Determination of radon distribution patterns in the upper soil as a tool for the localization of subsurface NAPL contamination

Schubert, Michael; Peña, P.; Balcázar, M.; Meißner, Ralph; López, Abraham Sánchez; Flores, J.H.

doi:10.1016/j.radmeas.2005.04.020

Cited by 34 publications

(12 citation statements)

References 5 publications

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“…Recently, Schubert et al (2005) used the high partitioning coefficients between non-aqueous phase-liquids (NAPLs) and air/water to infer the presence of subsurface NAPL. Radon concentrations are always higher in soil gas than in gases exhaling from mud volcanoes in SW Taiwan (T. F. Yang, unpublished data).…”

Section: Very Low Radon Concentrationmentioning

confidence: 99%

Methane Venting in Gas Hydrate Potential Area Offshore of SW Taiwan: Evidence of Gas Analysis of Water Column Samples

Yang¹,

Chuang²,

Lin³

et al. 2006

Terr. Atmos. Ocean. Sci.

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Section: Very Low Radon Concentrationmentioning

confidence: 99%

Methane Venting in Gas Hydrate Potential Area Offshore of SW Taiwan: Evidence of Gas Analysis of Water Column Samples

Yang¹,

Chuang²,

Lin³

et al. 2006

Terr. Atmos. Ocean. Sci.

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“…The Rn monitor was fitted with a canister filled with drierite (97% CaS0 4 + 3% CoCl 2 ) and a hydrophobic Teflon® filter to keep humidity within the instrument at a minimum, and to prevent fine particles from entering the ionization chamber. Soil air was collected with the help of a stainless-steel hollow probe which was hammered into the soil, down to a depth of 75-100 cm in order to minimize the influence of atmospheric factors (Schubert et al, 2005). The bottom of the hollow probe was fitted with a stainless-steel lost tip.…”

Section: Methodsmentioning

confidence: 99%

“…Schubert et al ( , 2007a carried out laboratory experiments to determine the partition coefficients /< N APL/W and /< N APL/AIR for commercial mixtures of petroleum hydrocarbons (gasoline, diesel, kerosene) and demonstrated the ability of NAPL accumulations to act as geochemical traps for Rn. The resulting reduction in Rn activity in the soil air of the vadose zone should therefore indicate the presence of underlying levels with high hydrocarbon saturation (Hunkeler et al, 1997;Semprini et al, 2000;Schubert et al, 2001Schubert et al, , 2005Schubert et al, , 2007b. Field tests and laboratory experiments published by Schubert et al (2007c), Fan et al (2007), Davis et al, (2002Davis et al, ( , 2003 and Semprini et al (2000) suggest that Rn can be used as a non-conservative tracer to estimate LNAPL saturation in the subsurface.…”

Section: Jj Physico-chemical Backgroundmentioning

confidence: 99%

Field validation of radon monitoring as a screening methodology for NAPL-contaminated sites

García-González

Ortega

Chacón

et al. 2008

Applied Geochemistry

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Screening methodologies aim at improving knowledge about subsurface contamination processes before expensive intrusive operations, i.e. drilling and core-sampling, well installation and development, sampling of groundwater and free-phase product, are implemented. Blind field tests carried out at a hydrocarbon storage and distribution center in NE Spain suggest that Rn monitoring can be effectively used to locate the boundaries of subsurface accumulations of NAPLs. Sixty seven measurements of Rn in soil air were performed with a SARAD RTM 2100 current-ionization alpha-particle spectrometer following a 10 m square grid. Reductions of 222 Rn concentration above a pool of LNAPL due to the preferential partition of Rn into the organic phase were spatially analyzed and resolved to yield the surface contour of the NAPL source zone. This surface trace of the source zone agreed well with the extent and situation inferred from measurements of free-phase thickness taken at eight monitoring wells at the site. Moreover, the good repeatability (as measured by replicate measurements at the same sampling point) and spatial resolution of the technique suggest that the boundaries of the plume can be delineated at the sub-decametre level.

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“…Direct detection of VOCs is; however, only possible when dealing with volatile NAPLs and is thus of no use in the case of contamination with diesel fuel, kerosene or engine oil, for example (Schubert et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Laboratory-scale experimental and modelling investigations of 222Rn profiles in chemically heterogeneous LNAPL contaminated vadose zones

Cohen

Bernachot

et al. 2019

Science of The Total Environment

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The potential of LNAPL delineation by 222 Rn soil-gas monitoring in a chemically heterogeneous vadose zone was investigated in this study based on laboratory (batch and columns) experiments and numerical modeling. An enhanced version of the MIN3P reactive transport code was used to simulate Rn transport in both uncontaminated and NAPL-contaminated vadose zones and results were validated against analytical solutions and laboratory experiments. Results show that 222 Rn activity profiles are mainly controlled by porous media 222 Rn production, vadose zone fluid saturations and especially the type and distribution of NAPL in contaminated areas. The results also show that decreases in 222 Rn activity and variations in activity gradients provide evidence for the presence and saturation of NAPL. This study demonstrates that LNAPL delineation via 222 Rn gas surveys at contaminated sites works best, if gas measurements extend as deep as possible and include regions where 222 Rn activity decreases due to elevated NAPL. In addition, collection and analysis of depth-discrete gas samples allows the characterization of vertical NAPL distribution based on the 222 Rn activity gradient. The determination of 222 Rn production in the unsaturated zone, as well as water capillary pressure curves are of key importance in enabling the discrimination of an uncontaminated from a NAPL-contaminated area.

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Determination of radon distribution patterns in the upper soil as a tool for the localization of subsurface NAPL contamination

Cited by 34 publications

References 5 publications

Methane Venting in Gas Hydrate Potential Area Offshore of SW Taiwan: Evidence of Gas Analysis of Water Column Samples

Methane Venting in Gas Hydrate Potential Area Offshore of SW Taiwan: Evidence of Gas Analysis of Water Column Samples

Field validation of radon monitoring as a screening methodology for NAPL-contaminated sites

Laboratory-scale experimental and modelling investigations of 222Rn profiles in chemically heterogeneous LNAPL contaminated vadose zones

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