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  • 2020-2024  (3)
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  • 1
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    Reconstructed upper ocean temperature (UK'37 and TEXH86) of sediment core GL-1180, western tropical Atlantic (2023)
    PANGAEA
    Details
    Publikationsdatum: 2023-12-02
    Beschreibung: During glacial terminations, the role of cross-equatorial currents in the northward spreading of warm and salty waters is essential to the reach of the following interglacial state. In the western tropical Atlantic, where the interhemispheric North Brazil current develops, most of the existing temperature records focused on the last deglaciation. Here, using a marine sediment core covering the last 305 kyr before present (BP), we present two records of the surface (mixed layer) and the subsurface (upper thermocline) temperatures based on organic proxies UK'37 and TEXH86 respectively. During the last three glacial terminations, these records exhibit large temperature increases especially in the subsurface layer. We suggest the combined influence of the thermal bipolar seesaw and the Agulhas Leakage, acting together to warm the interior South Atlantic, to explain the strong warming of the tropical western Atlantic thermocline (+ 5°C) during these periods of reduced AMOC. In addition, we propose an enhanced cross-equatorial gyre to elucidate the synchronous deglacial warming of the western and eastern sides of the tropical Atlantic. The resumption of the AMOC at the onset of the following interglacial leads to the release of heat stored in thermocline waters mainly in the whole South Atlantic, as highlighted by the sharp upper ocean cooling recorded at the end of the deglacial interval. The combination of this temperature record and previously published ones in the western tropical Atlantic confirms the strong sensitivity of the upper ocean to AMOC changes in this region.
    Schlagwort(e): AGE; Alkenone, unsaturation index UK'37; Calculated from C37 alkenones; Calculated from isoprenoid GDGTs; Core; CORE; Deglaciations; DEPTH, sediment/rock; GL1180; GL-1180; Tetraether index of 86 carbon atoms; TEXH86; UK'37; western tropical Atlantic
    Materialart: Dataset
    Format: text/tab-separated-values, 256 data points
    Standort Signatur Erwartet Verfügbarkeit
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    DATEN PANGAEA
  • 2
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    MAAT, MAP and pH in soils and peats (2022)
    PANGAEA
    Details
    Publikationsdatum: 2024-02-24
    Beschreibung: Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a family of bacterial lipids which have emerged over time as robust temperature and pH paleoproxies in continental settings. Despite improvements in brGDGT analytical methods and development of refined models, the root-mean-square error (RMSE) associated with global calibrations between brGDGT distribution and MAAT in soils and peats remains high (~ 5 °C). Here we proposed to extend the global brGDGT terrestrial dataset previously proposed (n = 663; Dearing Crampton-Flood et al., 2019) with 112 soil samples from 6 altitudinal transects located in France (n = 49), Italy (n = 24), Tibet (n = 17), Chile (n = 8) and Peru (n =14). The transects were selected to take into account as much climatic and environmental variability as possible. All of these surficial soil samples (0 -10 cm depth) cover a wide range of temperatures (0°C to 26°C) and pH (3 to 8) and are representative of a wide diversity of environmental variables, vegetation and soil type. These new data were combined with previously published ones. This allowed the development of a new global terrestrial brGDGT temperature calibration from a worldwide extended dataset (i.e. 775 soil and peat samples) using a machine learning algorithm. This new model, called random Forest Regression for PaleOMAAT using brGDGTs (FROG), represents a refined brGDGT temperature calibration (R² = 0.8; RMSE = 4.01°C) for soils and peats, more robust and accurate than previous global soil calibrations while being proposed on an extended dataset.
    Schlagwort(e): Area/locality; branched GDGT; Branched GDGTs; Chile; DATE/TIME; ELEVATION; Event label; France; GDGT; GDGTs; global temperature calibration; Italy; LATITUDE; Latitude 2; LONGITUDE; Longitude 2; MAAT; machine learning; MULT; Multiple investigations; peat; Peru; pH; Precipitation, annual, mean; Reference/source; Sample ID; Sample type; Soil; Temperature, air, annual mean; Tibet
    Materialart: Dataset
    Format: text/tab-separated-values, 725 data points
    Standort Signatur Erwartet Verfügbarkeit
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    DATEN PANGAEA
  • 3
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    Bulk geochemical data and fractional abundances of brGDGTs and brGMGTs in soils, SPM and sediments in the Seine River basin (NW France) (2024)
    PANGAEA
    Details
    Publikationsdatum: 2024-04-18
    Beschreibung: This dataset includes elemental and isotopic data, environmental parameters, and fractional abundances of branched glycerol dialkyl glycerol tetraethers (brGDGTs) and branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in the soils, Suspended Particulate Matter (SPM), and sediments collected along the Seine River basin in Northwest France. Samples (n=237) were collected in high-flow (over 250 m³/s) and low-flow (below 250 m³/s) periods from the three zones (river, upstream estuary and downstream estuary) of the Seine River basin from 2015 to 2021. Elemental and isotopic analyses were performed by an elemental analyzer coupled with an isotope ratio mass spectrometer. The brGDGTs and brGMGTs were analyzed using high pressure liquid chromatography coupled with mass spectrometry with an atmospheric pressure chemical ionization source in selected ion monitoring mode. Using this dataset, we aim to (1) investigate the sources of brGDGTs and brGMGTs along the land-sea continuum, (2) identify the environmental factors influencing the distribution of these molecules, and (3) evaluate the applicability of brGMGTs as an indicator for riverine runoff.
