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 below) used radium isotopes to demonstrate that a combination of high river discharge, coastal sediments or submarine groundwater discharge make the Congo the most significant riverine source of iron (Fe) to the South Atlantic. Rapid off-shelf transport close to the equator results in the delivery of extremely high fluxes of trace elements from the Congo River outflow into the Southeast Atlantic Ocean. This large trace element input relieves micro-nutrient limitation (iron and cobalt) across the eastern South Atlantic and provides an unusual example of a very efficient riverine Fe source.

20 Vieira l

Figure: Comparison of dissolved iron (dFe) concentrations vs. distance from the river mouth in other riverine systems globally. The presence of dFe several hundreds of kilometres off-shelf indicates more rapid horizontal mixing of the river plume compared to other systems. TPD indicates Transpolar Drift, and NY Bight indicates New York Bight.

Reference:

Vieira, L. H., Krisch, S., Hopwood, M. J., Beck, A. J., Scholten, J., Liebetrau, V., & Achterberg, E. P. (2020). Unprecedented Fe delivery from the Congo River margin to the South Atlantic Gyre. Nature Communications, 11(1), 556. DOI: https://doi.org/10.1038/s41467-019-14255-2

Latest highlights

Science Highlights

New trace metal data in the Seas of Japan and Okhotsk

Nakaguchi and colleagues realized full-depth and section distributions of traces metals collected from the Seas of Japan and Okhotsk.

24.05.2022

Science Highlights

The Arctic Ocean is a net source of micronutrients toward the North Atlantic through the gateway of Fram Strait

Krisch and colleagues present a flux budget for micronutrient exchange between the Arctic and the North Atlantic Ocean.

18.05.2022

Science Highlights

Confrontation of two models to constrain the hydrothermal iron contribution to the Southern Ocean export production

Tagliabue and his co-workers compare the hydrothermal dissolved iron simulated by both models.

11.05.2022

Science Highlights

A better insight into parameters that control particle flux in the ocean

Xiang and coworkers compiled full ocean-depth size-fractionated particle data from 3 recent U.S. GEOTRACES cruises.

10.05.2022

Rechercher