| Zhengzhou,as the capital of Henan Province,is located in the central part of Henan Province.It is a mega-city and the central city of the Central Plains.Besides,it is one of the areas with serious PM2.5 pollution in China.In this study,PM2.5 particles in Zhengzhou in 2018 were analyzed from pollution characteristics,components and main sources.At the same time,receptor model technology was used to analyze the causes of air pollution in Zhengzhou in 2016 and 2018 from multiple perspectives,and the sources of various pollutants were analyzed.To provide the basis for the compound air pollution prevention and control measures in Zhengzhou.Finally,the change trend of particulate matter,gaseous pollutants and source analysis was compared between 2016 and 2018,so as to explore the change of pollution characteristics and trends in Zhengzhou,and provide suggestions for comprehensive prevention and control of air pollution in Zhengzhou.Firstly,the PM2.5 component characteristics and reconstruction in Zhengzhou in 2018 and 2016 were analyzed.PM2.5 showed a decreasing trend in 2018,with the largest decline in winter,and the air quality improved significantly.The results of component analysis showed that NO3-,SO42-and NH4+ of water-soluble ions accounted for 50%of PM2.5 concentration in 2018,and water-soluble ions decreased by 15.34 μg/m3 in 2018 compared with 2016.The EC concentration in 2018 was 0.8μg/m3 lower than that in 2016,but the SOC concentration in 2018 was higher than that in 2016,and the value of OC/EC also showed an increasing trend,which still needed to strengthen the control of the use of fossil fuels.Moreover,there was a significant correlation between OC and SOC in 2018 and PM2.5 in winter(r>0.85).The results showed that the secondary organic reaction of OC had a great influence on the winter of 2018.Compared with 2016,the total element concentration decreased slightly in 2018,but the proportion of S element was as high as 35.5%.According to the reconstruction results,the total proportion of organic matter and nitrate in 2018 was 53.9%,higher than 15.2%in 2016,and the proportion of secondary inorganic salts in 2018 was as high as 45.3%.Therefore,the air pollution in Zhengzhou was mainly affected by secondary inorganic salts.The results of source analysis showed that secondary pollution in Zhengzhou had the largest impact on PM2.5 in 2016,accounting for 36.8%,followed by biomass combustion sources(18.28%),traffic sources(14.03%),industrial combustion sources(13.21%)and dust sources(11.03%),and power plants accounted for the least 6.64%.In 2018,the PM2.5 in Zhengzhou was mainly from combustion sources(37.0%),followed by industrial combustion sources(16.4%).NOx was greatly affected by vehicle emissions(69.4%),and industrial combustion was the second largest contribution source(23.2%).The sources of SO2 and CO are mainly>combustion source>motor vehicle emissions.By comparing primary sources in 2016 and 2018,the results show that PM2.5 mainly comes from comprehensive coal burning;The source of NOx was transferred from power plant emission to traffic emission.The contribution of CO to industrial combustion sources decreased by 36.0%;In 2016 and 2018,SO2 mainly came from industrial combustion sources and combustion sources,so combustion emissions were an important direct cause of air pollution in Zhengzhou. |
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