Nutrient Distribution in East Antarctic Summer Sea Ice: A Potential Iron Contribution From Glacial Basal Melt

Duprat, Luis P. A. M.; Corkill, Matthew; Genovese, Cristina; Townsend, Ashley T.; Moreau, Sébastien; Meiners, Klaus M.; Lannuzel, Delphine

doi:10.1029/2020jc016130

Cited by 19 publications

(29 citation statements)

References 122 publications

(197 reference statements)

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“…The factors that control exchange of Fe, and other trace elements, between glacier-derived particulate and dissolved phases (Lippiatt et al, 2010;Thuroczy et al, 2012;Ardiningsih et al, 2020) and how such exchanges are moderated by physical and chemical processes around the ice sheet peripheries, are less well understood (Sherrell et al, 2015;Annett et al, 2017;St-Laurent et al, 2017). These coastal dynamics may contribute to regional differences in dissolved trace metal availability in the marine environment (Marsay et al, 2017;Dinniman et al, 2020;Duprat et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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Around 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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…Sea-ice cores were collected off the East Antarctic coast during 3 field campaigns (Figure 1): the Sea Ice Physics and Ecosystem eXperiment-2 (SIPEX-2; a voyage conducted during the austral winter-spring 2012 transition; Meiners et al, 2016), the Davis time series (conducted in late spring 2015; Duprat et al, 2019), and the Aurora Australis Voyage-2 (AAV2; carried out in summer 2016-2017; Duprat et al, 2020). Ice cores for SIPEX-2 were collected at 6 different locations within first-year pack ice (64-65.1 S, 116-121.1 E) between September 26 and November 10, 2012.…”

Section: Sampling Sitesmentioning

confidence: 99%

“…Sampling sites were selected away and upwind from the study vessel (SIPEX-2 and AAV2) and research station (Davis). Additional information about the sampling sites can be found in Duprat et al (2019), Lim et al (2019), andDuprat et al (2020).…”

Section: Sampling Sitesmentioning

confidence: 99%

“…The thickness of sea ice and snow was measured at each site. Other standard physicochemical and biological parameters, including in situ ice temperature; bulk salinity; the concentrations of Chla, the macronutrients nitrate (NO 3 -), nitrite (NO 2 -), phosphate (PO 4 3-), silicic acid (Si(OH) 4 ), and ammonium (NH 4 þ ); and particulate organic carbon (POC) and nitrogen (PON), were also determined for each sample following the methods described in Duprat et al (2020).…”

Section: Physicochemical and Biological Parametersmentioning

confidence: 99%

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Spatial and seasonal distribution of dissolved and particulate bioactive metals in Antarctic sea ice

Duprat

Townsend

Merwe

et al. 2021

Elementa: Science of the Anthropocene

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Iron (Fe) has been shown to limit growth of marine phytoplankton in the Southern Ocean, regulating phytoplankton productivity and species composition, yet does not seem to limit primary productivity in Antarctic sea ice. Little is known, however, about the potential impact of other metals in controlling sea-ice algae growth. Here, we report on the distribution of dissolved and particulate cadmium (Cd), cobalt (Co), copper (Cu), manganese (Mn), nickel (Ni), and zinc (Zn) concentrations in sea-ice cores collected during 3 Antarctic expeditions off East Antarctica spanning the winter, spring, and summer seasons. Bulk sea ice was generally enriched in particulate metals but dissolved concentrations were similar to the underlying seawater. These results point toward an environment controlled by a subtle balance between thermodynamic and biological processes, where metal availability does not appear to limit sea-ice algal growth. Yet the high concentrations of dissolved Cu and Zn found in our sea-ice samples raise concern about their potential toxicity if unchelated by organic ligands. Finally, the particulate metal-to-phosphorus (P) ratios of Cu, Mn, Ni, and Zn calculated from our pack ice samples are higher than values previously reported for pelagic marine particles. However, these values were all consistently lower than the sea-ice Fe:P ratios calculated from the available literature, indicating a large accumulation of Fe relative to other metals in sea ice. We report for the first time a P-normalized sea-ice particulate metal abundance ranking of Fe >> Zn ≈ Ni ≈ Cu ≈ Mn > Co ≈ Cd. We encourage future sea-ice work to assess cellular metal quotas through existing and new approaches. Such work, together with a better understanding of the nature of ligand complexation to different metals in the sea-ice environment, would improve the evaluation of metal bioavailability, limitation, and potential toxicity to sea-ice algae.

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“…The major part of the Southern Ocean is considered a high-nutrient and low-chlorophyll (HNLC) area, primarily due to the limitation of micronutrients, such as iron (Fe) [ 54 ]. Nevertheless, phytoplankton may bloom if Fe is available and if light and mixing conditions are suitable.…”

Section: Microalgaementioning

confidence: 99%

Physiological and Molecular Responses to Main Environmental Stressors of Microalgae and Bacteria in Polar Marine Environments

et al. 2020

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The Arctic and Antarctic regions constitute 14% of the total biosphere. Although they differ in their physiographic characteristics, both are strongly affected by snow and ice cover changes, extreme photoperiods and low temperatures, and are still largely unexplored compared to more accessible sites. This review focuses on microalgae and bacteria from polar marine environments and, in particular, on their physiological and molecular responses to harsh environmental conditions. The data reported in this manuscript show that exposure to cold, increase in CO2 concentration and salinity, high/low light, and/or combination of stressors induce variations in species abundance and distribution for both polar bacteria and microalgae, as well as changes in growth rate and increase in cryoprotective compounds. The use of -omics techniques also allowed to identify specific gene losses and gains which could have contributed to polar environmental adaptation, and metabolic shifts, especially related to lipid metabolism and defence systems, such as the up-regulation of ice binding proteins, chaperones and antioxidant enzymes. However, this review also provides evidence that -omics resources for polar species are still few and several sequences still have unknown functions, highlighting the need to further explore polar environments, the biology and ecology of the inhabiting bacteria and microalgae, and their interactions.

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Nutrient Distribution in East Antarctic Summer Sea Ice: A Potential Iron Contribution From Glacial Basal Melt

Cited by 19 publications

References 122 publications

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

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

Spatial and seasonal distribution of dissolved and particulate bioactive metals in Antarctic sea ice

Physiological and Molecular Responses to Main Environmental Stressors of Microalgae and Bacteria in Polar Marine Environments

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