Great Salt Lake (GSL) is one of the world’s largest inland bodies of saltwater. Climate change, drought, and water diversions have caused the lake to reach historically low levels. Almost 1945 km2 of the lakebed is exposed.
Dust storms can carry particulate matter (PM) from the Great Salt Lake’s dry lakebed into nearby cities, harming air quality and health.
Researchers from the University of Utah assessed the oxidative potential (OP) of dust from the exposed lake bed compared to dust samples collected from other regional playas and to reference Arizona test dust.
The study suggests that sediments in the lake’s exposed playa are potentially more harmful than other major dust sources affecting the Wasatch Front’s air quality.
After aerosolizing, these sediments show higher levels of reactivity and bioavailability than sediments from other spots. Chemical analyses also detect the presence of several metals. The analyses also revealed that levels of arsenic and lithium exceed the U.S. Environmental Protection Agency’s soil residential regional screening levels.
Senior author Kerry Kelly, a professor of chemical engineering, said, “You’re talking about a huge 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. Manganese, iron, and copper are transition metals known to irritate 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 its adverse health effects like asthma.”
A recent study by Professor Sara Grineski found that dust from the Great Salt Lake affects poorer neighborhoods in Salt Lake County more.
In another upcoming study, Michael Werner’s lab will examine toxic metals in lakebed sediments from 2021, a year when the lake was very low. They will find that levels of some metals, like lead and zinc, have dropped due to less mining, but mercury levels have surprisingly gone up.
Researchers warned they can’t say if pollutants from the Great Salt Lake are being blown into cities because the proper monitoring equipment is not set up downwind of the lake. Most strong winds come from the southwest, blowing off the lake and moving north before shifting south.
For their study, Kerry Kelly’s lab, which focuses on air quality, worked with researchers from the University of Utah’s College of Science. They compared sediment samples from the Great Salt Lake with those from known dust sources in the Great Basin, like Sevier Lake, Fish Springs Lake, West Desert, and Tule Lake, to understand their contribution to dust pollution in Salt Lake City.
Kevin Perry, an atmospheric sciences professor, has been collecting samples from the exposed lakebed and biking hundreds of miles in recent years. His previous work has found “hotspots” on the lakebed with potentially toxic elements.
Perry reports that only 9% of the exposed lakebed, or about 43,000 acres, produces dust from disturbed areas. The rest is covered by a natural crust that keeps the dust down. His ongoing research shows that this crust breaks down and repairs itself relatively quickly, which might mean the lakebed’s impact on air quality isn’t as severe as once thought.
The latest study is the first to examine the dust’s “oxidative potential,” which measures how reactive it is with oxygen.
“When you breathe in something reactive, it’s going to interact with the cells inside your lungs, and it’s going to cause damage,” Kelly said.
The team aerosolized sediment samples to separate inhalable tiny particles- those smaller than 10 micrometers or PM10.
The particles were collected on filters and then analyzed with inductively coupled plasma mass spectrometry to identify their elements. Additional tests were used to measure their oxidative potential (how reactive they are with oxygen) and bioaccessibility (how easily the body can absorb them).
Perry said, “We devised a way to dissolve the metals using increasingly caustic acids to determine at what level these metals leach from the particles. It turns out that the Great Salt Lake dust has more bioavailable leachable metals than we would wish.”
Journal Reference:
- Reuben Attah and Kamaljeet Kaur of the Department of Chemical Engineering and Diego Fernandez of the Department of Geology & Geophysics. Assessing the oxidative potential of dust from Great Salt Lake. Atmospheric Environment. DOI: 10.1016/j.atmosenv.2024.120728
