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PANGAEA - Publishing Network for Geoscientific & Environmental Data (843.301 recursos)

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Citable datasets

Mostrando recursos 1 - 20 de 26.639

  1. C5 glycolipids of heterocystous cyanobacteria track symbiont abundance in the diatom Hemiaulus hauckii across the tropical North Atlantic

    Bale, Nicole Jane; Villareal, Tracy A; Hopmans, Ellen C; Brussaard, Corina P D; Besseling, Marc; Dorhout, Denise J C; Sinninghe Damsté, Jaap S; Schouten, Stefan
    TS2Diatom-diazotroph associations (DDAs) include marine heterocystous cyanobacteria found as exosymbionts and endosymbionts in multiple diatom species. Heterocysts are the site of N2 fixation and have thickened cell walls containing unique heterocyst glycolipids which maintain a low oxygen environment within the heterocyst. The endosymbiotic cyanobacterium Richelia intracellularis found in species of the diatom genus Hemiaulus and Rhizosolenia makes heterocyst glycolipids (HGs) which are composed of C30 and C32 diols and triols with pentose (C5) moieties that are distinct from limnetic cyanobacterial HGs with predominantly hexose (C6) moieties. Here we applied a method for analysis of intact polar lipids to the study...

  2. Organic UV stabilizers and UV filters in the sediment of Chinese Bohai and Yellow Seas in 2016

    Apel, Christina; Tang, Jianhui; Ebinghaus, Ralf
    Organic UV stabilizers and UV filters are applied to industrial materials and cosmetics worldwide. In plastics they prevent photo-induced degradation, while in cosmetics they protect human skin against harmful effects of UV radiation. This study reports on the occurrence and distribution of organic UV stabilizers and UV filters in the surface sediment of the Chinese Bohai and Yellow Seas for the first time. In total, 16 out of 21 analyzed substances were positively detected. Concentrations ranged from sub-ng/g dw to low ng/g dw. The highest concentration of 25 ng/g dw was found for octocrylene (OC) in the Laizhou Bay. In...

  3. Heavy mineral analysis and detrital U-Pb ages of the intracontinental Paleo-Yangzte basin, eastern margin of Tibetan Plateau

    Deng, Bin; Chew, David; Jiang, Lei; Mark, Chris; Cogn, Nathan; Wang, Zijian; Liu, Shugen
    The Paleo-Yangtze basin connected the Sichuan, Xichang and Chuxiong basins during the Late Mesozoic to Early Cenozoic. The Paleo-Yangtze basin subsequently fragmented later in the Cenozoic which makes it challenging to decipher its provenance shifts and the exhumation of the surrounding hinterlands. 47 Heavy mineral analyses combined with detrital (16 apatite, 8 rutile and 8 zircon) U-Pb dating were employed to elucidate the stratigraphic signatures and exhumation patterns along the eastern margin of the Tibetan Plateau during the Upper Cretaceous to Paleogene. Two key horizons have been identified across these basins based on their detrital mineralogy: a garnet-rich horizon within...

  4. 1.5 Ekman model response to the extratropical thermal forcing

    Shin, Yechul; Kang, Sarah
    We examine how the Ekman transport modulates the tropical response to hemispherically differential thermal forcing. The 1.5 layer ocean model is implemented to a gray atmospheric model, with no radiative feedbacks, coupled to an aquaplanet slab ocean. The control climate with no surface flux adjustment is perturbed by southern hemisphere cooling and northern hemisphere warming at the surface. We examine the sensitivity to the forcing amplitude, forcing location, and Ekman flux strength in the control climate. The tropics-to-midlatitude component of Ekman transport, which is a negative feedback that counteracts the prescribed forcing, dominates over the equatorial component, which is a...

