The stakes could hardly be higher. Global lithium consumption has exploded from less than 100 tons of lithium carbonate equivalent per year at the start of the twentieth century to more than 70,000 tons annually a century later. Production figures tell the same story: roughly 6,100 tons in 1994, swelling to an estimated 290,000 tons in 2025 according to the United States Geological Survey. Demand is projected to triple by 2030, driven overwhelmingly by electric vehicle manufacturing and grid-scale battery storage. Against that backdrop, every new prospective region matters, and Indonesia, straddling the Pacific Ring of Fire, is full of volcanic systems that have never been systematically screened for lithium.

Kulon Progo is a geologically promising place to look. Two major magmatic episodes, one in the Late Oligocene to Early Miocene roughly 25 to 30 million years ago and another in the Late Miocene about 8 million years ago, built the region’s volcanic and sedimentary framework out of calc-alkaline magmas ranging from basaltic to andesitic and dacitic in composition. The key unit is the Old Andesite Formation, a package of intrusive rocks, andesitic breccias and lava flows whose association with hydrothermal alteration makes it exactly the kind of terrain where lithium enrichment is considered plausible. The region’s layered history, from the claystone and limestone basement of the Nanggulan Formation through volcanic sequences and shallow intrusions of microdiorite, andesite and dacite, created a complex plumbing system for fluids moving through rock.

The research team, led by Asep Rohiman of the Bandung Institute of Technology and the Center for Geological Survey in Bandung, combined three analytical techniques: inductively coupled plasma optical emission spectrometry, or ICP-OES, to measure trace element concentrations; X-ray diffraction to identify mineral phases; and petrographic microscopy to characterize rock textures and alteration. In July 2023 they collected 14 water samples, including one from a saline to brackish well at Banyuasin, and rock samples from 50 stations spanning volcanic and sedimentary lithologies. Sampling sites were deliberately chosen away from domestic contamination, and water samples were acidified to pH 2 or below with nitric acid to keep dissolved cations in solution and prevent iron and manganese oxyhydroxides from scavenging trace metals during storage.

The results reveal striking spatial variability. Surface waters contained lithium at concentrations from 0.01 to 0.49 parts per million, with the highest value recorded in the Banyuasin well water, sample 23AA51A. That well also carried elevated sodium, potassium, calcium, boron and sulfur, at 1,538, 24.78, 425, 5.90 and 71 parts per million respectively, and field observers described cloudy, salty water with orange sediment and gas bubbles. Because the site sits far from the coast, the researchers argue that ancient connate formation water, trapped in sedimentary rocks during diagenesis, is a more plausible explanation than seawater intrusion. The region’s tectonic history of subsidence, uplift and renewed volcanism, combined with sea-level fluctuations, likely created the conditions for such fluids to accumulate within Oligocene to Miocene volcanic rocks of the Kebobutak Formation.

The rocks themselves tell an equally interesting story. Volcanic samples contained between 5 and 57 parts per million lithium, with the highest concentration, 57 parts per million, measured in a quartz-vein sample, 23AA09A, collected where a dacite intrusion meets the Old Andesite Formation host rock near Bagelen. Petrographic analysis showed moderate to strong alteration across the samples, with hydrothermal veins of both massive and stockwork type composed of secondary quartz, iron oxide, sericite mica, pyrite and calcite. The elemental profiles of surface waters and volcanic rocks broadly mirror each other, supporting the idea that water-rock interaction is the dominant process controlling lithium mobilization, though boron and bismuth in the waters appear to come from near-surface leaching of soils and sediments rather than directly from the volcanic rocks.

One honest limitation stands out: the team could not conclusively identify which minerals actually host the lithium. X-ray diffraction patterns showed some features resembling phases known from lithium-bearing systems, but at these trace concentrations the diagnostic peaks are swamped by abundant rock-forming minerals such as quartz, feldspar and mica. That is not surprising, because in volcanic systems lithium typically substitutes as a trace element within common silicates rather than forming its own discrete minerals. It can also concentrate in secondary clays, particularly smectite and illite, produced by weathering and hydrothermal alteration. The parallels are compelling: lithium-rich illitic claystones at Thacker Pass in Nevada and smectite-illite assemblages in Clayton Valley represent some of the most significant clay-hosted lithium resources known, both formed through alteration processes. Definitive identification in Kulon Progo will require higher-resolution techniques such as electron probe microanalysis, laser ablation ICP-MS or secondary ion mass spectrometry.

