Well-based, Geochemical Leakage Monitoring of an Aquifer Immediately Above a CO2 Storage Reservoir by Stable Carbon Isotopes at the Ketzin Pilot Site, Germany

AbstractWe measured dissolved inorganic carbon (DIC) stable isotopes (813CDIC in ‰) of brine from an observation well within the first aquifer above the CO2 reservoir at the Ketzin pilot site, to test weather these can detect potential CO2 leakage. The monitoring revealed that DIC concentrations and 813CDIC values were masked by the used high alkaline drilling mud, even eight months after well development. However, subsequent changes in 813CDIC and DIC from of -27 ‰ and 165mg L−1 to -23.5 ‰ and 116mg L−1 reflect most likely a shift towards pristine values of the aquifer

Applications of stable water and carbon isotopes in watershed research: Weathering, carbon cycling, and water balances

Research on rivers has traditionally involved concentration and flux measurements to better understand weathering, transport and cycling of materials from land to ocean. As a relatively new tool, stable isotope measurements complement this type of research by providing an extra label to characterize origin of the transportedmaterial, its transfer mechanisms, and natural versus anthropogenic influences. These new stable isotope techniques are scalable across a wide range of geographic and temporal scales. This review focuses on three aspects of hydrological and geochemical river research that are of prime importance to the policy issues of climate change and include utilization of stable water and carbon isotopes: (i) silicate and carbonate weathering in river basins, (ii) the riverine carbon and oxygen cycles, and (iii) water balances at the catchment scale. Most studies at watershed scales currently focus on water and carbon balances but future applications hold promise to integrate sediment fluxes and turnover, ground and surface water interactions, as well as the understanding of contaminant sources and their effects in river systems

Contribution of Herpesvirus Specific CD8 T Cells to Anti-Viral T Cell Response in Humans

Herpesviruses infect most humans. Their infections can be associated with pathological conditions and significant changes in T cell repertoire but evidences of symbiotic effects of herpesvirus latency have never been demonstrated. We tested the hypothesis that HCMV and EBV-specific CD8 T cells contribute to the heterologous anti-viral immune response. Volume of activated/proliferating virus-specific and total CD8 T cells was evaluated in 50 patients with acute viral infections: 20 with HBV, 12 with Dengue, 12 with Influenza, 3 with Adenovirus infection and 3 with fevers of unknown etiology. Virus-specific (EBV, HCMV, Influenza) pentamer+ and total CD8 T cells were analyzed for activation (CD38/HLA-DR), proliferation (Ki-67/Bcl-2low) and cytokine production. We observed that all acute viral infections trigger an expansion of activated/proliferating CD8 T cells, which differs in size depending on the infection but is invariably inflated by CD8 T cells specific for persistent herpesviruses (HCMV/EBV). CD8 T cells specific for other non-related non persistent viral infection (i.e. Influenza) were not activated. IL-15, which is produced during acute viral infections, is the likely contributing mechanism driving the selective activation of herpesvirus specific CD8 T cells. In addition we were able to show that herpesvirus specific CD8 T cells displayed an increased ability to produce the anti-viral cytokine interferon-γ during the acute phase of heterologous viral infection. Taken together, these data demonstrated that activated herpesvirus specific CD8 T cells inflate the activated/proliferating CD8 T cells population present during acute viral infections in human and can contribute to the heterologous anti-viral T cell response

