Scientists have found that sediments from the Great Salt Lake’s exposed playa have a heightened ‘oxidative potential,’ suggesting a greater health risk to humans compared to other dust sources impacting Salt Lake City.
With the Great Salt Lake in Utah diminishing, the dust from the now-exposed lakebed becomes a growing concern. However, scientists currently lack the necessary data to comprehend the pollutants in these airborne sediments thoroughly.
Researchers at the University of Utah are working to address this issue, and their most recent findings are troubling.
The sediments found in the exposed playa of the lake may pose a greater danger than other significant dust sources affecting the air quality in the Wasatch Front, as discussed in a new study published in the journal Atmospheric Environment.
When the sediments become airborne, they exhibit increased reactivity and bioavailability compared to dust gathered from other regions upwind of Utah’s main population areas along the Wasatch Front. Chemical analyses also revealed various metals, including arsenic and lithium, at levels that surpass the U.S. Environmental Protection Agency’s recommended soil screening thresholds for residential areas.
“A significant dust source is located near a large population, with elevated levels of manganese, iron, copper, and lead, which raises developmental concerns,” explained senior author Kerry Kelly, a professor of chemical engineering. “Manganese, iron, and copper are transition metals known to irritate lungs. This irritation can trigger an inflammatory response, which contributes to health issues related to particulate matter, including asthma.”
The Great Salt Lake is a terminal body of water receiving runoff from a vast drainage area covering northern Utah and parts of three other states. Both natural and human-made metals flow into the lake through runoff or atmospheric deposition, accumulating in the lakebed. Addressing the potential for harmful dust pollution has become a priority for Utah state officials, who have outlined specific steps to tackle the issue.
Additionally, a recent study led by sociology professor Sara Grineski indicated that dust from the lakebed disproportionately impacts disadvantaged communities in Salt Lake County.
In a separate upcoming research project led by biologist Michael Werner’s lab at the University of Utah, researchers analyzed toxic metals found in submerged lakebed sediments taken during 2021, which marked a record low water level for the lake. These findings revealed changes in metal levels since Utah’s mining peak, showing a decline in some metals like lead and zinc, likely due to reduced mining activity, while mercury levels had surprisingly increased.
Researchers warned that they cannot definitively determine whether these pollutants are being carried into populated areas during windy conditions, as monitoring gear to capture this dust has not yet been adequately placed downwind of the lake. Most strong wind events come from the southwest, blowing for several hours off the lake into Weber or Box Elder County before shifting south once the front passes.
For this published study, Kerry Kelly’s team, which focuses on air quality, collaborated with researchers from the University of Utah’s College of Science. They analyzed previously collected sediment samples from the Great Salt Lake and compared them with dust samples from other known contributors of pollution in the Great Basin, including Sevier Lake, Fish Springs Lake, and Tule Lake.
In recent years, co-author Kevin Perry, a professor of atmospheric sciences, has systematically collected exposed lakebed sediments, logging hundreds of cycling miles. His previous research has identified “hotspots” on the playa potentially enriched with harmful elements.
According to Perry, only 9% of the exposed lakebed, which is about 175 square kilometers (approximately 43,000 acres), emits dust from disturbed crust areas, while the rest has a natural hardened layer that stabilizes sediment. Perry’s ongoing research looks at the changes in these playa crusts over time, with initial findings suggesting that damaged layers can regenerate easily, indicating that the playa’s threat to air quality may not be as severe as initially assumed.
The current research is the first to evaluate the dust’s “oxidative potential,” a measure of how reactive the dust is when it interacts with oxygen.
“Inhaling highly reactive substances can harm lung cells and cause damage,” Kelly stated.
In the lab, the team aerosolized sediment samples to isolate particles small enough to be inhaled and trapped in lung tissue, specifically those smaller than 10 micrometers, known as PM10.
These particles were collected on filters and analyzed through inductively coupled plasma mass spectrometry to determine their elemental composition and through additional tests to assess their oxidative potential (OP) and bioaccessibility.
“We developed a method to dissolve metals using progressively harsher acids to determine how much metal can leach from the dust,” Perry noted. “It turns out that the dust from the Great Salt Lake contains more leachable, bioavailable metals than we would prefer.”
High oxidative potential was found in dust linked to certain metals, including copper, manganese, iron, and aluminum.
