The world’s largest known lithium deposit, buried beneath Bolivia’s iconic Salar de Uyuni salt flat, is emerging as a site of growing environmental concern as demand for the metal surges globally. While lithium is central to the transition toward electric vehicles and renewable energy storage, new scientific findings suggest that its extraction may quietly amplify toxic risks that extend well beyond mining zones.
The Salar de Uyuni, famous for its vast white landscape and mirror-like reflections during seasonal rains, holds highly saline groundwater rich in lithium. Mining operations pump this brine from depths of up to 50 metres into large evaporation ponds, where sun and wind concentrate lithium by removing water and crystallising unwanted salts. The final concentrate is processed into lithium carbonate for battery production, while leftover brines remain on site.
A long-term study led by Duke University researcher Dr Avner Vengosh examined chemical changes across the lithium extraction process, from raw underground brine to waste streams produced at processing plants. The research revealed that as lithium becomes more concentrated, the brine also becomes significantly more acidic, with pH levels dropping from near-neutral conditions to as low as 3.2 in later evaporation ponds.
One of the most alarming findings was the sharp rise in arsenic levels during concentration. While natural brine contained arsenic levels between one and nine parts per million, concentrations in the final ponds reached nearly 50 parts per million. Such levels pose a serious threat if leaks or discharges occur, as arsenic can spread across the salt crust where insects, algae, and birds feed.
The study warns that toxic metals can move through food chains in salt-flat ecosystems. Laboratory tests showed that brine shrimp, a key food source for flamingos, could tolerate arsenic only up to a limited threshold. Higher concentrations reduced survival, raising concerns that contamination at lower levels of the food web could ripple upward, affecting wildlife populations across the region.
Wastewater management adds another layer of complexity. Unlike pond brines, some wastewater from lithium processing plants is highly alkaline, which can alter how metals dissolve or settle. Reinjecting waste brine underground also carries risks, including clogging subsurface flow systems or diluting remaining lithium reserves.
Researchers further caution that large-scale brine extraction may contribute to land subsidence and falling water tables, potentially drying out nearby wetlands and freshwater wells. Indigenous communities living around the Salar de Uyuni depend on limited water supplies for drinking, farming, and grazing, making them especially vulnerable to contamination or hydrological changes.
While scientists acknowledge lithium’s importance for global energy security, they stress that sustainable extraction is critical. The study highlights the need for stricter waste containment, careful testing of reinjection strategies, and continuous environmental monitoring involving local communities. Without such safeguards, the process of harvesting lithium could undermine both fragile ecosystems and human health in one of the world’s most unique landscapes.