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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:

Paleoenvironmental shifts and precipitation variations recorded in tropical maar lake sediments during the Holocene in Southern China
The Holocene (2014)
X. Yang, G. Wei, J. Yang, G. Jia, C. Huang, L. Xie, W. Huang, K. Argyrios

Tropical ocean–atmosphere system exerts powerful control on the precipitation variations around the Pacific Ocean area where interactions among monsoon system, Intertropical Convergence Zone (ITCZ) migration, and other tropical ocean circulations modulate the regional climate changes in centennial-scale. However, little high-resolution information is known about the paleoenvironment changes in this area during the Holocene. In this study, a composite sediment profile, approximately 16 m in length, recovered from Shuangchiling (SCL) maar lake in Hainan Island, northern margin of western tropical Pacific, was selected to investigate the lake-level fluctuations, net precipitation variations, and the influence of the ocean–atmosphere system. Stable isotope (δ13C, δ15N) analyses, total organic carbon (TOC), and total nitrogen (TN) concentration measurements, as well as grain-size estimations revealed a two-stage evolution scenario for the lake dating back to 9 cal. kyr BP. The first stage spans a period of time from ~9 to ~3 cal. kyr BP, once the lake was characterized by shallow or ephemeral conditions. The second stage occurred from 3 to 0.6 cal. kyr BP and was characterized by a deeper water environment with substantial lake-level changes. All climate proxies suggest that the ocean–atmosphere variabilities, such as El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) activities, had a dominant influence on the regional net precipitation (the difference between precipitation and evaporation) and lake-level fluctuations. A three-step change of clay percentage at ~3, ~2.2, and ~1.3 cal. kyr BP correlate well with the ENSO proxy records from the eastern tropical Pacific
Schlagworte: carbon , nitrogen , geol , clim , elem

Improving accuracy and precision of ice core δd(CH4) analyses using methane pre-pyrolysis and hydrogen post-pyrolysis trapping and subsequent chromatographic separation
Atmospheric Measurement Techniques (2014)
M. Bock, J. Schmitt, J. Beck, R. Schneider, H. Fischer

Firn and polar ice cores offer the only direct palaeoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bub- bles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD(CH4) or δ2H(CH4)) 0.5 to 1.5 kg of ice was hitherto used. Here we present a method to improve precision and reduce the sam- ple amount for δD(CH4) measurements in (ice core) air. Pre- concentrated methane is focused in front of a high tempera- ture oven (pre-pyrolysis trapping), and molecular hydrogen formed by pyrolysis is trapped afterwards (post-pyrolysis trapping), both on a carbon-PLOT capillary at −196 ◦C. Argon, oxygen, nitrogen, carbon monoxide, unpyrolysed methane and krypton are trapped together with H2 and must be separated using a second short, cooled chromatographic column to ensure accurate results. Pre- and post-pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be mea- sured with a precision better than 1‰. For polar ice samples from glacial periods, we estimate a precision of 2.3‰ for 350 g of ice (or roughly 30mL – at standard temperature and pressure (STP) – of air) with 350 ppb of methane. This cor- responds to recent tropospheric air samples (about 1900 ppb CH4) of about 6mL (STP) or about 500 pmol of pure CH4
Schlagworte: hydrogen , clim

Insights into interconnections between the shallow and deep systems from a natural CO2 reservoir near Springerville, Arizona
International Journal of Greenhouse Gas Control (2014)
Elizabeth Keating, Dennis Newell, David Dempsey, Rajesh Pawar

If carbon dioxide (CO2) sequestration into deep geologic reservoirs is to be accepted by the public and environmental regulators, the possibility of upward leakage into shallow groundwater should be acknowledged and those processes well-understood. Studies of natural CO2 reservoirs and their connection (or lack thereof) with the shallow subsurface is one way to explore these issues. A natural reservoir near Springerville, Arizona has leaked CO2 to the surface along a fault zone for thousands of years, creating large travertine deposits. In recent times, the CO2 leak rates have declined significantly yet the shallow aquifer is still highly enriched in CO2. In this study, using water level data and simulations we demonstrate that the fault zone likely provides hydrologic communication between the shallow aquifer and the deeper reservoir. It is reasonable to assume, therefore, that the source of the CO2 in wells completed within the fault zone is the deeper CO2 reservoir. We present water chemistry data to demonstrate the geochemical impact of this CO2 on shallow groundwater quality. Interestingly, arsenic concentrations are elevated, but other trace metals concentrations are not. Arsenic and chloride concentrations co-vary, suggesting perhaps an external source of both elements rather than an in situ release of As due to CO2 attack on shallow aquifer sediments. Observations at this site demonstrate that hydraulic communications between shallow and deep layers and upward CO2 migration does not preclude long-term viability of a substantial CO2 reservoir at depth. We present multi-phase flow simulations to illustrate possible mechanisms trapping the CO2 at depth. Collectively, these analyses show that some degree of upward CO2 leakage may not be necessarily incompatible with the overarching goals of sequestering CO2 and protecting shallow groundwater. © 2014.
Schlagworte: carbon , oxygen , geol , clim , gashead

