Weekly variation of the 210Pb air concentration in North Estonia

We performed a gammaspectrometric analysis to determine the content of 210 Pb in aerosol filter samples collected weekly in Harku-Tallinn, North Estonia, in 2001-2005. Activity concentrations varied from 65 μBq m -3 to 2020 μBq m -3 with an arithmetic mean value of 366 μBq m -3 and followed a log-normal distribution with a geometric mean value of 308 μBq m -3 and dispersion factor of 0.52. The mean values were slightly higher than those expected at a location of comparable latitude and longitude. The analysis of monthly averaged concentrations revealed a dominant seasonal variation governed mainly by the origin of intruding air masses: high 210 Pb air concentrations in winter and low values in spring and summer. A multiple linear regression analysis confirms that significant correlations between the 210 Pb concentrations in the surface air and local meteorological parameters are observed only in winter.