Brine

Brine, water saturated with salts, from salt lakes. There are 2 main types of salt lakes: coastal and inland; the latter are endorheic basins whose salinity is due to the leaching of surrounding rocks; while marine lakes were formed with the direct participation of the sea and their salt reserves are of marine origin. Transitional types may exist between these two main types. In terms of salt composition, inland lakes sharply differ from coastal, lagoonal lakes. While lagoons, if they have completely separated from the sea and are deprived of seawater inflow, become depleted in sulfates and sodium, inland lakes, on the contrary, become enriched in sulfates and sodium. In turn, in lagoons from the moment of their complete separation from the sea, new special regime conditions are created (the influence of evaporation, condensation of brine, the influence of continental waters and soil particles brought by them, biochemical processes, etc.), as a result of which not only quantitative (higher concentration) but also significant qualitative differences arise between the salt mass of the brine and the salt mass of the sea. These qualitative differences, as Verigo showed earlier, consist in that all the sulfuric acid of the brine's salt mass is saturated with lime, whereas the marine salt mass contains lime in a much larger quantity than is needed to saturate the H₂SO₄ it contains; in other words, there is a depletion of the brine in soluble sulfates, a process of desulfation. Calcium carbonate, continuously entering the water body with rain and spring waters flowing through gullies, significantly affects the composition of marine salts. According to Burkser, the following chemical reactions lead to the formation of chlorides of magnesium and calcium in the brine: 2Ca(HCO₃)₂+MgSO₄ → CaMg(CO₃)₂+CaSO₄+2CO₂+2H₂O; 2Ca(HCO₃)₂+MgCl₂ → CaMg(CO₃)₂+CaCl₂+2CO₂+2H₂O. Such a process of metamorphosis of salt brines leads to the transformation of brines of the first class, according to Kurnakov's classification containing CaSO₄, MgSO₄, Na₂SO₄, MgCl₂, NaCl, into brines of the second class, containing CaSO₄, CaCl₂, MgCl₂, NaCl. Academician Kurnakov proposed to characterize the course of the desulfation process occurring during the metamorphosis of lagoons using the so-called coefficient of metamorphosis of salt lakes, expressed by the ratio * ⁴. A decrease in this coefficient indicates a decrease in the relative amount of sulfates in the lake brine. Kurnakov also constructed a classification of salt lakes, based on the complete absence of CaSO₄ salt in some of them (in this case the metamorphosis coefficient is zero) and their division into two classes. Typical lakes of the first class are the Khadzhibey and Kleinlibental lagoons near Odessa, Lake Saki, Elton, etc.; of the second class - the Kuyalnik lagoon, Baskunchak, etc. As both the classification proposed by Kurnakov and the classification modified later and more elaborated by Krotov, in the opinion of S. A. Shchukarev, are based on the idea of gradual depletion of the brine in SO₄ ions, and then in Mg²⁺ ions, due to double salt exchange reactions first between MgSO₄ and CaCO₃, and then between MgCl₂ and CaCO₃. These reactions are depicted as follows: 2CaCO₃+MgSO₄ → CaCO₃·MgCO₃+CaSO₄; 2CaCO₃+MgCl₂ → CaCO₃·MgCO₃+CaCl₂. The resulting poorly soluble substances - CaCO₃·MgCO₃ (dolomite) and gypsum - settle (as indicated by the arrows) and become part of the mud of this lake. As a result, in the early stages of the lake's life, it can be characterized by a gradual decrease in the MgSO₄ coefficient

Author signatures: ["E. Brusilovsky"]

