Abteilung Oberflächengewässer

Metallisotope als mögliche Proxy Indikatoren


Der biogeochemische Kreislauf von Spurenmetallen ist grundlegend mit der biologischen Produktivität verbunden, da Spurenmetalle Mikronährstoffe für das Phytoplankton sind. Aufgrund der Fraktionierung während der biologischen Aufnahme wird die Zusammensetzung der stabilen Isotope von Spurenmetallen auch von der biologischen Produktivität beeinflusst. Folglich entwickeln sich stabile Metallisotope in Sedimentaufschichten als potenzielle Instrumente zur Rekonstruktion der biologischen Produktivität in der Vergangenheit. Solche Indikatoren, so genannte Paläoproxies, helfen, die Zusammenhänge zwischen dem globalen Klima und der Biogeochemie des Oberflächenwassers in der Vergangenheit zu verstehen. Das aus Paläoproxies abgeleitete Verständnis der biogeochemischen Reaktionen auf vergangene Klimaveränderungen kann dann helfen, die Auswirkungen des aktuellen Klimawandels vorherzusagen.

Dieses Projekt stellt eine Verbindung zwischen dem modernen und dem vergangenen biogeochemischen Kreislauf von Spurenmetallen und ihren Isotopen her. Stabile Isotopensignale werden durch moderne aquatische Systeme verfolgt, von der Aufnahme in Oberflächengewässer über den Export in die Tiefe bis hin zur Sedimentation. Auf diese Weise werden die Verbindungen zwischen Isotopenaufzeichnungen in Sedimenten und dem biogeochemischen Kreislauf des Oberflächenwassers quantitativ eingegrenzt. Vielversprechende neue stabile Isotopenproxys werden dann mit bestehenden Tracern in biogenen Sedimenten verglichen. Diese Daten werden dazu beitragen, das Potenzial von stabilen Isotopen als Proxies zu bewerten, und werden die künftige Paläoproxy-Forschung zu stabilen Isotopen leiten.

Publikation

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      authors => protected'Chiu, C. F.; Archer, C.; Vance, D.; de Souza, G.&nb
         sp;F.; Ellwood, M. J.; Janssen, D. J.' (133 chars)
      title => protected'Elucidating the role of biogenic and authigenic phases in marine cycling of 
         nickel with paired dissolved and particulate nickel isotopes' (136 chars)
      journal => protected'Earth and Planetary Sciences Letters' (36 chars)
      year => protected2026 (integer)
      volume => protected681 (integer)
      issue => protected'' (0 chars)
      startpage => protected'119934 (11 pp.)' (15 chars)
      otherpage => protected'' (0 chars)
      categories => protected'nickel isotopes; particles; Southern Ocean; GEOTRACES; subtropical front; pr
         oductivity' (86 chars)
      description => protected'Nickel (Ni) is a bio-essential trace metal for marine phytoplankton, serving
          as a cofactor in key enzymes. Its nutrient-like distribution and the mirror
         ed distribution of δ<sup>60</sup>Ni in seawater suggest that δ<sup>60</sup
         >Ni could serve as a tracer of biological Ni cycling. However, particulate N
         i (pNi) remains understudied despite its important role. Here, we present th
         ree coupled dissolved and particulate δ<sup>60</sup>Ni profiles from distin
         ct biogeochemical regimes across the Subtropical Front in the Australian sec
         tor of the Southern Ocean.<br />In surface waters, pNi is isotopically light
         er than co-located dissolved Ni, and particulate Ni/P in the mixed layer fal
         ls within the range observed for phytoplankton, reflecting an association wi
         th organic matter. These results support previous studies suggesting that ph
         ytoplankton preferentially remove isotopically light Ni. In the subtropics, 
         higher surface productivity corresponds to elevated mixed layer pNi concentr
         ations, below which pNi declines, associated with the regeneration of organi
         c matter. However, particulate δ<sup>60</sup>Ni shows limited variation, im
         plying minimal isotope fractionation during this process. At subantarctic st
         ations, pNi concentrations remain relatively constant, while particulate δ<
         sup>60</sup>Ni decreases with depth in the upper 300 m. Moreover, δ<sup>60<
         /sup>Ni offsets between the dissolved and particulate phases are smaller tha
         n for the subtropical counterpart, likely associated with different phytopla
         nkton assemblages. At greater depth, particulate Mn/P increases, and Ni/P ra
         tios exceed those of phytoplankton. This suggests a shift in pNi association
          from organic-rich to Mn-rich phases, with minimal change in total particula
         te δ<sup>60</sup>Ni. These findings suggest a more complex internal cycling
          of Ni in the oceans than one driven solely by biological processes.' (1892 chars)
      serialnumber => protected'0012-821X' (9 chars)
      doi => protected'10.1016/j.epsl.2026.119934' (26 chars)
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Elucidating the role of biogenic and authigenic phases in marine cycling of nickel with paired dissolved and particulate nickel isotopes

Nickel (Ni) is a bio-essential trace metal for marine phytoplankton, serving as a cofactor in key enzymes. Its nutrient-like distribution and the mirrored distribution of δ60Ni in seawater suggest that δ60Ni could serve as a tracer of biological Ni cycling. However, particulate Ni (pNi) remains understudied despite its important role. Here, we present three coupled dissolved and particulate δ60Ni profiles from distinct biogeochemical regimes across the Subtropical Front in the Australian sector of the Southern Ocean.
In surface waters, pNi is isotopically lighter than co-located dissolved Ni, and particulate Ni/P in the mixed layer falls within the range observed for phytoplankton, reflecting an association with organic matter. These results support previous studies suggesting that phytoplankton preferentially remove isotopically light Ni. In the subtropics, higher surface productivity corresponds to elevated mixed layer pNi concentrations, below which pNi declines, associated with the regeneration of organic matter. However, particulate δ60Ni shows limited variation, implying minimal isotope fractionation during this process. At subantarctic stations, pNi concentrations remain relatively constant, while particulate δ60Ni decreases with depth in the upper 300 m. Moreover, δ60Ni offsets between the dissolved and particulate phases are smaller than for the subtropical counterpart, likely associated with different phytoplankton assemblages. At greater depth, particulate Mn/P increases, and Ni/P ratios exceed those of phytoplankton. This suggests a shift in pNi association from organic-rich to Mn-rich phases, with minimal change in total particulate δ60Ni. These findings suggest a more complex internal cycling of Ni in the oceans than one driven solely by biological processes.
Chiu, C. F.; Archer, C.; Vance, D.; de Souza, G. F.; Ellwood, M. J.; Janssen, D. J. (2026) Elucidating the role of biogenic and authigenic phases in marine cycling of nickel with paired dissolved and particulate nickel isotopes, Earth and Planetary Sciences Letters, 681, 119934 (11 pp.), doi:10.1016/j.epsl.2026.119934, Institutional Repository

Kontakt

Dr. David Janssen Tel. +41 58 765 2251 E-Mail senden
Chun Fung Chiu Tel. +41 58 765 2145 E-Mail senden

Zusammenarbeit

Prof. Dr. Derek Vance, ETH Zürich

Finanzierung

SNF Ambizione (Proposal PZ00P2_202069 / 1)