Arable land can have a negative impact on air quality

Over two-thirds of the land area in the Ukraine consists of fields and meadows. The soil on 220,000 square kilometres is regarded as being under threat. Since the 1930s wind erosion in what was then the Soviet Union has increased considerably as a result of collectivisation in agriculture and the resultant large field areas. In particular, this has affected the regions north of the Caucasus, the lower reaches of the Don river and eastern and southern Ukraine. It is possible that the process is also accelerated by climate change. In particular, previously unaffected semi-arid regions are continuing to dry out. A normal dust storm can result in 70 tons of the light black soil being whirled up per hectare per hour. "According to Russian studies, in the past 40 years there have been three to five such dust storms per year on average in the Ukrainian steppe," Birmili reports. "Our institute has been constantly monitoring the airborne particles and their components at the Melpitz research station near Leipzig for around 15 years. We analysed all these measurements again retrospectively but were unable to detect any comparable dust cloud from the Black Sea area. This makes the dust cloud of 24 March 2007 unusual. But who can say that such weather conditions may not occur more frequently in future as a result of climate change""

Small particles with a big effect

The research findings put a new complexion on the attempts being made by many local authorities to comply with the particulate limits using a wide range of measures. In the greater Berlin area for instance, scientists estimate that half of the particulate volumes come from regional and remote sources, rather than from local sources. Besides salt particles, soil particles form the largest mass of particles in the atmosphere. Scientists estimate that there are between 1,000 and 2,000 million tons of dust circulating around the world in the lower layers of the atmosphere in annual totals. This would be equivalent to the cargo of a goods train long enough to encircle the globe five times. This particulate matter comes primarily from arid areas and deserts, i.e. from the Sahara, the Arabian peninsula, the Gobi Desert and the Taklimakan Desert in Asia, and the deserts in Australia and South America. One-fifth is believed to be caused by human activity, such as field cultivation. And there are consequences for the climate because dust particles in the air block solar radiation trying to enter the atmosphere and block heat radiation escaping into space and are therefore the largest unknown factor in climate models. Moreover, not much is known about the possible health impacts of such long-distance transport of dust aerosols.

more information:
Dr Wolfram Birmili
Leibniz Institute for Tropospheric Research
http://www.tropos.de/physik/aerosol/physik_aero.html
phone +49-341-235-3437, -3210