Atmospheric 210Pb, 210Po and 210Po/210Pb activity ratio in urban aerosols: temporal variability and impact of biomass burning emission (original) (raw)
A B S T R A C T Atmospheric 210 Pb, 210 Po and their activity ratio ( 210 Po/ 210 Pb) have been studied for two years (January 2007Á April 2009) from an urban site (Kanpur: 26.58N and 80.38E) in the Indo-Gangetic Plain. The average activities of 210 Pb and 210 Po centre on 1.8 mBq m (3 (range: 0.5Á4.8 mBq m (3 for n099) and 0.094 mBq m (3 (n021, range: 0.002Á0.28 mBq m (3 ), respectively. The temporal variability in the activity of 210 Pb is significantly pronounced, with relatively high levels during OctoberÁNovember and DecemberÁFebruary; a trend similar to that observed for the carbonaceous species. The high aerosol abundance coinciding with the biomass burning emissions (agricultural-waste burning) during OctoberÁNovember and stagnant boundary layer in the wintertime (DecemberÁFebruary) is the dominant factor for the observed temporal trend. The preliminary data suggest that biomass burning emissions also contribute to the atmospheric 210 Po activity, as evident from the large variability in the 210 Po/ 210 Pb activity ratio (range: 0.02Á0.23) at this urban site. These results have implications to the model-based activity levels of 210 Pb and 210 Po from in-situ decay of the parent nuclide ( 222 Rn) for given latitude. (page number not for citation purpose) 2 K. RAM AND M.M. SARIN