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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

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115 Ergebnisse:

Lack of equivalence in the elemental and stable isotope chemistry within the sagittal otolith pair of the summer flounder, Paralichthys dentatus
(2014)
Antranik Kajajian, Jason J Schaffler, Cynthia M Jones

In fish that are not bilaterally symmetrical, the left and right sagittae are often not symmetrical, exhibiting divergent growth patterns and mass, and may have differences in chemical composition. We investigated this in the asymmetrical summer flounder Paralichthys dentatus, collected from different nursery habitats along the US east coast. Significant differences were detected in otolith mass, d13C, d18O, Li:Ca, Mg:Ca, and Sr:Ca, and overall chemical signatures. These results refute the hypothesis of left– right equivalence that is prevalent for bilaterally symmetrical fishes. We tested whether a specific side was better suited for classification. The best models differed between sagittae and resulted in different classification accuracies. The left otolith produced better classification accuracies. Simulated samples of randomized sets of left or right otoliths produced mean accuracies intermediate to classification and were often highly variable. We recommend that future otolith chemistry studies involving bilaterally asymmetrical species test the hypothesis of equivalence within the sagittae before randomly choosing an otolith for chemical analyses
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Paleoceanographic changes of surface and deep water based on oxygen and carbon isotope records during the last 130kyr identified in MD179 cores, off Joetsu, Japan Sea
Journal of Asian Earth Sciences (2014)
Saeko Ishihama, Takeshi Oi, Shiro Hasegawa, Ryo Matsumoto

We reconstructed the paleoenvironmental history of surface and deep water over the last 130. kyr from oxygen and carbon isotope ratios of planktonic and benthic foraminifera in two cores (MD179-3312 and MD179-3304) from the Joetsu Basin, eastern margin of the Japan Sea. Our data showed that paleoceanographic changes such as influx of surface currents and vertical circulation were associated with global glacial-interglacial sea level change. Surface water conditions were influenced by the influx of Tsushima Current, East China Sea coastal or off-shore waters through the Tsushima Strait during interglacial or interstadial stages, and strongly affected by freshwater input during the glacial maximum. During interglacial maximums such as Marine Isotope Stages 1 and 5e, development of well-oxygenated bottom water was indicated. A density-stratified ocean with weak ventilation was inferred from the isotopic records of benthic foraminifera during the Last Glacial Maximum. Local negative excursions in carbon isotopes during deglacial or interglacial periods may suggest the dissolution of gas hydrates or methane seep activities. ?? 2014 Elsevier Ltd.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Rapid environmental change during dynastic transitions in Yunnan Province, China
Quaternary Science Reviews (2014)
Aubrey L. Hillman, JunQing Yu, Mark B. Abbott, Colin A. Cooke, Daniel J. Bain, Byron A. Steinman

Pollution and eutrophication of Chinese lakes are widely perceived to be 20th century phenomena. However, China has a long history of deforestation, agriculture, mineral resource extraction, and other anthropogenic activities that impact the environment. Here, we present a sediment record from Xing Yun Lake in the Yunnan Province of China that reveals significant alterations to the lake, its ecosystem, and its watershed beginning as early as 500 AD. A comprehensive suite of biogeochemical and isotopic proxies reveal several rapid transitions related to changes in agriculture and lake-level management that coincides with cultural and dynastic transitions. The deterioration of contemporary environmental conditions at Xing Yun arises from a long history of anthropogenic manipulation, eutrophication, and pollution of the lake and its watershed. This study highlights the importance of using historical records of industrial and agricultural activities, including landscape modification, in conjunction with records of climate change, to place present day environmental concerns into a long-term context. © 2014 Elsevier Ltd.
Schlagworte: carbon , arch , poll , clim , mulitcarb

Isotopic composition of passively collected nitrogen dioxide emissions: Vehicle, soil and livestock source signatures
Atmospheric Environment (2014)
J. David Felix, Emily M. Elliott

Quantifying contributions of local and regional NOx emission sources is an important initial step towards accurately assessing improvements in NOx emission reduction efforts. Current global NOx inventories report large uncertainties in contributions of some NOx sources, especially diffuse sources (e.g. lightning and soil NOx). Examining the isotopic composition of NOx and its oxidation products (NOy) is one approach to further constrain contributions from these sources. While natural and anthropogenically-derived NOx emissions are reported to have relatively distinct δ15N values that could aid NOx source apportionment studies, existing δ15N–NOx source data is limited and variable collection approaches have been employed. To build on existing δ15N–NOx source data, inexpensive and easily deployable passive samplers were used to collect nitrogen dioxide (NO2) emissions and its oxidation product, nitric acid (HNO3), from multiple emission sources including livestock waste, fertilized soils, and vehicles. The resulting isotope data provides evidence that passive samplers can be used across a range of environmental conditions with widely varying NO2 concentrations and NO2 isotopic compositions. Using this approach, we report the first δ15N and δ18O–NO2 of livestock waste emissions, as well as the first measurements of δ18O–NO2 from biogenic soil and vehicle emissions. We observe the highest δ15N–NO2 values to date of vehicle emissions and investigate potential fractionations associated with oxidation and equilibrium processes. The large differences reported here between δ15N–NO2 values from fossil fuel-based sources and microbially-produced sources allows for identification and possible quantification of source contributions to ambient NOx concentrations.
Schlagworte: nitrogen , oxygen , clim , gashead

