LAUSR

In this study, the levels of natural radioactivity in the groundwater samples collected from 26 different locations in Al-Zulfi, Al-Qassim and Al-Majmaah regions were determined. The estimated average values of 226Ra, 228Ra, 40K, gross α and gross β activities in the samples were 0.87 Bq L−1, 1.33 Bq L−1, 4.22 Bq L−1, 36.82 mBq L−1 and 831.91 mBq L−1, respectively. We found that age-dependent effective ingestion dose from radionuclides in all samples were higher than WHO recommended levels of 0.1 µSv y−1 for adults 0.2 µSv y−1 for children and 0.26 µSv y−1 for infants while 20 sampling locations have age-dependent effective dose equivalent from β contributors were higher than WHO recommended level of 0.1 mSv y−1.