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PANGAEA - Publishing Network for Geoscientific & Environmental Data (863.041 recursos)

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Citable datasets

Mostrando recursos 1 - 20 de 20.729

  1. Time series of methane and carbon dioxide concentrations measured in subglacial air, Western Greenland

    Christiansen, Jesper Riis; Juncher Jørgensen, Christian
    Time series of methane and carbon dioxide concentrations measured in subglacial air in a cave under the Isunnguate Sermia glacier, Western Greenland. The Isunnguata Sermia is a glacier fed by the Greenland Ice Sheet. The time series are of shorter duration, 1 to 7 hours, and cover a 4-day period from August 23rd - 26th 2016. In situ concentrations of methane and carbon dioxide of the subglacial air were measured using a portable greenhouse gas analyzer based on state-of-the-art cavity ring-down spectroscopy with a measurement precision of 3 ppb and 0.4 ppm for methane and carbon dioxide, respectively and a sampling...

  2. Sedimentological, biogeochemical and geochronological data of yedoma and thermokarst deposits in West-Alaska

    Jongejans, Loeka L; Strauss, Jens; Lenz, Josefine; Peterse, Francien; Mangelsdorf, Kai; Fuchs, Matthias; Grosse, Guido
    These datasets describe samples taken from yedoma and thermokarst deposits in Baldwin Peninsula (BAL), West-Alaska. Five locations were sampled: a yedoma exposure (B2), three drained thermokarst lake basin (DTLB) exposures (B2, B3 and B4) and a thermokarst lake (UPL1-L1). The collection and analysis of the samples are described in Jongejans et al. (in review). The first four datasets include sampling dates, type of environment (active layer, permafrost or thermokarst lake), site coordinates and the depth from the sediment surface. Dataset https://doi.pangaea.de/10.1594/PANGAEA.892306 presents sedimentological (ice content, bulk density, grain size) and biogeochemical parameters (TC, TN, TOC, C/N, d13C) of the yedoma (B2),...

  3. Mollusk shell d18O in the past 1600 years in the Saloum Delta, Senegal

    Carré, Matthieu; Azzoug, Moufok; Zaharias, Paul; Camara, Abdoulaye; Cheddadi, Rachid; Chevalier, Manuel; Fiorillo, Denis; Gaye, Amadou T; Janicot, Serge; Khodri, Myriam; Lazar, Alban; Lazareth, Claire E; Mignot, Juliette; Mitma Garcia, Nancy; Patris, Nicolas; Perrot, Océane; Wade, Malick
    As climate model uncertainties remain very large for future rainfall in the Sahel, a multi-centennial perspective is required to assess the situation of current Sahel climate in the context of global warming. We present here the first record of hydroclimatic variability over the past 1600 years in Senegal, obtained from stable oxygen isotope analyses (δ18O) in archaeological shell middens from the Saloum Delta. During the preindustrial period, the region was relatively humid, with maximum humidity reached during the period from AD 1500 to AD 1800, referred to as the Little Ice Age. A significant negative link is observed at the...

  4. Isotopic composition of benthic and planktic foraminifera and bulk sediment from ODP Holes198-1209A and 208-1265A

    Harper, Dustin T; Zeebe, Richard E; Hönisch, Bärbel; Schrader, Cindy D; Lourens, Lucas Joost; Zachos, James C
    Eocene Thermal Maximum 2 (ETM-2; ca. 54.2 Ma) represents the second largest of the major Eocene hyperthermals, yet comparatively little is known about the scale and rate of climatic change for key regions. Here we provide the first detailed records of subtropical sea-surface warming and salinization for ETM-2 at two subtropical locations, Ocean Drilling Program Sites 1209 (North Pacific) and 1265 (South Atlantic). Coupled planktic foraminiferal Mg/Ca and δ18O indicate 2-4 °C of rapid warming and local salinization of ~1-2 ppt at both sites. The increase in sea-surface temperature is equivalent to anomalies reported from higher latitude sites, and is...

