Mineral Springs

MINERAL SPRINGS. Springs are called mineral if their water differs from ordinary spring or well water by 1) a higher content of dissolved substances, or 2) the content of rarely encountered and therapeutically important substances, or 3) a higher temperature. It is accepted (Deutsches Baderbuch) to consider water mineral if 1 liter contains more than 1 g of all dissolved solid substances (including bicarbonates) or more than 0.25 g of free carbonic anhydride (CO₂); 1 mg of lithium ion (Li⁺); 10 mg of strontium ion (Sr⁺⁺); 5 mg of barium ion (Ba⁺⁺); 10 mg of ferrous or ferric iron ion (Fe⁺⁺ or Fe⁺⁺⁺); 5 mg of bromine ion (Br^-); 1 mg of iodine ion (J^-); 2 mg of fluorine ion (F^-); 1.3 mg of hydroarsenate ion (HAsO₄^--); 1 mg of meta-arsenic acid (HAsO₂); 1 mg of total iodine-titratable sulfur (S, corresponding to H₂S + HS^- + S₂O₃^-- + SO₃^--); 5 mg of meta-boric acid (HBO₂); 4 milliequivalents of titratable alkalinity or bicarbonates and alkali carbonates, corresponding to 340 mg NaHCO₃. Water is also recognized as mineral if it possesses radioactivity of more than 3.5 Mache units or a temperature above +20°. The origin of mineral springs is connected with the fact of water circulation in the earth's crust. All strata of the earth's crust can be roughly divided into permeable (e.g., sand) and impermeable (e.g., clay); large quantities of groundwater can move only through the former. The emergence of groundwater to the surface can take place 1) when an aquifer layer emerges on the surface on a mountain slope, in a ravine (and in the presence of folding and erosion of strata—in any relief conditions), 2) upon violation of the integrity, or the so-called "continuity" of impermeable strata covering the aquifer; such a violation can be natural (cracks) or artificial (boreholes, mines). The water of mineral springs itself, according to Suess, is obtained in two ways: 1) so-called juvenile water is released in the deep layers of the earth's crust or near volcanic centers from magma; 2) vadose waters (see Vadose springs) originate from surface waters that have passed underground along a longer or shorter path. Being a very active chemical reagent and being distributed on the earth's surface everywhere, water long ago processed those substances that could enter into energetic interaction with it, and therefore at the present time we observe in nature only comparatively slowly proceeding processes of dissolution, leaching, exchange adsorption, etc. The chemical activity of water is conditioned to a significant extent by the asymmetric structure of its molecule, the polarity of the molecule; by virtue of this polarity, water molecules attract both each other (association phenomena) and foreign molecules, as well as ions. It is these attractions that primarily determine the ability of water to dissolve and leach rocks. Salts and other dissolved substances enter mineral water in many ways. Magma exhalations, i.e., incandescent vapors released from liquid magma, consist not only of water but also of a whole series of substances (H₂S, CO₂, H₃BO₃, HCl, alkalis); upon cooling, the greater part of them dissolves in water. Rain and snow carry with them from the air dust, O₂, N₂, O₃, SO₂, SO₃, NH₃, nitrogen oxides, NaCl (especially over the sea), etc. Rainwater can contain salts in far from negligible quantities: up to 950 mg NaCl, up to 16 mg NH₃ per 1 liter, etc. Flowing through the strata of the earth's crust, water becomes enriched with salts. The composition of mineral water depends on which rocks, in what sequence, under what conditions (temperature and pressure), and for how long the water was in contact. All rocks are subject to the action of water, but to varying degrees. Waters formed by interaction with