The Dzhidinsky orefield is located in the Zakamensky district of Buryatia. It is characterized by a high concentration of mineralization in a small area. The ores of the Dzhidinsky economic deposits are complex. This ore field includes Pervomaiskoye Mo, Kholtosonskoe W, and Inkurskoe W deposits. The catchment basin of the river Modonkul is located in the Dzhidinsky orefield. Mineral resource industry waste is a real threat to the city Zakamensk. Currently, the waste of deposits is located at the floodplain terrace and the watershed of the river Modonkul. In this work, the impact of the drainage mine and tributary Inkur on the formation chemical composition of the river Modonkul is studied. The 80 samples of water and suspended matter were taken from a surface of 0–0.5 m on seven sites. Physical and chemical parameters were measured at the sampling sites, and chemical composition was analyzed in the laboratory. In the natural background of the river, the major cations are, in decreasing order, Ca²⁺ > Mg²⁺ > Na⁺ + K⁺, and major anions are, also in decreasing order, HCO₃⁻ > SO₄²⁻ > Cl⁻. Along the river, the chemical type of water changes from bicarbonate to sulfate across the sulfate-bicarbonate or bicarbonate-sulfate class and from calcium-magnesium across sodium-calcium-magnesium reverse calcium-magnesium group. Total dissolved solids (TDS) increase by a factor of 4.0–4.7 between the upper and mouth of the river. The dissolved and suspended loads were studied in the mixing zone of acid mine and river water. The different hydrochemistry characteristics may result from Fe, Al, and Mn hydroxide precipitation. The pH values and dissolved oxygen cycles could change the uptake of heavy metals on suspended iron and manganese oxides, and the mechanism of removing it in water. River particulates have the potential of regulating heavy metal inputs to aquatic systems from pollution. The ore elements or the heavy metals are removed from the water in two ways: by the runoff of Modonkul and the sedimentation of suspended material at the bottom. The inflow of mine water into the Modonkul river leads to the rare earth elements (REEs) composition with negative cerium and positive europium anomalies.

Lake Gusinoe is the second largest freshwater lake in Transbaikalia. Lakes serve as a source for drinking water, irrigation, and as a water source for the electricity, aquatic production, and tourism industry. Currently variations of content nutrients and organic matter differ in different areas of the lake. The content of total nitrogen, phosphorus, organic matter, and dissolved oxygen are distinguished more than 1.2–2.0 times. In accordance with the behavior of elements in the water, three groups of elements can be distinguished. The first group of elements, including Li, Ga, Ge, As, Rb, Sr, Mo, Cd, W, and U, were directly correlated with variations of major elements. The first group of elements showed decreasing concentrations with an increasing amount of total dissolved salt (TDS). The second group of elements, including Fe, Y, Nb, Th, and REE, were correlated oppositely with variations of TDS. The behavior of the third group of elements, including Mn, Zn, Ni, Cu, and Pb, decoupled with TDS. The value of the Eu anomaly was positively correlated with TDS. The water of Lake Gusinoe was extremely enriched by W, Mo, V, U, Li, Sr, and Ga; moderately by Ni, Cu, Ge, As, Rb, Cd, and Pb; and minimally by Al, Cr, Mn, Fe, Co, Zn, Y, Th, and REE.

Цель – установление основных процессов, обусловливающих особенности миграции токсичных элементов в поверхностных и подземных водах Джидинской природно-техногенной системы. Материалы и методы. Полевые исследования, анализ воды и донных отложений методами масс-спектрометрии с индуктивно связанной плазмой, атомно-эмиссионной спектрометрии с индуктивно связанной плазмой, ренгено-структурный анализ. Результаты и обсуждение. Приведены экспериментальные исследования содержания токсичных элементов в реке Модонкуль и реке Мыргэншено. В составе поверхностных и подрусловых вод установлены высокие содержания таких элементов, как цинк, свинец, бериллий, ртуть, алюминий, железо, медь. Эти элементы поступают в реки в результате разгрузки штольневых вод и загрязненных родников техногенного происхождения. Под воздействием отходов добычи и переработки руд в реках образуется взвесь трудно растворимых соединений, которые осаждаются на берегах рек, переносятся ветром и длительно негативно воздействуют на окружающую среду. Под воздействием жидких и твердых отходов горнорудного производства на данной территории сформировался обширный ореол загрязнения подземных вод. В местах разгрузки грунтовых вод образуются гипергенные минералы, содержащие продукты выветривания рудной минерализации. Выводы. Токсичные элементы поступают в поверхностные воды с жидкими отходами производства, изливающимися из штольни, а также за счет разгрузки загрязненных грунтовых вод, которые поступают в подрусловые воды рек в местах хранения отходов добычи и переработки руд.