Trace Element (Fe, Co, Ni and Cu) Dynamics Across the Salinity Gradient in Arctic and Antarctic Glacier Fjords

dc.contributor.authorKrause, Jana
dc.contributor.authorHopwood, Mark J.
dc.contributor.authorHöfer, Juan
dc.contributor.authorKrisch, Stephan
dc.contributor.authorAchterberg, Eric P.
dc.contributor.authorAlarcón, Emilio
dc.contributor.authorCarroll, Dustin
dc.contributor.authorGonzález, Humberto E.
dc.contributor.authorJuul-Pedersen, Thomas
dc.contributor.authorLiu, Te
dc.contributor.authorLodeiro, Pablo
dc.contributor.authorMeire, Lorenz
dc.contributor.authorRosing, Minik T.
dc.description.abstractAround the Greenlandic and Antarctic coastlines, sediment plumes associated with glaciers are significant sources of lithogenic material to the ocean. These plumes contain elevated concentrations of a range of trace metals, especially in particle bound phases, but it is not clear how these particles affect dissolved (<0.2 µm) metal distributions in the ocean. Here we show, using transects in 8 glacier fjords, trends in the distribution of dissolved iron, cobalt, nickel and copper (dFe, dCo, dNi, dCu). Following rapid dFe loss close to glacier outflows, dFe concentrations in particular showed strong similarities between different fjords. Similar dFe concentrations were also observed between seasons/years when Nuup Kangerlua (SW Greenland) was revisited in spring, mid- and late-summer. Dissolved Cu, dCo and dNi concentrations were more variable and showed different gradients with salinity depending on the fjord, season and year. The lack of consistent trends for dCu and dNi largely reflects less pronounced differences contrasting the concentration of inflowing shelf waters with fresher glacially-modified waters. Particles also made only small contributions to total dissolvable Cu (dCu constituted 83 ± 28% of total dissolvable Cu) and Ni (dNi constituted 86 ± 28% of total dissolvable Ni) within glacier plumes. For comparison, dFe was a lower fraction of total dissolvable Fe; 3.5 ± 4.8%. High concentrations of total dissolvable Fe in some inner-fjord environments, up to 77 µM in Ameralik (SW Greenland), may drive enhanced removal of scavenged type elements, such as Co. Further variability may have been driven by local bedrock mineralogy, which could explain high concentrations of dNi (25-29 nM) and dCo (6-7 nM) in one coastal region of west Greenland (Kangaatsiaq). Our results suggest that dissolved trace element distributions in glacier fjords are influenced by a range of factors including: freshwater concentrations, local geology, drawdown by scavenging and primary production, saline inflow, and sediment dynamics. Considering the lack of apparent seasonality in dFe concentrations, we suggest that fluxes of some trace elements may scale proportionately to fjord overturning rather than directly to freshwater discharge flux.
dc.description.sponsorshipAntarctic sampling was possible through FONDAP-IDEAL 15150003. JH was supported by FONDECYT-Regular 1211338. MH received support from the DFG (award number HO 6321/1- 1), INTERACT (European Union Horizon 2020, grant 730938) and from the GLACE project, organised by the Swiss Polar Institute and supported by the Swiss Polar Foundation. LM was funded by research programme VENI with project number 016.Veni.192.150, which is financed by the Dutch Research Council (NWO). Ship time and work in Nuup Kangerlua was conducted in collaboration with MarineBasis-Nuuk, part of the Greenland Ecosystem Monitoring project (GEM). We gratefully acknowledge contributions from the Danish Centre for Marine Research (DCH), Greenland Institute of Natural Resources, Novo Nordic Foundation (NNF17SH0028142) and the Instituto Antártico Chileno (INACH) for their logistical support.
dc.publisherFrontiers Media
dc.relation.isformatofReproducció del document publicat a:
dc.relation.ispartofFrontiers In Earth Science, 2021, vol. 9, article 725279
dc.rightscc-by (c) Krause et al., 2021
dc.titleTrace Element (Fe, Co, Ni and Cu) Dynamics Across the Salinity Gradient in Arctic and Antarctic Glacier Fjords
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