Scientists have long recognized that many pollutants travel far from where they originated. Power plant emissions can be carried by winds to distant states, where they contribute to acid rain, ground-level ozone, or mercury in isolated lakes. That’s why some of our national parks, even though they are protected areas, have smog and haze problems.
The challenge for scientists is teasing out the sources of pollution once they have dispersed. Although some elements carry isotopic signatures, others do not; so it’s challenging to trace pollutants like lead or compounds like nitrogen oxides back to their precise source.
The earthquake and tsunami that damaged the Fukushima nuclear power plant in Japan last year provided an inadvertent demonstration of how air currents can transport pollution over long distances. Within a week of the earthquake, radioactive material was found in rainfall on the west coast of North America. It was in such small concentrations that it didn’t pose a health hazard. But the point is that, because there was no other possible source for the radioactive material, it served as a tracer. Meteorologists noted a strong jet stream over Japan in the days after the disaster; it carried the contaminants across the Pacific where they were then deposited in rainfall.
Although this fallout did not prove hazardous to Americans, the story is a sobering reminder that ocean and air currents are powerful mechanisms for moving pollution. We can’t control or regulate them. It is also a reminder that no matter how safe the nuclear power industry portrays itself to be, all of the safeguards in the world could not prevent the disaster that unfolded in Japan.
Web Link
Scientific paper on Fission-Product Isotopes from Fukushima to U.S.
http://pubs.acs.org/doi/abs/10.1021/es203217u
Photo, taken on May 20, 2007 using a Nikon Coolpix L5, courtesy of J. Brew via Flickr.