Research On The Sources Of Air Masses Of NO₂ And SO₂ Pollutants And Intercity Interaction In The Northern Slope Of Tianshan Mountains

The economic belt on the northern slope of Tianshan Mountain is an important carrier of the core area of the Silk Road Economic Belt,and it is also one of the key areas for the prevention and control of air pollution in the autonomous region.One belt,one road,is to grasp the pollution status of NO₂ and SO₂ in the region and raise the scientific understanding level of air pollutant dispersion,so as to lay a solid foundation for the successful implementation of the national"one belt and one way"strategy and the ecological security in the western region.Due to the acceleration of industrialization and the rapid growth of vehicle ownership,the problem of air pollution in the northern slope of Tianshan Mountains has become increasingly prominent.Therefore,based on the MAX-DOAS fixed monitoring in 10 cities on the northern slope of Tianshan Mountain from January to December in 2019,the seasonal variation of atmospheric tropospheric NO₂ and SO₂ column concentration in the region was retrieved,the air mass source and diffusion trajectory in the region were analyzed,and the inter city interaction in the region was analyzed by using spatial variability,combined with topography,meteorological factors,vehicle ownership,industrial structure and industrial structure Population and other factors were analyzed.The main conclusions are as follows:（1）From the perspective of seasonal variation,the tropospheric NO₂ and SO₂ column concentrations in the northern slope of Tianshan Mountains are characterized by"high in winter and low in summer",showing a"U"type trend.From the comparison of NO₂ column concentration in 10 cities on the northern slope of Tianshan Mountain:Urumqi City（12.58）>Shihezi City（7.93）>Karamay City（7.68）>Dushanzi district（6.22）>Kuitun city（7.45）>Changji City（7.69）>Wusu city（7.79）>Wujiaqu City（7.45）>Bole City（8.85）>Fukang City(6.24×10¹⁵mlec/cm²);the comparison of SO₂ column concentration:Urumqi City（7.45）>Bole City（8.85）>Fukang City(6.24×10¹⁵mlec/cm²)The results showed that the column concentration of NO₂was higher than the column concentration of SO2 in all the cities.The column concentration of NO₂ was（10.20）>Changji City（6.30）>Wujiaqu City（6.02）>Kuitun city（5.13）>Dushanzi district（5.49）>Wusu city（5.19）>Karamay City（4.75）>Shihezi City（5.32）>Bole City（5.67）>Fukang City(4.26×10¹⁵mlec/cm²).（2）Based on the backward trajectory and trajectory clustering model,the sources and diffusion trajectories of atmospheric NO₂ and SO₂ were studied.The results show that:in the northern slope of Tianshan Mountains,the proportion of pollutants coming from other places is small,and the main source is local pollution.The air mass flows from the western cities to the eastern cities as a whole.The intercity atmospheric activities are frequent and the intercity interaction is significant.From the cluster analysis,it shows that the closer the distance between cities,the stronger the interaction between cities,and vice versa.（3）The results show that the concentration of NO₂ in the study area is 1-39 ×10¹⁵molec/cm²,and the concentration of SO₂ in the study area is 1-18×10¹⁵molec/cm².On the whole,the concentration of SO₂ in the vertical column is less than that of NO₂.The variation coefficient of NO₂ vertical column concentration in each city ranged from 7.73%to 30.36%,and the variation coefficient of SO₂ vertical column concentration in each city ranged from 6.52%to 31.64%.The spatial autocorrelation range of NO₂ was Changji City>Urumqi City>Karamay City>Wusu city>Dushanzi District>Shihezi City>Bole City>Kuitun city>Wujiaqu City>Fukang city.The spatial autocorrelation range of SO₂ was Wujiaqu City>Karamay City>Changji City>Urumqi City>Dushanzi District>Wusu city>Bole City>Shihezi>Fukang City>Kuitun city.Generally speaking,the spatial autocorrelation range of urban seasons is summer>spring>autumn>winter.It can be concluded that the closer the distance between cities,the stronger the spatial interaction between cities.The inter city interaction is significantly affected by randomness and structure.（4）From the perspective of influencing factors,structural factors:the terrain of the study area on the northern slope of Tianshan Mountains is high in the South and low in the north,and the local annual dominant wind direction is northwest wind,which makes it difficult for pollutants to disperse effectively,and there is a certain transmission and accumulation of pollutants between cities;the concentration of NO₂and SO₂ in the area is related to the average temperature,average pressure and sunshine duration The average wind speed,average precipitation and relative humidity are inversely proportional.Random factors:the continuous growth of vehicle ownership,industrial structure,urban population and human activities lead to the accumulation of pollutants in the urban area.The anthropogenic source of SO₂mainly comes from industrial production,while the urban area on the northern slope of Tianshan Mountains is mainly coal-fired,and the rapid development of energy structure and petrochemical industry has led to the increasing pollution of SO₂ in this area.This study provides some scientific guidance for further understanding the air pollution situation of cities on the northern slope of Tianshan Mountains and formulating pollution prevention and control policies.