Identification Of Transport Pathways And Potential Source Regions Of Particulate Matters In The Eastern Pamirs

In this paper,based on the data of particulate matter（PM）in the Pamirs and the Kashgar environmental monitoring stations,the characteristics of PM pollution in Kashgar and the eastern Pamirs from March 2019 to February 2020 were analyzed at the same time,to explore the relationship between atmospheric particulate matter in plain and plateau of southern Xinjiang.The correlation between PM concentrations and meteorological parameters in the eastern Pamirs was analyzed by using mathematical statistics.In the Hybrid Single-Particle Lagrangian Integrated Trajectory（HYSPLIT）backward trajectory,cluster analyses,potential source contribution function（PSCF）and concentration-weight trajectory（CWT）were used to identify the transport pathways and potential source areas with hourly atmospheric particulate matter concentrations in different seasons in the eastern Pamirs.In order to provide scientific reference for scientific and effective prevention and control of atmospheric particulate matters and numerical simulation of pollutant cross-border transport process in plateau areas of China.The main research achievements of the thesis were as follows:（1）The daily mean concentrations of PM₁₀,PM_2.5and PM₁of the eastern Pamirs were（29.4±16.4）and（9.3±5.1）μg/m³,respectively.The two concentrations were respectively 26.5%and 38%lower than the annual average first-level concentration limit in the"Ambient Air Quality Standard"（GB 3095-2012）.The annual mean concentrations of PM₁₀and PM_2.5of Kashgar were（211.2±210.2）and（85.3±72.6）μg/m³,respectively.The concentrations of the two were 3 times and 2.4 times the annual average value in the air quality standard respectively.The annual average concentrations of PM₁₀and PM_2.5of Kashgar were 7.2 and 9.2 times higher than those in the eastern Pamirs,respectively.The concentrations of atmospheric particles in the plain areas were much higher than the plateau areas.（2）The correlation study showed that the distribution trend of PM_2.5and PM₁₀daily mean concentrations in the eastern Pamirs and Kashgar were highly correlated,and the main sources of PM_2.5and PM₁₀were similar.The annual PM_2.5/PM₁₀of the eastern Pamirs and Kashgar were 0.32 and 0.45,respectively,which indicated that PM₁₀was mainly composed of particulate matter in plain and plateau areas,and the values of PM_2.5/PM₁₀in the two regions were the lowest in spring,which indicated that the sand dust impact was the most serious in spring.（3）The analysis of backward trajectory clusters and potential source regions showed that the distribution characteristics of four season average trajectory in eastern Pamirs correspond to the synergy of westerly monsoon,and the distribution of potential source regions of PM₁₀were similar to PM_2.5.In spring,the westerly flow through Central Asia were the dominant flow,corresponding to the high concentration of atmospheric particulate matter,the contribution ranges of PM₁₀and PM_2.5were 40-90μg/m³and 5-35μg/m³.The contribution areas were mainly distributed in parts of Central Asia and Kashgar in the western Xinjiang;In summer,it mainly came from the monsoon flow in the western Xinjiang,China,and the contribution ranges of PM₁₀and PM_2.5were 10-30μg/m³and 5-10μg/m³.The potential contribution sources were mainly distributed in Kashgar and northern Hotan of Xinjiang,China;Westerly wind prevailed in autumn,and the contribution ranges of PM₁₀and PM_2.5were 20-50μg/m³and 5-15μg/m³.The potential contribution source areas were mainly banded,mainly distributed in parts of Central Asia and Kashgar of Xinjiang,China;In winter,the air flow mainly came from South Asia,and the contribution ranges of PM₁₀and PM_2.5were10-40μg/m³and 5-15μg/m³.The potential contribution source areas were mainly fan-shaped and concentrated in parts of South Asia.（4）The four-season airflows in Kashgar of southern Xinjiang,affected by westerly winds,mainly came from Central Asia,which were consistent with the author’s simulation of the main transport pathways of the eastern Pamirs.The differences were the corresponding the high PM₁₀concentrations airflow mainly came from Xinjiang of China,and the Taklimakan Desert in the south was the source of its heavy potential contributions.in Kashgar.（5）In the eastern Pamirs,the prevention and control focus was on the long-distance transportation of atmospheric particles carried by the westerly wind in Central Asia,and the second was to prevent the impact of dust aerosols of the Taklimakan Desert in the Tarim Basin.