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Manganese oxides from Zalas, Kraków area, southern Poland

Polak M., Gołębiowska B., Rzepa G.

Geology, Geophysics and Environment

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2016

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Vol. 42, no. 1

120--121

EN

The Zalas quarry is located in the southern, marginal part of the Silesian-Cracovian Monocline. Permian rhyodacite laccolith has been exploited here for over 70 years. The intrusion was formed about 260–280 Ma during the Early Permian transtensional, sinistral tectonic regime predominating in central Europe at that time (Nawrocki et al. 2005). Permian volcanic rocks are overlain by a Middle–Upper Jurassic sedimentary sequence, built from sands and sandstones, substituted with the passing of time by limestones and sandy limestones rich in fossils (Matyszkiewicz et al. 2006). Quarrying operations carried out approximately 10 years ago uncovered a fault zone cutting the Middle Jurassic sandy limestones. Exposed breccias was locally encrusted by a hydrothermal mineralization forming thin veinlets cutting the limestone, or surrounding the breccia clasts. Primary mineralization contained small relics of pyrite, chalcopyrite, chalcocite, galena, native bismuth and barite and was significantly replaced by supergene minerals e.g. Fe and Mn oxides, malachite, cuprite, Cu sulphates, iodargyrite, Bi oxychlorides and Na, K chlorides (Gołębiowska et al. 2006, 2010, 2015). The mineralization is most likely connected with rejuvenation of Early-Paleozoic fault zones during the Sava phase of the Alpine orogeny, and subsequent intensive weathering under semi-arid and arid climate in a period between the Oligocene and Middle Miocene (Gołębiowska et al. 2010). In the sandy limestone encrusted by the oxidized mineralization, very interesting Mn-oxides, enriched in numerous heavy metals were encountered. They filled small fractures and voids within the fault breccia. Among them, Tl-rich varieties have been recently reported. Extremely high thallium content, reaching 20.82 wt% Tl 2 O, makes the oxides unique on a world scale (Gołębiowska et al. 2015). In this paper we focused on the variable admixtures in Mn oxides from oxidation zone in Zalas; for this purpose, SEM-EDS and WDS analyses were carried out. Mn oxides in Zalas are accompanied by malachite, Fe oxides (goethite and hematite) and relics of primary mineralization (Matyszkiewicz et al. 2015). Mn and Fe oxides commonly form the yellowish to red-brownish or black tiny grains or cryptocrystalline aggregates with sizes up to a few millimetres across. Manganese oxides contain variable admixtures of Cu, Ca, Pb, Ba, Fe, Ni, Co and Tl. On the basis of chemical analyses, three major Mn oxide types have been distinguished: those enriched in (i) Ni and Co, (ii) Pb and (iii) Ba and Ca. Co-Ni-bearing Mn oxides, probably asbolane-type, contain 17.01–21.58 wt% CoO and 3.05–8.33 wt% NiO. These phases contain also admixtures of Cu (up to 10 wt% CuO) and Al (up to 7 wt% of Al 2 O 3 ), as well as traces of Fe, Ba, Zn, Mg and Tl (up to 0.5 wt%). Interestingly, in Mn oxides of this type, the admixtures of lead are absent. Pb-bearing Mn oxide, probably coronadite, contain up to 21.48 wt% PbO. In its composition various other elements were also noticed: up to 2 wt% CoO, 0.4 wt% NiO and very high concentrations of CuO up to 8 wt%, as well as up to 1 wt% BaO, FeO, CaO Tl 2 O, Al 2 O 3 and traces of Zn and Mg. Chemical mapping indicates that the Ba- or Ca-bearing Mn oxides occur only in marginal parts of zoned MnO 2 aggregates with almost pure MnO 2 in their cores. They contain 78–84 wt% MnO 2, 3–10 wt% BaO and 2.5–4.5 wt% CaO. High contents of Co, Ni, Pb, Cu and Tl in Mn oxides from Zalas indicate a direct link with the primary ore assemblage. High concentration of cobalt and nickel might suggest some connection with Co and Ni mineralization known from nearby Karniowice Travertine (Czerny 1992). Mineral association, as well as crystal morphologies and sizes could indicate hydrothermal origin of at least part of the Mn oxides. However, identification of the particular minerals as well as concluding on the details of their origin is quite difficult on this stage of research.

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Department of Mineralogy, Petrography and Geochemistry

Matusik J., Rzepa G.

Geology, Geophysics and Environment

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2016

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Vol. 42, no. 2

218--222

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Arsenic interactions with bog iron ores – As(III) and As(V) adsorption-desorption study

Tuchowska M., Bajda T., Rzepa G., Dębiec K., Drewniak Ł.

