Unraveling the process of aerosols secondary formation and removal based on cosmogenic beryllium-7 and beryllium-10

The secondary formation and diffusion processes of aerosol are extraordinarily complex and significantly impact the environment and human health. Therefore, exploring the process of aerosol formation and diffusion based on independent new tracer has always been a concern. The ⁷Be and ¹⁰Be, which are generated only by the action of cosmic rays, are chemically stable and adsorbed on aerosol for transmission, so they have the potential characteristics of aerosol tracers. Here, we obtained the daily resolution atmospheric ⁷Be, ¹⁰Be, and ¹⁰Be/⁷Be without dust interference in Xi'an autumn and winter (heavy pollution period in a typical polluted area) by accelerator mass spectrometry. It is found that during the rapid formation of secondary aerosols (SA) under the stable ¹⁰Be/⁷Be ratio, which indicates the stable atmospheric vertical structure, the concentration of ⁷Be and ¹⁰Be is significantly negatively correlated (R² > 0.9) with the aerosol concentration. Therefore, SA relative content in aerosols can be estimated by the dilution amount of ⁷Be and ¹⁰Be to reveal the secondary-formation process of aerosol (33% average contribution to aerosols during the winter heavy air pollution period). Furthermore, we also revealed the physical removal process of aerosols based on ⁷Be, ¹⁰Be, and ¹⁰Be/⁷Be, including precipitation removal and diffusion of vertical atmospheric movement caused by stratospheric air intrusion. In summary, meteoric cosmogenic ⁷Be and ¹⁰Be will provide a new way to study the secondary chemical formation and physical removal of aerosols.