Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A small wave of relief: Oxygen measured in the deep water of the Baltic Proper

08.08.2014

Recent readings of the IOW reveal: Oxygen-rich saltwater from the North Sea has entered the Central Baltic Sea and there, for the first time since 2003, has displaced hydrogen sulfide in the deep water.

After a long period of oxygen depletion and hydrogen sulfide formation in the deep water of the Central Baltic Sea (since 2003), saltwater being rich in oxygen has reached these submarine areas once again, as the results of the most recent measuring campaign of the Leibniz Institute for Baltic Sea Research in Rostock-Warnemünde now reveal.


Central Baltic Sea November 2013 – Situation before salt water inflow

(IOW)


Central Baltic Sea in July 2014 – Situation after salt water inflow

(IOW)

This slightly improves the living conditions of higher organisms in these regions which were often referred to as “dead zones”.

The last time a similar event has been observed was in November / December 2011. Back then, the deep water of the Southern Baltic Sea was not ventilated further than the Gdansk Basin. The recently measured inflowing salt water succeeded in progressing farther to the Northeast up to the Central Gotland Basin.

There,the bottom-near water layer in depths between 200 and 240 m was provided with oxygen while toxic hydrogen sulfide was removed. At the time of the measuring campaign, this inflow however did not yet reach the Northern part the Gotland Basin.

According to the Warnemünde scientists, two long-lasting phases of westerly winds in February and March 2014 have triggered these processes. The gauge data from February 3 – 20 and March 8 – 19 show minor wind-induced inflow events with estimated volumina of approximately 141 km³ and 203 km³, with the March event carrying the major volumes into the Baltic.

The scientific cruise from July 19 – 30, 2014 was one of five regular measurement campaigns per year which the IOW is conducting to monitor the state of the marine environment of the Baltic Sea. The campains follow a fixed station network reaching as far as to the Gotland Basin. Within the German EEZ, this is done on behalf of the Federal Maritime and Hydrographic Agency (BSH) which is responsible for the performance of the duties that the Federal Republic of Germany agreed upon in the Helsinki Convention.

The gained data are used as a foundation for regular assessments of the state of the Baltic Sea, both on national and international level, as well as for numerous other scientific publications. Besides, they provide the scientific basis for further measures planned to protect or restore the ecosystem of the Baltic Sea.

Contact:

Dr. Günther Nausch, Sektion Meereschemie, Arbeitsgruppe Allgemeine Meereschemie (Nährstoffanalytik), IOW
(Tel.: 0381 / 5197 332, Email: guenther.nausch@io-warnemuende.de)

Dr. Michael Naumann, Sektion Physikalische Ozeanographie und Messtechnik, IOW (Tel.: 0381 / 5197 267, Email: michael.naumann@io-warnemuende.de)

Nils Ehrenberg, Öffentlichkeitsarbeit, IOW
(Tel.: 0381 / 5197 106, Email: nils.ehrenberg@io-warnemuende.de)

Background information: salt water inflows

The water body of the Baltic Sea is permanently stratified with brackish surface water fed by the constant freshwater discharge of numerous rivers. This surface layer is in constant exchange with the atmosphere. It is well provided with oxygen by wind mixing, temperature-induced convection processes and the biological production. From a depth of approximately 70 m on, in areas which are no longer influenced by wind mixing, the Baltic Sea shows its close connection to the North Sea: it is here that the salty North Sea water concentrates which periodically flows into the Baltic Sea via the Danish Belt Sea, Being saltier than the Baltic Sea water, it is also heavier, thus it is flowing along the bottom of the Baltic Sea into the deep basins. Both water bodies do not mix but to a minor degree which causes a permanent stratification. Solid particles like dead organic matter can easily pass this boundary whereas gases dissolved in the water are hold back efficiently. The oxygen content of the deep water therefore constantly decreases as the oxygen is consumed during the decomposition of the deposited organic particles. When the oxygen is entirely depleted, toxic hydrogen sulfide forms. An improvement of this state can only be reached by the lateral supply with large amounts of North Sea water which has been in contact with the atmosphere and therefore is rich in oxygen.

Submarine sills in the Western Baltic Sea hamper this horizontal water exchange. Only under specific meteorological conditions, the salt water can pass these natural impediments to supply the eastern/central parts of the Baltic Sea with oxygen. These sills are the so called Darß Sill, an extended sandy plain between the Danish Island of Moen and the peninsula of Fischland-Darß-Zingst with water depths of 18 – 19 m, and the Drogden Sill being positioned in the Oere Sound between the Danish island Zealand and the Swedish mainland with water depths of only 8 – 9 m.

Since 2003, no major salt water inflow has occured, which has led to the fact that in the deep areas of the central Baltic Sea (>90 m) all oxygen has been consumed and an increased formation of hydrogen sulfide went on. Thus, the biological living conditions for higher organisms have strongly been limited in these areas, which therefore were often referred to as “dead zones” in the media.

Link to images in high resolution:

http://www.io-warnemuende.de/mitteilung/items/salzwassereinbruch-2014.html

Further material on demand

The IOW is a member of the Leibniz Association to which 89 research institutes and scientific infrastructure facilities for research currently belong. The focus of the Leibniz Institutes ranges from Natural, Engineering and Environmental Science to Economic, Social, and Space Sciences and to the humanities. The institutes are jointly financed at the state and national levels. The Leibniz Institutes employ a total of 17.200 people, of whom 8.200 are scientists, of which 3.300 are junior scientists. The total budget of the Institutes is more than 1.5 billion Euros. Third-party funds amount to approximately € 330 million per year. www.leibniz-gemeinschaft.de

Dr. Barbara Hentzsch | idw - Informationsdienst Wissenschaft

Further reports about: Baltic Basin IOW Leibniz-Institut Ostseeforschung Oxygen atmosphere

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Experiment Provides the Best Look Yet at 'Warm Dense Matter' at Cores of Giant Planets

In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...

Im Focus: Energy-autonomous and wireless monitoring protects marine gearboxes

The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.

As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...

Im Focus: 3-D satellite, GPS earthquake maps isolate impacts in real time

Method produced by UI researcher could improve reaction time to deadly, expensive quakes

When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.

Im Focus: Atlantic Ocean overturning found to slow down already today

The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe. 

Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...

Im Focus: Robot inspects concrete garage floors and bridge roadways for damage

Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.

From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference On Regenerative Medicine 2015: Registration And Abstract Submission Now Open

25.03.2015 | Event News

University presidents from all over the world meet in Hamburg

19.03.2015 | Event News

10. CeBiTec Symposium zum Big Data-Problem

17.03.2015 | Event News

 
Latest News

Two Most Destructive Termite Species Forming Superswarms in South Florida

27.03.2015 | Agricultural and Forestry Science

ORNL-Led Team Demonstrates Desalination with Nanoporous Graphene Membrane

27.03.2015 | Materials Sciences

Coorong Fish Hedge Their Bets for Survival

27.03.2015 | Ecology, The Environment and Conservation

VideoLinks
B2B-VideoLinks
More VideoLinks >>>