The research team, led by Aleeza Jalil with Mehwish Jamil Noor as corresponding author, set out to answer a deceptively simple question: how much toxic metal do consumers actually ingest when they eat vegetables purchased from local markets, and does that dose matter for health? To find out, they obtained nine vegetable species from wholesale markets in Islamabad and Rawalpindi, cities that together anchor the Pothohar plateau and supply a large urban population. The vegetables were analyzed using Flame Atomic Absorption Spectrophotometry, a well-established analytical technique in which a sample is ashed, dissolved, and aspirated into a flame that excites metal atoms; the wavelength and intensity of the light those atoms absorb reveal which metals are present and at what concentration. This method allowed the team to quantify four target metals: cadmium, chromium, nickel, and copper.

The numbers the spectrophotometer returned were striking. Cadmium ranged from 0.103 milligrams per kilogram in spearmint, Mentha spicata, sampled in Islamabad, to 2.28 milligrams per kilogram in potato, Solanum tuberosum, from Rawalpindi. Chromium varied from 0.09 milligrams per kilogram in Islamabad samples to a high of 7.52 milligrams per kilogram in coriander, Coriandrum sativum, purchased in Rawalpindi. Nickel spanned from 1.24 milligrams per kilogram in coriander from Islamabad to 21.18 milligrams per kilogram in bitter gourd, Momordica charantia, from Rawalpindi. Copper, the least toxic of the four but still problematic in excess, ranged from 1.37 milligrams per kilogram in bitter gourd from Rawalpindi to 24.98 milligrams per kilogram in tomato, Solanum lycopersicum, from Islamabad. Several vegetables, the authors report, exceeded permissible limits particularly for cadmium, chromium, and nickel.

What makes these figures concerning is the toxicology of the metals themselves. Cadmium, ranked among the highest on the United States Agency for Toxic Substances and Disease Registry’s substance priority list, accumulates in the kidneys and skeleton over decades and is classified as a human carcinogen; there is no beneficial biological role for it in the human body. Chromium, depending on its oxidation state, can range from an essential trace nutrient to the highly toxic hexavalent form that damages DNA. Nickel exposure is associated with dermatitis, respiratory irritation, and carcinogenic outcomes in certain compounds. Copper, in contrast, is an essential micronutrient required for enzyme function, but chronic overexposure damages the liver and gastrointestinal tract. Because plants take up these metals from soil and irrigation water and concentrate them in edible tissues, vegetables act as a direct conduit from contaminated growing environments to the human dinner plate.

The Pothohar region’s contamination profile has plausible sources rooted in its rapid urbanization. Rawalpindi and Islamabad host dense traffic corridors and industrial activity, and earlier work by some of the same research community has documented air pollution in the twin cities linked to heavy transportation and industry. Atmospheric deposition of metal particles onto leafy surfaces, irrigation with contaminated water, and application of fertilizers or sewage-derived amendments to peri-urban fields are all recognized pathways by which metals enter vegetable crops. Leafy herbs such as coriander and mint are particularly efficient accumulators because their large surface areas intercept airborne particles, while their fine root systems mine the soil intensively. The fact that some of the highest concentrations in this study appeared in coriander and bitter gourd from Rawalpindi is consistent with that pattern, although the study’s market-based design means it captures the produce supply as a whole rather than tracing individual farms.

To translate concentrations into health consequences, the team deployed the standard battery of dietary risk metrics used by environmental health agencies worldwide. The Estimated Daily Intake, or EDI, multiplies the measured metal concentration by the amount of vegetable a typical person eats each day, divided by body weight, yielding a dose in milligrams per kilogram of body weight per day. The Target Hazard Quotient, or THQ, compares that dose against a reference dose, the level below which regulatory agencies assume no appreciable harm over a lifetime of exposure. A THQ below one is considered acceptable; values above one signal potential non-carcinogenic risk. Summing the THQs across metals and vegetables produces the Hazard Index, or HI, which captures the cumulative burden of exposure to a mixture of metals. Finally, the Target Cancer Risk, or TCR, estimates the incremental lifetime probability of developing cancer from carcinogenic metals such as cadmium and chromium.

The results of this risk calculus reveal an important nuance. When each metal was evaluated on its own through the Estimated Daily Intake, exposures remained within acceptable limits, suggesting that no single vegetable delivers a dangerous dose of any one metal in a typical serving. But the cumulative indices told a different story. The Hazard Index and the Target Cancer Risk both suggested potential non-carcinogenic and carcinogenic risks, especially among children. The reason is arithmetic: children eat more food per kilogram of body weight than adults, so the same metal concentration in a vegetable translates into a higher dose for a smaller body. Their developing organs and longer remaining lifetimes further amplify both non-carcinogenic effects and lifetime cancer probability. A diet built around multiple contaminated vegetables, consumed daily over years, quietly stacks exposures that individually look tolerable but collectively cross thresholds.

This distinction between individual and cumulative risk is where the study’s significance lies, and it echoes a broader shift in how food safety is being assessed globally. Recent probabilistic assessments of dietary heavy metal exposure in China, Bangladesh, India, and Nigeria have converged on the same conclusion: single-metal, single-food evaluations systematically underestimate real-world risk because diets are diverse and contaminants co-occur. A companion systematic review by members of the same team, also published in Environmental Monitoring and Assessment, documented the global trend of rising heavy metal concentrations in vegetables and the spread of health risk assessment frameworks to quantify them. The Pothohar findings slot into that international picture while adding locally specific data from a region where such measurements had been sparse.

