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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:

Late Archean biospheric oxygenation and atmospheric evolution.
Science (2007)
Alan J Kaufman, David T Johnston, James Farquhar, Andrew L Masterson, Timothy W Lyons, Steve Bates, Ariel D Anbar, Gail L Arnold, Jessica Garvin, Roger Buick

High-resolution geochemical analyses of organic-rich shale and carbonate through the 2500 million-year-old Mount McRae Shale in the Hamersley Basin of northwestern Australia record changes in both the oxidation state of the surface ocean and the atmospheric composition. The Mount McRae record of sulfur isotopes captures the widespread and possibly permanent activation of the oxidative sulfur cycle for perhaps the first time in Earth's history. The correlation of the time-series sulfur isotope signals in northwestern Australia with equivalent strata from South Africa suggests that changes in the exogenic sulfur cycle recorded in marine sediments were global in scope and were linked to atmospheric evolution. The data suggest that oxygenation of the surface ocean preceded pervasive and persistent atmospheric oxygenation by 50 million years or more.
Schlagworte: sulfur , geol , clim , elem

High-precision, automated stable isotope analysis of atmospheric methane and carbon dioxide using continuous-flow isotope-ratio mass spectrometry.
Rapid communications in mass spectrometry : RCM (2006)
Rebecca Fisher, David Lowry, Owen Wilkin, Srimathy Sriskantharajah, Euan G Nisbet

Small-scale developments have been made to an off-the-shelf continuous-flow gas chromatography/isotope-ratio mass spectrometry (CF-GC/IRMS) system to allow high-precision isotopic analysis of methane (CH(4)) and carbon dioxide (CO(2)) at ambient concentrations. The repeatability (1sigma) obtainable with this system is 0.05 per thousand for delta(13)C of CH(4), 0.03 per thousand for delta(13)C of CO(2), and 0.05 per thousand for delta(18)O of CO(2) for ten consecutive analyses of a standard tank. An automated inlet system, which allows diurnal studies of CO(2) and CH(4) isotopes, is also described. The improved precision for CH(4) analysis was achieved with the use of a palladium powder on quartz wool catalyst in the combustion furnace, which increased the efficiency of oxidation of CH(4) to CO(2). The automated inlet further improved the precision for both CH(4) and CO(2) analysis by keeping the routine constant. The method described provides a fast turn-around in samples, with accurate, reproducible results, and would allow a long-term continuous record of CH(4) or CO(2) isotopes at a site to be made, providing information about changing sources of the gases both seasonally and interannually.
Schlagworte: carbon , clim , gashead

Long-chain alkenone unsaturation index as sea surface temperature proxy in southwest Bay of Bengal
Current Science (2006)
Nittala S Sarma, Sk G Pasha, M Sri Rama Krishna, P V Shirodkar, M G Yadava, K Mohan Rao

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 , ocea , clim , mulitcarb

Distinguishing Nitrous Oxide Production from Nitrification and Denitrification on the Basis of Isotopomer Abundances
(2006)
R L Sutka, N E Ostrom, P H Ostrom, J A Breznak, H Gandhi, A J Pitt, F Li

The intramolecular distribution of nitrogen isotopes in N2O is an emerging tool for defining the relative importance of microbial sources of this greenhouse gas. The application of intramolecular isotopic distributions to evaluate the origins of N2O, however, requires a foundation in laboratory experiments in which individual production pathways can be isolated. Here we evaluate the site preferences of N2O produced during hydroxylamine oxidation by ammonia oxidizers and by a methanotroph, ammonia oxidation by a nitrifier, nitrite reduction during nitrifier denitrification, and nitrate and nitrite reduction by denitrifiers. The site preferences produced during hydroxylamine oxidation were 33.5 +/- 1.2 per thousand, 32.5 +/- 0.6 per thousand, and 35.6 +/- 1.4 per thousand for Nitrosomonas europaea, Nitrosospira multiformis, and Methylosinus trichosporium, respectively, indicating similar site preferences for methane and ammonia oxidizers. The site preference of N2O from ammonia oxidation by N. europaea (31.4 +/- 4.2 per thousand) was similar to that produced during hydroxylamine oxidation (33.5 +/- 1.2 per thousand) and distinct from that produced during nitrifier denitrification by N. multiformis (0.1 +/- 1.7 per thousand), indicating that isotopomers differentiate between nitrification and nitrifier denitrification. The site preferences of N2O produced during nitrite reduction by the denitrifiers Pseudomonas chlororaphis and Pseudomonas aureofaciens (-0.6 +/- 1.9 per thousand and -0.5 +/- 1.9 per thousand, respectively) were similar to those during nitrate reduction (-0.5 +/- 1.9 per thousand and -0.5 +/- 0.6 per thousand, respectively), indicating no influence of either substrate on site preference. Site preferences of approximately 33 per thousand and approximately 0 per thousand are characteristic of nitrification and denitrification, respectively, and provide a basis to quantitatively apportion N2O.

Nitrogen isotopomer site preference of N2O produced by Nitrosomonas europaea and Methylococcus capsulatus Bath.
Rapid communications in mass spectrometry : RCM (2003)
R L Sutka, N E Ostrom, P H Ostrom, H Gandhi, J a Breznak

The relative importance of individual microbial pathways in nitrous oxide (N(2)O) production is not well known. The intramolecular distribution of (15)N in N(2)O provides a basis for distinguishing biological pathways. Concentrated cell suspensions of Methylococcus capsulatus Bath and Nitrosomonas europaea were used to investigate the site preference of N(2)O by microbial processes during nitrification. The average site preference of N(2)O formed during hydroxylamine oxidation by M. capsulatus Bath (5.5 +/- 3.5 per thousand) and N. europaea (-2.3 +/- 1.9 per thousand) and nitrite reduction by N. europaea (-8.3 +/- 3.6 per thousand) differed significantly (ANOVA, f((2,35)) = 247.9, p = 0). These results demonstrate that the mechanisms for hydroxylamine oxidation are distinct in M. capsulatus Bath and N. europaea. The average delta(18)O-N(2)O values of N(2)O formed during hydroxylamine oxidation for M. capsulatus Bath (53.1 +/- 2.9 per thousand) and N. europaea (-23.4 +/- 7.2 per thousand) and nitrite reduction by N. europaea (4.6 +/- 1.4 per thousand) were significantly different (ANOVA, f((2,35)) = 279.98, p = 0). Although the nitrogen isotope value of the substrate, hydroxylamine, was similar in both cultures, the observed fractionation (delta(15)N) associated with N(2)O production via hydroxylamine oxidation by M. capsulatus Bath and N. europaea (-2.3 and 26.0 per thousand, respectively) provided evidence that differences in isotopic fractionation were associated with these two organisms. The site preferences in this study are the first measured values for isolated microbial processes. The differences in site preference are significant and indicate that isotopomers provide a basis for apportioning biological processes producing N(2)O.