First direct measurement of actinium (but also radium and thorium) distribution coefficient values in marine sediments
Actinium-227, radium-226 and radium-228 profiles in sediments were measured and modeled at 5 stations in the Northeast Pacific…
Thorium
Intense benthic nepheloid layers in the Northwest Atlantic Ocean lead to unexpected distributions of dissolved and particulate thorium-230 and protactinium-231
Chen and colleagues explore the behaviour of thorium-230 and protactinium-231 in the benthic nepheloid layers…
A new and more quantitative atlas of the deep-sea burial fluxes of major and trace elements
Among other findings, authors find that the new opal flux is roughly a factor of two increase over previous estimates having important implications for the global silicon cycle.
Variable dissolution rates and fates of lithogenic tracers at the air-sea interface
Roy-Barman and co-authors established the dissolution rates from Saharan dust reaching Mediterranean seawater.
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.
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…
Surface water trace element and isotope data challenge dust flux models
Using measurements of dissolved and particulate thorium-230 and thorium-232 along a section across the South Pacific, authors estimated the dust flux over this remote area
Particulate fluxes and circulation in a changing Arctic Ocean: tracer data and modeling
A complete review of published and new water column profiles of thorium-230 (230Th) and protactinium-231 (231Pa) concentrations and neodymium (Nd) isotopic compositions collected in the Amerasian Basin of the Arctic […]
South Pacific particulate organic carbon fate challenges Martin’s Law
Joint Science Highlight with US-Ocean Carbon & Biogeochemistry (OCB). Carbon storage in the ocean is sensitive to the depths at which particulate organic carbon (POC) is respired back to CO2 […]
Using the three thorium isotope toolbox to probe the particle dynamic within an East Pacific Rise hydrothermal plume
The insoluble radiogenic isotopes of thorium (Th) are produced at a known rate in the water column via the decay of soluble uranium (234Th, 230Th) and radium (228Th) isotopes. These […]
Important spatial variation of the Particulate Organic Carbon export along the GEOVIDE section in the North Atlantic Ocean
Based on the thorium-234 (234Th) isotopes and the Particulate Organic Carbon/Thorium (POC/Th) ratios measured in small and large particles collected at 11 stations along the GEOVIDE section (GA01) using in […]
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 […]
Ever wonder how long your favourite element remains in the ocean before it’s gone again?
This timeframe, sometimes called a residence time, ranges from decades for the most reactive trace elements to millions of years for the most unreactive elements such as the major components […]
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 […]
Influence of particle composition on the rate constants of thorium adsorption
Chemical species are constantly exchanged between seawater (solution, D) and particles (solid material, P). This continuous D-P exchange is a key process determining the chemical composition of the ocean. Particles […]
High particulate organic carbon export in the Arabian Sea
In the framework of Indian GEOTRACES cruise GI02, high-resolution sampling was carried out in the Arabian Sea and the Indian Ocean during April–May 2014. The first 234Th-based carbon export flux […]
Astonishing protactinium and thorium profiles in the Mediterranean Sea
In the framework of the GEOTRACES cruise along the GA04 section in the Meditterranean Sea, Gdaniec et al. (2018, see reference below) measured thorium (Th) and protactinium (Pa) isotope distributions […]
Contrasting lithogenic inputs from North Atlantic to North Pacific Oceans traced by thorium isotopes
Dissolved thorium (Th) isotopes and iron (Fe) are used to document the transfer of lithogenic material to the ocean. Two contrasting areas are compared: the Atlantic Ocean around Barbados Islands, […]
Inference about rates of thorium and particle cycling in the ocean water column
Insoluble thorium (Th) isotopes are particle reactive while their radioactive parents are fairly soluble. This difference of behaviour has allowed chemical oceanographers to use Th isotopes to develop understanding about […]
Insights into Particle Cycling from Thorium and Particle Data
Phoebe Lam and Olivier Marchal (2015, see reference below) propose to describe, with the same model, the dynamics of particles in the oceanic water column and its effects –on four […]
Long-lived thorium isotopes: powerful tools to estimate lithogenic fluxes to the ocean
Hayes and co-workers are back with another rich contribution, based on dissolved thorium-232 (232Th) and thorium-230 (230Th) (click here to access previous highlight from the same author). The game is […]
New revelations on boundary scavenging in the North Pacific
Thorium (Th) and protactinium (Pa) are very efficient tracers of particle dynamics in the ocean. More particularly, their relative distributions inform on the intensity of “scavenging”, in other words, the […]
The power of tracers: a 3D animation example of Thorium-230 along GEOTRACES North Atlantic Sections
The central component of GEOTRACES is a series of cruises spanning the global ocean. These cruises collect water and analysis of many trace elements and isotopes. The power of the GEOTRACES […]
New strategy to evaluate trace element fluxes to the ocean from aerosols
Scientists participating in GEOTRACES have developed a new strategy to evaluate trace element fluxes to the ocean from aerosols (Hsieh et al, 2011). The new approach uses the common geochemical behaviour […]