The research team, led by Mohamed El Mderssa of Sultan Moulay Slimane University together with colleagues from the National School of Forest Engineering and Moulay Ismail University, compared Ifrane National Park in the Middle Atlas with Talassemtane National Park in the Rif Mountains. These two parks form a natural experiment: Ifrane’s forests grow on a patchwork of basaltic volcanic rock and dolomitic carbonate, while Talassemtane sits almost entirely on limestone. Because both parks harbor similar numbers of forest ecosystem types, any divergence in their soil carbon profiles points toward geology and ecological differentiation rather than simple species counts.

The researchers assembled a harmonized dataset of 67 field observations collected during the summer of 2022, drawing on 48 sampling points in Ifrane and 19 in Talassemtane. All measurements targeted the upper 30 centimeters of mineral soil, a depth consistent with Intergovernmental Panel on Climate Change reporting guidance and one that captures the biologically active horizon where litter inputs, root exudates and fine-root turnover concentrate. Carbon concentrations were determined by Walkley–Black wet oxidation, and stocks were calculated using bulk density measured with the core method, ensuring that both datasets could be compared on identical footing.

The headline result is striking. Mean soil organic carbon stock reached 173.99 tonnes of carbon per hectare in Ifrane, roughly two and a half times the 69.44 tonnes per hectare recorded in Talassemtane. Welch’s t-test confirmed the difference was highly significant. Just as telling was the spread: individual values in Ifrane ranged from 36.10 to 437.92 tonnes per hectare, with a coefficient of variation of nearly 54 percent, while Talassemtane’s values spanned only 44.64 to 107.74 tonnes per hectare with a variation coefficient of just over 22 percent. In ecological terms, the Middle Atlas landscape behaves like a mosaic of carbon banks of very different sizes, whereas the Rif landscape stores carbon more uniformly and, on average, far less of it.

Forest ecosystem type significantly shaped these patterns in both parks. In Ifrane, zeen oak forests topped the table with a mean of 251.54 tonnes of carbon per hectare, followed by holm oak at 219.62 and cedar at 169.47. Mixed cedar–holm oak and holm oak–zeen oak stands, along with maritime pine plantations, stored considerably less. In Talassemtane, Mediterranean matorral showed the highest mean at 101.41 tonnes per hectare, ahead of cork oak and the endemic Moroccan fir, though the authors caution that matorral and fir were each represented by only two observations, making those means indicative rather than statistically robust. The spread between ecosystem means, a simple measure of carbon differentiation, was 142.52 tonnes per hectare in Ifrane against just 41.72 in Talassemtane.

Geology emerged as the study’s most provocative variable. Within Ifrane, soils derived from basalt averaged 200.84 tonnes of carbon per hectare, about 37 percent more than the 147.14 tonnes on dolomite. A general linear model identified geological substrate as the strongest determinant of soil carbon variability once ecosystem type was adjusted for, and a linear mixed-effects model estimated that limestone soils in Talassemtane hold roughly 139 tonnes per hectare less carbon than basaltic ones. The mechanistic explanation lies in soil chemistry: basalt weathers into clay-rich soils packed with reactive iron and aluminum oxides that bind organic matter into stable organo-mineral associations, shielding it from microbial decomposition, whereas calcareous and dolomitic substrates tend to produce shallower, sandier soils with weaker mineral protection.

Yet the authors are refreshingly careful not to oversell this geology story. Because four of Ifrane’s six ecosystem types occur exclusively on a single substrate, ecosystem identity and rock type are heavily entangled in the data. The cleanest available test comes from cedar and holm oak forests, the only ecosystems sampled on both basalt and dolomite. Within each of these, the basalt–dolomite difference was not statistically significant, with P values of 0.680 and 0.143 respectively. The holm oak comparison did show a large numerical gap, 264.7 against 174.5 tonnes per hectare, but with only six replicates per group the test was likely underpowered. The team explicitly frames the substrate effect as suggestive rather than confirmed, an unusually candid position that highlights how difficult it is to separate vegetation from parent material in real landscapes, echoing the classic pedological framework of soil formation in which climate, organisms, relief, parent material and time act inseparably.

Perhaps the study’s most conceptually important contribution is its redefinition of biodiversity. Instead of counting tree species within plots, the researchers treated forest ecosystem diversity as the diversity and spatial heterogeneity of ecosystem types across the landscape, integrating differences in vegetation structure, litter chemistry, rooting depth and microclimate. Both parks showed nearly identical richness and evenness indices for their sampled ecosystems, yet their carbon behavior diverged dramatically. This suggests that for carbon accounting purposes, biodiversity should be read as landscape heterogeneity rather than species richness, since what drives soil carbon is the patchwork of contrasting ecological engines, not the number of names on a plant list.

