Abstract
Tritium and stable isotope (deuterium 2H and 18O) concentrations have been determined in natural waterscollected from shallow lakes, wells, streams and rivers inside and in the vicinity of the former SemipalatinskNuclear Test Site (NE Kazakhstan). The Semipalatinsk Test Site (STS) was one of the main proving groundsfor the testing of nuclear weapons by the former Soviet Union. Tritium activity concentrations have beendetermined by liquid scintillation counting, while hydrogen isotopic composition have been determinedusing a GV-Isoprime mass spectrometer coupled to an elemental analyzer. Tritium activity concentrationsrecorded in lake waters (in most cases >10 Bq L-1) were significantly higher than those in well, stream andthe Irtysh River waters. In lake waters, enrichments in deuterium and 18O (δD and δ18O varying between –5and –64 ‰ V-SMOW and –8.4 and +5.5 ‰ V-SMOW, respectively), and high salt concentrations, stronglysuggest that significant evaporation has occurred. In contrast, deuterium and tritium signatures of ‘common’surface and underground waters at the STS were mostly typical of present-day isotope backgrounds of natural waters in NE Kazakhstan. In STS, come salt lakes like Bajansor and Tumatsor with elevated tritium activity from 12 to 15 Bq L-1 lie close to the Global Meteoric Water Line. The potential tritium source for these lakes is residual concentration of tritium after former nuclear test in STS. The study provides evidence to show that export of tritium from underground nuclear test areas and tritium enrichment produced by evaporation are both important determinants of tritium concentrations in standing waters on the Semipalatinsk test site.