Re[2]: Radon flux from soils

[BRZGV@ccmail.ceco.com]

     Barometric pressure is the key.  Gas will also diffuse faster through 
     sandy soils than clays.
     
     Glen


______________________________ Reply Separator _________________________________
Subject: Re: Radon flux from soils
Author:  radsafe@romulus.ehs.uiuc.edu at INTERNET
Date:    6/28/96 11:36 PM


I would imagine the physical chemistry would play a large role.  If the 
temperature were raised, the gas dissolved in water would leach out.  I 
always like to think of a bottle of Pepsi (I am from the Carolina's) in a 
hot August day versus a cool November evening.  Which one would you bet 
will have more pressure upon opening?  I would imagine that a higher 
barometric pressure would force more gas to dissolve.  There may be 
another effect of moist soil.  I wonder if the water can "trap" the gas 
into these pore spaces within the soil, having the effect of lowering the 
amount of gas released?  Would this be more likely to happen in sandy 
type soil or fine soil?  Does it happen at all?
     
Robert A. Jones
RAJ6582@ACS.TAMU.EDU
     
Field@amrf-po.pmeh.uiowa.edu wrote:
> 
>           In response to D. Steva, there are likely numerous factors 
>           that affect radon emanation from soils.  Soil moisture,
>           barometric pressure and temperature are the first three 
>           that come to mind.
> 
>           I do agree with Ernest on the impact of moisture. We are
>           in our second year of performing  "state wide" outdoor radon 
>           monitoring.  Very preliminary findings do indicate that soil 
>           moisture is indeed a very important factor on radon
>           emanation from soils.
> 
>           Radon release from soils is most likely optimal when the
>           soil is moist. A radon atom that enters a water filled soil 
>           pore space has a good chance of ending its recoil in the
>           water.  If the soil is "moist", the radon is transferred 
>           to the air in the larger pore spaces.  If the larger pore
>           spaces are filled with water, little transport of the radon 
>           will occur.
> 
>           Temperature is probably of lessor importance.  However, 
>           researchers have noted a 55% increased radon exhalation 
>           rate for a soil sample when the soil temperature was
>           increased from 5 to 50 degrees C. However, I would suggest
>           this type of a temperature increase is not common in natural 
>           conditions.
> 
>           Barometric Pressure is also a factor in the radon flux from 
>           the soil surface.  See Clements and Wilkening (Journal of
>           Geophysical Research, Vol. 79, 1974; Schery et al., 
>           Journal of Geophysical Research, Vol 87, 1982)
> 
>          There are also probably other factors such as soil type, etc. 
> 
>           Regards, Bill