Threats and Shifts in Microbial Communities of Salars Associated With Direct Lithium Extraction and Brine Reinjection.

Lithium is a much in-demand element that is critical for the transition toward low-carbon energy systems. Beyond hard-rock mining, large quantities of lithium are extracted from brines of high-Andean salars (salares). The functioning of these microbial ecosystems depends on a delicate equilibrium between mineralogy, water, physical conditions, and microbial life. They are polyextreme environments where life thrives under limiting conditions. In the Salar de Atacama, Chile, lithium is generally extracted through sequential brine evaporation, where lithium is enriched from ∼0.2 to ∼6% w/w. This process has been associated with significant environmental and social consequences, leading to growing interest in implementing new processes, such as direct lithium extraction (DLE), promoted as 'environmentally friendly' alternatives. However, this involves the use of chemical reagents and the reinjection of treated brines into the salar, which may have ecological implications that have not yet been fully evaluated. Here, we analyse the main DLE techniques and their potential consequences for microorganisms at community and cellular levels. We argue that DLE technologies, though presented as sustainable alternatives, could potentially have environmental impacts and that current lithium extraction practices continue to conflict with several Sustainable Development Goals.