The practical implications ripple outward from Moroccan park boundaries. Carbon inventories that prioritize aboveground biomass while treating soil as a uniform black box risk mispricing these landscapes: a holm oak forest on basalt in Ifrane may hold more than four times the soil carbon of a holm oak forest on limestone in Talassemtane, even though the vegetation looks broadly similar. The authors argue that pedological information, including substrate type and mineralogy, should be built into national carbon accounting and that basalt-derived oak forests deserve priority in restoration and protection schemes as disproportionately valuable carbon reservoirs. At the same time, they caution against dismissing limestone ecosystems as low value, since they deliver unique biodiversity and hydrological services that carbon metrics alone cannot capture.

The team also lays out its own limitations with unusual transparency: uneven sampling between parks, the near-perfect confounding of substrate and ecosystem within Ifrane, the absence of climate, topographic and mineralogical covariates, and a 30-centimeter sampling depth that may underestimate total profile carbon in deeper soils. Future work, they suggest, should employ balanced designs in which the same ecosystem types are sampled across multiple substrates, and should extend to remote sensing and digital soil mapping for spatial prediction. For now, the message stands: if the world wants Mediterranean mountain forests to keep banking carbon, it must learn to read the rocks as carefully as it reads the trees.

Subject of Research: Soil organic carbon storage in Mediterranean mountain forests as shaped by forest ecosystem diversity and geological substrate in Morocco

Article Title: Soil organic carbon storage across Mediterranean mountain forests: a comparative assessment of forest ecosystem diversity and geological substrate in Ifrane and Talassemtane National Parks, Morocco

Article References: El Mderssa, M., ELMALKI, M., Malki, F., Abdelhakim, T., Abbas, Y., & Ibijbijen, J. (2026). Soil organic carbon storage across Mediterranean mountain forests: a comparative assessment of forest ecosystem diversity and geological substrate in Ifrane and Talassemtane National Parks, Morocco. Frontiers in Soil Science, 6, Article 1959268. https://doi.org/10.3389/fsoil.2026.1959268

Image Credits: AI Generated

DOI: 10.3389/fsoil.2026.1959268

Keywords: soil organic carbon, Mediterranean forests, Morocco, Ifrane National Park, Talassemtane National Park, geological substrate, basalt, limestone, carbon sequestration, forest ecosystems, Middle Atlas, Rif Mountains

Enhanced rock weathering is not a new idea in principle; it is an acceleration of one of Earth’s oldest climate-regulating processes. Over geological time, rain and soil moisture react with silicate rocks in a chain of chemical reactions that pulls carbon dioxide out of the air and converts it into dissolved inorganic carbon, ultimately carried by rivers to the oceans and stored there. The natural process is far too slow to matter on human timescales, but grinding rock into fine powder dramatically increases the reactive surface area exposed to water and air. When that powder is scattered on agricultural fields, soil moisture, plant roots and soil acids attack the mineral grains, releasing cations such as calcium and magnesium that combine with dissolved CO2 to form bicarbonates. In effect, the field becomes a vast, passive chemical scrubber, and the farmer’s existing machinery and irrigation infrastructure do much of the work.

What has been missing, the authors argue, is a credible national-scale quantification for China, the country whose carbon-neutrality pledge by 2060 arguably depends more than any other on finding affordable negative-emissions options at enormous scale. Most carbon dioxide removal technologies face well-known constraints: direct air capture remains expensive and energy-intensive, afforestation competes for land and stores carbon in vulnerable biomass, and bioenergy with carbon capture requires both large biomass supplies and reliable geological storage. Enhanced rock weathering sidesteps some of these bottlenecks because it piggybacks on agriculture, uses abundant silicate rocks such as basalt, and in many cases delivers co-benefits to soils, including the release of plant nutrients and the potential to ameliorate soil acidity.

The Tsinghua-Cambridge team addressed the gap with a spatially explicit analysis across China’s croplands, meaning that rather than averaging the country into a single number, they resolved the relevant variables location by location. That matters because the effectiveness of enhanced rock weathering is exquisitely sensitive to geography. Weathering rates depend on climate, with warm, wet conditions accelerating the dissolution of silicate minerals, and on soil chemistry, which controls how quickly acids in the soil can attack the rock. They also depend on logistics: basalt must be crushed, transported and spread, and the energy and emissions embedded in that supply chain eat directly into the net climate benefit. A field in humid South China served by a nearby quarry is a very different proposition from a dry northern plain hundreds of kilometres from suitable rock.

By accounting for these factors across the national cropland base, the study arrives at its headline range of 0.44 to 0.79 billion tonnes of CO2 removed by 2100 from a single year of application. To put that in perspective, the upper end of the range is comparable to a substantial fraction of China’s annual emissions from a single year of rock, spread once and continuing to weather for decades as the grains dissolve. The cost estimate of 127 to 226 dollars per tonne of CO2 removed is a net, life-cycle-adjusted figure, meaning the authors subtracted the emissions and costs of grinding, transporting and spreading the rock before tallying the balance. That places enhanced rock weathering in a competitive band relative to many other carbon removal pathways, though still well above the levels needed for mass deployment without policy support.

