Measurement of natural radioactivity in sand samples collected along the bank of rivers Indus and Kabul in northern Pakistan.

Radioactivity is a part of the natural environment. The presence of natural radioactivity in sand and other building materials results in internal and external exposure to the general public. Therefore, it is desirable to determine the concentration of naturally occurring radionuclides, namely (232)Th, (226)Ra and (40)K in sand, bricks and cement which are commonly used as building materials in Pakistan. In this context, sand samples were collected from 18 different locations covering an area of ∼1000 km(2) along the banks of river Indus (Ghazi to Jabba) and river Kabul (Nowshera to Kund) in the northern part of Pakistan, whereas bricks and cement samples were collected from local suppliers of the studied area. In order to measure the specific activities in these samples, a P-type coaxial high-purity germanium-based gamma-ray spectrometer was used. In sand samples, the average specific activities of (226)Ra, (232)Th, and (40)K were found to be 30.5±11.4, 53.2±19.5 and 531±49 Bq kg(-1), whereas in brick samples, specific activities of 30±14, 41±21 and 525±183 Bq kg(-1) were observed, respectively. In cement samples, measured specific activity values were 21±5, 14±3 and 231±30 Bq kg(-1), respectively. Radium equivalent activities were calculated and found to be 143.8±38.6, 124±49.8 and 56.69±7 Bq kg(-1) for sand, brick and cement samples, respectively. The annual mean effective dose for the studied sand samples was found to be 0.40 mSv. External and internal hazard indices were less than unity for all the studied samples. The present results have been compared with those reported in the literature.