Characteristics and adaptability of iron- and sulfur-oxidizing microorganisms used for the recovery of metals from minerals and their concentrates.

PubMed

Rawlings, Douglas E

2005-05-06

Microorganisms are used in large-scale heap or tank aeration processes for the commercial extraction of a variety of metals from their ores or concentrates. These include copper, cobalt, gold and, in the past, uranium. The metal solubilization processes are considered to be largely chemical with the microorganisms providing the chemicals and the space (exopolysaccharide layer) where the mineral dissolution reactions occur. Temperatures at which these processes are carried out can vary from ambient to 80 degrees C and the types of organisms present depends to a large extent on the process temperature used. Irrespective of the operation temperature, biomining microbes have several characteristics in common. One shared characteristic is their ability to produce the ferric iron and sulfuric acid required to degrade the mineral and facilitate metal recovery. Other characteristics are their ability to grow autotrophically, their acid-tolerance and their inherent metal resistance or ability to acquire metal resistance. Although the microorganisms that drive the process have the above properties in common, biomining microbes usually occur in consortia in which cross-feeding may occur such that a combination of microbes including some with heterotrophic tendencies may contribute to the efficiency of the process. The remarkable adaptability of these organisms is assisted by several of the processes being continuous-flow systems that enable the continual selection of microorganisms that are more efficient at mineral degradation. Adaptability is also assisted by the processes being open and non-sterile thereby permitting new organisms to enter. This openness allows for the possibility of new genes that improve cell fitness to be selected from the horizontal gene pool. Characteristics that biomining microorganisms have in common and examples of their remarkable adaptability are described.

Constraining the Thermal History of the Midcontinent Rift System with Clumped Isotopes and Organic Thermal Maturity Indices

NASA Astrophysics Data System (ADS)

Gallagher, T. M.; Sheldon, N. D.; Mauk, J. L.; Gueneli, N.; Brocks, J. J.

2015-12-01

The Mesoproterozoic (~1.1 Ga) North American Midcontinent Rift System (MRS) has been of widespread interest to researchers studying its economic mineral deposits, continental rifting processes, and the evolution of early terrestrial life and environments. For their age, the MRS rocks are well preserved and have not been deeply buried, yet a thorough understanding of the regional thermal history is necessary to constrain the processes that emplaced the mineral deposits and how post-burial alteration may have affected various paleo-records. To understand the thermal history of the MRS better, this study presents carbonate clumped isotope (Δ47) temperatures from deposits on the north and south sides of the rift. Due to the age of these deposits and known post-depositional processes, uncertainties exist about whether the clumped isotope signature has been reset. To test this, three generations of calcite were analyzed from the Nonesuch Fm. from the White Pine mine in Michigan including: sedimentary limestone beds, early diagenetic carbonate nodules, and hydrothermal calcite veins associated with the emplacement of copper mineralization. Clumped isotope temperatures from the White Pine mine range from 84 to 131°C, with a hydrothermal vein producing the hottest temperature. The clumped isotope temperature range for samples throughout the rift expands to 41-134°C. The hottest temperatures are associated with areas of known copper mineralization, whereas the coolest temperatures are found on the northern arm of the rift in Minnesota, far from known basin-bounding faults. Our hottest temperatures are broadly consistent with preexisting maximum thermal temperature estimates based on clay mineralogy, fluid inclusions, and organic geochemistry data. Clumped isotope results will also be compared to new hydrocarbon maturity data from the Nonesuch Fm., which suggest that bitumen maturities consistently fall within the early oil window across Michigan and Wisconsin.

Low-temperature hydrothermal synthesis of ZnO nanorods: Effects of zinc salt concentration, various solvents and alkaline mineralizers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edalati, Khatereh, E-mail: kh_ed834@stu.um.ac.ir; Shakiba, Atefeh; Vahdati-Khaki, Jalil

2016-02-15

Highlights: • We synthesized ZnO nanorods by a simple hydrothermal process at 60 °C. • Effects of zinc salt concentration, solvent and alkaline mineralizer was studied. • Increasing concentration of zinc salt changed ZnO nucleation system. • NaOH yielded better results in the production of nanorods in both solvents. • Methanol performed better in the formation of nanorods using the two mineralizers. - Abstract: ZnO has been produced using various methods in the solid, gaseous, and liquid states, and the hydrothermal synthesis at low temperatures has been shown to be an environmentally-friendly one. The current work utilizes a low reactionmore » temperature (60 °C) for the simple hydrothermal synthesis of ZnO nanorod morphologies. Furthermore, the effects of zinc salt concentration, solvent type and alkaline mineralizer type on ZnO nanorods synthesis at a low reaction temperature by hydrothermal processing was studied. Obtained samples were analyzed using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Increasing the concentration of the starting zinc salt from 0.02 to 0.2 M changed ZnO nucleation system from the homogeneous to the heterogeneous state. The XRD results confirmed the production hexagonal ZnO nanostructures of with a crystallite size of 40.4 nm. Varying the experimental parameters (mineralizer and solvent) yielded ZnO nanorods with diameters ranging from 90–250 nm and lengths of 1–2 μm.« less

A CO2-Silica Geothermometer for Low Temperature Geothermal Resource Assessment, with Application to Resources in the Safford Basin, Arizona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witcher, James C.; Stone, Claudia

1983-11-01

Geothermics is the study of the earth's heat energy, it's affect on subsurface temperature distribution, it's physical and chemical sources, and it's role in dynamic geologic processes. The term, geothermometry, is applied to the determination of equilibrium temperatures of natural chemical systems, including rock, mineral, and liquid phases. An assemblage of minerals or a chemical system whose phase composition is a function of temperature and pressure can be used as a geothermometer. Thus a geothermometer is useful to determine the formation temperature of rock or the last equilibrium temperature of a flowing aqueous solution such as ground water and hydrothermalmore » fluids.« less

Mineral formation and organo-mineral controls on the bioavailability of carbon at the terrestrial-aquatic interface

NASA Astrophysics Data System (ADS)

Rod, K. A.; Smith, A. P.; Renslow, R.

2016-12-01

Recent evidence highlights the importance of organo-mineral interactions in regulating the source or sink capacity of soil. High surface area soils, such as allophane-rich or clay-rich soils, retain organic matter (OM) via sorption to mineral surfaces which can also contribute physical isolation in interlayer spaces. Despite the direct correlation between mineral surfaces and OM accumulation, the pedogenic processes controlling the abundance of reactive surface areas and their distribution in the mineral matrix remains unclear. As global soil temperatures rise, the dissolution of primary minerals and formation of new secondary minerals may be thermodynamically favored as part of soil weathering process. Newly formed minerals can supply surfaces for organo-metallic bonding and may, therefore, stabilize OM by surface bonding and physical exclusion. This is especially relevant in environments that intersect terrestrial and aquatic systems, such as the capillary fringe zone in riparian ecosystems. To test the mechanisms of mineral surface area protection of OM, we facilitated secondary precipitation of alumino-silicates in the presence of OM held at two different temperatures in natural Nisqually River sediments (Mt Rainier, WA). This was a three month reaction intended to simulate early pedogenesis. To tease out the influence of mineral surface area increase during pedogenesis, we incubated the sediments at two different soil moisture contents to induce biodegradation. We measured OM desorption, biodegradation, and the molecular composition of mineral-associated OM both prior to and following the temperature manipulation. To simulate the saturation of capillary fringe sediment and associated transport and reaction of OM, column experiments were conducted using the reacted sediments. More co-precipitation was observed in the 20°C solution compared to the 4°C reacted solution suggesting that warming trends alter mineral development and may remove more OM from solution. The results from the static experiments will be used to model and predict the impacts of mineral sorption and biological activity on OM persistence in the context of dynamic saturation conditions and heterogeneous material properties.

Application of computational methods to analyse and investigate physical and chemical processes of high-temperature mineralizing of condensed substances in gas stream

NASA Astrophysics Data System (ADS)

Markelov, A. Y.; Shiryaevskii, V. L.; Kudrinskiy, A. A.; Anpilov, S. V.; Bobrakov, A. N.

2017-11-01

A computational method of analysis of physical and chemical processes of high-temperature mineralizing of low-level radioactive waste in gas stream in the process of plasma treatment of radioactive waste in shaft furnaces was introduced. It was shown that the thermodynamic simulation method allows fairly adequately describing the changes in the composition of the pyrogas withdrawn from the shaft furnace at different waste treatment regimes. This offers a possibility of developing environmentally and economically viable technologies and small-sized low-cost facilities for plasma treatment of radioactive waste to be applied at currently operating nuclear power plants.

Climate response of the soil nitrogen cycle in three forest types of a headwater Mediterranean catchment

NASA Astrophysics Data System (ADS)

Lupon, Anna; Gerber, Stefan; Sabater, Francesc; Bernal, Susana

2015-05-01

Future changes in climate may affect soil nitrogen (N) transformations, and consequently, plant nutrition and N losses from terrestrial to stream ecosystems. We investigated the response of soil N cycling to changes in soil moisture, soil temperature, and precipitation across three Mediterranean forest types (evergreen oak, beech, and riparian) by fusing a simple process-based model (which included climate modifiers for key soil N processes) with measurements of soil organic N content, mineralization, nitrification, and concentration of ammonium and nitrate. The model describes sources (atmospheric deposition and net N mineralization) and sinks (plant uptake and hydrological losses) of inorganic N from and to the 0-10 cm soil pool as well as net nitrification. For the three forest types, the model successfully recreated the magnitude and temporal pattern of soil N processes and N concentrations (Nash-Sutcliffe coefficient = 0.49-0.96). Changes in soil water availability drove net N mineralization and net nitrification at the oak and beech forests, while temperature and precipitation were the strongest climatic factors for riparian soil N processes. In most cases, net N mineralization and net nitrification showed a different sensitivity to climatic drivers (temperature, soil moisture, and precipitation). Our model suggests that future climate change may have a minimal effect on the soil N cycle of these forests (<10% change in mean annual rates) because positive warming and negative drying effects on the soil N cycle may counterbalance each other.

Enhanced 99Tc retention in glass waste form using Tc(IV)-incorporated Fe minerals

DOE PAGES

Um, Wooyong; Luksic, Steven A.; Wang, Guohui; ...

2017-09-07

We present that technetium ( 99Tc) immobilization by doping into iron oxide mineral phases may alleviate the problems with Tc volatility during vitrification of nuclear waste. Because reduced Tc, Tc(IV), substitutes for Fe(III) in the crystal structure by a process of Tc reduction from Tc(VII) to Tc(IV) followed by co-precipitation of Fe oxide minerals, two Tc-incorporated Fe minerals (Tc-goethite and Tc-magnetite/maghemite) were prepared and tested for Tc retention in glass melt samples at temperatures between 600 and 1000 °C. After being cooled, the solid glass specimens prepared at different temperatures at 600, 800, and 1000 °C were analyzed for Tcmore » oxidation state using Tc K-edge XANES. In most samples, Tc was partially (<60%) oxidized from Tc(IV) to Tc(VII) as the melt temperature increased up to 600 °C. However, most of Tc(IV) was completely (>95%) oxidized to Tc(VII) at temperature above 800 °C. Tc retention in glass melt samples prepared using Tc-incorporated Fe minerals were slightly higher (~10%) than in glass prepared using KTcO4 because of limited and delayed Tc volatilization.« less

Enhanced 99Tc retention in glass waste form using Tc(IV)-incorporated Fe minerals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Um, Wooyong; Luksic, Steven A.; Wang, Guohui

We present that technetium ( 99Tc) immobilization by doping into iron oxide mineral phases may alleviate the problems with Tc volatility during vitrification of nuclear waste. Because reduced Tc, Tc(IV), substitutes for Fe(III) in the crystal structure by a process of Tc reduction from Tc(VII) to Tc(IV) followed by co-precipitation of Fe oxide minerals, two Tc-incorporated Fe minerals (Tc-goethite and Tc-magnetite/maghemite) were prepared and tested for Tc retention in glass melt samples at temperatures between 600 and 1000 °C. After being cooled, the solid glass specimens prepared at different temperatures at 600, 800, and 1000 °C were analyzed for Tcmore » oxidation state using Tc K-edge XANES. In most samples, Tc was partially (<60%) oxidized from Tc(IV) to Tc(VII) as the melt temperature increased up to 600 °C. However, most of Tc(IV) was completely (>95%) oxidized to Tc(VII) at temperature above 800 °C. Tc retention in glass melt samples prepared using Tc-incorporated Fe minerals were slightly higher (~10%) than in glass prepared using KTcO4 because of limited and delayed Tc volatilization.« less

Carbon Isotope Systematics in Mineral-Catalyzed Hydrothermal Organic Synthesis Processes at High Temperature and Pressures

NASA Technical Reports Server (NTRS)

Fu, Qi; Socki, R. A.; Niles, Paul B.

2011-01-01

Observation of methane in the Martian atmosphere has been reported by different detection techniques. Reduction of CO2 and/or CO during serpentization by mineral surface catalyzed Fischer-Tropsch Type (FTT) synthesis may be one possible process responsible for methane generation on Mars. With the evidence a recent study has discovered for serpentinization in deeply buried carbon rich sediments, and more showing extensive water-rock interaction in Martian history, it seems likely that abiotic methane generation via serpentinization reactions may have been common on Mars. Experiments involving mineral-catalyzed hydrothermal organic synthesis processes were conducted at 750 C and 5.5 Kbars. Alkanes, alcohols and carboxylic acids were identified as organic compounds. No "isotopic reversal" of delta C-13 values was observed for alkanes or carboxylic acids, suggesting a different reaction pathway than polymerization. Alcohols were proposed as intermediaries formed on mineral surfaces at experimental conditions. Carbon isotope data were used in this study to unravel the reaction pathways of abiotic formation of organic compounds in hydrothermal systems at high temperatures and pressures. They are instrumental in constraining the origin and evolution history of organic compounds on Mars and other planets.

Geomicrobiology in oceanography: microbe-mineral interactions at and below the seafloor.

PubMed

Edwards, Katrina J; Bach, Wolfgang; McCollom, Thomas M

2005-09-01

Oceanography is inherently interdisciplinary and, since its inception, has included the study of microbe-mineral interactions. From early studies of manganese nodules, to the discovery of hydrothermal vents, it has been recognized that microorganisms are involved at various levels in the transformation of rocks and minerals at and below the seafloor. Recent studies include mineral weathering at low temperatures and microbe-mineral interactions in the subseafloor "deep biosphere". A common characteristic of seafloor and subseafloor geomicrobiological processes that distinguishes them from terrestrial or near-surface processes is that they occur in the dark, one or more steps removed from the sunlight that fuels the near-surface biosphere on Earth. This review focuses on geomicrobiological studies and energy flow in dark, deep-ocean and subseafloor rock habitats.

Terrestrial and Martian weathering signatures of xenon components in shergottite mineral separates

NASA Astrophysics Data System (ADS)

Cartwright, J. A.; Ocker, K. D.; Crowther, S. A.; Burgess, R.; Gilmour, J. D.

2010-08-01

Xenon-isotopic ratios, step-heating release patterns, and gas concentrations of mineral separates from Martian shergottites Roberts Massif (RBT) 04262, Dar al Gani (DaG) 489, Shergotty, and Elephant Moraine (EET) 79001 lithology B are reported. Concentrations of Martian atmospheric xenon are similar in mineral separates from all meteorites, but more weathered samples contain more terrestrial atmospheric xenon. The distributions of xenon from the Martian and terrestrial atmospheres among minerals in any one sample are similar, suggesting similarities in the processes by which they were acquired. However, in opaque and maskelynite fractions, Martian atmospheric xenon is released at higher temperatures than terrestrial atmospheric xenon. It is suggested that both Martian and terrestrial atmospheric xenon were initially introduced by weathering (low temperature alteration processes). However, the Martian component was redistributed by shock, accounting for its current residence in more retentive sites. The presence or absence of detectable 129Xe from the Martian atmosphere in mafic minerals may correspond to the extent of crustal contamination of the rock's parent melt. Variable contents of excess 129Xe contrast with previously reported consistent concentrations of excess 40Ar, suggesting distinct sources contributed these gases to the parent magma.

Argon thermochronology of mineral deposits; a review of analytical methods, formulations, and selected applications

USGS Publications Warehouse

Snee, Lawrence W.

2002-01-01

40Ar/39Ar geochronology is an experimentally robust and versatile method for constraining time and temperature in geologic processes. The argon method is the most broadly applied in mineral-deposit studies. Standard analytical methods and formulations exist, making the fundamentals of the method well defined. A variety of graphical representations exist for evaluating argon data. A broad range of minerals found in mineral deposits, alteration zones, and host rocks commonly is analyzed to provide age, temporal duration, and thermal conditions for mineralization events and processes. All are discussed in this report. The usefulness of and evolution of the applicability of the method are demonstrated in studies of the Panasqueira, Portugal, tin-tungsten deposit; the Cornubian batholith and associated mineral deposits, southwest England; the Red Mountain intrusive system and associated Urad-Henderson molybdenum deposits; and the Eastern Goldfields Province, Western Australia.

Replacement processes in crystalline rocks

NASA Astrophysics Data System (ADS)

John, Timm; Putnis, Andrew

2010-05-01

A substantial question in metamorphism is what is the mechanism that dominates the conversion of one mineral assemblage to another in response to a change in the ambient physical and/or chemical conditions. Petrological, microstructural, and isotopic data indicate that aqueous fluids must be involved even in the reequilibration of large-scale systems. Fluid-mineral reactions take place by dissolution - precipitation processes, but converting one solid rock to another requires pervasive, either dominantly advective or diffusive fluid-mediated transport through the entire rock. The generation of reaction-induced porosity and the spatial and temporal coupling of dissolution and precipitation can account for fluid and element transport through rocks and the replacement of one mineral assemblage by another. To determine the mechanism of metamorphic reactions we refer to examples of interfaces and reaction textures which contain both the "before" (precursor) and "after" mineral assemblages - case studies where the process of conversion is frozen in. We will illustrate some aspects of the role of fluids in metamorphic reactions and discuss how reactive fluids can pervasively infiltrate a rock. The examples we will use are focussed on crystalline rocks and include reactions from the lower continental crust, the subducting oceanic crust, and the continental upper crust to show that except at very high-temperature conditions, essentially the same mechanisms are responsible for converting rocks to thermodynamically more stable mineral assemblages for given Pressure-Temperature-fluid composition (P-T-X) conditions.

Discovery of New Mineral Butianite, Ni6SnS2, an Alteration Phase from Allende

NASA Astrophysics Data System (ADS)

Ma, C.

2017-07-01

Butianite (Ni6SnS2) is a new chalcogenide mineral from an Allende CAI, along with nuwaite (Ni6GeS2), formed from a late-stage sulfidation process, where Ni-Fe metals reacted with a low-temperature fluid enriched in S, Ge, Sn and Te.

Temperature-dependent dynamics of bovine casein micelles in the range 10-40 °C.

PubMed

Liu, Dylan Z; Weeks, Michael G; Dunstan, David E; Martin, Gregory J O

2013-12-15

Milk is a complex colloidal system that responds to changes in temperature imposed during processing. Whilst much has been learned about the effects of temperature on milk, little is known about the dynamic response of casein micelles to changes in temperature. In this study, a comprehensive physico-chemical study of casein micelles in skim milk was performed between 10 and 40 °C. When fully equilibrated, the amount of soluble casein, soluble calcium and the pH of skim milk all decreased as a function of increasing temperature, whilst the hydration and volume fraction of the casein micelles decreased. The effect of temperature on casein micelle size, as determined by dynamic light scattering and differential centrifugation, was less straightforward. Real-time measurements of turbidity and pH were used to investigate the dynamics of the system during warming and cooling of milk in the range 10-40 °C. Changes in pH are indicative of changes to the mineral system and the turbidity is a measure of alterations to the casein micelles. The pH and turbidity showed that alterations to both the casein micelles and the mineral system occurred very rapidly on warming. However, whilst mineral re-equilibration occurred very rapidly on cooling, changes to the casein micelle structure continued after 40 min of measurement, returning to equilibrium after 16 h equilibration. Casein micelle structure and the mineral system of milk were both dependent on temperature in the range 10-40 °C. The dynamic response of the mineral system to changes in temperature appeared almost instantaneous whereas equilibration of casein was considerably slower, particularly upon cooling. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fire Events and Soil Thermometry: The Applications of Clay Chemistry for Tracing Temperature Changes in Soils and Sediments Below Surface Fires

NASA Astrophysics Data System (ADS)

Watson, E.; Werts, S. P.; Gelabert, M.

2016-12-01

Fires in the natural environment affect the physical, chemical, and biological properties of soils. However, fires may also alter the mineralogy of the geologic material in which it comes in contact. Previous experiments on high temperature alteration of clays indicate that dehydration, oxidation, and hydroxylation in clay minerals can occur progressively in that order at increasing temperatures up to 500°C. It is also well known that wildfire events can heat soils to these temperature ranges several centimeters deep. In this experiment, alterations in clay chemistry were used as a tool to investigate fire intensity along with the changing morphology of clay minerals. For data collection, small camp fires were set in York County, SC and temperatures were recorded using a datalogger system to 5 cm deep during the fire event. Control samples were taken adjacent to the fires to compare the changing morphology of the minerals when heated. Powder x-ray diffraction and scanning electron microscopy were used to identify the clay mineralogy. The clay from soil samples was identified as hydrous kaolinite, anhydrous kaolinite, and varying types of goethite. To observe the dehydration, oxidation, and hydroxylation of clay minerals, scanning electron microscopy with emission dispersive spectroscopy was used to identify the O/cation ratios present, which would indicate changes in the oxidation state of the clay minerals. By mapping the changes in O/cation ratios with temperature in silicates, we are able to trace the temperature of the sediments during fire events. This research suggests it may be possible to utilize these geochemical trends to aid in soil and sediment temperature investigations in both archeological and modern soil and surface process investigations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stanislav S. Gornostayev; Jouko J. Haerkki

Examinations of polished and dry cut sections of feed and tuyere coke revealed some possible mechanisms for the physical influence of mineral compounds on the reactivity and strength of coke. It was observed that rounded particles of mineral phases that are exposed to the pore walls and surface of coke at high temperature create an inorganic cover, thus reducing the surface available for gas-solid reactions. The particles of mineral matter that have a low melting point and viscosity can affect the coke at earlier stages in the blast furnace process, acting in the upper parts of the blast furnace (BF).more » The temperature-driven redistribution of mineral phases within the coke matrix probably leads to the creation of weak spots and in general to anisotropy in its properties, thus reducing its strength. 9 refs., 2 figs., 1 tab.« less

Characteristics of Hydrothermal Mineralization in Ultraslow Spreading Ridges

NASA Astrophysics Data System (ADS)

Zhou, H.; Yang, Q.; Ji, F.; Dick, H. J.

2014-12-01

Hydrothermal activity is a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth's crust and oceans, and a locus for intense biological activity on the seafloor and underlying crust. In other hand, the structure and composition of hydrothermal systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes. Ultraslow spreading ridges, including the Southwest Indian Ridge, the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys in last decades, it is suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining hydrothermal activities. This increased efficiency could attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004). Distinct from in faster spreading ridges, one characteristics of hydrothermal mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag hydrothermal field at 49.6 degree of the Southwest Indian Ridge, is abundant and pervasive distribution of lower temperature precipitated minerals ( such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite etc. ) in hydrothermal fields. Structures formed by lower temperature activities in active and dead hydrothermal fields are also obviously. High temperature precipitated minerals such as chalcopyrite etc. are rare or very limited in hydrothermal chimneys. Distribution of diverse low temperature hydrothermal activities is consistence with the deep heating mechanisms and hydrothermal circulations in the complex background of ultraslow spreading tectonics. Meanwhile, deeper and larger mineralization at certain locations along the ultraslow spreading ridges is also presumable.

Engineered yeast for enhanced CO2 mineralization†

PubMed Central

Barbero, Roberto; Carnelli, Lino; Simon, Anna; Kao, Albert; Monforte, Alessandra d’Arminio; Riccò, Moreno; Bianchi, Daniele; Belcher, Angela

2014-01-01

In this work, a biologically catalyzed CO2 mineralization process for the capture of CO2 from point sources was designed, constructed at a laboratory scale, and, using standard chemical process scale-up protocols, was modeled and evaluated at an industrial scale. A yeast display system in Saccharomyces cerevisae was used to screen several carbonic anhydrase isoforms and mineralization peptides for their impact on CO2 hydration, CaCO3 mineralization, and particle settling rate. Enhanced rates for each of these steps in the CaCO3 mineralization process were confirmed using quantitative techniques in lab-scale measurements. The effect of these enhanced rates on the CO2 capture cost in an industrial scale CO2 mineralization process using coal fly ash as the CaO source was evaluated. The model predicts a process using bCA2- yeast and fly ash is ~10% more cost effective per ton of CO2 captured than a process with no biological molecules, a savings not realized by wild-type yeast and high-temperature stable recombinant CA2 alone or in combination. The levelized cost of electricity for a power plant using this process was calculated and scenarios in which this process compares favorably to CO2 capture by MEA absorption process are presented. PMID:25289021

Gas-solid carbonation as a possible source of carbonates in cold planetary environments

NASA Astrophysics Data System (ADS)

Garenne, A.; Montes-Hernandez, G.; Beck, P.; Schmitt, B.; Brissaud, O.; Pommerol, A.

2013-02-01

Carbonates are abundant sedimentary minerals at the surface and sub-surface of the Earth and they have been proposed as tracers of liquid water in extraterrestrial environments. Their formation mechanism is since generally associated with aqueous alteration processes. Recently, carbonate minerals have been discovered on Mars' surface by different orbitals or rover missions. In particular, the phoenix mission has measured from 1% to 5% of calcium carbonate (calcite type) within the soil (Smith et al., 2009). These occurrences have been reported in area where the relative humidity is significantly high (Boynton et al., 2009). The small concentration of carbonates suggests an alternative process on mineral grain surfaces (as suggested by Shaheen et al., 2010) than carbonation in aqueous conditions. Such an observation could rather point toward a possible formation mechanism by dust-gas reaction under current Martian conditions. To understand the mechanism of carbonate formation under conditions relevant to current Martian atmosphere and surface, we designed an experimental setup consisting of an infrared microscope coupled to a cryogenic reaction cell (IR-CryoCell setup). Three different mineral precursors of carbonates (Ca and Mg hydroxides, and a hydrated Ca silicate formed from Ca2SiO4), low temperature (from -10 to +30 °C), and reduced CO2 pressure (from 100 to 2000 mbar) were utilized to investigate the mechanism of gas-solid carbonation at mineral surfaces. These mineral materials are crucial precursors to form Ca and Mg carbonates in humid environments (0%

Evaluation of mineral-aqueous chemical equilibria of felsic reservoirs with low-medium temperature: A comparative study in Yangbajing geothermal field and Guangdong geothermal fields

NASA Astrophysics Data System (ADS)

Li, Jiexiang; Sagoe, Gideon; Yang, Guang; Lu, Guoping

2018-02-01

Classical geothermometers are useful tools for estimating reservoir temperatures of geothermal systems. However, their application to low-medium temperature reservoirs is limited because large variations of temperatures calculated by different classical geothermometers are usually observed. In order to help choose the most appropriate classical geothermometer for calculating the temperatures of low-medium temperature reservoirs, this study evaluated the mineral-aqueous equilibria of typical low-medium temperature felsic reservoirs in the Yangbajing geothermal field and Guangdong geothermal fields. The findings of this study support that reservoirs in the Guangdong geothermal fields have no direct magma influence. Also, natural reservoirs may represent the intermediate steady state before reaching full equilibrium, which rarely occurs. For the low-medium temperature geothermal systems without the influence of magma, even with seawater intrusion, the process of minerals reaching mineral-aqueous equilibrium is sequential: chlorite and chalcedony are the first, then followed by K-feldspar, kaolinite and K-mica. Chlorite may reach equilibrium at varying activity values, and the equilibrium between K-feldspar and kaolinite or K-feldspar and K-mica can fix the contents of K and Al in the solutions. Although the SiO2 and Al attain equilibrium state, albite and laumontite remain unsaturated and thus may affect low-medium temperature calculations. In this study, the chalcedony geothermometer was found to be the most suitable geothermometer for low-medium temperature reservoirs. The results of K-Mg geothermometer may be useful to complement that of the chalcedony geothermometer in low-medium temperature reservoir systems. Na-K geothermometer will give unreliable results at low-medium temperatures; and Na-K-Ca will also be unsuitable to calculate reservoir temperatures lower than 180 °C, probably caused by the chemical imbalance of laumontite.

Temperature-driven decoupling of key phases of organic matter degradation in marine sediments.

PubMed

Weston, Nathaniel B; Joye, Samantha B

2005-11-22

The long-term burial of organic carbon in sediments results in the net accumulation of oxygen in the atmosphere, thereby mediating the redox state of the Earth's biosphere and atmosphere. Sediment microbial activity plays a major role in determining whether particulate organic carbon is recycled or buried. A diverse consortium of microorganisms that hydrolyze, ferment, and terminally oxidize organic compounds mediates anaerobic organic matter mineralization in anoxic sediments. Variable temperature regulation of the sequential processes, leading from the breakdown of complex particulate organic carbon to the production and subsequent consumption of labile, low-molecular weight, dissolved intermediates, could play a key role in controlling rates of overall organic carbon mineralization. We examined sediment organic carbon cycling in a sediment slurry and in flow through bioreactor experiments. The data show a variable temperature response of the microbial functional groups mediating organic matter mineralization in anoxic marine sediments, resulting in the temperature-driven decoupling of the production and consumption of organic intermediates. This temperature-driven decoupling leads to the accumulation of labile, low-molecular weight, dissolved organic carbon at low temperatures and low-molecular weight dissolved organic carbon limitation of terminal metabolism at higher temperatures.

Effect Of Milling Time on Particle Size of Forsterite (Mg2SiO4) from South Solok District

NASA Astrophysics Data System (ADS)

Sarimai, S.; Ratnawulan, R.; Ramli, R.; Fauzi, A.

2018-04-01

West Sumatra has considerable serpentine mineral resources, including the Jorong Sungai Padi Nagari Lubuak Gadang Sangir Subdistrict, South Solok District. Exploitation of minerals of serpentine is still processed in raw or semi-finished material so that it has a low selling value. Serpentine minerals contain forsterite minerals that have higher economic value if in the form of nanoparticles. The manufacture of forsterite nanoparticles has been done using synthetic materials, while synthetic materials are expensive and require a long process to make them. The treatment of temperature variations of calcination to serpentine minerals, obtained results found forsterite phase that dominates at a temperature of 800 °C. Serpentine minerals can be used as alternative ingredients for the nanoparticle makers of forsterite that are easy to find in the deep, and do not require expensive to make them. The purpose of this study was to investigate the effect of milling time on the microstructure and grain size of the serpentine forsterite mineral nanoparticles in the form of crystal structure, crystal size, and particle size. The results of the study showed grain size of 5, 10, 20, and 40 hours milling time are 579, 478, 451, and 385 nm respectively. Based on the research that has been done can be drawn conclusion Time milling effect on the grain size of forsterite mineral serpentine from South Solok District, the longer milling time the size of forsterite grains smaller. Optimum milling time to produce nano forsterite is 40 hours with a grain size of 385 nm.

[Nitrogen mineralization rate in different soil layers and its influence factors under plastic film mulched in Danjiangkou Reservoir area, China].

PubMed

Yu, Xing Xiu; Xui, Miao Miao; Zhao, Jin Hui; Zhang, Jia Peng; Wang, Wei; Guo, Ya Li; Xiao, Juan Hua

2018-04-01

The objective of this study was to investigate the rate of nitrogen mineralization in various soil layers (0-10, 10-20, and 20-30 cm) and its influencing factors under plastic film mulching ridge-furrow in a corn field of Wulongchi small watershed, Danjiangkou Reservoir Area. Results showed that the rate of soil ammonification decreased with soil depth during the entire maize growth period. The rate of nitrification in seedling, jointing, and heading stages decreased in the following order: 10-20 cm > 0-10 cm > 20-30 cm, while it increased with soil depth in maturation stage. The rate of soil nitrogen mineralization decreased with the increases in soil depth in the seedling, jointing and heading stages, whereas an opposite pattern was observed in maturation stage. Compared with non-filming, film mulching promoted the soil ammonification process in 0-10 cm and the soil nitrification and nitrogen mineralization processes in jointing, heading, and maturation stages in both 0-10 and 10-20 cm. However, the rates of soil nitrification and nitrogen mineralization under film mulching were much lower than those under non-filming in seedling stage. The stepwise regression analysis indicated that the main factors influencing soil nitrogen mineralization rate varied with soil depth. Soil moisture and total N content were the dominant controller for variation of soil nitrogen mineralization in 0-10 cm layer. Soil temperature, moisture, and total N content were dominant controller for that in 10-20 cm layer. Soil temperature drove the variation of soil nitrogen mineralization in 20-30 cm layer.

Numerical modeling of the impact of temperature on the behavior of minerals in the Soultz-sous-Forêts enhanced geothermal system

NASA Astrophysics Data System (ADS)

Van Ngo, Viet; Lucas, Yann; Clément, Alain; Fritz, Bertrand

2015-04-01

Operation of the enhanced geothermal system (EGS) requires to re-inject fluid, after heat exchange at the surface to the energy production, into the geothermal reservoir. This cold re-injected fluid can cause a strong disequilibrium with the fluid and granitic rock within the geothermal reservoir and then implies the possible dissolution/precipitation of minerals. The hydrothermal alterations include the transformation of plagioclase, biotite and K-feldspar and the precipitation of various secondary minerals. The major sealing phases observed in the main fracture zones are quartz, calcite, and clay minerals. These mineralogical transformations may modify the porosity, permeability and fluid pathways of the geothermal reservoir. In the Soultz-sous-Forêts EGS (Alsace, France), the hydraulic connection between the injection well and the production well is quite poor. Therefore, understanding the impact of changes in temperature, which are caused by the re-injected fluid, on the behavior of minerals (especially for the main newly-formed minerals such as quartz, calcite and clay minerals) is a critical preliminary step for the long-term prediction of their evolution. The approach used in the present work is typically based on a geochemical code, called THERMA, which enables to calculate the changes in equilibrium constants of all primary and secondary minerals and aqueous species as a function of temperature. Our model accounted for a wide range of different mineral groups in order to make sure a large freedom for the numerical calculations. The modeling results showed that when the temperature of geothermal reservoir is cooled down, quartz, calcite, illites, galena and pyrite have tendency towards equilibrium state, which indicates that they are precipitated under the geothermal conditions. In contrast, other minerals including plagioclase, K-feldspar and biotite remained unsaturated. These behaviors of minerals were further illustrated by the Khorzinsky stability diagrams, which are based on the activities of different species such as H4SiO4, Ca2+, Mg2+, and Al3+ and take into account partial CO2 pressure,. The modeling results further suggested that we should pay a special attention to the main minerals (e.g., quartz, calcite and illites) when studying the changes in porosity and permeability of the geothermal reservoir. This study was preparing a simulation of water-rock interaction processes related to these temperature conditions.

Silver-bearing minerals in the Xinhua hydrothermal vein-type Pb-Zn deposit, South China

NASA Astrophysics Data System (ADS)

Wang, Minfang; Zhang, Xubo; Guo, Xiaonan; Pi, Daohui; Yang, Meijun

2018-02-01

Electron probe microanalysis (EPMA) results are reported for newly identified silver-bearing minerals from the Xinhua deposit, Yunkaidashan area, South China. The Xinhua deposit is a hydrothermal vein-type Pb-Zn deposit and is hosted in the Pubei Complex, which consists of a cordierite-biotite granite with a U-Pb zircon age of 244.3 ± 1.8-251.9 ± 2.2 Ma. The mineralization process is subdivided into four mineralization stages, characterized by the following mineral associations: mineralization stage I with quartz, pyrite, and sphalerite; mineralization stage II with siderite, galena, and tetrahedrite; mineralization stage III with quartz and galena; and mineralization stage IV with quartz, calcite, and baryte. Tetrahedrite series minerals, such as freibergite, argentotetrahedrite, and tennantite are the main Ag-bearing minerals in the Xinhua deposit. The greatest concentration of silver occurs in phases from mineralization stage II. Microscopic observations reveal close relationship between galena and tetrahedrite series minerals that mostly occur as irregular inclusions within galena. The negative correlation between Cu and Ag in the lattices of tetrahedrite series minerals suggests that Cu sites are occupied by Ag atoms. Zn substitution for Fe in argentotetrahedrite and Cd substitution for Pb in tetrahedrite are also observed. Micro-thermometric data reveal that both homogenization temperatures and calculated salinities of hydrothermal fluids decrease progressively from the early to the later mineralization stages. The metal ions, such as Ag+, Cu+, Pb2+, and Zn2+, are transported as chlorine complex ions in the early mineralization stage and as bisulfide complex ions in the late mineralization stage, caused by changes in oxygen fugacity, temperature, and pH of the hydrothermal fluids. Because of the varying solubility of different metal ions, Pb2+, Zn2+, and Cu2+ ions are initially precipitated as galena, sphalerite, and chalcopyrite, respectively. With decreasing temperature of the fluids, Pb2+ ions are incorporated along with Cu+, Sb3+, and As3+ ions into sulfosalt minerals, and Ag+ ions are coprecipitated with Cu+, Sb3+, and As3+ ions forming tetrahedrite series minerals or replacing earlier sulfides and sulfosalts.

High liquid yield process for retorting various organic materials including oil shale

DOEpatents

Coburn, Thomas T.

1990-01-01

This invention is a continuous retorting process for various high molecular weight organic materials, including oil shale, that yields an enhanced output of liquid product. The organic material, mineral matter, and an acidic catalyst, that appreciably adsorbs alkenes on surface sites at prescribed temperatures, are mixed and introduced into a pyrolyzer. A circulating stream of olefin enriched pyrolysis gas is continuously swept through the organic material and catalyst, whereupon, as the result of pyrolysis, the enhanced liquid product output is provided. Mixed spent organic material, mineral matter, and cool catalyst are continuously withdrawn from the pyrolyzer. Combustion of the spent organic material and mineral matter serves to reheat the catalyst. Olefin depleted pyrolysis gas, from the pyrolyzer, is enriched in olefins and recycled into the pyrolyzer. The reheated acidic catalyst is separated from the mineral matter and again mixed with fresh organic material, to maintain the continuously cyclic process.

A high liquid yield process for retorting various organic materials including oil shale

DOEpatents

Coburn, T.T.

1988-07-26

This invention is a continuous retorting process for various high molecular weight organic materials, including oil shale, that yields an enhanced output of liquid product. The organic material, mineral matter, and an acidic catalyst, that appreciably adsorbs alkenes on surface sites at prescribed temperatures, are mixed and introduced into a pyrolyzer. A circulating stream of olefin enriched pyrolysis gas is continuously swept through the organic material and catalyst, whereupon, as the result of pyrolysis, the enhanced liquid product output is provided. Mixed spent organic material, mineral matter, and cool catalyst are continuously withdrawn from the pyrolyzer. Combustion of the spent organic material and mineral matter serves to reheat the catalyst. Olefin depleted pyrolysis gas, from the pyrolyzer, is enriched in olefins and recycled into the pyrolyzer. The reheated acidic catalyst is separated from the mineral matter and again mixed with fresh organic material, to maintain the continuously cyclic process. 2 figs.

Irreverent Soils: Nitrogen Dynamics In Taiga Forests During Winter

NASA Astrophysics Data System (ADS)

Kielland, K.

2003-12-01

We measured annual net nitrogen mineralization, nitrification, and amino acid production in situ across a primary successional sequence in interior Alaska, USA. Net N mineralization rates during the growing season from green-up (late May) through freeze-up (late September) accounted for approximately 60% of the annual inorganic N flux, whereas the remaining N was released during the apparent dormant season. Nitrogen release during winter occurred primarily during October-January with only negligible N mineralization during early spring in stands of willow, alder, balsam poplar and white spruce. By contrast, black spruce stands also exhibited substantial mineralization after snow melt during early spring. The high rates of N mineralization in late autumn through early winter coincides with high turnover of fine root biomass in these stands, suggesting that labile substrate production, rather than temperature, is a major controlling factor over N release in these ecosystems. The results are consistent with the low temperature sensitivity of N mineralization previously documented for taiga soils, and demonstrate that measurements of soil processes restricted to the growing season may greatly underestimate annual flux rates of inorganic nitrogen in high-latitude ecosystems.

Stacking Defects in Synthetic and Meteoritic Hibonites: Implications for High-Temperature Processes in the Solar Nebula

NASA Technical Reports Server (NTRS)

Han, J.; Keller, L. P.; Brearley, A. J.; Danielson, L. R.

2016-01-01

Hibonite (CaAl12O19) is a primary, highly refractory phase occurring in many Ca-Al-rich inclusions (CAIs) from different chondrite groups, except CI chondrites. Hibonite is predicted to be one of the earliest minerals to condense during cooling of the solar nebula at higher temperatures than any other major CAI mineral. Therefore, hibonite has great potential to reveal the processes and conditions of the very early, high-temperature stages of the solar nebular evolution. Previous microstructural studies of hibonite in CAIs and their Wark-Lovering (WL) rims showed the presence of numerous stacking defects in hibonite. These defects are interpreted as the modification of the stacking sequences of spinel and Ca-containing blocks within the ideal hexagonal hibonite structure, as shown by experimental studies of reaction-sintered ceramic CaO-Al2O3 compounds. We performed preliminary experiments in the CaO-Al2O3-MgO system to understand the formation processes and conditions of defect-structured hibonite found in meteorites.

Kinetic Fractionation of Stable Isotopes in Carbonates on Mars: Terrestrial Analogs

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Gibson, Everett K., Jr.; Golden, D. C.; Ming, Douglas W.; McKay, Gordon A.

2003-01-01

An ancient Martian hydrosphere consisting of an alkali-rich ocean would likely produce solid carbonate minerals through the processes of evaporation and/or freezing. We postulate that both (or either) of these kinetically-driven processes would produce carbonate minerals whose stable isotopic compositions are highly fractionated (enriched) with respect to the source carbon. Various scenarios have been proposed for carbonate formation on Mars, including high temperature formation, hydrothermal alteration, precipitation from evaporating brines, and cryogenic formation. 13C and 18O -fractionated carbonates have previously been shown to form kinetically under some of these conditions, ie.: 1) alteration by hydrothermal processes, 2) low temperature precipitation (sedimentary) from evaporating bicarbonate (brine) solutions, and 3) precipitation during the process of cryogenic freezing of bicarbonate-rich fluids. Here we examine several terrestrial field settings within the context of kinetically controlled carbonate precipitation where stable isotope enrichments have been observed.

Sintering mantle mineral aggregates with submicron grains: examples of olivine and clinopyroxene

NASA Astrophysics Data System (ADS)

Tsubokawa, Y.; Ishikawa, M.

2017-12-01

Physical property of the major mantle minerals play an important role in the dynamic behavior of the Earth's mantle. Recently, it has been found that nano- to sub-micron scale frictional processes might control faulting processes and earthquake instability, and ultrafine-grained mineral aggregates thus have attracted the growing interest. Here we investigated a method for preparing polycrystalline clinoyproxene and polycrystalline olivine with grain size of sub-micron scale from natural crystals, two main constituents of the upper mantle. Nano-sized powders of both minerals are sintered under argon flow at temperatures ranging from 1130-1350 °C for 0.5-20 h. After sintering at 1180 °C and 1300 °C, we successfully fabricated polycrystalline clinopyroxene and polycrystalline olivine with grain size of < 500 nm, respectively. Our experiments demonstrate future measurements of ultrafine-grained mineral aggregates on its physical properties of Earth's mantle.

Propham mineralization in aqueous medium by anodic oxidation using boron-doped diamond anode: influence of experimental parameters on degradation kinetics and mineralization efficiency.

PubMed

Ozcan, Ali; Sahin, Yücel; Koparal, A Savaş; Oturan, Mehmet A

2008-06-01

This study aims the removal of a carbamate herbicide, propham, from aqueous solution by direct electrochemical advanced oxidation process using a boron-doped diamond (BDD) anode. This electrode produces large quantities of hydroxyl radicals from oxidation of water, which leads to the oxidative degradation of propham up to its total mineralization. Effect of operational parameters such as current, temperature, pH and supporting electrolyte on the degradation and mineralization rate was studied. The applied current and temperature exert a prominent effect on the total organic carbon (TOC) removal rate of the solutions. The mineralization of propham can be performed at any pH value between 3 and 11 without any loss in oxidation efficiency. The propham decay and its overall mineralization reaction follows a pseudo-first-order kinetics. The apparent rate constant value of propham oxidation was determined as 4.8 x 10(-4)s(-1) at 100 mA and 35 degrees C in the presence of 50mM Na(2)SO(4) in acidic media (pH: 3). A general mineralization sequence was proposed considering the identified oxidation intermediates.

Low Temperature Approach to Serpentinization Processes on Ocean Worlds

NASA Astrophysics Data System (ADS)

Neto-Lima, J.; Fernández-Sampedro, M.; Prieto-Ballesteros, O.

2018-05-01

MIR results from laboratory experiments at constant temperature of 90ºC. The monitoring of the mineral alterations is done in the presence of different amounts of a Fe-Ni catalyst (awaruite) and ammonia, using XRPD, IR, SEM-EDS, XPS,RAMAN and ICP-MS.

Development of Tc(IV)-Incorporated Fe Minerals to Enhance 99Tc Retention in Glass Waste Form

DOE Office of Scientific and Technical Information (OSTI.GOV)

Um, Wooyong; Luksic, Steven A.; Wang, Guohui

Iron minerals have been considered to be good hosts for Tc immobilization because the Tc(IV) ion substitutes for Fe(III) in the crystal structure of the Fe oxide due to similarities in (1) cation size [Tc(IV) = 78.5 pm ; Fe(III) = 69 or 78.5 pm], (2) metal-oxygen interatomic distance (Tc—O = 0.199 nm, Fe—O = 0.203 nm), (3) number of coordinating oxygen atoms (both 6-fold coordinated), and (4) the redox potential (Eh=ca. +20 mV at pH = 7) for a redox couple between Tc(VII)/Tc(IV) and Fe(III)/Fe(II). Magnetite, maghemite, and trevorite are iron oxide minerals and all belong to spinel mineralmore » group. Laboratory testing shows that Tc can be removed from aqueous waste solutions by a process of Tc reduction from Tc(VII) to Tc(IV) followed by co-precipitation with iron oxide minerals during recrystallization of Fe(OH)2(s) used as an initial solid precursor. X-ray absorption near edge structure (XANES) spectroscopy confirmed that Tc was in the +4 oxidation state in final Tc-Fe minerals. The Tc-incorporated Fe minerals were also tested for Tc retention in glass melts at different temperatures between 600 – 1,000 oC in a furnace. After being cooled in air, the solid glass specimens collected at different temperatures were analyzed for Tc oxidation state using XANES and Tc retention using liquid scintillation counting (LSC). Even though Tc(IV) started to reoxidize at 600 oC, Tc retention in the final glass specimen prepared with Tc-incorporated Fe mineral even at high temperatures was at least two times higher than glass prepared with KTcO4 salt. Higher Tc retention in glass is considered to result from limited and delayed Tc volatilization process due to Fe mineral encapsulation for Tc. Therefore, the results showing the presence of Tc(IV) in the Fe mineral structure indicate strong possibility to enhance Tc retention in borosilicate glass as well as to reduce the remediation costs at the Hanford Site.« less

What do we really know about the role of microorganisms in iron sulfide mineral formation?

USGS Publications Warehouse

Picard, Aude A.; Gartman, Amy; Girguis, Peter R.

2016-01-01

Iron sulfide mineralization in low-temperature systems is a result of biotic and abiotic processes, though the delineation between these two modes of formation is not always straightforward. Here we review the role of microorganisms in the precipitation of extracellular iron sulfide minerals. We summarize the evidence that links sulfur-metabolizing microorganisms and sulfide minerals in nature and we present a critical overview of laboratory-based studies of the nucleation and growth of iron sulfide minerals in microbial cultures. We discuss whether biologically derived minerals are distinguishable from abiotic minerals, possessing attributes that are uniquely diagnostic of biomineralization. These inquiries have revealed the need for additional thorough, mechanistic and high-resolution studies to understand microbially mediated formation of a variety of sulfide minerals across a range of natural environments.

Influence of ignition process on mineral phase transformation in municipal solid waste incineration (MSWI) fly ash: Implications for estimating loss-on-ignition (LOI).

PubMed

Mu, Yue; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki

2017-01-01

This research focused on the mineral phase transformation under varied ignition conditions with the objective of estimating loss-on-ignition (LOI) parameter in municipal solid waste incineration (MSWI) fly ash residues. LOI is commonly used to measure the volatile species, unburned carbon and moisture in the solid materials. There are criteria for LOI measurement in some research fields, while there is no standard protocol for LOI measurement in MSWI fly ash. Using thermogravimetry technique, the ignition condition candidates were proposed at 440/700/900°C for 1 and 2h. Based on X-ray diffractometry results, obvious mineral phase transformation occurred as a function of ignition temperature variation rather than ignition time. Until 440°C, only some minor phases disappeared comparing with the original state. Significant mineral phase transformations of major phases (Ca- and Cl-based minerals) occurred between 440 and 700°C. The mineral phase transformation and the occurrence of newly-formed phases were determined not only by the ignition condition but also by the content of the co-existing components. Mineral phase components rarely changed when ignition temperature rose from 700 to 900°C. Consequently, in order to prevent critical damages to the original mineralogical composition of fly ash, the lowest ignition temperature (440°C) for 2h was suggested as an ideal measurement condition of LOI in MSWI fly ash. Copyright © 2016 Elsevier Ltd. All rights reserved.

Process-based modeling of silicate mineral weathering responses to increasing atmospheric CO2 and climate change

NASA Astrophysics Data System (ADS)

Banwart, Steven A.; Berg, Astrid; Beerling, David J.

2009-12-01

A mathematical model describes silicate mineral weathering processes in modern soils located in the boreal coniferous region of northern Europe. The process model results demonstrate a stabilizing biological feedback mechanism between atmospheric CO2 levels and silicate weathering rates as is generally postulated for atmospheric evolution. The process model feedback response agrees within a factor of 2 of that calculated by a weathering feedback function of the type generally employed in global geochemical carbon cycle models of the Earth's Phanerozoic CO2 history. Sensitivity analysis of parameter values in the process model provides insight into the key mechanisms that influence the strength of the biological feedback to weathering. First, the process model accounts for the alkalinity released by weathering, whereby its acceleration stabilizes pH at values that are higher than expected. Although the process model yields faster weathering with increasing temperature, because of activation energy effects on mineral dissolution kinetics at warmer temperature, the mineral dissolution rate laws utilized in the process model also result in lower dissolution rates at higher pH values. Hence, as dissolution rates increase under warmer conditions, more alkalinity is released by the weathering reaction, helping maintain higher pH values thus stabilizing the weathering rate. Second, the process model yields a relatively low sensitivity of soil pH to increasing plant productivity. This is due to more rapid decomposition of dissolved organic carbon (DOC) under warmer conditions. Because DOC fluxes strongly influence the soil water proton balance and pH, this increased decomposition rate dampens the feedback between productivity and weathering. The process model is most sensitive to parameters reflecting soil structure; depth, porosity, and water content. This suggests that the role of biota to influence these characteristics of the weathering profile is as important, if not more important, than the role of biota to influence mineral dissolution rates through changes in soil water chemistry. This process-modeling approach to quantify the biological weathering feedback to atmospheric CO2 demonstrates the potential for a far more mechanistic description of weathering feedback in simulations of the global geochemical carbon cycle.

Thermodynamic constraints on hydrogen generation during serpentinization of ultramafic rocks

NASA Astrophysics Data System (ADS)

McCollom, Thomas M.; Bach, Wolfgang

2009-02-01

In recent years, serpentinized ultramafic rocks have received considerable attention as a source of H 2 for hydrogen-based microbial communities and as a potential environment for the abiotic synthesis of methane and other hydrocarbons within the Earth's crust. Both of these processes rely on the development of strongly reducing conditions and the generation of H 2 during serpentinization, which principally results from reaction of water with ferrous iron-rich minerals contained in ultramafic rocks. In this report, numerical models are used to investigate the potential influence of chemical thermodynamics on H 2 production during serpentinization. The results suggest that thermodynamic constraints on mineral stability and on the distribution of Fe among mineral alteration products as a function of temperature are likely to be major factors controlling the extent of H 2 production. At high temperatures (>˜315 °C), rates of serpentinization reactions are fast, but H 2 concentrations may be limited by the attainment of stable thermodynamic equilibrium between olivine and the aqueous fluid. Conversely, at temperatures below ˜150 °C, H 2 generation is severely limited both by slow reaction kinetics and partitioning of Fe(II) into brucite. At 35 MPa, peak temperatures for H 2 production occur at 200-315 °C, indicating that the most strongly reducing conditions will be attained during alteration within this temperature range. Fluids interacting with peridotite in this temperature range are likely to be the most productive sources of H 2 for biology, and should also produce the most favorable environments for abiotic organic synthesis. The results also suggest that thermodynamic constraints on Fe distribution among mineral alteration products have significant implications for the timing of magnetization of the ocean crust, and for the occurrence of native metal alloys and other trace minerals during serpentinization.

Pre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics.

PubMed

Petrone, Chiara Maria; Bugatti, Giuseppe; Braschi, Eleonora; Tommasini, Simone

2016-10-05

Constraining the timescales of pre-eruptive magmatic processes in active volcanic systems is paramount to understand magma chamber dynamics and the triggers for volcanic eruptions. Temporal information of magmatic processes is locked within the chemical zoning profiles of crystals but can be accessed by means of elemental diffusion chronometry. Mineral compositional zoning testifies to the occurrence of substantial temperature differences within magma chambers, which often bias the estimated timescales in the case of multi-stage zoned minerals. Here we propose a new Non-Isothermal Diffusion Incremental Step model to take into account the non-isothermal nature of pre-eruptive processes, deconstructing the main core-rim diffusion profiles of multi-zoned crystals into different isothermal steps. The Non-Isothermal Diffusion Incremental Step model represents a significant improvement in the reconstruction of crystal lifetime histories. Unravelling stepwise timescales at contrasting temperatures provides a novel approach to constraining pre-eruptive magmatic processes and greatly increases our understanding of magma chamber dynamics.

Pre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics

PubMed Central

Petrone, Chiara Maria; Bugatti, Giuseppe; Braschi, Eleonora; Tommasini, Simone

2016-01-01

Constraining the timescales of pre-eruptive magmatic processes in active volcanic systems is paramount to understand magma chamber dynamics and the triggers for volcanic eruptions. Temporal information of magmatic processes is locked within the chemical zoning profiles of crystals but can be accessed by means of elemental diffusion chronometry. Mineral compositional zoning testifies to the occurrence of substantial temperature differences within magma chambers, which often bias the estimated timescales in the case of multi-stage zoned minerals. Here we propose a new Non-Isothermal Diffusion Incremental Step model to take into account the non-isothermal nature of pre-eruptive processes, deconstructing the main core-rim diffusion profiles of multi-zoned crystals into different isothermal steps. The Non-Isothermal Diffusion Incremental Step model represents a significant improvement in the reconstruction of crystal lifetime histories. Unravelling stepwise timescales at contrasting temperatures provides a novel approach to constraining pre-eruptive magmatic processes and greatly increases our understanding of magma chamber dynamics. PMID:27703141

Quantification of Cation Sorption to Engineered Barrier Materials Under Extreme Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, Brian; Schlautman, Mark; Rao, Linfeng

The objective of this research is to examine mechanisms and thermodynamics of actinide sorption to engineered barrier materials (iron (oxyhydr)oxides and bentonite clay) for nuclear waste repositories under high temperature and high ionic strength conditions using a suite of macroscopic and microscopic techniques which will be coupled with interfacial reaction models. Gaining a mechanistic understanding of interfacial processes governing the sorption/sequestration of actinides at mineral-water interfaces is fundamental for the accurate prediction of actinide behavior in waste repositories. Although macroscale sorption data and various spectroscopic techniques have provided valuable information regarding speciation of actinides at solid-water interfaces, significant knowledge gapsmore » still exist with respect to sorption mechanisms and the ability to quantify sorption, particularly at high temperatures and ionic strengths. This objective is addressed through three major tasks: (1) influence of oxidation state on actinide sorption to iron oxides and clay minerals at elevated temperatures and ionic strengths; (2) calorimetric titrations of actinide-mineral suspensions; (3) evaluation of bentonite performance under repository conditions. The results of the work will include a qualitative conceptual model and a quantitative thermodynamic speciation model describing actinide partitioning to minerals and sediments, which is based upon a mechanistic understanding of specific sorption processes as determined from both micro-scale and macroscale experimental techniques. The speciation model will be a thermodynamic aqueous and surface complexation model of actinide interactions with mineral surfaces that is self-consistent with macroscopic batch sorption data, calorimetric and potentiometric titrations, X-ray absorption Spectroscopy (XAS, mainly Extended X-ray Absorption Fine Structure (EXAFS)), and electron microscopy analyses. The novelty of the proposed work lies largely in the unique system conditions which will be examined (i.e. elevated temperature and ionic strength) and the manner in which the surface complexation model will be developed in terms of specific surface species identified using XAS. These experiments will thus provide a fundamental understanding of the chemical and physical processes occurring at the solid-solution interface under expected repository conditions. Additionally, the focus on thermodynamic treatment of actinide ion interactions with minerals as proposed will provide information on the driving forces involved and contribute to the overall understanding of the high affinity many actinide ions have for oxide surfaces. The utility of this model will be demonstrated in this work through a series of advective and diffusive flow experiments.« less

Mg isotope systematics during magmatic processes: Inter-mineral fractionation in mafic to ultramafic Hawaiian xenoliths

NASA Astrophysics Data System (ADS)

Stracke, A.; Tipper, E. T.; Klemme, S.; Bizimis, M.

2018-04-01

Observed differences in Mg isotope ratios between bulk magmatic rocks are small, often on a sub per mill level. Inter-mineral differences in the 26Mg/24Mg ratio (expressed as δ26Mg) in plutonic rocks are on a similar scale, and have mostly been attributed to equilibrium isotope fractionation at magmatic temperatures. Here we report Mg isotope data on minerals in spinel peridotite and garnet pyroxenite xenoliths from the rejuvenated stage of volcanism on Oahu and Kauai, Hawaii. The new data are compared to literature data and to theoretical predictions to investigate the processes responsible for inter-mineral Mg isotope fractionation at magmatic temperatures. Theory predicts up to per mill level differences in δ26Mg between olivine and spinel at magmatic temperatures and a general decrease in Δ26Mgolivine-spinel (=δ26Mgolivine - δ26Mgspinel) with increasing temperature, but also with increasing Cr# in spinel. For peridotites with a simple petrogenetic history by melt depletion, where increasing depletion relates to increasing melting temperatures, Δ26Mgolivine-spinel should thus systematically decrease with increasing Cr# in spinel. However, most natural peridotites, including the Hawaiian spinel peridotites investigated in this study, are overprinted by variable extents of melt-rock reaction, which disturb the systematic primary temperature and compositionally related olivine-spinel Mg isotope systematics. Diffusion, subsolidus re-equilibration, or surface alteration may further affect the observed olivine-spinel Mg isotope fractionation in peridotites, making Δ26Mgolivine-spinel in peridotites a difficult-to-apply geothermometer. The available Mg isotope data on clinopyroxene and garnet suggest that this mineral pair is a more promising geothermometer, but its application is restricted to garnet-bearing igneous (garnet pyroxenites) and metamorphic rocks (eclogites). Although the observed δ26Mg variation is on a sub per mill range in bulk magmatic rocks, the clearly resolvable inter-mineral Mg isotope differences imply that crystallization or preferential melting of isotopically distinct minerals such garnet, spinel, and clinopyroxene should cause Mg isotope fractionation between bulk melt and residue. Calculated Mg isotope variations during partial mantle melting indeed predict differences between melt and residue, but these are analytically resolvable only for melting of mafic lithologies, that is, garnet pyroxenites. Contributions from garnet pyroxenite melts may thus account for some of the isotopically light δ26Mg observed in ocean island basalts and trace lithological mantle heterogeneity. Consequently, applications for high-temperature Mg isotope fractionations are promising and diverse, and recent advances in analytical precision may allow the full petrogenetic potential inherent in the sub per mill variations in δ26Mg in magmatic rocks to be exploited.

An approach to modeling coupled thermal-hydraulic-chemical processes in geothermal systems

USGS Publications Warehouse

Palguta, Jennifer; Williams, Colin F.; Ingebritsen, Steven E.; Hickman, Stephen H.; Sonnenthal, Eric

2011-01-01

Interactions between hydrothermal fluids and rock alter mineralogy, leading to the formation of secondary minerals and potentially significant physical and chemical property changes. Reactive transport simulations are essential for evaluating the coupled processes controlling the geochemical, thermal and hydrological evolution of geothermal systems. The objective of this preliminary investigation is to successfully replicate observations from a series of hydrothermal laboratory experiments [Morrow et al., 2001] using the code TOUGHREACT. The laboratory experiments carried out by Morrow et al. [2001] measure permeability reduction in fractured and intact Westerly granite due to high-temperature fluid flow through core samples. Initial permeability and temperature values used in our simulations reflect these experimental conditions and range from 6.13 × 10−20 to 1.5 × 10−17 m2 and 150 to 300 °C, respectively. The primary mineralogy of the model rock is plagioclase (40 vol.%), K-feldspar (20 vol.%), quartz (30 vol.%), and biotite (10 vol.%). The simulations are constrained by the requirement that permeability, relative mineral abundances, and fluid chemistry agree with experimental observations. In the models, the granite core samples are represented as one-dimensional reaction domains. We find that the mineral abundances, solute concentrations, and permeability evolutions predicted by the models are consistent with those observed in the experiments carried out by Morrow et al. [2001] only if the mineral reactive surface areas decrease with increasing clay mineral abundance. This modeling approach suggests the importance of explicitly incorporating changing mineral surface areas into reactive transport models.

Soil Surface Organic Layers in Alaska's Arctic Foothills: Development, Distribution and Microclimatic Feedbacks

NASA Astrophysics Data System (ADS)

Baughman, C. A.; Mann, D. H.; Verbyla, D.; Valentine, D.; Kunz, M. L.; Heiser, P. A.

2013-12-01

Accumulated organic matter at the ground surface plays an important role in arctic ecosystems. These soil surface organic layers (SSOLs) influence temperature, moisture, and chemistry in the underlying mineral soil and, on a global basis, comprise enormous stores of labile carbon. Understanding the dynamics of SSOLs is prerequisite to modeling the responses of arctic ecosystem processes to climate changes. Here, we ask three questions regarding SSOLs in the Arctic Foothills in northern Alaska: 1) What environmental factors control their spatial distribution? 2) How long do they take to form? 3) What is the relationship between SSOL thickness and mineral soil temperature through the growing season? The best topographically-controlled predictors of SSOL thickness and spatial distribution are duration of sunlight during the growing-season, upslope drainage area, slope gradient, and elevation. SSOLs begin to form within several decades following disturbance but require 500-700 years to reach equilibrium states. Once formed, mature SSOLs lower peak growing-season temperature and mean annual temperature in the underlying mineral horizon by 8° and 3° C respectively, which reduces available growing degree days within the upper mineral soil by nearly 80%. How ongoing climate change in northern Alaska will affect the region's SSOLs is an open and potentially crucial question.

Application of an adsorptive-thermocatalytic process for BTX removal from polluted air flow

PubMed Central

2014-01-01

Background Zero valent iron and copper oxide nanoparticles (30-60 nm) were coated on a bed of natural zeolite (Clinoptilolite) with 1-2 mm grains and arranged as a dual filter in a stainless steel cylindrical reactor (I.D 4.5 cm and L = 30 cm) to investigating the coated bed removal efficiency for BTX. The experiments were conducted in three steps. First, with an air flow of 1.5 L/min and temperature range of 38 (ambient temperature) to 600°C the BTX removal and mineralization was surveyed. Then, in an optimized temperature the effect of flow rate and pollution loading rate were surveyed on BTX removal. Results The BTX removal at 300 and 400°C were respectively up to 87.47% and 94.03%. Also in these temperatures respectively 37.21% and 90.42% of BTX mineralization were achieved. In the retention times of 14.1 s and 7.05 s, respectively 96.18% and 78.42% of BTX was removed. Conclusions According to the results, this adsorptive-thermocatalytic process with using Clinoptilolite as an adsorbent bed and combined Fe0 and Cu2O nanoparticles as catalysts can be an efficient and competitive process in the condition of high flow rate and high pollution loading rate with an adequate process temperature of 350°C. PMID:24955244

Damage characteristics and thermo-physical properties changes of limestone and sandstone during thermal treatment from -30 °C to 1000 °C

NASA Astrophysics Data System (ADS)

Shen, Yanjun; Yang, Yang; Yang, Gengshe; Hou, Xin; Ye, Wanjun; You, Zhemin; Xi, Jiami

2018-05-01

A series of experiments were carried out to measure the damage characteristics of two common sedimentary rocks of limestone and sandstone at temperatures ranging from -30 °C to 1000 °C The apparent thermal conductivity, thermal diffusivity and specific heat capacity were investigated respectively. Then, several discrepancy reasons for the damage characteristics and thermo-physical properties of limestone and sandstone were probed. The results show that water migration and phase transition are two core factors for the frost damage and thermal behaviors improvement during the cooling process(20 °C → -30 °C).The heating process (20 °C → 1000 °C) was divided into three stages of 20 °C → 200 °C, 200 °C → 600 °Cand 600 °C → 1000 °C. The first stage was closely related to pore-water evaporation, and the next two stages were attributed to the thermal reactions of mineral partials. The mineral decomposition tended to be intensified and resulted in the interior damage or even the accelerated degradation of thermal properties until at a threshold temperature of 600 °C. In essential, the structural features and the sensitivity of mineral composition to temperature were two mainly influential factors on the damage effects and heat conduct of the sedimentary rocks during variations in environmental temperature.

Use of MAGSAT anomaly data for crustal structure and mineral resources in the US midcontinent

NASA Technical Reports Server (NTRS)

Carmichael, R. S. (Principal Investigator); Black, R.

1982-01-01

Activities concerning the interpretation of processed MAGSAT data and maps are briefly reported. Work involving the identification of long wavelength 'regional' effects that might be associated with varying crustal thickness or Curie temperature depths is processing.

Thermal Alteration of Pyrite to Pyrrhotite During Earthquakes: New Evidence of Seismic Slip in the Rock Record

NASA Astrophysics Data System (ADS)

Yang, Tao; Dekkers, Mark J.; Chen, Jianye

2018-02-01

Seismic slip zones convey important information on earthquake energy dissipation and rupture processes. However, geological records of earthquakes along exhumed faults remain scarce. They can be traced with a variety of methods that establish the frictional heating of seismic slip, although each has certain assets and disadvantages. Here we describe a mineral magnetic method to identify seismic slip along with its peak temperature through examination of magnetic mineral assemblages within a fault zone in deep-sea sediments cored from the Japan Trench—one of the seismically most active regions around Japan—during the Integrated Ocean Drilling Program Expedition 343, the Japan Trench Fast Drilling Project. Fault zone sediments and adjacent host sediments were analyzed mineral magnetically, supplemented by scanning electron microscope observations with associated energy dispersive X-ray spectroscopy analyses. The presence of the magnetic mineral pyrrhotite appears to be restricted to three fault zones occurring at 697, 720, and 801 m below sea floor in the frontal prism sediments, while it is absent in the adjacent host sediments. Elevated temperatures and coseismic hot fluids as a consequence of frictional heating during earthquake rupture induced partial reaction of preexisting pyrite to pyrrhotite. The presence of pyrrhotite in combination with pyrite-to-pyrrhotite reaction kinetics constrains the peak temperature to between 640 and 800°C. The integrated mineral-magnetic, microscopic, and kinetic approach adopted here is a useful tool to identify seismic slip along faults without frictional melt and establish the associated maximum temperature.

Weaker soil carbon-climate feedbacks resulting from microbial and abiotic interactions

NASA Astrophysics Data System (ADS)

Tang, Jinyun; Riley, William J.

2015-01-01

The large uncertainty in soil carbon-climate feedback predictions has been attributed to the incorrect parameterization of decomposition temperature sensitivity (Q10; ref. ) and microbial carbon use efficiency. Empirical experiments have found that these parameters vary spatiotemporally, but such variability is not included in current ecosystem models. Here we use a thermodynamically based decomposition model to test the hypothesis that this observed variability arises from interactions between temperature, microbial biogeochemistry, and mineral surface sorptive reactions. We show that because mineral surfaces interact with substrates, enzymes and microbes, both Q10 and microbial carbon use efficiency are hysteretic (so that neither can be represented by a single static function) and the conventional labile and recalcitrant substrate characterization with static temperature sensitivity is flawed. In a 4-K temperature perturbation experiment, our fully dynamic model predicted more variable but weaker soil carbon-climate feedbacks than did the static Q10 and static carbon use efficiency model when forced with yearly, daily and hourly variable temperatures. These results imply that current Earth system models probably overestimate the response of soil carbon stocks to global warming. Future ecosystem models should therefore consider the dynamic interactions between sorptive mineral surfaces, substrates and microbial processes.

Mineral resource of the month: perlite

USGS Publications Warehouse

Bolen, Wallace

2003-01-01

Perlite is found in most homes, workplaces and schools. Most of the white ceiling tiles in offices and classrooms are made primarily of perlite. The soil around potted plants also has small white grains of perlite. Other than in these lightweight construction products and horticultural soil mixes, perlite is used in food processing for filtration and in natural gas processing as a low-temperature insulation that aids the gas liquefaction process. Perlite is also an excellent high temperature insulator and resists burning.

Studies of Quaternary saline lakes-III. Mineral, chemical, and isotopic evidence of salt solution and crystallization processes in Owens Lake, California, 1969-1971

USGS Publications Warehouse

Smith, G.I.; Friedman, I.; McLaughlin, R.J.

1987-01-01

As a consequence of the 1969-1970 flooding of normally dry Owens Lake, a 2.4-m-deep lake formed and 20% of the 2-m-thick salt bed dissolved in it. Its desiccation began August 1969, and salts started crystallizing September 1970, ending August 1971. Mineralogic, brine-composition, and stable-isotope data plus field observations showed that while the evolving brine composition established the general crystallization timetable and range of primary and secondary mineral assemblages, it was the daily, monthly, and seasonal temperature changes that controlled the details of timing and mineralogy during this depositional process. Deuterium analyses of lake brine, interstitial brine, and hydrated saline phases helped confirm the sequence of mineral crystallizations and transformations, and they documented the sources and temperatures of waters involved in the reactions. Salts first crystallized as floating rafts on the lake surface. Natron and mirabilite, salts whose solubilities decrease greatly with lowering temperatures, crystallized late at night in winter, when surface-water temperatures reached their minima; trona, nahcolite, burkeite, and halite, salts with solubilities less sensitive to temperature, crystallized during the afternoon in summer, when surface salinities reached their maxima. However, different temperatures were generally associated with crystallization (at the surface) and accumulation (on the lake floor) because short-term temperature changes were transmitted to surface and bottom waters at different rates. Consequently, even when solubilities were exceeded at the surface, salts were preserved or not as a function of bottom-water temperatures. Halite, a nearly temperature-insensitive salt, was always preserved. Monitoring the lake-brine chemistry and mineralogy of the accumulating salts shows: (1) An estimated 0.9 ?? 106 tons of CO2 was released to the atmosphere or consumed by the lake's biomass prior to most salt crystallization. (2) After deposition, some salts reacted in situ to form other minerals in less than one month, and all salts (except halite) decomposed or recrystallized at least once in response to seasons. (3) Warming in early 1971 caused solution of all the mirabilite and some of the natron deposited a few months earlier, a deepening of the lake (though the lake-surface lowered), and an increase in dissolved solids. (4) Phase and solubility-index data suggest that at the close of desiccation, Na2CO3??7H2O, never reported as a mineral, could have been the next phase to crystallize. ?? 1987.

Aerobic and anaerobic degradation and mineralization of 14C-chitin by water column and sediment inocula of the York River estuary, Virginia.

PubMed Central

Boyer, J N

1994-01-01

Potential rates of chitin degradation (Cd) and mineralization (Cm) by estuarine water and sediment bacteria were measured as a function of inoculum source, temperature, and oxygen condition. In the water column inoculum, 88 to 93% of the particulate chitin was mineralized to CO2 with no apparent lag between degradation and mineralization. No measurable dissolved pool of radiolabel was found in the water column. For the sediment inocula, 70 to 90% of the chitin was degraded while only 55 to 65% was mineralized to CO2. 14C label recoveries in the dissolved pool were 19 to 21% for sand, 17 to 24% in aerobic mud, and 12 to 21% for the anaerobic mud. This uncoupling between degradation and mineralization occurred in all sediment inocula. More than 98% of the initial 14C-chitin was recovered in the three measured fractions. The highest Cd and Cm values, 30 and 27% day-1, occurred in the water column inoculum at 25 degrees C. The lowest Cd and Cm values were found in the aerobic and anaerobic mud inocula incubated at 15 degrees C. Significant differences in Cd and Cm values among water column and sediment inocula as well as between temperature treatments were evident. An increased incubation temperature resulted in shorter lag times before the onset of chitinoclastic bacterial growth, degradation, and mineralization and resulted in apparent Q10 values of 1.1 for water and 1.3 to 2.1 for sediment inocula. It is clear that chitin degradation and mineralization occur rapidly in the estuary and that water column bacteria may be more important in this process than previously acknowledged. PMID:8117075

Stable isotope and mineralogical investigation of the genesis of amethyst geodes in the Los Catalanes gemological district, Uruguay, southernmost Paraná volcanic province

NASA Astrophysics Data System (ADS)

Duarte, Lauren C.; Hartmann, Leo A.; Ronchi, Luiz H.; Berner, Zsolt; Theye, Thomas; Massonne, Hans J.

2011-03-01

Stable isotopes (C, O, S) and mineralogical studies of the world-class amethyst-geode deposits of the Los Catalanes gemological district, Uruguay, constrain processes operative during mineral deposition. The mineralized basaltic andesites from the Cretaceous Paraná volcanic province are intensely altered to zeolites (clinoptilolite) and clay minerals. Variations in the δ18O values of silica minerals in geodes (chalcedony, quartz, and amethyst) are much larger and the values generally somewhat lower (21.2-31.5‰) in the Uruguayan deposits than in the Ametista do Sul area of southern Brazil. The range of δ34S values (-15.0 to -0.3‰) of altered basaltic rocks requires (in addition to sulfur of magmatic origin) the involvement of 34S-depleted sedimentary sulfur from bacterial sulfate reduction. The results delimit the mineralizing processes to a post-eruption environment characterized by low temperature and strong interaction of the lava flows with meteoric water.

An isotopic investigation of the temperature response of young and old soil organic matter respiration

NASA Astrophysics Data System (ADS)

Burns, Nancy; Cloy, Joanna; Garnett, Mark; Reay, David; Smith, Keith; Otten, Wilfred

2010-05-01

The effect of temperature on rates of soil respiration is critical to our understanding of the terrestrial carbon cycle and potential feedbacks to climate change. The relative temperature sensitivity of labile and recalcitrant soil organic matter (SOM) is still controversial; different studies have produced contrasting results, indicating limited understanding of the underlying relationships between stabilisation processes and temperature. Current global carbon cycle models still rely on the assumption that SOM pools with different decay rates have the same temperature response, yet small differences in temperature response between pools could lead to very different climate feedbacks. This study examined the temperature response of soil respiration and the age of soil carbon respired from radiocarbon dated fractions of SOM (free, intra-aggregate and mineral-bound) and whole soils (organic and mineral layers). Samples were collected from a peaty gley soil from Harwood Forest, Northumberland, UK. SOM fractions were isolated from organic layer (5 - 17 cm) material using high density flotation and ultrasonic disaggregation - designated as free (< 1.8 g cm-3), intra-aggregate (< 1.8 g cm-3 within aggregates > 1.8 g cm-3) and mineral-bound (> 1.8 g cm-3) SOM. Fractions were analysed for chemical composition (FTIR, CHN analysis, ICP-OES), 14C (AMS), δ13C and δ15N (MS) and thermal properties (DSC). SOM fractions and bulk soil from the organic layer and the mineral layer (20 - 30 cm) were incubated in sealed vessels at 30 ° C and 10 ° C for 3 or 9 months to allow accumulation of CO2 sufficient for sampling. Accumulated respired CO2 samples were collected on zeolite molecular sieve cartridges and used for AMS radiocarbon dating. In parallel, material from the same fractions and layers were incubated at 10 ° C, 15 ° C, 25 ° C and 30 ° C for 6 months and sampled weekly for CO2 flux measurements using GC chromatography. Initial data have shown radiocarbon ages ranging from modern to 219 y BP in bulk soil from the organic layer (5 - 17 cm depth), while free OM ranged from modern to 74 y BP, intra-aggregate OM 413 - 657 y BP and mineral-bound material 562 - 646 y BP. Bulk soil from the mineral layer (20 - 30 cm) was considerably older, at 2142 - 2216 y BP. These results indicate that within the upper layer of soil, mineral-bound OM represents a slow-cycling or recalcitrant pool of SOM; intra-aggregate OM is slightly less recalcitrant than mineral-bound OM, while free OM represents a fast-cycling, labile pool of SOM. Bulk soil from the mineral layer (20 - 30 cm) is much older than mineral-bound OM in the upper layers, suggesting the involvement of other stabilising factors associated with depth besides mineral interactions. The link between age and recalcitrance is corroborated by measured CO2 flux rates, which increase with decreasing age of fractions. Results for the 14C contents and calculated ages of isolated SOM fractions, bulk organic and mineral soils and their respired CO2 at different temperatures will be discussed and compared with long term trends in soil/SOM fraction CO2 fluxes and their temperature sensitivity. Data on soil chemical characteristics and δ13C values will also be presented.

Externally controlled pressure and temperature microreactor for in situ x-ray diffraction, visual and spectroscopic reaction investigations under supercritical and subcritical conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diefenbacher, Jason; McKelvy, Michael; Chizmeshya, Andrew V.G.

2005-01-01

A microreactor has been developed for in situ, spectroscopic investigations of materials and reaction processes with full external pressure and temperature control from ambient conditions to 400 deg. C and 310 bar. The sample chamber is in direct contact with an external manifold, whereby gases, liquids or fluids can be injected and their activities controlled prior to and under investigation conditions. The microreactor employs high strength, single crystal moissanite windows which allow direct probe beam interaction with a sample to investigate in situ reaction processes and other materials properties. The relatively large volume of the cell, along with full opticalmore » accessibility and external temperature and pressure control, make this reaction cell well suited for experimental investigations involving any combination of gas, fluid, and solid interactions. The microreactor's capabilities are demonstrated through an in situ x-ray diffraction study of the conversion of a meta-serpentine sample to magnesite under high pressure and temperature. Serpentine is one of the mineral candidates for the implementation of mineral carbonation, an intriguing carbon sequestration candidate technology.« less

Externally controlled pressure and temperature microreactor for in situ x-ray diffraction, visual and spectroscopic reaction investigations under supercritical and subcritial conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diefenbacher, J.; McKelvy, M.; Chizemeshya, A.V.

2010-07-13

A microreactor has been developed for in situ, spectroscopic investigations of materials and reaction processes with full external pressure and temperature control from ambient conditions to 400 C and 310 bar. The sample chamber is in direct contact with an external manifold, whereby gases, liquids or fluids can be injected and their activities controlled prior to and under investigation conditions. The microreactor employs high strength, single crystal moissanite windows which allow direct probe beam interaction with a sample to investigate in situ reaction processes and other materials properties. The relatively large volume of the cell, along with full optical accessibilitymore » and external temperature and pressure control, make this reaction cell well suited for experimental investigations involving any combination of gas, fluid, and solid interactions. The microreactor's capabilities are demonstrated through an in situ x-ray diffraction study of the conversion of a meta-serpentine sample to magnesite under high pressure and temperature. Serpentine is one of the mineral candidates for the implementation of mineral carbonation, an intriguing carbon sequestration candidate technology.« less

Mineral Composition and Abundance of the Rocks and Soils at Gusev and Meridiani from the Mars Exploration Rover Mini-TES Instruments

NASA Technical Reports Server (NTRS)

Christensen, P. R.; Wyatt, M. B.; Glotch, T. D.; Rogers, A. D.; Anwar, S.; Arvidson, R. E.; Bandfield, J. L.; Blaney, D. L.; Budney, C.; Calvin, W. M.

2005-01-01

The Miniature Thermal Emission Spectrometer (Mini-TES) has provided remote measurements of mineralogy, thermophysical properties, and atmospheric temperature profile and composition of the outcrops, rocks, spherules, and soils surrounding the Spirit and Opportunity Rovers. The mineralogy of volcanic rocks provides insights into the composition of the source regions and the nature of martian igneous processes. Carbonates, sulfates, evaporites, and oxides provide information on the role of water in the surface evolution. Oxides, such as crystalline hematite, provide insight into aqueous weathering processes, as would the occurrence of clay minerals and other weathering products. Diurnal temperature measurements can be used to determine particle size and search for the effects of sub-surface layering, which in turn provide clues to the origin of surficial materials through rock disintegration, aeolian transport, atmospheric fallout, or induration. In addition to studying the surface properties, Mini-TES spectra have also been used to determine the temperature profile in the lower boundary layer, providing evidence for convective activity, and have determined the seasonal trends in atmospheric temperature and dust and cloud opacity.

Solvent extraction of gold using ionic liquid based process

NASA Astrophysics Data System (ADS)

Makertihartha, I. G. B. N.; Zunita, Megawati; Rizki, Z.; Dharmawijaya, P. T.

2017-01-01

In decades, many research and mineral processing industries are using solvent extraction technology for metal ions separation. Solvent extraction technique has been used for the purification of precious metals such as Au and Pd, and base metals such as Cu, Zn and Cd. This process uses organic compounds as solvent. Organic solvents have some undesired properties i.e. toxic, volatile, excessive used, flammable, difficult to recycle, low reusability, low Au recovery, together with the problems related to the disposal of spent extractants and diluents, even the costs associated with these processes are relatively expensive. Therefore, a lot of research have boosted into the development of safe and environmentally friendly process for Au separation. Ionic liquids (ILs) are the potential alternative for gold extraction because they possess several desirable properties, such as a the ability to expanse temperature process up to 300°C, good solvent properties for a wide range of metal ions, high selectivity, low vapor pressures, stability up to 200°C, easy preparation, environmentally friendly (commonly called as "green solvent"), and relatively low cost. This review paper is focused in investigate of some ILs that have the potentials as solvent in extraction of Au from mineral/metal alloy at various conditions (pH, temperature, and pressure). Performances of ILs extraction of Au are studied in depth, i.e. structural relationship of ILs with capability to separate Au from metal ions aggregate. Optimal extraction conditon in order to gain high percent of Au in mineral processing is also investigated.

Optical luminescence studies of the ethyl xanthate adsorption layer on the surface of sphalerite minerals.

PubMed

Todoran, R; Todoran, D; Szakács, Zs

2016-01-05

In this work we propose optical luminescence measurements as a method to evaluate the kinetics of adsorption processes. Measurement of the intensity of the integral optical radiation obtained from the mineral-xanthate interface layer, stimulated with a monochromatic pulsating optical signal, as a function of time were made. The luminescence radiation was obtained from the thin interface layer formed at the separation surface between the sphalerite natural mineral and potassium ethyl xanthate solution, for different solution concentrations and pH-es at the constant industry standard temperature. This method enabled us to determine the time to achieve dynamic equilibrium in the formation of the interface layer of approximately 20min, gaining information on the adsorption kinetics in the case of xanthate on mineral surface and leading to the optimization of the industrial froth flotation process. Copyright © 2015 Elsevier B.V. All rights reserved.

Mineral Carbonation Potential of CO2 from Natural and Industrial-based Alkalinity Sources

NASA Astrophysics Data System (ADS)

Wilcox, J.; Kirchofer, A.

2014-12-01

Mineral carbonation is a Carbon Capture and Storage (CSS) technology where gaseous CO2 is reacted with alkaline materials (such as silicate minerals and alkaline industrial wastes) and converted into stable and environmentally benign carbonate minerals (Metz et al., 2005). Here, we present a holistic, transparent life cycle assessment model of aqueous mineral carbonation built using a hybrid process model and economic input-output life cycle assessment approach. We compared the energy efficiency and the net CO2 storage potential of various mineral carbonation processes based on different feedstock material and process schemes on a consistent basis by determining the energy and material balance of each implementation (Kirchofer et al., 2011). In particular, we evaluated the net CO2 storage potential of aqueous mineral carbonation for serpentine, olivine, cement kiln dust, fly ash, and steel slag across a range of reaction conditions and process parameters. A preliminary systematic investigation of the tradeoffs inherent in mineral carbonation processes was conducted and guidelines for the optimization of the life-cycle energy efficiency are provided. The life-cycle assessment of aqueous mineral carbonation suggests that a variety of alkalinity sources and process configurations are capable of net CO2 reductions. The maximum carbonation efficiency, defined as mass percent of CO2 mitigated per CO2 input, was 83% for CKD at ambient temperature and pressure conditions. In order of decreasing efficiency, the maximum carbonation efficiencies for the other alkalinity sources investigated were: olivine, 66%; SS, 64%; FA, 36%; and serpentine, 13%. For natural alkalinity sources, availability is estimated based on U.S. production rates of a) lime (18 Mt/yr) or b) sand and gravel (760 Mt/yr) (USGS, 2011). The low estimate assumes the maximum sequestration efficiency of the alkalinity source obtained in the current work and the high estimate assumes a sequestration efficiency of 85%. The total CO2 storage potential for the alkalinity sources considered in the U.S. ranges from 1.3% to 23.7% of U.S. CO2 emissions, depending on the assumed availability of natural alkalinity sources and efficiency of the mineral carbonation processes.

CO2-rich geothermal areas in Iceland as natural analogues for geologic carbon sequestration

NASA Astrophysics Data System (ADS)

Thomas, D.; Maher, K.; Bird, D. K.; Brown, G. E.; Arnorsson, S.

2013-12-01

Geologic CO2 sequestration into mafic rocks via silicate mineral dissolution and carbonate precipitation has been suggested as a way to mitigate industrial CO2 emissions by storing CO2 in a stable form. Experimental observations of irreversible reaction of basalt with supercritical or gaseous and aqueous CO2 have resulted in carbonate precipitation, but there are no universal trends linking the extent of mineralization and type of reaction products to the bulk rock composition, glass percentage or mineralogy of the starting material. Additionally, concern exists that CO2 leakage from injection sites and migration through the subsurface may induce mineral dissolution and desorption of trace elements, potentially contaminating groundwater. This study investigates low-temperature (≤180°C) basaltic geothermal areas in Iceland with an anomalously high input of magmatic CO2 as natural analogues of the geochemical processes associated with the injection of CO2 into mafic rocks and possible leakage. Fluids that contain >4 mmol/kg total CO2 are common along the divergent Snæfellsnes Volcanic Zone in western Iceland and within the South Iceland Seismic Zone in southwest Iceland. The meteorically derived waters contain up to 80 mmol/kg dissolved inorganic carbonate (DIC). The aqueous concentration of major cations and trace elements is greater than that in Icelandic surface and groundwater and increases with DIC and decreasing pH. Concentrations of As and Ni in some samples are several times the World Health Organization (WHO) guidelines for safe drinking water. Thermodynamic modeling indicates that waters approach saturation with respect to calcite and/or aragonite, kaolinite and amorphous silica, and are undersaturated with respect to plagioclase feldspar, clinozoisite and Ca-zeolites. Petrographic study of drill cuttings from wells that intersect the CO2-rich areas indicates that the sites have undergone at least two stages of hydrothermal alteration: initial high-temperature and late stage low-temperature alteration. Imaging results from scanning electron microscopy show that calcite has replaced hydrothermally altered silicate minerals, such as albitic plagioclase. CO2-rich low-temperature fluids are not in equilibrium with correlative high-temperature hydrothermal mineral assemblages, indicating that the kinetics of mineral dissolution and secondary mineral precipitation, along with fluid residence times, are important controls on CO2 alteration and mineral formation at low temperatures. Our results have implications for predicting mineral product formation and trace element release during geologic carbon sequestration into hydrothermally altered basalts.

The effect of elevated CO2 and temperature on nutrient uptake by plants grown in basaltic soil

NASA Astrophysics Data System (ADS)

Villasenor Iribe, E.; Dontsova, K.; Juarez, S.; Le Galliard, J. F.; Chollet, S.; Llavata, M.; Massol, F.; Barré, P.; Gelabert, A.; Daval, D.; Troch, P.; Barron-Gafford, G.; Van Haren, J. L. M.; Ferrière, R.

2017-12-01

Mineral weathering is an important process in soil formation. The interactions between the hydrologic, geologic and atmospheric cycles often determine the rate at which weathering occurs. Elements and nutrients weathered from the soil by water can be removed from soils in the runoff and seepage, but they can also remain in situ as newly precipitated secondary minerals or in biomass as a result of plant uptake. Here we present data from an experiment that was conducted at the controlled environment facility, Ecotron Ile-de-France (Saint-Pierre-les-Nemours, France) that studied mineral weathering and plant growth in granular basaltic material with high glass content that is being used to simulate soil in large scale Biosphere 2 Landscape Evolution Observatory (LEO) project. The experiment used 3 plant types: velvet mesquite (Prosopis velutina), green spangletop (Leptochloa dubia), and alfalfa (Medicago sativa), which were grown under varying temperature and CO2 conditions. We hypothesized that plants grown under warmer, higher CO2 conditions would have larger nutrient concentrations as more mineral weathering would occur. Results of plant digestions and analysis showed that plant concentrations of lithogenic elements were significantly influenced by the plant type and were different between above- and below-ground parts of the plant. Temperature and CO2 treatment effects were less pronounced, but we observed significant temperature effect on plant uptake. A number of major and trace elements showed increase in concentration with increase in temperature at elevated atmospheric CO2. Effect was observed both in the shoots and in the roots, but more significant differences were observed in the shoots. Results presented here indicate that climate change would have strong effect on plant uptake and mobility of weathered elements during soil formation and give further evidence of interactions between abiotic and biological processes in terrestrial ecosystems.