One of the study’s most consequential technical findings concerns particle size. The researchers found that particles finer than those typically used commercially provide the most favorable balance between removal potential and cost. The logic follows directly from reaction kinetics: the rate at which a mineral grain dissolves scales with its exposed surface area, and grinding rock finer multiplies that area. Finer milling costs more energy up front, but the additional carbon removed over the decades that follow more than compensates in the study’s accounting. This is a practical insight for anyone hoping to design a real deployment program, because it suggests the industry should invest in finer grinding than current agricultural lime or rock-dust practice would suggest, and it gives quarry operators and equipment manufacturers a concrete engineering target.

The analysis also looked beyond a one-off application. Under multi-year application, repeated spreading across successive seasons, the authors estimate that enhanced rock weathering could contribute 5 to 30 percent of China’s negative emissions needs by 2060. That range is wide, reflecting genuine uncertainties in weathering kinetics, application rates and future costs, but even the low end represents a meaningful slice of the enormous carbon-removal burden implied by carbon neutrality. The study identifies priority areas in Northeast, Central-South and East China, regions where the combination of climate, soils, cropland extent and proximity to basalt resources makes the approach most favorable. Such spatial prioritization is exactly what policymakers need to move from a promising concept to a targeted pilot program.

The authors are careful to frame their work as an initial spatially resolved assessment rather than a final verdict, and they are explicit about what must happen next. They call for field trials and coupled soil-river geochemical modeling to constrain three critical unknowns: the actual rate of weathering under real field conditions, the fraction of the dissolved carbon that is retained as it travels downstream rather than being re-released, and the magnitude of losses along the pathway from field to ocean. These are not minor caveats. The carbon captured on a farm exists as dissolved bicarbonate in soil water, and its ultimate fate depends on hydrology and river chemistry at scales far beyond any single plot. Without that downstream accounting, removal estimates could be systematically optimistic or pessimistic.

For China’s climate planners, the study supports considering enhanced rock weathering in the national carbon-management portfolio, a conclusion with global resonance. The same modeling framework could be applied to other major agricultural economies, from India and Brazil to the United States, where basaltic rocks and extensive croplands coexist. The work was supported by the National Key R&D Program of China, and its open-access publication means the underlying assessment is available to researchers and policymakers worldwide. If field trials bear out the model’s assumptions, the vision that emerges is quietly revolutionary: a carbon removal technology that requires no exotic chemistry, no vast new industrial infrastructure, and no land taken out of food production, only rock, crushers, spreaders and the patient chemistry of water meeting stone. In a world desperately searching for affordable ways to draw carbon down, the answer may lie in the oldest scrubber of all, the weathering of rock, accelerated by human ingenuity and deployed across the fields that already feed a fifth of humanity.

Subject of Research: National-scale assessment of enhanced rock weathering as a carbon dioxide removal strategy on China's croplands

Article Title: Assessing the potential and cost of enhanced rock weathering in China

Article References: Wang, Z., Teng, F., & Reiner, D. M. (2026). Assessing the potential and cost of enhanced rock weathering in China. Communications Earth & Environment. https://doi.org/10.1038/s43247-026-04136-0

Image Credits: AI Generated

DOI: 10.1038/s43247-026-04136-0

Keywords: enhanced rock weathering, carbon dioxide removal, China, basalt, croplands, carbon neutrality, negative emissions, soil chemistry, climate mitigation, carbon costs, geochemical modeling, Tsinghua University

The research team tested their approach on basaltic cores recovered during International Ocean Discovery Program Expedition 396, which drilled the Mid-Norwegian Margin in 2021 to investigate the massive volcanism that accompanied the opening of the Northeast Atlantic and the emplacement of the North Atlantic Igneous Province. Across five sites, the expedition recovered 587 meters of basaltic rock from eight holes, with an average recovery of 61 percent. Morris and colleagues focused on three of those sites: Hole U1566A on the western flank of the Kolga High, with at least 14 discrete lava flows; Hole U1571A on the Skoll High, which captured the upper termination of seaward-dipping reflectors; and Hole U1574A on the Eldhø Outer High, which penetrated 94 meters of pillow basalts and hyaloclastites. These rocks were anything but scanner-friendly, riddled with vesicles, chilled margins, brecciated flow tops, and secondary carbonate and zeolite veins.

The physics of X-ray fluorescence explains why flat surfaces matter so much. The instrument bombards a sample with high-energy X-rays that knock inner-shell electrons out of atoms; when outer-shell electrons drop in to fill the vacancies, they emit X-rays characteristic of each element. A detector counts these fluoresced photons, producing intensity data that correlate with concentration. Anything between the beam and the sample, including air and dust, gets measured too. Sediment cores can be smoothed and covered with a thin Ultralene film for near-perfect contact, but basalt offers no such luxury. The traditional workaround has been portable handheld XRF instruments, which let the analyst pick a homogeneous-looking spot. That flexibility comes at a price: every measurement location is a human choice, introducing selection bias, and only a handful of analyses, often one to three per 1.5-meter core section, end up representing many meters of rock.

