The results of hydrogeochemical studies on the content of rare earth elements (REE) in technogenically transformed waters of geotechnogenic objects of Zavitinskoye, Orlovskoye, Etykinskoye and Malo-Kulindinskoye rare metal deposits located in Eastern Transbaikalia are presented. Currently, the above-mentioned mines are closed and their territories represent typical man-made landscapes, the reclamation of which has not been carried out. Within the limits of rare metal deposits, the waters of quarry lakes, ponds-tailings ponds, drainage drains from under dumps and drilling holes drilled for blasting during the periods of mine development were tested. Chemical and analytical studies of water samples for macro components and some trace elements were carried out in the certified laboratory of INRE. SB RAS (Chita) by atomic absorption method. Determination of REE contents in water samples was carried out at the Vinogradov Institute of Geochemistry SB RAS (Irkutsk) by inductively coupled plasma mass spectrometry (ICP-MS). Normalization of REE contents is given by standard North American shale (NASC). The data obtained showed significant differences in REE contents in the waters of the technogenesis zone of rare metal deposits. The total concentrations of REE in the studied waters vary between 0,05-655 mu g/L. The maximum concentrations of REE and yttrium were observed in the acidic most mineralized sulfate drainage waters and waters from the drilling holes of the Orlovskoye tantalum deposit. Lower concentrations of REE, including Y (up to 148 mu g/L) and Sc (up to 4,9 mu g/L), were found in the acidic bottom waters of the Etykinskoye tantalum-niobium deposit. In the neutral tested waters of the Malo-Kulindinskoye tantalum deposit, the average total REE content was 0,76 mu g/L. Minimal concentrations of REE were observed in neutral and slightly alkaline waters of the Zavitinskoye lithium-beryllium deposit. Comparison of the average values of REE in the waters of the deposits showed an excess of the amounts of light lanthanides over heavy ones, which corresponds to the nature of their content in the earth's crust. All normalized distribution profiles of rare earth elements are characterized by enrichment with heavy lanthanides and accumulation of medium REE groups. Among the lanthanides, Europium is distinguished by the presence of both positive and negative anomalies, which is associated with the composition of the water-bearing rocks and ores of the studied territory. The normalized spectra of the studied waters of rare metal deposits have a negative anomaly in terms of cerium, with the exception of the waters of the Orlovskoye deposit. The presence of cerium minima is explained by the removal of cerium from an aqueous solution as a result of partial oxidation of its trivalent form (Ce3+) to a poorly soluble tetravalent form (Ce4+) and its precipitation together with iron and manganese hydroxides. For a more detailed study of the revealed features of the distribution of rare-earth elements in the waters of rare-metal deposits, it is necessary to conduct further research, including the study of the forms of REE migration and the processes of secondary mineral formation.
