Congener profiles, air-soil exchange, and potential risks of short- and medium-chain chlorinated paraffins in demonstration zone of Yangtze River Delta

Abstract

Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) have been widely detected in soil environment. However, as a good matrix for trapping chlorinated paraffins (CPs) in the air, tree bark has been less studied for CP pollution, and limited information exists on the air-soil exchange of CPs. In this study, 48 CP congener groups were measured in the surface soils and tree barks from 36 points in the demonstration zone of the Yangtze River Delta (YRD). The concentrations of SCCPs and MCCPs in the soils were 3.97 × 10−2-1.13 and 0.237–13.8 μg/g dw, and their concentrations in the barks were 0.127–5.38 and 0.944–80.8 μg/g dw, respectively. Generally, the highest levels of CPs in both soils and barks were found in the Taipu River watershed, which were concentrated areas for the textile manufacturing activities. Congeners profile indicated that C10Cl5-8 and C14–15Cl5-7 were the major SCCPs and MCCPs. With respect to the air-soil exchange behaviors, 70.0% fugacity fractions (ffs) values were below 0.3, indicating the dominant deposition of CPs congeners, and log KOA values were inversely associated with the ffs. Significantly higher net depositions (3.06 ± 5.08 ng/(m2⋅h)) than emission fluxes (0.37 ± 1.18 ng/(m2⋅h)) were observed for MCCPs, while the trend was reversed for SCCPs. A preliminary risk assessment suggested that CPs pose a low ecological risk for the demonstration zone of the YRD and exerted low risks through dust ingestion and dermal contact.