Environmental conditions in the South Atlantic (Angola Basin) during the Early Cretaceous
Organic Geochemistry (2014)
B.D.a. Naafs, R.D. Pancost

The South Atlantic has experienced periods of intense anoxia and black shale deposition that form an important hydrocarbon source. Here we have investigated the depositional environment during the initial opening phase of the South Atlantic during the Early Cretaceous. The period is crucial as it is characterized by extensive source rock deposition and because it sets the stage for subsequent periods of anoxia within the northern sub-basin of the South Atlantic. Within an Aptian sequence of organic-rich sediments (up to 40% total organic carbon, TOC) from Deep Sea Drilling Project (DSDP) Site 364, we found a distinct biomarker distribution, including the presence of isorenieratane and an array of thiophenic (S-containing) compounds. Our results indicate that, during the time of deposition, corresponding to the initial phase of opening of the South Atlantic, most of the water column in the Angola Basin was hypersaline (>40‰) and euxinic, with euxinia episodically reaching the photic zone. The low relative abundance of marine biomarkers in the samples suggests that these extreme conditions were unfavourable for typical marine organisms. Stratigraphically up-section, the biomarker distribution changed as the TOC content gradually decreased (< 20 wt.%), isorenieratane and thiophenic compounds became less abundant and marine biomarkers became more abundant. We interpret the results to reflect a shift towards more open marine conditions, with less extensive euxinia/anoxia and normal marine salinity as the opening of the South Atlantic continued and the basin became less restricted. Our results demonstrate that the opening of the South Atlantic was the dominant control on the deposition of organic rich shales in the Angola Basin during the Aptian, highlighting the control of local basin geography on the depositional environment and formation of organic rich black shales during the Early Cretaceous.

Interrogating trees for isotopic archives of atmospheric sulphur deposition and comparison to speleothem records.
Environmental pollution (Barking, Essex : 1987) (2014)
P M Wynn, N J Loader, I J Fairchild

Palaeorecords which depict changes in sulphur dynamics form an invaluable resource for recording atmospheric pollution. Tree rings constitute an archive that are ubiquitously available and can be absolutely dated, providing the potential to explore local- to regional-scale trends in sulphur availability. Rapid isotopic analysis by a novel "on-line" method using elemental analyser isotope ratio mass spectrometry (EA-IRMS) is developed, achieving sample precision of <0.4‰ using sample sizes of 40 mg wood powder. Tree cores from NE Italy show trends in pollution, evidenced through increasing concentrations of sulphur towards the youngest growth, and inverse trends in sulphur isotopes differentiating modern growth with light sulphur isotopes (+0.7‰) from pre-industrial growth (+7.5‰) influenced by bedrock composition. Comparison with speleothem records from the same location demonstrate replication, albeit offset in isotopic value due to groundwater storage. Using EA-IRMS, tree ring archives form a valuable resource for understanding local- to regional-scale sulphur pollution dynamics.
Schlagworte: sulfur , geol , clim , elem

Multiproxy reconstruction for Kuroshio responses to northern hemispheric oceanic climate and the Asian Monsoon since Marine Isotope Stage 5.1 (∼88 ka)
Climate of the Past (2014)
X. Shi, Y. Wu, J. Zou, Y. Liu, S. Ge, M. Zhao, J. Liu, A. Zhu, X. Meng, Z. Yao, Y. Han