  5. Deglacial authigenic and bulk sediment neodymium isotope records from sediment cores in the Gulf of Alaska

    Du, Jianghui; Haley, Brian A; Mix, Alan C; Walczak, Maureen H; Praetorius, Summer K
    Here we report the neodymium isotope compositions of sedimentary authigenic Fe-Mn oxyhydroxide and bulk sediment in the Gulf of Alaska, Northeast Pacific. These records span the last 22,000 years. We use these records to reconstruct deglacial North Pacific circulation.

  6. Shell (weight, density, thickness, crushing force, amino acid content) and soft tissue metrics (somatic tissue weight, gonad index) for eastern oysters Crassostrea virginica reared under variable predation conditions (S. Texas, 2013-14)

    Scherer, Avery E; Bird, Christopher E; McCutcheon, Melissa R; Hu, Xinping; Smee, Delbert L
    Inducing defenses to deter predators is a necessary process theorized to incur costs. Although studies have investigated defense trade-offs, quantifying trade-offs is challenging and costs are often inferred. Additionally, prey employ strategies to reduce costs, making costs difficult to predict. Our purpose was to investigate induced defense costs by characterizing the defense mechanisms and costs in eastern oysters (Crassostrea virginica). In the field (summer 2014; 28.13°N, 96.98°W), newly-settled oysters reared under field conditions and assigned to control or predator (blue crab, Callinectes sapidus) conditions, were tested for shell weight and crushing force (a proxy for shell strength; both metrics are...

  7. Benthic and substrate cover data derived from field photo-transect surveys for the Far Northern management region of the Great Barrier Reef

    Roelfsema, Christiaan M; Kovacs, Eva M; Markey, Kathryn; Phinn, Stuart R
    Field photos were uploaded to the CoralNet machine learning interface (https://coralnet.ucsd.edu/). A presviously trained subset of photoquadrats were uploaded as training images. Fifty annotation points were overlaid on all Great Barrier Reef (GBR) Legacy images and each was assigned a benthic cover category from a label list automatically by the program. The resulting benthic cover data of each photo was linked to gps coordinates, saved as an ArcMap point shapefile, and projected to Universal Transverse Mercator WGS84 Zone 55 South.

  8. Diatom-bound nitrogen isotope and opal flux records over the Holocene period in Southern Ocean sediment cores MD12-3396, MD11-3353 and PS75/072-4

    Studer, Anja S; Sigman, Daniel M; Martinez-Garcia, Alfredo; Thöle, Lena; Michel, Elisabeth; Jaccard, Samuel L; Lippold, Jörg; Mazaud, Alain; Wang, Xingchen T; Robinson, Laura F; Adkins, Jess; Haug, Gerald H
    The supplement contains 6 datasets. The abstract will be added by the authors.

  9. GAMDAM glacier inventory for High Mountain Asia

    Sakai, Akiko
    First version of GAMDAM (Glacier Area Mapping for Discharge from the Asian Mountains) glacier inventory are the first glacier inventory covering the HMA (High Mountain Asia), and underestimated glacier area because they did not include steep slopes covered with ice or snow and shadow part. In the process of revision of GAMDAM glacier inventory, source Landsat images are carefully selected in order to find shadow-free, cloud cover-free and seasonal snow cover-free images taken from 1990 to 2010. Then, more than 90% of glacier area in the final version of GAMDAM glacier inventory are delineated based on the summer Landsat images....

  10. Sediment core data from The Archipelago Sea, northern Baltic Sea, Finland, 2015

    Jokinen, Sami A; Virtasalo, Joonas J; Jilbert, Tom; Kaiser, Jérôme; Dellwig, Olaf; Arz, Helge W; Hänninen, J; Arppe, Laura; Collander, Miia; Saarinen, Timo
    The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment. Here we present a 1500-year multiproxy record of near-bottom water redox changes from the...

  11. Authigenic neodymium isotopic composition from sediment core KNR197-10 GGC17

    Pöppelmeier, Frerk; Gutjahr, Marcus; Blaser, Patrick; Keigwin, Lloyd D; Lippold, Jörg
    The notion of a shallow northern sourced intermediate water mass is a well evidenced feature of the Atlantic circulation scheme of the Last Glacial Maximum (LGM). However, recent observations from stable carbon isotopes (δ13C) at the Corner Rise in the deep northwest Atlantic suggested a significant contribution of a Northern Component Water mass to the abyssal northwest Atlantic basin that has not been described before. Here we test the hypothesis of this northern sourced water mass underlying the southern sourced glacial Antarctic Bottom Water by measuring the authigenic neodymium (Nd) isotopic composition from the same sediments from 5,010‐m water depth....

