Combined toxicity of pesticide and heavy metal to Daphnia magna

Pesticides and heavy metals are two common types of pollutants in aquatic environment. The combined pollution is noteworthy because they posed a serious threat to aqua ecology and living environment for human. Herein, the acute toxicities of 3 common pesticides (chlorpyrifos, triazophos and fipronil) and 2 common heavy metals (Pb and Cd) to Daphnia magna were evaluated. Their combined toxicities were also studied using five-factor quadratic general rotary unitized design. The 48 h-EC50 values of chlorpyrifos, triazophos, fipronil, Pb2+ and Cd2+ to D. magna were 6.30, 7.27, 2.17, 454.91 and 1 175.74 μg/L, respectively. The contribution of these five pollutions to combined toxicological effects following the order: Cd2+ > triazophos > fipronil > chlorpyrifos > Pb2+. Combined effects of five pollutants was observed on the survival of D. magna. Moreover, the maximum theoretical synergy appears when chlorpyrifos was 0.811 μg/L, triazophos concentration was 17.22 μg/L, fipronil was 5.65 μg/L, Pb2+ was 83.75 μg/L and Cd2+ was 3 793.15 μg/L. The data of this study can provide support for the risk assessment of composite pollutants.