primary crystalline rocks and waters that received their mineralization in sedimentary rock strata differ particularly sharply from each other. Primarily, easily soluble salts, captured by them during the period of salt deposition from seawater, are leached from sedimentary rocks. A particularly energetic solvent is water possessing an acidic reaction from the presence of carbonic acid or other acids. Thus, 0.013 g of CaCO₃ dissolves in 1 liter of pure water, while 1.099 g of CaCO₃ dissolves in water saturated with CO₂ at 1 atm pressure. An acidic reaction can also be caused by humic acids (swamp waters) or sulfuric acid, which is obtained during the oxidation of hydrogen sulfide, sulfur, pyrites, and during the hydrolysis of aluminum and iron sulfates. In general, when water already containing dissolved substances (gases, salts, acids) acts on rocks, a whole series of exchange reactions occurs with the formation of both soluble and insoluble products. Examples of reactions: CaCO₃ + H₂O + CO₂ ⇌ Ca(HCO₃)₂; MgCO₃ + H₂O + CO₂ ⇌ Mg(HCO₃)₂; FeO + H₂O + 2CO₂ ⇌ Fe(HCO₃)₂; CaCO₃ + H₂SO₄ → CaSO₄ + H₂O + CO₂; Fe(HCO₃)₂ + CaCO₃ ⇌ FeCO₃ + Ca(HCO₃)₂; FeCO₃ + H₂S ⇌ FeS + H₂O + CO₂; FeS₂ + 2CO₂ + 2H₂O → H₂S + Fe(HCO₃)₂ + S. According to experiments and conclusions of the newest theory of electrolyte solutions (Debye and Hückel), ions present in the solution often facilitate the dissolution of difficultly soluble salts (CaCO₃, CaSO₄·2H₂O) and reduce the solubility of gases. This change in solubility can reach a significant magnitude. Thus, 2.08 g of CaSO₄ dissolves in 1 liter of pure water at 25°, while 6.24 g of CaSO₄ dissolves in 1 liter of water containing 58 g of NaCl at the same temperature. Upon the interaction of water containing Ca(HCO₃)₂ or CaSO₄ with rocks containing Na (clays), NaHCO₃ or Na₂SO₄ are formed; thus, in all probability, the genesis of many soda and sulfate mineral waters is explained. Individual streams of water of different composition can meet underground and, having mixed, yield water of a new composition. In this case, the solubility limit for some salts may be reached, and they will precipitate from the solution. The composition of the resulting water is connected with the quantity and composition of the mixed waters by a definite mathematical relationship. Biochemical processes in the earth's crust also influence the composition of waters. Thus, sulfate waters, upon meeting rocks containing organic substances, often yield hydrogen sulfide and carbonic acid. This process is caused by bacteria that live at the expense of the energy released during this (Microspira desulfuricans and others). The simplest scheme of the process: 2C + Na₂SO₄ → Na₂S + 2CO₂; Na₂S + 2CO₂ + 2H₂O → 2NaHCO₃ + H₂S. In areas of the distribution of oil-bearing and bituminous rocks, waters are often encountered that contain absolutely no sulfates, enriched with carbonates and sulfides. Oil waters usually belong to the chloride type, often contain significant quantities of barium (up to 0.4 g per 1 liter) and an increased amount of Br^- and J^- compared to seawater. Biochemical processes also explain in many cases the transition of nitrates into nitrites and ammonium. Microorganisms also take part in the formation of baregine (see). Composition of mineral springs. In mineral waters, almost all known elements are encountered in the form of "traces", but in relatively significant quantities—only a few, mainly Na⁺, Ca⁺⁺, Mg⁺⁺, Cl^-, HCO₃^-, SO₄^--, less K⁺, H₂SiO₃, CO₂, NO₃^- and Fe⁺⁺, more rarely or in even smaller quantities CO₃^--, Br^-, J^-, HS^-, F^-, S₂O₃^--, SO₃^--, HSiO₃^-, HPO₄^--, HAsO₄^--, B₄O₇^--, Mn⁺⁺, Fe⁺⁺⁺, Al⁺⁺⁺, Zn⁺⁺, Cu⁺⁺, Ni⁺⁺, HBO₂, H₂TiO₃; organic acids: naphthenic (penta- and hexamethylenecarboxylic), humic; of gases, CO₂, CH₄, N₂ are carried out by mineral waters in large quantities, in smaller quantities H₂S, COS, O₂, H₂, Ar, He, Ne, Kr, Xe, as well as radioactive emanations: of colloids—S, Fe(OH)₃, Al(OH)₃, Mn(OH)₂, As₂S₃, FeS, H₂SiO₃, H₂TiO₃, organic substances. The maximum concentration of a given element and the compound in the form of which it is present in mineral water, for the majority of elements, is in a definite dependence on the presence and concentration of a number of other elements or compounds. Thus, the concentration of hydrogen ions determines the degree of dissociation of all weak acids: H₂CO₃, H₂S, H₂Si0₃, H₂TiO₃, H₃PO₄, H₃AsO₄, H₃BO₃, etc. Carbonic acid, hydrogen sulfide, and their ions are connected to each other by the ratio [CO₂ + H₂CO₃] x [HS^-] = 0.3, [H₂S] x [HCO₃^-]. The maximum possible concentrations of Ca(HCO₃)₂, Mg(HCO₃)₂, Fe(HCO₃)₂ depend on the concentration of free carbonic anhydride CO₂. Oxidizers NO₃^-, Fe⁺⁺⁺, O₂ and reducers—H₂S cannot exist simultaneously in any significant quantities. The presence of HS^-, H₂S or CO₃^-- practically excludes the possibility of the presence of metal ions in the solution except for alkali ones. Colloids in mineral waters are often products of the metamorphism of water already after its emergence onto the earth's surface. Thus, colloidal sulfur, colloidal Fe(OH)₃, FeS, etc., are formed. The catalytic action of many mineral waters on various reactions (decomposition of H₂O₂, coloring of guaiac resin) is conditioned by the surface properties of colloidal particles forming in the water. Methods of chemical and physico-chemical investigations of mineral springs are one of the most complex chapters of physical and analytical chemistry; an accurate and complete analysis of mineral water can be performed only in a special, well-equipped laboratory. Sanitary-bacteriological analysis of mineral waters is performed by methods adopted for fresh waters. Designation of the composition of mineral waters until recently was often arbitrary; the composition was presented in the form of oxides, ions, or they were combined into salts quite arbitrarily.

In 1930, at the IV Hydrological Conference under the Administration of Health Resorts of the People's Commissariat of Health, a standard for analysis in ionic form was approved in the form of 5 columns: 1) the name of anions, cations, and non-dissociated compounds; 2) their content in grams per liter; 3) in millimoles (a millimole is the number of milligrams equal to the molecular weight); 4) in milliequivalents (a milliequivalent is the number of milligrams equal to the equivalent weight; a milliequivalent is equal to a millimole divided by the valence of the ion); and 5) in equivalent percentages (the percentage of the sum of milliequivalents of cations or anions). For the characterization and classification of mineral waters, the 5th column—equivalent percentages—is considered decisive. For a visual characterization of mineral water, the IV Hydrological Conference adopted the Kurlov-Karstens formula: at the beginning, the content of gases and active elements is placed (in grams per liter); then the "degree of mineralization"—the sum of all ions and non-dissociated molecules excluding gases (in grams per liter); this is followed by a fraction: in its numerator, the anions are placed in order of decreasing numbers (in equivalent percentages), and in the denominator, the cations (in equivalent percentages). Both are included in the formula only when they are contained in an amount greater than 25 equivalent percentages. At the end of the formula, the water temperature (t°) and the flow rate in hectoliters per day are placed. Example: the Alexandro-Yermolovsky spring in Pyatigorsk: M 1.4 (HCO3) 88 (SO4) 12 / (Ca) 58 (Mg) 24 (Na) 18.

