Survey of natural and anthropogenic radioactivity in environmental samples from Yugoslavia (original) (raw)

2002, Journal of Environmental Radioactivity

Measurements of the levels of natural backg round level of the radioactiv ity fro m 226 Ra and 232 Th (and their decay progeny), as well as the primo rdial radionuclide 40 K are the main ob jective of the current study. The present work investigated the radioactivity level of the rocks, soil and water samples at Assalamya-Alho mira area, Abyan district in Yemen. Thirty two rocks and soil samples and 3 groundwater samples fro m Assalamya-Alho mira area were analy zed by gamma-ray spectrometry using NaI(Tl) detector with specially designed shield. The concentration of three natural radionuclides namely 226 Ra, 232 Th, and 40 K 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 40 K not detectable) for mig matit ic biotite gneiss, psammit ic and calc-silicate rocks, respectively. The highest activity concentration for 226 Ra and 232 Th is observed in calc-silicate rocks. Fro m the microscopic study of the calc-silicate rocks we noted it consists of Calcite, Carbonate (Ca, Mg-CO3), diopside, magnetite and zircon minerals wh ich accu mulate in limited uranium and thoriu m. 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. A lso radiu m equivalent activ ity, total dose rates and external hazard index of the (rocks/soil) samp les in the area under consideration were calcu lated. The radioactivity concentration of 226 Ra and 232 Th for water samples ranged fro m 2.01±0.6 to 6.55±1.4 Bq l-1 and fro m 1.07±0.7 to 2.93±0.67 Bq l-1 , respectively, while 40 K activity was not detectable. The results showed that this area has a h igh background radiat ion due to the presence of Calc-silicate rocks which contain a h igh proportion of natural rad ioactive elements, and therefore represent a danger to the population lives in this area.