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Stefan Debruyne, a business development director at SQM, says that the company’s data show that the mixing zone has prevented its pumping from shrinking water supply. Even within the salt flat, he says, brine extraction in the middle of the flat has no impact on brine on the edges where flamingos live.
However, in a series of studies, University of Vienna postdoctoral geosciences researcher Miguel Ángel Marazuela found companies are pumping brine so fast that it may be jeopardizing the balance.
When brine is pumped out, the water table drops, and less water evaporates naturally from below the surface. Initially, the lower evaporation can compensate for the drop in water level from companies’ brine pumping. But when the water table drops below two meters deep, the evaporation rate hits zero — no more water can evaporate. At this point, Marazuela concludes, dropping evaporation rates can no longer counteract the effects of brine pumping. Freshwater pools may soon begin losing water.
“We need to think [of] the system as a whole, as a complex ecosystem unit instead of seeing it as compartments, because at some point those things are related,” said Dorador.
In December 2019, an environmental court upheld a complaint by Indigenous communities that SQM was overdrawing brine. In the midst of the legal battle, the nation’s environmental regulator announced it would conduct the region’s first comprehensive management plan. It was a tacit recognition that the country didn’t know enough about the salt flat to approve the recent expansion of lithium production. Indigenous groups called on the government to revoke SQM’s environmental permit.
Few expect the lithium producers to leave or reduce production. Instead, Bitran says, mining companies could collaborate to secure water for their operations and invest in water mining technology that reduces brine use. The companies say there is no other technology proven at scale. Others have said that companies could potentially re-inject the water that typically evaporates and improve the capture of lithium from salts.
Mining companies have responded to the pressure. Copper miners, which once used more freshwater for their operations than lithium producers, have begun using desalinated seawater. SQM made an online monitoring system about its salt flat operations available to the public in August, and in October, the company said it would reduce brine pumping by 20 percent this year and by 50 percent by 2030, without reducing lithium output.
“We can’t understand the [salt flat] with only what’s right there,” Muñoz Coca said.
“If brine was recognized as a vital element that allows the existence of other ways of life, that would be fair both for science and also for the Indigenous peoples, and so for the health of the territory,” he added.
Local groups can wield an Indigenous rights law to exercise control over the salt flat’s resources, but lithium brine falls through the cracks, just as it has with Chile’s water and mining codes. With the overwhelming support of citizens, the government may be on track to rewrite its constitution and question its long tradition of privatizing natural resources.
In Chile, water rights depend on use. Citizens can buy, sell, and even take out mortgages on naturally occurring water, if they can prove they will use it. Under an Indigenous rights law, Atacameños can earn legal water rights if they prove a long history of water use. Brine is primarily used by companies, but growing scientific evidence suggests that it impacts usable water. Customary law would in theory grant Indigenous groups the rights to lagoons in the basin, but the state claims ownership.
“So it’s a fairly straightforward colonial situation,” said Alonso Barros. As an attorney, he has advised Indigenous groups for two decades.
With a long history of negotiating with copper miners, the Atacameños have been the most successful in engaging with the mining sector, Barros says. But lithium isn’t like copper. “Water is owned by Indigenous people, but the [brine] has somehow been taken out of this equation because it’s invisible,” he said.
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原文来源：https://undark.org/2020/12/21/chile-debate-over-lithium-brine/
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