Distribution Characteristics,cause Analysis And Health Risk Assessment Of Ambient Air VOCs Pollution In Alar City

In the last few years,most cities in China are facing increasingly serious ozone pollution.The concentration levels of particulate matter and O₃ in the atmosphere in southern Xinjiang show signs of rising,but the research on its precursor volatile organic compounds（VOCs）has not been reported.In this study,volatile organic compounds（VOCs）in the atmospheric environment of alar city were taken as the research object.Using tank sampling atmospheric preconcentration gas chromatography-mass spectrometry and tank sampling preconcentration gas chromatography-mass spectrometry,VOCs samples in the atmosphere were collected and analyzed for one year from March 2021 to February 2022.Combined with the local meteorological conditions and surrounding environment,the concentration,pollution level and time distribution characteristics of volatile organic compounds in the atmosphere of alar city are analyzed;By analyzing OFP and SOAFP the formation potential of ozone and secondary aerosol under the pollution concentration level is studied;The ratio method and orthogonal matrix factor model（PMF）are used to identify the main sources of VOCs in Alar City.The movement trajectory of air mass during observation is simulated by Meteoinfo software,and the subsequent trend is predicted by using potential source contribution function（PSCF）and concentration weighted trajectory（CWT）;Finally,the potential risks to human health posed by certain toxic and harmful VOCs species were analysed by combining the Monte Carlo simulation with health risk assessment methods recommended by the United States Environmental Agency.Important findings are as follows:（1）Annual average concentration of TVOC in the atmospheric environment during the study period was 268.02μg/m³,from high to low,the proportions of various types are alkanes（51.24%）,olefins（14.23%）,halogenated hydrocarbons（12.36%）,OVOCs（10.26%）,aromatic hydrocarbons（10.19%）and alkynes（1.71%）.There are obvious seasonal differences:Autumn（337.88μg/m³）>winter（320.32μg/m³）>summer（251.75μg/m³）>spring（167.79μg/m³）。The concentration change in special period is generally manifested in heating weather（338.27μg/m³）>non heating weather（267.98μg/m³）>heavily polluted weather（217.60μg/m³）>fine weather（166.29μg/m³）>polluted weather（116.43μg/m³）>dust weather（77.81μg/m³）。（2）During the observation period,the total value of OFP of VOCs in the ambient air of alar city was327.15(10^-9),and the total value of LOH was 511.15(s^-1).The generation potential of SOA is 1.49μg/m³,in which alkanes are 0.0965μg/m³,olefin 0.0377μg/m³,aromatic hydrocarbon 1.3544μg/m³。（3）The ratio analysis shows that VOCs in Alar City are more affected by foreign transmission sources than local pollution sources,and belong to the synergistic impact of vehicle tail gas source,traffic source and oil and gas use.PMF model is used to analyze the five pollution factors.The contribution rate of coal-fired sources to TVOCs in Alar City is the highest（36.0%）,Followed by the use of LPG/natural gas（9.4%）,automobile exhaust emission sources（20.2%）,industrial sources（14.7%）and solvent sources（19.7%）.（4）The backward trajectory,potential source contribution function（pscf）and concentration weighted trajectory（CWT）are simulated by Meteoinfo software.The analytical results are as follows:there are external potential sources of VOCs in different degrees in the observation process,which belongs to medium and long-distance transmission,but the impact of short-distance transmission is greater.（5）Toxic and harmful VOCs in the atmosphere in Ararat have a range of 0.01-2.37 with an average HI of 4.14,indicating a potential non-carcinogenic risk of VOCs in Alar.Benzene,1,2-dichloroethane and1,2-trichloroethane and trichloroethylene are the most hazardous VOCs in the atmospheric environment in the city of Ararat.Risk values of 1.26 E-04,7.47 E-04,1.61 E-04,1.85 E-05 indicate a potential carcinogenic risk for VOCs in the city of Alar.In conclusion,the results of this study can provide scientific basis and reference for analyzing the current situation and pollution characteristics of VOCs in southern Xinjiang,reducing VOCs emission,improving air quality and formulating air pollution prevention and control measures.