eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2016-09-25 13 3 1327 1332 10.13005/bbra/2273 15929 article Al-Ghamdi 1 A. Al-Muqrin 1 Princess Nourah University, College of Science, department of Physics, Riyadh, KSA. The purpose of this study was to determine the activity concentrations of radium isotopes (²²⁶Ra and ²²⁸Ra) in groundwaters from some selected wells in Saudi Arabia. These wells are located in different regions of Saudi Arabia. The relationship between the activity concentration of radium and the water chemical compositionin the investigated wells was also investigated.The radium isotopes were measured by gamma spectrometry using high purity germanium detector,after radiochemical separation of the isotopes with ion-exchange chromatography using a strong cation resin. The mean activity concentration of ²²⁶Ra was 9.7 pCi/L and for²²⁸Ra, it was 9.8 pCi/L. A relatively higher values of radium activities were found in Qaseem, Al Jawf and Tabouk. The ²²⁸Ra/²²⁶Ra activity ratio had an average value of 1.2. The chemical analyses showed thatgood correlationshave been observed between the radium activities and the total dissolved soilds and dissolved oxygen inthe investigated groundwaters. Most of the analyzed groundwater samples were below the maximum contaminant level of the combined radium (²²⁶Ra and ²²⁸Ra)proposed by EPA for drinking water. The data obtained from the activity concentrations of the investigatedradium isotopes are comparable to the results reported in literature for radium in the Kingdom of Saudi Arabia, and can be used to establish a radiological baseline radioactivity map for radium radioactivity levels in groundwater of these regions. https://www.biotech-asia.org/vol13no3/radium-activity-levels-in-groundwater-in-saudi-arabia-and-relationship-with-some-water-chemical-constituents/ groundwater; radium; Saudi Arabia; gamma spectrometry; alpha spectrometry; TDS; dissolved oxygen