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  • 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: 2024-02-15
    Keywords: 234Th tracer; Climate - Biogeochemistry Interactions in the Tropical Ocean; CTD/Rosette; CTD 002; CTD 003; CTD 012; CTD 017; CTD 028; CTD 040; CTD 053; CTD 054; CTD 065; CTD 073; CTD 077; CTD 086; CTD 094; CTD 101; CTD-RO; Date/Time of event; DEPTH, water; eastern tropical South Pacific; Elevation of event; Error, absolute; Event label; Fluorescence, chlorophyll; Latitude of event; Longitude of event; M138; M138_879-1; M138_879-3; M138_882-10; M138_883-12; M138_888-7; M138_892-14; M138_898-1; M138_898-2; M138_904-16; M138_906-18; M138_907-11; M138_912-3; M138_915-1; M138_919-1; Meteor (1986); Oxygen; Salinity; SFB754; Temperature, water; Thorium-234, total; Uranium-238; Uranium-238, error; uranium-salinity correlation
    Type: Dataset
    Format: text/tab-separated-values, 1006 data points
    Location Call Number Limitation Availability
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  • 5
    Publication Date: 2024-02-15
    Keywords: 234Th tracer; Climate - Biogeochemistry Interactions in the Tropical Ocean; CTD/Rosette; CTD 009; CTD 020; CTD 039; CTD 045; CTD 050; CTD 056; CTD 061; CTD 069; CTD 071; CTD 074; CTD 087; CTD 091; CTD 092; CTD-RO; Date/Time of event; DEPTH, water; eastern tropical South Pacific; Elevation of event; Error, absolute; Event label; Fluorescence, chlorophyll; Latitude of event; Longitude of event; M136; M136_353-1; M136_380-1; M136_402-1; M136_428-1; M136_445-1; M136_458-1; M136_472-1; M136_495-1; M136_508-1; M136_516-1; M136_547-1; M136_559-1; M136_567-1; Meteor (1986); Oxygen; Salinity; SFB754; Temperature, water; Thorium-234, total; Uranium-238; Uranium-238, error; uranium-salinity correlation
    Type: Dataset
    Format: text/tab-separated-values, 948 data points
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  • 6
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    PANGAEA
    In:  Supplement to: Le Moigne, Frédéric A C; Henson, Stephanie A; Sanders, Richard J; Madsen, Esben (2013): Global database of surface ocean particulate organic carbon export fluxes diagnosed from the 234Th technique. Earth System Science Data, 5, 295-304, https://doi.org/10.5194/essd-5-295-2013
    Publication Date: 2024-04-27
    Description: Through the processes of the biological pump, carbon is exported to the deep ocean in the form of dissolved and particulate organic matter. There are several ways by which downward export fluxes can be estimated. The great attraction of the 234Th technique is that its fundamental operation allows a downward flux rate to be determined from a single water column profile of thorium coupled to an estimate of POC/234Th ratio in sinking matter. We present a database of 723 estimates of organic carbon export from the surface ocean derived from the 234Th technique. Data were collected from tables in papers published between 1985 and 2013 only. We also present sampling dates, publication dates and sampling areas. Most of the open ocean Longhurst provinces are represented by several measurements. However, the Western Pacific, the Atlantic Arctic, South Pacific and the South Indian Ocean are not well represented. There is a variety of integration depths ranging from surface to 220m. Globally the fluxes ranged from -22 to 125 mmol of C/m**2/d. We believe that this database is important for providing new global estimate of the magnitude of the biological carbon pump.
    Keywords: -; Carbon, organic, flux; Comment; DATE/TIME; Date/time end; Day of the year; DEPTH, water; Identification; LATITUDE; LONGITUDE; Primary production of carbon per area, daily; Reference/source; Thorium-234, flux
    Type: Dataset
    Format: text/tab-separated-values, 4621 data points
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  • 7
    Publication Date: 2020-07-01
    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.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 39 (2012): L15610, doi:10.1029/2012GL052980.
    Description: The role of biominerals in driving carbon export from the surface ocean is unclear. We compiled surface particulate organic carbon (POC), and mineral ballast export fluxes from 55 different locations in the Atlantic and Southern Oceans. Substantial surface POC export accompanied by negligible mineral export was recorded implying that association with mineral phases is not a precondition for organic export to occur. The proportion of non-mineral associated sinking POC ranged from 0 to 80% and was highest in areas previously shown to be dominated by diatoms. This is consistent with previous estimates showing that transfer efficiency in such regions is low. However we propose that, rather than the low transfer efficiency arising from diatom blooms being inherently characterized by poorly packaged aggregates which are efficiently exported but which disintegrate readily in mid water, it is due to such environments having very high levels of unballasted organic C export.
    Description: This work is part of the lead author’s doctoral research and was supported by the CalMarO program, (E.U, grant agreement 215157) and by the U.K. Ocean 2025 program.
    Description: 2013-03-11
    Keywords: 234Th ; POC ; Ballast ; Particles export
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: text/plain
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  • 9
    Publication Date: 2021-10-15
    Description: Upwelling ocean currents associated with oxygen minimum zones (OMZs) supply nutrients fuelling intense marine productivity. Perturbations in the extent and intensity of OMZs are projected in the future, but it is currently uncertain how this will impact fluxes of redox-sensitive trace metal micronutrients to the surface ocean. Here we report seawater concentrations of Fe, Mn, Co, Cd, and Ni alongside the redox indicator iodide/iodate in the Peruvian OMZ during the 2015 El Niño event. The El Niño drove atypical upwelling of oxygen-enriched water over the Peruvian Shelf, resulting in oxidized iodine and strongly depleted Fe (II), total dissolved Fe, and reactive particulate Fe concentrations relative to non-El Niño conditions. Observations of Fe were matched by the redox-sensitive micronutrients Co and Mn, but not by non-redox-sensitive Cd and Ni. These observations demonstrate that oxygenation of OMZs significantly reduces water column inventories of redox-sensitive micronutrients, with potential impacts on ocean productivity.
    Keywords: 551 ; iron ; trace metals ; oxygen minimum zone ; El Niño ; eastern tropical south pacific ; shelf source
    Language: English
    Type: map
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  • 10
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 38 (2011): L04606, doi:10.1029/2011GL046735.
    Description: A major term in the global carbon cycle is the ocean's biological carbon pump which is dominated by sinking of small organic particles from the surface ocean to its interior. Several different approaches to estimating the magnitude of the pump have been used, yielding a large range of estimates. Here, we use an alternative methodology, a thorium isotope tracer, that provides direct estimates of particulate organic carbon export. A large database of thorium-derived export measurements was compiled and extrapolated to the global scale by correlation with satellite sea surface temperature fields. Our estimates of export efficiency are significantly lower than those derived from the f-ratio, and we estimate global integrated carbon export as ∼5 GtC yr−1, lower than most current estimates. The lack of consensus amongst different methodologies on the strength of the biological carbon pump emphasises that our knowledge of a major planetary carbon flux remains incomplete.
    Keywords: Carbon export ; Thorium-234 ; Satellite data
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: text/plain
    Format: application/pdf
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