Groundwater samples were evaluated throughout Turkana County (Kenya, East Africa) while looking for drinking water sources. Some samples showed high concentrations of fluoride with values in the range of 0.15–5.87 mg/L. Almost 50% of the samples exceeded the WHO and Kenyan potable water standard guideline value of 1.5 mg/L for drinking water quality. The hydrogeochemical studies revealed that the dominant cation in water is Na⁺ and the dominant anion is HCO₃⁻ resulting in Na-HCO₃ type of groundwater, followed by Ca/Mg-HCO₃ or Na-SO₄ and Na-Cl in a few cases. Speciation modelling revealed that the groundwater is undersaturated with respect to gypsum and anhydrite, mostly undersaturated with respect to fluorite (6 samples are at equilibrium), and supersaturated or at equilibrium with respect to calcite (CaCO₃). Precipitation of calcite favours the dissolution of F-rich minerals in the alkaline medium. Simultaneously, groundwater is enriched with sodium and bicarbonate, probably as a result of chemical weathering of Na-feldspar. Investigated groundwater can be presumably used for drinking purposes from 17 wells, but a detailed investigation of other trace element concentrations is necessary.

SMART LEVEE IN POLAND. FULL-SCALE MONITORING EXPERIMENTAL STUDY OF LEVEES BY DIFFERENT METHODS

The most promising Polish region in terms of its geothermal resource potential is the Podhale Trough in the Inner West Carpathians, where the thermal water occurs in the Eocene-Mesozoic strata. The origin and conditions of formation of the chemical composition of the thermal water are different in a regional scale due to the impact of infiltrating water on the chemical compounds present in nearby thermal intakes, chemical processes responsible for the concentration of major elements and residence time. The article presents the regional conceptual model in regard to the factors controlling the chemistry of thermal water from Podhale Trough and the conditions of its exchange. It was allowed by performing the hydrogeochemical characteristics of studied water and analyzing its changes according to flow direction from HCO₃-Ca-Mg type to SO₄-Cl-Na-Ca and SO₄-Ca-Mg types. The hydrogeochemical modelling was also made allowing identification of the impact of reservoir rocks on the formation of the chemical composition. For confirmation of the theories formulated and for more accurate interpretation of the results obtained from hydrogeochemical modelling, hydrochemical indices were calculated, i.e., rHCO₃⁻/rCl⁻, rNa⁺/rCl⁻, rCa²⁺/rMg²⁺, rCa²⁺/(rCa²⁺ + rSO₄²⁻) and rNa⁺/(rNa⁺ + rCl⁻). The results revealed the most important processes evolving the chemistry of thermal water are progressive freshening of the thermal water reservoir, which in the past was filled with salty water, dissolution of gypsum, and ongoing dolomitization. Conducted research presents the important factors that in the case of increased exploitation of thermal water in the Podhale Trough, may influence the quality of thermal water in terms of its physical and chemical parameters.

A proper methodology for collecting samples of geothermal water makes it possible not only to determine the hydrochemical characteristics of the water, but also to assess its temporal and spatial variability. The knowledge about the concentration of selected elements as well as the values of field measurements can help to indicate their impact on other environments and the processes that occur in a geothermal system. An important issue is the quality of the results obtained from in-situ measurements of unstable parameters, i.a. pH and electrical conductivity (EC). The results of measurements presented in the paper were completed with the use of three different devices in hot and cooled raw geothermal water (field test). The research was performed during two seasons of increased (winter) and lower (summer) exploitation of geothermal water. The percentage difference between EC at temperatures of 22°C and 75°C was 3.27%; however, for the pH the observed percentage difference was only 0.26%. An additional experiment was carried out on a laboratory scale to indicate the influence of temperature changes on pH and EC measurements.

The paper presents the possibility of using data mining tools — artificial neural networks — in prediction of hydrometer reading after 24 h in order to limit the duration of the test to 4 h. The authors analysed a database of 693 granulometric composition analysis results of genetically different soils with the use of radial basis function network (RBF) and multilayer perceptron (MLP). The calculations performed showed that it is possible to use MLP to shorten the test time without affecting the quality of the results. The presented accuracy of the model, in the range of 0.55–0.72, allows one to determine the content of silt and clay fractions with an accuracy of 0.49% for equivalent diameter (dT) and 1.50% for percentage of all particles with a diameter smaller than dT (ZT). The results were better than that achieved using linear re-gression models with all predictors (REG), stepwise regression models (SREG), and classification and regression trees (CRT). Taking into account the uncertainty of hydrometric determinations, the obtained forecast values is lower than this uncertainty, therefore neural networks can be used to predict the results of this type of research.

Iodine is a microelement which occurs in natural water in different concentrations dependent on water type, origin and total dissolved solids concentration. The objects of research were natural geothermal water. In this paper, the fitness of the inductively coupled plasma mass spectrometry (ICP-MS) method for iodine determination in water with higher temperatures was tested and selected methodological problems were discussed. Basic method parameters (precision, accuracy, linearity, uncertainty) were determined. Calculated statistical parameters of the validated method fulfil the assumed criteria. The received results (correlation coefficient equal to 0.999) show that the linearity of the ICP-MS method is good. The accuracy was expressed as recovery (R) and according to the literature is at an acceptable level. The results of precision assessments (RSD) also correspond to the literature data.