Iron Hydroxide Minerals Drive Organic and Phosphorus Chemistry in Subsurface Redox / pH Gradients

NASA Astrophysics Data System (ADS)

Flores, E.; Barge, L. M.; VanderVelde, D.; Baum, M.

2017-12-01

Iron minerals, particularly iron oxides and oxyhydroxides, are prevalent on Mars and may exist in mixed valence or even reduced states beneath the oxidized surface. Iron (II,III) hydroxides, including green rust, are reactive and potentially catalytic minerals that can absorb and concentrate charged species, while also driving chemical reactions. These minerals are highly redox-sensitive and the presence of organics and/or phosphorus species could affect their mineralogy and/or stability. Conversely, the minerals might be able to drive chemical processes such as amino acid formation, phosphorus oxyanion reactions, or could simply selectively preserve organic species via surface adsorption. In an open aqueous sediment column, soluble products of mineral-driven reactions could also diffuse to sites of different chemical conditions to react even further. We synthesized Fe-hydroxide minerals under various conditions relevant to early Earth and ancient Mars (>3.0 Gyr), anoxically and in the presence of salts likely to have been present in surface or ground waters. Using these minerals we conducted experiments to test whether iron hydroxides could promote amino acid formation, and how the reaction is affected by subsurface gradients of redox, pH, and temperature. We also tested the adsorption of organic and phosphorus species onto Fe-hydroxide minerals at different conditions within the gradients. The suite of organic or phosphorus signatures that may be found in a particular mineral system is a combination of what is synthesized there, what is preferentially concentrated / retained there, and what is preserved against degradation. Further work is needed to determine how these processes could have proceeded on Mars and what mineral-organic signatures, abiotic or otherwise, would be produced from such processes.

Mount St. Augustine volcano fumarole wall rock alteration: Mineralogy, zoning, composition and numerical models of its formation process

USGS Publications Warehouse

Getahun, A.; Reed, M.H.; Symonds, R.

1996-01-01

Intensely altered wall rock was collected from high-temperature (640??C) and low-temperature (375??C) vents at Augustine volcano in July 1989. The high-temperature altered rock exhibits distinct mineral zoning differentiated by color bands. In order of decreasing temperature, the color bands and their mineral assemblages are: (a) white to grey (tridymite-anhydrite); (b) pink to red (tridymite-hematite-Fe hydroxide-molysite (FeCl3) with minor amounts of anhydrite and halite); and (c) dark green to green (anhydrite-halite-sylvite-tridymite with minor amounts of molysite, soda and potash alum, and other sodium and potassium sulfates). The alteration products around the low-temperature vents are dominantly cristobalite and amorphous silica with minor potash and soda alum, aphthitalite, alunogen and anhydrite. Compared to fresh 1986 Augustine lava, the altered rocks exhibit enrichments in silica, base metals, halogens and sulfur and show very strong depletions in Al in all alteration zones and in iron, alkali and alkaline earth elements in some of the alteration zones. To help understand the origins of the mineral assemblages in altered Augustine rocks, we applied the thermochemical modeling program, GASWORKS, in calculations of: (a) reaction of the 1987 and 1989 gases with wall rock at 640 and 375??C; (b) cooling of the 1987 gas from 870 to 100??C with and without mineral fractionation; (c) cooling of the 1989 gas from 757 to 100??C with and without mineral fractionation; and (d) mixing of the 1987 and 1989 gases with air. The 640??C gas-rock reaction produces an assemblage consisting of silicates (tridymite, albite, diopside, sanidine and andalusite), oxides (magnetite and hercynite) and sulfides (bornite, chalcocite, molybdenite and sphalerite). The 375??C gas-rock reaction produces dominantly silicates (quartz, albite, andalusite, microcline, cordierite, anorthite and tremolite) and subordinate amounts of sulfides (pyrite, chalcocite and wurtzite), oxides (magnetite), sulfates (anhydrite) and halides (halite). The cooling calculations produce: (a) anhydrite, halite, sylvite; (b) Cu, Mo, Fe and Zn sulfides; (c) Mg fluoride at high temperature (> 370??C); (d) chlorides, fluorides and sulfates of Mn, Fe, Zn, Cu and Al at intermediate temperature (170-370??C); and (e) hydrated sulfates, liquid sulfur, crystalline sulfur, hydrated sulfuric acid and water at low temperature ( 0.41 (> 628??C). This is followed by precipitation of sulfates of Fe, Cu, Pb, Zn and Al at lg/a ratios between 0.41 and -0.4 (628-178??C). At a lg/r ratio of < - 0.4 (178??C), anhydrous sulfates are replaced by their hydrated forms and hygroscopic sulfuric acid forms. At these low g/a ratios, hydrated sulfuric acid becomes the dominant phase in the system. Comparison of the thermochemical modeling results with the natural samples suggests that the alteration assemblages include: (1) minerals that precipitate from direct cooling of the volcanic gas; (2) phases that form by volcanic gases mixing with air; and (3) phases that form by volcanic gas-air-rock reaction. A complex interplay of the three processes produces the observed mineral zoning. Another implication of the numerical simulation results is that most of the observed incrustation and sublimate minerals apparently formed below 700??C.

Characterization of Inclusions in Evolution of Sodium Sulfate Using Terahertz Time-domain Spectroscopy.

PubMed

Bao, Rima; Wu, Zhikui; Li, Hao; Wang, Fang; Miao, Xinyang; Feng, Chengjing

2017-01-01

The study of fluid inclusion is one of the important means to understanding the evolution of mineral crystals, and can therefore provide original information of mineral evolution. In the process of evolution, outside factors such as temperature and pressure, directly affect the number and size of inclusions, and thus are related to the properties of crystals. In this paper, terahertz time-domain spectroscopy (THz-TDS) was used to detect sodium sulfate crystals with different growth temperatures, and absorption coefficient spectra of the samples were obtained. It is suggested that the evolution of sodium sulfate could be divided into two stages, and 80°C was the turning point. X-ray diffraction (XRD) and polarizing microscopy were used to support this conclusion. The research showed that THz-TDS could characterize the evolution of mineral crystals, and it had a unique advantage in terms of crystal evolution.

Hydroxyapatite: Vibrational spectra and monoclinic to hexagonal phase transition

NASA Astrophysics Data System (ADS)

Slepko, Alexander; Demkov, Alexander A.

2015-02-01

Fundamental studies of biomaterials are necessary to deepen our understanding of their degradation and to develop cure for related illnesses. Biomineral hydroxyapatite Ca10(PO4)6(OH)2 is the main mineral constituent of mammal bone, and its synthetic analogues are used in biomedical applications. The mineral can be found in either hexagonal or monoclinic form. The transformation between these two phases is poorly understood, but knowing its mechanism may be critical to reversing processes in bone related to aging. Using density functional theory, we investigate the mechanisms of the phase transformation and estimate the transition temperature to be 680 K in fair agreement with the experimental temperature of 470 K. We also report the heat capacity of hydroxyapatite and a peculiarity in its phonon dispersion that might allow for non-destructive measurements of the crystal composition with applications in preventive medical screening for bone mineral loss.

A review of zinc oxide mineral beneficiation using flotation method.

PubMed

Ejtemaei, Majid; Gharabaghi, Mahdi; Irannajad, Mehdi

2014-04-01

In recent years, extraction of zinc from low-grade mining tailings of oxidized zinc has been a matter of discussion. This is a material which can be processed by flotation and acid-leaching methods. Owing to the similarities in the physicochemical and surface chemistry of the constituent minerals, separation of zinc oxide minerals from their gangues by flotation is an extremely complex process. It appears that selective leaching is a promising method for the beneficiation of this type of ore. However, with the high consumption of leaching acid, the treatment of low-grade oxidized zinc ores by hydrometallurgical methods is expensive and complex. Hence, it is best to pre-concentrate low-grade oxidized zinc by flotation and then to employ hydrometallurgical methods. This paper presents a critical review on the zinc oxide mineral flotation technique. In this paper, the various flotation methods of zinc oxide minerals which have been proposed in the literature have been detailed with the aim of identifying the important factors involved in the flotation process. The various aspects of recovery of zinc from these minerals are also dealt with here. The literature indicates that the collector type, sulfidizing agent, pH regulator, depressants and dispersants types, temperature, solid pulp concentration, and desliming are important parameters in the process. The range and optimum values of these parameters, as also the adsorption mechanism, together with the resultant flotation of the zinc oxide minerals reported in the literature are summarized and highlighted in the paper. This review presents a comprehensive scientific guide to the effectiveness of flotation strategy. Copyright © 2013 Elsevier B.V. All rights reserved.

Process for coal liquefaction employing selective coal feed

DOEpatents

Hoover, David S.; Givens, Edwin N.

1983-01-01

An improved coal liquefaction process is provided whereby coal conversion is improved and yields of pentane soluble liquefaction products are increased. In this process, selected feed coal is pulverized and slurried with a process derived solvent, passed through a preheater and one or more dissolvers in the presence of hydrogen-rich gases at elevated temperatures and pressures, following which solids, including mineral ash and unconverted coal macerals, are separated from the condensed reactor effluent. The selected feed coals comprise washed coals having a substantial amount of mineral matter, preferably from about 25-75%, by weight, based upon run-of-mine coal, removed with at least 1.0% by weight of pyritic sulfur remaining and exhibiting vitrinite reflectance of less than about 0.70%.

Gas-solid carbonation as a current alternative origin for carbonates in Martian regolith

NASA Astrophysics Data System (ADS)

Garenne, A.; Montes-Hernandez, G.; Beck, P.; Schmitt, B.; Brissaud, O.

2011-12-01

Carbonates are abundant sedimentary minerals at the surface and sub-surface of Earth and they have been proposed as tracers of liquid water in extraterrestrial environments (e.g. at Mars surface). Its formation mechanism is since generally associated with aqueous alteration processes. Recently, carbonates minerals have been discovered on Mars surface by different orbital or rovers missions. In particular, the phoenix mission has measured from 1 to 5% of calcium carbonate (calcite type). These occurrences have been reported in area were the relative humidity is significantly high (Boynton et al., 2009). The small concentration of carbonates suggests an alternative process than carbonation in aqueous conditions. Such an observation might rather point toward a possible formation mechanism by dust-gas reaction under current Martian conditions. For this reason, in the present study, we designed an experimental setup consisting of an infrared microscope coupled to a cryogenic reaction cell (IR-CryoCell setup) in order to investigate the gas-solid carbonation of three different mineral precursors for carbonates (Ca and Mg hydroxides, and a hydrated Ca silicate formed from Ca2SiO4) at low temperature (from -10 to 25°C) and at reduced CO2 pressure (from 100 to 1000 mbar). These mineral materials are crucial precursors to form respective Ca and Mg carbonates in humid environments (0 < relative humidity < 100%) at dust-CO2 or dust-water ice-CO2 interfaces. The results have revealed a significant and fast carbonation process for Ca hydroxide and hydrated Ca silicate. Conversely, slight carbonation process was observed for Mg hydroxide. These results suggest that gas-solid carbonation process or carbonate formation at the dust-water ice-CO2 interfaces could be a currently active Mars surface process. We note that the carbonation process at low temperature (<0°C) described in the present study could also have important implications on the dust-water ice-CO2 interactions in cold terrestrial environments (e.g. Antarctic).

Radioactive Demonstration Of Mineralized Waste Forms Made From Hanford Low Activity Waste (Tank SX-105 And AN-103) By Fluidized Bed Steam Reformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, Carol; Herman, Connie; Crawford, Charles

One of the immobilization technologies under consideration as a Supplemental Treatment for Hanford’s Low Activity Waste (LAW) is Fluidized Bed Steam Reforming (FBSR). The FBSR technology forms a mineral waste form at moderate processing temperatures thus retaining and atomically bonding the halides, sulfates, and technetium in the mineral phases (nepheline, sodalite, nosean, carnegieite). Additions of kaolin clay are used instead of glass formers and the minerals formed by the FBSR technology offers (1) atomic bonding of the radionuclides and constituents of concern (COC) comparable to glass, (2) short and long term durability comparable to glass, (3) disposal volumes comparable tomore » glass, and (4) higher Na2O and SO{sub 4} waste loadings than glass. The higher FBSR Na{sub 2}O and SO{sub 4} waste loadings contribute to the low disposal volumes but also provide for more rapid processing of the LAW. Recent FBSR processing and testing of Hanford radioactive LAW (Tank SX-105 and AN-103) waste is reported and compared to previous radioactive and non-radioactive LAW processing and testing.« less

Friction behavior for clay minerals during dehydration process: implication for unstable friction at shallow portion along subducting plate

NASA Astrophysics Data System (ADS)

Kubo, T.; Katayama, I.

2016-12-01

Along plate boundary subduction thrusts, the transformation of smectite to illite within fault gouge at temperatures around 100 - 200 °C is one of the key mineralogical changes thought to control the updip limit of seismicity (Hyndman et al., 1997). Since hydration state of clay minerals is possible to vary from moment to moment in nature, it is important to investigate the effect of dehydration and hydrate state on frictional properties with progression of a removal of water is rare. In this study, we focus on the effect of dehydration of water on the frictional properties of clay minerals by temperature-rising test. For the friction experiments, starting materials we used are Ca-montmorillonite, which were placed on the simulated fault surface and two side blocks were placed together to produce a double-direct shear configuration. The sample assembly was heated by an external furnace up to 400 °C that is monitored by thermocouples located in the central part of sample assembly. After steady-state friction at room temperature we started to elevate the temperature around the specimen at a constant heating rate of 1, 3, and 10 °C/min. Ca-montmorillonite gouge showed unique friction behavior development as elevated temperature, which is divided into three stages; (1) friction coefficient decreased at relative low temperature, (2) friction coefficient increased at middle temperature, and (3) stick-slip behavior occurred at high temperature. Stick-slip behavior as elevated temperature implies to have a potential of velocity weakening behavior. Observed stick-slip behavior occurs at a temperature of 320 °C, which is extremely higher from a temperature range of occurring dehydration for Ca-montmorillonite (100 - 200 °C). However, at low heating rate the temperature that stick-slip behavior occurs shifted to lower temperature. Our preliminary results suggest that the observed systematical shift suggest that these frictional behavior is likely to be controlled by dehydration reaction kinetics. Dehydration of clay minerals change friction behavior, and play a key role for the occurrence of earthquakes along subducting plate.

Estimation of reactive surface area using a combined method of laboratory analyses and digital image processing

NASA Astrophysics Data System (ADS)

Ma, Jin; Kong, Xiang-Zhao; Saar, Martin O.

2017-04-01

Fluid-rock interactions play an important role in the engineering processes such as chemical stimulation of enhanced geothermal systems and carbon capture, utilization, and storage. However, these interactions highly depend on the accessible reactive surface area of the minerals that are generally poorly constrained for natural geologic samples. In particular, quantifying surface area of each reacting mineral within whole rock samples is challenging due to the heterogeneous distribution of minerals and pore space. In this study, detailed laboratory analyses were performed on sandstone samples from deep geothermal sites in Lithuania. We measure specific surface area of whole rock samples using a gas adsorption method (so-called B.E.T.) with N2 at a temperature of 77.3K. We also quantify their porosity and pore size distribution by a Helium gas pycnometer and a Hg porosimetry, respectively. Rock compositions are determined by a combination of X-ray fluorescence (XRF) and quantitative scanning electron microscopy (SEM) - Energy-dispersive X-ray spectroscopy (EDS), which are later geometrically mapped on images of two-dimensional SEM- Backscattered electrons (BSE) with a resolution of 1.2 μm and three-dimensional micro-CT with a resolution of 10.3 μm to produce a digital mineral map for further constraining the accessibility of reactive minerals. Moreover, we attempt to link the whole rock porosity, pore size distribution, and B.E.T. specific surface area with the digital mineral maps. We anticipate these necessary analyses to provide in-depth understanding of fluid sample chemistry from later hydrothermal reactive flow-through experiments on whole rock samples at elevated pressure and temperature.

Process for coal liquefaction in staged dissolvers

DOEpatents

Roberts, George W.; Givens, Edwin N.; Skinner, Ronald W.

1983-01-01

There is described an improved liquefaction process by which coal is converted to a low ash and low sulfur carbonaceous material that can be used as a fuel in an environmentally acceptable manner without costly gas scrubbing equipment. In the process, coal is slurried with a pasting oil, passed through a preheater and at least two dissolvers in series in the presence of hydrogen-rich gases at elevated temperatures and pressures. Solids, including mineral ash and unconverted coal macerals, are separated from the condensed reactor effluent. In accordance with the improved process, the first dissolver is operated at a higher temperature than the second dissolver. This temperature sequence produces improved product selectivity and permits the incorporation of sufficient hydrogen in the solvent for adequate recycle operations.

A mild, near-surface aqueous environment on Noachian Mars preserved in ALH84001

NASA Astrophysics Data System (ADS)

Halevy, I.; Fischer, W. W.; Eiler, J. M.

2011-12-01

Despite widespread evidence for liquid water at the surface of Mars during parts of the Noachian epoch, the temperature of early aqueous environments has been impossible to establish, raising questions of whether Mars' surface was ever warmer than today. This has hindered insight into aqueous alteration processes, which, on the basis of orbital spectroscopy, appear to have been prevalent on Noachian Mars. It is important to understand such processes, as they link the observed secondary mineral assemblages to interactions between primary igneous silicates and the surface environment (atmosphere-hydrosphere). We have addressed this problem by determining the precipitation temperatures of secondary carbonate minerals preserved in the oldest known sample of Mars' crust-the meteorite Allan Hills 84001 (ALH84001). Using carbonate 'clumped' isotope thermometry we have found that the carbonates in ALH84001, which are 3.9-4.0 billion years old, formed at a temperature of ~18±4°C. With temperature known, we used the carbon and oxygen isotopic composition of the carbonates, as constrained by both our measurements and previous acid digestion and ion microprobe studies, to develop a model for their formation process and environment. The observed isotopic variation is best explained by carbonate precipitation out of a gradually evaporating, shallow subsurface aqueous solution (e.g. a regolith aquifer) at near-constant temperatures. Furthermore, on the basis of the isotopic composition of the earliest precipitated carbonates in ALH84001, the volatiles from which they formed (H2O and CO2) came not from depth, but from the early Martian surface. The occurrence of carbonates in other SNC meteorites and as a minor component of Martian dust implies that environments analogous to the one we studied may have been important in generating some of the observed secondary mineral assemblages by interaction between Mars' igneous crust and its atmosphere-hydrosphere.

How Life and Rocks Have Co-Evolved

NASA Astrophysics Data System (ADS)

Hazen, R.

2014-04-01

The near-surface environment of terrestrial planets and moons evolves as a consequence of selective physical, chemical, and biological processes - an evolution that is preserved in the mineralogical record. Mineral evolution begins with approximately 12 different refractory minerals that form in the cooling envelopes of exploding stars. Subsequent aqueous and thermal alteration of planetessimals results in the approximately 250 minerals now found in unweathered lunar and meteorite samples. Following Earth's accretion and differentiation, mineral evolution resulted from a sequence of geochemical and petrologic processes, which led to perhaps 1500 mineral species. According to some origin-of-life scenarios, a planet must progress through at least some of these stages of chemical processing as a prerequisite for life. Once life emerged, mineralogy and biology co-evolved and dramatically increased Earth's mineral diversity to >4000 species. Sequential stages of a planet's near-surface evolution arise from three primary mechanisms: (1) the progressive separation and concentration of the elements from their original relatively uniform distribution in the presolar nebula; (2) the increase in range of intensive variables such as pressure, temperature, and volatile activities; and (3) the generation of far-from-equilibrium conditions by living systems. Remote observations of the mineralogy of other terrestrial bodies may thus provide evidence for biological influences beyond Earth. Recent studies of mineral diversification through time reveal striking correlations with major geochemical, tectonic, and biological events, including large-changes in ocean chemistry, the supercontinent cycle, the increase of atmospheric oxygen, and the rise of the terrestrial biosphere.

Formation and Characterization of Anisotropic Block Copolymer Gels

NASA Astrophysics Data System (ADS)

Liaw, Chya Yan; Joester, Derk; Burghardt, Wesley; Shull, Kenneth

2012-02-01

Cylindrical micelles formed from block copolymer solutions closely mimic biological fibers that are presumed to guide mineral formation during biosynthesis of hard tissues like bone. The goal of our work is to use acrylic block copolymers as oriented templates for studying mineral formation reactions in model systems where the structure of the underlying template is well characterized and reproducible. Self-consistent mean field theory is first applied to investigate the thermodynamically stable micellar morphologies as a function of temperature and block copolymer composition. Small-angle x-ray scattering, optical birefringence and shear rheometry are used to study the morphology development during thermal processing. Initial experiments are based on a thermally-reversible alcohol-soluble system that can be converted to an aqueous gel by hydrolysis of a poly(t-butyl methacrylate) block to a poly(methacrylic acid) block. Aligned cylindrical domains are formed in the alcohol-based system when shear is applied in an appropriate temperature regime, which is below the critical micelle temperature but above the temperature at which the relaxation time of the gels becomes too large. Processing strategies for producing the desired cylindrical morphologies are being developed that account for both thermodynamic and kinetic effects.

Advances in chemical and physical properties of electric arc furnace carbon steel slag by hot stage processing and mineral mixing.

PubMed

Liapis, Ioannis; Papayianni, Ioanna

2015-01-01

Slags are recognised as a highly efficient, cost effective tool in the metal processing industry, by minimising heat losses, reducing metal oxidation through contact with air, removing metal impurities and protecting refractories and graphite electrodes. When compared to natural aggregates for use in the construction industry, slags have higher specific weight that acts as an economic deterrent. A method of altering the specific weight of EAFC slag by hot stage processing and mineral mixing, during steel production is presented in this article. The method has minimal interference with the production process of steel, even by limited additions of appropriate minerals at high temperatures. Five minerals are examined, namely perlite, ladle furnace slag, bauxite, diatomite and olivine. Measurements of specific weight are accompanied by X-ray diffraction (XRD) and fluorescence (XRF) analysis and scanning electron microscopy spectral images. It is also shown how altering the chemical composition is expected to affect the furnace refractory lining. Additionally, the process has been repeated for the most suitable mix in gas furnace and physical properties (FI, SI, LA, PSV, AAV, volume stability) examined. Alteration of the specific weight can result in tailoring slag properties for specific applications in the construction sector. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spycher, Nicolas; Peiffer, Loic; Finsterle, Stefan

GeoT implements the multicomponent geothermometry method developed by Reed and Spycher (1984, Geochim. Cosmichim. Acta 46 513–528) into a stand-alone computer program, to ease the application of this method and to improve the prediction of geothermal reservoir temperatures using full and integrated chemical analyses of geothermal fluids. Reservoir temperatures are estimated from statistical analyses of mineral saturation indices computed as a function of temperature. The reconstruction of the deep geothermal fluid compositions, and geothermometry computations, are all implemented into the same computer program, allowing unknown or poorly constrained input parameters to be estimated by numerical optimization using existing parameter estimationmore » software, such as iTOUGH2, PEST, or UCODE. This integrated geothermometry approach presents advantages over classical geothermometers for fluids that have not fully equilibrated with reservoir minerals and/or that have been subject to processes such as dilution and gas loss.« less

A simple model for closure temperature of a trace element in cooling bi-mineralic systems

NASA Astrophysics Data System (ADS)

Liang, Yan

2015-09-01

Closure temperature is defined as the lower temperature limit at which the element of interest effectively ceases diffusive exchange with its surrounding medium during cooling. Here we generalize the classic equation of Dodson (1973) for cooling mono-mineralic systems to cooling bi-mineralic aggregates by considering diffusive exchange of a trace element between the two minerals in a closed system. We present a simple analytical model that includes key parameters affecting the closure temperature of a trace element in cooling bi-mineralic systems: cooling rate, temperature-dependent diffusion coefficients for the trace element in the two minerals, temperature-dependent partition coefficient of the trace element between the two minerals, effective grain sizes of the two minerals, and volume proportions of the minerals in the system. We show that closure temperatures of a trace element in cooling bi-mineralic systems are bounded by the closure temperatures of the trace element in the two mono-mineralic systems and that our generalized model reduces to Dodson's equation when one of the mineral serves as "an effective infinite" reservoir to the other mineral. Application to closure temperatures of REE in orthopyroxene and clinopyroxene bi-mineralic systems highlights the importance of REE diffusion and partitioning in the pyroxenes as well as clinopyroxene modal abundance and grain size in the systems. Closure temperatures for REE in two-pyroxene bearing equigranular rocks are controlled primarily by diffusion in orthopyroxene unless the modal abundance of clinopyroxene is very small. This has important bearings on the interpretation of temperatures derived from the REE-in-two-pyroxene thermometer.

Clumped-isotope thermometry of magnesium carbonates in ultramafic rocks

DOE PAGES

Garcia del Real, Pablo; Maher, Kate; Kluge, Tobias; ...

2016-08-19

Here, magnesium carbonate minerals produced by reaction of H 2O–CO 2 with ultramafic rocks occur in a wide range of paragenetic and tectonic settings and can thus provide insights into a variety of geologic processes, including deposition of ore-grade, massive-vein cryptocrystalline magnesite; formation of hydrous magnesium carbonates in weathering environments; and metamorphic carbonate alteration of ultramafic rocks. However, the application of traditional geochemical and isotopic methods to infer temperatures of mineralization, the nature of mineralizing fluids, and the mechanisms controlling the transformation of dissolved CO 2 into magnesium carbonates in these settings is difficult because the fluids are usually notmore » preserved.« less

Clumped-isotope thermometry of magnesium carbonates in ultramafic rocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia del Real, Pablo; Maher, Kate; Kluge, Tobias

Here, magnesium carbonate minerals produced by reaction of H 2O–CO 2 with ultramafic rocks occur in a wide range of paragenetic and tectonic settings and can thus provide insights into a variety of geologic processes, including deposition of ore-grade, massive-vein cryptocrystalline magnesite; formation of hydrous magnesium carbonates in weathering environments; and metamorphic carbonate alteration of ultramafic rocks. However, the application of traditional geochemical and isotopic methods to infer temperatures of mineralization, the nature of mineralizing fluids, and the mechanisms controlling the transformation of dissolved CO 2 into magnesium carbonates in these settings is difficult because the fluids are usually notmore » preserved.« less

Processing of ash and slag waste of heating plants by arc plasma to produce construction materials and nanomodifiers

NASA Astrophysics Data System (ADS)

Buyantuev, S. L.; Urkhanova, L. A.; Kondratenko, A. S.; Shishulkin, S. Yu; Lkhasaranov, S. A.; Khmelev, A. B.

2017-01-01

The resultsare presented of plasma processing slag and ash waste from coal combustion in heating plants. Melting mechanism of ashand slagraw material is considered by an electromagnetic technological reactor. The analysis was conducted of temperature and phase transformations of raw material when it is heated up to the melting point, and also determination of specific energy consumption by using a generalized model of the thermodynamic analysis of TERRA. The study of materials melting temperature conditions and plum of melt was carried with high-temperature thermal imaging method, followed by mapping and 3D-modeling of the temperature fields. The investigations to establish the principal possibilities of using slag waste of local coal as raw material for the production of mineral (ash and slag) fibers found that by chemical composition there are oxides in the following ranges: 45-65% SiO2; 10-25% Al2O3; 10-45% CaO; 5-10% MgO; other minerals (less than 5%). Thus, these technological wastes are principally suitable for melts to produce mineral wool by the plasma method. An analysis of the results shows the melting point of ash and slag waste - 1800-2000 °C. In this case the specific energy consumption of these processes keeps within the limits of 1.1-1.3 kW*h/kg. For comparison it should be noted that the unit cost of electricity in the known high-melting industrial installations 5-6 kW*h/kg. Upon melting ash and slag waste, which contains up to 2-5% of unburned carbon, carbon nanomaterials were discovered.in the form of ultrafine soot accumulating as a plaque on the water-cooled surfaces in the gas cleaning chamber. The process of formation of soot consists in sublimation-desublimation of part of carbon which is in ash and slag, and graphite electrode. Thus, upon melting of ash and slag in the electromagnetic reactor it is possible to obtain melt, and in the subsequent mineral high quality fiber, which satisfies the requirements of normative documents, and simultaneously to receive a condensed product in the form of carbon sublimated nanoparticles, which can be found further use in construction materials, in particular in high-strength concrete and other materials.

Gross Nitrogen Mineralization in Surface Sediments of the Yangtze Estuary

PubMed Central

Liu, Min; Li, Xiaofei; Yin, Guoyu; Zheng, Yanling; Deng, Fengyu

2016-01-01

Nitrogen mineralization is a key biogeochemical process transforming organic nitrogen to inorganic nitrogen in estuarine and coastal sediments. Although sedimentary nitrogen mineralization is an important internal driver for aquatic eutrophication, few studies have investigated sedimentary nitrogen mineralization in these environments. Sediment-slurry incubation experiments combined with 15N isotope dilution technique were conducted to quantify the potential rates of nitrogen mineralization in surface sediments of the Yangtze Estuary. The gross nitrogen mineralization (GNM) rates ranged from 0.02 to 5.13 mg N kg-1 d-1 in surface sediments of the study area. The GNM rates were generally higher in summer than in winter, and the relative high rates were detected mainly at sites near the north branch and frontal edge of this estuary. The spatial and temporal distributions of GNM rates were observed to depend largely on temperature, salinity, sedimentary organic carbon and nitrogen contents, and extracellular enzyme (urease and L-glutaminase) activities. The total mineralized nitrogen in the sediments of the Yangtze Estuary was estimated to be about 6.17 × 105 t N yr-1, and approximately 37% of it was retained in the estuary. Assuming the retained mineralized nitrogen is totally released from the sediments into the water column, which contributed 12–15% of total dissolved inorganic nitrogen (DIN) sources in this study area. This result indicated that the mineralization process is a significant internal nitrogen source for the overlying water of the Yangtze Estuary, and thus may contribute to the estuarine and coastal eutrophication. PMID:26991904

Partitioning of Cu between mafic minerals, Fe-Ti oxides and intermediate to felsic melts

NASA Astrophysics Data System (ADS)

Liu, Xingcheng; Xiong, Xiaolin; Audétat, Andreas; Li, Yuan

2015-02-01

This study used improved capsule technique i.e., Pt95Cu05 or Au95Cu05 alloy capsules as Cu sources to determine Cu partitioning between mafic minerals, Fe-Ti oxides and intermediate to felsic melts at 0.5-2.5 GPa, 950-1100 °C and various oxygen fugacities (fO2). In combination with the data from the mafic composition systems, the results demonstrate that Cu is generally highly incompatible in mafic minerals and moderately incompatible to compatible in Fe-Ti oxides. The general order of mineral/melt Cu partition coefficients (DCu) is garnet (0.01-0.06) ⩽ olivine (0.04-0.20) ≈ opx (0.04-0.24) ≈ amphibole (0.04-0.20) ⩽ cpx (0.04-0.45) ⩽ magnetite, titanomagnetite and Cr-spinel (0.18-1.83). The variations in DCu depend mainly on temperature, fO2 or mineral composition. In general, DCu for olivine (and perhaps opx) increases with decreasing temperature and increasing fO2. DCu increases for cpx with Na+ (pfu) in cpx, for magnetite and Cr-spinel with Fe3+ (pfu) in these phases and for titanomagnetite with Ti4+ (pfu) in this phase. The large number of DCu data (99 pairs) serves as a foundation for quantitatively understanding the behavior of Cu during magmatic processes. The generation of intermediate to felsic magmas via fractional crystallization or partial melting of mafic rocks (magmas) at deep levels of crust involves removal of or leaving assemblages of mafic minerals + Fe-Ti oxides ± sulfides. With our DCu data on mafic minerals and Fe-Ti oxides, DCubulk values around 0.2 were obtained for the sulfide-free assemblages. Cu will thus be concentrated efficiently in the derived melts during these two processes if sulfides are absent or negligible, explaining that high fO2 and sulfide-destabilization are favorable to formation of the porphyry Cu system.

Substrate-dependent temperature sensitivity of soil organic matter decomposition

NASA Astrophysics Data System (ADS)

Myachina, Olga; Blagodatskaya, Evgenia

2015-04-01

Activity of extracellular enzymes responsible for decomposition of organics is substrate dependent. Quantity of the substrate is the main limiting factor for enzymatic or microbial heterotrophic activity in soils. Different mechanisms of enzymes response to temperature suggested for low and high substrate availability were never proved for real soil conditions. We compared the temperature responses of enzymes-catalyzed reactions in soils. Basing on Michaelis-Menten kinetics we determined the enzymes affinity to substrate (Km) and mineralization potential of heterotrophic microorganisms (Vmax) 1) for three hydrolytic enzymes: β-1,4-glucosidase, N-acetyl- β -D-glucosaminidase and phosphatase by the application of fluorogenically labeled substrates and 2) for mineralization of 14C-labeled glucose by substrate-dependent respiratory response. Here we show that the amount of available substrate is responsible for temperature sensitivity of hydrolysis of polymers in soil, whereas monomers oxidation to CO2 does not depend on substrate amount and is mainly temperature governed. We also found that substrate affinity of enzymes (which is usually decreases with the temperature) differently responded to warming for the process of depolymerisation versus monomers oxidation. We suggest the mechanism to temperature acclimation based on different temperature sensitivity of enzymes kinetics for hydrolysis of polymers and for monomers oxidation.

Temperature sensitivity of soil organic carbon mineralization along an elevation gradient in the Wuyi Mountains, China.

PubMed

Wang, Guobing; Zhou, Yan; Xu, Xia; Ruan, Honghua; Wang, Jiashe

2013-01-01

Soil organic carbon (SOC) actively participates in the global carbon (C) cycle. Despite much research, however, our understanding of the temperature sensitivity of soil organic carbon (SOC) mineralization is still very limited. To investigate the responses of SOC mineralization to temperature, we sampled surface soils (0-10 cm) from evergreen broad-leaf forest (EBF), coniferous forest (CF), sub-alpine dwarf forest (SDF), and alpine meadow (AM) along an elevational gradient in the Wuyi Mountains, China. The soil samples were incubated at 5, 15, 25, and 35°C with constant soil moisture for 360 days. The temperature sensitivity of SOC mineralization (Q(10)) was calculated by comparing the time needed to mineralize the same amount of C at any two adjacent incubation temperatures. Results showed that the rates of SOC mineralization and the cumulative SOC mineralized during the entire incubation significantly increased with increasing incubation temperatures across the four sites. With the increasing extent of SOC being mineralized (increasing incubation time), the Q(10) values increased. Moreover, we found that both the elevational gradient and incubation temperature intervals significantly impacted Q(10) values. Q(10) values of the labile and recalcitrant organic C linearly increased with elevation. For the 5-15, 15-25, and 25-35°C intervals, surprisingly, the overall Q(10) values for the labile C did not decrease as the recalcitrant C did. Generally, our results suggest that subtropical forest soils may release more carbon than expected in a warmer climate.

Factors influencing spatial variability in nitrogen processing in nitrogen-saturated soils

Treesearch

Frank S. Gilliam; Charles C. Somerville; Nikki L. Lyttle; Mary Beth Adams

2001-01-01

Nitrogen (N) saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF), West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and...

Numerical simulation of temperature distribution in cylindrical ilmenite (FeTiO3) due to microwave heating

NASA Astrophysics Data System (ADS)

Hidayat, Mas Irfan P.; Fellicia, Dian Mughni; Rafandi, Ferdiansyah Iqbal

2018-04-01

Microwave assisted heating has been extensively used in materials processing particularly in extraction of TiO2 from Ilmenite (FeTiO3) minerals. Nevertheless, this method could generate non-uniform temperature distribution during the heating process. The observation of this phenomena in cylindrical ilmenite has been conducted by numerical simulation using finite element method according to the Poynthing's theorem. Four different cylinders with variation on its height were simulated in ANSYS 17 with input microwave power of 5.5 Kw. The results indicated that height of heated object could vigorously influence the uniformity of temperature inside the body.

Low-temperature aqueous alteration on the CR chondrite parent body: Implications from in situ oxygen-isotope analyses

NASA Astrophysics Data System (ADS)

Jilly-Rehak, Christine E.; Huss, Gary R.; Nagashima, Kazu; Schrader, Devin L.

2018-02-01

The presence of hydrated minerals in chondrites indicates that water played an important role in the geologic evolution of the early Solar System; however, the process of aqueous alteration is still poorly understood. Renazzo-like carbonaceous (CR) chondrites are particularly well-suited for the study of aqueous alteration. Samples range from being nearly anhydrous to fully altered, essentially representing snapshots of the alteration process through time. We studied oxygen isotopes in secondary-minerals from six CR chondrites of varying hydration states to determine how aqueous fluid conditions (including composition and temperature) evolved on the parent body. Secondary minerals analyzed included calcite, dolomite, and magnetite. The O-isotope composition of calcites ranged from δ18O ≈ 9 to 35‰, dolomites from δ18O ≈ 23 to 27‰, and magnetites from δ18O ≈ -18 to 5‰. Calcite in less-altered samples showed more evidence of fluid evolution compared to heavily altered samples, likely reflecting lower water/rock ratios. Most magnetite plotted on a single trend, with the exception of grains from the extensively hydrated chondrite MIL 090292. The MIL 090292 magnetite diverges from this trend, possibly indicating an anomalous origin for the meteorite. If magnetite and calcite formed in equilibrium, then the relative 18O fractionation between them can be used to extract the temperature of co-precipitation. Isotopic fractionation in Al Rais carbonate-magnetite assemblages revealed low precipitation temperatures (∼60 °C). Assuming that the CR parent body experienced closed-system alteration, a similar exercise for parallel calcite and magnetite O-isotope arrays yields "global" alteration temperatures of ∼55 to 88 °C. These secondary mineral arrays indicate that the O-isotopic composition of the altering fluid evolved upon progressive alteration, beginning near the Al Rais water composition of Δ17O ∼ 1‰ and δ18O ∼ 10‰, and becoming increasingly 16O-enriched toward a final fluid composition of Δ17O ∼ -1.2‰ and δ18O ∼ -15‰.

Study of Some Mineral Exchangers for Use in Water at High Temperature; ETUDE DE QUELQUES ECHANGEURS MINERAUX UTILISABLES DANS L'EAU A HAUTE TEMPERATURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hure, J.; Platzer, R.; Bittel, R.

1959-10-31

The study of the use of ion exchangers at high temperatures was made with a view to the purification of water in reactors. Natural ion exchangers with mineral structures (clay of the montmorillonite type), natural mineral compounds so treated as to give them the properties of ion exchangers (activated graphite), and synthetic mineral compounds (zirconium phosphates and hydroxides and thorium hydroxide) were investigated. The preparation of the minerals is described, and the results obtained with them are discussed in detail. (J.S.R.)

Strong catalytic activity of iron nanoparticles on the surfaces of reduced olivine

NASA Astrophysics Data System (ADS)

Tucker, William C.; Quadery, Abrar H.; Schulte, Alfons; Blair, Richard G.; Kaden, William E.; Schelling, Patrick K.; Britt, Daniel T.

2018-01-01

It is demonstrated that olivine powders heated to subsolidus temperatures in reducing conditions can develop significant concentrations of 10-50 nm diameter Fe nanoparticles on grain surfaces and that these display strong catalytic activity not observed in powders without Fe nanoparticles. Reduced surfaces were exposed to NH3, CO, and H2, volatiles that may be present on the surfaces of comet and volatile-rich asteroids. In the case of NH3 exposure, rapid decomposition was observed. When exposed to a mixture of CO and H2, significant coking of the mineral surfaces occurred. Analysis of the mineral grains after reaction indicated primarily the presence of graphene or graphitic carbon. The results demonstrate that strong chemical activity can be expected at powders that contain nanophase Fe particles. This suggests space-weathered mineral surfaces may play an important role in the synthesis and processing of organic species. This processing may be part of the weathering processes of volatile-rich but atmosphereless solar-system bodies.

Geodiversity of hydrothermal processes along the Mid-Atlantic Ridge and ultramafic-hosted mineralization: A new type of oceanic Cu-Zn-Co-Au volcanogenic massive sulfide deposit

NASA Astrophysics Data System (ADS)

Fouquet, Yves; Cambon, Pierre; Etoubleau, Joël; Charlou, Jean Luc; Ondréas, Hélène; Barriga, Fernando J. A. S.; Cherkashov, Georgy; Semkova, Tatiana; Poroshina, Irina; Bohn, M.; Donval, Jean Pierre; Henry, Katell; Murphy, Pamela; Rouxel, Olivier

Several hydrothermal deposits associated with ultramafic rocks have recently been found along slow spreading ridges with a low magmatic budget. Three preferential settings are identified: (1) rift valley walls near the amagmatic ends of ridge segments; (2) nontransform offsets; and (3) ultramafic domes at inside corners of ridge transform-fault intersections. The exposed mantle at these sites is often interpreted to be a detachment fault. Hydrothermal cells in ultramafic rocks may be driven by regional heat flow, cooling gabbroic intrusions, and exothermic heat produced during serpentinization. Along the Mid-Atlantic Ridge (MAR), hydrothermal deposits in ultramafic rocks include the following: (1) sulfide mounds related to high-temperature low-pH fluids (Logatchev, Rainbow, and Ashadze); (2) carbonate chimneys related to low-temperature, high-pH fluids (Lost City); (3) low-temperature diffuse venting and high-methane discharge associated with silica, minor sulfides, manganese oxides, and pervasive alteration (Saldanha); and (4) stockwork quartz veins with sulfides at the base of detachment faults (15°05'N). These settings are closely linked to preferential circulation of fluid along permeable detachment faults. Compared to mineralization in basaltic environments, sulfide deposits associated with ultramafic rocks are enriched in Cu, Zn, Co, Au, and Ni. Gold has a bimodal distribution in low-temperature Zn-rich and in high-temperature Cu-rich mineral assemblages. The Cu-Zn-Co-Au deposits along the MAR seem to be more abundant than in ophiolites on land. This may be because ultramafic-hosted volcanogenic massive sulfide deposits on slow spreading ridges are usually not accreted to continental margins during obduction and may constitute a specific marine type of mineralization.

Mineral Surface Rearrangement at High Temperatures: Implications for Extraterrestrial Mineral Grain Reactivity.

PubMed

King, Helen E; Plümper, Oliver; Putnis, Christine V; O'Neill, Hugh St C; Klemme, Stephan; Putnis, Andrew

2017-04-20

Mineral surfaces play a critical role in the solar nebula as a catalytic surface for chemical reactions and potentially acted as a source of water during Earth's accretion by the adsorption of water molecules to the surface of interplanetary dust particles. However, nothing is known about how mineral surfaces respond to short-lived thermal fluctuations that are below the melting temperature of the mineral. Here we show that mineral surfaces react and rearrange within minutes to changes in their local environment despite being far below their melting temperature. Polished surfaces of the rock and planetary dust-forming silicate mineral olivine ((Mg,Fe) 2 SiO 4 ) show significant surface reorganization textures upon rapid heating resulting in surface features up to 40 nm in height observed after annealing at 1200 °C. Thus, high-temperature fluctuations should provide new and highly reactive sites for chemical reactions on nebula mineral particles. Our results also may help to explain discrepancies between short and long diffusion profiles in experiments where diffusion length scales are of the order of 100 nm or less.

Temperature Dependence and Recoil-free Fraction Effects in Olivines Across the Mg-Fe Solid Solution

NASA Technical Reports Server (NTRS)

Sklute, E. C.; Rothstein, Y.; Dyar, M. D.; Schaefer, M. W.; Menzies, O. N.; Bland, P. A.; Berry, F. J.

2005-01-01

Olivine and pyroxene are the major ferromagnesian minerals in most meteorite types and in mafic igneous rocks that are dominant at the surface of the Earth. It is probable that they are the major mineralogical components at the surface of any planetary body that has undergone differentiation processes. In situ mineralogical studies of the rocks and soils on Mars suggest that olivine is a widespread mineral on that planet s surface (particularly at the Gusev site) and that it has been relatively unaffected by alteration. Thus an understanding of the characteristics of Mossbauer spectra of olivine is of great importance in interpreting MER results. However, variable temperature Mossbauer spectra of olivine, which are needed to quantify recoil-free fraction effects and to understand the temperature dependence of olivine spectra, are lacking in the literature. Thus, we present here a study of the temperature dependence and recoil-free fraction of a series of synthetic olivines.

Evidence for interfacial dissolution-precipitation during low-temperature mineral weathering

NASA Astrophysics Data System (ADS)

Ruiz-Agudo, Encarnacion; Putnis, Christine V.; Rodriguez-Navarro, Carlos; Putnis, Andrew

2013-04-01

The dissolution of most common multicomponent minerals and glasses is typically "incongruent" as shown by the nonstoichiometric release of the solid phase components. This frequently results in the formation of so-called surface leached layers. The mechanism of this process has been a recurrent subject of research and debate over the past two decades, due to its relevance to a wide range of natural and technological processes, as well as being crucial in defining rate laws for mineral reactions. Here we report experimental, in situ nanoscale observations that confirm the formation of a cation depleted layer at the mineral-solution interface during dissolution of multicomponent minerals at acidic pH. Our in situ Atomic Force Microscopy studies of the dissolution of wollastonite, CaSiO3, and dolomite, Ca0.5Mg0.5CO3, combined with compositional analysis of reaction products, provide, for the first time, clear direct experimental evidence that cation-depleted (i.e. leached) layers are formed in a tight interface-coupled two step process: stoichiometric dissolution of the pristine mineral surfaces and subsequent precipitation of a secondary phase from a supersaturated boundary layer of fluid in contact with the mineral surface. Such a mechanism presents a new paradigm that differs from the concept of preferential leaching of cations, as postulated by most currently accepted incongruent dissolution models. References Ruiz Agudo, E; Putnis, CV; Rodríguez Navarro, C and Putnis, A. (2012) Mechanism of leached layer formation during chemical weathering of silicate minerals. Geology, 40, 947-950 Urosevic, M; Rodríguez Navarro,C; Putnis, CV; Cardell, C; Putnis, A and Ruiz Agudo, E (2012) In situ nanoscale observations of the dissolution of [10-14] dolomite cleavage surfaces. Geochimica et Cosmochimica Acta, 80, 1-13

Wavelength feature mapping as a proxy to mineral chemistry for investigating geologic systems: An example from the Rodalquilar epithermal system

NASA Astrophysics Data System (ADS)

van der Meer, Freek; Kopačková, Veronika; Koucká, Lucie; van der Werff, Harald M. A.; van Ruitenbeek, Frank J. A.; Bakker, Wim H.

2018-02-01

The final product of a geologic remote sensing data analysis using multi spectral and hyperspectral images is a mineral (abundance) map. Multispectral data, such as ASTER, Landsat, SPOT, Sentinel-2, typically allow to determine qualitative estimates of what minerals are in a pixel, while hyperspectral data allow to quantify this. As input to most image classification or spectral processing approach, endmembers are required. An alternative approach to classification is to derive absorption feature characteristics such as the wavelength position of the deepest absorption, depth of the absorption and symmetry of the absorption feature from hyperspectral data. Two approaches are presented, tested and compared in this paper: the 'Wavelength Mapper' and the 'QuanTools'. Although these algorithms use a different mathematical solution to derive absorption feature wavelength and depth, and use different image post-processing, the results are consistent, comparable and reproducible. The wavelength images can be directly linked to mineral type and abundance, but more importantly also to mineral chemical composition and subtle changes thereof. This in turn allows to interpret hyperspectral data in terms of mineral chemistry changes which is a proxy to pressure-temperature of formation of minerals. We show the case of the Rodalquilar epithermal system of the southern Spanish Gabo de Gata volcanic area using HyMAP airborne hyperspectral images.

Coal Combustion Science quarterly progress report, April--June 1992. Task 1, Coal devolatilization: Task 2, Coal char combustion; Task 3, Fate of mineral matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardesty, D.R.; Hurt, R.H.; Baxter, L.L.

1992-09-01

The objective of this work is to support the Office of Fossil Energy in executing research on coal combustion science. This project consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center (PETC) Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency (IEA) Coal Combustion Science Project. Specific tasks include: The characterization of the physical and chemical processes that constitute the early devolatilization phase of coal combustion: Characterization of the combustion behavior of selected coals under conditions relevant to industria pulverized coal-fired furnaces; and to establish a quantitative understanding of themore » mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distributions of mineral species in the unreacted coal, and the local gas temperature and composition.« less

Decoupling of microbial carbon, nitrogen, and phosphorus cycling in response to extreme temperature events

PubMed Central

Mooshammer, Maria; Hofhansl, Florian; Frank, Alexander H.; Wanek, Wolfgang; Hämmerle, Ieda; Leitner, Sonja; Schnecker, Jörg; Wild, Birgit; Watzka, Margarete; Keiblinger, Katharina M.; Zechmeister-Boltenstern, Sophie; Richter, Andreas

2017-01-01

Predicted changes in the intensity and frequency of climate extremes urge a better mechanistic understanding of the stress response of microbially mediated carbon (C) and nutrient cycling processes. We analyzed the resistance and resilience of microbial C, nitrogen (N), and phosphorus (P) cycling processes and microbial community composition in decomposing plant litter to transient, but severe, temperature disturbances, namely, freeze-thaw and heat. Disturbances led temporarily to a more rapid cycling of C and N but caused a down-regulation of P cycling. In contrast to the fast recovery of the initially stimulated C and N processes, we found a slow recovery of P mineralization rates, which was not accompanied by significant changes in community composition. The functional and structural responses to the two distinct temperature disturbances were markedly similar, suggesting that direct negative physical effects and costs associated with the stress response were comparable. Moreover, the stress response of extracellular enzyme activities, but not that of intracellular microbial processes (for example, respiration or N mineralization), was dependent on the nutrient content of the resource through its effect on microbial physiology and community composition. Our laboratory study provides novel insights into the mechanisms of microbial functional stress responses that can serve as a basis for field studies and, in particular, illustrates the need for a closer integration of microbial C-N-P interactions into climate extremes research. PMID:28508070

Bioactive and Porous Metal Coatings for Improved Tissue Regeneration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, A. A.

Our first objective was to develop the SIM process for the deposition of calcium phosphate films. This process is based on the observation that, in nature, living organisms use macromolecules to control the nucleation and growth of mineral phases. These macromolecules act as templates where various charged functional groups, contained within the molecule, can interact with the ions in the surrounding media, thus stimulating crystal nucleation and growth. Rather than using complex proteins or biopolymers, surface modification schemes were developed to place simple functional groups on the underlying substrate using self-assembling monolayers. Once the substrate was chemically modified, it wasmore » then placed into an aqueous solution containing soluble precursors of the desired mineral coating. Solution pH, ionic concentration and temperature is maintained in a regime where the solution is supersaturated with respect to the desired mineral phase, thereby creating the driving force for nucleation and growth.« less

Disentangling controls on mineral-stabilized soil organic matter using a slurry incubation

NASA Astrophysics Data System (ADS)

Lavallee, J. M.; Cotrufo, M. F.; Paul, E. A.; Conant, R. T.

2014-12-01

Mineral-stabilized organic matter (OM) is the largest and oldest pool of soil carbon and nitrogen. Mineral stabilization limits OM availability to soil microbes, preventing its decomposition and prolonging its turnover. Thus, understanding controls on the decomposition of mineral-stabilized OM is key to understanding soil carbon and nitrogen dynamics. The very slow turnover of mineral-stabilized OM makes it challenging to study in a typical incubation, and as a result, many potential controls (temperature, OM chemistry, and mineralogy) on its turnover remain unclear. We aimed to better understand controls on decomposition of mineral-stabilized OM by employing a slurry incubation technique, which speeds up microbial processing of OM by maximizing OM accessibility to microbes. In a slurry incubation, we expect that any OM that is not stabilized on mineral surfaces will be available for decomposition and will be converted to CO2. Using this technique, we studied the interactive effects of incubation temperature, plant material type (aboveground vs. belowground), and soil fraction (silt vs. clay) on CO2 efflux and OM stabilization. We separated silt-sized and clay-sized fractions from an agricultural soil, added aboveground or belowground plant material to each, and incubated them at 15°C, 25°C and 35°C. The added plant material was isotopically labeled (13C and 15N), which allowed us to trace it through the system and distinguish between the responses of the new (derived from the plant material) and old (derived from what was already present in the silt and clay) OM to warming. We measured CO2 efflux and 13CO2 efflux throughout the incubation. We performed one short-term harvest at day 6 and one final harvest at day 60. Initial results show higher cumulative CO2 efflux at warmer temperatures regardless of plant material type or soil fraction. A larger fraction of that CO2 came from OM that was initially present in the silt and clay, rather than from the plant material that we added, which suggests faster turnover of that "old" OM at warmer temperatures. We will present CO2 efflux data in addition to total [C] and [N] and the isotopic ratios of 13C and 15N in the silt and clay at each harvest to explain how the interactions between warming, plant material type and soil fraction affect turnover of mineral stabilized OM.

Formation of CaS-MgS in Enstatite Chondrites and Achondrites as a Function of Redox Conditions and Temperature: Constraints on Their Evolution in a Planetesimal and in a Proto-planet

NASA Technical Reports Server (NTRS)

Malavergne, Valerie; Berthet, S.; Righter, K.

2007-01-01

The cubic monosulfide series with the general formula (Mg,Mn,Ca,Fe)S are common phases in the enstatite chondrite (EH) and aubrite meteorite groups. In the Earth s mantle, sulfide minerals are associated with peridotites and eclogites. Study of these sulfide mineral systems is of interest for the mineralogy and petrology of planetary mantles. For example, MgS could occur in the primitive Earth and because it remains a low density phase compared to metal, would stay a separate phase during the core formation process, and thus not segregate to the core. (Mg,Ca,Mn,Fe)S sulphides might thus be important phases even in planetary differentiation processes. The importance of such minerals, and their formation, composition and textural relationships for understanding the genesis of enstatite chondrites and aubrites, has long been recognized. The main objective of this experimental study is to understand the formation and evolution of (Mg,Ca,Mn,Fe)S sulphides, particularly the oldhamite CaS and ningerite MgS, with pressure, temperature but also with redox conditions because EH and aubrites are meteorites that formed under reduced conditions. Piston-cylinder (PC) and multi-anvil (MA) experiments at high pressure (HP) and high temperature (HT) have been performed in order to simulate the evolution of these phases in a small planetary body from a planetesimal (with PC experiments) up to a proto-planet (with MA experiments).

Influence of heating on the weight loss and mineral phase in MSWI ash: LOI of incineration ash

NASA Astrophysics Data System (ADS)

Yang, Shuo

2017-04-01

Loss on ignition (LOI) is a very common method for estimating the volatile species in solid sample. Normally, the measurement of LOI can be convenient and accurate, but for municipal solid waste incineration (MSWI) ash, the process may become intricate due to the complexity of the sample. In the incineration ash, there exist various phases, such as mineral, metal, organic and glass. The reaction and transformation of some materials during heating will influence the measurement. 5 incineration ash samples were selected and tested in this study. LOI content was basically measured at high (850°C) and relatively low (440°C) temperatures. The comparison between these two measurements showed a large difference. X-ray diffraction (XRD) and thermal analysis (TG-DTA) were carried out to investigate the mineral changes and weight losses with different ignition temperatures. The mineralogical analysis suggests that the decomposition of hydrate and carbonate phases cannot be neglected for LOI measurement of incineration. A long-time heating under relatively lower temperature (400∼450°C) compared with soil sample measurement (≥500°C) was recommended by this study.

The role of extremophile in the redox reaction of Fe and As relating with the formation of secondary phase mineral in extreme environment, Norris Geyser Basin, Yellowstone National Park, USA

NASA Astrophysics Data System (ADS)

Koo, T. H.; Kim, J. Y.; Park, K. R.; Jung, D. H.; Geesey, G. G.; Kim, J. W.

2015-12-01

Redox reaction associated with microbial elemental respiration is a ubiquitous process in sediments and suspended particles at various temperatures or pH/Eh conditions. Particularly, changes in elemental redox states (structural or dissolved elemental form) induced by microbial respiration result in the unexpected biogeochemical reactions in the light of biotic/abiotic mineralization. The objective of the present study is, therefore to investigate the secondary phase mineralization through a-/biogeochemical Fe and As redox cycling in the acido-hyperhtermal Norris Geyser Basin (NGB) in Yellowstone National Park, USA, typical of the extreme condition. X-ray diffraction, scanning electron microscope with energy dispersive x-ray spectroscopy, X-ray absorption near edge structure, inductively coupled plasma-atomic emission spectrometer and liquid chromatography with ICP-mass spectroscopy with filtrated supernatant were performed for the mineralogical and hydro-geochemical analysis. The clay slurry collected from the active hot-spring of the NGB area (pH=3.5 and Temperature=78 ℃) was incubated with ("enrichment") or without the growth medium ("natural"). The control was prepared in the same condition except adding the glutaraldehyde to eliminate the microbial activity. The secondary phase mineral formation of the oxidative phase of Fe and As, and K identified as 'Pharmacosiderite' only appeared in the enrichment set suggesting a role of extremophiles in the mineral formation. The considerable population of Fe-oxidizer (Metallosphera yellowstonensis MK-1) and As-oxidizer (Sulfurihydrogenibium sp.) was measured by phylogenetic analysis in the present study area. The inhibition of As-oxidation in the low pH conditions was reported in the previous study, however the As-redox reaction was observed and consequently, precipitated the Pharmacosiderite only in the enrichment set suggesting a biotic mineralization. The present study collectively suggests that the microbial activity may bypass the chemical or thermodynamical reaction barriers and promote the secondary phase mineral formation through the elemental respiration. The possible biotic/abiotic mechanism or process in mineral alteration/formation in extreme environment will be discussed.

Post-shock temperatures in minerals

NASA Technical Reports Server (NTRS)

Raikes, S. A.; Ahrens, T. J.

1979-01-01

An experimental technique was developed for measuring post-shock temperatures in a wide variety of materials, including those of geophysical interest such as silicates. The technique uses an infrared radiation detector to determine the brightness temperature of samples shocked to pressures in the range 5 to approximately 30 GPa; in these experiments measurements were made in two wavelength ranges (4.5 to 5.75 microns and 7 to 14 microns). Reproducible results, with the temperatures in the two wavelength bands generally in excellent agreement, were obtained for aluminum-2024 (10.5 to 33 GPa, 125 to 260 C), stainless steel-304 (11.5 to 50 GPa, 80 to 350 C), crystalline quartz (5.0 to 21.5 GPa, 80 to 250 C), forsterite (7.5 to 28.0 GPa, approximately 30 to 160 C) and Bamble bronzite (6.0 to 26.0 GPa, approximately 30 to 225 C). It is concluded that release adiabat data should be used, wherever available, for calculations of residual temperature, and that adequate descriptions of the shock and release processes in minerals are more complex than generally assumed.

Iron isotope fractionation during hydrothermal ore deposition and alteration

NASA Astrophysics Data System (ADS)

Markl, Gregor; von Blanckenburg, Friedhelm; Wagner, Thomas

2006-06-01

Iron isotopes fractionate during hydrothermal processes. Therefore, the Fe isotope composition of ore-forming minerals characterizes either iron sources or fluid histories. The former potentially serves to distinguish between sedimentary, magmatic or metamorphic iron sources, and the latter allows the reconstruction of precipitation and redox processes. These processes take place during ore formation or alteration. The aim of this contribution is to investigate the suitability of this new isotope method as a probe of ore-related processes. For this purpose 51 samples of iron ores and iron mineral separates from the Schwarzwald region, southwest Germany, were analyzed for their iron isotope composition using multicollector ICP-MS. Further, the ore-forming and ore-altering processes were quantitatively modeled using reaction path calculations. The Schwarzwald mining district hosts mineralizations that formed discontinuously over almost 300 Ma of hydrothermal activity. Primary hematite, siderite and sulfides formed from mixing of meteoric fluids with deeper crustal brines. Later, these minerals were partly dissolved and oxidized, and secondary hematite, goethite and iron arsenates were precipitated. Two types of alteration products formed: (1) primary and high-temperature secondary Fe minerals formed between 120 and 300 °C, and (2) low-temperature secondary Fe minerals formed under supergene conditions (<100 °C). Measured iron isotope compositions are variable and cover a range in δ56Fe between -2.3‰ and +1.3‰. Primary hematite ( δ56Fe: -0.5‰ to +0.5‰) precipitated by mixing oxidizing surface waters with a hydrothermal fluid that contained moderately light Fe ( δ56Fe: -0.5‰) leached from the crystalline basement. Occasional input of CO 2-rich waters resulted in precipitation of isotopically light siderite ( δ56Fe: -1.4 to -0.7‰). The difference between hematite and siderite is compatible with published Fe isotope fractionation factors. The observed range in isotopic compositions can be accounted for by variable fractions of Fe precipitating from the fluid. Therefore, both fluid processes and mass balance can be inferred from Fe isotopes. Supergene weathering of siderite by oxidizing surface waters led to replacement of isotopically light primary siderite by similarly light secondary hematite and goethite, respectively. Because this replacement entails quantitative transfer of iron from precursor mineral to product, no significant isotope fractionation is produced. Hence, Fe isotopes potentially serve to identify precursors in ore alteration products. Goethites from oolitic sedimentary iron ores were also analyzed. Their compositional range appears to indicate oxidative precipitation from relatively uniform Fe dissolved in coastal water. This comprehensive iron isotope study illustrates the potential of the new technique in deciphering ore formation and alteration processes. Isotope ratios are strongly dependent on and highly characteristic of fluid and precipitation histories. Therefore, they are less suitable to provide information on Fe sources. However, it will be possible to unravel the physico-chemical processes leading to the formation, dissolution and redeposition of ores in great detail.

Chemical environments of submarine hydrothermal systems. [supporting abiogenetic theory

NASA Technical Reports Server (NTRS)

Shock, Everett L.

1992-01-01

The paper synthesizes diverse information about the inorganic geochemistry of submarine hydrothermal systems, provides a description of the fundamental physical and chemical properties of these systems, and examines the implications of high-temperature, fluid-driven processes for organic synthesis. Emphasis is on a few general features, i.e., pressure, temperature, oxidation states, fluid composition, and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

Weathering profiles in soils and rocks on Earth and Mars

NASA Astrophysics Data System (ADS)

Hausrath, E.; Adcock, C. T.; Bamisile, T.; Baumeister, J. L.; Gainey, S.; Ralston, S. J.; Steiner, M.; Tu, V.

2017-12-01

Interactions of liquid water with rock, soil, or sediments can result in significant chemical and mineralogical changes with depth. These changes can include transformation from one phase to another as well as translocation, addition, and loss of material. The resulting chemical and mineralogical depth profiles can record characteristics of the interacting liquid water such as pH, temperature, duration, and abundance. We use a combined field, laboratory, and modeling approach to interpret the environmental conditions preserved in soils and rocks. We study depth profiles in terrestrial field environments; perform dissolution experiments of primary and secondary phases important in soil environments; and perform numerical modeling to quantitatively interpret weathering environments. In our field studies we have measured time-integrated basaltic mineral dissolution rates, and interpreted the impact of pH and temperature on weathering in basaltic and serpentine-containing rocks and soils. These results help us interpret fundamental processes occurring in soils on Earth and on Mars, and can also be used to inform numerical modeling and laboratory experiments. Our laboratory experiments provide fundamental kinetic data to interpret processes occurring in soils. We have measured dissolution rates of Mars-relevant phosphate minerals, clay minerals, and amorphous phases, as well as dissolution rates under specific Mars-relevant conditions such as in concentrated brines. Finally, reactive transport modeling allows a quantitative interpretation of the kinetic, thermodynamic, and transport processes occurring in soil environments. Such modeling allows the testing of conditions under longer time frames and under different conditions than might be possible under either terrestrial field or laboratory conditions. We have used modeling to examine the weathering of basalt, olivine, carbonate, phosphate, and clay minerals, and placed constraints on the duration, pH, and solution chemistry of past aqueous alteration occurring on Mars.

Copper isotopic zonation in the Northparkes porphyry Cu-Au deposit, SE Australia

NASA Astrophysics Data System (ADS)

Li, Weiqiang; Jackson, Simon E.; Pearson, Norman J.; Graham, Stuart

2010-07-01

Significant, systematic Cu isotopic variations have been found in the Northparkes porphyry Cu-Au deposit, NSW, Australia, which is an orthomagmatic porphyry Cu deposit. Copper isotope ratios have been measured in sulfide minerals (chalcopyrite and bornite) by both solution and laser ablation multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). The results from both methods show a variation in δ 65Cu of hypogene sulfide minerals of greater than 1‰ (relative to NIST976). Significantly, the results from four drill holes through two separate ore bodies show strikingly similar patterns of Cu isotope variation. The patterns are characterized by a sharp down-hole decrease from up to 0.8‰ (0.29 ± 0.56‰, 1 σ, n = 20) in the low-grade peripheral alteration zones (phyllic-propylitic alteration zone) to a low of ˜-0.4‰ (-0.25 ± 0.36‰, 1 σ, n = 30) at the margins of the most mineralized zones (Cu grade >1 wt%). In the high-grade cores of the systems, the compositions are more consistent at around 0.2‰ (0.19 ± 0.14‰, 1 σ, n = 40). The Cu isotopic zonation may be explained by isotope fractionation of Cu between vapor, solution and sulfides at high temperature, during boiling and sulfide precipitation processes. Sulfur isotopes also show an isotopically light shell at the margins of the high-grade ore zones, but these are displaced from the low δ 65Cu shells, such that there is no correlation between the Cu and S isotope signatures. Fe isotope data do not show any discernable variation along the drill core. This work demonstrates that Cu isotopes show a large response to high-temperature porphyry mineralizing processes, and that they may act as a vector to buried mineralization.

Laboratory Investigation on Physical and Mechanical Properties of Granite After Heating and Water-Cooling Treatment

NASA Astrophysics Data System (ADS)

Zhang, Fan; Zhao, Jianjian; Hu, Dawei; Skoczylas, Frederic; Shao, Jianfu

2018-03-01

High-temperature treatment may cause changes in physical and mechanical properties of rocks. Temperature changing rate (heating, cooling and both of them) plays an important role in those changes. Thermal conductivity tests, ultrasonic pulse velocity tests, gas permeability tests and triaxial compression tests are performed on granite samples after a heating and rapid cooling treatment in order to characterize the changes in physical and mechanical properties. Seven levels of temperature (from 25 to 900 °C) are used. It is found that the physical and mechanical properties of granite are significantly deteriorated by the thermal treatment. The porosity shows a significant increase from 1.19% at the initial state to 6.13% for samples heated to 900 °C. The increase in porosity is mainly due to three factors: (1) a large number of microcracks caused by the rapid cooling rate; (2) the mineral transformation of granite through high-temperature heating and water-cooling process; (3) the rapid cooling process causes the mineral particles to weaken. As the temperature of treatment increases, the thermal conductivity and P-wave velocity decrease while the gas permeability increases. Below 200 °C, the elastic modulus and cohesion increase with temperature increasing. Between 200 and 500 °C, the elastic modulus and cohesion have no obvious change with temperature. Beyond 500 °C, as the temperature increases, the elastic modulus and cohesion obviously decrease and the decreasing rate becomes slower with the increase in confining pressure. Poisson's ratio and internal frictional coefficient have no obvious change as the temperature increases. Moreover, there is a transition from a brittle to ductile behavior when the temperature becomes high. At 900 °C, the granite shows an obvious elastic-plastic behavior.

Biologically controlled minerals as potential indicators of life

NASA Technical Reports Server (NTRS)

Schwartz, D. E.; Mancinelli, R. L.; Kaneshiro, E.

1991-01-01

Minerals can be produced and deposited either by abiotic or biologic means. Regardless of their origin, mineral crystals reflect the environment conditions (e.g., temperature, pressure, chemical composition, and redox potential) present during crystal formation. Biologically-produced mineral crystals are grown or reworked under the control of their host organism and reflect an environment different from the abiotic environment. In addition, minerals of either biologic or abiotic origin have great longevities. For these reasons, biologically produced minerals have been proposed as biomarkers. Biomarkers are key morphological, chemical, and isotopic signatures of living systems that can be used to determine if life processes have occurred. Studies of biologically controlled minerals produced by the protist, Paramecium tetraurelia, were initiated since techniques have already been developed to culture them and isolate their crystalline material, and methods are already in place to analyze this material. Two direct crystalline phases were identified. One phase, whose chemical composition is high in Mg, was identified as struvite. The second phase, whose chemical composition is high in Ca, has not been previously found occurring naturally and may be considered a newly discovered material. Analyses are underway to determine the characteristics of these minerals in order to compare them with characteristics of these minerals in order to compare them with characteristics of minerals formed abiotically, but with the same chemical composition.

Stable mineral recrystallization in low temperature aqueous systems: A critical review

NASA Astrophysics Data System (ADS)

Gorski, Christopher A.; Fantle, Matthew S.

2017-02-01

Minerals may undergo recrystallization reactions in low temperature (<100 °C) aqueous systems, during which they exchange isotopes and trace elements with the dissolved reservoir without undergoing overt structural, bulk compositional, or morphological changes. These interfacial reactions, which are often referred to in the literature as "atom exchange" and herein as "stable mineral recrystallization", have important implications for the use of isotopic and elemental proxies to interpret past temperatures, oxidation states, and aqueous chemistries on Earth. The reactions are also significant for modern environments, including engineered systems, as they imply that mineral lattices may be substantially more open to exchanging toxic elements and radionuclides with coexisting solutions than previously thought. To date, observations of stable mineral recrystallization are distributed among several disciplines, and no work has attempted to review their findings comprehensively. Accordingly, this review article presents laboratory evidence for stable mineral recrystallization, describes data collection and interpretation strategies, summarizes similar recrystallization systematics observed in multiple studies, explores the potential occurrence of stable mineral recrystallization in natural systems, and discusses possible mechanisms by which stable mineral recrystallization occurs. The review focuses primarily on carbonates, sulfates, and iron oxides because these minerals have been studied most extensively to date. The review concludes by presenting key questions that should be addressed in this field to further understand and account for stable mineral recrystallization in natural and engineered aqueous systems at low temperatures.

Toward a mechanism-based understanding of skeletal formation: Toolbox for biomineralization past, present, and future

NASA Astrophysics Data System (ADS)

Dove, P. M.; Wallace, A. F.; Stephenson, A. E.; Wang, D. E.; Hamm, L.; de Yoreo, J. J.

2008-05-01

Since the onset of the Cambrian radiation (~540 Ma), organisms have developed the ability to control the nucleation and growth of amorphous and crystalline earth materials to form skeletal structures. Observations that similar skeletal materials are utilized across multiple branches on the eukaryotic tree of life are cited as evidence that biomineralization strategies evolved independently by similar biochemical pathways that developed early in evolutionary history (A. Knoll). An understanding of these relations is critical to deciphering earth history, yet until recently, studies of biomineral formation were primarily based upon descriptive approaches focused on morphology. Insights into mineralization processes were inferred largely from macroscopic experiments and structural characterizations. Over the last ten years, we have pursued the long-term goal of establishing a mechanistic understanding of biologically controlled mineralization. Through molecular-scale studies of calcium carbonate growth using in situ atomic force microscopy and computational methods, our approach has been to design simple model systems that link direct measurements of growth with the underlying chemical interactions. Recent additions to the toolbox of insights for mineral formation and compositional signatures include: 1) Shape is a kinetic effect of differential energy barriers to solute attachment/detachment and stereochemical relationships between crystal and growth modifier.; 2) From simple amino acids to peptides and full proteins, acidic biomolecules enhance mineralization rate up to 25X by a systematic relation. This suggests a functional role for aspartate- and glutamate-enriched macromolecules long-known to be associated with calcification.; 3) Acidic biomolecules promote uptake of impurities such as magnesium by 2-3 mol%. This enhancement corresponds to a temperature difference of 7- 14°C in proxy models that correlate Mg content with temperature. Anecdotal evidence suggests water structure in confined biomineralization environments may have important, yet-unrecognized roles in biomolecule-solute- mineral interactions. With the realization that biogenic minerals often form by nonclassical processes from amorphous precursors, new studies are focused on establishing factors that drive the transformation of intermediate phases to final biomineral products. By developing model systems to probe how biological substrates can modulate the onset of mineral formation, we are working to establish 1) Principles of mineral formation by nonclassical processes and influences on resultant signatures; 2) Thermodynamic and kinetic role(s) of the organic matrix as a trigger/inhibitor to the timing and location of mineral formation; and 3) Interplay of solvation and organic matrix in polymorph selection. The next 10 years promise to be an exciting time of uncovering how skeletal formation is modulated by a rich biochemical machinery at sites of mineralization while also providing insights to phylogenetic relations.

Comparing the ice nucleation efficiencies of ice nucleating substrates to natural mineral dusts

NASA Astrophysics Data System (ADS)

Steinke, Isabelle; Funk, Roger; Höhler, Kristina; Haarig, Moritz; Hoffmann, Nadine; Hoose, Corinna; Kiselev, Alexei; Möhler, Ottmar; Leisner, Thomas

2014-05-01

Mineral dust particles in the atmosphere may act as efficient ice nuclei over a wide range of temperature and relative humidity conditions. The ice nucleation capability of dust particles mostly depends on the particle surface area and the associated physico-chemical surface properties. It has been observed that the surface-related ice nucleation efficiency of different dust particles and mineral species can vary by several orders of magnitude. However, the relation between aerosol surface properties and observed ice nucleation efficiency is still not completely understood due to the large variability of chemical compositions and morphological features. In order to gain a better understanding of small scale freezing processes, we investigated the freezing of several hundreds of small droplets (V=0.4 nl) deposited on materials with reasonably well defined surfaces such as crystalline silicon wafers, graphite and freshly cleaved mica sheets under atmospherically relevant conditions. These substrates are intended to serve as simple model structures compared to the surface of natural aerosol particles. To learn more about the impact of particle morphology on ice nucleation processes, we also investigated micro-structured silicon wafers with prescribed trenches. The ice nucleation efficiencies deduced from these experiments are expressed as ice nucleation active surface site density values. With this approach, the freezing properties of the above-described substrates could be compared to those of natural mineral dusts such as agricultural soil dusts, volcanic ash and fossil diatoms, which have been investigated in AIDA cloud chamber experiments. All tested ice nucleating substrates were consistently less efficient at nucleating ice than the natural mineral dusts. Crystalline silicon only had a negligible influence on the freezing of small droplets, leading to freezing near the homogeneous freezing temperature threshold. Applying surface structures to silicon led to a shift towards heterogeneous freezing. However, the measured ice nucleation active surface site densities were still smaller than those of mineral dusts.

Small scale changes of geochemistry and flow field due to transient heat storage in aquifers

NASA Astrophysics Data System (ADS)

Bauer, S.; Boockmeyer, A.; Li, D.; Beyer, C.

2013-12-01

Heat exchangers in the subsurface are increasingly installed for transient heat storage due to the need of heating or cooling of buildings as well as the interim storage of heat to compensate for the temporally fluctuating energy production by wind or solar energy. For heat storage to be efficient, high temperatures must be achieved in the subsurface. Significant temporal changes of the soil and groundwater temperatures however effect both the local flow field by temperature dependent fluid parameters as well as reactive mass transport through temperature dependent diffusion coefficients, geochemical reaction rates and mineral equilibria. As the use of heat storage will be concentrated in urban areas, the use of the subsurface for (drinking) water supply and heat storage will typically coincide and a reliable prognosis of the processes occurring is needed. In the present work, the effects of a temporal variation of the groundwater temperature, as induced by a local heat exchanger introduced into a groundwater aquifer, are studied. For this purpose, the coupled non-isothermal groundwater flow, heat transport and reactive mass transport is simulated in the near filed of such a heat exchanger. By explicitly discretizing and incorporating the borehole, the borehole cementation and the heat exchanger tubes, a realistic geometrical and process representation is obtained. The numerical simulation code OpenGeoSys is used in this work, which incorporates the required processes of coupled groundwater flow, heat and mass transport as well as temperature dependent geochemistry. Due to the use of a Finite Element Method, a close representation of the geometric effects can be achieved. Synthetic scenario simulations for typical settings of salt water formations in northern Germany are used to investigate the geochemical effects arising from a high temperature heat storage by quantifying changes in groundwater chemistry and overall reaction rates. This work presents the simulation approach used and results obtained for the synthetic scenarios. The model simulations show that locally in the direct vicinity of the borehole heat exchanger the flow field is changed, causing a ground water convergence and thus a mixing of water in the case of high temperatures. Also, geochemical reactions are induced due to shifting of temperature dependent mineral equilibria. Due to the moving groundwater, the changes are not reversible, and small impacts remain downstream of the borehole heat exchanger. However, the changes depend strongly on the mineral composition of the formation and the formation water present.

Modeling the oxidation kinetics of sono-activated persulfate's process on the degradation of humic acid.

PubMed

Songlin, Wang; Ning, Zhou; Si, Wu; Qi, Zhang; Zhi, Yang

2015-03-01

Ultrasound degradation of humic acid has been investigated in the presence of persulfate anions at ultrasonic frequency of 40 kHz. The effects of persulfate anion concentration, ultrasonic power input, humic acid concentration, reaction time, solution pH and temperature on humic acid removal efficiency were studied. It is found that up to 90% humic acid removal efficiency was achieved after 2 h reaction. In this system, sulfate radicals (SO₄⁻·) were considered to be the mainly oxidant to mineralize humic acid while persulfate anion can hardly react with humic acid directly. A novel kinetic model based on sulfate radicals (SO₄⁻·) oxidation was established to describe the humic acid mineralization process mathematically and chemically in sono-activated persulfate system. According to the new model, ultrasound power, persulfate dosage, solution pH and reaction temperature have great influence on humic acid degradation. Different initial concentration of persulfate anions and humic acid, ultrasonic power, initial pH and reaction temperature have been discussed to valid the effectiveness of the model, and the simulated data showed new model had good agreement with the experiments data.

Soil organic carbon and nitrogen pools drive soil C-CO2 emissions from selected soils in Maritime Antarctica.

PubMed

Pires, C V; Schaefer, C E R G; Hashigushi, A K; Thomazini, A; Filho, E I F; Mendonça, E S

2017-10-15

The ongoing trend of increasing air temperatures will potentially affect soil organic matter (SOM) turnover and soil C-CO 2 emissions in terrestrial ecosystems of Maritime Antarctica. The effects of SOM quality on this process remain little explored. We evaluated (i) the quantity and quality of soil organic matter and (ii) the potential of C release through CO 2 emissions in lab conditions in different soil types from Maritime Antarctica. Soil samples (0-10 and 10-20cm) were collected in Keller Peninsula and the vicinity of Arctowski station, to determine the quantity and quality of organic matter and the potential to emit CO 2 under different temperature scenarios (2, 5, 8 and 11°C) in lab. Soil organic matter mineralization is low, especially in soils with low organic C and N contents. Recalcitrant C form is predominant, especially in the passive pool, which is correlated with humic substances. Ornithogenic soils had greater C and N contents (reaching to 43.15gkg -1 and 5.22gkg -1 for total organic carbon and nitrogen, respectively). C and N were more present in the humic acid fraction. Lowest C mineralization was recorded from shallow soils on basaltic/andesites. C mineralization rates at 2°C were significant lower than at higher temperatures. Ornithogenic soils presented the lowest values of C-CO 2 mineralized by g of C. On the other hand, shallow soils on basaltic/andesites were the most sensitive sites to emit C-CO 2 by g of C. With permafrost degradation, soils on basaltic/andesites and sulfates are expected to release more C-CO 2 than ornithogenic soils. With greater clay contents, more protection was afforded to soil organic matter, with lower microbial activity and mineralization. The trend of soil temperature increases will favor C-CO 2 emissions, especially in the reduced pool of C stored and protected on permafrost, or in occasional Histosols. Copyright © 2016 Elsevier B.V. All rights reserved.

A meta-analysis of the response of soil respiration, net nitrogen mineralization, and aboveground plant growth to experimental ecosystem warming

Treesearch

L.E. Rustad; J.L. Campbell; G.M. Marion; R.J. Norby; M.J. Mitchell; A.E. Hartley; J.H.C. Cornelissen; J. Gurevitch

2001-01-01

Climate change due to greenhouse gas emissions is predicted to raise the mean global temperature by 1.0-3.5°C in the next 50-100 years. The direct and indirect effects of this potential increase in temperature on terrestrial ecosystems and ecosystem processes are likely to be complex and highly varied in time and space. The Global Change and Terrestrial...

Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

PubMed

Kang, Il-Mo; Roh, Ki-Min

2013-01-01

The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

Mineralogy, fluid inclusion petrography, and stable isotope geochemistry of Pb-Zn-Ag veins at the Shizhuyuan deposit, Hunan Province, southeastern China

NASA Astrophysics Data System (ADS)

Wu, Shenghua; Mao, Jingwen; Yuan, Shunda; Dai, Pan; Wang, Xudong

2018-01-01

The Shizhuyuan polymetallic deposit is located in the central part of the Nanling region, southeastern China, and consists of proximal W-Sn-Mo-Bi skarns and greisens and distal Pb-Zn-Ag veins. The sulfides and sulfosalts in the distal veins formed in three distinct stages: (1) an early stage of pyrite and arsenopyrite, (2) a middle stage of sphalerite and chalcopyrite, and (3) a late stage of galena, Ag-, Sn-, and Bi-bearing sulfides and sulfosalts, and pyrrhotite. Combined sulfide and sulfosalt geothermometry and fluid inclusion analyses indicate that the early stage of mineralization occurred at a temperature of 400 °C and involved boiling under hydrostatic pressure ( 200 bar), with the temperature of the system dropping during the late stage to 200 °C. Laser Raman analysis indicates that the fluid inclusions within the studied minerals are dominated by H2O, although some contain carbonate solids and CH4 gas. Vein-hosted sulfides have δ34S values of 3.8-6.3‰ that are interpreted as indicative of a magmatic source of sulfur. The mineralization process can be summarized as follows: an aqueous fluid exsolved on final crystallization of the Qianlishan pluton, ascended along fracture zones, cooled to <400 °C, and boiled under hydrostatic conditions, and with decreasing temperature and sulfur fugacity, sulfide and sulfosalt minerals precipitated successively from the Ag-Cu-Zn-Fe-Pb-Sb-As-S-bearing fluid system.

Evolution of organic matter fractions after application of co-compost of sewage sludge with pruning waste to four Mediterranean agricultural soils. A soil microcosm experiment.

PubMed

Pérez-Lomas, A L; Delgado, G; Párraga, J; Delgado, R; Almendros, G; Aranda, V

2010-10-01

The effect of co-compost application from sewage sludge and pruning waste, on quality and quantity of soil organic carbon (SOC) in four Mediterranean agricultural soils (South Spain), was studied in soil microcosm conditions. Control soil samples (no co-compost addition) and soils treated with co-composts to a rate equivalent of 140 Mg ha(-1) were incubated for 90 days at two temperatures: 5 and 35 degrees C. The significances of incubation temperature and the addition of co-compost, on the evolution of the different fractions of SOC, were studied using a 2(3) factorial design. The co-compost amendment increased the amounts of humic fractions: humic acids (HA) (1.9 times), fulvic acids (FA) (3.3 times), humin (1.5 times), as well as the free organic matter (1.4 times) and free lipids (21.8 times). Incubation of the soils enhanced its biological activity mainly in the amended soils and at 35 degrees C, leading to progressive SOC mineralization and humification, concomitant to the preferential accumulation of HA. The incubation results show large differences depending on temperature and soil types. This fact allows us to select suitable organic amendment for the soil when a rapid increase in nutrients through mineralization is preferred, or in cases intending the stabilization and preservation of the SOC through a process of humification. In soils with HA of more than 5 E(4)/E(6) ratio, the incubation temperature increased rates of mineralization and humification, whereas lower temperatures limited the extent of both processes. In these soils the addition of co-compost in spring or summer is the most recommendable. In soils with HA of lower E(4)/E(6) ratio (<5), the higher temperature favoured mineralization but not humification, whereas the low temperature maintained the SOC levels and even increased the HA/FA ratio. In these soils the moment of addition of organic amendment should be decided depending on the effect intended. On the other hand, the lower the SOC content in the original soil, the greater are the changes observed in the SOC after amendment with co-compost. The results suggest that proper recommendations for optimum organic matter evolution after soil amendment is possible after considering a small set of characteristics of soil and the corresponding soil organic matter fractions, in particular HA. (c) 2010 Elsevier Ltd. All rights reserved.

Environmental mineralogy - Understanding element behavior in ecosystems

NASA Astrophysics Data System (ADS)

Brown, Gordon E., Jr.; Calas, Georges

2011-02-01

Environmental Mineralogy has developed over the past decade in response to the recognition that minerals are linked in many important ways with the global ecosystem. Minerals are the main repositories of the chemical elements in Earth's crust and thus are the main sources of elements needed for the development of civilization, contaminant and pollutant elements that impact global and local ecosystems, and elements that are essential plant nutrients. These elements are released from minerals through natural processes, such as chemical weathering, and anthropogenic activities, such as mining and energy production, agriculture and industrial activities, and careless waste disposal. Minerals also play key roles in the biogeochemical cycling of the elements, sequestering elements and releasing them as the primary minerals in crustal rocks undergo various structural and compositional transformations in response to physical, chemical, and biological processes that produce secondary minerals and soils. These processes have resulted in the release of toxic elements such as arsenic in groundwater aquifers, which is having a major impact on the health of millions of people in South and Southeast Asia. The interfaces between mineral surfaces and aqueous solutions are the locations of most chemical reactions that control the composition of the natural environment, including the composition of natural waters. The nuclear fuel cycle, from uranium mining to the disposition of high-level nuclear waste, is also intimately related to minerals. A fundamental understanding of these processes requires molecular-scale information about minerals, their bulk structures and properties such as solubility, their surfaces, and their interactions with aqueous solutions, atmospheric and soil gases, natural organic matter, and biological organisms. Gaining this understanding is further complicated by the presence of natural, incidental, and manufactured nanoparticles in the environment, which are becoming increasingly important due to the rapidly developing field of nanotechnology. As a result of this complexity, Environmental Mineralogy requires the use of the most modern molecular-scale analytical and theoretical methods and overlaps substantially with closely related fields such as Environmental Sciences, low-temperature Geochemistry, and Geomicrobiology. This paper provides brief overviews of the above topics and discusses the complexity of minerals, natural vs. anthropogenic inputs of elements and pollutants into the biosphere, the role of minerals in the biogeochemical cycling of elements, natural nanoparticles, and the Environmental Mineralogy of three major potential pollutant elements (Hg, As and U).

PAH-Mineral Interactions. A Laboratory Approach to Astrophysical Catalysis

NASA Astrophysics Data System (ADS)

Adolfo Cruz Diaz, Gustavo; Mattioda, Andrew

2017-06-01

Polycyclic Aromatic Hydrocarbon (PAH) molecules carry the infrared emission features which dominate the spectra of most galactic and extragalactic sources. Our study investigates the chemical evolution, chemical properties, physical properties, thermal stability, and photostability of samples produced from the UV-irradiation of simulated mineral dust grains coated with aromatics and astrobiologically relevant ices, using infrared spectroscopy. We investigate the chemical evolution of aromatic organics via anhydrous (no H2O ice) and hydrous (H2O ice) mechanisms. The anhydrous mechanism involves UV-induced catalytic reactions between organics and dense-cloud mineral grains, whereas the hydrous mechanism incorporates H2O-rich ice mixtures with the minerals and organics. These investigations identify the chemical and physical interactions occurring between the organic species, the dust grains and water-rich ices.These laboratory simulations also generate observable IR spectroscopic parameters for future astronomical observations with infrared telescopes such as SOFIA and JWST as well as provide empirical parameters for input into astronomical models of the early stages of planetary formation. These studies give us a deeper understanding of the potential catalytic pathways mineral surfaces provide and a deeper understanding of the role of ice-organic compositions in the chemical reaction pathways and how these processes fit into the formation of new planetary systems.In order to achieve these goals we use the Harrick ‘Praying Mantis’ Diffuse Reflectance Accessory (DRIFTS), which allows FTIR measurements of dust samples under ambient conditions by measuring the light scattered by the dust sample. We have also incorporated a low -temperature reaction chamber permitting the DRIFTS measurements at low temperatures and high-vacuum. This set-up permits the analysis of the solid particles surfaces revealing the chemical species adsorbed as well as their chemical evolution via the introduction of reactant gases, UV irradiation, temperature change, etc.

Magnetic Properties of Iron Oxide Minerals in Atmospheric Dust and Source Sediments from Western US

NASA Astrophysics Data System (ADS)

Moskowitz, B. M.; Yauk, K.; Till, J. L.; Berquo, T. S.; Banerjee, S. K.; Reynolds, R. L.; Goldstein, H. L.

