Research On The Toxicity Of Pesticides To Microorganism In Sediments And Photobacterium Phosphorous

With the wide use of pesticides, their combined pollution in water sediment has been extensively concerned. The paper chose microbial toxicity as testing methodology to determine signal and joint toxicity of multiple pesticides on the background of sediment environment to analyze their interaction in combined pollution. The results can provide theoretical basis and statistic supports for ecological risk assessment of pesticides in water environment.Protozoa, mixed bacteria and green algae in sediment were selected to initially evaluate signal toxicity of dimethoate, malathion, atrazine, prometryn, metalaxyl, tebuconazole and acetochlor. It finds that seven pesticides firstly restrain survival rate of protozoa and green algae and then promote it, while early they promote bacterial growth and then present a inhibit toxicity. Different pesticides contribute mainly in pesticides mixtures’joint toxicity on different kind of microorganisms.For the further research on the joint toxicity and interaction mechanism of pesticides mixtures, photobacterium T3was adopted as tested biological to determine signal toxicity of seven pesticides, and orthogonal design, factorial design and equal-effect-concentration ratio were used to build toxicity predication model of pesticides mixtures. The result proves that toxicity of all the pesticides can be effectively described by Weibull and Logit model. Dimethoate, malathion and acetochlor express highly significant influence in joint toxicity of pesticides mixtures, which presents as antagonism between dimethoate and malathion<signal toxicity of malathion, and concentration of dimethoate and malation can decide their combined toxicity on T3. While atrazine and prometryn are added in mixed system, antagonism of atrazine and malathion, prometryn and acetochlor as well as synergistic effect among these pesticides play a major role, and single effect of malathion is coverd.