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  • 1
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    Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait (2022)
    Details
    Publication Date: 2022-10-04
    Description: The Arctic Ocean is considered a source of micronutrients to the Nordic Seas and the North Atlantic Ocean through the gateway of Fram Strait (FS). However, there is a paucity of trace element data from across the Arctic Ocean gateways, and so it remains unclear how Arctic and North Atlantic exchange shapes micronutrient availability in the two ocean basins. In 2015 and 2016, GEOTRACES cruises sampled the Barents Sea Opening (GN04, 2015) and FS (GN05, 2016) for dissolved iron (dFe), manganese (dMn), cobalt (dCo), nickel (dNi), copper (dCu) and zinc (dZn). Together with the most recent synopsis of Arctic‐Atlantic volume fluxes, the observed trace element distributions suggest that FS is the most important gateway for Arctic‐Atlantic dissolved micronutrient exchange as a consequence of Intermediate and Deep Water transport. Combining fluxes from FS and the Barents Sea Opening with estimates for Davis Strait (GN02, 2015) suggests an annual net southward flux of 2.7 ± 2.4 Gg·a−1 dFe, 0.3 ± 0.3 Gg·a−1 dCo, 15.0 ± 12.5 Gg·a−1 dNi and 14.2 ± 6.9 Gg·a−1 dCu from the Arctic toward the North Atlantic Ocean. Arctic‐Atlantic exchange of dMn and dZn were more balanced, with a net southbound flux of 2.8 ± 4.7 Gg·a−1 dMn and a net northbound flux of 3.0 ± 7.3 Gg·a−1 dZn. Our results suggest that ongoing changes to shelf inputs and sea ice dynamics in the Arctic, especially in Siberian shelf regions, affect micronutrient availability in FS and the high latitude North Atlantic Ocean.
    Description: Plain Language Summary: Recent studies have proposed that the Arctic Ocean is a source of micronutrients such as dissolved iron (dFe), manganese (dMn), cobalt (dCo), nickel (dNi), copper (dCu) and zinc (dZn) to the North Atlantic Ocean. However, data at the Arctic Ocean gateways including Fram Strait and the Barents Sea Opening have been missing to date and so the extent of Arctic micronutrient transport toward the Atlantic Ocean remains unquantified. Here, we show that Fram Strait is the most important gateway for Arctic‐Atlantic micronutrient exchange which is a result of deep water transport at depths 〉500 m. Combined with a flux estimate for Davis Strait, this study suggests that the Arctic Ocean is a net source of dFe, dNi and dCu, and possibly also dCo, toward the North Atlantic Ocean. Arctic‐Atlantic dMn and dZn exchange seems more balanced. Properties in the East Greenland Current showed substantial similarities to observations in the upstream Central Arctic Ocean, indicating that Fram Strait may export micronutrients from Siberian riverine discharge and shelf sediments 〉3,000 km away. Increasing Arctic river discharge, permafrost thaw and coastal erosion, all consequences of ongoing climate change, may therefore alter future Arctic Ocean micronutrient transport to the North Atlantic Ocean.
    Description: Key Points: Fram Strait is the major gateway for Arctic‐Atlantic exchange of the dissolved micronutrients Fe, Mn, Co, Ni, Cu and Zn. The Arctic is a net source of dissolved Fe, Co, Ni and Cu to the Nordic Seas and toward the North Atlantic; Mn and Zn exchange are balanced. Waters of the Central Arctic Ocean, including the Transpolar Drift, are the main drivers of gross Arctic micronutrient export.
