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    Paleothermometers

Klimaforschung

Der Klimawandel ist eine der größten Bedrohungen der menschlichen Zivilisation. Klimaszenarien der Zukunft können nur auf Basis dessen berechnet werden, was wir über die Vergangenheit wissen. Durch das Verständnis der Variabilität des Klimas und der Mechanismen, welche die globalen Klimakreisläufe beeinflussen, sind Wissenschaftler in der Lage, anspruchsvolle Modelle unseres zukünftigen Klimas zu entwickeln und liefern entscheidende Informationen für die Öffentlichkeit und Regierungen über mögliche Konsequenzen anthropogener Aktivitäten.

Die Stabilisotopenanalyse fungiert als ein virtuelles Paläothermometer, an dem vergangene Temperaturen von einer Vielzahl von Materialien wie Mikrofossilien, Eisbohrkernen und Baumringen abgelesen werden können. Durch das Kombinieren dieser Temperaturinformationen und der Extrapolation der Daten in die Zukunft sind wir in der Lage, die schlimmsten Auswirkungen des Klimawandels zu verhindern. Die Stabilisotopenanalyse wird eine entscheidene Rolle spielen, uns dabei zu helfen.

Carbonate

Klimasignale liegen am Meeresgrund in Form von sedimentierten Carbonaten altertümlicher Biota vor. Die 13C and 18O Isotopenverhältnisse dieser Materialien stehen in direktem Zusammenhang mit der Meerestemperatur und dem Zeitraum ihrer Existenz. Unser Dual Inlet System, ausgestattet mit MultiCarb, ist in der Lage, 13C and 18O Analysen von extrem kleinen Proben mit der höchsten Präzision durchzuführen, und ermöglicht die aufregend neue "clumped isotope" Analysenmethode.

» MultiCarb

Wasseranalyse aus Eisbohrkernen

Das Isotopenverhältnis des Niederschlags ist abhängig von der Temperatur der Ozeane, aus denen das Wasser verdunstet. Eisbohrkerne aus den arktischen und antarktischen Polarregionen haben die Variation der Isotope über Jahrtausende aufgezeichnet und ermöglichen es, die Temperatur zu dem Zeitpunkt zu rekonstruieren, als das Eis entstand. Verglichen mit anderen Techniken ist unser AquaPrep ist in der Lage, höchste 18O und 2H Analysen durchzuführen, was Unsicherheiten in Ihren Temperaturproxyberechnungen reduziert.

» AquaPrep

Treibhausgase

Treibhausgase in der Atmosphäre sind die Haupttreiber des Klimawandels. Um die Mechanismen des Klimawandels zu verstehen, ist die Entkopplung des anthropogenen Beitrags dieser Gase in die Atmosphäre von solchen, die das Ergebnis natürlicher Prozesse sind, entscheidend. Mit iso FLOW können die Isotopenverhältnisse der wichtigsten Treibhausgase CO2, N2O und CH4 in atmosphärischen Gasproben untersucht werden. Die Ergebnisse dieser Analysen können dabei helfen, Strategien zum Umgang mit dem Klimawandel zu entwickeln.

Publikationen zum Thema Klimawandel mit unseren Geräten

Unsere Kunden nutzen unsere Geräte für erstaunliche Forschungsprojekte zum Thema Klimawandel. Um Ihnen zu zeigen, wie unsere Kunden ihre Forschung durchführen und wie unsere IRMS-Geräte eingesetzt werden, haben wir eine Reihe von Fachpublikationen gesammelt, die unsere Produkte namentlich nennen. Die Informationen zu diesen Fachartikeln finden Sie unten. Durch Klicken auf den Link werden Sie zur Website des jeweiligen Zeitschriftenverlags weitergeleitet, wo Sie die Publikation herunterladen können.

Wenn Sie unsere Publikationsdatenbank durchsuchen möchten oder die Liste der Ergebnisse an sich selbst oder an Ihre Kollegen mailen möchten, dann werfen Sie einen Blick auf unsere gesamte Publikationsdatenbank.

