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  • Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754  (3)
  • 234Th tracer; Climate - Biogeochemistry Interactions in the Tropical Ocean; eastern tropical South Pacific; SFB754; uranium-salinity correlation  (1)
  • Phytoplankton  (1)
Document type
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Years
  • 1
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    PANGAEA
    In:  Supplement to: Engel, Anja; Wagner, Hannes; Le Moigne, Frédéric A C; Wilson, Samuel T (2017): Particle export fluxes to the oxygen minimum zone of the eastern tropical North Atlantic. Biogeosciences, 14(7), 1825-1838, https://doi.org/10.5194/bg-14-1825-2017
    Publication Date: 2023-10-28
    Description: In the ocean, sinking of particulate organic mat- ter (POM) drives carbon export from the euphotic zone and supplies nutrition to mesopelagic communities, the feeding and degradation activities of which in turn lead to export flux attenuation. Oxygen (O2) minimum zones (OMZs) with suboxic water layers (〈 5 µmol O2 kg-1 ) show a lower carbon flux attenuation compared to well- oxygenated waters (〉 100 µmol O2 kg-1), supposedly due to reduced heterotrophic activity. This study focuses on sinking particle fluxes through hypoxic mesopelagic waters (〈 60 µmol O2 kg-1); these represent about 100 times more ocean volume globally compared to suboxic waters, but they have less been studied. Particle export fluxes and attenuation coefficients were determined in the eastern tropical North Atlantic (ETNA) using two surface-tethered drifting sediment trap arrays with seven trapping depths located between 100 and 600 m.
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: application/zip, 6 datasets
    Location Call Number Limitation Availability
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  • 2
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    PANGAEA
    In:  Supplement to: Cisternas Novoa, Carolina; Le Moigne, Frédéric A C; Engel, Anja (2019): Composition and vertical flux of particulate organic matter to the oxygen minimum zone of the central Baltic Sea: impact of a sporadic North Sea inflow. Biogeosciences, 16(4), 927-947, https://doi.org/10.5194/bg-16-927-2019
    Publication Date: 2024-02-16
    Description: Here, we investigate the composition and vertical fluxes of POM in two deep basins of the Baltic Sea (GB: Gotland Basin and LD: Landsort Deep).
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: application/zip, 7 datasets
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2024-02-15
    Description: The eastern boundary region of the southeastern Pacific Ocean hosts one of the world's most dynamic and productive upwelling systems with an associated oxygen minimum zone (OMZ). The variability in downward export fluxes in this region, with strongly varying surface productivity, upwelling intensities and water column oxygen content, is however poorly understood. Thorium-234 (234Th) is a powerful tracer to study the dynamics of export fluxes of carbon and other elements, yet intense advection and diffusion in nearshore environments impact the assessment of depth-integrated 234Th fluxes when not properly evaluated. Here we use VmADCP current velocities, satellite wind speed and in situ microstructure measurements to determine the magnitude of advective and diffusive fluxes over the entire 234Th flux budget at 25 stations from 11°S to 16°S in the Peruvian OMZ. Contrary to findings along the GEOTRACES P16 eastern section, our results showed that weak surface wind speed during our cruises induced low upwelling rates and minimal upwelled 234Th fluxes, whereas vertical diffusive 234Th fluxes were important only at a few shallow shelf stations. Horizontal advective and diffusive 234Th fluxes were negligible because of small alongshore 234Th gradients. Our data indicated a poor correlation between seawater 238U activity and salinity. Assuming a linear relationship between the two would lead to significant underestimations of the total 234Th flux by up to 40% in our study. Proper evaluation of both physical transport and variability in 238U activity is thus crucial in coastal 234Th flux studies. Finally, we showed large temporal variations on 234Th residence times across the Peruvian upwelling zone, and cautioned future carbon export studies to take these temporal variabilities into consideration while evaluating carbon export efficiency.
    Keywords: 234Th tracer; Climate - Biogeochemistry Interactions in the Tropical Ocean; eastern tropical South Pacific; SFB754; uranium-salinity correlation
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Limitation Availability
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  • 4
    Publication Date: 2024-06-27
    Description: In the ocean, downward flux of particles produced in sunlit surface waters is the major component of the biological carbon pump, which sequesters atmospheric carbon dioxide and fuels deep-sea ecosystems. The efficiency of downward carbon transfer is expected to be particularly high in tropical upwelling systems where hypoxia occurring beneath the productive surface waters is thought to hamper particle consumption. However, observations of both particle feeders and carbon export in low-oxygen waters are scarce. Here, we provide evidence that hypoxia-tolerant zooplankton feed on sinking particles in the extensive Oxygen Minimum Zone off Peru. Using several arrays of drifting sediment traps and in situ imaging, we show geochemical and morphological transformations of sinking particles and substantial control of carbon export by zooplankton. Our findings challenge the assumption of a consistently efficient biological carbon pump in OMZs and further demonstrate the need to consider mesopelagic organisms' adaptations when studying oceanic carbon sequestration.
    Keywords: Climate - Biogeochemistry Interactions in the Tropical Ocean; SFB754
    Type: Dataset
    Format: application/zip, 7 datasets
    Location Call Number Limitation Availability
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  • 5
    Publication Date: 2022-10-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Kharbush, J. J., Close, H. G., Van Mooy, B. A. S., Arnosti, C., Smittenberg, R. H., Le Moigne, F. A. C., Mollenhauer, G., Scholz-Boettcher, B., Obreht, I., Koch, B. P., Becker, K. W., Iversen, M. H., & Mohr, W. Particulate organic carbon deconstructed: molecular and chemical composition of particulate organic carbon in the ocean. Frontiers in Marine Science, 7, (2020): 518, doi:10.3389/fmars.2020.00518.
    Description: The dynamics of the particulate organic carbon (POC) pool in the ocean are central to the marine carbon cycle. POC is the link between surface primary production, the deep ocean, and sediments. The rate at which POC is degraded in the dark ocean can impact atmospheric CO2 concentration. Therefore, a central focus of marine organic geochemistry studies is to improve our understanding of POC distribution, composition, and cycling. The last few decades have seen improvements in analytical techniques that have greatly expanded what we can measure, both in terms of organic compound structural diversity and isotopic composition, and complementary molecular omics studies. Here we provide a brief overview of the autochthonous, allochthonous, and anthropogenic components comprising POC in the ocean. In addition, we highlight key needs for future research that will enable us to more effectively connect diverse data sources and link the identity and structural diversity of POC to its sources and transformation processes.
    Description: We thank the Hanse Institute for Advanced Studies (HWK) and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 422798570, as well as the Geochemical Society, for funding which made the workshop possible. CA was additionally supported by OCE-1736772. BV was additionally supported by NSF OCE-1756254.
    Keywords: Marine particles ; Water column ; Phytoplankton ; Marine microbes ; Structural analysis ; Organic matter characterization ; Biomarkers
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Location Call Number Limitation Availability
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