The review synthesises recent reviews and primary studies spanning agricultural soils, cobalt inputs, plant physiology, soil enzymes and microbial communities. It is not a new field trial or meta-analysis, and the authors note that exposure systems, dose metrics, endpoints and soil conditions often cannot be compared directly. Cobalt occurs naturally in the terrestrial environment and can enter soils through geological weathering, mining, industrial emissions, sewage sludge and agricultural materials.

Its concentration is closely tied to parent material: basic and ultrabasic rocks may contain around 100 mg kg−1, basaltic rocks 40–50 mg kg−1, and acidic rocks such as granite only 1–10 mg kg−1. The global average crustal concentration is generally estimated at 20–25 mg kg−1, but local soil concentrations can depart substantially from that value. European geochemical data illustrate the resulting variability.

The LUCAS topsoil dataset contained 21,682 samples with a mean cobalt concentration of 6.35 mg kg−1 and a range from 0.32 to 91.89 mg kg−1. Agricultural and grazing lands had a mean of 8.9 mg kg−1 in another European survey. At two Greek sites, values were strongly linked to local geology: soils in the Triada area of Euboea ranged from 40 to 208 mg kg−1 because of ultrabasic and nickeliferous rocks, while a Mediterranean site on Megara had a median of 19.0 mg kg−1, about 2.4 times the European median of 7.8 mg kg−1.

These geographic contrasts show how parent material can produce widely different baseline exposures; they do not establish a universal upward or downward trend over time. Several numerical benchmarks appear in the literature, but they answer different questions. Values around 0.5–3.0 mg kg−1 have been described as deficiency ranges, with approximately 3 mg kg−1 often cited as a deficiency threshold.

Natural-background estimates commonly fall around 20–25 mg kg−1, while regulatory and ecological values include 20 mg kg−1 as a limit value, 50 mg kg−1 as a warning value, 240 mg kg−1 as a critical value, 40 mg kg−1 as an agricultural-use guideline, and approximately 13 mg kg−1 as an ecological screening level. None is a universal plant-toxicity threshold. The reviewed evidence was insufficient to define a general cobalt sufficiency range for crops because soil-based dose–response data linking total soil cobalt, plant-available cobalt and crop response remain limited.

Cobalt’s clearest plant function is indirect. In legumes, rhizobial microorganisms use it in symbiotic nitrogen fixation, supporting nodulation, metabolism, growth and yield. Some studies also report improved growth, stress responses or altered alkaloid production in non-legumes, but cobalt is not established as essential for all higher plants.

Deficiency does not consistently depress growth under natural conditions, its physiological role outside nitrogen-fixing symbioses remains incompletely resolved, and reported tissue concentrations may reflect environmental exposure or specialised accumulation rather than nutritional need. Most plants, including legumes, typically contain 0.1–10 mg kg−1 dry weight, although a larger synthesis spanning more than 140 non-hyperaccumulating species reported a much wider range. Such values cannot by themselves distinguish cobalt presence, accumulation, a beneficial response and a true physiological requirement.

Plant responses also depend strongly on how cobalt is delivered. Nutrient solutions and hydroponic media generally expose roots to cobalt more immediately than soil, where sorption, complexation and mineral reactions reduce availability. In solution-based studies, growth depression appeared at 5 µM in mung bean, while chickpea germination remained comparable with the control at 50 µM but declined above that concentration.

Tomato and cauliflower showed growth depression at 50 µM, with severe necrosis and biomass collapse at 500 µM. By contrast, a soil-based assessment placed an EC20, corresponding to a 20% reduction in growth metrics, at 30.6 mg kg−1 for alfalfa, barley, radish, perennial rye and Brassica rapa. Solution concentrations in micromoles, soil concentrations in milligrams per kilogram and foliar rates in grams per hectare describe fundamentally different exposure systems, so these figures cannot be transferred directly between soils or crops.

The review identifies a biphasic pattern in several selected studies: low exposure was associated with stimulation, whereas inhibition appeared after a comparatively small increase. The transition from the concentration associated with benefit to the first inhibitory or toxic concentration was 1.25 times higher in onion, 1.5 times in Paulownia seedlings and field-treated sugarcane, and 2 times in maize, radish and solution-grown sugarcane. These unitless ratios compare concentrations within individual studies and do not convert unlike units into a shared application threshold.

They nevertheless indicate that a modest rise in local cobalt availability could move a crop from a stimulatory response into toxicity, especially where fertiliser distribution is uneven or soil accumulates the element. In common bean, for example, stimulation was reported at 0.05–0.10 mg Co kg−1 soil, while adverse effects emerged at 0.25 mg kg−1, illustrating that even a nitrogen-fixing species can have a narrow response window under the tested conditions. Excess cobalt disrupts several connected physiological processes.

It has been associated with lower chlorophyll, carotenoid and gas-exchange performance, as well as chloroplast damage and iron-deficiency-like chlorosis. Reactive oxygen species can accumulate, antioxidant enzymes may first rise and then become inadequate, and membrane injury can follow. Cobalt also interferes with nutrient balance, particularly through effects on iron transport, and can restrict the movement of phosphorus, sulphur, manganese and zinc.

In legumes, cobalt stress may compromise nodule formation and nitrogen fixation; in one bacterial system, reducing expression of the dmeF gene in Sinorhizobium meliloti lowered nodule formation without necessarily disabling nitrogenase activity in the nodules that did form. Across the reviewed literature, sensitivity is therefore a multidimensional trait involving growth inhibition, pigment degradation, oxidative injury, nutrient imbalance and metabolic disruption rather than a single universal ranking of plant species. Soil responses can provide evidence of biological disruption, but they vary with the measured function and the soil itself.

Experimental soils showed measurable inhibition of dehydrogenases and urease from 25 mg kg−1 cobalt, and clay-and-sand incubations revealed reduced cellulose decomposition and lower cellulase and β-glucosidase activity, with stronger effects in sandy soil. Cobalt can affect catalase, peroxidase, phosphatase, arylsulphatase and β-glucosidase as well. Microbial responses vary: some taxa may proliferate under low exposure, while Azotobacter and cellulose-decomposing organisms can be sensitive, and resistant communities may gain a relative advantage.

Evidence linking cobalt around 22 mg kg−1 in urban soil to antibiotic-resistance genes adds a wider public-health dimension, although that association does not by itself demonstrate a pathway of human exposure. Cobalt also has documented effects on the bacterial-fungal balance, nitrogen cycling and other soil functions. Farm inputs make blanket additions especially difficult to justify.

Phosphate fertilisers commonly contain 1–12 mg kg−1 cobalt, nitrogen fertilisers 5–12 mg kg−1, lime materials 0.4–3.0 mg kg−1, and manures a broader 0.3–24 mg kg−1. Deliberately enriched products can supply cobalt as sulfate, nitrate or chloride salts through soil application, foliar sprays or seed coatings. In the European Union, cobalt has been regulated among seven micronutrients eligible for declaration in fertilising products, and current rules specify minimum rather than maximum cobalt contents for many categories.

Labels require micronutrient fertilisers to be used only where there is a recognised need, but the review notes that this general provision does not create a cobalt-specific operational requirement for prior soil testing or background verification. That regulatory gap matters because intentional inputs occur alongside repeated incidental ones. Compound nitrogen, phosphorus and potassium fertilisers can carry cobalt through their raw materials, and applying them at hundreds of kilograms per hectare may constitute a recurring loading pathway.

Cobalt is also an incidental impurity in some pesticide formulations, although it is not listed as an active substance in plant-protection products. The authors’ proposed direction is cautious rather than prohibitive: future studies should use crop- and soil-specific designs under realistic field conditions, with consistent reporting of cobalt dose, speciation or bioavailability, plant endpoints, soil enzymes and microbial responses. Until such evidence can identify reliable transfer and toxicity thresholds, they say, cobalt should not be treated as a routine fertiliser constituent.

