Analyses of ²¹⁰Pb concentrations in surface air and in rain water at the central Guizhou, China

Abstract

Samples of surface air and rain water were collected at the Mt. Guanfeng site located at Guiyang, China. The monthly mean ²¹⁰Pb concentrations in surface air exhibited a U-pattern with high values appearing in winter and low values in summer and early autumn. The annual mean of ²¹⁰Pb concentrations in surface air was estimated to be 2.7 ± 0.6 mBq m^-3, which was at least four times higher than the annual mean reported from a large number of monitoring stations located throughout the world. The amounts of enriched Uranium in soil at the region could significantly contribute a great deal of release of ²²²Rn that decay to ²¹⁰Pb which gets attached to the atmospheric aerosols. The site was under the influence of a monsoon climate. The distribution of monthly mean of ²¹⁰Pb concentrations in surface air correlates well with the reciprocal of monthly average of observed air temperature and rainfall. The partition coefficients of ²¹⁰Pb between rain water-surface air in the winter and spring were larger than those in the summer and autumn. The type and duration of rain depending on season played key roles for the changes of partition coefficients, although the rain amount is important.