The authors frame their results as a call for action on three fronts. First, continuous monitoring of food quality is needed, since market surveillance of vegetables for metal contamination is not currently routine in Pakistan, and contaminated produce can move through wholesale channels without detection. Second, agricultural practices require improved regulation, including controls on irrigation water quality, fertilizer composition, and the siting of vegetable plots near roads and industry, because preventing uptake at the source is far more effective than testing finished produce. Third, public awareness must increase, so that consumers understand which vegetables and which markets carry higher burdens and how washing, peeling, and dietary diversification can modestly reduce exposure. The research was funded by Fatima Jinnah Women University under grant ORIC/FJWU/2025/308 as part of a project evaluating heavy metal dietary exposure and health risks from vegetable consumption in the twin cities.

For the millions of people who shop in the bazaars of Rawalpindi and Islamabad, the study does not mean vegetables should be abandoned; plant foods remain central to nutrition and disease prevention, and the authors themselves emphasize food safety rather than dietary avoidance. What it does mean is that the safety of those foods depends on environmental conditions far upstream of the market stall, in the soil, water, and air of the farms that supply them. As urbanization intensifies across South Asia and demand for fresh produce grows, the invisible chemistry of contamination will increasingly determine public health outcomes. Studies like this one, which convert parts-per-million measurements into concrete risk estimates for adults and children, provide the evidence base that regulators, farmers, and consumers need to act before cumulative exposure becomes cumulative harm.

Subject of Research: Heavy metal contamination of market vegetables and associated dietary health risks in the Pothohar region of Punjab, Pakistan

Article Title: Dietary exposure and health risks associated with selected vegetables from Pothohar Region of Punjab, Pakistan

Article References: Jalil, A., Noor, M. J., Bukhari, A. L., Shaban, A., & Iram, S. (2026). Dietary exposure and health risks associated with selected vegetables from Pothohar Region of Punjab, Pakistan. Environmental Monitoring and Assessment, 198(9), Article 1020. https://doi.org/10.1007/s10661-026-15848-3

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15848-3

Keywords: heavy metals, cadmium, chromium, nickel, copper, vegetables, food safety, dietary exposure, health risk assessment, Pakistan, Pothohar region, Environmental Monitoring and Assessment

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

Nickel oxide has been a perennial favorite in pseudocapacitor research for good reason. Unlike carbon electrodes, which store charge electrostatically at the surface, nickel-based oxides participate in fast, reversible surface redox reactions in alkaline electrolytes, where hydroxide ions interact with nickel sites to store charge chemically. This faradaic mechanism, the hallmark of pseudocapacitance, can pack far more charge into a given mass of material than pure double-layer storage. The catch is kinetics: pristine nickel oxide is a relatively poor electrical conductor, and its redox reactions can stall when electrons and ions cannot reach active sites quickly enough. Researchers have therefore spent years trying to open up the material’s electronic structure and morphology without sacrificing its intrinsic charge-storage capacity.

The team, led by researchers including Muhammad Shahbaz, Mohsin Saleem, Jung Hyuk Koh, and Kamran Ali, took a dual-element approach. Using a rapid autocombustion synthesis—a self-sustaining exothermic reaction that converts precursor solutions into oxide powders in moments—they fabricated both pristine nickel oxide (NO) and a cobalt- and calcium-co-modified variant (CCNO). The choice of dopants is chemically deliberate. Cobalt, a neighboring transition metal with its own rich redox chemistry, is known to enhance electronic conductivity and contribute additional redox-active sites. Calcium, an alkaline earth metal with no redox activity of its own, acts as a structural modifier, perturbing the oxide lattice and influencing grain growth and morphology. Together, the two elements were intended to tune both the electronic and the microstructural dimensions of charge storage simultaneously.

X-ray diffraction patterns of the synthesized powders indexed to a hexagonal phase assigned to nickel(III) oxide, Ni2O3, according to reference card JCPDS 014-0481. The authors are careful to flag a caveat here: without spectroscopic valence analysis to confirm the nickel oxidation state, this phase assignment remains provisional, and the material is referred to throughout simply as nickel oxide. Such caution matters in a field where the distinction between NiO and Ni2O3 carries real electrochemical consequences, since trivalent nickel sites are associated with enhanced redox activity. The diffraction data nevertheless establish that co-modification did not destroy the parent oxide framework, preserving the crystalline host while subtly altering its internal structure.

Field-emission scanning electron microscopy revealed perhaps the most visually consequential effect of the co-modification. The CCNO powder displayed a connected, coarsened morphology—a network of interlinked particles rather than isolated grains. This architecture is not merely cosmetic. In an electrode, ions from the electrolyte must diffuse through and across the material to reach redox-active sites, and electrons must percolate through the particle network to the current collector. A connected, coarsened structure provides continuous pathways for both species, reducing diffusion lengths and interfacial resistance. The researchers argue that this morphology directly accelerates the redox kinetics, allowing the electrode to sustain its capacitive behavior even at high charge-discharge rates where poorly connected materials typically fail.

To probe the electronic consequences of co-modification, the team turned to optical spectroscopy. Ultraviolet-visible absorption, photoluminescence emission, and Raman spectra collectively revealed structural and electronic variations induced by the cobalt and calcium incorporation. These techniques serve as sensitive fingerprints of how dopants perturb defect populations, band structure, and lattice vibrations—changes that translate directly into altered charge transport behavior. While the paper does not claim a single dominant mechanism, the spectroscopic evidence supports the picture of a modified oxide whose electronic landscape has been reshaped by the dual-element treatment, priming it for faster electrochemical response.

The electrochemical results are where the strategy pays off quantitatively. In a three-electrode configuration, the CCNO electrode blended with activated carbon achieved a maximum specific capacitance of 318 farads per gram at a current density of 2 amperes per gram. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge measurements together characterized the electrode’s behavior across timescales, with impedance data revealing reduced charge-transfer resistance consistent with the morphological and electronic modifications. The researchers are transparent about an important limitation: because pristine and singly modified reference electrodes were not synthesized under identical conditions, the improvement of CCNO over pristine nickel oxide cannot be cleanly apportioned between the cobalt-calcium incorporation and the conductive carbon network. Both contributions are discussed explicitly rather than hidden behind a single attribution.

