ISSN:
1573-0662
Keywords:
Radon
;
radon daughters
;
plate-out
;
maritime air
;
particles
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
Notes:
Abstract Radon daughters are produced as free ions, but they become attached to aerosol particles at a rate depending on the particle concentration. In the lower marine boundary layer, most of those which do not become attached plate out on the ocean surface. In this paper a simple model is used to examine the influence of several parameters on radon/radon daughter disequilibria in maritime air. The model is compared with experimental data from Cape Grim. The radon daughter to radon ratio, ‘f’, decreases from 0.86 to 0.1 as the particle concentration falls from 1000 to 10 cm-3. Estimates of radon concentration at sea level, based on daughter measurements may therefore be in error by as much as a factor of 10 unless allowance is made for particle concentration. At 100 cm-3, the standard deviation of the distribution of measured ‘f’ values is about 30%, indicating that the particle concentration is not the only factor influencing the loss of radon daughters. The implication is that radon daughters can be used to measure radon concentrations at sea level with an accuracy of about 30%, provided the particle concentration is known. The measurements show that there is a very low proportion of unattached daughers in the air between about 30 and 165 m above sea level. According to the model, this implies that mixing of air up to about 200 m is usually rapid enough to result in plate-out of radon daughters on the ocean on a time scale of less than 100 s.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00053666
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