Measuring radon-222 in soil gas with high spatial and temporal resolution

In order to exploit 222Rn as a naturally-occurring tracer in soils we need to sample and measure radon isotopes in soil gas with high spatial and temporal resolution, without disturbing in situ activity concentrations and fluxes. Minimization of sample volume is key to improving the resolution with...

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Main Authors: Huxtable, Darren, Read, David, Shaw, George
Format: Article
Published: Elsevier 2017
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Online Access:https://eprints.nottingham.ac.uk/38559/
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author Huxtable, Darren
Read, David
Shaw, George
author_facet Huxtable, Darren
Read, David
Shaw, George
author_sort Huxtable, Darren
building Nottingham Research Data Repository
collection Online Access
description In order to exploit 222Rn as a naturally-occurring tracer in soils we need to sample and measure radon isotopes in soil gas with high spatial and temporal resolution, without disturbing in situ activity concentrations and fluxes. Minimization of sample volume is key to improving the resolution with which soil gas can be sampled; an analytical method is then needed which can measure radon with appropriate detection limits and precision for soil gas tracer studies. We have designed a soil gas probe with minimal internal dead volume to allow us to sample soil gas volumes of 45 cm3. Radon-222 is extracted from these samples into a mineral oil-based scintillation cocktail before counting on a conventional liquid scintillation counter. A detection limit of 320 Bq m-3 (in soil gas) is achievable with a one hour count. This could be further reduced but, in practice, is sufficient for our purpose since 222Rn in soil gas typically ranges from 2,000 - 50,000 Bq m-3. The method is simple and provides several advantages over commonly used field-portable instruments, including smaller sample volumes, speed of deployment and reliability under field conditions. The major limitation is the need to count samples in a liquid scintillation counter within 2 – 3 days of collection, due to the short (3.824 day) radioactive half-life of 222Rn. The method is not applicable to the very short-lived (55 second half-life) 220Rn.
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spelling nottingham-385592020-05-04T19:58:43Z https://eprints.nottingham.ac.uk/38559/ Measuring radon-222 in soil gas with high spatial and temporal resolution Huxtable, Darren Read, David Shaw, George In order to exploit 222Rn as a naturally-occurring tracer in soils we need to sample and measure radon isotopes in soil gas with high spatial and temporal resolution, without disturbing in situ activity concentrations and fluxes. Minimization of sample volume is key to improving the resolution with which soil gas can be sampled; an analytical method is then needed which can measure radon with appropriate detection limits and precision for soil gas tracer studies. We have designed a soil gas probe with minimal internal dead volume to allow us to sample soil gas volumes of 45 cm3. Radon-222 is extracted from these samples into a mineral oil-based scintillation cocktail before counting on a conventional liquid scintillation counter. A detection limit of 320 Bq m-3 (in soil gas) is achievable with a one hour count. This could be further reduced but, in practice, is sufficient for our purpose since 222Rn in soil gas typically ranges from 2,000 - 50,000 Bq m-3. The method is simple and provides several advantages over commonly used field-portable instruments, including smaller sample volumes, speed of deployment and reliability under field conditions. The major limitation is the need to count samples in a liquid scintillation counter within 2 – 3 days of collection, due to the short (3.824 day) radioactive half-life of 222Rn. The method is not applicable to the very short-lived (55 second half-life) 220Rn. Elsevier 2017-02 Article PeerReviewed Huxtable, Darren, Read, David and Shaw, George (2017) Measuring radon-222 in soil gas with high spatial and temporal resolution. Journal of Environmental Radioactivity, 167 . pp. 36-42. ISSN 1879-1700 radon-222; 222Rn; soil gas; tube sampler; liquid scintillation counting; ionisation chamber http://www.sciencedirect.com/science/article/pii/S0265931X16305434 doi:10.1016/j.jenvrad.2016.11.003 doi:10.1016/j.jenvrad.2016.11.003
spellingShingle radon-222; 222Rn; soil gas; tube sampler; liquid scintillation counting; ionisation chamber
Huxtable, Darren
Read, David
Shaw, George
Measuring radon-222 in soil gas with high spatial and temporal resolution
title Measuring radon-222 in soil gas with high spatial and temporal resolution
title_full Measuring radon-222 in soil gas with high spatial and temporal resolution
title_fullStr Measuring radon-222 in soil gas with high spatial and temporal resolution
title_full_unstemmed Measuring radon-222 in soil gas with high spatial and temporal resolution
title_short Measuring radon-222 in soil gas with high spatial and temporal resolution
title_sort measuring radon-222 in soil gas with high spatial and temporal resolution
topic radon-222; 222Rn; soil gas; tube sampler; liquid scintillation counting; ionisation chamber
url https://eprints.nottingham.ac.uk/38559/
https://eprints.nottingham.ac.uk/38559/
https://eprints.nottingham.ac.uk/38559/