Geology, Geophysics and Environment

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2016

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Vol. 42, no. 1

133--134

EN

Arsenic is a toxic element, elevated concentration of which in the environment can result from both anthropogenic activity and natural geochemical processes. The contamination of water, especially groundwater, with As has been recognized as a major environmental problem (Choong et al. 2007). The mobility and toxicology of As is related to its valence state which can be (+III) or (+V), depending mainly on pH and redox conditions. Because even low As concentrations in drinking water causes severe health effects, the technologies of its effective removal are thought to be very important (Mohan & Pittman 2007). Among many methods developed for removing aqueous arsenic species, the adsorption onto iron oxyhydroxides or oxyhydroxide-rich sorbents is one of the most effective. Despite many studies, the factors affecting the adsorption processes, especially those related to the sorbent properties, are still far from being fully understood (e.g. Adra et al. 2016). In this work we investigated As(III) and As(V) adsorption and desorption by bog iron ores – natural ferruginous sediments which have been recently demonstrated to exhibit very good sorption properties. For this study four samples of bog iron ores, were collected at different sites in the Polish Lowlands: Kolechowice (KOL), Biadaszki (BD), Strzyżew (ST) and Dębe Małe (DM). They represent different bog iron ore types which, in spite of having diversified structures, mineral composition and, subsequently, physical and chemical properties, revealed good sorption affinities for trace elements in previous work (Rzepa et al. 2009). In batch experiments the influence of various factors on adsorption were studied, including initial As concentrations, initial pH values and competitive adsorption of As(III) and As(V). The effect of initial As concentrations was studied in the range of 0.01–20 mM As(III) or As(V) at pH 7.5. The influence of pH was evaluated by the adsorption of 5 mM As solution in the pH range of 2–12. The experiment of competitive adsorption of arsenite and arsenate was performed for various proportion of As(III) to As(V) in the range of initial concentrations 0.025–20 mM at pH 7.5. The bonding strength of As with bog iron ore surface was estimated on the basis of three-step desorption experiments, which were conducted for the samples previously treated with As(III) or As(V) at pH 7.5 and at constant 20 mM initial concentration of arsenic. Arsenic concentrations in filtered (filter with a 0.22 μm pore size) solutions after all the experiments were analyzed using AAS and UV-Vis spectrophotometry. The results showed that arsenic sorption depends on its oxidation state. All the bog iron ores bound more As(III) than As(V). The highest amount of As(III) was sorbed by ST sample (458 mmol/kg), lower by KOL (430 mmol/kg) and DM (427 mmol/kg), and the lowest by BD (333 mmol/kg). However, in the case of As(V), the order was different: the highest amount of As was sorbed by BD sample (264 mmol/kg), lower by ST (218 mmol/kg), and the lowest by DM (163 mmol/kg) and KOL (158 mmol/kg). The highest uptake (80–95%) of As(III) was noted at lower initial concentrations, while the highest uptake (60–70%) of As(V) was observed at higher initial concentrations. As(III) sorption effectiveness was >80% throughout the pH range of 4 to 9 and was almost independent on pH in that range. In contrast, the As(V) sorption was higher at slightly acidic pH and significantly decreased in alkaline conditions. At pH around 3, sorption efficiency of both As(III) and As(V) decreased, which is likely due to the increased solubility of iron oxyhydroxides (Zeng, 2004). The results of competitive sorption experiments revealed that at low concentrations of both As species reduction of sorption efficiency of As(III) occurred. Sorption of As(V) was also affected, but only if amount of As(III) was higher than As(V). On the contrary, at high As(V) and As(III) concentrations, As(V) did not influence As(III) sorption, but As(III) substantially increased sorption of As(V). Desorption of arsenic by foreign ligands resulted in extraction of more than 70% of absorbed As(III) and As(V). In the absence of the exchange ligand, i.e., in deionized water, desorption of As(V) and As(III) was considerably lower, but noticeable. This study shows that bog iron ores are very good arsenic sorbents. However, the extent of As removal seems to be affected by various factors including As species and the composition of the ores themselves. As(V) is immobilized less effectively than As(III), and the process is influenced by pH values. It is believed, that the uptake of As by bog ores is controlled primarily by iron oxyhydroxides, as main components of these rocks, but mechanisms predominant in As(III) and As(V) adsorption are different and affected by presence of e.g. phosphate and silicate ions (Ociński et al. 2011). There are no simple correlations between mineralogy and sorption capacity. Due to the variability in chemical and mineral composition of different types of bog iron ores, various levels of arsenic removal can be obtained. Such properties of the ores, combined with their ubiquity in many near-surface environments may be regarded as an incentive for the environmental protection practice.

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Weathering in a regolith on the Werenskioldbreen forefield (SW Spitsbergen) : modelling of pore water chemistry

Kwaśniak-Kominek M., Manecki M., Rzepa G., Płonka A. M., Górniak D.

Annales Societatis Geologorum Poloniae

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2016

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Vol. 86, No. 3

249--264

EN

The mineral framework and pore waters of glacial sediments exposed in the foreland of Weren- skioldbreen in SW Spitsbergen were sampled and analyzed to model the evolution of pore water chemistry, representing the advancement of weathering in a chronosequence. Three samples were taken at distances representing snapshots of approximately 5, 45 and 70 years of exposure. Complementary mineralogical analyses of the mineral framework and chemical analyses of pore waters, coupled with thermodynamic modelling of mineral-water interactions were applied. Recently uncovered sediments of the bottom moraine underwent very little weathering underneath the glacier cover; both the sediments and pore waters in the forefield of the Werenskioldbreen represent a very immature system. Poorly sorted sediments were deposited by the glacier and not reworked by fluvioglacial waters. The ratio of ‘amorphous iron’ to ‘free iron’ Feo/Fed increases with distance from the glacier terminus from 0.30 through 0.36 to 0.49, typical for fresh glacial till. The increase in saturation with CO2 (from p(CO2) –3.8 to –2.4) and the concentration of all major ions in pore waters (from 123 to 748 mg/L total dissolved solids, TDS) was observed in this young chronosequence. The waters evolved from carbonate- dominated to sulphate-dominated, indicating that with progress in weathering the dominating processes are equilibration with carbonates, oxidation of sulphides and the influence of gypsum precipitation by seasonal freeze-thaw cycles. Mass balance calculations and inverse modelling of the composition of pore waters, verified by microscopic observations of alteration on the surfaces of mineral grains, allowed thermodynamic confirmation of the fact that the relative significance of carbonate weathering decreases and that of sulphate increases down the chronosequence. The participation of silicate minerals in weathering is low, indicating a relatively immature stage of weathering within this particular chronosequence. It is significant that the morphology of etch pits and the formation of secondary phases apparent on mineral surfaces were identical, regardless of the distance from the glacier terminus. This might indicate that the mechanisms of particular weathering processes at the mineral-water interface are the same at the initial as well as at the more mature stages and do not change at least within ca. 70 years of exposure.

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Wpływ metody syntezy na właściwości fizykochemiczne ferrihydrytu i Si-ferrihydrytu

Pieczara G., Mendsaikhan N., Manecki M., Rzepa G.

Przemysł Chemiczny

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2015

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T. 94, nr 10

1828-1831

PL

Przeprowadzono syntezę ferrihydrytów (Fe5HO8·4H2O) czystych (bez domieszki Si) i zawierających domieszki Si (stosunek molowy Si:Fe = 0,1) przez wytrącanie z roztworów wodnych. Porównano produkty otrzymane w reakcji zobojętniania roztworów siarczanu żelaza(III) (metoda siarczanowa) lub azotanu żelaza(III) (metoda azotanowa). Wykazano, że czyste ferrihydryty otrzymane metodą azotanową charakteryzują się mniejszymi rozmiarami cząstek, większą powierzchnią właściwą, mniejszym stopniem uporządkowania struktury oraz mniejszą trwałością termiczną. Sposób syntezy ma mniejszy wpływ na różnice we właściwościach ferrihydrytów z domieszką Si.

