S. L. Shvartsev

Geochemistry of fresh groundwater in the main landscape zones of the Earth

INTRODUCTION CHAPTER 1. AVERAGE ABUNDANCES OF CHEMICAL ELEMENTS IN THE GROUNDWATERS OF THE SUPERGENE ZONE 1.1. Method of Calculation of Clarke Values 1.2. Groundwaters of the Permafrost Province 1.3. Groundwaters of the Province of Tropical and Subtropical Climate 1.4. Groundwaters of the Provinceof Temperate Humid Climate 1.5. Groundwaters of Mountain Regions 1.6. Groundwaters of the Province of Arid Climate

Geochemistry and chemical evolution of saline lakes of Western Mongolia

This paper presents data on the major and trace element composition of saline lakes of western Mongolia. The main geochemical types of lakes distinguished in the study are soda-, chloride-, and sulfaterich lakes. Lake water equilibria with major carbonate, sulfate, chloride, and other rock-forming minerals were calculated. The results show that the major factors controlling the formation of each lake type include evaporation and water-rock interaction processes, and the latter factor plays a critical role in freshwater and soda lakes and only a minor role in chloride lakes. Special attention was given to the soda lakes and the factors controlling lake water chemistry.

Uranium in saline lakes of Northwestern Mongolia

Analysis of major- and trace-element compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia and Chuya basin (Gorny Altai) shows high enrichment in 238U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes and their watersheds in potential provinces of U-bearing rocks and (ii) uranium complexing with carbonate in presence of carbonate (bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the greatest uranium resources are stored in Lake Hyargas Nuur (about 6000 ton).

Geochemistry of wetland waters from the lower Tom basin, Southern Tomsk oblast

New data are reported on the major- and trace-component compositions of acidic and weakly acidic low-concentration wetland waters and other water types. Special attention was given to dissolved organic compounds: fulvic and humic acids, bitumens, and hydrocarbons. The first comprehensive data are presented for organic trace components in the wetland waters of western Siberia: alkanes, pentacyclic terpenoids, steranes, alkylbenzenes, naphthalenes, phenanthrenes, tetraarenes, etc.

Geochemistry of sodic waters in the Datong intermountain basin, Shanxi Province, northwestern China

The paper presents a critical analysis of current concepts of the origin of sodic waters. The example of the Datong Basin with widespread sodic waters is employed to demonstrate that these waters typically have salinities of 0.6–4.5 g/l at pH of 7.8–8.8. It was determined that sodic waters are in equilibrium with calcite and clay minerals (montmorillonite and kaolinite) and, sometimes, also with analcime but are never in equilibrium with anorthite, albite, forsterite, microcline, and muscovite; i.e., the water-rock system is in equilibrium-unequilibrium state. The degree of evaporation concentration of salts is in places as high as a few tens. The complex analyses of conditions under which sodic waters are formed indicates that these waters are produced during a certain weathering stage of aluminosilicates, after the groundwaters have reached equilibrium with calcite. The time when this equilibrium can be reached is controlled by the intensity of the water exchange.

The internal evolution of the water-rock geological system

Modern natural scientists are concerned with the nature and mechanisms of global evolution. The unique properties of water underlie this problem. Water predetermined the mechanisms of the global evolution of geological and biological systems. The source of this phenomenon should be sought in the mechanisms of interaction between water and rocks.

Where did global evolution begin

In the opinion of the author, the emergence of life on our planet was not a single act but a predetermined evolutionary stage caused by interaction between water and endogenous rocks. Living systems merely inherited the evolutionary mechanisms of nonliving systems, namely, of the water-rock system.

Equilibrium of nitrogen-rich spring waters of the Baikal Rift Zone with host rock minerals as a basis for determining mechanisms of their formation

This paper presents calculations of equilibria between nitrogenrich hot springs of the Baikal Rift Zone (BRZ) and a secondary mineral assemblage (carbonate, fluoride, clay, zeolite, and other minerals). The results confirm the equilibrium–nonequilibrium character of the nitrogen spring water–rock system. Unlike other water types, the system evolves under conditions of continuous incorporation of chemical elements released from the host minerals into the newly formed secondary minerals. This allows the system to remain dynamically stable with no increase in salinity, despite continued water–rock interaction. The main factor responsible for this state of the system is a deficiency of acids, i.e., high pH. As a result, the disturbance of relationships between concentrations of aqueous species compared to the starting composition of dissolved solids produces a deficiency of some elements (Ca, Mg, Fe, Al, etc.) and an excess of other elements (Na, Si, F, etc.).

Thermodynamic modeling of the behavior of Uranium and Arsenic in mineralized Shaazgai-Nuur Lake (Northwest Mongolia)

Highly mineralized closed lakes on the territory of ore regions of Mongolia are of special interest in relation to the search for nonconventional sources of metals. Water of soda Shaazgai-Nuur Lake contains ~1 mg/L U, and the content of the undesirable admixture of As is up to 300 μg/L. Uranium and Arsenic speciation in solution and in the bottom sediments of the lake was estimated using thermodynamic modeling, and a method of their separation was suggested. Calculation of the models of sorption of these elements by goethite and calcite showed that at pH 9.4 typical of natural water it could be effective only at a high concentration of FeOOH sorbent. In this case, at pH <5 and >8 (the area of U sorption), As may be removed by simple filtering of solutions from the suspension upon additional coagulation.

V.I. Vernadsky and main research avenues in modern hydrogeochemistry

The main research directions in modern hydrogeochemistry were analyzed in connection with the 75th anniversary of its foundation. It was shown that hydrogeochemistry has fruitfully developed on the basis of the scientific concepts of its founder, V.I. Vernadsky. Among these concepts are the mineralogy of water, evolution of the system of water-rock-gas-organic matter, dynamics of hydrogeochemical processes, isotopic and environmental hydrogeochemistry, geochemistry of free and capillary waters, ocean geochemistry, geological and biological role of water, physicochemical modeling, etc.