English abstract
Governorate of A'Dhahira is located in the north-west of Sultanate of Oman. It has AlMasrat Aquifer project that depends on groundwater which is considered the largest project not only in the country but also at the level of the GCC. Al Massarat Aquifer is a large groundwater resource in A'Dhahirah Governorate, which has been potentially developed for municipal water supplies and the supporting of agriculture and for domestic use in the region which serves most A'Dhahirah Governorate. The major purpose of this study is to provide data for the distribution of uranium series, thorium series and potassium in the groundwater of this project, also, to get some information about the radiological assessment at the sampling locations, and investigate the radon activity hazards and water quality of samples in that places. The concentrations of the natural radionuclides 4-8U, ---Th and K in 27 different water samples, divided into three categories well waters, tap waters and falajs, have been determined using (HPGe) and RAD7 detectors. Gamma ray spectrometric analysis was performed and the average concentrations obtained for each of the radionuclides 238U, 232Th and 40K in well water samples were found to be 0.29, 0.09 and 0.38 Bqi"!, respectively in Ibri, whereas, in Dhank, the average activities of 238U, 232Th and 40K were 0.31, 0.09 and 0.47 Bqla? respectively. The average activities of tap water samples were 0.35 Bal' of 238U, 0.11 Bql' of 232Th and 0.50 Bal' of 40K, while the concentrations of falaj samples for 238U, 232Th and 40K are 0.27, 0.03 and 0.39 in Bq l" respectively. The values calculated were lower than the recommended safe level by various international organizations. The radiological hazard indices of the samples were also calculated. The mean values obtained from well water samples are 0.87 BqL"?, 4.12E-01 nGyh;?, 0.51 uSv/y and 2.4 E-03 nGyh' for radium equivalent activity (Ra)eq, absorbed dose rates (D), annual effective dose rates (AED) and external hazard index (Hex) respectively, whereas, for tap water samples were found to be 1.06 BqL"', 4.18E-01 nGyh*', 0.62 uSv/y and 1.04E-04 nGyh' respectively. Falajs samples were the lowest compared to well and tap water samples with respect to radiological indices. All the health hazard indices are well below their recommended limits. The radon activity concentrations in well water samples were (2.3Bq/L ) the largest compared to other water types, whereas this value was much lower than that of values concern the average world (11.1 Bq/L). The annual effective dose resulting from radon in well waters, tap waters and falajs were significantly lower than UNSCEAR and WHO recommended limit for members of the public which is 0.025 mSv/y via inhalation and 0.002 mSv/y via ingestion. The study found no correlation between them. The measured values for all water samples in the study area suggest that the area is safe for the population and there is no significant threat to society.
