Accessing effects and signals of leakage from a CO<Subscript>2</Subscript> reservoir to a shallow freshwater aquifer by reactive transport modelling

CO₂ geological storage is a transitional technology for the mitigation of climate change. In the vicinity of potential CO₂ reservoirs in Hungary, protected freshwater aquifers used for drinking water supplies exist. Effects of disaster events of CO₂ escape and brine displacement to one of these aquifers have been studied by kinetic 1D reactive transport modelling in PHREEQC. Besides verifying that ion concentrations in the freshwater may increase up to drinking water limit values in both scenarios (CO₂ or brine leakage), total porosity of the rock is estimated. Pore volume is expected to increase at the entry point of CO₂ and to decrease at further distances, whereas it shows minor increase along the flow path for the effect of brine inflow. Additionally, electrical conductivity of water is estimated and suggested to be the best parameter to measure for cost-effective monitoring of both worst-case leakage scenarios.     

The investigation of flood risk perception as a quantitative analysis from socio-demographic perspective

The priority of flood management planning is physical victimization and focuses on taking structural measures. Although this approach is an accurate approach, more information is needed in implementing efficient precautionary and planning decisions. It is an indisputable fact that the existence of nothing that is not sustainable in nature cannot continue. Hence, it is necessary to implement a planning decision suitable for the structure of the population living in the region so that the continuity of the policies to be carried out against natural hazards of hydrometeorological origin such as a flood is ensured. How the socio-demographic structures affect the flood risk perception of 245 people living in the city center of Bayburt is examined in this study. It is the first research conducted for the province of Bayburt for this perspective. The participants were asked to fill a questionnaire containing 24 items and consisting of 2 sections. T test and one-way ANOVA (one-way analysis of variance) statistical methods were used to ascertain the difference between the responses of the participants to the questionnaire, based on their demographic structure. As the result of the study, significant differences were observed between the expressions depicting flood risk perception and the participant's age, income levels and educational background. In addition, it has been noted that there is a positive relationship between education and income levels and flood risk perception.

     

Effect of disturbed zone thickness on rock slope stability

Natural Hazards - Cut slope surfaces are affected by excavation activities and weathering agents. Disturbances on the surface can penetrate down to a certain depth. Slope stability analyses made on...     

Electron-probe check of fe-distribution in sphalerite grains of the Nagybörzsöny hydrothermal ore deposits,Hungary

Micron-scale iron-distribution patterns in sphalerite grains derived from two contrasting mineral assemblages of the Nagybörzsöny hydrothermal ore deposits (high temperature stockwork and low temperature veins), were determined with electron microprobe, pointcounter and continuous chart-recorder measurements along radial profiles. A significant oscillation of iron-content ranging from 8.1 to 18 per cent for stockwork and 4.3 to 15.8 per cent for veins took place during crystal growth. Homogeneous crystal cores are characteristic for vein-filling, while replacement occurring in deeper levels of the stockwork results in mosaic cores. Frequent oscillation of iron content is relevant to top-sections of the ore bodies, copious supply being recorded in recurring shells, whereas scanty, unilateral ones produce crescents arranged in onion-like structure.

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Zusammenfassung Bestimmungen der Eisenverteilung wurden an Zinkblendekörnern aus zwei verschiedenen Mineralparagenesen (Hochtemperatur-Stockwerk und Gangfüllungen niederiger Bildungstemperatur) der hydrothermalen Erzlagerstätte Nagybörzsöny im Mikronbereich durch Elektronen-Mikrosonde-Messungen (Punktzählung und kontinuierliche Band-Registrierung) entlang radialer Profile vorgenommen. Bedeutende Schwankungen des Eisengehaltes (8,1–18% für das Stockwerk und 4,3–15,8% für die Gänge) wurden registriert. Homogene Kristallkerne kennzeichnen die Gangfüllungen, wogegen in tieferen Horizonten des Stockwerks Verdrängungen zur Bildung von Kristallen mit Mosaik-Kernen führen. Allgemein ist in den Gipfel-Partien der Erzkörper Fluktuation des Eisengehaltes häufig. Gleichmäßiger Nachschub während des Kristallwachstums führte zu ringförmigen Zonen gleicher Eisengehalte, spärlicher oder einseitiger dagegen zu halbmondförmigen Hüllen mit Zwiebelstruktur.

