The Distribution And Migration Of Short Chain Chlorinated Paraffins In The Offshore Regions Of East China Sea

Short chain chlorinated paraffins （SCCPs）, candidate persistent organic pollutant（POPs） of the Stockholm Convention, have caused widespread concern in recent years.In this study, gas chromatograph-electron capture negative ion low resolution massspectrometry （GC-ECNI-LRMS） has been used to determine the contents of SCCPs inthe sediment samples from the East China Sea （ECS） for studying their temporal andspatial distributions and migration paths.Multiple-proxies of terrestrial organic matters （TOM） have been introduced forinvestigating the migration behaviors of SCCPs in the coastal area of ECS. Thecontents of SCCPs in the surface sediment collected from Yangtze River Delta（YRD） and along the Zhejiang-Fujian coastline ranged from9.0to37.2ng/g （dryweight, d.w.）, displaying a “Band-Style” distribution trend. Spatial distributionpatterns of SCCP congeners presented an increasing trend seaward and southwardalong the coastline for shorter carbon length （C10+C11） and lower chlorinated（Cl5+Cl6+Cl7） congeners, suggesting a spreading tendency seaward and southwardfrom the YRD and the north of the inner shelf. The significant relationship betweenΣSCCPs and total organic carbons （TOC）（R²=0.402, p <0.05） indicated that themigration of SCCPs in sediments was markedly affected by TOC. The spatial patternsof the TOM proxies of TOC δ13C, the contents of ΣC₂₇+C₂₉+C₃₁n-alkanes, TerrestrialMarine Biomarker Ratio （TMBR） and terrestrial TOC （T-TOC） were all similar to thatof ΣSCCPs. Linear relationships between SCCP contents and both the contents ofΣC₂₇+C₂₉+C₃₁n-alkanes （R²=0.537, p <0.05） and T-TOC （R²=0.495, p <0.05） werealso observed. The consistence demonstrated that a major portion of sedimentarySCCPs in the coastal ECS should be from the river input of Yangtze River （YR） and deposited in the YRD and along the inner shelf of the ECS, but few was transported tothe offshore areas.The records of SCCPs in core T06from Zhejiang-Fujian Mud Areas of the ECSpresented that the contents of SCCPs varies from9.38to41.55ng/g, with an averageof22.88ng/g and the deposition flux ranges from80.10to347.36μg/m2·y. Both thevertical variations of the contents and the deposition flux present an increasing trendtowards the core top, indicating the enhanced input of SCCPs into the ECS in recentyears. The lower carbon length （C10） and lower chlorinated （Cl5, Cl6and Cl7）homologues are the most predominant congeners, demonstrating that they were fromthe long-range atmospheric deposition or ocean current transportation. Significantpositive relationship between the contents of TOC and SCCPs is found （R²=0.597, p<0.05）. Terrestrial organic matter indicator of ΣC₂₇+C₂₉+C₃₁n-alkanes also presentsan increasing trend with that of SCCPs. The correlation analysis shows a relativepositive linear relationship （R²=0.363, p <0.05） between SCCP contents andΣC₂₇+C₂₉+C₃₁n-alkane contents. The coincidence demonstrates that sedimentarySCCPs in core T06are mainly from the river input through YR, similar to thoseterrestrial organic matters preserved in the inner shelf of the ECS.