The Kuroshio, a western boundary current in the northwestern Pacific, plays a key role in regulating ocean and climate in East Asia. The evolution of the Kuroshio and its branches has been the focus of paleoceanographic studies. In this study, we applied a multiproxy (grain size, planktonic foraminiferal species, δ18O, alkenone sea surface temperature (SST) and salinity) reconstruction from sediment core CSH1, which is located at the main axis of the Tsushima Warm Current, a branch of the Kuroshio, in the northern Okinawa Trough (OT). This study, extended the paleoceanographic record of the Kuroshio to Marine Isotope Stage (MIS) 5.1 (∼88 ka) from the far northern site in the OT. Planktonic foraminiferal species identified from this core contain warm-water species related to the Kuroshio and cold-water species related to subarctic water mass. The relative abundances of the warm-water species are high during MIS 1 and MIS 5.1, while cold-water species are high during MIS 2. An organic biomarker proxy, alkenone SST measured from core CSH1 ranges between 21 and 25 °C, with higher values during interglacials (MIS 1, 3.3, 5.1) and interstadials and lower values during glacials and Heinrich (H)/stadial events. Sea surface salinity (SSS) and the depth of the thermocline (DOT), reconstructed based on foraminifera isotopes and faunas, indicate dominant Kuroshio responses to an abrupt climate change event recorded in Greenland ice cores and in stalagmites in East China since ∼88 ka. The CSH1 SSS appears to be mainly controlled by the local river runoff and the Kuroshio, while the DOT change seems to be closely related to the strength of the Kuroshio and the latitudinal shift of the subarctic frontal zone. Our records suggest that, during MIS 1 and MIS 5.1, while global sea level was high, the Kuroshio was dominant; while during MIS 2, MIS 3 and MIS 4, with a low sea level, stronger winter Asian Monsoon (AM) and a more southerly subarctic front played important roles in governing the hydrographic characteristics in the OT. Spectral analysis of our multiproxy hydrographic records shows a dominant precessional period at ∼24 ka. Our hydrographic records, such as SST, SSS and DOT, from a site near the modern Tsushima Warm Current show regional responses corresponding mainly to the global sea level, the Kuroshio, AM and subarctic front, factors which are consistently invoked in the interpretations of other regional records from the OT.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Carbon cycle and sea-water palaeotemperature evolution at the Middle-Late Jurassic transition, eastern Paris Basin (France)
Marine and Petroleum Geology (2014)
Pierre Pellenard, Romain Tramoy, Emmanuelle Puc??at, Emilia Huret, Mathieu Martinez, Ludovic Bruneau, Jacques Thierry

A very high-resolution carbon and oxygen stable isotope analysis (bulk-carbonate) of a biostratigraphically well-constrained Callovian-Oxfordian series is provided here for the first time. The homogeneity of the clayey series and the weak diagenetic alteration allow the isotopic signal variations to be considered as primary in origin. A prominent and brief negative excursion in the ??13C curve (-2???), occurring at the start of the Middle Callovian (Jason Zone - Obductum Subzone) and correlated regionally, suggests a possible methane release. The increasing ??13C values thereafter up to the Early Oxfordian, concomitant with a warming episode, highlight the burial of carbon in organic-rich layers which, in return, may have triggered a decrease in atmospheric pCO2. At higher frequencies, observed fluctuations of the ??13C and ??18O values are orbitally driven (405-kyr and 100-kyr eccentricity cycles) and may correspond to the salinity and temperature variability recorded in sea water. The ??18O isotopic measurements from well-preserved diagenetically screened belemnites and bivalves along the series, compared to available data from Tethyan domains, agree with the scenario of a global cooling at the Middle-Late Jurassic transition. The well-dated ??18O isotopic curve suggests that the onset of this cooling event occurred at the end of the Coronatum Zone (Middle Callovian). ?? 2013 Elsevier Ltd.
Schlagworte: carbon , oxygen , geol , clim , mulitcarb

Links between southwestern tropical Indian Ocean SST and precipitation over southeastern Africa over the last 17 kyr
Palaeogeography, Palaeoclimatology, Palaeoecology (2014)
Syee Weldeab, David W. Lea, Hedi Oberha??nsli, Ralph R. Schneider

