Paleoceanography

The role of melting-ice in driving the slowdown of circulation in the western Atlantic Ocean revealed by protactinium-thorium ratio

Abrupt climate changes in the past have been attributed to variations in Atlantic Meridional Overturning Circulation (AMOC) strength. Knowing the exact timing and magnitude of the AMOC shift is important to understand the driving mechanism of such climate variability. After a thorough selection of 13 sediment cores, the authors show that the proxy Protactinium-231-Thorium-230 (231Pa/230Th) […]

Oct / 19 / 2018

Disentangling the paleo signals brought by neodymium isotopic composition

Which paleo information are traced by the imprint neodymium isotopic signatures (εNd) in the different archives: paleo circulation or paleo erosion? The scientific debate on this issue is opened for years now. Tachikawa and co-workers (2017, see reference below) are proposing an important step forward with a thorough review of the fate of εNd in […]

Apr / 12 / 2017

Using chromium isotopes to reconstruct the oxygenation history of the oceans is challenged by modern data

Analyses of seawater chromium (Cr) concentrations and isotopes in diverse marine environments (Arctic, Pacific, and Atlantic Oceans) reveal a strong correlation between Cr isotope composition (δ53Cr) and Cr concentration. High δ53Cr values and low Cr concentration reflect losses of isotopically light Cr in neritic environments. Contrastingly, open ocean waters with low δ53Cr values and high […]

Mar / 07 / 2016

Impressive set of data reveal new features on the modern cadmium–phosphate relationship

Xie and co-authors (2015, see reference below) report vertical profiles of dissolved cadmium (Cd) in the western South Atlantic Ocean (GEOTRACES section GA02), which show nutrient-like distributions similar to those of the macronutrient phosphate (PO4). A close look at the data reveal: In the surface ocean, preferential uptake of Cd over PO4 by phytoplankton occurs […]

Jan / 25 / 2016

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