Audra P.,University of Nice Sophia Antipolis |
Bosak P.,Institute of Geology of the CAS |
Bosak P.,University of Cambridge |
Bosak P.,University of Savoy |
And 12 more authors.
International Journal of Speleology | Year: 2017
Kahf Kharrat Najem Cave is a small cave in United Arab Emirates (UAE) that hosts a bat colony which is the source of guano deposits and peculiar centimeter-long yellowish stalactites. The mineralogy and geochemistry of these deposits were analyzed using powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopic microanalysis (EDX), scanning electron microscope (SEM), and stable isotope composition (δ13C and δ15N). Urea CO(NH2)2 was found to be the main compound of these stalactites, while allantoin C4H6N4O3 was found to be an accessory urea byproduct. This paper is the first to mention allantoin in a cave environment. We also identified rare sulfate minerals (aphthitalite, alunite) and phosphates that probably correspond to the archerite-biphosphammite series. The occurrence of these rare bat-related minerals is due to the extremely dry conditions in the cave, which accounts for the extraordinary preservation of the guano deposits and allows for the crystallization of these very soluble minerals. © 2016, Societa Speleologica Italiana. All rights reserved.
Vanek A.,Czech University of Life Sciences |
Grosslova Z.,Czech University of Life Sciences |
Mihaljevic M.,Charles University |
Trubac J.,Charles University |
And 12 more authors.
Environmental Science and Technology | Year: 2016
Here, for the first time, we report the thallium (Tl) isotope record in moderately contaminated soils with contrasting land management (forest and meadow soils), which have been affected by emissions from coal-fired power plants. Our findings clearly demonstrate that Tl of anthropogenic (high-temperature) origin with light isotope composition was deposited onto the studied soils, where heavier Tl (ϵ205Tl ∼ -1) naturally occurs. The results show a positive linear relationship (R2 = 0.71) between 1/Tl and the isotope record, as determined for all the soils and bedrocks, also indicative of binary Tl mixing between two dominant reservoirs. We also identified significant Tl isotope variations within the products from coal combustion and thermo-desorption experiments with local Tl-rich coal pyrite. Bottom ash exhibited the heaviest Tl isotope composition (ϵ205Tl ∼ 0), followed by fly ash (ϵ205Tl between -2.5 and -2.8) and volatile Tl fractions (ϵ205Tl between -6.2 and -10.3), suggesting partial Tl isotope fractionations. Despite the evident role of soil processes in the isotope redistributions, we demonstrate that Tl contamination can be traced in soils and propose that the isotope data represent a possible tool to aid our understanding of postdepositional Tl dynamics in surface environments for the future. © 2016 American Chemical Society.
Ludvikova J.,Czech Institute of Chemical Process Fundamentals |
Jiratova K.,Czech Institute of Chemical Process Fundamentals |
Klempa J.,Czech Institute of Chemical Process Fundamentals |
Boehmova V.,Institute of Geology of the CAS |
Obalova L.,VSB - Technical University of Ostrava
Catalysis Today | Year: 2012
Catalytic activity of the Co-Mn-Al mixed oxide catalysts (Co:Mn:Al molar ratio of 4:1:1) supported over titania was examined in total oxidation of ethanol. The prepared catalysts were characterized by chemical analysis (AAS), surface area measurements, and temperature programmed techniques (TPR, TPD). In ethanol oxidation, the catalysts activity gradually increased with increasing active phase content. Low concentration of Co-Mn-Al oxides in the catalyst negatively affected formation of reaction byproducts: carbon monoxide production steeply increased when Co + Mn metals concentration were lower than 5 wt.%. On the other hand, formation of the second main reaction intermediate, acetaldehyde was limited, when acidity of the catalyst was not high, i.e. concentration of Co-Mn metals over titania was low. © 2011 Elsevier B.V. All rights reserved.
Slavik L.,Institute of Geology of the CAS |
Valenzuela-Rios J.I.,University of Valencia |
Hladil J.,Institute of Geology of the CAS |
Chadimova L.,Institute of Geology of the CAS |
And 4 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2016
High-resolution petrophysical correlation methods were applied, for the first time, to mid-Paleozoic rocks of the Pyrenees. The methods included magnetic susceptibility measurements (MS), gamma-ray spectrometry (GRS), and alignment of MS logs using the dynamic time-warping (DTW) algorithm. Conodont biostratigraphy provided the basic framework necessary for work with the GRS and MS logs. Despite differences in the sediment patterns and accumulation/erosion rates, the logs from two selected sections in the Spanish Central Pyrenees show a striking symmetry that correlates well with the previously published logs from the Barrandian area in the Czech Republic. The high similarity between the petrophysical records from paleogeographically related but distant areas has the potential to contribute to the current discussions about the eustatic and climatic changes that took place in the overall greenhouse settings, where evidence for any polar ice sheets is still absent. In addition to the extant evidence of a major Lochkovian-Pragian offlap, combined with sea level lowering known from the North America, evidence about a major sea level fall and drastic reconstruction of the climatic system in the Pragian is now expanding over significant parts of the peri-Gondwanan belt. The data from Spain provide many new details about this change, including the phenomenon of a stratigraphically condensed upper Lochkovian, a dramatically different type of sedimentation in the Pragian, and a GRS-Th-and-MS anomalous stratigraphic interval in the middle Pragian. The multifaceted evidence allows us to determine the essential parts of the Pragian as a still "hot and humid" period, even with the strong differences from the possibly "extremely hot" Lochkovian. © 2016 Elsevier B.V..