  12. Radiolarian abundances from IODP Holes 349-U1431D, 349-U1432C and 349-U1433A

    Hernández-Almeida, Iván
    We studied radiolarian abundances in 303 samples from International Ocean Discovery Program Expedition 349 in the South China Sea (SCS), which cored five deep-sea sites. Three of them, Sites U1431, U1432, and U1433, are located along a latitudinal gradient. We analyzed, using a light microscope, the total radiolarian abundance (radiolarians per gram of dry sediment) for middle and upper Pleistocene sedimentary sequences from these three sites. Radiolarian abundances are higher uphole, in particular at Site U1432 (northern SCS). Site U1433 (southwestern SCS) contains the lowest numbers of radiolarians. In general, there are more barren samples in the older part of...

  13. Relative abundance and fluxes of coccospheres, planktonic foraminifera ( >63 µm) and diatoms in sediment trap ALB-5 sampled from July 1997 to May 1998 in the Alboran Sea , Western Mediterranean Sea

    Hernández-Almeida, Iván; Bárcena, Maria Angeles; Flores, José-Abel; Sierro, Francisco Javier; Sanchez-Vidal, Anna; Calafat, Antonio M
    The present work analyses the seasonal evolution of planktonic assemblages and particle fluxes through the water column in the Eastern Alboran Sea (Western Mediterranean) at 35º55.47'N/01º30.77'W. A Sediment trap was deployed below the influence of the Almeria-Oran Front (AOF), a semi-permanent geostrophic front, during July 1997 to June 1998. Overall, the temporal variability of coccolithophore, planktonic foraminifer, diatom, benthic and wind-carried biogenic particle fluxes is linked to the seasonal evolution of sea surface hydrological structures. Maximum planktonic fluxes were found during high-productivity periods and wind-induced upwelling, following a trimodal pattern, with maximum fluxes in July 1997, November-December 1997, and April-May...

  14. Intact polar lipid composition and bottom water and surface sediment characteristics during R/V Pelagia cruise PASOM to the Arabian Sea in 2009

    Besseling, Marc; Hopmans, Ellen C; Sinninghe Damsté, Jaap S; Villanueva, Laura
    Benthic Archaea comprise a significant part of the total prokaryotic biomass in marine sediments. Recent genomic surveys suggest they are largely involved in anaerobic processing of organic matter but the distribution and abundance of these archaeal groups is still largely unknown. Archaeal membrane lipids composed of isoprenoid diethers or tetraethers (glycerol dibiphytanyl glycerol tetraether, GDGT) are often used as archaeal biomarkers. Here, we compare the archaeal diversity and intact polar lipid (IPL) composition in both surface (0-0.5 cm) and subsurface (10-12 cm) sediments recovered within, just below, and well below the oxygen minimum zone (OMZ) of the Arabian Sea. Archaeal...

  15. Geochemistry of five sediment sequences obtained in the Campo coastal plain on Elba Island (Tuscany, Italy)

    Becker, Fabian; Eser, Raphael; Hoelzmann, Philipp; Schütt, Brigitta
    We obtained five sediment sequences by percussion drilling in order to reconstruct human-landscape interactions in the context of ancient bloomery smelting on Elba Island, Tyrrhenian Sea, based on sedimentological evidences; Elba was, together with Populonia, the centre of iron production in antiquity (mid-6th century B.C.E. to 2nd century C.E.). The aim of the analysis is an assessment of (1) palaeolandscape site conditions, (2) morphodynamics triggered by human land use change (especially charcoal production to run the bloomeries); and (3) to characterize a sediment smelting signature. We described the sediments macroscopically and measured basic bulk geochemical parameters, including pH, electric conductivity,...