Subject of Research: Critical assessment of cobalt fertilisation, plant requirements and phytotoxic risk in agricultural soils

Article Title: Re-evaluating cobalt in agricultural soils: plant requirement and phytotoxic risk

Article References: Tsourgianni, E., Konstantinou, M., Stefanou, S., & Giannakoula, A. (2026). Re-evaluating cobalt in agricultural soils: plant requirement and phytotoxic risk. Plant and Soil. https://doi.org/10.1007/s11104-026-09167-2

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09167-2

Keywords: cobalt fertilisation, agricultural soils, phytotoxicity, plant nutrition, soil bioavailability, soil enzymes, microbial communities, legume nitrogen fixation, soil health, fertiliser regulation, Re-evaluating, cobalt

The work addresses a central limitation of manganese dioxide cathodes in aqueous zinc batteries. Manganese-related reactions can be insufficiently reversible: the formation of Mn³⁺ can distort the host crystal structure, while manganese dioxide deposited during discharge may not fully dissolve, leaving electrochemically inactive material that raises interfacial resistance and accelerates capacity loss. The researchers therefore sought a way to stabilize the manganese dioxide structure while accelerating electron transfer and making interfacial deposition and dissolution reversible, without adding acid or external redox mediators that could introduce corrosion, self-discharge, or other stability problems.

The team fabricated the Co–MnO₂ nanoarray by electrochemically oxidizing a cobalt–manganese layered double hydroxide precursor. This topological phase transformation dispersed Co³⁺ ions atomically throughout the layered MnO₂ framework and placed them in a high-spin electronic configuration. According to the reported mechanism, the cobalt changes the local symmetry of the [MnO₆] octahedra, suppressing Jahn–Teller distortion and improving structural stability. Weaker Co–O bond covalency also increases electron availability around lattice oxygen, facilitating Mn²⁺ adsorption and charge transfer at the cathode–electrolyte interface. Together, these effects support two coupled storage processes: MnO₂/Mn³⁺ redox reactions within the bulk and MnO₂/Mn²⁺ deposition–dissolution reactions at the interface in an electrolyte containing Mn²⁺.

At a current density of 2 A g⁻¹, the optimized electrode retained 185 mAh g⁻¹ after 3,000 cycles. It also showed recovery after a rate test, reaching 280 mAh g⁻¹ at 2 A g⁻¹ and returning to 516 mAh g⁻¹ when the current was reduced to 0.2 A g⁻¹. By comparison, the unmodified MnO₂ cathode deteriorated rapidly in the reported tests. The cobalt-containing electrode also showed lower self-discharge over 24 hours, retaining 81.23% of capacity compared with 76.02% for pristine MnO₂. These results are laboratory measurements from the research system; the release does not establish performance under commercial cell formats, broad operating conditions, or extended service beyond the tested conditions.

The study also included a zinc pouch cell with a Co–MnO₂ cathode loading of 45 mg, which showed no observable capacity decay over 100 cycles. This demonstration suggests that the design can operate beyond a small laboratory electrode, although it does not amount to a validation of pack-level energy density, manufacturing scalability, or long-term field reliability. More broadly, the findings identify transition-metal spin-state regulation as a possible design principle for enabling reversible multielectron chemistry in manganese-based cathodes. Whether the approach can be translated into practical aqueous zinc batteries, or extended to other electrode materials and larger energy-storage systems, remains to be tested through additional device engineering and validation.

Subject of Research: Atomic high-spin cobalt engineering of manganese dioxide cathodes for long-lived aqueous zinc–manganese batteries

Article Title: High-spin cobalt unlocks a new era of long-life zinc–manganese batteries

Article References: High-spin cobalt unlocks a new era of long-life zinc–manganese batteries. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: aqueous zinc batteries, manganese dioxide cathodes, high-spin cobalt, atomic doping, multielectron storage, manganese redox, cycling stability, Jahn–Teller distortion, zinc pouch cell, High-spin, cobalt, unlocks

The motivation behind the work is deceptively simple. Riverbed mining exerts significant pressure on Himalayan river systems, yet its influence on trace metal dynamics in sediments remains poorly understood across elevation gradients. Sand and gravel extraction has become one of the most widespread forms of river modification in the region, disturbing channel beds, altering flow patterns and potentially remobilising metals that would otherwise remain locked in sediment. By sampling ten surface sediment sites from each of the three rivers, the team built an elevation transect that allowed them to separate the chemical fingerprint of pristine mountain catchments from that of intensively mined and industrially influenced lowland stretches.

The analytical approach was deliberately multi-layered. Rather than relying on a single contamination metric, the researchers evaluated the sediments using a battery of pollution indices, including the geoaccumulation index (Igeo), the Nemerow pollution index, the pollution load index (PLI), the potential ecological risk index (PERI), the mean effect range median quotient (MERMQ) and the mean effect concentration quotient (MEC). These were cross-checked against consensus-based sediment quality guidelines, which define threshold and probable effect concentrations above which adverse biological effects in aquatic organisms become likely. Pearson’s correlation analysis and hierarchical cluster analysis were then used to trace the likely sources of each metal, distinguishing geogenic inputs derived from rock weathering from anthropogenic contributions linked to mining and industry.

The concentration data revealed clear patterns. In both the Chandra and Beas Rivers, mean metal concentrations followed the order chromium greater than zinc greater than nickel greater than lead greater than copper greater than cobalt, while Chakki Khad showed a slightly different ranking in which nickel overtook zinc: chromium greater than nickel greater than zinc greater than lead greater than copper greater than cobalt. Chromium dominated every river, a finding that reflects both the geochemistry of Himalayan lithology and, in the lower reaches, additional human inputs. The consistency of the chromium signal across all three elevation zones underscores how the region’s geology sets a natural baseline that any contamination assessment must account for.

The most alarming results came from comparisons against sediment quality guidelines. Chromium exceeded the probable effect concentration, the threshold above which toxic effects on bottom-dwelling organisms are probable, in 40 percent of samples from the Chandra River, 20 percent from the Beas River and 40 percent from Chakki Khad. Nickel was even more concerning downstream: it surpassed the probable effect concentration in just 10 percent of Chandra samples but in 40 percent of Beas samples and a striking 70 percent of Chakki Khad samples. Because nickel and chromium are toxic to aquatic invertebrates and can bioaccumulate through food webs, these exceedances signal genuine ecological risk rather than a merely statistical anomaly.

The composite indices told a coherent story of escalating contamination with decreasing elevation. The Nemerow pollution index, which integrates the pollution levels of individual metals into a single warning score, indicated warning-level contamination in 70 percent of Chakki Khad samples. The mean effect range median quotient, a toxicity-predicting metric, reached 1.4 in Chakki Khad, with half of the samples from that river registering a 49 percent probability of sediment toxicity. By contrast, geoaccumulation index values were predominantly negative across all three rivers, indicating that most sediments are not strongly enriched relative to background geochemistry, with one isolated maximum of 1.71 for lead in the Chandra River pointing to a localised lead anomaly in the high Himalayan catchment.

Statistical source apportionment was where the elevation gradient became most revealing. In the Chandra River, correlation and cluster analyses pointed squarely to geogenic sources, meaning the metals there derive primarily from the weathering of the young, metal-rich rocks of the Himalayan orogen rather than from human activity. The Beas River showed mixed influences, a blend of natural background and moderate human pressure consistent with its position in a more developed middle-Himalayan valley. Chakki Khad, however, displayed pronounced anthropogenic inputs, which the researchers attribute to intensive sand mining and effluents from the dyeing industry. The chemical signature of that industrial discharge, visible in the nickel and chromium enrichments, effectively marks the point where a Himalayan river transitions from a geological archive to an industrial one.

Taken together, the ranking of contamination is unambiguous: Chakki Khad exhibited the highest contamination, followed by the Beas River and then the Chandra River. This inverse relationship between elevation and contamination risk carries important implications for how Himalayan basins are managed. Upstream catchments, though not untouched, remain dominated by natural geochemical processes, while downstream reaches bear the accumulating burden of extraction and industry. The pattern also suggests that regulatory attention focused only on the most visibly degraded lowland sites would miss the broader basin-scale dynamics that ultimately determine sediment quality throughout the river network.

The study’s significance extends beyond the three rivers it sampled. Sand mining is recognised internationally as a growing driver of river degradation, with documented consequences ranging from bank instability to the remobilisation of metals such as lead and cadmium in mined channels. In the Himalaya, where rivers carry some of the highest sediment loads on Earth and where infrastructure development is accelerating, the absence of systematic trace metal baselines has long hampered evidence-based regulation. By delivering the first systematic trace metal baseline for these river sediments, the research provides a reference point against which future monitoring can measure change, and a demonstration of how a multi-index, statistically grounded framework can disentangle natural from human contributions in complex mountain catchments.

