Map of the study area in the southwestern United States. Dust collectors are marked by stars corresponding to their position. The background image is an atmospheric footprint map derived from HYSPLIT-STILT backward trajectory simulations denoting the frequency with which air masses crossed different landscape positions en route to the Salt Lake City/Provo urban area during the two-year duration of this study. Warmer colors (higher values) correspond to areas more likely to have served as a regional source for dust reaching the urban collectors.
Airborne dust pollution has been a concern for Utahns for several years, especially with the exposed lakebed of Great Salt Lake potentially becoming more hazardous as the lake dries. Natural dust blows from the Great Basin and settles along the western edge of the Wasatch Front, Utah’s major population center, and the surrounding mountains. While airborne, the dust mixes with local human-made materials, potentially contaminating the nearby watershed and resulting in other negative consequences, according to new research from the University of Utah that investigates the influence of urban environments on transient dust.
A study team led by U atmospheric scientist Kevin Perry and Jeff Munroe, a geology professor at Middlebury College, considered Earth’s “Critical Zone,” a near-surface layer where organisms interact with rock, air, soils and water. Dust processes such as deposition, erosion and transport influence the Critical Zone.
Dust particles are typically diverse in their composition, as they are influenced by natural environments. However, agriculture, grazing, off-roading, construction, mining and other human activities alter the dust composition, with important implications for places like Utah’s populated Salt Lake Valley.
“The problem is that there are lots of dust sources in the urban area, and when it’s windy and it’s picking up dust from Great Salt Lake and other places upstream, it gets mixed in with this local dust that has a lot more junk in it,” Perry said. “So if we think about the contaminants of concern in Great Salt Lake dust, and then you add in additional contaminants from the local dust, it just makes it that much more potent, and not in a good way.”
Home to 2.5 million people, or three-fourths of Utah’s population, the Wasatch Front is particularly susceptible to dust pollution, so it provides an ideal laboratory for investigating interactions between natural and urban dust, according to the study, which was funded by the National Science Foundation.
“Our dust comes from various sources. We have natural sources like the West Desert, the Bonneville Salt Flats, Sevier Lake, but then we also have a lot of dust from Great Salt Lake and anthropogenic dust sources, quarries at Point of the Mountain, the Staker quarry in North Salt Lake,” said co-author Derek Mallia, a research assistant professor of atmospheric sciences. “This can be locally sourced, but you can also get dust impacts from sources on the other side of the Great Basin. An artifact of being on the eastern side of the Great Basin is we’re just downwind of a ton of dust sources.”
Read the full article by Ethan Hood in @The U.