EN

Pure Fe5HO8·4H2O and Si-doped ferrihydrites (Si/Fe = 0.1 molar ratio) were pptd. from aq. solns. of Fe2 (SO4)3 and Fe(NO3)3 with NaOH optionally in presence of Na2SiO3 under stirring. Si-contg. ferrihydrites had smaller particles and showed higher thermal stability and sp. surface area than the pure ones.

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“Four-letters” (γ → ε → β → α) thermal transformation of Si-rich ferrihydrite

Pieczara G., Rzepa G., Gaweł A., Tomczyk A.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 1

121--122

EN

Ferrihydrite is a poorly ordered iron (oxyhydr)oxide, ubiquitous in near-surface environments, where it is an important scavenger of numerous toxic metals and metalloids (Cornell & Schwertmann 2003). Being metastable, ferrihydrite transforms with time into stable phases, usually goethite and/or hematite. The latter is also a final product of ferrihydrite thermal conversion via both, hydrothermal and dry-heating pathways. The transformation course is affected by many factors and for this reason its details are still under debate. Pure ferrihydrite practically does not exist in nature. The admixtures present in its composition affect many properties of the oxyhydroxide, including surface chemistry, sorption effectiveness, crystallinity, magnetic ordering and solubility. Silicate, probably the most important natural impurity, was shown to hamper thermal transformation of ferrihydrite. The process was studied in detail only for relatively low-Si samples (Campbell et al. 2002). In some environments, such as modern seafloor hydrothermal vents, higher Si/Fe proportion have been found (Sun et al. 2013). The objective of this work was to determine if (and if so, how) the high silicate content in ferrihydrite modifies its thermal transformation. Ferrihydrite samples of high Si/Fe molar ratios (0.50, 0.75, 1.00, and 1.50) were obtained by reaction of Fe2(SO4)3 with NaOH in the presence of Na2SiO3 at pH 8.2 (Vempati & Loeppert 1989). The products were characterized using X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM). Simultaneous thermal analyses, including differential thermal analysis (DTA), thermogravimetry (TG) and quadrupole mass spectrometry of evolved gases (QMS) were also performed. All of the ferrihydrites were heated from 30°C • min−1to 1000°C • min−1, at 10°C • min−1in flowing air, using preheated sample as an inert material. The samples were also heated to various temperatures, chosen on the basis of the analysis of their thermal patterns. The heating was stopped immediately when reaching the desired temperature. The sample was removed, rapidly cooled in air and characterized again by XRD, FTIR and SEM. The thermal patterns revealed that the presence of Si in ferrihydrite hampers its conversion to hematite, which is reflected by shifting of the hematite crystallization exotherm to temperature as high as ca. 920°C, in comparison to 350–460°C when Si-free ferrihydrite is annealed (Pieczara et al. 2014). XRD patterns and FTIR spectra of the samples heated to 1000°C show the presence of hematite and cristobalite. It was observed that the higher molar Si-to-Fe ratio in initial mineral results in the higher cristobalite concentration in the product. SEM observation showed that hematite crystallites, embedded in cryptocrystalline silica, are distinctly smaller than those produced from pure ferrihydrite. They also exhibit wider range of crystal habits – isometric grains, plates, rods and even needles were encountered. Elongated crystallites (rods and needles) appear to be more common in the highest-Si products. Moreover, whilst during transformation of pure ferrihydrite into hematite no distinct intermediate phase is formed, the conversion of high-Si ferrihydrite proceeds by much more complex pathway. After low-temperature dehydration, the material still exhibits two-peak ferrihydrite-like XRD pattern, but a gradual amorphisation is observed up to ca. 600°C. Then, at 650°C amorphous silica emerges which is followed by the formation of nanocrystalline maghemite (γ-Fe2O3) between 700°C and 800°C. Subsequently, maghemite is transformed to orthorhombic ε-Fe2O3phase at 800–850°C. In the samples of 0.50, 0.75 and 1.0 Si/Fe ratios, further increase of temperature results in ε-Fe2O3conversion to hematite and crystallization of cristobalite-like phase. However, XRD patterns of annealed the highest-Si sample (Si/Fe = 1.5) show also the presence of β-Fe2O3between 907°C and 930°C. At 907°C hematite appears and ε-Fe2O3 vanishes by 930°C, so at the latter temperature two Fe2O3 polymorphs (α and β) are present. At 1000°C hematite is the sole iron oxide in all the products. Thus siliceous ferrihydrites transform into hematite via γ–ε or γ–ε–β pathway, depending on the Si/Fe ratio. Formation of rare epsilon and beta iron oxide polymorphs from high-Si ferrihydrites can be explained by emerging of amorphous SiO2during annealing, which subsequently acts as antisintering agent stabilizing maghemite precursor against its direct thermal conversion to hematite. Our results show that high silicate content causes not only the retarding of ferrihydrite conversion to hematite but also affects crystallinity of the product and complicates the transformation pathway. In the authors’ opinion the formation of rare epsilon and beta Fe2O3 is noteworthy for at least two reasons. Firstly, β- and, especially, ε-Fe2O3have been recently found to exhibit many interesting physical properties, which make them attractive nanomaterials for use in a wide range of applications (Machala et al. 2011). Annealing of Si-ferrihydrites might offer an alternative method of obtaining these oxides. Secondly, both these oxides have not been found in nature yet. This work suggests that their formation is possible in places where siliceous ferrihydrites or other Si-Fe amorphous sediments have been heated to high temperature, as in e.g. hydrothermal systems of mid-ocean ridges.

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Epigenetic silicification of the Upper Oxfordian limestones in the Sokole Hills (Kraków-Częstochowa Upland): relationship to facies development and tectonics

Matyszkiewicz J., Kochman A., Rzepa G., Gołębiowska B., Krajewski M., Gaidzik K., Żaba J.