2011-12-01

Atmospheric dust contains iron oxide minerals that can play important roles in various physical and biological processes affecting atmospheric and surface temperatures, marine phytoplankton productivity, and human health. Iron oxide minerals in dust deposited on mountain snow cover are especially important because these minerals absorb solar and IR radiation leading to changes in albedo and affecting the timing and rate of spring and summer snowpack melting. As part of an ongoing project to study physical and chemical properties of dust from sources to sinks in the western US, we will describe one approach to characterize iron oxide mineralogy using magnetic property measurements and Mossbauer spectroscopy. Magnetic property measurements over a wide range of temperatures (2-300 K) and magnetic fields (0-5 T) are particularly sensitive to composition, particle size (from nanometer to micrometer), and concentration of iron oxide and oxyhydroxide minerals. The high sensitivity of magnetic measurements to target minerals allows the measurement of bulk samples preventing any aliasing of composition or grain size resulting from attempts at prior magnetic separation. In addition, different magnetic measurement protocols can isolate different particle-size assemblages and different compositions in multicomponent mixtures and help to identify dust-source areas. These techniques have been applied to dust deposited on snow (DOS) cover of the San Juan Mountains, Colorado (collected 2005-2010) and Wasatch Mountains, Utah (collected 2010) and possible dust-source sediments from the North American Great Basin and Colorado Plateau deserts. Results show that all samples contain a high coercivity phase consistent with hematite and/or goethite as the dominate ferric oxide mineral plus minor amounts of magnetite (<0.5 wt%). The presence of magnetite was determined from the detection of the characteristic Verwey transition (T=121 K) on low-temperature (< 300 K) remanence and susceptibility curves. Room temperature remanence parameters for the San Juan Mountains DOS fall into two discrete populations of hematite concentration ( x2 difference) but with similar spreads in magnetite concentrations (0.05-0.2%) within each group. Preliminary Mössbauer spectroscopy at 300 K for San Juan Mountains DOS indicates hematite as the sole magnetic phase with magnetite below the detection limits. However, spectra taken at 4.2 K show an increase in the hematite component and the appearance of goethite indicating superparamagnetism and nanoparticle size distribution for both phases. The lack of the Morin transition (T=263 K) for hematite on low-temperature remanence curves is also consistent with nanohematite as the main iron oxide phase in DOS from the San Juan Mountains.

Step-wise supercritical extraction of carbonaceous residua

DOEpatents

Warzinski, Robert P.

1987-01-01

A method of fractionating a mixture containing high boiling carbonaceous material and normally solid mineral matter includes processing with a plurality of different supercritical solvents. The mixture is treated with a first solvent of high critical temperature and solvent capacity to extract a large fraction as solute. The solute is released as liquid from solvent and successively treated with other supercritical solvents of different critical values to extract fractions of differing properties. Fractionation can be supplemented by solute reflux over a temperature gradient, pressure let down in steps and extractions at varying temperature and pressure values.

30 CFR 18.23 - Limitation of external surface temperatures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Limitation of external surface temperatures. 18.23 Section 18.23 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING... and Design Requirements § 18.23 Limitation of external surface temperatures. The temperature of the...

30 CFR 18.23 - Limitation of external surface temperatures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Limitation of external surface temperatures. 18.23 Section 18.23 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING... and Design Requirements § 18.23 Limitation of external surface temperatures. The temperature of the...

30 CFR 18.23 - Limitation of external surface temperatures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Limitation of external surface temperatures. 18.23 Section 18.23 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING... and Design Requirements § 18.23 Limitation of external surface temperatures. The temperature of the...

30 CFR 18.23 - Limitation of external surface temperatures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Limitation of external surface temperatures. 18.23 Section 18.23 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING... and Design Requirements § 18.23 Limitation of external surface temperatures. The temperature of the...

Mineral compositions of plutonic rocks from the Lewis Hills massif, Bay of Islands ophiolite

NASA Technical Reports Server (NTRS)

Smith, Susan E.; Elthon, Don

1988-01-01

Mineral compositions of residual and cumulate rocks from the Lewis Hills massif of the Bay of Islands ophiolite complex are reported and interpreted in the context of magnetic processes involved in the geochemical evolution of spatially associated diabase dikes. The mineral compositions reflect greater degrees of partial melting than most abyssal peridotites do and appear to represent the most depleted end of abyssal peridotite compositions. Subsolidus equilibration between Cr-Al spinal and olivine generally has occurred at temperatures of 700 to 900 C. The spinel variations agree with the overall fractionation of basaltic magmas producing spinels with progressively lower Cr numbers. The compositions of clinopyroxenes suggest that the fractionation of two different magma series produced the various cumulate rocks.

Alteration behavior of mineral structure and hazardous elements during combustion of coal from a power plant at Huainan, Anhui, China.

PubMed

Tang, Quan; Sheng, Wanqi; Li, Liyuan; Zheng, Liugen; Miao, Chunhui; Sun, Ruoyu

2018-08-01

The alteration behavior of minerals and hazardous elements during simulated combustion (100-1200 °C) of a raw coal collected from a power plant were studied. Thermogravimetric analysis indicated that there were mainly four alteration stages during coal combustion. The transformation behavior of mineral phases of raw coal, which were detected by X-ray polycrystalline diffraction (XRD) technique, mainly relied on the combustion temperature. A series of changes were derived from the intensities of mineral (e.g. clays) diffraction peaks when temperature surpassed 600 °C. Mineral phases tended to be simple and collapsed to amorphous glass when temperature reached up to 1200 °C. The characteristics of functional groups for raw coal and high-temperature (1200 °C) ash studied by Fourier transform infrared spectroscopy (FTIR) were in accordance with the result obtained from XRD analysis. The volatilization ratios of Co, Cr, Ni and V increased consistently with the increase of combustion temperature, suggesting these elements were gradually released from the organic matter and inorganic minerals of coal. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrated Minerals on Asteroids: The Astronomical Record

NASA Technical Reports Server (NTRS)

Rivkin, A. S.; Howell, E. S.; Vilas, F.; Lebofsky, L. A.

2002-01-01

Knowledge of the hydrated mineral inventory on the asteroids is important for deducing the origin of Earth's water, interpreting the meteorite record, and unraveling the processes occurring during the earliest times in solar system history. Reflectance spectroscopy shows absorption features in both the 0.6-0.8 and 2.5-3.5 micrometers regions, which are diagnostic of or associated with hydrated minerals. Observations in those regions show that hydrated minerals are common in the mid-asteroid belt, and can be found in unexpected spectral groupings, as well. Asteroid groups formerly associated with mineralogies assumed to have high temperature formation, such as M- and E-class asteroids, have been observed to have hydration features in their reflectance spectra. Some asteroids have apparently been heated to several hundred degrees Celsius, enough to destroy some fraction of their phyllosilicates. Others have rotational variation suggesting that heating was uneven. We summarize this work, and present the astronomical evidence for water- and hydroxyl-bearing minerals on asteroids.

Hydrated Minerals on Asteroids: The Astronomical Record

NASA Technical Reports Server (NTRS)

Rivkin, A. S.; Howell, E. S.; Vilas, F.; Lebofsky, L. A.

2003-01-01

Knowledge of the hydrated mineral inventory on the asteroids is important for deducing the origin of Earth's water, interpreting the meteorite record, and unraveling the processes occurring during the earliest times in solar system history. Reflectance spectroscopy shows absorption features in both the 0.6-0.8 and 2.5-3.5-micron regions, which are diagnostic of or associated with hydrated minerals. Observations in those regions show that hydrated minerals are common in the mid-asteroid belt, and can be found in unexpected spectral groupings as well. Asteroid groups formerly associated with mineralogies assumed to have high-temperature formation, such as M- and E-class steroids, have been observed to have hydration features in their reflectance spectra. Some asteroids have apparently been heated to several hundred degrees Celsius, enough to destroy some fraction of their phyllosilicates. Others have rotational variation suggesting that heating was uneven. We summarize this work, and present the astronomical evidence for water- and Hydroxl-bearing minerals on asteroids.

A study of the relationship between process conditions and mechanical strength of mineralized red algae in the preparation of a marine-derived bone void filler.

PubMed

Walsh, P J; Walker, G M; Maggs, C A; Buchanan, F J

2011-06-01

Bone void fillers that can enhance biological function to augment skeletal repair have significant therapeutic potential in bone replacement surgery. This work focuses on the development of a unique microporous (0.5-10 microm) marine-derived calcium phosphate bioceramic granule. It was prepared from Corallina officinalis, a mineralized red alga, using a novel manufacturing process. This involved thermal processing, followed by a low pressure-temperature chemical synthesis reaction. The study found that the ability to maintain the unique algal morphology was dependent on the thermal processing conditions. This study investigates the effect of thermal heat treatment on the physiochemical properties of the alga. Thermogravimetric analysis was used to monitor its thermal decomposition. The resultant thermograms indicated the presence of a residual organic phase at temperatures below 500 degrees C and an irreversible solid-state phase transition from mg-rich-calcite to calcium oxide at temperatures over 850 degrees C. Algae and synthetic calcite were evaluated following heat treatment in an air-circulating furnace at temperatures ranging from 400 to 800 degrees C. The highest levels of mass loss occurred between 400-500 degrees C and 700-800 degrees C, which were attributed to the organic and carbonate decomposition respectively. The changes in mechanical strength were quantified using a simple mechanical test, which measured the bulk compressive strength of the algae. The mechanical test used may provide a useful evaluation of the compressive properties of similar bone void fillers that are in granular form. The study concluded that soak temperatures in the range of 600 to 700 degrees C provided the optimum physiochemical properties as a precursor to conversion to hydroxyapatite (HA). At these temperatures, a partial phase transition to calcium oxide occurred and the original skeletal morphology of the alga remained intact.

A modified sulfate process to lunar oxygen

NASA Technical Reports Server (NTRS)

Sullivan, Thomas A.

1992-01-01

A modified sulfate process which produces oxygen from iron oxide-bearing minerals in lunar soil is under development. Reaction rates of ilmenite in varying strength sulfuric acid have been determined. Quantitative conversion of ilmenite to ferrous sulfate was observed over a range of temperatures and concentrations. Data has also been developed on the calcination of by-product sulfates. System engineering for overall operability and simplicity has begun, suggesting that a process separating the digestion and sulfate dissolution steps may offer an optimum process.

The role of hydrothermal processes in the granite-hosted Zr, Y, REE deposit at Strange Lake, Quebec/Labrador: Evidence from fluid inclusions

NASA Astrophysics Data System (ADS)

Salvi, Stefano; Williams-Jones, Anthony E.

1990-09-01

The Strange Lake Zr, Y, REE, Nb, and Be deposit is hosted by a small, high-level, Late-Proterozoic peralkaline granite stock that intruded into high-grade metamorphic gneisses on the Quebec-Labrador border. The stock is extensively altered. Early alteration is manifested by the replacement of arfvedsonite with aegirine. Later alteration involved Ca-Na exchange. Zr, Ti, Y, REEs, Nb, and Be are concentrated in Ca-bearing minerals that, together with quartz, commonly pseudomorph Na-bearing minerals. Fluid inclusions in pseudomorphs comprise several distinct types: high-salinity (13 to 24 wt% NaCl eq.), Ca-rich aqueous inclusions that homogenize to liquid between 135 and 195°C; mixed aqueousmethane inclusions; methane inclusions; and solid-bearing inclusions. Aqueous-methane inclusions represent heterogeneous entrapment of immiscible high-salinity aqueous liquid and methane. Bastnäsite (tentatively identified by SEM analysis) occurs as a daughter mineral. Other daughter or trapped minerals include a Y, HREE-bearing mineral, possibly gagarinite, and hematite, galena, sphalerite, fluorite, pyrochlore, kutnahorite (?), and griceite (?). The first three inclusion types also occur in quartz in pegmatites and veins together with lower-temperature, lower-salinity, Na-dominated aqueous inclusions. The entrapment temperature inferred for the aqueous inclusions from microthermometry and the Na-K-Ca geothermometer range from 155 to 195°C for the higher-salinity inclusions and 100 to 165°C for the low-salinity inclusions. A model is proposed in which the intrusion of a peralkaline granite to high crustal levels initiated a ground/formational water-dominated hydrothermal system in adjacent gabbroic, calc-silicate, and graphitic gneisses. Reaction of the high-salinity, Ca-rich liquid with the graphitic gneisses led to the production of an immiscible methane gas. Subsequent interaction of this liquid with the granite led to extensive replacement of sodic minerals by calcium analogues at temperatures of less than 200°C. Some time after the onset of Ca metasomatism the high-salinity liquid mixed with a Ca-poor, low-salinity, low-temperature liquid that had leached F and rare metals from the granite. Yttrium and REE mineral deposition occurred as a result of the decreased ligand concentration that accompanied fluorite deposition during mixing of the Ca-rich and Ca-poor aqueous liquids.

Aqueous geochemistry of low molecular weight hydrocarbons at elevated temperatures and pressures: constraints from mineral buffered laboratory experiments

NASA Astrophysics Data System (ADS)

Seewald, Jeffrey S.

2001-05-01

Organic matter, water, and minerals coexist at elevated temperatures and pressures in sedimentary basins and participate in a wide range of geochemical processes that includes the generation of oil and natural gas. A series of laboratory experiments were conducted at 300 to 350°C and 350 bars to examine chemical interactions involving low molecular weight aqueous hydrocarbons with water and Fe-bearing minerals under hydrothermal conditions. Mineral buffers composed of hematite-magnetite-pyrite, hematite-magnetite, and pyrite-pyrrhotite-magnetite were added to each experiment to fix the redox state of the fluid and the activity of reduced sulfur species. During each experiment the chemical system was externally modified by addition of ethene, ethane, propene, 1-butene, or n-heptane, and variations in the abundance of aqueous organic species were monitored as a function of time and temperature. Results of the experiments indicate that decomposition of aqueous n-alkanes proceeds through a series of oxidation and hydration reactions that sequentially produce alkenes, alcohols, ketones, and organic acids as reaction intermediaries. Organic acids subsequently undergo decarboxylation and/or oxidation reactions to form carbon dioxide and shorter chain saturated hydrocarbons. This alteration assemblage is compositionally distinct from that produced by thermal cracking under anhydrous conditions, indicating that the presence of water and minerals provide alternative reaction pathways for the decomposition of hydrocarbons. The rate of hydrocarbon oxidation decreases substantially under reducing conditions and in the absence of catalytically active aqueous sulfur species. These results represent compelling evidence that the stability of aqueous hydrocarbons at elevated temperatures in natural environments is not a simple function of time and temperature alone. Under the appropriate geochemical conditions, stepwise oxidation represents a mechanism for the decomposition of low molecular weight hydrocarbons and the production of methane-rich ("dry") natural gas. Evaluation of aqueous reaction products generated during the experiments within a thermodynamic framework indicates that alkane-alkene, alkene-ketone, and alkene-alcohol reactions attained metastable thermodynamic equilibrium states. This equilibrium included water and iron-bearing minerals, demonstrating the direct involvement of inorganic species as reactants during organic transformations. The high reactivity of water and iron-bearing minerals suggests that they represent abundant sources of hydrogen and oxygen available for the formation of hydrocarbons and oxygenated alteration products. Thus, variations in elemental kerogen composition may not accurately reflect the timing and extent of hydrocarbon, carbon dioxide, and organic acid generation in sedimentary basins. This study demonstrates that the stabilities of aqueous hydrocarbons are strongly influenced by inorganic sediment composition at elevated temperatures. Incorporation of such interactions into geochemical models will greatly improve prediction of the occurrence of hydrocarbons in natural environments over geologic time.

Effects of Genotype and Growth Temperature on the Contents of Tannin, Phytate and In Vitro Iron Availability of Sorghum Grains

PubMed Central

Wu, Gangcheng; Johnson, Stuart K.; Bornman, Janet F.; Bennett, Sarita J.; Singh, Vijaya; Simic, Azra; Fang, Zhongxiang

2016-01-01

Background It has been predicted that the global temperature will rise in the future, which means crops including sorghum will likely be grown under higher temperatures, and consequently may affect the nutritional properties. Methods The effects of two growth temperatures (OT, day/night 32/21°C; HT 38/21°C) on tannin, phytate, mineral, and in vitro iron availability of raw and cooked grains (as porridge) of six sorghum genotypes were investigated. Results Tannin content significantly decreased across all sorghum genotypes under high growth temperature (P ≤0.05), while the phytate and mineral contents maintained the same level, increased or decreased significantly, depending on the genotype. The in vitro iron availability in most sorghum genotypes was also significantly reduced under high temperature, except for Ai4, which showed a pronounced increase (P ≤0.05). The cooking process significantly reduced tannin content in all sorghum genotypes (P ≤0.05), while the phytate content and in vitro iron availability were not significantly affected. Conclusions This research provides some new information on sorghum grain nutritional properties when grown under predicted future higher temperatures, which could be important for humans where sorghum grains are consumed as staple food. PMID:26859483

Enzymatic mechanisms of soil-carbon response to temperature on Mt. Kilimanjaro

NASA Astrophysics Data System (ADS)

Blagodatskaya, Evgenia; Blagodatskiy, Sergey; Kuzyakov, Yakov

2016-04-01

Short-term acceleration of soil organic matter (SOM) decomposition by increasing temperature contradicts the acclimation observed in long-term studies. We used the unique altitudinal gradient (from colline tropical zone to subalpine zone) on Mt. Kilimanjaro to demonstrate the mechanisms of short- and long-term acclimation of extra- and intracellular enzymes that decompose polymers (cellulose, chitin, phytate) and oxidize monomers (14C-glucose). Basing on Michaelis-Menten kinetics we determined the enzymes affinity to substrate (Km) and mineralization potential of heterotrophic microorganisms (Vmax) 1) for three hydrolytic enzymes: β-1,4-glucosidase, N-acetyl- β -D-glucosaminidase and phosphatase by the application of fluorogenically labeled substrates and 2) for mineralization of 14C-labeled glucose by substrate-dependent respiratory response. Here we show that the amount of available substrate is responsible for temperature sensitivity of hydrolysis of polymers in soil, whereas monomers oxidation to CO2 does not depend on substrate amount and is mainly temperature governed. We also found that substrate affinity of enzymes (which is usually decreases with the temperature) differently responded to warming for the process of depolymerisation versus monomers oxidation. We suggest the mechanism to temperature acclimation based on different temperature sensitivity of enzymes kinetics for hydrolysis of polymers and for monomers oxidation

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation

PubMed Central

Zhang, Anjie; Mu, Bin; Wang, Xiaowen; Wen, Lixin; Wang, Aiqin

2018-01-01

Different kinds of aluminosilicate minerals were employed to fabricate CoAl2O4 hybrid pigment for studying its formation and coloring mechanism. It revealed that the color of the obtained hybrid pigments was determined by the content of Al2O3 and lightness of clay minerals. The higher the Al2O3 content and the lightness of clay minerals, the better the color parameters of hybrid pigments. During the preparation of hybrid pigments, CoAl2O4 nanoparticles were confined to be loaded on the surface of the aluminosilicate minerals, which effectively prevented from the aggregation and the size increase of CoAl2O4 nanoparticles. What's more, aluminosilicate mineral might be an ideal natural aluminum source to compensate the aluminum loss due to the dissolution of Al(OH)3 at alkaline medium during precursor preparation, keeping an optimum molar ratio of Co2+/Al3+ for formation of spinel CoAl2O4 pigments in the process of high-temperature crystallization. PMID:29725589

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation.

PubMed

Zhang, Anjie; Mu, Bin; Wang, Xiaowen; Wen, Lixin; Wang, Aiqin

2018-01-01

Different kinds of aluminosilicate minerals were employed to fabricate CoAl 2 O 4 hybrid pigment for studying its formation and coloring mechanism. It revealed that the color of the obtained hybrid pigments was determined by the content of Al 2 O 3 and lightness of clay minerals. The higher the Al 2 O 3 content and the lightness of clay minerals, the better the color parameters of hybrid pigments. During the preparation of hybrid pigments, CoAl 2 O 4 nanoparticles were confined to be loaded on the surface of the aluminosilicate minerals, which effectively prevented from the aggregation and the size increase of CoAl 2 O 4 nanoparticles. What's more, aluminosilicate mineral might be an ideal natural aluminum source to compensate the aluminum loss due to the dissolution of Al(OH) 3 at alkaline medium during precursor preparation, keeping an optimum molar ratio of Co 2+ /Al 3+ for formation of spinel CoAl 2 O 4 pigments in the process of high-temperature crystallization.

Specificity of pyrometamorphic minerals of the ellestadite group

NASA Astrophysics Data System (ADS)

Zateeva, S. N.; Sokol, E. V.; Sharygin, V. V.

2007-12-01

Numerous rare and new mineral species are synthesized during the process of pyrometamorphism (Gross, 1977; Chesnokov et al., 1987; Chesnokov and Shcherbakova, 1991; Chesnokov, 1999), including silicooxides, chloride-, fluoride, and sulfate-silicates, carbonate-sulfides, chloride-oxides, etc. Having made sense of numerous findings of compounds of this type, Chesnokov (1999) set forth the concept of the crystallochemical transition at extreme temperatures attaining 1200-1450°C in pyrogenic systems. First of all, intertype transitions (oxygen-bearing-oxygen-free) and interclass transitions (chloride-silicate, carbonate-sulfide, chlorideoxide) are realized. The specificity of pyrometamorphic mineral assemblages consists in the abundance of silicates with additional anions (F-, Cl-, (CO3)2-) (Sokol et al., 2005). Minerals of the ellestadite group Ca10(SiO4)3 - x (SO4)3 - x (PO4)2 x (OH,F,Cl)2 are a spectacular example of these features. In the general case, they are silicate-sulfate-phosphate-hydroxide-chlorides-fluorides. The detailed description of these minerals based on the study of the original collection of pyrometamorphic minerals is presented in this paper.

Thermophilic microorganisms in biomining.

PubMed

Donati, Edgardo Rubén; Castro, Camila; Urbieta, María Sofía

2016-11-01

Biomining is an applied biotechnology for mineral processing and metal extraction from ores and concentrates. This alternative technology for recovering metals involves the hydrometallurgical processes known as bioleaching and biooxidation where the metal is directly solubilized or released from the matrix for further solubilization, respectively. Several commercial applications of biomining can be found around the world to recover mainly copper and gold but also other metals; most of them are operating at temperatures below 40-50 °C using mesophilic and moderate thermophilic microorganisms. Although biomining offers an economically viable and cleaner option, its share of the world´s production of metals has not grown as much as it was expected, mainly considering that due to environmental restrictions in many countries smelting and roasting technologies are being eliminated. The slow rate of biomining processes is for sure the main reason of their poor implementation. In this scenario the use of thermophiles could be advantageous because higher operational temperature would increase the rate of the process and in addition it would eliminate the energy input for cooling the system (bioleaching reactions are exothermic causing a serious temperature increase in bioreactors and inside heaps that adversely affects most of the mesophilic microorganisms) and it would decrease the passivation of mineral surfaces. In the last few years many thermophilic bacteria and archaea have been isolated, characterized, and even used for extracting metals. This paper reviews the current status of biomining using thermophiles, describes the main characteristics of thermophilic biominers and discusses the future for this biotechnology.

Abiotic dechlorination of chlorinated ethenes in natural clayey soils: Impacts of mineralogy and temperature

NASA Astrophysics Data System (ADS)

Schaefer, Charles E.; Ho, Paul; Gurr, Christopher; Berns, Erin; Werth, Charles

2017-11-01

Laboratory batch experiments were performed to assess the impacts of temperature and mineralogy on the abiotic dechlorination of tetrachloroethene (PCE) or trichloroethene (TCE) due to the presence of ferrous minerals in natural aquifer clayey soils under anaerobic conditions. A combination of x-ray diffraction (XRD), magnetic susceptibility, and ferrous mineral content were used to characterize each of the 3 natural soils tested in this study, and dechlorination at temperatures ranging from 20 to 55 °C were examined. Results showed that abiotic dechlorination occurred in all 3 soils examined, yielding reduced gas abiotic dechlorination products acetylene, butane, ethene, and/or propane. Bulk first-order dechlorination rate constants (kbulk), scaled to the soil:water ratio expected for in situ conditions, ranged from 2.0 × 10- 5 day- 1 at 20 °C, to 32 × 10- 5 day- 1 at 55 °C in the soil with the greatest ferrous mineral content. For the generation of acetylene and ethene from PCE, the reaction was well described by Arrhenius kinetics, with an activation energy of 91 kJ/mol. For the generation of coupling products butane and propane, the Arrhenius equation did not provide a satisfactory description of the data, likely owing to the complex reaction mechanisms associated with these products and/or diffusional mass transfer processes associated with the ferrous minerals likely responsible for these coupling reactions. Although the data set was too limited to determine a definitive correlation, the two soils with elevated ferrous mineral contents had elevated abiotic dechlorination rate constants, while the one soil with a low ferrous mineral content had a relatively low abiotic dechlorination rate constant. Overall, results suggest intrinsic abiotic dechlorination rates may be an important long-term natural attenuation component in site conceptual models for clays that have the appropriate iron mineralogy.

Deep Boreholes Seals Subjected to High P,T conditions - Proposed Experimental Studies

NASA Astrophysics Data System (ADS)

Caporuscio, F.

2015-12-01

Deep borehole experimental work will constrain the P,T conditions which "seal" material will experience in deep borehole crystalline rock repositories. The rocks of interest to this study include mafic (amphibolites) and silicic (granitic gneiss) end members. The experiments will systematically add components to capture discrete changes in both water and EBS component chemistries. Experiments in the system wall rock-clay-concrete-groundwater will evaluate interactions among components, including: mineral phase stability, metal corrosion rates and thermal limits. Based on engineered barrier studies, experimental investigations will move forward with three focusses. First, evaluation of interaction between "seal" materials and repository wall rock (crystalline) under fluid-saturated conditions over long-term (i.e., six-month) experiments; which reproduces the thermal pulse event of a repository. Second, perform experiments to determine the stability of zeolite minerals (analcime-wairakitess) under repository conditions. Both sets of experiments are critically important for understanding mineral paragenesis (zeolites and/or clay transformations) associated with "seals" in contact with wall rock at elevated temperatures. Third, mineral growth at the metal interface is a principal control on the survivability (i.e. corrosion) of waste canisters in a repository. The objective of this planned experimental work is to evaluate physio-chemical processes for 'seal' components and materials relevant to deep borehole disposal. These evaluations will encompass multi-laboratory efforts for the development of seals concepts and application of Thermal-Mechanical-Chemical (TMC) modeling work to assess barrier material interactions with subsurface fluids and other barrier materials, their stability at high temperatures, and the implications of these processes to the evaluation of thermal limits.

Extraction and Capture of Water from Martian Regolith Experimental Proof-of-Concept

NASA Technical Reports Server (NTRS)

Linne, Diane; Kleinhenz, Julie; Bauman, Steve; Johnson, Kyle

2016-01-01

Mars Design Reference Architecture 5.0:Lists in-situ resource utilization (ISRU) as enabling for robust human Mars missionsLO2LCH4 ascent propulsion 25,000 kg oxygen from atmosphere for ascent and life support Atmospheric based ISRU processes less operationally complex than surface based limited concept evaluation to date and Mars surface water property and distribution uncertainty would not allow [Mars soil water processing] to be base lined at this time Limited Concept Evaluation to Date Lunar regolith O2 extraction processing experience Lunar regolith is fluidized and heated to high temperatures with H2 to produce H2O from iron-bearing minerals Mars similarity concept: Soil placed in fluidized bed reactor Heated to moderate temperatures Inert gas flow used to fluidize the bed and help with water desorption Challenges: High-temperature dusty seals Working gas requires downstream separation and recycling to reduce consumables loss Batch process heating thermally inefficient.

The clumped-isotope geochemistry of exhumed marbles from Naxos, Greece

NASA Astrophysics Data System (ADS)

Ryb, U.; Lloyd, M. K.; Stolper, D. A.; Eiler, J. M.

2017-07-01

Exhumation and accompanying retrograde metamorphism alter the compositions and textures of metamorphic rocks through deformation, mineral-mineral reactions, water-rock reactions, and diffusion-controlled intra- and inter-mineral atomic mobility. Here, we demonstrate that these processes are recorded in the clumped- and single-isotope (δ13 C and δ18 O) compositions of marbles, which can be used to constrain retrograde metamorphic histories. We collected 27 calcite and dolomite marbles along a transect from the rim to the center of the metamorphic core-complex of Naxos (Greece), and analyzed their carbonate single- and clumped-isotope compositions. The majority of Δ47 values of whole-rock samples are consistent with exhumation- controlled cooling of the metamorphic complex. However, the data also reveal that water-rock interaction, deformation driven recrystallization and thermal shock associated with hydrothermal alteration may considerably impact the overall distribution of Δ47 values. We analyzed specific carbonate fabrics influenced by deformation and fluid-rock reaction to study how these processes register in the carbonate clumped-isotope system. Δ47 values of domains drilled from a calcite marble show a bimodal distribution. Low Δ47 values correspond to an apparent temperature of 260 °C and are common in static fabrics; high Δ47 values correspond to an apparent temperature of 200 °C and are common in dynamically recrystallized fabrics. We suggest that the low Δ47 values reflect diffusion-controlled isotopic reordering during cooling, whereas high Δ47 values reflect isotopic reordering driven by dynamic recrystallization. We further studied the mechanism by which dynamic recrystallization may alter Δ47 values by controlled heating experiments. Results show no significant difference between laboratory reactions rates in the static and dynamic fabrics, consistent with a mineral-extrinsic mechanism, in which slip along crystal planes was associated with atomic-scale isotopic reordering in the calcite lattice. An intrinsic mechanism (enhanced isotopic reordering rate in deformed minerals) is contraindicated by these experiments. We suggest that Δ47 values of dynamically recrystallized fabrics that form below the diffusion-controlled blocking-temperature for calcite constrain the temperature of deformation. We find that Δ47-based temperatures of static fabrics from Naxos marbles are ∼60-80 °C higher than commonly observed in slowly cooled metamorphic rocks, and would suggest cooling rates of ∼105 °CMyr-1. A similar thermal history is inferred for dolomite marbles from the core vicinity, which preserve apparent temperatures up to 200 °C higher than a typical blocking temperature (∼300 °C). This finding could be explained by a hydrothermal event driving a brief thermal pulse and locally resetting Δ47 values. Rapid cooling of the core-complex region is consistent with a compilation of published cooling ages and a new apatite U-Th/He age, associating the thermal event with the emplacement of a granodiorite pluton at ∼12 Ma.

Experimental Evaluation of pH and Temperature Effects on the Adsorption of Boron onto Clay Minerals

NASA Astrophysics Data System (ADS)

Hoenisch, B.; Marone, D.; Ruprecht, J.

2017-12-01

Modeling the secular evolution of the concentration [B] and isotopic composition (δ11B) of boron in seawater is hampered by limited constraints on the relative sources (i.e. riverine input of weathering products, hydrothermal convection at mid-ocean ridges and fluids expelled from accretionary prisms) and sinks (i.e. alteration of the oceanic crust, adsorption onto clays, and co-precipitation in carbonates) of boron to and from the ocean. Clays remove approximately 28% of total boron from the ocean and quantification of this sink thus represents a major factor for reconstructing the secular evolution of seawater [B] and δ11B over the Cenozoic. However, the relative strength of the clay sink could have been much smaller in the early Cenozoic compared to today, because borate ion as the charged species is preferentially adsorbed onto detrital clays over boric acid, and because the relative abundance of borate in seawater should have been lower under the more acidic conditions of the early Cenozoic. In addition, different clay minerals tend to fractionate boron isotopes differentially, and the relative composition of clay minerals has varied in the past with the dominant climate and weathering patterns on the continents. We have conducted a range of pH (7.5-8.4) and temperature (3-32°C) experiments with four clay minerals (Kaolinite, Illite, Montmorillonite and Chlorite), to build on previously published but limited experimental data. Similar to a previous study and as expected based on the relative abundance of borate ion in seawater, boron adsorption onto these clays increases at higher pH and lower temperatures, but whereas Montmorillonite and Illite absorb similar quantities of boron, Kaolinite is most and Chlorite least efficient in this process. We are now in the process of characterizing the boron isotope fractionation associated with these adsorption experiments.

Incineration and pyrolysis vs. steam gasification of electronic waste.

PubMed

Gurgul, Agnieszka; Szczepaniak, Włodzimierz; Zabłocka-Malicka, Monika

2018-05-15

Constructional complexity of items and their integration are the most distinctive features of electronic wastes. These wastes consist of mineral and polymeric materials and have high content of valuable metals that could be recovered. Elimination of polymeric components (especially epoxy resins) while leaving non-volatile mineral and metallic phases is the purpose of thermal treatment of electronic wastes. In the case of gasification, gaseous product of the process may be, after cleaning, used for energy recovery or chemical synthesis. If not melted, metals from solid products of thermal treatment of electronic waste could be recovered by hydrometallurgical processing. Three basic, high temperature ways of electronic waste processing, i.e. smelting/incineration, pyrolysis and steam gasification were shortly discussed in the paper, giving a special attention to gasification under steam, illustrated by laboratory experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Intracrystalline cation order in a lunar crustal troctolite

NASA Technical Reports Server (NTRS)

Smyth, J. R.

1975-01-01

Lunar sample 76535 appears to be one of the most slowly cooled bits of silicate material yet studied. It provides, therefore, a unique opportunity for the study of ordering processes in the minerals present. A better understanding of these processes may permit better characterization of the thermal history of this and similar rocks. The cation ordering in the olivine is consistent with terrestrial olivines favoring the interpretation that ordering in olivines increases with increasing temperature. In low bronzite, the deviations from the common orthopyroxene space group appear to be caused by cation order on the basis of four M sites instead of two. The degree of cation order in each of these minerals is consistent with the rock having been excavated from its depth of formation by tectonic or impact processes without being reheated above 300 C.

Temperature Effects on Microbial CH4 and CO2 Production in Permafrost-Affected Soils From the Barrow Environmental Observatory

NASA Astrophysics Data System (ADS)

Graham, D. E.; Roy Chowdhury, T.; Zheng, J.; Moon, J. W.; Yang, Z.; Gu, B.; Wullschleger, S. D.

2015-12-01

Warmer Arctic temperatures are increasing the annual soil thaw depth and prolonging the thaw season in Alaskan permafrost zones. This change exposes organic matter buried in the soils and permafrost to microbial degradation and mineralization to form CO2 and CH4. The proportion and fluxes of these greenhouse gases released into the atmosphere control the global feedback on warming. To improve representations of these biogeochemical processes in terrestrial ecosystem models we compared soil properties and microbial activities in core samples of polygonal tundra from the Barrow Environmental Observatory. Measurements of soil water potential through the soil column characterized water binding to the organic and mineral components. This suction combines with temperature to control freezing, gas diffusion and microbial activity. The temperature-dependence of CO2 and CH4 production from anoxic soil incubations at -2, +4 or +8 °C identified a significant lag in methanogenesis relative to CO2 production by anaerobic respiration and fermentation. Changes in the abundance of methanogen signature genes during incubations indicate that microbial population shifts caused by thawing and warmer temperatures drive changes in the mixtures of soil carbon degradation products. Comparisons of samples collected across the microtopographic features of ice-wedge polygons address the impacts of water saturation, iron reduction and organic matter content on CH4 production and oxidation. These combined measurements build process understanding that can be applied across scales to constrain key response factors in models that address Arctic soil warming.

Optical luminescence studies of diffusion times at the potassium ethyl xanthate adsorption layer on the surface of sphalerite minerals

NASA Astrophysics Data System (ADS)

Todoran, R.; Todoran, D.; Anitas, E. M.; Szakács, Zs

2016-08-01

We propose reflectance measurements as a method for the evaluation of the kinetics of adsorption processes, to compute the diffusion times of the adsorption products at the thin layers formed at the sphalerite natural mineral-potassium ethyl xanthate solution interface. The method is based on the intensity measurement of the reflected monochromatic radiation obtained from the mineral-xanthate thin layer as a function of time. These determinations were made at the thin layer formed between the sphalerite or activated sphalerite natural minerals with potassium ethyl xanthate, for different solutions concentrations and pH values at constant temperature. Diffusion times of desorbed molecular species into the liquid bring important information about the global kinetics of the ions in this phase during adsorption processes at interfaces. Analysing the time dependence of this parameter one concluded on the diffusion properties of the xanthate molecule in the solution depending on its concentration and pH, knowing that at the initial time these molecules had a uniform spread. This method enabled us to determine that, in time interval of approximately 35 minutes to achieve dynamic equilibrium in the formation of the interface layer, one had three different kinetic behaviours of our systems. In the first 5-8 min one had highly adsorbent character, the state of equilibrium is followed by low adsorbent properties. Gaining information on the adsorption kinetics in the case of xanthate on mineral surface leads to the optimization of the industrial froth flotation process.

Stochastic Approach to Determine CO2 Hydrate Induction Time in Clay Mineral Suspensions

NASA Astrophysics Data System (ADS)

Lee, K.; Lee, S.; Lee, W.

2008-12-01

A large number of induction time data for carbon dioxide hydrate formation were obtained from a batch reactor consisting of four independent reaction cells. Using resistance temperature detector(RTD)s and a digital microscope, we successfully monitored the whole process of hydrate formation (i.e., nucleation and crystal growth) and detected the induction time. The experiments were carried out in kaolinite and montmorillonite suspensions at temperatures between 274 and 277 K and pressures ranging from 3.0 to 4.0 MPa. Each set of data was analyzed beforehand whether to be treated by stochastic manner or not. Geochemical factors potentially influencing the hydrate induction time under different experimental conditions were investigated by stochastic analyses. We observed that clay mineral type, pressure, and temperature significantly affect the stochastic behavior of the induction times for CO2 hydrate formation in this study. The hydrate formation kinetics along with stochastic analyses can provide basic understanding for CO2 hydrate storage in deep-sea sediment and geologic formation, securing its stability under the environments.

The immersion freezing behavior of mineral dust particles mixed with biological substances

NASA Astrophysics Data System (ADS)

Augustin-Bauditz, S.; Wex, H.; Denjean, C.; Hartmann, S.; Schneider, J.; Schmidt, S.; Ebert, M.; Stratmann, F.

2015-10-01

Biological particles such as bacteria, fungal spores or pollen are known to be efficient ice nucleating particles. Their ability to nucleate ice is due to ice nucleation active macromolecules (INM). It has been suggested that these INM maintain their nucleating ability even when they are separated from their original carriers. This opens the possibility of an accumulation of such INM in e.g., soils, resulting in an internal mixture of mineral dust and INM. If particles from such soils which contain biological INM are then dispersed into the atmosphere due to wind erosion or agricultural processes, they could induce ice nucleation at temperatures typical for biological substances, i.e., above -20 up to almost 0 °C. To explore this hypothesis, we performed a measurement campaign within the research unit INUIT, where we investigated the ice nucleation behavior of mineral dust particles internally mixed with INM. Specifically, we mixed a pure mineral dust sample (illite-NX) with ice active biological material (birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). To characterize the mixing state of the generated aerosol we used different methods which will also be discussed. We found that internally mixed particles, containing ice active biological material, follow the ice nucleation behavior observed for the purely biological particles, i.e. freezing occurs at temperatures at which mineral dusts themselves are not yet ice active. It can be concluded that INM located on a mineral dust particle determine the freezing behavior of that particle.

Carbon dioxide/brine wettability of porous sandstone versus solid quartz: An experimental and theoretical investigation.

PubMed

Alnili, Firas; Al-Yaseri, Ahmed; Roshan, Hamid; Rahman, Taufiq; Verall, Michael; Lebedev, Maxim; Sarmadivaleh, Mohammad; Iglauer, Stefan; Barifcani, Ahmed

2018-08-15

Wettability plays an important role in underground geological storage of carbon dioxide because the fluid flow and distribution mechanism within porous media is controlled by this phenomenon. CO 2 pressure, temperature, brine composition, and mineral type have significant effects on wettability. Despite past research on this subject, the factors that control the wettability variation for CO 2 /water/minerals, particularly the effects of pores in the porous substrate on the contact angle at different pressures, temperatures, and salinities, as well as the physical processes involved are not fully understood. We measured the contact angle of deionised water and brine/CO 2 /porous sandstone samples at different pressures, temperatures, and salinities. Then, we compared the results with those of pure quartz. Finally, we developed a physical model to explain the observed phenomena. The measured contact angle of sandstone was systematically greater than that of pure quartz because of the pores present in sandstone. Moreover, the effect of pressure and temperature on the contact angle of sandstone was similar to that of pure quartz. The results showed that the contact angle increases with increase in temperature and pressure and decreases with increase in salinity. Copyright © 2018 Elsevier Inc. All rights reserved.

Analysis of Heat Stress and the Indoor Climate Control Requirements for Movable Refuge Chambers

PubMed Central

Hao, Xiaoli; Guo, Chenxin; Lin, Yaolin; Wang, Haiqiao; Liu, Heqing

2016-01-01

Movable refuge chambers are a new kind of rescue device for underground mining, which is believed to have a potential positive impact on reducing the rate of fatalities. It is likely to be hot and humid inside a movable refuge chamber due to the metabolism of trapped miners, heat generated by equipment and heat transferred from outside. To investigate the heat stress experienced by miners trapped in a movable refuge chamber, the predicted heat strain (PHS) model was used to simulate the heat transfer process between the person and the thermal environment. The variations of heat stress with the temperature and humidity inside the refuge chamber were analyzed. The effects of air temperature outside the refuge chamber and the overall heat transfer coefficient of the refuge chamber shell on the heat stress inside the refuge chamber was also investigated. The relationship between the limit of exposure duration and the air temperature and humidity was numerically analyzed to determine the upper limits of temperature and humidity inside a refuge chamber. Air temperature of 32 °C and relative humidity of 70% are recommended as the design standard for internal thermal environment control of movable refuge chambers. PMID:27213422

Analysis of Heat Stress and the Indoor Climate Control Requirements for Movable Refuge Chambers.

PubMed

Hao, Xiaoli; Guo, Chenxin; Lin, Yaolin; Wang, Haiqiao; Liu, Heqing

2016-05-20

Movable refuge chambers are a new kind of rescue device for underground mining, which is believed to have a potential positive impact on reducing the rate of fatalities. It is likely to be hot and humid inside a movable refuge chamber due to the metabolism of trapped miners, heat generated by equipment and heat transferred from outside. To investigate the heat stress experienced by miners trapped in a movable refuge chamber, the predicted heat strain (PHS) model was used to simulate the heat transfer process between the person and the thermal environment. The variations of heat stress with the temperature and humidity inside the refuge chamber were analyzed. The effects of air temperature outside the refuge chamber and the overall heat transfer coefficient of the refuge chamber shell on the heat stress inside the refuge chamber was also investigated. The relationship between the limit of exposure duration and the air temperature and humidity was numerically analyzed to determine the upper limits of temperature and humidity inside a refuge chamber. Air temperature of 32 °C and relative humidity of 70% are recommended as the design standard for internal thermal environment control of movable refuge chambers.

Swelling properties of montmorillonite and beidellite clay minerals from molecular simulation: Comparison of temperature interlayer cation, and charge location effects

DOE PAGES

Teich-McGoldrick, Stephanie L.; Greathouse, Jeffery A.; Jove-Colon, Carlos F.; ...

2015-08-27

In this study, the swelling properties of smectite clay minerals are relevant to many engineering applications including environmental remediation, repository design for nuclear waste disposal, borehole stability in drilling operations, and additives for numerous industrial processes and commercial products. We used molecular dynamics and grand canonical Monte Carlo simulations to study the effects of layer charge location, interlayer cation, and temperature on intracrystalline swelling of montmorillonite and beidellite clay minerals. For a beidellite model with layer charge exclusively in the tetrahedral sheet, strong ion–surface interactions shift the onset of the two-layer hydrate to higher water contents. In contrast, for amore » montmorillonite model with layer charge exclusively in the octahedral sheet, weaker ion–surface interactions result in the formation of fully hydrated ions (two-layer hydrate) at much lower water contents. Clay hydration enthalpies and interlayer atomic density profiles are consistent with the swelling results. Water adsorption isotherms from grand canonical Monte Carlo simulations are used to relate interlayer hydration states to relative humidity, in good agreement with experimental findings.« less

Promising Technologies of Mining and Processing of Solid Minerals

NASA Astrophysics Data System (ADS)

Shabaev, Sergey; Ivanov, Seregey; Vakhianov, Evgeniy

2017-11-01

The continuing growth in mineral extraction entails an increase in industrial waste, which in turn has a negative impact on the environment. Rubber-tired vehicles, in which the tires wear colossally, is mainly used as a transport for loading, unloading, transportation and other types of work in the extraction of solid minerals. The used tires are not disposed in any way, but are stored in special areas where harmful toxic substances are emitted under the influence of ultraviolet rays. Therefore, a decision was made to find a method for utilization and rational use of industrial waste in the road construction sector. The operating temperature of composite rubber-bituminous binders based on rubber crumb from the used automobile tires is estimated in this paper, which is necessary for assigning technological parameters of production and laying of asphalt-concrete mixtures produced on their basis. It is established that composite rubber-bituminous binders based on rubber chips from the used automobile tires, produced according to the two-stage technology, have the same viscosity as the original petroleum bitumen, at a temperature increased by 20°C.

Destabilization of emulsions by natural minerals.

PubMed

Yuan, Songhu; Tong, Man; Wu, Gaoming

2011-09-15

This study developed a novel method to destabilize emulsions and recycle oils, particularly for emulsified wastewater treatment. Natural minerals were used as demulsifying agents, two kinds of emulsions collected from medical and steel industry were treated. The addition of natural minerals, including artificial zeolite, natural zeolite, diatomite, bentonite and natural soil, could effectively destabilize both emulsions at pH 1 and 60 °C. Over 90% of chemical oxygen demand (COD) can be removed after treatment. Medical emulsion can be even destabilized by artificial zeolite at ambient temperature. The mechanism for emulsion destabilization by minerals was suggested as the decreased electrostatic repulsion at low pH, the enhanced gathering of oil microdroplets at elevated temperature, and the further decreased surface potential by the addition of minerals. Both flocculation and coalescence were enhanced by the addition of minerals at low pH and elevated temperature. Copyright © 2011 Elsevier B.V. All rights reserved.

Nanophase Carbonates on Mars: Implications for Carbonate Formation and Habitability

NASA Technical Reports Server (NTRS)

Archer, P. Douglas, Jr.; Lauer, H. Vern; Ming, Douglas W.; Niles, Paul B.; Morris, Richard V.; Rampe, Elizabeth B.; Sutter, Brad

2014-01-01

Despite having an atmosphere composed primarily of CO2 and evidence for abundant water in the past, carbonate minerals have only been discovered in small amounts in martian dust [1], in outcrops of very limited extent [2, 3], in soils in the Northern Plains (the landing site of the 2007 Phoenix Mars Scout Mission) [4] and may have recently been detected in aeolian material and drilled and powdered sedimentary rock in Gale Crater (the Mars Science Laboratory [MSL] landing site) [5]. Thermal analysis of martian soils by instruments on Phoenix and MSL has demonstrated a release of CO2 at temperatures as low as 250-300 degC, much lower than the traditional decomposition temperatures of calcium or magnesium carbonates. Thermal decomposition temperature can depend on a number of factors such as instrument pressure and ramp rate, and sample particle size [6]. However, if the CO2 released at low temperatures is from carbonates, small particle size is the only effect that could have such a large impact on decomposition temperature, implying the presence of extremely fine-grained (i.e., "nanophase" or clay-sized) carbonates. We hypothesize that this lower temperature release is the signature of small particle-sized (clay-sized) carbonates formed by the weathering of primary minerals in dust or soils through interactions with atmospheric water and carbon dioxide and that this process may persist under current martian conditions. Preliminary work has shown that clay-sized carbonate grains can decompose at much lower temperatures than previously thought. The first work took carbonate, decomposed it to CaO, then flowed CO2 over these samples held at temperatures >100 degC to reform carbonates. Thermal analysis confirmed that carbonates were indeed formed and transmission electron microsopy was used to determine crystal sized were on the order of 10 nm. The next step used minerals such as diopside and wollastonite that were sealed in a glass tube with a CO2 and H2O source. After reacting these materials for a number of hours, thermal analysis demonstrated the formations of carbonates that decomposed at temperatures as low as 500 degC [7]. Further work is underway to carry out the weathering process under more Mars-like conditions (low pressure and low temperature) to determine if the carbonate decomposition temperature can be shifted to even lower temperatures, consistent with what has been detected by thermal analysis instruments on Mars.

The role of hydrothermal processes in concentrating high-field strength elements in the Strange Lake peralkaline complex, northeastern Canada

NASA Astrophysics Data System (ADS)

Salvi, Stefano; Williams-Jones, Anthony E.

1996-06-01

The middle-Proterozoic peralkaline pluton at Strange Lake, Quebec/Labrador, comprises hypersolvus to subsolvus phases which are unusually enriched in Zr, Y, REEs, Nb, Be, and F, as exotic alkali and alkaline-earth silicate minerals. The highest concentrations of these elements are in subsolvus granite, which underwent intense low temperature (≤200°C) hydrothermal alteration involving hematization and the replacement of alkali high-field strength element (HFSE) minerals by calcic equivalents. This alteration is interpreted to have been caused by meteoric or formational waters. High temperature (≥ 350°C) alteration, attributed to orthomagmatic fluids, is evident in other parts of the subsolvus granite by the replacement of arfvedsonite by aegirine. Comparisons of the chemical compositions of fresh and altered rocks indicate that rocks subjected to high temperature alteration were chemically unaffected, except for depletion in Zr, Y, and HREEs. These elements were appreciably enriched in rocks that underwent low temperature alteration. Other elements affected by low temperature alteration include Ca and Mg, which were added and Na, which was removed. Available data on HFSE speciation in aqueous fluids and the chemistry of the pluton, suggest that the HFSEs were transported as fluoride complexes. If this was the case, the low temperature fluid could not have been responsible for HFSE transport, because the high concentration of Ca and low solubility of fluorite would have buffered F - activity to levels too low to permit significant complexation. We propose that HFSE mineralization and accompanying alteration were the result of mixing, in the apical parts of the pluton, of a F-rich, essentially Ca-free orthomagmatic fluid containing significant concentrations of HFSEs, with an externally derived meteoric-dominated fluid, enriched in Ca as a result of interaction with calc-silicate gneisses and gabbros. According to this interpretation, the latter fluid was responsible for the exchange of Ca for alkalis, mainly Na, in HFSE-rich minerals and, by sharply reducing F - activity in the mixed fluid through fluorite precipitation and/or increasing pH, destabilised the HFSE-fluoride complexes, causing deposition of HFSE-bearing minerals. An important implication of this study is that major HFSE enrichment may be restricted to those rare cases where F-rich, Ca-free, metal leaching environments and Ca-rich depositional environments are juxtaposed.

Radioactive Demonstrations Of Fluidized Bed Steam Reforming (FBSR) With Hanford Low Activity Wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, C. M.; Crawford, C. L.; Burket, P. R.

Several supplemental technologies for treating and immobilizing Hanford low activity waste (LAW) are being evaluated. One immobilization technology being considered is Fluidized Bed Steam Reforming (FBSR) which offers a low temperature (700-750?C) continuous method by which wastes high in organics, nitrates, sulfates/sulfides, or other aqueous components may be processed into a crystalline ceramic (mineral) waste form. The granular waste form produced by co-processing the waste with kaolin clay has been shown to be as durable as LAW glass. The FBSR granular product will be monolithed into a final waste form. The granular component is composed of insoluble sodium aluminosilicate (NAS)more » feldspathoid minerals such as sodalite. Production of the FBSR mineral product has been demonstrated both at the industrial, engineering, pilot, and laboratory scales on simulants. Radioactive testing at SRNL commenced in late 2010 to demonstrate the technology on radioactive LAW streams which is the focus of this study.« less

Laboratory study of adsorption and deliquescence on the surface of Mars

NASA Astrophysics Data System (ADS)

Nikolakakos, George; Whiteway, James A.

2018-07-01

A sample of the zeolitic mineral chabazite was subjected to a range of water vapor pressures and temperatures found on present day Mars. Laser Raman scattering was applied to detect the relative amounts of water and carbon dioxide adsorbed by the sample. Results show that zeolites are capable of adsorbing water from the atmosphere on diurnal time scales and that Raman scattering spectroscopy provides a promising method for detecting this process during a landed mission. When the water vapor pressure and temperature were sufficiently low, the zeolite sample also adsorbed carbon dioxide, resulting in the simultaneous adsorption of water and carbon dioxide on the surface mineral grains. Additional experiments were carried out using a mixture of magnesium perchlorate and chabazite. The sample of mixed surface material remained visually unchanged during water adsorption, but was found to darken during deliquescence.

Mineral-microbial interaction in long term experiments with sandstones and reservoir fluids exposed to CO2

NASA Astrophysics Data System (ADS)

Kasina, Monika; Morozova, Daria; Pellizzari, Linda; Würdemann, Hilke

2013-04-01

Microorganisms represent very effective geochemical catalysts, and may influence the process of the CO2 storage significantly. The goal of this study is to characterize the interactions between minerals and microorganisms during their exposure to the CO2 in a long term experiment in high pressure vessels to better understand the influence of biological processes on the composition of the reservoir sandstones and the long term stability of CO2 storage. The natural gas reservoir, proposed for the CO2 storage is characterized by high salinity (up to 420 g/l) and temperatures around 130°C, at depth of approximately 3.5 km. Microbial community of the reservoir fluid samples was dominated by different H2-oxidising, thiosulfate-oxidising and biocorrosive thermophilic bacteria as well as microorganisms similar to representatives from other deep environments, which have not previously been cultivated. The cells were attached to particles and were difficult to detect because of low cell numbers (Morozova et al., 2011). For the long term experiments, the autoclaved rock core samples from the core deposit were grinded, milled to the size of 0.5 mm and incubated with fresh reservoir fluids as inoculum for indigenous microorganisms in a N2/CH4/H2-atmosphere in high pressure vessels at a temperature of 80°C and pressure of 40 bars. Incubation was performed under lower temperature than in situ in order to favor the growth of the dormant microorganisms. After three months of incubation samples were exposed to high CO2 concentrations by insufflating it into the vessels. The sampling of rock and fluid material was executed 10 and 21 months after start of the experiment. Mineralogical analyses performed using XRD and SEM - EDS showed that main mineral components are quartz, feldspars, dolomite, anhydrite and calcite. Chemical fluid analyses using ICP-MS and ICP-OES showed that after CO2 exposure increasing Si4+ content in the fluid was noted after first sampling (ca. 25 relative %), whereas after the second sampling it decreased (to 31 relative %) in comparison to the reservoir fluid sample. This may suggest dissolution of silicate minerals at first, and secondary precipitation at second stage of experiment. In addition, immobilization of heavy metals dispersed within silicate minerals was also detected. An increase of Ca (3.2 up to 13% relative), SO4 (up to 14 relative %) and Fetot (47 and 24% relative) were also detected after first and second sampling respectively and may suggest dissolution of cements and iron rich minerals. The concentration of organic acids increased relatively by 12.5 % and 25% after first and second sampling respectively might be an indication for metabolic activity of microorganism or an effect of mobilisation due to CO2 exposure. The presence of newly formed mineral phases was detected using SEM-EDS. Quartz, albite and illite precipitation is a common process in all studied samples. However only illite is considered to be of bacterial origin, nevertheless its crystallization can also occur as a consequence of inorganic diagenetic processes. Further analyses of the microbial community composition, quantity and activity will bring a more insight into the CO2 exposure processes. Daria Morozova, Dagmar Kock, Martin Krüger, and Hilke Würdemann. Biogeochemical and microbial characterization of reservoir fluids from a gas field (Altmark). Geotechnologien 2011

Generation of Hydrogen and Methane during Experimental Low-Temperature Reaction of Ultramafic Rocks with Water

NASA Astrophysics Data System (ADS)

McCollom, Thomas M.; Donaldson, Christopher

2016-06-01

Serpentinization of ultramafic rocks is widely recognized as a source of molecular hydrogen (H2) and methane (CH4) to support microbial activity, but the extent and rates of formation of these compounds in low-temperature, near-surface environments are poorly understood. Laboratory experiments were conducted to examine the production of H2 and CH4 during low-temperature reaction of water with ultramafic rocks and minerals. Experiments were performed by heating olivine or harzburgite with aqueous solutions at 90°C for up to 213 days in glass bottles sealed with butyl rubber stoppers. Although H2 and CH4 increased steadily throughout the experiments, the levels were very similar to those found in mineral-free controls, indicating that the rubber stoppers were the predominant source of these compounds. Levels of H2 above background were observed only during the first few days of reaction of harzburgite when CO2 was added to the headspace, with no detectable production of H2 or CH4 above background during further heating of the harzburgite or in experiments with other mineral reactants. Consequently, our results indicate that production of H2 and CH4 during low-temperature alteration of ultramafic rocks may be much more limited than some recent experimental studies have suggested. We also found no evidence to support a recent report suggesting that spinels in ultramafic rocks may stimulate H2 production. While secondary silicates were observed to precipitate during the experiments, formation of these deposits was dominated by Si released by dissolution of the glass bottles, and reaction of the primary silicate minerals appeared to be very limited. While use of glass bottles and rubber stoppers has become commonplace in experiments intended to study processes that occur during serpentinization of ultramafic rocks at low temperatures, the high levels of H2, CH4, and SiO2 released during heating indicate that these reactor materials are unsuitable for this purpose.

EM Properties of Magnetic Minerals at RADAR Frequencies

NASA Technical Reports Server (NTRS)

Stillman, D. E.; Olhoeft, G. R.

2005-01-01

Previous missions to Mars have revealed that Mars surface is magnetic at DC frequency. Does this highly magnetic surface layer attenuate RADAR energy as it does in certain locations on Earth? It has been suggested that the active magnetic mineral on Mars is titanomaghemite and/or titanomagnetite. When titanium is incorporated into a maghemite or magnetite crystal, the Curie temperature can be significantly reduced. Mars has a wide range of daily temperature fluctuations (303K - 143K), which could allow for daily passes through the Curie temperature. Hence, the global dust layer on Mars could experience widely varying magnetic properties as a function of temperature, more specifically being ferromagnetic at night and paramagnetic during the day. Measurements of EM properties of magnetic minerals were made versus frequency and temperature (300K- 180K). Magnetic minerals and Martian analog samples were gathered from a number of different locations on Earth.

Inactive Mineral Filler as a Stiffness Modulus Regulator in Foamed Bitumen-Modified Recycled Base Layers

NASA Astrophysics Data System (ADS)

Buczyński, Przemyslaw; Iwański, Marek

2017-10-01

The article presents the results of a cold recycled mix test with a foam bitumen including the addition of the inactive mineral filler as a dust of basalt. Basalt dust was derived from dedusting system by extraction of aggregates in the mine. Assessment of the impact of a basalt dust on the properties of a recycled base layer was carried out in terms of the amount of mineral filler (basalt) in the composition of the mineral mixture. This experiment involved a dosing of mineral filler in range from 5 to 20% with steps of 7.5% in the mineral mixture composition. The foamed bitumen was performed at optimum foaming process settings (ie. bitumen temperature, air pressure) and at 2.5% of the water content. The amount of a hydraulic binder as a Portland cement was 2.0%. The evaluation of rheological properties allowed to determine whether the addition of inactive mineral fillers can act as a stiffness modulus controller in the recycled base layer. The analysis of the rheological properties of a recycled base layer in terms of the amount of inactive fillers was performed in accordance with given standard EN 12697-26 Annex D. The study was carried out according to the direct tension-compression test methodology on cylindrical samples. The sample was subjected to the oscillatory sinusoidal strain ε0 < 25με. Studies carried out at a specific temperature set-points: - 7°C, 5°C, 13°C, 25°C and 40°C and at the frequency 0.1 Hz, 0.3 Hz, 1 Hz, 3 Hz, 10 Hz and 20 Hz. The obtained results allow to conclude that the use of an inactive filler can reduce the stiffness of an appropriate designed mixes of the cold recycled foundation. In addition, the analysis of the relation E‧-E″ showed a similar behaviour of a recycled base, regardless of the amount of inactive fillers in the mix composition, at high temperatures/high frequency of induced load.

The role of organo-mineral interactions on the capacity of soils to store carbon

NASA Astrophysics Data System (ADS)

Georgiou, K.; Abramoff, R. Z.; Riley, W. J.; Torn, M. S.

2017-12-01

Observed patterns of soil organic carbon (SOC) content across geochemical regimes are signatures of process and provide opportunities to understand the underlying decomposition and stabilization mechanisms that can guide their representation in models. The type of sorption equation used in soil decomposition models has large implications for both SOC stock and its temperature sensitivity. Here we compared different model formulations of SOC sorption to mineral surfaces, motivated by the myriad of chemical associations between organic and mineral surfaces, and used laboratory and field incubations to inform model parameters. We explored linear, Langmuir, and Freundlich adsorption models, where the latter emerges from heterogeneous compositions of substrate and surface components. We show the effect of model representations on predicted trends of SOC as a function of mineralogy and discuss the role of soil C saturation on emergent patterns. Specifically, our results highlight that the response of mineral-associated (`protected') SOC to changes in plant C inputs depends greatly on the C saturation deficit of the soil and thus, the representation of organo-mineral interactions in models can lead to nonlinear steady-state responses in protected SOC. We also find that, consistent with field experiments, the trend in protected SOC and mineral C saturation capacity is linear, but, interestingly, the slope depends on the degree of C saturation. We contend that this latter finding is an important consideration for field studies that did not find a universal slope and interpreted this as an inability of mineralogy to explain observed patterns. Our results also suggest that warming affects this slope, with higher temperatures causing a decrease in the amount of protected C for a given saturation capacity and C input rate. This means that more C inputs will be needed to keep the same amount of protected C at higher temperatures. Organo-mineral interactions play a key role in governing soil C stabilization and long-term storage, and thus, improving their representation for inclusion in Earth system models is crucial for understanding and predicting feedbacks under global change.

Using Laboratory Methods to Better Understand Refractory Cloud Formation in Exoplanet Atmospheres

NASA Astrophysics Data System (ADS)

Kohler, E.; Ferguson, F.

2017-12-01

The high number of extrasolar planets found in recent years has brought a new importance to planetary atmospheres. These recently discovered planets show a large diversity in their masses, temperatures, orbital periods, and other properties. With such a diverse mix of planetary parameters, it is safe to assume that the atmospheric properties are just as varied. Recent literature suggests silicates and metals as possible condensates in extrasolar planetary atmospheres as well as the atmospheres of brown dwarfs. While theoretical studies have laid the foundation of cloud formation analysis, their findings still need to be validated via experiments. A verification of the condensation and vaporization predictions of refractory materials needs to be found in order to assist global circulation models in being as accurate as possible. The stability of minerals identified in the literature as potential candidates, will be tested in a thermogravimetric balance. The minerals will be pumped under vacuum for twenty-four hours under room temperature and then heated to a predetermined high temperature, dependent on the expected vaporization temperature of that sample. If there is apparent mass loss, then the temperature will be lowered at preset durations and mass measurements will be taken in similar measured increments. The data will be processed by a computer program in order to calculate the mass loss as a function of temperature. The current cloud formation and global circulation models are very important to the field of planetary science but their accuracy is hindered by the lack of experimental data. The aim of this work is to investigate the mineral stability of potential condensates in an effort to explain the formation of refractory clouds in the atmospheres of extrasolar planets and brown dwarfs.

Mineral resource of the month: mercury

USGS Publications Warehouse

Brooks, William E.

2006-01-01

The ore of mercury, cinnabar, is soft and dark red, and native mercury is one of a few metals that is liquid at room temperatures. Cinnabar from Almaden, Spain, the world’s oldest producing mercury mine, was used during Roman times, and the chemical symbol for mercury (Hg) is from "hydrargyrum," from the Greek word meaning liquid silver. Cinnabar and mercury are associated with some hydrothermal mineral deposits and occur in fine-grained or sedimentary and volcanic rocks near hot springs or volcanic centers. Mercury may be recovered as a byproduct of processing copper, gold, lead-zinc or silver.

Investigations of Iron Minerals Formed by Dissimilatory Alkaliphilic Bacterium with 57Fe Mössbauer Spectroscopy

NASA Astrophysics Data System (ADS)

Chistyakova, N. I.; Rusakov, V. S.; Shapkin, A. A.; Zhilina, T. N.; Zavarzina, D. G.; Lančok, A.; Kohout, J.

2010-07-01

Anaerobic alkaliphilic bacterium of Geoalkalibacter ferrihydriticus type (strain Z-0531), isolated from a bottom sediment sample from the weakly mineralized soda Lake Khadyn, have been analyzed. The strain uses the amorphous Fe(III)-hydroxide (AFH) as an electron acceptor and acetate CH3COO- as an electron donor. Mössbauer investigations of solid phase samples obtained during the process of the bacterium growth were carried out at room temperature, 77.8 K, 4.2 K without and with the presence of an external magnetic field (6 T) applied perpendicular to the γ-bebam.

Mineral Wells FAA, Texas. Ft. Wolters Mineral Wells/Texas. Revised Uniform Summary of Surface Weather Observations. Part A-F

DTIC Science & Technology

1972-05-18

DIRECTION AND SPEED (FROM HOURLY OBSERVATIONS) 0394,3 FT WIILTF.R’ AAF TEX/ MINERAI . WELLS 49-65,67-70 JUI) STATION STATION AM TRANS MONTM ALL WtI4THEk...DAIA PROCESSING DIVISCJN .~USAF ETAC PSYCHROMET(RICSU M R4 ’ AIR WEATHER SERYICE/MAC 03943 FT WO1LTER$ AAF TEX/ MINERAI . WELL$ 49*63#67-70 MAR____...AAF TEX/ MINERAI . WELLS 49-65b67-70 APRI STATION STATION NAME YEARS MONTH PAGE 2 0900-1100 HOURS (L. S. T.) Temp. WET BULB TEMPERATURE DEPRESSION (F

Barringerite Fe2P from Pyrometamorphic Rocks of the Hatrurim Formation, Israel

NASA Astrophysics Data System (ADS)

Britvin, S. N.; Murashko, M. N.; Vapnik, E.; Polekhovsky, Yu. S.; Krivovichev, S. V.

2017-12-01

The article provides a detailed mineralogical and crystallochemical description (including refinement of the crystal structure) of the first finding of the phosphide class mineral barringerite, Fe2P, from terrestrial pyrometamorphic rocks of the Hatrurim Formation in Israel. The mineral occurs in the association of the so-called paralavas—initially silicate—carbonate sedimentary rocks that remelted during pyrometamorphic processes at a temperature above 1000°C and at a low pressure. Questions on the genesis and crystal chemistry of barringerite are discussed in connection with another polymorphic iron phosphide, allabogdanite (Fe,Ni)2P.

Data Processing and Experimental Design for Micrometeorite Impacts in Small Bodies

NASA Technical Reports Server (NTRS)

Jensen, E.; Lederer, S.; Smith, D.; Strojia, C.; Cintala, M.; Zolensky, M.; Keller, L.

2014-01-01

Comets and asteroids have been altered from their original "pristine" state by impacts occurring throughout their 4.5 billion year lives: [1]. Proof of shock deformation has been detected in the crystal structure of several Stardust samples from Comet Wild 2 [2, 3]. Analyses indicated that the planar dislocations in the crystal structure of the minerals had been imparted by impacts sustained during their lives, and not due to the aerogel capture process. Distortions to crystal structure also affect the ideal absorption spectra in the infrared, and [4], thus providing indirect evidence of its impact history and a means of remotely investigating the impact history of small bodies through comparing laboratory spectra with spectra observed by telescopes or spacecraft. -The effects of impacts propagating shock waves through minerals were investigated through laboratory impact experiments. Utilizing NASA Johnson Space Center's Experimental Impact Laboratory, projectiles were fired from the vertical gun at velocities ranging from 2.0 to 2.8 km/sec, projected impact velocities between Kuiper Belt Objects. Two types of projectiles were used, including spherical alumina ceramic, whose density mimics that of rock, and cylinders made from the same material that they impacted. The target materials chosen for testing included: OLIVINES forsterite (Mg2SiO4) and fayalite, Fe2SiO4); PYROXENES enstatite (Mg2Si2O6) and diopside (MgCaSi2O6); and CARBONATES magnesite (MgCO3) and siderite (FeCO3). Targets were impacted at either 25 C or cooled to -20 C to examine the effects of temperature, if any, on lattice distortions during the shock propagation. As comets and asteroids can undergo a wide range of temperatures in their orbital lifetimes, the effect of temperature on the equation of state of minerals being shocked needs to be examined for interpreting the results of these experiments. The porosity of the target mineral is varied by either grinding it into a powder/granular texture or as whole mineral rocks to investigate the differences in shock propagation when voids are present. By varying velocity, ambient temperature, and porosity, we can investigate different variables affecting impacts in the solar system. -Data indicates that there is a non-linear relationship between peak shock pressure and the variation in infrared spectral absorbances by the distorted crystal structure. The maximum variability occurs around 37 GPa in enstatite and forsterite. The particle size distribution of the impacted material similarly changes with velocity/peak shock pressure. -The experiments described above are designed to measure the near- to mid-IR effects from these changes to the mineral structure. See Lederer et al., this meeting for additional experimental results.

Mineral Phases and Release Behaviors of As in the Process of Sintering Residues Containing As at High Temperature

PubMed Central

Wang, Xingrun; Zhang, Fengsong; Nong, Zexi

2014-01-01

To investigate the effect of sintering temperature and sintering time on arsenic volatility and arsenic leaching in the sinter, we carried out experimental works and studied the structural changes of mineral phases and microstructure observation of the sinter at different sintering temperatures. Raw materials were shaped under the pressure of 10 MPa and sintered at 1000~1350°C for 45 min with air flow rate of 2000 mL/min. The results showed that different sintering temperatures and different sintering times had little impact on the volatilization of arsenic, and the arsenic fixed rate remained above 90%; however, both factors greatly influenced the leaching concentration of arsenic. Considering the product's environmental safety, the best sintering temperature was 1200°C and the best sintering time was 45 min. When sintering temperature was lower than 1000°C, FeAsS was oxidized into calcium, aluminum, and iron arsenide, mainly Ca3(AsO4)2 and AlAsO4, and the arsenic leaching was high. When it increased to 1200°C, arsenic was surrounded by a glass matrix and became chemically bonded inside the matrix, which lead to significantly lower arsenic leaching. PMID:24723798

Peptides Enhance Mg Content of Calcite: Toward a Process-Based Understanding of Proxy Models

NASA Astrophysics Data System (ADS)

Dove, P.; Stephenson, A.; Wu, L.; Wu, K.; de Yoreo, J.; Hoyer, J.

2008-12-01

Investigations of modern organisms relating magnesium content of calcified skeletons to temperature often exhibit unexplained deviations from the signature expected for inorganically precipitated calcite. These 'vital effects' are believed to have kinetic and taxonomic origins but the mechanistic basis for measured offsets remains unclear. A complicating factor is that mineralization is isolated from the external environment within an organic-rich matrix whose roles in mineralization are implicated but not well understood. Here we show that a simple hydrophilic peptide, sharing the same acidic character as macromolecules isolated from sites of calcification, increases the magnesium content of calcite up to 3 mol%. Using in situ AFM, we demonstrate that (Asp3Gly)6Asp3 also enhances growth rate and step edge energy of calcite compared to inorganic controls. Kinetic and thermodynamic measurements indicate that biomolecules interact with calcite surfaces to lower the energy barrier to desolvating the more strongly hydrated magnesium ion, thereby increasing the probability of its incorporation relative to calcium. Comparisons to previous studies that correlate Mg content of carbonate minerals with temperature show this peptide-induced Mg- enhancement is equivalent to offsets of several degrees Centigrade. The findings suggest local macromolecule chemistry influences Mg signatures- a plausible origin of vital effects. Further, studies of nonskeletal carbonates have long-asked whether the natural marine humic and protein substances found in sedimentary environments may influence mineralization. These insights provide a physical basis for anecdotal evidence that organic chemistry modulates the mineralization of inorganic carbonates.

Experimental evidence for Nd-Sr decoupling during low-temperature (20-170oC) hydrothermal alteration of olivine and clinopyroxene

NASA Astrophysics Data System (ADS)

Frisby, C. P.; Bizimis, M.; Foustoukos, D.

2011-12-01

Serpentinization of abyssal peridotites represents a major reaction front between the hydrosphere and the mantle. While several studies have investigated the phase equilibria relationships that describe seawater - peridotite interaction at high temperature hydrothermal conditions (~400oC), there is limited data on the elemental mass exchange between seawater and ultramafic lithologies at temperatures similar to those expected at the flanks of hydrothermal vent sites. To better constrain seawater - peridotite elemental exchange alteration processes at low-temperatures, a series of experiments were conducted involving natural mantle olivine (Fo=90) and clinopyroxene coexisting with synthetic seawater enriched in elemental or isotopically enriched Sr, Ba, Nd, Sm, Gd, Dy, Yb, Pb, and U. The experiments were performed at temperatures from ambient to 170oC (at saturation vapor pressure), ranging from 15 minutes to 8 weeks and at water/rock mass ratios ~20. Our data shows strong decoupling between alkaline earth elements (Sr, Ba) and rare earth elements (REE). Overall, the REE are quantitatively removed from the solution to the mineral surface while Sr and Ba invariably remain in solution. In detail, we find that the rate of REE removal is proportional to temperature and inversely proportional to particle size distribution. For example at the 350-200um olivine grain size experiments 60% of REE removal occurred in 7 days at ambient temperature and in 6 hours at 100oC. No difference was observed on the removal rates between clinopyroxene and olivine. Additionally, we observe a fractionation of REE in solution where the HREE were removed at a faster rate than the LREE. The calculated apparent kDs for the experiments that approached steady state are similar to Fe-hydroxide scavenging experiments, and importantly show the tetrad effect in REE. We note in the experiments run with clinopyroxene and isotopically enriched seawater at 170oC, results indicate a simultaneous REE precipitation-dissolution process at the seawater/mineral interface, suggesting a bi-directional exchange between the rock and the solution. The decoupling between REE, and Sr implies that during low-temperature peridotite - seawater reaction, Nd may be preferentially deposited on the peridotite mineral surface while Sr, in the absence of carbonate precipitation, may not. The implications on the estimates of integrated water/rock mass ratios using bulk rock Sr-Nd isotopes in serpentinites will be discussed.

Mechanisms for chemostatic behavior in catchments: implications for CO2 consumption by mineral weathering

USGS Publications Warehouse

Clow, David W.; Mast, M. Alisa

2010-01-01

Concentrations of weathering products in streams often show relatively little variation compared to changes in discharge, both at event and annual scales. In this study, several hypothesized mechanisms for this “chemostatic behavior” were evaluated, and the potential for those mechanisms to influence relations between climate, weathering fluxes, and CO2 consumption via mineral weathering was assessed. Data from Loch Vale, an alpine catchment in the Colorado Rocky Mountains, indicates that cation exchange and seasonal precipitation and dissolution of amorphous or poorly crystalline aluminosilicates are important processes that help regulate solute concentrations in the stream; however, those processes have no direct effect on CO2 consumption in catchments. Hydrograph separation analyses indicate that old water stored in the subsurface over the winter accounts for about one-quarter of annual streamflow, and almost one-half of annual fluxes of Na and SiO2 in the stream; thus, flushing of old water by new water (snowmelt) is an important component of chemostatic behavior. Hydrologic flushing of subsurface materials further induces chemostatic behavior by reducing mineral saturation indices and increasing reactive mineral surface area, which stimulate mineral weathering rates. CO2 consumption by carbonic acid mediated mineral weathering was quantified using mass-balance calculations; results indicated that silicate mineral weathering was responsible for approximately two-thirds of annual CO2 consumption, and carbonate weathering was responsible for the remaining one-third. CO2 consumption was strongly dependent on annual precipitation and temperature; these relations were captured in a simple statistical model that accounted for 71% of the annual variation in CO2 consumption via mineral weathering in Loch Vale.

Biorefining of wheat straw: accounting for the distribution of mineral elements in pretreated biomass by an extended pretreatment-severity equation.

PubMed

Le, Duy Michael; Sørensen, Hanne R; Knudsen, Niels Ole; Schjoerring, Jan K; Meyer, Anne S

2014-01-01

Mineral elements present in lignocellulosic biomass feedstocks may accumulate in biorefinery process streams and cause technological problems, or alternatively can be reaped for value addition. A better understanding of the distribution of minerals in biomass in response to pretreatment factors is therefore important in relation to development of new biorefinery processes. The objective of the present study was to examine the levels of mineral elements in pretreated wheat straw in response to systematic variations in the hydrothermal pretreatment parameters (pH, temperature, and treatment time), and to assess whether it is possible to model mineral levels in the pretreated fiber fraction. Principal component analysis of the wheat straw biomass constituents, including mineral elements, showed that the recovered levels of wheat straw constituents after different hydrothermal pretreatments could be divided into two groups: 1) Phosphorus, magnesium, potassium, manganese, zinc, and calcium correlated with xylose and arabinose (that is, hemicellulose), and levels of these constituents present in the fiber fraction after pretreatment varied depending on the pretreatment-severity; and 2) Silicon, iron, copper, aluminum correlated with lignin and cellulose levels, but the levels of these constituents showed no severity-dependent trends. For the first group, an expanded pretreatment-severity equation, containing a specific factor for each constituent, accounting for variability due to pretreatment pH, was developed. Using this equation, the mineral levels could be predicted with R(2) > 0.75; for some with R(2) up to 0.96. Pretreatment conditions, especially pH, significantly influenced the levels of phosphorus, magnesium, potassium, manganese, zinc, and calcium in the resulting fiber fractions. A new expanded pretreatment-severity equation is proposed to model and predict mineral composition in pretreated wheat straw biomass.

Critical Materials Needs

DTIC Science & Technology

1975-05-01

Waste-to-energy systems Recycling of materials from refuse Desulfurization of flue gases from electric power plants Sattelle Specialists...High-Temperature Gas -Turbine Engines for Automotive Applications Initiation of Task II and Task III (Task II: Description of Technologies and...3 - • Mining and Minerals Processing • Ocean Engineering • Transportation • Waste Treatment and Environmental Control The technologies

Responses of redwood soil microbial community structure and N transformations to climate change

Treesearch

Damon C. Bradbury; Mary K. Firestone

2012-01-01

Soil microorganisms perform critical ecosystem functions, including decomposition, nitrogen (N) mineralization and nitrification. Soil temperature and water availability can be critical determinants of the rates of these processes as well as microbial community composition and structure. This research examined how changes in climate affect bacterial and fungal...

Sulfate-reducing bacteria influence the nucleation and growth of mackinawite and greigite

NASA Astrophysics Data System (ADS)

Picard, Aude; Gartman, Amy; Clarke, David R.; Girguis, Peter R.

2018-01-01

Sedimentary iron sulfide minerals play a key role in maintaining the oxygenation of Earth's atmosphere over geological timescales; they also record critical geochemical information that can be used to reconstruct paleo-environments. On modern Earth, sedimentary iron sulfide mineral formation takes places in low-temperature environments and requires the production of free sulfide by sulfate-reducing microorganisms (SRM) under anoxic conditions. Yet, most of our knowledge on the properties and formation pathways of iron sulfide minerals, including pyrite, derives from experimental studies performed in abiotic conditions, and as such the role of biotic processes in the formation of sedimentary iron sulfide minerals is poorly understood. Here we investigate the role of SRM in the nucleation and growth of iron sulfide minerals in laboratory experiments. We set out to test the hypothesis that SRM can influence Fe-S mineralization in ways other than providing sulfide through the comparison of the physical properties of iron sulfide minerals precipitated in the presence and in the absence of the sulfate-reducing bacterium Desulfovibrio hydrothermalis AM13 under well-controlled conditions. X-ray diffraction and microscopy analyses reveal that iron sulfide minerals produced in the presence of SRM exhibit unique morphology and aggregate differently than abiotic minerals formed in media without cells. Specifically, mackinawite growth is favored in the presence of both live and dead SRM, when compared to the abiotic treatments tested. The cell surface of live and dead SRM, and the extracellular polymers produced by live cells, provide templates for the nucleation of mackinawite and favor mineral growth. The morphology of minerals is however different when live and dead cells are provided. The transformation of greigite from mackinawite occurred after several months of incubation only in the presence of live SRM, suggesting that SRM might accelerate the kinetics of greigite formation under strict anoxic conditions. Pyrite formation was not observed in any experiments. While SRM provide nearly all the sulfide to the Fe-S system at low temperatures, we also posit that SRM play an additional formative role in the size, morphology and potentially the mineralogy of iron sulfide minerals in sedimentary environments, therefore potentially influencing their reactivity. Attempting to reconstruct modern and ancient biogeochemical cycles based on the geochemistry of iron sulfide minerals formed under purely abiotic conditions should be therefore done with caution.

Lunar and Planetary Science XXXV: Weird Martian Minerals: Complex Mars Surface Processes

NASA Technical Reports Server (NTRS)

2004-01-01

The session "Complex Mars Surface" included the following reports:A Reappraisal of Adsorbed Superoxide Ion as the Cause Behind the Reactivity of the Martian Soils; Sub-Surface Deposits of Hydrous Silicates or Hydrated Magnesium Sulfates as Hydrogen Reservoirs near the Martian Equator: Plausible or Not?; Thermal and Evolved Gas Analysis of Smectites: The Search for Water on Mars; Aqueous Alteration Pathways for K, Th, and U on Mars; Temperature Dependence of the Moessbauer Fraction in Mars-Analog Minerals; Acid-Sulfate Vapor Reactions with Basaltic Tephra: An Analog for Martian Surface Processes; Iron Oxide Weathering in Sulfuric Acid: Implications for Mars; P/Fe as an Aquamarker for Mars; Stable Isotope Composition of Carbonates Formed in Low-Temperature Terrestrial Environments as Martian Analogs; Can the Phosphate Sorption and Occlusion Properties Help to Elucidate the Genesis of Specular Hematite on the Mars Surface?; Sulfate Salts, Regolith Interactions, and Water Storage in Equatorial Martian Regolith; Potential Pathways to Maghemite in Mars Soils: The Key Role of Phosphate; and Mineralogy, Abundance, and Hydration State of Sulfates and Chlorides at the Mars Pathfinder Landing Site.

Submarine hydrothermal processes, mirroring the geotectonic evolution of the NE Hungarian Jurassic Szarvaskő Unit

NASA Astrophysics Data System (ADS)

Kiss, Gabriella B.; Zagyva, Tamás; Pásztor, Domokos; Zaccarini, Federica

2018-05-01

The Jurassic pillow basalt of the NE Hungarian Szarvaskő Unit is part of an incomplete ophiolitic sequence, formed in a back-arc- or marginal basin of Neotethyan origin. Different, often superimposing hydrothermal processes were studied aiming to characterise them and to discover their relationship with the geotectonic evolution of the region. Closely packed pillow, pillow-fragmented hyaloclastite breccia and transition to peperitic facies of a submarine lava flow were observed. The rocks underwent primary and cooling-related local submarine hydrothermal processes immediately after eruption at ridge setting. Physico-chemical data of this process and volcanic facies analyses revealed distal formation in the submarine lava flow. A superimposing, more extensive fluid circulation system resulted in intense alteration of basalt and in the formation of mostly sulphide-filled cavities. This lower temperature, but larger-scale process was similar to VMS systems and was related to ridge setting. As a peculiarity of the Szarvaskő Unit, locally basalt may be completely altered to a grossular-bearing mineral assemblage formed by rodingitisation s.l. This unique process observed in basalt happened in ridge setting/during spreading, in the absence of known large ultramafic blocks. Epigenetic veins formed also during Alpine regional metamorphism, related to subduction/obduction. The observed hydrothermal minerals represent different steps of the geotectonic evolution of the Szarvaskő Unit, from the ridge setting and spreading till the subduction/obduction. Hence, studying the superimposing alteration mineral assemblages can be a useful tool for reconstructing the tectonic history of an ophiolitic complex. Though the found mineral parageneses are often similar, careful study can help in distinguishing the processes and characterising their P, T, and X conditions.

Chemical and Sr isotopic characterization of North America uranium ores: Nuclear forensic applications

DOE PAGES

Balboni, Enrica; Jones, Nina; Spano, Tyler; ...

2016-08-31

This study reports major, minor, and trace element data and Sr isotope ratios for 11 uranium ore (uraninite, UO 2+x) samples and one processed uranium ore concentrate (UOC) from various U.S. deposits. The uraninite investigated represent ores formed via different modes of mineralization (e.g., high- and low-temperature) and within various geological contexts, which include magmatic pegmatites, metamorphic rocks, sandstone-hosted, and roll front deposits. In situ trace element data obtained by laser ablation-ICP-MS and bulk sample Sr isotopic ratios for uraninite samples investigated here indicate distinct signatures that are highly dependent on the mode of mineralization and host rock geology. Relativemore » to their high-temperature counterparts, low-temperature uranium ores record high U/Th ratios (>1000), low total rare earth element (REE) abundances (<1 wt%), high contents (>300 ppm) of first row transition metals (Sc, Ti, V, Cr, Mn, Co, Ni), and radiogenic 87Sr/ 86Sr ratios (>0.7200). Comparison of chondrite normalized REE patterns between uraninite and corresponding processed UOC from the same locality indicates identical patterns at different absolute concentrations. Lastly, this result ultimately confirms the importance of establishing geochemical signatures of raw, uranium ore materials for attribution purposes in the forensic analysis of intercepted nuclear materials.« less

Chemical and Sr isotopic characterization of North America uranium ores: Nuclear forensic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balboni, Enrica; Jones, Nina; Spano, Tyler

This study reports major, minor, and trace element data and Sr isotope ratios for 11 uranium ore (uraninite, UO 2+x) samples and one processed uranium ore concentrate (UOC) from various U.S. deposits. The uraninite investigated represent ores formed via different modes of mineralization (e.g., high- and low-temperature) and within various geological contexts, which include magmatic pegmatites, metamorphic rocks, sandstone-hosted, and roll front deposits. In situ trace element data obtained by laser ablation-ICP-MS and bulk sample Sr isotopic ratios for uraninite samples investigated here indicate distinct signatures that are highly dependent on the mode of mineralization and host rock geology. Relativemore » to their high-temperature counterparts, low-temperature uranium ores record high U/Th ratios (>1000), low total rare earth element (REE) abundances (<1 wt%), high contents (>300 ppm) of first row transition metals (Sc, Ti, V, Cr, Mn, Co, Ni), and radiogenic 87Sr/ 86Sr ratios (>0.7200). Comparison of chondrite normalized REE patterns between uraninite and corresponding processed UOC from the same locality indicates identical patterns at different absolute concentrations. Lastly, this result ultimately confirms the importance of establishing geochemical signatures of raw, uranium ore materials for attribution purposes in the forensic analysis of intercepted nuclear materials.« less

Bioactive hydrogel-nanosilica hybrid materials: a potential injectable scaffold for bone tissue engineering.

PubMed

Lewandowska-Łańcucka, Joanna; Fiejdasz, Sylwia; Rodzik, Łucja; Kozieł, Marcin; Nowakowska, Maria

2015-02-10

Novel bioactive organic-inorganic hybrid materials that can serve as injectable hydrogel systems for bone tissue regeneration were obtained. The silica nanoparticles (SiNP) prepared in situ by the Stöber method were dispersed in collagen, collagen-chitosan or chitosan sols, which were then subsequently crosslinked. Laser scanning confocal microscopy studies, in which fluorescent SiNP were applied, and SEM images indicated that the nanosilica particles were distributed in the whole volume of the hydrogel matrix. In vitro studies on fibroblast cell viability indicated that the hybrid materials are biocompatible. The silica nanoparticles dispersed in the biopolymer matrix had a positive effect on cell viability. Studies on the mineralization process under simulated body fluid (SBF) conditions confirmed the bioactivity of prepared materials. SEM images revealed mineral phase formation in the majority of the hybrid materials developed. EDS analysis indicated that these mineral phases are mainly composed of calcium and phosphorus. The XRD studies confirmed that mineral phases formed during SBF incubation of hybrid materials based on collagen are bone-like apatite minerals. The silica nanoparticles added to the hydrogel at the stage of synthesis induced the occurrence of mineralization. This process occurs not only at the surface of the material but in its entire volume, which is important for the preparation of scaffolds for bone tissue engineering. The ability of these materials to undergo in situ gelation under physiological temperature and their bioactivity as well as biocompatibility make them interesting candidates for bioactive injectable systems.

Studies on the Processing Methods for Extraterrestrial Materials

NASA Technical Reports Server (NTRS)

Grimley, R. T.; Lipschutz, M. E.

1984-01-01

The literature was surveyed for high temperature mass spectrometric research on single oxides, complex oxides, and minerals in an effort to develop a means of separating elements and compounds from lunar and other extraterrestrial materials. A data acquisition system for determining vaporization rates as a function of time and temperature and software for the IEEE-488 Apple-ORTEC interface are discussed. Experimental design information from a 1000 C furnace were used with heat transfer calculations to develop the basic design for a 1600 C furnace. A controller was built for the higher temperature furnace and drawings are being made for the furnace.

Oxygen isotope exchange in rocks and minerals from the Cerro Prieto geothermal system: Indicators of temperature distribution and fluid flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, A.E.; Elders, W.A.

1981-01-01

Oxygen isotopic compositions have been measured in drill cuttings and core samples from more than 40 wells ranging in depth to more than 3.5 km in the Cerro Prieto geothermal field. Profiles of isotopic ratios versus sampling depths provide information on the three-dimensional distribution of temperature and fluid flow. These parameters also indicate variations in the history of hydrothermal processes in different areas of the geothermal field.

Immersion freezing of internally and externally mixed mineral dust species analyzed by stochastic and deterministic models

NASA Astrophysics Data System (ADS)

Wong, B.; Kilthau, W.; Knopf, D. A.

2017-12-01

Immersion freezing is recognized as the most important ice crystal formation process in mixed-phase cloud environments. It is well established that mineral dust species can act as efficient ice nucleating particles. Previous research has focused on determination of the ice nucleation propensity of individual mineral dust species. In this study, the focus is placed on how different mineral dust species such as illite, kaolinite and feldspar, initiate freezing of water droplets when present in internal and external mixtures. The frozen fraction data for single and multicomponent mineral dust droplet mixtures are recorded under identical cooling rates. Additionally, the time dependence of freezing is explored. Externally and internally mixed mineral dust droplet samples are exposed to constant temperatures (isothermal freezing experiments) and frozen fraction data is recorded based on time intervals. Analyses of single and multicomponent mineral dust droplet samples include different stochastic and deterministic models such as the derivation of the heterogeneous ice nucleation rate coefficient (J­­het), the single contact angle (α) description, the α-PDF model, active sites representation, and the deterministic model. Parameter sets derived from freezing data of single component mineral dust samples are evaluated for prediction of cooling rate dependent and isothermal freezing of multicomponent externally or internally mixed mineral dust samples. The atmospheric implications of our findings are discussed.

