Harnessing Peridotite Alteration for Carbon Capture and Storage

Mantle peridotite, composed largely of the mineral olivine with Mg end-member Mg2SiO4, is far from equilibrium with the atmosphere and surface waters. Where peridotite comes to the surface via plate tectonics, faulting and erosion, this creates a huge, accessible reservoir of chemical potential energy, which drives rapid reaction and can support subsurface chemosynthetic ecosystems. Feedbacks in reactive transport lead to two very different outcomes. Hydration, carbonation and oxidation cause large increases in the mass and volume of solid phases, which can fill pore space, destroy permeability, and armor reactive surfaces, in a self-limiting, negative feedback. As a result, we can sample high grade metamorphic rocks on the Earth’s surface. Alternatively, heating due to exothermic reactions can accelerate reaction rates. More importantly, volume change due to increasing solid mass and decreasing density converts chemical potential energy to work, and can cause differential stresses that are sufficient to fracture rocks. This reaction-driven cracking process can maintain or enhance permeability and reactive surface area, in a positive feedback system leading to complete equilibration of fluid with altered peridotite. In some natural geologic settings, complete reaction of peridotite with CO2-rich hydrothermal fluid forms “listvenites”, rocks in which all Mg and Ca atoms combine with CO2 to form solid carbonate minerals. For example, olivine Mg2SiO4 reacts with dissolved CO2 in water to form magnesite MgCO3 + quartz SiO2. More commonly, all dissolved carbon is removed from ground water migrating through peridotite-hosted aquifers, by precipitation of Mg carbonates in the subsurface. C-depleted, CaOH-rich, alkaline water (pH 11.5) then returns to the surface, where it draws down additional CO2 from air to form extensive terraces composed of calcite CaCO3. Various avenues of research focus on emulating these natural processes to design engineered methods for carbon capture and storage that make maximum use of available chemical potential to minimize cost and energy use. One set of ideas focuses on solid storage of carbon which has already been captured via some other technique. Fluids with high P(CO2) - CO2-saturated water, H2O-saturated supercritical CO2, “seltzer”, perhaps even flue gas - could be injected into a peridotite-hosted aquifer, where they will react rapidly to form solid carbonate minerals. Such a system would be similar to the CarbFix project in Iceland, where “seltzer” is injected into basalt-hosted aquifers. However, reaction-rates and uptake capacities are larger in peridotite-hosted environments. On the other hand, basalt formations are more common, and generally have more ambient, initial permeability than peridotite. Alternatively, a more faithful emulation of natural systems involves CO2 removal from air, for example via enhanced reaction of surface water with peridotite. The simplest, “low-hanging fruit” in this context involves various methods to induce enhanced circulation of water through fine-grained mine tailings. Hundreds of millions of tons of CO2 could be captured and stored in this way, before extant peridotite mine-tailings were totally consumed. Thermal convection of seawater through subsurface, fractured, peridotite, could also achieve CO2 removal from air. The simplest, and thus probably lowest cost implementation would involve artesian production of warm, carbon-free, CaOH-rich alkaline waters from existing subsurface aquifers in peridotite. Once at the surface, these waters will draw down CO2 from air to form solid carbonate minerals. A geologist’s level analysis (not an economist’s!) suggests that the cost of such a system could be less than $100 per ton of CO2 captured and stored, provided that aquifers with permeability ~ 10^-12 m^2 can be found. Various hybrid technologies can be envisioned, for example geothermal power plants using CO2-rich fluids, in which carbon mineralization consumes CO2 along the fluid circulation path. However, successful implementation of such “hot dry rock” geothermal systems is problematic, with or without CO2 in the heat transfer fluid. More generally, if we understood how to induce reaction-driven cracking, there might be other applications for such techniques, including enhanced extraction of oil and gas from tight reservoirs using CO2 as a reactant to produce a ramified crack network at the grain scale. In addition, it may be important to understand and forestall reaction-driven cracking, in wellbore cement and in natural permeability barriers - such as carbonate-bearing shales - above storage reservoirs for acidic water saturated in supercritical CO2

