CaCO3 precipitation plays a pivotal role in fracture evolution and permeability in subsurface reservoirs, directly impacting the efficiency and reliability of geological carbon sequestration. Yet, how flow-driven transport interacts with nucleation, polymorph deposition, mineral transitions, and fracture heterogeneity remains poorly constrained. Here, we combine micromodel experiments, in situ Raman spectroscopy, pore-scale fluid and solute transport simulations, and Darcy-scale advection-diffusion-nucleation simulations to unravel coupled dynamics of flow, mass transfer, and mineral precipitation. We show that flow-controlled mixing plays a critical role on early-stage nucleation, polymorph precipitation, and subsequent fracture structure evolution. In most regions, supersaturation develops progressively through solute mixing, triggering initial calcite nucleates, followed by the accumulation of metastable CaCO3 phases that fill pore space and enhance the total precipitation mass. However, at high flow rates, reactants advected from finer fractures into coarser, high-velocity preferential flow paths form confined supersaturation zones along streamlines. These zones promote rapid amorphous calcium carbonate (ACC) formation and delay its transformation to stable calcite. These early-stage processes-including stochastic nucleation, transient ACC persistence, and polymorph precipitation and transitions-do not alter the final mineralogy but strongly regulate fracture geometry, saturation fields, and the reproducibility of precipitation. As a result, divergent long-term outcomes emerge: high flow rates restrict precipitation to narrower zones, producing reproducible but clog-prone fracture sealing; whereas low flow rates broaden saturation zones, amplify the stochastic nature of nucleation, and increase variability in precipitation distribution and fracture geometry evolution. Our findings reveal an underexplored mechanism by which flow-controlled mixing governs early-stage nucleation and polymorph precipitation, thereby regulating long-term fracture structure evolution and precipitation variability. These insights provide a mechanistic framework for optimizing CO2 injection strategies, predicting reservoir heterogeneity, and improving models of mineral trapping in fractured subsurface systems.

Abstract The Neogene expansion of C 4 grasslands transformed terrestrial ecosystems with marked influence on mammalian evolution, including hominins. However, the asynchronous C 4 expansion on different continents makes it difficult to identify the environmental drivers, especially for higher latitudes. Here we show that rainfall seasonality governed extratropical Plio-Pleistocene C 4 distributions in East Asia. Rainfall oxygen isotope ratios and clumped isotope soil temperatures exhibit coupled variations on the Chinese Loess Plateau (CLP) from 7 to 2.5 million years ago, indicating more spring rain during warmer times when the subtropical westerly jet was further poleward, and more concentrated summer rain under cooler climates. We attribute these changes to meridional shifts of a summer rain band on orbital and longer timescales. The most C 4 -rich ecosystems, as identified by organic carbon δ 13 C records, tracked this summer rain band, eventually eclipsing the southern CLP margin during the late Pleistocene cooling. Our model refines the East Asian paleomonsoon concept and explains the equatorward migration of extratropical C 4 ecosystems, highlighting the tight coupling between regional rainfall seasonality and vegetation.

The response of the East Asian summer monsoon (EASM) precipitation to Pleistocene global cooling is crucial for understanding Earth's climate and hydrological cycles. The long-term trend of the EASM precipitation during the Pleistocene remains hotly debated with two main hypotheses: one suggesting a gradually weakening EASM driven by global cooling, whereas the other proposing a gradually intensifying EASM influenced by the uplift of the Tibetan Plateau or strengthening Pacific Walker Circulation. The primary challenge in resolving this debate lies in disentangling the temperature effects from existing monsoon precipitation proxies, which complicates the interpretation of past climate records. Here, we present a new record of Pleistocene EASM precipitation change from North China, based on soil dolomite and calcite contents that are independent of temperature. Our results indicate increased interglacial EASM precipitation but near-constant glacial EASM precipitation in the long-term trend. This finding challenges the conventional view that global cooling weakened monsoon precipitation. We propose that Pleistocene EASM long-term evolution is controlled by the competition between the monsoon-weakening effects of global cooling and the monsoon-enhancing effects of the strengthening Walker Circulation, suggesting that even a cooling climate could strengthen monsoon precipitation. Our results hold profound implications for assessing the complex relationship between hydroclimatic cycles and global temperatures during the late Cenozoic.