Acta Geologica Polonica

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2015

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Vol. 65, no. 2

181--203

EN

A spectacular epigenetic silicification was encountered in the Oxfordian bedded limestones exposed in the Sokole Hills situated in the Kraków-Częstochowa Upland. The main epigenetic mineral is microcrystalline quartz accompanied by minor goethite, hematite, barite, galena and sphalerite. Locally, the mineralized limestones reveal Pb and Cu contents exceeding over 150 times the background values of these metals in unmineralized limestones. The epigenetic mineralization of the bedded limestones was probably a two-stage process. During the first, Early Cretaceous stage, silicified limestones formed at the erosional surface of a denuded carbonate complex. Such silicification greatly limited the progress of the first karstification phase of the Upper Jurassic carbonates initiated in the Hauterivian. The sources of silica accumulated in the limestones were descending solutions enriched in silica derived from the weathering zone. This silicification affected the topmost part of the Upper Jurassic massive limestones and the deeper portions of the bedded limestones along the fracture systems and stylolites. Early Cretaceous tectonic activity generated new dislocations and re-opened the existing faults, which were subsequently filled with permeable Albian quartz sands. These openings became the migration pathways for ascending, warm, relict, sulphide-carrying hydrothermal solutions at the second formation stage of the epigenetic mineralization. The newly supplied silica from the Albian sands precipitated on the silicified limestones and, as concentric rims, on brecciated, early diagenetic cherts. The second-stage mineralization proceeded under phreatic conditions, presumably close to a fluctuating mixing zone of ascending, warm hydrothermal solutions and descending cold groundwaters. The brecciated cherts acting as silica crystallization nuclei indicate that the last mineralization stage probably followed the final phase of Cenozoic faulting.

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Weathering of siderite in the polar conditions

Figura P., Manecki M., Rzepa G.

Geology, Geophysics and Environment

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2014

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Vol. 40, no. 1

84--85

EN

Rapid retreat and thinning of glaciers perturb balance of polar ecosystems. These processes influence global climate (Anderson et al. 2000, Płonka 2009). For better understanding of changes and their consequences for global climate, it is necessary to extend our knowledge about processes occurring contemporary in the forelands of retreating glaciers. Numerous researches were carried out on this subject (Anderson et al. 1997, Bukowska-Jania et al. 2003, Pulina et al. 2003). For example, upliftdriven climate change hypothesis assumes that decrease of temperature results from regression of glaciers and is connected with chemical denudation of silicate sediments, which acts as a sink of CO2 from the atmosphere (Płonka 2009). Despite of this, many processes and dependences in polar environment are poorly known. Retreating glaciers and high chemical denudation observed in Polar Regions play significant role in weathering of regolith. Fast retreat of many glaciers exposures great amounts of fresh and fine sediment. Weathering of rock-forming minerals is a source of ions in waters as well as secondary minerals and nutrients in initial soils. These issues are object of interest recently because intensified weathering in Polar Regions may affect global cycle of many elements, particularly Fe (Anderson et al. 1997, 2000, Brenasconi 2008). This study is a part of large research, concerning mechanisms, budget and transport of iron from the foreland of fast retreating arctic glacier. The objective of this research is to determine processes and products of siderite weathering in the polar condition. The area of this study is located on the SW part of the Spitsbergen, in the foreland of Werenskioldbreen. It is hypothesized that in Arctic these processes differ significantly from their equivalents in Alpine regions. Field experiment on Spitsbergen lasted eight years. Samples of the siderite were buried in the surface layer of bottom moraine (in the initial polar soils) 100 m, 250 m and 2000 m from glacier front. This represents a chronosequence of sediment uncovered from underneath the glacier ca. 5-, 10-, and 90-years ago. Samples were recovered after 1 year and after 8 years of burial. Optical microscopy in transmitted and reflected light, scanning electron microscopy SEM/EDS and powder X-ray diffractometry were applied to characterize both, control sample and experimental samples. Siderite with manganese substitutions sampled from the outcrops of metamorphic carbonate in the vicinity of Werenskiold glacier was used for the experiment. This resembles mineral fragments eroded and transported by the glacier. Characterization of control sample (siderite before the experiment) indicates that it already exhibits advanced stages of transformation into secondary phases. Secondary minerals include oxides and hydroxides of iron, such as: goethite, hematite and lepidocrocite. The same mineral phases were identified in experimental recovered after burial. Additionally, 8-year sample shows traces of dissolution. Weathering of siderite in polar initial soils in the foreland of retreating glacier leads to formation of secondary goethite, hematite and lepidocrocite. These phases appear to be the most stable products of siderite weathering in this environment. There is no difference between the samples buried in very young and in older, more evolved initial soil. Additionally, transformations of siderite are identical in initial polar soils and in the outcrops of siderite rock. Traces of dissolution noticed on the surface of older samples indicate that part of iron is permanently removed from the system by solutions. This process, probably mediated by microorganisms, requires further investigation.

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The influence of silicate content on thermal stability of 2-line ferrihydrite and properties of its transformation products

Pieczara G., Rzepa G., Gaweł A.