To adapt core scanning to hard rock, the team modified the standard procedure. Instead of measuring at regular centimeter intervals, they identified every rock fragment large enough to fill the scanner’s 10-by-12-millimeter irradiation area, then raised and leveled each piece within the core liner using moldable clay protected by Kimtech wipes to prevent contamination. Each fragment’s position was logged at millimeter scale. The scanner took measurements at three voltages, 10, 30, and 50 kilovolts, each optimized for a different suite of elements; because all elements of interest fell in the 30-kilovolt range, only that spectrum was used. The critical quality-control trick was argon: since argon is the only reliably measurable component of air, positive argon counts flag measurements with poor detector contact. Measurements with argon counts above 1,000 were discarded, as were outliers beyond three standard deviations of total spectrum throughput or argon counts.

The filtering produced 293 usable analyses from 47.7 meters of core at U1566A, 189 analyses from 29.4 meters at U1571A, and 237 analyses from 40.0 meters at U1574A, for a total of 719 filtered measurements from 797 raw scans. To convert raw intensities into concentrations, the team calibrated the core-scan data against calibrated discrete pXRF analyses collected on the same archive core halves during the expedition, using an Olympus Delta handheld spectrometer whose own calibration curves were built from ten standard reference materials. Matching analysis locations to within one centimeter of depth, they ran robust regressions on 35 pXRF-core-scan data pairs, a technique preferred over simple linear regression because it does not assume Gaussian error distributions. Eleven elements, including Ca, K, Ti, Fe, Mn, Ni, Cu, Zn, Sr, Y, and Zr, were successfully calibrated to apparent concentrations.

The validation came from comparison with independent datasets: 241 pXRF analyses and 60 conventional bulk-rock analyses by XRF and inductively coupled plasma mass spectrometry performed on the working halves of the same cores. The team compared immobile element ratios such as Ti/Zr, Y/Zr, Ni/Mn, and Zn/Mn, which track mantle source composition and fractional crystallization, alongside mobile-element ratios like K/Zr and Sr/Y, which fingerprint alteration. Analysis of variance and Tukey honestly significant difference tests quantified whether the three holes were genuinely chemically distinct. The verdict was encouraging: the core-scan data reproduced the regional trends seen in the pXRF and bulk-rock data, with Hole U1571A basalts standing out with lower Y/Zr and K/Zr and higher Sr/Y, consistent with the three sites recording different stages of rifting, from subaerial initiation to peak magmatism to late-stage shallow marine eruption.

But the study also delivered cautionary lessons. Uncalibrated intensity ratios sometimes told misleading stories. The Ni/Mn and Zn/Mn ratios in raw data suggested a progressive increase from U1566A to U1571A to U1574A, yet after calibration the values clustered tightly, matching the pXRF and bulk-rock results. The reason is fundamental: the relationship between X-ray intensity and concentration is non-linear, so raw intensity ratios can manufacture apparent trends that do not exist in concentration space. A second lesson involved potassium: the calibrated K/Zr data disagreed with the other datasets, but the culprit was traceable to a calibration built on only three pXRF pairs, because potassium in the pXRF analyses frequently fell below detection limits. The message is clear: calibration is essential, and a calibration is only as good as the number and quality of the paired analyses behind it.

Where the technique truly shines is in revealing fine-scale variability that discrete sampling misses entirely. The core-scan dataset, collected in just four days, is 280 percent larger than the pXRF dataset. Chemical stratigraphy plots exposed anomalies invisible to conventional methods: a brecciated basalt flagged by positive titanium, strontium, and zircon excursions; an altered pyroclastic layer marked by a 103 percent nickel spike; and, most strikingly, a visually homogeneous section of aphyric basalt in core U1566A-27R2 that showed five large strontium anomalies with increases of 108 to 741 percent, likely from vesicles filled with carbonate-bearing material. Meanwhile, a neighboring section packed with seven different lithofacies showed remarkably little chemical variation. Composition, in other words, does not always follow appearance, and only dense chemical sampling can tell the difference.

The implications extend well beyond one expedition. The Scientific Ocean Drilling 2050 Science Framework has emphasized the need for better core characterization as the community reorganizes around the post-IODP era, and kilometers of legacy core material collected over 50 years were never analyzed with consistent methods. Rapid, non-destructive, high-resolution chemistry could help scientists target the most valuable samples for destructive analyses and even train machine-learning classifiers, which require large datasets, to automate lithological identification in basaltic cores. The workflow does carry inherent biases: small, fragile, or highly vesicular fragments that cannot be leveled are excluded, and fewer elements can be calibrated than a scanner measures. Still, the authors argue that with careful filtering, honest calibration, and appropriate statistical testing, X-ray fluorescence core scanning can finally do for hard-rock cores what it has long done for mud: turn silent cylinders of stone into rich, continuous chemical narratives.

