| Wuhan,as a super large city in the Yangtze River Economic Belt in Central China,along with the improvement of the overall economic level and the acceleration of urbanization,the air pollution situation has changed significantly,especially now the pollution of fine particulate matter in the air is increasingly serious,which has a significant impact on the ecological environment,global climate and human health,all of which are closely related to PM2.5 concentration and its chemical components.In this paper,the atmospheric fine particles in Wuhan is taken as the research object.After medium and long-term sampling,the collected atmospheric fine particulate matter are calculated for their mass concentration,heavy metal elements are detected,and organic carbon?elemental carbon and ozone are analyzed under big data.The pollution characteristics of each chemical component,the correlation with PM2.5 and the seasonal change characteristics are discussed.Then use the PMF model to analyze the source of heavy metal elements,calculate the contribution rate of various pollution sources to the pollution of fine particulate matter.With the support of the above data,we propose targeted air pollution prevention measures to better improve the quality of the atmospheric environment,which has strong theoretical significance and practical value.The main conclusions are as follows:The study found that the change in PM2.5 concentration in Wuhan in 2019 is generally convex and concave,and the order of seasonal mass concentration is winter?151?g/m3?>spring?98?g/m3?>autumn?58?g/m3?>Summer?57?g/m3?.The seasonal mean concentrations of Ca,Fe,K,Al,Zn,Mn,Ba,Pb and Cu in the measured heavy metal elements have distinctive characteristics.The concentrations are high in spring and winter,and low in summer and autumn.For example,Ca is used as building dust and the main constituents of road dust in March and May reached the highest monthly concentrations of 3798ng/m3and 3938ng/m3,while Na,V,and Co did not meet the above seasonal rules.The annual average concentration of O3 is 111?g/m3,which is high in summer and autumn and low in spring and winter.The specific concentration is represented by autumn>summer>spring>winter.In summer,the O3concentration is at a high level and the change is not large.Moreover,the daily average concentration change of PM2.5 has a significant negative correlation with O3,and there are obvious seasonal distribution characteristics.In 2018,the concentrations of OC and EC in Wuhan basically showed a concave trend in each month of the year.In summer,the concentrations of OC,EC and TC reached the lowest values,which were 5.4?g/m3,1.4?g/m3 and 6.8?g/m3,respectively.The correlation between OC/EC in spring and winter is relatively large,which indicates that motor vehicle exhaust and coal combustion source emissions in spring and winter have a greater contribution to OC and EC in PM2.5.The PMF model was used to analyze the source of heavy metal elements in the samples.The results showed five types of sources:vehicle emissions,soil dust,biomass combustion,metal production,and chemical fuel combustion.The percentage of contribution to PM2.5 is from large to small are biomass burning?49.3%?>metal production?28.7%?>motor vehicle emissions?10.0%?>chemical fuel combustion?8.9%?>soil dust?3.0%?.Comparing the changes in source analysis results in recent years,it has been found that the contribution rate of motor vehicle pollution sources,which previously accounted for a large proportion,has decreased significantly.In this study,the metal production and biomass combustion that have contributed a lot have become the focus of governance. |
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