Pollution Characteristics Of Per-and Polyfluoroalkyl Substances In Soils And Coastal Sediments In Eastern China

Per-and polyfluoroalkyl substances(PFAS)are typical organic pollutants of significant global concern.Perfluorooctane sulfonate(PFOS),its salts and perfluorooctane sulfonyl fluoride were listed in Annex B of the Stockholm Convention in 2009;perfluorooctanoic acid(PFOA),its salts and related substances were listed in Annex A of the Stockholm Convention in 2019.Perfluorohexane sulfonic acid(PFHxS),its salts and related chemicals were recommended to be listed in the Stockholm Convention in 2017 as POPs’ candidate.Due to the demands of the industry,many alternatives with similar properties to banned/restricted PFAS are continuously being developed,and these emerging PFAS have been widely detected in various environmental matrices due to their similar environmental persistence.This work mainly focused on the occurrence and spatial distribution characteristics of legacy and emerging PFAS in the eastern coastal environment of China.The results are divided into the following two parts:The contamination level and spatial distribution of legacy and emerging PFAS in marine sediments collected from the Yellow Sea and the East China Sea were studied.Nineteen PFAS were identified,with concentrations ranging from 0.21 ng/g to 4.74 ng/g(mean value: 1.60ng/g).Legacy long-chain PFAS [e.g.,PFOA,perfluorononanoic acid(PFNA)and PFOS] were the dominant contaminants.Some emerging PFAS were identified within the detection range of 16%–100%,2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)propanoic acid(HFPO-DA)was measured in all sediments in equivalent levels to PFOS(0.119 ng/g and 0.139ng/g,respectively).This is the first report to found the occurrence of perfluoro-1-butanesulfonamide(FBSA)and HFPO-DA in marine sediments,indicating a replacement in the production of PFAS from legacy to emerging ones along with eastern coastal cities of China.Source analysis based on the positive matrix factorization(PMF)model found that metal plating plants,textile treatments,fluoropolymer products,food packaging,and the degradation of volatile precursor substances were the main sources of PFAS in the Yellow Sea and the East China Sea.Preliminary environmental risk assessment results showed that PFOS and PFOA in the coastal Yellow Sea and the East China Sea had a low-to-median risk to aquatic and benthic organisms.The concentrations and compositions of legacy and emerging PFAS in surface soils collected from different functional areas(residential areas,water environment,grasslands,farmlands and other functional areas)in Tianjin were investigated.Seventeen PFAS were identified,with concentrations ranging from 0.214 ng/g to 5.35 ng/g,with an average concentration of 1.25 ng/g.The main component of PFAS in the surface soils was PFOA.6:2Cl-PFESA(<MDL–1.95 ng/g,mean 0.107 ng/g)was found in the surface soil,with slightly higher concentration than PFOS(<MDL–1.62 ng/g,mean 0.102 ng/g),indicating that 6:2 ClPFESA as a substitute for PFOS has been widely produced and used in Tianjin..Based on the positive-definite matrix factor(PMF)receptor model,the major PFAS sources was dominated by textile treatment,metal electroplating plants,and some potential precursors of PFAS with longer chains were the major sources(43.4%),followed by food packaging as well as coating materials(25.5%).Spearman correlation analysis and structural equation model analysis showed that population density has a significant impact on PFAS in the surface soil of Tianjin.