Partial pressures of CO2 in epikarstic zone deduced from hydrogeochemistry of permanent drips, the Moravian Karst, Czech Republic

Permanent drips from straw stalactites of selected caves of the Moravian Karst were studied during one-year period. A hypothetical partial pressure of CO2 that has participated in limestone dissolution, PCO2(H)=10-1.53±0.04, was calculated from the dripwater chemistry. The value significantly exceeds the partial pressures generally measured in relevant shallow karst soils, PCO2(soil)=10-2.72±0.02. This finding may have important implications for karst/cave conservation and paleoenvironmental reconstructions.Keywords: cave, carbon dioxide, dripwater, hydrogeochemistry,hypothetical partial pressure, karst processes, karstification model

Impact of uranium mines closure and abandonment on groundwater quality

The aim of the study is to assess the evolving mine water quality of closed uranium mines (abandoned between 1958 and 1992) in the Czech Republic. This paper focuses on the changes in mine water quality over time and spatial variability. In 2010, systematic monitoring of mine water quality was performed at all available locations of previous uranium exploitation. Gravity flow discharges (mine adits, uncontrolled discharges) or shafts (in dynamic state or stagnating) were sampled. Since the quality of mine water results from multiple conditions—geology, type of sample, sampling depth, time since mine flooding, an assessment of mine water quality evolution was done taking into account all these conditions. Multivariate analyses were applied in order to identify the groups of samples based on their similarity. Evaluation of hydrogeochemical equilibrium and evolution of mine waters was done using the Geochemist’s Workbench and PHREEQC software. The sampling proved that uranium concentrations in mine waters did not predominantly exceed 0.45 mg/L. In case of discharges from old adits abandoned more than 40 years ago, uranium concentrations were below the MCL of US Environmental Protection Agency for uranium in drinking water (0.03 mg/L). Higher concentrations, up to 1.23 mg/L of U, were found only at active dewatered mines. Activity concentration of 226Ra varied from 0.03 up to 1.85 Bq/L except for two sites with increased background values due to rock formation (granites). Radium has a typically increasing trend after mine abandonment with a large variability. Concerning metals in mine water, Al, Co and Ni exceeded legislative limits on two sites with low pH waters. The mine water quality changes with a focus on uranium mobility were described from recently dewatered mines to shafts with water level maintained in order to prevent outflows to surface water and finally to stagnating shafts and discharges of mine water from old adits. The results were in good agreement with published experience on mine water stratification, its disturbance by pumping or natural water decant and the “first flush” phenomenon after mine flooding.Web of Science20117602759

Aplikace geochemického modelování při řešení aktuálních enviromentálních a hydrogeologických problémů

Prezenční541 - Institut geologického inženýrstvíNeuveden

Relationship between carbon dioxide in Balcarka Cave and adjacent soils in the Moravian Karst region of the Czech Republic

Carbon dioxide concentration, air temperature, and humidity were monitored at (1) two cave sites and (2) three adjacent karst soils. The data over a one-year period are supported by dripwater chemistry and cave visiting frequency. The results indicate that the sources of cave CO2 are anthropogenic and epikarstic ones in addition to ordinary soils. Epikarstic CO2 produced under almost stationary conditions probably control dripwater chemistry and cave’s CO2 maxima. Based on breathing and door opening, anthropogenic activity affects instantaneous cave CO2 levels, depending on site volume/position and visitor number. A conceptual model of the CO2 dynamics of the soil-cave system is proposed. The study indicates that karst processes such as limestone dissolution and speleothem growth need not be entirely/directly controlled by external climatic conditions.411281

Carbon dioxide in the soils and adjacent caves of the Moravian Karst

Variations of soil/cave CO2 concentrations and further variables such as temperature, humidity, and cave visitor attendance were studied in two sites of the Moravian Karst (Czech Republic). All the variables showed the same seasonality; they were strongly correlated with each other. The dependence of soil CO2 levels on soil air temperature and absolute humidity was confirmed. Individual effects could not be distinguished because of multicollinearity. The effect of vegetation on soil CO2 production was not recognized. Cave attendance was identified as the most significant predictor of cave CO2 levels. Other variables, soil CO2 and temperature gradients, were less significant. A spurious relationship was alternatively considered, in which external temperature was the universal predictor of cave CO2 levels

Ogljikovi dioksid v prsti in jamah na Moravskem krasu

Variations of soil/cave CO2 concentrations and further variables such as temperature, humidity, and cave visitor attendance were studied in two sites of the Moravian Karst (Czech Republic). All the variables showed the same seasonality; they were strongly correlated with each other. The dependence of soil CO2 levels on soil air temperature and absolute humidity was confirmed. Individual effects could not be distinguished because of multicollinearity. The effect of vegetation on soil CO2 production was not recognized. Cave attendance was identified as the most significant predictor of cave CO2 levels. Other variables, soil CO2 and temperature gradients, were less significant. A spurious relationship was alternatively considered, in which external temperature was the universal predictor of cave CO2 levels

Hydrogeochemical characteristics of the groundwater in the quaternary aquifer of western fringes of El-Minia Governorate, Egypt using an integration of geochemical modeling and geo-statistical techniques

Groundwater is a very important source of drinking and irrigation water especially in areas with little to no surface water sources. In the western desert of Egypt, groundwater acts as the main source of irrigation in the new reclamation project. The authors of the article used major constituents and trace elements chemistry as well as bacteriological and biological water analysis to assess the hydrogeochemical characteristics in the western bank of the River Nile, West El-Minia District. In order to fulfill the scope of work for this study, 88 groundwater samples were collected from the Pleistocene aquifer which represents the main aquifer in the study area. The groundwater samples were analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), major cations (Ca2+, Mg2+, Na-, K+), major anions (HCO3-, SO42- and Cl-) and trace metals (Mn, Cu, Pb, Zn, Ni, Co, As, Hg, Se, Al, Cd, Cr, B, and Fe). Microbiological and microscopic studies of the collected water samples were carried out to determine the micro-organisms' in order to confirm the safety of the water for human consumption. Also, statistical analysis and hydrogeochemical modeling were used to interpret the collected data. The study revealed that in all the collected water samples, alkaline earth metals have values higher than alkalies and are of meteoric origin. The groundwater chemistry is mainly controlled by rock weathering with a secondary contribution from anthropogenic sources. Forty-nine percent (49%) of analyzed water samples have trace constituents above the recommended limits for water use for drinking and irrigation purposes. The highest linear correlation was shown between TDS and EC, HCO3, Na+, Ca2+ and Mg2+, all macro-components and chlorides, between boron and chrome, as well as cobalt and lead. All sampled waters were classified as Ca-HCO3 water type and calcite precipitate in all collected water samples.Web of Science18915113

The abandoned underground mine as a semi-natural ecosystem: The story of Flaschar's Mine (Czechia)

We have investigated a typical abandoned underground slate mine situated in the Bohemian Massif (Central Europe) in order to describe its elementary components and to outline the varied relations among them. Based on the results from geological, geomorphological, hydrological, microclimatic, and biological investigation, we have defined the abandoned underground mine as an important but overlooked semi-natural ecosystem that represents an azonal and relatively fast evolving environment. Unlike any other studies published so far, we have found it also vulnerable in terms of fragility and time-limited stability. Our results together with a comprehensive discussion highlight the fundamental features of the abandoned underground mine and finally serve as a basis on which we introduce a conceptual model of the abandoned underground mine. The complex and interdisciplinary perception of abandoned underground mines is crucial for appropriate environmental assessment, tourist management, natural protection or remediation.Web of Science213art. no. 10617