Radon emanation from farm fields

[FIELDRW@aol.com]

Chris,

Thank-you very much for the interesting  thougts you expressed below.  I have
not considered that potential for radon release.  However, we have documented
extremely high waterborne radon concentrations in drainage tiles from
agricultural land.  In addition to the radon potential you describe, we also
have a potential source of radon from the millions of tons of phospate
fertilizer (radium source)  that gets deposited in the fields each year.  As
time permits, I will plow into an exploration of the potential release, it
sounds like an area that needs further cultivation.

Regards, Bill Field
bill-field@uiowa.edu 
University of Iowa

In a message dated 11/19/98, 3:33:59 AM, radsafe@romulus.ehs.uiuc.edu writes:
<<RADSAFERS and Bill Field,  Allow me to belatedly add a rock to the tailings
pile and propose an expansion of the 12th category.  Uranium and Radium are
well distributed in the ground and not confined to particular geological
formations.    Agricultural workers who till the land, particularly when
ploughing, obviously change (enhance) the emanation conditions for Radon
from the top layer of soil by changing the general porosity as well as the
concentration gradient by bringing higher concentrations  to the surface -
until a new equilibrium has developed.   The quantification of this effect
in terms of air Radon concentration could be a very interesting field of
study in the fields of Iowa (no pun intended) - millions of acres.   A few
inches below ground the Radon concentration is at least 3 orders of
magnitude higher than in the air above, explaining why small changes in the
transport conditions for Radon gas in the top layers or disturbance of the
concentration profiles could result in significant changes in emanation.
Care would have to be exercised to separate the surface disturbance effect
from other sources of fluctuation, e.g. barometric pressure.  The exposure
impact of temporarily enhanced Radon escape would depend on the dynamics of
the process, which would have to be investigated.  It seems logical that
persons in the proximity would be mainly affected, but that there should
also be a more general elevation of open air Radon concentrations in the
case of extensive operations.   The average life of Rn-222 is 5.5 days; the
daughter equilibrium factor (~ 0.8)  is established in about 2 hours.   I
think the effect should be considered seriously and investigated, although
in lighter vein, it remains doubtful whether the weekend gardener, pulling
weeds and turning the soil,  needs to be classified as a radworker...>>
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