Impact of Dust Aerosols on Air Quality in Southern Xinjiang

Dust aerosols, originating from wind erosion, desertification, and anthropogenic activities, ubiquitous in arid and semi-arid regions, profoundly influence radiation, clouds, precipitation, atmospheric chemistry, and biogeochemistry. This study investigates the impact of dust aerosols on air quality in the western region of China, mainly focusing on Xinjiang. As the largest provincial-level region in China, Xinjiang presents a diverse landscape ranging from vast deserts to mountainous terrains. The intricate interplay of geographical features, including the Taklamakan Desert and the Tianshan Mountains, contributes to the intricate transport pathways of dust aerosols. By selecting Xinjiang as the study area, we aim to capture the different impacts of dust aerosols on southern and northern Xinjiang. Simultaneously, we are committed to enhancing the accuracy of coarse dust aerosol (2.5 μm < D < 10 μm) simulations in the model. This research investigates the disparities in the impact of dust aerosols between northern and southern Xinjiang. Preliminary analyses suggest that the north and southern regions exhibit variations in dust aerosol concentrations, transport patterns, and associated air quality consequences. Based on hourly data of six conventional air pollutants from an automatic station in the oasis city at the edge of the Tarim Basin in 2016, as well as the analysis of 1664 PM2.5 and PM10 receptor samples from 14 different locations in the oasis city during different seasons, particularly in the dust and sandstorm season (March to May), the daily average concentrations of PM2.5 and PM10 ranged from 71 to 253 μg/m3 and 325 to 799 μg/m3, significantly exceeding those in the non-dust and non-heating season (20-59 μg/m3 and 87-196 μg/m3). During the dust and sandstorm season, dust emissions, primarily from natural sources, contribute to more than 60% of PM, highlighting their predominant role as significant contributors to PM concentrations. Therefore, enhancing the accuracy of simulating dust loa using models is crucial for understanding the impact of dust on air quality. Recent studies comparing global model simulations against measurements showed that most models underestimate coarse dust load in the atmosphere, and this underestimation can be associated with poorly resolved or poorly understood processes that result in too-little emission or too-fast deposition of these particles in the models. Therefore, we employ WRF-Chem to investigate the sensitivity of coarse mode particulate matter to size distribution and settling velocities based on existing dust simulation schemes. By comparing the simulation results with observational data to identify the optimal size distribution and settling velocities for effective coarse-mode dust simulation. Understanding the dynamics of dust aerosols in this region is crucial for comprehending their broader impacts on air quality and environmental health. And the regional differences are pivotal for implementing targeted air quality management strategies tailored to the specific challenges faced by each subregion.