University of Washington atmospheric researcher Daniel Jaffe said scientists previously thought banning substances like DDT and dieldrin would lessen the persistence of chemicals in the environment.
"We replaced them with pesticides with much shorter lifetimes in the environment," Jaffe said. "But in places like the Central Valley of California, we are applying many, many tons of these every year. ... We now know they can move substantial distances."
Higher Elevation, Higher Risk
A parks advocacy group called the federal report "a wake-up call" that should mobilize Congress to take a tougher stance on air pollution.
"We can take steps to reduce mercury emissions from power plants, steps to reduce carbon dioxide emissions that cause global warming," said Will Hammerquist with the National Parks Conservation Association.
The six million U.S. dollar study is known as the Western Airborne Contaminants Assessment Project. It is the most comprehensive to date on the distribution and concentration of contaminants outside developed areas, according to the project's scientific director, Dixon Landers with the Environmental Protection Agency.
Contrary to the conventional wisdom that remoteness means less pollution, Landers said many of the parks—particularly those at higher elevations and in colder climates—actually are at higher risk.
Mercury from power plants in China, for example, is borne across the Pacific in clouds that rise up when they hit West Coast mountains. That causes the mercury to drop out of the clouds attached to rain droplets or snowflakes, he said.
Release of the study, which was coordinated by the National Park Service, came after a delay of several months. A Park Service spokesperson, Colleen Flanagan, said the delay was caused by the time needed to analyze the vast volumes of data collected, from 2002 to 2007.
The study also included researchers from the U.S. Geological Survey and the U.S. Forest Service.
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