115 Ergebnisse:

Nitrogen Isotopic Composition of Coal-Fired Power Plant NO
Environmental science & technology (2012)
J David Felix, Emily M Elliott, Stephanie L Shaw

Despite the potential use of δ15N as a tracer of NOx source contributions, prior documentation of δ15N of various NOx emission sources is exceedingly limited. This manuscript presents the first measurements of the nitrogen isotopic composition of NOx (δ15N- NOx) emitted from coal-fired power plants in the U.S. at typical operating conditions with and without the presence of selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR) technology. To accomplish this, a novel method for collection and isotopic analysis of coal-fired stack NOx emission samples was developed based on modifications of a historic U.S. EPA stack sampling method. At the power plants included in this study, large differences exist in the isotopic composition of NOx emitted with and without SCRs and SNCRs; further the isotopic composition of power plant NOx is higher than that of other measured NOx emission sources confirming its use as an environmental tracer. These findings indicate that gradual implementation of SCRs at power plants will result in an industry-wide increase in δ15N values of NOx and NOy oxidation products from this emission source.
Schlagworte: nitrogen , oxygen , clim , gashead

Impacts of environmental deterioration on the carbon isotope values of modern vegetation and gazelles in the southern Levant: Predicting the severity of the Younger Dryas
Palaeogeography, Palaeoclimatology, Palaeoecology (2012)
Gideon Hartman

This study uses the carbon isotope values (δ13C) to determine how environmental deterioration is expressed in the δ13C values of vegetation and gazelles in the southern Levant. The ultimate goal is to use these modern data to predict the climatic impact of the Younger Dryas (YD). Climatic deterioration associated with the YD has been cited as the trigger for the transition to agriculture in the southern Levant. However, the evidence for the local severity of this climatic event is equivocal. There is disagreement over whether Mediterranean forest was succeeded by arid adapted steppic plant communities in what has been termed the Natufian ‘core area’. The modern data show a moderately negative regression slope between aridity and the δ13C values of both modern C3 plants and gazelle horn keratin within the Mediterranean phytogeographic belt. This pattern is expressed in both seasonal and annual datasets. The incorporation of a C4 plant component into gazelle diets is evident in the arid Mediterranean region, and is more pronounced in the dry season. The latter is apparent even despite interference caused by gazelle foraging on cultivated land. Based on the present day data, it is predicted that the succession of Mediterranean forest by open steppic vegetation would cause a positive shift of >2‰ in the δ13C values of C3 plants and gazelles. The argument is based on the response of C3 vegetation to growth under increasing water stress conditions and the current distribution of C3 and C4 vegetation in relation to rainfall. This study presents a new tool with the potential to assess the climatic severity of the YD and its effect on Natufian foraging strategies.
Schlagworte: carbon , ecol , clim , elem

Oxygen isotope variability in conodonts : implications for reconstructing Palaeozoic palaeoclimates and palaeoceanography
Journal of the Geological Society (2012)
James R Wheeley, M Paul Smith, I A N Boomer, Natural History, Parks Road, Oxford Ox

Conodonts have the potential to elucidate the intricacies of Palaeozoic climates, especially if δ18O values of single apatitic tooth-like ‘elements’ can be used to map evolving sea surface temperatures and dif- ferentiate oceanic water masses. Their ecological distribution as pelagic and nektobenthic organisms, high- resolution biostratigraphy, and abundance in Cambrian–Triassic rocks qualifies them as potentially robust climate archives. Previous ion microprobe conodont δ18O studies have proceeded directly to palaeotempera- ture interpretation without appreciation of inter- and intra-element variability or post-mortem artefacts. Here, ion microprobe analyses of Ordovician and Silurian conodonts establishes that: intra-element crown tissue δ18O typically varies by ≤1‰ (53% of conodonts analysed), is normally ≤2‰ (92% of analyses), and rarely varies by 2–4‰; δ18O can vary across elements, suggesting a microstructural and/or diagenetic control; δ18O can vary between species representatives by c. 3‰; δ18O of pelagic and nektobenthic taxa can be offset by 2–3‰; elements processed with formic acid have highly variable δ18O; and thermal alteration does affect δ18O. Conodont ion microprobe δ18O values are comparable with those of bulk methods, but utilization of material with no consideration of geological context or processing history may introduce significant artefacts. A protocol for future conodont oxygen isotope ion microprobe studies is proposed
Schlagworte: oxygen , clim , gashead

