PROBABILISTIC ECOLOGICAL RISK ASSESSMENT OF ORGANOCHLORINE PESTICIDES (OCP_S) IN SEDIMENT POREWATER FROM A SHALLOW FRESHWATER LAKE, CHINA

摘要

The probabilistic ecological risks associated with eight organochlorine pesticides (OCPs) in Baiyangdian Lake were assessed based on their concentrations in sediment porewater and their acute toxicity (LC_(50) or EC_(50)) to aquatic organisms using probability overlapping area (POA), joint probability curve (JPC), and Monte Carlo simulation (MCS). The results of three methods indicate that these OCPs pose varying degrees of the ecological risks to aquatic organisms. Endrin had the highest overall risk, whereas α-HCH had the lowest. The POA results indicated only α-HCH and γ-HCH exhibited ecological risks lower than 10%. The risks associated with endrin, dieldrin, and p,p'-DDT were relatively significant (probabilistic risk = 100%) at concentrations that affect less than 5% of aquatic species, according to JPC. The MCS results suggested that the ecological risks associated with aldrin, endrin, dieldrin, and p,p'-DDT all exceed 10%. POA demonstrated the degree of risk, JPC showed the risk probability associated with damaged species ratio, and MCS was more accurate for analyzing ecological risk because it allows sufficient random number simulation.