The authors argue that the findings underscore the need for basin-scale monitoring and regulation of mining activities across Himalayan fluvial systems. That call comes at a critical moment: India’s sustainable sand mining guidelines and district-level survey reports already exist on paper, but enforcement in remote mountain terrain remains difficult, and the sediment chemistry documented in this study shows that the ecological stakes are real. For the benthic communities that form the foundation of river food webs, exceeding probable effect concentrations is not an abstraction but a direct threat. As demand for construction sand continues to climb across South Asia, studies like this one make clear that the sediments of Himalayan rivers are not inert ground to be excavated at will, but sensitive chemical archives whose degradation will be read, sooner or later, in the health of the entire river ecosystem.

Subject of Research: Trace metal contamination and ecological risk in sediments of three Himalayan rivers affected by riverbed mining and industrial effluents

Article Title: Quantification of trace metal contamination and ecological risks in river sediments of the Himalaya

Article References: Rishi, M. S., Singh, R., Kaur, L., & Sidhu, N. (2026). Quantification of trace metal contamination and ecological risks in river sediments of the Himalaya. Environmental Monitoring and Assessment, 198(9), Article 1030. https://doi.org/10.1007/s10661-026-15825-w

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15825-w

Keywords: Himalayan rivers, trace metals, river sediments, sand mining, chromium, nickel, ecological risk, sediment quality guidelines, pollution indices, Himachal Pradesh, water pollution, geoaccumulation index

The scale of the challenge is staggering. China alone consumes roughly half of the world’s lithium, driven largely by its dominant position in the electric vehicle market, and has pledged to cut greenhouse gas emissions by 60 to 65 percent by 2030. Meanwhile, mining these metals generates vast quantities of tailings laden with heavy metals and chemicals. When improperly disposed of, these wastes contaminate water supplies, destroy biodiversity, and degrade soil — with acid mine drainage, in which sulfide minerals oxidize to produce extremely acidic runoff, posing the single greatest threat to water quality across large regions. Conventional recycling routes offer little relief: pyrometallurgical smelting is energy-hungry, while hydrometallurgical leaching demands aggressive acids and generates sludge and saline effluents of its own.

Membranes work on an entirely different principle. Instead of burning or dissolving entire waste streams, they act as molecular gatekeepers — semi-permeable barriers that allow some ions to pass while blocking others based on size, electrical charge, or specific chemical interactions. Pressure-driven systems such as ultrafiltration, nanofiltration, and reverse osmosis push liquid through these barriers, while electro-driven systems like electrodialysis use an applied voltage to steer ions toward oppositely charged electrodes. The review categorizes four main feed streams — battery leachates, acid mine drainage, salt-lake brines, and industrial effluents — each with distinct chemistries that demand tailored membrane approaches rather than one-size-fits-all solutions.

The most striking results come from lithium recovery. In acidic sulfate leachates from spent batteries, lithium exists largely as free Li+ ions while cobalt, nickel, and manganese form sulfate complexes. Negatively charged nanofiltration membranes exploit this difference: they repel the multivalent transition metal cations through electrostatic repulsion and size exclusion while allowing the smaller, singly charged lithium ions to permeate. One study cited in the review achieved 99.5 percent pure lithium carbonate after just two nanofiltration passes — approaching battery-grade material without harmful chemical additives. Another research group using polymer inclusion membrane electrodialysis, where selective carriers embedded in a PVDF-HFP polymer matrix bind lithium and cobalt ions, reported recoveries of 99.1 percent for lithium and 99.9 percent for cobalt, with a carbon footprint of just 3.1 kilograms of CO2-equivalent per kilogram of lithium recovered.

Separating lithium from magnesium in brines presents an even tougher puzzle because the two ions have similar ionic radii. Here, the review explains that the key lies in hydration energy: magnesium ions hold water molecules far more tightly than lithium does, giving Mg2+ a bulkier, more strongly bound hydration shell. Negatively charged nanofiltration membranes exploit this by electrostatically repelling the divalent magnesium while the monovalent lithium slips through more easily. Separating cobalt from nickel is harder still — both are divalent with nearly identical hydrated radii — so simple charge exclusion fails. Supported liquid membranes, which impregnate a porous support with a tailored organic extractant that reversibly binds one metal preferentially, offer a way forward, achieving extraction and stripping efficiencies of 85.7 and 83.2 percent for nickel in one reported case.

But the review is refreshingly honest about where membranes struggle. Real battery leachates are not clean laboratory solutions: they are acidic (often below pH 2), highly saline, loaded with organic residues from binders and electrolytes, and contain a shifting cast of competing ions. Under these conditions, membranes fail in chemistry-specific ways. Precipitation is the most common culprit — as pH, temperature, or ionic strength shifts, salts like calcium carbonate, magnesium hydroxide, and gypsum (calcium sulfate dihydrate) become supersaturated and crystallize on membrane surfaces, blocking pores and causing irreversible flux decline. Iron and aluminum hydrolyze into gelatinous hydroxides that clog membranes, while oxidants such as hydrogen peroxide and hypochlorite — often added during leaching — attack polyamide membranes chemically, degrading the polymer itself.

Long-term durability emerges as the review’s central concern. In one particularly revealing study, commercial NF270 and DK nanofiltration membranes were exposed to hydrochloric acid at pH 1 for up to 30 days. Both initially retained divalent ions at 96.5 percent or better, but NF270’s rejection dropped from 99.1 to 84.3 percent over the exposure period — a systematic decline the authors attribute to acid hydrolysis of the polyamide active layer. Another group incorporated sulfonated covalent organic framework nanosheets into a nanofiltration membrane to boost acid resistance; initial lithium rejection was moderate at 43.7 percent while divalent metals exceeded 90 percent, but even this engineered membrane lost significant performance after 7 to 14 days in acid. The lesson, the review argues, is that short-term laboratory tests cannot predict months-long industrial performance.

On economics, the numbers are encouraging but conditional. Membrane processes like electrodialysis and nanofiltration typically consume 0.5 to 5 kWh per cubic meter of treated water — substantially less than conventional thermal or precipitation-based routes, which can exceed 10 kWh per cubic meter when the full water-intensive mining chain is accounted for. Membrane-hybrid systems have demonstrated 50 to 84 percent reductions in total energy demand compared to conventional solvent extraction. Lithium recovered from salt-lake brines costs roughly USD 2 to 3 per kilogram, compared with around USD 80 per kilogram from seawater, while lithium carbonate commands a market price near USD 24 per kilogram — making brine-based membrane recovery economically attractive. Polymeric membranes last 5 to 8 years and ceramic membranes 15 to 20, offering long-term savings through reduced replacement frequency.

Yet the review is careful to position membranes as complementary rather than replacement technology. Nanofiltration achieves lithium selectivity in the 70 to 90 percent range with transition metal rejections typically above 90 percent, but separating chemically similar divalent cations like nickel from cobalt remains limited. Fluxes in concentrated leachates are often constrained to below 10 liters per square meter per hour due to osmotic pressure and fouling. Membranes excel at lithium concentration and acid recovery, but solvent extraction or precipitation is still needed for full transition metal separation. The realistic industrial pathway, the authors suggest, is a hybrid flowsheet: membranes as selective concentration and acid-recycling steps, followed by conventional precipitation to deliver battery-grade products.

The review’s conclusion is both a warning and a roadmap. The principal bottleneck in membrane-based critical material recovery is not initial separation performance — many studies already report 90 to 99 percent recovery — but sustained stability, fouling control, and honest accounting of energy per kilogram of product, membrane lifetime, and cleaning frequency under realistic leachate conditions. Few studies report these parameters, and most rely on simulated rather than real battery-derived streams. Future progress, the authors argue, depends on targeted material innovations such as acid-resistant thin-film composites and crown ether-functionalized ion-exchange membranes, thorough long-term stability testing, and integration into holistic pretreatment and recovery trains. If those gaps close, membranes could shift from promising laboratory curiosities to indispensable components of a circular economy that treats yesterday’s batteries and mine waste as tomorrow’s ore bodies.

