Researchers find the West is dustier than it was before
The amount of dust being blown across the landscape has increased over the last 17 years in large swaths of the West, according to a new study led by the University of Colorado Boulder.
The escalation in dust emissions — which may be due to the interplay of several factors, including increased windstorm frequency, drought cycles and changing land-use patterns — has implications both for the areas where the dust is first picked up by the winds and for the places where the dust is put back down.
“Dust storms cause a large-scale reorganization of nutrients on the surface of the Earth,” said Janice Brahney, who led the study as a CU-Boulder doctoral student.
The research team set out to determine if they could use calcium deposition as a proxy for dust measurements. Calcium can make its way into the atmosphere — before falling back to Earth along with precipitation — through a number of avenues, including coal-fired power plants, forest fires, ocean spray and, key to this study, wind erosion of soils.
Brahney and her colleagues reviewed calcium deposition data from 175 NADP sites across the United States between 1994 and 2010, and they found that calcium deposition had increased at 116 of them. The sites with the greatest increases were clustered in the Northwest, the Midwest and the Intermountain West, with Colorado, Wyoming and Utah seeing especially large increases.
The scientists were able to determine that the increase was linked to dust erosion because none of the other possible sources of atmospheric calcium — including industrial emissions, forest fires or ocean spray — had increased during the 17-year period studied.
The increase in dust erosion matters, said Brahney, who is now a post-doctoral researcher at the University of British Columbia, because it can impoverish the soil in the areas where dust is being lost. Wind tends to pick up the finer particles in the soils, and those are the same particles that have the most nutrients and can hold on to the most soil moisture.
Where the dust travels to is also affected, though the impacts are more mixed. When dust is blown onto an existing snowpack, as is often the case in the Rockies, the dark particles better absorb the sun’s energy and cause the snowpack to melt more quickly. But the dust that’s blown in also brings nutrients to alpine areas, and the calcium in dust can buffer the effects of acid rain.