Abstract
<jats:p>Relevanceю Rare earth elements in groundwater are considered as indicators of interaction in the water–rock system, data on distribution in a specific hydrogeochemical system expand the understanding of their water migration properties and the possibility of using them to clarify the conditions of groundwater formation. Aim. To expand the database on the hydrogeochemistry of rare earth elements, to identify the features of their presence in a rare occurrence of soda-type fresh groundwater in Eastern Transbaikalia. Object and methods. The rare earth elements content was obtained from data of testing a well in the Gazimur River basin used for water supply. The chemical composition of water was determined at the Institute of Natural Resources, Ecology and Cryology of the Siberian Branch of the Russian Academy of Sciences according to regulatory methods. Trace element analysis was performed by inductively coupled plasma mass spectrometry (ICP MS) at the Institute of Geochemistry SB RAS. The MINTEQ program is used for thermodynamic calculations of migration forms of macro- and micro-components and mineral equilibria. Results. The authors have analysed the obtained data on the chemical composition of the water from the well used for the water supply of the settlement. The soda type of water with a very low magnesium content (less than 0.1 mg/l), as well as a Ca/P ratio of less than 100, were established. This may be one of the reasons for the existing damage to the inhabitants of the Urovsky endemic disease. The distribution of rare earth elements weight concentrations on the graph corresponds to the Oddo-Garkins parity rule. Thermodynamic calculations determined that in the studied manifestation, macro components are present mainly in the form of simple ions, lanthanides are mainly in the composition of carbonate complexes, which may explain their increased content in an alkaline medium. The equilibrium mineral phases are represented by carbonates, hydroxides, oxides, and silicates. The only mineral form of lanthanides are phosphates, which can remove rare earth elements from the aquatic environment. Conclusions. A new manifestation of soda waters in Eastern Transbaikalia was revealed with rare earth elements distribution for fresh groundwater in the hypergenesis zone, corresponding to the Oddo-Garkins parity rule. For a well-founded explanation of the nature of soda water formation and the distribution features of these rare earth elements in the waters, petrological and geochemical studies of the water-bearing rocks are required.</jats:p>