Der Beginn der nordhemisphärischen Vereisung und die Entwicklung kontinuierlichen Permafrostes in Eurasien zwischen dem Ende des Miozäns und dem frühen Pleistozän zählt zu den bedeutendsten klimatischen Ereignissen des Känozoikums. Der Zeitpunkt extensiver Vereisung auf den Kontinenten und des Arktischen Ozeans und damit verbundene Veränderungen der klimatischen Bedingungen bleibt bislang ungenau bestimmt.Speläotheme (sekundäre Höhlenkarbonate) stellen ein wichtiges Archiv kontinentaler Umweltbedingungen dar, welches durch besonders genaue radiometrische Altersmodelle für eine grosse Bandbreite an Paläoklimaproxies charakterisiert ist.Wir konnten erfolgreich diagenetisch unveränderte und datierbare Proben aus Zentral- und Nordsibirien identifizieren und schlagen eine Multi-proxy-Studie an U/Pb-datierten Stalagmiten vor. Diese Studie wird Einblicke in die thermalen und hydrologischen Bedingungen zwischen 10.3 Ma und 8 Ma liefern. Wasser aus in den Speläothemen eingeschlossenen Fluidinklusionen wird auf seine Isotopenzusammensetzung hin untersucht. Zudem wird die in den Speläothemen beobachtete Lamination genutzt, um die Saisonalität während des Torton und Messiniums zu rekonstruieren. Wir suchen finanzielle Unterstützung für die parallele Analyse der Isotopie des Fluidinklusionswassers, der Sauerstoff- und Kohlenstoffisotopie des Karbonates, und der Elementkonzentration in den Speläothemen. Diese Kombination geochemischer Methoden wird Einblicke in regionale Umweltbedingungen, die Niederschlagshistorie und Temperaturen während des Miozäns und vor der Entwicklung kontinuierlichen Permafrostes geben. Zusätzliche Proben werden genutzt, um den Wechsel vom eisfreien zu einem durch Permafrost charakterisierten Sibirien zeitlich genauer einzugrenzen.Das vorgeschlagene Projekt wird unser Wissen zur atmosphärischen Zirkulation, und daran geknüpfter Veränderungen des Feuchte- und Temperaturregimes während eines saisonal eisfreien Arktischen Ozeans erweitern.
The goal of this project is to capture and analyse fluctuations of the fresh water in the western Nordic Seas and to understand the related processes. The East Greenland Current in the Nordic Seas constitutes an important conduit for fresh water exiting the Arctic Ocean towards the North Atlantic. The Arctic Ocean receives huge amounts of fresh water by continental runoff and by import from the Pacific Ocean. Within the Arctic Ocean fresh water is concentrated at the surface through sea ice formation. The East Greenland Current carries this fresh water in variable fractions as sea ice and in liquid form; part of it enters the central Nordic Seas, via branching of the current and through eddies. It controls the intensity of deep water formation and dilutes the water masses which result from convection. The last decades showed significant changes of the fresh water yield and distribution in the Nordic Seas and such anomalies were found to circulate through the North Atlantic. In this project the fresh water inventory, its spatial distribution and its pathways between the East Greenland Current and the interior Greenland and Icelandic seas shall be captured by autonomous glider missions. The new measurements and existing data will, in combination with the modeling work of the research group, serve as basis for understanding the causes of the fresh water variability and their consequences for the North Atlantic circulation and deep water formation.
The study of the geodynamic evolution of the Arctic continental margin and opening of the Arctic Ocean represents a primary target of BGR research and is studied within the frame of the CASE programme. In addition to onshore geological investigations, BGR conducts airborne aeromagnetic surveys. The available series contains the results of aeromagnetic surveys from the CASE program as well as cooperation projects (PMAP, NARES & NOGRAM), which were obtained with helicopters or fixed-wing aircraft in the Arctic.