  5. Carbon:Chlorophyll ratios of Subarctic Pacific surface waters

    Burt, William J; Westberry, Toby K; Behrenfeld, Michael J; Zeng, Chen; Izett, Robert; Tortell, Philippe Daniel
    We present optically-derived estimates of phytoplankton carbon (Cphyto) and chlorophyll a concentration (Chl) across a wide range of productivity and hydrographic regimes in the Subarctic Pacific Ocean. Our high-frequency measurements capture changes in Cphyto and Chl across regional gradients in macro- and micronutrient limitation, and sub-mesoscale hydrographic frontal zones. Throughout the majority of our survey region, carbon to chlorophyll ratios (Cphyto:Chl) ranged between 50-100. Lower values (10-20) were constrained to the highly productive coastal upwelling system along Vancouver Island, whereas higher estimated values (>200) were found directly off the southern British Columbia continental shelf. Further offshore, Cphyto:Chl was less variable,...

  6. (Table S2) Numbers and carapace widths of C. maenas and H. sanguineus sampled around Helgoland.

    Jungblut, Simon; Beermann, Jan; Boos, Karin; Saborowski, Reinhard; Hagen, Wilhelm
    The Asian shore crab Hemigrapsus sanguineus (De Haan, 1853) has recently established populations in the North Sea and now occurs within the native ranges of the green crab Carcinus maenas (Linnaeus, 1758). To determine potential competitive effects and to assess the progress of the invasion, species-specific population characteristics (numerical abundances, biomasses, and size distributions) of the two species around the island of Helgoland (German Bight, southern North Sea) were compared for surveys conducted in 2009 and 2014. Sampling sites were chosen based on accessibility and differed in their topography and wave exposure, which allowed testing for the influence of these...

  7. Velocity data for two tidewater glacier surges in Svalbard, 2012-2015

    Benn, Douglas I; Luckman, Adrian; Sevestre, Heidi
    A time-series of velocity data spanning recent surges of two tidewater glaciers in Svalbard: Aavatsmarkbreen (Dec 2012-Oct 2015) and Wahlenbergbreen (Sept 2013-Oct 2015). The data were obtained by feature tracking using pairs of TerraSAR-X backscatter intensity images, typically at 11 day intervals. The GeoTiff files are spatially filtered maps of surface speed. Filenames reveal satellite beams (strips) as well as dates and times.

  8. Carbon, carbon isotope and dinoflagellate and pollen of the Latrobe-1 and Point Margaret, Victoria, Australia

    Frieling, Joost; Huurdeman, Emiel P; Rem, Charlotte C M; Donders, Timme H; Pross, Jörg; Bohaty, Steven M; Holdgate, Guy R; Gallagher, Stephen J; McGowran, Brian; Bijl, Peter K
    Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene-Eocene sedimentary archives from the west of the Tasmanian Gateway...

  9. Inventory of glacial lakes in Austria (elevation >1700m)

    Buckel, Johannes; Otto, Jan-Christoph
    Glacial lakes constitute a substantial part of the legacy of vanishing mountain glaciation and act as water storage, sediment traps and sources of both natural hazards and leisure activities. For these reasons, they receive growing attention by scientists and society. However, while the evolution of glacial lakes has been studied intensively over timescales tied to remote sensing-based approaches, the longer-term perspective has been omitted due a lack of suitable data sources. We mapped and analysed the spatial distribution of glacial lakes in the Austrian Alps. Lakes in the inventory are located above 1.700 m a.s.l. and have a size greater...

  10. The effect of phosphorus limitation and heat stress on calcification in Emiliania huxleyi

    Gerecht, Andrea; Supraha, Luka; Henderiks, Jorijntje
    Calcifying haptophytes (coccolithophores) sequester carbon in the form of organic and inorganic cellular components (coccoliths). We examined the effect of phosphorus (P) limitation and heat stress on particulate organic and inorganic carbon (calcite) production in the coccolithophore Emiliania huxleyi. Both environmental stressors are related to rising CO2 levels and affect carbon production in marine microalgae, which in turn impacts biogeochemical cycling. Using semi-continuous cultures, we show that P limitation and heat stress decrease the calcification rate in E. huxleyi. However, using batch cultures, we show that different culturing approaches (batch versus semi-continuous) induce different physiologies. This affects the ratio of...