Time series of Mg/Ca, Ba/Ca, and ??18O analyzed in tests of surface-dwelling planktonic foraminifer Globigerinoides ruber from two marine sediment cores recovered in the Mozambique Channel off the Zambezi River, southwestern tropical Indian Ocean, reveal climate variability over the last 17kyr. Analysis of samples collected from the water column of the Mozambique Channel validates that Mg/Ca in G. ruber reflects calcification temperatures at 0-30m water depth and that the surface water of the southwestern Indian Ocean is very sensitive to dissolved Ba input from adjacent rivers. Foraminiferal Ba/Ca and Mg/Ca time series are used to reconstruct hydrological and thermal changes over southeastern African and southwestern tropical oceans. The Mg/Ca-based sea surface temperature (SST) estimates indicate that the thermal evolution of the tropical southwestern Indian Ocean followed, within age model uncertainties, climate changes over Antarctica. The trend of the SST record is marked by a gradual warming from 24.7??0.6??C at 17.0??0.2kyr BP to 26.4??0.3??C at 10-11kyr BP interrupted by two prominent coolings of ~1.5??0.2??C and ~1??C centered at 15??0.1kyr BP and 13.4??0.2kyr BP, respectively. Declining SSTs in the early Holocene reach their minimum (25??C) at 8.7??0.2kyr BP and give way to stable thermal conditions over the Middle and Late Holocene. The Ba/Ca record indicates that the Zambezi basin experienced relatively wet conditions during the early phase of the last deglaciation, B??lling-Aller??d, and the early Holocene. These wet phases coincide with an increase of SST in the Mozambique Channel. In contrast, relatively dry conditions throughout the middle and late Holocene epoch are accompanied by relatively cold Mozambique Channel surface water. These shifts likely reflect a response to meridional shifts of the austral westerlies and subtropical front. These hypothesized shifts would have modulated the advection of cold Southern Ocean water into the Mozambique Channel. Changes in SST in the Mozambique Channel, and possible resultant changes in the zonal gradient in the tropical Indian Ocean, in turn, had a strong impact on the precipitation over southeastern Africa.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Extreme warming of tropical waters during the Paleocene-Eocene thermal maximum
Geology (2014)
T. Aze, P. N. Pearson, A. J. Dickson, M. P S Badger, P. R. Bown, R. D. Pancost, S. J. Gibbs, B. T. Huber, M. J. Leng, A. L. Coe, A. S. Cohen, G. L. Foster

The Paleocene-Eocene Thermal Maximum (PETM), ca. 56 Ma, was a major global environmental perturbation attributed to a rapid rise in the concentration of greenhouse gases in the atmosphere. Geochemical records of tropical sea-surface temperatures (SSTs) from the PETM are rare and are typically affected by post-depositional diagenesis. To circumvent this issue, we have analyzed oxygen isotope ratios ({delta}18O) of single specimens of exceptionally well-preserved planktonic foraminifera from the PETM in Tanzania ([~]19{degrees}S paleolatitude), which yield extremely low {delta}18O, down to <-5{per thousand}. After accounting for changes in seawater chemistry and pH, we estimate from the foraminifer {delta}18O that tropical SSTs rose by >3 {degrees}C during the PETM and may have exceeded 40 {degrees}C. Calcareous plankton are absent from a large part of the Tanzania PETM record; extreme environmental change may have temporarily caused foraminiferal exclusion.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Methane in underground air in Gibraltar karst
Earth and Planetary Science Letters (2013)
D.P. Mattey, R. Fisher, T.C. Atkinson, J.-P. Latin, R. Durrell, M. Ainsworth, D. Lowry, I.J. Fairchild

Little is known about the abundance and geochemical behaviour of gaseous methane in the unsaturated zone of karst terrains. The concentrations and δ13C of methane in background atmosphere, soil air and cave air collected at monthly intervals over a 4 yr period are reported for St. Michaels Cave, Gibraltar, where the regional climate, surface and cave processes are well documented. Methane concentrations measured in Gibraltar soil are lower than the local background atmosphere average of 1868 ppb and fall to <500 ppb. The abundance–δ13C relationships in soil air methane lack strong seasonality and suggest mixing between atmosphere and a 12C depleted residue after methanotrophic oxidation. Methane abundances in cave air are also lower than the local background atmosphere average but show strong seasonality that is related to ventilation-controlled annual cycles shown by CO2. Cave air methane abundances are lowest in the CO2-rich air that outflows from cave entrances during the winter and show strong inverse relationship between CH4 abundance and δ13C which is diagnostic of methanotrophy within the cave and unsaturated zone. Anomalies in the soil and cave air seasonal patterns characterised by transient elevated CH4 mixing ratios with δ13C values lower than −47‰ suggests intermittent biogenic input. Dynamically ventilated Gibraltar caves may act as a net sink for atmospheric methane