Study on the Impact of Atmospheric Compound Pollutants on Air Quality in China during Sandy and Dusty Weather: A Case Study of March 2021

Horizontal dynamic monitoring of the sand and dust weather process was conducted using ground-level PM2.5 and PM10 data. The transport paths and potential sources of the sand and dust were analyzed through clustering of backward trajectories from the HYSPLIT model. Changes in the distribution of SO2, NO2, and O3 during the sand and dust weather were examined using remotely sensed data. The results indicated that: (1) The significant impact of sand and dust storms on regional air pollution in 2021, from March 13 to April 21, both PM10 and PM2.5 exhibited an overall west-to-east distribution change, with similar spatial and temporal patterns. PM10 showed the most pronounced changes, with the largest pollution range occurring on March 16, where the highest concentration reached 4943 μg/m³. The mean concentration increased by 127.1% compared to pre-sand and dust conditions. The maximum concentration peaked at 1155.70 μg/m³, representing a 190.4% increase from the initial dust levels. The daily average concentration rose from 46.34 μg/m³ on March 14 to 78.63 μg/m³, a 69.68% increase. The maximum UVAI pollution area was observed on March 15, with a peak value of 5.14 and an average value of 2.86, which is 1.9 times higher than pre-sand and dust conditions. (2) The different atmospheric components during dusty weather exhibited unique spatial and temporal evolution characteristics. The diffusion range of UVAI was largely consistent with the evolution of dust storms, with an influence range far exceeding that of PM10. Its concentration maximum and mean values increased by approximately 189% and 64%, respectively, compared to pre-dust storm conditions. The response of NO2 showed a noticeable lag, with concentrations exhibiting a distribution pattern of lower in the northwest and higher in the southeast. The peak concentration increased by 155% compared to pre-dust storm levels. The concentration of SO2 demonstrated an overall decreasing trend, particularly in the early stages of the dust storm due to enhanced turbulence, with the maximum value decreasing by up to 94.6%. This change occurred earlier than that of PM10 and PM2.5. O3 responded to the dust storm with a lag, and the impact was geographically specific, with the average value showing little change and the maximum value increasing by approximately 32%.(3) The sand source of this dusty weather is complex, and the transmission path is primarily divided into three branches: the northwest route, the west route, and the north route. The primary sand sources for the first dust storm include Kazakhstan and Kyrgyzstan outside the country, as well as the Taklamakan and Gurbantunggu deserts within the country. The second dust storm was caused by Mongolian air masses carrying sand and dust from abroad, superimposed on sand and dust from the Maowusu Desert. The combination of overseas inputs and regional sand sources was crucial to the formation of widespread pollution in both dust storms.