Geology, Geophysics and Environment

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2014

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Vol. 40, no. 1

160--161

EN

Naturally occurring ferrihydrite (Fe5HO8 • 4H2O) is a poorly ordered iron (oxyhydr)oxide mineral, with non-stoichiometric composition and not fully understood structure. Because of its unique chemical and physical properties, such as low crystallinity, high surface area and surface reactivity, ferrihydrite plays significant role in e.g. inorganic weathering processes, biochemical cycling of iron and as a sorbent in various near-surface environments. Ferrihydrite is a metastable phase and transforms with time into stable oxides: goethite and/or hematite, through dissolution-reprecipitation and dehydration-rearrangement mechanisms, respectively. Ferrihydrite structure provides numerous sorption sites and for this reason substantial amounts of admixtures are present in its chemical composition. The most common and well documented impurities include silicate, phosphate, arsenate, sulphate, calcium, aluminum and organic compounds. These ions affect ferrihydrite composition, surface molecular structure and sorption properties. Silicate, probably the most important impurity, causes decreasing crystallinity of this nanomineral, modifies magnetic ordering and solubility. Thus, natural ferrihydrite distinctly differ from synthetic pure analogue. As it was previously shown, the association of Si with ferrihydrite surface hindered thermal transformation to hematite. The implications of this observation for the understanding of Si-ferrihydrite stability in geochemical systems are obvious. The aim of this work was determining of the influence of the Si/Fe ratio in ferrihydrites on its thermal transformation processes and the properties of the products. Ferrihydrite samples having different Si/Fe molar ratios: 0.00, 0.05, 0.10, 0.20, 0.25, 0.50, 0.75, 1.00, and 1.50, were obtained by reaction of Fe2(SO4)3 with NaOH in the presence of Na2Si03 at pH 8.2. After four-day incubation, dialysis and freeze-drying, the precipitates were characterized using X-ray powder diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Raman spectroscopy, and scanning electron microscopy (SEM). Then thermal analyses (DTA/DTG/TG) were performed. All of the ferrihydrites were heated from 30°C to 1000°C, at 10°C min-1 in flowing air, using hematite as inert material. After heating all the samples were again characterized by XRD and SEM-EDS methods. DTA curve of pure ferrihydrite shows typical dehydration endotherm at 160°C and. sharp exotherm at 350°C, attributed to hematite formation. Additional weak peaks at 550°C and 710°C were probably originated form decomposition of relic sulphate. The presence of Si in ferrihydrite appears to stabilize its structure and prevents conversion to hematite: the ferrihydrite-hematite transformation peak weakens and broadens and is shifted towards higher temperatures, up to ca. 900°C for high-Si materials. However, no simple linear relationship between silica content in ferrihydrite and the position of this peak has been found. X-ray diffraction patterns indicate that the main product of thermal transformation of all ferrihydrites is hematite (α-Fe2O3). For low-Si samples (Si/Fe < 0.20), a gradual broadening of 104, 214, 300, 110 hematite reflexes has been noticed, indicating the decrease of its crystallinity. On the other hand, for high-Si materials the broadening appears to be less distinct. Increasing Si/Fe molar ratio (≥ 0.10) in the initial material took an effect also in the appearance of a cristobalite-type oxide, the content of which increases drastically for the highest-Si samples. Additionally, the XRD pattern of the Si/Fe 0.10 sample reveals the presence of some spinel phase. Hematite originating from the heating of Si-free ferrihydrite forms quite large (up to 1 mm in size) isometric and prismatic crystals, often exhibiting pseudohexagonal shape. In contrast, the oxide particles become tenfold smaller even in the lowest-silicate material (Si/Fe = 0.05) and reveal pseudospheric morphology. In higher-silicate products (Si/Fe > 0.10) the crystallites are getting elongated and the elongation increases with increasing Si/Fe ratio. This preliminary study demonstrates that silicate content causes the retarding of ferrihydrite (thermal) transformation to hematite and affecting crystallinity of the latter. Even small Si admixture in the precursor reduces crystal size of the product. During roasting of low-Si ferrihydrites some Si probably enter the hematite structure, but higher-Si hematites cannot form and for this reason heating of high-Si ferrihydrites produces two-phase composition.

10

Sub-sea tailings deposition leach modeling

Rzepka P., Walder I.F., Aagaard P., Bożęcki P., Rzepa G.

Geology, Geophysics and Environment

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2014

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Vol. 40, no. 1

123--124

EN

Submarine deep-sea tailings deposition is an alternative method of the land-based mine-waste disposal, whereby mineral ore is converted into slurry and transported via a pipeline to processing plants located at the coast. The tailings are then discharged into very deep water offshore where they usually cover large parts of the sea bottom. This type of deposition is applied only in few countries: Norway, Papua New Guinea, Philippines, Chile and Turkey. It is, however, a controversial method of mine tailings disposal primarily due to the hazardous chemicals used during processing and deposited metal sulfides which may dissolve and affects the sea environment. The overall objective of this project is to evaluate the copper leaching potential from tailings on the example of the proposed submarine tailings disposal in Repparfjorden discharged from two hydrothermal copper vein type deposits - Nussir and Ulveryggen, exploited by Nussir ASA. The two deposits are 5 km apart and will be processed by the same processing plant. This experiment gives better understanding of the reactivity of sulfide minerals in a saline system during submarine deposition. Planned by Nussir ASA, processing the ore by a flotation system will produce two types of flotation tailings material. These two tailings streams will be mixed with the flotation water, possibly aided by a flocculent, which will be extracted in a thickener afterwards. Seawater will then be added to the material prior to being discharged via a pipeline into the fjord that is at least 90 meters deep. Four kinetic test set-ups containing 0.5 kg of material and 2 L of seawater were prepared for an experiment that runs for 100 days, by recirculation of the leachate (batch experiments). Seawater was routed through pipes at a constant flow rate of 1-2 m/h via a peristaltic pump which arose from about 4 L/h water exchange rate in the column. The columns were run at a temperature of approximately 10°C. The seawater leachate was saturated by oxygen up to 80-100% in order to maintain condition providing sulfide oxidation leaching. Nine leachate samples were collected from each column for analysis of dissolved constituents and physical parameters. Results show that there was a distinct increase in copper concentration while other hazardous elements did not show significant changes. Copper concentrations reached 0.025 mg/L after 100 days. Towards the end of experiments (from 70-100 days), the leaching rate leveled off with time. Subsequent Cu concentrations indicated that there no more copper was released. Reaction was halted likely because sulfide particles have been consumed or encapsulated by iron hydroxides. The leaching reaction rate observed in this test resulted in a much lower copper contamination than previous estimates (Akvaplan-NIVA, 2011). Following the experiment results the estimated reaction rate is approximately 12.7 mg/m2/year, what involves approximately 5.75 kg/year of Cu release for proposed 2.4 km2 of tailings deposition area or approx. 9.75 kg/year in 4.0 km2 after a year from disposal closure. This is significantly less than the annual copper discharge from a river naturally leaching deposits (500-600 kg/year). It was assumed that the copper is being leached only from the surface of the tailings deposit. This is primarily due the saturated condition of the sediments which prohibits oxygen supply through the deposit. Therefore available oxygen is quickly used up, thereby halting sulfide oxidation (Walder & Rzepka 2013). This research revealed that copper leaching is a two-stage process: (1) initial rapid dissolution of secondary Cu minerals formed from previous sulfide oxidation, related to the tailings material disposing period, and (2) long term slow surface-based leaching of sulfide from tailings material settled on the bottom.

11

Results of microbiological research in the polish part of the Muskau Arch - the largest AMD environment in Poland - final report

Bożęcki P., Rzepa G., Ratajczak T.

Civil and Environmental Engineering Reports

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2014

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No. 12

17--26

EN

This work presents the results of microbiological investigations carried out in the Polish part of the Muskau Arch. In this abandoned lignite mining area highly acidified Fe-rich waters have been formed as a result of sulphide oxidation. Microbiological tests have shown that all studied groups of microorganisms exhibit both time and spatial variability. The most common group of microorganisms are bacteria Galionella sp.

