Toxicology Effect Of Organic Pesticides On Freshwater Microalgae

Base on the deficiency of research on the surface water quality criteria on Pesticides in China, in this paper, we studied four kinds of organic pesticide on the Chlorella pyrenoidosa and Merismopedia sp. acute and chronic toxicity effects under laboratory conditions. This research took the Chlorella pyrenoidosa and Merismopedia sp. as experiment object in Yangtze River Delta region and chose chlorpyrifos、chlorothalonil、endosulfan and trifluralin as the test target. This research provided theoretical and scientific data for the local aquatic organisms and organic pesticide varieties screening study. The main conclusions were as follows:1. The conclusion of acute toxicity experiment: The effective concentration (EC50) for72h of chlorpyrifos, endosulfan,trifluralin and chlorothalonil were29.42mg/LA4.52mg/L、1.63mg/L、1.93mg/L, respectively, on Chlorella pyrenoidosa. The effective concentration (EC50) for72h of chlorpyrifos, endosulfan, trifluralin and chlorothalonil were25.80mg/L、6.57mg/L、60.94mg/L、9.87mg/L, respectively, on Merismopedia sp. Chlorpyrifos, endosulfan, trifluralin and chlorothalonil can affect algae Chlorella pyrenoidosa peaceful split of algal cells metabolism, causing algal cells of SOD, CAT activity changes. SOD activity could not be used as chlorpyrifos targets set for evaluating the toxicity of Chlorella pyrenoidosa and could be used as chlorpyrifos、chlorothalonil endosulfan and trifluralin targets set for evaluating the toxicity of Merismopedia sp. CAT activity could not be used as chlorpyrifos targets set for evaluating the toxicity of Chlorella pyrenoidosa and not be used as chlorpyrifos, trifluralin targets set for evaluating the toxicity of Merismopedia sp.2. The conclusion of chronic toxicity experiment:The inhibitory effect of chlorpyrifos on Chlorella pyrenoidosa to chlorophyll a was not obvious, whatever the effect of chlorothalonil、 endosulfan and trifluralin was very obvious, Thus chlorophyll a could not be used as the toxicity evaluation index of chlorpyrifos on Chlorella pyrenoidosa, but it could be used as the sensitive index of effective toxicity evaluation of chlorothalonil、endosulfan and trifluralin. The inhibitory effect of chlorpyrifos, endosulfan and trifluralin on Merismopedia sp. to chlorophyll a was not obvious, whatever the effect of chlorothalonil was very obvious, Thus chlorophyll a could be used as the sensitive index of effective toxicity evaluation of chlorothalonil. The contents of MDA could be increased by the four kinds of organic pesticides, but under the after effect of stress for a long time, the contents of MDA on Chlorella pyrenoidosa under the effect of chlorpyrifos could be reduced. However, MDA couldn’t be the sensitive index of effective toxicity of chlorpyrifos. The contents of MDA could be increased by the four kinds of organic pesticides, but under the after effect of stress for a long time, the contents of MDA on Merismopedia sp. under the effect of endosulfan could be reduced. However, MDA couldn’t be the sensitive index of effective toxicity of endosulfan.