The analytical rigor behind the numbers deserves attention in its own right. To validate their measurements, the researchers sent one rock sample to five ISO/IEC 17025:2017-accredited laboratories for independent ICP-OES analysis. Three of the four comparison laboratories produced results statistically indistinguishable from the reference measurements, with relative percent differences between 1.42 and 9.52 percent, all within acceptable thresholds. One laboratory diverged substantially, with a relative difference of 45.57 percent attributed to fundamentally different analytical protocols, but the consistency of the other comparisons supports the reliability of the dataset. Quality assurance also included standard addition methods with certified reference materials and proficiency testing through interlaboratory comparisons.

Why does this matter beyond Indonesia? The study demonstrates that measuring lithium in surface waters can serve as a cheap, low-impact screening tool for early-stage exploration. Instead of exhaustive rock sampling campaigns, which are expensive and environmentally intrusive, exploration teams can analyze stream and well water to flag anomalies, then concentrate detailed work on the most promising catchments. The elevated lithium in altered andesitic rocks near Kalirejo suggests just such a link between hydrogeochemical signatures and mineral sources. For a country with limited exploration budgets and vast, roadless volcanic terrain, that approach could be transformative, and the authors point toward portable electrochemical lithium sensors, adapted from rapid diagnostic biosensor platforms, as a practical next step for field deployment.

There is also an environmental dimension that extends well beyond mining. Lithium is routinely absent from water quality monitoring programs, which traditionally focus on pH, conductivity, dissolved solids and major cations, along with well-characterized heavy metal contaminants. Yet rising battery use is increasing lithium’s footprint in the environment, and elevated lithium in drinking water raises potential health questions that remain poorly understood. The Kulon Progo dataset, the first hydrogeochemical baseline for the region, therefore does double duty: it flags a possible resource and simultaneously exposes a blind spot in how we watch our water. As the energy transition accelerates, the same element that stores clean electricity may need to be tracked as carefully in rivers and wells as lead or arsenic ever were, and this small corner of Java has just shown how to start.

Subject of Research: Lithium distribution in surface waters and volcanic rocks of the Kulon Progo region, Indonesia

Article Title: Geochemical characteristics of lithium in surface waters of the Kulon Progo volcanic region for sustainable energy applications

Article References: Rohiman, A., Setiyanto, H., Kurnia, K., Sendjaja, P., Saraswaty, V., Manurung, R. V., & Amran, M. B. (2026). Geochemical characteristics of lithium in surface waters of the Kulon Progo volcanic region for sustainable energy applications. Discover Geoscience, 4(1), Article 322. https://doi.org/10.1007/s44288-026-00693-1

Image Credits: AI Generated

DOI: 10.1007/s44288-026-00693-1

Keywords: lithium, hydrogeochemistry, volcanic rocks, Kulon Progo, Indonesia, water-rock interaction, ICP-OES, X-ray diffraction, battery metals, critical minerals, sustainable energy, geochemical exploration

The study draws on an unusually rich dataset: seven years of continuous monitoring, from 2016 to 2023, covering groundwater levels, water temperature, hydrochemistry, and land surface deformation across Tongzhou’s unconsolidated sedimentary aquifer system. Such systems, built up from layers of sand, silt, and compressible clay deposited over millennia, are typical of coastal plains worldwide and are notoriously vulnerable to over-abstraction. When water is pumped from confined aquifers faster than it can be replenished, pore pressure in the aquifer skeleton drops, the soft clay layers above and between the sandy units compact, and the ground surface sinks. Reversing that process is far harder than causing it, which is why the Tongzhou findings have attracted attention among hydrogeologists.

To untangle the causes behind the observed changes, the team deployed two sophisticated statistical tools. The first was generalized additive modeling, a flexible regression framework that can capture nonlinear relationships between groundwater variables and their potential drivers without imposing a rigid mathematical form. The second was wavelet transform coherence analysis, a signal-processing technique that examines how two time series co-vary across different frequencies and over time, revealing not only whether variables are linked but whether one responds to the other with a delay. This lag-detection capability proved crucial, because groundwater systems rarely react instantaneously to changes in pumping or recharge; pressure signals propagate slowly through low-permeability clay layers, and chemical adjustments can take even longer.

