The correlation between bedrock uranium and dissolved radon in ground water of a fractured carbonate aquifer in southwestern Ohio
- Wright State Univ., Dayton, OH (United States)
- Miami Univ., Oxford, OH (United States). Dept. of Geology
- Ohio State Univ., Columbus, OH (United States). Nuclear Reactor Facility
Two hypotheses have previously been proposed for the source of elevated radon in ground water of southwestern Ohio: (1) penecontemporaneous uranium at the Silurian-Ordovician unconformity, and/or (2) parent radionuclides transported from fragments of uranium-rich Ohio Shale within the glacial drift above the aquifer. To further test the first hypothesis, vertical profiles of dissolved radon in ground water and uranium in rock cores were obtained at two locations immediately underlain by the Silurian/Ordovician unconformity. Radon concentrations exceeding 1,000 pCi/l occurred in zones where the bedrock had uranium concentrations greater than 1.5 ppm. Radon concentrations of less than 500 pCi/l occurred in zones where the rock had uranium concentrations below 0.25 ppm. A log-linear regression model between uranium and radon had a correlation coefficient of 0.82. Three aspects of the results support the hypothesis that the source is transported, although not necessarily from fragments of Ohio Shale. First, the high uranium-radon zones did not occur consistently or exclusively at the Silurian/Ordovician unconformity. Second, the high uranium-radon zones are correlated to fracture zones having a higher hydraulic conductivity and thus appear to be related to the zones of greater flow and transport. Third, the amount of uranium-radon disequilibrium increases exponentially with increasing hydraulic conductivity. The hypothesis of a penecontemporaneous source, not supported by their study, arose when previous investigators conducted regional surveys of domestic wells and springs and found a correspondence between elevated radon and the location of the Silurian-Ordovician unconformity.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 31789
- Journal Information:
- Ground Water, Vol. 33, Issue 2; Other Information: PBD: Mar-Apr 1995
- Country of Publication:
- United States
- Language:
- English
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