Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nature Study: Is modern Arctic Ocean Circulation exceptional?

03.12.2007
The Arctic Ocean only has a limited exchange with the global ocean, whereby the Fram Strait between Greenland and Svalbard is the only deep water connection to the Atlantic Ocean. It is this connection that supplies oxygen to the deep Arctic Ocean.

Today a pronounced and stable freshwater layer at the surface originating from inputs of the large Russian rivers almost completely prevents any significant deep water formation in the Arctic Ocean itself. The results of Brian Haley and colleagues from the IFM-GEOMAR now show that this was an exception rather than the rule for most of the past 15 million years.

The Kiel team made their discovery when they carried out geochemical analyses on sediments of the Arctic Coring Expedition (ACEX, Leg 302 of the Integrated Ocean Drilling Program (IODP)) and of a RV Polarstern expedition, which had been recovered near the North Pole on the Lomonosov Ridge between 1.000 und 1.200 m water depth. They reconstructed the seawater isotope ratio of the element neodymium (143Nd/144Nd) from the sediments. The Nd, which has characteristic isotope ratios in rocks as a function of their type and age, is transported to the ocean through weathering, where it provides information on the sources of water masses. To their surprise, the geochemists found that the isotope signature of the seawater was strongly different from the present day values, with the exception of the warm periods of the past 400.000 years. “It is even more surprising that this isotope signature indicated a pronounced influence of the weathering of basaltic rocks”, says Brian Haley. On the Circum-arctic landmasses such rocks, however, only exist in the form of the Siberian “Putorana flood basalts”.

From this geologically unique setting and taking into account the evolution of the continental ice sheets of the past 140.000 years, it was then possible to reconstruct the circulation history of the deep Arctic Ocean. The signature of the basalts can only have arrived at 1.000 m water depth in the central Arctic Ocean if vast amounts of new sea ice formed near the basalt areas in the Kara Sea area. How did the signature arrive at the seafloor? “During sea ice formation the salt of the sea water freezes out and is rejected, thereby forming highly saline brines, which were denser than the surrounding sea water. These brines sank and transported the dissolved Nd isotope signature of the basalts to the sea floor where the sediment cores were recovered”, explains Martin Frank, co-author of the study. Further, the obtained Nd isotope variations imply that the inflow of Atlantic waters was significantly reduced during most of the past 15 million years and during the glacial periods of the past 400.000 years. This also suggests that during these periods of time the main area of Atlantic deep water formation was not located in the Norwegian-Greenland Sea, similar to today, but further south.

The arctic IODP ACEX drilling project was coordinated by the European consortium ECORD (European Consortium for Ocean Research Drilling). This organization consists of partners from 17 European nations participating in the „International Ocean Drilling Programme“. ECORD is also responsible for the planning and coordination of special operations, for which normal drilling vessels cannot be used, as was the case for the ACEX project. For such purposes special platforms are used to achieve the scientific goals.

Andreas Villwock | alfa
Further information:
http://www.ifm-geomar.de/index.php?id=3887&L=1

More articles from Studies and Analyses:

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

nachricht A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>