    Description: German Research Foundation
    Description: Netherlands Organization for Scientific Research
    Description: https://doi.pangaea.de/10.1594/PANGAEA.859558
    Description: https://doi.pangaea.de/10.1594/PANGAEA.871030
    Description: https://doi.pangaea.de/10.1594/PANGAEA.868396
    Description: https://doi.pangaea.de/10.1594/PANGAEA.905347
    Description: https://dataportal.nioz.nl/doi/10.25850/nioz/7b.b.jc
    Description: https://doi.pangaea.de/10.1594/PANGAEA.933431
    Description: https://www.bco-dmo.org/dataset/718440
    Description: https://doi.org/10.1594/PANGAEA.936029
    Description: https://doi.org/10.1594/PANGAEA.936027
    Description: https://doi.pangaea.de/10.1594/PANGAEA.927429
    Keywords: ddc:551.9
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 2
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    Dissolved, Labile, and Total Particulate Trace Metal Dynamics on the Northeast Greenland Shelf (2022)
    Chen, Xue‐Gang ; Krisch, Stephan ; Al‐Hashem, Ali ; [et al.]
    Details
    Publication Date: 2024-03-22
    Description: We present high‐resolution profiles of dissolved, labile, and total particulate trace metals (TMs) on the Northeast Greenland shelf from GEOTRACES cruise GN05 in August 2016. Combined with radium isotopes, stable oxygen isotopes, and noble gas measurements, elemental distributions suggest that TM dynamics were mainly regulated by the mixing between North Atlantic‐derived Intermediate Water, enriched in labile particulate TMs (LpTMs), and Arctic surface waters, enriched in Siberian shelf‐derived dissolved TMs (dTMs; Co, Cu, Fe, Mn, and Ni) carried by the Transpolar Drift. These two distinct sources were delineated by salinity‐dependent variations of dTM and LpTM concentrations and the proportion of dTMs relative to the total dissolved and labile particulate ratios. Locally produced meltwater from the Nioghalvfjerdsbræ (79NG) glacier cavity, distinguished from other freshwater sources using helium excess, contributed a large pool of dTMs to the shelf inventory. Localized peaks in labile and total particulate Cd, Co, Fe, Mn, Ni, Cu, Al, V, and Ti in the cavity outflow, however, were not directly contributed by submarine melting. Instead, these particulate TMs were mainly supplied by the re‐suspension of cavity sediment particles. Currently, Arctic Ocean outflows are the most important source of dFe, dCu, and dNi on the shelf, while LpTMs and up to 60% of dMn and dCo are mainly supplied by subglacial discharge from the 79NG cavity. Therefore, changes in the cavity‐overturning dynamics of 79NG induced by glacial retreat, and alterations in the transport of Siberian shelf‐derived materials with the Transport Drift may shift the shelf dTM‐LpTM stoichiometry in the future.
    Description: Plain Language Summary: Trace metals (TMs) including cobalt (Co), iron (Fe), manganese (Mn), copper (Cu), and nickel (Ni) are essential micronutrients for marine productivity. The Northeast Greenland shelf is a climatically sensitive region, influenced by both outflowing Arctic waters and local glacier melting. We lack knowledge on how these Arctic surface waters affect TM dynamics on the Greenland shelf and how climatic shifts may influence TM dynamics. Here, we distinguish local submarine meltwater from Arctic surface waters using distinct tracers; noble gases and radium isotopes. We show that the TM dynamics on the shelf are largely controlled by the intrusion of Arctic surface waters which creates a near‐surface plume of dissolved and labile particulate TMs. Conversely, submarine meltwater creates a subsurface plume enriched in dissolved TMs but depleted in particulate TMs, which is exported from underneath a floating ice tongue. In the future, increasing Arctic river discharge and local glacial melting may both significantly change shelf micronutrient ratios demonstrating downstream impacts of a changing cryosphere on marine biogeochemical cycles.
    Description: Key Points: The overall dissolved and particulate trace metal (TM) dynamics were mainly regulated by the mixing with Arctic surface waters. Resuspension of cavity sediments is a major localized source of labile and total particulate Cd, Co, Fe, Mn, Ni, Cu, Al, V, and Ti. Whilst dissolved and particulate TMs are mostly coupled on the Greenland shelf, cavity outflow decouples both phases.
