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 Lithium
Continued from page 30
deposits are located in the Salar de Atacama, the site of the research. The Salar de Atacama is host to a number of ecologically unique wildlife preserves and is also the ancestral home of sev- eral Atacameño indigenous communities, with whom the UMass team worked. Because the salt flats are so ecologically sensitive and depend on scarce supplies of fresh water, the use of water in the Salar de Atacama runs the risk of disturb- ing both the ecological health of the region and indigenous ways of life.
Yet, up until now, there has been no compre- hensive approach to gauging water use or lithi- um mining’s impact in the Salar de Atacama.
“To understand the environmental effect of lithium mining,” says Brendan Moran, a post- doctoral research associate in Geosciences
at UMass Amherst and the lead author of the paper, “we need to understand the hydrology in the region the lithium is found. That hydrology is much more complex than previous researchers have given it credit for.”
To illustrate the complexity, and the previ- ous misconception about the Salar de Atacama’s hydrology, Moran and Boutt drew on the meta- phor of a bank account. Imagine that you get
a paycheck every month; when you go to bal- ance your checkbook, as long as your monthly expenditures don’t exceed your monthly income, you are financially sustainable. Previous studies of the Salar de Atacama have assumed that the infrequent rainfall and seasonal runoff from the mountain ranges that ring it were solely respon- sible for the water levels in the salt flats, but it turns out that assumption is incorrect.
Using a variety of water tracers that can track the path that water takes on its way to the Salar de Atacama, as well as the average age of water within different water bodies, including surface waters and sub-surface aquifers, Moran and his colleagues discovered that, though localized, recent rainfall is critically important, more than half of the freshwater feeding the wetlands and lagoons is at least 60 years old.
“Because these regions are so dry, and the
than they currently do, while also paying atten- tion to major events, like droughts, in the region.
Complete hydrological monitoring requires additional tools paired with these geochemical tracers. The UMass and UAA teams used water usage data from the Chilean government and satellite imagery, which allowed them to assess the changing extent of wetlands over the past 40 years, as well as rain gauges and satellite mea- surements to determine changes in precipitation
“To understand the environmental effect of lithium mining, we need to understand the hydrology in the region the lithium is found. That hydrology is much more complex than previous researchers have given it credit for.
  ”
groundwater so old,” Moran said, “the overall hydrological system responds very slowly to changes in climate, hydrology, and water usage.”
At the same time, short-term climate changes, such as the recent major drought and extreme precipitation events, can cause sub- stantial and rapid changes to the surface water and the fragile habitats they sustain. Given that climate change is likely to cause more severe droughts over the region, it could further stress the area’s water budget.
To return to the accounting metaphor, the paycheck is likely getting smaller and isn’t com- ing monthly, but over a period of at least 60 years, which means researchers need to be mon- itoring water usage on a much longer time scale
over the same period.
Given how long it takes for groundwater
to move within the basin, “the effects of water overuse may still be making their way through the system and need to be closely monitored,” Moran said. “Potential impacts could last decades into the future.”
Ultimately, this comprehensive framework, which was funded by BMW Group and BASF,
is applicable far beyond the Salar de Atacama. “It’s a modern approach to water management,” Boutt said. u
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 32 JULY 25, 2022
TECHNOLOGY
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