The true test of any electrode material is how it performs in a complete device, where two dissimilar electrodes must operate in tandem across a shared voltage window. The researchers assembled an asymmetric hybrid supercapacitor pairing the CCNO/AC composite as the positive electrode with activated carbon as the negative electrode. Normalized to the combined active mass of both electrodes, the device delivered 160 farads per gram at a scan rate of 10 millivolts per second and 121 farads per gram at 2 amperes per gram. More strikingly, it achieved an energy density of 32.9 watt-hours per kilogram, with power density climbing from approximately 1.6 to 6 kilowatts per kilogram as the current density increased from 2 to 7 amperes per gram. These figures place the device in competitive territory for hybrid supercapacitors, approaching the energy storage regime where batteries begin to matter while retaining the power delivery and cycle life that define supercapacitor technology.

Durability, the quiet killer of promising electrode materials, held up impressively. Over 3000 galvanostatic charge-discharge cycles, the CCNO/AC device retained a coulombic efficiency of approximately 100 percent, meaning that nearly every charge stored during each cycle was recovered on discharge with virtually no parasitic losses. This kind of stability is essential for real-world deployment, where electrodes must withstand thousands of deep cycles without degrading. The structural integrity of the co-modified oxide, combined with the robust carbon network, appears to provide the mechanical and electrochemical resilience needed to sustain repeated redox cycling without capacity fade.

What makes this work notable beyond its headline numbers is its honest accounting of mechanisms and its demonstration that dual-element modification can be a rational design tool rather than trial-and-error alchemy. Cobalt contributes redox activity and electronic conductivity; calcium reshapes morphology and lattice structure; and the activated carbon network provides the conductive scaffold that ties everything together. The synergy among these three elements—engineered oxide, structural modifier, and carbon network—produces an electrode whose ion diffusion pathways, surface redox reactions, and charge transfer kinetics are all simultaneously optimized. As the demand for fast-charging, long-lived energy storage grows across renewable energy integration, electric transportation, and portable electronics, strategies like this one that squeeze more performance from cheap, scalable materials may prove decisive in bringing hybrid supercapacitors from the laboratory bench to the power grid.

Subject of Research: Tailoring redox activity and electrochemical kinetics of nickel oxide through Co and Ca co-modification for high-performance hybrid supercapacitors

Article Title: Tailoring redox activity and electrochemical kinetics of nickel oxide through Co and Ca co-modification for high-performance hybrid supercapacitors

Article References: Shahroz, Shahbaz, M., Saleem, M., Khan, M. Z., Irshad, M., Sharif, S., Koh, J. H., Mureed, S., Ghaffar, A., Shakir, I., & Ali, K. (2026). Tailoring redox activity and electrochemical kinetics of nickel oxide through Co and Ca co-modification for high-performance hybrid supercapacitors. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13810-9

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13810-9

Keywords: Tailoring, redox, activity, electrochemical, kinetics, nickel, oxide, co-modification, high-performance, hybrid, supercapacitors, scientific research

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

Researchers Solomon C. Onuchukwu, Innocent C. Nnorom, and Jude I. Ogubuike set out to measure the concentrations of four toxic metals—silver (Ag), cadmium (Cd), nickel (Ni), and lead (Pb)—in the plastic components of discarded mobile phones commonly used in Nigeria. Their findings, published in Discover Chemistry, reveal a complex and sometimes alarming picture. Across all brands, mean concentrations were 9.2 ± 1.9 mg/kg for silver, 46.2 ± 12.5 mg/kg for cadmium, 738 ± 1072 mg/kg for nickel, and 62.4 ± 32.0 mg/kg for lead. Most strikingly, nickel levels in certain samples were unexpectedly high, with one brand exceeding the total threshold limit concentration (TTLC) regulatory limit of 2,000 mg/kg, reaching a maximum of approximately 2,983 mg/kg.

The team collected twenty-five obsolete mobile phones representing five major brands—Tecno, Infinix, Itel, Samsung, and Apple—from repair workshops in Uyo, the capital of Akwa Ibom State in southeastern Nigeria. Five units of each brand were selected, with devices spanning production years from approximately 2015 to 2022. Repair shops were chosen deliberately because they serve as major aggregation points for discarded, damaged, or obsolete devices awaiting repair or disposal. To reduce selection bias, the researchers gathered phones from multiple independent repair shops, selecting devices based on availability and physical condition rather than brand preference or performance.

Once collected, each phone was partially disassembled using stainless steel screwdrivers and pliers, then separated into its major components: printed wiring boards, liquid crystal displays, and plastics. The plastic parts were covered with clean cloth to prevent cross-contamination, crushed with a standard hammer, and then reduced in size by cutting with stainless steel scissors. All tools were thoroughly cleaned with ethanol and lint-free wipes between samples, and each component was stored in labeled containers to avoid mixing materials from different devices. Crucially, the samples were analyzed in their unwashed state—a deliberate choice designed to reflect the real-world contamination levels of discarded e-waste plastics as they actually enter the waste stream.

Approximately 0.5 grams of each sample was digested using EPA Method 3050B, a standardized acid digestion procedure employing 65% nitric acid, 35% hydrochloric acid, and 30% hydrogen peroxide in a 1:1:1 ratio. The samples were heated to 90°C and then taken to near dryness before being resolubilized in deionized water and filtered. The resulting digest was analyzed for Pb, Cd, Ni, and Ag using an Agilent 720-ES Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), with emission intensities recorded at the most sensitive wavelengths for each target metal: 328.068 nm for silver, 214.439 nm for cadmium, 231.604 nm for nickel, and 220.353 nm for lead. Quality control procedures included multi-point calibration curves with linearity of R² ≥ 0.995, spike recovery studies yielding recoveries between 80% and 100%, procedural blanks, and replicate analyses performed in triplicate.