     

Size Fractionation (Dissolved, Colloidal and Particulate) of Trace Metals in the Thur River, Switzerland

The distribution of some trace metals (Cu, Zn, Ni, Co,Fe, Mn) and of DOC over a particulate (> 1 m),a colloidal (size < 0.45 m and molecular weight > 10 kD) and an ultrafiltered fraction (< 10 kD)was determined at several sites on the Thur River,Switzerland, at various times of the year. Thecomplexation of Cu by strong ligands in theultrafiltrate and in the conventional filtrate (<0.45 m) was compared using a ligand-exchange/CSV method.The <0.45 m concentrations of Cu (from anaverage of 7 nM to 24 nM), Zn (<5–23 nM), Ni (5–13 nM),Co (1.5–3 nM) and Mn (7–92 nM)increased downstream. The major part of Cu, Zn, Niand Co usually occurred in the ultrafiltratefraction at all sites, whereas Fe and Mn were mostlyin the particulate fraction, under conditions of lowsuspended matter content (< 10 mg L^-1) in theriver. The percentage of metal in the colloidalfraction, with respect to the 0.45-m filtrate,decreased in the order: Cu (median 11%) > Zn Ni(median 5–6%) > Mn Co (median < 5%). DOCalso consisted mostly of molecules in the < 10 kDrange.Cu was strongly complexed by natural organic ligandsin all filtrate and ultrafiltrate samples. A largepart of the strong Cu binding ligands consisted ofcompounds in the < 10 kD range, but colloidalligands with similar properties also occurred. Cu wasdistributed among the dissolved and the colloidalligands, roughly in proportion to organic carbon.The colloidal fraction (as defined here) did notincrease in its proportional amount downstream and wasonly of limited significance in transporting traceelements in the Thur River under low discharge conditions.     

Multistage Variscan magmatism in the central Tauern Window (Austria) unveiled by U/Pb SHRIMP zircon data

U/Pb SHRIMP ages of nine Variscan leucocratic orthogneisses from the central Tauern Window (Austria) reveal three distinct pulses of magmatism in Early Carboniferous (Visean), Late Carboniferous (Stephanian) and Early Permian, each involving granitoid intrusions and a contemporaneous opening of volcano-sedimentary basins. A similar relationship has been reported for the Carboniferous parts of the basement of the Alps further to the west, e.g. the “External massifs” in Switzerland. After the intrusion of subduction-related, volcanic-arc granitoids (374?±?10?Ma; Zwölferkogel gneiss), collisional intrusive-granitic, anatectic and extrusive-rhyolitic/dacitic rocks were produced over a short interval at ca. 340?Ma (Augengneiss of Felbertauern: 340?±?4?Ma, Hochweißenfeld gneiss: 342?± 5?Ma, Falkenbachlappen gneiss: 343?±?6?Ma). This Early Carboniferous magmatism, which produced relatively small volumes of melt, can be attributed to the amalgamation of the Gondwana-derived “Tauern Window” terrane with Laurussia–Avalonia. Probably due to the oblique nature of the collision, transtensional phenomena (i.e. volcano-sedimentary troughs and high-level intrusives) and transpressional regimes (i.e. regional metamorphism and stacked nappes with anatexis next to thrust planes) evolved contemporaneously. The magmas are mainly of the high-K I-type and may have been generated during a short phase of decompressional melting of lithospheric mantle and lower crustal sources. In the Late Carboniferous, a second pulse of magmatism occurred, producing batholiths of calc-alkaline I-type granitoids (e.g. Venediger tonalite: 296?±?4?Ma) and minor coeval bodies of felsic and intermediate volcanics (Heuschartenkopf gneiss: 299?±?4?Ma, Peitingalm gneiss: 300?±?5?Ma). Prior to this magmatism, several kilometres of upper crust must have been eroded, because volcano-sedimentary sequences hosting the Heu- schartenkopf and Peitingalm gneisses rest unconformably on 340-Ma-old granitoids. The youngest (Permian) period of magma generation contains the intrusion of the S-type Granatspitz Central Gneiss at 271?±?4?Ma and the extrusion of the rhyolitic Schönbachwald gneiss protolith at 279?±?9?Ma. These magmatic rocks may have been associated with local extension along continental wrench zones through the Variscan orogenic crust or with a Permian rifting event. The Permian and the above-mentioned Late Carboniferous volcano-sedimentary sequences were probably deposited in intra-continental graben structures, which survived post-Variscan uplift and Alpine compressional tectonics.     

