Iron Isotopes

Oceanic Margins as sources of lithogenic particulate and dissolved iron in the North Pacific Ocean

Three GEOTRACES Japanese cruises on board the R/V Hakuho Maru allowed establishing basin-scale and full-depth sectional distributions of total dissolvable iron (tdFe), dissolved iron (dFe), and labile particulate iron (lpFe=tdFe – dFe) in the North Pacific Ocean. Zheng and Sohrin (2019, see reference below) also discuss aluminum (Al) and manganese (Mn) data in this work. […]

Mar / 10 / 2020

Unprecedented iron delivery from the Congo River margin to the South Atlantic Gyre

The Congo River is the world’s second largest river by discharge volume and the only major river discharging into an eastern boundary region. Despite of its size, the Congo River plume and its influence on trace element cycles and ocean primary productivity is poorly constrained. During GEOTRACES cruise GA08, Vieira and co-workers (2020, see reference […]

Jan / 30 / 2020

Labile particulate iron isotopic signatures trace hydrothermal and margin inputs down to the benthic layers in the Eastern Pacific Ocean

For the first time, labile and total particulate iron (pFe) isotopic signatures were measured along a full depth oceanographic section (more than 200 0.8-51 µm-sized particles) in the Eastern Pacific Ocean (GP16 East Pacific Zonal Transect cruise). Marsay and co-authors revealed that: a hydrothermal plume emanating from the South East Pacific Rise was identified as […]

Jun / 06 / 2018

What constrains the hydrothermal dissolved iron isotopic signatures?

Assessing the processes leading to dissolved iron (dFe) isotope fractionation in a hydrothermal plume is a key question, because it allows a better characterization of this specific source of dFe in the deep ocean. For the first time, Fe isotope composition of dissolved and total dissolvable Fe fractions was determined and compared to the bulk […]

Feb / 21 / 2017

Dissolved iron isotopes reveal that distinct processes are controlling this micronutrient distribution in the ocean

Abadie and co-workers propose new dissolved iron concentration and isotopic composition distributions (DFe and ICFe respectively) along the Bonus-Goodhope IPY section (GIPY4), in the Atlantic sector of the Southern Ocean. DFe vertical profiles display a continuous increase with depth (see figure B), classically interpreted as due to biological uptake at the surface followed by remineralization […]

Jan / 16 / 2017

An example of a fruitful international intercomparison

The reliability of the GEOTRACES data products including the eGEOTRACES Electronic Atlas is strongly related to the quality of the data acquired by the different laboratories contributing to this international effort. A key aspect for assessing this quality relies on the good intercomparison of the trace metal data. Iron (Fe) concentrations and moreover Fe isotopes count among […]

May / 19 / 2016

How iron isotopes offer a new window on the oceanic biogeochemical cycling of iron

Two process studies (2008 and 2012) designed to study temporal changes in the biogeochemical cycling of iron (Fe), provide in situ results for dissolved and particulate Fe (DFe and PFe) cycling during the annual spring bloom. These field data have been complemented by a shipboard 700-L mesocosm incubation experiment. Later, a conceptual model helps figuring out […]

Feb / 12 / 2015

Iron isotopes in the Equatorial Pacific Ocean: when the dissolved phases are heavier than the particulate ones

A detailed study of the dissolved and particulate iron (Fe) concentrations and isotopes off the Papua New Guinea coast is proposed. Regarding the sources, iron isotopic composition (δ56Fe) values reveal that the aerosols are heavier than the average crustal value while the sediments and river/volcano waters display δ56Fe similar to crustal values. Surprisingly, all along the […]

Jan / 16 / 2015