Coupling and decoupling of barium and radium-226 along the GEOVIDE GEOTRACES section

Because radium-226 (226Ra) and barium (Ba) are both alkaline earth metals and thus display similar chemical behaviours, studying their fate in contrasting environments is of prime interest. With this aim, Le Roy and co-workers (2018, see reference below) realised a high-resolution description of the distribution of these tracers along the GEOVIDE section (GA01, see section map here). Using an optimum multi-parameter analysis of their data, they figured out that:

– both tracers can be considered as conservative of water mass transport in the deep open ocean part of the section;

– non conservative and decoupled behaviours are observed at the ocean boundaries, namely:

  • in the eastern part of the section, the deepest waters (North East Atlantic Deep Water) display high Ba and 226Ra concentrations, which could reflect either an accumulation in this “old” water mass or diffusion from the sediment below;
  • contrastingly, depletion of both tracers in the upper layers of the West European basin likely reflects biological stripping;
  • at the land-ocean contact, as for example close to the Greenland and Newfoundland coasts, marked decoupled behaviours reflect the different main input sources of both tracers (rivers for Ba, sediment for 226Ra).


Figure:
Distribution of dissolved 226Ra/Ba ratio (a) measured along the GEOVIDE section and the difference between the measured concentrations and those calculated by the optimum multiparameter (OMP) analysis for 226Ra (b), Ba (c) and  226Ra/Ba ratio (d) along the GA01 section. Positive anomalies (in Red) reflect recent tracer addition, while negative ones (in blue) reflect recent tracer removal. Station numbers are found above the panels. Click here to view the figure larger.

Reference:

Le Roy, E., Sanial, V., Charette, M. A., van Beek, P., Lacan, F., Jacquet, S. H. M., Henderson, P. B., Souhaut, M,. García-Ibáñez, Maribel I., Jeandel, C.,Pérez, F., F., Sarthou, G. (2018). 226Ra–Ba relationship in the North Atlantic during GEOTRACES-GA01. Biogeosciences, 15(9), 3027–3048. http://doi.org/10.5194/bg-15-3027-2018

 

Latest highlights

Science Highlights

Extremely high radioactive levels in the manganese nodules

Volz and co-authors demonstrate that radioisotopes in the manganese nodules mostly exceed exempt activity levels…

22.05.2023

Science Highlights

The North Pacific Ocean, a key actor for the zinc oceanic cycle

Sieber and his colleagues lift the veil on some of the mechanisms that control the behavior of zinc in the Pacific Ocean, and more globally.

17.05.2023

Science Highlights

Disentangling what controls the cadmium distribution in the Pacific Ocean

Sieber and his colleagues established the distribution of dissolved cadmium concentrations and isotopes a section from Alaska to Tahiti.

16.05.2023

Science Highlights

Solid-solution distribution of the cosmogenic beryllium-7 in the water column

This work questions the validity and limits of the hypothesis that particulate beryllium-7 can be neglected in the oceanographic applications of this tracer.

12.05.2023

Rechercher