PL

W rejonie Łuku Mużakowa prowadzona była eksploatacja m.in. węgla brunatnego. Działalność kopalń w tym rejonie trwała do końca lat 70. XX wieku. Po zakończeniu eksploatacji w obniżeniach terenu powstały liczne zbiorniki wodne, tworzące tzw. pojezierze antropogeniczne. W wyniku utleniania siarczków (głównie pirytu) występujące tutaj wody są bogate w żelazo oraz charakteryzują się bardzo niskim pH. W pracy przedstawiono wyniki badań mikrobiologicznych wykonywanych w polskiej części tej struktury geologicznej. Stwierdzono, że wszystkie badane grupy mikroorganizmów wykazują zmienność zarówno czasową (wynikającą z pór roku) jak i przestrzenną (wynikającą z miejsca pobrania próbki do badań). Wykazano, iż najliczniejszą grupą mikroorganizmów są nitkowate bakterie z rodzaju Gallionella. Stosunkowo liczne są ponadto bakterie Acidithiobacillus ferrooxidans. Ponieważ obie te grupy mikroorganizmów do swojego wzrostu potrzebują tych samych związków chemicznych ich populacje konkurują ze sobą – nawet kosztem ograniczenia tempa rozwoju populacji własnego gatunku.

12

Możliwości wykorzystania niektórych metod geofizycznych w poszukiwaniach i dokumentowaniu czwartorzędowych nagromadzeń rud żelaza

Gołębiowski T., Ratajczak T., Rzepa G., Sala D.

Górnictwo Odkrywkowe

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2013

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R. 54, nr 2

95--98

PL

W artykule przedstawiono czwartorzędowe nagromadzenia żelaza – rudy darniowe i ochry. Charakteryzują się one skomplikowanym sposobem zalegania, co utrudnia ustalenie granic ich nagromadzeń, powierzchni i zasobów. W celu rozwiązania tych zagadnień określono możliwości wykorzystania metod geofizycznych – magnetycznych i georadarowych, których głównymi zaletami są nieinwazyjność oraz krótki czas uzyskania informacji przestrzennej dla okonturowania nagromadzeń rud żelaza. Było to również możliwe z uwagi na specyficzne cechy mineralno-chemiczne oraz fizykochemiczne tych kopalin, a także znaczne zawartości żelaza w analizowanych próbkach.

EN

The paper presents Quaternary bog iron ores and ochre deposits. They are characterized by a complicated layers position, which makes it difficult to determine the boundary of accumulation, surface and resources. Solving these problems was possible using of selected geophysical methods - magnetic and GPR measurements. The main advantage of these techniques is non-invasive methods and short time needed for gathering of spatial information for outlining accumulations of iron ores. It was also possible due to the specific mineralogical, chemical and physicochemical properties of these deposits and large iron content in the analyzed samples.

13

Możliwości wykorzystania kopalin towarzyszących z wybranych złóż surowców skalnych Polski jako komponentów do budowy przesłon hydroizolacyjnych

Bożęcki P., Rzepa G.

Górnictwo Odkrywkowe

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2012

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R. 53, nr 1-2

104-108

PL

W artykule przedstawione zostały wyniki badań dotyczące możliwości wykorzystania kopalin towarzyszących z wybranych złóż na terenie województw małopolskiego, dolnośląskiego, podkarpackiego, śląskiego oraz świętokrzyskiego. W sumie przebadanych zostało 18 próbek glin pochodzących z 12. złóż. Wyniki przeprowadzonych badań pokazują iż żadna z przebadanych próbek nie spełnia wszystkich wymagań stawianych komponentom do budowy przesłon hydroizolacyjnych, dlatego też nie mogą być one wykorzystane do tego celu. W większości przypadków wynika to z niekorzystnego uziarnienia i/lub składu chemicznego, zwykle niewłaściwa jest również kolejność kationów wymiennych.

EN

The paper presents the results of studies on the possibility of use of the accompanying minerals from selected deposits in the Małopolskie, Śląskie, Podkarpackie, Dolnośląskie and Świętokrzyskie provinces. In total, 18 samples were tested from 12 clay deposits in Poland. Results of this study show that none of tested samples did not meet all the requirements for components of hydro-isołation layer, and therefore cannot be used for this purpose. In most cases this is due to unfavorablegrain size and/or chemical composition, usually it is also wrong order of cation exchange.

14

The using possibility of clay-rich overburden rocks from selected Polish deposits

Bożęcki P., Rzepa G.

Geology, Geophysics and Environment

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2012

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Vol. 38, no. 4

457

EN

The objective of this work was an assessment of the possibility of utilization of selected clay-rich overburden rocks from selected rock raw material found in Polish deposits. For this purpose samples from 12 deposits in five different provinces of southern Poland (Małopolskie, Śląskie, Podkarpackie, Dolnośląskie and Świętokrzyskie) have been collected. Exploited mineral deposits from which samples have been taken belong to wide range of materials. They are for example dolomite (Rędziny), magnesite (Braszowice), limestone (Czatkowice and Morawica), rhyodacites (Zalas), clay materials for construction of ceramics (Harasiuki, Wala Rzedzińska, Kraniec, Wręczyca) and mineral aggregates like sand (Bielany at Sole and Wola Batorska). Main field of feasibility of using samples were components of waterproofing layers. Part of the samples was also tested for the possibility of their use in land reclamation. Mineral and chemical composition of the samples was analysed, using XRD and ICP-OAS methods, respectively. Grain size distribution was performed by using sieve analysis and by a laser particle size analyser. Exchangeable cations and cation exchange capacity were also estimated based on the concentration of displaced ions (such as Ba +, Fe +, Sr +, Al +, Mg +, Ca +, Na+, K+, Li+) by ammonium cation (from the 1 M ammonium acetate solution) and indicated cations. Results of this study show that none of the tested samples met all the requirements for components of hydro-isolation layer, and therefore they cannot be used for this purpose. In most cases this is an effect of unfavourable mineral composition (to high percentage of non-clay minerals) and/or chemical composition. Usually the amount of examined exchangeable cations was also incorrect. The applicability results for land reclamation showed a very large variation. Part of the samples has acquired the highest A class. However, some samples were also found to be characterized by the worst D class of reclamation utility.

