Precipitation scavenging studies of radionuclides in air using cosmogenic 7Be

Precipitation scavenging of 7Be in air was studied, especially during winter. A nearly linear relation between precipitation and 7Be deposition was found, not only in the winter monthly data, but also in the individual snowfalls. The 7Be concentrations in snow water and in air were measured simultaneously. Washout of 7Be-bearing aerosols in air was directly observed. But in the overall precipitation phenomenon, it appeared that rainout was the predominant process in wet scavenging of 7Be. Then, the linear relation between precipitation and 7Be deposition was introduced and an equation which was composed of two terms corresponding to washout and rainout was derived from integration of the empirical formula of deposition for individual precipitation.