Model diatom aggregates were produced from the diatom Skeletonema marinoi and the natural microbial community of seawater collected in Oeresund (Stief et al. 2023), Central Arctic Ocean, and Japan Trench. S. marinoi was grown to stationary phase in L1 medium plus silicate (Guillard & Hargraves 1993) at 15°C under a light/dark regime of 14/10 h. The diatom aggregates were individually incubated at either atmospheric pressure (0.1 MPa = control treatment) or at gradually increasing hydrostatic pressure (0.1-100 MPa = pressure treatment) throughout 20 days in darkness and at 3°C. The pressure treatment simulated the sinking of diatom-bacteria aggregates from the ocean surface down into a hadal trench of 10 km depth. Pressure-induced leakage of dissolved organic matter (DOM) was followed throughout the incubations. Ambient concentrations of different DOM components were measured: Dissolved organic carbon (DOC), total dissolved nitrogen (TDN), protein-like and humic-like DOM fluorescence.
Soil algae are the most important primary producers where vascular plants are absent, as in the Arctic and Antarctica. They give rise to species-rich microbial food webs in biological soil crusts (biocrusts). The terrestrial snow- and ice-free areas are in permanent expansion as glaciers retreat, leaving behind extensive areas of uncovered rock and new soil. Biocrusts stabilize the soil surface and have an important role in soil development. However, the microbial food webs and the nutrient and energy flow to higher trophic levels remain largely unexplored. Here, we characterized the microbial predator-prey dynamics of polar soils by combining molecular and traditional culturing techniques. Using high-throughput sequencing of environmental samples, we assessed the biodiversity and function of soil protists, applying a trait-based approach for acquiring and describing functional traits, i.e., the feeding behavior of heterotrophic protists in relation to microalgae. The study encompasses the analysis of biocrust samples of three polar regions. In the Arctic, one region was sampled - Svalbard in the Arctic Ocean (78°N) in July 2021. In Antarctica, two regions were studied, i.e. King George Island (62°S) in the South Shetland archipelago of Maritime Antarctica and the Thala Hills oasis in Enderby Land, East Antarctica (67°S), between January and March 2022.
The Long-Term Ecological Research observatory HAUSGARTEN was established by the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung in the Fram Strait in summer 1999 to detect and track the impact of large-scale environmental changes on the marine ecosystem in the transition zone between the northern North Atlantic and the central Arctic Ocean. In this area, bathymetric data have been recorded with multibeam echosounders during 44 research expeditions on RV Polarstern and RV Maria S. Merian since 1984. From these data, a digital elevation model was generated and geostatistical analyses were performed to calculate geospatial derivatives and quantitative terrain descriptors for subsequent terrain analyses and habitat mapping. The dataset covers an area from 78°N to 81°N and 6°W to 12°E. To create the data product, archive data was used from seven different multibeam echosounders in various raw data formats. This data has been processed and cleaned with CARIS HIPS & SIPS, including sound velocity correction for datasets from 1999 and newer. Older datasets are calculated with a static sound velocity of 1500 m/s. Soundings where exported for gridding with Generic Mapping Tools (GMT) nearneighbor. The resulting Digital Elevation Model (DEM) is in the WGS84/Arctic Polar Stereographic (EPSG:3995) projection with a cell size of 100m x 100m. The hillshade was computed with a combination of slope and synthetic illumination with a vertical exaggeration of 10. Slope inclination was calculated with GDAL tool Slope with the formula of Zevenbergen and Thorne (1987) in degree. Terrain Ruggedness Index (TRI) was computed with the QGIS tool Ruggedness index following the approach of Riley et al. (1999) in meters. For the Bathymetric Position Indices (BPI), focal statistics have been calculated with the GRASS tool "r.neighbors" and the QGIS raster calculator following the concept of the Topographic Position Index (Weiss, 2001) with a circular reference area of 99 cells (broad) and 9 cells (fine). The additional coverage polygon layer gives and overview on the used datasets and their corresponding metadata. The map gives an overview on the LTER HAUSGARTEN area and the HAUSGARTEN 2024 DEM.
