| With the quick expansion of population and rapid economic development,the energy consumption and the number of motor vehicles in Handan city have increased rapidly,and air pollution has become increasingly serious,making it the most polluted area in Beijing-Tianjin-Hebei region.In order to get the characteristics of air pollution in Handan city,this paper,based on the online monitoring air pollutant data and meteorological data in Handan city in 2013-2017 as well as PM2.5 component data in 2013 and 2017,discusses the temporal variation characteristics of air pollution in Handan city,and focuses on the characteristics of the chemical composition of atmospheric particulate matter and its correlation with meteorological factors as well as the air pollution control measures.The main findings of the study are as follows(1)In 2013-2017,the annual mean of particulate matters continued to decline in the previous four years,rebounded slightly in 2017,but remained far lower than in 2013;the annual mean of SO2 continued to decline,and the annual mean average concentration of SO2(37?g m-3)in 2017 was 61.9%lower than that of 2013(97?g m-3);the annual mean of NO2 fluctuated;the annual mean of O3 decreased first and then rose,and it was only 4?g·m-3 lower than that of 2013.The daily average fluctuation range of SO2 shrunk year by year,while the particulate matter was first expanded and then shrunk;the concentration of PM2.5,PM10 and SO2 in winter were greater than that of summer,and O3 was the opposite.PM2.5,PM10,SO2,NO2 and SO2/NO2 were negatively correlated with humidity,and PM2.5/PM10 was positively correlated with humidity.The gradient change of PM2.5 concentration in 1h and 5h can be used as an indicator to identify the explosive growth of PM2.5.Although the explosive growth in 2013-2017 had been controlled to some extent,the pollution level remained high,and the root cause was still the high emission of local pollutants.(2)The annual mean of pollutants is mainly influenced by the number of fine days,number of heavy pollution days and heavy pollution levels.Among them,the cumulative concentration of heavy pollution has the greatest influence on the annual cumulative concentration.Compared with the year of 2014,the fine days of particulate matters and SO2 increased significantly,the heavy pollution days reduced significantly,the pollution level greatly improved;however,the annual cumulative high concentration of 20%still accounted for about 40%of the total annual cumulative concentration,indicating that the emergency emission reduction actions in heavy pollution days could reduce the annual mean more effectively.Besides,the cumulative proportion in 2014-2016 rose continuously and fell sharply in 2017,indicating that emergency measures for heavy pollution had produced remarkable results.The inter-annual fluctuations of CO were small and the fluctuation trend was similar to NO2,indicating that both were greatly affected by the common source motor vehicles.(3)Organic carbon and water-soluble ions(TWSII)were the main compositions of PM2.5 in Handan city.SO42-,NO3-and NH4+(SNA)are important compositions of TWSII;for the ratio of SNA/TWSII,summer>autumn>spring>winter;SO42-concentration was the highest in winter;for the NO3-concentration,winter>autumn>spring>summer.Sulfur oxidation rate(SOR)was maximal at high temperature and humidity,and the nitrogen oxidation rate(NOR)was maximal at low temperature and high humidity.As for the ratio of[SO42-]/[NO3-],it was greater than 1 in 2013 and less than 1 in autumn and winter of 2017,indicating that SO2 was well controlled in 2017.(4)In 2013 and 2017,OC and EC concentrations were winter>autumn>spring>summer.The percent of carbon in was the hightest the whole year,the carbon fraction of biomass and coal source in PM2.5 were larger in the autumn and winter,The carbon content of PM2.5 in all seasons in 2017 was lower than that in 2013.(5)After factor analysis and enrichment factor analysis of the trace metal elements of PM2.5,the results show that the results showed that in 2013 and 2017,Zn and Pb accounted for 28.1%,55.0%,33.1%and 43.2%of trace elements respectively,and were the metal elements with the highest content;the contribution rate of primary combustion source and secondary aerosol,soil construction dust source were 29.91%,13.40%and 16.20%respectively in 2017,both lower than that in 2013;Ti,V,Sr,Ba and Ca mainly sourced from soil;Cr,Mn,Ni and K came from a mixture of crustal and artificial sources;and Cu,Zn,As,Se,Cd and Pb were typical polluting elements(6)In recent years,through coal cutting,capacity reduction,emission reduction,dust removal and other air pollution control measures,Handan city has improved air pollution level as a whole,but still significantly higher than other cities.After exploring the measures and existing problems of air pollution control in Handan city,this author believes that air pollution control should be combined with the reality,and work should be carried out from the aspects of deepening treatment of major pollution problems,optimizing urban layout and industrial energy structure,strengthening financial technical support,enforcing environmental laws strictly,improving environmental regulations and building a national participation system. |
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