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. Results emphasize a major contribution of lithogenic material to the Fe budget of this area. More specifically, they identify i) a clear correlation between labile particulate iron and labile particulate Al, with a ratio of 0.544 largely above the Fe/Al crustal ratio and ii) that the dFe is strongly enriched in the northern part of the North Pacific. Both relationships are shown on the Figure 1. Figure 2 emphasizes the impact of these margin inputs for the dFe concentrations at 1000 m for the whole North Pacific. The authors estimate a total inventory for tdFe and dFe in this area equal to 1.1×1012 mol and 2.8×1011 mol respectively. The difference of 8.2×1011 mol equates to the amount of lpFe. This first inventory of observed Fe fractions in the North Pacific reveals the potential importance of lpFe in the ocean iron cycle which may have been underestimated as a source of bioavailable so far.


Zheng, L., & Sohrin, Y. (2019). Major lithogenic contributions to the distribution and budget of iron in the North Pacific Ocean. Scientific Reports, 9(1), 11652. https://doi.org/10.1038/s41598-019-48035-1

Latest highlights

Breaking down disciplinary silos in marine sciences, a key to climate forecasting

Alessandro Tagliabue exposes how ocean modelling must evolve to take the biological complexity of the surface ocean into account.

Challenging results on iron bioavailability in the Southern Ocean

Fourquez and co-authors conducted dissolved iron uptake experiments with Phaeocystis antarctica…

Lead isotopes allow tracing the processes injecting of anthropogenic lead in deep waters

This work follows the penetration of anthropogenic lead (traced using its isotopic signatures) into the pristine deep Pacific Ocean.

Protactinium-231 budget of the Atlantic sector of Southern Ocean

Levier and colleagues analysed dissolved and particulate protactinium-231 in samples collected in a section in the Southern Ocean…