Identification Of Aerosol Anthropogenic And Natural Dust Sources And Attribution Of Emission Rate In Typical Arid Area

Xinjiang is characterized by widely desert and Gobi distribution,frequently dust storms and the heavy dust emissions.21st century,due to the interference of climate change and human factors,the degree of desertification in arid regions has increased,and dust activities have become more intense,which has caused serious threats to the ecological environment and human health in Xinjiang.Relevant scientists have used remote sensing technology to perform a lot of research on dust sources and emissions on a global scale.However,there is a lack of pertinent research on dust sources in small and medium-sized regions.In this article,long-term MODIS aerosol data and Reanalysis data,combined with the DEM,land use type,precipitation data,DMSP/OLS nighttime light image and population density of Xinjiang,analyze the major dust sources as well as the dust transportation process.The research results are as follows:(1)This study compared the AOD and DOD data with ground base observation data and evaluated the applicability of AOD and DOD data in Xinjiang region.The AOD and DOD high value areas were mainly located in the Tarim Basin and Jungar Basin.The results showed that the mean AOD and DOD values of the four seasons were:spring>summer>winter>autumn,AOD and DOD high value were mainly concentrated in the southern part of Xinjiang.Apart from autumn,AOD and DOD were changed significantly in other seasons during the study period.The monthly mean AOD and DOD in Xinjiang peak from March to April.The yearly mean AOD and DOD showed a weak downward trend,average value of AOD during the 17 years was 0.25,DOD average value was 0.03.During 2003-2008,AOD in Xinjiang presented a growth trend,the DOD in the region remained stable.During 2009-2014,AOD in the Central and Southwestern part of the region continue to increase,while the trend of AOD in the North and Southeast Xinjiang changed from increasing to decreasing,DOD in the Taklimakan Desert displayed a declining trend.During 2015-2019,AOD and DOD in most areas of Xinjiang showed a significant downward trend.(2)Compared the percent cumulative frequency of three values of optical depths and for each region and season,DOD threshold 0.2 was supposed to distinguish dust events from background aerosols.The maximum value of dust frequency of occurrence indicates the location of the dust sources.The most active period of dust sources was in spring,with the highest frequency of 23%.Natural dust sources were mainly located in the desert,dry lakes,and riverbeds.Anthropogenic dust sources were mainly found in farmland,the range of dust sources changed frequently.The trajectory analysis showed that dust in Lop Nur region can be transferred to East China or even the Pacific Ocean,but most of the dust settled near the dust source region.(3)Xinjiang annual dust emissions were 294.01 kg m^-2 yr^-1,92%of dust emissions come from natural dust sources and only 8%were related to the anthropogenic surface.The precipitation in the entire area was inversely proportional to the dust emissions.The major dust source regions distributed over the transit zones of Alluvial fan to the edge of the desert.Anthropogenic dust emissions were proportional to the DMSP/OLS night-time light data and population density,indicated that human activities were the main factors affecting the anthropogenic dust aerosol in the region.Considered the annual mean dust emissions of different regions,the greatest emissions of natural dust occurred over Hami Prefecture,Bayingol Mongolian Autonomous Prefecture,Hotan Prefecture,Turpan Prefecture,Aksu Prefecture,Changji Hui Autonomous Prefecture and the greatest emissions of anthropogenic dust occurred over Tacheng Prefecture,Karamay,Altay Prefecture,Urumqi.