Occurrence of radon in Riyadh groundwater supplies

A study of 222Rn levels in the ground water supplies of the capital city of Saudi Arabia (Riyadh) was carried out. Such sources contribute up to 34% of the total city water demand. Samples were collected from 90 wells (75 deep and 15 shallow) out of 161 that supply water to six water treatment plants and from three locations within each plant. All samples have low radon levels with an average concentration of 2.99 +/- 0.29 and 3.44 +/- 0.35 Bq L-1 (61.8 +/- 7.8 and 92.9 +/- 9.5 pCi L-1) for the deep and shallow well waters, respectively. Due to water cooling, radon level reduction in the treatment plants was found to be in the range of 74-96%. The plants' product waters were found to have very low levels of radon with an overall average value of 0.49 +/- 0.14 Bq L-1 (13.2 +/- 3.8 pCi L-1).