Water scarcity footprint of dairy milk production in New Zealand - A comparison of methods and spatio-temporal resolution

Water scarcity footprinting now has a consensual life cycle impact assessment indicator recommended by the UNEP/SETAC Life Cycle Initiative called AWaRe. It was used in this study to calculate the water scarcity footprint of New Zealand (NZ) milk produced in two contrasting regions; "non-irrigated moderate rainfall" (Waikato) and "irrigated low rainfall" (Canterbury). Two different spatial and temporal resolutions for the inventory flows and characterisation factors (CFs) were tested and compared: country and annual vs. regional and monthly resolution. An inventory of all the consumed water flows was carried out from cradle to farm-gate, i.e. from the production of dairy farm inputs to the milk and meat leaving the dairy farm, including all water uses on-farm such as irrigation water, cow drinking water and cleaning water. The results clearly showed the potential overestimation of a water scarcity footprint when using aggregated CFs. Impacts decreased by 74% (Waikato) and 33% (Canterbury) when regional and monthly CFs were used instead of country and annual CFs. The water scarcity footprint calculated at the regional and monthly resolution was 22 L_{world eq}/kg FPCM (Fat Protein Corrected Milk) for Waikato milk, and 1118 L_{world eq}/kg FPCM for Canterbury milk. The contribution of background processes dominated for milk from non-irrigated pasture, but was negligible for milk from irrigated pasture, where irrigation dominated the impacts. Results were also compared with the previously widely-used Pfister method (Pfister et al., 2009) and showed very similar ranking in terms of contribution analysis. An endpoint indicator was evaluated and showed damages to human health of 7.66 × 10^-5 DALY/kg FPCM for Waikato and 2.05 × 10^-3 DALY/kg FPCM for Canterbury, but the relevance of this indicator for food production needs reviewing. To conclude, this study highlighted the importance of using high-resolution CFs rather than aggregated CFs.

The water footprint of lithium extraction technologies: Insights from environmental impact reports in Argentina's salt flats

This study estimates water consumption in two lithium mines (Olaroz and Fénix) that use different extraction technologies in Argentina's salt flats. Based on Environmental Impact Reports (EIRs), we assess the water footprint (WF) and brine consumption (BC) in both mines. To the best of our knowledge, this study is the first to estimate WF and BC for lithium extraction and provides data to assess water consumption and better understand its implications for local ecosystems and communities. We also contextualize freshwater consumption in lithium extraction projects by estimating the blue water intensity (WIblue) and the population equivalent (PE), namely the number of local inhabitants that would consume an equivalent volume of water. Total WF was 51.0 and 135.5 m3/ton of lithium carbonate (Li2CO3) for Olaroz and Fénix, respectively. Per unit of product, WF was 2.7 times higher in Fénix but BC was higher in Olaroz. WIblue indicates that, while Fénix had a higher WFblue, its impact on local blue water availability is moderate due to greater local water availability. WFblue in Olaroz and Fénix was equivalent to the water consumption of 32,238 and 141,047 inhabitants of their nearest towns (Susques and Antofagasta de la Sierra, respectively, both with a current population of less than 2,100 inhabitants). Our findings underscore that the water consumption of lithium mining can have important impacts that vary significantly with geographic context. EIRs provide a useful basis for estimating WF and BC, though certain limitations and challenges persist, particularly regarding incomplete or insufficiently detailed data.