Characterization of Rare Earth Element Minerals in Coal Utilization Byproducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montross, Scott N.; Verba, Circe A.; Collins, Keith

The United States currently produces over 100 million tons of coal utilization byproducts (CUB) per year in the form of fly ash, bottom ash, slag, and flue gas (American Coal Ash Association (ACCA), 2015). But this “waste material” also contains potentially useful levels of rare earth elements (REE). Rare earth elements are crucial for many existing and emerging technologies, but the U.S. lacks a domestic, sustainable REE source. Our project explored the possibility of developing a supply of REEs for U.S. technologies by extracting REEs from CUBs. This work offers the potential to reduce our dependence on other countries formore » supply of these critical elements (NETL, REE 2016 Project Portfolio). Geologic and diagenetic history, industrial preparation methods, and the specific combustion process all play major roles in the composition of CUB. During combustion, inorganic mineral phases of coal particles are fluidized at temperatures higher than 1400oC, so inorganic mineral materials are oxidized, fused, disintegrated, or agglomerated into larger spherical and amorphous (non-crystalline) particles. The original mineralogy of the coal-containing rock and heating/cooling of the material significantly affects the composition and morphology of the particles in the combustion byproduct (Kutchko and Kim, 2006). Thus, different types of coal/refuse/ash must be characterized to better understand mineral evolution during the combustion process. Our research focused on developing a working model to address how REE minerals behave during the combustion process: this research should help determine the most effective engineering methods for extracting REEs from CUBs. We used multimodal imaging and image processing techniques to characterize six rock and ash samples from different coal power plants with respect to morphology, grain size, presence of mineral phases, and elemental composition. The results of these characterization activities provided thresholds for realizing the occurrence of REE mineral phases in CUB and allowed us to calculate structural and volumetric estimates of REE. Collectively, the rock and coal ash samples contained minerals such as quartz, kaolinite, muscovite/illite, iron oxide (as hematite or magnetite), mullite, and clinochlore. Trace minerals included pyrite, zircon, siderite, rutile, diopside, foresterite, gypsum, and barite. We identified REE phosphate minerals monazite (Ce,La,Nd,Th)(PO 4,SiO 4), xenotime (YPO 4,SiO 4), and apatite (Ca 5(PO 4) 3(F,Cl,OH) via SEM and electron microprobe analysis: these materials generally occurred as 1-10 μm-long crystals in the rock and ash samples. As has been shown in other studies, amorphous material-aluminosilicate glass or iron oxyhydroxide-are the major components of coal fly and bottom ash. Trace amounts of amorphous calcium oxide and mixed element (e.g., Al-Si-Ca-Fe) slag are also present. Quartz, mullite, hematite, and magnetite are the crystalline phases present. We found that REEs are present as monomineralic grains dispersed within the ash, as well as fused to or encapsulated by amorphous aluminosilicate glass particles. Monazite and xenotime have relatively high melting points (>1800 °C) compared to typical combustion temperatures; our observations indicate that the REE-phosphates, which presumably contribute a large percentage of REE to the bulk ash REE pool, as measured by mass spectroscopy, are largely unaltered by the combustion. Our study shows that conventional coal combustion processes sequester REE minerals into aluminosilicate glass phases, which presents a new engineering challenge for extracting REE from coal ash. The characterization work summarized in this report provides a semi-quantitative assessments of REE in coal-containing rock and CUB. The data we obtained from 2- and 3-D imaging, elemental mapping, volumetric estimates, and advanced high-resolution pixel classification successfully identified the different mineral phases present in CUB. Further, our characterization results can guide techniques for extracting REEs from CUB, or other geologic and engineered materials. Whilst, interpretations will inform future REE separation and extraction techniques and technologies practical for commercial utilization of combustion byproducts generated by power plants.« less

Hydrated salt minerals on Europa's Surface from the Galileo near-infrared mapping spectrometer (NIMS) investigation

USGS Publications Warehouse

McCord, T.B.; Hansen, G.B.; Matson, D.L.; Johnson, T.V.; Crowley, J.K.; Fanale, F.P.; Carlson, R.W.; Smythe, W.D.; Martin, P.D.; Hibbitts, C.A.; Granahan, J.C.; Ocampo, A.

1999-01-01

We reported evidence of heavily hydrated salt minerals present over large areas of Europa's surface from analysis of reflectance spectra returned by the Galileo mission near infrared mapping spectrometer (NIMS) [McCord et al., 1997a, b, 1998a, b]. Here we elaborate on this earlier evidence, present spatial distributions of these minerals, examine alternate water-ice interpretations, expand on our hydrated-salts interpretation, consider salt mineral stability on Europa, and discuss the implications. Extensive well-defined areas on Europa show distinct, asymmetric water-related absorption bands in the 1 to 2.5-??m region. Radiative transfer modeling of water ice involving different particle sizes and layers at Europa temperatures does not reproduce the distinctive Europa water bands. However, ice near its melting temperature, such as in terrestrial environments, does have some characteristics of the Europa spectrum. Alternatively, some classes of heavily hydrated minerals do exhibit such water bands. Among plausible materials, heavily hydrated salt minerals, such as magnesium and sodium sulfates, sodium carbonate and their mixtures, are preferred. All Europa spectral features are present in some salt minerals and a very good match to the Europa spectrum can be achieved by mixing several salt spectra. However, no single or mix of salt mineral spectra from the limited library available has so far been found to perfectly match the Europa spectrum in every detail. The material is concentrated at the lineaments and in chaotic terrain, which are technically disrupted areas on the trailing side. Since the spectrum of the material on Europa is nearly the same everywhere so-far studied, the salt or salt-mixture composition may be nearly uniform. This suggests similar sources and processes over at least a near-hemispheric scale. This would suggest that an extensive subsurface ocean containing dissolved salts is the source, and several possible mechanisms for deposit emplacement are considered. The hydrogen bonds associated with hydration of these salts are similar or greater in strength and energy to those in pure water ice. Thus, once on the surface, the salt minerals should be as stable to disruption as water ice at the Europa temperatures, and mechanisms are suggested to enhance the stability of both materials. Spectra obtained of MgSO4???6H2O at 77 K show only small differences from room temperature spectra. The main difference is the .appearance of the individual absorptions composing the broad, composite water features and associated with the several different H2O sites in the salt hydrate molecule. This suggests that the Europa absorption bands are also composites. Thus higher spectral resolution may reveal these diagnostic features in Europa's spectrum. The specific salts present and their relative abundances would be indicators of the chemistry and conditions of an ocean environment, and areas of fresh, heavy concentration of these minerals should make ideal lander mission sampling sites. Copyright 1999 by the American Geophysical Union.

Occurrence of the Visible Gold and Sn-Bearing Mineral in Seafloor Hydrothermal Sulfides at Central Indian Ridge, 12.4°S

NASA Astrophysics Data System (ADS)

Choi, S. K.; Pak, S. J.; Kim, J.; Park, J. W.; Son, S. K.

2017-12-01

Sn-rich chimney fragments (up to 1,720 ppm) were recovered with ultramafic rocks from ocean core complex (OCC-4-1) of Central Indian Ridge, 12.4°S. The chimney fragments are featured by barite-free and Zn-rich (up to 50.1 wt.%) ores. The chimney fragments are mainly composed of sphalerite, isocubanite, pyrrhotite, chalcopyrite and marcasite with galena and electrum as minor minerals. The precipitation sequences of the minerals are categorized into three stages by mineral assemblage; early stage with low-temperature minerals, late stage with high-temperature minerals and seawater weathering stage with covellite, Fe-oxyhydroxides and amorphous silica. Early stage is characterized by sphalerite, intermittently showing colloform-texture, closely co-existed with anhedral marcasite and minor galena, whereas late stage is dominated by aggregates of isocubanite with chalcopyrite exsolution lamellae, pyrrhotite partially replaced by long prismatic marcasite and FeS enriched sphalerite (up to 42.69 FeS mole%). Electrums, main phase of gold mineralization, are mostly visible grains (< 3 um in diameter), occuring in sphalerite and isocubanite as inclusions and/or free gold in amorphous silica through the whole mineralization stages. On the basis of semi-quantified analysis, electrum grains are likely to have Au-rich composition. High Sn concentrations are typically observed in altered rim along the grain boundaries between sphalerite and isocubanite, going up to 5.5 wt.% in sphalerite. LA-ICP-MS mapping exhibits that Sn is preferentially incorporated into sphalerite relative to isocubanite, especially showing the highest values in boundaries between both minerals, but significantly lower in marcasite. Stoichiometry of Sn-enriched sphalerite rim seems to have a uniform ratio of atomic proportion of Cu to Sn as almost 2:1, implying that stannite micro-inclusions may result in Sn-enrichment. The LA-ICP-MS spectra also shows abrupt increase in Sn signal intensity, indicating Sn-bearing inclusions are distributed within sphalerite. Therefore, Sn-bearing mineral in sphalerite and isocubanite is likely to be fine particle of stannite in late stage and subsequently one of the possible ways to precipitate these particles could be reworking process of previously deposited Sn-bearing sulfides.

Optimizing deacetylation process for chitosan production from green mussel (perna viridis) shell

NASA Astrophysics Data System (ADS)

Danarto, Y. C.; Distantina, Sperisa

2016-02-01

The green mussel (perna viridis) shell waste could be utilized for chitosan production because it contained chitin. Chitin can be derived into chitosan through the deacetylation process. Chitosan is a polysaccharides polymer that is readily soluble in dilute acid solution and easily modified into other useful compounds. This research aimed to study the chitosan production from green mussel shells. This experiment had the following stages, deproteinization process aimed to eliminate the protein content using 1N NaOH solution, demineralization process aimed to remove minerals in green mussel shells as CaCO3 using 1 N HCl solution and decolorization process aimed to eliminate the color pigments and other impurities using ethanol solvent. All process above resulted chitin. Furthermore, chemical modification of chitin into chitosan by deacetylation process. This stage was very important because it greatly affected the chitosan properties. This research studied two different treatment for deacetylation process. The first treatment was the deacetylation process using concentrated NaOH solution (50% w), at high temperatures (90 - 100 °C) for 2 hours extraction, whilw the second treatment was deacetylation process using a low concentration of NaOH solution (15% w), at room temperature for 24 hours. The results showed that deproteinization, demineralization, and decolorizaton was capable of removing protein, mineral, and pigment. This experiment yield chitin 41.6 %wt. Chitosan yield from second treatment was 39.5%w and it was better than first treatment. Chitosan from first treatment had 79.8% degree of deacetylation and 16.5 kDa molecular weight. It was better than first treatment.

Experiments and Modeling in Support of Generic Salt Repository Science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourret, Suzanne Michelle; Stauffer, Philip H.; Weaver, Douglas James

Salt is an attractive material for the disposition of heat generating nuclear waste (HGNW) because of its self-sealing, viscoplastic, and reconsolidation properties (Hansen and Leigh, 2012). The rate at which salt consolidates and the properties of the consolidated salt depend on the composition of the salt, including its content in accessory minerals and moisture, and the temperature under which consolidation occurs. Physicochemical processes, such as mineral hydration/dehydration salt dissolution and precipitation play a significant role in defining the rate of salt structure changes. Understanding the behavior of these complex processes is paramount when considering safe design for disposal of heat-generatingmore » nuclear waste (HGNW) in salt formations, so experimentation and modeling is underway to characterize these processes. This report presents experiments and simulations in support of the DOE-NE Used Fuel Disposition Campaign (UFDC) for development of drift-scale, in-situ field testing of HGNW in salt formations.« less

Lunar Sulfur Capture System

NASA Technical Reports Server (NTRS)

Berggren, Mark; Zubrin, Robert; Bostwick-White, Emily

2013-01-01

The Lunar Sulfur Capture System (LSCS) protects in situ resource utilization (ISRU) hardware from corrosion, and reduces contaminant levels in water condensed for electrolysis. The LSCS uses a lunar soil sorbent to trap over 98 percent of sulfur gases and about two-thirds of halide gases evolved during hydrogen reduction of lunar soils. LSCS soil sorbent is based on lunar minerals containing iron and calcium compounds that trap sulfur and halide gas contaminants in a fixed-bed reactor held at temperatures between 250 and 400 C, allowing moisture produced during reduction to pass through in vapor phase. Small amounts of Earth-based polishing sorbents consisting of zinc oxide and sodium aluminate are used to reduce contaminant concentrations to one ppm or less. The preferred LSCS configuration employs lunar soil beneficiation to boost concentrations of reactive sorbent minerals. Lunar soils contain sulfur in concentrations of about 0.1 percent, and halogen compounds including chlorine and fluorine in concentrations of about 0.01 percent. These contaminants are released as gases such as H2S, COS, CS2,HCl, and HF during thermal ISRU processing with hydrogen or other reducing gases. Removal of contaminant gases is required during ISRU processing to prevent hardware corrosion, electrolyzer damage, and catalyst poisoning. The use of Earth-supplied, single-use consumables to entirely remove contaminants at the levels existing in lunar soils would make many ISRU processes unattractive due to the large mass of consumables relative to the mass of oxygen produced. The LSCS concept of using a primary sorbent prepared from lunar soil was identified as a method by which the majority of contaminants could be removed from process gas streams, thereby substantially reducing the required mass of Earth-supplied consumables. The LSCS takes advantage of minerals containing iron and calcium compounds that are present in lunar soil to trap sulfur and halide gases in a fixedbed reactor downstream of an in-ISRU process such as hydrogen reduction. The lunar-soil-sorbent trap is held at a temperature significantly lower than the operating temperature of the hydrogen reduction or other ISRU process in order to maximize capture of contaminants, but is held at a high enough temperature to allow moisture to pass through without condensing. The lunar soil benefits from physical beneficiation to remove ultrafine particles (to reduce pressure drop through a fixed bed reactor) and to upgrade concentrations of iron and/or calcium compounds (to improve reactivity with gaseous contaminants).

Climate-change effects on soils: Accelerated weathering, soil carbon and elemental cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qafoku, Nikolla

2015-04-01

Climate change [i.e., high atmospheric carbon dioxide (CO2) concentrations (≥400 ppm); increasing air temperatures (2-4°C or greater); significant and/or abrupt changes in daily, seasonal, and inter-annual temperature; changes in the wet/dry cycles; intensive rainfall and/or heavy storms; extended periods of drought; extreme frost; heat waves and increased fire frequency] is and will significantly affect soil properties and fertility, water resources, food quantity and quality, and environmental quality. Biotic processes that consume atmospheric CO2, and create organic carbon (C) that is either reprocessed to CO2 or stored in soils are the subject of active current investigations, with great concern over themore » influence of climate change. In addition, abiotic C cycling and its influence on the inorganic C pool in soils is a fundamental global process in which acidic atmospheric CO2 participates in the weathering of carbonate and silicate minerals, ultimately delivering bicarbonate and Ca2+ or other cations that precipitate in the form of carbonates in soils or are transported to the rivers, lakes, and oceans. Soil responses to climate change will be complex, and there are many uncertainties and unresolved issues. The objective of the review is to initiate and further stimulate a discussion about some important and challenging aspects of climate-change effects on soils, such as accelerated weathering of soil minerals and resulting C and elemental fluxes in and out of soils, soil/geo-engineering methods used to increase C sequestration in soils, soil organic matter (SOM) protection, transformation and mineralization, and SOM temperature sensitivity. This review reports recent discoveries, identifies key research needs, and highlights opportunities offered by the climate-change effects on soils.« less

Overview of different aspects of climate change effects on soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qafoku, Nikolla P.

2014-08-01

Climate change [i.e., high atmospheric carbon dioxide (CO 2) concentrations (≥400 ppm); increasing air temperatures (2-4°C or greater); significant and/or abrupt changes in daily, seasonal, and inter-annual temperature; changes in the wet/dry cycles; intensive rainfall and/or heavy storms; extended periods of drought; extreme frost; heat waves and increased fire frequency] is and will significantly affect soil properties and fertility, water resources, food quantity and quality, and environmental quality. Biotic processes that consume atmospheric CO 2 and create organic carbon (C) that is either reprocessed to CO 2 or stored in soils, are the subject of active current investigations with greatmore » concern over the influence of climate change. In addition, abiotic C cycling and its influence on the inorganic C pool in soils is a fundamental global process in which acidic atmospheric CO 2 participates in the weathering of carbonate and silicate minerals, ultimately delivering bicarbonate and Ca 2+ or other cations that precipitate in the form of carbonates in soils or are transported to the rivers, lakes, and oceans. Soil responses to climate change will be complex, and there are many uncertainties and unresolved issues. The objective of the review is to initiate and further stimulate a discussion about some important and challenging aspects of climate-change effects on soils, such as accelerated weathering of soil minerals and resulting C and elemental fluxes in and out of soils, soil/geo-engineering methods used to increase C sequestration in soils, soil organic matter (SOM) protection, transformation and mineralization, and SOM temperature sensitivity. This review reports recent discoveries and identifies key research needs required to understand the effects of climate change on soils.« less

Climate Change Mitigation through Enhanced Weathering in Bioenergy Crops

NASA Astrophysics Data System (ADS)

Kantola, I. B.; Masters, M. D.; Wolz, K. J.; DeLucia, E. H.

2016-12-01

Bioenergy crops are a renewable alternative to fossil fuels that reduce the net flux of CO2 to the atmosphere through carbon sequestration in plant tissues and soil. A portion of the remaining atmospheric CO2 is naturally mitigated by the chemical weathering of silica minerals, which sequester carbon as carbonates. The process of mineral weathering can be enhanced by crushing the minerals to increase surface area and applying them to agricultural soils, where warm temperatures, moisture, and plant roots and root exudates accelerate the weathering process. The carbonate byproducts of enhanced weathering are expected accumulate in soil water and reduce soil acidity, reduce nitrogen loss as N2O, and increase availability of certain soil nutrients. To determine the potential of enhanced weathering to alter the greenhouse gas balance in both annual (high disturbance, high fertilizer) and perennial (low disturbance, low fertilizer) bioenergy crops, finely ground basalt was applied to fields of maize, soybeans, and miscanthus at the University of Illinois Energy Farm. All plots showed an immediate soil temperature response at 10 cm depth, with increases of 1- 4 °C at midday. Early season CO2 and N2O fluxes mirrored soil temperature prior to canopy closure in all crops, while total N2O fluxes from miscanthus were lower than corn and soybeans in both basalt treatment and control plots. Mid-season N2O production was reduced in basalt-treated corn compared to controls. Given the increasing footprint of bioenergy crops, the ability to reduce GHG emissions in basalt-treated fields has the potential to mitigate atmospheric warming while benefitting soil fertility with the byproducts of weathering.

Chemical controls on fault behavior: weakening of serpentinite sheared against quartz-bearing rocks and its significance for fault creep in the San Andreas system

USGS Publications Warehouse

Moore, Diane E.; Lockner, David A.

2013-01-01

The serpentinized ultramafic rocks found in many plate-tectonic settings commonly are juxtaposed against crustal rocks along faults, and the chemical contrast between the rock types potentially could influence the mechanical behavior of such faults. To investigate this possibility, we conducted triaxial experiments under hydrothermal conditions (200-350°C), shearing serpentinite gouge between forcing blocks of granite or quartzite. In an ultramafic chemical environment, the coefficient of friction, µ, of lizardite and antigorite serpentinite is 0.5-0.6, and µ increases with increasing temperature over the tested range. However, when either lizardite or antigorite serpentinite is sheared against granite or quartzite, strength is reduced to µ ~ 0.3, with the greatest strength reductions at the highest temperatures (temperature weakening) and slowest shearing rates (velocity strengthening). The weakening is attributed to a solution-transfer process that is promoted by the enhanced solubility of serpentine in pore fluids whose chemistry has been modified by interaction with the quartzose wall rocks. The operation of this process will promote aseismic slip (creep) along serpentinite-bearing crustal faults at otherwise seismogenic depths. During short-term experiments serpentine minerals reprecipitate in low-stress areas, whereas in longer experiments new Mg-rich phyllosilicates crystallize in response to metasomatic exchanges across the serpentinite-crustal rock contact. Long-term shear of serpentinite against crustal rocks will cause the metasomatic mineral assemblages, which may include extremely weak minerals such as saponite or talc, to play an increasingly important role in the mechanical behavior of the fault. Our results may explain the distribution of creep on faults in the San Andreas system.

Chemical dispersion of oil with mineral fines in a low temperature environment.

PubMed

Wang, Weizhi; Zheng, Ying; Lee, Kenneth

2013-07-15

The increasing risks of potential oil spills in the arctic regions, which are characterized by low temperatures, are a big challenge. The traditional dispersant method has shown limited effectiveness in oil cleanup. This work studied the role of mineral fines in the formation of oil-mineral aggregates (OMAs) at low temperature (0-4 °C) environment. The loading amount of minerals and dispersant with different dispersant and oil types were investigated under a full factorial design. The shapes and sizes of OMAs were analyzed. Results showed that the behavior of OMA formation differs when dispersant and mineral fines are used individually or together. Both the experimental and microscopic results also showed the existence of optimal dispersant to oil ratios and mineral to oil ratios. In general, poor oil removal performance was observed for more viscous oil. Corexit 9500 performed better than Corexit 9527 with various oils, in terms of oil dispersion and OMA formation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Oxygen isotope compositions of selected laramide-tertiary granitoid stocks in the Colorado Mineral Belt and their bearing on the origin of climax-type granite-molybdenum systems

USGS Publications Warehouse

Hannah, J.L.; Stein, H.J.

1986-01-01

Quartz phenocrysts from 31 granitoid stocks in the Colorado Mineral Belt yield ??18O values less than 10.4???, with most values between 9.3 and 10.4???. An average magmatic value of about 8.5??? is suggested. The stocks resemble A-type granites; these data support magma genesis by partial melting of previously depleted, fluorine-enriched, lower crustal granulites, followed by extreme differentiation and volatile evolution in the upper crust. Subsolidus interaction of isotopically light water with stocks has reduced most feldspar and whole rock ??18O values. Unaltered samples from Climax-type molybdenumbearing granites, however, show no greater isotopic disturbance than samples from unmineralized stocks. Although meteoric water certainly played a role in post-mineralization alteration, particularly in feldspars, it is not required during high-temperature mineralization processes. We suggest that slightly low ??18O values in some vein and replacement minerals associated with molybdenum mineralization may have resulted from equilibration with isotopically light magmatic water and/or heavy isotope depletion of the ore fluid by precipitation of earlier phases. Accumulation of sufficient quantities of isotopically light magmatic water to produce measured depletions of 18O requires extreme chemical stratification in a large magma reservoir. Upward migration of a highly fractionated, volatile-rich magma into a small apical Climax-type diapir, including large scale transport of silica, alkalis, molybdenum, and other vapor soluble elements, may occur with depression of the solidus temperature and reduction of magma viscosity by fluorine. Climax-type granites may provide examples of 18O depletion in magmatic systems without meteoric water influx. ?? 1986 Springer-Verlag.

Functioning of a Shallow-Water Sediment System during Experimental Warming and Nutrient Enrichment

PubMed Central

Alsterberg, Christian; Sundbäck, Kristina; Hulth, Stefan

2012-01-01

Effects of warming and nutrient enrichment on intact unvegetated shallow-water sediment were investigated for 5 weeks in the autumn under simulated natural field conditions, with a main focus on trophic state and benthic nitrogen cycling. In a flow-through system, sediment was exposed to either seawater at ambient temperature or seawater heated 4°C above ambient, with either natural or nutrient enriched water. Sediment–water fluxes of oxygen and inorganic nutrients, nitrogen mineralization, and denitrification were measured. Warming resulted in an earlier shift to net heterotrophy due to increased community respiration; primary production was not affected by temperature but (slightly) by nutrient enrichment. The heterotrophic state was, however, not further strengthened by warming, but was rather weakened, probably because increased mineralization induced a shortage of labile organic matter. Climate-related warming of seawater during autumn could therefore, in contrast to previous predictions, induce shorter but more intensive heterotrophic periods in shallow-water sediments, followed by longer autotrophic periods. Increased nitrogen mineralization and subsequent effluxes of ammonium during warming suggested a preferential response of organisms driving nitrogen mineralization when compared to sinks of ammonium such as nitrification and algal assimilation. Warming and nutrient enrichment resulted in non-additive effects on nitrogen mineralization and denitrification (synergism), as well as on benthic fluxes of phosphate (antagonism). The mode of interaction appears to be related to the trophic level of the organisms that are the main drivers of the affected processes. Despite the weak response of benthic microalgae to both warming and nutrient enrichment, the assimilation of nitrogen by microalgae was similar in magnitude to rates of nitrogen mineralization. This implies a sustained filter function and retention capacity of nutrients by the sediment. PMID:23240032

Hydrogen and oxygen isotope exchange reactions between clay minerals and water

USGS Publications Warehouse

O'Neil, J.R.; Kharaka, Y.K.

1976-01-01

The extent of hydrogen and oxygen isotope exchange between clay minerals and water has been measured in the temperature range 100-350?? for bomb runs of up to almost 2 years. Hydrogen isotope exchange between water and the clays was demonstrable at 100??. Exchange rates were 3-5 times greater for montmorillonite than for kaolinite or illite and this is attributed to the presence of interlayer water in the montmorillonite structure. Negligible oxygen isotope exchange occurred at these low temperatures. The great disparity in D and O18 exchange rates observed in every experiment demonstrates that hydrogen isotope exchange occurred by a mechanism of proton exchange independent of the slower process of O18 exchange. At 350?? kaolinite reacted to form pyrophyllite and diaspore. This was accompanied by essentially complete D exchange but minor O18 exchange and implies that intact structural units in the pyrophyllite were inherited from the kaolinite precursor. ?? 1976.

Coal Combustion Science quarterly progress report, April--June 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardesty, D.R.; Hurt, R.H.; Baxter, L.L.

1992-09-01

The objective of this work is to support the Office of Fossil Energy in executing research on coal combustion science. This project consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center (PETC) Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency (IEA) Coal Combustion Science Project. Specific tasks include: The characterization of the physical and chemical processes that constitute the early devolatilization phase of coal combustion: Characterization of the combustion behavior of selected coals under conditions relevant to industria pulverized coal-fired furnaces; and to establish a quantitative understanding of themore » mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distributions of mineral species in the unreacted coal, and the local gas temperature and composition.« less

Geochemical and modal data for igneous rocks associated with epithermal mineral deposits

USGS Publications Warehouse

du Bray, Edward A.

2014-01-01

The purposes of this report are to (1) present available geochemical and modal data for igneous rocks associated with epithermal mineral deposits and (2) to make those data widely and readily available for subsequent, more in-depth consideration and interpretation. Epithermal precious and base-metal deposits are commonly associated with subduction-related calc-alkaline to alkaline arc magmatism as well as back-arc continental rift magmatism. These deposits form in association with compositionally diverse extrusive and intrusive igneous rocks. Temperature and depth regimes prevailing during deposit formation are highly variable. The deposits form from hydrothermal fluids that range from acidic to near-neutral pH, and they occur in a variety of structural settings. The disparate temperature, pressure, fluid chemistry, and structural controls have resulted in deposits with wide ranging characteristics. Economic geologists have employed these characteristics to develop classification schemes for epithermal deposits and to constrain the important genetic processes responsible for their formation.

Permafrost and Subsurface Ice in the Solar System

NASA Technical Reports Server (NTRS)

Anderson, D. M.

1985-01-01

The properties and behavior of planetary permafrost are discussed with reference to the ability of such surfaces to sustain loads characteristics of spacecraft landing and planetary bases. In most occurrences, water ice is in close proximity to, or in contact with, finely divided silicate mineral matter. When ice contacts silicate mineral surfaces, a liquid-like, transition zone is created. Its thickness ranges from several hundred Angstron units at temperatures near 0 degrees C to about three Angstrom units at -150 degrees C. When soluble substances are present, the resulting brine enlarges the interfacial zone. When clays are involved, although the interfacial zone may be small, its extent is large. The unfrozen, interfacial water may amount to 100% or more weight at a temperature of -5 degrees C. The presence of this interfacial unfrozen water acts to confer plasticity to permafrost, enabling it to exhibit creep at all imposed levels of stress. Nucleation processes and load-bearing capacity are examined.

Influence of Eco-Friendly Mineral Additives on Early Age Compressive Strength and Temperature Development of High-Performance Concrete

NASA Astrophysics Data System (ADS)

Kaszynska, Maria; Skibicki, Szymon

2017-12-01

High-performance concrete (HPC) which contains increased amount of both higher grade cement and pozzolanic additives generates more hydration heat than the ordinary concrete. Prolonged periods of elevated temperature influence the rate of hydration process in result affecting the development of early-age strength and subsequent mechanical properties. The purpose of the presented research is to determine the relationship between the kinetics of the heat generation process and the compressive strength of early-age high performance concrete. All mixes were based on the Portland Cement CEM I 52.5 with between 7.5% to 15% of the cement mass replaced by the silica fume or metakaolin. Two characteristic for HPC water/binder ratios of w/b = 0.2 and w/b = 0.3 were chosen. A superplasticizer was used to maintain a 20-50 mm slump. Compressive strength was determined at 8h, 24h, 3, 7 and 28 days on 10x10x10 cm specimens that were cured in a calorimeter in a constant temperature of T = 20°C. The temperature inside the concrete was monitored continuously for 7 days. The study determined that the early-age strength (t<24h) of concrete with reactive mineral additives is lower than concrete without them. This is clearly visible for concretes with metakaolin which had the lowest compressive strength in early stages of hardening. The amount of the superplasticizer significantly influenced the early-age compressive strength of concrete. Concretes with additives reached the maximum temperature later than the concretes without them.

Stage-Specific Changes in Physiological and Life-History Responses to Elevated Temperature and Pco2 during the Larval Development of the European Lobster Homarus gammarus (L.).

PubMed

Small, Daniel P; Calosi, Piero; Boothroyd, Dominic; Widdicombe, Steve; Spicer, John I

2015-01-01

An organism's physiological processes form the link between its life-history traits and the prevailing environmental conditions, especially in species with complex life cycles. Understanding how these processes respond to changing environmental conditions, thereby affecting organismal development, is critical if we are to predict the biological implications of current and future global climate change. However, much of our knowledge is derived from adults or single developmental stages. Consequently, we investigated the metabolic rate, organic content, carapace mineralization, growth, and survival across each larval stage of the European lobster Homarus gammarus, reared under current and predicted future ocean warming and acidification scenarios. Larvae exhibited stage-specific changes in the temperature sensitivity of their metabolic rate. Elevated Pco2 increased C∶N ratios and interacted with elevated temperature to affect carapace mineralization. These changes were linked to concomitant changes in survivorship and growth, from which it was concluded that bottlenecks were evident during H. gammarus larval development in stages I and IV, the transition phases between the embryonic and pelagic larval stages and between the larval and megalopa stages, respectively. We therefore suggest that natural changes in optimum temperature during ontogeny will be key to larvae survival in a future warmer ocean. The interactions of these natural changes with elevated temperature and Pco2 significantly alter physiological condition and body size of the last larval stage before the transition from a planktonic to a benthic life style. Thus, living and growing in warm, hypercapnic waters could compromise larval lobster growth, development, and recruitment.

Metamorphism, metasomatism, retrogression: the common control on isotope transport

NASA Astrophysics Data System (ADS)

Villa, I. M.; Williams, M. L.

2011-12-01

Compositional or isotopic modification of a mineral can be viewed as a single process with many names. Depending on the large-scale context, different names are used: aqueous alteration, retrogression, metasomatism, metamorphism, but it should be clear that the underlying atomic-scale mechanism is the same. Changes in stoichiometry and in crystallographic structure require recrystallization. Following [1], all recrystallization processes can be viewed as nano-scale dissolution/reprecipitation, mediated by an aqueous fluid. In fact, aqueous fluids are the main control on the formation of all metamorphic parageneses [2], and also isotope exchange in minerals [3]. The reason is that the rate constants for fluid-mediated isotope transport are orders of magnitude larger, and activation energies much smaller, than those for diffusion. Recrystallisation is energetically less costly at almost any temperature than diffusive reequilibration [3]. However, recrystallization is not the only cause of isotope loss/exchange. Temperature can also play a role in reducing the retentivity of a geochronometer by increasing diffusivity. In cases where diffusion was the factor limiting isotopic closure (or chemical closure), a bell-shaped isotope (or element) concentration profile is observed. The criterion to decide whether in a particular sample diffusion or recrystallization was the principal control on chemical/isotope transport lies in the spatial variation of elemental or isotopic composition. Patchy spatial patterns are certain evidence of fluid-mediated local recrystallization. Bell-shaped gradients are compatible with (but not unambiguous proof of) volume diffusion. In-situ dating over three decades has never described bell-shaped isotope gradients in patchily zoned minerals. On the contrary, age mapping usually coincides with microchemical mapping [4]. This is best explained by a common cause for the recrystallization and the isotope transport. The cause, fluid-mediated dissolution/reprecipitation, depends mainly on water activity and only very loosely on temperature, i.e. provides a geohygrometric but not a geothermometric datum. We conclude that only in rare cases diffusion is the sole promoter of isotope resetting. The observations require a major shift in perspective on the significance of mineral ages. Just as the "diffusionist" view that zircon discordance is due to thermal disturbances (e.g. [5]) was superseded by the petrological understanding that it is due to recrystallization (e.g. [6]), a blanket interpretation of intra-mineral age variations in terms of a purely thermal history neglecting the petrogenetic context is no longer tenable. [1] Putnis A (2009) Rev Mineral Geochem 70, 87-124 [2] Lasaga A (1986) Mineral Mag 50, 359-373 [3] Cole DR et al (1983) Geochim Cosmochim Acta 47, 1681-1693 [4] Williams ML et al (2007) Ann Rev Earth Planet Sci 35, 137-175 [5] Steiger RH, Wasserburg GJ (1969) Geochim Cosmochim Acta 33, 1213-1232 [6] Mezger K, Krogstadt EJ (1997) J Metam Geol 15, 127-140

Some physicochemical aspects of water-soluble mineral flotation.

PubMed

Wu, Zhijian; Wang, Xuming; Liu, Haining; Zhang, Huifang; Miller, Jan D

2016-09-01

Some physicochemical aspects of water-soluble mineral flotation including hydration phenomena, associations and interactions between collectors, air bubbles, and water-soluble mineral particles are presented. Flotation carried out in saturated salt solutions, and a wide range of collector concentrations for effective flotation of different salts are two basic aspects of water-soluble mineral flotation. Hydration of salt ions, mineral particle surfaces, collector molecules or ions, and collector aggregates play an important role in water-soluble mineral flotation. The adsorption of collectors onto bubble surfaces is suggested to be the precondition for the association of mineral particles with bubbles. The association of collectors with water-soluble minerals is a complicated process, which may include the adsorption of collector molecules or ions onto such surfaces, and/or the attachment of collector precipitates or crystals onto the mineral surfaces. The interactions between the collectors and the minerals include electrostatic and hydrophobic interactions, hydrogen bonding, and specific interactions, with electrostatic and hydrophobic interactions being the common mechanisms. For the association of ionic collectors with minerals with an opposite charge, electrostatic and hydrophobic interactions could have a synergistic effect, with the hydrophobic interactions between the hydrophobic groups of the previously associated collectors and the hydrophobic groups of oncoming collectors being an important attractive force. Association between solid particles and air bubbles is the key to froth flotation, which is affected by hydrophobicity of the mineral particle surfaces, surface charges of mineral particles and bubbles, mineral particle size and shape, temperature, bubble size, etc. The use of a collector together with a frother and the use of mixed surfactants as collectors are suggested to improve flotation. Copyright © 2016 Elsevier B.V. All rights reserved.

Solar Thermo-coupled Electrochemical Oxidation of Aniline in Wastewater for the Complete Mineralization Beyond an Anodic Passivation Film.

PubMed

Yuan, Dandan; Tian, Lei; Li, Zhida; Jiang, Hong; Yan, Chao; Dong, Jing; Wu, Hongjun; Wang, Baohui

2018-02-15

Herein, we report the solar thermal electrochemical process (STEP) aniline oxidation in wastewater for totally solving the two key obstacles of the huge energy consumption and passivation film in the electrochemical treatment. The process, fully driven by solar energy without input of any other energies, sustainably serves as an efficient thermoelectrochemical oxidation of aniline by the control of the thermochemical and electrochemical coordination. The thermocoupled electrochemical oxidation of aniline achieved a fast rate and high efficiency for the full minimization of aniline to CO 2 with the stability of the electrode and without formation of polyaniline (PAN) passivation film. A clear mechanism of aniline oxidation indicated a switching of the reactive pathway by the STEP process. Due to the coupling of solar thermochemistry and electrochemistry, the electrochemical current remained stable, significantly improving the oxidation efficiency and mineralization rate by apparently decreasing the electrolytic potential when applied with high temperature. The oxidation rate of aniline and chemical oxygen demand (COD) removal rate could be lifted up to 2.03 and 2.47 times magnification compared to conventional electrolysis, respectively. We demonstrate that solar-driven STEP processes are capable of completely mineralizing aniline with high utilization of solar energy. STEP aniline oxidation can be utilized as a green, sustainable water treatment.

Hydrothermal carbonization of Opuntia ficus-indica cladodes: Role of process parameters on hydrochar properties.

PubMed

Volpe, Maurizio; Goldfarb, Jillian L; Fiori, Luca

2018-01-01

Opuntia ficus-indica cladodes are a potential source of solid biofuel from marginal, dry land. Experiments assessed the effects of temperature (180-250°C), reaction time (0.5-3h) and biomass to water ratio (B/W; 0.07-0.30) on chars produced via hydrothermal carbonization. Multivariate linear regression demonstrated that the three process parameters are critically important to hydrochar solid yield, while B/W drives energy yield. Heating value increased together with temperature and reaction time and was maximized at intermediate B/W (0.14-0.20). Microscopy shows evidence of secondary char formed at higher temperatures and B/W ratios. X-ray diffraction, thermogravimetric data, microscopy and inductively coupled plasma mass spectrometry suggest that calcium oxalate in the raw biomass remains in the hydrochar; at higher temperatures, the mineral decomposes into CO 2 and may catalyze char/tar decomposition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogeochemical processes governing the origin, transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters

USGS Publications Warehouse

Nordstrom, D. Kirk

2011-01-01

Mobility of potential or actual contaminants from mining and mineral processing activities depends on (1) occurrence: is the mineral source of the contaminant actually present? (2) abundance: is the mineral present in sufficient quantity to make a difference? (3) reactivity: what are the energetics, rates, and mechanisms of sorption and mineral dissolution and precipitation relative to the flow rate of the water? and (4) hydrology: what are the main flow paths for contaminated water? Estimates of relative proportions of minerals dissolved and precipitated can be made with mass-balance calculations if minerals and water compositions along a flow path are known. Combined with discharge, these mass-balance estimates quantify the actual weathering rate of pyrite mineralization in the environment and compare reasonably well with laboratory rates of pyrite oxidation except when large quantities of soluble salts and evaporated mine waters have accumulated underground. Quantitative mineralogy with trace-element compositions can substantially improve the identification of source minerals for specific trace elements through mass balances. Post-dissolution sorption and precipitation (attenuation) reactions depend on the chemical behavior of each element, solution composition and pH, aqueous speciation, temperature, and contact-time with mineral surfaces. For example, little metal attenuation occurs in waters of low pH (2, and redox-sensitive oxyanions (As, Sb, Se, Mo, Cr, V). Once dissolved, metal and metalloid concentrations are strongly affected by redox conditions and pH. Iron is the most reactive because it is rapidly oxidized by bacteria and archaea and Fe(III) hydrolyzes and precipitates at low pH (1–3) which is related directly to its first hydrolysis constant, pK1 = 2.2. Several insoluble sulfate minerals precipitate at low pH including anglesite, barite, jarosite, alunite and basaluminite. Aluminum hydrolyzes near pH 5 (pK1 = 5.0) and provides buffering and removal of Al by mineral precipitation from pH 4–5.5. Dissolved sulfate behaves conservatively because the amount removed from solution by precipitation is usually too small relative to the high concentrations in the water column and relative to the flow rate of the water.

Discharge, water temperature, and water quality of Warm Mineral Springs, Sarasota County, Florida: A retrospective analysis

USGS Publications Warehouse

Metz, Patricia A.

2016-09-27

Warm Mineral Springs, located in southern Sarasota County, Florida, is a warm, highly mineralized, inland spring. Since 1946, a bathing spa has been in operation at the spring, attracting vacationers and health enthusiasts. During the winter months, the warm water attracts manatees to the adjoining spring run and provides vital habitat for these mammals. Well-preserved late Pleistocene to early Holocene-age human and animal bones, artifacts, and plant remains have been found in and around the spring, and indicate the surrounding sinkhole formed more than 12,000 years ago. The spring is a multiuse resource of hydrologic importance, ecological and archeological significance, and economic value to the community.The pool of Warm Mineral Springs has a circular shape that reflects its origin as a sinkhole. The pool measures about 240 feet in diameter at the surface and has a maximum depth of about 205 feet. The sinkhole developed in the sand, clay, and dolostone of the Arcadia Formation of the Miocene-age to Oligocene-age Hawthorn Group. Underlying the Hawthorn Group are Oligocene-age to Eocene-age limestones and dolostones, including the Suwannee Limestone, Ocala Limestone, and Avon Park Formation. Mineralized groundwater, under artesian pressure in the underlying aquifers, fills the remnant sink, and the overflow discharges into Warm Mineral Springs Creek, to Salt Creek, and subsequently into the Myakka River. Aquifers described in the vicinity of Warm Mineral Springs include the surficial aquifer system, the intermediate aquifer system within the Hawthorn Group, and the Upper Floridan aquifer in the Suwannee Limestone, Ocala Limestone, and Avon Park Formation. The Hawthorn Group acts as an upper confining unit of the Upper Floridan aquifer.Groundwater flow paths are inferred from the configuration of the potentiometric surface of the Upper Floridan aquifer for September 2010. Groundwater flow models indicate the downward flow of water into the Upper Floridan aquifer in inland areas, and upward flow toward the surface in coastal areas, such as at Warm Mineral Springs. Warm Mineral Springs is located in a discharge area. Changes in water use in the region have affected the potentiometric surface of the Upper Floridan aquifer. Historical increase in groundwater withdrawals resulted in a 10- to 20-foot regional decline in the potentiometric surface of the Upper Floridan aquifer by May 1975 relative to predevelopment levels and remained at approximately that level in May 2007 in the area of Warm Mineral Springs. Discharge measurements at Warm Mineral Springs (1942–2014) decreased from about 11–12 cubic feet per second in the 1940s to about 6–9 cubic feet per second in the 1970s and remained at about that level for the remainder of the period of record. Similarity of changes in regional water use and discharge at Warm Mineral Springs indicates that basin-scale changes to the groundwater system have affected discharge at Warm Mineral Springs. Water temperature had no significant trend in temperature over the period of record, 1943–2015, and outliers were identified in the data that might indicate inconsistencies in measurement methods or locations.Within the regional groundwater basin, Warm Mineral Springs is influenced by deep Upper Floridan aquifer flow paths that discharge toward the coast. Associated with these flow paths, the groundwater temperatures increase with depth and toward the coast. Multiple lines of evidence indicate that a source of warm groundwater to Warm Mineral Springs is likely the permeable zone of the Avon Park Formation within the Upper Floridan aquifer at a depth of about 1,400 to 1,600 feet, or deeper sources. The permeable zone contains saline groundwater with water temperatures of at least 95 degrees Fahrenheit.The water quality of Warm Mineral Springs, when compared with other springs in Florida had the highest temperature and the greatest mineralized content. Warm Mineral Springs water is characterized by a slight-green color, with varying water clarity, low dissolved oxygen (indicative of deep groundwater), and a hydrogen sulfide odor. Water-quality samples detected ammonium-nitrogen and nitrates, but at low concentrations. The drinking water standard for nitrate adopted by the U.S. Environmental Protection Agency is 10 milligrams per liter, measured as nitrogen. Water samples collected at spring vents by divers on April 29, 2015, had concentrations of 0.9 milligram per liter nitrate-nitrogen at vent A and 0.04–0.05 milligram per liter at vents B, C, and D. Typically, the water clarity is highest in the morning (about 30 feet Secchi depth) and often decreases throughout the day.Analysis of existing data provided some insight into the hydrologic processes affecting Warm Mineral Springs; however, data have been sparsely and discontinuously collected since the 1940s. Continuous monitoring of hydrologic characteristics such as discharge, water temperature, specific conductance, and water-quality indicators, such as nitrate and turbidity (water clarity), would be valuable for monitoring and development of models of spring discharge and water quality. In addition, water samples could be analyzed for isotopic tracers, such as strontium, and the results used to identify and quantify the sources of groundwater that discharge at Warm Mineral Springs. Groundwater flow/transport models could be used to evaluate the sensitivity of the quality and quantity of water flowing from Warm Mineral Springs to changes in climate, aquifer levels, and water use.

Studies of Young Hawai'ian Lava Tubes: Implications for Planetary Habitability and Human Exploration

NASA Technical Reports Server (NTRS)

McAdam, Amy; Bleacher, Jacob; Young, Kelsey; Johnson, Sarah Stewart; Needham, Debra; Schmerr, Nicholas; Shiro, Brian; Garry, Brent; Whelley, Patrick; Knudson, Christine;

Correlation between magnetic susceptibility and mineral species along NWA-1 well, southern Tunisia: An overlap of the depositional environment, the climate, and the diagenesis

NASA Astrophysics Data System (ADS)

Mefteh, Samir; Essefi, Elhoucine; Yaich, Chokri; Jamoussi, Fakher; Medhioub, Mounir

2015-03-01

In order to distinguish the effects of diagenesis, the climate and the depositional environment, the magnetic properties were correlated with some minerals along the NWA-1 well, which crosses the southern subsurface from Cretaceous to Silurian successions. The MS along NWA-1 well shows major picks probably indicating a dramatic change of geochemical and mineralogical composition. Minor picks may be attributed to diagenetic transformations affecting some minerals. The mineralogical analysis shows the presence of illite, kaolinite with some traces of chlorite and smectite. Quartz, calcite, white feldspar, anorthite, dolomite, gypsum and pyrite are identified as associated minerals. The PCA of the different minerals and the magnetic susceptibility shows three different heterogeneous populations. In these populations, the traditional classification of magnetic minerals is not respected. For instance, diamagnetic minerals are positively correlated with MS. This correlation is through indirect causal relation extrapolating the temperature caused by the burial diagenesis. The aim is not totally reached because the handicap is twofold. The XRD diffraction is not able to identify the low amounts of magnetic minerals and the primary mineralogy and magnetic properties are radically modified by post-depositional processes. At the productive well of NWA-1, this overlap is further complicated by hydrocarbons, low grade metamorphism and remagnetization modifying the original magnetic signal.

Understanding processes affecting mineral deposits in humid environments

USGS Publications Warehouse

Seal, Robert R.; Ayuso, Robert A.

2011-01-01

Recent interdisciplinary studies by the U.S. Geological Survey have resulted in substantial progress toward understanding the influence that climate and hydrology have on the geochemical signatures of mineral deposits and the resulting mine wastes in the eastern United States. Specific areas of focus include the release, transport, and fate of acid, metals, and associated elements from inactive mines in temperate coastal areas and of metals from unmined mineral deposits in tropical to subtropical areas; the influence of climate, geology, and hydrology on remediation options for abandoned mines; and the application of radiogenic isotopes to uniquely apportion source contributions that distinguish natural from mining sources and extent of metal transport. The environmental effects of abandoned mines and unmined mineral deposits result from a complex interaction of a variety of chemical and physical factors. These include the geology of the mineral deposit, the hydrologic setting of the mineral deposit and associated mine wastes, the chemistry of waters interacting with the deposit and associated waste material, the engineering of a mine as it relates to the reactivity of mine wastes, and climate, which affects such factors as temperature and the amounts of precipitation and evapotranspiration; these factors, in turn, influence the environmental behavior of mineral deposits. The role of climate is becoming increasingly important in environmental investigations of mineral deposits because of the growing concerns about climate change.

Origin and diagenesis of clay minerals in relation to sandstone paragenesis: An example in eolian dune reservoirs and associated rocks, Permian upper part of the Minnelusa Formation, Powder River basin, Wyoming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pollastro, R.M.; Schenk, C.J.

Eolian dune sandstones are the principal reservoir rocks in the Permian upper part of the Minnelusa Formation, Powder River basin, Wyoming. These sandstones formed as shorelines retreated and dunes migrated across siliciclastic sabkhas. Sandstones are mainly quartzarenites; on average, clay minerals constitute about 5 wt.% the whole rock. Although present in minor amounts, clay minerals play an important role in the diagenetic evolution of these sandstones. Allogenic clay minerals are present in shaly rock fragments and laminae. Early infiltration of clays into porous sabkha sands commonly form characteristic menisei or bridges between framework grains or, when more extensive, form coatingsmore » or rims on grain surfaces. Authigenic clays include nearly pure smectite, mixed-layer illite/smectite (I/S), and late diagenetic illite and corrensite; these clay minerals are present as pore-lining cements. In addition to the deposition and neoformation of clay minerals throughout sandstone paragenesis, the conversion of smectite to illite occurred as temperatures increased with progressive burial. A temperature of 103C is calculated at a present depth of 3,200 m using a geothermal gradient of 30C/km and a mean annual surface temperature of 7C. After correction for uplift and erosion (250 m), the maximum calculated temperature for the conversion of all random I/S to ordered I/S is 100C. This calculated temperature is in excellent agreement with temperatures of 100-110C implied from I/S geothermometry.« less

Kinetics of scheelite dissolution in groundwater: defining the release rate of tungsten contamination from a natural source

NASA Astrophysics Data System (ADS)

Montgomery, S. D.; Mckibben, M. A.

2011-12-01

Tungsten, an emerging contaminant, has no EPA standard for its permissible levels in drinking water. At sites in California, Nevada, and Arizona there may be a correlation between elevated levels of tungsten in drinking water and clusters of childhood acute lymphocytic leukemia (ALL). Developing a better understanding of how tungsten is released from rocks into surface and groundwaters is therefore of growing environmental interest. Knowledge of tungstate ore mineral weathering processes, particularly the rates of dissolution of scheelite (CaWO4) in groundwater, could improve models of how tungsten is released and transported in natural waters. Our research is focusing on experimental determination of the rates and products of tungstate mineral dissolution in synthetic groundwater, as a function of temperature, pH and mineral surface area. The initial rate method is being used to develop rate laws. Batch reactor experiments are conducted within constant temperature circulation baths over a pH range of 2-9. Cleaned scheelite powder with grain diameters of 106-150um is placed between two screens in a sample platform and then placed inside a two liter Teflon vessel filled with synthetic groundwater. Ports on the vessel allow sample extraction, temperature and pH measurement, gas inflow, and water circulation. Aliquots of solution are taken periodically for product analysis by ICP -MS. Changes in mineral surface characteristics are monitored using SEM and EDS methods. Results so far reveal that the dissolution of scheelite is incongruent at both neutral and low pH. Solid tungstic acid forms on scheelite mineral surfaces under acidic conditions, implying that this phase controls the dissolution rate in acidic environments. The influence of dissolved CO2 and resultant calcium carbonate precipitation on the dissolution of scheelite at higher pH is also being investigated. The rate law being developed for scheelite dissolution will be useful in reactive-transport computer codes designed to model tungsten contamination in a variety of surface and groundwater settings.

Correlation between thermal behavior of clays and their chemical and mineralogical composition: a review

NASA Astrophysics Data System (ADS)

Dwi Yanti, Evi; Pratiwi, I.

2018-02-01

Clay's abundance has been widely used as industrial raw materials, especially ceramic and tile industries. Utilization of these minerals needs a thermal process for producing ceramic products. Two studies conducted by Septawander et al. and Chin C et al., showed the relationship between thermal behavior of clays and their chemical and mineralogical composition. Clays are characterized by XRD analysis and thermal analysis, ranging from 1100°C to 1200°C room temperature. Specimen of raw materials of clay which is used for the thermal treatment is taken from different geological conditions and formation. In raw material, Quartz is almost present in all samples. Halloysite, montmorillonite, and feldspar are present in Tanjung Morawa raw clay. KC and MC similar kaolinite and illite are present in the samples. The research illustrates the interrelationships of clay minerals and chemical composition with their heat behavior. As the temperature of combustion increases, the sample reduces a significant weight. The minerals which have undergone a transformation phase became mullite, cristobalite or illite and quartz. Under SEM analysis, the microstructures of the samples showed irregularity in shape; changes occurred due the increase of heat.

Modeling hot spring chemistries with applications to martian silica formation

NASA Astrophysics Data System (ADS)

Marion, G. M.; Catling, D. C.; Crowley, J. K.; Kargel, J. S.

2011-04-01

Many recent studies have implicated hydrothermal systems as the origin of martian minerals across a wide range of martian sites. Particular support for hydrothermal systems include silica (SiO 2) deposits, in some cases >90% silica, in the Gusev Crater region, especially in the Columbia Hills and at Home Plate. We have developed a model called CHEMCHAU that can be used up to 100 °C to simulate hot springs associated with hydrothermal systems. The model was partially derived from FREZCHEM, which is a colder temperature model parameterized for broad ranges of temperature (<-70 to 25 °C), pressure (1-1000 bars), and chemical composition. We demonstrate the validity of Pitzer parameters, volumetric parameters, and equilibrium constants in the CHEMCHAU model for the Na-K-Mg-Ca-H-Cl-ClO 4-SO 4-OH-HCO 3-CO 3-CO 2-O 2-CH 4-Si-H 2O system up to 100 °C and apply the model to hot springs and silica deposits. A theoretical simulation of silica and calcite equilibrium shows how calcite is least soluble with high pH and high temperatures, while silica behaves oppositely. Such influences imply that differences in temperature and pH on Mars could lead to very distinct mineral assemblages. Using measured solution chemistries of Yellowstone hot springs and Icelandic hot springs, we simulate salts formed during the evaporation of two low pH cases (high and low temperatures) and a high temperature, alkaline (high pH) sodic water. Simulation of an acid-sulfate case leads to precipitation of Fe and Al minerals along with silica. Consistency with martian mineral assemblages suggests that hot, acidic sulfate solutions are plausibility progenitors of minerals in the past on Mars. In the alkaline pH (8.45) simulation, formation of silica at high temperatures (355 K) led to precipitation of anhydrous minerals (CaSO 4, Na 2SO 4) that was also the case for the high temperature (353 K) low pH case where anhydrous minerals (NaCl, CaSO 4) also precipitated. Thus we predict that secondary minerals associated with massive silica deposits are plausible indicators on Mars of precipitation environments and aqueous chemistry. Theoretical model calculations are in reasonable agreement with independent experimental silica concentrations, which strengthens the validity of the new CHEMCHAU model.

Modeling hot spring chemistries with applications to martian silica formation

USGS Publications Warehouse

Marion, G.M.; Catling, D.C.; Crowley, J.K.; Kargel, J.S.

2011-01-01

Many recent studies have implicated hydrothermal systems as the origin of martian minerals across a wide range of martian sites. Particular support for hydrothermal systems include silica (SiO2) deposits, in some cases >90% silica, in the Gusev Crater region, especially in the Columbia Hills and at Home Plate. We have developed a model called CHEMCHAU that can be used up to 100??C to simulate hot springs associated with hydrothermal systems. The model was partially derived from FREZCHEM, which is a colder temperature model parameterized for broad ranges of temperature (<-70 to 25??C), pressure (1-1000 bars), and chemical composition. We demonstrate the validity of Pitzer parameters, volumetric parameters, and equilibrium constants in the CHEMCHAU model for the Na-K-Mg-Ca-H-Cl-ClO4-SO4-OH-HCO3-CO3-CO2-O2-CH4-Si-H2O system up to 100??C and apply the model to hot springs and silica deposits.A theoretical simulation of silica and calcite equilibrium shows how calcite is least soluble with high pH and high temperatures, while silica behaves oppositely. Such influences imply that differences in temperature and pH on Mars could lead to very distinct mineral assemblages. Using measured solution chemistries of Yellowstone hot springs and Icelandic hot springs, we simulate salts formed during the evaporation of two low pH cases (high and low temperatures) and a high temperature, alkaline (high pH) sodic water. Simulation of an acid-sulfate case leads to precipitation of Fe and Al minerals along with silica. Consistency with martian mineral assemblages suggests that hot, acidic sulfate solutions are plausibility progenitors of minerals in the past on Mars. In the alkaline pH (8.45) simulation, formation of silica at high temperatures (355K) led to precipitation of anhydrous minerals (CaSO4, Na2SO4) that was also the case for the high temperature (353K) low pH case where anhydrous minerals (NaCl, CaSO4) also precipitated. Thus we predict that secondary minerals associated with massive silica deposits are plausible indicators on Mars of precipitation environments and aqueous chemistry. Theoretical model calculations are in reasonable agreement with independent experimental silica concentrations, which strengthens the validity of the new CHEMCHAU model. ?? 2011 Elsevier Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byong-chul Kim; Sushil Gupta; David French

Iron minerals in coke can catalyze its gasification and may affect coke behavior in the blast furnace. The catalytic behavior of iron depends largely upon the nature of the iron-bearing minerals. To determine the mineralogical changes that iron could undergo in the blast furnace, cokes made from three coals containing iron present in different mineral forms (clays, carbonates, and pyrite) were examined. All coke samples were heat-treated in a horizontal furnace at 1373, 1573, and 1773 K and then gasified with CO{sub 2} at 1173 K in a fixed bed reactor (FBR). Coke mineralogy was characterized using quantitative X-ray diffractionmore » (XRD) analysis of coke mineral matter prepared by low-temperature ashing (LTA) and field emission scanning electron microscopy combined with energy dispersive X-ray analysis (FESEM/EDS). The mineralogy of the three cokes was most notably distinguished by differing proportions of iron-bearing phases. During heat treatment and subsequent gasification, iron-containing minerals transformed to a range of minerals but predominantly iron-silicides and iron oxides, the relative amounts of which varied with heat treatment temperature and gasification conditions. The relationship between initial apparent reaction rate and the amount of catalytic iron minerals - pyrrhotite, metallic iron, and iron oxides - was linear and independent of heat treatment temperature at total catalyst levels below 1 wt %. The study showed that the coke reactivity decreased with increasing temperature of heat treatment due to decreased levels of catalytic iron minerals (largely due to formation of iron silicides) as well as increased ordering of the carbon structure. The study also showed that the importance of catalytic mineral matter in determining reactivity declines as gasification proceeds. 37 refs., 13 figs., 7 tabs.« less

The role of minerals and mean annual temperature on soil carbon accumulation: A modeling analysis

NASA Astrophysics Data System (ADS)

Abramoff, R. Z.; Georgiou, K.; Tang, J.; Torn, M. S.; Riley, W. J.

2016-12-01

Soil organic carbon (SOC) is the largest actively cycling terrestrial C pool with mean residence times that can exceed 10,000 years. There is strong evidence suggesting that SOC dynamics depend on soil temperature and C inputs to soil through net primary production (NPP), but it is unclear what the relative importance of these factors is relative to SOC protection by minerals. Recent empirical studies have suggested that mineral protection explains more variation in SOC stock sizes and C respiration fluxes than does NPP or climate. Our previous modeling has demonstrated that representing the chemistry of mineral sorption in a microbially-explicit model affects the temperature sensitivity of SOC dynamics. We apply this modeling framework to interpret observations of SOC stocks, mineral surface availability, mean annual temperature (MAT), and NPP collected along a 4,000 km transect in South America. We use a Random Forest machine learning algorithm and regression to analyze our model output and the empirical data. This analysis shows that mineral surface availability is the dominant control over C respiration and SOC stock, and is substantially larger than the effects of belowground NPP. We further show that minerals interact with MAT to determine the observed range of SOC stocks along this transect in the present day, as well as projected SOC stocks under long-term warming. Our model-data comparison suggests that soil mineralogy and MAT will explain the majority of the spatial variation in SOC stock over decadal-to-millennial timescales. We extend the analysis of these interactions using the ACME Land Model (ALM) coupled with an explicit representation of microbes, minerals, and vertical transport of solutes and gases. The model results confirm the dominant effects of minerals on organic matter decomposition throughout the soil column.

Gold in Accessory Zircon (the Kozhim Massif, Subpolar Urals)

NASA Astrophysics Data System (ADS)

Denisova, Yuliya; Pystin, Aleksandr

2017-12-01

The crystals of zircon due to their resistance to external impact of various processes can reveal information about the environment of their formation and the inclusions observed of them. Zircon contains different mineral inclusions: biotite, plagioclase, quartz, apatite, etc. However, there is no information about gold inclusions in the zircons from granites of the Sudpolar Urals. The study results of the inclusions of gold in accessory zircon of the Kozhim granitic massif are presented in this paper. The studied mineral is a dark-brown translucent short-prismatic crystal containing the inclusion of gold and the allocations of quartz. According to studies, the inclusion of gold formed during the growth of zircon and it is the gold covered with a thin film of oxide gold. It was confirmed that the crystallization of the studied zircon occurred at a temperature of 800°C and above on the stage of formation of granites of Kozhim massif. The assumption is made about the additional temperature in the course of which was caused by decreasing of temperature up to 700° C and below during postmagmatic stage.

iGeoT v1.0: Automatic Parameter Estimation for Multicomponent Geothermometry, User's Guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spycher, Nicolas; Finsterle, Stefan

GeoT implements the multicomponent geothermometry method developed by Reed and Spycher [1984] into a stand-alone computer program to ease the application of this method and to improve the prediction of geothermal reservoir temperatures using full and integrated chemical analyses of geothermal fluids. Reservoir temperatures are estimated from statistical analyses of mineral saturation indices computed as a function of temperature. The reconstruction of the deep geothermal fluid compositions, and geothermometry computations, are all implemented into the same computer program, allowing unknown or poorly constrained input parameters to be estimated by numerical optimization. This integrated geothermometry approach presents advantages over classical geothermometersmore » for fluids that have not fully equilibrated with reservoir minerals and/or that have been subject to processes such as dilution and gas loss. This manual contains installation instructions for iGeoT, and briefly describes the input formats needed to run iGeoT in Automatic or Expert Mode. An example is also provided to demonstrate the use of iGeoT.« less

High temperature gas-solid reactions in calc-silicate Cu-Au skarn formation; Ertsberg, Papua Province, Indonesia

NASA Astrophysics Data System (ADS)

Henley, Richard W.; Brink, Frank J.; King, Penelope L.; Leys, Clyde; Ganguly, Jibamitra; Mernagh, Terrance; Middleton, Jill; Renggli, Christian J.; Sieber, Melanie; Troitzsch, Ulrike; Turner, Michael

2017-12-01

The 2.7-3 Ma Ertsberg East Skarn System (Indonesia), adjacent to the giant Grasberg Porphyry Copper deposit, is part of the world's largest system of Cu -Au skarn deposits. Published fluid inclusion and stable isotope data show that it formed through the flux of magma-derived fluid through contact metamorphosed carbonate rock sequences at temperatures well above 600° C and pressures of less than 50 MPa. Under these conditions, the fluid has very low density and the properties of a gas. Combining a range of micro-analytical techniques, high-resolution QEMSCAN mineral mapping and computer-assisted X-ray micro-tomography, an array of coupled gas-solid reactions may be identified that controlled reactive mass transfer through the 1 km3 hydrothermal skarn system. Vacancy-driven mineral chemisorption reactions are identified as a new type of reactive transport process for high-temperature skarn alteration. These gas-solid reactions are maintained by the interaction of unsatisfied bonds on mineral surfaces and dipolar gas-phase reactants such as SO2 and HCl that are continuously supplied through open fractures and intergranular diffusion. Principal reactions are (a) incongruent dissolution of almandine-grossular to andradite and anorthite (an alteration mineral not previously recognized at Ertsberg), and (b) sulfation of anorthite to anhydrite. These sulfation reactions also generate reduced sulfur with consequent co-deposition of metal sulfides. Diopside undergoes similar reactions with deposition of Fe-enriched pyroxene in crypto-veins and vein selvedges. The loss of calcium from contact metamorphic garnet to form vein anhydrite necessarily results in Fe-enrichment of wallrock, and does not require Fe-addition from a vein fluid as is commonly assumed.

Age of metamorphic events : petrochronology and hygrochronology

NASA Astrophysics Data System (ADS)

Bosse, Valerie; Villa, Igor M.

2017-04-01

Geodynamic models of the lithosphere require quantitative data from natural samples. Time is a key parameter: it allows to calculate rates and duration of geological processes and provides informations about the involved physical processes (Vance et al. 2003). Large-scale orogenic models require linking geochronological data with other parameters: structures, kinematics, magmatic and metamorphic petrology (P-T-A-X conditions), thermobarometric evolution of the lithosphere, chemical dynamics (Muller, 2003). This requires geochronometers that are both powerful chemical and petrological tracers. In-situ techniques allow dating a mineral in its petrological-microstructural environment. Getting a "date" has become quite easy... But what do we date in the end ? What is the link between the numbers obtained from the mass spectrometer and the age of the metamorphic event we are trying to date ? How can we transform the date into a geological meaningful age ? What do we learn about the behavior of the geochronometer minerals? Now that we can perform precise dating on very small samples directly in the studied rock, it is important to improve the way we interpret the ages to give them more pertinence in the geodynamic context. We propose to discuss the Th/U/Pb system isotopic closure in various metamorphic contexts using our published examples of in situ dating on monazite and zircon (Bosse et al. 2009; Didier et al. 2014, 2015). The studied examples show that (i) fluid assisted dissolution-precipitation processes rather than temperature-dependent solid diffusion predominantly govern the closure of the Th/U/Pb system (ii) monazite and zircon are sensitive to the interaction with fluids of specific composition (F, CO2, K ...), even at low temperature (iii) in the absence of fluids, monazite is able to record HT events and to retain this information in poly-orogenic contexts or during partial melting events (iv) complex chemical and isotopic zonations, well known in monazite, reflect the interaction with the surrounding mineral assemblages. An often neglected observation is that the K-Ar chronometer minerals show similar patterns of isotopic inheritance closely tied to relict patches and heterochemical retrogression phases (Villa and Williams 2013). Isotopic closure in the U-Pb and K-Ar systems follows the same principle: thermal diffusion is very slow, dissolution and reprecipitation are several orders of magnitude faster. This means that both U-Pb and K-Ar mineral chronometers are hygrochronometers. The interpretation of the ages of the different domains cannot be decoupled from the geochemical and petrological context. The focus on petrology also requires, following Villa (1998, 2016), that the ages measured in metamorphic rocks no longer can be used in geodynamic models according to the "closure temperature" concept as originally defined by Dodson (1973). Bosse et al. (2009) Chem Geol 261: 286 Didier et al. (2014) Chem Geol 381: 206 Didier et al. (2015) Contrib Mineral Petrol 170: 45 Dodson (1973) Contrib Mineral Petrol 40: 259 Muller (2003) EPSL, 206: 237 Villa (1998) Terra Nova 10: 42 Villa (2016) Chem Geol 420: 1 Villa & Williams (2013) In: Harlov & Austrheim (eds.), Metasomatism and the Chemical Transformation of Rock. Springer, p171

Preparation and thermal properties of mineral-supported polyethylene glycol as form-stable composite phase change materials (CPCMs) used in asphalt pavements.

PubMed

Jin, Jiao; Lin, Feipeng; Liu, Ruohua; Xiao, Ting; Zheng, Jianlong; Qian, Guoping; Liu, Hongfu; Wen, Pihua

2017-12-05

Three kinds of mineral-supported polyethylene glycol (PEG) as form-stable composite phase change materials (CPCMs) were prepared to choose the most suitable CPCMs in asphalt pavements for the problems of asphalt pavements rutting diseases and urban heat islands. The microstructure and chemical structure of CPCMs were characterized by SEM, FT-IR and XRD. Thermal properties of the CPCMs were determined by TG and DSC. The maximum PEG absorption of diatomite (DI), expanded perlite (EP) and expanded vermiculite (EVM) could reach 72%, 67% and 73.6%, respectively. The melting temperatures and latent heat of CPCMs are in the range of 52-55 °C and 100-115 J/g, respectively. The results show that PEG/EP has the best thermal and chemical stability after 100 times of heating-cooling process. Moreover, crystallization fraction results show that PEG/EP has slightly higher latent heats than that of PEG/DI and PEG/EVM. Temperature-adjusting asphalt mixture was prepared by substituting the fine aggregates with PEG/EP CPCMs. The upper surface maximum temperature difference of temperature-adjusting asphalt mixture reaches about 7.0 °C in laboratory, and the surface peak temperature reduces up to 4.3 °C in the field experiment during a typical summer day, indicating a great potential application for regulating pavement temperature field and alleviating the urban heat islands.

Significance of elevated K/Rb ratios in lower crustal rocks

NASA Technical Reports Server (NTRS)

Frost, B. Ronald; Frost, Carol D.

1988-01-01

The granulite uncertainty principle, which states that it is difficult or impossible to determine with certainty the maximum geopressure and geotemperature that a granulite has experienced, is addressed. Also, geochemical fingerprinting cannot always be used reliably in the nebulous region that is transitional between metamorphic and igneous environments. Ion exchange thermometers are typically useful to approximately 800 C in slowly cooled plutonic rocks unless one uses a reintegration technique on unmixed minerals, or unless a metastable mineral assemblage can be observed. It is argued that in most granulites, fossil temperatures are typically obliterated by reequilibration and/or deformation during slow cooling. Granulite metamorphism may be further complicated by the common association with igneous activity. The previously-used geochemical indicators such as high K/Rb ratios and LIL depletion may not be strictly the result of granulite facies metamorphic depletion, but also may result from igneous processes, which depend on bulk and mineral compositions and on the mineralogy of the protolith. Detailed geologic mapping will be the ultimate arbitrator of whether a given geochemical signature is the result of igneous or metamorphic processes.

Formation and alteration of airborne particles in the subway environment.

PubMed

Moreno, T; Querol, X; Martins, V; Minguillón, M C; Reche, C; Ku, L H; Eun, H R; Ahn, K H; Capdevila, M; de Miguel, E

2017-01-25

Most particles in the rail subway environment are sub-micron sized ferruginous flakes and splinters generated mechanically by frictional wear of brake pads, wheels and rails. To better understand the mechanisms of formation and the alteration processes affecting inhalable particles in subways, PM samples (1-2.5 μm and 2.5-10 μm) were collected in the Barcelona Metro and then studied under a scanning electron microscope. Most particles in these samples are hematitic (up to 88%), with relatively minor amounts of mineral matter (up to 9%) and sulphates (up to 5%). Detailed microscopy (using back scattered and TEM-DRX imaging) reveals how many of the metallic particles comprise the metallic Fe nucleus surrounded by hematite (Fe 2 O 3 ) and a coating of sulphate and chloride salts mixed with mineral matter (including Ca-carbonates, clay minerals and quartz). These observations record the emission of fine to ultrafine FePM by frictional wear at elevated temperatures that promote rapid partial (or complete) oxidation of the native metal. Water condensing on the PM surface during cooling leads to the adsorption of inorganic mineral particles that coat the iron oxide. The distinctively layered polymineralic structure that results from these processes is peculiar to particles generated in the subway environment and very different from PM typically inhaled outdoors.

Formation of Hematite fine crystals by hydrothermal alteration of synthetic Martian basalt, static and fluid flow experiments

NASA Astrophysics Data System (ADS)

Kobayashi, K.; Isobe, H.

2011-12-01

Exploration made by Martian rovers and probes provided enormous information on the composition of the Martian surface materials. Origin and formation processes of the Martian surface materials should be various depending on topography and history of the Martian crust. Especially, iron minerals in the Martian soil should have essential role to characterize surface environment of the "red planet". In the present study, experimental reproduction of the Martian soil was carried out by hydrothermal alteration of the synthetic iron-rich basaltic rock. Experimental conditions for temperature and fluid composition followed Isobe and Yoshizawa (2010). Static alteration experiments are carried out at 100 °C and 150 °C, and mass ratio of the starting material to the pH1.0 sulfuric acid solution is 1:50. Run durations are 1, 2, 4 or 8 weeks. Appropriate mass of dry ice was sealed in the experimental vessels to expel atmospheric oxygen with CO2. For the static experiments, powdered starting materials were charged in PFA vial to keep textures of the run products. For the fluid flow experiments, we constructed closed loop with Teflon tube inclined approximately 45°. One of the vertical tube is charged with crushed synthetic basalt and heated approximately 150°C by aluminum block with ribbon heater. Surlfuric acid solution flows through the tube from bottom to top and cooled at the end of the aluminum block. Cooled solution returns to the bottom of the heated tube through another vertical tube without heating block. In the static condition run products, characteristic iron mineral particles are formed for 100°C and 150°C concordant with Isobe and Yoshizawa (2010). These iron minerals distributed not only inside the starting material powder but also on the surface of the reaction vessel and the PFA vial in the reactive solution. The surface of the reaction vessel shows orange and reddish color on 100°C and 150°C run products, respectively. By SEM observation, dissolution of melt and olivine grains were observed, and iron mineral particles substituted olivine partly. Diameters of the iron mineral particles are submicron to several micron meters at 100°C, and slowly increase with run durations and temperatures. In the fluid flow experiment, deposition of the characteristic iron minerals occur inside the heated tube. Distribution of iron minerals corresponds to temperature gradient and fluid flow direction. Iron minerals are partially covered by silica phase with submicron meters in thickness. The occurrence of the iron minerals in the run products of this study suggests that characteristic iron mineral fine particles including hematite and goethite were formed by acidic hydrothermal alteration of iron-rich basaltic rock even at remote region from the source materials.

Variability in range cow mineral use is associated with season and daily high temperature in Northern Great Plains

USDA-ARS?s Scientific Manuscript database

Accurate assessment of mineral nutrition in range cattle is complicated by seasonal changes in diet mineral concentrations, shifting requirements and a lack of knowledge of seasonal mineral intake variability. This study was designed to evaluate variation in herd mineral intake, and individual cow m...

The influence of scale inhibitors on calcium oxalate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, J.S.

1999-11-01

Precipitation of calcium oxalate is a common occurrence in mammalian urinary tract deposits and in various industrial processes such as paper making, brewery fermentation, sugar evaporation, and tannin concentration. Between pH 3.5 to 4.5 the driving force for calcium oxalate precipitation increases almost by three fold. It is a complicated process to predict both the nature of a deposit and at which stage of a multi-effect evaporator a particular mineral will deposit, as this depends on temperature, pH, total solids, and kinetics of mineralization. It is quite a challenge to inhibit calcium oxalate precipitation in the pH range of 4--6.more » Al{sup 3+} ions provide excellent threshold inhibition in this pH range and can be used to augment traditional inhibitors such as polyphosphates and polycarboxylates.« less

Mineralogy of ash of some American coals: variations with temperature and source

USGS Publications Warehouse

Mitchell, R.S.; Gluskoter, H.J.

1976-01-01

Ten samples of mineral-matter residue were obtained by the radio-frequency low-temperature ashing of subbituminous and bituminous coals. The low-temperature ash samples were then heated progressively from 400 ??C to 1400 ??C at 100 ??C intervals. Mineral phases present at each temperature interval were determined by X-ray diffraction analyses. The minerals originally present in the coals (quartz, kaolinite, illite, pyrite, calcite, gypsum, dolomite, and sphalerite) were all altered to higher temperature phases. Several of these phases, including kaolinite, metakaolinite, mullite, anhydrite, and anorthite, were found only in limited temperature ranges. Therefore the temperature of formation of the ashes in which they occur may be determined. Mineralogical differences were observed between coal samples from the Rocky Mountain Province, the Illinois Basin, and the Appalachians; and as a result of these mineralogical differences, different high-temperature phases resulted as the samples were heated. However, regional generalizations cannot be made until a greater number of samples have been studied. ?? 1976.

Effects of detrital influx in the Pennsylvanian Upper Freeport peat swamp

USGS Publications Warehouse

Ruppert, L.F.; Stanton, R.W.; Blaine, Cecil C.; Eble, C.F.; Dulong, F.T.

1991-01-01

Quartz cathodoluminescence properties and mineralogy of three sets of samples and vegetal and/ or miospore data from two sets of samples from the Upper Freeport coal bed, west-central Pennsylvania, show that detrital influence from a penecontemporaneous channel is limited to an area less than three km from the channel. The sets of samples examined include localities of the coal bed where (1) the coal is thin, split by partings, and near a penecontemporaneous fluvial channel, (2) the coal is relatively thick and located approximately three km from the channel, and (3) the coal is thick and located approximately 12 km from the channel. Samples from locality 1 (nearest the channel) have relatively high-ash yields (low-temperature ash average = 27.3% on a pyrite- and calcite-free basis) and high proportions of quartz and clay minerals. The quartz is primarily detrital, as determined by cathodoluminescent properties, and the ratio of kaolinite to illite is low. In addition, most of the plant remains and miospores indicate peat-forming plants that required low nutrient levels for growth. In contrast, samples from localities 2 and 3, from the more interior parts of the bed, contained predominantly authigenic quartz grains nd yielded low-temperature ash values of less than 14% on a pyrite- and calcite-free basis. The low-temperature ash contains low concentrations of quartz and clay minerals and the ratio of kaolinite to illite is relatively high. Although intact core was not available for paleobotanical analyses, another core collected within 1 km from locality 3 contained plant types interpreted to have required high nutrient levels for growth. These data indicate that mineral formation is dominated by authigenic processes in interior parts of the coal body. Some of the authigenic quartz may have been derived from herbaceous ferns as indicated by patterns in the palynological and paleobotanical data. In contrast, detrital processes appeared to be limited to in areas directly adjacent to the penecontemporaneous channel where the coal bed is high in ash, split by mineral-rich partings, and of little or no economic value. ?? 1991.

Geothermal resources and energy complex use in Russia

NASA Astrophysics Data System (ADS)

Svalova, V.

2009-04-01

Geothermal energy use is the perspective way to clean sustainable development of the world. Russia has rich high and low temperature geothermal resources and makes good steps in their use. In Russia the geothermal resources are used predominantly for heat supply both heating of several cities and settlements on Northern Caucasus and Kamchatka with a total number of the population 500000. Besides in some regions of country the deep heat is used for greenhouses of common area 465000 m2. Most active the hydrothermal resources are used in Krasnodar territory, Dagestan and on Kamchatka. The approximately half of extracted resources is applied for heat supply of habitation and industrial puttings, third - to a heating of greenhouses, and about 13 % - for industrial processes. Besides the thermal waters are used approximately on 150 health resorts and 40 factories on bottling mineral water. The most perspective direction of usage of low temperature geothermal resources is the use of heat pumps. This way is optimal for many regions of Russia - in its European part, on Ural and others. The electricity is generated by some geothermal power plants (GeoPP) only in the Kamchatka Peninsula and Kuril Islands. At present three stations work in Kamchatka: Pauzhetka GeoPP (11MW e installed capacity) and two Severo-Mutnovka GeoPP ( 12 and 50 MWe). Moreover, another GeoPP of 100 MVe is now under preparation in the same place. Two small GeoPP are in operation in Kuril's Kunashir Isl, and Iturup Isl, with installed capacity of 2,б MWe and 6 MWe respectively. There are two possible uses of geothermal resources depending on structure and properties of thermal waters: heat/power and mineral extraction. The heat/power direction is preferable for low mineralized waters when valuable components in industrial concentration are absent, and the general mineralization does not interfere with normal operation of system. When high potential geothermal waters are characterized by the high mineralization and propensity for scaling, the extraction of mineral components should be considered. The mineral-extraction direction is basic for geothermal waters, containing valuable components in industrial quantities. Thus, the ability to extract minerals is dependent upon the use and maturity of recovery technologies. For such waters the heat is an added product, which use can raise efficiency of basic mineral production processes and even to save fuel. The process of extraction of valuable components should be dominant in such systems. The most significant deposits of thermal waters represent the brines containing from 35 up to 400 and more g/l of salts. They are mineral raw materials for many chemical elements. Many brines can become deposits of valuable chemical elements: cesium, boron, strontium, tantalum, magnesium, calcium, tungsten, etc. Basically it is possible to recover iodine, bromine, boron, chloride salts of ammonium, potassium, sodium, calcium and magnesium from natural solutions using inexpensive technological solutions. Extraction of other chemical elements is complicated due to high cost of technology. There is a perspective method of ion-exchange pitches for selective extraction of certain components from natural waters. In a basis of the method there is the principle of selective sorption of ions of useful elements or their complexes in solutions with special compounds. Works of some scientific institutes in Russia strive to create the procedures of chemical processing of hydrothermal minerals to expand the spheres of its economic application. Many laboratory and natural tests on extraction of valuable components from thermal waters confirm the necessity and an opportunity of complex use of this nonconventional raw material. It is planned to recover I, Br, KCl, CaCl, NaCl from brines in Yaroslavl area. New methods of mineral and valuable elements extraction from industrial solutions are developed on the basis of biosorbent use.

The importance of geochemical processes for the sustainability of deep geothermal systems: insights from coupled thermal-hydraulic-chemical modeling of the geothermal system at Bad Blumau, Austria

NASA Astrophysics Data System (ADS)

Alt-Epping, P.; Waber, H. N.; Eichinger, L.; Diamond, L. W.

2009-04-01

We use reactive-transport models patterned after the geothermal system at Bad Blumau, Austria, to track the fate of a fluid during its ascent from the geothermal reservoir to the surface, where it undergoes heat- and CO2-extraction, and during its subsequent reinjection into the deep aquifer. The fluid in the reservoir is in equilibrium with the carbonate-dominated mineralogy of the aquifer rock at local temperature and pressure conditions. Pressure and conductive temperature changes during ascent and descent of the fluid induce changes in mineral solubilities. Subsequent mineral precipitation within the borehole changes the fluid composition and gradually clogs the borehole, thereby obstructing fluid flow. Because different minerals exhibit different solubilities as a function of temperature, the mineral assemblages that precipitate in the production well are distinct from those in the injection well. For instance, if the fluid in the reservoir is saturated in quartz, then the prograde solubility behaviour of quartz favours its precipitation in the production well. Conversely, carbonate minerals tend to precipitate in the injection well owing to their retrograde solubility functions. However, calculating the distribution of mineral phases is complicated by the fact that the precipitation of some minerals is kinetically controlled, such that they may continue to precipitate far into the injection well (e.g. quartz). The strongest modification of the fluid composition and the greatest potential for mineral precipitation occurs during heat extraction, and, in the particular case of Bad Blumau, during the extraction of CO2 at the surface. The extraction of CO2 entails a dramatic increase in the pH and leads to massive precipitation of carbonate minerals. Simulations suggest that, in the worst case, the extraction of CO2 can cause the borehole to be sealed by carbonate minerals within a few weeks. Thus, the use of chemical additives to inhibit carbonate precipitation is imperative in the Bad Blumau system. Furthermore, any modification of the fluid composition caused by mineral precipitation along the fluid's pathway means that the reinjected fluid is no longer in equilibrium with the aquifer rock. Consequently, rock-water interaction and fluid mixing at the base of the injection well drive chemical reactions that cause changes in porosity and permeability of the aquifer, potentially compromising the efficiency of the geothermal system. One concern during geothermal energy production is that of chemical corrosion of the borehole casing. For a range of "what-if" scenarios we explore the effect of corrosion on the fluid composition and on mineral precipitation to identify chemical fingerprints that could be used as corrosion indicators. Once suitable indicators are identified, incipient corrosion could be detected early on during regular chemical monitoring. Corrosion of the casing is typically associated with the release of Fe and H2 into the circulating fluid. However, the implications of this release depend on the local chemical conditions where corrosion occurs. For instance, elevated H2 in the fluid is a corrosion indicator only if it is not involved in subsequent redox reactions. Similarly, low H2 concentrations do not rule out possible corrosion. In general, the interpretation of a fluid or a mineral sample requires the understanding of chemical processes that occur along the flowpath throughout the geothermal system. If direct observations are not possible, then this understanding can only be achieved through numerical simulations that integrate and couple fluid flow, heat transport and chemical reactions within one theoretical framework. Our simulations demonstrate that these models are useful for quantifying the impact and minimizing the risk that chemical reactions may have on the productivity and sustainability of a geothermal system.

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

NASA Astrophysics Data System (ADS)

Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

2015-10-01

;Clumped-isotope; thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope ;clumps;). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals. We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3- and CO32-. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two types of experiments yielded statistically indistinguishable results, and these measurements yield a calibration that overlaps with our theoretical predictions for calcite at equilibrium. The slow-growing Devils Hole calcite exhibits Δ47 and δ18O values consistent with lattice equilibrium. Factors influencing DIC speciation (pH, salinity) and the timescale for DIC equilibration, as well as reactions at the mineral-solution interface, have the potential to influence clumped-isotope signatures and the δ18O of carbonate minerals. In fast-growing carbonate minerals, solution chemistry may be an important factor, particularly over extremes of pH and salinity. If a crystal grows too rapidly to reach an internal equilibrium (i.e., achieve the value for the temperature-dependent mineral lattice equilibrium), it may record the clumped-isotope signature of a DIC species (e.g., the temperature-dependent equilibrium of HCO3-) or a mixture of DIC species, and hence record a disequilibrium mineral composition. For extremely slow-growing crystals, and for rapidly-grown samples grown at a pH where HCO3- dominates the DIC pool at equilibrium, effects of solution chemistry are likely to be relatively small or negligible. In summary, growth environment, solution chemistry, surface equilibria, and precipitation rate may all play a role in dictating whether a crystal achieves equilibrium or disequilibrium clumped-isotope signatures.

Generation of Hydrogen and Methane during Experimental Low-Temperature Reaction of Ultramafic Rocks with Water.

PubMed

McCollom, Thomas M; Donaldson, Christopher

2016-06-01

Serpentinization of ultramafic rocks is widely recognized as a source of molecular hydrogen (H2) and methane (CH4) to support microbial activity, but the extent and rates of formation of these compounds in low-temperature, near-surface environments are poorly understood. Laboratory experiments were conducted to examine the production of H2 and CH4 during low-temperature reaction of water with ultramafic rocks and minerals. Experiments were performed by heating olivine or harzburgite with aqueous solutions at 90°C for up to 213 days in glass bottles sealed with butyl rubber stoppers. Although H2 and CH4 increased steadily throughout the experiments, the levels were very similar to those found in mineral-free controls, indicating that the rubber stoppers were the predominant source of these compounds. Levels of H2 above background were observed only during the first few days of reaction of harzburgite when CO2 was added to the headspace, with no detectable production of H2 or CH4 above background during further heating of the harzburgite or in experiments with other mineral reactants. Consequently, our results indicate that production of H2 and CH4 during low-temperature alteration of ultramafic rocks may be much more limited than some recent experimental studies have suggested. We also found no evidence to support a recent report suggesting that spinels in ultramafic rocks may stimulate H2 production. While secondary silicates were observed to precipitate during the experiments, formation of these deposits was dominated by Si released by dissolution of the glass bottles, and reaction of the primary silicate minerals appeared to be very limited. While use of glass bottles and rubber stoppers has become commonplace in experiments intended to study processes that occur during serpentinization of ultramafic rocks at low temperatures, the high levels of H2, CH4, and SiO2 released during heating indicate that these reactor materials are unsuitable for this purpose. Serpentinization-Hydrogen generation-Abiotic methane synthesis. Astrobiology 16, 389-406.

Modeling low-temperature serpentinization reactions to estimate molecular hydrogen production with implications for potential microbial life on Saturn's moon Enceladus.

NASA Astrophysics Data System (ADS)

Zwicker, Jennifer; Smrzka, Daniel; Taubner, Ruth-Sophie; Bach, Wolfgang; Rittmann, Simon; Schleper, Christa; Peckmann, Jörn

2017-04-01

Serpentinization of ultramafic rocks attracts much interest in research on the origin of life on Earth and the search for life on extraterrestrial bodies including icy moons like Enceladus. Serpentinization on Earth occurs in peridotite-hosted systems at slow-spreading mid-ocean ridges, and produces large amounts of molecular hydrogen and methane. These reduced compounds can be utilized by diverse chemosynthetic microbial consortia as a metabolic energy source. Although many hydrothermal vents emit hot and acidic fluids today, it is more likely that life originated in the Archean at sites producing much cooler and more alkaline fluids that allowed for the synthesis and stability of essential organic molecules necessary for life. Therefore, a detailed understanding of water-rock interaction processes during low-temperature serpentinization is of crucial importance in assessing the life-sustaining potential of these environments. In the course of serpentinization, the metasomatic hydration of olivine and pyroxene produces various minerals including serpentine minerals, magnetite, brucite, and carbonates. Hydrogen production only occurs if ferrous iron within iron-bearing minerals is oxidized and incorporated as ferric iron into magnetite. The PHREEQC code was used to model the pH- and temperature-dependent dissolution of olivine and pyroxene to form serpentine, magnetite and hydrogen under pressure and temperature conditions that may exist on Saturn's icy moon Enceladus. Various model setups at 25 and 50°C were run to assess the influence of environmental parameters on hydrogen production. The results reveal that hydrogen production rates depend on the composition of the initial mineral assemblage and temperature. The current assumption is that there is a gaseous phase between Enceladus' ice sheet and subsurface ocean. To test various scenarios, model runs were conducted with and without the presence of a gas phase. The model results show that hydrogen production is further dependent on carbon dioxide partial pressure within the gas phase. Moreover, no other gases apart from hydrogen, such as methane, were produced in any of the model runs. The combined results offer a constraint on hydrogen production over time, and may aid habitability assessments of extraterrestrial bodies where serpentinization could occur.

Carbonate mineral solubility at low temperatures in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system

NASA Astrophysics Data System (ADS)

Marion, Giles M.

