Air pollution's global reach. Why Arctic haze can be dirtier than New Jersey smog
SIBERIAN soot dims Arctic skies. North American pollutants waft over Irish hills. Pesticides show up in dolphins and whales. ``Chemicals used by man are easily and quickly moved around the environment and to faraway places,'' says Elliot Atlas. ``It is not just a local or regional problem - it is a global problem,'' he adds.
The Texas A&M pollution sleuth is part of the Sea-Air Exchange (SEAREX) project group that has been tracing the drift of chemicals over the Pacific Ocean. They are now turning to the Atlantic to complete their studies. But nine years' Pacific research has already shown how fast and far airborne chemicals can spread. And, what may be most important, it has produced techniques that may develop into a systematic method for tracing specific pollutants back to their sources.
For example, Robert B. Gagosian and Edward T. Peltzer of the Woods Hole Oceanographic Institution and John T. Merrill of the University of Rhode Island have mapped the wanderings of lipids (waxes found in plants) observed in air passing over New Zealand. They analyzed the aerosols for organic compounds, which differ according to the regions where the original plants grew. These served as ``fingerprints'' to suggest where the lipids came from. By carefully backtracking the air masses that carried it, they could reconstruct the wanderings of this natural pollution from sources in such places as southern Australia and Tasmania.
Cadmium and lead are hallmarks of auto exhaust. Smelters, power plants, and other pollution sources have their chemical ``fingerprints,'' too. As scientists refine their techniques for tracing the long-distance travels of such chemicals through the atmosphere, they may eventually be able to pinpoint pollution sources as specific as power plants or a metal processing complex.
Even an ability to pin down remote pollution sources reliably to specific regions could have significant diplomatic implications. Atlas observes that other nations might then be in the situation of the United States, which has agreed to help pay for cleaning up acid rain pollution in Canada because some of it undoubtedly comes from the US.
Actually, there's nothing surprising in finding that wind moves materials around. Atmospheric scientists are well aware that Saharan dust can redden English towns. Fallout analysts have long traced radioactive debris from bomb tests - and more recently from the Chernobyl reactor accident - around the world. A volcano's dust can veil a hemisphere and even cross the equator. But the range of human pollution has been surprising.
Arctic haze has sources in North America, Europe, and Eurasia. Some of its strongest input comes from Siberia. The haze contains industrial soot whose absorption of solar heat may slightly warm the summer Arctic air.
Russell Schnell of the National Oceanic and Atmospheric Administration - leader of the US contribution to a multinational Arctic study - reports that some of the haze has more carbon than does air flowing out to sea from New Jersey.
Donald Thornton of Drexel University, who joined in the studies, found 67 percent higher concentration of sulfur dioxide in the Arctic smog than in air off the mid-Atlantic coast. The Arctic haze pollution was traced to industrial complexes and power plants in Eastern Europe and Eurasia some 4,000 miles away.
That's a wide-ranging and rapid spread for pollution that originates locally at ground level. Volcanic pollution also originates locally and close to the ground. But the force of an eruption shoots dust and sulfur dioxide high into the air where prevailing winds rapidly carry it away. R.R. Dickerson of the University of Maryland and colleagues reported in Science last January that their research shows that thunderstorms do the same thing for human pollution. Caught in the updraft and pumped out the top of the thundercloud, the pollution, like volcanic dust, moves off with the winds.
This is not the only way power plant and other pollution disperses. But it's a particularly efficient and rapid means of transport. The researchers note that, locally, this may seem to be a good thing. It can clear the air and ameliorate acid-rain effects. But by redistributing chemicals that help create ozone in the lower atmosphere, this dispersal exacerbates global air pollution. ``Thunderstorms,'' the scientists concluded, ``may transform local air pollution problems into regional or global atmospheric chemistry problems.''
In short, it's misleading to think in terms of ``my city's'' or ``your factory's'' air pollution. The dirty mess any local source throws into the air may become an international problem.
A Tuesday column. Robert C. Cowen is the Monitor's natural science editor.