Untersuchungen zur Seroprävalenz der Virus-Hepatitiden im Krankengut des Institutes für Medizinische Virologie der Universitätsklinik Frankfurt am Main

Für Hepatitis-Viren sind für Westeuropa im allgemeinen und Deutschland im besonderen niedrige bis sehr niedrige Belastungen dokumentiert. In der vorliegenden Arbeit wurde die Prävalenz der serologischen Marker der verschiedenen Erreger in Proben, die dem Institut für Medizinische Virologie der Universitätsklinik Frankfurt am Main vorgelegt wurden, untersucht. Aus den Jahren 1995 - 2002 wurden 220.468 Tests auf Hepatitis-Virus-Antikörper sowie HBs-Antigen und HGV-RNA in die Analysen einbezogen. Dabei ließ sich ein starker Rückgang der jährlichen Testzahlen vom Höchststand in 1996 mit 30.566 auf nur noch 20.435 in 2002 (-33%) belegen. Außerdem wurden die Präferenzen bei den einzelnen Erregern deutlich: 98% aller Untersuchungen entfielen auf die Hepatitis-Viren A-C und ganze 4.114 Tests auf die Viren D-G. Bei der Hepatitis-A-Infektion, die fast immer folgenlos ausheilt und eine lebenslange Immunität hinterlässt, spiegelten die Antikörper-Prävalenzen die kumulative Wahrscheinlichkeit für den Erregerkontakt mit einem altersabhängig hohen Gesamtdurchschnitt (48,02%) wider. Der Nachweis von viralem Antigen bzw. Genom zeigte die aktuelle Infektionslage (für HBV mit 3,9% und HGV mit 6,06%). Bei Erkrankungen, die zu einem komplizierten Verlauf neigen und/oder keine langfristige Immunität hinterlassen, standen unterschiedliche Antikörper-Prävalenzen für das jeweilige Risiko (im Mittel HBV 19,15%, HCV 11,51%, HDV 6,55%, HEV 3,98%). Diese Zahlen liegen über den in anderen Untersuchungen für die deutsche Gesamtbevölkerung angegebenen Werten. Das ist insofern nicht verwunderlich, als hier kein Normalkollektiv untersucht wurde, sondern belastete Probanden, bei denen bereits eine Infektion vermutet wurde oder die einer erhöhten Infektionsgefahr ausgesetzt waren. Die Auswertung der Daten für spezifische Risikogruppen belegte die höhere Belastung von HIV-Positiven und i.v. -Drogenabhängigen für fast alle Hepatitis-Viren, während sich für Empfänger von Organen, Blut- und Blutprodukten vielfach eine unterdurchschnittliche oder zumindest eine gegenüber früheren Untersuchungen gesunkene Belastung als Bestätigung für vorgeschriebene Screening-Methoden zeigte. Ein ähnliches Bild bot das medizinische Personal, das lediglich bei den akuten HBV-Erkrankungen über dem Durchschnitt lag. Die Aufnahme der Hepatitis-B-Impfung in den Impfkalender der STIKO (Ständige Impfkommission am Robert-Koch-Institut) zeigte schon in den ersten acht Jahren einen beachtlichen Erfolg: bereits in dieser kurzen Zeit stieg die Anti-HBs-Prävalenz bei den Unter-10-Jährigen von anfangs 21,53% auf 82,50%. Dabei hatten in 1995 lediglich 40% die Antikörper durch eine Immunisierung, folglich 60% aufgrund einer Infektion entwickelt. Bis zum Jahr 2002 verschob sich dieses Verhältnis auf 96,49% vs. 3,51% zu Gunsten der Impfung.Viral hepatitis is reported to have low or even very low rates generally in western Europe and particularly in Germany. In this paper the seroprevalence of different hepatitis-markers has been investigated in samples examined at the Institute of Medical Virology, University Clinic Frankfurt. 220,468 tests for hepatitis antibodies, HBs-antigen and HGV-RNA from 1995 to 2002 have been included. The average number of tests decreased from its highest level in 1996 at 30,566 to only 20,435 in 2002 (-33%). Of these 98% was performed on hepatitis A-C, but only 4,114 on hepatitis D-G. For hepatitis A the prevalence of antibodies represented the age-dependent cumulative probability of viral confrontation (mean 48.02%), since they can be detected after infection for a life-time and almost all affected individuals survive. The presence of viral antigen or genome showed actual infection for HBV in 3.90% and for HGV in 6.06%. In more severe cases or if the antibodies are only detectable for a short time their prevalence characterized the risk of contagion (mean levels: HBV 19.15%, HCV 11.51%, HDV 6.55%, HEV 3.98%). These results showed higher rates than those found in other analyses for the German population in general. The reason for this was the fact that only samples from presumably infected individuals or those at high risk were sent to the Institute of Virology in Frankfurt and not from average or even healthy citizens. Data for specific risk groups verified higher prevalence in almost all hepatitis viruses for HIV-positives and intravenous drug abusers. However patients after transplantation or transfusion often showed under average or at least decreasing levels compared with earlier analyses. This proves the positive effect of the mandatory screening methods. Similar conditions were found for medical personnel. Only eight years after inventing hepatitis B immunisation as a standard procedure for children by the STIKO (Ständige Impfkommission am Robert-Koch-Institut) the results were obvious: within this short period the prevalence of anti-HBs-antibodies in children under 10 years increased from 21.53% to 82.50%. Of these in 1995 only 40% had developed antibodies after immunisation but 60% after infection. By 2002 this proportion shifted to 96.49% immunisation versus 3.51% infection