2001-06-01

Carbonate minerals have played an important role in the geochemical evolution of Earth, and may have also played an important role in the geochemical evolution of Mars and Europa. Several models have been published in recent years that describe chloride and sulfate mineral solubilities in concentrated brines using the Pitzer equations. Few of these models are parameterized for subzero temperatures, and those that are do not include carbonate chemistry. The objectives of this work are to estimate Pitzer-equation bicarbonate-carbonate parameters and carbonate mineral solubility products and to incorporate them into the FREZCHEM model to predict carbonate mineral solubilities in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system at low temperatures (≤25°C) with a special focus on subzero temperatures. Most of the Pitzer-equation parameters and equilibrium constants are taken from the literature and extrapolated into the subzero temperature range. Solubility products for 14 sodium, potassium, magnesium, and calcium bicarbonate and carbonate minerals are included in the model. Most of the experimental data are at temperatures ≥ -8°C; only for the NaHCO 3-NaCl-H 2O and Na 2CO 3-NaCl-H 2O systems are there bicarbonate and carbonate data to temperatures as low as -21.6°C. In general, the fit of the model to the experimental data is good. For example, calculated eutectic temperatures and compositions for NaHCO 3, Na 2CO 3, and their mixtures with NaCl and Na 2SO 4 salts are in good agreement with experimental data to temperatures as low as -21.6°C. Application of the model to eight saline, alkaline carbonate waters give predicted pHs ranging from 9.2 to 10.2, in comparison with measured pHs that range from 8.7 to 10.2. The model suggests that the CaCO 3 mineral that precipitates during seawater freezing is probably calcite and not ikaite. The model demonstrates that a proposed salt assemblage for the icy surface of Europa consisting of highly hydrated MgSO 4 salts and natron (Na 2CO 3 · 10H 2O) is an incompatible salt assemblage.

Rock-colonizing plants: abundance of the endemic cactus Mammillaria fraileana related to rock type in the southern Sonoran Desert

Treesearch

Blanca R. Lopez; Yoav Bashan; Macario Bacilio; Gustavo De la Cruz-Aguero

2009-01-01

Establishment, colonization, and permanence of plants affect biogenic and physical processes leading to development of soil. Rockiness, temperature, and humidity are accepted explanations to the influence and the presence of rock-dwelling plants, but the relationship between mineral and chemical composition of rocks with plant abundance is unknown in some regions. This...

Temperature response of permafrost soil carbon is attenuated by mineral protection.

PubMed

Gentsch, Norman; Wild, Birgit; Mikutta, Robert; Čapek, Petr; Diáková, Katka; Schrumpf, Marion; Turner, Stephanie; Minnich, Cynthia; Schaarschmidt, Frank; Shibistova, Olga; Schnecker, Jörg; Urich, Tim; Gittel, Antje; Šantrůčková, Hana; Bárta, Jiři; Lashchinskiy, Nikolay; Fuß, Roland; Richter, Andreas; Guggenberger, Georg

2018-05-18

Climate change in Arctic ecosystems fosters permafrost thaw and makes massive amounts of ancient soil organic carbon (OC) available to microbial breakdown. However, fractions of the organic matter (OM) may be protected from rapid decomposition by their association with minerals. Little is known about the effects of mineral-organic associations (MOA) on the microbial accessibility of OM in permafrost soils and it is not clear which factors control its temperature sensitivity. In order to investigate if and how permafrost soil OC turnover is affected by mineral controls, the heavy fraction (HF) representing mostly MOA was obtained by density fractionation from 27 permafrost soil profiles of the Siberian Arctic. In parallel laboratory incubations, the unfractionated soils (bulk) and their HF were comparatively incubated for 175 days at 5 and 15°C. The HF was equivalent to 70 ± 9% of the bulk CO 2 respiration as compared to a share of 63 ± 1% of bulk OC that was stored in the HF. Significant reduction of OC mineralization was found in all treatments with increasing OC content of the HF (HF-OC), clay-size minerals and Fe or Al oxyhydroxides. Temperature sensitivity (Q10) decreased with increasing soil depth from 2.4 to 1.4 in the bulk soil and from 2.9 to 1.5 in the HF. A concurrent increase in the metal-to-HF-OC ratios with soil depth suggests a stronger bonding of OM to minerals in the subsoil. There, the younger 14 C signature in CO 2 than that of the OC indicates a preferential decomposition of the more recent OM and the existence of a MOA fraction with limited access of OM to decomposers. These results indicate strong mineral controls on the decomposability of OM after permafrost thaw and on its temperature sensitivity. Thus, we here provide evidence that OM temperature sensitivity can be attenuated by MOA in permafrost soils. © 2018 John Wiley & Sons Ltd.

Orogenic-type copper-gold-arsenic-(bismuth) mineralization at Flatschach (Eastern Alps), Austria

NASA Astrophysics Data System (ADS)

Raith, Johann G.; Leitner, Thomas; Paar, Werner H.

2015-10-01

Structurally controlled Cu-Au mineralization in the historic Flatschach mining district (Styria, Austria) occurs in a NE-SW to NNE-WSW oriented vein system as multiple steep-dipping calcite-(dolomite)-quartz veins in amphibolite facies metamorphic rocks (banded gneisses/amphibolites, orthogneisses, metagranitoids) of the poly-metamorphosed Austroalpine Silvretta-Seckau nappe. Vein formation postdated ductile deformation events and Eoalpine (Late Cretaceous) peak metamorphism but predated Early to Middle Miocene sediment deposition in the Fohnsdorf pull-apart basin; coal-bearing sediments cover the metamorphic basement plus the mineralized veins at the northern edge of the basin. Three gold-bearing ore stages consist of a stage 1 primary hydrothermal (mesothermal?) ore assemblage dominated by chalcopyrite, pyrite and arsenopyrite. Associated minor minerals include alloclasite, enargite, bornite, sphalerite, galena, bismuth and matildite. Gold in this stage is spatially associated with chalcopyrite occurring as inclusions, along re-healed micro-fractures or along grain boundaries of chalcopyrite with pyrite or arsenopyrite. Sericite-carbonate alteration is developed around the veins. Stage 2 ore minerals formed by the replacement of stage 1 sulfides and include digenite, anilite, "blue-remaining covellite" (spionkopite, yarrowite), bismuth, and the rare copper arsenides domeykite and koutekite. Gold in stage 2 is angular to rounded in shape and occurs primarily in the carbonate (calcite, Fe-dolomite) gangue and less commonly together with digenite, domeykite/koutekite and bismuth. Stage 3 is a strongly oxidized assemblage that includes hematite, cuprite, and various secondary Cu- and Fe-hydroxides and -carbonates. It formed during supergene weathering. Stage 1 and 2 gold consists mostly of electrum (gold fineness 640-860; mean = 725; n = 46), and rare near pure gold (fineness 930-940; n = 6). Gold in stage 3 is Ag-rich electrum (fineness 350-490, n = 12), and has a high Hg content (up to 11 mass %). The Cu-Au deposits in the Flatschach area show similarities with meso- to epizonal orogenic lode gold deposits regarding the geological setting, the structural control of mineralization, the type of alteration, the early (stage 1) sulfide assemblage and composition of gold. Unique about the Flatschach district is the lower-temperature overprint of copper arsenides (domeykite and koutekite) and copper sulfides (djurleite, yarrowite/spionkopite) on earlier formed sulfide mineralization. Based on mineralogical considerations temperature of stage 2 mineralization was between about 70 °C and 160 °C. Gold was locally mobilized during this low-temperature hydrothermal overprint as well as during stage 3 supergene oxidation and cementation processes.

Chemical equilibria of thermal waters for the application of geothermometers from the Guanzhong basin, China

NASA Astrophysics Data System (ADS)

Xilai, Zheng; Armannsson, Halldor; Yongle, Li; Hanxue, Qiu

2002-03-01

In this study, representative samples from thermal wells and springs were chemically analyzed and geothermometers were used to calculate the deep temperatures of geothermal reservoirs on the basis of water-mineral equilibrium. In some cases, however, the chemical components are not in equilibrium with the minerals in the reservoir. Therefore, log( Q/ K) diagrams are used to study the chemical equilibrium for the minerals that are likely to participate. The Na-K-Mg triangular diagram is also applied to evaluate the equilibrium of water with reservoir rocks. Standard curves at the reference temperatures are prepared to reveal which type of silica geothermometer is appropriate for the specified condition. This study shows that water samples from geothermal wells W9 and W12 are in equilibrium with the selective minerals, and chalcedony may control the fluid-silica equilibrium. It is estimated that there is an exploitable low-temperature reservoir with possible temperatures of 80-90°C in the Guanzhong basin.

Long-term fertilization of a boreal Norway spruce forest increases the temperature sensitivity of soil organic carbon mineralization

PubMed Central

Coucheney, Elsa; Strömgren, Monika; Lerch, Thomas Z; Herrmann, Anke M

2013-01-01

Boreal ecosystems store one-third of global soil organic carbon (SOC) and are particularly sensitive to climate warming and higher nutrient inputs. Thus, a better description of how forest managements such as nutrient fertilization impact soil carbon (C) and its temperature sensitivity is needed to better predict feedbacks between C cycling and climate. The temperature sensitivity of in situ soil C respiration was investigated in a boreal forest, which has received long-term nutrient fertilization (22 years), and compared with the temperature sensitivity of C mineralization measured in the laboratory. We found that the fertilization treatment increased both the response of soil in situ CO2 effluxes to a warming treatment and the temperature sensitivity of C mineralization measured in the laboratory (Q10). These results suggested that soil C may be more sensitive to an increase in temperature in long-term fertilized in comparison with nutrient poor boreal ecosystems. Furthermore, the fertilization treatment modified the SOC content and the microbial community composition, but we found no direct relationship between either SOC or microbial changes and the temperature sensitivity of C mineralization. However, the relation between the soil C:N ratio and the fungal/bacterial ratio was changed in the combined warmed and fertilized treatment compared with the other treatments, which suggest that strong interaction mechanisms may occur between nutrient input and warming in boreal soils. Further research is needed to unravel into more details in how far soil organic matter and microbial community composition changes are responsible for the change in the temperature sensitivity of soil C under increasing mineral N inputs. Such research would help to take into account the effect of fertilization managements on soil C storage in C cycling numerical models. PMID:24455147

Interstellar and Solar Nebula Materials in Cometary Dust

NASA Technical Reports Server (NTRS)

Messenger, Scott; Nakamura-Messenger, Keiko; Keller, Lindsay; Nguyen, Ann; Clemett, Simon

2017-01-01

Laboratory studies of cometary dust collected in the stratosphere and returned from comet 81P/Wild 2 by the Stardust spacecraft have revealed ancient interstellar grains and molecular cloud organic matter that record a range of astrophysical processes and the first steps of planetary formation. Presolar materials are rarer meteorites owing to high temperature processing in the solar nebula and hydrothermal alteration on their asteroidal parent bodies. The greater preservation of presolar materials in comets is attributed to their low accretion temperatures and limited planetary processing. Yet, comets also contain a large complement of high temperature materials from the inner Solar System. Owing to the limited and biased sampling of comets to date, the proportions of interstellar and Solar System materials within them remains highly uncertain. Interstellar materials are identified by coordinated isotopic, mineralogical, and chemical measurements at the scale of individual grains. Chondritic porous interplanetary dust particles (CP IDPs) that likely derive from comets are made up of 0.1 - 10 micron-sized silicates, Fe-Ni-sulfides, oxides, and other phases bound by organic material. As much as 1% of the silicates are interstellar grains that have exotic isotopic compositions imparted by nucleosynthetic processes in their parent stars. Crystalline silicates in CP IDPs dominantly have normal isotopic compositions and probably formed in the Solar System. 81P samples include isotopically normal refractory minerals that resemble Ca-Al rich inclusions and chondrules common in meteorites. The origins of sub-micron amorphous silicates in IDPs are not certain, but at least a few % of them are interstellar grains. The remainder have isotopic compositions consistent with Solar System origins and elemental compositions that are inconsistent with interstellar grain properties, thus favoring formation in the solar nebula [4]. The organic component in comets and primitive meteorites has large enrichments in D/H and N-15/N-14 relative to terrestrial materials. These isotopic signatures are probably due to low temperature chemical processes in cold molecular clouds or the outermost reaches of the protoplanetary disk. The greatest isotopic anomalies are found in sub-micron organic nanoglobules that show chemical signatures of interstellar chemistry. The observation that cometary dust is mostly composed of isotopically normal minerals within isotopically anomalous organic matter is difficult to reconcile with the formation models of each component. The mineral component likely formed in high temperature processes in the inner Solar System, while the organic fraction shows isotopic and chemical signatures of formation near 10 K. Studying more primitive remnants of the Solar System starting materials would help in resolving this paradox. Comets formed across a vast expanse of the outer disk under differing thermal and collisional regimes, and some are likely to be better preserved than others. Finding truly pristine aggregates of presolar materials may require return of a pristine sample of comet nucleus material.

Seafloor weathering buffering climate: numerical experiments

NASA Astrophysics Data System (ADS)

Farahat, N. X.; Archer, D. E.; Abbot, D. S.

2013-12-01

Continental silicate weathering is widely held to consume atmospheric CO2 at a rate controlled in part by temperature, resulting in a climate-weathering feedback [Walker et al., 1981]. It has been suggested that weathering of oceanic crust of warm mid-ocean ridge flanks also has a CO2 uptake rate that is controlled by climate [Sleep and Zahnle, 2001; Brady and Gislason, 1997]. Although this effect might not be significant on present-day Earth [Caldeira, 1995], seafloor weathering may be more pronounced during snowball states [Le Hir et al., 2008], during the Archean when seafloor spreading rates were faster [Sleep and Zahnle, 2001], and on waterworld planets [Abbot et al., 2012]. Previous studies of seafloor weathering have made significant contributions using qualitative, generally one-box, models, and the logical next step is to extend this work using a spatially resolved model. For example, experiments demonstrate that seafloor weathering reactions are temperature dependent, but it is not clear whether the deep ocean temperature affects the temperature at which the reactions occur, or if instead this temperature is set only by geothermal processes. Our goal is to develop a 2-D numerical model that can simulate hydrothermal circulation and resulting alteration of oceanic basalts, and can therefore address such questions. A model of diffusive and convective heat transfer in fluid-saturated porous media simulates hydrothermal circulation through porous oceanic basalt. Unsteady natural convection is solved for using a Darcy model of porous media flow that has been extensively benchmarked. Background hydrothermal circulation is coupled to mineral reaction kinetics of basaltic alteration and hydrothermal mineral precipitation. In order to quantify seafloor weathering as a climate-weathering feedback process, this model focuses on hydrothermal reactions that influence carbon uptake as well as ocean alkalinity: silicate rock dissolution, calcium and magnesium leaching reactions, carbonate precipitation, and clay formation.

Oxygen isotope thermometry of quartz-Al2SiO5veins in high-grade metamorphic rocks on Naxos island (Greece)

NASA Astrophysics Data System (ADS)

Putlitz, Benita; Valley, John; Matthews, Alan; Katzir, Yaron

2002-04-01

Diffusion models predict that peak metamorphic temperatures are best recorded by the oxygen isotope fractionation between minerals in a bi-mineralic rock in which a refractory accessory mineral with slow oxygen diffusion rate is modally minor to a mineral with a faster diffusion rate. This premise is demonstrated for high-grade metamorphism on the island of Naxos, Greece, where quartz-kyanite oxygen isotope thermometry from veins in high-grade metamorphic pelites gives temperatures of 635-690 °C. These temperatures are in excellent agreement with independent thermometry for the regional M2 peak metamorphic conditions and show that the vein minerals isotopically equilibrated at the peak of metamorphism. Quartz-sillimanite fractionations in the same veins give similar temperatures (680+/-35 °C) and suggest that the veins grew near to the kyanite-sillimanite boundary, corresponding to pressures of 6.5 to 7.5 kbar for temperatures of 635-685 °C. By contrast, quartz-kyanite and quartz-biotite pairs in the host rocks yield lower temperature estimates than the veins (590-600 and 350-550 °C, respectively). These lower apparent temperatures are also predicted from calculations of diffusional resetting in the polyphase host-rock system. The data demonstrate that bimineralic vein assemblages can be used as accurate thermometers in high-temperature rocks whereas retrograde exchange remains a major problem in many polymineralic rocks.

Delineating Spatial Patterns in the Yellowstone Hydrothermal System using Geothermometry

NASA Astrophysics Data System (ADS)

King, J.; Hurwitz, S.; Lowenstern, J. B.

2015-12-01

Yellowstone National Park is unmatched with regard to its quantity of active hydrothermal features. Origins of thermal waters in its geyser basins have been traced to mixing of a deep parent water with meteoric waters in shallow local reservoirs (Fournier, 1989). A mineral-solution equilibrium model was developed to calculate water-rock chemical re-equilibration temperatures in these shallow reservoirs. We use the GeoT program, which uses water composition data as input to calculate saturation indices of selected minerals; the "best-clustering" minerals are then statistically determined to infer reservoir temperatures (Spycher et al., 2013). We develop the method using water composition data from Heart Lake Geyser Basin (HLGB), for which both chemical and isotopic geothermometers predict a reservoir water temperature of 205°C ± 10°C (Lowenstern et al., 2012), and minerals found in drill cores in Yellowstone's geyser basins. We test the model for sensitivity to major element composition, pH, Total Inorganic Carbon (TIC) and selected minerals to optimize model parameters. Calculated temperatures are most accurate at pH values below 9.0, and closely match the equilibrium saturation indices of quartz, stilbite, microcline, and albite. The model is optimized with a TIC concentration that is consistent with the mass of diffuse CO2 flux in HLGB (Lowenstern et al., 2012). We then use water compositions from other thermal basins in Yellowstone in search of spatial variations in reservoir temperatures. We then compare the calculated temperatures with various SiO2 and cation geothermometers.

The Use of Artificial Neural Network for Prediction of Dissolution Kinetics

PubMed Central

Elçiçek, H.; Akdoğan, E.; Karagöz, S.

2014-01-01

Colemanite is a preferred boron mineral in industry, such as boric acid production, fabrication of heat resistant glass, and cleaning agents. Dissolution of the mineral is one of the most important processes for these industries. In this study, dissolution of colemanite was examined in water saturated with carbon dioxide solutions. Also, prediction of dissolution rate was determined using artificial neural networks (ANNs) which are based on the multilayered perceptron. Reaction temperature, total pressure, stirring speed, solid/liquid ratio, particle size, and reaction time were selected as input parameters to predict the dissolution rate. Experimental dataset was used to train multilayer perceptron (MLP) networks to allow for prediction of dissolution kinetics. Developing ANNs has provided highly accurate predictions in comparison with an obtained mathematical model used through regression method. We conclude that ANNs may be a preferred alternative approach instead of conventional statistical methods for prediction of boron minerals. PMID:25028674

Temperature and Redox Effect on Mineral Colonization in Juan de Fuca Ridge Flank Subsurface Crustal Fluids

PubMed Central

Baquiran, Jean-Paul M.; Ramírez, Gustavo A.; Haddad, Amanda G.; Toner, Brandy M.; Hulme, Samuel; Wheat, Charles G.; Edwards, Katrina J.; Orcutt, Beth N.

2016-01-01

To examine microbe-mineral interactions in subsurface oceanic crust, we evaluated microbial colonization on crustal minerals that were incubated in borehole fluids for 1 year at the seafloor wellhead of a crustal borehole observatory (IODP Hole U1301A, Juan de Fuca Ridge flank) as compared to an experiment that was not exposed to subsurface crustal fluids (at nearby IODP Hole U1301B). In comparison to previous studies at these same sites, this approach allowed assessment of the effects of temperature, fluid chemistry, and/or mineralogy on colonization patterns of different mineral substrates, and an opportunity to verify the approach of deploying colonization experiments at an observatory wellhead at the seafloor instead of within the borehole. The Hole U1301B deployment did not have biofilm growth, based on microscopy and DNA extraction, thereby confirming the integrity of the colonization design against bottom seawater intrusion. In contrast, the Hole U1301A deployment supported biofilms dominated by Epsilonproteobacteria (43.5% of 370 16S rRNA gene clone sequences) and Gammaproteobacteria (29.3%). Sequence analysis revealed overlap in microbial communities between different minerals incubated at the Hole U1301A wellhead, indicating that mineralogy did not separate biofilm structure within the 1-year colonization experiment. Differences in the Hole U1301A wellhead biofilm community composition relative to previous studies from within the borehole using similar mineral substrates suggest that temperature and the diffusion of dissolved oxygen through plastic components influenced the mineral colonization experiments positioned at the wellhead. This highlights the capacity of low abundance crustal fluid taxa to rapidly establish communities on diverse mineral substrates under changing environmental conditions such as from temperature and oxygen. PMID:27064928

Characterization of biochar prepared from biogas digestate.

PubMed

Hung, Chao-Yi; Tsai, Wen-Tien; Chen, Jie-Wei; Lin, Yu-Quan; Chang, Yuan-Ming

2017-08-01

In the study, the biogas digestate was evaluated as a potential feedstock for preparing biochars at a broad temperature range of 300-900°C. The physico-chemical and pore properties of the resulting biochars (denoted as SDBC, solid digestate biochar), including calorific value (higher heating value), surface area/pore volume/pore size distribution, true density, scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD), were studied. It was found that the higher heating values of the SDBC products were on a decreasing trend as pyrolysis temperature increased, but they indicated an increase in true density. The results are probably associated with the active pyrolysis of the lignocellulosic fragments and the calcination (or shrinkage) processes, thus resulting in the increased contents of aromatic carbon clusters and main mineral constituents remained. Based on the pore properties, pyrolysis temperature at around 800°C seemed to be the optimal condition for producing SDBC, where its Brunauer-Emmet-Teller (BET) surface area (>100m 2 /g) largely increased as compared to that of the digestate feedstock (<1m 2 /g). Furthermore, the main compositions of mineral ash in the resulting biochar could exist as phosphates, carbonates, or oxides of calcium and other alkali/alkaline earth elements. According to the data on EDS and XRD, more pores could be significantly generated under severe pyrolysis (>700°C) due to the high aromaticity via the thermal decomposition of lignocelluloses and the volatilization of inorganic minerals. Copyright © 2017 Elsevier Ltd. All rights reserved.

30 CFR 7.47 - Deflection temperature test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Deflection temperature test. 7.47 Section 7.47 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.47 Deflection...

30 CFR 7.47 - Deflection temperature test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Deflection temperature test. 7.47 Section 7.47 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.47 Deflection...

Composite membranes for alkaline electrolysis based on polysulfone and mineral fillers

NASA Astrophysics Data System (ADS)

Burnat, Dariusz; Schlupp, Meike; Wichser, Adrian; Lothenbach, Barbara; Gorbar, Michal; Züttel, Andreas; Vogt, Ulrich F.

2015-09-01

Mineral-based membranes for high temperature alkaline electrolysis were developed by a phase inversion process with polysulfone as binder. The long-term stability of new mineral fillers: wollastonite, forsterite and barite was assessed by 8000 h-long leaching experiments (5.5 M KOH, 85 °C) combined with thermodynamic modelling. Barite has released only 6.22 10-4 M of Ba ions into the electrolyte and was selected as promising filler material, due to its excellent stability. Barite-based membranes, prepared by the phase inversion process, were further studied. The resistivity of these membranes in 5.5 M KOH was investigated as a function of membrane thickness and total porosity, hydrodynamic porosity as well as gas purities determined by conducting electrolysis at ambient conditions. It was found that a dense top layer resulting from the phase inversion process, shows resistivity values up to 451.0 ± 22 Ω cm, which is two orders of magnitude higher than a porous bulk membrane microstructure (3.89 Ω cm). Developed membranes provided hydrogen purity of 99.83 at 200 mA cm-2, which is comparable to previously used chrysotile membranes and higher than commercial state-of-the-art Zirfon 500utp membrane. These cost-effective polysulfone - barite membranes are promising candidates as asbestos replacement for commercial applications.

A study of iron mineral transformation to reduce red mud tailings.

PubMed

Li, L Y

2001-01-01

This study examines the effects of iron mineral transformation in an aluminum extraction process on the settling behavior, and the physical and chemical properties of the resulting red mud slurry that must be disposed of. By producing a red mud with a higher solid content, the total volume of mud slurry will also be reduced for a given alumina production rate and more caustic soda will be recovered. The settling behavior and the mineralogical, physical, and physico-chemical properties of one bauxite and three red muds processed under varying conditions were analyzed based on examination of the iron mineral transformations. The properties of red muds derived from the same bauxite can differ markedly due to variations in operating conditions of the Bayer process, such as temperature and the addition of a reducing agent. The settling of red mud can be improved by converting goethite into hematite and/or magnetite to produce a mud of larger particle size, smaller specific surface area, and larger specific gravity, characteristics which reduce the total volume of mud slurry to be disposed of and which allow for less potential contamination from caustic soda. This study also found that the by-product--Bayer sodalite--has the high exchange capacity for Na+ that might contribute to the long-term environmental problems.

Modeling Thermal Pressurization Around Shallow Dikes Using Temperature-Dependent Hydraulic Properties: Implications for Deformation Around Intrusions

NASA Astrophysics Data System (ADS)

Townsend, Meredith R.

2018-01-01

Pressurization and flow of groundwater around igneous intrusions depend in part on the hydraulic diffusivity of the host rocks and processes that enhance diffusivity, such as fracturing, or decrease diffusivity, such as mineral precipitation during chemical alteration. Characterizing and quantifying the coupled effects of alteration, pore pressurization, and deformation have significant implications for deformation around intrusions, geothermal energy, contact metamorphism, and heat transfer at mid-ocean ridges. Fractures around dikes at Ship Rock, New Mexico, indicate that pore pressures in the host rocks exceeded hydrostatic conditions by at least 15 MPa following dike emplacement. Hydraulic measurements and petrographic analysis indicate that mineral precipitation clogged the pores of the host rock, reducing porosity from 0.25 to <0.10 and reducing permeability by 5 orders of magnitude. Field data from Ship Rock are used to motivate and constrain numerical models for thermal pore fluid pressurization adjacent to a meter-scale dike, using temperature-dependent hydraulic properties in the host rock as a proxy for porosity loss by mineral precipitation during chemical alteration. Reduction in permeability by chemical alteration has a negligible effect on pressurization. However, reduction in porosity by mineral precipitation increases fluid pressure by constricting pore volume and is identified as a potentially significant source of pressure. A scaling relationship is derived to determine when porosity loss becomes important; if permeability is low enough, pressurization by porosity loss outweighs pressurization by thermal expansion of fluids.

Sensitivity of mineral dissolution rates to physical weathering : A modeling approach

NASA Astrophysics Data System (ADS)

Opolot, Emmanuel; Finke, Peter

2015-04-01

There is continued interest on accurate estimation of natural weathering rates owing to their importance in soil formation, nutrient cycling, estimation of acidification in soils, rivers and lakes, and in understanding the role of silicate weathering in carbon sequestration. At the same time a challenge does exist to reconcile discrepancies between laboratory-determined weathering rates and natural weathering rates. Studies have consistently reported laboratory rates to be in orders of magnitude faster than the natural weathering rates (White, 2009). These discrepancies have mainly been attributed to (i) changes in fluid composition (ii) changes in primary mineral surfaces (reactive sites) and (iii) the formation of secondary phases; that could slow natural weathering rates. It is indeed difficult to measure the interactive effect of the intrinsic factors (e.g. mineral composition, surface area) and extrinsic factors (e.g. solution composition, climate, bioturbation) occurring at the natural setting, in the laboratory experiments. A modeling approach could be useful in this case. A number of geochemical models (e.g. PHREEQC, EQ3/EQ6) already exist and are capable of estimating mineral dissolution / precipitation rates as a function of time and mineral mass. However most of these approaches assume a constant surface area in a given volume of water (White, 2009). This assumption may become invalid especially at long time scales. One of the widely used weathering models is the PROFILE model (Sverdrup and Warfvinge, 1993). The PROFILE model takes into account the mineral composition, solution composition and surface area in determining dissolution / precipitation rates. However there is less coupling with other processes (e.g. physical weathering, clay migration, bioturbation) which could directly or indirectly influence dissolution / precipitation rates. We propose in this study a coupling between chemical weathering mechanism (defined as a function of reactive area, solution composition, temperature, mineral composition) and the physical weathering module in the SoilGen model which calculates the evolution of particle size (used for surface area calculation) as influenced by temperature gradients. The solution composition in the SoilGen model is also influenced by other processes such as atmospheric inputs, organic matter decomposition, cation exchange, secondary mineral formation and leaching. We then apply this coupled mechanism on a case study involving 3 loess soil profiles to analyze the sensitivity of mineral weathering rates to physical weathering. Initial results show some sensitivity but not that dramatic. The less sensitivity was attributed to dominance of resistant primary minerals (> 70% quartz). Scenarios with different sets of mineralogy will be tested and sensitivity results in terms of silicate mineral dissolution rates and CO2-consumption will be presented in the conference. References Sverdrup H and Warfvinge P., 1993. Calculating field weathering rates using a mechanistic geochemical model PROFILE. Applied Geochemistry, 8:273-283. White, A.F., 2009. Natural weathering rates of silicate minerals. In: Drever, J.I. (Ed.), Surface and Ground Water, Weathering and Soils. In: Holland, H.D., Turekian, K.K. (Eds.), Treatise on Geochemistry. vol. 5. Elsevier-Pergamon, Oxford, pp. 133-168.

Calibrated Hydrothermal Parameters, Barrow, Alaska, 2013

DOE Data Explorer

Atchley, Adam; Painter, Scott; Harp, Dylan; Coon, Ethan; Wilson, Cathy; Liljedahl, Anna; Romanovsky, Vladimir

2015-01-29

A model-observation-experiment process (ModEx) is used to generate three 1D models of characteristic micro-topographical land-formations, which are capable of simulating present active thaw layer (ALT) from current climate conditions. Each column was used in a coupled calibration to identify moss, peat and mineral soil hydrothermal properties to be used in up-scaled simulations. Observational soil temperature data from a tundra site located near Barrow, AK (Area C) is used to calibrate thermal properties of moss, peat, and sandy loam soil to be used in the multiphysics Advanced Terrestrial Simulator (ATS) models. Simulation results are a list of calibrated hydrothermal parameters for moss, peat, and mineral soil hydrothermal parameters.

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

USGS Publications Warehouse

Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

2015-01-01

“Clumped-isotope” thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope “clumps”). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals.We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect.Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3− and CO32−. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two types of experiments yielded statistically indistinguishable results, and these measurements yield a calibration that overlaps with our theoretical predictions for calcite at equilibrium. The slow-growing Devils Hole calcite exhibits Δ47 and δ18O values consistent with lattice equilibrium.Factors influencing DIC speciation (pH, salinity) and the timescale for DIC equilibration, as well as reactions at the mineral–solution interface, have the potential to influence clumped-isotope signatures and the δ18O of carbonate minerals. In fast-growing carbonate minerals, solution chemistry may be an important factor, particularly over extremes of pH and salinity. If a crystal grows too rapidly to reach an internal equilibrium (i.e., achieve the value for the temperature-dependent mineral lattice equilibrium), it may record the clumped-isotope signature of a DIC species (e.g., the temperature-dependent equilibrium of HCO3−) or a mixture of DIC species, and hence record a disequilibrium mineral composition. For extremely slow-growing crystals, and for rapidly-grown samples grown at a pH where HCO3- dominates the DIC pool at equilibrium, effects of solution chemistry are likely to be relatively small or negligible. In summary, growth environment, solution chemistry, surface equilibria, and precipitation rate may all play a role in dictating whether a crystal achieves equilibrium or disequilibrium clumped-isotope signatures.

Weathering of Olivine during Interaction of Sulfate Aerosols with Mars Soil under Current Climate Conditions

NASA Astrophysics Data System (ADS)

Niles, P. B.; Golden, D. C.; Michalski, J. R.; Ming, D. W.

2017-12-01

Sulfur concentrations in the Mars soils are elevated above 1 wt% in nearly every location visited by landed spacecraft. This observation was first made by the Viking landers, and has been confirmed by subsequent missions. The wide distribution of sulfur in martian soils has been attributed to volcanic degassing, formation of sulfate aerosols, and later incorporation into martian soils during gravitational sedimentation. However, later discoveries of more concentrated sulfur bearing sediments by the Opportunity rover has led some to believe that sulfates may instead be a product of evaporation and aeolian redistribution. One question that has not been addressed is whether the modern surface conditions are too cold for weathering of volcanic materials by sulfate aerosols. We suggest here that mixtures of atmospheric aerosols, ice, and dust have the potential for creating small films of cryo-concentrated acidic solutions that may represent an important unexamined environment for understanding weathering processes on Mars. Laboratory experiments were conducted to simulate weathering of olivine under Mars-like conditions. The weathering rates measured in this study suggest that fine grained olivine on Mars would weather into sulfate minerals in short time periods if they are exposed to H2SO4 aerosols at temperatures at or above -40°C. In this system, the strength of the acidic solution is maximized through eutectic freezing in an environment where the silicate minerals are extremely fine grained and have high surface areas. This provides an ideal environment for olivine weathering despite the very low temperatures. The likelihood of substantial sulfur-rich volcanism on Mars and creation of abundant sulfate aerosols suggests that this process would have been important during formation of martian soils and sediments. Future work modeling sulfur release rates during volcanic eruptions and aerosol distribution over the surface will help understand how well this process could concentrate sulfate minerals in nearby surface materials or whether this process would simply result in widespread globally distributed sulfur materials.

The La Unión Au ± Cu prospect, Camagüey District, Cuba: fluid inclusion and stable isotope evidence for ore-forming processes

NASA Astrophysics Data System (ADS)

Santana, Miriela María Ulloa; Moura, Márcia Abrahão; Olivo, Gema R.; Botelho, Nilson Francisquini; Kyser, T. Kurtis; Bühn, Bernhard

2011-01-01

The Camagüey district, Cuba, is known for its epithermal precious metal deposits in a Cretaceous volcanic arc setting. Recently, the La Unión prospect was discovered in the southern part of the district, containing gold and minor copper mineralization interpreted as porphyry type. Mineralization is hosted in a 73.0 ± 1.5 Ma calc-alkaline I-type oxidized porphyry quartz diorite intrusive within volcanic and volcaniclastic rocks of the early Cretaceous Guáimaro Formation. The porphyry is affected by propylitic alteration and crosscut by a network of quartz and carbonate veinlets and veins. Chlorite, epidote, sericite, quartz, and pyrite are the main minerals in the early veins which are cut by late carbonate and zeolite veins. Late barite pseudomorphously replaces pyrite. Gold is associated with pyrite as disseminations in the altered quartz diorite and in the veins, occurring as inclusions or filling fractures in pyrite with 4 g/t Au in bulk samples, and up to 900 ppm Au in in pyrite. Fluid inclusion and oxygen isotope data are consistent with a H2O-NaCl-(KCl) mineralizing fluid, derived from the quartz diorite magma, and trapped at least at 425°C and 1.2 kbar. This primary fluid unmixed into two fluid phases, a hypersaline aqueous fluid and a low-salinity vapor-rich fluid. Boiling during cooling may have played an important role in metal precipitation. Pyrite δ34S values for the La Unión prospect range between 0.71‰ and 1.31‰, consistent with a homogeneous magmatic sulfur source. The fluids in equilibrium with the mineralized rocks have estimated δ18O values from 8‰ to 11.8‰, calculated for a temperature range of 480-505°C. The tectonic environment of the La Unión prospect, its high gold and low copper contents, the physical-chemical characteristics of the mineralizing fluids and the isotopic signature of the alteration minerals and fluids indicate that the La Unión gold mineralization is similar to the porphyry gold type, even though the ore-related epidote-chlorite alteration can be classified as propylitic and not the classic potassic and/or phyllic alteration. The low copper contents in the prospect could be due to a mineralizing fluid previously saturated in copper, which is indicated by trapped chalcopyrite crystals in high-temperature fluid inclusions. The low-temperature paragenesis, represented by carbonate, zeolite and barite, indicates epithermal overprint. The study shows the potential for other gold porphyry-type deposits in the Cretaceous volcanoplutonic arc of Cuba.

The influence of HCl concentration and demineralization temperature of Atrina pectinata shells on quality of chitin

NASA Astrophysics Data System (ADS)

Nugroho, Intan Lazuardi; Pursetyo, Kustiawan Tri; Masithah, Endang Dewi

2017-02-01

Atrina pectinata is one of shells species widely consumed by people, which means the high consumption will generate the availability of shells in the environment as waste. Chitin can be produced from the shells. Shells contain quite high minerals that it should be demineralized to reduce the mineral content from the shells. This study aimed to determine the effect of HCl concentration and temperature affect chitin characteristics as the result of demineralization process from pen shells. The method based on two steps, there were demineralization and deproteination. This study used Completely Randomized Design (CRD) with two factors, including HCl concentration (2N, 4N, and 6N) and temperature (33°C and 60°C) which consists six combination treatments and three replications. Data was analyzed by using Analysis of Variance (ANOVA) and followed by Duncan's Multiple Range Test. The results showed that interaction of HCl concentration and temperature has significant effect (p<0.05) to ash content of chitin. The use concentration of 6N and 33°C produced the lowest ash content. Characteristics chitin resulted from the treatment of 6N and 33°C produced ash content 25.33% ± 6.82, moisture content 3.67% ± 1.10, yield 0.72% ± 0.12 and protein content 5.86%.

Geochemical Analysis for Sedimentary Emerald Mineralization in Western Emerald belt, Colombia

NASA Astrophysics Data System (ADS)

Nino Vasquez, Gabriel Felipe; Song, Sheng-Rong

2017-04-01

1Gabriel Felipe Nino Vasquez and 1Sheng-Rong Song 1Department of Geosciences, National Taiwan University Colombia hosts a large quantity of mineral resources due to its complex tectonic arrangement, and emerald deposits are one of the most representatives for the country. Emeralds in Colombia occur mainly in black shale, and are located in eastern Andes Cordillera with two parallel belts separated by approximately 130 Km: the Western belt (WB) and the Eastern belt (EB). The geological, mineralogical and tectonic features from these belts are quite similar (Buenaventura 2002). Previous researchers concluded that emeralds in Colombia came from hydrothermal sedimentary processes without any magmatic influence, and suggested that the source of Cr, V and Be (which are important components of the beryl) was the host rock. According to their results, the process which allowed the shale to release these cations was the metasomatism (albitization and carbonization), which was resulted from the interaction between the rocks and the alkaline brines. Fractures and fault planes originated by these tectonic movements were fulfilled by enriched fluids, which they allowed emeralds and the other minerals precipitation with decreasing alkalinity and pressure (Giuliani et al. 1994). However, there were several pitfalls of conclusions drawn from previous researches. Firstly, Cr and V were widely distributed and come from mafic and ultramafic rocks, and Be was mostly found in pegmatites, finding these elements in sedimentary rocks suggest that probably the ultramafic rocks occurred not far from the deposits. Secondly, there was an inconsistency in the estimated temperatures of emeralds formation, i.e. temperature of hydrothermal sedimentary deposits was only 200° C, while laboratory analysis showed that the formation of emeralds was higher than 300° C. Therefore, there might still be an allocthonus influence on emerald formation that significantly increases the temperature. This research is going to contribute information in order to clarify these inconsistencies, We have done the O and C isotopes in calcite and S isotope in pyrite and shale from different mines along the (WB) in order to determine the main fluid source of the mineralization. Selected samples will also be analyzed with EDS, RAMAN and ICP-MS methods to obtain the exact compositions of elements with extremely low concentrations in host rock, metazomatized host rock and mineralization (productive and not productive veins); the main purpose is to measure how strong were the fluid-rock interaction to leach elements out from the black shale. Thin sections from the altered shale and vein have been analyzed with the purpose of identify paragenesis and microstructures in the mineralization. Finally, we would like to gather the results from different sectors and compare it with the previous studies.

Identification and significance of accessory minerals from a bituminous coal

USGS Publications Warehouse

Finkelman, R.B.; Stanton, R.W.

1978-01-01

A scanning electron microscope (SEM) has been used to study the in situ accessory minerals in polished blocks and pellets of petrographically analysed samples of the Waynesburg coal (hvb). Individual grains from the low-temperature ash (LTA) of the same coal were also studied. The visual resolution of the SEM permitted the detection of submicron mineral grains, which could then be analysed by the attached energy-dispersive system. Emphasis was placed on the highly reflective grains in the carbominerite bands. Among the most abundant accessory minerals observed were rutile, zircon, and rare-earth-bearing minerals. Small (1-5 ??m) particles of what may be authigenic iron-rich chromite and a nickel silicate form rims on quartz grains. The SEM also permits the observation of grain morphology and mineral intergrowths. These data are useful in determining authigenicity and diagenic alteration. Substances in density splits of LTA include authigenic, detrital, extraterrestrial magnetite, tourmaline, and evaporite (?) minerals, and a fluorine-bearing amphibole. This analytical approach allows the determination of specific sites for many of the trace elements in coals. In the Waynesburg coal, most of the chromium is in the iron-chromium rims, the fluorine is in the amphibole, and the rare-earth elements are in rare-earth-bearing minerals. The ability to relate trace-element data to specific minerals will aid in predicting the behaviour of elements in coal during combustion, liquefaction, gasification, weathering, and leaching processes. This ability also permits insight into the degree of mobility of these elements in coal and provides clues to sedimentological and diagenetic conditions. ?? 1978.

Acid leaching of natural chrysotile asbestos to mesoporous silica fibers

NASA Astrophysics Data System (ADS)

Maletaškić, Jelena; Stanković, Nadežda; Daneu, Nina; Babić, Biljana; Stoiljković, Milovan; Yoshida, Katsumi; Matović, Branko

2018-04-01

Nanofibrous silica with a high surface area was produced from chrysotile by the acid-leaching method. Natural mineral chrysotile asbestos from Stragari, Korlace in Serbia was used as the starting material. The fibers were modified by chemical treatment with 1 M HCl and the mineral dissolution was monitored by transmission electron microscopy, X-ray powder diffraction, inductively coupled plasma spectrometry and low-temperature nitrogen adsorption techniques to highlight the effects of the leaching process. The results showed that the applied concentration of acid solution and processing time of 4 h were sufficient to effectively remove the magnesium hydroxide layer and transform the crystal structure of the hazardous starting chrysotile to porous SiO2 nanofibers. With prolonged acid leaching, the specific surface area, S BET, calculated by BET equation, was increased from 147 up to 435 m2 g- 1, with micropores representing a significant part of the specific surface.

Development of Detonation Flame Sprayed Cu-Base Coatings Containing Large Ceramic Particles

NASA Astrophysics Data System (ADS)

Tillmann, Wolfgang; Vogli, Evelina; Nebel, Jan

2007-12-01

Metal-matrix composites (MMCs) containing large ceramic particles as superabrasives are typically used for grinding stone, minerals, and concrete. Sintering and brazing are the key manufacturing technologies for grinding tool production. However, restricted geometry flexibility and the absence of repair possibilities for damaged tool surfaces, as well as difficulties of controlling material interfaces, are the main weaknesses of these production processes. Thermal spraying offers the possibility to avoid these restrictions. The research for this paper investigated a fabrication method based on the use of detonation flame spraying technology to bond large superabrasive particles (150-600 μm, needed for grinding minerals and stones) in a metallic matrix. Layer morphology and bonding quality are evaluated with respect to superabrasive material, geometry, spraying, and powder-injection parameters. The influence of process temperature and the possibilities of thermal treatment of MMC layers are analyzed.

Spectroscopy of Minerals Analogs of Mercury Under the Hermean Conditions: The Effect of the Temperature

NASA Astrophysics Data System (ADS)

Bott, N.; Brunetto, R.; Carli, C.; Capaccioni, F.; Doressoundiram, A.; Langevin, Y.; Perna, D.; Poulet, F.; Serventi, G.; Sgavetti, M.; Borondics, F.; Sandt, C.

2018-05-01

We present a preliminary study of the effects of the strong variations of temperature on minerals of the surface of Mercury. We measured a loose powder (75-100 μm) of plagioclase and 5 mm diameter pellets made with the same powder.

A compilation of rate parameters of water-mineral interaction kinetics for application to geochemical modeling

USGS Publications Warehouse

Palandri, James L.; Kharaka, Yousif K.

2004-01-01

Geochemical reaction path modeling is useful for rapidly assessing the extent of water-aqueous-gas interactions both in natural systems and in industrial processes. Modeling of some systems, such as those at low temperature with relatively high hydrologic flow rates, or those perturbed by the subsurface injection of industrial waste such as CO2 or H2S, must account for the relatively slow kinetics of mineral-gas-water interactions. We have therefore compiled parameters conforming to a general Arrhenius-type rate equation, for over 70 minerals, including phases from all the major classes of silicates, most carbonates, and many other non-silicates. The compiled dissolution rate constants range from -0.21 log moles m-2 s-1 for halite, to -17.44 log moles m-2 s-1 for kyanite, for conditions far from equilibrium, at 25 ?C, and pH near neutral. These data have been added to a computer code that simulates an infinitely well-stirred batch reactor, allowing computation of mass transfer as a function of time. Actual equilibration rates are expected to be much slower than those predicted by the selected computer code, primarily because actual geochemical processes commonly involve flow through porous or fractured media, wherein the development of concentration gradients in the aqueous phase near mineral surfaces, which results in decreased absolute chemical affinity and slower reaction rates. Further differences between observed and computed reaction rates may occur because of variables beyond the scope of most geochemical simulators, such as variation in grain size, aquifer heterogeneity, preferred fluid flow paths, primary and secondary mineral coatings, and secondary minerals that may lead to decreased porosity and clogged pore throats.

Post-magmatic structural evolution of the Troodos Ophiolite Pillow Lavas revealed by microthermometry within vein precipitates, with application to Alpine-Mediterranean supra-subduction zone settings

NASA Astrophysics Data System (ADS)

Klöcking, M.; White, N. J.; Maclennan, J.; Fitton, J. G.

2016-12-01

The Troodos ophiolite, Cyprus, is one of the best preserved ophiolites. Based on geochemical data a supra-subduction zone (SSZ) setting was proposed. Microtextures and fluid inclusions of veins and vesicles within the Pillow Lavas record the post-magmatic structural and geochemical evolution of this SSZ beginning at 75 Ma. Three different vein types from the Upper and Lower Pillow Lavas are distinguished and imply vein precipitation under a dominant extensional regime: (1) syntaxial calcite-, quartz- and zeolite-bearing veins are interpreted as mineralized extension fractures that were pervaded by seawater. This advective fluid flow in an open system changed later into a closed system characterized by geochemical self-organization. (2) Blocky and (3) antitaxial fibrous calcite veins are associated with brecciation due to hydrofracturing and diffusion-crystallization processes, respectively. Based on aqueous fluid inclusion chemistry with seawater salinities in all studied vein types, representative fluid inclusion isochores crossed with calculated litho- and hydrostatic pressure conditions yield mineral precipitation temperatures between 180 and 210 °C, for veins and vesicles hosted in the Upper and Lower Pillow Lavas. This points to a heat source for the circulating seawater and implies that vein and vesicle minerals precipitated shortly after pillow lava crystallization under dominant isobaric cooling conditions. Compared to previous suggestions derived from secondary mineralization a less steep geothermal gradient of 200 °C from the Sheeted Dyke Complex to the Pillow Lavas of the Troodos SSZ is proposed. Further fossil and recent SSZ like the Mirdita ophiolite, Albania, the South-Anatolian ophiolites, Turkey, and the Izu-Bonin fore arc, respectively, reveal similar volcanic sequences. Vein samples recovered during International Ocean Discovery Program expedition 351 and 352 in the Izu-Bonin back and fore arc, respectively, indicate also seawater infiltration into fractures but low-temperature (<150 °C) mineral precipitation. This comparison of spatially and temporally unrelated vein systems contributes to the understanding of post-magmatic structural and geochemical processes in SSZ. This study was granted by the Austrian Science Fund (FWF-P 27982-N29).

Post-magmatic structural evolution of the Troodos Ophiolite Pillow Lavas revealed by microthermometry within vein precipitates, with application to Alpine-Mediterranean supra-subduction zone settings

NASA Astrophysics Data System (ADS)

Kurz, W.; Quandt, D.; Micheuz, P.; Krenn, K.

2017-12-01

The Troodos ophiolite, Cyprus, is one of the best preserved ophiolites. Based on geochemical data a supra-subduction zone (SSZ) setting was proposed. Microtextures and fluid inclusions of veins and vesicles within the Pillow Lavas record the post-magmatic structural and geochemical evolution of this SSZ beginning at 75 Ma. Three different vein types from the Upper and Lower Pillow Lavas are distinguished and imply vein precipitation under a dominant extensional regime: (1) syntaxial calcite-, quartz- and zeolite-bearing veins are interpreted as mineralized extension fractures that were pervaded by seawater. This advective fluid flow in an open system changed later into a closed system characterized by geochemical self-organization. (2) Blocky and (3) antitaxial fibrous calcite veins are associated with brecciation due to hydrofracturing and diffusion-crystallization processes, respectively. Based on aqueous fluid inclusion chemistry with seawater salinities in all studied vein types, representative fluid inclusion isochores crossed with calculated litho- and hydrostatic pressure conditions yield mineral precipitation temperatures between 180 and 210 °C, for veins and vesicles hosted in the Upper and Lower Pillow Lavas. This points to a heat source for the circulating seawater and implies that vein and vesicle minerals precipitated shortly after pillow lava crystallization under dominant isobaric cooling conditions. Compared to previous suggestions derived from secondary mineralization a less steep geothermal gradient of 200 °C from the Sheeted Dyke Complex to the Pillow Lavas of the Troodos SSZ is proposed. Further fossil and recent SSZ like the Mirdita ophiolite, Albania, the South-Anatolian ophiolites, Turkey, and the Izu-Bonin fore arc, respectively, reveal similar volcanic sequences. Vein samples recovered during International Ocean Discovery Program expedition 351 and 352 in the Izu-Bonin back and fore arc, respectively, indicate also seawater infiltration into fractures but low-temperature (<150 °C) mineral precipitation. This comparison of spatially and temporally unrelated vein systems contributes to the understanding of post-magmatic structural and geochemical processes in SSZ. This study was granted by the Austrian Science Fund (FWF-P 27982-N29).

Up-scaling mineral-aqueous interfacial processes that govern isotope and trace element partitioning during calcite growth

NASA Astrophysics Data System (ADS)

Lammers, L. N.

2014-12-01

The dependence of the isotopic and trace element composition of calcium carbonate minerals on growth conditions including temperature, pH, and salinity is widely used to infer paleoclimate conditions. These inferences rely heavily on phenomenological observations of biogenic and inorganic precipitation both in and ex situ, where only limited variability in solution conditions can be explored. Ionic fluxes between the mineral surface and aqueous growth solution govern the net uptake of both stoichiometric and trace species during calcification, so developing a mechanistic understanding of the reactions governing these fluxes is critical to refine existing proxies and to develop new ones. The micro-scale mechanisms of calcite precipitation from aqueous solution have been extensively studied, and net ionic uptake post-nucleation is known to occur primarily at monomolecular kink sites along step edges at the mineral surface. In this talk, I will present a theoretical framework that uses the quasi-elementary ion attachment and detachment reactions governing ion uptake at kink sites to simultaneously model bulk mineral growth kinetics and tracer partitioning during calcite precipitation. Several distinct processes occur during ion uptake at kink sites that can influence the distribution of trace species, directly impacting the composition of various carbonate paleoproxies including δ44Ca, δ18O, Sr/Ca and Mg/Ca. The distribution of these trace species will be shown to depend on (1) the relative rates of ion desolvation during attachment to kink sites, (2) the relative rates of bond breaking during detachment from kink sites, and (3) the equilibrium partitioning of trace aqueous species. This model accounts for the impact of solution conditions on net ion fluxes and surface speciation, which in turn controls the population of kink sites available for direct ion exchange with the aqueous phase. The impacts of solution variables including pH, temperature and salinity can be treated independently, which unlike traditional partitioning studies allows the impacts of these parameters to be deconvolved. The type of theoretical framework discussed here can be readily extended to explicitly account for each of the major solution composition variables that are implicated in paleoproxy composition.

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

NASA Astrophysics Data System (ADS)

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; Sullivan, R. C.; Petters, M. D.; Tobo, Y.; Niemand, M.; Möhler, O.; Snider, J. R.; Wang, Z.; Kreidenweis, S. M.

2014-06-01

Data from both laboratory studies and atmospheric measurements are used to develop a simple parametric description for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken to approximate the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A correction factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this correction factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization to the immersion freezing surface active site density parameterization for mineral dust particles, developed separately from AIDA experimental data alone, shows excellent agreement for data collected in a descent through a Saharan aerosol layer. These studies support the utility of laboratory measurements to obtain atmospherically-relevant data on the ice nucleation properties of dust and other particle types, and suggest the suitability of considering all mineral dust as a single type of ice nucleating particle as a useful first order approximation in numerical modeling investigations.

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

NASA Astrophysics Data System (ADS)

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; Sullivan, R. C.; Petters, M. D.; Tobo, Y.; Niemand, M.; Möhler, O.; Snider, J. R.; Wang, Z.; Kreidenweis, S. M.

2015-01-01

Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken as a measure of the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A calibration factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this calibration factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization, including calibration correction, to predictions of the immersion freezing surface active site density parameterization for mineral dust particles, developed separately from AIDA experimental data alone, shows excellent agreement for data collected in a descent through a Saharan aerosol layer. These studies support the utility of laboratory measurements to obtain atmospherically relevant data on the ice nucleation properties of dust and other particle types, and suggest the suitability of considering all mineral dust as a single type of ice nucleating particle as a useful first-order approximation in numerical modeling investigations.

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

DOE PAGES

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; ...

2014-06-27

Data from both laboratory studies and atmospheric measurements are used to develop a simple parametric description for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RH w) are taken to approximate the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterizationmore » developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A correction factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RH w of 105% vs. maximum fractions active at higher RH w. Instrumental factors that affect activation behavior vs. RH w in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this correction factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization to the immersion freezing surface active site density parameterization for mineral dust particles, developed separately from AIDA experimental data alone, shows excellent agreement for data collected in a descent through a Saharan aerosol layer. These studies support the utility of laboratory measurements to obtain atmospherically-relevant data on the ice nucleation properties of dust and other particle types, and suggest the suitability of considering all mineral dust as a single type of ice nucleating particle as a useful first order approximation in numerical modeling investigations.« less

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

DOE PAGES

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; ...

2015-01-13

Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RH w) are taken as a measure of the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. Themore » parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A calibration factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RH w of 105% vs. maximum fractions active at higher RH w. Instrumental factors that affect activation behavior vs. RH w in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this calibration factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization, including calibration correction, to predictions of the immersion freezing surface active site density parameterization for mineral dust particles, developed separately from AIDA experimental data alone, shows excellent agreement for data collected in a descent through a Saharan aerosol layer. These studies support the utility of laboratory measurements to obtain atmospherically relevant data on the ice nucleation properties of dust and other particle types, and suggest the suitability of considering all mineral dust as a single type of ice nucleating particle as a useful first-order approximation in numerical modeling investigations.« less

Effects of a clearcut on the net rates of nitrification and N mineralization in a northern hardwood forest, Catskill Mountains, New York, USA

USGS Publications Warehouse

Burns, Douglas A.; Murdoch, Peter S.

2005-01-01

The Catskill Mountains of southeastern New York receive among the highest rates of atmospheric nitrogen (N) deposition in eastern North America, and ecosystems in the region may be sensitive to human disturbances that affect the N cycle. We studied the effects of a clearcut in a northern hardwood forest within a 24-ha Catskill watershed on the net rates of N mineralization and nitrification in soil plots during 6 years (1994-1999) that encompassed 3-year pre- and post-harvesting periods. Despite stream NO3- concentrations that increased by more than 1400 ??mol l-1 within 5 months after the clearcut, and three measures of NO3- availability in soil that increased 6- to 8-fold during the 1st year after harvest, the net rates of N mineralization and nitrification as measured by in situ incubation in the soil remained unchanged. The net N-mineralization rate in O-horizon soil was 1- 2 mg N kg-1 day-1 and the net nitrification rate was about 1 mg N kg-1 day-1, and rates in B-horizon soil were only one-fifth to one-tenth those of the O-horizon. These rates were obtained in single 625 m2 plots in the clearcut watershed and reference area, and were confirmed by rate measurements at 6 plots in 1999 that showed little difference in N-mineralization and nitrification rates between the treatment and reference areas. Soil temperature increased 1 ?? 0.8??C in a clearcut study plot relative to a reference plot during the post-harvest period, and soil moisture in the clearcut plot was indistinguishable from that in the reference plot. These results are contrary to the initial hypothesis that the clearcut would cause net rates of these N-cycling processes to increase sharply. The in situ incubation method used in this study isolated the samples from ambient roots and thereby prevented plant N uptake; therefore, the increases in stream NO3- concentrations and export following harvest largely reflect diminished uptake. Changes in temperature and moisture after the clearcut were insufficient to measurably affect the net rates of N mineralization and nitrification in the absence of plant uptake. Soil acidification resulting from the harvest may have acted in part to inhibit the rates of these processes. ?? Springer 2005.

Assessment of the geoavailability of trace elements from selected zinc minerals

USGS Publications Warehouse

Driscoll, Rhonda L.; Hageman, Phillip L.; Benzel, William M.; Diehl, Sharon F.; Morman, Suzette; Choate, LaDonna M.; Lowers, Heather

2014-01-01

This assessment focused on five zinc-bearing minerals. The minerals were subjected to a number of analyses including quantitative X-ray diffraction, optical microscopy, leaching tests, and bioaccessibility and toxicity studies. Like a previous comprehensive assessment of five copper-bearing minerals, the purpose of this assessment was to obtain structural and chemical information and to characterize the reactivity of each mineral to various simulated environmental and biological conditions. As in the copper minerals study, analyses were conducted consistent with widely accepted methods. Unless otherwise noted, analytical methods used for this study were identical to those described in the investigation of copper-bearing minerals. Two sphalerite specimens were included in the zinc-minerals set. One sphalerite was recovered from a mine in Balmat, New York; the second came from a mine in Creede, Colorado. The location and conditions of origin are significant because, as analyses confirmed, the two sphalerite specimens are quite different. For example, data acquired from a simulated gastric fluid (SGF) study indicate that the hydrothermally formed Creede sphalerite contains orders of magnitude higher arsenic, cadmium, manganese, and lead than the much older metamorphic Balmat sphalerite. The SGF and other experimental results contained in this report suggest that crystallizing conditions such as temperature, pressure, fluidization, or alteration processes significantly affect mineral properties—properties that, in turn, influence reactivity, solubility, and toxicity. The three remaining minerals analyzed for this report—smithsonite, hemimorphite, and hydrozincite—are all secondary minerals or alteration products of zinc-ore deposits. In addition, all share physical characteristics such as tenacity, density, streak, and cleavage. Similarities end there. The chemical composition, unit-cell parameters, acid-neutralizing potential, and other observable and quantifiable properties indicate very different minerals. Only one of each of these minerals was studied. Had this assessment included multiples of these minerals, geochemical and mineralogical distinctions would have emerged, similar to the results for the two sphalerite specimens.

Bioaccessibility of Ca, Cu, Fe, Mg, Zn, and crude protein in beef, pork and chicken after thermal processing.

PubMed

Menezes, Eveline A; Oliveira, Aline F; França, Celia J; Souza, Gilberto B; Nogueira, Ana Rita A

2018-02-01

The bioaccessibility of Ca, Cu, Fe, Mg, Zn, and crude protein was evaluated after submitting beef, pork, and chicken to five different thermal treatments. The bioaccessibility of crude protein and metals were simulated by using in vitro enzymatic digestion with a gastric fluid solution and dialysability approach. Inductively coupled plasma optical spectrometry was used to quantify the dialyzable fraction and the total mineral content after microwave-assisted digestion. Graphite furnace atomic absorption spectrometry quantified Cu in chicken dialyzable fraction. The increase of temperature and heat exposure period decreased the protein bioaccessibility. Considering the total and dialyzable fraction, beef is an important source of Cu, Fe, Mg, and Zn to the human diet. The results of Fourier-transform infrared spectroscopy indicated physical changes in the treated samples related to protein denaturation, which was probably responsible for the decreased bioaccessibility of minerals and protein, mainly at higher temperatures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Koster van Groos, A F

NASA Astrophysics Data System (ADS)

Guggenheim, S.

2008-12-01

The deep-ocean environment, including the ocean floor and crust, represents one of the last scientific frontiers on earth. The surprising lack of information on the mineralogy, the geochemical processes, or the biota of the ocean floor is the result of the inability to simulate ocean-floor conditions and to study geochemical systems at these conditions. A proto-type high-pressure environmental chamber (HPEC) has been constructed for use on a transmission- mode X-ray diffractometer to study geochemical processes at the deep-ocean sediment cover and crust. The HPEC has a designed pressure range to 1000 bars and temperature range from -20 oC to 200 oC. In this chamber, a liquid (e.g., sea water) plus sample in suspension can be pressurized either by gas or liquid. A cell-pump system continuously agitates the liquid to keep particles in suspension, thereby allowing the examination of mineral phases, including clays minerals. A major feature of the HPEC is that the mineral component moves freely and can react with its environment while being illuminated by the X-ray beam. The cell-pump also allows applied gas, such as CH4 or CO2, or O2, to interact efficiently with the aqueous liquid so that the system may rapidly reach equilibrium. In addition, mixing these gases with inert gases, e.g. He or Ar, allows control of the fugacity of these gas components. The design components and how data are manipulated to remove X-ray dispersion effects caused by the liquid will be discussed, along with examples showing the effects of temperature, pressure, and salt content on smectite clay.

Process for the preparation of methane and/or ethane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagstaff, N.

1981-09-22

According to Shell, methane and ethane can be produced from a C/sub 2/-C/sub 4/ paraffin feed stream (such as the by-product of mineral-oil production) by contacting the stream with certain crystalline silicates at temperatures of 800/sup 0/-1200/sup 0/F and 145 psi pressure. The crystalline silicates must be specially prepared to obtain the required characteristics.

Epigenetic formation of amethyst-bearing geodes from Los Catalanes gemological district, Artigas, Uruguay, southern Paraná Magmatic Province

NASA Astrophysics Data System (ADS)

Duarte, L. C.; Hartmann, L. A.; Vasconcellos, M. A. Z.; Medeiros, J. T. N.; Theye, T.

2009-07-01

Giant geodes (up to 4 m long) in the massive central portions of altered basalt lavas from the Paraná Magmatic Province, southern Brazil and Uruguay, form a world-class source of amethyst and agate. Although the origin of the cavities has been ascribed to degassing of the lava at > 1150 °C, field evidence is conclusive that the giant amethyst-agate-filled geodes were formed by hydrothermal processes at low temperatures. We propose an epigenetic and hydrothermal model for the origin of giant geodes. This model includes hydrothermal brecciation during an early brittle stage and the late formation of the cavities (geodes). In the brittle stage an overpressured aqueous fluid affected the basalt in a P, T field delimited by temperatures between 100 and 150 °C and vapor pressures between 1.2 and 5.5 bar. The fluids were capable of lifting the roof and fracturing the host rock along new subhorizontal and subvertical fractures and breccias in the massive lava. The formation of these structures occurred at shallow depths, unit-by-unit. To open the cavities, dissolution of the now altered basalt to clay minerals is necessary. The process is closely linked to the highest alteration grade of mineralized lavas in Los Catalanes gemological district. Dissolution processes are observed in micrometer-scale in the studied basalts. The primary mineralogy, consisting of labradorite (± andesine) +augite + pigeonite + mesostasis (K-rich), was altered during the interaction of large volumes of hot aqueous fluid with the rock. The alteration of pigeonite and its replacement by smectite is observed around the cavities, followed by the precipitation of amorphous silica and microcrystalline quartz in clay-rich sites. Associated zeolites (heulandite + clinoptilolite) fill the newly formed cavities in progressive stages of hydrothermal alteration. Our data indicate that the temperatures were less than 200 °C and probably less than 150 °C; cavity formation occurred after alteration of the basalt to more than 60 vol.% clay minerals. We thus suggest that cavities related to geode formation are of epigenetic origin.

Modification of the magnetic mineralogy in basalts due to fluid-rock interactions in a high-temperature geothermal system (Krafla, Iceland)

NASA Astrophysics Data System (ADS)

Oliva-Urcia, Belén; Kontny, Agnes; Vahle, Carsten; Schleicher, Anja M.

2011-07-01

Active high-temperature (>150 °C) geothermal areas like the Krafla caldera, NE-Iceland, often show distinct magnetic lows in aeromagnetic anomaly maps suggesting a destruction of magnetic minerals by hydrothermal activity. The main alteration processes in such an environment are low-temperature oxidation (<350 °C, maghemitization) and fluid-rock interactions. We investigated the rock magnetic properties [natural remanent magnetization (NRM) magnetic susceptibility and their temperature and field variation] and the mineralogy, using X-ray diffraction, microscopic methods and electron microprobe analyses, of two drill cores (KH1 and KH3) from the rim of the Krafla caldera. The drill cores have distinctly lower NRM values (average <3 A m-1) compared to younger surface basalts (average 20 A m-1) along with a large variation in magnetic susceptibility (1.3 × 10-7- 4.9 × 10-5 m3 kg-1). The secondary mineral assemblage (sulphides, sphene, rutile and chlorite) indicates an alteration within the chlorite-smectite zone for both cores without depth zoning. Optical miscroscopy in combination with the Bitter technique and backscatter electron microscopy along with the thermomagnetic analyses allow distinguishing two different magnetomineralogical groups of titanomaghemite: (1) titanomaghemite with intermediate titanium concentration and probably high vacancy concentration, and (2) titanomaghemite with low titanium concentration and low vacancy concentration. The mineral assemblages, textures and magnetic properties deduced from the mentioned magnetic measurements indicate two-stage transformation mechanism: (1) Dissolution of titanium at low pH under oxidizing conditions. The ulvöspinel component of titanomagnetite and ilmenite forms rutile or sphene, and Fe2 + migrates out of the spinel lattice forming titanomaghemite. (2) Formation of pyrite and dissolution of remaining titanomaghemite under reducing and acidic conditions. The latter mechanism produces ghost textures (all titanomaghemite is transformed and only their former grain shapes are preserved), with only paramagnetic minerals left and ferrimagnetic minerals nearly dissolved. This mechanism could explain the significant magnetization loss, which is seen in many local magnetic anomaly lows within the oceanic crust and volcanic islands like Iceland or Hawaii. The production of nanoporous textures in titanomaghemites is suggested as a mechanism for the enhancement of the magnetic susceptibility values related to the hydrothermal alteration of Krafla.

Incineration, pyrolysis and gasification of electronic waste

NASA Astrophysics Data System (ADS)

Gurgul, Agnieszka; Szczepaniak, Włodzimierz; Zabłocka-Malicka, Monika

2017-11-01

Three high temperature processes of the electronic waste processing: smelting/incineration, pyrolysis and gasification were shortly discussed. The most distinctive feature of electronic waste is complexity of components and their integration. This type of waste consists of polymeric materials and has high content of valuable metals that could be recovered. The purpose of thermal treatment of electronic waste is elimination of plastic components (especially epoxy resins) while leaving non-volatile mineral and metallic phases in more or less original forms. Additionally, the gaseous product of the process after cleaning may be used for energy recovery or as syngas.

Remote Raman Spectroscopy of Minerals at Elevated Temperature Relevant to Venus Exploration

NASA Technical Reports Server (NTRS)

Sharma, Shiv K.; Misra, Anupam K.; Singh, Upendra N.

2008-01-01

We have used a remote time-resolved telescopic Raman system equipped with 532 nm pulsed laser excitation and a gated intensified CCD (ICCD) detector for measuring Raman spectra of a number of minerals at high temperature to 970 K. Remote Raman measurements were made with samples at 9-meter in side a high-temperature furnace by gating the ICCD detector with 2 micro-sec gate to minimize interference from blackbody emission from mineral surfaces at high temperature as well as interference from ambient light. A comparison of Raman spectra of gypsum (CaSO4.2H2O), dolomite (CaMg(CO3)2), and olivine (Mg2Fe2-xSiO4), as a function of temperature shows that the Raman lines remains sharp and well defined even in the high-temperature spectra. In the case of gypsum, Raman spectral fingerprints of CaSO4.H2O at 518 K were observed due to dehydration of gypsum. In the case of dolomite, partial mineral dissociation was observed at 973 K at ambient pressure indicating that some of the dolomite might survive on Venus surface that is at approximately 750 K and 92 atmospheric pressure. Time-resolved Raman spectra of low clino-enstatite (MgSiO3) measured at 75 mm from the sample in side the high-temperature furnace also show that the Raman lines remains sharp and well defined in the high temperature spectra. These high-temperature remote Raman spectra of minerals show that time-resolved Raman spectroscopy can be used as a potential tool for exploring Venus surface mineralogy at shorter (75 mm) and long (9 m) distances from the samples both during daytime and nighttime. The remote Raman system could also be used for measuring profiles of molecular species in the dense Venus atmosphere during descent as well as on the surface.

High-temperature carbonates in the Stillwater Complex, Montana, USA

NASA Astrophysics Data System (ADS)

Aird, H. M.; Boudreau, A. E.

2012-12-01

The processes involved in the petrogenesis of the sulphide-hosted platinum-group-element (PGE) deposits of the Stillwater Complex are controversial, with theories ranging from the purely magmatic to those involving an aqueous fluid. To further constrain these models, we have been examining the trace phase assemblages in rocks away from the ore zones. High-temperature carbonates have been observed in association with sulphide minerals below the platiniferous J-M Reef of the Stillwater Complex. The carbonate assemblage consists of dolomite with exsolved calcite and is found in contact with sulphide minerals: chalcopyrite and pyrrhotite in the Peridotite Zone; and pyrrhotite with pentlandite, pyrite and chalcopyrite in Gabbronorite I of the Lower Banded Series. The minimal silicate alteration and the lack of greenschist minerals in association with the mineral assemblage are consistent with a high-temperature origin for the carbonates. The calcite-dolomite geothermometer [1] yields a minimum formation temperature of ~900°C for the unmixed assemblages. A reaction rim surrounds the carbonate-sulphide assemblages, showing an alteration of the host orthopyroxene to a more Ca-enriched, Fe-depleted composition. This is consistent with diffusive exchange between carbonates and pyroxenes at high temperatures, mediated by an aqueous fluid. The highly variable molar MnO/FeO ratios in both the high-temperature carbonates and their associated altered pyroxene rims also imply their interaction with a fluid. The carbonate assemblages are consistent with Stillwater fluid inclusion studies [2], showing that fluids comprising coexisting Cl-rich brine and carbonic fluid were trapped in pegmatitic quartz at 700-715°C, some of which also contained "accidental" calcite inclusions. The high Cl-content of apatite [3] found below the platiniferous J-M Reef is further evidence that a Cl-rich fluid was migrating through the rocks beneath the Reef. Carbonates have been shown to be stabilized by Cl-rich fluids [4]. The association of high-temperature carbonates with sulphides beneath the J-M reef supports the hydromagmatic theory which involves a late-stage chloride-carbonate fluid percolating upwards, dissolving PGE and sulphides and redepositing them at a higher stratigraphic level. [1] Anovitz, L.M., and Essene, E.J., 1987, Phase Equilibria in the System CaCO3-MgCO3-FeCO3: Journal of Petrology, v. 28, p. 389-414. [2] Hanley, J.J., Mungall, J.E., Pettke, T., Spooner, E.T.C., and Bray, C.J., 2008, Fluid and Halide Melt Inclusions of Magmatic Origin in the Ultramafic and Lower Banded Series, Stillwater Complex, Montana, USA: Journal of Petrology, v. 49, p. 1133-1160. [3] Boudreau, A.E., and McCallum, I.S., 1989, Investigations of the Stillwater Complex: Part V. Apatites as indicators of evolving fluid composition: Contributions to Mineralogy and Petrology, v. 102, p. 138-153. [4] Newton, R.C., and Manning, C.E., 2002, Experimental determination of calcite solubility in H2O-NaCl solutions at deep crust/upper mantle pressures and temperature: implications for metasomatic processes in shear zones: American Mineralogist, v. 87, p. 1401-1409.

Influence of water on clumped-isotope bond reordering kinetics in calcite

NASA Astrophysics Data System (ADS)

Brenner, Dana C.; Passey, Benjamin H.; Stolper, Daniel A.

2018-03-01

Oxygen self-diffusion in calcite and many other minerals is considerably faster under wet conditions relative to dry conditions. Here we investigate whether this "water effect" also holds true for solid-state isotope exchange reactions that alter the abundance of carbonate groups with multiple rare isotopes ('clumped' isotope groups) via the process of solid-state bond reordering. We present clumped-isotope reordering rates for optical calcite heated under wet, high-pressure (100 MPa) conditions. We observe only modest increases in reordering rates under such conditions compared with rates for the same material reacted in dry CO2 under low-pressure conditions. Activation energies under wet, high-pressure conditions are indistinguishable from those for dry, low-pressure conditions, while rate constants are resolvably higher (up to ∼3 times) for wet, high-pressure relative to dry, low-pressure conditions in most of our interpretations of experimental results. This contrasts with the water effect for oxygen self-diffusion in calcite, which is associated with lower activation energies, and diffusion coefficients that are ≥103 times higher compared with dry (pure CO2) conditions in the temperature range of this study (385-450 °C). The water effect for clumped-isotopes leads to calculated apparent equilibrium temperatures ("blocking temperatures") for typical geological cooling rates that are only a few degrees higher than those for dry conditions, while O self-diffusion blocking temperatures in calcite grains are ∼150-200 °C lower in wet conditions compared with dry conditions. Since clumped-isotope reordering is a distributed process that occurs throughout the mineral volume, our clumped-isotope results support the suggestion of Labotka et al. (2011) that the water effect in calcite does not involve major changes in bulk (volume) diffusivity, but rather is primarily a surface phenomenon that facilitates oxygen exchange between the calcite surface and external fluids. We explore the mechanism(s) by which clumped isotope reordering rates may be modestly increased under wet, high-pressure conditions, including changes in defect concentrations in the near surface environment due to reactions at the water-mineral interface, and lattice deformation resulting from pressurization of samples.

Alteration and mineralization of an oceanic forearc and the ophiolite-ocean crust analogy

USGS Publications Warehouse

Alt, J.C.; Teagle, D.A.H.; Brewer, T.; Shanks, Wayne C.; Halliday, A.

1998-01-01

Mineralogical, chemical, and isotopic (O, C, S, and Sr) analyses were performed on minerals and bulk rocks from a forearc basement section to understand alteration processes and compare with mid-ocean ridges (MOR) and ophiolites. Ocean Drilling Program Hole 786B in the Izu-Bonin forearc penetrates 103 m of sediment and 725 m into volcanic flows, breccias, and basal dikes. The rocks comprise boninites and andesites to rhyolites. Most of the section was affected by low-temperature (<100??C) seawater alteration, with temperatures increasing downward. The rocks are partly (5-25%) altered to smectite, Fe-oxyhydroxide, calcite, and phillipsite, and exhibit gains of K, Rb, and P, loss of Ca, variable changes in Si, Na, Mg, Fe, Sr, and Y, and elevated ??18O and 87Sr/86Sr. Higher temperatures (???150??C) in the basal dikes below 750 m led to more intense alteration and formation of chlorite-smectite, corrensite, albite, K-feldspar, and quartz (??chlorite). A 5 m thick hydrothermally altered and pyritized zone at 815 m in the basal dikes reacted with mixtures of seawater and hydrothermal fluids to Mg-chlorite, albite, and pyrite, and gained Mg and S and lost Si and Ca. Focused flow of hydrothermal fluids produced sericitization halos (Na-K sericite, quartz, pyrophyllite, K-feldspar, and pyrite) along quartz veins at temperatures of 200??-250??C. High 87Sr/86Sr ratios of chloritized (???0.7055) and sericitized (???0.7065) rocks indicate involvement of seawater via mixing with hydrothermal fluids. Low ??34S of sulfide (???2 to -5.5???) and sulfate (12.5???) are consistent with input of magmatic SO2 into hydrothermal fluids and disproportionation to sulfide and sulfate. Alteration processes were generally similar to those at MORs, but the arc section is more intensively altered, in part because of the presence of abundant glassy rocks and mafic phases. The increase in alteration grade below 750 m and the mineralization in the basal dikes are analogous to changes that occur near the base of the volcanic section in MOR and the Troodos ophiolite.

Characterization and Thermodynamics Studies of Feldspar and Feldspathoid Minerals

NASA Astrophysics Data System (ADS)

Rudow, M.; Lilova, K.

2015-12-01

The application of thermal analysis and calorimetry for the studies of minerals has a history as long as the existence of the thermal methods themselves. New advanced calorimetric techniques have been developed for more accurate characterization of both bulk and nano materials thus impacting their design, processing, and applications. TG-DTA and TG-DSC are used to characterize the composition of complex minerals (e.g. [KxNa1-x(AlSi3)O8]) based on the weight changes and phase transformations observed with temperature increase. Additionally, those techniques allow to determine the quantity of the different types of water contained in natural feldspars and feldspathoids (absorbed, interlayer, structural). The results for several clays will be discussed. The geochemical properties and thermal stability of another class of minerals - aluminosilicate frameworks (alkali sodalities, natrolites, etc.) as related to high-level nuclear waste treatment facilities, radioactive waste storage and management were studied. The natural sodalite Na8[Al6Si6O24]Cl2 and similar frameworks with different anions are part of sodium-aluminosilicate (NAS) low activity radioactive waste produced during steam reforming process treatment. The enthalpies and entropies of formation and the hydration enthalpies of the above-mentioned feltspathoids are obtained and the effect of the different cations and anions on the thermodynamic stability was studied. The results will allow to predict the long term behavior of the compounds in the environment under different conditions.

Diversity of Mineralogy and Occurrences of Phyllosilicates on Mars

NASA Astrophysics Data System (ADS)

Clark, R. N.; Swayze, G. A.; Murchie, S. L.; Mustard, J. F.; Milliken, R. E.; Ehlmann, B. L.; McKeown, N. K.; Calvin, W. M.; Wray, J. J.; Bishop, J. L.

2008-12-01

Minerals and their occurrences tell us about the chemistry, pressure,and temperatures of past environments, and the possible conditions for past habitability. To date, a fair number of phyllosilicates and other minerals have been detected on Mars (e.g., Poulet et al., Nature v438,p623, 2005; Mustard et al., Nature, v454, p309, 2008; Bishop et al., Science, V321, p830, 2008, and references therein). Minerals and amorphous materials detected and mapped over large areas include kaolinite/halloysite, montmorillonite, Fe/Mg-smectite, nontronite, saponite, chlorite, opal/hydrated glass, illite, muscovite, magnesite, prehnite, olivine, high- and low-calcium pyroxene, hematite, jarosite, alunite, kieserite, gypsum, coquimbite or ferricopiapite, possible szomolnokite and others yet to be identified. Phyllosilicate minerals are generally seen associated with Noachian outcrops and are thought to result from aqueous alteration, perhaps over sustained periods. Poly- and mono-hydrated Mg-sulphates appear to have been formed after the phyllosilicates. The patterns and occurrences of minerals so far mapped do not appear to show classic hydrothermal systems as have been observed on Earth (e.g., Yellowstone, Wyoming, and Cuprite, Nevada). Prehnite, previously identified on Mars as scapolite, a low-temperature phyllosilicate commonly found in mafic volcanics on Earth, appears widespread on Mars, often in association with Fe/Mg-smectite or chlorite. Phyllosilicates are observed in local outcrops, but occur regionally, generally indicating the effects of a common alteration process during the Noachian epoch. The discovery of mineralogies indicating both acidic and alkaline environments using CRISM and OMEGA data show that conditions were locally diverse. If the environments for the regional phyllosilicate deposits are found to be hostile to past habitability, perhaps studying the smaller mineralogically diverse areas may prove more fruitful. This talk will review the minerals and their diversity, and geologic environments on Mars and how they compare to terrestrial environments.

Different origins of garnet in high pressure to ultrahigh pressure metamorphic rocks

NASA Astrophysics Data System (ADS)

Xia, Qiong-Xia; Zhou, Li-Gang

2017-09-01

Garnet in high-pressure (HP) to ultrahigh-pressure (UHP) metamorphic rocks in subduction zone commonly shows considerable zonation in major and trace elements as well as mineral inclusions, which bears information on its growth mechanism via metamorphic or peritectic reactions in coexistence with relic minerals and metamorphic fluids or anatectic melts at subduction-zone conditions. It provides an important target to retrieve physicochemical changes in subduction-zone processes, including those not only in pressure and temperature but also in the durations of metamorphism and anatexis. Garnet from different compositions of HP to UHP metamorphic rocks may show different types of major and trace element zonation, as well as mineral inclusions. Discrimination between the different origins of garnet provides important constraints on pressure and temperature and the evolution history for the HP to UHP metamorphic rocks. Magmatic garnet may occur as relics in granitic gneisses despite metamorphic modification at subduction-zone conditions, with spessartine-increasing or flat major element profiles from inner to outer core and exceptionally higher contents of trace elements than metamorphic mantle and rim. Metamorphic garnet can grow at different metamorphic stages during prograde subduction and retrograde exhumation, with spessartine-decreasing from core to rim if the intracrystalline diffusion is not too fast. The compositional profiles of metamorphic garnet in the abundances of grossular, almandine and pyrope are variable depending on the composition of host rocks and co-existing minerals. Peritectic garnet grows through peritectic reactions during partial melting of HP to UHP rocks, with the composition of major elements to be controlled by anatectic P-T conditions and the compositions of parental rocks and anatectic melts. Trace element profiles in garnet with different origins are also variable depending on the coexisting mineral assemblages, the garnet-forming reactions and the property of metamorphic fluids or anatectic melts. Mineral inclusions not only present key clues to identify the different origins of garnet, but also serve as sound candidates for the temporal constraint on garnet growth.

C-O-H-S magmatic fluid system in shrinkage bubbles of melt inclusions

NASA Astrophysics Data System (ADS)

Robidoux, P.; Frezzotti, M. L.; Hauri, E. H.; Aiuppa, A.

2016-12-01

Magmatic volatiles include multiple phases in the C-O-H-S system of shrinkage bubbles for which a conceptual model is still unclear during melt inclusion formation [1,2,3,4]. The present study aims to qualitatively explore the evolution of the volatile migration, during and after the formation of the shrinkage bubble in melt inclusions trapped by olivines from Holocene to present at San Cristóbal volcano (Nicaragua), Central American Volcanic Arc (CAVA). Combined scanning electron microscope (SEM) and Raman spectroscopy observations allow to define the mineral-fluid phases inside typical shrinkage bubbles at ambient temperature. The existence of residual liquid water is demonstrated in the shrinkage bubbles of naturally quenched melt inclusion and this water could represents the principal agent for chemical reactions with other dissolved ionic species (SO42-, CO32-, etc.) and major elements (Mg, Fe, Cu, etc.) [4,5]. With the objective of following the cooling story of the bubble-inclusion system, the new methodological approach here estimate the interval of equilibrium temperatures for each SEM-Raman identified mineral phase (carbonates, hydrous carbonates, sulfurs, sulfates, etc.). Finally, two distinct mechanisms are proposed to describe the evolution of this heterogeneous fluid system in bubble samples at San Cristóbal which imply a close re-examination for similar volcanoes in subduction zone settings: (1) bubbles are already contracted and filled by volatiles by diffusion processes from the glass and leading to a C-O-H-S fluid-glass reaction enriched in Mg-Fe-Cu elements (2) bubbles are formed by oversaturation of the volatiles from the magma which is producing an immiscible metal-rich fluid. [1]Moore et al. (2015). Am. Mineral. 100, 806-823 [2]Wallace et al. (2015). Am. Mineral. 100, 787-794 [3]Lowenstern (2015). Am. Mineral. 100, 672-673 [4]Esposito, et al. (2016). Am. Mineral. 101, 1691-1708 [5]Kamenetsky et al. (2001). Earth Planet. Sci. Lett. 184, 685-702

Stevia rebaudiana Leaves: Effect of Drying Process Temperature on Bioactive Components, Antioxidant Capacity and Natural Sweeteners.

PubMed

Lemus-Mondaca, Roberto; Ah-Hen, Kong; Vega-Gálvez, Antonio; Honores, Carolina; Moraga, Nelson O

2016-03-01

Stevia leaves are usually used in dried state and undergo the inevitable effect of drying process that changes the quality characteristics of the final product. The aim of this study was to assess temperature effect on Stevia leaves through analysis of relevant bioactive components, antioxidant capacity and content of natural sweeteners and minerals. The drying process was performed in a convective dryer at constant temperatures ranging from 30 to 80 °C. Vitamin C was determined in the leaves and as expected showed a decrease during drying proportional to temperature. Phenolics and flavonoids were also determined and were found to increase during drying below 50 °C. Antioxidant activity was determined by DPPH and ORAC assays, and the latter showed the highest value at 40 °C, with a better correlation with the phenolics and flavonoids content. The content of eight natural sweeteners found in Stevia leaves was also determined and an increase in the content of seven of the sweeteners, excluding steviol bioside, was found at drying temperature up to 50 °C. At temperatures between 60 and 80 °C the increase in sweeteners content was not significant. Stevia leaves proved to be an excellent source of antioxidants and natural sweeteners.

Temperature Oscillation Modulated Self-Assembly of Periodic Concentric Layered Magnesium Carbonate Microparticles

PubMed Central

Li, Shihong; Wang, Zheng Jim; Chang, Ting-Tung

2014-01-01

Intriguing patterns of periodic, concentric, layered, mineral microstructure are present in nature and organisms, yet they have elusive geneses. We hypothesize temperature oscillation can be an independent factor that causes the self-assembly of such patterns in mineral phases synthesized in solution. Static experiments verify that rhythmic concentric multi-layered magnesium carbonate microhemispheres can be synthesized from bicarbonate solution by temperature oscillation, without use of a chemical template, additive or gel-diffusion system. Appropriate reactant concentration and initial pH value can restrain the competitive growth of other mineral generations. Polarized light microscopy images indicate the microhemispheres are crystalline and the crystallinity increases with incubation time. The thickness of a single mineral layer of microhemisphere in microscale is precisely controlled by the waveform parameters of the temperature oscillation, while the layer number, which can reach tens to about one hundred, is constrained by the temperature oscillation period number. FT-IR spectra show that these microhemispheres synthesized under different conditions can be identified as the basic form of magnesium carbonate, hydromagnesite (Mg5(CO3)4(OH)2⋅4H2O). SEM images exhibit the characteristic microscopic texture of the alternating dark and light rings of these microhemispheres. TEM images and ED patterns suggest the nanoflakes of microhemispheres are present in polycrystalline form with some degree of oriented assembly. The temperature oscillation modulated self-assembly may offer a new mechanism to understand the formation of layered microstructure of minerals in solution, and provide a non-invasive and programmable means to synthesize hierarchically ordered materials. PMID:24520410

Mo isotope fractionation during hydrothermal evolution of porphyry Cu systems

NASA Astrophysics Data System (ADS)

Shafiei, Behnam; Shamanian, GholamHossein; Mathur, Ryan; Mirnejad, Hassan

2015-03-01

We present Mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the Kerman region, Iran. The data provide new insights into controlling processes on Mo isotope fractionation during the hydrothermal evolution of porphyry systems. The Mo isotope compositions of 27 molybdenite samples show wide variations in δ97Mo ranging from -0.37 to +0.92 ‰. The data reveal that molybdenites in the early and transitional stages of mineralization (preferentially 2H polytypes; δ97Mo mean = 0.35 ‰) have higher δ97Mo values than late stage (mainly 3R polytypes; δ97Mo mean = 0.02 ‰) molybdenites. This trend suggests that fractionation of Mo isotopes occurred in high-temperature stages of mineralization and that hydrothermal systems generally evolve towards precipitation of molybdenite with lower δ97Mo values. Taking into account the genetic models proposed for porphyry Cu deposits along with the temperature-dependent fractionation of Mo isotope ratios, it is proposed that large variations of Mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore-forming fluid phases with different density, pH, and ƒO2 properties (i.e., brine and vapor). The fractionation of Mo isotopes during fluid boiling and Rayleigh distillation processes likely dominates the Mo isotope budget of the remaining ore-forming fluids for the late stage of mineralization. The lower δ97Mo values in the late stage of mineralization can be explained by depletion of the late ore-forming hydrothermal solutions in 97Mo, as these fluids have moved to considerable distance from the source. Finally, the relationship observed between MoS2 polytypes (2H and 3R) and their Mo isotopic compositions can be explained by the molecular vibration theory, in which heavier isotopes are preferentially partitioned into denser primary 2H MoS2 crystals.

Unraveling the Alteration History of Serpentinites and Associated Ultramafic Rocks from the Kampos HPLT Subduction Complex, Syros, Greece

NASA Astrophysics Data System (ADS)

Cooperdock, E. H. G.; Stockli, D. F.

2016-12-01

Serpentinization, hydration of peridotite, has a profound effect on fundamental tectonic and petrologic processes such as deformation of the lithosphere, bulk rheology, fluid-mobile element cycling and deep earth carbon cycling. Though numerous studies have investigated the petrology, structure and geochemistry of serpentinites, the absolute chronology of serpentinization remains elusive due to a lack of accessory minerals that can be dated using established geochronological techniques. Magnetite forms as a common secondary mineral in serpentinites from the fluid-induced breakdown reaction of primary peridotite minerals. Magnetite (U-Th)/He chronometry provides the potential to directly date the cooling of exhumed ultramafic bodies and the low-temperature fluid alteration of serpentinites. We present the first application of magnetite (U-Th)/He chronometry to date stages of alteration in ultramafic rocks from the Kampos mélange belt, a high-pressure low-temperature (HP-LT) subduction complex that experienced exhumation in the Miocene on the island of Syros, Greece. Two generations of magnetite are distinguishable by grain size, magnetite trace element geochemistry and (U-Th)/He age. Large magnetite grains (mm) from a chlorite schist and a serpentinite schist have distinct geochemical signatures indicative of formation during blackwall-related fluid alteration and record Mid-Miocene exhumation-related cooling ages, similar to zircon (U-Th)/He ages from northern Syros. Smaller grains (µm) from the serpentinite schist lack blackwall-related fluid signatures and record post-exhumation mineral formation associated with widespread high-angle Pliocene normal faulting. These results reveal evidence for multiple episodes of fluid-rock alteration, which has implications for the cooling history and local geochemical exchanges of this HP-LT terrane. Given the fundamental impact of serpentinizaton on a vast array of tectonic, petrological, and geochemical processes, the ability to differentiate and date these alteration events can be used to address significant questions related to serpentinization in exhumed subduction complexes, continental margins, or obducted ophiolites.

