Measurement of uranium and its isotopes at trace levels in environmental samples using mass spectrometry

Actinides have widely entered the environment as a result of nuclear accidents and atmospheric weapon testing. These radionuclides, especially uranium, are outstanding radioactive pollutants, due to their high radiotoxicity and long half-lives. In addition to this, since depleted uranium (DU) has been used in the Balkan conflict in 1999, there has been a concern about the possible consequences of its use for the-people and environment. Therefore, accurate, precise and simple determination methods are necessary in order to evaluate the human dose and the concentration and effects of these nuclides in the environment. The principal isotopes of uranium e.g. (235)U and (111)U are of primordial origin and (234)U present in radioactive equilibrium with (238)U. (236)U occurs in nature at ultra trace concentrations with a (236)U : (238)U atom ratio of 10(-14). Concentrations of uranium in soil samples were determined using inductively coupled plasma mass spectrometry (ICP-MS) and isotope ratios of uranium were measured using a thermal ionisation mass spectrometer. Radioactive dis-equilibrium of (234)U/(238)U, depletion of (235)U/(238)U and significant evidence of (236)U/(238)U were noticed in soil samples.