Occurrence Of Per- And Polyfluoroalkyl Substances (PFASs) In Chinese Specific Regions

Perfluoroalkyl and polyfluoroalkyl substances?PFASs?are a class of synthetic pollutants with strong persistence in the environment and a relatively high solubility and polarity.The South China Sea is adjacent to the Pearl River Delta,one of the most developed regions in China.However,there is no report on the vertical distribution of PFASs in the South China Sea,and there is no report on the occurrence of the novel PFASs in the South China Sea.PFASs is widely used as a surfactant in ski wax.The Winter Olympic Games will be held in Beijing in 2022.With the approaching of the Winter Olympic Games,the scale of skiing activities in the northern China is increasing.However,the environmental behavior of PFASs around ski resorts in China has not been reported yet.The filter effect of forests on tranditional nonpolar persistent organic pollutants,such as polychlorinated biphenyl?PCBs?and polycyclic aromatic hydrocarbons PAHs have been widely accepted and verified by experiments,however,the report about the impact of forests on PFASs was scarce.The Three Northern Shelter Forest covers 42.7%of China's land area but there is no report on the occurrence of PFASs in this region.To fill the above knowledge gaps,the following work has been done in this study:1.Surface seawater,bottom seawater,and surface sediments were collected in the coastal region of the South China Sea.2.Air and needle samples were collected every two months around six ski resorts in Shenyang and Zhangjiakou while snow,soil and ski wax were collected in winter.Urban and background sampling sites were also set for comparison.3.Air and leaf samples were collected every two months inside and outside of poplar and pine forests in Zhangbei and Zhangwu Country while soil samples inside and outside the forest were collected in summer.Levels and composition of 27targeted PFASs were analyzed in these samples.After the analysis work,the data were compared and discussed with the literature.The main conclusions are as follows:?1?Concentrations of PFASs in surface water,bottom water and sediments of the South China Sea ranged from 19.0 to 18.9×10³ pg/L,38.0 to 779 pg/L and 7.50 to 84.2 pg/g dry weight,respectively.Novel PFASs,e.g.,6:2 chlorine-polyfluorinated ether sulfonate?Cl-PFESA?were detected in seawater and sediment of the South China Sea for the first time.The dominant pollutant in seawater was perfluorobutanoic acid?PFBA?,while perfluorooctane sulfonic acid?PFOS?dominated in the sediment.The insufficient mixing of seawater led to significantly higher concentration of PFASs in surface seawater than that in bottom seawater.The influx of rivers and the movement of ocean currents had a great influence on the spatial distribution of PFASs in seawater.Higher concentrations of PFASs appeared in the sampling sites near Modaomen and Yamen estuaries,and a decreasing trend was found with the increasing distance from the shore.The concentrations of PFASs in west Lingdingyang bay were higher than those in the eastern.Preliminary environmental risk assessment results showed that PFOS in the coastal South China Sea had a moderate risk to aquatic and benthic organisms,while other PFASs had no impact on aquatic and benthic organisms.?2?Concentrations of ionic and neutral PFASs in the atmosphere around the ski resort ranged from 1.12 to 34.0 pg/m³,and 170 to 437 pg/m³,respectively.Levels of PFASs in the atmosphere around the ski resort were lower than the city but higher than the background sites.Perfluorooctanoic acid?PFOA?and 8:2 fluorotelomer alcohol?FTOH?were the dominant PFASs,and long-chain PFASs were widely detected.The concentrations of ionic PFASs in pine needles ranged from 283 to 3.34×10³ pg/g dry weight,while 8:2 FTOH was the only detected neutral PFASs with an average concentration of 982 pg/g dry weight.Higher levels of PFOA and long chain PFASs?C>10?in the atmosphere were found around the ski resort during the peak season?November to March?than the slack season?March to November?,which indicates that skiing activities caused the release of PFASs to the surrounding environment.The concentrations of ionic PFASs in pine needles did not vary greatly with the season,showing relative stability.However,influenced by skiing activity and temperature,significantly higher levels of 8:2 FTOH were found in the peak season than the slack season.For most PFASs,the accumulation factors?AF?were higher than 1,which indicated the bioaccumulation.When compared with Shenyang,the contribution rate of PFASs released by skiing activities during winter in Zhangjiakou was higher.PFASs in the snow was one of the main sources of PFASs in the soil.?3?The concentrations of ionic and neutral PFASs ranged from 1.12 to 17.1 pg/m³ and 17.5 to 112 pg/m³ in the shelter forest region,respectively.PFBA,8:2 FTOH were the dominant pollutants,and the concentration of neutral PFASs were higher than that of ionic PFASs.The concentration of PFASs in the atmosphere of shelter forest in Shenyang was higher than that in Zhangjiakou.Generally,the ratios of levels of PFASs in the air outside and inside the forest(Q_OI)were greater than 1,which indicates that shelter forest played a role in removing PFASs from the air.The values of Q_OI of poplar forest were close in winter and summer,while the Q_OII of pine forest in winter was higher than that in summer.The temperature in winter is low,and neutral PFASs were more easily distributed to pine needles,which resulted in the enhancement of the removal ability of neutral PFASs.The concentrations of PFASs in poplar leaves ranged from 101 to 877 pg/g dry weight,and the concentrations increased with the growth.The concentrations of ionic PFASs in pine needles ranged from 686 to 933 pg/g dry weight,which were stable during different seasons.The concentration and composition of the ionic PFASs in pine needles in Shenyang and Zhangjiakou was similar.The composition of PFASs in poplar leaves was similar to that in pine needles.PFBA and 8:2 FTOH were the dominant pollutants.Only ionic PFASs were detected in soil.The average concentration of PFASs in the soil from the inside shelter forest was 125 pg/g dry weight,while that in outside forest was 504 pg/g dry weight.The retention effect of shelter forest on PFASs in the atmosphere made the concentrations of PFASs in the soil from the inside forest lower than the outside forest.