Stable isotope record of Devonian brachiopd shell calcite

In dieser Studie wurden devonische Brachiopoden aus unterschiedlichen paläogeographischen Einheiten (Nordamerika, Spanien, Marokko, Deutschland, Russland und China) untersucht. Alle Brachiopodenschalen wurden sorgfältig mittels Kathodenlumineszenz, Spurenelementchemie (Sr, Mn, Fe) sowie Rasterelektronenmikroskopie auf ihren Erhaltungszustand untersucht. Proben, die Anzeichen für diagenetische Veränderungen zeigten, wurden ebenso wie punctate bzw. pseudopunctate Schalen von den weiteren Untersuchungen ausgeschlossen. Nach Abschluss der Voruntersuchungen wurden 409 Brachiopodenschalen, an denen d13C und d18O bestimmt wurde, in den Gesamtdatensatz übernommen. An 72 ausgewählten Proben wurde zusätzlich das 87Sr/86Sr-Verhältnis bestimmt. Aus den Daten wurde mit Hilfe eines nichtparametrischen, lokal gewichteten Regressionsverfahrens (Locfit), das sich besonders zur Glättung nicht äquidistant verteilter Daten eignet, Isotopenkurven berechnet. Die d13C- und d18O-Kurven umfassen den Zeitabschnitt mittleres Emsium bis mittleres Famennium, die 87Sr/86Sr-Kurve den Abschnitt Lochkovium bis mittleres Famennium. Die Kohlenstoffisotopenkurve zeigt vier positive d13C-Exkursionen (australis-Zone, Kacak-Event, Unteres und Oberes Kellwasser-Event), die zeitlich mit Sedimenten korrelieren, die einen erhöhten Anteil an organischem Kohlenstoff beinhalten. Die positiven d13C-Exkursionen werden als Folge einer Erhöhung des Anteils organischen Materials an der Gesamtkohlenstoffsedimentation interpretiert. Die beiden d13C-Exkursionen der Kellwasser-Events werden von zwei positiven d18O-Exkusionen begleitet, die einen Temperaturabfall anzeigen. Ursache des Temperaturrückgangs, der an der F/F-Grenze etwa 6 °C beträgt, war wahrscheinlich die Verringerung des Kohlendioxidpartialdrucks der Atmosphäre (pCO2), was wiederum durch die verstärkten Sedimentation organischen Materials verursacht wurde. In der neueren Literatur wird für die Kohlen- und Sauerstoffisotopie von Calcit ein Einfluss des pH-Wertes diskutiert. Die Untersuchung des Einflusses eines veränderten pCO2 auf den pH-Wert des Oberflächenwassers zeigt, dass eine Verzehnfachung des Kohlendioxidpartialdrucks eine Verringerung des pH-Wertes um 0,5 Einheiten zur Folge hat. Die beobachteten, kurzfristigen d13C- und d18O-Exkursionen können damit keine Folge sich rasch ändernder pH-Bedingungen gewesen sein, da hierzu extreme pH-Wert Schwankungen erforderlich gewesen wären. Die pH-Wert abhängige Temperaturkorrektur führt für das Devon, je nach pCO2-Modell, zu Oberflächenwassertemperaturen, die um 1,5 °C bis 3,5 °C über den Temperaturen liegen, die ohne Berücksichtigung des pH-Effektes berechnet werden. Die Sauerstoffisotopenkurve zeigt neben den kurzfristigen, temperaturbedingten Exkursionen vom Mittel- zum Oberdevon eine längerfristige Entwicklung zu niedrigeren d18O-Werten. Während die d18O-Werte der berechneten Kurve im Emsium, Eifelium und frühen Givetium konstant bei rund –3,0 ‰ liegen, sinkt die Kurve im späten Givetium deutlich ab und erreicht mit –6,1 ‰ im spätesten Givetium ein Minimum. Im Frasnium und Famennium verläuft die Kurve mit Werten zwischen –4,3 ‰ und –5,7 ‰ deutlich unter den Werten, die zuvor im Unter- und dem größten Teil des Mitteldevons auftreten. Der Kurvenverlauf wird als Kombination aus Temperaturanstieg und gleichzeitigem Rückgang des d18O-Wertes des Meerwassers (d18Ow) interpretiert. Im Unter- und Mitteldevon ergeben sich unter Annahme eines d18Ow-Wertes von –1,0 ‰ (VSMOW) Temperaturen von rund 25 °C. Im späten Mitteldevon und im Oberdevon liegen die berechneten Temperaturen unter Annahme eines um 1,5 ‰ niedrigeren d18Ow-Wertes zwischen 24 °C und maximal 33 °C (d18Ow = –2,5 ‰). Diese Temperaturen sind mit der beobachteten reichen, marinen Fauna, die beispielsweise eine hohe Anzahl hermatypischer, stenothermer Korallen enthält, vereinbar. Parallel zum Rückgang des d18Ow-Wertes findet mit dem Taghanic Onlap (Basis T-R Zyklus IIa) ein bedeutender Meeresspiegelanstieg statt. Der Verlauf der Strontiumisotopenkurve wird durch den Verwitterungseintrag bestimmt. Der Einfluss hydrothermaler Prozesse spielt, wenn überhaupt, nur eine untergeordnete Rolle. Der Rückgang des 87Sr/86Sr-Verhältnisses im Unterdevon korreliert mit dem Abklingen der Kaledonischen Orogenese. Mit Beginn des Mitteldevons geht die Kurve an der Grenze Eifelium/Givetium in einen flachen Verlauf über. Während dieses Zeitabschnitts herrscht ein Gleichgewichtszustand zwischen Verwitterungseintrag und hydrothermalem Strontiumeintrag. Zeitgleich mit dem Abfall der d18O-Werte und dem Taghanic Onlap kommt es im späten Givetium zu einem Anstieg des 