Modification of the atmospheric polonium 210 to lead 210 ratio by volcanic emissions

Abstract

Volcanic gases are very rich in long‐lived radon daughters, especially in 210 Po. Thus more than 50×10 3 Ci per year of 210 Po are injected into the troposphere by a normal volcanic activity, and more than 1×10 3 Ci per year into the stratosphere by volcanic explosions. These fluxes should account for one half of the 210 Po content in both of these reservoirs. On the contrary the volcanic sources of 222 Rn and 210 Pb are generally negligible with regard to the soil production. This new result could explain most of the discrepancies observed by comparing the activity ratios of the different radon daughters, including the existence of 210 Po/ 210 Pb figures superior to one (overequilibriums). Stratospheric aerosol residence times calculated on this basis are found to be shorter than the previous figures.