Advanced aerospace management of integrated education and training towards comprehensive security

The aviatic integrated education and training based on the progressive technologies towards comprehensive security will be necessary for the future specialized preparation and training of the personnel in civil and military aerospace management and aviation, especially for expeditionary missions. The integrated pilot flight preparation and training based on the modern methodology of situational control would be used for improving our general system of present preparation and training, within the framework of the Armed Forces of the Slovak Republic

Theorizing on the connection between organizational and individual mindfulness

This paper explores the relationship between individual mindful- ness and organizational mindfulness. Many authors consider these concepts to be related and interlocked, however, the exact nature of this connection is still unclear. Therefore, we investigate the link between these two concepts using both literature review approach and theoretical reflection. The results of the literature review are classified and synthesized in a constructive way into a theoretical framework that sheds light on the main aspects of the relationship between individual and collective mindfulness. Our research shows that the existence of organizational mindfulness implies the existence of mindfulness on the individual level. Individual mindfulness is a necessary, but not sufficient condition to developing organizational mindfulness. Additional factors other than individual mindfulness must be included in order to increase organizational mindfulness. The reason for this is the difference between individual mindfulness, an intrapsychic process of indi- viduals, and organizational mindfulness, which is a function of social procedures in an organization

Relationship between seismic P-wave velocity and the composition of anhydrous igneous and meta-igneous rocks

