Spatiotemporal patterns of lithium mining and environmental degradation in the Atacama Salt Flat, Chile

Abstract

Emerging electric-vehicle technologies and the global transition to renewable energy have driven the production of lithium batteries significantly in the past ten years. However, potential adverse impacts accompanying this transition require closer scrutiny. The purpose of this research is to assess the environmental impact and its possible correlation with lithium mining in the Atacama Salt Flat, the world’s largest lithium extraction site. Using both Landsat imagery and MODIS land products, we investigate the mining areas to (1) determine area and rate of change over time, (2) analyze spatiotemporal patterns of changes in key environmental parameters, and (3) perform regression analysis between lithium mining activities and environmental degradation between 1997 and 2017. We use five environmental parameters for our analysis: Normalized Difference Vegetation Index (NDVI), Daytime Land Surface Temperature (Day-LST), Soil Moisture Index (SMI), Nighttime Land Surface Temperature (Night-LST), and Net Evapotranspiration (ET). Our analysis shows that lithium mining operations have expanded rapidly by 7.07% annually. Our pixel-based time-series trend analysis for each image stack, using the Mann-Kendall test and Sen’s slope coefficient, shows some significant degradation over the past 20 years including (1) vegetation decline, (2) elevating daytime temperatures, (3) decreasing trend of soil moisture, and (4) increasing drought condition in national reserve areas. However, no substantial degradation in nighttime-LST and ET is observed in the study area. Our analyses of the relationship between mining activities and environmental degradation also indicate that the continuous expansion of lithium mining has strong negative correlations with the NDVI and SMI, and a strong positive correlation with LST. We identified lithium mining activities as one of the major stressors to the local environmental degradation. The results provide a baseline to evaluate future socio-environmental impacts of lithium mining in the region. We anticipate our analysis will help inform mining and environmental regulators, lithium industry decision-makers, and national park managers to provide better management of the world’s largest lithium production sites for a sustainable future.