The Hydrothermal Chemistry of Gold, Arsenic, Antimony, Mercury and Silver

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bessinger, Brad; Apps, John A.

2003-03-23

A comprehensive thermodynamic database based on the Helgeson-Kirkham-Flowers (HKF) equation of state was developed for metal complexes in hydrothermal systems. Because this equation of state has been shown to accurately predict standard partial molal thermodynamic properties of aqueous species at elevated temperatures and pressures, this study provides the necessary foundation for future exploration into transport and depositional processes in polymetallic ore deposits. The HKF equation of state parameters for gold, arsenic, antimony, mercury, and silver sulfide and hydroxide complexes were derived from experimental equilibrium constants using nonlinear regression calculations. In order to ensure that the resulting parameters were internally consistent,more » those experiments utilizing incompatible thermodynamic data were re-speciated prior to regression. Because new experimental studies were used to revise the HKF parameters for H2S0 and HS-1, those metal complexes for which HKF parameters had been previously derived were also updated. It was found that predicted thermodynamic properties of metal complexes are consistent with linear correlations between standard partial molal thermodynamic properties. This result allowed assessment of several complexes for which experimental data necessary to perform regression calculations was limited. Oxygen fugacity-temperature diagrams were calculated to illustrate how thermodynamic data improves our understanding of depositional processes. Predicted thermodynamic properties were used to investigate metal transport in Carlin-type gold deposits. Assuming a linear relationship between temperature and pressure, metals are predicted to predominantly be transported as sulfide complexes at a total aqueous sulfur concentration of 0.05 m. Also, the presence of arsenic and antimony mineral phases in the deposits are shown to restrict mineralization within a limited range of chemical conditions. Finally, at a lesser aqueous sulfur concentration of 0.01 m, host rock sulfidation can explain the origin of arsenic and antimony minerals within the paragenetic sequence.« less

High-resolution chemical composition of geothermal scalings from Hungary: Preliminary results

NASA Astrophysics Data System (ADS)

Boch, Ronny; Dietzel, Martin; Deák, József; Leis, Albrecht; Mindszenty, Andrea; Demeny, Attila

2015-04-01

Geothermal fluids originating from several hundreds to thousands meters depth mostly hold a high potential for secondary mineral precipitation (scaling) due to high total dissolved solid contents at elevated temperature and pressure conditions. The precipitation of e.g. carbonates, sulfates, sulfides, and silica has shown to cause severe problems in geothermal heat and electric power production, when clogging of drill-holes, downhole pumps, pipes and heat exchangers occurs (e.g. deep geothermal doublet systems). Ongoing scaling reduces the efficiency in energy extraction and might even question the abandonment of installations in worst cases. In an attempt to study scaling processes both temporally and spatially we collected mineral precipitates from selected sites in Hungary (Bükfürdo, Szechenyi, Szentes, Igal, Hajduszoboszlo). The samples of up to 8 cm thickness were recovered from different positions of the geothermal systems and precipitated from waters of various temperatures (40-120 °C) and variable overall chemical composition. Most of these scalings show fine lamination patterns representing mineral deposition from weeks up to 45 years at our study sites. Solid-fluid interaction over time captured in the samples are investigated applying high-resolution analytical techniques such as laser-ablation mass-spectrometry and electron microprobe, micromill-sampling for stable isotope analysis, and micro-XRD combined with hydrogeochemical modeling. A detailed investigation of the processes determining the formation and growth of precipitates can help to elucidate the short-term versus long-term geothermal performance with regard to anthropogenic and natural reservoir and production dynamics. Changes in fluid chemistry, temperature, pressure, pH, degassing rate (CO2) and flow rate are reflected by the mineralogical, chemical and isotopic composition of the precipitates. Consequently, this high-resolution approach is intended as a contribution to decipher the environmental conditions during the formation of the investigated scalings and to increase our knowledge on retarding and preventive measures of scaling for geothermal applications.

Mineralized breccia clasts: a window into hidden porphyry-type mineralization underlying the epithermal polymetallic deposit of Cerro de Pasco (Peru)

NASA Astrophysics Data System (ADS)

Rottier, Bertrand; Kouzmanov, Kalin; Casanova, Vincent; Bouvier, Anne-Sophie; Baumgartner, Lukas P.; Wälle, Markus; Fontboté, Lluís

2018-01-01

Cerro de Pasco (Peru) is known for its large epithermal polymetallic (Zn-Pb-Ag-Cu-Bi) mineralization emplaced at shallow level, a few hundred meters below the paleo-surface, at the border of a large diatreme-dome complex. Porphyry-style veins crosscutting hornfels and magmatic rock clasts are found in the diatreme breccia and in quartz-monzonite porphyry dikes. Such mineralized veins in clasts allow investigation of high-temperature porphyry-style mineralization developed in the deep portions of magmatic-hydrothermal systems. Quartz in porphyry-style veins contains silicate melt inclusions as well as fluid and solid mineral inclusions. Two types of high-temperature (> 600 °C) quartz-molybdenite-(chalcopyrite)-(pyrite) veins are found in the clasts. Early, thin (1-2 mm), and sinuous HT1 veins are crosscut by slightly thicker (up to 2 cm) and more regular HT2 veins. The HT1 vein quartz hosts CO2- and sulfur-rich high-density vapor inclusions. Two subtypes of the HT1 veins have been defined, based on the nature of mineral inclusions hosted in quartz: (i) HT1bt veins with inclusions of K-feldspar, biotite, rutile, and minor titanite and (ii) HT1px veins with inclusions of actinolite, augite, titanite, apatite, and minor rutile. Using an emplacement depth of the veins of between 2 and 3 km (500 to 800 bar), derived from the diatreme breccia architecture and the supposed erosion preceding the diatreme formation, multiple mineral thermobarometers are applied. The data indicate that HT1 veins were formed at temperatures > 700 °C. HT2 veins host assemblages of polyphase brine inclusions, generally coexisting with low-density vapor-rich inclusions, trapped at temperatures around 600 °C. Rhyolitic silicate melt inclusions found in both HT1 and HT2 veins represent melt droplets transported by the ascending hydrothermal fluids. LA-ICP-MS analyses reveal a chemical evolution coherent with the crystallization of an evolved rhyolitic melt. Quartz from both HT1 and HT2 veins also contains secondary, low-temperature ( 300 °C) brine and aqueous fluid inclusions that record the cooling of the system. Both vein types are locally crosscut and/or reopened by a pre-diatreme polymetallic event consisting of pyrite, sphalerite with "chalcopyrite disease," galena, chalcopyrite, tetrahedrite-tennantite, and minor quartz. LA-ICP-MS analyses of mineral and high-temperature fluid inclusions hosted in HT1 and HT2 veins and in situ secondary-ion mass spectrometry oxygen isotope analyses of vein quartz indicate a magmatic signature for the mineralizing fluids with no major meteoric water input and allow reconstruction of the source and chemical evolution of fluids that formed these porphyry-style veins as snapshots of the early and deep mineralizations at Cerro de Pasco. This detailed study of the porphyry-type mineralization hosted in clasts offers a unique opportunity to reconstruct the late magmatic and early hydrothermal evolutions of porphyry mineralization underlying the world-class Cerro de Pasco epithermal polymetallic (Zn-Pb-Ag-Cu-Bi) deposit.

The Crystal-Chemical Effect of REE Separation in Minerals: Causes and Practical Values

NASA Astrophysics Data System (ADS)

Vinokurov, S. F.

2018-03-01

Contrast variations in the type of REE distribution from a distinctly negative mode to a positive mode is revealed in zonal fluorites of Eastern Transbaikal, with a pronounced decrease in the Ce/Y ratios in successive zones of increasing Y accompanied by a gradual decrease in the temperature and salinity of fluid inclusions in the fluorites. It is assumed that these facts are caused by the appearance of nm-size phases of REE minerals characterized by various crystalline structures and demonstrating selective concentrations of lanthanides, i.e., exhibiting a crystal-chemical differentiation of REEs that is widespread in the processes of mineral formation. Based on this natural mechanism, the development of a procedure of selective REE extraction from the concentrates is proposed. The primary laboratory experiments resulted in the discovery of the difference in REE concentrations in the sediment and filtrate with the separation coefficient varying by a factor of 76. The results obtained allow one to expect a true separation possibility for Nd along with the medium and heavy REEs. In view of the data obtained, the crystalline-chemical separation of REEs has some advantages compared to the processes currently used, especially extraction.

Modelling Iron-Bentonite Interactions

NASA Astrophysics Data System (ADS)

Watson, C.; Savage, D.; Benbow, S.; Wilson, J.

2009-04-01

The presence of both iron canisters and bentonitic clay in some engineered barrier system (EBS) designs for the geological disposal of high-level radioactive wastes creates the potential for chemical interactions which may impact upon the long-term performance of the clay as a barrier to radionuclide migration. Flooding of potential radionuclide sorption sites on the clay by ferrous ions and conversion of clay to non-swelling sheet silicates (e.g. berthierine) are two possible outcomes deleterious to long-term performance. Laboratory experimental studies of the corrosion of iron in clay show that corrosion product layers are generally thin (< 1 µm) with magnetite, siderite, or ‘green rust' occurring depending upon temperature and ambient partial pressure of carbon dioxide. In theory, incorporation of iron into clay alteration products could act as a ‘pump' to accelerate corrosion. However, the results of laboratory experiments to characterise the products of iron-bentonite interaction are less than unequivocal. The type and amounts of solid products appear to be strong functions of time, temperature, water/clay ratio, and clay and pore fluid compositions. For example, the products of high temperature experiments (> 250 °C) are dominated by chlorite, whereas lower temperatures produce berthierine, odinite, cronstedtite, or Fe-rich smectite. Unfortunately, the inevitable short-term nature of laboratory experimental studies introduces issues of metastability and kinetics. The sequential formation in time of minerals in natural systems often produces the formation of phases not predicted by equilibrium thermodynamics. Evidence from analogous natural systems suggests that the sequence of alteration of clay by Fe-rich fluids will proceed via an Ostwald step sequence. The computer code, QPAC, has been modified to incorporate processes of nucleation, growth, precursor cannibalisation, and Ostwald ripening to address the issues of the slow growth of bentonite alteration products. This, together with inclusion of processes of iron corrosion and diffusion, has enabled investigation of a representative model of the alteration of bentonite in a typical EBS environment. Simulations with fixed mineral surface areas show that berthierine dominates the solid product assemblage, with siderite replacing it at simulation times greater than 10 000 years. Simulations with time-dependent mineral surface areas show a sequence of solid alteration products, described by: magnetite -> cronstedtite -> berthierine -> chlorite. Using plausible estimates of mineral-fluid interfacial free energies, chlorite growth is not achieved until 5 000 years of simulation time. The results of this modelling work suggest that greater emphasis should be placed upon methods to up-scale the results of laboratory experiments to timescales of relevance to performance assessment.

Experimental observation and numerical simulation of permeability changes in dolomite at CO2 sequestration conditions

NASA Astrophysics Data System (ADS)

Tutolo, B. M.; Luhmann, A. J.; Kong, X.; Saar, M. O.; Seyfried, W. E.

2013-12-01

Injecting surface temperature CO2 into geothermally warm reservoirs for geologic storage or energy production may result in depressed temperature near the injection well and thermal gradients and mass transfer along flow paths leading away from the well. Thermal gradients are particularly important to consider in reservoirs containing carbonate minerals, which are more soluble at lower temperatures, as well as in CO2-based geothermal energy reservoirs where lowering heat exchanger rejection temperatures increases efficiency. Additionally, equilibrating a fluid with cation-donating silicates near a low-temperature injection well and transporting the fluid to higher temperature may enhance the kinetics of mineral precipitation in such a way as to overcome the activation energy required for mineral trapping of CO2. We have investigated this process by subjecting a dolomite core to a 650-hour temperature series experiment in which the fluid was saturated with CO2 at high pressure (110-126 bars) and 21°C. This fluid was recirculated through the dolomite core, increasing permeability from 10-16 to 10-15.2 m2. Subsequently, the core temperature was raised to 50° C, and permeability decreased to 10-16.2 m2 after 289 hours, due to thermally-driven CO2 exsolution. Increasing core temperature to 100°C for the final 145 hours of the experiment caused dolomite to precipitate, which, together with further CO2 exsolution, decreased permeability to 10-16.4 m2. Post-experiment x-ray computed tomography and scanning electron microscope imagery of the dolomite core reveals abundant matrix dissolution and enlargement of flow paths at low temperatures, and subsequent filling-in of the passages at elevated temperature by dolomite. To place this experiment within the broader context of geologic CO2 sequestration, we designed and utilized a reactive transport simulator that enables dynamic calculation of CO2 equilibrium constants and fugacity and activity coefficients by incorporating mineral, fluid, and aqueous species equations of state into its structure. Phase equilibria calculations indicate that fluids traveling away from the depressed temperature zone near the injection well may exsolve and precipitate up to 200 cc CO2, 1.45 cc dolomite, and 2.3 cc calcite, per kg, but we use the reactive transport simulator to place more realistic limits on these calculations. The simulations show that thermally-induced CO2 exsolution creates velocity gradients within the modeled domain, leading to increased velocities at lower pressure due to the increasingly gas-like density of CO2. Because dolomite precipitation kinetics strongly depend on temperature, modeled dolomite precipitation effectively concentrates within high temperature regions, while calcite precipitation is predicted to occur over a broader range. Additionally, because the molar volume of dolomite is almost double that of calcite, transporting a low temperature, dolomite-saturated fluid across a thermal gradient can lead to more substantial pore space clogging. We conclude that injecting cool CO2 into geothermally warm reservoirs may substantially alter formation porosity, permeability, and injectivity, and can result in favorable conditions for permanent storage of CO2 as a solid carbonate phase.

FLUIDS, LUBRICANTS, FUELS AND RELATED MATERIALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klaus, E.E.; Fenske, M.R.; Tewksbury, E.J.

1961-01-01

Work was carried out on a continuing program to characterize the capabilities of hydraulic fluids, lubricants, and functional fluids for aeronautic and astronautic applications under extreme environmental conditions. The effects of solvent type and solvent to oil ratio on the deep dewaxing process are shown. The yield and viscosity-temperature properties of the deep dewaxed oil are related to the type and degree of refining of the mineral oil fraction. The preparation of large volumes of super-refined mineral oil formulations for ""mock-up'' testing is reponted. Extensive technical liaison on processing, properties, and application is discussed. Physical and chemical stability of basemore » stocks, additives, and finished hydraulic fluid and lubricant formulations after 5 to 17 years in storage is described. A sample of hydraulic fluid taken from the "Lady Be Good" B-25 Bomber after 16 years in the North African desert is discussed. The design, construction, and preliminary testing of a versatile capillary pressure viscometer is reported. The use of this viscometer to measure the effect of gas solubility on viscosity and the analysis of flow profile in a capillary viscometer are discussed. The use of the pressure unit with a modified Lipkin pycnometer for the measure of bulk modulus is suggested. The thermal stability of esters is contrasted and compared as a function of chemical structure. Quantitative evaluations of the gas produced and the liquid phase are used to illustrate the effect of metal catalysts. The effects of fluid type, viscosity, vapor pressure, oxidation mechanism, oxidation inhibitor, and gaseous environment on evaporation are presented. The use of evaporation tests in studying the mechanism of oxidation is suggested. The relative lubricity properties of a series of high-temperature-bearing materials are reported. The relative effects of fluid volatility on lubricity are discussed. The similarities between high-temperature and the lowtemperatare lubricity properties of the residual fluids after high-temperature oxidation and thermal tests are pointed out. The wear properties of mineral oils and esters with and without lubricity additives are compared and contrasted with silicons and silicate fluids at 167 to 700 deg F. A simple, versatile, quantitative oxidation test is described for use with a variety of high-temperature oxidation tests. (auth)« less

Time-Resolved Remote-Raman Spectroscopic study of Minerals at High Temperature and under Supercritical CO2 Relevant to Venus Exploration

NASA Astrophysics Data System (ADS)

Sharma, S. K.; Misra, A. K.; Clegg, S. M.; Barefield, J. E.; Wiens, R. C.; Acosta, T.

2009-12-01

We have used a remote time-resolved (TR) telescopic Raman system equipped with 532 nm pulsed laser excitation and a gated intensified CCD (ICCD) detector for measuring Raman spectra of a number of minerals under two sets of conditions. The first set of experiments involved probing samples as a function of temperature ranging from 300 to 973 K at 1 atm. These experiments involve a 5x beam expander to focus the 532 nm (30 mJ/pulse 20 Hz) laser beams onto the sample at 9 m from the remote Raman system. The second set of experiments involved placing the samples in a high pressure vessel with a sapphire window containing supercritical CO2 at pressures up to 93 atm and 423 K. At high temperatures and ambient pressure, the remote Raman measurements were made with samples at 9 meter distance inside a high temperature furnace by gating the ICCD detector with 2 micro-s gate to minimize interference from blackbody emission from mineral surfaces at high temperature as well as interference from ambient light. A comparison of Raman spectra of gypsum (CaSO4.2H2O), dolomite (CaMg(CO3)2), and olivine (Mg2Fe2-xSiO4), as a function of temperature shows that the Raman lines remains sharp and well defined even in the high temperature spectra. In the pressure vessel, Cr3+ fluorescence from sapphire window interfere with the Raman spectra of hydrous minerals in the high-frequency region (2500-4500 cm-1). With time-resolved Raman measurements the interference of the fluorescence in the Raman spectra on minerals was minimized by gating ICCD to <100 ns. The Fermi resonance doublet of CO2 molecules consisting of Raman lines at 1285 (2ν2) and 1388 (ν1) cm-1 does not interfere with the major Raman fingerprints of silicates, carbonate, sulfates minerals. With suitable time delay of the ICCD detector, the Raman bands from supercritical CO2 atmosphere can be minimized providing pure Raman spectra of the mineral targets. We will present remote Raman data on silicates (olivine, pyroxene, quartz, feldspars and talc), dolomite, gypsum, hydrous iron sulfate and barite under supercritical CO2 environment. With TR remote Raman system using 532 nm (15 mJ/pulse, 20Hz) laser excitation, a large varieties of minerals could be easily identified from their respective Raman fingerprints typically in 1s. Minerals with low Raman cross section (e.g., feldspars, pyroxene, olivine, talc, etc) can be detected and quantified from their respective Raman spectra in 10 to 30 s. These results show that time-resolve remote Raman system is capable of making spectral measurements at several hundred to thousand target points on Venus surface within limited (a few hours) expected lifetime of a lander because of extreme temperature and pressure conditions.

Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birkle, P.; Pruess, K.; Xu, T.

Waterflooding for enhanced oil recovery requires that injected waters must be chemically compatible with connate reservoir waters, in order to avoid mineral dissolution-and-precipitation cycles that could seriously degrade formation permeability and injectivity. Formation plugging is a concern especially in reservoirs with a large content of carbonates, such as calcite and dolomite, as such minerals typically react rapidly with an aqueous phase, and have strongly temperature-dependent solubility. Clay swelling can also pose problems. During a preliminary waterflooding pilot project, the Poza Rica-Altamira oil field, bordering the Gulf coast in the eastern part of Mexico, experienced injectivity loss after five months ofmore » reinjection of formation waters into well AF-847 in 1999. Acidizing with HCl restored injectivity. We report on laboratory experiments and reactive chemistry modeling studies that were undertaken in preparation for long-term waterflooding at Agua Frma. Using analogous core plugs obtained from the same reservoir interval, laboratory coreflood experiments were conducted to examine sensitivity of mineral dissolution and precipitation effects to water composition. Native reservoir water, chemically altered waters, and distilled water were used, and temporal changes in core permeability, mineral abundances and aqueous concentrations of solutes were monitored. The experiments were simulated with the multi-phase, nonisothermal reactive transport code TOUGHREACT, and reasonable to good agreement was obtained for changes in solute concentrations. Clay swelling caused an additional impact on permeability behavior during coreflood experiments, whereas the modeled permeability depends exclusively on chemical processes. TOUGHREACT was then used for reservoir-scale simulation of injecting ambient-temperature water (30 C, 86 F) into a reservoir with initial temperature of 80 C (176 F). Untreated native reservoir water was found to cause serious porosity and permeability reduction due to calcite precipitation, which is promoted by the retrograde solubility of this mineral. Using treated water that performed well in the laboratory flow experiments was found to avoid excessive precipitation, and allowed injection to proceed.« less

Subsolidus cooling of mid-ocean ridge peridotites and implications for the oxygen fugacity of the oceanic upper mantle

NASA Astrophysics Data System (ADS)

Birner, S.; Davis, F. A.; Cottrell, E.; Warren, J. M.; Kelley, K. A.

2017-12-01

Peridotites dredged from mid-ocean ridges provide a window into the chemistry of Earth's upper mantle. At equilibrium, mineral assemblages within peridotite record intrinsic properties, including oxygen fugacity (fO2). During cooling below the solidus, however, reactions affect the chemical compositions and modal abundances of minerals, directly affecting the fO2 recorded by these mineral assemblages. The slow kinetics of subsolidus diffusion also prevent full re-equilibration of peridotite during cooling, and different reactions have different closure temperatures. As a result, peridotites measured at the surface record neither equilibrium nor asthenospheric conditions. In order to quantify the effect of subsolidus diffusion on fO2, we analyzed minerals from abyssal peridotites dredged from the Southwest Indian Ridge (SWIR), which we then used as a basis for modeling potential subsolidus reactions. We first examined exchange reactions where no modal changes occur. We considered both Fe-Mg exchange between olivine and spinel [1] and Al-Cr exchange between orthopyroxene and spinel [2], and combined these models with spinel oxybarometry [3] to determine the effect of these reactions on fO2. Our results indicate that as peridotites cool from 1300°C to 900°C, these exchange processes together increase recorded fO2 by 0.3 log units relative to the approach in which compositional changes are not considered. Some reactions additionally change mineral modal abundances during cooling, in particular the Tschermak exchange in orthopyroxene [2], which consumes olivine and Al-rich orthopyroxene and produces spinel and Al-poor orthopyroxene as temperature decreases. Depending on partitioning of Fe3+ between phases, this reaction may dilute the concentration of Fe3+ in spinel and decrease recorded fO2 as temperature decreases. Preliminary results suggest that the magnitude of this effect is strongly sensitive to both initial spinel mode and partitioning of Fe3+ between orthopyroxene and spinel. Finally, we compare the fO2 recorded by SWIR peridotites to the fO2 recorded by basalts, projected to source conditions. [1] Li et al., 1995; [2] Voigt and von der Handt, 2011; [3] Davis et al., 2017

Nucleation and Growth Rates of Pyroxene, Plagioclase and Fe-Ti Oxides in Basalt

NASA Astrophysics Data System (ADS)

Burkhard, D. J.

2003-12-01

Rock textures and physical and chemical properties are determined by the time-temperature path of a magma, and the nucleation and growth rates (J, G) of crystallizing mineral phases. We applied the crystal size distribution theory (CSD) to derived J and G of pyroxene, plagioclase and of Fe-Ti oxides in basalt glass during heat treatment [1,2,3,4]. The glass was sampled from active Pu`u O`o, Kilauea, Hawaii, by hammer-dipping and subsequent quenching [5]. Temperature (T) and time (t) dependent heat treatment of the glass above temperature of nucleation and growth maxima, about 930° C, allows one to derive the activation energy of J and G, EJ, EG, which are at steady state after about 100 hrs, at 180/200, 353/307, 292/343 kJ/mol (EJ/EG, for pyroxene, plagioclase and Fe-Ti oxides). On a logarithmic scale, J and G are linear with t. A comparison with growth rates of lava cooled within a lava lobe, from top to bottom [6], suggests that independent of depth, all mineral phases crystallized at T < 1000° C. According to our results of t and T dependent J and G, such rock textures should first crystallize pyroxene, and intersertal plagioclase which is, indeed, observed. Slow cooling or a hold at T > 1000° C, should result in a first crystallization of plagioclase. This is reported in the literature [e.g., 7]. In agreement with this, we detected anorthite nuclei in the glass with HRTEM [8]. [1] Randolph R.D., Larson M.A (1979); Theory of particulate processes. Academic Press, New York. [2] Marsh B.D. (1988); Contrib.Mineral. Petrol. 99, 277-291. [3] Cashman K.V., Marsh (1988) Contrib. Mineral. Petrol. 99, 292-305. [4] Burkhard D.J.M. (2002); Contrib. Mineral. Petrol. 142, 724-527. [5] Burkhard D.J.M. (2001); J. Petrol. 42, 507-527. [6] Burkhard D.J.M. (2003; Bull. Volcanol. 65, 136-143. [7] Lofgren G.E 1983; J. Petrol., 24, 229-225. [8] Burkhard D.J.M., Wirth, R. (2001); EOS Trans. AGU, 82 (47), Fall Meet. Suppl., abstract V51B-1014.

Computational study of deformation mechanisms and grain size evolution in granulites - Implications for the rheology of the lower crust

NASA Astrophysics Data System (ADS)

Maierová, Petra; Lexa, Ondrej; Jeřábek, Petr; Schulmann, Karel; Franěk, Jan

2017-05-01

Most of granulite terrains worldwide are characterized by large mean grain sizes of 1 mm or more. An important exception are the high-pressure felsic granulites in the Bohemian Massif, the European Variscan belt. There, recrystallization of original coarse-grained ternary feldspar led to formation of a fine-grained (∼100 μm) mixed matrix dominated by plagioclase and K-feldspar. This change occurred at temperatures of ∼850 °C and was probably caused by chemically induced decomposition related to slight cooling and enhanced by deformation during continental collision. The resulting microstructure shows indications of diffusion creep assisted by melt-enhanced grain-boundary sliding. Further on, minor coarsening occurred associated with deformation by dislocation creep and aggregation of mineral phases. Using a thermodynamics-based model of grain size evolution we show that stability of the fine-grained microstructure crucially depends on Zener pinning in the two-phase mineral matrix. Pinning efficiently hinders grain growth, and the small grain size that resulted from the ternary feldspar decomposition can be stable even at high temperatures. The late switch from the grain-size-sensitive creep to dislocation creep is rather difficult to explain by temperature and strain rate (or stress) changes only. However, a simple incorporation of melt solidification can successfully simulate this behavior. Alternatively, the switch and the associated grain size growth can be related to mineral phase aggregation at lower pressure-temperature conditions resulting into a decrease of pinning efficiency. This study suggests that the fine grain size of the Bohemian granulites, in contrast to the common coarse-grained type, stems from abrupt recrystallization during the high-pressure high-temperature conditions, and pinning in the fine-grained matrix. Such a process may in some cases significantly and suddenly reduce the strength of the lower continental crust and allow for its efficient redistribution.

Metasomatic hydration of the Oeyama forearc peridotites: Tectonic implications

NASA Astrophysics Data System (ADS)

Nozaka, Toshio

2014-01-01

In contrast to the widely recognized aspects of serpentinization, initial stages of hydration and tectonic processes of unserpentinized peridotites are still unclear, but have important implications for understanding the lithospheric architecture of supra-subduction zones. This study provides petrological evidence from the Oeyama ophiolite, SW Japan, of the effects of high-temperature metasomatic hydration immediately before the cooling and ductile deformation of forearc peridotites. Key findings in this study are: 1) complex association of high-temperature metasomatic minerals: tremolitic amphibole, cummingtonite, phlogopite, chlorite, olivine and orthopyroxene in veins and in mylonites; 2) the systematic variation in Si and Na + K contents of the tremolitic amphibole, corresponding to its mode of occurrence and mineral association; and 3) the presence of thin (< 0.7 mm) veins of fine-grained olivine accompanied by a narrow diffusion zone of the host primary olivine. On the basis of petrography and mineral chemistry, the temporal sequence of hydration and deformation of the Oeyama ophiolite is considered as follows: 1) infiltration of slab-derived fluids, causing decomposition of primary pyroxene and chemical modification of primary olivine, 2) metasomatic formation of variable modal amounts of amphibole, phlogopite, chlorite, vein-forming olivine and secondary orthopyroxene at 650-750 °C; 3) early-stage mylonitization of the hydrous peridotites in localized shear zones; and 4) syntectonic serpentinization at 400-600 °C to form serpentinite mylonites. Paragenesis and amphibole compositions suggest comparable temperature conditions for metasomatism and early-stage mylonitization. Mylonitization occurred exclusively in hydrous peridotites, and the peridotite mylonites were preferentially overprinted by syntectonic serpentinization. Diffusion profiles of olivine cut by a vein suggest rapid cooling immediately after the metasomatic fluid infiltration. From these observations and calculations, it is concluded that the exhumation of the forearc peridotites was closely related to the infiltration of high-temperature metasomatic fluids and hydration occurred under a wide range of temperature conditions.

Incorporation of Np(V) and U(VI) in Carbonate and Sulfate Minerals Crystallized from Aqueous Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balboni, Enrica; Morrison, Jessica M.; Wang, Zheming

2015-02-15

The neptunyl Np(V)O2 + and uranyl U(VI)O2 2+ ions are soluble in groundwater, although their interaction with minerals in the subsurface may impact their mobility. One mechanism for the immobilization of actinyl ions in the subsurface is coprecipitation in low-temperature minerals that form naturally, or that are induced to form as part of a remediation strategy. Important differences in the crystal-chemical behavior of the Np(V) neptunyl and U(VI) uranyl ions suggest their behavior towards incorporation into growing crystals may differ significantly. Using a selection of low temperature minerals synthesized in aqueous systems under ambient conditions, this study examines the factorsmore » that impact the structural incorporation of the Np(V) neptunyl and U(VI) uranyl ions in carbonate and sulfate minerals.« less

Coal liquefaction process

DOEpatents

Wright, Charles H.

1986-01-01

A process for the liquefaction of coal wherein raw feed coal is dissolved in recycle solvent with a slurry containing recycle coal minerals in the presence of added hydrogen at elevated temperature and pressure. The highest boiling distillable dissolved liquid fraction is obtained from a vacuum distillation zone and is entirely recycled to extinction. Lower boiling distillable dissolved liquid is removed in vapor phase from the dissolver zone and passed without purification and essentially without reduction in pressure to a catalytic hydrogenation zone where it is converted to an essentially colorless liquid product boiling in the transportation fuel range.

Supercomputer analysis of sedimentary basins.

PubMed

Bethke, C M; Altaner, S P; Harrison, W J; Upson, C

1988-01-15

Geological processes of fluid transport and chemical reaction in sedimentary basins have formed many of the earth's energy and mineral resources. These processes can be analyzed on natural time and distance scales with the use of supercomputers. Numerical experiments are presented that give insights to the factors controlling subsurface pressures, temperatures, and reactions; the origin of ores; and the distribution and quality of hydrocarbon reservoirs. The results show that numerical analysis combined with stratigraphic, sea level, and plate tectonic histories provides a powerful tool for studying the evolution of sedimentary basins over geologic time.

Fluid evolution of Au-Cu zones in Um Balad area, North Eastern Desert of Egypt: Implications from mineral chemistry and fluid inclusions

NASA Astrophysics Data System (ADS)

Abd El Monsef, Mohamed; Salem, Ibrahim; Slobodník, Marek; Ragab, Ahmed

2018-07-01

Scanning electron microscope (SEM), Electron microprobe (EMPA) and fluid inclusion studies of the ore body, as well as geochemical analyses of country rocks were performed to determine the nature and characteristics of the mineralizing fluid responsible for Au-Cu deposits in Um Balad area, Northern Eastern Desert of Egypt. The Um Balad Au-Cu deposits are confined to well developed-quartz veins and veinlets cutting through the hosting country rocks. Petrographic and geochemical investigations of the hosting rocks distinguished between two main rock units; 1) metagabbro-diorite rocks with tholeiitic nature derived in island arc/continental margin tectonic regime, and 2) granodiorite rocks formed from calc-alkaline magma in continental margin regime. Wallrock alterations are represented by propylitic and argillic types. The mineralized quartz veins are striking in NE-SW direction and dipping between (35°-45°) in SE direction, other mineralized mafic dykes enriched with auriferous quartz veinlets are trending NE-SW and dipping 70°/SE. The main ore minerals are represented by gold, chalcopyrite, pyrite, sphalerite, malachite, covellite and goethite. While, geffroyite, cuprite, chrysocolla, pseudomalachite, britholite, wolframite, scheelite, hematite and rutile are detected as minor constituents. Fluid inclusions microthermometry and isochore calculations combined with chlorite geothermometry revealed that the Um Balad deposits were formed at temperature ranging from 305 °C to 325 °C and pressure between (100-500 bar). The mineralization had been developed in the shallow levels, beneath the water table at depth of 350-1760 m, rather than common mesothermal vein-type deposits in Egypt. Magmatic water have been suggested as the main source for the mineralized fluid. The transportation of the gold metal seems to be happen as bisulfide complexes in moderately acidic environment. The deposition was resulted from combination of changes in physico-chemical parameters, temperature and pressure plus the instability of the reduced sulfur complexes. A contamination with metamorphic and/or meteoric water was also proposed that has strong influence during the depositional process.

Temperature sensitivity of methanogenesis in a thermokarst lake sediment core

NASA Astrophysics Data System (ADS)

Heslop, J. K.; Walter Anthony, K. M.; Grosse, G.; Anthony, P.; Bondurant, A.

2016-12-01

Little is known about temperature sensitivity of permafrost organic carbon (OC) mineralization over time scales of years to centuries following thaw. Due to their formation and thaw histories, taliks (thaw bulbs) beneath thermokarst lakes provide a unique natural laboratory from which to examine how permafrost thawed in saturated anaerobic conditions responds to changes in temperature following long periods of time since thaw. We anaerobically incubated samples from a 590 cm thermokarst lake sediment core near Fairbanks, Alaska at four temperatures (0, 3, 10, and 25 ºC) bracketing observed talik temperatures. We show that since initial thaw 400 yr BP CH4 production shifts from being most sensitive to at lower (0-3 ºC; Q10-EC=1.15E7) temperatures to being most sensitive at higher (10-25 ºC; Q10-EC=67) temperatures. Frozen sediments collected from beneath the talik, thawed at the commencement of the incubation, had significant (p ≤ 0.05) increases in CH4 production rates at lower temperatures but did not show significant CH4 production rate increases at higher temperatures (10-25 ºC). We hypothesize the thawing of sediments removed a major barrier to C mineralization, leading to rapid initial permafrost C mineralization and preferential mineralization of the most biolabile OC compounds. In contrast, sediments which had been thawed beneath the lake for longer periods of time did not experience statistically significant increases in CH4 production at lower temperatures (0-10 ºC), but had high temperature sensitivities at higher temperatures (10-25 ºC). We believe these rate increases are due to warmer temperatures in the experimental incubations crossing activation energy thresholds, allowing previously recalcitrant fractions of OC to be utilized, and/or the presence of different microbial communities adapted to thawed sediments. Recently-deposited sediments at shallow depths in the lake core experienced increases in CH4 production across all incubation temperatures (Q10-ST=4.4).

METHOD OF PREPARING PLUTONIUM TETRAFLUORIDE

DOEpatents

Beede, R.L.; Hopkins, H.H. Jr.

1959-11-17

C rystalline plutonium tetrafluoride is precipitated from aqueous up to 1.6 N mineral acid solutions of a plutorium (IV) salt with fluosilicic acid anions, preferably at room temperature. Hydrogen fluoride naay be added after precipitation to convert any plutonium fluosilicate to the tetrafluoride and any silica to fluosilicic acid. This process results in a purer product, especially as to iron and aluminum, than does the precipitation by the addition of hydrogen fluoride.

An Investigation of Mineral Dynamics in Sea Ice by Solubility Measurements

NASA Astrophysics Data System (ADS)

Butler, B.; Kennedy, H.; Papadimitriou, S.

2016-02-01

Sea ice is a composite material with a sponge-like structure. The framework of the structure is composed of pure ice, and within the pores exists a concentrated seawater brine. When the temperature is reduced, the volume of this residual brine decreases, while its salinity increases. As a result of the paired changes to temperature and salinity, the brine becomes supersaturated with respect to a mineral at several points when cooling sea ice towards -30°C, creating a sequence of minerals that precipitate. The presence of countless microscopic salt crystals encapsulated within the ice, coupled with changes in brine volume associated with their precipitation/dissolution, results in changes to the optical and structural properties of the medium that contribute to the surface energy balance in sea ice environments. Furthermore, attainment of mineral equilibrium can result in abrupt changes in brine composition and osmotic conditions in the isolated brine pockets, imposing challenging conditions upon the biota that habitat the sea ice environment. Mirabilite (Na2SO4.10H2O), gypsum (CaSO4.2H2O) and hydrohalite (NaCl.2H2O) each represent minerals that are understood to exist within sea ice. Previous research has focused upon mineral extraction/detection, and the specific temperature for the onset of each minerals precipitation in sea ice; rather than the overarching dynamics. For this reason, solubility measurements of mirabilite, gypsum and hydrohalite in conditions representative of equilibrium sea ice brines were carried between 0 and -28°C, covering a range of undersaturated and supersaturated conditions for each mineral. Results provide accurate data for the onset of each minerals formation in sea ice, as well as important information on the way in which precipitation and dissolution reactions are affected when sea ice warms or cools. By incorporating the solubility data into a model that simluates the temperature-salinity profiles of first-year sea ice, the spatial and temporal distrubtion of each mineral throughout periods of ice growth and melt have been estimated for the first time. This information highlights the ubiquitous presence of minerals in the sea ice system, which have remained relatively elusive due to the nature of the complex structure and extreme environment that they exist in.

Role of mineralization inhibitors in the regulation of hard tissue biomineralization: relevance to initial enamel formation and maturation

PubMed Central

Margolis, Henry C.; Kwak, Seo-Young; Yamazaki, Hajime

2014-01-01

Vertebrate mineralized tissues, i.e., enamel, dentin, cementum, and bone, have unique hierarchical structures and chemical compositions. Although these tissues are similarly comprised of a crystalline calcium apatite mineral phase and a protein component, they differ with respect to crystal size and shape, level and distribution of trace mineral ions, the nature of the proteins present, and their relative proportions of mineral and protein components. Despite apparent differences, mineralized tissues are similarly derived by highly concerted extracellular processes involving matrix proteins, proteases, and mineral ion fluxes that collectively regulate the nucleation, growth and organization of forming mineral crystals. Nature, however, provides multiple ways to control the onset, rate, location, and organization of mineral deposits in developing mineralized tissues. Although our knowledge is quite limited in some of these areas, recent evidence suggests that hard tissue formation is, in part, controlled through the regulation of specific molecules that inhibit the mineralization process. This paper addresses the role of mineralization inhibitors in the regulation of biological mineralization with emphasis on the relevance of current findings to the process of amelogenesis. Mineralization inhibitors can also serve to maintain driving forces for calcium phosphate precipitation and prevent unwanted mineralization. Recent evidence shows that native phosphorylated amelogenins have the capacity to prevent mineralization through the stabilization of an amorphous calcium phosphate precursor phase, as observed in vitro and in developing teeth. Based on present findings, the authors propose that the transformation of initially formed amorphous mineral deposits to enamel crystals is an active process associated with the enzymatic processing of amelogenins. Such processing may serve to control both initial enamel crystal formation and subsequent maturation. PMID:25309443

Gas chemistry of Icelandic thermal fluids

NASA Astrophysics Data System (ADS)

Stefánsson, Andri

2017-10-01

The chemistry of gases in thermal fluids from Iceland was studied in order to evaluate the sources and processes affecting volatile concentrations in volcanic geothermal systems at divergent plate boundaries. The fluids included vapor fumaroles and two-phase well discharges with temperatures of 100-340 °C. The vapor was dominated by H2O accounting for 62-100 mol% and generally for > 99 mol%, with CO2, H2S and H2 being the dominant gases followed by N2, CH4, and Ar. Overall mineral-gas and gas-gas equilibria were not observed for the major gases, including CO2, H2S, H2 and CH4 within the geothermal reservoirs. Instead the system proved to be controlled by source(s) and their ratios and various metastable equilibria along a fluid-rock reaction progress with gas concentrations controlled by such metastable equilibria varying at particular temperatures as a functional extent of reaction. The concentrations of H2S and H2 closely reflect mineral-fluid metastable equilibria, whereas CO2 concentrations are controlled by the input of magma gas corresponding to > 0.1 to < 5% mass input. With fluid ascent to the surface, boiling and condensation may occur, further changing the gas concentrations and hence surface fumaroles may not reflect the reservoir fluid characteristics but rather secondary processes.

Moderate-temperature zeolitic alteration in a cooling pyroclastic deposit

USGS Publications Warehouse

Levy, S.S.; O'Neil, J.R.

1989-01-01

The locally zeolitized Topopah Spring Member of the Paintbrush Tuff (13 Myr.), Yucca Mountain, Nevada, U.S.A., is part of a thick sequence of zeolitized pyroclastic units. Most of the zeolitized units are nonwelded tuffs that were altered during low-temperature diagenesis, but the distribution and textural setting of zeolite (heulandite-clinoptilolite) and smectite in the densely welded Topopah Spring tuff suggest that these hydrous minerals formed while the tuff was still cooling after pyroclastic emplacement and welding. The hydrous minerals are concentrated within a transition zone between devitrified tuff in the central part of the unit and underlying vitrophyre. Movement of liquid and convected heat along fractures from the devitrified tuff to the ritrophyre caused local devitrification and hydrous mineral crystallization. Oxygen isotope geothermometry of cogenetic quartz confirms the nondiagenetic moderate temperature origin of the hydrous minerals at temperatures of ??? 40-100??C, assuming a meteoric water source. The Topopah Spring tuff is under consideration for emplacement of a high-level nuclear waste repository. The natural rock alteration of the cooling pyroclastic deposit may be a good natural analog for repository-induced hydrothermal alteration. As a result of repository thermal loading, temperatures in the Topopah Spring vitrophyre may rise sufficiently to duplicate the inferred temperatures of natural zeolitic alteration. Heated water moving downward from the repository into the vitrophyre may contribute to new zeolitic alteration. ?? 1989.

Using soil temperature and moisture to predict forest soil nitrogen mineralization

Treesearch

Jennifer D. Knoepp; Wayne T. Swank

2002-01-01

Due to the importance of N in forest productivity ecosystem and nutrient cycling research often includes measurement of soil N transformation rates as indices of potential availability and ecosystem losses of N. We examined the feasibility of using soil temperature and moisture content to predict soil N mineralization rates (Nmin) at the Coweeta Hydrologic Laboratory...

Transformation of corn plant residues in loamy and sandy substrates

NASA Astrophysics Data System (ADS)

Mal'tseva, A. N.; Zolotareva, B. N.; Pinskii, D. L.

2014-05-01

The mineralization and humification dynamics of corn plant residues in loamy and sandy substrates have been studied under laboratory conditions. It has been shown that the dynamics are determined by the undulating development laws of the microbial community under constant temperature and moisture conditions. At the same time, the intensity and final results of the processes significantly differ depending on the composition and properties of the mineral substrate. The loss of Corg during the mineralization and the content of newly formed humic substances reached the maximum values a month after the beginning of the experiment. The mineralization is more intensive in sand at the early stages, and the humification is more active in loam throughout the incubation period. The loamy substrate has better protective properties compared to the sand; therefore, it favors the accumulation of significant amounts of fulvic acids (FAs), along with humic acids (HAs), and causes the relative fulvatization of the humic substances. It has been found using densimetric fractionation and Fourier IR spectroscopy that the different mineralogy of the fractions results in differences in the chemical composition of the formed mineral-organic compounds of newly formed humic substances, mainly due to carboxyl and nitrogen-containing groups. The similarity of the humification products in the heavy fractions of the loamy and sandy substrates has been revealed.

Synergistic reaction between SO2 and NO2 on mineral oxides: a potential formation pathway of sulfate aerosol.

PubMed

Liu, Chang; Ma, Qingxin; Liu, Yongchun; Ma, Jinzhu; He, Hong

2012-02-07

Sulfate is one of the most important aerosols in the atmosphere. A new sulfate formation pathway via synergistic reactions between SO(2) and NO(2) on mineral oxides was proposed. The heterogeneous reactions of SO(2) and NO(2) on CaO, α-Fe(2)O(3), ZnO, MgO, α-Al(2)O(3), TiO(2), and SiO(2) were investigated by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) at ambient temperature. Formation of sulfate from adsorbed SO(2) was promoted by the coexisting NO(2), while surface N(2)O(4) was observed as the crucial oxidant for the oxidation of surface sulfite. This process was significantly promoted by the presence of O(2). The synergistic effect between SO(2) and NO(2) was not observed on other mineral particles (such as CaCO(3) and CaSO(4)) probably due to the lack of the surface reactive oxygen sites. The synergistic reaction between SO(2) and NO(2) on mineral oxides resulted in the formation of internal mixtures of sulfate, nitrate, and mineral oxides. The change of mixture state will affect the physicochemical properties of atmospheric particles and therefore further influence their environmental and climate effects.

Thermometers and thermobarometers in granitic systems

USGS Publications Warehouse

Anderson, J.L.; Barth, A.P.; Wooden, J.L.; Mazdab, F.; ,

2008-01-01

The ability to determine the thermal and barometric history during crystallization and emplacement of granitic plutons has been enhanced by several new calibrations applicable to granitic mineral assemblages. Other existing calibrations for granitic plutons have continued to be popular and fairly robust. Recent advances include the trace element thermometers Ti-in-quartz, Ti-in-zircon, and Zr-in-sphene (titanite), which need to be further evaluated on the roles of reduced activities due to lack of a saturating phase, the effect of pressure dependence (particularly for the Ti-in-zircon thermometer), and how resistive these thermometers are to subsolidus reequilibration. As zircon and sphene are also hosts to radiogenic isotopes, these minerals potentially also provide new insights into the temperature - time history of magmas. When used in conjunction with pressure-sensitive mineral equilibria in the same rocks, a complete assessment of the P-T-t (pressure-temperature-time) path is possible given that the mineralogy of plutons can reflect crystallization over a range of pressure and temperature during ascent and emplacement and that many intrusions are now seen as forming over several millions of years during the protracted history of batholith construction. Accessory mineral saturation thermometers, such as those for zircon, apatite, and allanite, provide a different and powerful perspective, specifically that of the temperature of the onset of crystallization of these minerals, which can allow an estimate of the range of temperature between the liquidus and solidus of a given pluton. In assessment of the depth of crystallization and emplacement of granitic plutons, the Al-in-hornblende remains popular for metaluminous granites when appropriately corrected for temperature. For peraluminous granites, potential new calibrations exist for the assemblages bearing garnet, biotite, plagioclase, muscovite, and quartz. Other thermometers, based on oxygen abundance, and including Fe-Ti oxides, pyroxene, fayalitic olivine, quartz, sphene, and/or biotite, some of which have been recently revised, can provide additional information on temperature and oxygen fugacity. Oxygen fugacity can range over several orders of magnitude in different magmatic systems and can have profound influence on the mineralogy and mineral compositions in granitic magmas. It also forms the foundation of the popular magnetite- versus ilmenite-series granite classification. Copyright ?? Mineralogical Society of America.

Kinetics of thermal decomposition of hydrated minerals associated with hematite ore in a fluidized bed reactor

NASA Astrophysics Data System (ADS)

Beuria, P. C.; Biswal, S. K.; Mishra, B. K.; Roy, G. G.

2017-03-01

The kinetics of removal of loss on ignition (LOI) by thermal decomposition of hydrated minerals present in natural iron ores (i.e., kaolinite, gibbsite, and goethite) was investigated in a laboratory-scale vertical fluidized bed reactor (FBR) using isothermal methods of kinetic analysis. Experiments in the FBR in batch processes were carried out at different temperatures (300 to 1200°C) and residence time (1 to 30 min) for four different iron ore samples with various LOIs (2.34wt% to 9.83wt%). The operating velocity was maintained in the range from 1.2 to 1.4 times the minimum fluidization velocity ( U mf). We observed that, below a certain critical temperature, the FBR did not effectively reduce the LOI to a desired level even with increased residence time. The results of this study indicate that the LOI level could be reduced by 90% within 1 min of residence time at 1100°C. The kinetics for low-LOI samples (<6wt%) indicates two different reaction mechanisms in two temperature regimes. At lower temperatures (300 to 700°C), the kinetics is characterized by a lower activation energy (diffusion-controlled physical moisture removal), followed by a higher activation energy (chemically controlled removal of LOI). In the case of high-LOI samples, three different kinetics mechanisms prevail at different temperature regimes. At temperature up to 450°C, diffusion kinetics prevails (removal of physical moisture); at temperature from 450 to 650°C, chemical kinetics dominates during removal of matrix moisture. At temperatures greater than 650°C, nucleation and growth begins to influence the rate of removal of LOI.

Extreme hydrothermal conditions at an active plate-bounding fault.

PubMed

Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G R; Janku-Capova, Lucie; Carpenter, Brett M; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

2017-06-01

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

Extreme hydrothermal conditions at an active plate-bounding fault

NASA Astrophysics Data System (ADS)

Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G. R.; Janku-Capova, Lucie; Carpenter, Brett M.; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R.; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

2017-06-01

Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

Temperature determines size and direction of effects of elevated CO2 and nitrogen form on yield quantity and quality of Chinese cabbage.

PubMed

Reich, M; van den Meerakker, A N; Parmar, S; Hawkesford, M J; De Kok, L J

2016-01-01

Rising atmospheric CO2 concentrations (e[CO2 ]) are presumed to have a significant impact on plant growth and yield and also on mineral nutrient composition, and therefore, on nutritional quality of crops and vegetables. To assess the relevance of these effects in future agroecosystems it is important to understand how e[CO2 ] interacts with other environmental factors. In the present study, we examined the interactive effects of e[CO2 ] with temperature and the form in which nitrogen is supplied (nitrate or ammonium nitrate) on growth, amino acid content and mineral nutrient composition of Chinese cabbage (Brassica pekinensis Rupr.), a crop characterised by its high nutritional value and increasing relevance for human nutrition in many developing countries. Higher temperature, ammonium nitrate and e[CO2 ] had a positive impact on net photosynthesis and growth. A stimulating effect of e[CO2 ] on growth was only observed if the temperature was high (21/18 °C, day/night), and an interaction of e[CO2 ] with N form was only observed if the temperature was ambient (15/12 °C, day/night). Mineral nutrient composition was affected in a complex manner by all three factors and their interaction. These results demonstrate how much the effect of e[CO2 ] on mineral quality of crops depends on other environmental factors. Changes in temperature, adapting N fertilisation and the oxidation state of N have the potential to counteract the mineral depletion caused by e[CO2 ]. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

Ion microprobe survey of the grain-scale oxygen isotope geochemistry of minerals in metamorphic rocks

NASA Astrophysics Data System (ADS)

Ferry, John M.; Kitajima, Kouki; Strickland, Ariel; Valley, John W.

2014-11-01

The oxygen isotope compositions of calcite, diopside, dolomite, forsterite, garnet, K-feldspar, kyanite, plagioclase, quartz, and wollastonite were analyzed in suites of contact and regional metamorphic rocks using an ion microprobe. Spatial resolution was ∼10 μm. Precision, measured as the standard deviation of working standards averaged over the entire project, was 0.13-0.18‰ for three carbonate standards and 0.11-0.12‰ for two silicate standards. A total of 1176 analyses (excluding standards) were made of 73 minerals in 23 samples. Both intercrystalline and intracrystalline variability in δ18O is greater in contact than in regional metamorphic rocks. Of 27 minerals analyzed in contact metamorphosed rocks, 70% exhibit statistically significant grain-to-grain variability in δ18O over areas ⩽1.41 cm2 with the largest range in silicates and carbonates in a single sample of 7.4‰ (forsterite) and 10.6‰ (dolomite). Of 88 grains analyzed in two or more places in contact metamorphosed rocks, 32% exhibit statistically significant intracrystalline variability in δ18O with the largest range in a single silicate and carbonate grain of 3.1‰ (forsterite) and 10.1‰ (dolomite). In contrast, 44% of 45 minerals in regional metamorphic rocks exhibit significant grain-to-grain variability in δ18O over areas ⩽1.17 cm2 with the largest range in silicates and carbonates in a single sample of only 1.1‰ (plagioclase) and 0.9‰ (calcite). Only 6% of 144 grains analyzed in two or more places in regional metamorphic rocks exhibit significant intracrystalline variability in δ18O with the largest range in a single silicate and carbonate grain of only 1.5‰ (diopside) and 0.7‰ (calcite). The difference in intercrystalline and intracrystalline variability in δ18O between contact and region metamorphic rocks is explained by the longer duration and slower reaction rates of regional metamorphism rather than to differences in temperature. There is no significant difference in intercrystalline and intracrystalline variability in δ18O in regional metamorphic rocks among samples from the biotite, garnet, and kyanite zones. Calcite inclusions in forsterite, and calcite and quartz inclusions in garnet either have δ18O that is statistically indistinguishable from δ18O of the same mineral occurring as nearby matrix grains or have statistically significant lower δ18O. No reversed isotope fractionations were measured between coexisting mineral pairs. Minerals in individual samples, however, exhibit a wide range in the degree to which they attained and preserve oxygen isotope fractionations consistent with metamorphic temperatures recorded by mineral equilibria. Processes that account for grain-scale departures from isotope exchange equilibrium include: (a) overstepping of prograde mineral reactions, (b) growth zoning in low-diffusivity minerals, (c) interaction of rocks with fluids at the peak of metamorphism and/or during cooling, (d) retrograde mineral reactions, and (e) closed-system isotope exchange between coexisting minerals during cooling. This study provides new information about (1) the degree to which a variety of textural changes experienced by rocks during metamorphism are associated with changes in δ18O, (2) oxygen isotope homogenization at the outcrop scale among contrasting lithologies, (3) changes in δ18O with increasing grade of regional metamorphism, and (4) time scales of metamorphic process.

A coupled model between mechanical deformation and chemical diffusion: An explanation for the preservation of chemical zonation in plagioclase at high temperatures

NASA Astrophysics Data System (ADS)

Zhong, Xin; Vrijmoed, Johannes; Moulas, Evangelos; Tajcmanová, Lucie

2016-04-01

Compositional zoning in metamorphic minerals have been generally recognized as an important geological feature to decipher the metamorphic history of rocks. The observed chemical zoning of, e.g. garnet, is commonly interpreted as disequilibrium between the fractionated inner core and the surrounding matrix. However, chemically zoned minerals were also observed in high grade rocks (T>800 degree C) where the duration of metamorphic processes was independently dated to take several Ma. This implies that temperature may not be the only factor that controls diffusion timescales, and grain scale pressure variation was proposed to be a complementary factor that may significantly contribute to the formation and preservation of chemical zoning in high temperature metamorphic minerals [Tajcmanová 2013, 2015]. Here, a coupled model is developed to simulate viscous deformation and chemical diffusion. The numerical approach considers the conservation of mass, momentum, and a constitutive relation developed from equilibrium thermodynamics. A compressible viscoelastic rheology is applied, which associates the volumetric change triggered by deformation and diffusion to a change of pressure. The numerical model is applied to the chemically zoned plagioclase rim described by [Tajcmanová 2014]. The diffusion process operating during the plagioclase rim formation can lead to a development of a pressure gradient. Such a pressure gradient, if maintained during ongoing viscous relaxation, can lead to the preservation of the observed chemical zonation in minerals. An important dimensionless number, the Deborah number, is defined as the ratio between the Maxwell viscoelastic relaxation time and the characteristic diffusion time. It characterizes the relative influence between the maintenance of grain scale pressure variation and chemical diffusion. Two extreme regimes are shown: the mechanically-controlled regime (high Deborah number) and diffusion-controlled regime (low Deborah number). In the mechanically-controlled regime, the grain scale pressure variation and thus the chemical zonation can be maintained due to slow viscous relaxation. Furthermore, by utilizing experimental flow laws and diffusion coefficients, the Deborah number is estimated in a variety of physical conditions. References Tajcmanová, L., Y. Podladchikov, R. Powell, E. Moulas, J.C. Vrijmoed, and J.A.D. Connolly, 2014. Journal of Metamorphic Geology, 32(2):195-207. Tajcmanová, L., J.C. Vrijmoed, and E. Moulas, 2015. Lithos, 216-217:338-351.

Chronology of magmatism and mineralization in the Kassandra mining area, Greece: The potentials and limitations of dating hydrothermal illites

NASA Astrophysics Data System (ADS)

Gilg, H. Albert; Frei, Robert

1994-05-01

Various geochronological methods ( U/Pb, Rb/Sr, and K/Ar) have been applied to constrain the timing of magmatism and polymetallic mineralization in the Kassandra mining district, northern Greece. These data provide the first geochronological evidence that porphyry copper mineralization, proximal copper skarns, and distal high-temperature carbonate-hosted Pb-Zn-Ag-Au replacement ores formed contemporaneously and probably within less than 2 million years. Polymetallic mineralization is temporally related to the emplacement of granodioritic to quartz dioritic porphyries (24-25 Ma) that postdate the largest post-tectonic intrusion of the area, the Stratoni granodiorite (27.9 ± 1.2 Ma). Andesite porphyry dikes, which crosscut the Pb-Zn-Ag-Au ores and associated alterations, represent the last magmatic phase in the area (19.1 ± 0.6 Ma) and did not contribute to metal concentration. The combination of K/Ar, Rb/Sr, and oxygen isotope studies of hydrothermal illite-rich clays and careful granulometric analysis constrains the reliability of these geochronological methods and emphasizes the importance of characterizing the post-formational history of the sample. We identify various processes which partly disturbed the K/Ar and Rb/Sr system of some clays, such as retrograde alteration by heated meteoric waters, superimposed supergene illitization, and resetting of both isotopic systems due to a hydrothermal overprint related to the intrusion of the andesite porphyry. Our data, however, suggest that diffusive Ar loss from the finest clay fractions (< 0.6 μm) during cooling of the hydrothermal system probably played the most important role in the disturbance of the K/Ar system. Conventional K/Ar ages of < 2 μm fractions from high-temperature illites (> 200°C), therefore, do not give reliable formation ages. The loss of Ar may be used to model the cooling history of the hydrothermal system applying the concept of closure temperatures ( DODSON, 1973). 40K- 40Ar rad isochrons of natural, coarser grained (> 0.6 μm) size fractions of illites from single samples, even when slightly contaminated with feldspars, may yield meaningful ages either of the formation or of a reheating event. The Rb/Sr dating of hydrothermal clays is sensitive to contamination by adsorbed strontium, which may not be cogenetic with the clay, as well as feldspars, which may not have been homogenized isotopically by the illitization process.

Monazite behaviours during high-temperature metamorphism: a case study from Dinggye region, Tibetan Himalaya

NASA Astrophysics Data System (ADS)

Wang, Jia-Min; Wu, Fu-Yuan; Rubatto, Daniela; Liu, Shi-Ran; Zhang, Jin-Jiang

2017-04-01

Monazite is a key accessory mineral for metamorphic geochronology, but its growth mechanisms during melt-bearing high-temperature metamorphism is not well understood. Therefore, the petrology, pressure-temperature and timing of metamorphism have been investigated in pelitic and psammitic granulites from the Greater Himalayan Crystalline Complex (GHC) in Dinggye, southern Tibet. These rocks underwent an isothermal decompression process from pressure conditions of >10 kbar to <5 kbar with constant temperatures of 750-830°C, and recorded three metamorphic stages of kyanite-grade (M1), sillimanite-grade (M2) and cordierite-spinel grade (M3). Monazite and zircon crystals were analyzed for ages by microbeam techniques either in mounts or thin sections. Ages were linked to specific conditions of mineral growth by comprehensive studies on zoning patterns, trace element signatures, index mineral inclusions (melt inclusions, sillimanite and K-feldspar) in dated domains and textural correlations with coexisting minerals. The results show that inherited domains (500-400 Ma) are common in monazite even at granulite-facies conditions. Few monazites formed at the M1-stage ( 30-29 Ma) and recorded heterogeneous Th, Y, and HREE compositions, which formed by recrystallization related to muscovite dehydration melting reaction. These monazite grains were protected from dissolution or lateral overprinting mainly by the armour effect of matrix crystals (biotite and quartz). Most monazite grains formed at the M3-stage (21-19 Ma) through either dissolution-reprecipitation or recrystallization that was related to biotite dehydration melting reaction. These monazite grains record HREE and Y signatures in local equilibrium with different reactions involving either garnet breakdown or peritectic garnet growth. Another peak of monazite growth occurs during melt crystallization ( 15 Ma), and these monazites are unzoned and have homogeneous compositions. Our results documented the widespread recrystallization to account for monazite growth during high-temperature metamorphism and related melting reactions that trigger monazite recrystallization. In a regional sense, our P-T-t data along with published data indicate that the pre-M1 eclogite-facies metamorphism occurred at 39-30 Ma in the Dinggye Himalaya. Our results are in favour of a steady exhumation of the GHC rocks since Oligocene that was contributed by partial melting. Key words: U-Th-Pb geochronology, Monazite, Recrystallization, Pelitic granulite, Himalaya

Immersion freezing of supermicron mineral dust particles: freezing results, testing different schemes for describing ice nucleation, and ice nucleation active site densities.

PubMed

Wheeler, M J; Mason, R H; Steunenberg, K; Wagstaff, M; Chou, C; Bertram, A K

2015-05-14

Ice nucleation on mineral dust particles is known to be an important process in the atmosphere. To accurately implement ice nucleation on mineral dust particles in atmospheric simulations, a suitable theory or scheme is desirable to describe laboratory freezing data in atmospheric models. In the following, we investigated ice nucleation by supermicron mineral dust particles [kaolinite and Arizona Test Dust (ATD)] in the immersion mode. The median freezing temperature for ATD was measured to be approximately -30 °C compared with approximately -36 °C for kaolinite. The freezing results were then used to test four different schemes previously used to describe ice nucleation in atmospheric models. In terms of ability to fit the data (quantified by calculating the reduced chi-squared values), the following order was found for ATD (from best to worst): active site, pdf-α, deterministic, single-α. For kaolinite, the following order was found (from best to worst): active site, deterministic, pdf-α, single-α. The variation in the predicted median freezing temperature per decade change in the cooling rate for each of the schemes was also compared with experimental results from other studies. The deterministic model predicts the median freezing temperature to be independent of cooling rate, while experimental results show a weak dependence on cooling rate. The single-α, pdf-α, and active site schemes all agree with the experimental results within roughly a factor of 2. On the basis of our results and previous results where different schemes were tested, the active site scheme is recommended for describing the freezing of ATD and kaolinite particles. We also used our ice nucleation results to determine the ice nucleation active site (INAS) density for the supermicron dust particles tested. Using the data, we show that the INAS densities of supermicron kaolinite and ATD particles studied here are smaller than the INAS densities of submicron kaolinite and ATD particles previously reported in the literature.

Inferring changes in soil organic matter in post-wildfire soil burn severity levels in a temperate climate.

PubMed

Merino, Agustín; Fonturbel, María T; Fernández, Cristina; Chávez-Vergara, Bruno; García-Oliva, Felipe; Vega, Jose A

2018-06-15

Simple, rapid and reliable methods of assessing soil burn severity (SBS) are required in order to prioritize post-fire emergency stabilization actions. SBS proxies based on visual identification and changes in soil organic matter (SOM) content and quality can be related to other soil properties in order to determine the extent to which soil is perturbed following fire. This task is addressed in the present study by an approach involving the use of differential scanning calorimetry-thermogravimetric analysis (DSC-TGA) to determine changes in SOM generated in soils subjected to different levels of SBS. Intact topsoil monoliths comprising the organic horizons and the surface mineral soil (alumic-humic umbrisols) were collected from a representative P. pinaster stand in NW Spain. The monoliths were experimentally burned in a combustion wind tunnel to simulate different fire conditions (fuel bed comprising forest pine litter and wood; air flow, 0.6 m s -1 ). Changes in OM properties in the soil organic layer and mineral soils samples (0-2 cm) at the different temperatures and SBS levels were identified. For both duff and mineral soil, the data revealed a temperature-induced increase in aromatic compounds and a concomitant decrease of carbohydrates and alkyl products. However, for a given temperature, the degree of carbonization/aromatization was lower in the mineral soil than in the duff, possibly due to the different composition of the OM and to the different combustion conditions. The low degree of aromatization of the organic matter suggests that this soil component could undergo subsequent biological degradation. SOM content and thermal recalcitrance (measured as T50) discriminated the SBS levels. Use of visual identification of SBS levels in combination with DSC-TGA enables rapid evaluation of the spatial variability of the effects of fire on SOM properties. This information is useful to predict soil degradation process and implement emergency soil stabilization techniques. Copyright © 2018 Elsevier B.V. All rights reserved.

Electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clays. Role in U and Hg(II) transformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scherer, Michelle

2016-08-31

During this project, we investigated Fe electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clay minerals. We used selective chemical extractions, enriched Fe isotope tracer experiments, computational molecular modeling, and Mössbauer spectroscopy. Our findings indicate that structural Fe(III) in clay minerals is reduced by aqueous Fe(II) and that electron transfer occurs when Fe(II) is sorbed to either basal planes and edge OH-groups of clay mineral. Findings from highly enriched isotope experiments suggest that up to 30 % of the Fe atoms in the structure of some clay minerals exhanges with aqueous Fe(II). First principles calculations usingmore » a small polaron hopping approach suggest surprisingly fast electron mobility at room temperature in a nontronite clay mineral and are consistent with temperature dependent Mössbauer data Fast electron mobility suggests that electrons may be able to conduct through the mineral fast enough to enable exchange of Fe between the aqueous phase and clay mineral structure. over the time periods we observed. Our findings suggest that Fe in clay minerals is not as stable as previously thought.« less

Secondary mineral growth in fractures in the Miravalles geothermal system, Costa Rica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rochelle, C.A.; Milodowski, A.E.; Savage, D.

1989-01-01

A mineralogical, fluid-chemical, and theoretical study of hydrothermal alteration in veins from drillcore from the Miravalles geothermal field, Costa Rica has revealed a complex history of mineral-fluid reaction which may be used to characterize changes in temperature and fluid composition with time. Mineralogical and mineral-chemical data are consistent with hydrothermal alteration in the temperature range 200{sup 0}-270{sup 0}C, with deeper portions of the system having undergone temperatures in excess of 300{sup 0}C. Thermodynamic calculations suggest that the observed alteration assemblage is not equilibrium with current well fluids, unless estimates of reservoir pH are incorrect. Fe-Al zoning of prehnite and epidotemore » in veins is consistent with rapid, isothermal fluctuations in fluid composition at current reservoir temperatures, and may be due to changes in volatile content of the fluid due to tectonic activity.« less

Crystal Structure Studies of Low-Ca Pyroxenes from LL-Group Chondritic Meteorites

NASA Astrophysics Data System (ADS)

Artioli, G.; Davoli, G.; Sighinolfi, G. P.

1993-07-01

One orthorhombic (Pbca) and two monoclinic (P2(sub)1/c) single crystals of low-Ca pyroxenes were extracted from unequilibrated chondritic meteorites of the LL-group. The results of the crystal structure refinements performed using x-ray diffraction data indicate that: (1) the intracrystalline Fe-Mg distribution over the M1 and M2 crystallographic sites of the Parnallee (LL-3) orthoenstatite is consistent with a temperature of 960 degrees C for the closure of the exchange equilibrium process; and (2) the structural state and intracristalline Fe-Mg order in the Soko Banja (LL-4) and Jolomba (LL-6) clinoenstatites indicate a closing temperature of at least 1000-1100 degrees C, with no significant reequilibration at lower temperatures. The present data represent the first detailed crystallographic investigation of pyroxenes from LL-chondrites and support the hypothesis that the chondrule pyroxenes bear a distinct memory of rapid cooling in the solar nebular and that thermal metamorphism in the parent body, if present, was totally unsufficient to allow reequilibration of the pyroxene minerals to the low-temperature ordered crystal structures. The data also indicate that, assuming low or mild pressure and shock effects, there is no well-defined correlation between equilibrium temperature of the mineral phases and the alleged petrologic type of the meteorites. This evidence is consistent with a rubble-pile model for the parent body accretional history, or with an onion-shell model with very low thermal-peak metamorphism, as it is assumed for a very small object.

Tin in granitic melts: The role of melting temperature and protolith composition

NASA Astrophysics Data System (ADS)

Wolf, Mathias; Romer, Rolf L.; Franz, Leander; López-Moro, Francisco Javier

2018-06-01

Granite bound tin mineralization typically is seen as the result of extreme magmatic fractionation and late exsolution of magmatic fluids. Mineralization, however, also could be obtained at considerably less fractionation if initial melts already had enhanced Sn contents. We present chemical data and results from phase diagram modeling that illustrate the dominant roles of protolith composition, melting conditions, and melt extraction/evolution for the distribution of Sn between melt and restite and, thus, the Sn content of melts. We compare the element partitioning between leucosome and restite of low-temperature and high-temperature migmatites. During low-temperature melting, trace elements partition preferentially into the restite with the possible exception of Sr, Cd, Bi, and Pb, that may be enriched in the melt. In high-temperature melts, Ga, Y, Cd, Sn, REE, Pb, Bi, and U partition preferentially into the melt whereas Sc, V, Cr, Co, Ni, Mo, and Ba stay in the restite. This contrasting behavior is attributed to the stability of trace element sequestering minerals during melt generation. In particular muscovite, biotite, titanite, and rutile act as host phases for Sn and, therefore prevent Sn enrichment in the melt as long as they are stable phases in the restite. As protolith composition controls both the mineral assemblage and modal contents of the various minerals, protolith composition eventually also controls the fertility of a rock during anatexis, restite mineralogy, and partitioning behavior of trace metals. If a particular trace element is sequestered in a phase that is stable during partial melting, the resulting melt is depleted in this element whereas the restite becomes enriched. Melt generation at high temperature may release Sn when Sn-hosts become unstable. If melt has not been lost before the breakdown of Sn-hosts, Sn contents in the melt will increase but never will be high. In contrast, if melt has been lost before the decomposition of Sn-hosts, the small volume of the high-temperature melt will not be diluted by low-temperature, low-Sn melts and, therefore, could have high Sn-contents. The combination of multiple melt extractions and Sn-mobilization at high temperature results in strong Sn enrichment in late, high-temperature melts. Metal enrichment during partial melting becomes particularly efficient, if the sedimentary protolith had experienced intense chemical alteration as the loss of Na and Ca together with a relative enrichment of K favors muscovite-rich metamorphic mineral assemblages that produce large amounts of melt during muscovite dehydration melting.

Laboratory-generated mixtures of mineral dust particles with biological substances: characterization of the particle mixing state and immersion freezing behavior

NASA Astrophysics Data System (ADS)

Augustin-Bauditz, Stefanie; Wex, Heike; Denjean, Cyrielle; Hartmann, Susan; Schneider, Johannes; Schmidt, Susann; Ebert, Martin; Stratmann, Frank

2016-05-01

Biological particles such as bacteria, fungal spores or pollen are known to be efficient ice nucleating particles. Their ability to nucleate ice is due to ice nucleation active macromolecules (INMs). It has been suggested that these INMs maintain their nucleating ability even when they are separated from their original carriers. This opens the possibility of an accumulation of such INMs in soils, resulting in an internal mixture of mineral dust and INMs. If particles from such soils which contain biological INMs are then dispersed into the atmosphere due to wind erosion or agricultural processes, they could induce ice nucleation at temperatures typical for biological substances, i.e., above -20 up to almost 0 °C, while they might be characterized as mineral dust particles due to a possibly low content of biological material. We conducted a study within the research unit INUIT (Ice Nucleation research UnIT), where we investigated the ice nucleation behavior of mineral dust particles internally mixed with INM. Specifically, we mixed a pure mineral dust sample (illite-NX) with ice active biological material (birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). A very important topic concerning the investigations presented here as well as for atmospheric application is the characterization of the mixing state of aerosol particles. In the present study we used different methods like single-particle aerosol mass spectrometry, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), and a Volatility-Hygroscopicity Tandem Differential Mobility Analyser (VH-TDMA) to investigate the mixing state of our generated aerosol. Not all applied methods performed similarly well in detecting small amounts of biological material on the mineral dust particles. Measuring the hygroscopicity/volatility of the mixed particles with the VH-TDMA was the most sensitive method. We found that internally mixed particles, containing ice active biological material, follow the ice nucleation behavior observed for the pure biological particles. We verified this by modeling the freezing behavior of the mixed particles with the Soccerball model (SBM). It can be concluded that a single INM located on a mineral dust particle determines the freezing behavior of that particle with the result that freezing occurs at temperatures at which pure mineral dust particles are not yet ice active.

Association of gold with uraninite and pyrobitumen in the metavolcanic rock hosted hydrothermal Au-U mineralisation at Rompas, Peräpohja Schist Belt, northern Finland

NASA Astrophysics Data System (ADS)

Molnár, Ferenc; Oduro, Harry; Cook, Nick D. J.; Pohjolainen, Esa; Takács, Ágnes; O'Brien, Hugh; Pakkanen, Lassi; Johanson, Bo; Wirth, Richard

2016-06-01

The Peräpohja Schist Belt comprises a supracrustal sequence of quartzites, mafic volcanics and volcaniclastics, carbonate rocks, black shales, mica schists and greywackes which were deposited from ca. 2.44 to ~1.91 Ga, during the rifting of the Archaean basement in the eastern part of the Fennoscandian shield. Metamorphism and multiple folding of the basin fill took place during the Svecofennian orogeny (1.9-1.8 Ga) followed by intrusions of late-orogenic (1.84-1.80 Ga) and post-orogenic granitoids (1.79-1.76 Ga). The Rompas Au-U mineralisation is hosted by deformed calcsilicate veins in mafic volcanic rocks and locally contains very high grade (>10,000 g/t Au) gold pockets with strict spatial association of gold minerals to uraninite and pyrobitumen. Chemical ages from the unaltered domains in the structure of uraninite indicate a 1.95-1.90 Ga age for the deposition of the primary, high temperature (e.g. U/Th < 100 in uraninite) hydrothermal uranium mineralisation. These data are in agreement with the results of previous U-Pb dating of uraninite by SIMS. Textural evidence suggests that metamorphic recrystallisation of the uraninite-bearing quartz-dolomite veins into calcsilicate mineral assemblages during the Svecofennian orogeny (1.9-1.8 Ga) was followed by a hydrocarbon-bearing fluid flow event and radiolytic polymerisation of hydrocarbons around grains of uraninite. Gold precipitated during a subsequent hydrothermal process in the fractures of uraninite, as well as in the cracks and on the botryoidal surfaces of uraninite-pyrobitumen nodules. Remobilisation and redeposition of uranium by these hydrothermal events produced secondary uraninite grains with chemical ages between 1.85 and 1.65 Ga. Native gold is associated with galena, altaite, hunchunite, nickeline and rare cobaltite, Pb-bearing maldonite, pyrite, pyrrhotite, chalcopyrite, molybdenite and titanite. Raman spectra show disordered structure of undeformed pyrobitumen nodules in contrast with the well-ordered graphite in calcsilicate veins. Mean random reflectance data for pyrobitumen indicate 270-340 °C maximum temperature of thermal maturation—this temperature range is also considered as the temperature of gold deposition. Results of multiple sulphur isotope analyses of organic material-, pyrite- and acid-volatile-bound sulphur show distinct ranges of δ34S values for SORG and SCRS in uraninite-pyrobitumen (from -6.99 to -3.55‰ and from -10.02 to -4.41‰, respectively) and uraninite-pyrobitumen-native gold mineral associations (from +1.36 to +6.87‰ and from +0.42 to +9.7‰, respectively). Δ33S data indicate local occurrence of nonmass-dependent sulphur isotope fractionation owing to interaction of fluids with organic material. Concentration of lead in uraninite is depleted along the gold mineral filled fractures whereas the uranogenic lead isotope contents of galena, altaite and hunchuite deposited in the same fractures are extremely high, suggesting that the dominant source of lead for the crystallisation of these minerals was the radiogenic lead content of uraninite. Taking into account this source of radiogenic lead, the calculated Pb-Pb model ages for the lead minerals are between 1.75 and 1.70 Ga. Sulphur and tellurium removal from the fluid by reaction with radiogenic lead released by uraninite appears to be an important mechanism in the strongly localised deposition of gold minerals. Scavenging of sulphur by pyrobitumen nodules from gold transporting fluids was an additional process triggering precipitation of gold. Carbon particles and organic functional groups in pyrobitumen probably acted as nucleation and adsorption centres for gold minerals.

Multiple hydrothermal and metamorphic events in the Kidd Creek volcanogenic massive sulphide deposit, Timmins, Ontario: evidence from tourmalines and chlorites

USGS Publications Warehouse

Slack, J.F.; Coad, P.R.

1989-01-01

The tourmalines and chlorites record a series of multiple hydrothermal and metamorphic events. Paragenetic studies suggest that tourmaline was deposited during several discrete stages of mineralization, as evidence by brecciation and cross-cutting relationships. Most of the tourmalines have two concentric growth zones defined by different colours (green, brown, blue, yellow). Some tourmalines also display pale discordant rims that cross-cut and embay the inner growth zones and polycrystalline, multiple-extinction domains. Late sulphide veinlets (chalcopyrite, pyrrhotite) transect the inner growth zones and pale discordant rims of many crystals. The concentric growth zones are interpreted as primary features developed by the main ore-forming hydrothermal system, whereas the discordant rims, polycrystalline domains, and cross-cutting sulphide veinlets reflect post-ore metamorphic processes. Variations in mineral proportions and mineral chemistry within the deposit mainly depend on fluctuations in temperature, pH, water/rock ratios, and amounts of entrained seawater. -from Authors

13C-18O isotope signatures and ‘clumped isotope’ thermometry in foraminifera and coccoliths

NASA Astrophysics Data System (ADS)

Tripati, Aradhna K.; Eagle, Robert A.; Thiagarajan, Nivedita; Gagnon, Alexander C.; Bauch, Henning; Halloran, Paul R.; Eiler, John M.

2010-10-01

Accurate constraints on past ocean temperatures and compositions are critical for documenting climate change and resolving its causes. Most proxies for temperature are not thermodynamically based, appear to be subject to biological processes, require regional calibrations, and/or are influenced by fluid composition. As a result, their interpretation becomes uncertain when they are applied in settings not necessarily resembling those in which they were empirically calibrated. Independent proxies for past temperature could provide an important means of testing and/or expanding on existing reconstructions. Here we report measurements of abundances of stable isotopologues of calcitic and aragonitic benthic and planktic foraminifera and coccoliths, relate those abundances to independently estimated growth temperatures, and discuss the possible scope of equilibrium and kinetic isotope effects. The proportions of 13C- 18O bonds in these samples exhibits a temperature dependence that is generally similar to that previously been reported for inorganic calcite and other biologically precipitated carbonate-containing minerals (apatite from fish, reptile, and mammal teeth; calcitic brachiopods and molluscs; aragonitic coral and mollusks). Most species that exhibit non-equilibrium 18O/ 16O (δ 18O) and 13C/ 12C (δ 13C) ratios are characterized by 13C- 18O bond abundances that are similar to inorganic calcite and are generally indistinguishable from apparent equilibrium, with possible exceptions among benthic foraminiferal samples from the Arctic Ocean where temperatures are near-freezing. Observed isotope ratios in biogenic carbonates can be explained if carbonate minerals generally preserve a state of ordering that reflects the extent of isotopic equilibration of the dissolved inorganic carbon species.

Magnetic Properties of Soils from Sarimukti Landfill as Proxy Indicators of Pollution (Case Study: Desa Sarimukti, Kabupaten Bandung Barat)

NASA Astrophysics Data System (ADS)

Cita Novala, Gesti; Fitriani, Dini; Susanto, Kusnahadi; Hajar Kirana, Kartika

2016-01-01

Leachate is the liquid arises from waste disposal. It contains heavy metals and magnetic minerals. Leachate could penetrate into sub surface that cause soil contamination. We have studied magnetic properties of soils from three zones in the Sarimukti landfill. We measured magnetic susceptibility in dual frequency and temperature dependent of susceptibility. The results showed that magnetic susceptibility at low frequency (xlf) of soil samples have the value ranging from 50-1400 (x 10-8 m3/kg). It infers that the samples were dominated by ferrimagnetic minerals. The relative difference of magnetic susceptibility measured at two frequency (xfd(%)) are less than 4%. It indicates that magnetic minerals probably derived from anthropogenic sources. There is negative correlation between xlf and Xfd(%). It supports the analysis that the source of magnetic minerals is anthropogenic. The results of the temperature dependent magnetic susceptibility measurements showed that the peak of magnetic susceptibility in heating curve occurs at the temperature about 200°C and 500°C. After 500°C, heating curve rapidly decreases. It can be inferred that the dominant type of magnetic minerals in the samples is titanomagnetite.

Measuring the Spectral Properties of Candidate Mineral Sources of the Venus Radar Anomalies

NASA Astrophysics Data System (ADS)

Kohler, E.; Maturilli, A.; Koulen, J.; Helbert, J.

2016-12-01

Radar mapping of the surface of Venus shows areas of high reflectivity (low emissivity) in the Venusian highlands at altitudes between 2.5-4.75 kilometers. The origin of the radar anomalies found in the highlands remains unclear. Previous experimental research investigated possible materials under simulated Venusian atmospheric and surface conditions, with special emphasis on the combined effect of pressure and temperature, and chemical composition. The results of these studies identified candidate source materials for the radar anomalies. In order to fully be considered a true source candidate the material must have spectroscopic measurements comparable to those measured on the surface of Venus where the high temperature affects spectral characteristics of minerals. The spectroscopic measurements of the previously identified candidate minerals were made at the Planetary Spectroscopy Laboratory (PSL) of DLR in Berlin in an effort to identify the anomaly source. The spectroscopic measurements were made with a FTIR Bruker Vertex 80V evacuated to .1 mbar and using several pairings of detector+beamsplitter to cover the spectral range from 0.2 to 20 µm. Each sample was poured in a stainless steel reflectance cup and measured fresh. Successively each cup was heated (via an induction system) in vacuum (0.07 mbar) at 400°C for 8 hours and measured again in the UV+VIS+MIR spectral range. Three consecutive cycles of heating and measuring reflectance were performed to account for spectral variations arising from the thermal processing of the samples. Heating the samples directly inside the reflectance cups allows to measure every time exactly the same surface, exposed to increasing levels of thermal processing. Results from this study are expected to further constrain the source of the Venus radar anomalies.

Evaporation in equilibrium, in vacuum, and in hydrogen gas

NASA Technical Reports Server (NTRS)

Nagahara, Hiroko

1993-01-01

Evaporation experiments were conducted for SiO2 in three different conditions: in equilibrium, in vacuum, and in hydrogen gas. Evaporation rate in vacuum is about two orders of magnitude smaller than that in equilibrium, which is consistent with previous works. The rate in hydrogen gas changes depending on hydrogen pressure. The rate at 10 exp -7 bar of hydrogen pressure is as small as that of free evaporation, but at 10 exp -5 bar of hydrogen pressure it is larger than that in equilibrium. In equilibrium and in vacuum, the evaporation rate is limited by decomposition of SiO2 on the crystal surface, but it is limited by a diffusion process for evaporation in hydrogen gas. Therefore, evaporation rate of minerals in the solar nebula can be shown neither by that in equilibrium nor by that in vacuum. The maximum temperature of the solar nebula at the midplane at 2-3 AU where chondrites are believed to have originated is calculated to be as low as 150 K, 1500 K, or in between them. The temperature is, in any case, not high enough for total evaporation of the interstellar materials. Therefore, evaporation of interstellar materials is one of the most important processes for the origin and fractionation of solid materials. The fundamental process of evaporation of minerals has been intensively studied for these several years. Those experiments were carried out either in equilibrium or in vacuum; however, evaporation in the solar nebula is in hydrogen (and much smaller amount of helium) gas. In order to investigate evaporation rate and compositional (including isotopic) fractionation during evaporation, vaporization experiments for various minerals in various conditions are conducted. At first, SiO2 was adopted for a starting material, because thermochemical data and its nature of congruent vaporization are well known. Experiments were carried out in a vacuum furnace system.

Simulating thermal stress features on hot planetary surfaces in vacuum at high temperature facility in the PEL laboratory

NASA Astrophysics Data System (ADS)

Maturilli, A.; Ferrari, S.; Helbert, J.; D'Incecco, P.; D'Amore, M.

2011-12-01

In the Planetary Emissivity Laboratory (PEL) at the Institute for Planetary Research of the German Aerospace Center (DLR) in Berlin, we set-up a simulation chamber for the spectroscopic investigation of minerals separates under Mercurial conditions. The chamber can be evacuated to 10-4 bar and the target samples heated to 700 K within few minutes, thanks to the innovative inductive heating system. While developing the protocol for the high temperature spectroscopy measurements we discovered interesting "morphologies" on the sample surfaces. The powders are poured into stainless steel cups of 50 mm internal diameter, 8 mm height and 3 mm depth, having a 5 mm thick base (thus leaving 3 mm free space for the minerals), and rim 1 mm thick. We selected several minerals of interest for Mercurial surface composition and for each of them we analyzed various grain size separates, to study the influence of grain dimensions to the process of thermal stressing. We observed that for the smaller grain size separate (0-25 μm) the thermal stress mainly induces large depressions and fractures, while on larger grain sizes (125-250 μm) small depressions and a cratered surface. Our current working hypothesis is that these features are mainly caused by thermal stress induced by a radiatively quickly cooling surface layer covering the much hotter bulk material. Further investigation is ongoing to understand the processes better. The observed morphologies exhibit surprising similarities to features observed at planetary scale size for example on Mercury and even on Venus. Especially the high resolution images provided currently from MESSENGER'S Mercury Dual Imaging System (MDIS) instrument has revealed plains dominated by polygonal fractures whose origin still have to be determined. Our laboratory analogue studies might in the future provide some insight into the processes creating those features

Thermochemical Constraints For the Formation Conditions of the Hydrothermal Alteration Mineralogy of Home Plate and Columbia Hills

NASA Astrophysics Data System (ADS)

Filiberto, J.; Schwenzer, S. P.

2012-12-01

Home Plate is a plateau in the Columbia Hills of Gusev Crater. It is dominated by igneous minerals (olivine, pyroxene, and magnetite) with small amounts of alteration minerals (hematite and nanophase oxides). Surrounding Home Plate are deposits containing diverse secondary mineral assemblages: Fe3+-sulfates deposits at Paso Robles, Dead Sea, Shredded, Arad, Tyrone, and Troy; Hematite-rich outcrops between Home Plate and Tyrone; SiO2-rich deposits possibly containing pyrite and/or marcasite at Fuzzy Smith; SiO2-rich, possibly opaline silica, deposits at Northern Valley, Eastern Valley, and Tyrone; and Mg-Fe-carbonate outcrops at Comanche in the Columbia Hills [1-4]. Here, we focus on using thermochemical modeling to understand the secondary alteration mineralogy at the Home Plate outcrop and surrounding Columbia Hills region in Gusev Crater. We use CHILLER [5] to evaluate mineral assemblages that are likely to form from the Martian Home Plate, Barn-Hill class rock Fastball in contact with a dilute fluid at various pressures, temperatures, and water-rock ratios. For details see [6]. In our models, hematite dominates the alteration assemblage at high W/R at 150°C, but is generally produced at W/R above 10. Goethite only forms at low temperature and W/R above 40 with a maximum around 100 and again around 100,000. Pyrite is produced at all temperatures but only at relatively high W/R. These results imply intermediate to high W/R and low to intermediate temperatures during alteration of the Home Plate region. Additional acidic brine, while not strictly excluded, is not required to form many of the observed phases. In contrast, the phyllosilicates recently invoked from orbital observations [4] indicate neutral to alkaline conditions - either accompanying the silica precipitation or as a separate event. For future exploration, our results emphasize that the observation of assemblages is critically important to understand mineral formation conditions and that minor phases such as fluorite can give valuable insights into host rock chemistry and alteration conditions. REFS: [1] Ruff S.W. et al. (2011) JGR 116, doi.10.1029/2010je003767. [2] Morris R.V. et al. (2008) JGR 113, doi.10.1029/2008je003201. [3] Morris R.V. et al. (2010) Science 329, 421-424. [4] Carter J. and Poulet F. (2012) Icarus 219, 250-253. [5] Reed M.H. and Spycher N.F. (2006) User Guide for CHILLER: A Program for Computing Water-Rock Reactions, Boiling, Mixing, and Other Reaction Processes in Squeous-Mineral-Gas Systems and Minplot Guide (3rd ed.), Eugene, Oregon: University of Oregon. [6] Schwenzer S.P. and Kring D.A. (2009) Geology 37, 1091-1094.

Temperature Dependence of Mineral Solubility in Water. Part 3. Alkaline and Alkaline Earth Sulfates

NASA Astrophysics Data System (ADS)

Krumgalz, B. S.

2018-06-01

The databases of alkaline and alkaline earth sulfate solubilities in water at various temperatures were created using experimental data from the publications over about the last two centuries. Statistical critical evaluation of the created databases was produced since there were enough independent data sources to justify such evaluation. The reliable experimental data were adequately described by polynomial expressions over various temperature ranges. Using the Pitzer approach for ionic activity and osmotic coefficients, the thermodynamic solubility products for the discussed minerals have been calculated at various temperatures and represented by polynomial expressions.

Temperature Dependence of Mineral Solubility in Water. Part 2. Alkaline and Alkaline Earth Bromides

NASA Astrophysics Data System (ADS)

Krumgalz, B. S.

