3,734 research outputs found
Colombia: Doctoral Excursion, Earth Sciences Department ETH Zurich, August 21-September 5, 2018
No full textHandbook for particpants in the 2018 ETH Zurich Earth Sciences Department's field trip for doctoral students to Columbia
TEX86 SST analysis from ODP Site 133-820 in the Coral Sea between MIS 22-MIS 1
No full textIn this data set, we present a new biomarker, sea surface temperature (SST) reconstructions from ODP site 820. ODP site 820 is from the Coral Sea, located next to the Great Barrier Reef. In this data set, we use TEX86 to reconstruct SSTs from MIS 22- MIS 1. In the data we include both the raw GDGT data, the TEX86, and indices. Also included are replicates for all the biomarker data. Finally, we include information on SST values that were later rejected because of issues with the indices. We also updated the age model using revised biostratigraphic data and tuning. In doing so we show that SSTs increased around MIS 17 at the same time as records show the development of the Great Barrier Reef. The data is published in the following article: Petrick, Benjamin, Lars Reuning, Alexandra Auderset, Miriam Pfeiffer, Gerald Auer, and Lorenz Schwark. 2024. "High Sea Surface Temperatures Were a Prerequisite for the Development and Expansion of the Great Barrier Reef." Science Advances 10 (49): eado2058. doi:10.1126/sciadv.ado205
Simultaneous extraction and chromatographic separation of n-alkanes and alkenones from glycerol dialkyl glycerol tetraethers via selective Accelerated Solvent Extraction
No full textA method is described for simultaneous extraction and chromatographic separation of saturated hydrocarbons (n-alkanes) and unsaturated long-chain ketones (alkenones) from glycerol dialkyl glycerol tetraethers (GDGTs) using selective accelerated solvent extraction (ASE). We show that the method can be used to successfully separate n-alkanes and alkenones from GDGTs in marine sediment samples and n-alkanes from GDGTs in lake sediments and soil samples. A comparison of our method with analysis of samples purified using classical silica column chromatography demonstrates that the new method does not affect the alkenone unsaturation index (), the TetraEther indeX (TEX86), the Methane Index (MI), the Ring Index (RI), the branched-GDGT-based paleotemperature and soil pH indices, the Branched and Isoprenoid Tetraether (BIT) index, the n-alkane average chain length (ACL) or the carbon preference index (CPI). The new procedure results in higher sample recoveries for n-alkanes and more precise estimates at low concentrations, and contributes to reduced analyst laboratory time
Preface: special issue on probing the open ocean with the research sailing yacht <i>Eugen Seibold</i> for climate geochemistry
No full textThe 72-foot sailing yacht Eugen Seibold is a new research platform for contamination-free sampling of the water column and atmosphere for biological, chemical, and physical properties, and the exchange processes between the two realms. Ultimate goal of the project is a better understanding of the modern and past ocean and climate. Operations started in 2019 in the Northeast Atlantic, and will focus on the Tropical Eastern Pacific from 2023 until 2025. Laboratories for air and seawater analyses are equipped with down-sized and automated state-of-the-art technology for a comprehensive description of the marine carbon system including CO2 concentration in the air and sea surface, pH, macro-, and micro-nutrient concentration (e.g., Fe, Cd), trace metals, and calcareous plankton. Air samples are obtained from ca. 13 m above sea surface and analyzed for particles (incl. black carbon and aerosols) and greenhouse gases. Plankton nets and seawater probes are deployed over the custom-made A-frame at the stern of the boat. Near Real-Time Transfer of underway data via satellite connection allows dynamic expedition planning to maximize gain of information. Data and samples are analyzed in collaboration with the international expert research community. Quality controlled data are published for open access. The entire suite of data facilitates refined proxy calibration of paleoceanographic and paleoclimate archives at high temporal and spatial resolution in relation to seawater and atmospheric parameters
Gulf Stream intensification after the early Pliocene shoaling of the Central American Seaway
No full textThe shoaling of the Central American Seaway (CAS) around 4.6 Ma (million years ago) is thought to have enhanced the Gulf Stream, strengthening the Atlantic Meridional Overturning Circulation and potentially influencing the evolution of Pliocene climate. Paleoclimate records indicate a buildup of heat and salt in the Caribbean and changes in the formation of North Atlantic Deep Water (NADW) associated with a major step in the shoaling of the CAS at 4.6 Ma. However, so far, direct evidence supporting an intensification of the Gulf Stream is scarce. Here we report new North Atlantic early Pliocene (5.3–3.9 Ma) records of sea surface temperature (SST) reconstructed using the UK37’ and TEX86 paleotemperature indices. Based on new sediment trap measurements near the study site, we suggest that in this particular region, the two paleothermometers record SST during different seasons: spring for UK37’ and summer for TEX86. At 4.6 and 4.2 Ma, our results indicate substantial increases in SST and salinity during summer but not spring, pointing to a significant intensification of the Gulf Stream and its extension, the North Atlantic Current, after the shoaling of the CAS. The divergence of the UK37’ and TEX86 temperature trends in those intervals suggests that the Gulf Stream intensification contributed to the strong North Atlantic seasonality that is observed toda