  11. A global sediment trap database of Mg/Ca in planktic foraminifera Globigerinoides ruber

    Gray, William R; Weldeab, Syee; Lea, David W; Rosenthal, Yair; Gruber, Nicolas; Donner, Barbara; Fischer, Gerhard
    The Mg/Ca of planktic foraminifera Globigerinoides ruber (white) is a widely applied proxy for tropical and sub-tropical sea-surface temperature. The accuracy with which temperature can be reconstructed depends on how accurately relationships between Mg/Ca and temperature and the multiple secondary controls on Mg/Ca are known; however, these relationships remain poorly quantified under oceanic conditions. Here, we present new calibrations based on 440 sediment trap/plankton tow samples from the Atlantic, Pacific and Indian Oceans, including 130 new samples from the Bay of Bengal/Arabian Sea and the tropical Atlantic Ocean. Our results indicate temperature, salinity and the carbonate system all significantly influence...

  12. Net Community Production derived from DeltaO2/Ar measurements and N2O-based corrections for vertical mixing in the Subarctic Northeast Pacific

    Izett, Robert; Manning, C C; Hamme, Roberta C; Tortell, Philippe Daniel
    We present the first field application of a N2O-based approach to correct for vertical mixing in the estimation of net community production (NCP) from mixed layer O2 measurements. Using new ship-based observations of N2O and biological oxygen saturation anomalies (DeltaO2/Ar) from the Subarctic Northeast Pacific, we provide refined mixed layer NCP estimates across contrasting hydrographic regimes and a comprehensive assessment of the methodological considerations and limitations of the approach. Increased vertical mixing coefficients at the base of the mixed layer, derived using N2O measurements, corresponded with periods of heightened wind speed and coastal upwelling. Corrections were most significant in coastal...

  13. Geochemistry of sediment core Kinneret_AA3

    Quintana Krupinski, Nadine B; Marlon, Jennifer R; Nishri, Ami; Street, Joseph H; Paytan, Adina
    Long-term fire histories provide insight into the effects of climate, ecology and humans on fire activity; they can be generated using accumulation rates of charcoal and soot black carbon in lacustrine sediments. This study uses both charcoal and black carbon, and other paleoclimate indicators from Lake Kinneret (Sea of Galilee), Israel, to reconstruct late Holocene variations in biomass burning and aridity. We compare the fire history data with a regional biomass-burning reconstruction from 18 different charcoal records and with pollen, climate, and population data to decipher the relative impacts of regional climate, vegetation changes, and human activity on fire. We...

  14. Pollen and biomarker record of Lake Dojran

    Masi, Alessia; Francke, Alexander; Pepe, Caterina; Thienemann, Matthias; Wagner, Bernd; Sadori, Laura
    A sediment sequence (Co1260, 717 cm) from Late Glacial to Holocene of Lake Dojran, located at the border between Greece and F.Y.R. of Macedonia, has been investigated to provide a high-resolution pollen and NPPs analysis. Percentage, concentration and influx values have been interpreted to reconstruct the vegetational dynamics of the last 12500 years. Late Glacial is characterized by steppic taxa replaced by Holocene vegetation after 11500 yr BP. Mesophilous plants dominate for the entire Holocene. The first human trace is clear since 5000 yr BP, but the start of a strong human impact is dated at 2600 yr BP. The...

  15. Age at length data for larval African halfbeak Hyporhamphus picarti (Hemiramphidae) in the Sine Saloum estuary, Senegal

    Döring, Julian; Neumann, S I; Sloterdijk, Hans; Ekau, Werner
    The African halfbeak Hyporhamphus picarti (Hemiramphidae) is one of the most abundant species within the ichthyoplankton community of the Sine Saloum estuary (Senegal). A year-round occurrence of larvae suggests that the Sine Saloum is an important spawning habitat for this species. Annual fluctuations in water temperature, however, can have severe impacts on the survival probabilities of marine fish larvae. To determine whether temperature has an effect on the growth of H. picarti during its larval development, larval age at length and somatic growth rates were investigated for two contrasting spawning seasons in 2014: February (cold season, 20.8°C) and June (warm...