The headline result is unambiguous: since abstraction limits were implemented, groundwater levels in both confined aquifers have risen significantly. That recovery set off a cascade of secondary effects. Chloride concentrations, a key indicator of salinity, have declined across the monitored system. Land surface dynamics have flipped from sinking to rising, with the rebound gradually tending toward stabilization over time. Groundwater temperature, by contrast, remained relatively stable throughout the monitoring period, a detail that turned out to be scientifically telling rather than uninteresting.

By applying their statistical toolkit to all of these variables simultaneously, the researchers identified groundwater levels as the dominant controlling factor of the entire groundwater environment. Changes in hydrochemistry and in land surface deformation were both lagged responses to level variations, meaning the chemistry and the ground surface did not simply track pumping in real time but adjusted after a delay as pressure changes propagated through the aquifer-aquitard sequence. This finding carries practical weight for water managers: it implies that the benefits of conservation measures unfold over years, and that monitoring programs must be designed to capture these delayed responses rather than judging policy success on immediate outcomes alone.

The temperature story is particularly striking. While groundwater temperatures in many urbanizing regions are warming due to the urban heat island effect, geothermal anomalies, and heat pump discharge, Tongzhou’s confined groundwater temperatures were found to be governed primarily by the geothermal gradient, the natural increase in temperature with depth, with only limited influence from human disturbances. In other words, the deep aquifer system has remained thermally insulated from the surface changes happening above it. That stability provides a useful baseline: any future thermal anomaly in these aquifers would stand out clearly against a naturally controlled background, making temperature a sensitive early-warning indicator for emerging human impacts.

Salinity dynamics revealed a more complex picture. Confined Aquifer I, the shallower of the two confined units, still carries high chloride concentrations as a legacy of historical seawater intrusion, a reminder that coastal aquifers can store the chemical fingerprints of past marine transgressions long after the inciting event. Yet even in this compromised aquifer, recovery is underway. As groundwater levels rose, chloride concentrations declined, and the team determined that during the recovery process the chloride behavior was controlled by water-rock interactions, the slow chemical exchanges between groundwater and the mineral grains of the aquifer matrix. This suggests that freshening is not merely a matter of flushing salty water out but involves ongoing geochemical equilibration as the flow regime reverses, a process that models of coastal aquifer restoration need to account for.

Perhaps the most visually dramatic finding concerns the land itself. The study attributes the observed changes in surface elevation mainly to the rebound of overlying compressible clay layers as groundwater levels in the deep aquifers recovered. The physics follows classical consolidation theory, first formulated by Karl Terzaghi a century ago: when pore water pressure in a clay layer falls, effective stress on the mineral skeleton rises and the layer compresses; when pore pressure recovers, some of that compression is elastic and can be recovered, allowing the surface to rise. The Tongzhou data show this rebound in action, with the land tending toward stability as the system equilibrates. For low-lying coastal cities already contending with sea-level rise, every centimeter of prevented or reversed subsidence matters, and the study demonstrates that subsidence can be at least partially reversible when abstraction is curtailed early enough.

The broader significance of the work extends well beyond one district on the Jiangsu coast. Coastal plains across Asia, Africa, and the Americas face the same triple threat of over-pumping, saltwater intrusion, and land subsidence, often compounded by climate change and urban growth. Many studies have documented the damage; far fewer have tracked, with high-resolution monitoring and rigorous causal analysis, what recovery actually looks like. The Tongzhou case shows that a managed aquifer system can respond coherently to policy intervention: levels rise, chemistry freshens with a lag, the ground rebounds, and the thermal regime stays steady. It also shows that the response is orchestrated by a single master variable, groundwater level, which therefore serves as the most effective lever and the most informative monitoring target.

For groundwater managers, the practical lessons are concrete. First, abstraction restrictions work, but their full benefits materialize over multi-year timescales as lagged responses play out through the aquifer system. Second, chemical recovery from historical salinization is governed by water-rock interactions and will be gradual, so expectations should be calibrated accordingly. Third, land rebound tied to clay-layer recovery offers a quantifiable measure of policy success, one that can be tracked with satellite-based deformation measurements as well as ground instruments. Fourth, stable temperatures governed by the geothermal gradient provide a clean reference against which future anthropogenic thermal impacts, from heat pump fields to urban warming, can be detected. As the authors note, these findings improve understanding of groundwater evolution in unconsolidated sedimentary aquifer systems and provide a scientific basis for groundwater management in coastal regions. In an era when roughly half of humanity lives within reach of the sea, the quiet recovery unfolding beneath Tongzhou’s fields and streets is a story worth watching, and perhaps emulating.

