An experimental study of the role of radon and its daughter products in the conversion of sulphur dioxide into aerosol particles in the atmosphere

A set of experiments carried out to study the possible role of radon (Rn) and its daughters in the conversion of gaseous sulphur dioxide into particulate sulphate in the atmosphere is described. The experiments were performed under simulated atmospheric conditions in a reaction vessel containing known quantities of SO2, O3 and C2H4 in varying concentrations. The introduction of Rn gas of concentrations in the ranges prevalent in the atmosphere resulted in an enhancement of particle generation in the vessel. An increase of Rn concentration from 100 to 500 pCi m-3 resulted in an increase in the aerosol concentration in the reaction vessel from 6 x 104 to 1.4 x 105 cm-3. Since the concentrations of Rn used for these experiments correspond to the average levels of Rn at ground level it can be expected that a significant fraction of the gas to particle formation could be influenced by the background concentrations of Rn. This observation has significant implications in the study of atmospheric aerosol formation mechanisms. (author)