Kodesova R.,Czech University of Life Sciences |
Nemecek K.,Czech University of Life Sciences |
Zigova A.,Institute of Geology of the CAS |
Nikodem A.,Czech University of Life Sciences |
Fer M.,Czech University of Life Sciences
Biologia (Poland) | Year: 2015
Plants influence the water regime in soil by both water uptake and an uneven distribution of water infiltration at the soil surface. The latter process is more poorly studied, but it is well known that roots modify soil structure by enhancing aggregation and biopore production. This study used a dye tracer to visualize the impact of plants on water flow in the topsoil of a Greyic Phaeozem. Brilliant blue was ponded to 10 cm height in a 1 m x 1 m frame in the field immediately after harvest of winter wheat (Triticum aestivum L.). After complete infiltration, the staining patterns within the vertical and horizontal field-scale sections were studied. In addition, soil thin sections were made and micromorphological images were used to study soil structure and dye distribution at the microscale. The field-scale sections clearly documented uneven dye penetration into the soil surface, which was influenced by plant presence and in some cases by mechanical compaction of the soil surface. The micromorphological images showed that root activities compress soil and increases the bulk density near the roots (which could be also result of root water uptake and consequent soil adhesion). On the other hand in few cases a preferential flow along the roots was observed. © Institute of Molecular Biology, Slovak Academy of Sciences 2015.
Navratil T.,Institute of Geology of the CAS |
Shanley J.,U.S. Geological Survey |
Rohovec J.,Institute of Geology of the CAS |
Oulehle F.,Czech Geological Survey |
And 4 more authors.
Journal of Geochemical Exploration | Year: 2015
The Czech Republic was heavily industrialized in the second half of the 20th century but the associated emissions of Hg and S from coal burning were significantly reduced since the 1990s. We studied dissolved (filtered) stream water mercury (Hg) and dissolved organic carbon (DOC) concentrations at five catchments with contrasting Hg and S deposition histories in the Bohemian part of the Czech Republic. The median filtered Hg concentrations of stream water samples collected in hydrological years 2012 and 2013 from the five sites varied by an order of magnitude from 1.3 to 18.0ngL-1. The Hg concentrations at individual catchments were strongly correlated with DOC concentrations r from 0.64 to 0.93 and with discharge r from 0.48 to 0.75. Annual export fluxes of filtered Hg from individual catchments ranged from 0.11 to 13.3μgm-2yr-1 and were highest at sites with the highest DOC export fluxes. However, the amount of Hg exported per unit DOC varied widely; the mean Hg/DOC ratio in stream water at the individual sites ranged from 0.28 to 0.90ngmg-1. The highest stream Hg/DOC ratios occurred at sites Pluhův Bor and Jezeří which both are in the heavily polluted Black Triangle area. Stream Hg/DOC was inversely related to mineral and total soil pool Hg/C across the five sites. We explain this pattern by greater soil Hg retention due to inhibition of soil organic matter decomposition at the sites with low stream Hg/DOC and/or by precipitation of a metacinnabar (HgS) phase. Thus mobilization of Hg into streams from forest soils likely depends on combined effects of organic matter decomposition dynamics and HgS-like phase precipitation, which were both affected by Hg and S deposition histories. © 2015 Elsevier B.V.
Zigova A.,Institute of Geology of the CAS |
Stastny M.,Institute of Geology of the CAS
Acta Geodynamica et Geomaterialia | Year: 2015
The development of soil cover on loess in regions of Cretaceous sediments and Devonian limestones in the Bohemian Massif was analysed. The study was performed in areas with different land use. Parent material was characterized on the basis of thin section study. Soils were evaluated by macromorphological analysis, particle size distribution, chemical properties, parameters of soil organic matter and mineral composition of clay fraction. The results revealed differences in the formation of soil cover which are predominately connected with geological conditions. The main pedogenetic process for Bohemian Cretaceous Basin is humification. Pedogenetic clay differentiation is relatively slight. Intense pedogenetic clay differentiation, less pronounced processes of litter formation and humification are characteristic for soils in the Devonian limestone areas. The intensity of processes of pedogenetic clay differentiation is influenced by pH values. The quality and quantity of soil organic matter were influenced by the source of biomass, biological activity and type of land use. Petrography of parent material from thin sections shows some differences among features of Ck horizons. The most abundant minerals of clay fraction of the studied soil are quartz, illite and kaolinite. Bt horizons of Albic Luvisols have an elevated content of illite. © 2015 Academy of Sciences of the Czech Republic. All Rights Reserved.