Bemerkung zu dem „Serpentintalk” aus dem Zechsteinanhydritprofil der Erdgasbohrung Frenswegen 3 im Emsland

Zusammenfassung Im folgenden werden die Röntgendaten — mit Einschränkung auch die Brechungsindizes — des von H.Füchtbauer und H.Goldschmidt untersuchten Serpentintalks den Untersuchungsergebnissen eigener Talksyntheseprodukte gegenübergestellt. Es zeigt sich eine sehr gute Übereinstimmung. Die Talksynthesen wurden im Hinblick auf semisalinare Mineralbildungen in Salzlagerstätten bei milden Metamorphosebedingungen durchgeführt. Ein Vergleich mit den Untersuchungsergebnissen der thermischen Zersetzung und der Differentialthermoanalyse, wie sie von H.Füchtbauer und H.Goldschmidt durchgeführt wurden, war nicht möglich, da die Reaktionsprodukte nicht nach diesen Methoden untersucht werden konnten. Für eine nähere Bestimmung des Serpentintalks wäre eine Gegenüberstellung weiterer Untersuchungsergebnisse sehr wichtig.     

Chemical alteration of the oceanic crust

The alteration of the upper oceanic crust through sea water-basement rock interaction produces different and distinct alteration zones with increasing depth. The zonation generally shows a consistent worldwide pattern.The uppermost basement is influenced by oxidative sea water-basalt alteration at low temperatures and high water/rock ratios. With increasing crustal depth or even in a single pillow the temperatures rise, the water/rock ratios become lower, the redox and pH values normally decrease, and the oxidative zone is followed by a non-oxidative one. Below these zones the basement has suffered high-temperature alteration under reducing and acidic conditions.This results in chemical modifications of the rocks by the addition or leaching of certain elements, and has also consequences for the composition of sea water.From our own data and data presently available in the literature I summarize the mineralogical and geochemical characteristica of sea water alteration processes affecting the oceanic crust.

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Zusammenfassung Die chemische Veränderung der oberen ozeanischen Kruste durch Gestein/Meerwasser-Interaktionen produziert verschiedene und unterscheidbare Alterationszonen die von der Krustentiefe abhängig sind. Diese Zonierung zeigt weltweit vergleichbare Muster.Das oberste Basement wird von einer niedrig temperierten oxidativen Meerwasseralteration beeinflußt. Mit zunehmender Krustentiefe steigen die Reaktionstemperaturen an, die Redox- und pH-Werte werden kleiner, d.h. nichtoxidative Alterationsvorgänge dominieren. Unterhalb dieser Zonen wird die ozeanische Kruste überwiegend von reduzierenden und sauren Hydrothermallösungen alteriert.Im Verlauf der Seewasser/Basalt-Reaktionen werden die Gesteine mineralogisch und chemisch verändert, indem verschiedene Elemente aus den Basalten herausgelöst und wiederum andere aufgenommen werden. Diese Vorgänge haben auch für die Zusammensetzung des Meerwassers drastische Konsequenzen.Mit Hilfe publizierter aber vor allem mit eigenen Daten werden die mineralogischen und geochemischen Charakteristika der unterschiedlichen Alterationsprozesse zusammengefaßt dargestellt.

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Résumé L'altération de la partie supérieure de la croûte océanique sous l'action de l'eau de mer engendre plusieurs zones distinctes qui se succèdent de haut en bas. Ce zonage présente d'ordinaire une extension mondiale.La partie supérieure de la croûte est affectée d'une altération oxydante de basse température du basalte. Vers le bas, parfois même au sein d'un même pillow, la température s'élève, la quantité d'eau décroît, le potentiel redox et le pH diminuent, de sorte que la zone d'oxydation est suivie d'une zone non oxydante. En-dessous de ces deux zones, les roches ont subi une altération de haute température dans des conditions acides et réductrices.Il en résulte des changements de la composition chimique des roches par apport ou par lessivage de certains élements, ainsi qu'une modification de la composition de l'eau de mer.A partir des données de la littérature et surtout de mes propres observations, je présente une synthèse des caractères minéralogiques et géochimiques des divers processus de l'altération sous-marine.

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