Study On The Pollution Characteristics Of PM_2.5 And PM₁₀ On The Ground In Sandy Days In Kashgar

As an important economic development town in the northwest border,Kashgar is located on the edge of the Taklimakan Desert.Sand and dust weather occurs frequently in spring and summer,and air pollution mainly caused by atmospheric particles is getting worse.In order to further understand the concentration levels of water-soluble ions and inorganic elements in the atmospheric particles in Kashgar and their pollution sources,this study conducted a survey of the atmosphere at the two sampling points of the West Park and the Electric Power Bureau in Kashgar from May 23,2020 to July 6,2020.Particulate matter PM₁₀ and PM_2.5 are collected on site,and the pollution characteristics of PM₁₀,PM_2.5and their chemical components are analyzed from both time and space.Using correlation analysis,enrichment factor analysis and principal component analysis（PCA）methods to analyze their main pollution sources.At the same time,the pollution characteristics of particulate matter in the occurrence of sand and dust weather are discussed.The main conclusions are as follows:（1）A comparative analysis of the mass concentrations of PM₁₀and PM_2.5at the two sampling points found that their pollution characteristics during the study period were similar and correlated well.When affected by sand and dust weather,the concentration of particulate matter increases sharply,and PM_2.5/PM₁₀decreases.Sand and dust weather is the main source of contribution to PM₁₀in the atmosphere.During the study period,other meteorological factors except temperature have little effect on the level of particulate pollution,and it shows that PM_2.5is more susceptible to the influence of meteorological factors.（2）During the study period,the mass concentration of total water-soluble ions in PM₁₀in the study area of Kashgar City was relatively high,and the proportion of water-soluble ions in PM_2.5was relatively high,and the proportion of water-soluble ions in the particles at the power bureau site was higher than that at the park site,and the average mass concentration All showed:SO₄^2->Ca²⁺>Na⁺>Cl^->NO₃^->K⁺>NH₄⁺>Mg²⁺>F^-,SO₄^2-、Ca²⁺、Na⁺and Cl^-accounted for the main part.The difference between the two sampling points is that the proportion of water-soluble ions from natural sources in the particles in the park is relatively high,and the alkaline is relatively strong,while the proportion of ions from man-made sources at the power bureau in residential areas is relatively high.It shows that the locations of urban power bureaus are more susceptible to human activities.The PCA results of water-soluble ions in Kashgar City showed that soil and building dust contributed the most to water-soluble ions,followed by traffic pollution sources.（3）During the study period,the total mass concentration of 14 inorganic elements in the particles in the West Park and Power Bureau of Kashgar City accounted for 27.14%and 31.85%of the PM2.5 mass concentration,and 19.40%and 24.51%of the PM₁₀mass concentration.Ca,Na,Fe,Al,Mg,K,and Zn are the main elements,and the concentration sums up to more than 97%of the total element concentration.The differences in different locations are as follows:the concentration of crustal elements in the park is higher,the concentration of trace elements in the power bureau is higher,and the human pollution at the power bureau in the urban area is the most serious.When affected by sand and dust weather,the mass concentration of inorganic elements in particles is much higher than that on non-dust days,and the mass concentrations of Na,Ca,Fe,Al,and Mg elements show greater fluctuations.Further comprehensive correlation analysis,enrichment factors,and principal component analysis analyzed the pollution sources of inorganic elements in particulate matter in the study area and found that the main contribution source of inorganic elements in PM_2.5and PM₁₀in Kashgar during this period was the source of soil dust.（4）The human health risk assessment of heavy metals in PM_2.5in this study area was carried out,and different populations in Kashgar were exposed to 9 kinds of heavy metal elements（Mn,Cr,As,Fe,Pb,Zn,Cd,Cu,Ni）found that none of the 9 heavy metals in PM_2.5during the study period had a non-carcinogenic risk.The carcinogenic risks of the four carcinogenic elements are all within the human body’s tolerance range,of which Cd and Ni have the lowest carcinogenic risks.The non-carcinogenic risk value（HQ）and carcinogenic risk value（Risk）of exposure to different groups of people through the respiratory route both showed children>adult men>adult women.