The sources and fate of 210Po in the urban air: A review (original) (raw)
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Journal of Radioanalytical and Nuclear Chemistry, 2012
The significant differences in the activities of 210 Pb, 210 Bi, 210 Po and cosmogenic 7 Be and 22 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 7 25 days) and in the lower stratosphere (103 7 205 days). The relative input of the additional sources (beside of the 222 Rn decay in the air) to the total activity concentrations of 210 Pb, 210 Bi and 210 Po radionuclides in the urban air, plays a substantial role (up to 97% of the total activity) only in the case of 210 Po.
Journal of Geophysical Research, 2007
Daughter products of 222 Rn (such as 210 Pb, half-life = 22.1 years, and 210 Po, half-life = 138 days) have been widely used as tracers to determine the removal rates of aerosols as well to obtain analog information on the behavior of other chemical species in the lower atmosphere. To establish the first data set on the depositional fluxes of 210 Po in bulk precipitation and concentrations in air samples from the midwestern United States, we measured the depositional fluxes of 210 Pb and 210 Po in the bulk (wet plus dry) and dry fallout by deploying a rain collector (dry and bulk) for a period of 17 months. We also collected 30 aerosol samples during this period to assess the temporal variations of these nuclides in the surface air in Detroit, Michigan. The activity of 210 Po in the surface air ranged from below detection limit to 0.118 mBq m À3 (mean of 0.072 mBq m À3). The specific activities of 210 Po and 210 Pb in aerosols ranged between 0.28 and 4.48 Bq g À1 (mean of 0.87 Bq g À1) and 2.7 and 30 Bq g À1 (mean of 13.6 Bq g À1), respectively; these values are about 1-2 orders of magnitude higher than the surface soil. The mean activity ratios of 210 Po/ 210 Pb in the bulk precipitation and dry fallout were found to be 0.049 (n = 27) and 0.25 (n = 8), corresponding to residence times of 15 and 75 days, respectively. Higher values in the dry fallout are attributed to resuspension of very fine older material from the ground. The 210 Po/ 210 Pb activity ratios in the aerosols varied between 0 and 0.210 (mean of 0.075), with corresponding residence times of 0-61 days (mean of 22 days). The mean deposition velocity and bulk washout ratio obtained using 210 Po is compared with those obtained for 210 Pb. From the measured aerosol mass concentrations and calculated values of the depositional velocity, the calculated depositional fluxes of aerosols are reported.
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
Environmental Science: Processes & Impacts, 2013
A radiological survey on the iron-and steel-making plant ILVA (Italy) was mainly focused on contamination source-term investigation and exposure impact evaluation of the volatile radionuclides 210 Po and 210 Pb. The activity concentrations of 210 Po and 210 Pb in the raw materials, dust particles, surficial soils and atmospheric particulate samples collected in the area of ILVA Taranto were determined. The results showed that the activity concentrations in the raw materials were in the range of 3.46-17.9 Bq kg À1 for 210 Po and 3.50-16.8 Bq kg À1 for 210 Pb, which could create maximum annual inventories of 2.64 Â 10 11 Bq of 210 Po and 2.71 Â 10 11 Bq of 210 Pb if a total quantity of 22 Mt per year raw materials was consumed in the plant. The activity concentrations in dust particles emitted from the chimney of the ILVA Taranto were in the range of 5.91-85.6 kBq kg À1 for 210 Po and 5.44-34.6 kBq kg À1 for 210 Pb, releasing more 210 Po than 210 Pb. The activity concentrations in surficial soils were in the range of 49.3-140 Bq kg À1 for 210 Po and 51.6-150 Bq kg À1 for 210 Pb, a variation of the activity concentrations being observable with distance. The activity concentrations in atmospheric particulate were in the range of 43.1-564 mBq m À3 for 210 Po and 618-1099 mBq m À3 for 210 Pb, and it was observed that the mass specific activity concentrations of 210 Po and 210 Pb in the atmospheric particulate are one to three orders of magnitude higher than that found in the top soil. After deduction of the background contribution, about 27.2 mSv per year of the estimated committed effective dose at mean and 49.2 mSv per year at maximum could be attributed to 210 Po and 210 Pb emitted from the chimney of the ILVA Taranto and inhaled by the public in the form of atmospheric particulate, of which about 63.5-69.0% was the contribution of 210 Pb. No specific interventions should be required, as far as only inhalation of 210 Po and 210 Pb are concerned.
