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

Science Highlights

Thorium-Protactinium fate across the tropical Atlantic Ocean: what reveals the water column-sediment coupling

Twenty seawater profiles and twenty core-top 231-protactinium and 230-thorium analyses were realised by Ng and colleagues along five depth transects across the northern tropical Atlantic open ocean.


Science Highlights

Constraining Oceanic Copper Cycling through Artificial Intelligence and Ocean Circulation Inverse Model

Using available observations of dissolved copper, artificial neural networks, and an ocean circulation inverse model, authors calculated a global estimate of the 3-dimensional distribution and cycling of dissolved copper in the ocean


Science Highlights

Particulate rare earth elements distributions, processes and characterisation of nepheloids in the North Atlantic

Lagarde et al. realised the first basin scale section of particulate rare earth elements concentrations across the North Atlantic Ocean.


Science Highlights

Isopycnal mixing controls protactinium and thorium distributions in the Pacific Southern Ocean

Pavia and co-workers determined the physical and chemical speciation as well as the vertical distribution of Protactinium-231 and Thorium-230 at 12 stations across the Southern Pacific Antarctic Circumpolar Current…