Ever wondered about the countless mysteries lurking beneath Utah’s Great Salt Lake? As the lake shrinks and exposes more of its hidden wonders, one aspect has been grabbing the attention of scientists lately: the dust released from the dried lakebed.
This is not ordinary dust. It carries certain elements that have been raising eyebrows and, more importantly, concerns. Scientists from the University of Utah have investigated what pollutants may be lurking within these airborne sediments .
And what do their findings suggest? These sediments could potentially be more harmful than other significant dust sources that affect air quality in the Wasatch Front.
Composition of the Salt Lake dust
What exactly is in these sediments? When these particles become airborne or aerosolized, they exhibit higher levels of reactivity and bioavailability than sediments from other places upwind of Utah's major population center.
Chemical analysis has helped uncover the presence of numerous metals and levels of arsenic and lithium exceeding the U.S. Environmental Protection Agency's soil residential regional screening levels.
“You’re talking about a very large dust source located next to a very large population, and you’ve got elevated levels of manganese, iron, copper and lead. Lead is a concern for developmental reasons,” said senior author Kerry Kelly, a professor of chemical engineering.
“Manganese, iron and copper, these are transition metals and are known to be very irritating to your lungs. Once you get irritation, that can lead to this whole inflammatory response. And that’s part of the problem with particulate matter and it’s adverse health effects like asthma.”
Harmful dust pollution
The Great Salt Lake is not a solitary entity; it receives runoff from a considerable drainage basin spread across northern Utah and parts of three other states.
Metals, both from natural sources and human disturbances, are pushed into the lake from inflows or atmospheric deposition, accumulating in the lakebed.
This potential for harmful dust pollution has caught the attention of Utah state officials, resulting in a set of priority goals to tackle the issue.
Social impacts of the dust
Dr. Sara Grineski, a professor of sociology, led another recent study which revealed that dust from the lakebed disproportionately impacts disadvantaged neighborhoods in Salt Lake County. It's not just about environmental impacts, but social ones too.
In a separate forthcoming study by U biologist Michael Werner’s lab, a different team of researchers dug into the history of the lakebed. They surveyed levels of toxic metals in submerged lakebed sediments from the lake's record low-water year of 2021 and noticed changes from Utah's mining era years.
While concentrations of some metals, such as lead and zinc, appear to have decreased, mercury levels have strangely increased.
Where are the pollutants going?
However, here's a twist in the tale. Experts cannot conclusively say if these pollutants are being swept into populated areas during high-wind events. Why? The answer lies in the lack of sufficient monitoring equipment to capture the dust downwind of the lake.
Researchers in Dr. Kelly’s lab, who specialize in air quality, set out to unravel this mystery. They teamed up with colleagues in the U’s College of Science.
The experts analyzed sediment samples from Great Salt Lake , comparing them with sediments from other dust sources in the Great Basin. Interestingly, only a small fraction of the exposed lakebed, around 9%, emits dust from areas where the lakebed crusts have been disturbed.
Threat level of Salt Lake dust
So, should we be worried? The initial findings suggest that the broken layers of the lakebed reset fairly easily, implying that the threat to air quality might not be as severe as previously assumed.
However, the latest study brings forth a new perspective. It explores the dust's "oxidative potential," 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 cause damage," explained Dr. Kelly.
In the lab, the team aerosolized the sediment samples to isolate particles small enough to inhale and lodge in lung tissue. Further analyses showed high oxidative potential associated with certain metals, including copper, manganese, iron, and aluminum.
The study is published in the journal Atmospheric Environment .
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