Bella P.,State Nature Conservancy of the Slovak Republic |
Bella P.,Catholic University in Ruzomberok |
Bosak P.,Institute of Geology of the CAS
Acta Carsologica | Year: 2015
Ceiling channels belong to specific geomorphological forms occurring only in caves. Their origin has been commonly connected with the paragenesis. According to review articles, the terms of ceiling channel and paragenesis were defined by Philippe Renault (1958) for the first time. Nevertheless, Zdeněk Roth in his study of morphology and geomorphological evolution of the Domica Cave (southern Slovakia) published in 1937 (in Czech with long French summary) not only described ceiling channels, but he presented also their definition. Roth and other authors used the term later in describing features of several caves in Slovakia and Hungary. Based on original Roth observations, Josef Kunský defined the term generally in his textbook (1950 in Czech, 1956 in Polish and 1958 in French). The description of paragenetic ceiling channels by Renault (1958) can be considered as the first one only in Western European karstology literature. © 2015 Zalozba Z R C. All rights reserved.
Zitt J.,Institute of Geology of the CAS |
Vodrazka R.,Czech Geological Survey |
Hradecka L.,Czech Geological Survey |
Svobodova M.,Institute of Geology of the CAS |
And 2 more authors.
Cretaceous Research | Year: 2015
Dark grey strata belonging to the basal horizons of the Bílá Hora Formation (lower Turonian) were exposed during quarrying at the locality of Plaňany (Bohemian Cretaceous Basin). Based mainly on quarry maps, the early Turonian rocky bottom was reconstructed in the area of about 14,800 m2. Two sedimentologic and palaeoecological settings were recognized in the area. Dark grey deposits form part of the first setting, representing a fill of large and deep depressions on the northern foot of the Plaňany elevation. The second setting with a phosphatic lag is located on the elevated part of the area. Dark grey sedimentation belongs to the UC6a and particularly to the UC6b nannoplankton zones. During the latter zone the dark sedimentation passed upwards into light siltstones. The enrichment of Corg and S, clay minerals with an important kaolinite peak, formation of framboidal pyrite and the enrichment of macrofauna and phosphatic particles are characteristic of the basal portions of the dark deposits. The sulphate reduction zone is suggested for this sedimentary environment. In the associations of phosphatic particles, shark coprolites, faecal pellets and sponge fragments prevail. No phosphatic lag is developed. On the other hand, the phosphatic lag directly overlying the Cenomanian relics is most characteristic of the second setting. This lag is a product of sedimentary condensation, characterized by a long-lasting concentration of phosphatic particles and phosphogenesis, accompanied by encrustation of closely adjacent free rock surfaces by a faunal community with Terebella. Additional biostratigraphic data presently contributed to a proposed correlation of both settings. Micropalaeontological data (foraminifera, palynomorphs, nannoplankton) indicate that the phosphatic lag and basal dark grey deposits may be approximately coeval. The stagnant depositional conditions with only very slow sea-level rise are thought to have lasted for a relatively long period that includes a significant part of the Whiteinella archaeocretacea Zone (lowermost Turonian). In elevated parts, condensation could proceed under conditions of prevailingly weak currents and strong oxidation of organic matter, while decomposition of organic matter was probably very slow and incomplete in depressions below the elevation. The sedimentary condensation in both settings is highlighted by the remarkable formation of abundant glauconite in local deposits. © 2015 Elsevier Ltd.
PubMed | CAS Institute of Biophysics, University of Chicago, Martin Luther University of Halle Wittenberg, Institute of Geology of the CAS and 3 more.
Type: Journal Article | Journal: The New phytologist | Year: 2016
Cadmium (Cd) is an important environmental pollutant and is poisonous to most organisms. We aimed to unravel the mechanisms of Cd toxicity in the model water plant Ceratophyllum demersum exposed to low (nM) concentrations of Cd as are present in nature. Experiments were conducted under environmentally relevant conditions, including nature-like light and temperature cycles, and a low biomass to water ratio. We measured chlorophyll (Chl) fluorescence kinetics, oxygen exchange, the concentrations of reactive oxygen species and pigments, metal binding to proteins, and the accumulation of starch and metals. The inhibition threshold concentration for most parameters was 20nM. Below this concentration, hardly any stress symptoms were observed. The first site of inhibition was photosynthetic light reactions (the maximal quantum yield of photosystem II (PSII) reaction centre measured as Fv /Fm , light-acclimated PSII activity PSII , and total Chl). Trimers of the PSII light-harvesting complexes (LHCIIs) decreased more than LHC monomers and detection of Cd in the monomers suggested replacement of magnesium (Mg) by Cd in the Chl molecules. As a consequence of dysfunctional photosynthesis and energy dissipation, reactive oxygen species (superoxide and hydrogen peroxide) appeared. Cadmium had negative effects on macrophytes at much lower concentrations than reported previously, emphasizing the importance of studies applying environmentally relevant conditions. A chain of inhibition events could be established.