Examining the transport of ammonia emissions across landscapes using nitrogen isotope ratios
Atmospheric Environment (2014)
J. David Felix, Emily M. Elliott, Timothy Gish, Ronaldo Maghirang, Leah Cambal, Jane Clougherty

The proportion of reactive nitrogen in wet deposition attributable to ammonium (NH4+) has increased over the last three decades in the U.S. due to steadily increasing NH3 emissions and concomitant reductions in NOx emissions. The importance of examining NH3 emission sources and transport is amplified as the fraction of NH3 contributing to reactive nitrogen budget increases. Presented here is a study illustrating how the nitrogen stable isotopic composition of NH3 (δ15N–NH3) can be used to characterize the transport of NH3 emissions at the landscape-scale. To accomplish this, ambient NH3 was sampled across varying land use types (e.g. conventionally managed cornfield, tallgrass prairie, concentrated animal feeding operation (CAFO), dairy operation, urban setting) and analyzed for δ15N–NH3 values. Ambient δ15N–NH3 values at a conventionally managed cornfield were used in an isotope mixing model to make first order approximations of NH3 source contributions to ambient air over the cornfield. Results suggest that while volatilized fertilizer is a primary contributor to ambient NH3 after fertilizer application, during periods of low or no fertilization, vehicle NH3 emissions can be a substantial contributor to ambient NH3 over cornfields that are adjacent to roadways. These source approximations can aid in evaluating NH3 emission abatement techniques to local landscapes. Modeled NH3 deposition flux at a CAFO was found to contribute a considerable amount of nitrogen to the landscape and δ15N–NH3 values were used to trace the livestock source contributing to this flux. Ambient NH3 concentrations and δ15N–NH3 values were measured across an urban region and δ15N–NH3 values indicated primarily fossil fuel-based emissions and large spatial variations in NH3 concentrations.
Schlagworte: nitrogen , clim , gashead

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 (δ18O) of single specimens of exceptionally well-preserved planktonic foraminifera from the PETM in Tanzania (∼19°S paleolatitude), which yield extremely low δ18O, down to <–5‰. After accounting for changes in seawater chemistry and pH, we estimate from the foraminifer δ18O that tropical SSTs rose by >3 °C during the PETM and may have exceeded 40 °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

Orbital-scale benthic foraminiferal oxygen isotope stratigraphy at the northern Bering Sea Slope Site U1343 (IODP Expedition 323) and its Pleistocene paleoceanographic significance
Deep-Sea Research Part II: Topical Studies in Oceanography (2014)
H. Asahi, S. Kender, M. Ikehara, T. Sakamoto, K. Takahashi, A. C. Ravelo, C. A. Alvarez Zarikian, B. K. Khim, M. J. Leng

A continuous composite oxygen isotope (??18O) stratigraphy from benthic foraminifera in the Bering Sea was reconstructed in order to provide insight into understanding sea-ice evolution in response to Northern Hemisphere Glaciation. Oxygen isotope records from multiple species of benthic foraminifera at Integrated Ocean Drilling Program (IODP) Expedition 323 Site U1343 (54??33.4'N, 176??49.0'E, water depth 1950 m) yield a highly refined orbital-scale age model spanning the last 1.2 Ma, and a refined age model between 1.2 and 2.4 Ma. An inter-species calibration was used to define species offsets and to successfully obtain a continuous composite benthic ??18O record, correlated with the global composite benthic ??18O stack curve LR04 to construct an orbital-scale age model. The consistency of the benthic ??18O stratigraphy with biostratigraphy and magnetostratigraphy confirms the reliability of both methods for constraining age. The time difference between cyclic changes in sedimentary physical properties and glacial-interglacial cycles since 0.8 Ma is notable, and suggests that physical properties alone cannot be used to construct an orbital-scale age model. Amplitude changes in physical properties and a significant drop in the linear sedimentation rate during glacials after 0.9 Ma indicate that the glacial sea-ice edge extended beyond the Bering Sea Slope (Site U1343) at this time. ?? 2014 Elsevier Ltd. All rights reserved.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Isotopic and anatomical evidence of an herbivorous diet in the Early Tertiary giant bird Gastornis. Implications for the structure of Paleocene terrestrial ecosystems.
Die Naturwissenschaften (2014)
D. Angst, C. Lécuyer, R. Amiot, E. Buffetaut, F. Fourel, F. Martineau, S. Legendre, A. Abourachid, A. Herrel