Subject of Research: Spatiotemporal evolution of groundwater levels, hydrochemistry, temperature, and land subsidence in a coastal aquifer system under abstraction restrictions

Article Title: The spatiotemporal evolution and controlling factors of the groundwater environment: Insights from long-term monitoring of Tongzhou District, China

Article References: Dong, L., Wu, J., Zhang, J., Luo, Z., & Li, Z. (2026). The spatiotemporal evolution and controlling factors of the groundwater environment: Insights from long-term monitoring of Tongzhou District, China. Hydrogeology Journal. https://doi.org/10.1007/s10040-026-03167-3

Image Credits: AI Generated

DOI: 10.1007/s10040-026-03167-3

Keywords: groundwater, hydrogeology, coastal aquifer, land subsidence, saltwater intrusion, chloride, water-rock interaction, groundwater management, China, wavelet coherence, generalized additive model, aquifer recovery

A new study led by Candice Bedford, a research scientist in Purdue University’s Department of Earth, Atmospheric, and Planetary Sciences, and published in Communications Earth & Environment, shows that the Margin Unit did not record a single lakeshore environment. Instead, the rocks preserve a layered history of multiple, distinct episodes in which water of different origins and temperatures moved through, altered, and reworked the crust. Groundwater percolated through fractures and left carbonate deposits behind. Lake water or evolving groundwater systems chemically transformed minerals that had formed earlier. And in a final act, warm hydrothermal fluids pushed through the fractured bedrock, depositing vein minerals that recorded yet another chapter in the crater’s watery past. The Margin Unit, the team concluded, became a kind of crossroads where several aqueous systems converged over geological time.

Bedford and an international team of collaborators pieced together this history using measurements and images from Perseverance, particularly the data returned by the rover’s SuperCam instrument. SuperCam, mounted on the rover’s mast or head, combines remote chemical analysis techniques, including laser-induced breakdown spectroscopy, with high-resolution imaging, allowing scientists to determine the composition of rocks and individual mineral grains from a distance. That capability proved essential on the Margin Unit, where the crucial evidence was written at scales invisible from orbit: fine fractures, thin mineral veins, and subtle chemical variations between grains that together revealed a sequence of water-rock interactions spanning a long stretch of Martian history.

“If there is one thing I have learned after 10 years working with Mars rovers, it is that Mars constantly throws surprises at you,” Bedford said. “It is very rare that things are as we expect them to be from orbital data. They are usually far more complex and interesting, which is what makes planetary exploration so exciting.” Her comment captures a recurring lesson of the Mars 2020 mission: orbital spectroscopy can flag promising locations, but only close-up, grain-scale analysis can reveal the true sequence of geological events preserved in the rocks.

The oldest chapter of the story begins deep underground. At higher elevations within the Margin Unit, Perseverance encountered coarse, crystalline rocks rich in olivine, an iron-magnesium silicate mineral commonly associated with igneous processes. The chemistry and texture of these olivine-bearing rocks suggest that they originally formed from a magma that cooled slowly beneath the Martian surface, allowing large crystals to grow. In other words, the foundation of the Margin Unit is not sediment laid down on a lakebed but volcanic rock crystallized in the crust, later exposed and made available for alteration by whatever water arrived afterward. This igneous starting point matters, because it gives scientists a well-defined baseline against which every subsequent chemical change introduced by water can be measured.

The first watery episode left an unmistakable signature at lower elevations. The team identified carbonate-rich ridges cutting across the bedrock, evidence that groundwater once traveled through a network of fractures and precipitated minerals along its path. Bedford offered an analogy drawn from terrestrial plumbing: “The fractures are like pipes, and the carbonate is the Mars ‘limescale’ that eventually blocked the ‘pipes’ up.” Just as hard water leaves mineral scale inside household pipes, the Martian groundwater left carbonate crusts inside its fracture conduits, gradually sealing them. These carbonate fills record the chemistry of the fluids that deposited them and, by extension, the subsurface environment of early Mars, making them prime targets in the search for conditions that could once have supported microbial life.

