Re Radon Emanation / Tilling Soil

["Leo M. Lowe" <llowe@senes.on.ca>]

The instantaneous radon flux rate from tilling soil with a Ra-226
concentration (average in St. Louis) was previously estimated at about
2.3E5 pCi/s (based on a till rate of 3 m2/s).

Dispersion models can be used to estimate the resultant air concentrations.
 However, assuming very conservatively for now that all the radon is
emitted from a ground-based point source (instead of a diffuse area
source), a moderate dilution factor would be in the order of 1E-4 or
smaller at a distance of 100 m from the source.  The above flux rate would
therefore convert to a radon concentration of 2.3E5 x 1E-4 = 23 pCi/L.

However, this concentration (upper bound estimate) would be very short-term
(only during tilling) and very localized.  The average over the course of a
year would be insignificant.  Also note that radon progeny ingrowth would
be very small because of the short time available (less than 1 min at 100 m
for windspeeds of 2 to 3 m/s).


Leo M. Lowe, Ph.D.
Principal, Senior Health and
Environmental Physicist

SENES Consultants Limited
121 Granton Drive, Unit 12
Richmond Hill, Ontario
Canada L4B 3N4
Tel:	(905) 764-9380
Fax:	(905) 764-9386
email:	llowe@senes.on.ca
WWW:	www.senes.on.ca
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