Cycles

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 […]

May / 15 / 2020

Artificial intelligence helps investigate the oceanic zinc cycle

What explains the hitherto mysterious correlation between zinc (Zn) and silicon, an element not involved in the Zn cycle? Roshan and co-workers (2018, see reference below) used an artificial neural network (ANN, a machine learning technique inspired by biological neural systems) to produce a global climatology of dissolved Zn concentration, the first such global climatology […]

Jan / 24 / 2019

Barium isotope measurements help constraining the oceanic barium cycle

Hsieh and Henderson (2017, see reference below) propose a compilation of the oceanic barium (Ba) concentrations together with its isotopic profiles measured so far. Their review covers the main oceanic basins, comparing data obtained in the North and South Atlantic, North Pacific and the Southern Oceans. Their main conclusions are: near-surface Ba isotope values are […]

Oct / 19 / 2017

Changing the paradigm on the oceanic iron cycle

Tagliabue and co-workers (2017, see reference below) discuss an extensive review on the recent findings on iron (Fe) cycle in the ocean. They figure out clearly that: Fe is a nutrient as essential as nitrogen (N) or phosphorus (P) for the phytoplankton. In other words, the full understanding of any marine ecosystem cannot neglect the […]

Mar / 17 / 2017

The coupled zinc-silicon cycle paradox illuminated

The strong similarities between zinc (Zn) and silicon (Si) vertical profiles have led many studies to suggest the uptake of Zn in diatom frustules, followed by simultaneous remineralisation at depth. However, recent lab experiments have demonstrated that Zn, although essential for diatoms, is located in the organic part of the cell. These cells are characterized […]

Feb / 08 / 2017

Amazingly detailed compilation of the silicon cycle, with an emphasis on the oceanic silicon isotope budget

Although this article is not resulting from GEOTRACES activity, its content is definitely GEOTRACES relevant. The authors constructed an up-to-date compilation of the continental silicon (Si) cycle, including the fate of Si isotopic composition in the different continental but also estuarine and marine solid and solutions. This is a paper highly recommended by Catherine Jeandel, […]

May / 09 / 2016

New insights into global barium cycling from the first barium isotope data for seawater

A new method developed by Horner and co-workers (2015, see reference below) allows for the determination of dissolved barium (Ba) isotopic compositions in seawater using nanogram quantities of Ba. The formation of BaSO4 (barite) in open ocean seawater is largely driven by the microbial remineralization of sinking organic matter. By analysing a 4500 m depth […]

Nov / 16 / 2015

What controls the copper isotopic composition in oceanic waters?

Takano and co-workers (2014, see reference below) strongly suggest that the isotopic composition of dissolved copper (δ65Cu) in surface seawater is mainly controlled by supply from rivers, the atmosphere and deep seawater. This is the conclusion of a study involving six vertical profiles of copper (Cu) concentration and isotopes measured in the Indian (1) and […]

Dec / 19 / 2014

Field data constrain ocean mercury budget

Thanks to recent measurements during several oceanographic expeditions, among them GEOTRACES cruises, estimates of the total amount and spatial distribution of anthropogenic mercury in the global ocean were substantially improved. Global budgets of total mercury suggest that there has been a tripling of the surface water mercury content and a ~150% increase in the amount […]

Sep / 08 / 2014

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