    Description: Kuwait Institute for Scientific Research
    Description: Deutsche Forschungsgemeinschaft
    Description: https://doi.pangaea.de/10.1594/PANGAEA.871030
    Description: https://doi.pangaea.de/10.1594/PANGAEA.871030
    Description: https://doi.pangaea.de/10.1594/PANGAEA.871028
    Description: https://doi.pangaea.de/10.1594/PANGAEA.905347
    Description: https://doi.pangaea.de/10.1594/PANGAEA.933431
    Description: https://doi.pangaea.de/10.1594/PANGAEA.948466
    Description: https://doi.pangaea.de/10.1594/PANGAEA.936029
    Description: https://doi.pangaea.de/10.1594/PANGAEA.936027
    Description: https://doi.org/10.1594/PANGAEA.931336
    Keywords: ddc:551.9 ; Arctic ; trace metals ; labile particulate ; glacier ; meltwater ; GEOTRACES
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 3
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    The GEOTRACES Intermediate Data Product 2017 (2018)
    Elsevier
    In:  Chemical Geology, 493 . pp. 210-223.
    Details
    Publication Date: 2021-02-08
    Description: The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2017 consists of two parts: (1) a compilation of digital data for more than 450 TEIs as well as standard hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing an on-line atlas that includes more than 590 section plots and 130 animated 3D scenes. The digital data are provided in several formats, including ASCII, Excel spreadsheet, netCDF, and Ocean Data View collection. Users can download the full data packages or make their own custom selections with a new on-line data extraction service. In addition to the actual data values, the IDP2017 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering and for statistical analysis. Metadata about data originators, analytical methods and original publications related to the data are linked in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2017 as section plots and rotating 3D scenes. The basin-wide 3D scenes combine data from many cruises and provide quick overviews of large-scale tracer distributions. These 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of tracer plumes near ocean margins or along ridges. The IDP2017 is the result of a truly international effort involving 326 researchers from 22 countries. This publication provides the critical reference for unpublished data, as well as for studies that make use of a large cross-section of data from the IDP2017.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.chemgeo.2018.05.040
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Comment on "Do geochemical estimates of sediment focusing pass the sediment test in the equatorial Pacific?" by Lyle et al. (2007)
    AGU (American Geophysical Union)
    In:  Paleoceanography, 22 (PA1216).
    Details
    Publication Date: 2019-09-23
    Type: Article , NonPeerReviewed
    Format: text
    DOI: 10.1029/2005PA001235
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    OceanRep: Article in a Scientific Journal - without review
  • 5
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    228Ra as a tracer for shelf water in the arctic ocean (1995)
    Elsevier
    In:  Deep-Sea Research Part II-Topical Studies in Oceanography, 42 (6). pp. 1533-1553.
    Details
    Publication Date: 2016-10-10
    Description: During its formation on the vast Siberian shelves, Arctic surface water is strongly enriched in 228Ra. When 228Ra of surface samples from the Arctic interior is plotted against the river water component fr, derived from salinity, δ180 and silicate as tracers, a shelfwater end-member can be calculated by extrapolation. Highest values occur in the core of the Transpolar Drift, indicating rapid transport of surface water, comparable to the known ice-drift pattern. Low values at Ice Island T3 are explained by radioactive decay (5.8 year half-life) during the long residence time of fresh and shelf-influenced water in the Beaufort Gyre. Some evidence of decay and, consequently, prolonged transit times is also observed in the southern Nansen Basin. Future research is required to establish the seasonal, interannual and spatial variability of 228Ra on the shelves in order to determine the full potential of 228Ra as a tracer for the origin and transport rates of shelfwater in the Arctic Basin. Apart from the usual 228Ra signature of bottom waters, the tracer is also observed in intermediate layers where it gives evidence of recent contact with slope or shelf sediments. The Atlantic Inflow along the Barents slope is enriched down to 2000 m. The return flow over the Amundsen Basin and Lomonosov Ridge carries a shelf signature of 228Ra and 228Th down to more than 1200 m depth, in agreement with the enrichment observed in 137Cs. Deeper maxima around 1900–2500 m in the Nansen Basin are interpreted as inflow of bottom water from the Norwegian Sea through Fram Strait.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/0967-0645(95)00053-4
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Silica cycle in surface sediments of the South Atlantic (1998)
    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 45 (7). pp. 1085-1109.