Impact of the Middle Jurassic diversification of Watznaueria (coccolith-bearing algae) on the carbon cycle and ?? 13C of bulk marine carbonates
Global and Planetary Change (2012)
Baptiste Such??ras-Marx, Abel Guihou, Fabienne Giraud, Christophe L??cuyer, Pascal Allemand, Bernard Pittet, Emanuela Mattioli

During the Mid Mesozoic Revolution, thought to have started 200Ma ago (Late Triassic), the production of calcium carbonate in the ocean shifted from platform and epicontinental seas to the open ocean, concurrently with the diversification of coccolithophorids. In this regard, the radiation of the coccolith genus Watznaueria during the Middle Jurassic is thought to represent one of the most important steps of this diversification. Nevertheless, the timing of this diversification remains poorly constrained, and its possible impact on global carbon budgets remains unclear. In this study, we present new records of nannofossil fluxes and carbon stable isotope composition from sedimentary deposits of Lower Bajocian age from the Cabo Mondego (Portugal) reference section to further address the possible impact of this diversification on the Middle Jurassic global carbon cycle. Our results show that calcareous nannofossil fluxes increase markedly from the upper part of the Aalenian to the Early Bajocian, coinciding with a 0.75??? positive shift in carbon isotope compositions of bulk carbonate. Reconstructions of mass accumulation rates indicate that nannofossil fluxes increased by two orders of magnitude (from 10 9 to 10 11nannofossils/m 2/yr) during the corresponding time interval, mainly related to the rise of Watznaueria genus, whose relative abundance jumped from 2% to 20% of the total rock composition. The calculated amount of carbon derived from calcareous nannofossils deposited in the Early Bajocian seas was, however, 10 to 20 times lower than current levels. Mass balance calculations indicate that the increase of nannofossil flux throughout the studied interval was most likely not the main cause of the accompanying isotopic perturbation, suggesting a limited role of the Early Bajocian diversification on the global carbon cycle. Our results show that while the diversification of Watznaueria throughout the Bajocian caused a major increase in the flux of pelagic carbonate to the deep ocean, it was most likely quantitatively insufficient to have a large impact on the global biogeochemistry of the oceans. ?? 2012 Elsevier B.V..
Schlagworte: carbon , geol , ocea , clim , mulitcarb

Stable carbon and oxygen isotope compositions of invertebrate carbonate shells and the reconstruction of paleotemperatures and paleosalinities-A case study of the early Pleistocene of Rhodes, Greece
Palaeogeography, Palaeoclimatology, Palaeoecology (2012)
Christophe Lécuyer, Valérie Daux, Pierre Moissette, Jean Jacques Cornée, Frédéric Quillévéré, Efterpi Koskeridou, François Fourel, François Martineau, Bruno Reynard

The coastal sediments of Rhodes in the eastern Mediterranean have recorded transgression-regression cycles that took place during the early Pleistocene. The sedimentary deposits from the Kritika Member of the Rhodes Formation consist in conglomerates, sandstones, siltstones and clays deposited in brackish to shallow marine environments. Faunal associations are dominated by molluscs and reveal rapid ecological changes. Carbon and oxygen isotope ratios of aquatic skeletal carbonates show that these ecological changes were most likely driven by large salinity changes while water temperature remained rather constant at about 22.0 ± 1.5 °C. The tectonic activity of the island rather than glacio-eustatic variations of climatic origin is advocated to be responsible for the ecological and salinity changes and sea-level variations recorded in the sedimentary sequence. © 2012 Elsevier B.V.
Schlagworte: carbon , oxygen , geol , ocea , clim , mulitcarb

