Natural Radioactivity of Environmental Samples and their Impact on the Population at Assalamia-Alhomira Area in Yemen

Measurements of the levels of natural background level of the radioactivity from 226Ra and 232Th (and their decay progeny), as well as the primordial radionuclide 40K are the main objective of the current study. The present work investigated the radioactivity level of the rocks, soil and water samples at Assalamya-Alhomira area, Abyan district in Yemen. Thirty two rocks and soil samples and 3 groundwater samples from Assalamya-Alhomira area were analyzed by gamma-ray spectrometry using NaI(Tl) detector with specially designed shield. The concentration of three natural radionuclides namely 226Ra, 232Th, and 40K has been determined. The results showed that these radionuclides were present in concentrations of (48.68±6.7, 28.8±3.3 and 1618±53 Bq kg-1), (102.49±8, 149.8±8 and 2120±73 Bq kg-1) and (769.5±39, 4125±124 Bq kg-1 and 40K not detectable) for migmatitic biotite gneiss, psammitic and calc-silicate rocks, respectively. The highest activity concentration for 226Ra and 232Th is observed in calc-silicate rocks. From the microscopic study of the calc-silicate rocks we noted it consists of Calcite, Carbonate (Ca, Mg-CO3), diopside, magnetite and zircon minerals which accumulate in limited uranium and thorium. For clay and sandy soil the corresponding values were (41.46±5.6, 68.68±6 and 1224.7±31 Bq kg-1) and (80.77±4.5, 211.5±14 and 1004.8±40 Bq kg-1), respectively. Also radium equivalent activity, total dose rates and external hazard index of the (rocks/soil) samples in the area under consideration were calculated. The radioactivity concentration of 226Ra and 232Th for water samples ranged from 2.01±0.6 to 6.55±1.4 Bq l-1 and from 1.07±0.7 to 2.93±0.67 Bq l-1, respectively, while 40K activity was not detectable. The results showed that this area has a high background radiation due to the presence of Calc-silicate rocks which contain a high proportion of natural radioactive elements, and therefore represent a danger to the population lives in this area.