eGEOTRACES

Find below a summary of main GEOTRACES findings and products on protactinium research:

Atlas

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3D scenes showing the distribution of dissolved iron in the Atlantic and the Pacific, the Arctic Oceans. In warm colours (red, orange, etc.) you can view high concentrations of dissolved protactinium-231.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on protactinium research:

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…

Measuring actinium-227 by mass spectrometry is feasible, sensitive and reliable!

Levier and co-authors have developed a new protocol measurement of the dissolved actinium in 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…

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 […]

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 […]

List of publications

Scroll down to view the list of GEOTRACES publications on protactinium-231:

May / 31 / 2022

In the marine environment, the different elements of the natural radioactive families of uranium (U)and thorium (Th) can be classified into two groups: those that are soluble in seawater and those that are particle-reactive, extracted from the water column by chemical and biological processes (adsorption, aggregation, precipitation).

Thorium isotopes are very reactive toward particles in the marine environment. In seawater, thorium is present as Th(OH)₄ oxide and adsorbs on all solid surfaces.

Thorium-232 (²³²Th) is the most abundant and is brought to the ocean in detrital form by rivers and the atmosphere. ²³²Th, coming from terrigenous dust, is directly associated with particles in the ocean. It is mostly transported by detrital matter. In the earth’s crust its concentration is of the order of 10.7 ppm but in sea water it is less than 0.7 ppt Thus, this isotope is used in marine geochemistry to quantify the so-called lithogenic contributions (from the erosion of rocks).

Thorium-234 (²³⁴Th) and Thorium-230 (²³⁰Th) are produced in situ (in dissolved form) by radioactive decay of Uranium-238 (²³⁸U) and Uranium-234(²³⁴U) by alpha emission. The concentrations of ²³⁸U and ²³⁴U are constant in the ocean, these nuclides represent homogeneous sources of ²³⁴Th and ²³⁰Th in the water column. These thorium isotopes, produced in situ, rapidly leave the seawater by attaching to marine particles. In this form, they become tracers of particulate matter. Therefore, the use of U/Th imbalances allows the study of:

• Particle fall rate and calibration of particle traps
• Estimation of exported production
• Interaction processes between solution and marine particles
• Ventilation of intermediate and deep waters

Find below a summary of main GEOTRACES findings and products on thorium research:

Atlas

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Thorium-230

Thorium-232

Thorium-234

3D scenes showing the distribution of ²³⁰Th, ²³²Th and ²³⁴th in the Atlantic, the Pacific and the Arctic Oceans. In warm colours (red, orange, etc.) you can view high concentrations of dissolved thorium.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on thorium research:

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…

Measuring actinium-227 by mass spectrometry is feasible, sensitive and reliable!

Levier and co-authors have developed a new protocol measurement of the dissolved actinium in 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…

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 […]

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 […]

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved thorium:

May / 31 / 2022

Find below a summary of main GEOTRACES findings and products on neodymium research:

Atlas

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3D scenes showing the distribution of dissolved iron in the Atlantic and the Pacific. In warm colours (red, orange, etc.) you can view high concentrations of dissolved neodymium.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on neodymium research:

Exhaustive modelling study of the oceanic neodymium parameters

The conclusion of this study reinforces the important role of the solid particles in driving the neodymium oceanic cycle.

Updated compilation of the global continental and marine lithogenic neodymium isotopic measurements

This new compilation and gridded datasets offer a concrete way forward to improve the application of neodymium isotopes as a useful tracer of ocean circulation.

Rare Earth Elements and neodymium isotopes as tracers in the Mediterranean Sea

Garcia-Solsona and co-workers analysed 9 seawater stations around the central Mediterranean Sea

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 […]

Tracing water mass mixing in the Cape Basin and the restricted Angola Basin with radiogenic neodymium isotopes

In the frame of GEOTRACES cruise GA08, Rahlf et al. (2020, see reference below) determined seawater profiles of dissolved radiogenic neodymium isotope signatures (εNd) and neodymium concentrations across the restricted western […]

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 […]

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved neodymium:

May / 31 / 2022

Find below a summary of main GEOTRACES findings and products on nickel research:

Atlas

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3D scenes showing the distribution of dissolved iron in the Atlantic and the Pacific. In warm colours (red, orange, etc.) you can view high concentrations of dissolved nickel.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on nickel research:

Shelf sediments in the Benguela Upwelling System as a major source of trace metals to the shelf and eastern South Atlantic Ocean

Liu and her colleagues investigated dissolved trace metals distributions within the Benguela Upwelling System sampled from GEOTRACES GA08 cruise.

