Short- and medium-chain chlorinated paraffins in sediments from the middle reaches of the Yangtze River: Spatial distributions, source apportionment and risk assessment.

Chlorinated paraffins (CPs) are easily adsorbed into sediments where they pose potential risks to the ecosystem and human health. Few studies have investigated short- and medium-chain CPs (SCCPs and MCCPs) in sediments. The aim of the present study was to comprehensively investigate contamination levels, spatial distributions, sources and risks posed by CPs in sediments from the middle reaches of the Yangtze River. The sediment samples were analyzed by two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). The concentrations of SCCPs and MCCPs ranged from 4.19 to 41.6ng/g dry weight (dw) and not detected to 14.6ng/g dw, respectively. No significant correlation was found between the total organic carbon contents and CP concentrations (P>0.05). The spatial distributions showed that CP contamination levels in the sediments were related to local human activities. The dominant congener groups were C10-11Cl6-7 for SCCPs, and C14Cl7-8 for MCCPs. Correspondence analysis revealed that likely sources of SCCPs were the production and use of CP-42 and CP-52. Principal component analysis indicated that SCCPs and MCCPs in the sediments may come from different sources. Moreover, CPs with nine carbon atoms were quantitated for the first time in sediment samples, and the results indicated they should not be neglected in future analyses. Risk assessments indicated that CPs in the sediments did not pose a great ecological risk currently.