    Details
    Publication Date: 2019-07-02
    Description: Production of biogenic silica and dissolution processes in the water column and surface sediment are important aspects for the investigation and reconstruction of present and past productivity of the ocean. Although the geological record of biogenic silica is often used as a proxy for paleoceanographic processes in the Southern Ocean, little is known about the present regional distribution of biogenic silica flux and accumulation and their relation to primary production in surface waters. Based on more than 130 sediment and pore water samples, the regional differences of the biogenic silica flux to the sea floor of the southern South Atlantic were investigated. In contrast to biogenic silica content, the dissolved Si-flux through the sediment/water interface, caused by intense dissolution of BSi in surface sediments, reflects biogenic production in surface waters. This was inferred by observed increases of Si-fluxes in regions of recurrent polynya formation or in the vicinity of Marginal Ice Zones as at the Weddell-Scotia Sea boundary. In the Scotia Sea, where no benthic fluxes were reported before, we found a considerable burial of biogenic silica and biogenic silica fluxes to the sea floor of ∼800–1300 mmol m-2 a-1. This is a significantly higher flux than derived for the known opal accumulation area in the SE Atlantic, further to the east in the Antarctic Circumpolar Current, where a flux of ∼600–767 mmol m-2 a-1 was observed. This shows that the Scotia Sea is not a gap within the Circumpolar Antarctic Opal Belt as previously assumed. The geochemical budget for different sub-regions of the South Atlantic was considered by a Geographic Information System. In contrast to most previous attempts, this ensures the accurate consideration of the spatial distribution of sampling sites, a crucial aspect for the accuracy of geochemical budgets. For the South Atlantic we calculated the flux of biogenic silica to the sea floor as ∼5.1×1012 mol a-1. Only ∼0.84×1012 mol a-1 is buried in these sediments, which is considerably less than previous estimates.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0967-0637(98)00006-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Dissolved, labile and total particulate trace metal dynamics on the northeast Greenland Shelf (2022)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: We present high-resolution profiles of dissolved, labile and total particulate trace metals (TMs) on the Northeast Greenland shelf from GEOTRACES cruise GN05 in August 2016. Combined with radium isotopes, stable oxygen isotopes, and noble gas measurements, elemental distributions suggest that TM dynamics were mainly regulated by the mixing between North Atlantic-derived Intermediate Water, enriched in labile particulate TMs (LpTMs), and Arctic surface waters, enriched in Siberian shelf-derived dissolved TMs (dTMs; Co, Cu, Fe, Mn, and Ni) carried by the Transpolar Drift. These two distinct sources were delineated by salinity-dependent variations of dTM and LpTM concentrations and the proportion of dTMs relative to the total dissolved and labile particulate ratios. Locally produced meltwater from the Nioghalvfjerdsbræ (79NG) glacier cavity, distinguished from other freshwater sources using helium excess, contributed a large pool of dTMs to the shelf inventory. Localized peaks in labile and total particulate Cd, Co, Fe, Mn, Ni, Cu, Al, V, and Ti in the cavity outflow, however, were not directly contributed by submarine melting. Instead, these particulate TMs were mainly supplied by the re-suspension of cavity sediment particles. Currently, Arctic Ocean outflows are the most important source of dFe, dCu and dNi on the shelf, while LpTMs and up to 60% of dMn and dCo are mainly supplied by subglacial discharge from the 79NG cavity. Therefore, changes in the cavity-overturning dynamics of 79NG induced by glacial retreat, and alterations in the transport of Siberian shelf-derived materials with the Transport Drift may shift the shelf dTM-LpTM stoichiometry in the future. Key Points The overall dissolved and particulate trace metal dynamics were mainly regulated by the mixing with Arctic surface waters Resuspension of cavity sediments is a major localized source of labile and total particulate Cd, Co, Fe, Mn, Ni, Cu, Al, V, and Ti Whilst dissolved and particulate trace metals are mostly coupled on the Greenland shelf, cavity outflow decouples both phases
