A giant haboob engulfs Gilbert, Arizona, a suburb of Phoenix, 25 July 2012. Photo: Saija Lehtonen

By Henry Gass and ClimateWire 
30 July 2013

(Scientific American) – When Rose Eitmiller found a new house on Sweet Pea Lane in Dewey-Humboldt, Ariz., population 3,613, she felt at home. She was still mourning the death of a daughter whom she always called "Sweetpea," and the place seemed right to her.

But that move in 2004 only brought more heartache for Eitmiller. Four years later, U.S. EPA dug up her front lawn in a successful search for arsenic, and Dewey-Humboldt soon became a Superfund site.

Now the town is one of several locations in the western United States that scientists say could become a major source of airborne arsenic poisoning due to global warming and breakneck human expansion.

"If arsenic's in the air, if all that stuff is in the air, there's really nothing you can do," Eitmiller said. "That's the sad thing, you really can do nothing once you're here, and I've been here going on nine years."

Arsenic ore is present throughout nature, and rainfall gradually washes arsenic particles through the soil into the groundwater, often in small enough amounts that are safe for humans to consume. Sometimes this natural concentration is augmented by man-made arsenic, usually from factories, smelters or mines.

Dewey-Humboldt, nestled in the heart of the Prescott Valley between Phoenix and Flagstaff, has both natural arsenic and deposits of the toxic chemical from a retired mine and a retired smelter. Scientists from the University of Arizona are testing to see how much is getting into the air.

As global warming means rain becomes less frequent in some areas, and soil and rocks dry up, scientists think much of the arsenic that should be leaching into the groundwater will instead be blown into the air.

"Here in Dewey-Humboldt," Eitmiller said, "we're not getting the rain that we used to get."

The West is getting dustier. A recent study from the University of Colorado found that dust depositions have dramatically increased in the past 20 years, due to increased aridity, wind transport, and human activities.

Clark Lantz, a University of Arizona professor researching arsenic in dust in Dewey-Humboldt, is looking specifically for how dangerous the arsenic in the town's dust might become. By studying the composition of the dust, he's hoping to determine how likely it would be for the arsenic fractions to break away from the dirt particles that they're riding on and create greater exposure and damage to the human body.

"As climate change occurs, I think there'll be areas where it becomes more arid, and if arsenic is part of the geologic landscape it could potentially become a problem," Lantz said. [more]

How Global Warming Is Spreading Toxic Dust

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