SOIL RADON STUDIES IN ATLANTA, GEORGIA

The area around Atlanta, Georgia has some of the highest radon levels in the southeastern U.S. In this work, we present the soil characterization analysis aspects of Georgia State University’s (GSU) Radon Testbed project, funded by the U.S. Department of Agriculture (USDA) and the National Science Foundation (NSF). The Radon Testbed project entails designing, implementing and deploying a real-time wireless under-the-soil radon gas measurement sensor testbed. The testbed will constitute 100-200 sensor-nests — a collection of environmental physical and gas sensors in addition to radon — deployed around five study areas including GSU campuses in Atlanta, Clarkston, Decatur and Dunwoody, and at Stone Mountain.

Ground Penetrating Radar (GPR) surveys were performed at each of the radon monitoring sites to determine depth to water table and bedrock. A Geophysical Survey System Incorporated (GSSI) GPR system with a SIR4000 controller was paired with a 200 MHz antenna. The data will be used to evaluate how the thickness of the vadose zone and the depth to bedrock serve as controls on the occurrence and magnitude of radon concentrations.

With a primary goal to understand the relationship between under-the-soil radon gas emanation and other physical-chemical characteristics of the soil, we have embarked on an extensive soil characterization study at the five deployment sites. This includes preliminary field sampling at 25-30 point locations at each site, along a grid pattern, to analyze soil bulk density, porosity and soil texture, using standardized methods from the USDA: Soil Survey Field and Laboratory Methods manual and the Natural Resources Conservation Services (NRCS). We will repeat these analyses using soil core samples collected from professional soil-core extraction methods with target depths from 2 inches to 6 feet. We will use the soil samples from the deepest horizons to test for other elemental concentrations, including radioactive elements, such as Uranium, Thorium, Radium and Potassium, through inductively coupled plasma mass spectrometry (ICP-MS).