_orv, -j^oP > ^a after the disappearance of all SO₄- Ca. Cl* ions > by the relation ^-тг,- . However, at the present time Shchukarev considers it proven that the process of loss of R. sulfate ions and magnesium ions occurs mainly not by the two equations given above (although theoretically such a path is quite possible), but by two completely different paths. The first of these paths is biochemical, removing SO₄ from the solution by biochemical reduction to HS' and binding with iron into black hydrotroilite; calculations made by him for Lake Saki established a significant influence of sulfate reduction on the lowering of the metamorphization coefficient. The other path is colloid-chemical - it occurs only in lakes with a high concentration of R. Instead of a double salt exchange reaction, we have here to deal with an exchange adsorption process. The mechanism of these processes differs essentially from exchange reactions with CaCO₃, but practically the result for R. is the same - the disappearance from the solution first of sulfate ions, and then of magnesium ions, and the appearance in it of calcium ions; however, for the composition of the mud forming in the lake it is not indifferent whether we are dealing with a salt exchange reaction or with exchange adsorption; in the first case, dolomite accumulates in the mud, in the second - accumulation of adsorbed magnesium and sodium ions. The study of Saki mud, carried out by Shchukarev, confirmed the presence in it of an adsorbing colloidal complex as well as adsorbed sodium and magnesium ions, and did not confirm the presence of dolomite (CaCO₃ · MgCO₃) assumed by the previous theory. Haydinger's reaction. When sea water evaporates, the precipitation of different salts does not occur simultaneously, but in a certain sequence. The first stage of crystallization during the evaporation and concentration of this brine is the precipitation of magnesium and calcium carbonates. The processes occurring in this respect are interesting, firstly, in relation to the metamorphization of sea water by calcium carbonates, and secondly, in relation to the conditions for the formation of natural magnesium carbonates, in particular - dolomites and magnesites. When calcium carbonate enters a brine of the sea type, precipitation of calcium-magnesium-dolomite carbonate and gypsum occurs. This reaction is represented by the following equation: 2CaCO₃+MgSO₄ £: CaMg(CO₃)₂+CaSO₄. In this case, magnesium sulfate disappears from the brine. Marignac's reaction occurs after the disappearance of MgSO₄ and consists of the following equation: 2CaCO₃+MgCl₂ £: CaMg(CO₃)₂+CaCl₂, 2Ca(HCO₃)₂+MgCl₂ :£ CaMg(CO₃)₂+CaCl₂+2CO₂+2H₂O. The reaction leads to the formation of calcium chloride in the brine instead of magnesium chloride. Both carbonate and bicarbonate of calcium can react. As a result of both reactions, metamorphization of a coastal lake occurs, forming R. of the type of Kuyalnitsky Liman. Rykovsky and Neely set out to verify Haydinger's reaction. The peculiarities of this reaction, making its study a task unfavorable in the authors' opinion, are: 1) abundance of solid phases (for calcium carbonates one must reckon with the possibility of the appearance of three modifications - calcite, aragonite, vaterite; for magnesium carbonate - magnesite, penta- and trihydrate, amorphous carbonate and basic salts; besides, the formation of Link's spheroids and dolomites is possible; for calcium sulfate - anhydrite, gypsum and hemihydrate); 2) low solubility of carbonates; 3) slowness in establishing equilibria. On the basis of their research, the authors come to the conclusion that the metamorphization of sea water by calcium carbonates turns out to be impossible, if, which should be especially emphasized, the metamorphization is explained only by Haydinger's reaction. Continental lakes, as has already been said above, differ sharply from coastal lakes. The metamorphization coefficient «g^f* for continental lakes is very large and can even become equal to infinity; in these lakes Na₂SO₄ (Glauber's bitter lakes) and NaHCO₃ (soda lakes) accumulate; while the final stage of metamorphization of sea lakes will be chloromagnesium and calcium-chloride lakes with 'hard' R., on the continent we often encounter bodies of water with 'soft' R., completely devoid of magnesium and calcium - so-called soda lakes. For hard lakes, the absence in R. of borates, phosphates, large amounts of sulfates and carbonates is characteristic; in soft lakes, soda, Glauber's salt are encountered in large quantities, sometimes phosphates in noticeable amounts, even sodium borates. The composition of the salt mass of the lake R. and the degree of its salinity depend on a whole range of geological, climatic and other factors and can fluctuate within very wide limits. Many years of systematic observations over the Odessa limans have shown that the level of the limans and the density of their water mass undergo periodic fluctuations depending on the amount of atmospheric precipitation, the speed of snow melting, the average summer t° and the strength of evaporation from the lake surface, etc. These conditions can combine from year to year in the most diverse ways, acting together sometimes in one direction, sometimes in opposite directions. The result of such combinations is either a gradual condensation of R. and a progressive drop in the water level in the liman - for several consecutive years, or the reverse phenomenon - a sudden rise in the water level and a weakening of its concentration. All these conditions combine differently for different limans, thereby causing essential differences in the range of fluctuations in R. density. The data concerning the Odessa limans can serve as an illustration. During a 70-year period of observations at Kuyalnitsky Liman, the density of its brine fluctuated within the range from 3½₂° to 26° Baumé, at which self-sedimenting salt precipitates. The greatest condensation of brine: during the summer reached 5--§° Baumé. When comparing the concentration of R. of both Odessa limans - Kuyalnitsky and Khadzhibey - over a 10-year period of simultaneous continuous observations (1884-1894), it turns out that the years of greatest and least density R. of both limans during this time coincide; the minimum difference between them is 1.5° Baumé, while the maximum of the same difference reaches 14° Baumé, and with an increase in the concentration of the limans in general this difference increases and vice versa. If the same fluctuations in density are represented graphically, then from the examination of the curves obtained the following conclusions can be drawn: the increase in concentrations usually occurs slowly but progressively over several consecutive years, while the decreases occur suddenly and rapidly within one or two years; this phenomenon is more clearly manifested on the curve of Kuyalnitsky Liman, however it is also noted on the curve of Khadzhibey Liman. The tops of both curves in years of low concentrations approach each other, in years of high concentrations they diverge significantly; in other words, the lower limits of brine density of both limans are quite close, while the upper limits of the same density differ significantly from each other. The radioactivity of R. compared to the radioactivity of many mineral springs is very insignificant. Due to the shallow depths of salt lakes and limans, the radioactivity of their R. is subject to significant fluctuations depending on meteorological factors as well as on the nature of bottom sediments. Thus, for example, according to Burxer's data, the radioactivity of R. of Kuyalnitsky Liman fluctuates from 0.30 to 2.55 Eman, of Khadzhibey from 0.23 to 1.44 Eman, of Lake Saki from 0.30 to 1.52 Eman, of Elton from 0.57 to 0.95 Eman, of Repnoye in Slavyansk from 0.57 to 0.95 Eman, of Slepnogo in Slavyansk from 0.30 to 0.42 Eman. What significance such insignificant radioactivity of R. has in the therapeutic effect of the latter remains an open question. The therapeutic application of lake R. is very diverse. R. is used in the form of heated baths of various t° and concentration and in the form of bathing in the open lake, the t° of which fluctuates in the summer months from 20° to 32°, in combination with sun baths. Brine baths are divided into general and local, and according to the density of R. - into full, diluted and concentrated; the latter are obtained by adding to R. table salt or mother liquor, and diluted ones - by diluting R. with fresh water to the desired concentration, measured by a Baumé hydrometer; besides, brine and thickened mother liquor are used in the form of hot compresses and heating compresses on affected parts of the body. The temperature of general brine baths fluctuates within the range of 30° to 38°, concentration - from 1° to 26° Baumé, duration of baths - from 10 to 30 min.; the temperature of local baths rises from 42° to 46°, the temperature of hot compresses - to 47-48°.