During the period from 1974 to 2018 various cruises from BGR acquired seismic lines worldwide. The aim of these marine expeditions was a detailed survey of the geological structure.
Total organic carbon (TOC) and mineral assemblages are key data sets determined to characterize marine sediments in terms of sediment provenances, processes, and depositional environments. In a comprehensive review and synthesis (Stein, 2008), such data were compiled for Arctic Ocean surface sediments and shown in nine selected distribution maps: four maps of clay minerals (illite, smectite, chlorite, and kaolinite), four maps of heavy minerals (amphibole, clinopyroxene, epidote, and garnet), and one TOC map. The data used to produce these maps, are represented in the three tables of this data report. For details in background information and methodology see primary source literature cited here as well as the Stein (2008) synthesis.
In March 2023, cell densities of the Arctic diatom Thalassiosira gravida (isolated from the Central Arctic Ocean) were determined to calculate its growth rates at different temperatures and photoperiods in the presence and absence of its natural microbiome. Therefore, a full-factorial experimental design was chosen with two levels of temperature (9°C; 13.5°C) and photoperiod (16h; 24h), to which axenic and xenic diatom cultures were acclimated for one week in climate cabinets prior to the start of the actual growth experiment at a light intensity of 50 µmol photons m-2 s-1. With an initial cell density of 1500 cells/ml, axenic and xenic diatoms were grown under the respective experimental conditions until a cell density of approximately 15000 cells/ml was reached. Cell densities were determined microscopically using an inverted light microscope, following the procedure described in detail in Giesler et al. (2023, 10.3389/fmars.2023.1244639).
This dataset compiles raw measurements generated to investigate perturbations of the marine nitrogen cycle during the Paleocene–Eocene Thermal Maximum (PETM). It includes abundances of isoprenoidal GDGTs (isoGDGTs) and crenarchaeol mass accumulation rates, (ii) chromatographic peak areas of bacteriohopanetetrol (BHT) and BHT-x, and (iii) the nitrogen isotopic composition of bulk sediments (bulk sediment δ¹⁵N). Samples were collected from multiple ocean basins and regions: the Central Arctic Ocean (IODP 302–M0004), East Tasman Plateau in the Southwest Pacific (ODP Site 1172), Central Northern Caucasus (Kheu River), the New Jersey Shelf/Atlantic Coastal Plain (ODP 174AX Ancora), the Côte d'Ivoire–Ghana Transform Margin in the equatorial Atlantic (ODP 959), the Southeast Newfoundland Ridge in the central North Atlantic (IODP 1403), Fur Island, Denmark (Fur Formation), and the Tarim Basin, western China (Qimugen Formation). Lipid biomarker data were obtained using liquid chromatography coupled to mass spectrometry, and bulk nitrogen isotope data were measured by elemental analysis coupled to isotope-ratio mass spectrometry.
| Organisation | Count |
|---|---|
| Bund | 180 |
| Europa | 17 |
| Land | 10 |
| Wissenschaft | 172 |
| Type | Count |
|---|---|
| Daten und Messstellen | 33 |
| Ereignis | 6 |
| Förderprogramm | 160 |
| Taxon | 3 |
| Text | 2 |
| unbekannt | 16 |
| License | Count |
|---|---|
| Geschlossen | 16 |
| Offen | 201 |
| Language | Count |
|---|---|
| Deutsch | 131 |
| Englisch | 108 |
| Resource type | Count |
|---|---|
| Archiv | 18 |
| Bild | 1 |
| Datei | 22 |
| Dokument | 2 |
| Keine | 93 |
| Unbekannt | 5 |
| Webdienst | 3 |
| Webseite | 89 |
| Topic | Count |
|---|---|
| Boden | 154 |
| Lebewesen und Lebensräume | 213 |
| Luft | 158 |
| Mensch und Umwelt | 215 |
| Wasser | 217 |
| Weitere | 210 |