Determination of the mean aerosol residence times in the atmosphere and additional Po input on the base of simultaneous determination of Be, Na, Pb, Bi and Po in urban air.

The significant differences in the activities of Pb, Bi, Po and cosmogenic Be and Na radionuclides in the urban aerosol samples collected in the summers 2010 and 2011 in the Lodz city of Poland were observed. Simultaneous measurement of these radionuclides, after a simple modification of the one compartment model, allows us to calculate both: the corrected aerosol residence times in the troposphere (1 ÷ 25 days) and in the lower stratosphere (103 ÷ 205 days). The relative input of the additional sources (beside of the Rn decay in the air) to the total activity concentrations of Pb, Bi and Po radionuclides in the urban air, plays a substantial role (up to 97% of the total activity) only in the case of Po.