Statistical analysis using one-way ANOVA at a 95% confidence level revealed significant inter-brand differences for silver, nickel, and lead, with nickel and lead showing particularly strong brand-related variation. Brand C and brand E frequently stood out from the pack. The distribution patterns were equally revealing: cadmium concentrations were below 50 mg/kg in approximately 75% of samples, silver remained below this threshold in all samples, but nickel stayed below 50 mg/kg in only 20% of samples. Furthermore, 40% of samples exceeded 500 mg/kg for nickel—a level far above what would be expected from the plastic polymer matrix alone. Lead levels fell below 50 mg/kg in 55% of samples, with 20% falling in the elevated 100–500 mg/kg range.

The researchers attribute the elevated nickel concentrations to several possible sources. Nickel-containing components such as connectors, contacts, and plated parts located within electronic assemblies may be enclosed by or attached to plastic housings, allowing metal fragments to transfer onto plastic surfaces during dismantling and mechanical processing. Contamination from mixed electronic waste streams, residual fluxes, oxidation products, tool abrasion during disassembly, and metal-laden fumes generated during soldering and repair work may all contribute to the observed variability. This interpretation is consistent with earlier studies reporting wide ranges of nickel levels in waste mobile phone plastics, with occasional high outliers linked to heterogeneous material composition and exogenous contamination.

When the measured concentrations were compared with TTLC regulatory limits—standards developed by the Department of Toxic Substances Control to determine total concentrations of specific components in a sample—most metals were generally below their respective thresholds, suggesting that the plastic components do not pose an immediate critical risk under standard disposal scenarios. The predominantly sub-threshold levels may reflect the impact of regulatory efforts such as the European Union’s Restriction of Hazardous Substances (RoHS) Directive, which has restricted the use of toxic metals in consumer electronics since the mid-2000s. Earlier European Community directives, including the Packaging Directive (EC Directive 94/62/EEC) and Directive 91/338/EC, had already set limits of 100 mg/kg for cadmium and total metals in plastic materials.

However, the nickel exceedance in brand C samples, combined with the persistent nature of these metals and their potential for leaching under landfill or incineration conditions, raises significant concerns about long-term environmental contamination. The authors emphasize that TTLC values reflect total elemental concentrations and do not directly evaluate the mobility or leaching potential of metals under environmental conditions. Toxicity Characteristic Leaching Procedure (TCLP) tests, which simulate contaminant release under landfill conditions, would provide a more direct assessment of environmental risk. Previous studies have shown that roughly 50% of TCLP extracts for lead from end-of-life mobile phone components surpassed 5 mg/L, indicating widespread non-compliance, while another investigation reported lead leachate values ranging from 7.21 to 84.38 mg/L in plastic housings and printed wiring boards.

The broader implications extend far beyond laboratory measurements. In Nigeria and similar developing countries, e-waste management is often informal and unregulated, with an estimated 100,000 individuals employed in manually collecting and dismantling electronic waste to recover valuable components. These workers face direct exposure to toxic substances, including lead, which can damage the liver, kidneys, and nervous system and impair cognitive development, and nickel, which is associated with dermatitis and bronchial asthma. According to the World Health Organization, more than 18 million children and adolescents are now active in scavenging for e-waste, often without any protective equipment. Once released into the environment through improper disposal pathways such as open dumping, landfill leaching, or uncontrolled burning, toxic metals can migrate into soil, surface water, and groundwater systems, entering ecological and human exposure pathways through ingestion of contaminated food crops, inhalation of contaminated dust, or dermal contact with polluted soils. The findings underscore the urgent need for improved end-of-life management strategies, formal recycling infrastructure, and stronger regulatory oversight to minimize the environmental and public health impacts of discarded mobile phone components in developing regions.

Subject of Research: Concentrations of toxic metals in plastic components of discarded mobile phones from five brands commonly used in Nigeria

Article Title: Evaluation of toxic metals in plastic components of discarded mobile phones commonly used in Nigeria

Article References: Onuchukwu, S. C., Nnorom, I. C., & Ogubuike, J. I. (2026). Evaluation of toxic metals in plastic components of discarded mobile phones commonly used in Nigeria. Discover Chemistry, 3(1), Article 432. https://doi.org/10.1007/s44371-026-00892-2

Image Credits: AI Generated

DOI: 10.1007/s44371-026-00892-2

Keywords: e-waste, mobile phones, toxic metals, nickel, lead, cadmium, silver, plastic components, Nigeria, ICP-OES, TTLC, informal recycling

The solvent at the heart of the work is 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, abbreviated [BMPyrr][TFSI]. Ionic liquids are salts that stay liquid near room temperature, and their properties can be tuned by swapping either the cation or the anion. This particular pyrrolidinium salt is hydrophobic, chemically stable and dense, at about 1.40 grams per cubic centimeter, which matters enormously for the extraction scheme the team used. In dispersive liquid-liquid microextraction, or DLLME, the ionic liquid is first dissolved in a water-miscible disperser and then rapidly injected into the aqueous sample. The sample instantly turns cloudy as countless microscopic ionic-liquid droplets form, creating a vast interfacial area across which metal species can migrate. A spin in the centrifuge then coalesces the droplets into a dense, sedimented receiving phase that can be collected with a pipette.

