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  • Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754  (4)
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  • 1
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    PANGAEA
    In:  Supplement to: Grasse, Patricia; Stichel, Torben; Stumpf, Roland; Stramma, Lothar; Frank, Martin (2012): The distribution of neodymium isotopes and concentrations in the Eastern Equatorial Pacific Water mass advection versus particle exchange. Earth and Planetary Science Letters, 198-207, https://doi.org/10.1016/j.epsl.2012.07.044
    Publication Date: 2023-10-28
    Description: The radiogenic isotope composition of the Rare Earth Element (REE) neodymium (Nd) is a powerful water mass proxy for present and past ocean circulation. The processes controlling the Nd budget of the global ocean are not quantitatively understood and in particular source and sink mechanisms are still under debate. In this study we present the first full water column data set of dissolved Nd isotope compositions and Nd concentrations for the Eastern Equatorial Pacific (EEP), where one of the globally largest Oxygen Minimum Zones (OMZ) is located. This region is of particular interest for understanding the biogeochemical cycling of REEs because anoxic conditions may lead to release of REEs from the shelf, whereas high particle densities and fluxes potentially remove the REEs from the water column. Data were obtained between 11400N and 161S along a nearshore and an offshore transect. Near surface zonal current bands, such as the Equatorial Undercurrent (EUC) and the Subsurface Countercurrent (SSCC), which are supplying oxygen-rich water to the OMZ are characterized by radiogenic Nd isotope signatures (eNd=-2). Surface waters in the northernmost part of the study area are even more radiogenic (eNd = +3), most likely due to release of Nd from volcanogenic material. Deep and bottom waters at the southernmost offshore station (141S) are clearly controlled by advection of water masses with less radiogenic signatures (eNd=- 7) originating from the Southern Ocean. Towards the equator, however, the deep waters show a clear trend towards more radiogenic values of up to eNd=-2. The northernmost station located in the Panama basin shows highly radiogenic Nd isotope signatures in the entire water column, which indicates that particle scavenging, downward transport and release processes play an important role. This is supported by relatively low Nd concentrations in deep waters (3000-6000 m) in the EEP (20 pmol/kg) compared to locations in the Northern and Central Pacific (40-60 pmol/kg), which suggests enhanced removal of Nd in the EEP.
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 2
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    PANGAEA
    In:  Supplement to: Ehlert, Claudia; Doering, Kristin; Wallmann, Klaus; Scholz, Florian; Sommer, Stefan; Grasse, Patricia; Geilert, Sonja; Frank, Martin (2016): Stable silicon isotope signatures of marine pore waters – Biogenic opal dissolution versus authigenic clay mineral formation. Geochimica et Cosmochimica Acta, 191, 102-117, https://doi.org/10.1016/j.gca.2016.07.022
    Publication Date: 2023-10-28
    Description: Dissolved silicon isotope compositions have been analysed for the first time in pore waters (δ30SiPW) of three short sediment cores from the Peruvian margin upwelling region with distinctly different biogenic opal content in order to investigate silicon isotope fractionation behaviour during early diagenetic turnover of biogenic opal in marine sediments. The δ30SiPW varies between +1.1‰ and +1.9‰ with the highest values occurring in the uppermost part close to the sediment–water interface. These values are of the same order or higher than the δ30Si of the biogenic opal extracted from the same sediments (+0.3‰ to +1.2‰) and of the overlying bottom waters (+1.1‰ to +1.5‰). Together with dissolved silicic acid concentrations well below biogenic opal saturation, our collective observations are consistent with the formation of authigenic alumino-silicates from the dissolving biogenic opal. Using a numerical transport-reaction model we find that approximately 24% of the dissolving biogenic opal is re-precipitated in the sediments in the form of these authigenic phases at a relatively low precipitation rate of 56 μmol Si cm−2 yr−1. The fractionation factor between the precipitates and the pore waters is estimated at −2.0‰. Dissolved and solid cation concentrations further indicate that off Peru, where biogenic opal concentrations in the sediments are high, the availability of reactive terrigenous material is the limiting factor for the formation of authigenic alumino-silicate phases.
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: application/zip, 6 datasets
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  • 3
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    PANGAEA
    In:  Supplement to: Grasse, Patricia; Bosse, Michael; Hathorne, Ed C; Böning, Philipp; Pahnke, Katharina; Frank, Martin (2017): Short-term variability of dissolved rare earth elements and neodymium isotopes in the entire water column of the Panama Basin. Earth and Planetary Science Letters, 475, 242-253, https://doi.org/10.1016/j.epsl.2017.07.022
    Publication Date: 2023-12-09
    Description: The distribution of dissolved rare earth elements (REEs) and neodymium isotopes (εNd) in the open ocean traces water mass mixing and provides information on lithogenic inputs to the source regions of the water masses. However, the processes influencing the REE budget at the ocean margins, in particular source and sink mechanisms, are not yet well quantified. In this study the first dissolved REE concentrations and Nd isotope compositions of seawater from the Panama Basin (RV Meteor cruise M90) in the Eastern Equatorial Pacific (EEP) are presented.
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
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  • 4
    Publication Date: 2024-03-28
    Description: Seawater samples for stable isotopes measurements of dissolved silicate (δ30Si), nitrate (δ15NO3-) and nitrite (δ15NO2-) were taken from the CTD/rosette on a number of SFB 754 cruises. Seawater samples for Rare Earth Element (REE) concentrations and neodymium (Nd) isotopes were taken during M77/3, M77/4 (Grasse et al., 2012) and during M90 in the Panama Basin (Grasse et al., 2017).
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: 9 datasets
    Location Call Number Expected Availability
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