Subject of Research: Membrane-based separation technologies for recovering critical metals from spent batteries and mineral wastes

Article Title: Membrane-based extraction of critical materials from spent batteries and other mineral wastes

Article References: Matebese, F., Raseala, M. J., & Moutloali, R. M. (2026). Membrane-based extraction of critical materials from spent batteries and other mineral wastes. Frontiers in Membrane Science and Technology, 5, Article 1766669. https://doi.org/10.3389/frmst.2026.1766669

Image Credits: AI Generated

DOI: 10.3389/frmst.2026.1766669

Keywords: membrane technology, lithium recovery, battery recycling, nanofiltration, electrodialysis, acid mine drainage, critical materials, circular economy, cobalt, nickel, fouling, hydrometallurgy

The appeal of the new material lies in its bifunctionality. Electrode materials for supercapacitors and catalysts for the hydrogen evolution reaction typically demand different, sometimes conflicting, properties: fast and reversible redox activity for charge storage, and efficient adsorption of hydrogen intermediates for water splitting. By embedding nickel cobalt oxide, a spinel oxide celebrated for its rich redox chemistry, and cadmium oxide, which contributes additional electroactive sites, onto reduced graphene oxide, the researchers created a hierarchical architecture in which each component compensates for the limitations of the others. The result is a single electrode that performs credibly in both roles, a design philosophy that could simplify the materials toolkit for integrated energy devices.

The numbers reported for charge storage are striking. At a current density of 2 amperes per gram, the composite delivered a specific capacity of 2700 coulombs per gram, a metric that quantifies the total charge an electrode can store per unit mass and one that translates into substantial energy density when paired with an appropriate counter-electrode in a full device. The hybrid also achieved an energy density of 71.2 watt-hours per kilogram alongside a power density of 1600 watts per kilogram, a combination that matters because supercapacitors have long been criticized for storing less energy than batteries even though they can deliver and absorb charge far more rapidly. Pushing both figures upward simultaneously is the central engineering challenge of the field.

Durability, the quiet killer of promising electrode materials, also fared well. The composite retained a coulombic efficiency of 89.87 percent over 1000 charge-discharge cycles, indicating that the redox reactions remained reversible and that the material resisted the structural degradation, dissolution, and detachment that plague many metal oxide electrodes as they swell and contract during repeated cycling. The researchers attribute this resilience to the reduced graphene oxide matrix, which substantially enhances charge-transport pathways, preserves the hierarchical structure, and exposes abundant electroactive sites while physically supporting the oxide nanoparticles.

Reduced graphene oxide deserves particular attention in explaining the composite’s performance. Derived from graphite oxide by partial chemical reduction, it retains functional oxygen groups that serve as nucleation points for anchoring metal oxide nanoparticles, preventing them from clumping into larger particles with diminished surface area. Its conductive carbon network then acts as a highway for electrons, funneling charge from the current collector to the dispersed oxide particles and back. Without this scaffold, electrons moving through a thick film of semiconducting oxides encounter resistance at every grain boundary; with it, the effective resistance drops and the redox activity of the oxides can be exploited at high rates. The synergistic effect from embedding the two oxides onto the carbon matrix facilitates efficient electron transfer, redox activity, and durability, the authors write.

Nickel cobalt oxide itself is a spinel structure in which nickel and cobalt cations occupy defined sites within a cubic oxide framework. Its electrochemical activity stems from the multiple oxidation states accessible to both metals, allowing rich and reversible Faradaic reactions in which charge is stored through electron transfer at the electrode surface rather than through the purely electrostatic adsorption seen in carbon-based double-layer capacitors. Cobalt’s involvement raises the electrical conductivity relative to pure nickel oxide, while nickel contributes additional redox capacity. Cadmium oxide, a well-known transparent conducting oxide, adds a second population of electroactive nanoparticles and may improve the overall electronic character of the composite, though the researchers emphasize the cooperative interaction among all three solid phases rather than the contribution of any single component.

The hydrogen evolution results add a catalytic dimension to the work. When tested as an electrocatalyst for splitting water, the composite required an overpotential of 190.22 millivolts to reach a current density of 10 milliamperes per square centimeter, with a Tafel slope of 67.22 millivolts per decade. The overpotential measures the extra voltage beyond the thermodynamic requirement that must be applied to drive hydrogen production at a practical rate; lower values mean less wasted energy. The Tafel slope, obtained from the relationship between overpotential and the logarithm of current density, offers insight into the reaction mechanism and the kinetics of the catalytic process, with shallower slopes indicating faster kinetics. Achieving both metrics in a material designed primarily for charge storage suggests that the same surface features that promote fast redox reactions also assist the adsorption and recombination steps of hydrogen generation.

The bifunctional design carries practical weight for the emerging hydrogen economy. Green hydrogen, produced by electrolyzing water with renewable electricity, depends on electrocatalysts that are active, stable, and cheap. Precious-metal catalysts based on platinum and iridium set the performance benchmark but remain expensive and scarce, motivating intense research into transition-metal oxides, sulfides, and phosphides as alternatives. A hydrothermally synthesized composite of abundant metals on a carbon scaffold fits squarely within this search, and the fact that the same electrode can be repurposed for energy storage hints at integrated systems in which a single material platform serves supercapacitors, water splitters, and possibly regenerative fuel cells.

The study, published on 16 October 2026, suggests an auspicious approach for designing efficient hybrid electrode systems for electrochemical energy storage applications and next-generation supercapacitors, according to the authors. The fabrication and design of advanced electrode materials via low-cost and environmentally friendly approaches have attracted great interest, they note, positioning the hydrothermal route as a scalable pathway for industry. The work also reflects a broad international collaboration, with contributors from Princess Nourah bint Abdulrahman University and Taif University in Saudi Arabia, the University of Chemistry and Technology Prague in the Czech Republic, Urgench State University in Uzbekistan, and the University of Hafr Al Batin and Prince Sattam bin Abdulaziz University in Saudi Arabia, supported by the Princess Nourah bint Abdulrahman University Researchers Supporting Project.

Challenges remain before such composites reach commercial devices. Cycle life beyond 1000 cycles, full-cell performance with realistic mass loadings, and long-term stability under industrially relevant current densities all require further demonstration, and cadmium’s toxicity raises environmental questions that researchers will need to address through encapsulation or substitution. Yet the underlying design logic, dispersing redox-active oxides across a conductive carbon network to harvest the strengths of both, continues to spread through the energy materials community. As the demand for rapid-charging storage and low-cost hydrogen production grows in parallel, materials that serve both missions at once may prove among the most consequential innovations of the decade.

Subject of Research: Nickel cobalt oxide-cadmium oxide anchored on reduced graphene oxide (NiCo2O4–CdO@rGO) as a bifunctional electrode material for energy storage devices and hydrogen evolution reaction

Article Title: Nickel cobalt oxide-cadmium oxide anchored on reduced graphene oxide (NiCo2O4–CdO@rGO) as a bifunctional electrode material for energy storage devices and hydrogen evolution reaction

Article References: Khan, S., Ashraf, M., Zahid, T., Ahsan, U., Fakhraddin, M., Alotaibi, M. T., Maati, L. A. E., Tawfik, S. G., Alrubayyi, A., Alrobei, H., & Mumtaz, S. (2026). Nickel cobalt oxide-cadmium oxide anchored on reduced graphene oxide (NiCo2O4–CdO@rGO) as a bifunctional electrode material for energy storage devices and hydrogen evolution reaction. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13909-z

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13909-z

Keywords: supercapacitors, hydrogen evolution reaction, reduced graphene oxide, nickel cobalt oxide, cadmium oxide, bifunctional electrode, energy storage, electrocatalysis, Nickel, cobalt, oxide-cadmium, oxide

The study, published in Frontiers in Geochemistry, examined mine wastes from two strikingly different legacy mining regions: the town of Cobalt in Ontario, Canada, and three historic mine sites in Cornwall, England. Despite vast differences in geology, ore type, and processing methods spanning a millennium of mining history, the researchers found that cobalt in both locations showed consistently high potential for mobilization — meaning it could readily dissolve and travel into aquatic environments where it might enter the food chain.

“The concentrations we found at Cobalt, Canada were extraordinary,” the research indicates, with high-grade Nipissing tailings containing up to 5,630 milligrams of cobalt per kilogram of material — roughly 900 times higher than the Cornwall sites. Even the low-grade tailings at Cobalt reached 1,230 milligrams per kilogram, dwarfing the averages of 40, 76, and 59 milligrams per kilogram found at Poldice, Wheal Unity, and Dolcoath mines in Cornwall respectively. These concentrations far exceed residential soil quality guidelines set by regulatory bodies in Ontario, Canada, the United States, and the European Union.

