Investigations of Soil as a Source of Indoor Radon

Sextro, R.G.; Moed, B.A.; Nazaroff, William W.; Revzan, K.L.; Nero, A.V.

doi:10.1021/bk-1987-0331.ch002

Cited by 33 publications

(21 citation statements)

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“…Figure Captions Only probes with complete data sets are included (7,8,5, and 4 probes in the high-, mid-, low-, and sub-slab-levels, respectively). Vertical bars indicate the standard error in the mean values.…”

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Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Garbesi¹,

Sextro²,

Fisk³

et al. 1993

Environ. Sci. Technol.

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The article has not been subjected to CARB review and does not necessarily reflect their views. Additional funding from NIEHS Superfund Program under Grant 5 P42 ES04699-05 is gratefully acknowledged.Previous studies have reported a large and persistent discrepancy between field measurements and model predictions of pressure-driven entry of soil gas into housesthe phenomenon that causes high concentrations of radon indoors. The discrepancy is often attributed to poor understanding of inherently complex field sites. This paper compares measurements of soil-gas entry made at a fullscale test basement located in natural solid with predictions of a three-dimensional finite difference model. The results corroborate the earlier findings, with the model underpredicting the soil-gas entry rate by a factor of 7. The effect of seasonal changes in soil conditions on soil-gas entry is also examined. Despite large seasonal changes in near-surface soil moisture content and air permeability, there is no observable effect on soil-gas entry, apparently because critical soil conditions near the soil-gas entry location in the structure floor remain relatively constant.

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“…Vertical bars indicate the standard error in the mean values. North 0.7 [9] 0.6 [3] 3 [-2] .x [5] (0. …”

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Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Garbesi¹,

Sextro²,

Fisk³

et al. 1993

Environ. Sci. Technol.

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“…Studies so far [e.g. Sextro et al, 1987; have shown that the soil adjacent to the house substructure is usually the dominant radon source in buildings with even moderately elevated radon concentrations. Radon is produced within the soil by the radioactive decay of radium, which is present in all earth-crustal materials, and is transported within the soil both by diffusion and advective flow of soil gas.…”

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Effects of periodic atmospheric pressure variation on radon entry into buildings

Tsang¹,

Narasimhan²

1992

J. Geophys. Res.

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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.

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“…9) Diffusion is major radon transport process in soil having low permeability whereas convective transport process tends to dominate in highly permeable soil. 10) For some geological situations, radon migrates long distances from its place of origin and can be detected by -Particle recorder at the earth's crust. 11 12) TANNER 13) has also suggested that squeezing in zones of compression causes a net upward and outward ow of soil-gas, thereby upward shifting of the near surface pro le of radon concentration.…”

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Radon Variations in Soil and Groundwater of Bhilagana Valley, Garhwal Himalaya, India

Choubey

Ahmad

Kamra

et al. 2010

Jpn. J. Health Phys.

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Radon measurements were made in the soil-gas and groundwater present in various lithological units and across the major tectonic zone (Munsiari and Bhatwari-Ramgarh Thrust) located between Ghansali and Ghuttu area in Bhilangana valley of the Garhwal Himalaya, India. High concentrations of radon were observed both in soil-gas and groundwater samples located close to the tectonic planes. Overall radon concentration in this area was found to be controlled by lithology, structure and associated uranium mineralization.

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Investigations of Soil as a Source of Indoor Radon

Cited by 33 publications

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Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Effects of periodic atmospheric pressure variation on radon entry into buildings

Radon Variations in Soil and Groundwater of Bhilagana Valley, Garhwal Himalaya, India

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