Normal groundwaters

Normal groundwaters have a low content of dissolved solid substances, gases or microorganisms which do not satisfy any of the criteria for mineral waters. The reserves of groundwater are made up by soaking of atmospheric and surface waters, through permeable layers (infiltration), and also by the condensation of water vapour in the soil and condensation of the vapours from magma. 

Chemical changes of groundwaters are the result of complex processes taking place in the water-rock-atmosphere system. These are physical, chemical and biochemical processes taking place simultaneously or in a close sequence. Dissolution, hydrolysis, adsorption, ion exchange, oxidation and reduction, diffusion and osmosis are of decisive importance in the formation of a given chemical composition. 

Many of physico-chemical processes taking place in the system water-rocks-atmosphere have an oxidation or reduction character. Insoluble sulphides are oxidized in the presence of oxygen into sulphates. The rate of oxidation depends on the grain size of the sulphides, the degree of rock protection, conditions of oxygen supply, etc. Thus, the natural waters are enriched by sulphate ions in the chemical erosion of eruptive rocks. 

In sedimentary rocks with a porous structure adsorption processes are involved to a considerable degree. Via the adsorption phenomena, natural water gets rid of many, sometimes undesirable substances, e.g. high-molecular compounds, as well as of some elements (for example, Cu, Pb, Zn, Sr) which enter the waters together with wastewaters. 

The transfer of salts by diffusion and the accompanying processes can change the total mineralization of the chemical composition of groundwaters. 

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The coupons were contacted with tracer-free groundwater solutions, which were assayed after 28 d to determine the amount of activity that is reversibly bound to the granite under normal groundwater conditions. 

Just a few ions like Na+, K+, N03 or Cl+ are soluble to the same extent across the whole range of pH values of normal groundwater. Mainly the dissolution of metals is strongly pH dependent. While precipitating as hydroxides, oxides, and salt under basic conditions, they dissolve and are mobile as free cations under acid conditions. Aluminum is soluble under acid as well as under basic conditions. It precipitates as hydroxide or clay mineral in the pH range of 5 to 8. 

The act of pumping liquid into a formation creates a zone of high pressure potential. Because of this, the entering fluid flows away from this zone in all directions, locally changing the normal groundwater flow pattern. At low pumping pressure, the excess pressure potential dissipates at short distances from the injection point, and it may be possible to establish new equilibrium conditions with steady-state inflow. 

The content of calcium or magnesium in surface and normal groundwaters is unimportant from the viewpoint of health. As for the taste, the best waters are those which contain calcium and hydrogen carbonates. A magnesium content above 250 mg 1 causes a bitter taste. Waters with high concentrations of magnesium and sulphates have laxative effects. 

In fresh waters strontium is present at higher concentrations than barium, but some mineral waters can be an exception. Both elements occur in surface and normal groundwaters at concentrations of only units or tenths of/igr ... 

In surface and normal groundwaters aluminium occurs only in hundredths to tenths of mg 1 . High aluminium content was found in acid waters from the vicinity of deposits of some sulphide-containing ores or slates, by the oxidation of which sulphuric acid was formed, which decomposed the neighbouring minerals. 

The content of iron in surface and normal groundwaters is not significant from the viewpoint of hygiene. However, it influences the sensory properties of water. Taste is affected at concentrations from about 0.1-1.5 mg 1 . At concentrations higher than 0.5 mg 1 separation of the hydrated oxide... 

Chlorine occurs most widely in the form of chlorides. In nature this anion is present in all waters at fairly high concentrations. Together with hydrogen carbonates and sulphates chlorides are the chief anions in waters. In surface and normal groundwaters they are present in amounts ranging from units to tens of mg 1 . Chlorides may predominate in groundwaters from great depths. 

Mineral waters in the broader sense of the word are waters which differ from normal groundwaters by their chemical composition and physical properties, and they are formed by particular circumstances occurring in the groundwater circulation. 

The process is understood to have been applied successfully to many sites in Europe. The treatment undoubtedly improves the characteristics of the soil and sludge and immobilises the organic matter to a degree. However, there is concern as to whether the treated material meets the requirements of the appropriate leaching tests [32.35, 32.36]. The latter simulates the effects of acidic rain, which is much more aggressive than normal groundwater. 

Evaluation of the capability of the plant to withstand the effects of severe hydrometeorological phenomena will be presented at the time of application for a specific site. For purposes of the analysis presented herein, yard grade for "safety-related" structures is set at an elevation above the water level that can be reached by the probable maximum event. Normal groundwater elevation is assumed to be 8 feet below grade. 

Facilities which must serve to ensure, with a high level of confidence, that systems or components they house fulfill their lOCFRlOO-related radionuclide control functions under design basis conditions are designed for a normal groundwater level of 2.4 m (8 ft) below the ground surface and a maximum groundwater level at the ground surface. 

Uranous complexes tend to be insoluble at low temperatures and at pH 4.5-7. At temperatures above 150°C uranous transport may become dominant. Depending on ligand concentrations, uranous fluoride, phosphate, sulphate and especially hydroxide compounds are important species under these conditions, but uranous carbonate complexes are not. Uranyl species are soluble over a wide range of conditions. In normal groundwater, at temperatures of 25°C, uranyl fluoride complexes are dominant at pH <4, uranyl phosphates at pH 4-7.5 and uranyl di- and tricarbonate complexes at pH >7.5. Uranyl silicate complexes are probably insignificant, and at temperatures near 100°C uranyl hydroxides predominate, whereas uranyl carbonate complexes dissociate. ... 

Where the formalism is supported by the physical chemistry of the radionuclide scavenging process, it is possible to estimate the theoretical efficiency of a reactive barrier based on simple mass balance relationships. Specifically, the lotal capacity (mg contaminant g of barrier material) of a reactive barrier is equal lo the product j(mL g ) x Q (mg mL ). The total number of volumes that can pass through a unit area of the barrier until contaminant breakthrough occurs is equal (o the product A, (inl. g ) x Mass in column (g)/Column pore volume (mL). The retardation of contiiiiiiiiant velocity (V. ) relative to the normal groundwater veloc-... 

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