor coexisting with Zn²⁺ was similar to that of Rac- and S-metolachlor alone. The growth inhibition rate of Scenedesmus obliquus was decreased by the coexistence of Zn²⁺ with high concentrations of metolachlor. The inhibition rates with 0.30 mg·L^-1 Rac- and S-metolachlor alone at 24 h were 49.61% and 59.73%, and in the coexistence of Zn²⁺ the values were 38.41% and 42.52%, respectively. The enantioselective toxicity of Rac- and S-metolachlor was expanded and the toxicity of S-metolachlor increased greater than that of Rac-metolachlor. The coexistence of Zn²⁺ showed partial increase in toxicity of metolachlor in low concentrations, while there was antagonistic effect in high content of metolachlor. The trend of Chlorophyll content of Scenedesmus obliquus at 96 h was in accordance with the growth inhibition.