87Sr/86Sr-Verhältnisses, was auf die Temperaturerhöhung und den dadurch verstärkten Verwitterungseintrag zurückgeführt wird. Die berechnete Locfit-Kurve der Strontiumisotopenwerte kann in den Bereichen mit ausreichend großer Steigung als stratigraphisches Werkzeug zur Datierung und Korrelation eingesetzt werden.Devonian brachiopods from different paleogeographic locations (North America, Spain, Morocco, Russia, Germany, and China) were analyzed in this study. All brachiopod shells were thoroughly examined for their preservation state by cathodoluminescence, trace element chemistry (Sr, Mn, Fe) and scanning electron microscopy. Samples, which indicated diagenetic alteration, as well as punctate and pseudopunctate shells were rejected. 409 shells, which were measured for their d13C and d18O isotopic composition, were taken into the final data set. 87Sr/86Sr analysis was carried out on 72 selected samples. Isotope curves were calculated from the data using a nonparametric locally-weighted regression method (Locfit). This method is particularly suitable for smoothing unevenly spaced data points. d13C and d18O isotope curves cover the period from the middle Emsian to the middle Famennian, the 87Sr/86Sr curve stretches from the Lochkovian to the middle Famennian. The carbon isotope curve shows four positive d13C excursions (australis zone, Kacak event, Lower and Upper Kellwasser event), which correlate with sediments containing an increased amount of organic carbon. The positive d13C excursions are interpreted as the result of enhanced organic carbon burial. The two d13C excursions correlating with the Kellwasser events are accompanied by two positive d18O excursions indicating a drop in temperature. The cooling, which is about 6 °C at the F/F boundary, was probably caused by a lowering of atmospheric carbon dioxide concentrations (pCO2), which in turn was the result of increased organic carbon burial. A pH dependence of the carbon and oxygen isotopic composition of calcite is discussed in the recent literature. Examination of the influence of changing pCO2 on the pH of the ocean surface water shows, that a tenfold increase of the pCO2 causes a decrease of the pH by 0.5 units. Therefore, the observed short term d13C and d18O excursions can not be attributed to rapid changing pH conditions, since this would require extreme pH fluctuations. For the Devonian, the pH dependent temperature correction results in sea surface temperatures, which are 1.5 °C to 3.5 °C higher than temperatures calculated without taking into account the pH effect. The amplitude of the temperature correction depends on the used pCO2 model. The oxygen isotope curve shows short term excursions, which are the result of temperature changes. In addition, the curve exhibits a long term trend to generally lower d18O values from the Middle to the Late Devonian. The d18O values of the calculated curve show constant values around –3 ‰ in the Emsian, Eifelian, and the early Givetian. Starting in the late Givetian, the curve reaches a minimum value of –6.1 ‰ in the latest Givetian. During the Frasnian and Famennian, the curve runs between –4.3 ‰ and –5.7 ‰, which is significantly lower than the values observed in the Lower Devonian and most of the Middle Devonian. The shape of the curve is interpreted to be the result of a combination of temperature rise and simultaneous decrease of the d18O of sea water (d18Ow). Temperatures are about 25 °C for the Lower and Middle Devonian assuming a d18Ow of –1.0 ‰ (VSMOW). For the latest Middle and Late Devonian the d18Ow is assumed to be 1.5 ‰ lower (d18Ow = –2.5 ‰). The calculated temperatures for this time period range from 24 °C to a maximum of 33 °C. These temperatures are consistent with the observed rich marine facies with abundant hermatypic, stenothermal corals. The drop of the d18Ow is paralleled by the important sea level rise of the Taghanic onlap (basis of T R cycle IIa). The shape of the strontium isotope curve is controlled by the weathering flux. The hydrothermal strontium flux is of secondary importance only. The decrease of the 87Sr/86Sr in the Lower Devonian correlates with the ending of the Caledonian orogeny. At the Eifelian/Givetian boundary, the curve turns to a flat slope. During this period, a balance between the riverine strontium flux and the hydrothermal strontium flux prevailed. Simultaneous to the decrease of the d18O values and the Taghanic onlap in the late Givetian, a rise of 87Sr/86Sr is observed. This rise is attributed to an enhanced weathering rate caused by increasing temperatures. In parts where the slope is steep enough, the calculated Locfit curve can serve as a stratigraphic dating and correlation tool

