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

Abstract

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.