  16. Population genetics analyses of larch tree stands in north-central Siberia

    Kruse, Stefan; Epp, Laura Saskia; Wieczorek, Mareike; Pestryakova, Ludmila A; Stoof-Leichsenring, Kathleen Rosmarie; Herzschuh, Ulrike
    Arctic treelines are facing a strong temperature increase as a result of recent global warming, causing possible changes in forest extent, which will alter vegetation-climate feedbacks. However, the mode and strength of the response is rather unclear, as potential changes are happening in areas that are very remote and difficult to access, and empirical data are still largely lacking. Here, we assessed the current population structure and genetic differentiation of Larix Mill. tree stands within the northernmost latitudinal treeline reaching ~72° N in the southern lowlands of the Taymyr Peninsula (~100° E). We sampled 743 individuals belonging to different height classes...

  17. Pollen analytical investigations at Carrownaglogh prehistoric field system, County Mayo, Ireland

    O'Connell, Michael
    Palaeoecological investigations were carried out at a late Bronze Age site situated at Carrownaglogh, northeast Co. Mayo, with a view to reconstructing environmental conditions prior to and following blanket bog growth, which served to preserve the site. The main feature of the excavated area consisted of a stone wall enclosure (2.2 ha) sited on a small knoll at 150 m O.D. Well defined cultivation ridges, 14C dated to the 9th century B.C., filled the area within the enclosure. Outside the enclosure, the ground is ridged or levelled and stone cleared. Soil profile descriptions, chemical and mechanical analyses of fossil soils and pollen...

  18. Absorption line height and chl-a during POLARSTERN cruises PS93.2 and PS99.2 from underway spectrophotometry and discrete water samples

    Liu, Yangyang; Röttgers, Rüdiger; Ramírez-Pérez, Marta; Dinter, Tilman; Steinmetz, Francois; Nöthig, Eva-Maria; Hellmann, Sebastian; Wiegmann, Sonja; Bracher, Astrid
    We present a data set on particulate absorption line height at 676 and surface Chl-a concentration using underway spectrophotometry (Wetlabs AC-s instrument) and collocated discrete water sampling (measured by High Pressure Liquid Chromatography, HPLC, and Quantitative Filtration Technique) during two summer cruises PS93.2 and PS99.2 in the Fram Strait. Additionally we present for the discrete water samples the fraction of different phytoplankton groups on the total biomass, approximated by the chl-a concentration, which are derived from phytoplankton marker pigments also measured by HPLC. All details on the methods can be found in: Liu. Y., Roettgers R., Ramírez-Pérez M., Dinter T.,...

  19. Collection of data on physical and chemical soil properties in the Jena Experiment (Main Experiment)

    Kreutziger, Yvonne; Baade, Jussi; Gleixner, Gerd; Habekost, Maike; Hildebrandt, Anke; Schwichtenberg, Guido; Attinger, Sabine; Oelmann, Yvonne; Wilcke, Wolfgang; Cortois, Roeland; De Deyn, Gerlinde B; Luo, Guangjuan; Meyer, Sebastian Tobias
    This collection contains measurements of physical and chemical soil properties on the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional...

  20. Late Miocene alkenone unsaturation data, age models, and regional stacks of alkenones

    Herbert, Timothy D; Lawrence, Kira T; Tzanova, Alexandrina; Peterson, Laura C; Caballero-Gill, Rocio P; Kelly, Christopher S
    During the late Miocene epoch, about seven million years ago, large areas of the continents experienced drying, enhanced seasonality, and a restructuring of terrestrial plant and animal communities. These changes are seen throughout the subtropics, but have typically been attributed to regional tectonic forcing. Here we present a set of globally distributed sea surface temperature records spanning the past 12 million years based on the alkenone unsaturation method. We find that a sustained late Miocene cooling occurred synchronously in both hemispheres, and culminated with ocean temperatures dipping to near-modern values between about 7 and 5.4 million years ago. The period...

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