Debate on the dissolved nickel bioavailibility in surface waters

John and co-authors tackle one of the known paradoxes regarding trace metal cycles in the ocean…

Nickel bioactive role in the oceans assessed by its isotopes

Lemaitre and her colleagues realized the simultaneous analysis of the dissolved nickel isotopes and concentrations in the North Atlantic.

Contrasting distributions of dissolved manganese, nickel, cadmium and zinc in the Mediterranean Sea

Extensive trace metal clean sampling during the Dutch GEOTRACES cruise in the Mediterranean Sea allowed Middag and his colleagues to establish the basin scale distribution of these trace metals.

Icebergs as sources of trace metals to the ocean: which impact?

Earth’s Ice Sheets are known to release significant quantities of lithogenic particles into the ocean every year, but how does this material affect trace metal availability in the ocean?

Scavenging differentiates the distribution of cadmium, nickel, zinc and copper in the North Pacific Ocean

Zheng and co-authors observed sectional distributions of cadmium, nickel, zinc, and copper in the North Pacific Ocean during three GEOTRACES related cruises…

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved nickel:

May / 31 / 2022

Find below a summary of main GEOTRACES findings and products on manganese research:

Atlas

(The images below may not show if you are using Safari. Please change your browser if necessary).

3D scenes showing the distribution of dissolved iron in the Atlantic and the Pacific. In warm colours (red, orange, etc.) you can view high concentrations of dissolved manganese.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on manganese research:

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…

Measuring actinium-227 by mass spectrometry is feasible, sensitive and reliable!

Levier and co-authors have developed a new protocol measurement of the dissolved actinium in 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…

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 […]

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 […]

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved manganese:

May / 31 / 2022

Find below a summary of main GEOTRACES findings and products on cobalt research:

Atlas

(The images below may not show if you are using Safari. Please change your browser if necessary).

3D scenes showing the distribution of dissolved iron in the Atlantic and the Pacific. In warm colours (red, orange, etc.) you can view high concentrations of dissolved cobalt.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on cobalt research:

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…

Measuring actinium-227 by mass spectrometry is feasible, sensitive and reliable!

Levier and co-authors have developed a new protocol measurement of the dissolved actinium in 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…

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 […]

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 […]

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved cobalt:

May / 31 / 2022

Find below a summary of main GEOTRACES findings and products on zinc research:

Atlas

(The images below may not show if you are using Safari. Please change your browser if necessary).

3D scenes showing the distribution of dissolved zinc in the Atlantic and the Pacific. In warm colours (red, orange, etc.) you can view high concentrations of dissolved zinc.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on zinc research:

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…

Measuring actinium-227 by mass spectrometry is feasible, sensitive and reliable!

Levier and co-authors have developed a new protocol measurement of the dissolved actinium in 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…

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 […]

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 […]

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved iron:

May / 31 / 2022

Atlas

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3D scenes showing the distribution of dissolved cadmium in the Atlantic, Pacific Indian and Arctic Oceans. In warm colours (red, orange, etc.) you can view high concentrations of dissolved Cadium.

Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on cadmium research:

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.

Shelf sediments in the Benguela Upwelling System as a major source of trace metals to the shelf and eastern South Atlantic Ocean

Liu and her colleagues investigated dissolved trace metals distributions within the Benguela Upwelling System sampled from GEOTRACES GA08 cruise.

Contrasting distributions of dissolved manganese, nickel, cadmium and zinc in the Mediterranean Sea

Extensive trace metal clean sampling during the Dutch GEOTRACES cruise in the Mediterranean Sea allowed Middag and his colleagues to establish the basin scale distribution of these trace metals.

Unique winter dataset of particulate and dissolved cadmium in the Indian sector of the Southern Ocean

Cloete and collaborators analysed particulate and dissolved cadmium at 7 stations in austral winter along a North South section off South Africa.

