Mineral dust scavenges anthropogenic aerosols in polluted environment

Scavenging of anthropogenic aerosols by mineral dust in polluted environment was investigated in this work based on comprehensive observations of a long durative dust event from March 15 to 18, 2021 over north China. Combined observations of a Raman-depolarization lidar (355 nm) and a micro-pulse lidar (532 nm) show that dust particles become more spherical after mixing with anthropogenic pollutants in a polluted environment, likely due to mixing with anthropogenic aerosols. A sharply decease in anthropogenic aerosol in PM2.5 during dust event, especially for inorganic components (e.g., nitrate (NO3−), sulfate (SO42+), ammonium (NH4+)), supports the above viewpoint. The mass concentration of anthropogenic aerosol in PM2.5 decreased by 78% in late period of dust event. Further analyses suggest that such a decrease of anthropogenic aerosol in PM2.5 is caused by the coating of fine anthropogenic aerosols on coarse dust particles, rather than enhanced atmospheric diffusion capacity or weakened chemical reactions. Dust particles own high deposition velocity due to their coarse size. Hence, the coating of anthropogenic aerosols on dust particles enhance the scavenging of anthropogenic aerosols.