Impact Of Chlorprifos On Zooplanktons In Smll-sized Recombinant Systems

According to the amount of chlorpyrifos and the characteristics of environmental chemistry, it produces a potential threat to the environmental creatures, especially aquatic organisms, so it is necessary to make an ecological risk assessment. In this paper, the author cultivated Brachionus calyciflorus, Daphnia carinata, Eucyclops serrulatus and Dolerocypris sinensis, and studied toxicity effects of chlorpyrifos to the four species. On this basis, it also studied the change and recovery of the mixed populations under the stress of chlorpyrifos and detected the changes of water quality, using the indoor aquatic ecosystems (2L) containing Ceratophyllum demersum L. as the tool.Research on the rotifer life history showed that under experimental conditions, the average life and generation time of rotifer were78.76±33.08h and51.56±20.55h. With the improvement of inoculation density, rotifers population growth rate was declining. So the toxicity test’s initial population density was35ind/100mL and the experiment time was144h. The results showed that the96h-EC50and120h-EC50of chlorpyrifos to Brachionus calyciflorus were0.6066mg/L and0.7323mg/L.The author measured the acute toxicity of chlorpyrifos to Daphnia carinata, Eucyclops serrulatus and Dolerocypris sinensis. The results showed that the48h-LC50were0.6000,6.9200and2.8600μg/L, respectively.In order to study the interrelations between Daphnia carinata, Eucyclops serrulatus, Dolerocypris sinensis and Brachionus calyciflorus, the author made mixed cultures between different density of crustaceans and Brachionus calyciflorus (inoculation time of0.35ind/mL). The results showed that the population of Brachionus calyciflorus was suppressed by three crustaceans. With the inoculation density increased, the inhibiting effect of Brachionus calyciflorus population was increased. When the incubation time was prolonged, this effect could cause the death of Brachionus calyciflorus population further research showed that there was only simple competition relationship between Daphnia carinata and Brachionus calyciflorus. While Eucyclops serrulatus and Dolerocypris sinensis suppressed Brachionus calyciflorus, their growth had gained a certain degree of promotion in turn.In PCA of mixed population of four species, the results showed that there was negative correlation between three crustaceans and pesticide; positive correlation between rotifers and pesticide. On the part of quality parameters of water, it showed that ammonia nitrogen and turbidity were positively correlated with pesticide; the pH, conductivity and total nitrogen were slightly negatively correlated with pesticide; total phosphorus was no correlation. The PCA also showed, the chitobiase of activity was positively correlated with these crustaceans, and negatively correlated with Brachionus calyciflorus.On the basis of PCA, the author made Williams test to sample scores of each sampling time. The result showed that the NOEC and LOEC of chlorpyrifos to mixed population were0.25,1.25μg/L (p<0.01), respectily.