Author Posting. © American Geophysical Union 2003. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 4 (2003): 1041, doi:10.1029/2002GC000393.This study presents a new approach to quantitatively assess the relationship between the composition and seismic P-wave velocity of anhydrous igneous and meta-igneous rocks. We perform thermodynamic calculations of the equilibrating phase assemblages predicted for all igneous composition space at various pressure and temperature conditions. Seismic velocities for each assemblage are then estimated from mixing theory using laboratory measurements of the elastic parameters for pure mineral phases. The resultant velocities are used to derive a direct relationship between Vp and major element composition valid to ±0.13 km/s for pressure and temperature conditions along a normal crustal geotherm in the depth range of 5–50 km and equilibration pressures ≤12 kbar. Finally, we use the calculated velocities to invert for major element chemistry as a function of P-wave velocity assuming only the in situ temperature and pressure conditions are known. Compiling typical velocity-depth profiles for the middle and lower continental and oceanic crust, we calculate compositional bounds for each of these geologic environments. We find that the acceptable compositional range for the middle (15–30 km) and lower continental (≥35 km) crust is broad, ranging from basaltic to dacitic compositions, and conclude that P-wave velocity measurements alone are insufficient to provide fundamental constraints on the composition of the middle and lower continental crust. However, because major oxides are correlated in igneous rocks, joint constraints on Vp and individual oxides can narrow the range of acceptable crustal compositions. In the case of the lower oceanic crust (≥2 km), observed velocities are 0.2–0.3 km/s lower than velocities calculated based on the average bulk composition of gabbros in drill cores and exposed ophiolite sequences. We attribute this discrepancy to a combination of residual porosity at crustal depths less than ∼10 km and hydrous alteration phases in the lower crust, and suggest caution when inferring mantle melting parameters from observed velocities in the lower oceanic crust.This research was supported by National Science Foundation Grants OCE- 9819666, EAR-9910899, and EAR-0087706 (P.B. Kelemen)

Highly depleted cratonic mantle in West Greenland extending into diamond stability field in the Proterozoic

This study presents electron microprobe data for dunite xenoliths from a lamprophyre dyke located on the island of Qeqertaa, West Greenland. The minimum age of this dyke is Palaeoproterozoic and it experienced amphibolite facies metamorphism and deformation during that era. The samples consist of nearly 200 xenoliths with a size range of 0.5-8 cm. These dunite xenoliths have olivine Mg#, that range from 80.3 to 94.6 (n = 579) with a mean of 92.6. Orthopyroxene is found in three xenoliths and garnet in five others. The latter suggests the depth of the Qeqertaa xenolith suite to be near the diamond stability-field, which is substantiated by the finding of diamonds in bulk samples of the Qeqertaa dyke. This further indicates the presence of a lithospheric mantle domain dominated by high-Mg# dunite to this depth in Palaeoproterozoic time. Cr-rich spinel, in the 0.1–0.2 mm size range, is found within and between olivine grains in individual xenoliths. These Cr-spinels yield Fe–Mg exchange temperatures of 400–600 °C. However, the presence of intermediate spinel compositions spanning the lower temperature solvus suggests that equilibration temperatures were > 550 °C. Fe3 +#, expressed as 100 × Fe3 +/(Fe3 + + Al + Cr), is shown to be a useful parameter in order to screen for altered spinel (Fe3 +# > 10) with disturbed Mg# and Cr#. The screened spinel data (Fe3 +# < 10) show a distinctly different trend in terms of spinel Cr# versus Mg#, compared to unmetamorphosed xenoliths in Tertiary lavas and dikes from Ubekendt Ejland and Wiedemann Fjord, respectively, also located within the North Atlantic craton. This difference likely reflects amphibolite facies metamorphic resetting of the Qeqertaa xenolith suite by Fe–Mg exchange. Given the similarity of the Qeqertaa xenolith suite with the Ubekendt and Wiedemann suites, in terms of their olivine Mg# and spinel Cr# distribution, high-Mg# dunite is likely to be an important component of the subcontinental lithospheric mantle beneath the North Atlantic craton and appears to have spanned a vertical distance of at least 150 km in this region, even during the Palaeoproterozoic

