Pollution Characteristics And Source Apportionment Of PM_2.5 And PAHs In Taiyuan City

The atmospheric fine particle pollution is a threat to eco-environment and human health,which is why the research on the features of urban atmospheric PM_2.5 pollution and its impact on human health is important.Since it became one of cities affected by the atmospheric pollution spreading from Beijing?“ 2+26 ”?,Tianjin,and Hebei in 2017,Taiyuan has taken rigorous measures to control emissions,which have improved its air quality.This study collected monitoring data of atmospheric pollutants(PM_2.5,PM10,SO2,NO₂,CO,and O3)and meteorological parameters from September,2018 to August,2019 and sampled PM_2.5 in different seasons.The temporal and spatial distributions of PM_2.5 and its correlations with other pollutants and meteorological factors were analyzed.The PAHs pollution level in PM_2.5,its source and impact on human health were further analyzed.The study draw the following conclusion:?1?the average annual PM_2.5 mass concentration in Taiyuan is56.67±42.16 ?g/m3 and its seasonal distribution is winter?91.34?g/m3?>autumn?51.81 ?g/m3?>spring?50.72 ?g/m3?>summer?33.49 ?g/m3?;an analysis of correlations between PM_2.5 and other atmospheric pollutants and meteorological factors indicates a positive correlation?p<0.01?between PM_2.5 and PM10,SO2,NO₂,and CO in four seasons and a negative correlation?p<0.01?between PM_2.5 and O3 in autumn and winter.In spring and winter,PM_2.5 is susceptible to meteorological factors such as humidity,solar radiation,evaporation,and air pressure?p<0.01?.Besides,in summer and autumn,PM_2.5 is remarkably correlated with temperature?p<0.01?.?2?From January 2 to 13,2019,the heavy pollution was dominated by PM_2.5,followed by PM10 and NO₂.The correlation between PM_2.5 and temperature,humidity,and wind speed was remarkable?p<0.01?.According to a meteorological analysis,cold air carrying vast particles moved from the north to the south at the beginning of the pollution and then was in staticstability that caused pollutant accumulation at the end of the pollution.According to a backward trajectory analysis,air mass arrived in Taiyuan via Inner Mongolia,and Shaanxi and carried 152.39 ?g/m3 of PM_2.5 and240.68 ?g/m3 of PM10.?3?During the study,the annual average of USEPA's 16 priority pollutant PM_2.5-bound PAHs in Taiyuan was 27.2 ng/m3 with a regularity of winter?65.64 ng/m3?> autumn?18.44 ng/m3?> spring?11.42 ng/m3?>summer?6.18 ng/m3?.In four seasons,Bbk content was high and HMW,the predominant component of PM_2.5-bound PAHs,accounted for 43%-49%.Carcinogenic PAHs had a high percentage of 50% and above in all the four seasons.?4?Principal component analysis and PMF model analysis of the source of PAHs in PM_2.5 points out that traffic emission sources and coal combustion sources are their main sources.The result of the PM_2.5-bound PAHs source analysis by characteristic ratio indicated that biomass,coal burning,and vehicle emissions were contributors in four seasons.Besides,oil burning and leakage was a contributor in spring,autumn and winter.In terms of space,PSCF and CWT showed that areas south of Taiyuan exerted a great influence in summer and Taiyuan and its northwest were major influence factors.?5?The health risk evaluation showed that PM_2.5-bound PAHs intake and skin exposure have a cancer risk that is nearly 105 times higher that of inhalation.Children have a higher cancer risk associated with PAHs intake than that of adults while adults have a higher cancer risk associated with PAHs skin exposure and inhalation than that of children.An analysis on three?ILCR exposure channels found that children and adults have a cancer risk in autumn and winter.Children's cancer risk associated with PAHs is higher than that of adults while adults' cancer risk associated with PAHs skin exposure and inhalation is higher than that of children.An analysis on three?ILCR exposure channels found that children and adults have a cancer risk in autumn and winter.