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    The 79°N Glacier cavity modulates subglacial iron export to the NE Greenland Shelf (2021)
    Nature Research
    Details
    Publication Date: 2024-02-07
    Description: Approximately half of the freshwater discharged from the Greenland and Antarctic Ice Sheets enters the ocean subsurface as a result of basal ice melt, or runoff draining via the grounding line of a deep ice shelf or marine-terminating glacier. Around Antarctica and parts of northern Greenland, this freshwater then experiences prolonged residence times in large cavities beneath floating ice tongues. Due to the inaccessibility of these cavities, it is unclear how they moderate the freshwater associated supply of nutrients such as iron (Fe) to the ocean. Here, we show that subglacial dissolved Fe export from Nioghalvfjerdsbrae (the ‘79°N Glacier’) is decoupled from particulate inputs including freshwater Fe supply, likely due to the prolonged ~162-day residence time of Atlantic water beneath Greenland’s largest floating ice-tongue. Our findings indicate that the overturning rate and particle-dissolved phase exchanges in ice cavities exert a dominant control on subglacial nutrient supply to shelf regions.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    Format: text
    Format: other
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Arctic – Atlantic exchange of the dissolved micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc with a focus on Fram Strait (2022)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: The Arctic Ocean is considered a source of micronutrients to the Nordic Seas and the North Atlantic Ocean through the gateway of Fram Strait. However, there is a paucity of trace element data from across the Arctic Ocean gateways, and so it remains unclear how Arctic and North Atlantic exchange shapes micronutrient availability in the two ocean basins. In 2015 and 2016, GEOTRACES cruises sampled the Barents Sea Opening (GN04, 2015) and Fram Strait (GN05, 2016) for dissolved iron (dFe), manganese (dMn), cobalt (dCo), nickel (dNi), copper (dCu) and zinc (dZn). Together with the most recent synopsis of Arctic-Atlantic volume fluxes, the observed trace element distributions suggest that Fram Strait is the most important gateway for Arctic-Atlantic dissolved micronutrient exchange as a consequence of Intermediate and Deep Water transport. Combining fluxes from Fram Strait and the Barents Sea Opening with estimates for Davis Strait (GN02, 2015) suggests an annual net southward flux of 2.7 ± 2.4 Gg·a-1 dFe, 0.3 ± 0.3 Gg·a-1 dCo, 15.0 ± 12.5 Gg·a-1 dNi and 14.2 ± 6.9 Gg·a-1 dCu from the Arctic towards the North Atlantic Ocean. Arctic-Atlantic exchange of dMn and dZn were more balanced, with a net southbound flux of 2.8 ± 4.7 Gg·a-1 dMn and a net northbound flux of 3.0 ± 7.3 Gg·a-1 dZn. Our results suggest that ongoing changes to shelf inputs and sea ice dynamics in the Arctic, especially in Siberian shelf regions, affect micronutrient availability in Fram Strait and the high latitude North Atlantic Ocean.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Radionuclides from sediment trap Bouvet_1 (2006)
    PANGAEA
    Details
    Publication Date: 2023-03-16
    Keywords: Alpha spectrometry; ANT-IX/2; AWI_MarGeoChem; AWI_Paleo; BO1_trap; Bouvet_1; Bouvet Island, Southern Ocean (Atlantic sector); Calculated; DATE/TIME; Date/time end; DEPTH, water; Duration, number of days; Marine Geochemistry @ AWI; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; Protactinium-231; Protactinium-231, standard deviation; Protactinium-231/Thorium-230 excess; Protactinium-231/Thorium-230 excess, standard deviation; Protactinium-231 excess; Protactinium-231 excess, standard deviation; PS18 06AQANTIX_2; Sample code/label; Thorium-230; Thorium-230, standard deviation; Thorium-230 excess; Thorium-230 excess, standard deviation; Thorium-232; Thorium-232, standard deviation; Total mass, flux per day; Trap, sediment; TRAPS
    Type: Dataset
    Format: text/tab-separated-values, 132 data points
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    DATA PANGAEA
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