Bedrock geochemical baseline and pre-mining risk assessment of heavy metals in a potential lithium deposit in Sonora, Mexico: Implications for sustainable resource management

The clay-hosted lithium deposit in Sonora, Mexico, represents a potential mining site for this critical mineral, which is essential for clean energy technologies and currently in high demand during the energy transition. Establishing geochemical baselines is crucial for anticipating potential environmental risks before mining and for supporting a fair and sustainable energy transition. The objective was to report lithium (Li) concentrations and establish a geochemical baseline under pre-mining conditions by analyzing spatial distribution, statistical variability, and background comparisons, and to evaluate the degree of pollution and potential environmental risks, laying a foundation for incorporating sustainable policies. Therefore, 15 samples were collected from the bedrock of the Li deposit in Sonora, Mexico, to determine the concentrations of Li and other toxic heavy metals (Cr, Co, Ni, Cu, Zn, As, and Pb). Results revealed Li concentrations ranging from 301 to 5890 ppm, and multivariate analysis showed significant geochemical associations. The calculated environmental indices (Igeo, CF, Cdeg, PLI, PINemerow, Er, and RI) showed that most elements presented low contamination and ecological risk, with only localized moderate enrichment for Ni, Cu, and Zn. In contrast, arsenic showed extreme variability and posed a potential environmental risk. Thus, this study provides evidence that bridges geoscientific analysis with sustainability policy in mining, the first link of the supply chain, strengthening the foundations for responsible Li governance in emerging clay-hosted deposits and contributing to sustainable production and consumption.