    Schlagwort(e): Acyclic glycerol dialkyl glycerol tetraether; Archaeal glycerol dialkyl glycerol tetraether (peak area); Branched and isoprenoid tetraether index; Branched glycerol dialkyl glycerol tetraether, 1036d; Branched glycerol dialkyl glycerol tetraether, 1050d; Branched glycerol dialkyl glycerol tetraether, Ia; Branched glycerol dialkyl glycerol tetraether, Ib; Branched glycerol dialkyl glycerol tetraether, Ic; Branched glycerol dialkyl glycerol tetraether, IIa (5); Branched glycerol dialkyl glycerol tetraether, IIa (6); Branched glycerol dialkyl glycerol tetraether, IIa (7); Branched glycerol dialkyl glycerol tetraether, IIb (5); Branched glycerol dialkyl glycerol tetraether, IIb (6); Branched glycerol dialkyl glycerol tetraether, IIc (5); Branched glycerol dialkyl glycerol tetraether, IIc (6); Branched glycerol dialkyl glycerol tetraether, IIIa (5); Branched glycerol dialkyl glycerol tetraether, IIIa (6); Branched glycerol dialkyl glycerol tetraether, IIIa (7); Branched glycerol dialkyl glycerol tetraether, IIIb (5); Branched glycerol dialkyl glycerol tetraether, IIIb (6); Branched glycerol dialkyl glycerol tetraether, IIIb (7); Branched glycerol dialkyl glycerol tetraether, IIIc (5); Branched glycerol dialkyl glycerol tetraether, IIIc (6); Branched glycerol dialkyl glycerol tetraether (peak area); Branched glycerol monoalkyl glycerol tetraethers, H1020a; Branched glycerol monoalkyl glycerol tetraethers, H1020b; Branched glycerol monoalkyl glycerol tetraethers, H1020c; Branched glycerol monoalkyl glycerol tetraethers, H1034a; Branched glycerol monoalkyl glycerol tetraethers, H1034b; Branched glycerol monoalkyl glycerol tetraethers, H1034c; Branched glycerol monoalkyl glycerol tetraethers, H1048; Branched glycerol monoalkyl glycerol tetraethers (peak area); brGDGTs; brGMGTs; Carbon, organic, total; Chlorophyll a; Comment of event; Crenarchaeol; Crenarchaeol regio-isomer; CTD, Sea-Bird; Date/Time of event; Dicyclic glycerol dialkyl glycerol tetraether; Elemental analyzer coupled with an isotope ratio mass spectrometer, Thermo Fisher Scientific, Delta V Advantage; Estuary; Event label; Fluorometer, Cyclops, Turner Design; France; High pressure liquid chromatography coupled with mass spectrometry with an atmospheric pressure chemical ionization source (HPLC-APCI-MS), Shimadzu, LCMS 2020; Isomer ratio; Latitude of event; Longitude of event; Monocyclic glycerol dialkyl glycerol tetraether; Month; MULT; Multiparametric probe (600QS, YSI Inc.); Multiple investigations; Nitrogen, total; Organic Geochemistry; Oxygen saturation; Period; pH; river; Riverine Index; River kilometer; Salinity; Sample ID; Sample type; Seine_site1; Seine_site10; Seine_site11; Seine_site12; Seine_site13; Seine_site14; Seine_site15; Seine_site16; Seine_site17; Seine_site18; Seine_site19; Seine_site2; Seine_site3; Seine_site4; Seine_site5; Seine_site6; Seine_site7; Seine_site8; Seine_site9; Seine_siteA; Seine_siteB; Seine_siteC; Seine_siteD; Seine_siteE; Temperature, water; Tricyclic glycerol dialkyl glycerol tetraether; Turbidity (Nephelometric turbidity unit); Year of observation; Zone; δ13C, organic carbon; δ15N
    Materialart: Dataset
    Format: text/tab-separated-values, 12192 data points
    Standort Signatur Erwartet Verfügbarkeit
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    DATEN PANGAEA
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