Heavy metals were analyzed in rhizosphere soils and rice grains collected from typical black shale areas. The concentrations of As, Cd, Cu, and Zn in the rhizosphere soil exceeded the current soil environmental quality standards. Cd exhibited the highest bioaccumulation capacity, with 45

The long-term climate stability of the Earth has been attributed to the negative feedback between the rate of CO2-consuming silicate weathering and the partial pressure of atmospheric CO2. It is generally believed that the capability of silicate weathering in feedbacking climate is mainly associated with the rapid-eroding mountains where fresh bedrock adequately exposes. In contrast, the slow-eroding terrains are considered to have low climate sensitivity of silicate weathering due to the almost complete depletion of CO2-consuming Ca and Mg cations in highly-weathered top regolith. However, much of the Earth's history, marked by tectonic quiescence and slow erosion, has also exhibited significant climate stability. Here we demonstrate that the slow-eroding post-orogenic terrains exceptionally show strong temperature dependence of silicate weathering. This conclusion is drawn from a historical reconstruction of the weathering-derived clay production over the past similar to 23 million years, based on the sediments from the Ocean Drilling Program sites 1147/1148 offshore from the South China continent. We employ a sensitive proxy, the Rb/Zr ratio of fine sediments, showing that weathering of exposed granitic plutons closely tracks temperature changes. The resulting apparent activation energy (Ea) of silicate weathering (77.1 +/- 14.9 kJ/mol) is significantly higher than previous estimations for the slow-eroding terrains. Given the temporal and spatial dominance of slow-eroding terrains on global weathering flux, our findings suggest that the strong temperature dependence of weathering in these settings would largely enhance the sensitivity of global silicate weathering flux in response to temperature changes. This may help to explain the Earth's climate stability, particularly during periods of tectonic quiescence.

Coprecipitation of phosphate in calcium carbonate minerals is a ubiquitous geochemical phenomenon in marine sedimentation and cave stalagmite formation, however, it is not clear whether phosphate is incorporated into the calcite structure. In this research, we applied solid-state nuclear magnetic resonance (NMR) spectroscopy to analyze P speciation during coprecipitation with calcite. The 31P NMR results show three peaks with chemical shifts of 3.9, 3.0 and-1.0 ppm, indicative of at least three phosphate species in the coprecipitates. Combined with advanced 31P{1H} cross-polarization (CP)/MAS, 1H DE/MAS, 31P{1H} 2-d heteronuclear correlation (HetCor) and 31P{13C} cross-polarization rotational echo double resonance (CP-REDOR) NMR experiments, the 3.9 ppm peak can be tentatively assigned to calcite structural defects as amorphous calcium phosphate (ACP)-like environments while the 3.0 ppm peak arises from a carbonated hydroxyapatite (CHap). The 31P NMR peak at-1.0 ppm can be assigned to structurally incorporated phosphate in the calcite crystals in the form of HPO42-. Nano secondary ion mass spectrometry (NanoSIMS) and high-resolution scanning transmission electron microscopy (HR-STEM) analysis further suggests that the incorporated HPO42-substitutes for the structural carbonate group (CO32-) of calcite. However, the local expansion stress field generated with HPO42-incorporation in the calcite structure prevents PO4/CO3 isomorphous substitution and favors the precipitation of calcium phosphates. The findings of this study not only provide deep insights into carbonate crystal chemistry but also shed light on the application of carbonate materials as potent geochemical proxies in paleoenvironmental reconstructions.

Enhanced silicate weathering (ESW) is a geoengineering method aimed at accelerating carbon dioxide (CO2) removal (CDR) from atmosphere by increasing the weathering flux of silicate rocks and minerals. It has emerged as a promising strategy for CDR. Theoretical studies underscore ESW’s substantial potential for CDR and its diverse benefits for crops when applied to croplands. However, the well-known significant discrepancies in silicate weathering rates between laboratory and field conditions introduce uncertainty in CDR through ESW. By compiling data from recent literature, we calculated and compared CDR efficiency (t CO2 tsilicate−1 ha−1 y−1) observed in mesocosm experiments and field trials. The findings indicate that CDR efficiencies in field trials are comparable to or exceeding that observed in mesocosm experiments by 1–3 orders of magnitude, particularly evident with wollastonite application. The hierarchy of CDR efficiency among silicates suitable for ESW is ranked as follows: olivine ⩾ wollastonite > basalt > albite ⩾ anorthite. We suggest the potential role of biota, especially fungi, in contributing to higher CDR efficiencies observed in field trials compared to mesocosm experiments. We further emphasize introducing fungi known for their effectiveness in silicate weathering could potentially enhance CDR efficiency through ESW in croplands. But before implementing fungal-facilitated ESW, three key questions need addressing: (i) How does the community of introduced fungi evolve over time? (ii) What is the long-term trajectory of CDR efficiency following fungal introduction? and (iii) Could fungal introduction lead to organic matter oxidation, resulting in elevated CO2 emissions? These investigations are crucial for optimizing the efficiency and sustainability of fungal-facilitated ESW strategy.