Subject of Research: Adapting X-ray fluorescence core-scanning techniques to basaltic hard-rock cores for high-resolution geochemical characterization and sample selection

Article Title: Recommendations for using core X-ray fluorescence data on basaltic rock as a tool to assess compositional variability

Article References: Morris, A. M., Lambart, S., Alvarez Zarikian, C. A., Millett, J. M., Jones, M. T., Planke, S., Betlem, P., Chatterjee, S., Christopoulou, M., Ferré, E. C., Filina, I. Y., Frieling, J., Scherer, R. P., Varela, N., Xu, W., & Yager, S. L. (2026). Recommendations for using core X-ray fluorescence data on basaltic rock as a tool to assess compositional variability. Scientific Drilling, 35(1), 21-37. https://doi.org/10.5194/sd-35-21-2026

Image Credits: AI Generated

DOI: 10.5194/sd-35-21-2026

Keywords: X-ray fluorescence, core scanning, basalt, IODP Expedition 396, geochemistry, scientific drilling, North Atlantic Igneous Province, pXRF calibration, chemostratigraphy, sample selection, legacy cores, Mid-Norwegian Margin

The experiment took place at the Sleepers River Research Watershed in Danville, Vermont, a long-studied 59-hectare agricultural catchment known as W-2, where hayfields and pasture cover roughly three-quarters of the land. After a full year of baseline monitoring, the team spread basalt powder at a rate of 20 tonnes per hectare over 8.9 hectares of the downstream portion of the catchment in June 2023, amounting to about 15 percent of the total watershed area. The basalt, sourced from the Holyoke Basalt formation of the Newark Supergroup, was rich in the calcium-bearing minerals that make silicate weathering an effective carbon sink. When silicate minerals dissolve, they consume atmospheric carbon dioxide and convert it into bicarbonate alkalinity, a form of carbon that can remain safely stored in the ocean for tens of thousands of years once it arrives there.

What happened next surprised even the researchers. Streamwater alkalinity and calcium concentrations in the treated catchment rose above counterfactual estimates within a single month of application. In the first three months, alkalinity exceeded the no-basalt baseline by an average of 267 microequivalents per liter, peaking at 557 microequivalents per liter above the counterfactual in September, while calcium climbed by as much as 696 microequivalents per liter. Because a nearby forested reference watershed, W-9, showed no such changes, the team could attribute the shifts directly to the basalt. The concentration-discharge relationships in the stream also changed character, weakening the natural dilution pattern that had been established during the baseline year, a sign that a new, persistent source of solutes had entered the system.

The evidence went well beyond alkalinity. Concentrations of silica and lithium, both far more abundant in basalt than in the carbonate rocks that could otherwise explain the chemistry, rose in parallel with the base cations. The isotopic composition of lithium shifted as well: the ratio of lithium-7 to lithium-6 in streamwater declined from an average of 19.0 per mil before treatment to 17.5 per mil within three months, moving toward the isotopically light signature of the applied basalt itself, which measured just 2.34 per mil. Rubidium, which substitutes for potassium in the feldspars and micas of the basalt, also increased at equivalent stream discharges. Together, these geochemical tracers painted a coherent picture of freshly applied silicate rock dissolving and its dissolution products racing to the stream.

One curious detail was the preferential export of calcium over sodium and magnesium, with the calcium increase more than twenty times larger than the corresponding rises in the other cations. The researchers attribute this to a combination of mechanisms. The soils at the site are dominated by calcium on their exchange complex, with roughly 85 percent calcium saturation, meaning other basalt-derived cations can displace calcium from exchange sites and flush it downstream early. Non-stoichiometric mineral dissolution plays a role too, since clinopyroxene and calcium-rich plagioclase, both abundant in the feedstock, release calcium preferentially. A small carbonate content in the basalt, about 0.14 percent by weight, likely contributed a minor share as well.

Perhaps the most consequential finding is that the treatment effect was strongly seasonal. Using a generalized additive model coupled with a difference-in-differences framework that leveraged data from the reference watershed, the team found that enhanced weathering accounted for 14 to 18 percent of streamwater alkalinity, calcium, magnesium, sodium and silica during the summer of 2023, but the effect weakened in autumn, became statistically indistinguishable from zero in winter, and rebounded in spring with snowmelt. The same pattern repeated, slightly attenuated, in the second year. Export of basalt-derived alkalinity, expressed as removed carbon dioxide, plunged from a summertime high of about 102 tonnes of CO2 per square kilometer per year to less than 3 tonnes in winter.

The seasonal rhythm reflects two intertwined controls. Temperature governs the kinetics of basalt dissolution, and the researchers quantified this with an Arrhenius analysis of discharge-normalized alkalinity export, deriving an apparent activation energy of 58.5 kilojoules per mole, squarely within the expected range for basalt weathering and actually exceeding laboratory values for calcium-bearing plagioclase. That excess likely reflects additional temperature-dependent processes in the field, such as seasonal swings in soil carbon dioxide from microbial and root respiration, which acidify soil water and accelerate dissolution. Hydrology supplies the second control: an endmember mixing analysis showed that basalt-derived solutes traveled to the stream mainly through quick-flow pathways fed by shallow, near-stream soils, whose solute concentrations jumped by up to 1,200 microequivalents per liter in summer and autumn, while slow-flow water originating upslope showed no detectable weathering signal at all.