What makes this study unusual is that it applied the technique not to trace analysis in clean laboratory water, the usual domain of DLLME, but to genuinely dirty industrial matrices. The researchers sampled five real wastewater streams at an effluent treatment facility in Malumichampatti, Coimbatore District, drawing from pharmaceutical manufacturing, industrial sewage, leather tanning, paint and coating operations, and metal electroplating. Flame atomic absorption spectroscopy revealed chromium in every single stream, from 0.28 parts per million in pharmaceutical wastewater to 21.42 parts per million in the composite industrial sewage sample. The plating wastewater, at 10.31 parts per million chromium, was selected for the recovery experiments because it combined a comparatively high metal loading with a traceable process origin.

The chemistry of these effluents is punishing. The chromium-bearing stream measured a pH of 10.0, total dissolved solids of 9742 milligrams per liter and suspended solids of 3471 milligrams per liter, with a total hardness of 568 milligrams per liter as calcium carbonate. Such a background can interfere with dispersion, sedimentation and phase disengagement, which is precisely why conventional treatments like precipitation, ion exchange and membrane filtration often lose selectivity or become economically prohibitive when target metals occur at trace-to-intermediate concentrations. Hexavalent chromium, meanwhile, is classified as a confirmed human carcinogen, and both metals are regulated as environmental priority substances owing to their persistence and bioaccumulation potential.

Because the response of a DLLME system depends on interacting variables, the team screened each parameter one factor at a time for each metal. For chromium, extractant volume produced a bell-shaped response: raising the ionic liquid from 100 to 400 microliters lifted recovery from about 35 percent to approximately 89 percent, but pushing further to 500 and 600 microliters dragged it back down to 73 and 61 percent. Too much solvent apparently disrupts the delicate phase ratio that lets droplets coalesce cleanly. Feed concentration told a similar story of finite capacity, with recovery falling from 86 percent at 10 parts per million to just 13 percent at 60 parts per million under fixed solvent conditions.

Centrifugation and salt addition each showed their own optima. Recovery peaked at 83 percent at 2000 revolutions per minute, dropping at both gentler and harsher spins, and climbed from 49 percent at 3 minutes of centrifugation to 93 percent at 15 minutes before declining again at 18 minutes. Sodium chloride, added to exploit salting-out effects, raised recovery from 47 percent at 0.1 grams to 86 percent at 0.4 grams, then reversed to 59 percent at 0.6 grams as ionic strength began to alter solvation, viscosity and interfacial transfer. Combining the best values, 400 microliters of ionic liquid at pH 6, 2000 rpm, 15 minutes and 0.4 grams of NaCl, delivered approximately 89 percent chromium recovery in a combined-condition experiment.

Nickel behaved differently. In a separate alkaline feed held at pH 10, aqueous-phase removal peaked at 96.1 percent at 80 parts per million initial nickel and then declined to 56.9 percent at 240 parts per million. Removal rose to a plateau of about 95 percent with 5 to 6 milliliters of ionic liquid, and centrifugation speed pushed removal from 55.9 percent at 500 rpm to 87.6 percent at 2500 rpm. The most dramatic effect came from salt: removal climbed monotonically from 70.7 percent at 0.4 grams of NaCl to 98.2 percent at 2.4 grams. The authors are careful to note, however, that at pH 10 nickel hydroxo-speciation and precipitation of nickel hydroxide can contribute to the measured depletion alongside genuine ionic-liquid partitioning, so the 98.2 percent figure represents overall aqueous-phase removal rather than an isolated extraction coefficient.

Two characterization techniques probed what actually happened to the solvent and the recovered metal. Fourier-transform infrared spectra recorded before and after extraction retained the diagnostic TFSI-anion bands, including asymmetric SO2 stretching near 1201 wavenumbers, CF3 stretching near 1059 and S-N-S bending near 619, along with the pyrrolidinium cation signatures, indicating no major structural decomposition was detectable. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy of the recovered material showed an irregular, aggregated particulate morphology enriched in chromium at approximately 12.9 weight percent, with chromium K-alpha and K-beta peaks at 5.41 and 5.95 kiloelectronvolts. Notably, iron appeared at 8.6 weight percent alongside sodium, chlorine and other matrix elements, revealing that the recovery was a co-enrichment of competing species rather than a phase-pure chromium separation.

Recyclability exposed the practical challenge ahead. Reused over three consecutive cycles without regeneration, the ionic liquid’s performance fell from 96.1 percent in the first cycle to 81.8 percent in the second and 65.6 percent in the third. FTIR alone cannot resolve whether the decline stems from solvent loss, water carry-over or matrix fouling, and the authors emphasize that phase mass-balance, washing and regeneration measurements are needed separately. The team also stresses that the single-factor design yields local maxima rather than a statistically derived global optimum, and that no comparative screening against imidazolium, ammonium or phosphonium ionic liquids was performed, so intrinsic selectivity among ionic-liquid families remains undetermined.

Even so, the study marks a meaningful step toward viewing metal-bearing wastewater as a resource rather than a burden. Compared with published benchmarks, the chromium recovery of roughly 89 percent sits below the 95.40 percent overall recovery of multistage amide solvent extraction and the 98.6 percent precipitation recovery of an integrated ion-exchange process, while the nickel removal of 98.2 percent numerically exceeds the 95.6 percent electrodeposition recovery achieved after fixed-bed ion exchange, though such comparisons cannot establish process equivalence given different feeds and endpoints. The authors point to phase-specific metal mass balances, quantitative selectivity in multicomponent systems, ionic-liquid regeneration and back-extraction, and reduction of the solvent-to-feed ratio for nickel treatment as the priorities for scaling the process. If those hurdles fall, the humble cloudy vial could become a compact tool for closing the loop on two of industry’s most problematic metals.