Dissolution of secondary clay minerals during continental weathering (hereafter clay dissolution) has been proposed as a mechanism to explain some of the low seawater lithium isotopic ratios (δ 7 Li) observed in the geologic past. However, direct evidence for clay dissolution on Earth surface remains limited, and the controlling factors are poorly understood. Here, we suggest that δ 7 Li of fine sediments can serve as a proxy for clay dissolution. We analyzed δ 7 Li of the sediments from the Ocean Drilling Program site 1148, and developed a stoichiometric model to disentangle the respective contributions of source rock fragments and marine authigenic aluminosilicate clays to the sediment Li budget. Our results reveal low δ 7 Li in continentally formed clays during the warm interval of 23–15 Ma, followed by a progressive increase during 15–5 Ma, coinciding with global cooling. We suggest that warm and tectonically stable conditions might have promoted clay dissolution on continents.

Quantifying climate sensitivity is essential for future climate projections, yet it varies with major Earth system changes. We present a glacial CO₂ reconstruction using paleosols from the Chinese Loess Plateau, covering 2580 to 800 thousand years ago. A stepwise decline in glacial CO₂ levels from ~300 ppm to <200 ppm is observed. Our paleosol-based CO₂ estimates support the key role of atmospheric CO₂ in driving major climate transitions during the Pleistocene, such as the long-term global cooling and the amplification of the glacial cycles. Based on compiled glacial and interglacial CO2 records, Earth system sensitivity, defined as the global temperature change for a doubling of CO2 once the whole Earth system has reached equilibrium, is estimated to be ~6.2-7.4 K (3.2-12.0 K, 95% confidence). Equilibrium climate sensitivity, after accounting for the different efficacy between ice-sheet and CO2 forcing and other slow feedbacks, is estimated to be 3.3 K (2.1-6.3 K, 95% confidence) and 3.7 K (1.7-6.3 K, 95% confidence), respectively. The lack of a significant difference between these values suggests no apparent state-dependency of climate sensitivity between glacial and interglacial climate states.

Agricultural soils in karst regions present a remarkable paradox where high geochemical background levels of heavy metals correspond with unexpectedly low crop uptake, challenging traditional risk assessment frameworks and limiting agricultural development. To decode this paradox, we investigated the geochemical speciation of cadmium (Cd), nickel (Ni), and zinc (Zn) in soil-rice systems in southwestern China, which collectively constitute the world’s largest continuous karst region and represent diverse soil weathering stages. We employed three chemical extraction methods that revealed reactive pools ranking as Cd (58.74%) > Zn (7.31%) > Ni (4.65%) and risk patterns varying with soil type (Andosols > Cambisols/Gleysols > Lithosols), while multi-surface speciation model (MSM) elucidated the underlying mechanisms. We identified a stage activation-contamination model (SACM) that demonstrates how pH-dependent weathering controlled heavy metal distribution among dissolved, surface-active, semi-stable carbonate, and nonactive species, thereby explaining the observed risk patterns. Specifically, in alkaline soils (pH > 7.50), Cd and Zn were primarily humic acid (HA)- and carbonate-bound, while Ni was goethite-bound. As weathering intensified, the reactive pool shifted to more active HA- and hydrous ferric oxide (HFO)-bound species. In acidic soils (pH < 6.50), dissolved and HA-bound species dominated. Both random forest, offering robust predictions using readily available data, and MSM stepwise regression models, providing high accuracy with mechanistic insights, effectively predicted rice risks. This study from speciation and activation model to prediction model clarifies why standardized risk assessments fail in karst regions and offers practical tools for accurate risk evaluation and management in these agricultural environments.