  16. Different Mid-Pleistocene transition analysis from IODP Site 306-U1314

    Hernández-Almeida, Iván; Sierro, Francisco Javier; Flores, José-Abel; Cacho, Isabel; Filippelli, Gabriel M
    Marine sediments from the Integrated Ocean Drilling Project (IODP) Site U1314 (56.36°N, 27.88°W), in the subpolar North Atlantic, were studied for their planktonic foraminifera, calcium carbonate content, and Neogloboqudrina pachyderma sinistral (sin.) δ13C records in order to reconstruct surface and intermediate conditions in this region during the Mid‐Pleistocene Transition (MPT). Variations in the palaeoceanography and regional dynamics of the Arctic Front were estimated by comparing CaCO3 content, planktonic foraminiferal species abundances, carbon isotopes and ice‐rafted debris (IRD) data from Site U1314 with published data from other North Atlantic sites. Site U1314 exhibited high abundances of the polar planktonic foraminifera N. pachyderma...

  17. Chrysophyte-based reconstruction of number of days below 4°C from sediment traps of Lake Zabinskie in northeastern Poland

    Hernández-Almeida, Iván; Grosjean, M; Przybylak, R; Tylmann, W
    Chrysophyte cysts are recognized as powerful proxies of cold-season temperatures. In this paper we use the relationship between chrysophyte assemblages and the number of days below 4 °C (DB4 °C) in the epilimnion of a lake in northern Poland to develop a transfer function and to reconstruct winter severity in Poland for the last millennium. DB4 °C is a climate variable related to the length of the winter. Multivariate ordination techniques were used to study the distribution of chrysophytes from sediment traps of 37 low-land lakes distributed along a variety of environmental and climatic gradients in northern Poland. Of all...

  18. Radiolarian relative abundance and opal and radiolarian accumulation rate from IODP Site 306-U1314

    Hernández-Almeida, Iván; Bjorklund, Kjell R; Sierro, Francisco Javier; Filippelli, Gabriel M; Cacho, Isabel; Flores, José-Abel
    A high-resolution record of radiolarian assemblages from Site U1314 was studied to reconstruct hydrographic and climatic changes in the North Atlantic Ocean during the Mid-Pleistocene Transition period (1069–779 ka). Besides the faunal record, absolute accumulation of radiolarians and total biogenic opal are used to determine changes in surface water productivity. Results show that the North Atlantic Arctic Front shifted back and forth repeatedly at a glacial/interglacial timescale, bringing the site under the influence of both cold Arctic (glacial), and much warmer Atlantic (interglacial) waters. During glacial intervals and “ice-rafted debris” (IRD) events, the deep-dwelling taxon Cycladophora davisiana was the greatest...

  19. Pacific oxygen reconstructions last 40,000 years

    Hoogakker, Babette A A; Lu, Zunli; Umling, Natalie; Jones, Luke; Zhou, Xiaoli; Rickaby, Rosalind E M; Thunell, Robert C; Cartapanis, Olivier; Galbraith, Eric D
    Seven spreadsheets accompanying a manuscript currently in review with Nature, including records of planktonic foraminifera I/Ca for ODP Sites 849 and 1242, benthic foraminifera dd13C for ODP 1242 and TR163-25, modern seawater O2 versus seawater d13C of DIC, and LCM-DICmodern d13C.

  20. (Supplement Fig. 2-4) Proxy data from IODP Site 306-U1314

    Hernández-Almeida, Iván; Sierro, Francisco Javier; Cacho, Isabel; Flores, José-Abel
    Subsurface water column dynamics in the subpo-lar North Atlantic were reconstructed in order to improve theunderstanding of the cause of abrupt ice-rafted detritus (IRD)events during cold periods of the early Pleistocene. We usedpaired Mg/Ca andδ18O measurements ofNeogloboquad-rina pachyderma(sinistral - sin.), deep-dwelling planktonicforaminifera, to estimate the subsurface temperatures andseawaterδ18O from a sediment core from Gardar Drift, inthe subpolar North Atlantic. Carbon isotopes of benthic andplanktonic foraminifera from the same site provide informa-tion about the ventilation and water column nutrient gradient . Mg/Ca-based temperatures and seawaterδ18O suggestincreased subsurface temperatures and salinities during ice-rafting, likely due to northward subsurface transport of sub-tropical waters...

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