Isotopes

The circulation loop in the North Atlantic and Arctic oceans depicted by the artificial radionuclides

Three articles from three cruises highlighted here! Atlantic waters have been recently recognized to play an increasing role in reducing sea-ice extent in the Arctic Ocean at a rate now comparable to losses from atmospheric thermodynamic forcing. Beyond the Arctic Ocean, the water mass transport and transformation processes in the North Atlantic Ocean substantially contribute […]

Jan / 30 / 2019

Cadmium isotopes, tracers of the cadmium sequestration as cadmium sulphide in oxygen minimum zone?

The linear relationship between the seawater cadmium and phosphate dissolved concentrations lead to use the cadmium/calcium (Cd/Ca) imprinted in calcareous archives to reconstruct the past phosphate (PO4) distributions. However, variations in the Cd/PO4 ratio between different water masses and within vertical oceanic profiles were recently identified. Among the processes that could explain these variations, sequestration […]

Jan / 07 / 2019

Local geologies imprint the Antarctic Bottom Water neodymium isotopic signatures

Dissolved neodymium (Nd) isotopes and concentrations were measured at six stations in the Australian sector of the Southern Ocean, targeting the study of the Adelie Land Bottom Water (ALBW), a variety of Antarctic Bottom Water formed off the Adélie Land coast of East Antarctica. Lambelet and co-authors (2018, see reference below) present the first dissolved […]

Dec / 11 / 2018

More realistic oceanic particle field improved the thorium-230 and protactinium-231 modeling

Thorium-230 (230Th) and protactinium-231 (231Pa) are two geochemical tracers extensively used for investigating particle transport in the ocean and reconstructing past ocean circulation. A key feature in reproducing their distributions by modelling is to understand and constrain as good as possible the scavenging processes, which means: 1) having the good adsorption-desorption kinetic rates and 2) describing […]

Dec / 10 / 2018

Helium-3 plumes in the deep Indian Ocean confirm hydrothermal activity

Thanks to samples collected as part of the Japanese GEOTRACES cruise in 2009 – 2010, along section GI04, Takahata and co-workers (2018, see reference below) identified a maximum helium-3 ratios value (δ3He >14%) at mid-depth (2000 – 3000 m) in the northern part (north of 30°S) of the central Indian Ocean, whereas lower ratio was […]

Oct / 23 / 2018

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

Environmental changes in the Arctic Ocean are occurring now!

This is what reveals the first full transarctic section of radium-228 (228Ra) in surface waters measured during Arctic cruises along GEOTRACES transects GN04 (cruise PS94) and GN01 (cruise HLY1502) proposed by Rutgers van der Loeff and colleagues (2018, see reference below). 228Ra activities in the central Arctic have increased from 2007 through 2011 to 2015 […]

Sep / 22 / 2018

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