Over the full 22-month monitoring window, the exported alkalinity amounted to 63.8 tonnes of CO2 per square kilometer, equivalent to 34.7 tonnes per square kilometer per year, which is among the highest rates reported for any field-based enhanced weathering study and roughly matches the median carbon consumption rate of natural basaltic rivers worldwide. Yet that figure represents only 9.5 to 11 percent of the theoretical maximum carbon removal potential of the applied basalt. The gap is not necessarily a failure. Water isotope analysis showed that only about 23 percent of streamflow was younger than roughly two months, meaning most water lingers in catchment storage, and weathering products traveling along slower, deeper paths may simply not have emerged yet. The mean residence time of water in the catchment is about 1.3 years, so a substantial fraction of the carbon removal signal may still be in transit.

The implications for the booming carbon removal industry are significant. Monitoring schemes that rely on streamwater chemistry will need to account for seasonal variability, or they risk badly misestimating removal, particularly if measurements cluster in winter when the signal vanishes. Deployments that target moist, near-stream corridors will be most responsive to stream-based verification, while upslope applications may require extended monitoring windows stretching well beyond two years to capture the delayed tail of the weathering signal. There are also limits to watch: repeated applications could push streamwater toward calcite saturation in summertime, triggering carbonate precipitation that would claw back alkalinity and reduce net removal.

What the Vermont trial ultimately demonstrates is that a watershed can serve as a natural integrator of enhanced weathering signals, capturing the combined effects of dissolution kinetics, hydrologic transport and climate variability in a single, measurable output at the stream gauge. Despite the cold northern climate that should slow weathering, the high calcium saturation of the soils and favorable hydrologic connections allowed signals to emerge quickly and repeatably across two years. As enhanced weathering scales from experimental plots toward the gigatonne ambitions projected for global croplands, studies like this one provide the template for knowing what to measure, when to measure it, and how to read the seasonal heartbeat of a landscape quietly eating carbon dioxide.

Subject of Research: Watershed-scale monitoring of carbon dioxide removal via enhanced weathering with crushed basalt

Article Title: Multiple lines of evidence reveal rapid, seasonal watershed responses to enhanced weathering

Article References: Sun, F., Rioux, R. A., Suhrhoff, T. J., Tatge, W., Kalderon-Asael, B., Zacharias, Q., Miller-Brown, W. A., MacDonald, A. A., Garcia, E., Shanley, J. B., Raymond, P. A., Planavsky, N. J., & Saiers, J. E. (2026). Multiple lines of evidence reveal rapid, seasonal watershed responses to enhanced weathering. Nature Water. https://doi.org/10.1038/s44221-026-00716-8

Image Credits: AI Generated

DOI: 10.1038/s44221-026-00716-8

Keywords: enhanced weathering, carbon dioxide removal, basalt, alkalinity, streamwater chemistry, hydrology, seasonality, silicate dissolution, carbon sequestration, watershed monitoring, lithium isotopes, climate mitigation

The research team, led by Emad A. Alsherif of Beni-Suef University together with colleagues at Princess Nourah bint Abdulrahman University and Taif University, extracted solvent-soluble metabolites from shoots collected at the four sites, designated B1 and B2 on basalt and G1 and G2 on granite. The chemical composition of each extract was resolved by gas chromatography coupled with mass spectrometry, the standard technique for separating and identifying volatile and semi-volatile organic compounds. To quantify the diversity of the resulting chemical profiles, the researchers borrowed tools from community ecology, calculating compound richness as well as the Shannon, Simpson, and Pielou diversity indices, and used Jaccard similarity coefficients to measure how much the chemical repertoires of different populations overlapped. Antioxidant capacity was assessed with the DPPH assay, expressed as Trolox equivalents, allowing a direct functional comparison between the extracts.

The results were unambiguous. Shrubs rooted in basalt-derived soils produced markedly richer chemical portfolios, with solvent extracts containing between 49 and 50 distinct compounds. These basalt populations were dominated by sesquiterpenes and their oxygenated derivatives, a class of fifteen-carbon terpenoid molecules well known for their roles in plant defense and signaling. In the B1 sample, the oxygenated sesquiterpene beta-eudesmol accounted for 17.95 percent of the profile and viridiflorol for 8.16 percent, illustrating how strongly these defensive compounds can dominate a basalt-grown plant’s chemistry. Granite samples, by contrast, yielded far leaner extracts of only 11 to 26 compounds and displayed a clearly different chemical fingerprint, with a different suite of major constituents.

One of the most striking features of the data was the sheer magnitude of intraspecific chemical variability. For many of the major compounds, the coefficient of variation exceeded 100 percent, meaning the standard deviation of their relative abundance was larger than the mean itself. In plain terms, the same species growing on different substrates did not merely shift its chemistry at the margins; it rearranged which molecules were abundant and which were trace components. The Jaccard similarity analysis made this divergence quantitative: the two basalt populations shared a similarity of 0.612, indicating substantial chemical overlap within the same rock type, while the average similarity between basalt and granite populations was only around 0.30. In ecological terms, the substrate, not geography alone, appears to be the primary axis along which the species’ chemistry partitions.