The mode of life of the early Tertiary giant bird Gastornis has long been a matter of controversy. Although it has often been reconstructed as an apex predator feeding on small mammals, according to other interpretations, it was in fact a large herbivore. To determine the diet of this bird, we analyze here the carbon isotope composition of the bone apatite from Gastornis and contemporaneous herbivorous mammals. Based on (13)C-enrichment measured between carbonate and diet of carnivorous and herbivorous modern birds, the carbonate δ(13)C values of Gastornis bone remains, recovered from four Paleocene and Eocene French localities, indicate that this bird fed on plants. This is confirmed by a morphofunctional study showing that the reconstructed jaw musculature of Gastornis was similar to that of living herbivorous birds and unlike that of carnivorous forms. The herbivorous Gastornis was the largest terrestrial tetrapod in the Paleocene biota of Europe, unlike the situation in North America and Asia, where Gastornis is first recorded in the early Eocene, and the largest Paleocene animals were herbivorous mammals. The structure of the Paleocene terrestrial ecosystems of Europe may have been similar to that of some large islands, notably Madagascar, prior to the arrival of humans.
Schlagworte: oxygen , arch , clim , elem

Effect of a controlled sub-seabed release of CO2 on the biogeochemistry of shallow marine sediments, their pore waters, and the overlying water column
International Journal of Greenhouse Gas Control (2014)
Anna Lichtschlag, Rachael H. James, Henrik Stahl, Doug Connelly

The potential for leakage of CO2 from a storage reservoir into the overlying marine sediments and into the water column and the impacts on benthic ecosystems are major challenges associated with carbon capture and storage (CCS) in subseafloor reservoirs. We have conducted a field-scale controlled CO2 release experiment in shallow, unconsolidated marine sediments, and documented the changes to the chemical composition of the sediments, their pore waters and overlying water column before, during and up to 1 year after the 37-day long CO2 release. Increased levels of dissolved inorganic carbon (DIC) were detected in the pore waters close to the sediment-seawater interface in sediments sampled closest to the subsurface injection point within 5 weeks of the start of the CO2 release. Highest DIC concentrations (28.8 mmol L−1, compared to background levels of 2.4 mmol L−1) were observed 6 days after the injection had stopped. The high DIC pore waters have high total alkalinity, and low ı13CDIC values (−20‰, compared to a background value of −2‰), due to the dissolution of the injected CO2 (ı13C = −26.6‰). The high DIC pore waters have enhanced concentrations of metals (including Ca, Fe, Mn) and dissolved silicon, relative to non-DIC enriched pore waters, indicating that dissolution of injected CO2 promotes dissolution of carbonate and silicate minerals. However, in this experiment, the pore water metal concentrations did not exceed levels considered to be harmful to the environment. The spatial extent of the impact of the injected CO2 in the sediments and pore waters was restricted to an area within 25 m of the injection point, and no impact was observed in the overlying water column. Concentrations of all pore water constituents returned to background values within 18 days after the CO2 injection was stopped
Schlagworte: carbon , geol , ocea , clim , gashead

Tracing CO2 leakage into groundwater using carbon and strontium isotopes during a controlled CO2 release field test
International Journal of Greenhouse Gas Control (2014)
D.L. Newell, T.E. Larson, G. Perkins, J.D. Pugh, B.W. Stewart, R.C. Capo, R.C. Trautz

During a carbon sequestration field study to simulate the impact of CO2 migration on shallow groundwa- ter chemistry, the isotope composition of dissolved inorganic carbon (ı13CDIC) and dissolved strontium (87Sr/86Sr) were evaluated as tracers. Dissolved CO2 in groundwater was introduced using a closed-loop dipole-style well field situated in a shallow sand-dominated aquifer. Baseline ı13CDIC values, oxygen and hydrogen isotope ratios, and 87Sr/86Sr values of groundwater were established in four monitoring wells (MW-1 to 4) and one up-gradient background well (BG-1) prior to the introduction of dissolved CO2. Base- line groundwater ı13CDIC-PDB, oxygen (ı18OSMOW) and hydrogen (ıDSMOW) stable isotope values averaged −17, −4.1 and −19.5‰, respectively. Groundwater 87Sr/86Sr baseline values averaged 0.70840 at MW-3 and 0.70818 at MW-2. Arrival of the dissolved CO2 plume at the monitoring wells is modeled using a 1-D analytical equation, which yields breakthrough curves with flow velocities that are consistent with prior numerical modeling estimates. The ı13CDIC-PDB rose to an average steady-state value of 0.16 ± 0.3‰ during the test; ı18O and ıD of water did not change from their baseline values. 87Sr/86Sr dropped sharply by 0.00022 at MW-3 and 0.00005 at MW-2 in the first two weeks after plume arrival at the wells, and then slowly increased toward baseline values, correlating with the behavior of dissolved Na, K, Ca, Sr and Si. Carbonate dissolution and desorption from organic matter and Fe-bearing phases at the low-pH plume front is the likely mechanism producing this behavior. The ı13CDIC and the 87Sr/86Sr of dissolved strontium served as excellent tracers of plume movement during this experiment
Schlagworte: carbon , hydrogen , oxygen , geol , clim , gashead