Environmental radioactivity studies in Kabul and northern Afghanistan

From earlier surveys conducted by soviet researchers, the Kabul area was identified as a region of high natural radioactivity. However, only fragmentary maps on dose rates (often only given in relative units) are available. No detailed information of, e.g., uranium and thorium distributions in the upper soil and rock exists. In recent years, residential houses have been built in some of these places known for their elevated radiation dose rate. In order to assess possible radiological risk, 51 soil and rock samples as well as 51 all-purpose water samples were collected and measured with regard to radioisotope content and contamination by other pollutants such as, e.g. heavy metals. For the rocks and soil samples, gamma spectroscopy was used as main technique, while ICP-MS and ICP-OES was used as main technique for water analysis. Furthermore, alpha spectroscopy, μ-XRF, PXRD, TOF-SIMS and LSC were used to verify the gamma spectroscopy and ICP-MS results. Activity concentrations in soil and rocks ranged between 160 to 28600 Bq/kg, 73 to 383000Bq/kg, and 270 to 24600 Bq/kg for uranium, thorium, and potassium, respectively. While none of the samples showed any anomalies of the radioactive equilibria some of the samples contained remarkably high levels of thorium and uranium (and their daughter nuclides). Thorium was bound in a cheralite mineral structure. Not all of the investigated waters are safe for drinking, exceeding the national and international recommended values.