Chemical diversity indices told the same story from another angle. The Shannon index, which combines richness with evenness, the Simpson index of diversity, and Pielou’s measure of evenness were all consistently higher in the basalt extracts than in the granite ones. Antioxidant activity, measured by the DPPH free-radical scavenging assay, followed the same pattern, with the B1 basalt population showing the strongest capacity of all four sites. This alignment between chemical diversity and antioxidant function suggests that the richer sesquiterpene-laden profiles of basalt plants are not just more varied but also more biochemically potent, at least with respect to radical-scavenging activity relevant to medicinal and perfumery applications.

Why should the underlying rock matter so much? The answer lies in the profound differences between the two parent materials. Basalt, a fine-grained volcanic rock, weathers relatively rapidly and releases a steady supply of mineral nutrients, including magnesium, iron, calcium, and a suite of micronutrients such as copper, zinc, manganese, and molybdenum that serve as cofactors for plant enzymes. Granite, composed largely of quartz, feldspar, and mica, weathers slowly and yields soils that are comparatively oligotrophic, or nutrient-poor. Recent work on parent material influences on soil properties has shown that the mineralogy of the underlying rock can shape not only soil fertility but also microbial community assembly and enzyme functions, cascading upward into the plants that depend on those soils. The new study extends this edaphic control into the realm of specialized metabolism.

The authors interpret their findings through the lens of the Resource Availability Hypothesis, a classic framework in plant ecology first articulated by Coley, Bryant, and Chapin in 1985 and later refined by meta-analysis. The hypothesis predicts that plants growing in nutrient-rich environments can afford to invest in constitutive chemical defenses, producing a broad arsenal of protective metabolites because the carbon and nutrient costs are easily recouped by fast growth. Plants on nutrient-poor substrates, in contrast, are expected to favor slower growth and more carbon-intensive, specialized defenses, since replacing lost tissue is prohibitively expensive when resources are scarce. The basalt populations of Commiphora gileadensis, with their high compound richness and abundant oxygenated sesquiterpenes, fit the first prediction, while the granite populations, with fewer but more specialized carbon-based metabolites, fit the second.

The study also speaks to a broader and increasingly active research frontier: the geodiversity-biodiversity nexus. Ecologists have long recognized that edaphic factors, the physical and chemical properties of soils, exert strong control over plant species diversity at landscape scales, but the idea that geology can structure variation within a single species, down to the level of its secondary metabolite profile, is a more granular and provocative claim. Comparable patterns have been documented in other aromatic and medicinal plants, such as soil and vegetation effects on sesquiterpene lactone profiles in Arnica montana flower heads and environmental influences on essential oil chemotypes in Balkan juniper populations. Together, these studies suggest that substrate-driven chemotypic plasticity may be a widespread and underappreciated dimension of plant adaptation in stressful environments, one that operates alongside genetic differentiation and climatic filtering.

For Commiphora gileadensis specifically, the stakes are considerable. The species produces the fragrant resins historically traded as balsam of Mecca, prized for millennia in traditional medicine and perfumery across the Arabian Peninsula and the Horn of Africa, its native range. Previous population genetic work using SSR markers has revealed structured, inbred populations in the mountainous sites of Makkah Province, and the new chemical evidence adds a functional layer to that picture: even where genetic lineages persist, their medicinal chemistry may be shaped as much by geology as by heredity. Conservation planners seeking to preserve the species’ full chemical heritage would therefore need to protect populations across both basalt and granite substrates, since each rock type safeguards a distinct chemotype that the other does not replicate.

The findings also carry practical weight for cultivation and bioprospecting. If nutrient-richer volcanic substrates reliably promote greater metabolic diversity and stronger antioxidant activity, growers establishing plantations of this medicinally important species could, in principle, select substrate types to steer resin quality, while researchers screening for bioactive compounds would be advised to sample across edaphic gradients rather than from a single soil type. At a time when enhanced weathering of basalt rock powder is being explored both as a soil fertility amendment and as a carbon sequestration strategy, the observation that basalt-derived substrates can reshape the defensive chemistry of a desert shrub adds an ecological dimension to an already expanding portfolio of basalt’s agricultural relevance. What emerges from this study is a vivid demonstration that in arid ecosystems, the ground itself is not passive scenery but an active architect of plant chemistry, quietly scripting which molecules a legendary balsam shrub will produce, and in what abundance, from one mountainside to the next.