The story did not end with the groundwater. The rover also found widespread silica distributed through the lower-elevation rocks, along with clear evidence that previously formed carbonates had been chemically altered. That combination points to a second, later episode of water-rock interaction, one that may have involved water from Jezero’s ancient lake spilling into the margin rocks or shifts in the groundwater system itself changing the composition and flow paths of subsurface fluids. Either way, the alteration of the earlier carbonates demonstrates that the region’s water history was not a single event but a sequence of overlapping processes, each overprinting and modifying the record left by the last.

The final chapter is perhaps the most surprising. Perseverance discovered a mineral vein containing fluorite and calcium sulfate, a chemical pairing that points to a hydrothermal episode occurring after the groundwater and lake-related alteration had already taken place. Fluorite, the mineral form of calcium fluoride, typically precipitates from warm, chemically distinctive fluids, and its presence alongside calcium sulfate suggests that heated waters moved through the fractured bedrock late in the crater’s history. Hydrothermal systems are of special interest to astrobiologists because on Earth they support thriving ecosystems independent of sunlight, making similar environments on Mars compelling places to look for signs of past life. The vein indicates that even after Jezero’s lake had faded from the scene, the crust beneath it remained geologically and hydrologically active.

Taken together, the findings fundamentally reshape how scientists view the Margin Unit and, by extension, the history of water in Jezero Crater and across Mars. “Before we arrived at the Margin Unit, the main hypothesis was that these carbonates formed from interaction with the lake that existed in Jezero Crater, but now we know that this location became a sort of crossroads for aqueous systems, which significantly altered the crystalline volcanic rocks that were originally there,” Bedford said. Environments where water and rock interact repeatedly over long periods are precisely the kinds of settings that intrigue scientists studying the possibility of life on Mars, because such systems can supply energy and chemical gradients that living organisms can exploit. The Margin Unit had long been considered a promising research target since orbiting spacecraft first detected its strong carbonate signatures, but only Perseverance’s close-up view could reveal the fractures, mineral veins, and individual grains that exposed its far more complex history.

The research drew on the collective expertise of the SuperCam team, which Roger Wiens, professor of Earth, Atmospheric, and Planetary Sciences at Purdue, has led since before the launch of NASA’s Mars 2020 mission. Briony Horgan, professor of planetary science at Purdue, contributed to the work and served as campaign science lead during Perseverance’s exploration of the Margin Unit, and former Purdue doctoral students Stephanie Connell and Brad Garczynski also played important roles. Bedford, Wiens, and Connell received support from NASA for the SuperCam instrument. During its traverse, Perseverance collected rock samples from the Margin Unit, sealing them in tubes for a future mission intended to carry them to Earth. In terrestrial laboratories, those samples will be analyzed with instruments far more sensitive than anything a rover can carry, allowing scientists to examine the environments recorded in the rocks at microscopic scales and to assess their potential to preserve signs of ancient habitability.

“I hope this work helps to reshape how scientists view the history of water in Jezero Crater and across Mars,” Bedford said. “Ultimately, I hope this study helps planetary scientists reconstruct the changing climate and habitability of early Mars and provides helpful context for future researchers when these cached Perseverance samples are returned to Earth to be analyzed for potential biosignatures.” The paper, titled “Lake- and groundwater-associated alteration of the olivine-rich Margin Unit in Jezero Crater, Mars,” was accepted for publication in Communications Earth & Environment. For now, the findings stand as a vivid reminder that planetary surfaces keep their secrets at scales that only surface missions can reach, and that the red planet’s ancient waters were not a single still lake but a dynamic, evolving system whose shifting flows left an intricate, overlapping archive in the rocks along Jezero’s rim.

Subject of Research: Alteration of the olivine-rich Margin Unit in Jezero Crater, Mars, by groundwater, lake water, and hydrothermal fluids as observed by the Perseverance rover

Article Title: Purdue-led study finds an ancient history of water on Mars that shifted over time

Article References: Purdue-led study finds an ancient history of water on Mars that shifted over time. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Mars, Perseverance rover, Jezero Crater, Margin Unit, carbonates, groundwater, hydrothermal activity, SuperCam, olivine, astrobiology, water-rock interaction, Purdue University