The hydrological impact of lithium brine mining has been uncovered in a groundbreaking study by Researchers from the University of Massachusetts Amherst, in collaboration with the University of Alaska Anchorage.
Since lithium is the key component of the lithium-ion batteries, which are crucial for the transition away from fossil fuels and towards green energy, researchers said it is critical to fully understand how to responsibly obtain the precious element.
Previous studies have not addressed two of the most important factors in determining whether lithium is obtained responsibly: the age and source of the water the lithium is found in.
This first-of-its-kind study is the result of more than a decade of research, and it suggests that total water usage in the Salar de Atacama is exceeding its resupply – though, as the team also points out, the impact of lithium mining itself is comparatively small.
Lithium mining accounts for less than ten per cent of freshwater usage and its brine extraction does not correlate with changes in either surface water features or basin water storage.
More than 40 per cent of the world’s proven lithium deposits are located in the Salar de Atacama, a massive, arid Chilean salt flat encompassing approximately 850 square miles, and 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 several 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 disturbing both the ecological health of the region and the indigenous ways of life.
And yet, up until now, there has been no comprehensive approach to gauging water use or lithium mining’s impact in the Salar de Atacama.
“To understand the environmental effect of lithium mining, we need to understand the hydrology in the region where the lithium is found. That hydrology is much more complex than previous researchers have given it credit for,” Brendan Moran, a postdoctoral research associate in geosciences at UMass Amherst and the lead author of the paper said.
To illustrate the complexity, and the previous misconception about the Salar de Atacama’s hydrology, Moran and Boutt draw on the metaphor of a bank account.
Imagine that you get a paycheck every month; when you go to balance your cheque book, 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 responsible 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 subsurface aquifers, Moran and his colleagues discovered that though localised, 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 groundwater so old, the overall hydrological system responds very slowly to changes in climate, hydrology and water usage,” Mr Moran said.
“At the same time, short-term climate changes, such as the recent major drought and extreme precipitation events, can cause substantial 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.”
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, rain gauges, and satellite measurements to determine changes in precipitation 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. Potential impacts could last decades into the future,” Mr Moran said
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,” Mr Boutt said.