The research team, led by Gabriel Ziwa of the Camborne School of Mines at the University of Exeter, employed a sophisticated battery of analytical techniques to understand not just how much cobalt was present, but in what chemical forms. Using X-ray diffraction, scanning electron microscopy, and electron microprobe analysis, they identified the specific minerals hosting the cobalt — a crucial step because a metal locked inside a stable crystal is far less dangerous than one sitting on a mineral surface ready to dissolve at the first change in water chemistry.

At Cobalt, Canada, the picture was dominated by a striking pink mineral called erythrite — a cobalt arsenate that formed as needle-like crystals growing on silicate and carbonate grains throughout the tailings. This secondary mineral, containing roughly 20.8 percent cobalt by weight, proved to be the most widespread cobalt-bearing phase at the site. The researchers also identified primary cobalt minerals including cobaltite, safflorite, and skutterudite, alongside cobalt incorporated into arsenopyrite, loellingite, pyrite, and chalcopyrite. Secondary phases such as arseniosiderite, scorodite, and iron oxyhydroxides also harboured significant cobalt concentrations.

In Cornwall, by contrast, no dedicated cobalt minerals were found at all. Instead, cobalt existed only as a trace component — typically less than one percent by weight — hidden inside common sulfide minerals like pyrite, chalcopyrite, and arsenopyrite, and in secondary phases such as scorodite and iron-manganese oxyhydroxides. Yet this difference in mineralogical hosting made almost no difference to the metal’s behaviour when subjected to sequential extraction testing.

The most alarming result came from the BCR sequential extraction analysis, a standardized European protocol that subjects mine waste to progressively stronger chemical leaches to simulate what might happen under different environmental conditions. In both the Canadian and British samples, an average of 46 percent of the total cobalt was extracted in the very first, mildest step — the “exchangeable” fraction that represents metal most easily dissolved by slight changes in acidity. This means nearly half the cobalt in these wastes is sitting in a form that could be released into water with only minor pH shifts.

Applying the Risk Assessment Code framework developed by Perin and colleagues, the researchers classified cobalt in the Cornwall samples as ranging from high risk to very high risk, with individual samples reaching exchangeable fractions of up to 62 percent. At Cobalt, Canada, values ranged from 28 to 58 percent, placing the metal in medium to very high risk categories. According to the RAC guidelines, metals exceeding 50 percent in the exchangeable fraction are considered to easily enter the food chain — a classification that directly implicates these mine wastes as potential vectors for human cobalt exposure through crops, livestock, and water supplies.

The chemistry behind this mobilization is well understood. At Cornwall’s acidic sites, where paste pH values ranged from 3.72 to 5.77, sulfide minerals like pyrite generate acid through oxidation, and any cobalt-bearing phases dissolve readily, releasing cobalt ions and arsenic oxyanions into solution. At Cobalt, Canada, the near-neutral pH of 7.50 to 7.84 currently stabilizes erythrite within its thermodynamic stability field — but the researchers warn this equilibrium is fragile. A shift toward acidity, whether from changing oxidation conditions or altered hydrology, could dissolve the erythrite and release its cobalt payload. The iron and manganese oxyhydroxides that scavenge cobalt in both locations are themselves thermodynamically unstable under reducing conditions, meaning buried or waterlogged wastes could also release their stored metal.

What makes this research particularly significant is its implication for the future. Cobalt demand is projected to surge as electric vehicle adoption accelerates globally, and governments worldwide have designated it a strategic resource. Yet the environmental behaviour of cobalt in mine waste has been remarkably understudied compared to metals like arsenic or lead. The Exeter team’s finding that cobalt behaves similarly across such geologically different settings — a five-element silver-cobalt-nickel vein deposit in Precambrian rocks versus polymetallic tin-copper-arsenic veins in Devonian-Carboniferous host rocks — suggests that the metal’s mobility in mine waste may follow predictable patterns worldwide. If confirmed by further research, this would mean that every new cobalt mine opening today is generating waste with the same latent capacity to contaminate water and food chains that century-old sites in Canada and England are only now revealing.

Subject of Research: Geochemistry and mineralogy of cobalt mobility in legacy mine wastes from Cobalt, Canada and Cornwall, England

Article Title: Geochemistry and mineralogy of Cobalt in mine wastes: examples from Cobalt, Canada and Cornwall, England

Article References: Ziwa, G., Crane, R., & Hudson-Edwards, K. A. (2025). Geochemistry and mineralogy of Cobalt in mine wastes: examples from Cobalt, Canada and Cornwall, England. Frontiers in Geochemistry, 3, Article 1543695. https://doi.org/10.3389/fgeoc.2025.1543695

Image Credits: AI Generated

DOI: 10.3389/fgeoc.2025.1543695

Keywords: cobalt, mine waste, tailings, geochemistry, mineralogy, erythrite, sequential extraction, mobility, critical raw materials, contamination, Cornwall, Ontario

The team sampled water from six lakes and ponds across three site-wide surveys conducted in Summer 2024, Fall 2025, and Spring 2026, producing eighteen individual site-campaign observations. From each sample, they measured eleven trace elements that survived rigorous data verification: aluminum, arsenic, cadmium, cobalt, copper, iron, manganese, nickel, lead, selenium, and zinc, all standardized to micrograms per liter. These are not obscure contaminants. Arsenic and lead are among the most notorious poisons in environmental health, cadmium accumulates in kidneys and bones, and excess manganese has been linked to neurological harm. Even elements such as copper and zinc, essential nutrients in trace amounts, become ecologically damaging when concentrations climb too high.

To translate raw concentrations into something actionable, the researchers deployed two complementary screening tools. The first was the exceedance ratio, calculated simply as the measured concentration of an element divided by its screening benchmark, so that any value above one signals a potential concern. The second was the Heavy Metal Pollution Index, or HPI, a composite metric first developed in the 1990s that weights multiple metals together into a single score reflecting overall water quality. By combining these indices with a variance-partitioning statistical analysis, the team could ask two distinct questions: which water bodies are the most contaminated, and what factor, location or season, best explains the variation they observed.

The answer to the first question was unambiguous. Lake Manawa, a popular recreation spot near Council Bluffs, Iowa, recorded the highest mean HPI of any site at 327.13, along with the highest overall mean exceedance ratio of 1.85. Digging into the element-level data, the researchers found that the lake’s poor showing was driven principally by cobalt, which exceeded its benchmark by an average factor of 7.19, followed by lead at 5.16 times the benchmark, manganese at 1.99, aluminum at 1.94, and cadmium at 1.49. A cobalt exceedance of more than sevenfold is striking, since cobalt is rarely the headline contaminant in freshwater assessments, and a lead ratio above five raises immediate questions about legacy sources such as historical industrial activity, atmospheric deposition from the era of leaded gasoline, or contaminated sediments resuspended into the water column.

Among the remaining five sites, Pinky’s Glen posted the highest mean exceedance ratio at 1.57, dominated by manganese at 5.31 times its benchmark, aluminum at 3.24, and cobalt at 3.15. Steinhart Park showed a similar fingerprint, with elevated manganese at 5.61, cobalt at 3.05, and aluminum at 2.59. The recurring trio of manganese, aluminum, and cobalt at these sites is geochemically suggestive. All three elements are abundant in the region’s glacial tills and alluvial sediments, and their co-elevation can reflect natural weathering of fine-grained deposits, particularly under the low-oxygen conditions that develop in stagnant pond bottoms where manganese and iron oxides dissolve and release bound metals into the water. Distinguishing between such geogenic enrichment and genuine anthropogenic pollution is precisely the kind of question that confirmatory monitoring, with sediment chemistry and speciation analysis, would need to answer.

The variance partition delivered the study’s most conceptually important result. Using an additive two-factor model, the researchers found that the identity of the water body itself accounted for more than 90 percent of the variation in seven of the eleven elements analyzed: aluminum, cobalt, copper, iron, manganese, lead, and zinc. In other words, each pond and lake carries its own geochemical fingerprint, shaped by its local catchment, sediment history, and hydrology, so distinct from its neighbors that sampling one tells you almost nothing about the others. The campaign factor, by contrast, dominated for only two elements: it explained 95.8 percent of the variation in arsenic and 54.2 percent of the variation in cadmium. This suggests that arsenic levels in these waters fluctuate strongly between surveys, possibly in response to seasonal changes in redox conditions, water level, or sediment disturbance, while the other metals remain stubbornly anchored to place.

