Pollution Characteristics Of Atmospheric Particulate In Aksu City During Dust Weather

Atmospheric particulate matter has certain harm to climate environment and human health,the concentration of particulate matter will increase greatly in dust period.Aksu is located on the northwestern edge of the Taklimakan Desert,and is susceptible to the impact of sand and dust,which increases the concentration of particulate matter and deteriorates air quality.In order to understand the pollution characteristics and potential sources of atmospheric particulate matter in dust weather in Aksu city,in this study to collected PM₁₀ and PM_2.5 from two sampling sites in Meteorological Bureau and Fengquanhe Park of Aksu city from May 24,2020 to July 4,2020,combined with meteorological elements,and Correlation analys is and enrichment factor analysis were used to study the mass concentration and chemical composition characteristics of PM₁₀ and PM_2.5.Backward trajectory clustering,potential source contribution factor（PSCF）and concentration weight trajectory（CWT）were used to comprehensively analyze the main transport routes and potential source areas of PM₁₀ and PM_2.5 during dust weather in Aksu City.In order to provide a theoretic al basis for particle pollution control in Aksu city.The results of this study are as follows:（1）The daily average mass concentration of PM₁₀ at the point of Meteorological Bureau and Fengquanhe park was 893.14μg/m³ and 1010.99μg/m³ on dust day,the daily average mass concentration of PM₁₀ at two point was 151.02μg/m³ and 176.28μg/m³ on non dust day.The daily average mass concentration of PM_2.5 at the point of Meteorological Bureau and Fengquanhe park was 246.92μg/m³ and268.31μg/m³ on dust day,the daily average mass concentration of PM_2.5 at two point was 58.53μg/m³ and65.45μg/m³ on non dust day,the mass concentrations of PM₁₀ and PM_2.5 in dusty weather were higher than those in non dusty weather.The ratio of PM_2.5/PM₁₀ decreased on dusty day,and PM₁₀ was the primary pollutant.Wind speed had a significant negative correlation with the mass concentration of PM₁₀ and PM_2.5.（2）The mass concentration of water-soluble ions in atmospheric particulate matter PM₁₀ and PM_2.5 at two point in the Meteorological Bureau and Fengquanhe Park on dust day was higher than that on non-dust day,and water-soluble ions mainly existed in PM_2.5 on dust day and non-dust day.Four water-soluble ions,SO₄^2-,Ca²⁺,Cl^-and Na⁺,were the main part of sand dust day and non-dust day,which were speculated to come from natural sources.Under the influence of dust,the mass concentration of total water-soluble ions in Fengquanhe Park was slightly higher than that in Meteorological Bureau.The atmospheric particles on dust day and non-dust day was generally alkaline.（3）The mass concentrations of inorganic elements in PM₁₀ and PM_2.5 at the two sampling sites w as higher on dust day than non-dust day.The element mass concentration of Fengquanhe Park in sand-dust day was higher than that of Meteorological Bureau,and the element mass concentration of non-sand-dust day weather in Meteorological Bureau was higher than that of Fengquanhe Park.Ca,Fe,Al,Mg,Na and K were dominant on dust day and non-dust day.Crustal elements were easy to be enriched in PM₁₀,and pollution elements were easy to be enriched in PM_2.5.The results of enrichment factor analysis showed that Ca,Fe,Al,Mg,Na,K and Mn,Cu,Cr,Ni,Zn in particulate matter were mainly from natural sources,Pb and Cd greatly affected by anthropogenic source.（4）In dust weather,the air transport path of Aksu City mainly c ame from the eastern direction of Aksu,and the corresponding average mass concentration of PM₁₀ and PM_2.5 was the highest.The high concentration contribution of PM₁₀ and PM_2.5 in Aksu city was consistent with the distribution of potential source areas,mainly concentrated in Aksu area and the western region of Taklimakan Desert.The contribution to the mass concentration of atmospheric particulate matter in Aksu city was more signif icant in the east direction of the short distance transmission.Before the occurrence of dust weather,the cold air poured into the southern Xinjiang basin from west to East.There was an obvious East pouring weather in Aksu area.The ground wind direction was mainly northeast wind,and it was expected to be accompanied by dust weather to varying degrees.