Natural radioactivity in sand samples collected along the bank of river Indus in the area spanning over Gilgit to Lowarian, Pakistan: assessment of its radiological hazards

摘要

Sand is extensively used in construction of buildings. The presence of natural radioactivity in it results in internal and external exposure to the general public. Therefore, it is desirable to determine the concentration of naturally occurring radio-nuclides, namely ~(232)Th, ~(226)Ra and ~(40)K in sand. In this regard, in continuation of our earlier studies, 42 sand samples were collected from fourteen different locations along the banks of river Indus from Gilgit to Lowarian in the northern part of Pakistan covering an area of ~500 km. In order to measure the specific activities in these samples, a P-type coaxial high purity germanium based gamma-ray spectrometer was used. Average values of the measured activities of ~(226)Ra, ~(232)Th and ~(40)K were found to be 45.6 ± 3, 74.73 ± 3 and 339.8 ± 3.6 Bq kg~(-1), respectively which results in an average absorbed dose rate 83.54 nGy h~(-1). From the measured activities, average radium equivalent activity was found to be 178.59 Bq kg~(-1). External and internal hazard indices were also calculated and found to be 0.48 and 0.61, respectively. Average effective dose expected to be received due to the gamma rays was 0.26 mSv y~(-1). Measured natural radioactivity, hazard indices and effective doses received by the population were found to be within the recommended limits.