Reconstruction of warm-season temperatures in central Europe during the past 60 000 years from lacustrine branched glycerol dialkyl glycerol tetraethers (brGDGTs)
No full textMillennial-scale climate variations during the last glacial period, such as Dansgaard–Oeschger (D/O) cycles and Heinrich events, have been extensively studied using ice core and marine proxy records. However, there is a limited understanding of the magnitude of these temperature fluctuations in continental regions, and questions remain about the seasonal signal of these climate events. This study presents a 60,000-year long temperature reconstruction based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) extracted from lake sediments from the Eifel volcanic field, Germany. brGDGTs are bacterial membrane lipids that are known to have strong relationship with temperature, making them suitable for temperature reconstructions. We test several temperature calibration models on modern samples taken from soils and multiple maar lakes. We find a bias associated with water depth and anoxic conditions that can be corrected for by accounting for a brGDGT isomer that is only produced in anoxic conditions. The corrected temperature reconstruction correlates with proxy and model temperature record spanning the same time period, validating the calibration model. However, millennial-scale variability is significantly dampened in the brGDGT record, and in contrast to other northern hemisphere climate records, during several Heinrich stadials, temperatures actually increase. We demonstrate that these apparent discrepancies can be explained by the unique seasonal response of the brGDGT paleothermometer to temperatures of months above freezing (TMAF). Our data support the view that warm season temperatures in Europe varied minimally during the last glacial period, and that abrupt millennial-scale events were defined by colder, longer winters. Our continuous high-resolution temperature reconstruction provides important information about the magnitude of seasonal climate variability during the last glacial period that can be used to test climate models and inform studies of paleoecological change
Author, Philosopher Alexandra Stoddard to Speak March 2 at Williams Library
No full textOXFORD, Miss. – Contemporary philosopher, author, interior designer and speaker Alexandra Stoddard gives an inspirational lecture and reading March 2 at the University of Mississippi
High sea surface temperatures were a prerequisite for the development and expansion of the Great Barrier Reef
No full textThe Great Barrier Reef is the largest reef system in the modern ocean. To date, the influence of temperature on the origin and long-term evolution of the Great Barrier Reef remains enigmatic. Here, we present a 900–thousand year TEX86H-derived temperature proxy record from Ocean Drilling Program Site 820 in the Coral Sea. It demonstrates that the onset of reef growth on the outer shelf was preceded by a rise in summer temperature from ~26° to ~28°C at around 700 thousand years ago (marine isotope stage 17). This approximately 2°C rise in summer sea surface temperatures (SSTs) likely resulted in higher carbonate production rates, which were crucial for the formation of the Great Barrier Reef. Subsequently, reconstructed SSTs remained sufficiently warm for the Great Barrier Reef to thrive and evolve continuously. The evolution of the Great Barrier Reef, therefore, appears to be closely linked to SSTs
Stages for the More Sustainable Farm
Full text linkCurrently, agricultural farm units are faced with a double and most times contradictory challenge, in order to be successful: on the one hand the invested capital has to be profitable and the economic performance has to be maximised. On the other hand, given the socio-environmental situation, it is necessary to preserve and to protect the environment and natural resources. Given the potential conflict of the two aims, since the satisfaction of one implies the underperformance of the other (and vice versa), the question then is: which is the solution to choose? We intend, in this work, to formulate a farm plan with the purpose of reconciling the criteria of environmental sustainability with that of economic competitiveness. For this achievement we proceed to the comparative study of sustainability of different groups of farms identified in the study area (first evaluation cycle) through MESMIS (“Marco para la Evaluación de Sistemas de Manejo de Recursos Naturales Mediante Indicadores de Sustentabilidad” - Framework for Evaluation of Natural-Resource Systems Handling through Sustainability Indicators) methodology, that allowed to select the more sustainable group of farms. Based on the found potentialities and weakness on these production systems, we stepped to the planning of a production unit of bovine meat, which obeys simultaneously to economic and environmental objectives, using Multicriteria Decision. We finished the work with the sustainability evaluation between groups of farms identified previously and the planned farms (second evaluation cycle), based, again, in the MESMIS methodology, to confirm (or not) the greatest sustainability of the last ones. Analyses of the results allow us to confirm the greatest relative sustainability of the planned farm, for the diverse traced scenarios.Decision taking, planning, sustainability, Environmental Economics and Policy, Farm Management,
Global core-top compilation of published species-specific foraminifera-bound nitrogen isotopes data
No full textThis dataset contains a global compilation of published core-top (Holocene) species-specific foraminifera-bound nitrogen isotopes data used for Figures 5, 7 and 8 in Auderset et al., 2025
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