Environmental microbial communities are crucial in regulating ecosystem functions and are increasingly affected by human-induced geochemical perturbations. While microbial communities are known to shift under such perturbations, the explicit link between these shifts and corresponding biogeochemical processes remains unclear. Here, we conducted time-series sediment incubation experiments under elevated nitrate conditions, combining 16S rRNA gene sequencing, qPCR, and metagenomics to track microbial taxonomic and functional dynamics. We further developed a gene-centric, process-based biogeochemical model to quantitatively connect microbial community structure to geochemical reaction kinetics. Our results revealed that functional metagenomics provided a broader view of functional diversity than qPCR and enabled detailed analysis of gene co-occurrence. Through modeling, we uncover a quantitative coupling between functional gene abundance and reaction rates under geochemical perturbations. However, this relationship can be obscured by redox-driven abiotic processes affected by perturbations and the nonlinear nature of enzyme-mediated reactions, making it difficult to resolve using standard statistical approaches. Together, these findings improve our understanding of the linkage between microbial function and biogeochemical processes, and underscore the value of gene-centric, process-based models for predicting ecosystem behavior under geochemical stress.

Spatial distribution of soil arsenic (As) is heterogeneous. Making clear the dominant factor(s) controlling its spatial variation contributes to the differentiation of its natural background from anthropogenic pollution. Recent studies have found that the "high background" of soil heavy metals may be induced by the process of carbonate weathering. However, the extent, process, and factors that controls the degree of this enrichment, is still unclear, especially in large spatial scales. In this study, this problem is to be revealed by a compilation and spatial data mining of soil geochemical data for Australia, North America, Europe, and China with a collection and chemical analysis of bedrock and soil profiles in a typical region. The results indicated that the process of carbonate weathering strengthened the As enrichment in the soil; therefore, the carbonate rock underlaid regions could be distinguished from those of other bedrocks in the soil As maps. In the southwest region of China, an area larger than 12,000 km(2) exceeding the intervention value of 100 mg/kg could be produced according to the national standard. Iron minerals play an important role for this enrichment as they serve as carriers for As during the stages of both carbonate leaching and the decomposition of silicate minerals. Geodetector results indicated a significant dependence on climate for the degree of enrichment, and both higher temperature and precipitation were necessary, which caused a decreasing trend of soil As on carbonate region from the warm and humid south to the cold and dry north in China. The dependence of soil As concentration on the mean average precipitation (MAP) and mean average temperature (MAT) was formulated using the data of the wider geographical regions across the world, and a theoretically predicted map has been produced to show the extent caused by this causation.

Silicate weathering acts as a significant carbon sink and sustains ecosystems by supplying essential elements, thus shaping Earth's habitability. However, our understanding the evolution of silicate weathering rates remains incomplete, with most knowledge focusing on rate decreases at solution-silicate interfaces, while reactivity at fungi-weathered silicate interfaces is poorly understood. This study shows that the fungus Talaromyces flavus significantly enhances the dissolution of olivine and lizardite covered by Si-rich layers up to 3.6 mu m thick by one to two orders of magnitude compared to abiotic conditions. Initially, fungal hyphae create dissolution channels similar to 10-65 nm deep, promoting element release from altered layers and underlying pristine minerals while oxidizing structural Fe(II). Over time, hyphae penetrate these altered layers, exposing and etching the underlying minerals. Our data suggest that fungal etching and penetration degrade the altered layers, leading to increased interdiffusion of weathering agents and released cations, thereby continuously driving silicate weathering.

AbstractIt is debated whether there was strong climate seasonality during the Eocene, which provides a close geological analogy for near‐future scenarios of greenhouse gas emissions. Lithological data suggest the existence of a broad arid zone centered around 30°N paleo‐latitude, while a humid climate was supported by palaeobotanic assemblages in East Asia. Here, we report the occurrence of massive primary lacustrine dolomite and magnesite in the central East Asia during the middle Eocene. We provide a novel perspective from magnesium isotopes to link the formation of Mg‐carbonates to seasonal dry‐wet cycles. Rapid magnesium input during the rainy season and intense evaporation in the dry season likely caused the formation of magnesium carbonates in an enclosed lake. These findings provide insights into hydroclimatic seasonality during the Eocene, contributing to our understanding of the hydrological cycle response to a greenhouse climate.