Quantitativer Nachweis chlorungsvorgeschädigter Escherichia coli

Zum Schutz von Umwelt und Bevölkerung vor unerwünschten Nebenwirkungen wird vielfach der Einsatz von Chemikalien auf ein notwendiges Minimum reduziert. Gerade in der Trinkwasseraufbereitung muss deren Wirkung sorgfältig und zuverlässig kontrolliert werden, da es bei einer Unterdosierung leicht zur Kontamination mit Mikroorganismen kommt. Ein Verfahren mag zum Nachweis solcher Mikroorganismen als geeignet erscheinen, wenn es intakte Keime anzeigt. Gerade in vorbehandelten Proben können jedoch nach einer unvollständigen Desinfektion geschädigte Zellen enthalten sein, die sich unter günstigen Bedingungen erholen (Resuscitation), d. h. ihre Vermehrungsfähigkeit wiedererlangen und dadurch Infektionen auslösen können. Also sollten dafür verwendete Medien auch solche Erreger erfassen, da ansonsten falsch negative Ergebnisse die Folge sind. Im mehrstufigen Nachweis von Escherichia coli nach den Deutschen Einheitsverfahren zur Wasser, Abwasser und Schlammuntersuchung (DEV) wird eine Lactose-Pepton-Lösung als Primärkulturmedium beschrieben, die schon für das Membranfilter-Verfahren als nicht optimal eingestuft wurde. Diese Problematik hatte sich in der vorliegenden Arbeit auch für die Flüssig- keitsanreicherung, das zweite Verfahren nach den DEV, gezeigt. Als Ursache für die verminderten Angehraten im DEV-Medium konnte das darin in einer Kon- zentration von 20 µg/l enthaltene Bromkresolpurpur identifiziert werden. Um das Wachstum bestimmter Mikroorganismen anhand ihrer spezifischen Stoffwechselleistungen anzuzeigen, werden geeignete Substrate in Kombination mit entsprechenden pH-Indikatoren verwendet, zu denen auch das Bromkresolpurpur zählt. Für ungeschädigte Keime hatte letzteres im Vergleich mit anderen, Selektionsmitteln enthaltenden Nährmedien besser abgeschnitten und wurde als weniger giftig" bezeichnet. Bei den in dieser Arbeit untersuchten chlorungsvorgeschädigten Zellen bewirkte es eine signifikante Wachstumshemmung. Im Zuge der weiteren Untersuchungen konnte gezeigt werden, dass eine Verminderung der Bromkresolpurpur-Konzentration auf 10 µg/l nur noch bei einem Teil und auf 5 µg/l bei keinem der verwendeten Stämme mehr eine signifikante Veränderung der Angehrate bewirkte. Die Funktion als Farbindikator wurde dadurch nicht beeinträchtigt

Peridotite enclaves hosted by Mesoarchaean TTG-suite orthogneisses in the Fiskefjord region of southern West Greenland

AbstractThis study presents bulk-rock major, trace, and platinum-group element data, as well as mineral chemistry for peridotites which form large enclaves (up to 500×1000m) within Mesoarchaean orthogneisses of the Akia terrane in the Fiskefjord region, southern West Greenland. The largest peridotite body, known as Seqi, contains highly fosteritic olivine with a median Mg# of 92.6 and hosts extensive layers of chromitite, which can be traced for tens of metres with thicknesses of up to 30cm. Thinner (<100m thick), but extensive (up to 2000m long) peridotite sheets are associated with coarse norite and orthopyroxenite with distinct cumulate textures in the Amikoq complex, located a few tens of kilometres south of Seqi. Intercalated amphibolites of tholeiitic basaltic composition show complementary geochemical evolution to the peridotites, consistent with igneous crystal fractionation trends. The U-shaped trace element patterns of the peridotites may either reflect the parental melt composition from which these olivine-rich rocks were derived, or alternatively this feature may be the result of melt-rock interaction. Overall, we interpret the Fiskefjord region peridotites to have formed as ultramafic cumulates derived from Archaean high-Mg, low Ca/Al magmas, although their geodynamic setting remains to be established

Coexisting serpentine and quartz from carbonate-bearing serpentinized peridotite in the Samail Ophiolite, Oman