2018-03-01

Databases of alkaline and alkaline earth bromide solubilities in water at various temperatures were created using experimental data from publications over about the last two centuries. Statistical critical evaluation of the created databases was produced since there were enough independent data sources to justify such evaluation. The reliable experimental data were adequately described by polynomial expressions over various temperature ranges. Using the Pitzer approach for ionic activity and osmotic coefficients, the thermodynamic solubility products for the discussed bromide minerals have been calculated at various temperature intervals and also represented by polynomial expressions.

Characteristics and composition of fouling caused by pig slurry in a tubular heat exchanger--recommended cleaning systems.

PubMed

Cunault, C; Coquinot, Y; Burton, C H; Picard, S; Pourcher, A M

2013-03-15

The structure and composition of the fouling deposits caused by pig slurry heated in a tubular heat exchanger were characterized to understand their formation and thus be able to minimize fouling and define effective routine cleaning methods. Two temperatures (55 °C and 80 °C) were investigated. Two types of fouling were identified: organic/mineral and biofilm. The first only formed at temperatures above 50 °C, often during the heating phase, and was the main problem encountered in treatments at 80 °C. Organic/mineral deposits formed a thin compact sub-layer and a thick porous top layer composed of 67-76% minerals, 9-15% proteins, 8-20% carbohydrates and 0-5% fats. Biofilms formed at temperatures between 25 °C and 70 °C in both the cooling and heating sections of the exchanger. This type of fouling predominated at temperatures below 55 °C. The biofilm covered a thin mineral base layer. Strongly acidic or alkaline washing cycle are recommended to clean Type I deposits, while in-line gas-rumbling is recommended for Type II fouling. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimization of an innovative approach involving mechanical activation and acid digestion for the extraction of lithium from lepidolite

NASA Astrophysics Data System (ADS)

Vieceli, Nathália; Nogueira, Carlos A.; Pereira, Manuel F. C.; Durão, Fernando O.; Guimarães, Carlos; Margarido, Fernanda

2018-01-01

The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. Therefore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from lepidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and response-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphization and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery.

Electro activation of persulfate using iron sheet as low-cost electrode: the role of the operating conditions.

PubMed

Silveira, Jefferson E; Cardoso, Tais O; Barreto-Rodrigues, Marcio; Zazo, Juan A; Casas, José A

2018-05-01

This work assesses the role of the operational conditions upon the electro-activation of persulfate (PS) using sacrificed iron electrode as a continuous low-cost Fe 2+ source. An aqueous phenol solution (100 mg L -1 ) was selected as model effluent. The studied variables include current density (1-10 mA cm -2 ), persulfate concentration (0.7-2.85 g L -1 ), temperature (30-90°C) and the solution conductivity (2.7-20.7 mS cm -1 ) using Na 2 SO 4 and NaCl as supporting electrolyte. A mineralization degree of around 80% with Na 2 SO 4 and 92% in presence of NaCl was achieved at 30°C using 2.15 g L -1 PS at the lowest current density tested (1 mA cm -2 ). Besides PS concentration, temperature was the main variable affecting the process. In the range of 30-70°C, it showed a positive effect, achieving TOC conversion above 95% (using Na 2 SO 4 under the previous conditions) along with a significant increase in iron sludge, which adversely affects the economy of the process. A lumped and simplified kinetic model based on persulfate consumption and TOC mineralization is suggested. The activation energy obtained for the TOC decay was 29 kJ mol -1 . An estimated operating cost of US$ 3.00 per m 3 was obtained, demonstrating the economic feasibility of this process.

Evaluation and simulation of nitrogen mineralization of paddy soils in Mollisols area of Northeast China under waterlogged incubation

PubMed Central

Zhang, Yuling; Xu, Wenjing; Duan, Pengpeng; Cong, Yaohui; An, Tingting; Yu, Na; Zou, Hongtao; Dang, Xiuli; An, Jing; Fan, Qingfeng; Zhang, Yulong

2017-01-01

Background Understanding the nitrogen (N) mineralization process and applying appropriate model simulation are key factors in evaluating N mineralization. However, there are few studies of the N mineralization characteristics of paddy soils in Mollisols area of Northeast China. Materials and methods The soils were sampled from the counties of Qingan and Huachuan, which were located in Mollisols area of Northeast China. The sample soil was incubated under waterlogged at 30°C in a controlled temperature cabinet for 161 days (a 2: 1 water: soil ratio was maintained during incubation). Three models, i.e. the single first-order kinetics model, the double first-order kinetics model and the mixed first-order and zero-order kinetics model were used to simulate the cumulative mineralised N (NH4+-N and TSN) in the laboratory and waterlogged incubation. Principal results During 161 days of waterlogged incubation, the average cumulative total soluble N (TSN), ammonium N (NH4+-N), and soluble organic N (SON) was 122.2 mg kg-1, 85.9 mg kg-1, and 36.3 mg kg-1, respectively. Cumulative NH4+-N was significantly (P < 0.05) positively correlated with organic carbon (OC), total N (TN), pH, and exchangeable calcium (Ca), and cumulative TSN was significantly (P < 0.05) positively correlated with OC, TN, and exchangeable Ca, but was not significantly (P > 0.05) correlated with C/N ratio, cation exchange capacity (CEC), extractable iron (Fe), clay, and sand. When the cumulative NH4+-N and TSN were simulated, the single first-order kinetics model provided the least accurate simulation. The parameter of the double first-order kinetics model also did not represent the actual data well, but the mixed first-order and zero-order kinetics model provided the most accurate simulation, as demonstrated by the estimated standard error, F statistic values, parameter accuracy, and fitting effect. Conclusions Overall, the results showed that SON was involved with N mineralization process, and the mixed first-order and zero-order kinetics model accurately simulates the N mineralization process of paddy soil in Mollisols area of Northeast China under waterlogged incubation. PMID:28170409

Evaluation and simulation of nitrogen mineralization of paddy soils in Mollisols area of Northeast China under waterlogged incubation.

PubMed

Zhang, Yuling; Xu, Wenjing; Duan, Pengpeng; Cong, Yaohui; An, Tingting; Yu, Na; Zou, Hongtao; Dang, Xiuli; An, Jing; Fan, Qingfeng; Zhang, Yulong

2017-01-01

Understanding the nitrogen (N) mineralization process and applying appropriate model simulation are key factors in evaluating N mineralization. However, there are few studies of the N mineralization characteristics of paddy soils in Mollisols area of Northeast China. The soils were sampled from the counties of Qingan and Huachuan, which were located in Mollisols area of Northeast China. The sample soil was incubated under waterlogged at 30°C in a controlled temperature cabinet for 161 days (a 2: 1 water: soil ratio was maintained during incubation). Three models, i.e. the single first-order kinetics model, the double first-order kinetics model and the mixed first-order and zero-order kinetics model were used to simulate the cumulative mineralised N (NH4+-N and TSN) in the laboratory and waterlogged incubation. During 161 days of waterlogged incubation, the average cumulative total soluble N (TSN), ammonium N (NH4+-N), and soluble organic N (SON) was 122.2 mg kg-1, 85.9 mg kg-1, and 36.3 mg kg-1, respectively. Cumulative NH4+-N was significantly (P < 0.05) positively correlated with organic carbon (OC), total N (TN), pH, and exchangeable calcium (Ca), and cumulative TSN was significantly (P < 0.05) positively correlated with OC, TN, and exchangeable Ca, but was not significantly (P > 0.05) correlated with C/N ratio, cation exchange capacity (CEC), extractable iron (Fe), clay, and sand. When the cumulative NH4+-N and TSN were simulated, the single first-order kinetics model provided the least accurate simulation. The parameter of the double first-order kinetics model also did not represent the actual data well, but the mixed first-order and zero-order kinetics model provided the most accurate simulation, as demonstrated by the estimated standard error, F statistic values, parameter accuracy, and fitting effect. Overall, the results showed that SON was involved with N mineralization process, and the mixed first-order and zero-order kinetics model accurately simulates the N mineralization process of paddy soil in Mollisols area of Northeast China under waterlogged incubation.

Urban net-zero water treatment and mineralization: experiments, modeling and design.

PubMed

Englehardt, James D; Wu, Tingting; Tchobanoglous, George

2013-09-01

Water and wastewater treatment and conveyance account for approximately 4% of US electric consumption, with 80% used for conveyance. Net zero water (NZW) buildings would alleviate demands for a portion of this energy, for water, and for the treatment of drinking water for pesticides and toxic chemical releases in source water. However, domestic wastewater contains nitrogen loads much greater than urban/suburban ecosystems can typically absorb. The purpose of this work was to identify a first design of a denitrifying urban NZW treatment process, operating at ambient temperature and pressure and circum-neutral pH, and providing mineralization of pharmaceuticals (not easily regulated in terms of environmental half-life), based on laboratory tests and mass balance and kinetic modeling. The proposed treatment process is comprised of membrane bioreactor, iron-mediated aeration (IMA, reported previously), vacuum ultrafiltration, and peroxone advanced oxidation, with minor rainwater make-up and H2O2 disinfection residual. Similar to biological systems, minerals accumulate subject to precipitative removal by IMA, salt-free treatment, and minor dilution. Based on laboratory and modeling results, the system can produce potable water with moderate mineral content from commingled domestic wastewater and 10-20% rainwater make-up, under ambient conditions at individual buildings, while denitrifying and reducing chemical oxygen demand to below detection (<3 mg/L). While economics appear competitive, further development and study of steady-state concentrations and sludge management options are needed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Method for separating water soluble organics from a process stream by aqueous biphasic extraction

DOEpatents

Chaiko, David J.; Mego, William A.

1999-01-01

A method for separating water-miscible organic species from a process stream by aqueous biphasic extraction is provided. An aqueous biphase system is generated by contacting a process stream comprised of water, salt, and organic species with an aqueous polymer solution. The organic species transfer from the salt-rich phase to the polymer-rich phase, and the phases are separated. Next, the polymer is recovered from the loaded polymer phase by selectively extracting the polymer into an organic phase at an elevated temperature, while the organic species remain in a substantially salt-free aqueous solution. Alternatively, the polymer is recovered from the loaded polymer by a temperature induced phase separation (cloud point extraction), whereby the polymer and the organic species separate into two distinct solutions. The method for separating water-miscible organic species is applicable to the treatment of industrial wastewater streams, including the extraction and recovery of complexed metal ions from salt solutions, organic contaminants from mineral processing streams, and colorants from spent dye baths.

The influence of shale depositional fabric on the kinetics of hydrocarbon generation through control of mineral surface contact area on clay catalysis

NASA Astrophysics Data System (ADS)

Rahman, Habibur M.; Kennedy, Martin; Löhr, Stefan; Dewhurst, David N.; Sherwood, Neil; Yang, Shengyu; Horsfield, Brian

2018-01-01

Accurately assessing the temperature and hence the depth and timing of hydrocarbon generation is a critical step in the characterization of a petroleum system. Clay catalysis is a potentially significant modifier of hydrocarbon generation temperature, but experimental studies of clay catalysis show inconsistent or contradictory results. This study tests the hypothesis that source rock fabric itself is an influence on clay mineral catalysis as it controls the extent to which organic matter and clay minerals are physically associated. Two endmember clay-organic fabrics distinguish the source rocks studied: (1) a particulate fabric where organic matter is present as discrete, >5 μm particles and (2) a nanocomposite fabric in which amorphous organic matter is associated with clay mineral surfaces at sub-micron scale. High-resolution electron imaging and bulk geochemical characterisation confirm that samples of the Miocene Monterey Formation (California) are representative of the nanocomposite source rock endmember, whereas samples from the Permian Stuart Range Formation (South Australia) represent the particulate source rock endmember. Kinetic experiments are performed on paired whole rock and kerogen isolate samples from these two formations using open system, non-isothermal pyrolysis at three different heating rates (0.7, 2 and 5 K/min) to determine the effects of the different shale fabrics on hydrocarbon generation kinetics. Extrapolation to a modelled geological heating rate shows a 20 °C reduction in the onset temperature of hydrocarbon generation in Monterey Formation whole rock samples relative to paired kerogen isolates. This result is consistent with the Monterey Formations's nanocomposite fabric where clay catalysis can proceed because reactive clay minerals are intimately associated with organic matter. By contrast, there is no significant difference in the modelled hydrocarbon generation temperature of paired whole rock and kerogen isolates from the Stuart Range Formation. This is consistent with its particulate fabric, where relatively large, discrete organic particles have limited contact with the mineral matrix and the clay minerals are mainly diagenetic and physically segregated within pores. While heating rate may have a control on mineral matrix effects, this result shows that the extent to which organic matter and clay minerals are physically associated could have a significant effect on the timing of hydrocarbon generation, and is a function of the depositional environment and detrital vs diagenetic origin of clay minerals in source rocks.

Experimental Investigation and Simplistic Geochemical Modeling of CO₂ Mineral Carbonation Using the Mount Tawai Peridotite.

PubMed

Rahmani, Omeid; Highfield, James; Junin, Radzuan; Tyrer, Mark; Pour, Amin Beiranvand

2016-03-16

In this work, the potential of CO₂ mineral carbonation of brucite (Mg(OH)2) derived from the Mount Tawai peridotite (forsterite based (Mg)₂SiO4) to produce thermodynamically stable magnesium carbonate (MgCO3) was evaluated. The effect of three main factors (reaction temperature, particle size, and water vapor) were investigated in a sequence of experiments consisting of aqueous acid leaching, evaporation to dryness of the slurry mass, and then gas-solid carbonation under pressurized CO2. The maximum amount of Mg converted to MgCO₃ is ~99%, which occurred at temperatures between 150 and 175 °C. It was also found that the reduction of particle size range from >200 to <75 µm enhanced the leaching rate significantly. In addition, the results showed the essential role of water vapor in promoting effective carbonation. By increasing water vapor concentration from 5 to 10 vol %, the mineral carbonation rate increased by 30%. This work has also numerically modeled the process by which CO₂ gas may be sequestered, by reaction with forsterite in the presence of moisture. In both experimental analysis and geochemical modeling, the results showed that the reaction is favored and of high yield; going almost to completion (within about one year) with the bulk of the carbon partitioning into magnesite and that very little remains in solution.

Chlorite, Biotite, Illite, Muscovite, and Feldspar Dissolution Kinetics at Variable pH and Temperatures up to 280 C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carroll, S.; Smith, M.; Lammers, K.

2016-10-05

Summary Sheet silicates and clays are ubiquitous in geothermal environments. Their dissolution is of interest because this process contributes to scaling reactions along fluid pathways and alteration of fracture surfaces, which could affect reservoir permeability. In order to better predict the geochemical impacts on long-term performance of engineered geothermal systems, we have measured chlorite, biotite, illite, and muscovite dissolution and developed generalized kinetic rate laws that are applicable over an expanded range of solution pH and temperature for each mineral. This report summarizes the rate equations for layered silicates where data were lacking for geothermal systems.

Chlorite dissolution kinetics at pH 3–10 and temperature to 275°C

DOE PAGES

Smith, Megan M.; Carroll, Susan A.

2015-12-02

Sheet silicates and clays are ubiquitous in geothermal environments. Their dissolution is of interest because this process contributes to scaling reactions along fluid pathways and alteration of fracture surfaces which could affect reservoir permeability. Here, in order to better predict the geochemical impacts on long-term performance of engineered geothermal systems, we have measured chlorite dissolution and developed a generalized kinetic rate law applicable over an expanded range of solution pH and temperature. Chlorite, (Mg,Al,Fe) 12(Si,Al) 8O 20(OH) 16, commonly occurs in many geothermal host rocks as either a primary mineral or alteration product.

Chlorite dissolution kinetics at pH 3–10 and temperature to 275°C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Megan M.; Carroll, Susan A.

Sheet silicates and clays are ubiquitous in geothermal environments. Their dissolution is of interest because this process contributes to scaling reactions along fluid pathways and alteration of fracture surfaces which could affect reservoir permeability. Here, in order to better predict the geochemical impacts on long-term performance of engineered geothermal systems, we have measured chlorite dissolution and developed a generalized kinetic rate law applicable over an expanded range of solution pH and temperature. Chlorite, (Mg,Al,Fe) 12(Si,Al) 8O 20(OH) 16, commonly occurs in many geothermal host rocks as either a primary mineral or alteration product.

Intumescent composition, foamed product prepared therewith, and process for making same

NASA Technical Reports Server (NTRS)

Riccitiello, S. R.; Parker, J. A. (Inventor)

1973-01-01

An intumescent composition and the foamed product prepared by heating are discussed wherein the composition comprises the reaction product of para-benzoquinone dioxime and a concentrated mineral acid such as sulfuric acid, phosphoric acid, and polyphosphoric acid. The composition is useful as an intumescent agent either by itself or when combined with other materials. A fire-resistant and heat-insulating composition is provided by heating the intumescent composition above its intumescent temperature.

Mineralization of wastes of human vital activity and plants to be used in a Life Support System.

PubMed

Kudenko YuA; Gribovskaya, I V; Pavlenko, R A

1997-08-01

Available methods for mineralizing wastes of human activity and inedible biomass of plants used in this country and abroad are divided into two types: dry mineralization at high temperatures up to 1270 K with subsequent partial dissolution of the ash and the other--wet oxidation by acids. In this case mineralization is performed at a temperature of 470-460 K and a pressure of 220-270 atmospheres in pure oxygen with the output of mineral solution and dissoluble sediments in the form of scale. The drawback of the first method is the formation of dioxins, CO, SO2, NO2 and other toxic compounds. The latter method is too sophisticated and is presently confined to bench testing. The here proposed method to mineralize the wastes is in mid-position between the thermal and physical chemical methods. At a temperature of 80-90 degrees C the mixture was exposed to a controlled electromagnetic field at normal atmospheric pressure. The method merits simplicity, reliability, produces no dissoluble sediment or emissions noxious for human and plants. The basic difference from the above said methods is to employ as an oxidizer atomic oxygen, its active forms including OH-radicals with hydrogen peroxide as the source. Hydrogen peroxide can be produced with electric power from water inside the Life Support System (LSS).

Massive sulfide deposition and trace element remobilization in the Middle Valley sediment-hosted hydrothermal system, northern Juan de Fuca Rdge

USGS Publications Warehouse

Houghton, J.L.; Shanks, Wayne C.; Seyfried, W.E.

2004-01-01

The Bent Hill massive sulfide deposit and ODP Mound deposit in Middle Valley at the northernmost end of the Juan de Fuca Ridge are two of the largest modern seafloor hydrothermal deposits yet explored. Trace metal concentrations of sulfide minerals, determined by laser-ablation ICP-MS, were used in conjunction with mineral paragenetic studies and thermodynamic calculations to deduce the history of fluid-mineral reactions during sulfide deposition. Detailed analyses of the distribution of metals in sulfides indicate significant shifts in the physical and chemical conditions responsible for the trace element variability observed in these sulfide deposits. Trace elements (Mn, Co, Ni, As, Se, Ag, Cd, Sb, Pb, and Bi) analyzed in a representative suite of 10 thin sections from these deposits suggest differences in conditions and processes of hydrothermal alteration resulting in mass transfer of metals from the center of the deposits to the margins. Enrichments of some trace metals (Pb, Sb, Cd, Ag) in sphalerite at the margins of the deposits are best explained by dissolution/reprecipitation processes consistent with secondary remineralization. Results of reaction-path models clarify mechanisms of mass transfer during remineralization of sulfide deposits due to mixing of hydrothermal fluids with seawater. Model results are consistent with patterns of observed mineral paragenesis and help to identify conditions (pH, redox, temperature) that may be responsible for variations in trace metal concentrations in primary and secondary minerals. Differences in trace metal distributions throughout a single deposit and between nearby deposits at Middle Valley can be linked to the history of metal mobilization within this active hydrothermal system that may have broad implications for sulfide ore formation in other sedimented and unsedimented ridge systems. ?? 2004 Elsevier Ltd.

Effect of temperature and moisture on the mineralization and humification of leaf litter in a model incubation experiment

NASA Astrophysics Data System (ADS)

Larionova, A. A.; Maltseva, A. N.; Lopes de Gerenyu, V. O.; Kvitkina, A. K.; Bykhovets, S. S.; Zolotareva, B. N.; Kudeyarov, V. N.

2017-04-01

The mineralization and humification of leaf litter collected in a mixed forest of the Prioksko-Terrasny Reserve depending on temperature (2, 12, and 22°C) and moisture (15, 30, 70, 100, and 150% of water holding capacity ( WHC)) has been studied in long-term incubation experiments. Mineralization is the most sensitive to temperature changes at the early stage of decomposition; the Q 10 value at the beginning of the experiment (1.5-2.7) is higher than at the later decomposition stages (0.3-1.3). Carbon losses usually exceed nitrogen losses during decomposition. Intensive nitrogen losses are observed only at the high temperature and moisture of litter (22°C and 100% WHC). Humification determined from the accumulation of humic substances in the end of incubation decreases from 34 to 9% with increasing moisture and temperature. The degree of humification CHA/CFA is maximum (1.14) at 12°C and 15% WHC; therefore, these temperature and moisture conditions are considered optimal for humification. Humification calculated from the limit value of litter mineralization is almost independent of temperature, but it significantly decreases from 70 to 3% with increasing moisture. A possible reason for the difference between the humification values measured by two methods is the conservation of a significant part of hemicelluloses, cellulose, and lignin during the transformation of litter and the formation of a complex of humic substances with plant residues, where HSs fulfill a protectoral role and decrease the decomposition rate of plant biopolymers.

Modeling CO2-Water-Mineral Wettability and Mineralization for Carbon Geosequestration.

PubMed

Liang, Yunfeng; Tsuji, Shinya; Jia, Jihui; Tsuji, Takeshi; Matsuoka, Toshifumi

2017-07-18

Carbon dioxide (CO 2 ) capture and storage (CCS) is an important climate change mitigation option along with improved energy efficiency, renewable energy, and nuclear energy. CO 2 geosequestration, that is, to store CO 2 under the subsurface of Earth, is feasible because the world's sedimentary basins have high capacity and are often located in the same region of the world as emission sources. How CO 2 interacts with the connate water and minerals is the focus of this Account. There are four trapping mechanisms that keep CO 2 in the pores of subsurface rocks: (1) structural trapping, (2) residual trapping, (3) dissolution trapping, and (4) mineral trapping. The first two are dominated by capillary action, where wettability controls CO 2 and water two-phase flow in porous media. We review state-of-the-art studies on CO 2 /water/mineral wettability, which was found to depend on pressure and temperature conditions, salt concentration in aqueous solutions, mineral surface chemistry, and geometry. We then review some recent advances in mineral trapping. First, we show that it is possible to reproduce the CO 2 /water/mineral wettability at a wide range of pressures using molecular dynamics (MD) simulations. As the pressure increases, CO 2 gas transforms into a supercritical fluid or liquid at ∼7.4 MPa depending on the environmental temperature. This transition leads to a substantial decrease of the interfacial tension between CO 2 and reservoir brine (or pure water). However, the wettability of CO 2 /water/rock systems depends on the type of rock surface. Recently, we investigated the contact angle of CO 2 /water/silica systems with two different silica surfaces using MD simulations. We found that contact angle increased with pressure for the hydrophobic (siloxane) surface while it was almost constant for the hydrophilic (silanol) surface, in excellent agreement with experimental observations. Furthermore, we found that the CO 2 thin films at the CO 2 -hydrophilic silica and CO 2 -H 2 O interfaces displayed a linear correlation, which can in turn explain the constant contact angle on the hydrophilic silica surface. In view of the literature and our study results, a few recommendations seem necessary to construct a molecular system suitable to study wettability with MD simulations. Future work should be conducted to determine the influence of brine salinity on the wettability of minerals with high cation exchange capacity. Mineral trapping is believed to be an extremely slow process, likely taking thousands of years. However, a recent pilot study demonstrated that CO 2 mineralization occurs within 2 years in highly reactive basalt reservoirs. A first-principles MD study has also shown that carbonation reactions occur rapidly at the surface oxygen sites of a reactive mineral. We observed carbonate ions on both a newly cleaved quartz surface (without hydrolysis), and a basalt andesine surface after hydrolysis in a CO 2 -rich environment. Future work should consider the influence of water, gas impurities, and mineral cation type on carbonation.

Progress on geoenvironmental models for selected mineral deposit types, edited by R. R. Seal, II and N. K. Foley

USGS Publications Warehouse

Seal, Robert R.; Foley, Nora K.

2002-01-01

Since the beginning of economic geology as a subdiscipline of the geological sciences, economic geologists have tended to classify mineral deposits on the basis of geological, mineralogical, and geochemical criteria, in efforts to systematize our understanding of mineral deposits as an aid to exploration. These efforts have led to classifications based on commodity, geologic setting (Cox and Singer, 1986), inferred temperatures and pressures of ore formation (Lindgren, 1933), and genetic setting (Park and MacDiarmid, 1975; Jensen and Bateman, 1979). None of these classification schemes is mutually exclusive; instead, there is considerable overlap among all of these classifications. A natural outcome of efforts to classify mineral deposits is the development of “mineral deposit models.” A mineral deposit model is a systematically arranged body of information that describes some or all of the essential characteristics of a selected group of mineral deposits; it presents a concept within which essential attributes may be distinguished and from which extraneous, coincidental features may be recognized and excluded (Barton, 1993). Barton (1993) noted that the grouping of deposits on the basis of common characteristics forms the basis for a classification, but the specification of the characteristics required for belonging to the group is the basis for a model. Models range from purely descriptive to genetic. A genetic model is superior to a descriptive model because it provides a basis to distinguish essential from extraneous attributes, and it has flexibility to accommodate variability in sources, processes, and local controls. In general, a descriptive model is a necessary prerequisite to a genetic model.

Equilibrium lithium isotope fractionation in Li-rich minerals

NASA Astrophysics Data System (ADS)

Liu, S.; Li, Y.; Liu, J.

2017-12-01

Lithium is the lightest alkali metal, and only exhibits +1 valence state in minerals. It is widely distributed on the Earth, and usually substitutes for Mg in silicate minerals. Li has two stable isotopes, 6Li and 7Li, with the relative abundances of 7.52% and 92.48%, respectively. The large mass difference between 6Li and 7Li could induce significant isotope fractionation in minerals. Li isotopes can provide an important geochemical tracer for mantle processes. However, the fractionation factors for Li in most minerals remain poorly known, which makes the geochemical implications of Li isotope fractionations in minerals difficult to assess. Here, we try to use the vibrational frequencies obtained by the first-principles methods based on density-functional theory to calculate the Li isotope fractionation parameters for amblygonite (LiAlPO4F), bikitaite (LiSi2AlO7H2), eucryptite (LiAlSiO4), lithiophilite (LiMnPO4), lithiophosphate (Li3PO4), montebrasite (LiAlPO5H), and spodumene (LiAlSi2O6) in the temperature range of 0-1200 ºC. For forsterite (Mg2SiO4) and diopside (CaMgSi2O6) in which Li takes the place of Mg, the equilibrium Li isotope fractionation between them also be studied. Our preliminary calculations show that the coordination number of Li seems to play an important role in controlling Li isotope fractionation in these minerals, and concentration of Li in forsterite and diopside seems to have great effects on Li isotope fractionation factors of them.

Characterization and origin of low-T willemite (Zn2SiO4) mineralization: the case of the Bou Arhous deposit (High Atlas, Morocco)

NASA Astrophysics Data System (ADS)

Choulet, Flavien; Barbanson, Luc; Buatier, Martine; Richard, James; Vennemann, Torsten; Ennaciri, Aomar; Zouhair, Mohamed

2017-10-01

Willemite (Zn2SiO4) usually reported in hypogene non-sulfide deposits is described as the main ore mineral in the carbonate-hosted Bou Arhous zinc deposit. This deposit is located in the High Atlas intracontinental range that formed during the Tertiary. Based on a set of microscopic observations, it was possible to establish that willemite replaces primary sphalerite. On the basis of cathodoluminescence imaging, three successive generations of willemite are distinguished, with evidence of dissolution-reprecipitation processes. Willemite is also variably enriched in Ge (up to 1000 ppm), while Ge contents lower than 100 ppm are reported in the primary sulfide minerals. Depending on the willemite generation, this substitution was positively or negatively correlated to the Zn-Pb substitution. According to the nature of zoning (sector versus oscillatory), the incorporation of Ge was either controlled by crystallographic factors or by the nature of the mineralizing fluids. Willemite is associated with other oxidation-related mineral species, like cerussite (PbCO3) but is not in isotopic equilibrium and therefore not considered to be cogenetic. Oxygen isotope compositions support the formation of willemite at temperatures below 130 °C, from mixed meteoric and deeper, hydrothermal fluids. The formation of the High Atlas Belt during the Tertiary has contributed to the exhumation of the sulfide minerals and the development of vertical conduits for percolation of meteoric water and ascending hydrothermal fluids. In addition to a local contribution of silicate minerals of the host limestone, hydrothermal fluids probably transported Si and Ge that are incorporated in willemite.

Thermomagnetic identification of manganese and iron minerals present in soils and industrial dusts

NASA Astrophysics Data System (ADS)

Wawer, Małgorzata; Rachwał, Marzena; Jabłońska, Mariola; Krzykawski, Tomasz; Magiera, Tadeusz

2017-04-01

Many industries (e.g. metallurgy, power, cement, and coking plants) constitute a sources of industrial dusts containing technogenic magnetic particles (TMP). TMP are mostly iron oxides with ferrimagnetic or antiferromagnetic properties, therefore their presence in dusts, soils and sediments can be easily detected by magnetic susceptibility measurements. TMP, thanks their specific mineral and magnetic properties, and well developed specific surface area, are characterized by a chemical affinity for some elements like heavy metals. The main objective of this study was identification of manganese and iron (hydro)oxides occurring in industrial dusts and soils being under their deposition for long time period. In principle, Mn and Fe (hydro)oxides present in these samples originate from high-temperature technological processes. Soils samples (collected from different soil horizons) taken from surroundings of power station, iron/steel and non-ferrous plants as well as metallurgical dusts and fly ashes from power stations were subjected to investigation. During the studies temperature dependent magnetic susceptibility measurements and X-ray powder diffraction analyses were applied. Thermomagnetic analyses (K-T) revealed differences between samples from particular industries, however an inflexion at 450-500°C of all curves was observed indicating a probable occurrence of maghemite- or titanomagnetite-like phases. The curves of TMP emitted by power plants have inflection at 580 °C indicating that magnetite was the main magnetic phase. In case of TMP originated from non-ferrous metal smelting additional curve deflection at 130 and 210 °C occurred relating to intermediate titanomagnetite or iron sulfides. X-ray diffraction proved the occurrence of magnetite and maghemite in almost all samples, especially connected with power industry and iron/steel metallurgy. Mineral analysis revealed that kind of industrial process influenced on the dominating mineral forms found in polluted soils and specific industrial dusts. Fly ashes were composed mainly of anhydrite (2-46%), quartz (18-33%), muscovite (0-8%), feldspar (0-8%) and hematite (2-8%), while different spinels (19-53%), hematite (0-38%), wüstite (0-40%) and additives of calcite, halite, sylvine and graphite are the components of metallurgical dusts. Dusts from non-ferrous metal smelting contain Pb and Zn minerals: zincite (1-95%), lanarkite (0-45%), gordaite (0-10%), challacoloite and sphalerite. Additionally, some rare minerals were found in these dusts, such as: anglesite, sphalerite, galena, metasideronatrite and in soil, coronadite. Acknowledgements: The research project received funding from the National Science Centre of Poland on the basis of the decision number DEC-2013/09/B/ST10/02227.

Modeling the hysteretic moisture and temperature responses of soil carbon decomposition resulting from organo-mineral interactions

NASA Astrophysics Data System (ADS)

Tang, J.; Riley, W. J.

2017-12-01

Most existing soil carbon cycle models have modeled the moisture and temperature dependence of soil respiration using deterministic response functions. However, empirical data suggest abundant variability in both of these dependencies. We here use the recently developed SUPECA (Synthesizing Unit and Equilibrium Chemistry Approximation) theory and a published dynamic energy budget based microbial model to investigate how soil carbon decomposition responds to changes in soil moisture and temperature under the influence of organo-mineral interactions. We found that both the temperature and moisture responses are hysteretic and cannot be represented by deterministic functions. We then evaluate how the multi-scale variability in temperature and moisture forcing affect soil carbon decomposition. Our results indicate that when the model is run in scenarios mimicking laboratory incubation experiments, the often-observed temperature and moisture response functions can be well reproduced. However, when such response functions are used for model extrapolation involving more transient variability in temperature and moisture forcing (as found in real ecosystems), the dynamic model that explicitly accounts for hysteresis in temperature and moisture dependency produces significantly different estimations of soil carbon decomposition, suggesting there are large biases in models that do not resolve such hysteresis. We call for more studies on organo-mineral interactions to improve modeling of such hysteresis.

Double-Sided Laser Heating in Radial Diffraction Geometry for Diamond Anvil Cell Deformation Experiments at Simultaneous High Pressures and Temperatures

NASA Astrophysics Data System (ADS)

Miyagi, L. M.; Kunz, M.; Couper, S.; Lin, F.; Yan, J.; Doran, A.; MacDowell, A. A.

2017-12-01

The rheology of rocks and minerals in the Earth's deep interior plays a primary role in controlling large scale geodynamic processes such as mantle convection and slab subduction. Plastic deformation resulting from these processes can lead to texture development and associated seismic anisotropy. If a detailed understanding of the link between deformation and seismic anisotropy is established, observations of seismic anisotropy can be used to understand the dynamic state in the deep Earth. However, performing deformation experiments at lower mantle pressure and temperature conditions are extremely challenging. Thus most deformation studies have been performed either at room temperature and high pressure or at reduced pressures and high temperature. Only a few extraordinary efforts have attained pressures and temperatures relevant to lower mantle. Therefore our ability to interpret observations of lower mantle seismic anisotropy in terms of mantle flow models remains limited. In order to expand the pressure and temperature range available for deformation of deep Earth relevant mineral phases, we have developed a laser heating system for in-situ double-sided heating in radial diffraction geometry at beamline 12.2.2 of the Advanced Light Source of Lawrence Berkeley National Laboratory. This allows texture and lattice strain measurements to be recorded at simultaneous high pressures and temperatures in the diamond anvil cell. This new system is integrated into the newly built axial laser heating system to allow for rapid and reliable transitioning between double-sided laser heating in axial and radial geometries. Transitioning to radial geometry is accomplished by redirecting the laser and imaging paths from 0° and 180° to 90° and 270°. To redirect the 90° path, a motorized periscope mirror pair with an objective lens can be inserted into the downstream axial beam path. The 270° redirection is accomplished by removing the upstream axial objective lens and manually installing a small assembly carrying 2 infrared mirrors and an objective lens. Using this system we have performed two pilot studies recording texture and lattice strain development during deformation of FeO up to 1300 K and 45 GPa and bridgmanite up to 1600 K and 80 GPa.

Modeling particulate matter emissions during mineral loading process under weak wind simulation.

PubMed

Zhang, Xiaochun; Chen, Weiping; Ma, Chun; Zhan, Shuifen

2013-04-01

The quantification of particulate matter emissions from mineral handling is an important problem for the quantification of global emissions on industrial sites. Mineral particulate matter emissions could adversely impact environmental quality in mining regions, transport regions, and even on a global scale. Mineral loading is an important process contributing to mineral particulate matter emissions, especially under weak wind conditions. Mathematical models are effective ways to evaluate particulate matter emissions during the mineral loading process. The currently used empirical models based on the form of a power function do not predict particulate matter emissions accurately under weak wind conditions. At low particulate matter emissions, the models overestimated, and at high particulate matter emissions, the models underestimated emission factors. We conducted wind tunnel experiments to evaluate the particulate matter emission factors for the mineral loading process. A new approach based on the mathematical form of a logistical function was developed and tested. It provided a realistic depiction of the particulate matter emissions during the mineral loading process, accounting for fractions of fine mineral particles, dropping height, and wind velocity. Copyright © 2013 Elsevier B.V. All rights reserved.

Mineral Reactions Involving Sapphirine and Their Application for Characterization of Metamorphic Conditions

NASA Astrophysics Data System (ADS)

Podlesskii, K. K.

2008-05-01

Assemblages of sapphirine, once considered to be a rare mineral, have in recent years been recognized as important indicators of high-temperature metamorphism. They occur in rocks that have undergone different tectono-metamorphic histories, with the P-T range of formation being estimated from below 700°C and 0.5 GPa to above 1100°C and 1.5 GPa. Sapphirine associated with quartz is attributed exclusively to the highest temperature conditions of crustal metamorphism referred to as ultrahigh-temperatiure metamorphism. Although experimental data involving sapphirine extend over an even wider P-T range, the quantitative interpretation of sapphirine-bearing assemblages remains ambiguous. Thermodynamic properties of magnesian sapphirine end-members have been optimized on the basis of experimentally constrained phase relations with the equation of state developed by Gerya et al., 2004. They differ from the model used in THERMOCALC (Kelsey et al., 2004), and the differences in the estimated stability of assemblages of sapphirine with quartz, kyanite and forsterite, to which a special attention have been paid due to their petrologic importance, look dramatic and may change interpretations of petrogenetic processes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simmons, Stuart F.; Spycher, Nicolas; Sonnenthal, Eric

This report summarizes the results of Phase I work for a go/no go decision on Phase II funding. In the first objective, we assessed the extent to which fluid-mineral equilibria controlled deep water compositions in geothermal systems across the Great Basin. Six systems were evaluated: Beowawe; Desert Peak; Dixie Valley; Mammoth; Raft River; Roosevelt. These represent a geographic spread of geothermal resources, in different geological settings and with a wide range of fluid compositions. The results were used for calibration/reformulation of chemical geothermometers that reflect the reservoir temperatures in producing reservoirs. In the second objective, we developed a reactive -transportmore » model of the Desert Peak hydrothermal system to evaluate the processes that affect reservoir fluid geochemistry and its effect on solute geothermometry. This included testing geothermometry on “reacted” thermal water originating from different lithologies and from near-surface locations where the temperature is known from the simulation. The integrated multi-component geothermometer (GeoT, relying on computed mineral saturation indices) was tested against the model results and also on the systems studied in the first objective.« less

Insights into Silicate Carbonation Processes in Water-Bearing Supercritical CO2 Fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Quin RS; Thompson, Christopher J.; Loring, John S.

2013-07-01

Long-term geologic storage of carbon dioxide (CO2) is considered an integral part to moderating CO2 concentrations in the atmosphere and subsequently minimizing effects of global climate change. Although subsurface injection of CO2 is common place in certain industries, deployment at the scale required for emission reduction is unprecedented and therefore requires a high degree of predictability. Accurately modeling geochemical processes in the subsurface requires experimental derived data for mineral reactions occurring between the CO2, water, and rocks. Most work in this area has focused on aqueous-dominated systems in which dissolved CO2 reacts to form crystalline carbonate minerals. Comparatively little laboratorymore » research has been conducted on reactions occurring between minerals in the host rock and the wet supercritical fluid phase. In this work, we studied the carbonation of wollastonite [CaSiO3] exposed to variably hydrated supercritical CO2 (scCO2) at a range of temperatures (50, 55 and 70 °C) and pressures (90,120 and 160 bar) that simulate conditions in geologic repositories. Mineral transformation reactions were followed by three novel in situ high pressure techniques, including x-ray diffraction that tracked the rate and extents of wollastonite conversion to calcite. Increased dissolved water concentrations in the supercritical CO2 resulted in increased silicate carbonation approaching ~50 wt. %. Development of thin water films on the mineral surface were directly observed with infrared spectroscopy and determined to be critical for facilitating carbonation processes. Even in extreme low water conditions, magic angle spinning nuclear magnetic resonance detected formation of Q3 [Si(OSi)3OH] and Q4 [Si(OSi)4] amorphous silica species. Unlike the thick (<10 μm) passivating silica layers observed in the fully water saturated scCO2 experiments, images obtained from a focused ion beam sectioned sample indicted these coatings were chemically wollastonite but structurally amorphous. In addition, evidence of an intermediate hydrated amorphous calcium carbonate forming under these conditions further emphasize the importance of understanding geochemical processes occurring in water bearing scCO2 fluids.« less

Frictional melting of clayey gouge during seismic fault slip: Experimental observation and implications

NASA Astrophysics Data System (ADS)

Han, Raehee; Hirose, Takehiro; Jeong, Gi Young; Ando, Jun-ichi; Mukoyoshi, Hideki

2014-08-01

Clayey gouges are common in fault slip zones at shallow depths. Thus, the fault zone processes and frictional behaviors of the gouges are critical to understanding seismic slip at these depths. We conducted rotary shear tests on clayey gouge (~41 wt % clay minerals) at a seismic slip rate of 1.3 m/s. Here we report that the gouge was melted at 5 MPa of normal stress and room humidity conditions. The initial local melting was followed by melt layer formation. Clay minerals (e.g., smectite and illite) and plagioclase were melted and quenched to glass with numerous vesicles. Both flash heating and bulk temperature increases appear to be responsible for the melting. This observation of clayey gouge melting is comparable to that of natural faults (e.g., Chelungpu fault, Taiwan). Due to heterogeneous fault zone properties (e.g., permeability), frictional melting may be one of the important processes in clayey slip zones at shallow depths.

Coordinated Chemical and Isotopic Imaging of Bells (CM2) Meteorite Matrix

NASA Technical Reports Server (NTRS)

Clemett, S. J.; Messenger, S.; Naklamura-Messenger, K.; Thomas-Keprta, K. L.

2014-01-01

Meteoritic organic matter is a complex conglomeration of species formed in distinct environments and processes in circumstellar space, the interstellar medium, the Solar Nebula and asteroids. Consequently meteorites constitute a unique record of primordial organic chemical evolution. While bulk chemical analysis has provided a detailed description of the range and diversity of organic species present in carbonaceous chondrites, there is little information as to how these species are spatially distributed and their relationship to the host mineral matrix. The distribution of organic phases is nevertheless critical to understanding parent body processes. The CM and CI chondrites all display evidence of low temperature (< 350K) aqueous alteration that may have led to aqueous geochromatographic separation of organics and synthesis of new organics coupled to aqueous mineral alteration. Here we present the results of the first coordinated in situ isotopic and chemical mapping study of the Bells meteorite using a newly developed two-step laser mass spectrometer (mu-L(sup 2)MS) capable of measuring a broad range of organic compounds.

Decoding magma plumbing and geochemical evolution beneath the Lastarria volcanic complex (Northern Chile)-Evidence for multiple magma storage regions

NASA Astrophysics Data System (ADS)

Stechern, André; Just, Tobias; Holtz, François; Blume-Oeste, Magdalena; Namur, Olivier

2017-05-01

The petrology of quaternary andesites and dacites from Lastarria volcano was investigated to reconstruct the magma plumbing and storage conditions beneath the volcano. The mineral phase compositions and whole-rock major and trace element compositions were used to constrain temperature, pressure and possible mechanisms for magma differentiation. The applied thermobarometric models include two-pyroxene thermobarometry, plagioclase-melt thermometry, amphibole composition thermobarometry, and Fe-Ti oxide thermo-oxybarometry. The overall temperature estimation is in the range 840 °C to 1060 °C. Calculated oxygen fugacity ranges between NNO to NNO + 1. Results of the geo-barometric calculations reveal multiple magma storage regions, with a distinct storage level in the uppermost crust ( 6.5-8 km depth), a broad zone at mid-crustal levels ( 10-18 km depth), and a likely deeper zone at intermediate to lower crustal levels (> 20 km depth). The highest temperatures in the range 940-1040 °C are recorded in minerals stored in the mid-crustal levels ( 10-18 km depth). The whole-rock compositions clearly indicate that magma mixing is the main parameter controlling the general differentiation trends. Complex zoning patterns and textures in the plagioclase phenocrysts confirm reheating and remobilization processes due to magma replenishment.

An integrated monitoring network for hydrologic, geochemical, and sediment fluxes to characterize carbon-mineral fate in the Christina River Basin Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Sawyer, A. H.; Karwan, D. L.; Lazareva, O.

2011-12-01

Organic carbon (C) -mineral complexation mechanism plays an important role in C sequestration within watersheds. The primary goal of the Christina River Basin Critical Zone Observatory in SE Pennsylvania and N Delaware, USA (one of six National Science Foundation-funded observatories) is to quantify net carbon sink or source due to mineral production and transport and its dependence on land use. This effort requires an interdisciplinary understanding of carbon and mineral fluxes across interfaces between soil, aquifer, floodplain, and river. We have established a monitoring network that targets hydrologic, geochemical, and sedimentological transport processes across channel-floodplain-aquifer interfaces within White Clay Creek Watershed. Within the channel, suspended material is sampled and analyzed for organic and mineral composition as well as geochemical fingerprints. Surface water and groundwater are analyzed for C, Fe, and Mn chemistry. Within the floodplain, in-situ sensors monitor soil moisture, pressure, temperature, conductivity, and redox potential. Integrated data analysis should yield estimates of water and solute fluxes between the vadose zone, riparian aquifer, and stream. Our preliminary data show that storm events are important for carbon and mineral fluxes-suspended material in surface water changes in source and composition throughout the storm. Meanwhile, the variation in stream stage drives surface water-groundwater exchange, facilitating changes in redox potential and providing opportunity for enhanced transport and reactions involving C, Fe, and Mn in the riparian aquifer.

Soil organic carbon quality in forested mineral wetlands at different mean annual temperature.

Treesearch

Cinzia Fissore; Christian P. Giardina; Randall K. Kolka; Carl C. Trettin

2009-01-01

Forested mineral soil wetlands (FMSW) store large stocks of soil organic carbon (SOC), but little is known on: (i) whether the quality of SOC stored in these soils (proportion of active versus more resistant SOC compounds) differs from SOC in upland soils; (ii) how the quality of SOC in FMSW varies with mean annual temperature (MAT); and (iii) whether SOC decomposition...

Mineral Selection for Multicomponent Equilibrium Geothermometry

DOE PAGES

Plamer, C. D.; Ohly, S. R.; Smith, R. W.; ...

2015-04-01

Multicomponent geothermometry requires knowledge of the mineral phases in the reservoir with which the geothermal fluids may be equilibrated. These minerals phases are most often alteration products rather than primary minerals. We have reviewed the literature on geothermal systems representing most major geologic environments typically associated with geothermal activity and identified potential alteration products in various environments. We have included this information in RTEst, a code we have developed to estimate reservoir conditions (temperature, CO 2 fugacity) from the geochemistry of near-surface geothermal waters. The information has been included in RTEst through the addition of filters that decrease the potentialmore » number of minerals from all possibilities based on the basis species to those that are more relevant to the particular conditions in which the user is interested. The three groups of filters include host rock type (tholeiitic, calc-alkaline, silicic, siliciclastic, carbonate), water type (acidic, neutral), and the temperature range over which the alteration minerals were formed (low, medium, high). The user-chosen mineral assemblage is checked to make sure that it does not violate the Gibbs phase rule. The user can select one of three mineral saturation weighting schemes that decrease the chance the optimization from being skewed by reaction stoichiometry or analytical uncertainty.« less

Magnetic properties of chemical remanent magnetization in synthetic and natural goethite - Prospects for a natural remanent magnetization/thermoremanent magnetization ratio paleomagnetic stability test?

NASA Astrophysics Data System (ADS)

Dekkers, Mark J.; Rochette, Pierre

1992-11-01

Results are presented of measurements of chemical remanent magnetization properties in natural goethite and in goethite samples synthesized under controlled field conditions (horizontally directed field of 0.30 mT) at 30 C and 55 C, with and without the presence of microfiber glass filters. Results indicate that both the temperature and the presence of a substrate (microfiber glass filters) affect the goethite aging process and the magnetic properties of the resulting goethite. The goethite aging from ferrihydrite was much faster at 55 C than at 30 C, likely because of increased ion diffusion velocity in solution. Results of goethite aging in the presence of other mineral substrate (gibbsite) indicate that the type of mineral substrate is important.

Coal liquefaction process

DOEpatents

Wright, C.H.

1986-02-11

A process is described for the liquefaction of coal wherein raw feed coal is dissolved in recycle solvent with a slurry containing recycle coal minerals in the presence of added hydrogen at elevated temperature and pressure. The highest boiling distillable dissolved liquid fraction is obtained from a vacuum distillation zone and is entirely recycled to extinction. Lower boiling distillable dissolved liquid is removed in vapor phase from the dissolver zone and passed without purification and essentially without reduction in pressure to a catalytic hydrogenation zone where it is converted to an essentially colorless liquid product boiling in the transportation fuel range. 1 fig.

Mineralogy of new Antarctic achondrites with affinity to Lodran and a model of their evolution in an asteroid

NASA Technical Reports Server (NTRS)

Takeda, Hiroshi; Mori, Hiroshi; Hiroi, Takahiro; Saito, Jun

1994-01-01

We studied five new Antartic achondrites, MacAlpine Hills (MAC) 88177, Yamato (Y)74357, Y75274, Y791491 and Elephant Moraine (EET)84302 by mineralogical techniques to gain a better understanding of the mineral assemblages of a group of meteorites with an affinity to Lodran (stony-iron meteorite) and their formation processes. This group is being called lodranites. These meteorites contain major coarse-grained orthopyroxene (Opx) and olivine as in Lodran and variable amounts of FeNi metal and troilite etc. MAC88177 has more augite and less FeNi than Lodran; Y74357 has more olivine and contains minor augite; Y791491 contains in addition plagioclase. EET84302 has an Acapulco-like chondritic mineral assembladge and is enriched in FeNi metal and plagioclase, but one part is enriched in Opx and chromite. The EET84302 and MAC88177 Opx crystals have dusty cores as in Acapulco. EET84302 and Y75274 are more Mg-rich than other members of the lodranite group, and Y74357 is intermediate. Since these meteorites all have coarse-grained textures, similar major mineral assemblages, variable amounts of augite, plagioclase, FeNi metal, chromite and olivine, we suggest that they are related and are linked to a parent body with modified chondritic compositions. The variability of the abundances of these minerals are in line with a proposed model of the surface mineral assemblages of the S asteroids. The mineral assemblages can best be explained by differing degrees of loss or movements of lower temperature partial melts and recrystallization, and reduction. A portion of EET84302 rich in metal and plagioclase may represent a type of component removed from the lodranite group meteorites. Y791058 and Caddo County, which were studied for comparison, are plagioclase-rich silicate inclusions in IAB iron meteorites and may have been derived by similar process but in a different body.

Overview of the evolution of clay mineralogy in the Gulf of Mexico: implications for regional climate and drainage history of the Mississippi and Brazos-Trinity Rivers

NASA Astrophysics Data System (ADS)

Adatte, T.; John, C. M.; Flemings, P. B.; Behrmann, J.

2005-12-01

In this paper we present the overview and preliminary results of the analysis of clay minerals in two mini basins drilled during IODP Expedition 308. The goal of our project is to explore the vertical and temporal trends in clay mineralogy in the Ursa Basin and the Brazos-Trinity basin #4. The Brazos-Trinity basin was the sink for sands and clays carried by the Brazos and Trinity Rivers, while the Ursa basin was the sink for sediments carried by the Mississippi river. Reconstructing clay minerals (phyllosilicates <2μm in size) accumulations at these locations could thus potentially yield information on changes in the transport and the source of the siliclastic material transported in the course of the Pleistocene by these three rivers. Moreover, because the type of clay formed in soils through weathering processes largely depend on temperature and amount of precipitation, the dataset generated could provide clues on past climate changes. Some of the mechanisms that are hypothesized to play a major role in controlling clay accumulation in the basins investigated are reworking of clays on the American continent (controlled at the time-scale investigated here by changes in precipitation) and turbidity current deposition (controlled mainly by sea-level changes and thus glacio-eustasy). Finally, a major focusing point of Expedition 308 was sediment physical properties in an overpressured basin. Because each clay mineral specie has a specific average grain sizes, physical properties and cation exchange capacity, the clay mineral composition of the sediment investigated here (dominated by clay-sized particles) may partly control how these sediments react to changes in pressure and temperature. Thus, clay mineral data could contribute to our understanding of the physical properties of the sediments in overpressured basins, and collaborations with geotechnical scientist are planned.

Iron isotopic systematics of pyroxenite xenoliths from North China Craton: implications for Melt-rock interaction in the sub-continental lithospheric mantle beneath eastern China

NASA Astrophysics Data System (ADS)

Zhao, X.; Cao, H.; Yu, H.; Huang, F.

2016-12-01

Iron isotope systems have become widely used tools in high temperature geochemistry and provide important constraints on mantle dynamics. Here, we report Fe isotopic data on a series of pyroxenite xenoliths from Hannuoba, North China Craton to further constrain the Fe isotopic composition of the mantle and investigate the behavior of Fe isotopes during mantle processes. These xenoliths range from Cr- pyroxenites, Al-pyroxenites to garnet pyroxenites, and are taken as physical evidence for different episodes of melt injection events. Our results show that both Cr- pyroxenites and Al-pyroxenites have a narrow range of Fe isotopes (δ57Fe=-0.01 to 0.09), similar to that reported typical mantle peridotites and they show equilibrium inter-mineral Fe isotope fractionation between coexisting mantle minerals. In contract, the garnet pyroxenites, which are products of reaction between a silicate melt and peridotite, exhibit larger Fe isotopic variations, with δ57Fe ranging from 0.08 to 0.30. The δ57Fe values of minerals in these garnet pyroxenites also vary widely from -0.25 to -0.03 in olivines, from -0.04 to 0.14 in orthopyroxenes, from -0.07 to 0.31 in clinopyroxenes, from 0.07 to 0.26 in spinels and from 0.30 to 0.39 in garnets. These observed data stand in marked contrast to the calculated equilibrium Fe isotope fractionation between coexisting mantle minerals at mantle temperature from theory, indicating disequilibrium isotope fractionation. The disequilibrium isotope fractionations between coexisting mantle minerals in garnet pyroxenites most likely reflect kinetic isotope fractionation during melt-peridotite interaction. In addition, the phlogopite clinopyroxenite with an apparent metasomatic overprint has the heaviest δ57Fe (as high as 1.00) but lightest δ26Mg (as low as -1.50) values of the investigated samples. Our study shows that mantle metasomatism plays an important role in producing Fe isotopic heterogeneity of the subcontinental mantle.

Inferences from Microfractures and Geochemistry in Dynamic Shale-CO2 Packed Bed Experiments

NASA Astrophysics Data System (ADS)

Radonjic, M.; Olabode, A.

2016-12-01

Subsurface storage of large volumes of carbondioxide (CO2) is expected to have long term rock-fluid interactions impact on reservoir and seal rocks properties. Caprocks, particularly sedimentary types, are the ultimate hydraulic barrier in carbon sequestration. The mineralogical components of sedimentary rocks are geochemically active under enormous earth stresses, which generate high pressure and temperature conditions. It has been postulated that in-situ mineralization can lead to flow impedance in natural fractures in the presence of favorable geochemical and thermodynamic conditions. This experimental modelling research investigated the impact of in-situ geochemical precipitation on conductivity of fractures. Geochemical analyses were performed on four different samples of shale rocks, effluent fluids and recovered precipitates both before and after CO2-brine flooding of crushed shale rocks at moderately high temperature and pressure conditions. The results showed that most significant diagenetic changes in shale rocks after flooding with CO2-brine, reflected in the effluent fluid with predominantly calcium based minerals dissolving and precipitating under experimental conditions. Major and trace elements in the effluent (using ICP-OES analysis) indicated that multiple geochemical reactions are occurring with almost all of the constituent minerals participating. The geochemical composition of precipitates recovered after the experiments showed diagenetic carbonates and opal as the main constituents. The bulk rock showed little changes in composition except for sharper and more refined peaks on XRD analysis, suggesting that a significant portion of the amorphous content of the rocks have been removed via dissolution by the slightly acid CO2-brine fluid that was injected. Micro-indentation results captured slight reduction in the hardness of the shale rocks and this reduction appeared dependent on diagenetic quartz content. It can be inferred that convective reactive transport of dissolved minerals are involved in nanoscale precipitation-dissolution processes in shale. This reactive transport of dissolved minerals can occlude micro-fracture flow paths, thereby improving shale caprock seal integrity with respect to leakage risk under CO2 sequestration conditions.

Geochemical and textural characterization of phosphate accessory phases in the vein assemblage and metasomatically altered Llallagua tin porphyry

NASA Astrophysics Data System (ADS)

Betkowski, Wladyslaw B.; Rakovan, John; Harlov, Daniel E.

2017-09-01

Petrographic and geochemical characterization of phosphate accessory minerals represents a powerful tool in understanding the mineralization and metasomatic history of one of the world's biggest tin deposits, the Siglo XX mine, Salvadora stock, Llallagua, Bolivia. The Llallagua tin deposit lies in a hydrothermally altered porphyry stock that is part of the subduction-related Bolivian tin belt. Despite numerous studies, there is still a debate over the timing and characteristics of mineralization history of the deposit. Primary igneous fluorapatite and monazite (for the first time) were recognized in the altered porphyry. The igneous monazite is enriched in Th, unlike the hydrothermal monazite that is recognized for its low Th concentration. Fluorapatite, monazite, and xenotime also coexist with cassiterite within the hydrothermal vein assemblage. Fluorapatite and xenotime are essentially pristine. Monazite, however, shows various degrees of alteration in the form of regenerative mineral replacement (RMR). This exemplifies differential reactivity and selective mineral replacement/alteration of three accessory phosphate minerals, that are all important geochemical tracers of magmatic and hydrothermal processes, and which can all be used as geochronometers. Mineral textures and composition in the altered porphyry and vein assemblages have been evaluated. Monazite-xenotime geothermometry indicates monazite crystallization beginning around 550 °C. Monazite continues to grow as temperatures gradually decrease to about 300 °C, when most of cassiterite precipitation occurred in the samples studied. The primary mechanism of phosphate alteration has been identified as a coupled dissolution-reprecipitation process, which led to REE exchange in the igneous fluorapatite and hydrothermal monazite. In Type I local alteration, La and Pr-Nd show continuity across the pre- and post- alteration concentric zones indicating that they were not affected by alteration. This is an example of a selective elemental exchange during coupled dissolution-precipitation. Type II, pervasive post-growth alteration, is evident by the presence of micro-porosity and the formation of secondary, reaction induced minerals. Release of HREE from the monazite goes into the formation of void filling xenotime inclusions; the first documentation of this metasomatic alteration product in monazite. A well-documented discrepancy exists among ages determined from the zircon, fluorapatite, monazite, and altered porphyry minerals. These observations, regarding selective alteration of fluorapatite and monazite, may help to elucidate the reasons for this discrepancy.

Reduced radiative conductivity of low spin FeO6-octahedra in FeCO3 at high pressure and temperature

NASA Astrophysics Data System (ADS)

Lobanov, Sergey S.; Holtgrewe, Nicholas; Goncharov, Alexander F.

2016-09-01

The ability of Earth's mantle to conduct heat by radiation is determined by optical properties of mantle phases. Optical properties of mantle minerals at high pressure are accessible through diamond anvil cell experiments, but because of the intense thermal radiation at T > 1000 K such studies are limited to lower temperatures. Accordingly, radiative thermal conductivity at mantle conditions has been evaluated with the assumption of the temperature-independent optical properties. Particularly uncertain is the temperature-dependence of optical properties of lower mantle minerals across the spin transition, as the spin state itself is a strong function of temperature. Here we use laser-heated diamond anvil cells combined with a pulsed ultra-bright supercontinuum laser probe and a synchronized time-gated detector to examine optical properties of high and low spin ferrous iron at 45-73 GPa up to 1600 K in an octahedral crystallographic unit (FeO6), one of the most abundant building blocks in the mantle. Siderite (FeCO3) is used as a model for FeO6-octahedra as it contains no ferric iron and exhibits a sharp optically apparent pressure-induced spin transition at 44 GPa, simplifying data interpretation. We find that the optical absorbance of low spin FeO6 increases with temperature due to the partially lifted Laporte selection rule. The temperature-induced low-to-high spin transition, however, results in a dramatic drop in absorbance of the FeO6 unit in siderite. The absorption edge (Fe-O charge transfer) red-shifts (∼1 cm-1/K) with increasing temperature and at T > 1600 K and P > 70 GPa becomes the dominant absorption mechanism in the visible range, suggesting its superior role in reducing the ability of mantle minerals to conduct heat by radiation. This implies that the radiative thermal conductivity of analogous FeO6-bearing minerals such as ferropericlase, the second most abundant mineral in the Earth's lower mantle, is substantially reduced approaching the core-mantle boundary conditions.

Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS: Application to Analysis of Experimentally Derived Hydrothermal Mineral-Catalyzed Organic Products

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Fu, Qi; Niles, Paul B.; Gibson, Everett K., Jr.

2012-01-01

We report results of experiments to measure the H isotope composition of organic acids and alcohols. These experiments make use of a pyroprobe interfaced with a GC and high temperature extraction furnace to make quantitative H isotope measurements. This work compliments our previous work that focused on the extraction and analysis of C isotopes from the same compounds [1]. Together with our carbon isotope analyses our experiments serve as a "proof of concept" for making C and H isotope measurements on more complex mixtures of organic compounds on mineral surfaces in abiotic hydrocarbon formation processes at elevated temperatures and pressures. Our motivation for undertaking this work stems from observations of methane detected within the Martian atmosphere [2-5], coupled with evidence showing extensive water-rock interaction during Mars history [6-8]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization [9,10]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [11-13]. Our H isotope measurements utilize an analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). This technique is designed to carry a split of the pyrolyzed GC-separated product to a Thermo DSQII quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

First-Row Transition Metal Doping in Calcium Phosphate Bioceramics: A Detailed Crystallographic Study

PubMed Central

Renaudin, Guillaume; Gomes, Sandrine; Nedelec, Jean-Marie

2017-01-01

Doped calcium phosphate bioceramics are promising materials for bone repair surgery because of their chemical resemblance to the mineral constituent of bone. Among these materials, BCP samples composed of hydroxyapatite (Ca10(PO4)6(OH)2) and β-TCP (Ca3(PO4)2) present a mineral analogy with the nano-multi-substituted hydroxyapatite bio-mineral part of bones. At the same time, doping can be used to tune the biological properties of these ceramics. This paper presents a general overview of the doping mechanisms of BCP samples using cations from the first-row transition metals (from manganese to zinc), with respect to the applied sintering temperature. The results enable the preparation of doped synthetic BCP that can be used to tailor biological properties, in particular by tuning the release amounts upon interaction with biological fluids. Intermediate sintering temperatures stabilize the doping elements in the more soluble β-TCP phase, which favors quick and easy release upon integration in the biological environment, whereas higher sintering temperatures locate the doping elements in the weakly soluble HAp phase, enabling a slow and continuous supply of the bio-inspired properties. An interstitial doping mechanism in the HAp hexagonal channel is observed for the six investigated cations (Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with specific characteristics involving a shift away from the center of the hexagonal channel (Fe3+, Co2+), cationic oxidation (Mn3+, Co3+), and also cationic reduction (Cu+). The complete crystallochemical study highlights a complex HAp doping mechanism, mainly realized by an interstitial process combined with calcium substitution for the larger cations of the series leading to potentially calcium deficient HAp. PMID:28772452

Geomicrobial Optical Logging Detectors (GOLD)

NASA Astrophysics Data System (ADS)

Bramall, N. E.; Stoker, C. R.; Price, P. B.; Coates, J. D.; Allamandola, L. J.; Mattioda, A. L.

2008-12-01

We will present concepts for downhole instrumentation that could be used in the Deep Underground Science and Engineering Laboratory (DUSEL). We envision optical borehole-logging instruments that could monitor bacterial concentration, mineralogy, aromatic organics, temperature and oxygen concentration, allowing for the in situ monitoring of time-dependent microbial and short-scale geologic processes and provide valuable in situ data on stratigraphy to supplement core analyses, especially where instances of missing or damaged core sections make such studies difficult. Incorporated into these instruments will be a sampling/inoculation tool to allow for the recovery and/or manipulation of particularly interesting sections of the borehole wall for further study, enabling a series of microbiological studies. The borehole tools we will develop revolve around key emerging technologies and methods, some of which are briefly described below: 1) Autofluorescence Spectroscopy: Building on past instruments, we will develop a new borehole logger that searches for microbial life and organics using fluorescence spectroscopy. Many important organic compounds (e.g. PAHs) and biomolecules (e.g. aromatic amino acids, proteins, methanogenic coenzymes) fluoresce when excited with ultraviolet and visible light. Through the careful selection of excitation wavelength(s) and temporal gating parameters, a borehole logging instrument can detect and differentiate between these different compounds and the mineral matrix in which they exist. 2) Raman Spectroscopy: Though less sensitive than fluorescence spectroscopy, Raman spectroscopy is more definitive: it can provide important mineral phase distribution/proportions and other chemical data enabling studies of mineralogy and microbe-mineral interactions (when combined with fluorescence). 3) Borehole Camera: Imaging of the borehole wall with extended information in the UV, visible, and NIR for a more informative view can provide a lot of insight to in situ processes. 4) Temperature and Oxygen Sensors: The ambient temperature will be recorded as well as the presence of oxygen. Oxygen presence can be measured using a fluorescence quenching fiber optic probe to avoid interference from other gases. We forsee that this technology will enable experiments including studies of gene transfer, microbial habitat, in situ stratigraphy and hydrological processes. In addition, though designed to scan borehole walls, GOLD could be used to scan core samples as they are recovered for rapid quantification and analysis in order to discover samples of particular interest that could then be prioritized for more in-depth, traditional analysis.

Soil Organic Carbon and Nitrogen in the 21st Century: Projections of the Responses of an Old-Growth Douglas-Fir Forest in the Pacific Northwest under RCP 4.5 and RCP 8.5 Climate Change Scenarios

NASA Astrophysics Data System (ADS)

Dong, Z.; Driscoll, C. T.; Hayhoe, K.; Pourmokhtarian, A.; Stoner, A. M. K.

2015-12-01

The biogeochemical model, PnET-BGC, was applied to Watershed 2 in H. J. Andrews Experimental Forest, Oregon, to project ecosystem carbon and nitrogen responses under different future climate change scenarios. Downscaled climate change inputs derived from two IPCC scenarios (RCP 4.5 and RCP 8.5) were interpreted by four Atmosphere-Ocean General Circulation Models (AOGCMs) at Andrews Forest. Model results showed decreases in foliar production under high temperature/CO2 scenarios due to increasing vapor pressure deficit. Projections by PnET-BGC suggest that under future climate changes in primary production coupled with an increasing rate of decomposition may result in decreases in litterfall carbon and nitrogen and soil organic carbon and nitrogen. Such changes in soil organic carbon and nitrogen may cause wide range of changes in ecosystem processing of nitrogen and carbon, such as nitrogen mineralization, plant NH4+ uptake, and stream NH4+ and dissolved organic carbon concentrations depending on climate change scenario considered. Under most high emission scenarios, net nitrogen mineralization and plant NH4+ uptake are projected to increase until the end of this century as result of increasing temperature and associated higher rates of decomposition. An accumulation of nitrogen in plant tissue due to decreasing litterfall decreases plant demand for nitrogen. Such changes in nitrogen mineralization and uptake will result in increase in stream NH4+ concentrations under high emission scenarios. Under low emission scenarios, net nitrogen mineralization and plant NH4+ uptake are projected to increase up to mid-century, then slightly decrease until the end of the century.

The effect of bonding environment on iron isotope fractionation between minerals at high temperature

NASA Astrophysics Data System (ADS)

Sossi, Paolo A.; O'Neill, Hugh St. C.

2017-01-01

Central to understanding the processes that drive stable isotope fractionation in nature is their quantification under controlled experimental conditions. The polyvalent element iron, given its abundance in terrestrial rocks, exerts controls on the structural and chemical properties of minerals and melts. The iron isotope compositions of typical high temperature minerals are, however, poorly constrained and their dependence on intensive (e.g. fO2) and extensive (e.g. compositional) variables is unknown. In this work, experiments involving a reference phase, 2 M FeCl2·4H2O(l), together with an oxide mix corresponding to the bulk composition of the chosen mineral were performed in a piston cylinder in Ag capsules. The oxide mix crystallised in situ at 1073 K and 1 GPa, in equilibrium with the iron chloride, and was held for 72 h. In order to characterise the effect of co-ordination and oxidation state on the isotope composition independently, exclusively Fe2+ minerals were substituted in: VIII-fold almandine, VI-fold ilmenite, fayalite and IV-fold chromite and hercynite. Δ57FeMin-FeCl2 increases in the order VIII < VI < IV, consistent with a decrease in the mean Fe-O bond length. Magnetite, which has mixed VI- and IV-fold co-ordination, has the heaviest Δ57Fe by virtue of 2/3 of its iron being the smaller, ferric ion. The composition of the VIFe2+-bearing minerals is similar to that of the aqueous FeCl2 fluid. To the degree that this represents the speciation of iron in fluids exsolving from magmas, the fractionation between them should be small, unless the iron is hosted in magnetite. By contrast, predominantly Fe2+-bearing mantle garnets should preserve a much lighter δ57Fe than their lower pressure spinel counterparts, a signature that may be reflected in partial melts from these lithologies. As the Fe-O bond lengths in fayalite and ilmenite are comparable, their isotope compositions overlap, suggesting that high Ti mare basalts acquired their heavy isotopic signature from ilmenite that crystallised late during lunar magma ocean solidification.

Tracking Hydrothermal Fluid Pathways from Surface Alteration Mineralogy: The Case of Licancura Geothermal Field, Northern Chile

NASA Astrophysics Data System (ADS)

Camus, E.; Elizalde, J. D.; Morata, D.; Wechsler, C.

2017-12-01

In geothermal systems alteration minerals are evidence of hot fluid flow, being present even in absence of other surface manifestations. Because these minerals result from the interaction between geothermal fluids and surrounding host rocks, they will provide information about features of thermal fluids as temperature, composition and pH, allowing tracking their changes and evolution. In this work, we study the Licancura Geothermal field located in the Andean Cordillera in Northern Chile. The combination of Principal Components Analysis on ASTER-L1T imagery and X Ray Diffraction (XRD) allow us to interpret fluid conditions and the areas where fluid flow took place. Results from red, green, blue color composite imagery show the presence of three types of secondary paragenesis. The first one corresponds to hematite and goethite, mainly at the east of the area, in the zone of eroded Pliocene volcanic edifices. The second one, mainly at the center of the area, highlighting propylitic alteration, includes minerals such as chlorite, illite, calcite, zeolites, and epidote. The third paragenesis, spatially related to the intersection between faults, represents advanced argillic alteration, includes minerals as alunite, kaolinite, and jarosite. XRD analysis support results from remote sensing techniques. These results suggest an acid pH hydrothermal fluid reaching temperatures at surface up to 80-100°C, which used faults as a conduit, originating advanced argillic minerals. The same fluid was, probably, responsible for propylitic paragenesis. However, iron oxides paragenesis identified in the area of eroded volcanoes probably corresponds to other processes associated with weathering rather than geothermal activity. In this work, we propose the applicability of remote sensing techniques as a first level exploration tool useful for high-altitude geothermal fields. Detailed clay mineral studies (XRD and SEM) would allow us to a better characterization of the geothermal fluid flow and the defining fluid pathways in the Licancura geothermal field. This work is a contribution to the FONDAP-CONICYT 15090013 Project. E.C. thanks CONICYT for her Ph.D. grant.

The life cycle of a mineral deposit: a teacher's guide for hands-on mineral education activities

USGS Publications Warehouse

Frank, Dave; Galloway, John; Assmus, Ken

2005-01-01

This teacher's guide defines what a mineral deposit is and how a mineral deposit is identified and measured, how the mineral resources are extracted, and how the mining site is reclaimed; how minerals and mineral resources are processed; and how we use mineral resources in our every day lives. Included are 10 activitybased learning exercises that educate students on basic geologic concepts; the processes of finding, identifying, and extracting the resources from a mineral deposit; and the uses of minerals. The guide is intended for K through 12 Earth science teachers and students and is designed to meet the National Science Content Standards as defined by the National Research Council (1996). To assist in the understanding of some of the geology and mineral terms, see the Glossary (appendix 1) and Minerals and Their Uses (appendix 2). The process of finding or exploring for a mineral deposit, extracting or mining the resource, recovering the resource, also known as beneficiation, and reclaiming the land mined can be described as the “life cycle” of a mineral deposit. The complete process is time consuming and expensive, requiring the use of modern technology and equipment, and may take many years to complete. Sometimes one entity or company completes the entire process from discovery to reclamation, but often it requires multiple groups with specialized experience working together. Mineral deposits are the source of many important commodities, such as copper and gold, used by our society, but it is important to realize that mineral deposits are a nonrenewable resource. Once mined, they are exhausted, and another source must be found. New mineral deposits are being continuously created by the Earth but may take millions of years to form. Mineral deposits differ from renewable resources, such as agricultural and timber products, which may be replenished within a few months to several years.

Linking Microbial Dynamics and Physicochemical Processes in High-temperature Acidic Fe(III)- Mineralizing Systems

NASA Astrophysics Data System (ADS)

Inskeep, W.

2014-12-01

Microbial activity is responsible for the mineralization of Fe(III)-oxides in high-temperature chemotrophic communities that flourish within oxygenated zones of low pH (2.5 - 4) geothermal outflow channels (Yellowstone National Park, WY). High-temperature Fe(II)-oxidizing communities contain several lineages of Archaea, and are excellent model systems for studying microbial interactions and spatiotemporal dynamics across geochemical gradients. We hypothesize that acidic Fe(III)-oxide mats form as a result of constant interaction among primary colonizers including Hydrogenobaculum spp. (Aquificales) and Metallosphaera spp. (Sulfolobales), and subsequent colonization by archaeal heterotrophs, which vary in abundance as a function of oxygen, pH and temperature. We are integrating a complementary suite of geochemical, stable isotope, genomic, proteomic and modeling analyses to study the role of microorganisms in Fe(III)-oxide mat development, and to elucidate the primary microbial interactions that are coupled with key abiotic events. Curated de novo assemblies of major phylotypes are being used to analyze additional -omics datasets from these microbial mats. Hydrogenobaculum spp. (Aquificales) are the dominant bacterial population(s) present, and predominate during early mat development (< 30 d). Other Sulfolobales populations known to oxidize Fe(II) and fix carbon dioxide (e.g., Metallosphaera spp.) represent a secondary stage of mat development (e.g., 14 - 30 d). Hydrogenobaculum filaments appear to promote the nucleation and subsequent mineralization of Fe(III)-oxides, which likely affect the growth and turnover rates of these organisms. Other heterotrophs colonize Fe(III)-oxide mats during succession (> 30 d), including novel lineages of Archaea and representatives within the Crenarchaeota, Euryarchaeota, Thaumarchaeota and Nanoarchaeota. In situ oxygen consumption rates show that steep gradients occur within the top 1 mm of mat surface, and which correlate with changes in the abundance of different organisms that occupy these microenvironments. The relative consumption of oxygen by different members of Fe(II)-oxidizing mat communities has implications for autotroph-heterotroph associations and the dynamic micromorphology of active Fe(III)-oxide terraces.

Effects of mineral nutrition conditions on heat tolerance of chufa (Сyperus esculentus L.) plant communities to super optimal air temperatures in the BTLSS

NASA Astrophysics Data System (ADS)

Shklavtsova, E. S.; Ushakova, S. A.; Shikhov, V. N.; Anishchenko, O. V.

2014-09-01

The use of mineralized human wastes as a basis for nutrient solutions will increase the degree of material closure of bio-technical human life support systems. As stress tolerance of plants is determined, among other factors, by the conditions under which they have been grown before exposure to a stressor, the purpose of the study is to investigate the level of tolerance of chufa (Cyperus esculentus L.) plant communities grown in solutions based on mineralized human wastes to a damaging air temperature, 45 °C. Experiments were performed with 30-day-old chufa plant communities grown hydroponically, on expanded clay aggregate, under artificial light, at 690 μmol m-2 s-1 PAR and at a temperature of 25 °C. Plants were grown in Knop’s solution and solutions based on human wastes mineralized according to Yu.A. Kudenko’s method, which contained nitrogen either as ammonium and urea or as nitrates. The heat shock treatment lasted 20 h at 690 and 1150 μmol m-2 s-1 PAR. Chufa heat tolerance was evaluated based on parameters of CO2 gas exchange, the state of its photosynthetic apparatus (PSA), and intensity of peroxidation of leaf lipids. Chufa plants grown in the solutions based on mineralized human wastes that contained ammonium and urea had lower heat tolerance than plants grown in standard mineral solutions. Heat tolerance of the plants grown in the solutions based on mineralized human wastes that mainly contained nitrate nitrogen was insignificantly different from the heat tolerance of the plants grown in standard mineral solutions. A PAR intensity increase from 690 μmol m-2 s-1 to 1150 μmol m-2 s-1 enhanced heat tolerance of chufa plant communities, irrespective of the conditions of mineral nutrition under which they had been grown.

The formation of the dolomite-analogue norsethite: Reaction pathway and cation ordering

NASA Astrophysics Data System (ADS)

Pimentel, Carlos; Pina, Carlos M.

2014-10-01

Reaction pathways and cation ordering mechanisms involved in the formation of the mineral dolomite in nature still remain poorly understood. This is mainly due to the experimental problems posed by the synthesis of dolomite at ambient conditions, which preclude monitoring its formation in reasonable time scales. However, processes leading to the crystallization of fully-ordered dolomite-like structures can be studied by conducting experiments with mineral analogues, which are more readily precipitated. In this paper we present a study of the formation of the dolomite-analogue norsethite [BaMg(CO3)2] from a slurry which was aged at room temperature during 14 days. We found that norsethite forms by two dissolution-crystallization reactions from an initial amorphous nano-sized precipitate. The first reaction produces a mineral assemblage composed by witherite [BaCO3], northupite [Na3Mg(CO3)2Cl] and norsethite. The second dissolution-crystallization process leads to the almost complete depletion of witherite and northupite in favor of norsethite. While the composition of norsethite crystals rapidly reaches a Ba/Mg = 1 ratio, X-ray diffraction peaks indicate an increase in the crystallinity of those crystals during the first 48 h of reaction. Simultaneously, Ba-Mg cation ordering increases, as shown by the evolution of intensity ratios of certain superstructure and structure reflections. Altogether, these results demonstrate that the formation of fully-ordered norsethite occurs by a sequence of solvent-mediated processes which involve a number of precursors. Our study also suggests that similar processes might lead to the formation of dolomite in natural environments.

A ferroelectric model for the low emissivity highlands on Venus

NASA Technical Reports Server (NTRS)

Shepard, Michael K.; Arvidson, Raymond E.; Brackett, Robert A.; Fegley, Bruce, Jr.

1994-01-01

A model to explain the low emissivity venusian highlands is proposed utilizing the temperature-dependent dielectric constant of ferroelectric minerals. Ferroelectric minerals are known to occur in alkaline and carbonite rocks, both of which are plausible for Venus. Ferroelectric minerals possess extremely high dielectric constants (10(exp 5)) over small temperature intervals and are only required in minor (much less than 1%) abundances to explain the observed emissivities. The ferroelectric model can account for: (1) the observed reduction in emissivity with increased altitude, (2) the abrupt return to normal emissivities at highest elevations, and (3) the variations in the critical elevation observed from region to region.

Evaluation of mineral oil as an acoustic coupling medium in clinical MRgFUS.

PubMed

Gorny, K R; Hangiandreou, N J; Hesley, G K; Felmlee, J P

2007-01-07

We empirically evaluate mineral oil as an alternative to the mixture of de-gassed water and ultrasound gel, which is currently used as an acoustic coupling medium in clinical magnetic resonance guided focused ultrasound (MRgFUS) treatments. The tests were performed on an ExAblate 2000 MRgFUS system (InSightec Inc., Haifa, Israel) using a clinical patient set-up. Acoustic reflections, treatment temperatures, sonication spot dimensions and position with respect to target location were measured, using both coupling media, in repeated sonications in a tissue mimicking gel phantom. In comparison with the water-gel mix, strengths of acoustic reflections from coupling layers prepared with mineral oil were on average 39% lower and the difference was found to be statistically significant (p = 3.3 x 10(-8)). The treatment temperatures were found to be statistically equivalent for both coupling media, although temperatures corresponding to mineral oil tended to be somewhat higher (on average 1.9 degrees C) and their standard deviations were reduced by about 1 degrees C. Measurements of sonication spot dimensions and positions with respect to target location did not reveal systematic differences. We conclude that mineral oil may be used as an effective non-evaporating acoustic coupling medium for clinical MRgFUS treatments.

Intumescent composition, foamed product prepared therewith and process for making same

NASA Technical Reports Server (NTRS)

Riccitiello, S. R.; Parker, J. A. (Inventor)

1974-01-01

An intumescent composition and the foamed product prepared by heating the composition are provided. The composition comprises the reaction product of para-benzoquinone dioxime and a concentrated mineral acid such as sulfuric acid, phosphoric acid, and polyphosphoric acid. The composition is useful as an intumescent agent either by itself or when combined with other materials. A fire-resistant and heat-insulating composition is provided by heating the intumescent composition above its intumescent temperature.

Hydrodesulfurization and hydrodenitrogenation catalysts obtained from coal mineral matter

DOEpatents

Liu, Kindtoken H. D.; Hamrin, Jr., Charles E.

1982-01-01

A hydrotreating catalyst is prepared from coal mineral matter obtained by low temperature ashing coals of relatively low bassanite content by the steps of: (a) depositing on the low temperature ash 0.25-3 grams of an iron or nickel salt in water per gram of ash and drying a resulting slurry; (b) crushing and sizing a resulting solid; and (c) heating the thus-sized solid powder in hydrogen.

Self-assembly processes in the prebiotic environment

PubMed Central

Deamer, David; Singaram, Sara; Rajamani, Sudha; Kompanichenko, Vladimir; Guggenheim, Stephen

2006-01-01

An important question guiding research on the origin of life concerns the environmental conditions where molecular systems with the properties of life first appeared on the early Earth. An appropriate site would require liquid water, a source of organic compounds, a source of energy to drive polymerization reactions and a process by which the compounds were sufficiently concentrated to undergo physical and chemical interactions. One such site is a geothermal setting, in which organic compounds interact with mineral surfaces to promote self-assembly and polymerization reactions. Here, we report an initial study of two geothermal sites where mixtures of representative organic solutes (amino acids, nucleobases, a fatty acid and glycerol) and phosphate were mixed with high-temperature water in clay-lined pools. Most of the added organics and phosphate were removed from solution with half-times measured in minutes to a few hours. Analysis of the clay, primarily smectite and kaolin, showed that the organics were adsorbed to the mineral surfaces at the acidic pH of the pools, but could subsequently be released in basic solutions. These results help to constrain the range of possible environments for the origin of life. A site conducive to self-assembly of organic solutes would be an aqueous environment relatively low in ionic solutes, at an intermediate temperature range and neutral pH ranges, in which cyclic concentration of the solutes can occur by transient dry intervals. PMID:17008220

Grain size associations of branched tetraether lipids in soils and riverbank sediments: influence of hydrodynamic sorting processes

NASA Astrophysics Data System (ADS)

Peterse, Francien; Eglinton, Timothy I.

2017-06-01

We analyzed the abundance and distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in grain size fractions of 7 globally distributed river flank sediments and catchment soils in order to determine if and how the initial soil-brGDGT signature is influenced by hydrodynamic sorting upon entering a river and during subsequent transport from land to sea. BrGDGTs are hypothesized to form associations with high-surface-area fine-grained minerals in soils. Such associations, if maintained during transport, may impart resistance to degradation and promote downstream transport, reducing potential interferences by aquatic brGDGTs. We find that brGDGTs are indeed primarily associated with organic carbon (OC) bound to the clay-silt fraction (<63μm) in both soils and river sediments, and that these associations appear to be maintained during river transport. However, the relative distribution of individual brGDGTs among size fractions is relatively uniform, suggesting that brGDGTs are well mixed in river sediments and that OC-mineral associations are continuously renewed. Consequently, the brGDGT signature finally stored in continental margin sediments appears insensitive to differential particle transport processes. Nevertheless, the lower (upstream) temperature signal generally reflected by brGDGTs in river sediments may also be explained by a contribution of in situ produced brGDGTs leading to an underestimation of reconstructed air temperatures.

Phlogopite Decomposition, Water, and Venus

NASA Technical Reports Server (NTRS)

Johnson, N. M.; Fegley, B., Jr.

2005-01-01

Venus is a hot and dry planet with a surface temperature of 660 to 740 K and 30 parts per million by volume (ppmv) water vapor in its lower atmosphere. In contrast Earth has an average surface temperature of 288 K and 1-4% water vapor in its troposphere. The hot and dry conditions on Venus led many to speculate that hydrous minerals on the surface of Venus would not be there today even though they might have formed in a potentially wetter past. Thermodynamic calculations predict that many hydrous minerals are unstable under current Venusian conditions. Thermodynamics predicts whether a particular mineral is stable or not, but we need experimental data on the decomposition rate of hydrous minerals to determine if they survive on Venus today. Previously, we determined the decomposition rate of the amphibole tremolite, and found that it could exist for billions of years at current surface conditions. Here, we present our initial results on the decomposition of phlogopite mica, another common hydrous mineral on Earth.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelli Kazuberns; Sushil Gupta; Mihaela Grigore

Blast furnace efficiency may be improved by optimizing coke reactivity. Some but not all forms of mineral matter in the coke modify its reactivity, but changes in mineral matter that occur within coke while in the blast furnace have not been fully quantified. To determine changes in mineral matter forms in the blast furnace, coke samples from a dissection study in the LKAB experimental blast furnace (EBF) were characterized using SEM/EDS analysis, EPMA (microprobe), and low-temperature ashing/quantitative XRD analysis. Variations in alkali concentration, particularly potassium, dominated the compositional changes. At high concentrations of potassium, the mineral matter was largely potassium-bearingmore » but even more potassium was diffused throughout the coke and not associated with mineral matter. There was little difference in potassium concentration between the core and surface of the coke pieces, suggesting that potassium diffused rapidly through the whole coke. Iron, calcium, silicon, and aluminum concentrations were relatively constant in comparison, although the mineralogy of all elements changed significantly with changing temperature. 23 refs., 20 figs., 9 tabs.« less

Are anharmonicity corrections needed for temperature-profile calculations of interiors of terrestrial planets

NASA Astrophysics Data System (ADS)

Anderson, O. L.

1982-07-01

The temperature profile of planetary interiors is an important item of information, because many thermodynamic or geodynamic investigations of a planet's interior require an estimate of the temperature profile. Modeling studies of the thermal history or convective processes focus in detail on the thermal profile of the planet. A description is presented of results which show how the present (or equilibrium) interior temperature profile is related to certain constraints placed on the planet, especially the physical properties of the mantle material. These properties depend upon a priori assumptions of chemical composition. The investigation is mainly concerned with experimental and theoretical data appropriate to mantle minerals, in order to justify the use of a simple equation-of-state for planet interiors. It is found that anharmonicity does not seem to be required for calculations of interior properties of the terrestrial planets.

Antibiotics mineralization by electrochemical and UV-based hybrid processes: evaluation of the synergistic effect.

PubMed

Wohlmuth da Silva, Salatiel; Arenhart Heberle, Alan Nelson; Pereira Santos, Alexia; Siqueira Rodrigues, Marco Antônio; Pérez-Herranz, Valentín; Moura Bernardes, Andréa

2018-05-29

Antibiotics are not efficiently removed in conventional wastewater treatments. In fact, different advanced oxidation process (AOPs), including ozone, peroxide, UV radiation, among others, are being investigated in the elimination of microcontaminants. Most of AOPs proved to be efficient on the degradation of antibiotics, but the mineralization is on the one hand not evaluated or on the other hand not high. At this work, the UV-based hybrid process, namely Photo-assisted electrochemical oxidation (PEO), was applied, aiming the mineralization of microcontaminants such as the antibiotics Amoxicillin (AMX), Norfloxacin (NOR) and Azithromycin (AZI). The influence of the individual contributions of electrochemical oxidation (EO) and the UV-base processes on the hybrid process (PEO) was analysed. Results showed that AMX and NOR presented higher mineralization rate under direct photolysis than AZI due to the high absorption of UV radiation. For the EO processes, a low mineralization was found for all antibiotics, what was associated to a mass-transport limitation related to the low concentration of contaminants (200 µg/L). Besides that, an increase in mineralization was found, when heterogeneous photocatalysis and EO are compared, due to the influence of UV radiation, which overcomes the mass-transport limitations. Although the UV-based processes control the reaction pathway that leads to mineralization, the best results to mineralize the antibiotics were achieved by PEO hybrid process. This can be explained by the synergistic effect of the processes that constitute them. A higher mineralization was achieved, which is an important and useful finding to avoid the discharge of microcontaminants in the environment.

First-principles investigations of equilibrium Ca, Mg, Si and O isotope fractionations between silicate melts and minerals

NASA Astrophysics Data System (ADS)

Qi, Y.; Liu, X.; Kang, J.; He, L.