For environmental managers, this statistical architecture has a blunt practical message: pooled regional averages are the wrong tool for this landscape. If water-body identity explains over 90 percent of the variance for most metals, then a single regional mean conceals exactly the information that matters, namely which specific lakes exceed safe thresholds and by how much. A regional program that samples one representative pond and extrapolates to the floodplain would likely declare the area broadly acceptable while missing a lake like Lake Manawa, where the composite pollution index towers over its neighbors. The study’s authors argue that monitoring should instead be site-specific and analyte-specific, prioritizing the locations and elements where exceedances are real and repeated.

To formalize that prioritization, the team constructed an equal-weight ranking score that combined three normalized metrics: the mean HPI, the frequency with which benchmarks were exceeded, and the mean exceedance ratio. The exercise produced a clear shortlist. Lake Manawa, Pinky’s Glen, and Steinhart Park emerged as the three highest priorities for confirmatory monitoring, each for slightly different reasons. Lake Manawa’s case rests on its exceptional cobalt and lead levels, while Pinky’s Glen and Steinhart Park share a manganese-aluminum-cobalt signature that may point to sediment chemistry and oxygen dynamics as the controlling processes. Confirmatory monitoring, the researchers emphasize, would involve denser temporal sampling, sediment and pore-water analysis, and measurements of metal speciation, the chemical forms that determine how bioavailable, and therefore how toxic, each element actually is to aquatic organisms and humans.

The study also recovered a physicochemical dataset that frames the metal findings in context. Carter Lake recorded the highest mean total dissolved solids at 264.67 milligrams per liter and the highest electrical conductivity at 529.33 microsiemens per centimeter, indicators of its higher dissolved ion load. Water temperatures across the surveys ranged from 3.03 to 6.57 degrees Celsius, and mean pH values sat in the circumneutral band between 6.95 and 7.62. These parameters matter because metal behavior in water is exquisitely sensitive to them. Circumneutral pH limits the dissolution of many metal species, while conductivity and dissolved solids influence how metals complex with dissolved organic matter and carbonate ions, altering both their transport and their toxicity. The cold temperatures during sampling may also slow the microbial and geochemical reactions that mobilize metals from sediments, meaning warm-season conditions could push concentrations in either direction.

The authors are careful to flag the limits of their design. Because the three surveys occurred in different years rather than within a single annual cycle, temporal comparisons and benchmark exceedances must be interpreted as screening-level evidence rather than definitive trend statements. That caution is scientifically appropriate, but it does not blunt the central finding. In a floodplain landscape scarred and reshaped by more than a century of Missouri River engineering, agricultural runoff, and industrial legacy, six neighboring water bodies behave as six independent geochemical systems. The study’s call to abandon pooled regional assessment in favor of targeted, site-by-site monitoring is a challenge to conventional water-quality practice, and one that, if heeded, could uncover hidden contamination hotspots in floodplains well beyond the Iowa-Nebraska border.

Subject of Research: Trace-element contamination dynamics in Missouri River floodplain lakes and ponds

Article Title: Spatial and campaign-scale dynamics of trace elements in lakes and ponds of the Iowa and Nebraska – Missouri River floodplain

Article References: Adojoh, O. C., Trabal, W., Adewuyi, F., Ayinde, K., Bellamy, M., Meziani, M. J., & Monroe, L. (2026). Spatial and campaign-scale dynamics of trace elements in lakes and ponds of the Iowa and Nebraska – Missouri River floodplain. Environmental Geochemistry and Health, 48(16), Article 642. https://doi.org/10.1007/s10653-026-03525-w

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03525-w

Keywords: trace elements, Missouri River floodplain, heavy metal pollution index, Lake Manawa, water quality monitoring, manganese, cobalt, lead contamination, exceedance ratio, floodplain lakes, environmental geochemistry, Iowa and Nebraska

The framework, which covers 193 countries and 36 territories, rests on a conceptual distinction between primary and secondary availability. Primary availability attributes cobalt according to the corporate ownership of the mines and processing facilities that extract it, asking which countries’ firms and investors hold the equity stakes that give them claims on output. Secondary availability attributes cobalt according to international trade, following the metal as it moves across borders in concentrates, intermediates and refined chemicals. The authors then compare both attribution perspectives against a combined baseline scenario built from geographic production and pre-trade viewpoints, which represents the traditional way of thinking about mineral endowment. The gap between the baseline and the ownership- and trade-adjusted pictures quantifies, for the first time in a systematic way, how much foreign direct investment and trade each reshape national cobalt access.

This matters because cobalt supply is extraordinarily concentrated. A handful of countries, with the Democratic Republic of the Congo dominating mine output, produce the overwhelming majority of the world’s primary cobalt, and a small number of refining hubs, most prominently China, process the bulk of intermediate materials into battery-grade compounds. Under a purely geographic lens, most countries appear to have essentially no cobalt availability at all. But ownership and trade complicate that picture enormously. Mining companies headquartered in one country routinely operate assets in another, and the resulting output flows through multi-stage supply chains that crisscross the globe before ending up in cathodes and finished batteries. The new framework is designed to capture exactly these layers of indirection.

The headline quantitative findings are striking. Relative to the combined baseline scenario, total cobalt availability is higher in 63.6 percent of the countries analyzed, meaning that when ownership and trade are taken into account, nearly two-thirds of nations end up with more effective access to cobalt than their geological endowment or territorial production would suggest. When the researchers weight primary and secondary availability equally in a composite measure, 72.7 percent of countries show a positive change. In other words, the mechanisms of globalized investment and commerce are not zero-sum transfers that enrich a few intermediaries at everyone else’s expense; for most countries, participation in these networks increases the cobalt they can effectively draw upon.

Perhaps the most consequential result, however, concerns concentration. Foreign direct investment and international trade do not change the total amount of cobalt available to humanity, the global sum is fixed by geology and extraction economics. What they do change is how that fixed total is spread across countries. The study finds that both mechanisms reduce the concentration of cobalt availability, redistributing effective access from a tiny cluster of production territories toward a much broader set of nations connected through investment ties and trade relationships. This reframing has immediate implications for how policymakers think about critical mineral security, because a country’s vulnerability to supply disruption depends less on whether cobalt is mined within its borders and more on the structure of the corporate and commercial networks in which it participates.

Technically, the dual-attribution approach required reconciling datasets that are rarely combined. Ownership attribution demands information on the corporate structure of mining and refining enterprises, including the ultimate parent companies behind joint ventures in producing countries, so that output can be assigned to the jurisdictions where controlling capital resides. Trade attribution, by contrast, relies on bilateral trade flows in cobalt-bearing commodities at multiple stages of processing, distinguishing ores and concentrates from unwrought intermediates and refined oxides and hydroxides. By computing both perspectives for every country and comparing them with the geographic-production and pre-trade baseline, the team could decompose the composite change in availability into a component driven by investment and a component driven by trade, exposing which channel dominates for each nation.

The results illuminate asymmetries that a single-lens analysis would hide. Countries that host mines but lack domestic ownership may show high geographic production while their ownership-attributed availability is far lower, with the difference flowing to the home countries of the investing firms. Conversely, countries with negligible mining but strong refining industries and dense import networks can accumulate substantial secondary availability through trade. The framework also captures intermediate cases, such as producing countries that have attracted foreign investment and simultaneously export processed goods, where primary and secondary attributions pull in different directions. Mapping these configurations across nearly two hundred economies turns an abstract debate about resource globalization into a concrete, country-by-country accounting.

For resource governance, the implications cut in several directions. Host countries, particularly in the developing world, may find that the cobalt extracted on their territory generates effective availability elsewhere, strengthening arguments for policies that link mining concessions to domestic processing, equity participation or export constraints. Exporting and investing countries, meanwhile, gain a quantitative basis for understanding how their corporate presence abroad translates into strategic material access, a consideration increasingly central to industrial strategies in the United States, the European Union, China and elsewhere. The authors emphasize that policies which account for both host-country and exporting-country perspectives are more likely to produce durable and equitable outcomes than measures designed from a single vantage point.

