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Radon in Groundwater- Influencing Factors and Prediction Methodology for a Swedish Environment
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis presents a method for predicting radon (222Rn) levels in groundwater on a general scale, within an area of approximately 185 x 145 km2. The method applies to Swedish conditions, where 222Rn is the main contributor to natural radioactivity. Prediction of radon potential in groundwater is complex because there are many different factors affecting radon content, including geochemical and flow processes. The proposed method is based on univariate and multivariate statistical analyses and investigated the influence of different factors such as bedrock, soils, uranium distribution, altitude, distance to fractures and land use. A statistical variable based method (the RV method) was used to estimate risk values related to different radon concentrations. The method was calibrated and tested on more than 4400 drilled wells in Stockholm County. The weighted index (risk value) estimated by the RV method provided a fair prediction of radon potential in groundwater on a general scale. The RV method was successful in estimating the median radon concentration within 12 subregions (at a local scale, each of area 25 x 25 km2), based on weighted index values obtained from half of all wells tested. A high correlation between risk values and median radon concentrations was demonstrated. The factors bedrock, altitude, distance to fracture zone and distribution of uranium in bedrock were found to be significant in the prediction approach on a general scale. Visual data mining, which comprised analysis of 3D images, was a useful tool for data exploration but could not be used as an independent method for drawing conclusions regarding radon in groundwater. Results of a field study based on 38 drilled wells on the island of Ljusterö in the Stockholm archipelago showed that 222Rn concentrations in groundwater were weakly correlated to the parent elements (226Ra and 238U) in solution.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , vii, 23 p.
Series
Trita-LWR. LIC, ISSN 1650-8629 ; 2032
Keyword [en]
Radon, Grondwater, GIS, RV method, Multivariate statistics
National Category
Water Engineering
Identifiers
URN: urn:nbn:se:kth:diva-491ISBN: 91-7178-208-7 (print)OAI: oai:DiVA.org:kth-491DiVA: diva2:14203
Presentation
2005-11-21, V21, mark-och vattenteknik, Teknikringen 72, 1tr, KTH campus, 10:00
Opponent
Supervisors
Note
QC 20101221Available from: 2005-11-11 Created: 2005-11-11 Last updated: 2010-12-21Bibliographically approved
List of papers
1. A prediction method for radon in groundwater using GIS and multivariate statistics
Open this publication in new window or tab >>A prediction method for radon in groundwater using GIS and multivariate statistics
2006 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 367, no 2-3, 666-680 p.Article in journal (Refereed) Published
Abstract [en]

Radon (Rn-222) in groundwater constitutes a source of natural radioactivity to indoor air. It is difficult to make predictions of radon levels in groundwater due to the heterogeneous distribution of uranium and radium, flow patterns and varying geochemical conditions. High radon concentrations in groundwater are not always associated with high uranium content in the bedrock, since groundwater with a high radon content has been found in regions with low to moderate uranium concentrations in the bedrock. This paper describes a methodology for predicting areas with high concentrations of Rn-222 in groundwater on a general scale, within an area of approximately 185 x 145 km(2). The methodology is based on multivariate statistical analyses, including principal component analysis and regression analysis, and investigates the factors of geology, land use, topography and uranium (U) content in the bedrock. A statistical variable based method (the RV method) was used to estimate risk values related to different radon concentrations. The method was calibrated and tested on more than 4400 drilled wells in Stockholm County.

The results showed that radon concentration was clearly correlated to bedrock type, well altitude and distance from fracture zones. The weighted index (risk value) estimated by the RV method provided a fair prediction of radon potential in groundwater on a general scale. Risk values obtained using the RV method were compared to radon measurements in 12 test areas (on a local scale, each of area 25 x 25 km(2)) in Stockholm County and a high correlation (r=-0.87) was observed. The study showed that the occurrence and spread of radon in groundwater are guided by multiple factors, which can be used in a radon prediction method on a general scale. However, it does not provide any direct information on the geochemical and flow processes involved.

