Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Measuring Individual Argon Atoms Helps In Understanding Ocean Ventilation

20.12.2018

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.

Contact:
Communications and Marketing
Press Office
Phone +49 6221 54-2311
presse@rektorat.uni-heidelberg.de

Wissenschaftliche Ansprechpartner:

Prof. Dr Markus Oberthaler
Kirchhoff-Institute for Physics
Phone +49 6221 54-51770
markus.oberthaler@kip.uni-heidelberg.de

Prof. Dr Werner Aeschbach
Institute for Environmental Physics
Phone +49 6221 54-6331
aeschbach@iup.uni-heidelberg.de

Dr Toste Tanhua
GEOMAR Helmholtz Centre for Ocean Research Kiel
Phone +49 432 600-4219
ttanhua@geomar.de

Originalpublikation:

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, www.nature.com/articles/s41467-018-07465-7

Weitere Informationen:

https://www.sfb754.de/de/m116

Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-heidelberg.de

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

More articles from Earth Sciences:

nachricht The Blue Acceleration: Recent colossal rise in human pressure on ocean quantified
27.01.2020 | Stockholm Resilience Centre

nachricht Earth's most biodiverse ecosystems face a perfect storm
27.01.2020 | Lancaster University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Integrate Micro Chips for electronic Skin

Researchers from Dresden and Osaka present the first fully integrated flexible electronics made of magnetic sensors and organic circuits which opens the path towards the development of electronic skin.

Human skin is a fascinating and multifunctional organ with unique properties originating from its flexible and compliant nature. It allows for interfacing with...

Im Focus: Dresden researchers discover resistance mechanism in aggressive cancer

Protease blocks guardian function against uncontrolled cell division

Researchers of the Carl Gustav Carus University Hospital Dresden at the National Center for Tumor Diseases Dresden (NCT/UCC), together with an international...

Im Focus: New roles found for Huntington's disease protein

Crucial role in synapse formation could be new avenue toward treatment

A Duke University research team has identified a new function of a gene called huntingtin, a mutation of which underlies the progressive neurodegenerative...

Im Focus: A new look at 'strange metals'

For years, a new synthesis method has been developed at TU Wien (Vienna) to unlock the secrets of "strange metals". Now a breakthrough has been achieved. The results have been published in "Science".

Superconductors allow electrical current to flow without any resistance - but only below a certain critical temperature. Many materials have to be cooled down...

Im Focus: Programmable nests for cells

KIT researchers develop novel composites of DNA, silica particles, and carbon nanotubes -- Properties can be tailored to various applications

Using DNA, smallest silica particles, and carbon nanotubes, researchers of Karlsruhe Institute of Technology (KIT) developed novel programmable materials....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

 
Latest News

Towards better anti-cancer drugs: New insights into CDK8, an important human oncogene

28.01.2020 | Life Sciences

Rice lab turns trash into valuable graphene in a flash

28.01.2020 | Materials Sciences

AI can jump-start radiation therapy for cancer patients

28.01.2020 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>