Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Measuring Individual Argon Atoms Helps In Understanding Ocean Ventilation


Study uses Heidelberg dating method for deep ocean water for first time

The age of the water in the world's oceans is critical for understanding ocean circulation, especially for the transport of gases from the atmosphere into the deep ocean.

The first sample for Argon-39 measurements using the new ATTA method, collected at a depth of 4,000 metres. The sample was obtained during a pilot study in the tropical North Atlantic off the Cape Verde Islands. Pictured: Toste Tanhua (left) and Boie Bogner (right) from the GEOMAR Helmholtz Centre for Ocean Research Kiel with Arne Kersting (centre) from the Institute for Environmental Physics of Heidelberg University.

Photo: Martin Visbeck (GEOMAR)

Researchers from Heidelberg University recently used an atomic physics technique they developed to determine the age of deep ocean water ranging from 50 to 1,000 years.

This new dating method, which measures individual argon atoms, was used in a pilot study in the North Atlantic. The experiments are part of an interdisciplinary project with oceanographers of the GEOMAR Helmholtz Centre for Ocean Research Kiel. The results were published in the journal “Nature Communications”.

The circulation of the world's oceans is of great importance for life in the ocean as well as for the global climate system.

For future climate prognoses, it is important to understand not only how deep water is supplied with fresh oxygen but also how quickly and in what quantities the oceans absorb human-generated CO2 greenhouse gas from the air. To do that requires knowing the age of the deep water.

How long does it take for water from the surface to reach a specific location in the ocean's interior? For periods of up to around 50 years, there are multiple dating methods. But for older water – and hence most of the ocean – there has been no optimal dating method until now, the Heidelberg researchers emphasise.

The rare radioactive isotope 39Ar of the noble gas argon (Ar) is used for dating. With a half-life of 269 years, it is especially suitable for the 50- to 1,000-year range. This period of time is critical for understanding the movement of surface water into the deep ocean.

But there is only a single atom of the sought-after 39Ar isotope in a thousand billion (1015) argon atoms in the atmosphere and surface water. How many of these isotopes can still be detected in deep water that has had no contact with the atmosphere for some time?

Until now, answering this question required substantial effort and an enormous sample size. The Heidelberg researchers have now adapted a fundamentally new measurement method, Atom Trap Trace Analysis (ATTA), especially for 39Ar.

Using this method, the research group led by Prof. Dr Markus Oberthaler at the Kirchhoff Institute for Physics was able to reduce the sample size needed for dating from the minimum of 1,000 litres of water to five.

“Unlike with conventional methods, we do not wait for the isotope to spontaneously decay to capture it; we slow the atoms down using modern laser technology, capture them in atom traps, and selectively count individual atoms,” explains Dr Sven Ebser, the study's primary author.

Each isotope responds to minimally different laser light, which the physicists use to their advantage in this process. This slight effect in the wavelength is enough to “manipulate” and detect the desired 39Ar atoms while all the other atoms can freely pass through atom trap unobserved.

“The 39Ar method was available for our work only because of the greatly reduced sample size,” explains oceanographer Dr Toste Tanhua of the GEOMAR Helmholtz Centre for Ocean Research. As the pilot study off the Cape Verde Islands demonstrated, the method enables the researchers to identify much more precisely when a water sample last had contact with the atmosphere. This provides new insights into the movement of trace substances in the ocean. In the area studied at depths between 1,000 and 2,000 metres, for instance, there was considerably less mixing than assumed. The calculations indicate that more CO2 is being absorbed from the atmosphere than previously thought. “I am sure that a global 39Ar data set will lead to entirely new discoveries about ocean circulation and the ‘respiration’ of the world's oceans,” states Dr Tanhua.

“The new method of measurement will benefit not only ocean research but groundwater and ice research as well,” adds Prof. Dr Werner Aeschbach of the Institute for Environmental Physics at Heidelberg University. According to Prof. Oberthaler, the project is an excellent example of how basic research in atomic physics can lead to discoveries in initially totally unrelated fields. The German Research Foundation is funding the development of atom trap measurement technology as part of the "New Instrumentation for Research" programme.

Communications and Marketing
Press Office
Phone +49 6221 54-2311

Wissenschaftliche Ansprechpartner:

Prof. Dr Markus Oberthaler
Kirchhoff-Institute for Physics
Phone +49 6221 54-51770

Prof. Dr Werner Aeschbach
Institute for Environmental Physics
Phone +49 6221 54-6331

Dr Toste Tanhua
GEOMAR Helmholtz Centre for Ocean Research Kiel
Phone +49 432 600-4219


S. Ebser, A. Kersting, T. Stöven, Z. Feng, L. Ringena, M. Schmidt, T. Tanhua, W. Aeschbach & M.K. Oberthaler: 39Ar dating with small samples provides new key constraints on ocean ventilation. Nature Communications (2018) 9:5046,

Weitere Informationen:

Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
Further information:

Further reports about: Atmosphere Atoms GEOMAR Ocean Ocean Research Phone argon deep ocean deep water

More articles from Earth Sciences:

nachricht Welcome Committee for Comets
19.07.2019 | Technische Universität Braunschweig

nachricht Sea level rise: West Antarctic ice collapse may be prevented by snowing ocean water onto it
18.07.2019 | Potsdam-Institut für Klimafolgenforschung

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

Latest News

Heat flow through single molecules detected

19.07.2019 | Physics and Astronomy

Heat transport through single molecules

19.07.2019 | Physics and Astronomy

Welcome Committee for Comets

19.07.2019 | Earth Sciences

Science & Research
Overview of more VideoLinks >>>