In the last 40 years the Aral Sea, situated on the southern border of Kazakhstan, has shrunk to a small fraction of its original size. It is now considered to be among the driest places in Central Asia. While the surrounding desert continues to grow, duststorms are spreading a dangerous mixture of sand, salt and poisonous chemicals into populated areas. European researchers are working together with scientists from this region to better understand the duststorms and minimise the harm they can do.
The Aral Sea had once served as a massive oasis between two deserts, known as Karakoum and Kusulkoum, with a high biodiversity. Since 1960 around 50,000 kilometres of sea has disappeared, due to inefficient use of the main tributary rivers, leaving the sea reduced to three smaller lakes. The area that used to be sea is now known as 'Aralkoum', meaning Aral desert.
The loss of so much water had a huge impact on the people living in the area. Many fish species have disappeared and most fishermen lost their jobs. Unemployment, poverty and disease are common in the towns along the earlier shoreline. Cases of tuberculosis and hepatitis are twice as likely to be found here than in neighbouring regions.
There is, however, another problem. Frequent duststorms disperse sand, salt, aerosols and chemical compounds used for farming into the air, which is ultimately being breathed in by the local population. Furthermore, the spreading of this poisonous mixture has crippled the growth of vegetations within a 150 km radius, bringing about the desertification of the whole region.
The current situation has led to the creation of CALTER, a European research project. The aim is to better understand the dynamics of the duststorms in Central Asia, in particular those near the Aral Sea, and to study their direction and composition. Based on their findings, the project will put forward solutions to minimise the consequences of the duststorms.
At a meteorological station, 300 kms from the Aral Sea, particles were trapped during a duststorm to be weighed, measured and analysed. The mineral make-up of the particles can be analysed using techniques like radiofluorescence, which, in this case due to the rich salt content, proved that the dust particles came from the Aral Sea. The duststorm had carried the particles a distance of 300 km.
The duststorms can be observed at Kazakhstan's National Space Research Centre, in Almaty, using satellites. Since the year 2000, an increase in the intensity and the frequency of duststorms in the Aral region has been observed. The amount of dust being transported is therefore also higher.
At the Kazakh Research Institute of Ecology and Climate miniature duststorms can be produced in a wind tunnel. Using laser technology researchers can study the internal dynamics of a duststorm, including their volume, speed, density, how they form and how they diminish. From these simulations it has become clear that the sand particles of a duststorm travel similar to an avalanche; small particles are accelerated and collide with larger particles, which then collide with even larger particles, and so on. The researchers here can now calculate the mass of sand being carried at varying heights and wind speeds.
The scientists believe firmly that the increase in duststorms is a result of the man-made desertification that is expanding around the Aral Sea. There are few possible solutions. One suggestion coming from the CALTER project is the cultivation of native plants to stop any further soil degradation. Arranged in small vegetation patches across the former seabed of the Aral Sea, the plants would secure the surface and the amount of dust blown away would decrease.