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Diel variations of selected elements in arsenic-rich stream at the Mokrsko
Nováková, Barbara ; Drahota, Petr (advisor) ; Skřivan, Petr (referee)
The filtration and ultrafiltration experiment was applied on the stream water at the Mokrsko gold deposit and the results revealed that most of the elements were in the dissolved form and the 0,45 or 0,1 m filters could be used. During two 24-h field experiments, water samples were collected at 1-h intervals in order to prove the diel changes in the concentration and speciation of several trace elements. The determination of sorption processes at the surface of or within the veneer of biofilm has been determined by collecting natural and artificial priphyton. The results showed regular diel changes of As, Sb and Mo with highest concentrations occurring after the moon and the lowest concentrations in the early morning. The dissolved concentrations of other elements are conservative or their values were closed to their detection limits. The diel cycles are caused by changes in adsorption/desorption equilibria induced by diel cycles of temperature. The samples of biofilm revealed increased concentrations of the elements under the study and their diel variation were significant (approximatelly 35-96%); however, biofilm-controlled diel cycles of dissolved concentrations have not been proved.
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Distribution of arsenic in the soil of gold mineralizations in Central Bohemian metallogenetic zone
Řeháček, Jan ; Drahota, Petr (advisor) ; Kindlová, Helena (referee)
Univerzita Karlova v Praze Přírodovědecká fakulta Ústav geochemie, mineralogie a nerostných zdrojů Obsahy arzenu v půdách zlatonosných ložisek středočeské metalogenetické zóny Bakalářská práce Jan Řeháček Vedoucí bakalářské práce: doc. Mgr. Petr Drahota, Ph.D. Praha, 2016 Summary This bachelor thesis reviews scientific publications regarding high concentrations of arsenic in soils of natural geochemical anomalies and former gold mines in the Central Bohemian Metallogenic Zone. High concentrations of arsenic in these areas originates primarily from sulfide minerals which are associated with gold mineralization. Arsenopyrite and pyrite are the most important primary As carriers in the bedrock. Due to natural weathering of sulfide minerals hosting rocks, release of arsenic and other potentially toxic elements into the surrounding environment takes place. This presents danger not only to soil fauna and flora but also to local inhabitants as contamination may also affect water sources in the area. At the beginning of this thesis some general aspects of the presence of arsenic in the environment are described, followed by chapters about the Central Bohemian Metallogenic Zone and its sites with anomalous concentration of arsenic in soil.
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Evaluation of sequential extraction for speciation of arsenic in mining wastes
Grösslová, Zuzana ; Drahota, Petr (advisor) ; Vaněk, Aleš (referee)
ii SUMMARY This master thesis deals with selectivity assessment of an arsenic sequential extraction procedure for evaluating mobility in mine wastes. A modified sequential extraction procedure was designed on the basis of preliminary tests of extraction efficiency and selectivity for the synthetic As mineral phases (scorodite, amorphous iron arsenate, schwertmannite, goethite, jarosite) and five natural samples (Kaňk, Dlouhá Ves, Giftkies, Roudný) that were previously characterized for As concentration and speciation. The modified sequential extraction has five steps. The first leaching step was performed in nitrogen-purged deionized H2O for 10 hours; next step involved 0.01M NH4H2PO4 leaching for 16 hours. Phases in the third step were dissolved with 0.2M Tamm`s reagent in darkness for 2 hours. The fourth step was represented by 0.2M of Tamm`s reagent heated in water bath at 80řC for 4 hours. Strong acid solutions HCl/KClO3/HNO3 were used to leach sulphide phases in the last step. The testing of the sequential extraction procedure using model mixtures showed a good discrimination of several fractions: adsorbed arsenic, arsenic associated with poorly crystalline oxyhydroxide, hydroxosulfate and arsenate phases (amorphous iron arsenate, schwertmannite, ferrihydrite), arsenic associated with crystalline...
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Anomalous occurences of arsenic in natural waters in the Czech Republic
Rodovská, Zuzana ; Drahota, Petr (advisor) ; Redlich, Aleš (referee)
This bachelor thesis reviews the data on the distribution of arsenic in surface and underground natural waters of the Czech Republic. In addition the thesis focuses on the occurrence of anomalous arsenic concentrations and tries to detect sources of arsenic contamination. Results of the thesis suggest high quality of the surface and groundwater in the Czech Republic with respect to arsenic. Its anomalous concentrations in the natural waters in Czech Republic have been rarely documented only in areas with strong anthropogenic impact and in areas affected by historical mining operations. Keywords: Arsenic, toxicity, contamination, surface water, groundwater, Czech Republic
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Indium in the environment
Kulakowski, Ondřej ; Drahota, Petr (advisor) ; Filippi, Michal (referee)
This bachelor thesis is focused on the presence, bonds and concentration of indium in various spheres of the environment. It presents a comprehensive overview of the distribution of indium in rocks, waters, air and organisms, its concentrations, speciation, mobility and refers to its toxicity. It also provides the basic physical and chemical properties of indium and its compounds, mineralogy and geochemistry. The major Czech and world deposits are reported. At the end it devotes significant world producers of indium, and also mentions recycling procedures of this element. Powered by TCPDF (www.tcpdf.org)
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Weathering of arsenopyrite in soils in acidified environment
Soukupová, Lenka ; Mihaljevič, Martin (advisor) ; Drahota, Petr (referee)
Lenka Soukupová, Zvětrávání arsenopyritu v lesních půdách v acidifikovaném prostředí SUMMARY The weathering of arsenopyrite (FeAsS) has been studied at the experimental site Načetín in the Ore Mountains, Czech Republic. There were chosen three areas with different vegetation (beech, spruce a unforested areas) at this site. The arsenopyrite samples were placed in all soil horizons (litter, horizons A, B and C for forest areas; horizons A, B and C for unforested area), where they were exposed to ambient conditions for one year. After one-year weathering, the newly formed secondary minerals were identified and the rate of surface oxidation was determined, both depending on the environment of oxidation. Although physical-chemical parameters and content of main and trace elements of the studied soils varied, the only detected crystalline secondary mineral of arsenic was scorodite (FeAsO4∙2H2O). Nevertheless, this differences affected amount of formed scorodite. The highest concentrations were determined on the surface of the arsenopyrite grains that oxidized in the beech stand, conversely the lowest concentrations were determined on the arsenopyrite grains from the unforested area.
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