Scavenging differentiates the distribution of cadmium, nickel, zinc and copper in the North Pacific Ocean

Zheng and co-authors observed sectional distributions of cadmium, nickel, zinc, and copper in the North Pacific Ocean during three GEOTRACES related cruises…

Controls of cadmium-phosphate systematic unraveled by Neural Networks and Ocean Circulation Inverse Model

Roshan and DeVries explore the similarities and contrasts between oceanic cadmium and phosphate cycles using an Artificial Neural Network mapping technique and Ocean Circulation Inverse Model.

List of publications

Scroll down to view the list of GEOTRACES publications on dissolved cadmium:

May / 30 / 2022

Naturally occurring radium isotopes allow the study of short and long term processes in the ocean. Radium is produced by the decay of thorium mainly in the sediments but also in the water column. In the ocean, thorium is produced by the decay of uranium directly present in the water column. Thorium have a strong affinity for particles and is adsorbed on the particles. Then thorium is transported to the bottom and slowly accumulates in the sediments. Having an affinity for the dissolved phase, radium, produced in the sediments, diffuses to the water column at the margins and into the deep ocean. Therefore, radium concentrations are generally high near the sediments, in freshwater discharges to the ocean and in circulating waters through the sediments, and are low in the open ocean. Water masses in contact with sediments become enriched in radium. Radium isotopes can be used to trade different processes.

The isotopes radium-224 (²²⁴Ra) and radium-223 (²²³Ra), because of their short half-lives, remain in the ocean about 2 or 3 weeks and 2 months, respectively. They are detected mainly at the interfaces (sediment, surface, margins. . .) and in the first 100 km offshore in the mixed layer. These two isotopes can be used to quantify freshwater discharge fluxes at sea and circulation waters through sediments, to estimate the residence time in the coastal zone, horizontal transports from the coast to the open sea gradient.

Radium-228 (²²⁸Ra) has a longer half-life which allows it to reach the open ocean. ²²⁸Ra can be measured up to about 30 years after its release from the sediments. The highest activities of ²²⁸Ra are observed at the surface due to surface transport from continental margins, rivers, freshwater discharges, and recirculating water in the sediments. Fluxes of ²²⁸Ra from springs and, more generally, from continental margins to the open ocean can be converted to fluxes of trace elements such as iron.

Radium-226 (²²⁶Ra) has the longest half-life. ²²⁶Ra activities increase with depth, which is mainly explained by diffusion from deep sediments. ²²⁶Ra activities vary from one basin to another depending on the water masses and their origins. Bottom waters get enriched with ²²⁶Ra along the path of the thermohaline circulation between the North Atlantic and the North Pacific. The transit time of water from the North Atlantic to the North Pacific is about 1000 years. This transit time is similar to the half-life of ²²⁶Ra and makes it a potential tracer of this global circulation and water masses.

Find below a summary of main GEOTRACES findings and products on radium research:

Atlas

3D scenes showing the distribution of dissolved radium-226 and radium-228 in the North Atlantic and the Pacific. In warm colours (red, orange, etc.) you can view high activities of dissolved radium.

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Data

Data is available to download after registration here: https://geotraces.webodv.awi.de/login

Discoveries include:

Below you can find a list of science highlights of main GEOTRACES discoveries on radium research:

A detailed study of the land-ocean input of dissolved iron, manganese and cobalt in the Northeast Atlantic Ocean

Chen and co-authors propose a detailed study of the spatial and seasonal distributions of dissolved iron, manganese and cobalt in the Northeast Atlantic continental margin.

Radium-224 and radium-223: powerful chronometers to estimate the residence time of Amazon waters on the Brazilian continental shelf

In this study, radium is used as a tracer for the waters of the Amazon that mix with those of the Atlantic Ocean.

Unprecedented iron delivery from the Congo River margin to the South Atlantic Gyre

Radium isotopes are used to demonstrate that make the Congo the most significant riverine source of iron to the South Atlantic.

Environmental changes in the Arctic Ocean are occurring now!

Radium-228 increase in the central Arctic (2007 to 2015), is attributed to stronger wave action on shelves due to a longer ice-free season.

List of publications

Scroll down to view the list of GEOTRACES publications on radium isotopes:

May / 19 / 2022