Plankton response to sudden polychlorinated biphenyls pollution on a Reservoir of North China based on AQUATOX model

Emergency management research on sudden organic pollution accidents in urban water sources is of great significance. In the study, AQUATOX, coupled water quality and water quantity based on food web, was implemented to simulate and predict the effects of sudden Polychlorinated biphenyls (PCBs) pollution under different concentrations scenario on water quality and dominant biological populations in Panshitou Reservoir, China. The model was used to quantify how the biomass changes of the modelled taxa in the reservoir food web deviated from natural conditions due to varying concentration inputs of the PCBs. Also, no observed effect concentrations (NOECs) were derived using AQUATOX model. The results showed that the contents of DO, TN, TP and NH4+-N increased slightly with the concentration increase of PCBs, and the comprehensive water quality indexes (WQI) decreased little. The biomass of dominant biological populations did not show significant changes in the previous week, but the changes gradually increased, and the ecological risk rose correspondingly. The NOEC levels of PCBs for primary producers, such as diatom, green algae, blue-green algae and cryptoalgae, were about 1.89μg/L, 0.66μg/L, 0.81μg/L and 0.45μg/L, respectively; consumers such as water fleas, planktonic predators, and oligochaetes were around 3.4μg/L, 2.6 μg/L, and 0.81 μg/L, respectively. Compared with benchmarks of NOEC from the PCB Residue Effects Database of USEPA, threshold concentration computed using AQUATOX model were generally of the same order of magnitude in Panshitou Reservoir ecosystem. Our findings indicated that ecosystem models could be a useful tool in the assessment of organic chemical sudden impact on reservoir ecosystems as a whole.