Canadian Arctic Archipelago Shelf‐Ocean Interactions: A Major Iron Source to Pacific Derived Waters Transiting to the Atlantic

Colombo, Manuel; Rogalla, Birgit; Li, Jingxuan; Allen, Susan E.; Orians, Kristin J.; Maldonado, María T.

doi:10.1029/2021gb007058

Cited by 16 publications

(30 citation statements)

References 78 publications

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“…Our calculations suggest Davis Strait is an additional gateway for transport of dFe, dMn, labile dCo, dNi, dCu and dZn from the Arctic to the North Atlantic Ocean (Table 2). Surface Water, including contributions from freshwater and sediment sources in the Canadian Arctic Archipelago (Colombo et al, 2020(Colombo et al, , 2021, was the dominant component in the water column and comprised ∼80% of dFe, ∼94% of dMn, ∼85% of dCo, dNi and dCu and ∼74% of dZn fluxes across Davis Strait.…”

Section: Arctic-atlantic Flux Estimatesmentioning

confidence: 99%

Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait

Krisch

Hopwood

Roig

et al. 2022

Global Biogeochemical Cycles

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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. Plain Language SummaryRecent 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.

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Section: Arctic-atlantic Flux Estimatesmentioning

confidence: 99%

Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait

Krisch

Hopwood

Roig

et al. 2022

Global Biogeochemical Cycles

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“…As has been previously postulated, the Barents Shelf is less productive and may be too deep to generate a significant benthic trace metal source (Jensen et al., 2019; Sakshaug, 2004). Sediment resuspension, rather than reductive dissolution, has been linked to Fe and Mn benthic fluxes along the CAA (Colombo et al., 2021), but this apparently did not meaningfully affect Cu and Ni, which shared no relationship to other dissolved trace metals in the CAA. The dominant feature in the CAA appeared to be the high dissolved Cu and Ni concentrations in the Canada Basin UHL waters that flow through the CAA and out into Baffin Bay.…”

Section: Resultsmentioning

confidence: 99%

A Refinement of the Processes Controlling Dissolved Copper and Nickel Biogeochemistry: Insights From the Pan‐Arctic

et al. 2022

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Recent studies, including many from the GEOTRACES program, have expanded our knowledge of trace metals in the Arctic Ocean, an isolated ocean dominated by continental shelf and riverine inputs. Here, we report a unique, pan‐Arctic linear relationship between dissolved copper (Cu) and nickel (Ni) present north of 60°N that is absent in other oceans. The correlation is driven primarily by high Cu and Ni concentrations in the low salinity, river‐influenced surface Arctic and low, homogeneous concentrations in Arctic deep waters, opposing their typical global distributions. Rivers are a major source of both metals, which is most evident within the central Arctic's Transpolar Drift. Local decoupling of the linear Cu‐Ni relationship along the Chukchi Shelf and within the Canada Basin upper halocline reveals that Ni is additionally modified by biological cycling and shelf sediment processes, while Cu is mostly sourced from riverine inputs and influenced by mixing. This observation highlights differences in their chemistries: Cu is more prone to complexation with organic ligands, stabilizing its riverine source fluxes into the Arctic, while Ni is more labile and is dominated by biological processes. Within the Canadian Arctic Archipelago, an important source of Arctic water to the Atlantic Ocean, contributions of Cu and Ni from meteoric waters and the halocline are attenuated during transit to the Atlantic. Additionally, Cu and Ni in deep waters diminish with age due to isolation from surface sources, with higher concentrations in the younger Eastern Arctic basins and lower concentrations in the older Western Arctic basins.

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“…Dissolved Mn increases near the ocean floor in the Canadian Arctic by sediment resuspension (non-reductive dissolution; Colombo et al, 2020). While reductive dissolution is important over the Chukchi Shelf regions (Vieira et al, 2019), we did not include sediment diffusion as reducing conditions in the sediments are not prevalent in the CAA (Colombo et al, 2021;Lehmann et al, 2022). The northern and western model boundary conditions from the global Mn model (Van Hulten et al, 2017) may account for some inflow of reduced Mn from the Chukchi shelves, as the global model includes sediment diffusion.…”

Section: Sediment Resuspension Over the Continental Shelfmentioning

confidence: 99%

“…The relative importance of river runoff and sea ice depends in part on the distance from the source and internal cycling within the ocean (Fichot et al, 2013). The narrow and shallow systems of channels of the CAA are in close contact with the land-ocean interface and are more directly impacted by boundary processes such as river discharge and sedimentary inputs (Colombo et al, 2021). Comparatively, the Canada Basin is distant from land, and we expect the prevalence of boundary sources such as river discharge and sedimentary inputs to be diminished.…”

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confidence: 99%

Sediments in sea ice drive the Canada Basin surface Mn maximum: insights from an Arctic Mn ocean model

Rogalla

Allen

Colombo

et al. 2021

Preprint

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Canadian Arctic Archipelago Shelf‐Ocean Interactions: A Major Iron Source to Pacific Derived Waters Transiting to the Atlantic

Cited by 16 publications

References 78 publications

Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait

Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait

A Refinement of the Processes Controlling Dissolved Copper and Nickel Biogeochemistry: Insights From the Pan‐Arctic

Sediments in sea ice drive the Canada Basin surface Mn maximum: insights from an Arctic Mn ocean model

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