The study also arrives at a moment when cobalt demand trajectories are fiercely debated. Battery chemistries are shifting, with manufacturers reducing cobalt content in some cathode types while others, such as high-nickel formulations for long-range vehicles, remain cobalt-dependent. Recycling is expected to grow but cannot yet displace primary supply at scale. Against that backdrop, knowing who effectively holds cobalt availability, and through which channel, is essential input for scenario planning. A disruption in a producing region, a change in export policy, or a shift in ownership of a major mining asset propagates through the dual channels the framework describes, and the country-level sensitivity to each channel varies widely.

Methodologically, the dual-attribution framework is generalizable beyond cobalt. The same logic, attributing primary availability through corporate ownership and secondary availability through trade, could be applied to lithium, nickel, graphite, rare earth elements or any other critical mineral whose supply chains are globalized. As governments build critical mineral stockpiles, negotiate strategic partnerships and scrutinize foreign investment in mining sectors, tools of this kind offer a way to move beyond production statistics toward a genuinely structural understanding of resource access. The study’s central message is deceptively simple but far-reaching: in a globalized economy, the geography of what a country has and the geography of what a country can use are two different questions, and answering only the first one leaves policymakers flying blind on the second.

Subject of Research: How foreign direct investment and international trade redistribute country-level cobalt availability

Article Title: A dual-attribution framework reveals how foreign investment and trade redistribute cobalt availability

Article References: Liu, L., Zhang, L., Jiang, S., Li, Y., Li, R., Mei, Z., Yuan, Z., & Chen, J. (2026). A dual-attribution framework reveals how foreign investment and trade redistribute cobalt availability. Nature Communications. https://doi.org/10.1038/s41467-026-78222-4

Image Credits: AI Generated

DOI: 10.1038/s41467-026-78222-4

Keywords: cobalt, foreign direct investment, international trade, critical minerals, supply chains, resource governance, battery materials, mineral availability, dual-attribution framework, Nature Communications, mining ownership, global concentration

The research team, led by Xuena Liu and Haibin Liu, constructed a multilayer supply chain network centered on nine of the world’s dominant battery manufacturers, including CATL, BYD, LG Energy Solution, Panasonic, SK Innovation, CALB, Samsung SDI, Gotion, and EVE Energy. Using the FactSet Revere database of interfirm supply relationships, supplemented by corporate disclosures and stock-market volatility data, they built a directed, weighted network spanning mineral extraction, intermediate materials, battery assembly, electric vehicle manufacturing, and recycling. The timing could hardly be more pressing: global electric vehicle battery demand reached 950 gigawatt-hours in 2024 and is projected to exceed 3 terawatt-hours by 2030, while the International Energy Agency expects electric vehicles and energy storage to account for more than 90 percent of future lithium demand.

The network’s anatomy alone tells a striking story. All nine manufacturer-centered networks follow power-law degree distributions, meaning a few hub firms dominate connectivity while most firms maintain only a handful of relationships. The commodity trader Glencore, the Australian lithium producer Pilbara Minerals, and the Chinese materials firm CNGR each maintain business relationships with seven to nine core battery makers, forming what the authors call cross-layer super-hubs. Meanwhile, most shared nodes connect to only two manufacturers. The networks led by Samsung SDI and LG Energy Solution are strongly correlated with each other and with Panasonic’s, implying that a shock at a shared supplier could transmit simultaneous damage across multiple corporate ecosystems. By contrast, the SK Innovation- and Gotion-led networks show slightly negative correlations, hinting at potential substitutability at certain supply nodes.

When the researchers simulated shortages of increasing intensity, from 10 percent to a complete cutoff of supply, lithium emerged as the most damaging mineral by a clear margin, with network losses ranking lithium above cobalt above nickel under every scenario. This asymmetry reflects chemistry as much as geology. Lithium is an indispensable element in every lithium-ion battery, whereas cobalt is progressively being engineered out of newer cathode designs, and nickel benefits from abundant resources and diversified supply. At a shortage intensity of 0.9, the CATL-dominated network suffered losses of 1171.42 under lithium scarcity, compared with 909.05 for cobalt and 918.45 for nickel. The BYD-led network fared worst of all under lithium stress, reaching 2587.49, a consequence of its enormous lithium iron phosphate production volumes and vertically integrated business model.

Manufacturer-level losses varied dramatically, defying any simple ranking of corporate might. CATL, the world’s largest battery maker, recorded the highest losses across all three minerals, ranging from roughly 130 to 160 under lithium shortages, a pattern the authors attribute to its simultaneous operation of both LFP and high-nickel NMC pathways, which broadens its mineral exposure and concentrates its supplier base. SK Innovation’s network proved exceptionally vulnerable to nickel because its product portfolio is dominated by high-nickel NCM811 cells, while EVE Energy’s cobalt-containing cathode materials and stringent certification requirements concentrated its dependence on upstream refining hubs. Panasonic, by contrast, recorded the lowest losses and responded only weakly to changes in shortage intensity, reflecting its comparatively low structural exposure.

Tracing exactly where the damage came from produced some of the study’s most actionable findings. Under cobalt shortages, a single firm, Glencore, accounted for between 73.43 and 92.75 percent of CATL’s attributed losses, a near-single-source structure in which one disruption could rapidly amplify risk downstream. Nickel losses for CATL were dominated by Glencore and the Indonesian producer Trimegah Bangun Persada, the latter reflecting the localized supply concentration fostered by Indonesia’s nickel ore export ban. Lithium losses were far more dispersed, spread across Tianqi Lithium, Ganfeng Lithium, Yahua, and Albemarle. Path analysis of a total Tianqi Lithium shortage showed that two pathways, a direct cross-chain link to BYD and a long cascade through the midstream materials firm BTR, together accounted for roughly 70 percent of BYD’s total impact, with the cathode makers Hunan Yuneng and Ronbay emerging as the most frequently traversed intermediary nodes.

Perhaps the most surprising result concerns how the industry recovers. The researchers decomposed recovery into three mechanisms: direct restoration through existing supply relationships, indirect recovery through shared nodes that connect multiple manufacturer networks, and recovery through newly established supply links. Indirect recovery dominated overwhelmingly, contributing 70 to 74 percent of total recovery, followed by new links at 15 to 18 percent, with direct recovery contributing a mere 10 to 12 percent. In other words, when a mineral shortage strikes, battery makers do not primarily heal through their own contracted suppliers; they heal through the network’s hidden cross-connections, as shared suppliers reallocate resources across tiers. EVE Energy relied most heavily on forging new relationships, at 35 to 40 percent, while Gotion addressed roughly 40 percent of its shortfalls through existing ties. Recovery pathways themselves were highly concentrated, repeatedly routing through a small group of firms including Hunan Zhongke Electric, Hunan Yuneng, and Tianqi Lithium.

To quantify resilience across the full disruption-and-recovery cycle, the team borrowed the marginal-response logic of price elasticity of demand, regressing each manufacturer’s cumulative loss rate on shortage intensity to obtain a resilience response coefficient. The results exposed a crucial disconnect between loss magnitude and loss sensitivity. Under lithium shortages, CATL combined the highest cumulative losses with the longest recovery requirement, roughly 88 to 90 cycles, and a significantly positive response coefficient of 0.071. Under cobalt shortages, CALB showed the strongest marginal response at 0.420, while under nickel shortages all nine manufacturers responded significantly, with Samsung SDI and EVE Energy posting the highest coefficients at 0.209 and 0.138 despite suffering relatively low cumulative losses. Samsung SDI even recorded a negative coefficient under lithium stress, indicating attenuating losses as intensity grew. High loss, the study concludes, does not necessarily coincide with high sensitivity, and loss rankings alone cannot capture corporate vulnerability.

The findings survived an unusually thorough battery of robustness tests. Inventory buffering of 90 days cut high-end loss rates by up to 24.7 percent under cobalt stress but left manufacturer rankings essentially unchanged, with Spearman correlations above 0.93. Convex nonlinear propagation, meant to mimic order-batching and capacity constraints, raised median cumulative losses by 51 percent yet preserved both the lithium-over-cobalt-over-nickel ordering and the vulnerability rankings. Across 1,500 Monte Carlo parameter combinations, indirect recovery remained dominant with average contributions near 79 percent. Parameterized adaptation, simulating strategic inventories, material substitution, chemistry switching, and contract renegotiation, cut mean cumulative losses by up to 34.7 percent and recovery cycles by 47.4 percent. Recycling networks built around GEM and Umicore already reduced system losses by 10.35 percent under cobalt and 9.69 percent under nickel at full shortage intensity, though strengthening recycling paradoxically increased cobalt losses in some scenarios by rerouting propagation pathways.

