The 8,000-Year History of Great Salt Lake and its Watershed is Recorded in Sediments
upstart writes:
Photo of Great Salt Lake, taken in 2020, shows how the rail causeway built in 1959 has divided the lake into bodies with much different chemistries. On the right is lake's North Arm, which has no tributaries other than what flows through an opening in the causeway from the South Arm and consequently has much higher salinity. The red tint comes from halophilic bacteria and archaea that thrive there.
Over the past 8,000 years, Utah's Great Salt Lake has been sensitive to changes in climate and water inflow. Now, new sediment isotope data indicate that human activity over the past 200 years has pushed the lake into a biogeochemical state not seen for at least 2,000 years.
A University of Utah geoscientist applied isotope analysis to sediments recovered from the lake's bed to characterize changes to the lake and its surrounding watershed back to the time the lake took its current shape from the vast freshwater Lake Bonneville that once covered much of northern Utah.
"Lakes are great integrators. They're a point of focus for water, for sediments, and also for carbon and nutrients," said Gabriel Bowen, a professor and chairman of the Department of Geology & Geophysics. "We can go to lakes like this and look at their sediments and they tell us a lot about the surrounding landscape."
Sedimentary records provide context for ongoing changes in terminal saline lakes, which support fragile, yet vital ecosystems, and may help define targets for their management, according to Bowen's new study, published last month in Geophysical Research Letters.
This research helps fill critical gaps in the lake's geological and hydrological records, coming at a time when the drought-depleted level of the terminal body has been hovering near its historic low.
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