Human health risk management of a mercury, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, and pentachlorophenol contaminated site: Remediation action

The An-Shun plant soil contaminated site of China Petrochemical Development Corporation polluted by multi-pollutants, including mercury, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), and pentachlorophenol (PCP), is a unique and complex soil contamination case. During the remediation period environmental monitoring of groundwater, river water, and air were conducted to evaluate the health risk of the residents near the site to understand the effect of secondary pollution. Multiple exposure pathways were considered including ingestion and inhalation. Monitoring results showing contaminants level with notable health risk only occurred inside the site. The concentration of mercury, PCDD/Fs and PCP in the river water around the site was low with only one monitoring result showing hazard index contributed by PCDD/Fs of 1.11. The results suggested that the health risk from mercury, PCDD/Fs, and PCP were retained in the site, while the health risk to the residents around the site was negligible. Solid phase and gas phase mercury and PCDD/Fs in the air were monitored in this study. Mercury in the air was mainly presented in the gas phase with concentration three orders of magnitude higher than in solid phase. Both mercury, gas and solid phase, and PCDD/Fs concentrations were lower in summer (May to September). The correlation of PCDD/ Fs and particulate matter (PM10 and PM2.5) suggested the effect of the Asian dust storm episodes and the Southeast Asia biomass burning events on increasing of PCDD/Fs concentration in fall, winter, and spring. However, the secondary pollution control strategies applied in this site effectively restrained the inhalation health risk to the residents near the site in acceptable range.