Radon as a naturally occurring tracer for the assessment of residual NAPL contamination of aquifers

Schubert, Michael; Paschke, Albrecht; Lau, Steffen; Geyer, W.; Knöller, Kay

doi:10.1016/j.envpol.2006.04.029

Cited by 57 publications

(25 citation statements)

References 23 publications

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“…Figure 5 illustrates data from the laboratory experiments of radon partitioning between gasoline and water. The radon-222 deficit factor (ÁC Rn ) is defined relative to the aqueous radon background concentration in the uncontaminated zone (S o ¼ 0) to the aqueous radon concentration in the same aquifer inside the NAPL source zone (S o 0) as follows (Hunkeler et al 1997;Davis et al 2003;Schubert et al 2007):…”

Section: Resultsmentioning

confidence: 99%

Radon as a Complementary Well‐Purging Indicator for Sampling Volatile Organic Compounds in a Petroleum‐Contaminated Aquifer

Han¹,

Kuo²,

Fan³

et al. 2007

Groundwater Monitoring Rem

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Ground water sampling protocols generally require that a well be purged prior to sampling. At present, the stability of conventional field measurements such as electrical conductivity, water temperature, and pH is used as a criterion to determine whether a well has been purged sufficiently to yield ''representative'' water quality samples. The primary objectives of this study were (1) to evaluate the validity of using the stability of conventional field measurements as a well-purging criterion for sampling volatile organic compounds (VOCs) in an aquifer region contaminated with free-phase gasoline and (2) to investigate the possibility of using radon-222 as a complementary well-purging indicator. Monitoring wells in a refinery were sampled at locations both upstream and inside an area contaminated with free-phase gasoline. The variation of conventional field measurements, VOCs, and radon-222 was evaluated with time and the number of casing volumes flushed. The results indicated that the number of casing volumes required for purging prior to sampling for VOCs is significantly larger in the gasoline-impacted area than in the uncontaminated aquifer. In addition, the stability of conventional field measurements alone was not sufficient to determine if a well had been purged sufficiently to yield representative VOC water quality samples. Radon-222 concentrations appeared to follow the temporal variation of dissolved VOCs in the gasoline-contaminated region of the aquifer, suggesting that radon-222 might be a complementary well-purging indicator if a field method were available for rapid assessment of dissolved radon concentrations.

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Section: Resultsmentioning

confidence: 99%

Radon as a Complementary Well‐Purging Indicator for Sampling Volatile Organic Compounds in a Petroleum‐Contaminated Aquifer

Han¹,

Kuo²,

Fan³

et al. 2007

Groundwater Monitoring Rem

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“…Outstanding examples are the localization and evaluation of non-aqueous phase liquid contamination in soils and aquifers (Schubert et al, 2001(Schubert et al, , 2007, the investigation of groundwater/surface water interaction processes (Burnett and Dulaiova, 2003;Schubert et al, 2008;Schmidt et al, 2009Schmidt et al, , 2010Schubert et al, 2010b), or the estimation of groundwater flow velocities (Cook et al, 1999;Hamada, 2000;Schubert et al, 2010a).…”

Section: Radon As Aqueous Tracer E General Remarksmentioning

confidence: 98%

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

Schubert¹,

Schmidt²,

Muller³

et al. 2011

Journal of Environmental Radioactivity

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“…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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Radon as a naturally occurring tracer for the assessment of residual NAPL contamination of aquifers

Cited by 57 publications

References 23 publications

Radon as a Complementary Well‐Purging Indicator for Sampling Volatile Organic Compounds in a Petroleum‐Contaminated Aquifer

Radon as a Complementary Well‐Purging Indicator for Sampling Volatile Organic Compounds in a Petroleum‐Contaminated Aquifer

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

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

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