A geomatics approach to assess the environmental impact of lithium mining.

Nowadays, the economic development is still heavily dependent on raw materials extraction: future trends predict that the extraction of mineral resources will increase in the next decades, also due to the increase in the global population and to the transition towards clean energy. Lithium is one of the critical minerals in the energy transition, because fundamental for electric cars lithium-ion batteries. Its demand is expected to soar in a sustainable scenario that wants the global temperature rising to stay below 2°C with respect to the pre-industrial levels. The aim of this study is to show the important role of Remote Sensing and Geographic Information System (GIS) to study lithium mining and its supply chain, underlining the need to use geospatial data and tools to quantify the carbon emissions of transportation and the environmental impacts of mining activity on the land use. Two case studies have been considered, representing the two different lithium mining technologies: one in Salar de Atacama (Chile) where lithium is extracted from brine and the other one at Greenbushes (Western Australia) where lithium is extracted from ore. In Chile, an automatic way of extraction of the land disturbed by the mining activity has been carried out using several indices, evaluating which of them performs better through an accuracy assessment. In Western Australia, a manual extraction of the mine area has been performed in GIS since a lower time-consuming process is needed. Sentinel 5P satellite images have been analysed to detect if eventual atmospheric emissions can be quantified at mine sites to be integrated in the Life Cycle Assessment (LCA) analysis. Land and sea routes in the lithium supply chain have been studied and kilometres travelled by trucks and vessels have been quantified. Land disturbed by the mine activity has been linked to the production rate of the mine site, generating an indicator of the Land Use Intensity (LUI) using both mass and economic allocation methods. The global impact of carbon emissions generated from the transportation in lithium supply chain have been estimated, through the integration in a LCA analysis, using the ILCD 2011 Midpoint+ characterization method. Among all the indices used to extract the mine area in Chile, the MNDWI computed with the SWIR shows the highest accuracy, followed by the NDVI. Sentinel 5P satellite images have a spatial resolution that do not allow the identification of emissions belonging to the mine sites, underlining the need to develop higher spatial resolution data products. Land Use Intensity results are highly dependent on allocation methods: considering the results obtained with economic allocation, LUI is higher for lithium products extracted from brine in Salar de Atacama (133.4 - 142.7m2/ton) with respect to the ones extracted from ore at Greenbushes (42.7 - 48.6 m2/ton). The results of the carbon emissions analysis estimated that transportation in lithium supply chain accounts for 12.5% for lithium carbonate and 5.05% for lithium hydroxide in the Chilean pathway and respectively 3.32% and 4.29% in the Australian one. LCA results also shows that a shorter supply route in Western Australia lower the emission from 0.70 tonCO2eq/ton of lithium product to 0.18 tonCO2eq/ton. The results obtained in this work underline the importance to adopt a multidisciplinary approach in the study of mining sector and to define a common methodology and criteria to assess its environmental impacts, integrating Remote Sensing and GIS tools.