| By the continuous development of economic condition,atmospheric environmental problemshave become increasingly prominent and lead to an increase in domestic and transregional atmospheric particulate matter including PM2.5 and PM10.In order to understand the variation characteristics and pollution sources of air pollutants in the main urban area of Xinxiang City,atmospheric particulate matter including PM2.5,PM10 and also corresponding gaseous pollutants and meteorological data were collected.Based on one year'monitoring data collection,the temporal variation characteristics of atmospheric pollutants concentrations in the main urban area ofXinxiang City were considered,and the meteorological factors affecting their concentrations were studied.Furthermore,the pollution concentration levels and temporal variation characteristics of water-soluble inorganic ions in PM2.5 and PM10 were evaluated.Principal component analysis?PCA?was used to investigate the sources of water-soluble ions in PM2.5 and PM10particles,and also the pollution status of particles in heating period was analyzed.Multiple stepwise regression method was applied to establish the regression model between PM2.5,PM10 and the environmental factors.Some major findings of this study are as follows:1.SO42-,NO3-and NH4+were the main water-borne ions in PM2.5 and PM10,and their combinedratio accounts for 85%and 81%of the total water-soluble ions in PM2.5 and PM10.The water-soluble ions SO42-,NO3-,and NH4+mostly by its gaseous precursors derived by photochemical reaction,and serious secondary pollution of atmospheric particulates in the main urban area of Xinxiang City.In PM2.5 and PM10,NH4+was highly correlated with NO3-and SO42-,and ammonium salt may exist in the forms of NH4NO3,?NH4?2SO4,NH4HSO4,and NH4Cl.The average annual ratios of NO3-and SO42-in PM2.5 andPM10 were1.09 and 1.07,respectively.These results indicated that the contribution of mobile sources to PM2.5 and PM10 was similar to that of fixed sources,and the contribution of fixed sources was more prominent in summer,while the contribution of mobile sources was more obvious in winter.The sources of atmospheric particulate matter in spring and summer,it mainly comes from the conversion and dust of secondary ions.In winter,it mainly comes from secondary pollution sources and combustion sources?e.g.vehicle and industry?.In autumn,it is dominated by dust sources and agricultural sources.2.Air particle pollution was serious during heating period in the main urban area of XinxiangCity.The daily average concentration of PM2.5 and PM10 was 101.00 g·m-3 and 175.27 g·m-3,respectively,and exceeded the standard by 1.35 times and 1.17times,respectively.The diurnal variation of PM2.5 and PM10 was characterized by weak double-peak and single-valley,and the peak concentration appeared at10:00 and 22:00.The sulfur oxidation rate?SOR?and nitrogen oxidation rate?NOR?were high of PM2.5and PM10,indicating that the secondary pollution was relatively serious in the heating period in the main urban area of Xinxiang City.The main sources of atmospheric particulate matter were combustion,industrial,secondary conversion,and dust sources in the heating period in the main urban area of Xinxiang City.3.The northeast wind and southwest wind were the prevailing wind direction in the main urbanarea of Xinxiang City.The correlation analysis of PM2.5 and PM10 with meteorological factors:shows that temperature,air pressurerelative humidity,and average wind speed will affect the mass concentration of PM2.5 and PM10 in the main urban area of Xinxiang City.The stepwise regression result showed that temperature and wind speed were the main factors affecting the concentration of PM2.5 and PM10.4.In addition to the annual average concentration of SO2,CO and ozone on the maximum 8hours of air pollutants in the main urban area of Xinxiang City,the annual average concentrations of the remaining atmospheric pollutants NO2,PM2.5 and PM10 exceed the national ambient air quality level.The standard concentration limits are specified to exceed 1.3,1.9 and 1.8 times,respectively.In 2017-2018,the proportion of PM2.5in the main urban area of Xinxiang City to PM10 varies from 0.40 to 0.72,and the seasonal change is winter?0.58?=summer?0.58?>autumn?0.56?>spring?0.45?.The main factor causing particulate matter contamination is fine particulate matter(PM2.5). |
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