The relationship among naturally occurring radionuclides, geology, and geography: Tsodilo Hills, Botswana

ABSTRACT The area around Tsodilo Hills in the northwestern part of Botswana provided an opportunity to investigate the relationship among naturally occurring radionuclides, geology, and geography. In situ gamma ray surveys were carried out close to the hills in order to assess radionuclide concentrations. The concentrations of potassium, thorium, and uranium were measured and plotted with the help of Geographical Information System (GIS) software. The measurements showed high uranium concentrations and relatively low potassium and thorium concentrations. The highest concentrations were found to be 223 Bq/kg for uranium, 258 Bq/kg for potassium, and 31 Bq/kg for thorium. The measurements demonstrated that high uranium concentrations occurred in low-lying areas close to Tsodilo Hills. It is suggested that uranium concentrations were caused by alluvial deposition, mainly from the hills. Similar results were also found on a road leading to Tsodilo Hills. The article finally draws conclusions as to the distinctive geographical environment at Tsodilo Hills and the resultant unique distribution patterns of naturally occurring radionuclides at the site