Two dimensional diffusion theory of trace gas emission into soil chambers for flux measurements

Sahoo, B. K.; Mayya, Y. S.

doi:10.1016/j.agrformet.2010.05.009

Cited by 69 publications

(33 citation statements)

References 26 publications

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“…As the radon concentration around the sample grow, radon atom diffusing back to the material due to porous nature of the materials thus lowering the equilibrium radon concentration inside the accumulator. This phenomenon was known as back diffusion and causes an underestimate of true radon exhalation rate (Petropoulos, Anagnostakis, & Simopoulos, 2001;Sahoo & Mayya, 2010). Due to this problem, the sealed cup technique suffers from some uncertainty in the results of exhalation rates.…”

Section: Introductionmentioning

confidence: 97%

Radon exhalation rates corrected for leakage and back diffusion – Evaluation of radon chambers and radon sources with application to ceramic tile

Abo-Elmagd

2014

Journal of Radiation Research and Applied Sciences

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Leakage rateBack diffusion rate Radon exhalation rate Radon chambers a b s t r a c tThe natural radon decay, leakage and back diffusion are the main removal processes of radon from its container. Ignoring these processes leads to underestimate the measured value of radon related parameters like exhalation rate and radium content. This work is aimed to evaluate two different radon chambers through determining their leakage rate l v and evaluation of radon source by determine its back diffusion rate l b inside the evaluated radon chambers as well as a small sealed cup. Two different methods are adapted for measuring both the leakage rate and the back diffusion rate. The leakage rate can be determined from the initial slope of the radon decay curve or from the exponential fitting of the whole decay curve. This can be achieved if a continuous monitoring of radon concentration inside the chamber is available. Also, the back diffusion rate is measured by sealing the radon source in the chamber and used the initial slope of the buildup curve to determine l b and therefore the exhalation rate of the source. This method was compared with simple equation for l b based on the ratio of the source to the chamber volume. The obtained results are applied to ceramic tile as an important radon source in homes. The measurement is targeted the ceramic glaze before and after firing as well as the obtained tile after adhere the glaze on the tile main body. Also, six different tile brands from Egyptian market are subjected to the study for comparison.

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Section: Introductionmentioning

confidence: 97%

Radon exhalation rates corrected for leakage and back diffusion – Evaluation of radon chambers and radon sources with application to ceramic tile

Abo-Elmagd

2014

Journal of Radiation Research and Applied Sciences

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“…To solve this problem, conditions (4) or (5) provide for correct problem setting. Schematically, it is possible to show the model of a well of the underground storage, using boundary conditions [20] in the following form (which corresponds to (5)) ( Fig. 4).…”

Section: Results Of Research Into Modeling Of Filtering Processmentioning

confidence: 99%

Estimation of gas losses based on the characteristic of the state of wells of dashava storage

Olijnyk

Chernova

2017

EEJET

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“…We are not aware of a comparable solution for situations where the soil acts as both a sink and/or a source. Sahoo and Mayya [] offer a potential solution by solving a two‐dimensional nonsteady state diffusion model, but the solution is quite complicated and cannot be easily implemented in existing software packages such as OpenBUGS or JAGS. However, one could use a simpler (e.g., exponential) equation [ Hutchinson and Mosier , ; Sahoo and Mayya , ] that approximates the complicated analytical solution, and our work suggests that this should be implemented in a hierarchical statistical framework.…”

Section: Discussionmentioning

confidence: 99%

Quantifying and reducing uncertainties in estimated soil CO₂fluxes with hierarchical data‐model integration

et al. 2016

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Nonsteady state chambers are often employed to measure soil CO2 fluxes. CO2 concentrations (C) in the headspace are sampled at different times (t), and fluxes (f) are calculated from regressions of C versus t based on a limited number of observations. Variability in the data can lead to poor fits and unreliable f estimates; groups with too few observations or poor fits are often discarded, resulting in “missing” f values. We solve these problems by fitting linear (steady state) and nonlinear (nonsteady state, diffusion based) models of C versus t, within a hierarchical Bayesian framework. Data are from the Prairie Heating and CO2 Enrichment study that manipulated atmospheric CO2, temperature, soil moisture, and vegetation. CO2 was collected from static chambers biweekly during five growing seasons, resulting in >12,000 samples and >3100 groups and associated fluxes. We compare f estimates based on nonhierarchical and hierarchical Bayesian (B versus HB) versions of the linear and diffusion‐based (L versus D) models, resulting in four different models (BL, BD, HBL, and HBD). Three models fit the data exceptionally well (R2 ≥ 0.98), but the BD model was inferior (R2 = 0.87). The nonhierarchical models (BL and BD) produced highly uncertain f estimates (wide 95% credible intervals), whereas the hierarchical models (HBL and HBD) produced very precise estimates. Of the hierarchical versions, the linear model (HBL) underestimated f by ~33% relative to the nonsteady state model (HBD). The hierarchical models offer improvements upon traditional nonhierarchical approaches to estimating f, and we provide example code for the models.

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Two dimensional diffusion theory of trace gas emission into soil chambers for flux measurements

Cited by 69 publications

References 26 publications

Radon exhalation rates corrected for leakage and back diffusion – Evaluation of radon chambers and radon sources with application to ceramic tile

Radon exhalation rates corrected for leakage and back diffusion – Evaluation of radon chambers and radon sources with application to ceramic tile

Estimation of gas losses based on the characteristic of the state of wells of dashava storage

Quantifying and reducing uncertainties in estimated soil CO₂fluxes with hierarchical data‐model integration

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Two dimensional diffusion theory of trace gas emission into soil chambers for flux measurements

Cited by 69 publications

References 26 publications

Radon exhalation rates corrected for leakage and back diffusion – Evaluation of radon chambers and radon sources with application to ceramic tile

Radon exhalation rates corrected for leakage and back diffusion – Evaluation of radon chambers and radon sources with application to ceramic tile

Estimation of gas losses based on the characteristic of the state of wells of dashava storage

Quantifying and reducing uncertainties in estimated soil CO2fluxes with hierarchical data‐model integration

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Resources

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Quantifying and reducing uncertainties in estimated soil CO₂fluxes with hierarchical data‐model integration