Subject of Research: Substrate-driven chemotypic variation in the medicinal shrub Commiphora gileadensis

Article Title: Habitat-specific chemotypes in commiphora gileadensis: granite versus basalt parent materials

Article References: Alsherif, E. A., Korany, S. M., Hassan, W. A., & Fadl, M. A. (2026). Habitat-specific chemotypes in commiphora gileadensis: granite versus basalt parent materials. Plant Biosystems, 160(4), Article 220. https://doi.org/10.1007/s44473-026-00229-y

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00229-y

Keywords: Commiphora gileadensis, chemotype, secondary metabolites, sesquiterpenes, basalt, granite, edaphic factors, Resource Availability Hypothesis, antioxidant activity, GC-MS, chemical ecology, arid ecosystems

Enhanced rock weathering has long been touted as one of the most promising carbon removal strategies because it leverages a process that has regulated Earth’s climate for billions of years. When rainwater, slightly acidified by dissolved carbon dioxide, percolates through silicate rocks such as basalt, the carbonic acid pulls calcium and magnesium ions out of the mineral lattice. These ions ultimately combine with carbonate in oceans and soils, forming stable minerals that sequester carbon for tens of thousands of years or longer. The catch is speed: natural weathering operates on geological timescales, and even crushed and spread basalt can take years to decades to absorb a meaningful fraction of the carbon dioxide applied to farmland alongside it.

The new study attacks that bottleneck at its chemical root. Siderophores are small organic molecules with an extraordinary affinity for iron, capable of prizing the metal out of mineral surfaces even at vanishingly low concentrations. In doing so, they destabilize the crystal structures of iron-bearing silicates, exposing fresh surfaces to attack by carbonic and organic acids. Microbiologists have understood this mechanism for decades, but the idea of engineering microbes to produce siderophores at industrial scale for climate purposes remained largely theoretical—until now.

The research team used synthetic biology tools to upregulate the biosynthetic gene clusters responsible for siderophore synthesis in their bacterial strain, carefully balancing the metabolic burden that enhanced production imposes on the cells. Overproducing secondary metabolites can cripple microbial growth, so the engineering had to thread a needle between maximizing output and keeping the organisms viable. The resulting strains secreted siderophore concentrations several times higher than wild-type counterparts, and when applied to crushed basalt in controlled experiments, the treated microbial communities accelerated mineral dissolution rates well beyond what natural weathering achieves.

Measurements of dissolved ions released from the rock confirmed that the engineered bacteria were genuinely driving enhanced weathering rather than simply growing more prolifically. Elevated concentrations of calcium, magnesium, and silicon in solution served as chemical fingerprints of accelerated mineral breakdown. The researchers also tracked the fate of the released cations, which are the direct precursors of the carbonate species that permanently store carbon dioxide, providing a quantitative link between microbial activity and the theoretical carbon removal potential of the system.

What makes the approach especially attractive is its compatibility with existing agricultural practice. Enhanced rock weathering proposals typically involve spreading crushed basalt—a byproduct of mining and quarrying industries—across croplands, where it can also supply nutrients and raise soil pH. Adding engineered bacteria or their siderophore products to this workflow requires no new land, no exotic infrastructure, and no dramatic change in farm operations. The biological catalyst simply boosts the yield of carbon removal per tonne of rock applied, improving the economics of a scheme whose costs have otherwise been dominated by the grinding and transport of stone.

The carbon math is compelling if the laboratory results translate to the field. A single tonne of basalt can, in principle, absorb on the order of hundreds of kilograms of carbon dioxide over its weathering lifetime. If microbial siderophores can compress that timeline or increase the fraction of rock that fully dissolves, the effective carbon removal capacity of each tonne of applied rock rises accordingly, and with it the viability of gigatonne-scale deployment scenarios that climate models suggest will be necessary alongside deep emissions cuts.

Significant hurdles remain before engineered weathering microbes see real-world deployment. Field soils are wildly heterogeneous environments where introduced strains face competition from established microbial communities, predation, and fluctuating moisture and temperature. Regulators will also demand rigorous assessment of any genetically modified organism released into open agricultural systems, and researchers will need containment strategies or self-limiting designs to address ecological concerns. The team acknowledges that scaling from petri dishes and reactor columns to windswept fields is the defining test ahead.

Still, the study marks a striking convergence of biotechnology and geoscience, suggesting that the tools of synthetic biology can be pointed not merely at medicines and materials but at the planet’s own climate-regulating chemistry. If follow-up field trials vindicate the laboratory findings, the humble bacterial molecules that microbes have used for eons to feed on rock-bound iron could become one of the cheapest levers available for scrubbing carbon dioxide from the sky—and a vivid reminder that some of the most powerful climate technologies may already be alive in the soil beneath our feet.

Subject of Research: Engineered bacterial siderophore production for enhanced silicate rock weathering and carbon dioxide removal

Article Title: Engineered bacterial siderophore production accelerates rock weathering for carbon removal

Article References: Dalvie, N. C., Jalihal, A. P., Fitzgibbon, A., Böhnke, J.-T., Hijaz, M., Justman, Q. A., Davis, S. J., Silver, P. A., & Springer, M. (2026). Engineered bacterial siderophore production accelerates rock weathering for carbon removal. Nature Biotechnology. https://doi.org/10.1038/s41587-026-03288-w

Image Credits: AI Generated

DOI: 10.1038/s41587-026-03288-w

Keywords: enhanced rock weathering, siderophores, carbon removal, synthetic biology, basalt, silicate minerals, carbon dioxide sequestration, soil microbiology, climate engineering, mineral dissolution, biogeochemistry, Nature Biotechnology