Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Portrait of a doomed Sea

29.07.2003


Image 1: This image of the dying Aral Sea was taken by Envisat’s Medium Resolution Imaging Spectrometer (MERIS) instrument on July 9.

Image 2: This south-facing image of a much larger Aral Sea was taken by an astronaut on the Space Shuttle Challenger (carrying ESA’s Spacelab) in August 1985.


Image 3: During its heyday the Aral Sea fishing town of Muynak had fishing boats deliver their catch straight to canneries that employed 2,000 people. Now the town is 150 km away from water. Credits: Petter Hveem - Medecins San Frontieres Norway


Earth’s youngest desert is shown in this July MERIS satellite image of the Aral Sea in Central Asia. Once the fourth largest lake in the world, over the last 40 years the Aral Sea has evaporated back to half its original surface area and a quarter its initial volume, leaving a 40,000 square kilometre zone of dry white-coloured salt terrain now called the Aralkum Desert.

As its water level has dropped 13 metres since the 1960s the Sea has actually split into two – the larger horseshoe-shaped body of water and a smaller almost unconnected lake a little to its north. This Small Aral Sea is the focus of international preservation efforts, but the Large Aral Sea has been judged beyond saving (the shallowness of its eastern section is clear in the image). It is expected to dry out completely by 2020.

Towards the bottom right can be seen the sands of the Qyzylqum Desert. Already stretching across an area greater than Italy, this desert is set to extend further west in future, eventually merging with its younger Aralkum sibling. The distinctive darker area to the south of the Large Aral Sea is the delta of the Amu Darya river. Its waters support environmentally-unique tugai forests found only in Central Asia, along with land used for rice and cotton cultivation.



The grey area seen in the otherwise whitish zone between the two arms of the Large Aral Sea was once Vozrozhdeniye (’’Rebirth’’) Island, the isolated site of biological warfare experimentation during the Cold War, now joined to the mainland and freely accessible by foot. In reaction to this development, a US-led international team last year moved in to destroy remaining anthrax stocks.

Located on the border between Uzbekistan and Kazakhstan, the Aral Sea shows what happens when the concept of sustainable development is disregarded. Starting in the 1960s, the waters of the two rivers feeding the Sea – the Amu Darya, seen south, and the Syr Darya to the northwest – were diverted by Soviet planners to irrigate thirsty cotton fields across the region. By the 1980s there was little water reaching the lake and it began to shrink.

For local people the results have been disastrous. The Aral Sea’’s retreating shoreline has left ports landlocked and boats stranded on dry sand. Commercial fishing was forced to halt twenty years ago. The few remaining fishermen commute by car to the water’’s edge. The waters that remain grow increasingly saline so only salt-resistant fish imported from elsewhere can endure them. Wildlife habitats have been destroyed and communities find themselves without clean water supplies.

The retreat of the waters has also altered the regional microclimate. Winters are colder and the summers hotter. Each year violent sandstorms pick up at least 150,000 tonnes of salt and sand from the dried-up lakebed and transport it across hundreds of kilometres.

The sandstorms are tainted with pesticide residue and have been linked to high regional rates of respiratory illnesses and certain types of cancer. The salty dust does harm to livestock pastures and has even been linked with melting glaciers up in the distant Pamir Mountains, on the Afghanistan border.

Back in the days of the USSR, planners spoke casually of diverting Siberian rivers to save the Aral Sea. Today that certainly will not happen. Instead Central Asian governments have come together to establish the International Fund for Saving the Aral Sea. But their economies are too dependent on cotton exports to end all irrigation.

The Small Aral Sea is still thought to be saveable, and several dikes have been constructed to cut it off from the Large Aral Sea – preventing water loss and salt contamination - but shifting water levels have so far defeated these efforts. The channel connecting the two should soon dry up anyway, preserving the Small Aral Sea at least. Meanwhile researchers are studying the salty Aralkum Desert – effectively the newest land surface on Earth – to see how best to promote plant growth and stabilise the dusty dry lakebed.

| European Space Agency
Further information:
http://www.esa.int

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>