Hydrogeological investigation of shallow aquifers in an arid data-scarce coastal region (El Daba’a, northwestern Egypt)

Hydrogeological investigations in arid regions are particularly important to support sustainable development. The study area, El Daba'a in northwestern Egypt, faces scarce water resources as a result of reported climate change that particularly affects the southern Mediterranean coast and increases stress on the local groundwater reserves. This change in climate affects the area in terms of drought, over-pumping and unregulated exploration of groundwater for irrigation purposes. The hydrogeological investigation is based on a multidisciplinary data-layer analysis that includes geomorphology, geology, slope, drainage lines, soil type, structural lineaments, subsurface data, stable isotopes, and chemical analyses. The study area contains Pleistocene and middle Miocene marine limestone aquifers. Based on lithology and microfacies analysis, the middle Miocene aquifer is subdivided into two waterbearing zones. The area is affected by sets of faults and anticline folds, and these structures are associated with fractures and joints that increase permeability and facilitate the recharge of groundwater. Stable isotope data indicate that groundwater of both the Pleistocene and middle Miocene aquifers is recharged by modern precipitation. The high salinity values observed in some groundwater wells that tap both aquifers could be attributed to leaching and dissolution processes of marine salts from the aquifers' marine limestone matrix. In addition, human activities can also contribute to an increase in groundwater salinity. A future water exploration strategy, based on the results from the multidisciplinary data-layer analysis, is proposed for the area. The derived scientific approach is transferable to other arid coastal areas with comparable conditions

Boron isotope geochemistry of Paleozoic brachiopod calcite: Implications for a secular change in the boron isotope geochemistry of seawater over the Phanerozoic

International audience—Boron isotope composition of marine carbonates has been proposed as a paleo-pH proxy and potential tool to reconstruct atmospheric pCO2. The precise knowledge of the boron isotopic composition of ancient seawater represents the fundamental prerequisite for any paleo-pH reconstruction. This contribution presents boron isotope values for Silurian to Permian brachiopod calcite that might be used to reconstruct pH or boron isotope composition of past oceans. All brachiopod shells were screened for diagenetic recrystallization by means of cathodoluminescence microscopy, trace element geochemistry (B, Fe, Mn, Sr) as well as SEM. Only nonluminescent shells revealing well-preserved microstructures, high strontium and boron concentrations as well as low iron and manganese contents were accepted for boron isotope analysis. The boron isotope ratios of Silurian, Devonian, Pennsylvanian and Permian brachiopod calcite range from 6.8 to 11.0‰, 7.3 to 14.9‰, 12.4 to 15.8‰ and 10.1 to 11.7‰, respectively. These δ 11B values are significantly lower in comparison to δ 11 B values of modern biogenic carbonates and indicate that the Paleozoic oceans were depleted in 11B by up to 10‰. Box modeling of the boron geochemical cycle suggests that the significant depletion of 11B in the oceanic reservoir may have been initiated by an enhanced continental boron discharge. Our data support the earlier made conclusion that boron isotopes may not be used in the geological past as reliable paleo-pH proxy unless the boron isotopic composition of ancient oceans can be constrained by further studies

CO2 degassing from karstic springs in Southern Germany

This study examines characteristics of dissolved inorganic carbon (DIC) and partial pressures of CO2 characteristics (pCO2) in the source springs and headwaters of four karstic watersheds, via dissolved inorganic carbon concentration and stable carbon isotope measurements. All four spring sources are located in Southern Germany and were measured for water chemistry and stable isotopes with nearby headwater stream points, which were located up to 100 m downstream of the discharge points. Seasonal sampling covered winter, spring, summer, and autumn in 2018