Subject of Research: Near-quantitative nickel recovery and selective chromium preconcentration from complex industrial wastewaters by pyrrolidinium ionic-liquid dispersive liquid–liquid microextraction

Article Title: Near-quantitative nickel recovery and selective chromium preconcentration from complex industrial wastewaters by pyrrolidinium ionic-liquid dispersive liquid–liquid microextraction

Article References: Mariappan, D., Janani, V. A., Ganesan, S. K., & Raj, A. S. (2026). Near-quantitative nickel recovery and selective chromium preconcentration from complex industrial wastewaters by pyrrolidinium ionic-liquid dispersive liquid–liquid microextraction. Frontiers in Chemical Engineering, 8, Article 1896238. https://doi.org/10.3389/fceng.2026.1896238

Image Credits: AI Generated

DOI: 10.3389/fceng.2026.1896238

Keywords: ionic liquids, chromium recovery, nickel removal, industrial wastewater, dispersive liquid-liquid microextraction, heavy metals, circular economy, electroplating, water treatment, Frontiers in Chemical Engineering, Near-quantitative, nickel

Space weathering, the cumulative surface modification caused by meteoritic and micrometeoritic impacts, plays a fundamental role in altering planetary surfaces everywhere in the Solar System. On the Moon, which lacks an atmosphere to burn up incoming debris, micrometeorites strike the regolith at hypersonic speeds, vaporizing both impactor and target and welding exotic material into the topmost soil grains. Yet two basic questions have remained unresolved: where do these impactors actually come from, and how does impact-induced evaporation control the accretion of micrometeorite material? The Chang’e-6 samples offered a fresh, unsampled lunar locale to attack both problems at once.

The team measured the isotopic composition of nickel in regolith and in lithic clasts, individual rock fragments embedded in the soil. Nickel is a particularly clever tracer because it carries two kinds of isotopic information. The ratio of its heavier to lighter stable isotopes, expressed as δ60Ni, records evaporation processes, since lighter isotopes escape preferentially when material vaporizes. Meanwhile, tiny nucleosynthetic anomalies, expressed in parts per million as μ60Ni and μ62Ni, act as a genetic barcode distinguishing materials formed in different regions of the early Solar System.

The results for the bulk regolith were striking. The Chang’e-6 regolith and some of the lithic clasts exhibit systematically enriched heavy nickel isotopic compositions, with δ60Ni values ranging from 1.07 to 1.25 per mil. These values are consistent with cumulative evaporation during repeated micrometeoritic bombardment under quasi-saturated conditions. In other words, each micrometeorite impact briefly creates a vapor cloud that is nearly saturated with nickel, limiting further fractionation per event, but the sheer number of impacts over billions of years drives the surviving soil progressively heavier in its nickel isotope signature. The regolith is, in effect, a palimpsest recording countless evaporation episodes.

Even more intriguing was a subset of basaltic clasts from the Chang’e-6 collection, which recorded unusually light nickel isotopic compositions, with δ60Ni values between −0.95 and −0.48 per mil. These values fall beyond the range previously reported for any lunar materials. The researchers interpret them as evidence of post-evaporation recondensation: after impact vapor plumes boiled away lighter nickel isotopes, some of that vapor recondensed locally, depositing material with the opposite, light isotopic signature into the basaltic fragments. It is a rare direct capture of both halves of the vaporization cycle, the escape and the return, within a single sample suite.

The genetic part of the story came from the nucleosynthetic anomalies. The Chang’e-6 regolith shows μ60Ni of 7 ± 3 and μ62Ni of −6 ± 9, values that point toward materials originating in the inner Solar System rather than the outer realms. This matters because planetary scientists have long debated the balance of impactor flux reaching the Moon. Some models emphasize cometary material delivered from the outer Solar System, particularly on the farside, which faces outward into interplanetary space. The nickel isotope anomalies suggest instead that the long-term average accreting materials to the lunar surface were dominantly sourced from the inner Solar System, meaning asteroidal and planetary debris from the region inside the main belt.

The technical achievement underlying these conclusions should not be understated. Nucleosynthetic isotope anomalies in nickel are measured in parts per million, requiring extraordinary instrumental precision and rigorous correction for interferences. Applying such measurements to a mere handful of grams of Chang’e-6 regolith, and to individual clasts within it, demanded careful sample preparation and repeated analysis. The consistency between the evaporation signal in the bulk soil and the recondensation signal in the clasts strengthens the interpretation that micrometeorite bombardment, not some exotic lunar process, generated the observed patterns.

These findings also refine our understanding of space weathering itself. Because the heavy nickel isotope enrichment in the regolith matches predictions for cumulative evaporation under quasi-saturated conditions, the measurements provide a quantitative constraint on how micrometeorite accretion proceeds on airless bodies. The light isotope signatures in the basaltic clasts, indicative of post-evaporation recondensation, show that impact vapor does not simply disperse into space; a portion recondenses and is preserved in the local geology. That has implications for how exotic elements and isotopic signatures are redistributed across planetary surfaces, from Mercury to asteroids.

For the wider community, the study demonstrates the scientific payoff of the Chang’e-6 mission beyond its headline achievement of farside sample return. The sampling site sits within the South Pole–Aitken basin context, a region geologically distinct from the nearside locales visited by Apollo and Luna missions, and the nickel isotope data confirm that the farside regolith records the same inner Solar System impactor dominance seen in other tracers. As more laboratories gain access to these samples, isotope systems like nickel will continue to decode the impact history of the Moon and, by extension, the delivery of material throughout the inner Solar System over the past several billion years.

