Analysis Of Air Quality And PM_2.5 Pollution Characteristics And Sources In Taiyuan City

Air quality problem mainly caused by PM_2.5 pollution has seriously affected the economic and social development and people's daily life in Taiyuan.In order to analyze the present situation of air quality and the pollution characteristics and sources of PM_2.5 in Taiyuan.Based on the air pollutant(PM10,PM_2.5,SO2,NO2,O3,CO)data,meteorological data and PM_2.5 sampling and analysis data,this study studied the temporal and spatial variation of air quality and its correlation with meteorological factors in Taiyuan from 2016 to 2017.Analyzing heavy polluted weather in Taiyuan from 2016 to 2017,clarifying pollution types and analyzing pollution process;studying pollution characteristics of water-soluble ions,TOC and inorganic elements of PM_2.5 in Taiyuan;combining source analysis model and Traj Stat software,analyzing the source and transmission path of PM_2.5.The main results are as follows:1.The results of air quality analysis show that particulate matter(PM_2.5 and PM10)is the most heavily loaded air pollutant in Taiyuan from 2016 to 2017,while the problem of ozone pollution is becoming increasingly prominent;SO2 and particulate matter in heating period of 2017 are significantly reduced compared with the same period of 2016,and the implementation effect of winter prevention is remarkable;the air quality of Taiyuan has obvious difference between the north and the south,the air quality of Xiaodian,Jinsheng and Jinyuan in the south was poor,pollutants in the Jiancaoping and Taoyuan were clustered into one group.The results of correlation analysis of pollutants with AQI and meteorological factors from 2016 to 2017 showed that O3 was negatively correlated with AQI and atmospheric pressure,positively correlated with temperature,wind and visibility?**p<0.01?;other pollutants except O3 were positively correlated with AQI?**p<0.01?,negatively correlated with visibility and wind?**p<0.01?.2.The results of heavy pollution process analysis show that the weather situation of accumulative heavy pollution is windless and the relative humidity is relatively high.The air mass mainly comes to Jinzhong and Lvliang,and the main pollutant is PM_2.5.The dust-type heavy pollution is mainly affected by Mongolia high pressure,and the air mass mainly comes from the arid areas of Mongolia.The Ca2+ proportion in PM_2.5 increases,and the air representative pollutant is PM10.O3 heavy pollution is closely related to meteorological factors of high temperature and low humidity.The heavy pollution during the Spring Festival is mainly related to the transportation of fireworks and firecrackers in surrounding cities and counties.3.The results of principal component analysis of PM_2.5 show that SO42-,NH4+ and NO3-?SNA?are relatively high,accounting for 81% of total water-soluble ions?TWSI?;NH4NO3,?NH4?2SO4 are the main binding states of NH4+ in PM_2.5;CE/AE is 1.1439 > 1,which is lower than that of CE/AE in 2012,SO42-and TWSI in PM_2.5 have decreased significantly in recent years,indicating that the winter control measures in Taiyuan City had achieved remarkable results.The contents of Fe,K,Na and other elements in PM_2.5 are high,the contents of heavy metals are low,while the potential ecological risk is very strong,especially Cd and Hg;the carcinogenic heavy metals in PM_2.5 have no obvious carcinogenic risk.4.Source analysis results of PM_2.5 show that the enrichment factors?EF?of Cd,Pb,Zn,Hg,Cu and As are more than 10,mainly from anthropogenic emissions;PCA analysis shows that the main sources of PM_2.5 heavy metals are coal combustion and industrial emissions and soil dust;water-soluble ions are mainly from secondary sources,coal and biomass combustion and dust;backward trajectory cluster analysis shows that the 500 m high-altitude air mass in Taiyuan City mainly comes from the west.Potential source analysis shows that the heavy pollution grids are mainly located in the southern Shanxi and Guanzhong areas of Shaanxi Province,and WPSCF in Lvliang and Jinzhong areas is generally greater than 0.4 in winter.Regional transport contributes greatly to PM_2.5 concentration in Taiyuan.In summary,the winter prevention measures in Taiyuan City have achieved remarkable results.Particulate matter pollution load has been reduced,but the problem of O3 pollution has become prominent,which should be paid great attention to.Heavily polluted weather in Taiyuan is greatly affected by meteorological conditions and regional transmission.It is necessary to jointly control with surrounding cities and counties to reduce pollutant emissions.SNA is the main component of PM_2.5,the content of Cd and Hg is low,while the ecological risk is very strong.It is suggested to strengthen the control of the above pollutants.