18O/16O ratio measurements of inorganic and organic materials by elemental analysis-pyrolysis-isotope ratio mass spectrometry continuous-flow techniques.
Rapid communications in mass spectrometry : RCM (2011)
François Fourel, François Martineau, Christophe Lécuyer, Hans-Joachim Kupka, Lutz Lange, Charles Ojeimi, Mike Seed

We have used a high-precision, easy, low-cost and rapid method of oxygen isotope analysis applied to various O-bearing matrices, organic and inorganic (sulfates, nitrates and phosphates), whose (18)O/(16)O ratios had already been measured. It was first successfully applied to (18)O analyses of natural and synthetic phosphate samples. The technique uses high-temperature elemental analysis-pyrolysis (EA-pyrolysis) interfaced in continuous-flow mode to an isotope ratio mass spectrometry (IRMS) system. Using the same pyrolysis method we have been able to generate a single calibration curve for all those samples showing pyrolysis efficiencies independent of the type of matrix pyrolysed. We have also investigated this matrix-dependent pyrolysis issue using a newly developed pyrolysis technique involving 'purge-and-trap' chromatography. As previously stated, silver phosphate being a very stable material, weakly hygroscopic and easily synthesized with predictable (18)O/(16)O values, could be considered as a good candidate to become a reference material for the determination of (18)O/(16)O ratios by EA-pyrolysis-IRMS.
Schlagworte: oxygen , geol , arch , clim , elem

Effects of diagenesis on paleoclimate reconstructions from modern and young fossil corals
Geochimica et Cosmochimica Acta (2011)
Hussein R. Sayani, Kim M. Cobb, Anne L. Cohen, W. Crawford Elliott, Intan S. Nurhati, Robert B. Dunbar, Kathryn a. Rose, Laura K. Zaunbrecher

The integrity of coral-based reconstructions of past climate variability depends on a comprehensive knowledge of the effects of post-depositional alteration on coral skeletal geochemistry. Here we combine millimeter-scale and micro-scale coral Sr/Ca data, scanning electron microscopy (SEM) images, and X-ray diffraction with previously published d18O records to investigate the effects of submarine and subaerial diagenesis on paleoclimate reconstructions in modern and young sub-fossil corals from the central tropical Pacific. In a 40-year-old modern coral, we find secondary aragonite is associated with rela- tively high coral d18O and Sr/Ca, equivalent to sea-surface temperature (SST) artifacts as large as ?3 and ?5 ?C, respectively. Secondary aragonite observed in a 350-year-old fossil coral is associated with relatively high d18O and Sr/Ca, resulting in apparent paleo-SST offsets of up to ?2 and ?4 ?C, respectively. Secondary Ion Mass Spectrometry (SIMS) analyses of sec- ondary aragonite yield Sr/Ca ratios ranging from 10.78 to 12.39 mmol/mol, significantly higher compared to 9.15 ± 0.37 mmol/mol measured in more pristine sections of the same fossil coral. Widespread dissolution and secondary cal- cite observed in a 750-year-old fossil coral is associated with relatively low d18O and Sr/Ca. SIMS Sr/Ca measurements of the secondary calcite (1.96–9.74 mmol/mol) are significantly lower and more variable than Sr/Ca values from more pristine por- tions of the same fossil coral (8.22 ± 0.13 mmol/mol). Our results indicate that while diagenesis has a much larger impact on Sr/Ca-based paleoclimate reconstructions than d18O-based reconstructions at our site, SIMS analyses of relatively pristine skeletal elements in an altered coral may provide robust estimates of Sr/Ca which can be used to derive paleo-SSTs
Schlagworte: oxygen , geol , clim , mulitcarb

Quantifying seasonal precipitation using high-resolution carbon isotope analyses in evergreen wood
Geochimica et Cosmochimica Acta (2011)
Brian a. Schubert, a. Hope Jahren

