Fig. 1.
Air mass back-trajectories (n=50) arriving at the sampling site (Kanpur, shown in red-square) originating from (a) long-range transport from Desert regions (40%), (b) maritime air masses (22%) and (c) localised winds from Northern India (38%).
Fig. 2.
Temporal variability of 210Pb activity and carbonaceous species (EC, OC) in aerosols from Kanpur during the sampling period. The vertical dashed-line separates the seasons whereas the vertical bar indicates a break in the sampling.
Fig. 3.
Average 210Pb activity in urban aerosols during the sampling period. The vertical dash-lines indicate breaks in the aerosol sampling.
Table 1. 210Pb, 210Po and 210Po/210Pb activity ratios from an urban site (this study) are compared with the literature data. The values in the parenthesis represent average values.
[i] $above sea level.
[ii] BDL=below detection limit.
Fig. 4.
Seasonal wind-rose plot for the sampling period from January 2007 to April 2009: (a) October–November, (b) December–February and (c) March–June. The acronyms N, E, S and W refer to North, East, South and West directions, respectively.
Fig. 5.
The relationship between 210Pb activities with (a) ambient temperature and (b) wind speed in aerosols at Kanpur during the sampling period. The data for October–November (post-monsoon), winter (December–February) and summer (March–June) are shown separately. The lower temperature and wind-speed are typical of the wintertime conditions due to lower boundary layer height.
Table 2. The average 210Pb activity in different types of air masses arriving at Kanpur during the sampling period
Fig. 6.
Temporal plot of activities (in mBq m−3) of environmental nuclides: (a) 210Po, (b) 210Pb and (c) 210Po/210Pb activity ratio at the sampling site (Kanpur) in the Indo-Gangetic Plain.
