Quantifying The Contribution Of Dust Sources In Major Cities In Hexi Region Based On Composite Fingerprinting Technology

As a catastrophic weather phenomenon,dust storms have a profound impact on global climate change and human production and life.The Hexi region,as the main part of the northwest China,is one of the major dust sources globally and an important ecological barrier in the northwest arid zone.The sustainable and stable social,economic,and ecological development of the Hexi region is not only vital to the development of the surrounding cities and the production and livelihood of the residents,but also plays an important role in maintaining the overall stability of the country and the strategic pattern of ecological security.However,due to global climate change and human activities,the ecological environment of the Hexi region is extremely fragile and vulnerable to dust storms and even exceptionally strong dust storms,which seriously affects the sustainable development of the local ecological environment,society,and economy,and the production life and health of the residents,and is also an important threat to the sustainable development of the environment in China and globally.Therefore,conducting research on dust storms in the Hexi region is of great importance for environmental change in East Asia and even globally.However,the current studies on dust storms in the Hexi region mainly have the following shortcomings:1)Previous studies have mainly identified some macroscopic source areas of dust storms through simulations,with less research on the refinement of dust source areas.2)Most previous studies have modelled and quantified the contribution of dust source at larger scales,resulting in large differences in results,and there is a lack of research on the refinement of regional dust sources and quantification of the contribution of different sources.3)The distinction between natural and anthropogenic dust sources and the quantification of source contributions are relatively weak due to the relatively diverse sources of dust.Therefore,this paper takes dust storms in the Hexi region as the research object and takes the source-transport-sink process of dust storms as the linkage.By using a combination of field sampling,satellite remote sensing,ground monitoring and model simulation,we define the dust source areas affecting the major cities in the Hexi region,identify dust events,reveal the characteristics of dust variability and transport mechanisms,quantify the contribution of dust sources affecting the major cities in the Hexi region and identify the major sources.On this basis,we further subdivided the Hexi region into several dust source areas,collected topsoil samples and dustfall samples during dust storms in the Hexi region,and used the composite fingerprint recognition technique to establish an end-model between dustfall samples and topsoil samples to quantify the contribution of each dust source to major cities in the Hexi region,distinguish between natural and anthropogenic sources and quantify their contributions.The main findings are as follows:The main dust sources affecting the Hexi region are generally located in the northern part of Xinjiang,which is mainly dominated by the Gurbantunggut Desert（Source A）;the Taklimakan and Kumtag Deserts and their surrounding areas（Source B）;both Qaidam Basins（Source C）;and the Badain Jaran Desert,Tengger Desert,Hobq Desert,Ulan Buh Desert,and Mu Us Sandy Land and their surrounding areas（Source D）.Using PM₁₀concentrations in major cities in the Hexi region as an indicator to quantify the contribution of each source area,it was found that Sources D makes the highest contribution to PM₁₀concentrations in the Hexi region（42%）and is the most significant dust source affecting the Hexi region.Although the Taklamakan Desert,which is included in Source B,is one of the major dust sources affecting the Hexi region（23%contribution）,about 63%of the dust originates from the Kumtag Desert and therefore the Kumtag Desert,rather than the Taklamakan Desert,is one of the major dust sources affecting the Hexi region.Source A contributes less to the Hexi region（22%）due to higher precipitation and higher vegetation cover.Sources C contributes the least（13%）to the Hexi region due to the obstruction of the Qilian Mountains.In general,the influence of the dust source areas on the different areas of the Hexi region shows a clear distance effect.The frequency of dust weather that occurred and the frequency of PM₁₀that exceeded the daily standard value in the Hexi region followed a significant seasonal variation,with higher values in the spring and lower values in the autumn.The occurrence of dust events has caused PM₁₀concentrations to rise sharply in cities,however the higher PM₁₀concentrations in winter were mainly due to emissions from anthropogenic sources during the heating process.There is a strong spatial heterogeneity in soil properties and surface landscape characteristics across the dust source in the Hexi region,and the heterogeneity is more obvious in areas with human activities such as farmland.The refined dust source was classified into 12 source groups according to the different source areas through which all dust events were transported.The optimal combination of fingerprints for different source groups was found to be different,and the cumulative correct discrimination rate was greater than 85%,indicating that the combination of fingerprint factors for each source group has high discrimination ability and can effectively distinguish and quantify the contribution of each source in the corresponding source group.Therefore,the composite fingerprint technology has shown good applicability in the tracing and contribution quantification of dust sources.Based on the Collins,DFA and MixSIAR models to quantify the contribution of dust sources in the Hexi region and found that the contribution of dust sources to different cities in the study area varied significantly due to the combined influence of anthropogenic and natural sources,but the simulated source contributions were generally similar.All three models showed that the main dust sources in the western cities（Dunhuang and Jiuquan）were the Western Gobi and Western Oasis;Zhangye was mainly influenced by the Western Gobi,Western Oasis,Middle Gobi,and Middle Oasis,with the Middle Oasis having the most significant influence.The eastern Gobi,the eastern oasis,the Badain Jaran Desert,and the Tengger Desert have a greater impact on the eastern cities of the Hexi region（Jinchang,Wuwei,Baiyin and Lanzhou）,although the results of the three models differ for individual cities in the eastern part.The main dust and sand source in Alxa Right Banner is the Badain Jaran Desert,while the rest of the sources are less influential.In addition,the contribution of each dust source to each city is also clearly diversified from west to east,i.e.,cities in the west are influenced by fewer dust sources,while cities in the east are influenced by multiple source areas due to prevailing winds,etc.The overall contribution of each dust source to the cities in the study area shows a clear distance effect,i.e.,the closer the city is to the dust source,the more it is influenced by it.The overall contribution of natural sources to the major cities in the Hexi region was greater than that of anthropogenic sources,however,there was a higher contribution of anthropogenic sources than natural sources in Zhangye,indicating that the influence of anthropogenic sources on the study area as a major source of dust storms in the Hexi region cannot be ignored.This study showed that the composite fingerprinting technique is a new method to detect the sources of dust storms and to quantify the source contribution,however,differences in model principles and parameters lead to differences in contribution values.Therefore,in future studies,various measures such as the determination of dust grain size,the selection of fingerprint factors with high tracer capacity and good conservativeness,and the consideration of factors contributing to model uncertainty will be considered to select different composite fingerprinting techniques and thus quantify the contribution of dust sources.