[Combined toxicity of cadmium and S-metolachlor to Scenedesmus obliquus].

The single and combined effects of Cd2+ and S-metolachlor on acute toxicity, total soluble protein content, superoxide dismutase (SOD) activity and cell membrane permeability of Scenedesmus obliquus (S. obliquus) were studied using the standard toxic testing methods. The results showed that the EC50 of Cd2+ and S-metolachlor decreased with time, and the acute toxicity of S-metolachlor was higher than that of Cd2+, EC(50-24h) of Cd2+ and S-metolachlor was 0.

[Influence of S-metolachlor and Cd2+ on photosynthesis of Scenedesmus obliquus].

The single and combined effects of Cd2+ and S-metolachlor on the chlorophyll content and chlorophyll fluorescence parameters of Scenedesmus obliquus were studied by using standard toxic testing method. Both Cd2+ and S-metolachlor had effects on the chlorophyll content and fluorescence parameters such as F0, FV/Fm, FV/F0, Y( II), qP, NPQ and rETR after 96 h-exposure, showing that Cd2+ and S-metolachlor damaged the PS II in algae, inhibited the primary reaction of photosynthesis, stopped the process of photosynthetic electron transport, and destroyed its ability of heat dissipation. The effects of Cd2 + on the chlorophyll content and fluorescence parameters were greater than those of S-metolachlor, and the effects increased with the increasing concentration.

[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.