View unanswered posts | View active topics It is currently Fri Apr 19, 2019 8:20 pm



Reply to topic  [ 3 posts ] 
 Effects of atmospheric pressure variation on radon 
Author Message
Moderator
User avatar

Joined: Mon Jan 28, 2013 7:40 pm
Posts: 2837
Location: Illinois
Harlan,

I found this last night and thought you would find it interesting as I have:

Quote:
Using a mathematical model, we have investigated the temporal variations of radon entry into a house basement in the presence of time-dependent periodic variations of barometric pressure as well as a persistent small steady depressurization within the basement. The tool for our investigation is an integral finite difference numerical code which can solve for both diffusive and advective flux of radon in the soil gas which is treated as a slightly compressible fluid. Two different boundary conditions at the house basement are considered: (1) a dirt floor basement so that diffusion is equally or more important than advective transport, and (2) an “impermeable” cement basement except for a 1-cm-wide crack near the perimeter of the basement floor; in which case, advective transport of radon flux dominates. Two frequencies of barometric pressure fluctuation with representative values of amplitudes, based on a Fourier decomposition of barometric pressure data, were chosen in this study: one with a short period of 0.5 hour with pressure amplitude of 50 Pa, the other a diurnal variation with a period of 24 hours with the typical pressure amplitude of 250 Pa. For a homogeneous soil medium with soil permeability to air between 10−13 and 10−10 m2, we predict that the barometric fluctuations increase the radon entry into the basement by up to 120% of the steady radon inflow into the basement owing to a steady depressurization of 5 Pa. If soil permeability heterogeneity is present, such as the presence of a thin layer of higher permeability aggregate immediately below the basement floor, radon flux due to atmospheric pumping is further increased. Effects of pressure pumping on radon entry are also compared to diffusion-only transport when the steady depressurization is absent. It is found that contribution to radon entry is significant for the basement crack configuration. In particular, for pressure pumping at 0.5-hour period and for a homogeneous medium of permeability of 10−10 m2, the radon entry is a factor of 10 larger than that predicted by the diffusion-only transport. This may help to explain indoor radon concentrations during times of low steady state driving force. Extending beyond radon transport, the results of this case study establish the importance of transient advective transport resulting from atmospheric pressure variation. These results may have relevance in the estimations of the transfer of trace gases such as methane and nitrous oxide across the soil-atmosphere interface and their impact on global climate changes.


http://onlinelibrary.wiley.com/doi/10.1029/92JB00707/abstract

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Sat Apr 13, 2013 3:28 pm
Profile
Moderator
User avatar

Joined: Mon Jan 28, 2013 7:40 pm
Posts: 2837
Location: Illinois
Harlan,

If you thought the information above was interesting and useful, check this out:

http://www.google.com/url?sa=t&rct=j&q=barmetric%20pressure%20radon&source=web&cd=1&cad=rja&ved=0CD0QFjAA&url=http%3A%2F%2Fwww.aarst.org%2Fproceedings%2F1993%2F1993_39_Wind_Barometric_Pressure_Effects_on_Radon_in_Two_M.pdf&ei=tRNrUaPsPMLF0gGV04H4Bw&usg=AFQjCNFG1O8g0Xf-oHLQe7ezysQmmMMOjg

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Sun Apr 14, 2013 3:39 pm
Profile
Site Admin
User avatar

Joined: Mon Jan 28, 2013 6:51 pm
Posts: 744
Location: Arkansas
I like the articles, wind and pressure together. Interesting...


Mon Apr 15, 2013 3:37 pm
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 3 posts ] 

Who is online

Users browsing this forum: No registered users and 15 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group
Designed by STSoftware.