Subject of Research: Geochemistry

Article Title: Nickel isotopes reveal micrometeorite accretion on the lunar farside dominated by inner Solar System materials

Article References: Chen, K., Zhang, Y., Wang, Z., Shen, J., Yang, B., Zhou, M., Sun, J., Liu, K., Chen, D., & Qin, L. (2026). Nickel isotopes reveal micrometeorite accretion on the lunar farside dominated by inner Solar System materials. Communications Earth & Environment. https://doi.org/10.1038/s43247-026-04038-1

Image Credits: AI Generated

DOI: 10.1038/s43247-026-04038-1

Keywords: Chang'e-6, lunar farside, nickel isotopes, micrometeorites, space weathering, inner Solar System, lunar regolith, evaporation, Nickel, isotopes, reveal, micrometeorite

The research team, led by Ayyandurai Mani and Mathiyazhagan Narayanan of the Saveetha Institute of Medical and Technical Sciences in Chennai, together with colleagues from the institute’s medical college laboratories, set out to track how nine toxicologically significant metals behave across seasons. The elements examined were arsenic, lead, cadmium, chromium, nickel, copper, zinc, iron and aluminium, all of which were selected because they persist in the environment, have the potential to bioaccumulate in living organisms, and serve as sensitive indicators of aquatic pollution. By sampling water and sediment across different seasons and multiple stations, the researchers were able to build a picture of how the lake’s contamination profile shifts with the monsoon cycle.

The seasonal signal was unmistakable. Concentrations of chromium, nickel, lead and iron were substantially higher in the post-monsoon season, a pattern the authors attribute to increased runoff across the catchment, greater inflow of contaminated water into the lake, and the physical stirring up of bottom sediments as inflows surge. This mechanism matters because sediments act as long-term repositories for heavy metals. When storms and flood pulses disturb the lake bed, metals that had been locked away can be released back into the water column, effectively giving the reservoir a second, delayed dose of pollution long after the original sources discharged their loads.

To quantify the ecological dimension of the problem, the team applied a suite of established sediment contamination indices, including the geoaccumulation index, the contamination factor, the degree of contamination and the potential ecological risk index. These metrics, which compare measured metal levels against background geological values and weight each element by its toxicity, told a consistent story: iron and cadmium emerged as the most significant contributors to ecological risk. Particularly striking were the pre-monsoon degree-of-contamination values, which indicated severe contamination at multiple sampling locations even before the rains arrived, suggesting that the lake carries a substantial legacy burden that the monsoon then redistributes and amplifies.

On the water quality side, the researchers calculated the heavy metal pollution index and the heavy metal evaluation index, two widely used composite measures that aggregate the concentrations of multiple metals relative to permissible limits. The results showed that many of the sampling stations fell into the moderate to highly contaminated categories during the post-monsoon period. For a reservoir that feeds directly into Chennai’s drinking water supply, this seasonal deterioration is more than an academic concern. It implies that the very months in which the lake collects the water it will store for the dry season are also the months in which its metal load peaks.

The most consequential part of the study, however, is its human health risk assessment. Using standard exposure models that estimate the intake of contaminants through water consumption, the team computed hazard quotients for non-carcinogenic effects and total carcinogenic risk values for each metal. The analysis revealed that exposure to chromium, nickel and arsenic produced non-carcinogenic hazard index values exceeding 1, the conventional threshold above which adverse health effects cannot be ruled out. More alarmingly, the calculated carcinogenic risks surpassed the widely used upper limit of one in ten thousand, meaning the estimated lifetime cancer risk from these exposures exceeds the level typically considered acceptable by regulatory agencies.

Children emerged as the most sensitive population group in the assessment. Because children consume more water relative to their body weight and their developing physiology makes them more vulnerable to toxic insults, the risk metrics for this group were consistently the highest. This finding echoes a growing body of international research showing that heavy metal contamination in drinking water sources disproportionately threatens the youngest members of exposed communities, with potential consequences ranging from developmental impairment to elevated lifetime cancer risk.

The study’s emphasis on seasonality carries a broader lesson for freshwater management in monsoon-influenced regions. Climate-induced hydrological variability is intensifying around the world, and the authors note that these shifting patterns, together with growing anthropogenic pressures, strongly affect the transport and bioavailability of heavy metals in freshwater ecosystems. In other words, the monsoon is not simply a dilution event that flushes pollutants away; in catchments loaded with industrial, agricultural and urban residues, it can act as a pump, mobilising contaminants from land and sediment into the water that millions of people depend on. Understanding this seasonal dynamic is therefore essential for maintaining ecosystem integrity and reducing health risks.

Chembarambakkam Lake is not an isolated case. Comparable studies from reservoirs and lakes across South Asia and beyond, from Dhaka to Lake Nasser in Egypt, have documented similar patterns of metal enrichment in water and sediment, with seasonal hydrology playing a decisive role in when and how contamination peaks. What sets the new work apart is its integrated approach, combining sediment contamination indices, water quality indices and formal human health risk calculations within a single seasonal framework. This holistic design allows managers to see not just where contamination is worst, but when it is worst and who is most at risk.

The practical implications are clear. Monitoring programmes that sample only once a year, or only during the dry season, risk missing the post-monsoon spikes that the study identifies as the most hazardous period. The authors’ results underscore the need for seasonal surveillance of drinking water reservoirs, targeted control of catchment runoff, and remediation of metal-laden sediments before they can be resuspended. As climate change alters the intensity and timing of monsoon rainfall across South Asia, the findings from Chembarambakkam Lake offer a timely warning: the health of a city’s water supply may hinge on what the rains stir up.

