Studies On The Toxic Effect Of Three Kinds Of Organophosphorus Pesticides To Daphnia Magna Under Different Ammonia Nitrogen Level

Base on the deficiency of research on the surface water quality criteria on Pesticides in China, in this paper, we studied three kinds of organophosphorus pesticide on the Daphnia magna acute and chronic toxicity effects under laboratory conditions. This research took the Daphnia magna as experiment object in Yangtze River Delta region and chose chlorpyrifos、chlorothalonil and trifluralin as the test target. This research provided theoretical and scientific data for the local aquatic organisms and organophorus pesticide varieties screening study.1. The effective concentration (LC50) of24h and48h of chlorpyrifos, trifluralin and chlorothalonil were0.61μg/L、0.71mg/L,1.5Mg/L and0.13μg/L、0.29mg/L、0.96mg/L, among which,the safety concentration of Pesticides were0.018μg/L、0.015mg/L and0.118mg/L.The toxicity of chlorpyrifos was the highest than other pesticides and the toxicity of trifluralin was higher than chlorothalonil. The metabolic balance of cells of Daphnia magna could be broken by chlorpyrifos, trifluralin and chlorothalonil. Therefore, they could be used as the sensitive index for monitoring the Pesticide contamination.2. The activity of SOD enzyme on Daphnia magna was firstly increased ang then decresed when the concentration of pesticides were increased in48h. There was no obvious effect in24h. The activity of GST enzyme on DaPhnia magna was induction in the low concentrations and inhabited in the high concentration in24h. But the GST enzyme was restrained in three kinds of Pesticides, only of chlorothalonil, the activity was increased in low concentrations. The toxicy of chlorothalonil on DaPhnia magna was lower than that of the other two Pesticides. Therefore,the activity of GST was more effective and more rapid than SOD.3. The first brood time, first spawning time, fecundity and total production for the first time were suppressed on three kinds of organic phosphorus pesticides,w hile under the effect of different nitrogen levels, the inhibition of Daphnia magna was more pronounced than before. They were promoted each other. In addition the growth rate of Daphnia magna was the higest in rich level. After the pesticide effected, low concentration of ammonia nitrogen level to promote the synergy of different Daphnia magna ontogeny, while in high concentration could inhibit the.