Keyword
radon, groundwater, hard rock, GIS, multivariate statistics, risk variable method
National Category
Water Engineering
Identifiers
urn:nbn:se:kth:diva-8776 (URN)10.1016/j.scitotenv.2006.02.044 (DOI)000240042700013 ()2-s2.0-33746265353 (Scopus ID)
Note
QC 20101221Available from: 2005-11-11 Created: 2005-11-11 Last updated: 2017-12-14Bibliographically approved
2. Use of GIS and 3D visualisation to investigate radon problem in groundwater
Open this publication in new window or tab >>Use of GIS and 3D visualisation to investigate radon problem in groundwater
2005 (English)In: 10th Scandinavian Research Conference on Geographical Information Science, Scangis, Stockholm, Sweden, June 13-15 / [ed] H. Hauska and H. Tveite, 2005, 39-51 p.Conference paper, Published paper (Refereed)
Abstract [en]

Radon is radioactive and its origin in groundwater is principally linked to the content of its parent element, uranium or radium in bedrocks. However, an on-going research at the Department of Land andWater Resources Engineering shows that a number of factors other than bedrock may potentially influence the radon concentration in groundwater.These factors include: steepness of the terrain, soil type, distribution of uranium and the effect of fracture zone. This article presents an application of GIS and 3D visualisation to explore the radon problem in groundwater. After a GIS pre-processing, 3D visualisations of the thematic data were produced in order to see if the visual approach would be useful to preliminary identify possible relationships between the high concentration of radon and other parameters.

National Category
Water Engineering
Identifiers
urn:nbn:se:kth:diva-8777 (URN)2-s2.0-33746200929 (Scopus ID)91-7323-126-6 (ISBN)
Conference
ScanGIS'2005, Stockholm, Sweden. June 13-15
Note
QC 20101221Available from: 2005-11-11 Created: 2005-11-11 Last updated: 2010-12-21Bibliographically approved
3. Uranium and radon in groundwater- An overview of the problem
Open this publication in new window or tab >>Uranium and radon in groundwater- An overview of the problem
2005 (English)In: Proceedings of the 6th EWRA International Conference on Water Resources., 2005, 1-17 p.Conference paper, Published paper (Refereed)
Abstract [en]

Radioactive elements occur naturally in our environment. A long-term exposure to the radioactive gasradon (222Rn) can lead to lung cancer. In Sweden, 500 cases of lung cancer are registered every year,due to inhalation of radon gas. The parent element of 222Rn is uranium (238U), which is found in soilsand bedrocks in varying concentrations. 238U is also radioactive but causes more harm due to its toxicity;kidney problems arise when uranium is ingested. In areas where municipal water is not available, wells aredrilled in bedrocks to extract water for drinking purposes and other uses. Groundwater from wells drilled inrocks rich in uranium (e.g. granite rocks) have shown tendency to have both high radon and uranium concentrations.However, the opposite is not always true; In Stockholm, concentrations of radon exceeding theSwedish regulatory limit of 1000 Bq/l have been observed in bedrocks containing low concentrations ofuranium (0-2 ppm). The uranium concentration in water is usually not routinely measured as an indicator ofwater quality despite its toxicity. A uranium concentration as high as 445 microg/l (WHO limit is 15 microg/l)was observed in one private well in Stockholm, The heterogeneous conditions in the subsurface (geochemistry,groundwater flow, geology and fracture system) make the development of a risk prediction model, that canbe applied at large scale, complex. This paper presents an overview of the problem of natural radioactivity inour drinking water.

Keyword
Radon, Uranium, Groundwater, Risk prediction.
National Category
Water Engineering
Identifiers
urn:nbn:se:kth:diva-8778 (URN)
Conference
6th EWRA international conference on water resources, Sharing a common vision of our water resources, 7-10 September 2005, Menton - France
Note
QC 20101221Available from: 2005-11-11 Created: 2005-11-11 Last updated: 2012-02-14Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
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Output format
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