Joint Exposure Risk Assessment for Dual Heavy Metal Mixing Contamination Emergencies in the Lower Reaches of the Dongjiang River

Acute heavy metal leakage accidents pose an essential threat to human health, ecosystem balance, and property security in a river.Joint exposure risk assessment for an accidental heavy metal mixed pollution is helpful to improve the quality and delicacy of risk prevention and management.To address the lack of research on the joint exposure risk assessment of accidental river pollution caused by heavy metal leakage, a Copula-based exposure risk dynamic simulation model was proposed.A coupled hydrodynamic and accidental heavy metal exposure model is constructed for an hourly simulation of the concentration distributions of heavy metals from each risk source once accidental leakage has occurred.The Copula analysis was introduced to calculate the dual heavy metal joint exposure probability in real time.This method was applied to an acute Cr(VI)-Hg(II) joint exposure risk assessment for a typical electroplating enterprise in the mainstream of the lower reaches of the Dongjiang River.The results indicated the Cr(VI)-Hg(II) joint exposure probability distributions were influenced by both Cr(VI) and Hg(II) marginal exposure functions, rather than the linear superposition.Besides, acute Cr(VI) exposure has a greater impact on the joint exposure probability distributions, compared to the acute Hg(II) exposure.This research highlights an effective probabilistic approach for performing a joint exposure risk analysis of accidental river pollution caused by the heavy metal mixtures.