Tracking spatiotemporal dynamics of dust aerosols in China: Emissions, transport, and mitigation insights

Dust aerosols, recognized as hazardous atmospheric pollutants, significantly impact air quality, human health, and ecosystems. Understanding the dust's spatiotemporal dynamics, sources, and transport paths is crucial, especially in China, as it is home to major dust sources in East Asia and frequently experiences severe dust events. Substantial dust aerosols are produced during dust events, leading to sharp increases in particulate matter concentrations and resulting in health and environmental issues in both the dust source regions and downwind populated areas. Building on this context, this study analyzes the spatiotemporal distribution of dust aerosols in China and its six subregions between 2000 and 2023 using MERRA-2 reanalysis data. Unlike previous studies that focus on climatic drivers and anthropogenic factors influencing dust aerosol trends, this study provides new insights into dust aerosol trends in large provincial cities (population 2-20 million) within the dust-prone "Three-North" region, from the perspective of dust emissions, fluxes, and transport processes. Furthermore, the combination of MERRA-2 simulations and backward (forward) trajectory analyses offers complementary strengths. The results show that (1) spring Dust Aerosol Optical Depth (DAOD) decreased 2000-2023, with the exception of the Taklamakan Desert, where both dust emissions and DAOD increased; (2) increased dust emissions from the Saryesik-Atyrau Basin in eastern Kazakhstan resulted in higher DAOD over the southern Jungger Basin; (3) Taklamakan Desert emissions remained high across all seasons, sustaining elevated DAOD within the Tarim Basin; (4) MERRA-2 fails to capture anthropogenic dust emissions from cropland of the North China Plain, while the back-trajectory analysis based on measurements of particulate matter less than 10 μg/m³ in several cities across the North China and Northeast China suggests dust emissions from this region. This finding highlights the need to improve dust emission parameterizations in reanalysis models like MERRA-2, particularly when studying the impact of anthropogenic activities on dust emissions and air quality. Overall, the study provides essential references for managing the health and environmental impacts of dust aerosols in large densely populated cities of China.