Mediterranean Endures Emissions from Afar. (Air-Pollution Pileup)
Pickrell, J., Science News
Most Mediterranean countries aren't big polluters. A new survey suggests, however, that the area is a crossroads for pollution-carrying air currents from Europe, Asia, and North America.
According to an international team of 31 atmospheric chemists, climatologists, and others, these currents converge over the Mediterranean Sea, creating pollutant concentrations that routinely surpass the European Union's air-quality standards. The team reports its findings in the Oct. 25 Science.
Previous measurements of unusually high ozone concentrations in the region prompted Jos Lelieveld of the Max-Planck Institute for Chemistry in Mainz, Germany, and his colleagues to attempt a more detailed analysis. In the summer of 2001, they used aircraft as well as atmosphere-measuring stations on Crete and Malta to monitor pollutants and climatic activity.
The researchers found that trace gases, such as carbon monoxide and nitric oxide, and atmospheric aerosol particles were between 2 and 10 times as concentrated over the Mediterranean Sea as in areas above the northern Pacific. "It was rather astonishing," says Lelieveld, "to find similar levels above [the Mediterranean Sea] as you'd expect to find above a ... city."
Computer models suggest that as little as 20 percent of the carbon monoxide found in the lowest atmospheric layers originated in Greece, Yugoslavia, and other Mediterranean nations, the researchers report. Instead, 60 to 80 percent of the gas appears to be coming from Russia, Poland, France, Germany, and other European nations. Northerly summertime winds in the lower atmosphere are to blame for transporting the pollution, says Lelieveld. …