Chemosphere, 2020
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Atmospheric deposition of 210Po and 210Pb in Malaysian waters during haze events
Journal of Radioanalytical and Nuclear Chemistry, 2013
ABSTRACT Biogenic burning as forest fire phenomena occurring from April to August each year in the Sumatra and Borneo islands are major sources of biogenic uranium–thorium decay series in marine systems. 30 samples were collected during the Ekspedisi Pelayaran Saintifik Perdana 2009 cruise (EPSP 2009 cruise) between 12th June and 1st August 2009 from the Straits of Malacca to the Sulu and Sulawesi Seas to study the effect of haze and the monsoon season on the deposition rate of 210Po and 210Pb in Malaysian waters. All samples were spiked with 1 ml of lead [Pb(NO3)2; 25 mg ml−1] and 0.05 ml of Polonium-209 tracer (26.08 dpm ml−1). 210Po activity was determined by auto plating onto silver foil and counting using an alpha spectrometry system (Canberra model Alpha Analyst with a silicon-surface barrier detector). Lead that was collected via electrodeposition, formed lead sulphate (PbSO4) precipitation. This precipitate was wrapped onto plastic discs and counted for 210Pb beta activity using a gross alpha–beta counting system (Tennelec model LB-5100 low background gas-flowing anti-coincidence alpha/beta counter) after 1 month to allow bismuth ingrowths. The range of 210Po activities varied between 51.08 ± 15.1 and 742.08 ± 220.34 Bq/kg, whereas the activity of 210Pb ranged from 31.10 ± 4.20 to 880.23 ± 123.86 Bq/kg and 210Po/210Pb ratio value varied between sampling stations from 0.19 to 13.77. The contents of 210Po were also statistically positively correlated with the amount of total suspended particulate especially those recorded during heavy haze period events.
Aerosol and Air Quality Research, 2014
Atmospheric deposition of 210 Pb and 210 Po from Nov. 2010 to Jan. 2012 were analyzed to reveal their temporal variations, as well as applications in constraining the residence times of aerosol. The monthly depositional fluxes varied from 2.42 to 29.31 Bq/m 2 /mon and from 0.160 to 3.388 Bq/m 2 /mon for 210 Pb and 210 Po, respectively. High fluxes of 210 Pb and 210 Po were observed in the southwest monsoon prevailing months, while low fluxes corresponded to the northeast monsoon seasons, revealing the monsoon control over 210 Pb and 210 Po deposition on seasonal timescales. There were significant positive linear correlations between the daily depositional fluxes and precipitation, supporting the predominant removal passage of 210 Pb and 210 Po through rainfall. The inverse relations between specific activities and precipitation indicated that the removal efficiencies were much higher at the beginning of rainfall. In contrast, the dry deposition only accounted for 22% and 29% of the bulk depositional fluxes of 210 Pb and 210 Po, respectively. The depositional flux ratios of 210 Po to 210 Pb varied between 0.015 and 0.223 with a mean of 0.091 ± 0.012, corresponding to the residence times of 3.1-57.5 d with an average of 20.8 ± 3.0 d. Investigations on size-fractionated 210 Po and 210 Pb could provide better understanding of the resident timescales of aerosol.
Atmospheric Environment, 1995
Concentrations of 222Rn, 21°Pb, 2~°Bi and 21°po were measured in surface air at Sacavem, near Lisbon, at the.iunction of the North Atlantic ocean and the European continent. 222Rn concentrations were strongly associated with the origin of the air masses, being very low, ~ 0.1 Bq m-3, in maritime air and much higher, 2-10 Bq m-3, in continental air masses. Furthermore, different 222Rn : 2~°Pb activity ratios were found in those air masses with average values of 1 x 103 and 5 x 10", respectively. In the short time intervals of sampling, 2t°pb concentrations in the atmosphere were positively correlated with aerosol concentration.,;, suggesting soil resuspension as 2 t Opb source. However, comparison of 2 topb: 23s U activity ratios in aerosols and surface soil particles provided evidence that resuspensions give little contribution, averaging 10%, to 210pb in surface air. A seasonal fluctuation in the concentration of 2 ~Opb in surface air was observed being higher 2~°Pb concentrations consistently measured during fall and winter. Nevertheless, concentrations of 210pb in surface air were not controlled by the seasonal rainfall. Instead, the seasonal fluctuation of ::lOpb corresponds to the seasonal influence on the region of air masses with different origins: predominantly, of continental origin in fall and winter and of maritime origin during spring and summer. The annual average of 2~°pb at Sacavem, 181 #Bqm -a, is substantially lower than values reported for inland locations, attesting for the strong influence of oceanic air masses. The mean residence time (MRT) of aerosols, 3.8 d, was found comparable to values reported for other regions, but data further suggest different MRTs with the seasons of the year. It is concluded that at Sacavem, the concentrations of radon and radon daughters, particularly those of 21°pb, are controlled mainly by large-scale meteorological conditions, especially through the alternate intrusion of either oceanic or continental air masses into the local surface air. 222Rn : 21°pb concentration ratios in those air masses are distinct and provide a means to identify their origin.