Testing for variations in radon soil gas emissions over glacial till in Union County, Ohio

Abstract

Many recent studies in Ohio on radon in glacial deposits have concluded that substrate characteristics (which includes both sediment and the underlying bedrock) have a primary influence on detected levels of radon soil gas. Throughout Ohio, till deposited over shale, particularly the Ohio Shale, produces consistantly high levels of radon due to its high uranium content available to circulating groundwater. However, in till overlying limestone or sandstone, factors other than bedrock become more important influences on radon levels. The bedrock of Union County, Ohio consists mostly of limestone and is covered by glacial deposits of variable thickness. A study of radon soil gas emissions in Union County was done for this thesis to get a better understanding of the effects of variable glacial till characteristics on detected soil gas levels. The results of this study indicate that permeability, proximity to the watertable, and the amount of uranium-bearing material in the till are the most important factors which influence variations of radon soil gas in this county. These findings also suggest that radon is not an effective tool to locate fractures and areas of high permeability in glacial deposits.