Tectonically exposed mantle peridotite in the Oman Ophiolite is variably serpentinized and carbonated. Networks of young carbonate veins are prevalent in highly serpentinized peridotite, particularly near low-temperature alkaline springs emanating from the peridotite. An unusual feature in some samples is the coexistence of serpentine and quartz, which is not commonly observed in serpentinites. This assemblage is unstable with respect to serpentine + talc or talc + quartz under most conditions. Serpentine in the carbonated serpentinites in this study is more iron rich than in most serpentinites reported in previous studies, and samples with co-existing quartz contain the most iron-rich serpentines. Calculations of thermodynamic equilibria in the MgO–SiO2–H2O–CO2 system suggest that serpentine + quartz may be a stable assemblage at low temperatures (e.g., <~15–50 °C) and is stabilized to higher temperatures by preferential cation substitutions in serpentine over talc. Based on these calculations, serpentine + quartz assemblages could result from serpentinization at near-surface temperatures. Clumped isotope thermometry of carbonate veins yields temperatures within error of the observed temperatures in Oman groundwater for all samples analyzed, while the δ^18O of water calculated to be in equilibrium with carbonate precipitated at those temperatures is within error of the observed isotopic composition of Oman groundwater for the majority of samples analyzed. As groundwater geochemistry suggests that carbonate precipitation and serpentinization occur concomitantly, this indicates that both hydration and carbonation of peridotite are able to produce extensive alteration at the relatively low temperatures of the near-surface weathering environment

A detailed geochemical study of island arc crust : the Talkeetna Arc section, south–central Alaska

Author Posting. © The Author, 2006. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Journal of Petrology 47 (2006): 1051-1093, doi:10.1093/petrology/egl002.The Early to Middle Jurassic Talkeetna Arc section exposed in the Chugach Mountains of south central Alaska is 5-18 km wide and extends for over 150 km. This accreted island arc includes exposures of upper mantle to volcanic upper crust. The section comprises six lithologic units, in order of decreasing depth: (1) residual upper mantle harzburgite (with lesser proportions of dunite); (2) pyroxenite; (3) basal gabbronorite; (4) lower crustal gabbronorite; (5) mid-crustal plutonic rocks; and (6) volcanic rocks. The pyroxenites overlie residual mantle peridotite, with some interfingering of the two along the contact. The basal gabbronorite overlies pyroxenite, again with some interfingering of the two different units along their contact. Lower crustal gabbronorite (≤10 km thick) includes abundant rocks with well developed modal layering. The mid-crustal plutonic rocks include a heterogeneous assemblage of gabbroic rocks, dioritic to tonalitic rocks (30-40% area), and concentrations of mafic dikes and chilled mafic inclusions. The volcanic rocks (~7 km thick) range from basalt to rhyolite. Many of the evolved volcanic compositions are a result of fractional crystallisation processes whose cumulate products are directly observable in the lower crustal gabbronorites. For example, Ti and Eu enrichments in lower crustal gabbronorites are mirrored by Ti and Eu depletions in evolved volcanics. In addition, calculated parental liquids from ion microprobe analyses of clinopyroxene in lower crustal gabbronorites indicate that the clinopyroxenes crystallised in equilibrium with liquids whose compositions were the same as the compositions of volcanic rocks. The compositional variation of the main series of volcanic and chilled mafic rocks can be modeled through fractionation of observed phase compositions and phase proportions in lower crustal gabbronorite (i.e. cumulates). Primary, mantle-derived melts in the Talkeetna Arc underwent fractionation of pyroxenite at the base of the crust. Our calculations suggest that more than 25 wt % of the primary melts crystallised as pyroxenites at the base of the crust. The discrepancy between the observed proportion of pyroxenites (less than 5% of the arc section) and the proportion required by crystal fractionation modeling (more than 25%) may be best understood as the result of gravitational instability, with dense ultramafic cumulates, probably together with dense garnet granulites, foundering into the underlying mantle during the time when the Talkeetna Arc was magmatically active, or in the initial phases of slow cooling (and sub-solidus garnet growth) immediately after the cessation of arc activity.This study was supported by National Science Foundation Grant EAR-9910899