Atmospheric ²¹⁰Pb, ²¹⁰Po and ²¹⁰Po/²¹⁰Pb activity ratio in urban aerosols: temporal variability and impact of biomass burning emission

Figures & data

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.

Sites	Sampling period	n	Location	Elevation (m asl^$)	^210Pb (mBq m^−3)	^210Po (mBq m^−3)	^210Po/^210Pb ratio	References
Kanpur	January 2007–April 2009	99	(26.5°N, 80.3°E)	142	1.8±1.1	0.0–0.28 (0.094)	0.002–0.229 (0.079)	This study
Lodz, Poland	2008–2009		(51.8°N, 19.5°E)		0.556	0.067		Dlugosz et al. (2010)
Xiamen, China	2004–2005		(24.4°N, 118.1°E)			0.03–0.21 (0.11)		Yi et al. (2007)
Michigan, USA	1999–2001	30	(42.4°N, 83.0°W)	190	0.30–4.22	BDL-0.118 (0.072)	0.0–0.21 (0.075)	McNeary and Baskaran (2007)
Malaga, Spain	1996–2001		(36.7°N, 4.5°W)		0.51	0.045–0.070	0.11–0.13	Duenas et al. (2004)
South Pole	November 2000–January 2001		(90°S, 102°E)	2841	0.2	0.022±0.0011	0.13 & 0.18	Arimoto et al. (2004)
Egypt	January–December 2002		(28.1°N, 30.6°E)		1.2±0.15			Ahmed et al. (2004)
Alaska	January–March 1996	10	(65.1°N, 147.5°W)		0.22–1.02	0.0–0.152	0.0–0.177	Baskaran and Shaw (2001)
Argonne, Illinois	June 1996–August 1996		(41.7°N, 88°W)					Marley et al. (2000)
Jungfraujoch	January–December 1991		(46.5°N, 8°E)	3450	0.005–0.5			Gaggeler et al. (1995)
Boulder, Colorado	1967–1972		(40°N, 103.3°W)		0.15–0.78	0.002–0.052		Poet et al. (1972)
Milford, Haven			(51.7°N, 5°W)					Peirson et al. (1966)

^$above sea level.

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

Air-mass type	No. of trajectories	Occurrence (%)	Wind speed (ms^−1)	^210Pb (mBq m^−3)
Desert areas	20	40	0.7±0.6	1.3±0.5
Maritime	11	22	0.9±0.4	0.9±0.2
Localised winds	19	38	0.4±0.3	2.5±1.2

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.

Gaggeler H. W, Jost D. T, Baltensperger U, Schwikowski M, Seibert P. Radon and thoron decay product and 210Pb measurements at Jungfraujoch, Switzerland. Radiochimica Acta. 1995; 29(5): 607–616.

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