15

The results of multistage liming and lacustrine chalk application in AMD water reservoir in the Muskau Arch near Łęknica, W Poland

Rzepka P., Bożęcki P., Manecki M., Rzepa G., Bajda T.

Geology, Geophysics and Environment

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2012

|

Vol. 38, no. 4

527--528

EN

The Muskau Arc is a 40 km long moraine belt bent into a horseshoe-like shape pushed by the Mid Polish Glaciation, located in west Poland. Pyrite-bearing Neogene lignite deposits were mined there until the 1980s. The abandoned open pits filled with groundwater are forming a set of reservoirs called "Anthropogenic Lake District". It consists of more than 100 reservoirs on the total area of more than 1500 square kilometers. Oxidation process of iron sulfide-containing lignite left in mining pits or deposited in dumps, exposed to atmospheric oxygen and water results in formation of acidic waters and precipitation of ochreous sediments. The water is characterized by high Fe and SO42- content. This chemical association with low pH waters is causing the main environmental waste problem in this region, which is typical for most Acid Mine Drainage (AMD) areas. The main goal of conducted experiment has been to examine the abilities of acid mine water remediation on the example of Muskau Arch lake named Africa. The chemical neutralization of acidic pH and removal of high salinity by precipitation was made by various substances application. The objective of this study was comparison of the potential effects of this treatments applied in several steps. Africa is one of the largest and deepest reservoirs of Muskau Arch. This meromictic lake has constant vertical stratification characterized by diversity of physicochemical parameters and content of major ions. Water contained in the mixolimnion at the top (down to about 10 m depth from surface) is well mixed by air currents and saturated with oxygen. It has lower pH (pH — 2.75) and lower ion concentrations (the average TDS amounts to 2000 mg/L) than the bottom layer. Monimolimnion in the bottom part (below 10 m from the surface) is anoxic, poor in oxygen, with higher pH (pH — 4.75) and salinity (TDS up to 6000 mg/L). Water in both layers is not mixing due to significant density difference preserving the geochemical stratification. In the set of laboratory experiments samples of waters from both layers were mixed with different doses of lime and lacustrine chalk. The application was carried out over half a year in several steps, because of the ability of this water to acidify itself. In all cases, especially in second stage, the treatments lead to rapid increase of pH and to precipitation of different secondary phases, mostly gypsum and iron hydroxides (ferrihydride, goethite and rare green rust). This results in removal of ferric and ferrous ions and reduction of sulfates content by close to 80%. However effects was varying and depends on kind of treatment, layers, which have different acid neutralizing capacity, and step of dosing. pH of upper layer is lifted to about neutral value (7-8) by chalk dosing or slightly basic (9) in the case of liming. These treatments are successful already in first step application. Hydrogen ion releasing in iron hydroxides precipitation process in bottom layer, due to occurring specific pH-Eh conditions, restrains neutralization effectiveness. Therefore next application steps are necessary to reach neutral pH (6-7) after chalk treatment or even alkaline (11-12) by liming.

16

Synthesis and preliminary characterization of 2-line ferrihydrite containing different amounts of Si

Pieczara G., Rzepa G.

Geology, Geophysics and Environment

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2012

|

Vol. 38, no. 4

517--518

EN

Ferrihydrite (Fe5HO8 • 4H2O) is the reddish-brown, nearly amorphous hydrous ferric oxyhydroxide mineral with variable composition, widespread in various near-surface environments. Being thermodynamically unstable, it transforms with time into goethite (a-FeOOH) or hematite (a-Fe2O3). Due to its low crystallinity and high surface area, ferrihydrite is highly reactive and plays, through coprecipitation and adsorption reactions, an essential role in e.g. geochemical cycling of various trace elements and capturing of contaminants from streams and groundwater in such environments as ironladen springs, mine wastes and acid mine drainage. The environmental importance is one of the main reasons for numerous studies on ferrihydrite properties which have been carried out recently. These studies have been dealing with, among others, solubility, thermodynamic features, surface chemistry, sorption and catalytic properties etc. However, in the majority of experimental works synthetic ferrihydrite analogues with chemical composition close to ideal have been applied. Such approach might cause oversimplification, because ferrihydrite always contain substantial amounts of admixtures, with Si, C, P, As, Ca, Al being probably most common. One of the most important and the most common impurity is Si, which in the form of silicate ion has strong affinity for a hydrous ferric oxyhydroxide surface. An association of ferrihydrite with Si not only retards the rate of its transformation to the stable phases (goethite or hematite), but also seriously affects e.g. surface chemistry. Although Si-ferrihydrite was successfully synthesized in several studies, relatively little is known about its properties. The aim of this work was to fill that gap. Ferrihydrite samples having different Si/Fe molar ratios: 0.00, 0.05, 0.10, 0.20, 0.25, 0.50, 0.75, 1.00, and 1.50, were obtained by reaction of Fe2(SO4)3 with NaOH in the presence of Na2Si03 at pH 8.2. The precipitates were incubated for four days at room temperature, then the suspensions were dialyzed to remove an excess of salt, and finally freezedried. The products were characterized using a variety of analytical techniques, including X-ray powder diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and Raman spectroscopy. The X-ray pattern of pure ferrihydrite reveals two asymmetric broad bands with maxima at 2.55 A and 1.50 A, characteristic for 2-line ferrihydrite. With increasing Si/Fe molar ratio, shifting in position of the first (ca. 35°20) peak towards lower angles (up to ca. 29°20) was observed. Gradual broadening of the peak and declining its asymmetry were noticed as well. Both the position and the shape of the second band did not shift at the same time. These features indicate reducing crystallinity and lowering grain size of Si-ferrihydrite in comparison to those for the pure ferrihydrite. Infrared spectrum of the pure (Si-free) ferrihydrite shows a broad band at ca. 400 cm"1, with a shoulder at 600 cm"1, attributable to Fe-0 stretching vibrations. Distinct bands at 1635 cm"1 and 3400 cm"1, related to OH stretching, are apparent as well. The presence of small peaks at 975 cm" , 1055 cm" and 1125 cm" is probably an effect of sulfate complex formation on the ferrihydrite surface. Increasing Si concentration strongly affects infrared spectra of ferrihydrite: additional intensive band at ca. 990 cm" (Si-0 stretching) appears and is getting stronger with increasing Si/Fe ratio. The position of this band is shifted slightly towards higher wavenumbers (up to 1003 cm"1) at higher-Si-ferrihydrite spectra. At the same time, ~ 600 cm"1 shoulder and sulfate peaks disappear. Results of Raman spectroscopy are in general consistent with those of FTIR and gave more specific information about the band at ca. 400 cm"1, which is quite indistinct on infrared spectra and attributed to Fe-OH unsymmetrical-stretching vibrations. The band is getting broader and is slightly shifted to higher wavenumbers with increasing Si/Fe ratio but its intensity decreases drastically for the highest-Si samples (Si/Fe > 0.75). At the same time, characteristic 720 cm"1 peak and ca. 500 cm"1 shoulder become hardly visible and the spectra are getting dominated by broad but intensive band of ca. 1500-1700 cm"1, typical for amorphous silica. Additionally, sharp peak at 980 cm"1 present on lower-Si spectra is probably an effect of relic sulfate ion adsorption onto ferrihydrite surface. Preliminary results indicate that silicate ions not only cause decreasing crystallinity and retard ferrihydrite transformation but also strongly affect its surface properties. To verify this hypothesis and to enhance characteristics of Si-ferrihydrite, additional analyses are planned, including solubility, surface area and pHPZC determinations, thermal analyses and electron microscopy. Sorption/desorption studies involving cations and anions binding are planned as well.

