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Re: Radon profiles in the ground/soil
Hi all:
My recollection is from readings of the literature over two decades ago,
that the radon concentration in soil gas "at depth" is anything but in
equilibrium with the radium at the same depth. Just as radon in ground
water can be 1,000,000 pCi/L of water while the radium-226 level might be
only a few pCi/L, radon in soil gases can be very elevated. I'd contact the
DOE's Environmental Measurements Lab [EML] in NYCity [the former HASL lab]
which used to have a radon studies group which performed numerous
environmental studies of radon emanation and pathways in the late 60s and
1970s related to mill tailings disposal in the West.
Stewart Farber
203 367-0791
==============
On Tue, 23 Dec 2003 09:27:51 +1100, Sonter Mark <sonterm@epa.nsw.gov.au>
wrote:
> Radon concentration "at depth" should be in equilibrium with the radium
> at
> the same depth.
>
> The "diffusion length" (1/e) in highly permeable soil has been taken to
> be
> (from memory) 2 or 3 metres. Try Tanner as an original reference.
>
> Less permeable covers can easily reduce diffusion length to a few
> centimetres.
>
> Mark Sonter
>
>
> -----Original Message-----
> From: Bjorn Cedervall [mailto:bcradsafers@HOTMAIL.COM]
> Sent: Tuesday, 23 December 2003 3:29 AM
> To: radsafe@list.vanderbilt.edu
> Subject: Radon profiles in the ground/soil
>
>
> I just picked up the two year old note by Chris H. from our archives. I
> wonder if anyone can give published references to radon 222 level data
> for different depths and for various types of soil (gradient description)
> . The context is "radioprotection of the environment". As examples I
> wonder what an earthworm say at a depth of 10-20 cm may be exposed to or
> a mole in the hole that is 50 cm below the surface. The context extends
> to radiation sensitivity data for bats (references). Any hints will be
> appreciated.
>
> My personal initiative only,
>
> Bjorn Cedervall bcradsafers@hotmail.com
> -----------------------------------------------------------------
> Radsafers,
> Radon concentrations a metre or so below the ground surface are
> typically a thousand times higher than in the air above ground, so there
> are concentration profiles due to diffusion out of the ground, which
> ensure continuity. Where there is an effective barrier to diffusion,
> like below a concrete basement, the concentration there builds up to a
> high equilibrium value, so that even small openings or cracks can cause
> an elevated concentration inside, compared with outdoors, particularly
> if the ventilation is poor.
>
> Ploughing would disturb the concentration profiles in the top soil
> layers and temporarily cause a faster release of radon gas until a new
> equilibrium has been established. According to e.g. IAEA definitions,
> should farming therefore be classed as a practice, and the farmer a
> potential radworker?
>
> Chris Hofmeyr
> chofmeyr@nnr.co.za
>
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