The International Society of Medical Hydrology has a special commission for standardizing descriptions of mineral waters. It has developed a standard similar to the Russian one, differing mainly in that the milligram, not the gram, is taken as the unit. The nomenclature and classification of mineral waters, according to the resolution of the IV Hydrological Conference, must be based on the names of ions, not salts; as a rule, only ions present in quantities of not less than 25 valpercent are included in the name. Therapeutically active elements and gases are included in the name and in the Kurlov formula at concentrations not below: Fe"-10 mg., Al'-5 mg, J'-10 mg, Br'-25 mg, HAs0₄" and HPO₄"-1 mg, H₂S free-10 mg, CO₂ free.-750 mg.-Sources with t° above 35° are called hot; at 20°-35° they are called warm. Thus, names are composed of the names of therapeutically active substances (in order of decreasing concentration in grams), anions (in order of decreasing valpercent values) and cations (in order of decreasing valpercent values). The temperature t° is placed at the end of the name if it deserves it. On the basis of this nomenclature, Prof. V. A. Aleksandrov in 'Fundamentals of Balneology' has developed the latest classification of mineral waters, which has the advantage of unambiguity over all previous ones: each class has certain numerical limits, and no water can fall into two classes at once. As an example, the analysis of the water from the Batalinsky source is given. In old classifications, often still used now, there are many ambiguities; to facilitate the use of old literary data, a summary of the main names along with their corresponding ions is provided: iron sources, ferruginous contain Fe**, steel-Fe", lime-Ca", earthy, earthy-Ca", Mg", Fe", alkaline earth-2 meanings: 1) Ca", Mg", 2) Ca", Mg", K', Na*; alkaline-2 meanings: 1) Na*, K*, 2) waters of alkaline reaction; glauber's-Na₂SO₄; bitter, sulfate, sulfuric-SO/'; gypsum-CaSO₄; saline, muriatic, brine-Cl; gas-usually CO₂, rarely H₂S, CH₄, N₂; sulfide, sulfuric, sulfur, hydrogen sulfide, containing H₂S or HS' or both together [it is more correct to call waters with SO₃" sulfurous, with free (colloidal) sulfur-sulfur waters, with free H₂S-hydrogen sulfide]; carbonic-CO₂, HCO₃', CO₃" (correct only CO₂); carbonate-CO₃"HCO₃'(correct only CO₃"); bicarbonate, hydrocarbonate-HCO₃'; arsenic, arsenic-As. (Overview of old classifications - see Balneology.) - The International Commission for Standardizing Descriptions of Mineral Waters proposed in 1930 a very simple classification-by one predominant or active ingredient, e.g. chloride, iron, etc. This classification has not yet become widespread. The radioactivity of mineral waters is usually measured in units of Mache (ME); it ranges from fractions of ME to thousands; it depends 1) on the gas content - radon emanation (Em); such radioactivity disappears quickly, since the half-life of Em is 3.85 days; or 2) on the salt content of radium itself or other radioactive metals with a long half-life (radium-1760 years); such radioactivity can also increase to certain limits, as the activity of decay products is added to it. - Cryoscopic and ebullioscopic studies (decrease in freezing point and increase in boiling point) of mineral waters determine the total concentration of all substances dissolved in the mineral water, and therefore its osmotic properties, or 'tonicity'. The International Commission for Standardizing Descriptions of Mineral Waters proposed to call 'hypotonic' waters whose osmotic pressure is less than that of a solution containing 9 g NaCl in 1 l, or 303 millimoles of all ions and molecules; 'isotonic' and 'hypertonic' are waters with osmotic pressure equal to or respectively greater than that of this solution. Changes in the composition of mineral water may depend on changes in the source regime or (more often) on changes in conditions when the water comes to the surface. In the first case, changes most often depend on the inflow of fresh water to the main mineral stream; for vadose and mixed sources, fluctuations in composition occur, for example, with seasonal fluctuations in precipitation; such changes are always accompanied by changes in flow rate and usually temperature. Therefore, the source's feeding area must be protected from the possibility of pollution and from violations of the normal water regime, which is the task of sanitary protection of mineral waters (see). Mineral waters-When mineral water comes to the surface, its conditions of existence change radically; this is always accompanied by some change in composition; often these changes are so great that after a short time they completely devalue the mineral water. When the temperature of the water changes, the solubility conditions change, and substances that were in a saturated solution can be released. Thus, thermal sources upon cooling often deposit siliceous sediments; cold sources saturated with gas, when heated, release it in the form of bubbles. A decrease in pressure also causes the release of gases saturating the water in bubbles. However, gas loss occurs not only by bubbles, but also by the invisible diffusion of gas from water into air. The loss of CO₂ is especially important, because due to this the reaction of the water changes (increase in pH), which is the transition of bicarbonates to carbonates and the precipitation of CaCO₃, MgCO₃, Fe(OH)₃. They form deposits at the source exit, called travertines. With a decrease in the concentration of carbonic acid (corresponding to an increase in pH), the conditions of sulfide-carbonate equilibrium change, and part of the free H₂S passes into a 'bound' state - into HS'.