17

Geochemistry of waters and bottom sediments in landslide lakes in Babiogórski National Park

Sala D., Rzepa G.

Mineralogia

|

2011

|

Vol. 42, iss. 1

63--72

EN

The aim of this work was to assess the contamination of the landslide lakes located within Babiogórski National Park. For this purpose, samples of water and bottom sediment from 12 lakes were collected. Chemical analyses of the waters (including main cation and anion concentrations, trace-metal levels and selected physicochemical parameters) and of the sediments (including heavy metals) were performed. The waters are acidic to neutral and are characterized by low mineralization. Concentrations of trace elements are commonly low. Elevated levels of Fe, Mn and Al are probably related to natural geochemical processes. The sediments are strongly contaminated by Cd, whereas other trace metals levels are at their hydrogeochemical background. The high level of Cd contamination is most probably related to long-range industrial emissions.

18

Lokalne kopaliny mineralne a możliwości ich wykorzystania w ochronie środowiska (na przykładzie mazurskich rud darniowych)

Ratajczak T., Rzepa G.

Inżynieria Ekologiczna

|

2011

|

Nr 27

161-169

PL

Rudy darniowe należą do zapomnianych kopalin zalegających na terenie Warmii i Mazur. W czasach historycznych były eksploatowane i stanowiły podstawę lokalnego przemysłu hutniczego. Ze względów ekonomicznych przestano je wykorzystywać. Wykazane w późniejszym czasie ich właściwości, wynikające z ich składu mineralnego i chemicznego pozwoliły traktować je jako sorbenty mineralne. W tej sytuacji obecność tych kopalin na terenie Warmii i Mazur może zostać spożytkowana praktycznie. Jako kopaliny lokalne mogą zostać wykorzystane w charakterze naturalnych sorbentów.

EN

Bog iron ores represent a forgotten or, virtually unknown mineral raw material in the Warmia and Mazury region (NE Poland). Long ago they were an interesting, exploited commodity thatmade the basis of a local "metallurgical industry", but because of economic reasons their mining ceased. However, current advances in analytical methods have resulted in revealing new, previously unsuspected properties of the bog ores. Detailed information on their mineral and chemical composition as well as physical and chemical features points to a possibility of utilizing the bog ores in question as mineral sorbents. Therefore, bog ores can become a new, local commodity in the region of Warmia and Mazury.

19

Wstępne wyniki badań mineralogiczno-hydrogeochemicznych prowadzonych w rejonie zlikwidowanej Kopalni Węgla Brunatnego "Przyjaźń Narodów" szyb "Babina" w rejonie Łęknicy

Bożęcki P., Rzepa G.

Górnictwo Odkrywkowe

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2010

|

R. 51, nr 2

66-69

PL

Obszar badań położony jest na południowym krańcu Łuku Mużakowa. W rejonie tym była prowadzona eksploatacja węgla brunatnego do początku lat 70-tych XX wieku. Po zaprzestaniu wydobycia doszło do utworzenia środowiska kwaśnych wód kopalnianych. W pracy zaprezentowano wstępne wyniki badań mineralogicznych osadów tworzących się w rejonie zlikwidowanej kopalni węgla brunatnego "Babina" jak również rezultaty analiz hydrogeochemicznych wód, ze zbiorników sedymentacyjnych.

EN

The study area is located on the southern edge of the Muskau Arc. Excavation in this area was carried to the early 70 's XX century. Stopping the operation in the research area led to creation of environment of Acid Mine Drainage (AMD). The following paper presents preliminary results of mineralogical studies of sediments forming in the region offormer lignite mine " Babina " as well as the results of hydrogeochemical research of waters from which these sediments formed.

20

Microbiology of acid waters ans ferruginous precipitates formation in the polish part of the Muskau Arch - preliminary raport

Bożęcki P., Rzepa G., Ratajczak T.

Civil and Environmental Engineering Reports

|

2010

|

No. 4

13-18

EN

This work presents preliminary results of mineralogical, geochemical and microbiological investigations carried out in the Polish part of the Muskau Arch. As a result of sulphide oxidation in this abandoned mining area, highly acidified Fe-rich waters have been formed. Ferruginous precipitates composed mainly of schwertmannite, goethite, jarosite and gypsum accompany them. Both the water chemistry and the rate of the sediments formation vary significantly due to seasonal weather changes and microbiological activity.

PL

W pracy przedstawiono wstępne wyniki badań mineralogicznych, geochemicznych i mikrobiologicznych wykonywanych w polskiej części Łuku Mużakowa. W wyniku utleniania siarczków w tym opuszczonym obszarze górnictwa tworzą się wody bardzo zakwaszone oraz bogate w żelazo. Osady żelaziste składają się głównie z schwertmannitu, goethytu, jarosytu oraz gipsu. Zarówno chemia wody oraz tempo powstawania osadów różnią się znacząco ze względu na sezonowe warunki pogodowe i aktywność mikrobiologiczną.