2017-12-01

Equilibrium isotope fractionation factors are essential for using stable isotope data to study many geosciences processes such as planetary differentiation and mantle evolution. The mass-dependent equilibrium isotope fractionation is primarily controlled by the difference in bond energies triggered by the isotope substitution. With the recent advances in computational capabilities, first-principles calculation has become a reliable tool to investigate equilibrium isotopic fractionations, greatly improving our understanding of the factors controlling isotope fractionations. It is important to understand the isotope fractionation between melts and minerals because magmatism is critical for creating and shaping the Earth. However, because isotope fractionation between melts and minerals is small at high temperature, it is difficult to experimentally calibrate such small signature. Due to the disordered and dynamic character of melts, calculations of equilibrium isotope fractionation of melts are more challenging than that for gaseous molecules or minerals. Here, we apply first-principles molecular dynamics method to calculate equilibrium Ca, Mg, Si, and O isotope fractionations between silicate melts and minerals. Our results show that equilibrium Mg, Si, and O isotope fractionations between olivine and pure Mg2SiO4 melt are close to zero at high temperature (e.g. δ26Mgmelt-ol = 0.03 ± 0.04‰, δ30Simelt-ol = -0.06 ± 0.07‰, δ18Omelt-ol = 0.07‰ ± 0.08 at 1500 K). Equilibrium Ca, Mg, Si, and O isotope fractionations between diopside and basalt melt (67% CaMgSi2O6 + 33% CaAl2Si2O8) are also negligible at high temperature (e.g. δ44/40Camelt-cpx = -0.01 ± 0.02‰, δ26Mgmelt-cpx = -0.05 ± 0.14‰, δ30Simelt-cpx = 0.04 ± 0.04‰, δ18Omelt-cpx = 0.03 ± 0.07‰ at 1500 K). These results are consistent with the observations in natural samples that there is no significant Ca, Mg, Si, and O isotope fractionation during mantle partial melting, demonstrating the reliability of our methods. Thus, our results can be used to understand stable isotope fractionation during partial melting of mantle peridotite or fractional crystallization during magmatic differentiation. The first-principles molecular dynamics method is a promising tool to obtain equilibrium fractionation of more isotope systems for complicate liquids.

Soil Minerals Affect Extracellular Enzyme Activities in Cold and Warm Environments

NASA Astrophysics Data System (ADS)

Yang, Z.; Morin, M. M.; Graham, D. E.; Wullschleger, S. D.; Gu, B.

2017-12-01

Extracellular enzymes are mainly responsible for degrading and cycling soil organic matter (SOM) in both cold and warm terrestrial ecosystems. Minerals can play important roles in affecting soil enzyme activities, however, the interactions between enzyme and soil minerals remain poorly understood. In this study, we developed a model soil-enzyme system to examine the mineral effects on a hydrolytic enzyme (i.e., β-glucosidase) under both cold (4°C) and relatively warm (20 and 30°C) conditions. Minerals including iron oxides and clays (e.g., kaolinite and montmorillonite) were used to mimic different types of soils, and enzyme adsorption experiments were conducted to determine the enzyme interactions with different mineral surfaces. Time-series experiments were also carried out to measure enzymatic degradation of the organic substrates, such as cellobiose and indican. We observed that fractions of adsorbed enzyme and the hydrolytic activity were higher on iron oxides (e.g., hematite) compared to kaolinite and montmorillonite at given experimental conditions. The degradation of cellobiose was significantly faster than that of indican in the presence of minerals. We also found that the adsorption of enzyme was not dependent on the mineral surface areas, but was controlled by the mineral surface charge. In addition, temperature increase from 4 to 30°C enhanced mineral-assisted glucosidase hydrolysis by 2 to 4 fold, suggesting greater degradation under warmer environments. The present work demonstrates that the enzyme activity is influenced not only by the soil temperature but also by the surface chemistry of soil minerals. Our results highlight the need to consider the physical and chemical properties of minerals in biogeochemical models, which could provide a better prediction for enzyme-facilitated SOM transformations in terrestrial ecosystems.

Iron Sulfide Minerals Record Microbe-Mineral Interactions in Anoxic Environments

NASA Astrophysics Data System (ADS)

Picard, A.; Gartman, A.; Cosmidis, J.; Clarke, D. R.; Girguis, P. R.

2017-12-01

The precipitation of most minerals in low-temperature environments on Earth is directly or indirectly influenced by the presence of organic substances and/or microbial biomass. Notably, the influence of microorganisms on the formation of Mn and Fe oxides/oxyhydroxides at the surface of the Earth has been well characterized (Chan et al., 2011; Estes et al., 2017). However, an oxygenated atmosphere is a unique feature of planet Earth. It is therefore critical for the search of life on other planetary bodies to characterize microbe-mineral interactions that form in anoxic conditions. Here we explore the role of microorganisms on the formation of iron sulfide minerals, which form under anoxic conditions. On modern Earth, sulfate-reducing microorganisms (SRM) are the major source of dissolved sulfide in low-temperature sedimentary environments. We experimentally demonstrate that SRM play a role in the nucleation and growth of iron sulfide minerals by acting as organic templates. The physical characteristics of the resulting minerals are different from those formed under abiotic conditions. Moreover, upon forming, iron sulfide minerals become associated with organic carbon, producing a potential organo-mineral signature. We also evaluate how the presence of various organic substances affect the formation of abiotic minerals and how this could produce false biosignatures that could be mistaken as biogenic minerals. Chan, C.S., Fakra, S.C., Emerson, D., Fleming, E.J. and Edwards, K.J. (2011) Lithotrophic iron-oxidizing bacteria produce organic stalks to control mineral growth: implications for biosignature formation. Isme Journal 5, 717-727. Estes, E.R., Andeer, P.F., Nordlund, D., Wankel, S.D. and Hansel, C.M. (2017) Biogenic manganese oxides as reservoirs of organic carbon and proteins in terrestrial and marine environments. Geobiology 15, 158-172.

Comparative study on inorganic composition and crystallographic properties of cortical and cancellous bone.

PubMed

Wang, Xiao-Yan; Zuo, Yi; Huang, Di; Hou, Xian-Deng; Li, Yu-Bao

2010-12-01

To comparatively investigate the inorganic composition and crystallographic properties of cortical and cancellous bone via thermal treatment under 700 °C. Thermogravimetric measurement, infrared spectrometer, X-ray diffraction, chemical analysis and X-ray photo-electron spectrometer were used to test the physical and chemical properties of cortical and cancellous bone at room temperature 250 °C, 450 °C, and 650 °C, respectively. The process of heat treatment induced an extension in the a-lattice parameter and changes of the c-lattice parameter, and an increase in the crystallinity reflecting lattice rearrangement after release of lattice carbonate and possible lattice water. The mineral content in cortical and cancellous bone was 73.2wt% and 71.5wt%, respectively. For cortical bone, the weight loss was 6.7% at the temperature from 60 °C to 250 °C, 17.4% from 250 °C to 450 °C, and 2.7% from 450 °C to 700 °C. While the weight loss for the cancellous bone was 5.8%, 19.9%, and 2.8 % at each temperature range, the Ca/P ratio of cortical bone was 1.69 which is higher than the 1.67 of stoichiometric HA due to the B-type CO₃²⁻ substitution in apatite lattice. The Ca/P ratio of cancellous bone was lower than 1.67, suggesting the presence of more calcium deficient apatite. The collagen fibers of cortical bone were arrayed more orderly than those of cancellous bone, while their mineralized fibers ollkded similar. The minerals in both cortical and cancellous bone are composed of poorly crystallized nano-size apatite crystals with lattice carbonate and possible lattice water. The process of heat treatment induces a change of the lattice parameter, resulting in lattice rearrangement after the release of lattice carbonate and lattice water and causing an increase in crystal size and crystallinity. This finding is helpful for future biomaterial design, preparation and application. Copyright © 2010 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

Possible genetic link between I-type granite and orogenic gold deposits in Egypt (metamorphic-magmatic interaction?)

NASA Astrophysics Data System (ADS)

Abd El Monsef, Mohamed

2015-04-01

The orogenic gold deposits are a distinctive type of deposits that revealed unique temporal and spatial association with an orogeny. Where, the system of gold veins and related ore minerals was confined to hydrothermal solutions formed during compressional to transpressional deformation processes at convergent plate margins in accretionary and collisional orogens, with the respect to ongoing deep-crustal, subduction-related thermal processes. In Egypt, most of vein-type and dyke-type gold mineralization are restricted to granitic rocks or at least near of granitic intrusion that seems to have had an important influence on gold mineralization. Shear zone-related, mesothermal gold deposits of Fatira and Gidami mines in the northern Eastern Desert of Egypt are found within granitic bodies or at the contact between granites and metavolcanic rocks. The hosting-granitic rocks in Fatira and Gidami areas are mainly of granodioritic composition (I-Type granite) which is related to calc-alkaline magmatic series. However, Fatira granitoids were developed within island arc tectonic settings related to mature island arc system (Late-orogenic stage), at relatively low temperature (around 660° C) and medium pressure between (5 - 10 Kbar). On the other hand, Gidami granitoids were developed during the collision stage in continental arc regime related to active continental margin (Syn-orogeny), which were crystallized at relatively high temperature (700-720° C) and low pressure (around 0.1 Kbar). The ore mineralogy includes pyrite, chalcopyrite, sphalerite, covellite, ilmenite, goethite ± pyrrhotite ± pentlandite ± galena ± molybdenite. Native gold is detected only in Gidami mineralization as small inclusions within pyrite and goethite or as tiny grains scattered within quartz vein (in close proximity to the sulfides). In Fatira deposits, it is detected only by microprobe analysis within the crystal lattice of pyrite and jarosite. Fluid inclusions study for the mineralized ores revealed two main groups of fluid inclusions in both areas: A) Aqueous inclusions (H2O-NaCl±KCl system), and B) Carbonic inclusions (H2O-CO2-NaCl±CH4). A drop of pressure during the migration of these fluids to shallower depths along the shear zones was the main reason for phase separation. Isochores calculation from microthermometric results proved that, the P-T boundary conditions outlined for Fatira gold deposits are of 275° to 297° C and between (0.2 - 1.2 Kbar); and of 277° to 300° C and between (0.2 - 1 Kbar) for Gidami gold deposits. The normalization Chondrite patterns of rare earth elements (REEs) for the gold-ore deposits with the surrounding I-type granitic rocks exhibit an obvious similarity and positive correlation. The geological, mineralogical, geochemical and fluid inclusions studies revealed a genetic link between gold mineralization and intrusion of calc-alkaine granitic magma. Whereas, The granitic magma acts as a supplier for the ore-bearing fluid and as a heat source for metamorphic processes, leading to hydrothermal convection currents.

Soil respiration and net N mineralization along a climate gradient in Maine

Treesearch

Jeffery A. Simmons; Ivan J. Fernandez; Russell D. Briggs

1996-01-01

Our objective was to determine the influence of temperature and moisture on soil respiration and net N mineralization in northeastern forests. The study consisted of sixteen deciduous stands located along a regional climate gradient within Maine. A significant portion of the variance in net N mineralization (41 percent) and respiration (33 percent) was predicted by...

Chapter 7:Mineral Scale Management

Treesearch

Alan W. Rudie; Peter W. Hart

2012-01-01

Mineral scale problems are not new to pulp mills and bleach plants. The liquor recovery system ensures that white liquor is saturated in calcium carbonate, and this mineral will precipitate when heated to cooking temperatures in the digester [1,2]. The original single-vessel continuous digesters sold by Kamyr had an extra liquor heater as standard equipment to enable...

Kinetics of carbonate dissolution in CO2-saturated aqueous system at reservoir conditions

NASA Astrophysics Data System (ADS)

Peng, Cheng; Crawshaw, John P.; Maitland, Geoffrey; Trusler, J. P. Martin

2014-05-01

In recent years, carbon capture and storage (CCS) has emerged as a key technology for limiting anthropogenic CO2 emissions while allowing the continued utilisation of fossil fuels. The most promising geological storage sites are deep saline aquifers because the capacity, integrity and injection economics are most favourable, and the environmental impact can be minimal. Many rock-fluid chemical reactions are known to occur both during and after CO2 injection in saline aquifers. The importance of rock-fluid reactions in the (CO2 + H2O) system can be understood in terms of their impact on the integrity and stability of both the formation rocks and cap rocks. The chemical interactions between CO2-acidified brines and the reservoir minerals can influence the porosity and permeability of the formations, resulting in changes in the transport processes occurring during CO2 storage. Since carbonate minerals are abundant in sedimentary rocks, one of the requirements to safely implement CO2 storage in saline aquifers is to characterise the reactivity of carbonate minerals in aqueous solutions at reservoir conditions. In this work, we reported measurements of the intrinsic rate of carbonate dissolution in CO2-saturated water under high-temperature high-pressure reservoir conditions extending up to 373 K and 14 MPa. The rate of carbonate dissolution in CO2-free HCl(aq) was also measured at ambient pressure at temperatures up to 353 K. Various pure minerals and reservoir rocks were investigated in this study, including single-crystals of calcite and magnesite, and samples of dolomite, chalks and sandstones. A specially-designed batch reactor system, implementing the rotating disc technique, was used to obtain the intrinsic reaction rate at the solid/liquid interface, free of mass transfer effects. The effective area and mineralogy of the exposed surface was determined by a combination of surface characterisation techniques including XRD, SEM, EDX and optical microscopy. The results of the study indicate that the rotating disc technique can allow accurate measurement of the carbonate dissolution rate under surface-reaction-controlled conditions, and that the carbonate dissolution rate typically increases with the increase of temperature, CO2 partial pressure and solution acidity. The study shows that the dissolution of carbonate in CO2-free acidic solutions can be described as a first order heterogeneous reaction; however, this model is not sufficient to describe the reaction kinetics of carbonate minerals in the (CO2 + H2O) system, particularly for high reactivity carbonates, such as calcite, at reservoir conditions. For these systems, both pH and the activity of CO2(aq) influence the dissolution rate. Based on the experimental results, kinetic models have been developed and parameterised to describe the dissolution of different carbonate minerals. The results of this study should facilitate more rigorous modelling of mineral dissolution in deep saline aquifers used for CO2 storage. We gratefully acknowledge the funding of QCCSRC provided jointly by Qatar Petroleum, Shell, and the Qatar Science & Technology Park. Keywords: Carbon Dioxide, Carbonate, High Pressure, High Temperature, Reaction Kinetics.

Heterogeneity of carbon loss and its temperature sensitivity in East-European subarctic tundra soils.

PubMed

Diáková, Kateřina; Čapek, Petr; Kohoutová, Iva; Mpamah, Promise A; Bárta, Jiří; Biasi, Christina; Martikainen, Pertti J; Šantrůčková, Hana

2016-09-01

Arctic peatlands store large stocks of organic carbon which are vulnerable to the climate change but their fate is uncertain. There is increasing evidence that a part of it will be lost as a result of faster microbial mineralization. We studied the vulnerability of 3500-5900 years old bare peat uplifted from permafrost layers by cryogenic processes to the surface of an arctic peat plateau. We aimed to find biotic and abiotic drivers of CLOSS from old peat and compare them with those of adjacent, young vegetated soils of the peat plateau and mineral tundra. The soils were incubated in laboratory at three temperatures (4°C, 12°C and 20°C) and two oxygen levels (aerobic, anaerobic). CLOSS was monitored and soil parameters (organic carbon quality, nutrient availability, microbial activity, biomass and stoichiometry, and extracellular oxidative and hydrolytic enzyme pools) were determined. We found that CLOSS from the old peat was constrained by low microbial biomass representing only 0.22% of organic carbon. CLOSS was only slightly reduced by the absence of oxygen and exponentially increased with temperature, showing the same temperature sensitivity under both aerobic and anaerobic conditions. We conclude that carbon in the old bare peat is stabilized by a combination of physical, chemical and biological controls including soil compaction, organic carbon quality, low microbial biomass and the absence of plants. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Basic Performance of Fibre Reinforced Asphalt Concrete with Reclaimed Asphalt Pavement Produced In Low Temperatures with Foamed Bitumen

NASA Astrophysics Data System (ADS)

Chomicz-Kowalska, Anna; Iwański, Mateusz M.; Mrugała, Justyna

2017-10-01

During the reconstruction of road pavements, the reclaimed asphalt pavement (RAP), which is obtained through milling of the worn out existing asphalt, is commonly used for producing new base courses in cold recycling processes. Two of these techniques are most popular: one using mineral-cement-emulsion mixes and one utilizing mineral cement mixes with foamed bitumen. Additionally, some amounts of RAP can be incorporated into traditional hot mix asphalt. The demand for energy efficient and environmentally friendly solutions however, results in a need for development of new techniques that would result in cheaper and more reliable solutions with smaller carbon footprint. The reduction of processing temperatures with simultaneous incorporation of reclaimed material is the most efficient way of obtaining these objectives, but it often results in the overall decrease of bituminous mix quality. The paper presents the possibility of using RAP for producing asphalt concrete in warm mix asphalt (WMA) production process by the use of foamed bitumen modified with Fischer-Tropsch synthetic wax and polymer-basalt fibers. Additionally, a series of reference mixtures were produced to investigate the effects of the additives and of the warm process. The carried out analyses and tests shown that the experimental warm mix asphalt produced with RAP and foamed bitumen returned satisfactory performance. The introduction of synthetic F-T wax in the warm foam bitumen mixes resulted in a significantly improved compaction levels and moisture and frost resistance and the addition of polymer-basalt fibers has further improved the permanent deformation resistance of the mixes. All of the designed and tested mixes have fulfilled the requirements for binding course asphalt concrete with medium traffic loads.

Mixed biogenic and hydrothermal quartz in Permian lacustrine shale of Santanghu Basin, NW China: implications for penecontemporaneous transformation of silica minerals

NASA Astrophysics Data System (ADS)

Jiao, Xin; Liu, Yiqun; Yang, Wan; Zhou, Dingwu; Wang, Shuangshuang; Jin, Mengqi; Sun, Bin; Fan, Tingting

2018-01-01

The cycling of various isomorphs of authigenic silica minerals is a complex and long-term process. A special type of composite quartz (Qc) grains in tuffaceous shale of Permian Lucaogou Formation in the sediment-starved volcanically and hydrothermally active intracontinental lacustrine Santanghu rift basin (NW China) is studied in detail to demonstrate such processes. Samples from one well in the central basin were subject to petrographic, elemental chemical, and fluid inclusion analyses. About 200 Qc-bearing laminae are 0.1-2 mm and mainly 1 mm thick and intercalated within tuffaceous shale laminae. The Qc grains occur as framework grains and are dispersed in igneous feldspar-dominated matrix, suggesting episodic accumulation. The Qc grains are bedding-parallel, uniform in size (100 s µm), elongate, and radial in crystal pattern, suggesting a biogenic origin. Qc grains are composed of a core of anhedral microcrystalline quartz and an outer part of subhedral mega-quartz grains, whose edges are composed of small euhedral quartz crystals, indicating multiple episodic processes of recrystallization and overgrowth. Abundance of Al and Ti in quartz crystals and estimated temperature from fluid inclusions in Qc grains indicate that processes are related to hydrothermal fluids. Finally, the Qc grains are interpreted as original silica precipitation in microorganism (algae?) cysts, which were reworked by bottom currents and altered by hydrothermal fluids to recrystalize and overgrow during penecontemporaneous shallow burial. It is postulated that episodic volcanic and hydrothermal activities had changed lake water chemistry, temperature, and nutrient supply, resulting in variations in microorganic productivities and silica cycling. The transformation of authigenic silica from amorphous to well crystallized had occurred in a short time span during shallow burial.

Mineralogical, geochemical and isotopic characteristics of hydrothermal alteration processes in the active, submarine, felsic-hosted PACMANUS field, Manus Basin, Papua New Guinea

NASA Astrophysics Data System (ADS)

Lackschewitz, K. S.; Devey, C. W.; Stoffers, P.; Botz, R.; Eisenhauer, A.; Kummetz, M.; Schmidt, M.; Singer, A.

2004-11-01

During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges. The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite ± illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite ± mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite ± illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite ± chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ˜250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite ± chlorite alteration formed at ˜300°C; (2) chlorite ± illite alteration at 235°C; (3) chlorite ± illite and mixed layer clay alteration; and (4) chlorite ± illite alteration at 220°C. Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly present in the pyrophyllites. Illite shows a significant enrichment for Cs and Cu relative to the bulk altered samples. Considerations of mineral stability allow us to place some constraints on fluid chemistry. Hydrothermal fluid pH for the chloritization and illitization was neutral to slightly acidic and relatively acidic for the pyrophyllite alteration. In general the fluids, especially from Roman Ruins and at intermediate depths below Snowcap, show only a small proportion of seawater mixing (<10%). Fluids in shallow and deep parts of the Snowcap holes, in contrast, show stronger seawater influence.

HCMM satellite to take earth's temperature

NASA Technical Reports Server (NTRS)

1978-01-01

The heat capacity mapping mission (HCMM), a low cost modular spacecraft built for the Applications Explorer Missions (AEM), was designed to allow scientists to determine the feasibility of using day/night thermal infrared remote sensor-derived data to: (1) discriminate various rock types and locate mineral resources; (2) measure and monitor surface soil moisture changes; (3) measure plant canopy temperatures at frequent intervals to determine transpiration of water and plant stress; and (4) measure urban heat islands. The design of the spacecraft (AEM-A), its payload, launch vehicle, orbit, and data collection and processing methods are described. Projects in which the HCMM data will be applied by 12 American and 12 foreign investigators are summarized.

Zinc Isotopic Compositions of Spinel Peridotites

NASA Astrophysics Data System (ADS)

Chen, S.; Huang, F.

2015-12-01

Zn isotope geochemistry has shown great potential in exploring planetary differentiation and volatilization history [1,2,3,4]. However, the zinc isotopic composition of the mantle and its fractionation mechanism in high-temperature processes are still unclear. In order to understand Zn isotope composition of the mantle, here we measured Zn isotope data for mantle rocks and minerals, including coexisting olivine, orthopyroxene (Opx), clinopyroxene (Cpx) and spinel from peridotite xenoliths in the Hannuoba (China), Vitim (Siberia), Tariat (central Mongolia), and Dariganga (SE Mongolia). As an accessary mineral, spinels in our study have high Zn contents (500-1400 ppm), accounting for 18%-40% of the total Zn budget in peridotites. Spinels have higher δ66Zn ranging from 0.17 to 0.30‰ than other mantle minerals. For most samples, the δ66Zn of olivines vary from -0.03‰ to 0.19‰, indistinguishable to the value of the coexisting Opx (0.05‰ to 0.20‰). However, we also observed large fractionation between these two minerals, which may reflect disequilibrium fractionation due to kinetic processes. Finally, δ66Zn for peridotites are 0.12-0.21‰, slightly lighter than that of basalts (~0.25±0.05‰), revealing that Zn isotopes can be slightly fractionated during mantle melting. [1] Luck et al., (2005) Geochimica Cosmo Acta, 69, 5351-5363. [2] Paniello et al., (2012) Nature, 490, 376-379. [3] Chen et al., (2013) Meteoritics Planet Sci, 48, 2441-2450. [4] Day and Moynier, (2014) Phil. Transac. of the Royal Society B, 372, 20130259

Salinity/temperature ranges for application of seawater SA-T-P models

NASA Astrophysics Data System (ADS)

Marion, G. M.; Millero, F. J.; Feistel, R.

2009-01-01

At the present time, little is known about how broad salinity and temperature ranges are for seawater thermodynamic models that are functions of absolute salinity (SA), temperature (T) and pressure (P). Such models rely on fixed compositional ratios of the major components (e.g. Na/Cl, Mg/Cl, Ca/Cl, SO4/Cl, etc.). As seawater evaporates or freezes, solid phases (e.g. CaCO3(s) or CaSO42H2O(s)) will eventually precipitate. This will change the compositional ratios, and these salinity models will no longer be applicable. A future complicating factor is the lowering of seawater pH as the atmospheric concentrations of CO2 increase. A geochemical model (FREZCHEM) was used to quantify the SA-T boundaries at P=0.1 MPa and the range of these boundaries for future atmospheric CO2 increases. An omega supersaturation model for CaCO3 minerals based on homogeneous nucleation was extended from 25-40°C to 3°C. CaCO3 minerals were the boundary defining minerals (first to precipitate) between 3°C (at SA=104 g kg-1 and 40°C (at SA=66 g kg-1. At 2.82°C, calcite(CaCO3) transitioned to ikaite(CaCO36H2O) as the dominant boundary defining mineral for colder temperatures, which culminated in a low temperature boundary of -4.93°C. Increasing atmospheric CO2 from 385 μatm (in Year 2008) to 550 μatm (in Year 2100) would increase the SA and t boundaries as much as 11 g kg-1 and 0.66°C, respectively. The model-calculated calcite-ikaite transition temperature of 2.82°C is in excellent agreement with ikaite formation in natural environments that occurs at temperatures of 3°C or lower. Furthermore, these results provide a quantitative theoretical explanation (FREZCHEM model calculations) for why ikaite is the solid phase CaCO3 mineral that precipitates during seawater freezing.

Diversity of sulfate-reducing bacteria in a plant using deep geothermal energy

NASA Astrophysics Data System (ADS)

Alawi, Mashal; Lerm, Stephanie; Vetter, Alexandra; Wolfgramm, Markus; Seibt, Andrea; Würdemann, Hilke

2011-06-01

Enhanced process understanding of engineered geothermal systems is a prerequisite to optimize plant reliability and economy. We investigated microbial, geochemical and mineralogical aspects of a geothermal groundwater system located in the Molasse Basin by fluid analysis. Fluids are characterized by temperatures ranging from 61°C to 103°C, salinities from 600 to 900 mg/l and a dissolved organic carbon content (DOC) between 6.4 to 19.3 mg C/l. The microbial population of fluid samples was analyzed by genetic fingerprinting techniques based on PCR-amplified 16S rRNA- and dissimilatory sulfite reductase genes. Despite of the high temperatures, microbes were detected in all investigated fluids. Fingerprinting and DNA sequencing enabled a correlation to metabolic classes and biogeochemical processes. The analysis revealed a broad diversity of sulfate-reducing bacteria. Overall, the detection of microbes known to be involved in biocorrosion and mineral precipitation indicates that microorganisms could play an important role for the understanding of processes in engineered geothermal systems.

Process for the physical segregation of minerals

DOEpatents

Yingling, Jon C.; Ganguli, Rajive

2004-01-06

With highly heterogeneous groups or streams of minerals, physical segregation using online quality measurements is an economically important first stage of the mineral beneficiation process. Segregation enables high quality fractions of the stream to bypass processing, such as cleaning operations, thereby reducing the associated costs and avoiding the yield losses inherent in any downstream separation process. The present invention includes various methods for reliably segregating a mineral stream into at least one fraction meeting desired quality specifications while at the same time maximizing yield of that fraction.

Degradation and mineralization of chitin in an estuary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyer, J.

1987-01-01

A method for measuring microbial degradation and mineralization of radiolabeled native chitin is described. /sup 14/C-labeled chitin was synthesized in vivo by injecting shed blue crabs (Callinectes sapidus) with N-acetyl-D-(/sup 14/C)-glucosamine, allowing for its incorporation into the exoskeleton. Rates of chitin degradation and mineralization in estuarine water and sediments were determined as functions of temperature, inoculum source, and oxygen condition. Significant differences in rates between temperature treatments were evident. Q/sub 10/ values ranged from 1.2 to 2.5 for water and sediment, respectively. Increased incubation temperature also resulted in decreased lag times before onset of chitinoclastic bacterial growth and chitin degradation.more » The anaerobic pathway of chitin decomposition by chitinoclastic bacteria was examined with an emphasis on end product coupling to other bacterial types. Actively growing chitinoclastic bacterial isolates produced primarily acetate, hydrogen, and carbon dioxide in broth culture.« less

Method for the production of mineral wool and iron from serpentine ore

DOEpatents

O'Connor, William K [Albany, OR; Rush, Gilbert E [Scio, OR; Soltau, Glen F [Lebanon, OR

2011-10-11

Magnesium silicate mineral wools having a relatively high liquidus temperature of at least about 1400.degree. C. and to methods for the production thereof are provided. The methods of the present invention comprise melting a magnesium silicate feedstock (e.g., comprising a serpentine or olivine ore) having a liquidus temperature of at least about 1400.degree. C. to form a molten magnesium silicate, and subsequently fiberizing the molten magnesium silicate to produce a magnesium silicate mineral wool. In one embodiment, the magnesium silicate feedstock contains iron oxide (e.g., up to about 12% by weight). Preferably, the melting is performed in the presence of a reducing agent to produce an iron alloy, which can be separated from the molten ore. Useful magnesium silicate feedstocks include, without limitation, serpentine and olivine ores. Optionally, silicon dioxide can be added to the feedstock to lower the liquidus temperature thereof.

High temperature crystal field spectra of transition metal-bearing minerals - Relevance to remote-sensed spectra of planetary surfaces

NASA Technical Reports Server (NTRS)

Parkin, K. M.; Burns, R. G.

1980-01-01

It is pointed out that transition metal ions in silicate minerals, glasses, and crystalline and amorphous oxyhydroxides and salts contribute to the visible-near infrared spectral profiles of planetary surfaces. Investigations are conducted to obtain spectral information which might be helpful in the interpretation of the remote-sensed spectra of planetary surfaces. A description is presented of the results of high temperature crystal field spectral measurements of a variety of heated minerals containing Cr(3+), Fe(3+), Fe(++), and Mn(++) ions in different coordination symmetries, taking into account a correlation of the temperature-induced variations with those previously observed for octahedrally coordinated Fe(++)-bearing silicates. The employed experimental methods are also discussed, giving attention to the preparation of the samples, the determination of the absorption spectra, electron microprobe analyses, and the curve fitting procedure.

Simulation of the Aerosol-Atmosphere Interaction in the Dead Sea Area with COSMO-ART

NASA Astrophysics Data System (ADS)

Vogel, Bernhard; Bangert, Max; Kottmeier, Christoph; Rieger, Daniel; Schad, Tobias; Vogel, Heike

2014-05-01

The Dead Sea is a unique environment located in the Dead Sea Rift Valley. The fault system of the Dead Sea Rift Valley marks the political borders between Israel, Jordan, and Palestine. The Dead Sea region and the ambient Eastern Mediterranean coastal zone provide a natural laboratory for studying atmospheric processes ranging from the smallest scale of cloud processes to regional weather and climate. The virtual institute DESERVE is designed as a cross-disciplinary and cooperative international project of the Helmholtz Centers KIT, GFZ, and UFZ with well-established partners in Israel, Jordan and Palestine. One main focus of one of the work packages is the role of aerosols in modifying clouds and precipitation and in developing the Dead Sea haze layer as one of the most intriguing questions. The haze influences visibility, solar radiation, and evaporation and may even affect economy and health. We applied the online coupled model system COSMO-ART, which is able to treat the feedback processes between aerosol, radiation, and cloud formation, for a case study above the Dead Sea and adjacent regions. Natural aerosol like mineral dust and sea salt as well as anthropogenic primary and secondary aerosol is taken into account. Some of the observed features like the vertical double structure of the haze layer are already covered by the simulation. We found that absorbing aerosol like mineral dust causes a temperature increase in parts of the model domain. In other areas a decrease in temperature due to cirrus clouds modified by elevated dust layers is simulated.

Sono-synthesis of solar light responsive S-N-C-tri doped TiO2 photo-catalyst under optimized conditions for degradation and mineralization of Diclofenac.

PubMed

Ramandi, Sara; Entezari, Mohammad H; Ghows, Narjes

2017-09-01

C-N-S-tri doped TiO 2 anatase phase was synthesized using a facile, effective and novel sonochemical method at low frequency (20kHz) and at room temperature. Titanium butoxide as the titanium precursor and thiourea as the dopant source were used in the synthesis of the photo-catalyst. The effects of important parameters such as thiourea/Ti molar ratio, ultrasound intensity, sonication time and temperature were studied on the synthesis of tri-doped TiO 2 . The XPS results confirmed the presence of N, S, and C in the photo-catalyst. The photo-catalytic efficiency of the synthesized catalyst was studied toward the removal of Diclofenac as a model pharmaceutical organic pollutant. The results confirmed that the photo-catalyst synthesized with narrower band gap energy, shorter sonication time and higher ultrasound intensity leads to a rapid removal of Diclofenac. The effect of operational variables on the photo-catalytic activity of C-N-S tri doped TiO 2 nanoparticles was studied and optimized using the Taguchi method as a statistical technique. Additionally, the degradation process followed the pseudo-first-order kinetics model and the highest apparent rate constant of 0.0632min -1 achieved in 90min. Chemical oxygen demand (COD) analysis confirmed that the mineralization took place completely (100%) under the optimized conditions in 180min. Different scavengers were applied during the degradation process and active species such as OH and O 2 - had key roles in the photo-catalytic process. Copyright © 2017 Elsevier B.V. All rights reserved.

Degradation of Penicillin G by heat activated persulfate in aqueous solution.

PubMed

Norzaee, Samira; Taghavi, Mahmoud; Djahed, Babak; Kord Mostafapour, Ferdos

2018-06-01

We used Heat Activated of Persulfate (HAP) to decompose Penicillin G (PEN G) in aqueous solution. The effect of pH (3-11), temperature (313-353 K), and initial concentration of Sodium Persulfate (SPS) (0.05-0.5 mM) on the decomposition level of PEN G were investigated. The residue of PEN G was determined by spectrophotometry at the wavelength of 290 nm. Also, the Chemical Oxygen Demand (COD) was measured in each experiment. The Total Organic Carbon (TOC) analysis was utilized for surveying the mineralization of PEN G. In addition, based on Arrhenius equation, the activation energy of PEN G decomposition was calculated. The results indicated that the maximum PEN G removal rate was obtained at pH 5 and by increasing the doses of SPS from 0.05 to 0.5 mM, the PEN G decomposition was enhanced. It was found that an increase in temperature is accompanied by an increase in removal efficiency of PEN G. The activation energy of the studied process was determined to be 94.8 kJ mol -1 , suggesting that a moderate activation energy is required for PEN G decomposition. The TOC measurements indicate that the HAP can efficiently mineralize PEN G. Besides, the presence of the scavengers significantly suppressed the HAP process to remove the PEN G. Overall, the results of this study demonstrate that using HAP process can be a suitable method for decomposing of PEN G in aqueous solutions. Copyright © 2018 Elsevier Ltd. All rights reserved.

A negative feedback mechanism for the long-term stabilization of the earth's surface temperature

NASA Technical Reports Server (NTRS)

Walker, J. C. G.; Hays, P. B.; Kasting, J. F.

1981-01-01

It is suggested that the partial pressure of carbon dioxide in the atmosphere is buffered, over geological time scales, by a negative feedback mechanism, in which the rate of weathering of silicate minerals (followed by deposition of carbonate minerals) depends on surface temperature, which in turn depends on the carbon dioxide partial pressure through the greenhouse effect. Although the quantitative details of this mechanism are speculative, it appears able to partially stabilize the earth's surface temperature against the steady increase of solar luminosity, believed to have occurred since the origin of the solar system.

High pressure-elevated temperature x-ray micro-computed tomography for subsurface applications.

PubMed

Iglauer, Stefan; Lebedev, Maxim

2018-06-01

Physical, chemical and mechanical pore-scale (i.e. micrometer-scale) mechanisms in rock are of key importance in many, if not all, subsurface processes. These processes are highly relevant in various applications, e.g. hydrocarbon recovery, CO 2 geo-sequestration, geophysical exploration, water production, geothermal energy production, or the prediction of the location of valuable hydrothermal deposits. Typical examples are multi-phase flow (e.g. oil and water) displacements driven by buoyancy, viscous or capillary forces, mineral-fluid interactions (e.g. mineral dissolution and/or precipitation over geological times), geo-mechanical rock behaviour (e.g. rock compaction during diagenesis) or fines migration during water production, which can dramatically reduce reservoir permeability (and thus reservoir performance). All above examples are 3D processes, and 2D experiments (as traditionally done for micro-scale investigations) will thus only provide qualitative information; for instance the percolation threshold is much lower in 3D than in 2D. However, with the advent of x-ray micro-computed tomography (μCT) - which is now routinely used - this limitation has been overcome, and such pore-scale processes can be observed in 3D at micrometer-scale. A serious complication is, however, the fact that in the subsurface high pressures and elevated temperatures (HPET) prevail, due to the hydrostatic and geothermal gradients imposed upon it. Such HPET-reservoir conditions significantly change the above mentioned physical and chemical processes, e.g. gas density is much higher at high pressure, which strongly affects buoyancy and wettability and thus gas distributions in the subsurface; or chemical reactions are significantly accelerated at increased temperature, strongly affecting fluid-rock interactions and thus diagenesis and deposition of valuable minerals. It is thus necessary to apply HPET conditions to the aforementioned μCT experiments, to be able to mimic subsurface conditions in a realistic way, and thus to obtain reliable results, which are vital input parameters required for building accurate larger-scale reservoir models which can predict the overall reservoir-scale (hectometer-scale) processes (e.g. oil production or diagenesis of a formation). We thus describe here the basic workflow of such HPET-μCT experiments, equipment requirements and apparatus design; and review the literature where such HPET-μCT experiments were used and which phenomena were investigated (these include: CO 2 geo-sequestration, oil recovery, gas hydrate formation, hydrothermal deposition/reactive flow). One aim of this paper is to give a guideline to users how to set-up a HPET-μCT experiment, and to provide a quick overview in terms of what is possible and what not, at least up to date. As a conclusion, HPET-μCT is a valuable tool when it comes to the investigation of subsurface micrometer-scaled processes, and we expect a rapidly expanding usage of HPET-μCT in subsurface engineering and the subsurface sciences. Copyright © 2018 Elsevier B.V. All rights reserved.

Definitions of Health Terms: General Health

MedlinePlus

... needs to stay healthy. You can start by learning these general health terms. Find more definitions on Fitness | General Health | Minerals | Nutrition | Vitamins Basal Body Temperature Basal body temperature is your temperature at rest ...

Mineral-organic interfacial processes: potential roles in the origins of life.

PubMed

Cleaves, H James; Michalkova Scott, Andrea; Hill, Frances C; Leszczynski, Jerzy; Sahai, Nita; Hazen, Robert

2012-08-21

Life is believed to have originated on Earth ∼4.4-3.5 Ga ago, via processes in which organic compounds supplied by the environment self-organized, in some geochemical environmental niches, into systems capable of replication with hereditary mutation. This process is generally supposed to have occurred in an aqueous environment and, likely, in the presence of minerals. Mineral surfaces present rich opportunities for heterogeneous catalysis and concentration which may have significantly altered and directed the process of prebiotic organic complexification leading to life. We review here general concepts in prebiotic mineral-organic interfacial processes, as well as recent advances in the study of mineral surface-organic interactions of potential relevance to understanding the origin of life.

Covellite CuS as a matrix for "invisible" gold: X-ray spectroscopic study of the chemical state of Cu and Au in synthetic minerals

NASA Astrophysics Data System (ADS)

Tagirov, Boris R.; Trigub, Alexander L.; Kvashnina, Kristina O.; Shiryaev, Andrey A.; Chareev, Dmitriy A.; Nickolsky, Maximilian S.; Abramova, Vera D.; Kovalchuk, Elena V.

2016-10-01

Geological processes leading to formation of sulfide ores often result in precipitation of gold-bearing sulfides which can contain high concentrations of this metal in ;invisible; (or ;refractory;) state. Covellite (CuS) is ubiquitous mineral in many types of the ore deposits, and numerous studies of the natural ores show that covellite can contain high concentrations of Au. At the same time, Au-bearing covellite withstands cooling in contrast to other minerals of the Cu-Fe-S system (chalcocite, bornite, chalcopyrite), where Au exsolves at low temperatures. This makes covellite a convenient model system for investigation of the chemical state (local environment and valence) of the ;invisible; Au in copper-sulfide ores (copper-porphyry, epithermal, volcanogenic massive sulfide, SEDEX deposits). Therefore, it is necessary to determine the location of Au in the covellite matrix as it will have important implications for the methods employed by mineral processing industry to extract Au from sulfide ores. Here we investigate the chemical state of Cu and Au in synthetic covellite containing up to 0.3 wt.% of Au in the ;invisible; state. The covellite crystals were synthesized by hydrothermal and salt flux methods. Formation of the chemically bound Au is indicated by strong dependence of the concentration of Au in covellite on the sulfur fugacity in the experimental system (d(log C(Au))/d(log f(S2)) ∼ 0.65). The Au concentration of covellite grows with increasing temperature from 400 to 450 °C, whereas further temperature increase to 500 °C has only minor effect. The synthesized minerals were studied using X-ray absorption fine structure spectroscopy (XAFS) in high energy resolution fluorescence detection (HERFD) mode. Ab initio simulations of Cu K edge XANES spectra show that the Cu oxidation state in two structural positions in covellite (tetrahedral and triangular coordination with S atoms) is identical: the total loss of electronic charge for the 3d shell is ∼0.3 for both positions of Cu. This result is confirmed by theoretical analysis of electron density performed using quantum theory of atoms in molecules (QTAIM). Modeling of the Au L3 edge EXAFS/XANES spectra showed that Au in covellite exists in the form of the isomorphous solid solution formed by substitution for Cu atoms in triangular coordination with the Me-S distance in the first coordination shell increased by 0.18 Å relative to the pure CuS structure. The ;formal; oxidation state of Au in covellite is +1. The Bader partial atomic charge for Au in covellite is lower than the charge of Cu (+0.2 e vs. +0.5 e) indicating that the degree of covalency for the Au-bearing covellite is higher than that of pure CuS. The analysis of electronic density of states shows that this structural position of Au results in strong interactions between hybridized Au s,p,d, S p, and Cu p,d orbitals. Such chemical bonding of Au to S and Cu can result in the formation of Au-bearing solid solution with other minerals in the Cu-Fe-S system.

Mineralization of aniline in aqueous solution by electrochemical activation of persulfate.

PubMed

Chen, Wen-Shing; Huang, Chi-Pin

2015-04-01

Oxidative degradation of aniline in aqueous solution was carried out by coupling electrolysis with persulfate oxidation, in which a synergistic effect occurred. Experiments were performed under a batch-wise mode to evaluate the influence of various operation parameters on the electrolytic behavior, such as acidity of aqueous solution, temperature, electrode potential, persulfate anion concentration and nitrogen/oxygen gas dosage. The aniline pollutants could be almost entirely mineralized by means of electro-activated persulfate oxidation, wherein sulfate radicals were presumed to be principal oxidizing agents. Besides, electrogenerated hydrogen peroxide originated from cathodic reduction of oxygen, supplied chiefly by anodic oxidation of water, would contribute partially for decomposition of aniline. On the whole, the electro-activated persulfate process is a very promising method for treatment of aniline in wastewater. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adhesion and abrasion of surface materials in the Venusian aeolian environment

NASA Technical Reports Server (NTRS)

Marshall, John R.; Greeley, Ronald; Tucker, David; Fogleman, Guy; Hixon, Raymond

1991-01-01

In laboratory simulations of the Venusian environment, rock and mineral 'target' surfaces struck by aeolian particles develop a thin layer of accretionary material derived from the particles' attrition debris. Accretion may be (in part) a manifestation of 'cold welding', a process well known in engineering, where bonding occurs between metals at a tribological interface. Accretion on geological materials was found to occur at all Venusian surface temperatures and for all types of materials tested. First-order variations in the amount deposited by particles are related to relative attrition susceptibilities. Second-order variations relate to properties of the particle-target interface. Variations in accretion volume are apparently independent of mineral chemistry and are only weakly dependent on crystallography. The results suggest that accretion should be a fairly universal phenomenon in areas of Venus subject to aeolian activity.

Laboratory assessment of bioleaching of shallow eutrophic sediment by immobilized photosynthetic bacteria.

PubMed

Sun, Shiyong; Fan, Shenglan; Shen, Kexuan; Lin, Shen; Nie, Xiaoqin; Liu, Mingxue; Dong, Faqin; Li, Jian

2017-10-01

Eutrophic sediment is a serious problem in ecosystem restoration, especially in shallow lake ecosystems. We present a novel bioleaching approach to treat shallow eutrophic sediment with the objective of preventing the release of nitrate, phosphate, and organic compounds from the sediment to the water column, using porous mineral-immobilized photosynthetic bacteria (PSB). Bioactivity of bacteria was maintained during the immobilization process. Immobilized PSB beads were directly deposited on the sediment surface. The deposited PSB utilized pollutants diffused from the sediment as a nutritive matrix for growth. We evaluated the effects of light condition, temperature, initial pH, amount of PSB beads, and frequency of addition of PSB beads for contaminant removal efficiency during bioleaching operations. The presented study indicated that immobilized PSB beads using porous minerals as substrates have considerable application potential in bioremediation of shallow eutrophic lakes.

Effects of whey protein concentrate, feed moisture and temperature on the physicochemical characteristics of a rice-based extruded flour.

PubMed

Teba, Carla da Silva; Silva, Erika Madeira Moreira da; Chávez, Davy William Hidalgo; Carvalho, Carlos Wanderlei Piler de; Ascheri, José Luis Ramírez

2017-08-01

The influence of whey protein concentrate (WPC), feed moisture and temperature on the physicochemical properties of rice-based extrudates has been investigated. WPC (0.64-7.36g/100g rice) was extruded under 5 moisture (16.64-23.36g/100g) and 5 temperature (106.36-173.64°C) established by a 3 2 central composite rotational design. Physicochemical properties [color, porosimetry, crystallinity, water solubility and absorption, pasting properties, reconstitution test, proximate composition, amino acids, minerals and electrophoresis] were determined. WPC and feed moisture increased redness, yellowness and decreased luminosity. Feed moisture and temperature increased density and total volume pore. WPC and moisture increased crystallinity, but only WPC increased solubility and decrease the retrogradation tendency. Increasing temperature increased the viscosity of the extrudates. The addition of WPC improved the nutritional composition of the extrudates, especially proteins. It is suggested that the extrusion process positively affected the retention of most of the polypeptides chains. Copyright © 2017 Elsevier Ltd. All rights reserved.

30 CFR 227.401 - What are a State's responsibilities if it processes production reports or royalty reports?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and Reports, the MMS Minerals Production Reporter Handbook, any interagency memorandum of... processes production reports or royalty reports? 227.401 Section 227.401 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR MINERALS REVENUE MANAGEMENT DELEGATION TO STATES States...

Principles of Metamorphic Petrology

NASA Astrophysics Data System (ADS)

Williams, Michael L.

2009-05-01

The field of metamorphic petrology has seen spectacular advances in the past decade, including new X-ray mapping techniques for characterizing metamorphic rocks and minerals, new internally consistent thermobarometers, new software for constructing and viewing phase diagrams, new methods to date metamorphic processes, and perhaps most significant, revised petrologic databases and the ability to calculate accurate phase diagrams and pseudosections. These tools and techniques provide new power and resolution for constraining pressure-temperature (P-T) histories and tectonic events. Two books have been fundamental for empowering petrologists and structural geologists during the past decade. Frank Spear's Metamorphic Phase Equilibria and Pressure-Temperature-Time Paths, published in 1993, builds on his seminal papers to provide a quantitative framework for P-T path analysis. Spear's book lays the foundation for modern quantitative metamorphic analysis. Cees Passchier and Rudolph Trouw's Microtectonics, published in 2005, with its superb photos and figures, provides the tools and the theory for interpreting deformation textures and inferring deformation processes.

Strong, tough and stiff bioinspired ceramics from brittle constituents

NASA Astrophysics Data System (ADS)

Bouville, Florian; Maire, Eric; Meille, Sylvain; van de Moortèle, Bertrand; Stevenson, Adam J.; Deville, Sylvain

2014-05-01

High strength and high toughness are usually mutually exclusive in engineering materials. In ceramics, improving toughness usually relies on the introduction of a metallic or polymeric ductile phase, but this decreases the material’s strength and stiffness as well as its high-temperature stability. Although natural materials that are both strong and tough rely on a combination of mechanisms operating at different length scales, the relevant structures have been extremely difficult to replicate. Here, we report a bioinspired approach based on widespread ceramic processing techniques for the fabrication of bulk ceramics without a ductile phase and with a unique combination of high strength (470 MPa), high toughness (22 MPa m1/2), and high stiffness (290 GPa). Because only mineral constituents are needed, these ceramics retain their mechanical properties at high temperatures (600 °C). Our bioinspired, material-independent approach should find uses in the design and processing of materials for structural, transportation and energy-related applications.

[Soil organic carbon mineralization of Black Locust forest in the deep soil layer of the hilly region of the Loess Plateau, China].

PubMed

Ma, Xin-Xin; Xu, Ming-Xiang; Yang, Kai

2012-11-01

The deep soil layer (below 100 cm) stores considerable soil organic carbon (SOC). We can reveal its stability and provide the basis for certification of the deep soil carbon sinks by studying the SOC mineralization in the deep soil layer. With the shallow soil layer (0-100 cm) as control, the SOC mineralization under the condition (temperature 15 degrees C, the soil water content 8%) of Black Locust forest in the deep soil layer (100-400 cm) of the hilly region of the Loess Plateau was studied. The results showed that: (1) There was a downward trend in the total SOC mineralization with the increase of soil depth. The total SOC mineralization in the sub-deep soil (100-200 cm) and deep soil (200-400 cm) were equivalent to approximately 88.1% and 67.8% of that in the shallow layer (0-100 cm). (2) Throughout the carbon mineralization process, the same as the shallow soil, the sub-deep and deep soil can be divided into 3 stages. In the rapid decomposition phase, the ratio of the mineralization or organic carbon to the total mineralization in the sub-deep and deep layer (0-10 d) was approximately 50% of that in the shallow layer (0-17 d). In the slow decomposition phase, the ratio of organic carbon mineralization to total mineralization in the sub-deep, deep layer (11-45 d) was 150% of that in the shallow layer (18-45 d). There was no significant difference in this ratio among these three layers (46-62 d) in the relatively stable stage. (3) There was no significant difference (P > 0.05) in the mineralization rate of SOC among the shallow, sub-deep, deep layers. The stability of SOC in the deep soil layer (100-400 cm) was similar to that in the shallow soil layer and the SOC in the deep soil layer was also involved in the global carbon cycle. The change of SOC in the deep soil layer should be taken into account when estimating the effects of soil carbon sequestration in the Hilly Region of the Loess Plateau, China.

Integrated Spectroscopic Studies of Anhydrous Sulfate Minerals

NASA Technical Reports Server (NTRS)

Lane, M. D.; Bishop, J. L.; Dyar, M. D.; Cloutis, E.; Forray, F. L.; Hiroi, T.

2005-01-01

Sulfates have been identified in Martian soils and bedrock and are emerging as an important indicator for aqueous activity on Mars. Sulfate minerals can form in a variety of low-temperature (evaporitic; chemical-weathering) and high-temperature (volcanic/fumarolic; hydrothermal) environments and their formational environments can range from alkaline to acidic. Although sulfates generally form in the presence of water, not all sulfates are hydrous or contain water in their structures. Many of these anhydrous sulfates (Dana group 28; Strunz class 67A) are minerals that form as accompanying phases to the main minerals in ore deposits or as replacement deposits in sedimentary rocks. However, some form from thermal decomposition of OH or H2O-bearing sulfates, such as from the reaction [1]: jarosite = yavapaiite + Fe2O3 + H2O. Where known, the stability fields of these minerals all suggest that they would be stable under martian surface conditions [2]. Thus, anhydrous sulfate minerals may contribute to martian surface mineralogy, so they must be well-represented in spectral libraries used for interpretation of the Martian surface. We present here the preliminary results of an integrated study of emittance, reflectance, and Mossbauer spectroscopy of a suite of wel-lcharacterized anhydrous sulfates.

Radioactive Demonstration Of Mineralized Waste Forms Made From Hanford Low Activity Waste (Tank SX-105, Tank AN-103, And AZ-101/102) By Fluidized Bed Steam Reformation (FBSR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, C. M.; Crawford, C. L.; Bannochie, C. J.

Fluidized Bed Steam Reforming (FBSR) is a robust technology for the immobilization of a wide variety of radioactive wastes. Applications have been tested at the pilot scale for the high sodium, sulfate, halide, organic and nitrate wastes at the Hanford site, the Idaho National Laboratory (INL), and the Savannah River Site (SRS). Due to the moderate processing temperatures, halides, sulfates, and technetium are retained in mineral phases of the feldspathoid family (nepheline, sodalite, nosean, carnegieite, etc). The feldspathoid minerals bind the contaminants such as Tc-99 in cage (sodalite, nosean) or ring (nepheline) structures to surrounding aluminosilicate tetrahedra in the feldspathoidmore » structures. The granular FBSR mineral waste form that is produced has a comparable durability to LAW glass based on the short term PCT testing in this study, the INL studies, SPFT and PUF testing from previous studies as given in the columns in Table 1-3 that represent the various durability tests. Monolithing of the granular product was shown to be feasible in a separate study. Macro-encapsulating the granular product provides a decrease in leaching compared to the FBSR granular product when the geopolymer is correctly formulated.« less

Quality assessment of compost prepared with municipal solid waste

NASA Astrophysics Data System (ADS)

Jodar, J. R.; Ramos, N.; Carreira, J. A.; Pacheco, R.; Fernández-Hernández, A.

2017-11-01

One way that helps maintain the sustainability of agro-ecosystems land is the application of compost from municipal solid waste as fertilizer, because it can recover the nutrients contained in them, minimizing the negative impact on the environment. Composting as a method for preparing organic fertilizers and amendments is economically and ecologically sound and may well represent an acceptable solution for disposing of municipal solid waste. In the present work, the quality of compost is studied made from municipal solid waste; the content of mineral nutrients: potassium, calcium, magnesium, sodium, zinc, manganese, cupper, iron, nickel, chromium and lead has been investigated. The objective was to evaluate the changes in mineral nutrient concentration during the composting process. The compost was prepared in a pilot-plant using the turning-pile system. Temperature was used as a monitoring parameter to follow the composting progress, which underwent the typical trend of municipal solid waste composting mixtures. The results showed a similar evolution on the content of mineral nutrients of the mixture of municipal solid waste. This evolution originated in a mature compost (end sample) with an adequate content of mineral elements and physical-chemical characteristics for its use in agriculture. So, the use of compost of municipal solid waste represents an important tool for fertilization requirements for its use in agriculture.

Non-equilibrium freezing of water-ice in sandy basaltic regoliths and implications for fluidized debris flows on Mars

NASA Technical Reports Server (NTRS)

Gooding, J. L.

1987-01-01

Many geomorphic features on Mars were attributed to Earth-analogous, cold-climate processes involving movement of water or ice lubricated debris. Clearly, knowledge of the behavior of water in regolith materials under Martian conditions is essential to understanding the postulated geomorphic processes. Experiments were performed with sand-sized samples of natural basaltic regoliths in order to further elucidate how water/regolith interactions depend upon grain size and mineralogy. The data reveal important contrasts with data for clay-mineral substrates and suggest that the microphysics of water/mineral interactions might affect Martian geomorphic processes in ways that are not fully appreciated. Sand and silt sized fractions of two soils from the summit of Mauna Kea were used as Mars-analogous regolith materials. Temperatures were measured for water/ice phase transitions as wet slurries of individual soil fractions which were cooled or heated at controlled rates under a carbon dioxide atmosphere. Freezing and melting of ice was studied as a function of water/soil mass ratio, soil particle size, and thermal-cycle rate. Comparison tests were done under the same conditions with U.S. Geological Survey standard rock powders.

Derivation and calibration of semi-empirical gas geothermometers for Mahanagdong Geothermal Project, Philippines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, D.R.

1996-12-31

The dissolved CO{sub 2}, H{sub 2}S, and H{sub 2} gases in Mahanagdong aquifer fluids are controlled by specific gas-mineral equilibria. At temperature range of 250 to 310 {degrees}C, CO{sub 2} is buffered by clinozoisite + K-feldspar + calcite + muscovite (illite) + quartz mineral assemblage. For H{sub 2}S and H{sub 2} dissolved gases, they are more likely buffered by pyrrhotite + pyrite + magnetite mineral assemblage at similar temperature range. Calibration of five Mahanagdong (MG) gas geothermometers is presented, three of which used CO{sub 2}, H{sub 2}S, and H{sub 2} concentration in steam. The remaining two use CO{sub 2}/H{sub 2}more » and H{sub 2}S/H{sub 2} ratios. The calibration is based on the relation between gas content of drillhole discharges and measured aquifer temperatures. After establishing the gas content in the aquifer, gas concentrations were computed in steam after adiabatic boiling to atmospheric condition (100 {degrees}C), to obtain gas geothermometry functions. These functions could also be used in evaluating fraction of steam condensation and temperature of phase separation. A demonstration given the Mahanagdong fumarole data, indicates that there is generally a fair relation between computed temperatures using Mahanagdong gas geothermometers and the actual field trend`s temperatures.« less

Relationship between fire temperature and changes in chemical soil properties: a conceptual model of nutrient release

NASA Astrophysics Data System (ADS)

Thomaz, Edivaldo L.; Doerr, Stefan H.

2014-05-01

The purpose of this study was to evaluate the effects of fire temperatures (i.e., soil heating) on nutrient release and aggregate physical changes in soil. A preliminary conceptual model of nutrient release was established based on results obtained from a controlled burn in a slash-and-burn agricultural system located in Brazil. The study was carried out in clayey subtropical soil (humic Cambisol) from a plot that had been fallow for 8 years. A set of three thermocouples were placed in four trenches at the following depths: 0 cm on the top of the mineral horizon, 1.0 cm within the mineral horizon, and 2 cm within the mineral horizon. Three soil samples (true independent sample) were collected approximately 12 hours post-fire at depths of 0-2.5 cm. Soil chemical changes were more sensitive to fire temperatures than aggregate physical soil characteristics. Most of the nutrient response to soil heating was not linear. The results demonstrated that moderate temperatures (< 400°C) had a major effect on nutrient release (i.e., the optimum effect), whereas high temperatures (> 500 °C) decreased soil fertility.

The El Teniente porphyry Cu-Mo deposit from a hydrothermal rutile perspective

NASA Astrophysics Data System (ADS)

Rabbia, Osvaldo M.; Hernández, Laura B.; French, David H.; King, Robert W.; Ayers, John C.

2009-11-01

Mineralogical, textural, and chemical analyses (EPMA and PIXE) of hydrothermal rutile in the El Teniente porphyry Cu-Mo deposit help to better constrain ore formation processes. Rutile formed from igneous Ti-rich phases (sphene, biotite, Ti-magnetite, and ilmenite) by re-equilibration and/or breakdown under hydrothermal conditions at temperatures ranging between 400°C and 700°C. Most rutile nucleate and grow at the original textural position of its Ti-rich igneous parent mineral phase. The distribution of Mo content in rutile indicates that low-temperature (˜400-550°C), Mo-poor rutile (5.4 ± 1.1 ppm) is dominantly in the Mo-rich mafic wallrocks (high-grade ore), while high-temperature (˜550-700°C), Mo-rich rutile (186 ± 20 ppm) is found in the Mo-poor felsic porphyries (low-grade ore). Rutile from late dacite ring dikes is a notable exception to this distribution pattern. The Sb content in rutile from the high-temperature potassic core of the deposit to its low-temperature propylitic fringe remains relatively constant (35 ± 3 ppm). Temperature and Mo content of the hydrothermal fluids in addition to Mo/Ti ratio, modal abundance and stability of Ti-rich parental phases are key factors constraining Mo content and provenance in high-temperature (≥550°C) rutile. The initial Mo content of parent mineral phases is controlled by melt composition and oxygen fugacity as well as timing and efficiency of fluid-melt separation. Enhanced reduction of SO2-rich fluids and sulfide deposition in the Fe-rich mafic wallrocks influences the low-temperature (≤550°C) rutile chemistry. The data are consistent with a model of fluid circulation of hot (>550°C), oxidized (ƒO2 ≥ NNO + 1.3), SO2-rich and Mo-bearing fluids, likely exsolved from deeper crystallizing parts of the porphyry system and fluxed through the upper dacite porphyries and related structures, with metal deposition dominantly in the Fe-rich mafic wallrocks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Liange; Rutqvist, Jonny; Kim, Kunhwi

The focus of research within the UFD Campaign is on repository-induced interactions that may affect the key safety characteristics of an argillaceous rock. These include thermal-hydrological-mechanical-chemical (THMC) process interactions that occur as a result of repository construction and waste emplacement. Some of the key questions addressed in this report include the development of fracturing in the excavation damaged zone (EDZ) and THMC effects on the near-field argillaceous rock and buffer minerals and petrophysical characteristics, particularly the impacts of induced temperature rise caused by waste heat.

Hot Oil Removes Wax

NASA Technical Reports Server (NTRS)

Herzstock, James J.

1991-01-01

Mineral oil heated to temperature of 250 degrees F (121 degrees C) found effective in removing wax from workpieces after fabrication. Depending upon size and shape of part to be cleaned of wax, part immersed in tank of hot oil, and/or interior of part flushed with hot oil. Pump, fittings, and ancillary tooling built easily for this purpose. After cleaning, innocuous oil residue washed off part by alkaline aqueous degreasing process. Serves as relatively safe alternative to carcinogenic and environmentally hazardous solvent perchloroethylene.

Structure and stability of pyrophyllite edge surfaces: Effect of temperature and water chemical potential

NASA Astrophysics Data System (ADS)

Kwon, Kideok D.; Newton, Aric G.

2016-10-01

The surfaces of clay minerals, which are abundant in atmospheric mineral dust, serve as an important medium to catalyze ice nucleation. The lateral edge surface of 2:1 clay minerals is postulated to be a potential site for ice nucleation. However, experimental investigations of the edge surface structure itself have been limited compared to the basal planes of clay minerals. Density functional theory (DFT) computational studies have provided insights into the pyrophyllite edge surface. Pyrophyllite is an ideal surrogate mineral for the edge surfaces of 2:1 clay minerals as it possesses no or little structural charge. Of the two most-common hydrated edge surfaces, the AC edge, (1 1 0) surface in the monoclinic polytype notation, is predicted to be more stable than the B edge, (0 1 0) surface. These stabilities, however, were determined based on the total energies calculated at 0 K and did not consider environmental effects such as temperature and humidity. In this study, atomistic thermodynamics based on periodic DFT electronic calculations was applied to examine the effects of environmental variables on the structure and thermodynamic stability of the common edge surfaces in equilibrium with bulk pyrophyllite and water vapor. We demonstrate that the temperature-dependent vibrational energy of sorbed water molecules at the edge surface is a significant component of the surface free energy and cannot be neglected when determining the surface stability of pyrophyllite. The surface free energies were calculated as a function of temperature from 240 to 600 K and water chemical potential corresponding to conditions from ultrahigh vacuum to the saturation vapor pressure of water. We show that at lower water chemical potentials (dry conditions), the AC and B edge surfaces possessed similar stabilities; at higher chemical potentials (humid conditions) the AC edge surface was more stable than the B edge surface. At high temperatures, both surfaces showed similar stabilities regardless of the water chemical potential. The equilibrium morphology of pyrophyllite crystals is also expected to be dependent on these two environmental variables. Surface defects may impact the surface reactivity. We discuss the thermodynamic stability of a possible Si cation vacancy defect which provides additional hydroxyl group on the surface.

Biogeochemical Controls on Microbial CO2 and CH4 Production in Polygonal Soils From the Barrow Environmental Observatory

NASA Astrophysics Data System (ADS)

Graham, D. E.; Roy Chowdhury, T.; Herndon, E.; Gu, B.; Liang, L.; Wullschleger, S. D.

2014-12-01

Organic matter buried in Arctic soils and permafrost will become accessible to increased microbial degradation as the ground warms due to climate change. The rates of organic matter degradation and the proportion of CH4 and CO2 greenhouse gasses released in a potential warming feedback cycle depend on the microbial response to warming, organic carbon structure and availability, the pore-water quantity and geochemistry, and available electron acceptors. Significant amounts of iron(II) ions in organic and mineral soils of the active layer in low-centered ice wedge polygons indicate anoxic conditions in most soil horizons. To adapt and improve the representation of these Arctic subsurface processes in terrestrial ecosystem models for the NGEE Arctic project, we examined soil organic matter transformations from elevated and subsided areas of low- and high-centered polygons from interstitial tundra on the Barrow Environmental Observatory (Barrow, AK). Using microcosm incubations at fixed temperatures and controlled thawing systems for frozen soil cores, we investigated the microbiological processes and rates of soil organic matter degradation and greenhouse gas production under anoxic conditions, at ecologically relevant temperatures of -2, +4 or +8 °C. In contrast to the low-centered polygon incubations representing in situ water-saturated conditions, microcosms with unsaturated high-centered polygon samples displayed lower carbon mineralization as either CH4 or CO2. Substantial differences in CH4 and CO2 response curves from different microtopographic samples separate the thermodynamic controls on biological activity from the kinetic controls of microbial growth and migration that together determine the temperature response for greenhouse gas emissions in a warming Arctic.

Early Implementation of Large Scale Carbon Dioxide Removal Projects through the Cement Industry

NASA Astrophysics Data System (ADS)

Zeman, F. S.

2014-12-01

The development of large-scale carbon dioxide reduction projects requires high purity CO2and a reactive cation source. A project seeking to provide both of these requirements will likely face cost barriers with current carbon prices. The cement industry is a suitable early implementation site for such projects by virtue of the properties of its exhaust gases and those of waste concrete. Cement plants are the second largest source of industrial CO2 emissions, globally. It is also the second largest commodity after water, has no ready substitute and is literally the foundation of society. Finally, half of the CO2 emissions originate from process reactions rather than fossil fuel combustion resulting in higher flue gas CO2concentrations. These properties, with the co-benefits of oxygen combustion, create a favorable environment for spatially suitable projects. Oxygen combustion involves substituting produced oxygen for air in a combustion reaction. The absence of gaseous N2 necessitates the recirculation of exhaust gases to maintain kiln temperatures, which increase the CO2 concentrations from 28% to 80% or more. Gas exit temperatures are also elevated (>300oC) and can reach higher temperatures if the multi stage pre-heater towers, that recover heat, are re-designed in light of FGR. A ready source of cations can be found in waste concrete, a by-product of construction and demolition activities. These wastes can be processed to remove cations and then reacted with atmospheric CO2 to produce carbonate minerals. While not carbon negative, they represent a demonstration opportunity for binding atmospheric CO2while producing a saleable product (precipitated calcium carbonate). This paper will present experimental results on PCC production from waste concrete along with modeling results for oxygen combustion at cement facilities. The results will be presented with a view to mineral sequestration process design and implementation.

Contaminant Removal from Oxygen Production Systems for In Situ Resource Utilization

NASA Technical Reports Server (NTRS)

Anthony, Stephen M.; Santiago-Maldonado, Edgardo; Captain, James G.; Pawate, Ashtamurthy S.; Kenis, Paul J. A.

2012-01-01

The In Situ Resource Utilization (ISRU) project has been developing technologies to produce oxygen from lunar regolith to provide consumables to a lunar outpost. The processes developed reduce metal oxides in the regolith to produce water, which is then electrolyzed to produce oxygen. Hydrochloic and hydrofluoric acids are byproducts of the reduction processes, as halide minerals are also reduced at oxide reduction conditions. Because of the stringent water quality requirements for electrolysis, there is a need for a contaminant removal process. The Contaminant Removal from Oxygen Production Systems (CROPS) team has been developing a separation process to remove these contaminants in the gas and liquid phase that eliminates the need for consumables. CROPS has been using Nafion, a highly water selective polymeric proton exchange membrane, to recover pure water from the contaminated solution. Membrane thickness, product stream flow rate, and acid solution temperature and concentration were varied with the goal of maximizing water permeation and acid rejection. The results show that water permeation increases with increasing solution temperature and product stream flow rate, while acid rejection increases with decreasing solution temperature and concentration. Thinner membranes allowed for higher water flux and acid rejection than thicker ones. These results were used in the development of the hardware built for the most recent Mars ISRU demonstration project.

Potato Production, Usage, and Nutrition--A Review.

PubMed

Zaheer, Khalid; Akhtar, M Humayoun

2016-01-01

Potato is an economically important staple crop prevailing all across the world with successful large-scale production, consumption, and affordability with easy availability in the open market. Potatoes provide basic nutrients such as-carbohydrates, dietary fiber (skin), several vitamins, and minerals (e.g., potassium, magnesium, iron). On occasion exposures to raw and cooked potatoes impart allergic reactions. Dietary intake of potatoes, especially colored potatoes, play an important role in the production of antioxidant defense system by providing essential nutrient antioxidants, such as vitamins, β-carotene, polyphenols, and minerals. This may help lower the incidence of wide range of chronic and acute disease processes (like hypertension, heart diseases, cancer, neurodegenerative, and other diseases). However, retention of nutrients in potatoes is affected by various cooking and processing methods. Cooking at elevated temperature also produces acrylamide-a suspected carcinogen. Independent and/or collaborative studies have been conducted and reported on the various pathways leading to the formation of acrylamide in heat processed foods. This article reviews the latest research on potato production, consumption, nature of phytochemicals and their health benefits, and allergic reactions to children. Also included is the discovery of acrylamide in processed starch-rich foods including potatoes, mechanism of formation, detection methodologies, and mitigation steps to reduce acrylamide content in food.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagy, Kathryn L.; Sturchio, Neil C.

This project, renewal of a previous EMSP project of the same title, is in its first year of funding at the University of Illinois at Chicago. The purpose is to continue investigating rates and mechanisms of reactions between primary sediment minerals found in the Hanford subsurface and leaked waste tank solutions. The goals are to understand processes that result in (1) changes in porosity and permeability of the sediment and resultant changes in flow paths of the contaminant plumes, (2) formation of secondary precipitates that can take up contaminants in their structures, and (3) release of mineral components that canmore » drive redox reactions affecting dissolved contaminant mobility. A post-doctoral scientist, Dr. Sherry Samson, has been hired and two masters of science students are beginning to conduct experimental research. One research project that is underway is focused on measurement of the dissolution rates of plagioclase feldspar in high pH, high nitrate, high Al-bearing solutions characteristic of the BX tank farms. The first set of experiments is being conduced at room temperature. Subsequent experiments will examine the role of temperature because tank solutions in many cases were near boiling when leakage is thought to have occurred and temperature gradients have been observed beneath the SX and BX tank farms. The dissolution experiments are being conducted in stirred-flow kinetic reactors using powdered labradorite feldspar from Pueblo Park, New Mexico.« less

A role for subducted super-hydrated kaolinite in Earth’s deep water cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, Huijeong; Seoung, Donghoon; Lee, Yongjae

Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slabmore » (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H2O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.« less

A role for subducted super-hydrated kaolinite in Earth's deep water cycle

NASA Astrophysics Data System (ADS)

Hwang, Huijeong; Seoung, Donghoon; Lee, Yongjae; Liu, Zhenxian; Liermann, Hanns-Peter; Cynn, Hyunchae; Vogt, Thomas; Kao, Chi-Chang; Mao, Ho-Kwang

2017-12-01

Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slab (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H2O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.

Potential climate change impacts on temperate forest ecosystem processes

USGS Publications Warehouse

Peters, Emily B.; Wythers, Kirk R.; Zhang, Shuxia; Bradford, John B.; Reich, Peter B.

2013-01-01

Large changes in atmospheric CO2, temperature and precipitation are predicted by 2100, yet the long-term consequences for carbon, water, and nitrogen cycling in forests are poorly understood. We applied the PnET-CN ecosystem model to compare the long-term effects of changing climate and atmospheric CO2 on productivity, evapotranspiration, runoff, and net nitrogen mineralization in current Great Lakes forest types. We used two statistically downscaled climate projections, PCM B1 (warmer and wetter) and GFDL A1FI (hotter and drier), to represent two potential future climate and atmospheric CO2 scenarios. To separate the effects of climate and CO2, we ran PnET-CN including and excluding the CO2 routine. Our results suggest that, with rising CO2 and without changes in forest type, average regional productivity could increase from 67% to 142%, changes in evapotranspiration could range from –3% to +6%, runoff could increase from 2% to 22%, and net N mineralization could increase 10% to 12%. Ecosystem responses varied geographically and by forest type. Increased productivity was almost entirely driven by CO2 fertilization effects, rather than by temperature or precipitation (model runs holding CO2 constant showed stable or declining productivity). The relative importance of edaphic and climatic spatial drivers of productivity varied over time, suggesting that productivity in Great Lakes forests may switch from being temperature to water limited by the end of the century.

Decomposition of soil organic matter from boreal black spruce forest: Environmental and chemical controls

USGS Publications Warehouse

Wickland, K.P.; Neff, J.C.

2008-01-01

Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of this soil carbon. It is unclear, however, how changes in environmental conditions influence decomposition in these systems, and if substrate controls of decomposition vary with hydrologic and thermal regime. We addressed these issues by investigating the effects of temperature, moisture, and organic matter chemical characteristics on decomposition of fibric soil horizons from three black spruce forest sites. The sites varied in drainage and permafrost, and included a "Well Drained" site where permafrost was absent, and "Moderately well Drained" and "Poorly Drained" sites where permafrost was present at about 0.5 m depth. Samples collected from each site were incubated at five different moisture contents (2, 25, 50, 75, and 100% saturation) and two different temperatures (10??C and 20??C) in a full factorial design for two months. Organic matter chemistry was analyzed using pyrolysis gas chromatography-mass spectrometry prior to incubation, and after incubation on soils held at 20??C, 50% saturation. Mean cumulative mineralization, normalized to initial carbon content, ranged from 0.2% to 4.7%, and was dependent on temperature, moisture, and site. The effect of temperature on mineralization was significantly influenced by moisture content, as mineralization was greatest at 20??C and 50-75% saturation. While the relative effects of temperature and moisture were similar for all soils, mineralization rates were significantly greater for samples from the "Well Drained" site compared to the other sites. Variations in the relative abundances of polysaccharide-derivatives and compounds of undetermined source (such as toluene, phenol, 4-methyl phenol, and several unidentifiable compounds) could account for approximately 44% of the variation in mineralization across all sites under ideal temperature and moisture conditions. Based on our results, changes in temperature and moisture likely have similar, additive effects on in situ soil organic matter (SOM) decomposition across a wide range of black spruce forest systems, while variations in SOM chemistry can lead to significant differences in decomposition rates within and among forest sites. ?? 2007 Springer Science+Business Media B.V.

Effect of organic matter properties, clay mineral type and thermal maturity on gas adsorption in organic-rich shale systems

USGS Publications Warehouse

Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Lewan, Mike; Sun, Xun; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

2013-01-01

A series of CH4 adsorption experiments on natural organic-rich shales, isolated kerogen, clay-rich rocks, and artificially matured Woodford Shale samples were conducted under dry conditions. Our results indicate that physisorption is a dominant process for CH4 sorption, both on organic-rich shales and clay minerals. The Brunauer–Emmett–Teller (BET) surface area of the investigated samples is linearly correlated with the CH4 sorption capacity in both organic-rich shales and clay-rich rocks. The presence of organic matter is a primary control on gas adsorption in shale-gas systems, and the gas-sorption capacity is determined by total organic carbon (TOC) content, organic-matter type, and thermal maturity. A large number of nanopores, in the 2–50 nm size range, were created during organic-matter thermal decomposition, and they significantly contributed to the surface area. Consequently, methane-sorption capacity increases with increasing thermal maturity due to the presence of nanopores produced during organic-matter decomposition. Furthermore, CH4 sorption on clay minerals is mainly controlled by the type of clay mineral present. In terms of relative CH4 sorption capacity: montmorillonite ≫ illite – smectite mixed layer > kaolinite > chlorite > illite. The effect of rock properties (organic matter content, type, maturity, and clay minerals) on CH4 adsorption can be quantified with the heat of adsorption and the standard entropy, which are determined from adsorption isotherms at different temperatures. For clay-mineral rich rocks, the heat of adsorption (q) ranges from 9.4 to 16.6 kJ/mol. These values are considerably smaller than those for CH4 adsorption on kerogen (21.9–28 kJ/mol) and organic-rich shales (15.1–18.4 kJ/mol). The standard entropy (Δs°) ranges from -64.8 to -79.5 J/mol/K for clay minerals, -68.1 to -111.3 J/mol/K for kerogen, and -76.0 to -84.6 J/mol/K for organic-rich shales. The affinity of CH4 molecules for sorption on organic matter is stronger than for most common clay minerals. Thus, it is expected that CH4 molecules may preferentially occupy surface sites on organic matter. However, active sites on clay mineral surfaces are easily blocked by water. As a consequence, organic-rich shales possess a larger CH4-sorption capacity than clay-rich rocks lacking organic matter. The thermodynamic parameters obtained in this study can be incorporated into model predictions of the maximum Langmuir pressure and CH4- sorption capacity of shales under reservoir temperature and pressure conditions.

Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

USGS Publications Warehouse

Sturchio, N.C.; Keith, T.E.C.; Muehlenbachs, K.

1990-01-01

Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199??C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The ??18O values of the thirty-two analyzed silica samples (quartz, chalcedony, ??-cristobalite, and ??-cristobalite) range from -7.5 to +2.8???. About one third of the silica 7samples have ??18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7???) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have ??18O values higher (by 3.5 to 7.9???) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with deposition during transient boiling or rock-water exchange (fracturing) events. ?? 1990.

Structural study of graphite materials prepared by HTT of unburned carbon concentrates from coal combustion fly ashes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miguel Cabielles; Miguel A. Montes-Moran; Ana B. Garcia

2008-03-15

Unburned carbon concentrates with different mineral matter contents were obtained from coal combustion fly ashes by an oil agglomeration procedure. The concentrates were then heated in the temperature interval 1800-2700{sup o}C for the purpose of exploring their ability to graphitize. The influence of the treatment temperature and mineral matter of the unburned carbon on the structural characteristics of the materials prepared was studied. The interlayer spacing, d{sub 002}, and crystallite sizes along the c-axis, L{sub c}, and the {alpha}-axis, L{sub a}, calculated from X-ray diffractometry (XRD) as well as the relative intensity of the Raman D-band, I{sub D}/I{sub t}, weremore » used to assess the degree of structural order of the materials. Graphite materials with structural characteristics comparable to those of other oil-derived synthetic graphites were prepared from the unburned carbon concentrates at temperatures {>=}2400{sup o}C. It was also observed that more-ordered materials were obtained from the unburned carbon concentrates with higher mineral matter content. The influence of the mineral matter on the graphitization of the unburned carbon concentrates is the result of two countereffects, thus limiting its extent. On the one hand, the lateral coalescence of the crystallites is preferentially promoted. Reasonably good linear correlations were attained between the mineral matter of the unburned carbon concentrate and the XRD parameter L{sub a} of the materials. However, on the other, this coalescence also facilitates the flattening of the pores, thus decreasing the temperature at which their breakage occurs. As a consequence, from this point on, the structural evolution of the materials with increasing mineral matter is only noticeable by the slow vegetative growth of the crystallites along the a-axis. 40 refs., 2 figs., 3 tabs.« less

Petromagnetic Properties In The Naica Mining District, Chihuahua, Mexico: Searching For Source of Mineralization

NASA Astrophysics Data System (ADS)

Alva, L.; Gogichaishvili, A.; Urrutia, J.

Ore mineral and host lithologies have been sampled with 89 oriented samples from 14 sites in the Naica District, northern Mexico. Magnetic parameters permit to charac- terise samples: saturation magnetization, density, low- high-temperature magnetic sus- ceptibility, remanence intensity, Koenigsberger ratio, Curie temperature and hystere- sis parameters. Rock magnetic properties are controlled by variations in titanomag- netite content and hydrothermal alteration. Post-mineralization hydrothermal alter- ation seems the major event that affected the minerals and magnetic properties. Curie temperatures are characteristic of titanomagnetites or titanomaghemites. Hysteresis parameters indicate that most samples have pseudo-single domain (PSD) magnetic grains. Alternating filed (AF) demagnetization and isothermal remanence (IRM) ac- quisition both indicate that natural and laboratory remanences are carried by MD-PSD spinels in the host rocks. The trend of NRM intensity vs susceptibility suggests that the carrier of remanent and induced magnetization is the same in all cases (spinels). The Koenigsberger ratio range from 0.05 to 34.04, indicating the presence of MD and PSD magnetic grains. Constraints on the geometry of the intrusive source body devel- oped in the model of the magnetic anomaly are obtained by quantifying the relative contributions of induced and remanent magnetization components.

Mineral disequilibrium in lavas explained by convective self-mixing in open magma chambers.

PubMed

Couch, S; Sparks, R S; Carroll, M R

2001-06-28

Characteristic features of many porphyritic andesite and dacite lavas are that they are rich in crystals and display a range of disequilibrium features, including reversely zoned crystals, resorption surfaces, wide ranges of mineral compositions and minerals which are not in equilibrium with the surrounding rock matrix. These features are often interpreted as evidence of the mixing of magmas of contrasting composition, temperature and origin. Here, however, we propose that such features can also be caused by convection within a magma body with a single composition, that is heated from below and cooled from above. We describe petrological observations of andesite lava erupted at the Soufrière Hills volcano, Montserrat, which indicate a heating event and the intermingling of crystals that have very different thermal histories. We present experimental data on a representative groundmass composition of this lava, which indicate that it is difficult to explain the calcic compositions of plagioclase overgrowth rims and microphenocrysts unless parts of the magma were at temperatures much higher than the inferred average temperature. The concept of convective self-mixing allows us to explain the occurrence of compositions of minerals that apparently cannot coexist under equilibrium conditions.

The arsenic removal from arsenopyrite in sulfide mineral by physicochemical extraction

NASA Astrophysics Data System (ADS)

Jo, Jiyu; Cho, Kanghee; Choi, Nagchoul; Park*, Cheonyoung

2015-04-01

The most abundant As ore mineral is arsenopyrite (FeAsS). Arsenopyrite is present in sulfide ores associated with sediment-hosted Au deposits, it tends to be the earliest-formed mineral, derived from hydrothermal solutions and formed at temperatures typically of 100(degree Celsius) or more. The aim of this study was to investigate the mineralogical phase change and arsenic removal from arsenopyrite as a penalty element in sulfide mineral contained Au by physical extraction (high frequency) and chemical leaching (thiocyanate). Arsenic removal experiments for were performed under various conditions of high frequency exposure(1~35 min), thiocyanate concentration (0.1~1.0M), HCl concentration (0.1~2.0M), copper(2) sulfate concentration (0.1~1.0M), temperature (30~60 degree Celsius). Increasing the high frequency exposure produced a positive effect on arsenic removal in arsenopyrite. The highest percentage arsenic removal of 96.67% was obtained under the following conditions by thiocyanate leaching: thiocyanate concentration = 1.0M ; HCl concentration = 2.0M ; copper(2) sulfate concentration = 1.0M ; temperature = 60(degree Celsius) This study demonstrates the adequate performance of physical extraction (high frequency) and chemical leaching (thiocyanate) for the arsenic removal from arsenopyrite as a penalty element.

Breakdown Characteristics and Streaming Electrification Characteristics of Flame Retardant Silicone Oil

NASA Astrophysics Data System (ADS)

Arazoe, Satoshi; Yasuda, Koji; Okabe, Shigemitsu; Ueta, Genyo; Yanabu, Satoru

We have investigated the performance of the silicone oil as alternative oil to the mineral oil that is used as an insulation medium of the oil immersed transformer. There are various methods of evaluating the performance, we especially investigated the breakdown characteristics and the streaming electrification characteristics. In the breakdown characteristics, the insulation performance under the influence of changing the temperature, and the electrode shape was investigated. Moreover, the insulation performance in the composite insulation system that was composed of the insulation oil and the oil immersed insulator was investigated. From these results, we found that in the oil gap model, the breakdown voltage of silicone oil was lower than that of mineral oil by 15%. In contrast, in the composite insulation system, breakdown voltage of combination with silicone oil is higher than that of combination with mineral oil. In the streaming electrification characteristics, the difference of the amount of electrification under the influence of changing the kinds of solid insulators and the temperature was investigated. As a result, we found that silicone oil has the maximum of the amount of electrification at a high temperature compared with mineral oil.

Trace element abundances in major minerals of Late Permian coals from southwestern Guizhou province, China

USGS Publications Warehouse

Zhang, Jiahua; Ren, D.; Zheng, C.; Zeng, R.; Chou, C.-L.; Liu, J.

2002-01-01

Fourteen samples of minerals were separated by handpicking from Late Permian coals in southwestern Guizhou province, China. These 14 minerals were nodular pyrite, massive recrystallized pyrite, pyrite deposited from low-temperature hydrothermal fluid and from ground water; clay minerals; and calcite deposited from low-temperature hydrothermal fluid and from ground water. The mineralogy, elemental composition, and distribution of 33 elements in these samples were studied by optical microscopy, scanning electron microscope equipped with energy-dispersive X-ray spectrometer (SEM-EDX), X-ray diffraction (XRD), cold-vapor atomic absorption spectrometry (CV-AAS), atomic fluorescence spectrometry (AFS), inductively coupled-plasma mass spectrometry (ICP-MS), and ion-selective electrode (ISE). The results show that various minerals in coal contain variable amounts of trace elements. Clay minerals have high concentrations of Ba, Be, Cs, F, Ga, Nb, Rb, Th, U, and Zr. Quartz has little contribution to the concentration of trace elements in bulk coal. Arsenic, Mn, and Sr are in high concentrations in calcite. Pyrite has high concentrations of As, Cd, Hg, Mo, Sb, Se, Tl, and Zn. Different genetic types of calcite in coal can accumulate different trace elements; for example Ba, Co, Cr, Hg, Ni, Rb, Sn, Sr, and Zn are in higher concentrations in calcite deposited from low-temperature hydrothermal fluid than in that deposited from ground water. Furthermore, the concentrations of some trace elements are quite variable in pyrite; different genetic types of pyrites (Py-A, B, C, D) have different concentrations of trace elements, and the concentrations of trace elements are also different in pyrite of low-temperature hydrothermal origin collected from different locations. The study shows that elemental concentration is rather uniform in a pyrite vein. There are many micron and submicron mosaic pyrites in a pyrite vein, which is enriched in some trace elements, such as As and Mo. The content of trace element in pyrite vein depends upon the content of mosaic pyrite and of trace elements in it. Many environmentally sensitive trace elements are mainly contained in the minerals in coal, and hence the physical coal cleaning techniques can remove minerals from coal and decrease the emissions of potentially hazardous trace elements. ?? 2002 Elsevier Science B.V. All rights reserved.

Shining a light on Jarosite: formation, alteration and stability studies using in situ experimental synchrotron and neutron techniques.

NASA Astrophysics Data System (ADS)

Brand, H. E. A.; Scarlett, N. V. Y.; Wilson, S. A.; Frierdich, A. J.; Grey, I. E.

2016-12-01

Jarosites and related minerals are critical to a range of mineral processing and research applications. They are used in the removal of iron species from smelting processes; they occur in metal bioleaching systems, and they are present in acid mine drainage environments. There has been a recent resurgence in interest in jarosites since their detection on Mars. In this context, the presence of jarosite has been recognised as a likely indicator of liquid water at the surface of Mars in the past & it is thought that their study will provide insight into the environmental history of Mars. Acid sulfate soils cover large areas of the Australian coastline and are likely to be a major constituent of the Martian environment. The oxidation of acid sulfate soils, coupled with potential release of heavy metals and acidic groundwaters, can have serious consequences for fragile ecosystems. Understanding these sediments will provide insight into the biogeochemical processes that affect the lifetimes of transient mineral species on Earth, and may be used to better understand soil acidification, contaminant mobility at sites affected by acid and metalliferous drainage, and even constrain past weathering and putative biosignatures on Mars. Knowledge of the behaviour of jarosite minerals under the actual conditions that they are found in is crucial to understanding their potential environmental impacts on both Earth and Mars. To this end, we are engaged in a program to study the formation, stability and alteration of natural and synthetic jarosite minerals using a complementary suite of in situ synchrotron and neutron techniques. There are 3 sections to this work that will introduce the experimental techniques and sample environments that make these measurements possible: Studying the nucleation and growth of jarosites under laboratory conditions. The experimentation consisted of time-resolved synchrotron small angle X-ray scattering and X-ray diffraction. Studying the stability of natural & synthetic jarosites with temperature and pressure using synchrotron and neutron diffraction. Parallel neutron and X-ray imaging at OPAL and the Australian Synchrotron, combined with synchrotron pseudo-microdiffraction to map the mineralogy and structural relationships within naturally occurring jarosite nodules.

Enrichment of Gold in Antimony Matte by Direct Smelting of Refractory Gold Concentrate

NASA Astrophysics Data System (ADS)

Yang, Tianzu; Xie, Boyi; Liu, Weifeng; Zhang, Duchao; Chen, Lin

2018-04-01

Conventional cyanidation technology achieves low gold recovery when used to process refractory gold concentrate. Based on the geochemical characteristics of gold deposit mineralization, a new method is proposed herein for gold enrichment in antimony matte by smelting of refractory gold concentrate. The effects of the FeO/SiO2 and CaO/SiO2 ratios, smelting temperature, and smelting time on the gold recovery were investigated in detail. The optimum conditions were determined to be FeO/SiO2 ratio of 1.2, CaO/SiO2 ratio of 0.4, smelting temperature of 1200°C, and smelting time of 45 min. The gold content in antimony matte and smelting slag was 96.68 and 1.13 g/t, respectively. The gold, antimony, and arsenic recovery was 97.72%, 26.89%, and 6.56%, respectively, with most of the antimony and arsenic volatilized into dust. Mineral liberation analyzer results showed that the antimony matte mainly consisted of FeS and FeO, with three phases, viz. FeAs, SbAs, and AuSb, embedded between them, indicating that gold was easily enriched with antimony and arsenic during smelting of refractory gold concentrate.

Effects of amendment of different biochars on soil physical and biological properties related to carbon mineralization

NASA Astrophysics Data System (ADS)

Zhang, Renduo; Zhu, Shuzhi; Ouyang, Lei

2014-05-01

Biochar addition to soils potentially affects various soil properties, and these effects are dependent on biochars derived from different feedstock materials and pyrolysis processes. The objective of this study was to investigate the effects of amendment of different biochars on soil physical and biological properties. Biochars were produced with dairy manure and woodchip at temperatures of 300, 500, and 700°C, respectively. Each biochar was mixed at 5% (w/w) with a forest soil and the mixture was incubated for 180 days, during which soil physical and biological properties, and soil respiration rates were measured. Results showed that the biochar addition significantly enhanced the formation of soil macroaggregates at the early incubation time. The biochar application significantly reduced soil bulk density, increased the amount of soil organic matter, and stimulated microbial activity and soil respiration rates at the early incubation stage. Biochar applications improved water retention capacity, with stronger effects by biochars produced at higher pyrolysis temperatures. At the same suction, the soil with woodchip biochars possessed higher water content than with the dairy manure biochars. Biochar addition significantly affected the soil physical and biological properties, which resulted in different soil carbon mineralization rates.