In a groundbreaking study of the South American ‘Lithium Triangle,’ scientists have discovered that different types of water react differently to changes in the environment and human activity.
A team of researchers from the University of Massachusetts Amherst, working with the University of Alaska-Anchorage and Columbia University, has conducted the most extensive hydrological tracer analysis of the Dry Andes region in Chile, Argentina, and Bolivia. These areas are home to most of the world’s lithium deposits and other essential elements, such as copper, which are crucial for the shift from oil to electricity in the green energy transition. But the Dry AndYes, hyper-arid regions like this one are very sensitive to any activities, like mining, that could disrupt the presence, composition, and flow of water. So far, there hasn’t been a reliable understanding of how the hydrological systems work in these extremely arid landscapes. This lack of information makes it difficult for environmental regulators to manage the mining industry and work towards a more environmentally sustainable future. The research is published in PLOS Water.”
“We’ve been thinking about water all wrong,Brendan Moran, a postdoctoral research associate in geosciences at UMass Amherst, is the lead author of the paper. He stated, “We typically assume that water is water, and manage all water the same way, but our research shows that there are actually two very distinct pieces of the water budget in the Dry Andes, and they respond very differently to environmental change and human usage.”
Water plays a crucial role in lithium, which is a vital component of powerful batteries used in electric and hybrid cars, as well as photovoltaic systems. Lithium tends to occur in layers of volcanic ash and does not like to be in a solid form, reacting quickly.Moran and his colleagues, along with Davi, explained that lithium is found in volcanic ash layers and can be easily dissolved in water. As rain or snowmelt pass through these ash layers, lithium is released into the groundwater and flows downhill until it settles in a flat basin as a briny mix of water and lithium. This dense brine often settles beneath pockets of fresh surface water, creating fresh and brackish lagoons and wetlands that support unique ecosystems and species like flamingos. Distinguishing between the different types of water present in these areas can be a challenge.d Boutt, who is a geosciences professor at UMass Amherst, and Lee Ann Munk, a geological sciences professor at the University of Alaska, previously created a method for determining the age of water samples and tracking their interaction with the environment using 3H, or tritium, and the ratio of the oxygen isotope 18O to the hydrogen isotope 2H. Tritium is naturally present in rainwater and decays at a known rate. According to Moran, “This allows us to determine the relative age of the water. Is it ‘old,’ meaning it fell over a century ago, or is it ‘contemporary’ water that fell just a few weeks to years ago?”
By analyzing the ratio between 18O and 2H, the team was able to track the amount of water evaporation. According to the researchers, “The 18O/2H ratio acts like a unique fingerprint, since different sources of water — such as streams or lakes — will have different ratios. This helps us determine the origin of the water and how long it has been exposed to the surface and not underground.”
For this new study, Moran and Boutt collaborated with stakeholders in the Dry Andes to collect samples from nearly every water source in the entire region — a remarkable achievement, considering the harsh and sparsely populated nature of the Dry Andes.The researchers used a method called isotopic analysis to measure the various isotopes in old and young waters. This allowed them to find out that the two types of water do not mix and behave differently. Boutt claims that the deep, old groundwater is crucial for the hydrological system in the Dry Andes. He also mentions that only 20% – 40% of the water is contemporary surface water, which is the most susceptible to climate change, storm cycles, and human activities such as mining. In the past, scientists believed that surface water was the most stable because of constant recharge from runoff. However, in extremely dry areas like the Dry Andes, this is not the case.It’s not true. The problem is, this new understanding of how water works has not been integrated into any management system anywhere. The implications are significant, and Moran states that one of the most important is to protect the various channels through which fresh rainwater flows into critical lagoons and wetlands. This means that managers need to implement different strategies for managing young and old waters, as a one-size-fits-all approach will not be effective. Boutt emphasizes the importance of what is seen in the Dry Andes as representative.The study found that the understanding of hydrology in extremely dry regions, including the western United States, is crucial for more than just lithium mining. According to Moran, water in arid regions operates in a similar manner globally, and water managers worldwide should be aware of the age and source of their waters to protect their hydrological cycles. The study was published in PLOS Water in 2024 and was authored by Brendan J. Moran, David F. Boutt, Lee Ann Munk, and Joshua D. Fisher.4): e0000191 DOI: 10.1371/journal.pwat.0000191