-At the same time, the process of saturation of mineral water with atmospheric gases occurs; oxygen is especially important here, as it determines a number of oxidation processes that radically change the composition of mineral water. Ferrous compounds oxidize into ferric compounds, which are more prone to hydrolysis and therefore usually precipitate; the same applies to manganese. Free hydrogen sulfide oxidizes depending on conditions to sulfur or to sulfuric acid. Sulfides (S") and hydrosulfides (HS') upon oxidation give hyposulfite (S₃O₃") and sulfate (SO/')- At the same time, sulfite (SO₃") appears as an intermediate product in the solution. Microorganisms play a large role in all these processes; their organic substance is often the binding material for sediments S, Fe(OH)₃ and others,-thus gelatinous masses 'muff', 'barezina' and other sediments are obtained; these accumulations cause clogging of the pipes through which mineral water is supplied to baths or drinking pavilions (see). For balneotechnics, the physical properties of mineral water are especially important. Temperature is measured in degrees Celsius. The true thermal conductivity of water (K) is very small, but in practice the transfer of heat from the bath to the patient's body and back occurs very quickly due to convective currents, thanks to which the layer of water adjacent to the body constantly changes; heat transfer is especially accelerated in so-called flow baths (Strombader), in Charcot showers, etc. The heat capacity (C) ranges from 1 (pure water) to 0.75 (strong brines), i.e. brines give off or take away less heat from the body than waters with low mineralization at the same temperature. The specific gravity (d) of mineral waters is usually close to 1; it increases with the amount of dissolved salts and in brines reaches 1.3; the specific gravity determines the pressure of the water on the patient's body immersed to a certain depth. Electrical conductivity Γ^-1 is measured in reciprocal ohms per 1 cm³; it is important for galvanomineral baths; it depends on the composition of salts and their degree of dissociation.

The materials used for the capture of mineral waters and for conducting water to the place of use are acted upon by the water and themselves influence its composition. Cement and concrete are corroded by carbonic water and enrich it with calcium; sulfate waters cause the destruction of concrete due to volume changes during the formation of complex compounds in the concrete. Iron pipes are subject to the action of carbonic, hydrogen sulfide, and brine waters; sulfide waters act particularly strongly on all materials (except wood and glass) at their point of contact with air; the sulfuric acid formed here corrodes everything in a very short time; therefore, sulfide waters must be conducted completely hermetically, ensuring constant filling of the entire cross-section of the pipe with water. The possibility of significant changes in the composition of mineral water both underground and on the surface necessitates constant control of the composition through brief analyses. Usually, the daily determination of 1-2 ingredients is quite sufficient, e.g. for saline waters-chlorine; for hydrogen sulfide waters-H₂S, alkalinity (pH); for carbonic waters-free CO₂ and pH, etc. In control, exclusively volumetric or colorimetric methods are used as requiring a minimum of time. Small changes in the composition of water can be easily detected by changes in its electrical conductivity. There are self-recording instruments that register fluctuations in the electrical conductivity of water. The timing and principles of observation of mineral waters and their chemical control were established in 1925 by the Main Resort Administration. Fluctuations in the flow rate or temperature of the source always indicate some change in composition. Heating and cooling of mineral water should be done, if possible, avoiding contact with air. The best system is closed coils cooled externally by water; for heating, the most rational method is the use of detachable coils immersed in the bath and heated internally by steam. It is necessary to avoid overheating the water to prevent loss of gases. When heating or storing water in tanks, wooden covers floating on the water surface are of great service, as they minimize the surface of contact with air. The basic technical conditions for bottling mineral waters are sterility and absence of aeration. When storing and transporting mineral waters, bottles should be kept in a horizontal position so that the cork is always moistened with water; otherwise, the cork dries out, the tightness of the seal is lost, and with the escape of gases, the composition of the water changes. A low temperature is an essential condition for the stability of composition; therefore, mineral waters are usually stored in cellars and icehouses, transported in isothermal cars. Saturation of mineral water with CO₂ significantly increases not only its taste qualities but also the stability of the composition of mineral water in the bottle; nevertheless, the therapeutic properties of bottled water are not identical to the properties of water at the sources. Artificial mineral waters are usually prepared from chemically pure salts according to the analysis of natural water; complete identity of composition and properties of artificial and natural water can be achieved only with great difficulty; special difficulties are presented by the exact imitation of the composition of dissolved gases and the properties of colloids. Of artificial mineral waters, only saline baths, baths with sea salt, and carbonic baths have become widespread. Artificial hydrogen sulfide baths are beginning to come into use. The therapeutic application of mineral waters-see Balneotherapy. Sanitary protection zones of mineral waters-see Mountain-sanitary protection.