Навидҳои рӯз

  Abstract: For a better understanding of the previously observed increased natural radioactivity at the confluence of Varzob and Sioma rivers, the activity concentration of natural radioactive 40K, Th and U daughters as well as of the anthropogenic 137Cs were determined in nine sampling points covering the entire Sioma river. The radiometric determinations evidenced, beside increased activity concentrations of Th and U daughter radionuclides, an anomalous accumulation of anthropic 137Cs and natural 210Pb in the middle of the Sioma gorge.

  Complementarity, the mass fractions of natural Th and U determined by Instrumental Neutron Activation Analysis (INAA) evidencing an increased presence of Th and U which, in some places overpasses six times the average mass fraction found in the Upper Continental Crust. The 137Cs and 210Pb activity concentrations did not correlate with the other radionuclides or Th and U presence, but were reciprocally correlated suggesting an active air transport from the southern Tadjik plane most probably during the Afgan storms. At their turn, the increased presence of Th and U as gamma-ray spectroscopy and INAA determinations proved could be attributed to the existence of actinides rich minerals, similar to those fond on neighbouring Odjuk pegmatite field.

Read more: Geochemical and isotope anomalies in Sioma river gorge, central Tajikistan