Subject of Research: Seasonal heavy metal contamination and associated ecological and human health risks in a tropical freshwater reservoir

Article Title: Seasonal variations in heavy metals concentration in water and sediment and associated ecological and human health risk assessment in Chembarambakkam lake, Tamil Nadu, India

Article References: Mani, A., Kolandhasamy, P., Loganathan, P., & Narayanan, M. (2026). Seasonal variations in heavy metals concentration in water and sediment and associated ecological and human health risk assessment in Chembarambakkam lake, Tamil Nadu, India. Environmental Monitoring and Assessment, 198(10), Article 1058. https://doi.org/10.1007/s10661-026-15899-6

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15899-6

Keywords: heavy metals, Chembarambakkam Lake, water quality, sediment contamination, monsoon, ecological risk, human health risk, carcinogenic risk, pollution indices, freshwater reservoir, Tamil Nadu, seasonal variation

The research team, led by Mujahid Farid of the University of Gujrat in Pakistan together with collaborators at universities in Saudi Arabia and Syria, set out to test whether a dual-route strategy could overcome the central weakness of phytoextraction: plants that accumulate large quantities of metals usually suffer severe growth penalties, while plants that grow well often accumulate too little metal to be useful for cleanup. Spinach, a fast-growing leafy vegetable with substantial biomass, sits squarely in the middle of this trade-off, which is precisely why the researchers chose it as their experimental system.

The experiments used real surgical industry wastewater rather than artificially prepared metal solutions, an important distinction because genuine effluents contain complex mixtures of contaminants that can interact in unpredictable ways. Plants were grown under two levels of contamination, 50 percent and 100 percent wastewater, and the untreated conditions proved harsh. At full-strength wastewater, plant height fell by 65.8 percent, biomass production collapsed, and the plants showed clear signs of oxidative damage as reactive oxygen species accumulated in their tissues.

That oxidative damage is the biochemical heart of heavy metal toxicity. Metals such as nickel, copper and lead interfere with electron transport chains and enzyme active sites, causing cells to overproduce reactive oxygen species. Left unchecked, these molecules attack membranes, degrade photosynthetic pigments and damage DNA. Plants normally defend themselves with an antioxidant arsenal, including the enzyme superoxide dismutase, which converts the superoxide radical into less harmful compounds. Under severe metal stress, however, this defense system is quickly overwhelmed.

The dual treatment changed that picture in striking fashion. When spinach plants received 10 millimolar malic acid in the rhizosphere together with foliar applications of Moringa oleifera leaf extract, the damage from full-strength wastewater was largely reversed. Plant height, which had dropped by nearly two-thirds, recovered by 42.8 percent. Root superoxide dismutase activity rose from 34.25 to 53.06 units per milligram of protein under the harshest conditions, indicating a substantially strengthened antioxidant front line. The treated plants also maintained their photosynthetic pigments, preserving the green machinery on which growth depends.

The two components of the treatment play complementary roles. Malic acid, a natural organic acid found in the rhizosphere of many plants, acts as a chelator. By binding metal ions in the soil solution, it increases their bioavailability, effectively unlocking metals that would otherwise remain locked to soil particles and unavailable for uptake. This is a well-known principle in assisted phytoextraction, but the study shows it operating under genuinely contaminated, multi-metal conditions rather than in simplified single-metal pot experiments.

Moringa leaf extract, by contrast, works from above. The extract of the moringa tree, often called the miracle tree, is rich in growth-promoting compounds including cytokinins, antioxidants, amino acids and vitamins. Sprayed onto foliage, it appears to bolster the plant’s internal defenses and support photosynthetic performance while the roots are busy absorbing an increased load of metals. The result is a rare combination: more metal taken up and a healthier plant at the same time.

The accumulation figures are the most eye-catching part of the study. Under 100 percent wastewater, treated plants accumulated 7046.67 micrograms of copper and 10510.69 micrograms of nickel in their roots, alongside significant increases in lead. These absolute accumulation values matter because phytoextraction is ultimately judged on the total mass of metal removed from a site, not merely on concentration measurements. A plant that concentrates metals modestly but produces abundant biomass can outperform a hyperaccumulator that barely grows, and the malic acid plus moringa strategy appears to push spinach toward that favorable balance.

The authors emphasize that this is the first report of simultaneous rhizosphere application of malic acid and foliar application of Moringa oleifera leaf extract tested against authentic multi-metal surgical wastewater in spinach. Previous work has generally examined these treatments separately, in isolation, or against synthetic contamination. Testing the combined approach under real-world effluent conditions gives the results practical weight, since industrial wastewater chemistry, with its mixture of metals and organic compounds, is far more challenging than any laboratory solution.

The implications extend in two directions. For environmental remediation, the study points toward a low-cost phytoextraction package: malic acid is inexpensive and biodegradable, and moringa leaf extract can be prepared from a widely grown tree, making the approach accessible in regions where synthetic chelators and sophisticated amendments are unaffordable. For agriculture, the work suggests that organic biostimulants can help crops tolerate contaminated irrigation water, a growing concern in areas where wastewater is routinely reused. The researchers caution, implicitly, that metal-enriched spinach is not for the dinner plate; the value here lies in cleanup and in understanding stress regulation. As wastewater reuse expands worldwide, strategies that let plants survive, grow and simultaneously pull metals out of the soil and water could become an important tool in the fight against insidious, long-lasting heavy metal pollution.

Subject of Research: Regulation of multi-metal stress responses and phytoextraction in spinach using malic acid and Moringa leaf extract

Article Title: Regulation of multi-metal stress responses in spinach by malic acid and Moringa leaf extract: implications for plant performance and phytoextraction

Article References: Farid, M., Farooq, F., Alghanem, S. M. S., Alhaithloul, H. A. A. S., Alotaibi, M. S., Munir, M., Hamoud, Y. A., & Shaghaleh, H. (2026). Regulation of multi-metal stress responses in spinach by malic acid and Moringa leaf extract: implications for plant performance and phytoextraction. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10087-7

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10087-7

Keywords: spinach, phytoextraction, heavy metals, malic acid, Moringa oleifera leaf extract, oxidative stress, antioxidant defense, industrial wastewater, nickel, copper, lead, biostimulants