Organochlorine pesticides in soil, air, and vegetation at and around a contaminated site in southwestern China: Concentration, transmission, and risk evaluation.

Remediation and management of contaminated sites have become a prevalent problem under the current situation in China. The present study was conducted to investigate the concentration, transmission, and health risk of organochlorine pesticides (OCPs) in soil, air, and vegetation at and around a typical pesticide-contaminated site located in southwestern China. Exchange flux between soil and air was calculated to investigate the transmission of OCPs. Hexachlorocyclohexane (ΣHCHs, top soil: 19.1 mg/kg d.w., air: 52.3 ng/m3, vegetation: 0.17 mg/kg d.w.) and dichlorodiphenyltrichloroethane (ΣDDTs, top soil: 200 mg/kg d.w., air: 130 ng/m3, vegetation: 0.78 mg/kg d.w.) were the dominant pollutants at the contaminated site. Around the site, the soil, air, and vegetation samples had higher OCP concentrations than those in the normal areas, which were found to be dominated by ΣHCHs (top soil: 129 ng/g d.w., air: 5.09 ng/m3, vegetation: 81.8 ng/g d.w.) and ΣDDTs (top soil: 360 ng/g, air: 7.47 ng/m3, vegetation: 189 ng/g d.w.). The fugacity fractions of OCPs (>0.7) showed a net volatilization from soil into air, indicating that soil is an obvious pollution source for the atmosphere, especially at the site. Through human health risk evaluation, serious carcinogenic risk (CRn) and hazardous index (HIn) were found at the site (CRn: 7.4 × 10-6-1.04 × 10-4, HIn: 0.02 to 8.97) and the nearby areas (CRn: 3.37 × 10-6 for adults and 1.68 × 10-6 for children on average).