Facing the current context of increased water scarcity, the use of seawater, especially in mining operations located in arid regions such as northern Chile, is continuously gaining relevance. Seawater uses in copper mining in Chile was 25% of the make-up water in 2019 and is expected to reach 43% by 2029, some of it without any treatment.
The increased use of untreated seawater in mining operations can cause groundwater quality changes in mine areas similar to those observed in coastal aquifers, and therefore, suitable tracers must be used for the early identification of mine-impacted water.
Early-warning systems in mine sites use physico-chemical indicators to trace mine-impacted water flow in the environment. Typical indicators used in Chile monitor changes on water level, water temperature, pH and the concentration of different ions (e.g. SO4, Cu, Fe) with respect to baseline values, independently of the physicochemical processes occurring along the flow path. However, it is well known, that different geochemical processes occur when mixing seawater and continental water, producing mixed solutions with solute contents far apart from that predicted by the conservative groundwater-seawater mixing line. Therefore, another approach to choose parameters considering their geochemical behaviour is needed.
