Study On Physical And Chemical Properties Of Atmospheric Aerosols Along The Silk Road In Gansu And Xinjiang

With the rapid development of social economy and people's living standards,the atmospheric environment is undergoing fundamental changes.Pollution problem has aroused the great concern of the governments all over the world.In ancient time,the land Silk Road made an important contribution to the transmission of property and cultural exchanges between China and other countries.The areas along the Silk Road have important geographical advantages,abundant natural resources and broad prospects for development,the relevent countries have put forward strategic ideas aimed at this region in recent years,and China has also put forward the concept of the"Silk Road Economic Belt".The observation of atmospheric aerosols in this area can understand the atmospheric environment of the major cities and improve the living environment quality of the residents along the route.More importantly,the research can provide scientific basis for improving the quality of living environment of the residents in these areas and formulating the policies of air pollution prevention and remediation in line with the economic development strategy.In this paper,the main cities and counties along the Silk Road?including Lanzhou,Jinchang,Yumen,Hami,Urumqi,Karamay,Altai?were observed and sampled.Based on the physical and chemical characteristics of aerosols,the characteristics of physical and chemical,diurnal and seasonal variations,formation mechanism and transmission path of atmospheric aerosols are analyzed and discussed.We find the following points:?1?In spring air pollution of main cities along the Silk Road was dominated by PM₁₀,and the concentration of particulate matter decreased with the decrease of particle size.According to the geomorphologic unit,the sampling sites are divided into three areas:Hexi Corridor area,Tianshan area and Altai area,under the influence of local geological environment and wind direction,the concentration of particulate matter decreases from southeast to northwest.In most urban areas,daytime concentrations were greater than night concentrations due to daytime human activity,but the daytime concentrations in Hami and Urumqi were lower than night.?2?Water-soluble ions can reflect the influence of industrialization and economic development level on the local atmospheric environment under the natural background.The concentration of water-soluble ions in Jinchang was the highest in PM₁₀ and PM₁,mainly Ca²⁺,SO₄^2-and Cl^-.The concentration of water-soluble ions in Urumqi was the highest in PM_2.5,mainly SO₄^2-and NO₃^-.The main ions in atmospheric environment of other sampling points were Ca²⁺and Na⁺.The results show that the artificial pollution in Urumqi is serious and the pollution is enriched in fine grains,Jinchang and Yumen are affected by both natural and man-made factors,and other sampling areas are mainly influenced by nature factor.?3?The air pollution in Lanzhou city is mainly particulate matter pollution(PM₁₀)and gas pollution?O₃,NO₂?.The environmental quality in suburb is better than urban.The annual variation trend of six pollutants is"U"type.For the intradiurnal variation trend,PM₁₀ and PM_2.5are double peaks and O₃ are single peaks.In spring the pollution sources are mainly Inner Mongolia and Gansu.In summer the pollution source is concentrated in the eastern part of Gansu province.In autumn the pollution source of PM₁₀ is consistent with desert distribution in Mongolia and Gansu,the source of NO₂ decreases gradually with Lanzhou as the center.In winter,the pollution sources concentrated in Lanzhou and Baiyin.?4?The main ionic components of aerosol in Lanzhou is NO₃^-,SO₄^2-,Ca²⁺,NH₄⁺.The highest concentration of ions occurs in winter.NO₃^-is the most important ion in winter,and the other seasons are Ca²⁺.Through the study of secondary ion transformation,it is found that the conversion rate of SO₂ is higher than NO₂,the variation trend of SOR is similar with relative humidity,and the variation trend of NOR is opposite to temperature.Stationary source is the main source of man-made pollutants in Lanzhou city,and the contribution of mobile source is higher than other cities.The analysis indicates that Lanzhou should strengthen the control and prevention of inhalable particulate matter,and pay attention to the influence of coarse particulate matter on the atmospheric environment.