Distribution And Potential Sources Of Perfluoroalkyl Substances (PFASs) In Jiaozhou Bay

Perfluoroalkyl substances（PFASs）,as a class of emerging persistent organic pollutants,ubiquitously distributed in various types of environmental matrices.PFASs have potential toxicity and environmental persistent and they can bioaccumulate and have adverse effects on human and ecological environment.Therefore,Environmental problems caused by PFASs have attracted a great attention from many scientists.Coastal aquatic environment is an important media to Land-Ocean interaction.With the widespread pollution of PFASs in terrestrial aquatic environment,the pollution of PFASs to the coastal environment is becoming more and more serious.Jiaozhou bay is an‘modeling bay’for coastal ecological research.In the past few decades,with the rapid development of economy and society,environmental health undergo seriously threat.In this study,Jiaozhou bay is selected as the study area.Surface seawater samples from different seasons,rainfall samples in three consecutive rainfall events,river water samples,effluents from wastewater treatment plants（WWTP）and various types of organisms were collected.High performance liquid chromatography-electrospray ionization multi-stage mass spectrometry（HPLC-ESI-MS/MS）was used to determine fourteen kinds of typical PFASs.Spatiotemporal distribution and potential source of PFASs in surface water and bioaccumulation characters in aquatic organisms were preliminarily discussed.The results are as follows:The total concentrations of PFASs（∑PFASs）in surface seawater from Jiaozhou bay ranged from 1.71 to 48.27 ng/L（mean concentration,16.41 ng/L）.PFOA was the predominant PFASs in surface seawater from Jiaozhou bay with mean concentration of 11.58 ng/L,accounting for 29.2-95.6%.The mean concentrations of PFASs in surface water from Jiaozhou bay have obviously seasonal difference,∑PFASs were in winter and spring than those in summer and autumn which may attribute to seasonal variation of wet precipitation and tidal prism.∑PFASs displayed a decreasing trend from the coastal area.∑PFASs were in eastern and northern area than in the mouth of bay and middle regions.Effluents from coastal river and WWTP is an important sources of PFASs in Jiaozhou bay,and the contribution of wet precipitation can not be neglected.∑PFASs in aquatic organisms from Jiaozhou bay ranged from 1.73-23.68 ng/g ww,with mean concentration 7.33 ng/g ww.PFOS is the predominant PFASs in aquatic organisms from Jiaozhou bay,which contributed to 23.26%-68.39%of the∑PFASs in the aquatic organisms,with concentrations ranging from 0.87 to 16.15ng/g ww.Concentrations of PFOS in fish were higher（6.39 ng/g ww）than sepia（2.01ng/g ww）,shrimp（1.79 ng/g ww）,shellfish（1.23 ng/g ww）and phytoplankton（1.13ng/g ww）.Log BAFs of PFOA,PFNA,PFDA,PFUnDA,PFDoDA and PFOS in aquatic organisms were higher than 1,indicated that long-chain（C≥8）PFASs obviously accumulated in organisms.The bioaccumulation potential increased with increasing carbon length.But the bioconcentration for PFDoDA(C₁₂)was lower than expected,and bioaccumulative potential is limited by molecular sizes for PFCAs with>11-12 fluorinated carbons.In addition,The values of estimated daily intake（EDI）are much less than tolerable daily intake（TDI）.This suggests that the present concentrations of PFASs in the seafood from Jiaozhou bay will probably not cause immediate harm to the nearby population.