How Dangerous Is the Dust from the Great Salt Lake? New Research Finds Clues

As Utah’s Great Salt Lake shrinks, exposing more of its playa, concerns are growing about dust emitted from the dry lake bed. But scientists lack the data to fully understand what pollutants are present in this airborne sediment.

Researchers at the University of Utah are trying to answer this question, and the latest findings are concerning.

Sediments in the lake’s exposed playa are potentially more harmful than other major sources of dust affecting Wasatch Front air quality, according to a study published online in the journal Atmospheric environmententitled “Evaluation of the oxidizing potential of Great Salt Lake dust”.

These sediments, once aerosolized, have higher levels of reactivity and bioavailability than those collected from other locations upstream of Utah’s major population center along the Wasatch Front. Chemical analysis also indicated the presence of numerous metals and levels of arsenic and lithium that exceed the U.S. Environmental Protection Agency’s regional screening levels for residential soils.

“This is a very large dust source located near a very large population, and you have high levels of manganese, iron, copper and lead. Lead is a concern for development reasons,” said lead author Kerry Kelly, professor of chemical engineering.

“Manganese, iron and copper are transition metals that are known to be very irritating to the lungs. Once irritated, this can lead to an inflammatory response. This is part of the problem with fine particles and their adverse health effects, such as asthma.”

The Great Salt Lake is a terminal basin that receives runoff from a large drainage basin that spans northern Utah and parts of three other states. Metals from natural sources and human disturbances are pushed into the lake by atmospheric inputs or deposition, and these materials accumulate in the lakebed. The risk of harmful dust pollution has become a priority for Utah state officials, who have issued a list of priorities aimed at addressing the problem.

Another recent study by sociology professor Sara Grineski found that lake-bottom dust disproportionately affects poor neighborhoods in Salt Lake County.

In a separate upcoming study led by Utah biologist Michael Werner’s lab, another team of researchers characterized levels of toxic metals deposited in submerged lakebed sediments sampled during the lake’s record low water year in 2021, noting how those levels have changed since Utah’s mining-era years.

Concentrations of some metals, such as lead and zinc, appear to have declined, likely reflecting the decline in mining activity in the area, while mercury levels have increased surprisingly.

The researchers cautioned that they can’t determine whether these pollutants are actually being carried to populated areas during the high winds because monitoring equipment to capture the dust hasn’t been adequately deployed downwind of the lake. Most of the high winds come from the southwest, blowing north from the lake to Weber or Box Elder counties for several hours before shifting south as the front passes.

To conduct the study, Kelly’s air quality lab teamed up with researchers from Utah State University’s College of Science. They examined sediment samples previously collected from the Great Salt Lake, comparing them to other dust sources in the Great Basin: Sevier Lake, Fish Springs Lake and the Western Desert in western Utah, and Tule Lake in northeastern California. These locations are known to contribute to the dust pollution that reaches Salt Lake City.

In recent years, co-author Kevin Perry, a professor of atmospheric sciences, has been systematically collecting sediment exposed from the lake floor, cycling hundreds of miles. His previous research has identified “hot spots” on the playa that appear to be enriched with potentially toxic elements.

According to Perry, only 9 percent of the exposed lake bed, or 175 square kilometers (about 43,000 acres), emits dust from areas where the lake bed crusts are disturbed. The rest of the playa is covered by a natural hardened layer that holds the sediment in place.

Perry’s ongoing research is examining what happens to the playa crusts over time. He said his early findings indicate that the broken layers resettle fairly easily, suggesting that the playa’s threat to air quality may not be as dire as previously thought.

The latest study is the first to analyze the “oxidative potential” of dust, a measure of its ability to react with oxygen.

“When you breathe in something that’s really reactive, it’s going to interact with the cells inside your lungs and it’s going to cause damage,” Kelly said.

In the lab, the team aerosolized the sediment samples to isolate particles small enough to be inhaled and lodge in lung tissue, those smaller than 10 micrometers, or PM₁₀.

These particles were captured on filters and further analyzed using a method called inductively coupled plasma mass spectrometry to determine their elemental composition and further tests to determine their oxidative potential (OP) and bioaccessibility.

“We developed a way to dissolve the metals using increasingly caustic acids to see how much of these metals are leaching out of the particles,” Perry said. “It turns out that the Great Salt Lake dust contains more leachable and bioavailable metals than we would like.”

Meanwhile, high OP content has been detected in dust associated with certain metals, including copper, manganese, iron and aluminum.