High-resolution natural abundance stable carbon isotope analyses across annual growth rings in evergreen trees reveal a cyclic increase and decrease in the measured carbon isotopic composition (??13C), but the causes of this pattern are poorly understood. We compiled new and published high-resolution ??13C data from across annual growth rings of 33 modern evergreen trees from 10 genera and 15 globally distributed sites to quantify the parameters that affect the observed ??13C pattern. Across a broad range of latitude, temperature, and precipitation regimes, we found that the average, measured seasonal change in ??13C (????13Cmeas, ???) within tree rings of evergreen species reflects changes in the carbon isotopic composition of atmospheric carbon dioxide (????13CCO2) and changes in seasonal precipitation (??P) according to the following equation: ????13Cmeas=????13CCO2-0.82(??P)+0.73; R2=0.96. Seasonal changes in temperature, pCO2, and light levels were not found to significantly affect ????13Cmeas. We propose that this relationship can be used to quantify seasonal patterns in paleoprecipitation from intra-ring profiles of ??13C measured from non-permineralized, fossil wood. ?? 2011 Elsevier Ltd.
Schlagworte: carbon , clim , elem

Foraminifer isotope study of the Pleistocene Labrador Sea, northwest North Atlantic (IODP Sites 1302/03 and 1305), with emphasis on paleoceanographical differences between its "inner" and "outer" basins
Marine Geology (2011)
Claude Hillaire-Marcel, Anne De Vernal, Jennifer McKay

Cores raised during IODP Expedition 303 off southern Greenland (Eirik Ridge site 1305) and off the Labrador Coast (Orphan Knoll site 1302/1303) were analyzed to establish an isotope stratigraphy, respectively for the "inner" and "outer" basins of the Labrador Sea (LS). These isotopic data also provide information on the Atlantic Meridional Overturning Circulation (AMOC), notably with regard to the intensity of the Western Boundary Under Current (WBUC), which is tightly controlled by the production of Denmark Strait Overflow Water (DSOW), and the production of Labrador Sea Water (LSW) in the inner basin through winter cooling and convection. The upper 184m of sediment at Eirik Ridge spans marine isotope stages (MIS) 32 to 1. At this site, two distinct regimes are observed: prior to MIS 20, the isotopic record resembles that of the open North Atlantic records of the interval, whereas a more site-specific pattern is observed afterwards. This later pattern was characterized by i) high DSOW production rates and strong WBUC during interglacial stages, as indicated by sedimentation rates, ii) large amplitude ??18O-shifts from glacial stages to interglacial stages (>2.5%) and iii) an overall range of ??18O-values significantly more positive than before. At Orphan Knoll, the 105m record spans approximately 800ka and provides direct information on linkages between the northeastern sector of the Laurentide Ice Sheet and the North Atlantic. At this site, a shift towards larger amplitude glacial/interglacial ranges of ??18O-values occurred after MIS 13, although isotopic records bear a typical North Atlantic signature, particularly during MIS 5, in contradiction to those of Eirik Ridge, where substages 5a to 5c are barely recognized. Closer examination of ??18O-records in planktic and benthic foraminifera demonstrates the presence of distinct deep-water masses in the inner vs. outer LS basins during MIS 11 and more particularly MIS 5e. Data confirm that the modern AMOC, with LSW formation, seems mostly exclusive to the present interglacial, and also suggest some specificity of each interglacial with respect to the production rate of DSOW and the AMOC, in general. ?? 2010 Elsevier B.V.
Schlagworte: carbon , oxygen , geol , ocea , clim , mulitcarb

Micropowder collecting technique for stable isotope analysis of carbonates
Rapid Communications in Mass Spectrometry (2011)
Saburo Sakai, Tsuyoshi Kodan

Micromilling is a conventional technique used in the analysis of the isotopic composition of geological materials, which improves the spatial resolution of sample collection for analysis. However, a problem still remains concerning the recovery ratio of the milled sample. We constructed a simple apparatus consisting of a vacuum pump, a sintered metal filter, electrically conductive rubber stopper and a stainless steel tube for transferring the milled powder into a reaction vial. In our preliminary experiments on carbonate powder, we achieved a rapid recovery of 5 to 100 µg of carbonate with a high recovery ratio (>90%). This technique shortens the sample preparation time, improves the recovery ratio, and homogenizes the sample quantity, which, in turn, improves the analytical reproducibility.
Schlagworte: carbon , oxygen , geol , ocea , clim , mulitcarb