The biogeochemical ventures of dissolved iron and manganese across the Arctic Ocean

The spatial distributions and biogeochemical cycling of dissolved Fe (dFe) and dissolved manganese (dMn) across the Arctic Ocean were established during summer and fall 2015. The Canadian GEOTRACES transect extended from the Canada Basin (CB) to the Labrador Sea (LS) via the Canadian Arctic Archipelago (CAA).

The surface, subsurface and deep water distributions for both metals are controlled by i) a large variety of processes and ii) a complex balance between sources and sink (river inputs in surface, advective transports and particle remineralization at depth). For example, the highest concentrations are measured in surface waters of the CAA and the CB because these regions are strongly influenced by river inputs. Contrastingly, in the highly productive Baffin Bay and Labrador Sea, the surface waters are markedly depleted in dFe and dMn while organic matter remineralization likely acts as a notable source of these elements to deep waters.

The figure below summarizes the complexity of the processes governing the fate of these elements in the Canadian Arctic Ocean.

Figure: a) Sampled stations for Fe and Mn during the Canadian Arctic GEOTRACES cruises, bathymetry and schematic of water circulation. b) Conceptual scheme displaying the concentrations and key processes (e.g. freshwater and sedimentary inputs, remineralization and scavenging removal) controlling the distributions of dissolved Fe and Mn in the Canadian Arctic Ocean.


Colombo, M., Jackson, S. L., Cullen, J. T., & Orians, K. J. (2020). Dissolved iron and manganese in the Canadian Arctic Ocean: On the biogeochemical processes controlling their distributions. Geochimica et Cosmochimica Acta, 277, 150–174. DOI :

Latest highlights

Science Highlights

Arctic mercury export flux with marine particles higher than anticipated

In the ocean, the residence time of mercury (Hg), is largely driven by two removal mechanisms: evasion to the atmosphere and downward export flux with settling particles. The later was particularly poorly constrained in the Arctic Ocean, as was the Hg burial rate into the sediment. Using samples collected during the German GEOTRACES TransArcII (GN04) […]


Science Highlights

Land inputs in the Arctic transported up to the North Pole

A new study found that freshwater runoff from rivers and continental shelf sediments are bringing significant quantities of carbon and trace elements into parts of the Arctic Ocean


Science Highlights

Loihi Seamount, hydrothermal Helium-3 and dissolved iron sources and their dispersion within the Pacific Ocean

As part of the GEOTRACES cruise GP15, Jenkins and co-workers (2020, see reference below) observed large water column anomalies in helium isotopes and trace metal concentrations above the Loihi Seamount (~19°N, 154°W) that extends along the GP15 track for hundreds of kilometers. Expanding their data with historical ones, they observe that the Loihi Helium-3 (3He) […]


Science Highlights

Silicon isotopes reveal the different Arctic endmembers contributing to the deep water formed in the North Atlantic Ocean

Combining a multiparametric analysis, biogenic and dissolved silicon (Si) isotope data (30Si-bSiO2 and δ30Si-DSi, respectively) in the Arctic Ocean, Liguori and co-workers (2020, see reference below) could unravel the influence of water masses on the δ30Si-DSi distribution within the Arctic Ocean. Any deviation of the δ30Si-DSi signature from pure mixing was attributed to the contribution […]