Variation Characteristics And Source Apportionment Of PM_2.5 Chemical Components In Fengfeng Mining Area

With the rapid development of coal and related industries,the air quality problem in Fengfeng mining area cannot be ignored.Samples of atmospheric fine particulate matter were collected in Fengfeng Mining area from 2017 to 2019,and the chemical components of PM_2.5 were detected by photo-thermal carbon analyzer,ion chromatograph and inductively coupled plasma mass spectrometer.Meanwhile,the variation characteristics and sources of atmospheric fine particulate matter and chemical components were analyzed by combining atmospheric gaseous pollutants and meteorological data during the sampling period.The main conclusions are as follows:The PM_2.5 concentration in Fengfeng Mining area is 1.66 times of the daily average of the national secondary standard,and the PM_2.5 pollution degree decreased in 2018-2019.The peak PM_2.5 concentration was affected by winter heating,wind speed and low temperature,and all appeared in winter.The PM_2.5 concentration was positively correlated with SO₂,NO₂,CO and humidity,and negatively correlated with O₃.The concentrations of PM_2.5,SO₂,NO₂ and CO are negatively correlated with wind speed and temperature.The analysis of chemical components of PM_2.5 in Fengfeng mining area shows that the lowest concentration of total carbon（TC）during the sampling period is（10.01±2.44）μg/m³ in summer.OC concentration was the highest in winter,little difference in spring and autumn,and the lowest in summer.The concentration of EC in four seasons was low,and there was no obvious seasonal characteristics.The highest concentration of SOC in winter is 46.68μg/m³,accounting for 95%of the total.The average concentration of SOC in winter is the highest,exceeding 20μg/m³,which is 3-4 times that of other seasons.The OC/EC ratio between 1.47 and 36.74 indicates that the sources of fine particulate matter in the atmosphere are motor vehicle exhaust,coal burning and biomass burning.Ion concentration order is:NO₃^->SO₄^2->NH₄⁺>Cl^->Ca²⁺>Na⁺>K⁺>F^->Mg²⁺.SNA accounted for78.21%of the total water-soluble ion concentration,and the secondary pollution was serious.The NO₃^-/SO₄^2-values are all greater than 1,indicating that the water-soluble component of PM_2.5 in Fengfeng mining area is mainly affected by vehicle emission,and the ratio is increasing year by year.The concentration of most elements is the highest in winter,and the order of element concentration is Zn>Pb>Mn>Cr>Cu>As>Sb>Ni>Cd>Co.The sum of Zn,Pb,Mn,Cr and Cu accounts for 92.7%of the total element concentration,and As exceeds the standard by 2.26,2.85 and 1.21 times in three years,respectively.Cr exceeded 203.32,189.49 and 161.10 times.The analysis of enrichment factor and ground accumulation index shows that Cd is the primary pollution element of PM_2.5in Fengfeng mining area,and the ecological risk level is very strong.The sources of PM_2.5 in the three heavy pollution processes during the sampling period were analyzed,and the results showed that the transport was mainly influenced by the northwest and surrounding sources.Positive definite matrix factor analysis and principal component analysis were used for source analysis.The PMF analysis results were industrial source（25.208%）,coal source（24.515%）,natural source（9.033%）,dust source（8.895%）,agricultural source（7.351%）and traffic source（6.425%）.The principal component analysis results showed that,The sources of PM_2.5 in Fengfeng Mining area are mainly industrial sources,coal sources,natural sources,dust sources,agricultural sources and traffic sources.