Contaminant Characteristics Of Perfluorinated Compounds In Atmospheric Of Typical Cities

Perfluorinated compounds(PFCs)are a class of organic compounds in which all hydrogen atoms on carbonchain are substituted by fluorine atoms and have been applied broadly to various kinds of industrial and commercial products due to their remarkable thermal stability,surfactant properties and frequent occurrence in various environmental matrices.PFCs can enter the atmosphere during volatilization from water bodies and soils in areas where PFCs were used or deposited,and are subject to long-range atmospheric transport.Semi-volatile PFCs precursors can be degraded into PFCs.Numerous studies have reported on the sources and atmospheric chemistry of semi-volatile PFCs precursors,but only a few studies have reported on the atmospheric occurrence of PFCs.Seventeen perfluorinated compounds(PFCs)were quantified by ultrasonic extraction,high performance liquid chromatography and tandem mass spectrometry(HPLC-MS/MS)to study the level and distribution of PFCs in atmospheric particle amples in Beijing and surrounding cities,Jiangsu fluorochemical park and surrounding cities.In addition,the occurrence of perfluorinated compounds(PFCs)in 36 precipitation samples were determined.The aim of this study was to investigate the occurrence and distribution of PFCs of atmospheric particle phase and precipitation in the research areas.This paper also briefly deduces the possible source of PFCs and estimates the risk assessment of PFOS and PFOA.Major results are as fllows:(1)The 13 PFCs were detected in rain water samples in Beijing.The∑PFCs concentrations were between 0.23 and 62.4 ng/L,while PFOA was the predominant compound.Due to the abundant rainfall in Beijing in 2018,the level of∑PFCs in rain water samples of Beijing in 2018 was much lower than that in 2019.The possible sources of PFCs in rainfall are the oxidation of precursor chemicals in the atmospheric and the escape from WWTPs as anions in aqueous aerosols and subsequently partition to the gaseous phase in their neutral form.Higher fluxes of perfluorobutanoic acid(PFBA)were detected in precipitation in Beijing in 2019(average:168 ng/m~2),which may reflect the current shift to short-chain PFCs and/or their precursors.(2)The target PFCs were found in the atmospheric particle amples in Beijing,Cangzhou and Zhangjiakou,and perfluorooctanoic acid(PFOA)was the dominant PFCs in the samples.The mean concentration of∑PFCs in atmospheric particle amples in Cangzhou was 202 pg/m~3,which was higher than those characterized in Beijing(mean:23.3 pg/m~3)and Zhangjiakou(mean:1.17 pg/m~3).The levels of PFCs in the atmosphere are probably associated with industrial activities and weather conditions.The concentration of PFCs in atmospheric particle phase in Beijing may be affected by the atmosphere from Cangzhou.The PFCs were predominantly observed in the fine particle-size fraction sampled in this study(<2.5μm),while the maximum PFOA mass fractions appears to be found in particle sizes fraction of 1.4～2.5μm.(3)The average∑PFCs concentration in the particle phase of the atmosphere in the fluorochemical park was 248 pg/m~3,which is higher than that in Yushan Town District,Changshu(average:76.2 pg/m~3),Zhangjiagang City(average:53.8 pg/m~3)and Taicang City(average:22.2 pg/m~3),and PFOA was the dominant PFCs in the samples.There is no significant correlation between the concentration of∑PFCs and the distance from the sampling site to the fluorochemical park.The air mass trajectories indicating the air mass of Taicang,Zhangjiagang and Yushan Town District,Changshu were from many regions,including the fluorochemical park.(4)A preliminary environmental health risk assessment indicated that the PFOA and PFOS in the particle phase of the atmosphere in the study areas may pose no or immediate threat to the residents.