Thursday, May 04, 2006

Atmospheric Pollution Travels to Mountains

By Susan Gordon
The Tacoma News Tribune

May 3, 2006

Winter snow falling on Mount Rainier and other high-elevation parks in Western states is contaminated with minute amounts of agricultural pesticides.

Recently published scientific research shows some of the compounds detected are so dangerous that they are banned in the United States.

“We thought these areas were pristine, and they’re not,” said Barbara Samora, Mount Rainier National Park biologist.

Scientists have not determined how the contaminated snow affects plants, fish and wildlife in the park, but plan to study the consequences. There’s no immediate risk to human health, the scientists say.

Researchers found a correlation between regional farm practices and concentrations of contaminants in winter snowfall at Mount Rainier and three national parks in California, Colorado and Montana.

While the results underscore the regional effects of pesticide use, scientists have not ruled out the influence of pollution from other parts of the world. That is a focus of related atmospheric research.

The pesticide analysis is based on seasonal snowfall samples collected three years ago. On Mount Rainier, a team of researchers climbed to Alta Vista – a viewpoint 5,676 feet above sea level, between Paradise and Camp Muir – and collected snow samples. Two such treks took place in March 2003.

Snow samples from all of the parks showed tiny concentrations of pesticides, measured in fractions of nanograms. A nanogram equals 1 billionth of a gram.

“These may well be the cleanest snows anywhere in the U.S., so the exposure we receive in urban areas is probably higher,” said Dan Jaffe, a University of Washington atmospheric chemist who read the report.

The lead scientist, Kim Hageman, an Oregon State University chemist, analyzed snow samples from seven parks, including three in Alaska. She tested for 47 organic compounds. Of those, eight stood out. Four are banned but persist in the environment.

To identify the source of the contaminants, Hageman compared data on agricultural activity within a radius of about 93 miles of each of the parks.

She found the highest concentrations of pesticides in snow from parks near farmlands.

“Clearly, regional U.S. and Canadian agricultural practices, both past and present, play a significant role in contributing to the accumulation of pesticides in the seasonal snowpack,” Hageman wrote.

Because there’s no farmland near Alaskan parks, scientists concluded that contamination in snow there originates elsewhere.

Hageman detected the highest concentrations of pesticides in snow from Sequoia National Park in California, near the Central Valley, which is largely agricultural.

Mount Rainier is affected by both regional and long-range atmospheric transport of chemical contaminants, Hageman said.

“The more cropland, the more concentration in a nearby national park,” she said.

Findings

The most commonly found pesticides in current use were:

Dacthal or DCPA. A weed killer used by onion and turf growers.

Chlorpyrifos, marketed as Dursban and Lorsban. An insecticide used on tree fruits, corn, grapes and mint.

Endosulfan, marketed as Thiodan and other brand names. An insecticide and wood preservative used on tree fruits, grapes and potatoes.

Gamma-Hexachlorocyclohexane, also known as HCH, marketed as Lindane. An insecticide and seed treatment used in grain production.

Of the banned pesticides, the most commonly detected were:

Dieldrin, also known as Aldrin. An insecticide formerly used on corn and as a wood preservative.

Alpha-Hexachlorocylclohexane (HCH), also known as benzene hexachloride or BHC. Derives from a technical grade of the compound formerly used as a broad-spectrum insecticide.

Chlordane, an insecticide. A persistent toxic compound formerly used to kill termites and used on agricultural crops and on turf. It also was sold to consumers for lawn and garden application.

Hexachlorobenzene, or HCB. An insecticide or fungicide. Formerly used on wheat. Scientists did not measure this compound in snow from Mount Rainier.

ON THE NET

For information on National Park Service studies of airborne contamination in Western national parks, go to www2.nature.nps.gov/air/Studies/air_toxics/wacap.cfm.

0 Comments:

Post a Comment

Links to this post:

Create a Link

<< Home