The implications reach well beyond corporate boardrooms. The authors argue that critical mineral governance must extend beyond counting reserves and import dependence to monitor midstream processors, shared suppliers, and the deep interfirm relationships through which risk actually travels. Because a small number of pathways contribute disproportionately to downstream losses, targeted interventions such as dual sourcing, pre-qualified backup suppliers, and inventory buffers along dominant routes offer more leverage than blanket diversification. For the energy transition as a whole, the message is sobering: the feasibility of electrifying transport depends not only on how much lithium, cobalt, and nickel the world can extract, but on the resilience of a network whose most important nodes are often invisible until the moment they fail.

Subject of Research: Resilience of lithium-ion battery supply chains to critical mineral shortages

Article Title: Resilience assessment of lithium ion battery supply chains under critical mineral shortages

Article References: Liu, X., Huang, H., An, F., Dong, X., Fang, W., Wang, Y., Zhang, H., Liu, Y., & Liu, H. (2026). Resilience assessment of lithium ion battery supply chains under critical mineral shortages. iScience, 29(10), Article 117703. https://doi.org/10.1016/j.isci.2026.117703

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117703

Keywords: lithium-ion batteries, supply chain resilience, critical minerals, lithium, cobalt, nickel, electric vehicles, risk propagation, network analysis, CATL, BYD, energy transition

The research, published in the journal Discover Soil by Francesca Pedron and Gianniantonio Petruzzelli of Italy’s National Research Council’s Institute of Research on Terrestrial Ecosystems in Pisa, tackles a question that has been largely ignored: what happens to a soil’s ability to trap cobalt long after compost spreading has stopped? Most studies of organic amendments focus on soils that are actively being treated. The Italian team instead examined soils from a single Tuscan farm where compost applications had ceased either five or ten years earlier, comparing them with a neighboring field that had never received compost at all.

Cobalt occupies an unusual position among trace metals. In tiny amounts it is essential, serving as the metallic core of vitamin B12 and supporting crop growth, but above certain thresholds it becomes harmful to plants, disrupting nutrient transport within cells and producing symptoms such as leaf yellowing, premature leaf drop, reduced photosynthesis, and stunted biomass. It enters soil from natural events such as volcanic eruptions and forest fires, and from human activities including mining, smelting, road traffic, and the manufacture of cobalt-containing alloys and chemicals. Material flow analyses indicate that its dispersion in the environment is increasing as demand for batteries and green technologies accelerates, and recent machine-learning maps of European soils have revealed rising cobalt concentrations in some agricultural areas.

Whether that rising cobalt actually threatens crops and groundwater depends on a set of chemical reactions collectively called sorption, the transfer of dissolved metal ions from soil water onto solid soil surfaces. A soil with strong sorptive capacity holds cobalt immobilized, keeping it away from plant roots and aquifers. A soil with weak sorption lets the metal remain in solution, where it can be taken up by crops or leached away. The researchers hypothesized that compost-induced changes in soil organic matter and acidity would persist long enough to maintain enhanced cobalt sorption for a decade or more, and their experiments were designed to test exactly that.

The three soils came from the plough layer of a farm in the Province of Pisa, in a flat alluvial plain with a Mediterranean climate. Two of them had received green compost, produced from garden trimmings, crop residues, and other plant waste, for eight consecutive years at a rate of five megagrams of dry matter per hectare per year. On one plot, applications stopped ten years before sampling; on another, five years before. The third plot had never been treated. Texture, iron content, and total cobalt concentration were nearly identical across all three soils, but the chemical fingerprints of compost were unmistakable. Organic matter had risen from 1.15 percent in the untreated soil to 2.08 percent in the ten-year-old plot and 3.13 percent in the five-year-old one, while pH had shifted from a slightly acidic 6.25 to near-neutral values around 7.0. Cation exchange capacity, a measure of the soil’s ability to hold positively charged ions, climbed in parallel.

Those differences translated directly into cobalt retention. In laboratory batch experiments, the team shook one-gram soil samples with cobalt nitrate solutions of increasing concentration for twelve hours at controlled temperatures, then measured how much metal disappeared from solution. Fitting the resulting curves to the Langmuir isotherm model revealed maximum sorption capacities of 222 millimoles per kilogram in the five-year soil and 196 in the ten-year soil, against just 141 in the untreated control. The shape of the isotherms, an L-type pattern, showed that at low cobalt concentrations sorption rose almost linearly, indicating that high-affinity binding sites dominate initially; only as those sites fill do weaker domains take over, flattening the curve toward a plateau.

The mechanism behind this enhanced retention lies in the chemistry of compost-derived organic matter. Humified materials introduce abundant carboxyl, phenolic, and hydroxyl functional groups that form stable complexes with divalent cations such as cobalt. The near-neutral pH produced by composting amplifies the effect in two ways: it reduces competition between cobalt ions and hydrogen ions for reactive surfaces, and it encourages the deprotonation of those functional groups, making them more negatively charged and chemically reactive. Experiments that varied the ionic strength of the background solution added a further clue. Sorption in the untreated soil dropped by 40 to 48 percent as ionic strength increased, a signature of weak, electrostatically held outer-sphere complexes. In the compost-amended soils the decline was far smaller, 18 to 22 percent in the five-year soil and 28 to 36 percent in the ten-year one, pointing to a predominance of inner-sphere complexes, in which cobalt coordinates directly and strongly with organic and mineral surfaces.

Thermodynamic analysis reinforced the picture. Across temperatures from 298 to 318 kelvin, the Gibbs free energy of sorption was negative in all soils, confirming a spontaneous process, but the values were most favorable in the compost-amended plots. Enthalpy changes were positive, indicating an endothermic process that likely reflects the energy cost of partially dehydrating cobalt ions and forming specific surface complexes, and entropy changes were negative, consistent with metal ions becoming immobilized on ordered surface sites. The distribution coefficient, a ratio that summarizes how strongly a soil partitions cobalt between solid and solution phases, told the same story: differences among the soils were largest at low cobalt concentrations, precisely the range most relevant to real agricultural contamination, and converged only as high-affinity sites approached saturation.

Perhaps the most striking evidence came from desorption experiments, in which previously loaded soils were challenged with a harsh 0.5 molar calcium chloride solution designed to displace loosely held metal. In the untreated soil, between 1.6 and 24 percent of the sorbed cobalt was released, depending on loading. In the ten-year compost soil the released fraction ranged from 1.2 to 18 percent, and in the five-year soil from just 0.6 to 11 percent. At low cobalt loadings, desorption was minimal in all soils, confirming that the first metal ions to arrive occupy high-affinity sites and are effectively locked in place. The cobalt that resisted even this aggressive extraction can reasonably be considered non-bioavailable, meaning it is unlikely to reach plants or soil microorganisms.

The authors are careful to note the limits of their work. The compost’s own cobalt content was never measured because Italian law does not require it, so a complete mass balance was impossible, although total soil cobalt did not differ among the three plots, suggesting the compost added no detectable metal. Laboratory conditions, with fixed temperatures and equilibration times, cannot fully reproduce the complexity of field soils, including microbial activity, and the results apply specifically to the soils studied rather than to all soil types. Long-term effects will also depend on compost composition, climate, and farming practices. Even so, the central finding stands: in Mediterranean soils, where organic matter decomposes slowly enough to persist for decades, a single decade of composting left a chemical legacy that still suppressed cobalt mobility ten years later. As cobalt demand surges with the ecological transition, the study suggests that the humble practice of returning organic waste to farmland is not merely a fertility tool but a long-term instrument for keeping a critical, and potentially toxic, metal out of the food chain.

Subject of Research: Long-term cobalt sorption and desorption behavior in aged compost-amended Mediterranean agricultural soils

Article Title: Cobalt sorption in aged compost-amended soils

Article References: Pedron, F., & Petruzzelli, G. (2026). Cobalt sorption in aged compost-amended soils. Discover Soil, 3(1), Article 109. https://doi.org/10.1007/s44378-026-00273-2

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00273-2

Keywords: cobalt, compost, soil organic matter, sorption, desorption, Langmuir isotherm, heavy metals, soil chemistry, Mediterranean soils, bioavailability, trace metal contamination, sustainable soil management