The capture of CO 2 has become a global research focus. Rock weathering in the natural environment makes significant contributions to the stable carbon capture at both long and short time scales. However, traditional methods of estimating carbon capture potential are still uncertain due to the solely instantaneous carbon capture rates, dependence of measured data, and difficulty in predicting future carbon sink potential. Here, the estimated carbon capture potential of rock weathering using conventional methods and the PROFILE weathering model were compared for the various rocks in subtropics in China. The results showed that the carbon capture rates estimated by the GEM-CO 2 model vary from 1.64 to 27.40 mmol·m − 2 ·d − 1 , while 2.63 ~ 13.46 mmol·m − 2 ·d − 1 by traditional the water chemistry method. Similarly, carbon capture rates calculated by the PROFILE model based on chemical weathering rate of individual specific mineral, ranging from 0.03 to 19.03 mmol·m − 2 ·d − 1 . The results of the PROFILE calculation showed that, the carbon capture rate was 1.30 to 1.99 times in summer than in winter due to the higher temperature and precipitation. In extreme climates, high temperatures (≥ 30°C) and heavy precipitation (≥ 25mm) have increased the capture rate of carbon dioxide by approximately 21.33% and 66.23%, respectively. On the interdecadal time scale, the carbon capture rate increased by 6.1% from 1970 to 2020, due to temperature rising by 1.4°C, precipitation increasing by 2.8%, and partial pressure of atmospheric carbon dioxide ( pco 2 ) increasing by 28.4%. Further, we predict an increase in carbon capture rates will change approximately from 4.7 to 5.1% in the period of 2020–2100 under four Representative Concentration Pathway (RCP) modes. The findings of this study will offer novel scientific recommendations and methods for future research and policy making on global carbon neutrality.

The diversity of soil adsorbents for arsenic (As) and the often-overlooked influence of manganese (Mn) on As(III) oxidation impose challenges in predicting As adsorption in soils. This study uses Mössbauer spectroscopy, X-ray diffraction of oriented clay, and batch experiments to develop a kinetic coupled multi-surface complexation model that characterizes As adsorbents in natural soils and quantifies their contributions to As adsorption. The model integrates dynamic adsorption behaviors and Mn-oxide interactions with unified thermodynamic and kinetic parameters. The results indicate that As adsorption is governed by five primary adsorbents: poorly crystalline Fe oxides, well crystalline Fe oxides, Fe-rich clay, Fe-depletion clay, and organic carbon (OC). Fe oxides dominate As adsorption at low As concentrations. However, at higher As concentrations, soils from carbonate strata, with higher content of Fe-rich clay, exhibit stronger As adsorption capabilities than soils from Quaternary sediment strata. The enrichment in Fe-rich clay can enhance the resistance of adsorbed As to reduction processes affecting Fe oxides. Additionally, extensive redox cycles in paddy fields increase OC levels, enhancing their As adsorption compared to upland fields. This model framework provides novel insights into the intricate dynamics of As within soils and a versatile tool for predicting As adsorption across diverse soils.

This study examined the concentrations, sources, and health risks associated with 7 heavy metals in Chinese pomegranates. The results showed that the heavy metal in pomegranates was within standard limits, and the accumulation of heavy metals was low. PCA showed that Cd and Hg in pomegranates originate from irrigation water, Zn, As, and Cu from soil, and Cr and Pb from fertilizers. MLR and Monte Carlo sensitivity analysis showed that soil and irrigation water were the primary sources of heavy metals in pomegranates, with Zn, As, Cu, and Pb primarily originating from soil, and Cd, Cr, and Pb predominantly coming from irrigation water. The presence of organic matter and Ca in soil influenced heavy metal accumulation in pomegranates, other properties (Mg, Fe, and pH value in soil) have minor effects. The TTHQ for both adults and children remained below 1, while the TTRisk exceeded 1×10-4, mainly due to the hazardous impact of As in water. The upper 95% uncertainty limit indicated that residents were exposed to both non-carcinogenic and carcinogenic risks, primarily due to the toxicity of Cr in soil and As in water. Strengthening heavy metal screening in soil and water and enhancing pollution management policies are imperative.

The carbon sink effect of afforestation is key to mitigating current global warming. China’s planted forest area accounts for more than a quarter of the global afforestation efforts and has made a prominent contribution to carbon sequestration. Previously, afforestation as a carbon sink was primarily evaluated in terms of the biomass carbon pool and soil organic carbon pool. Plants play a significant role in enhancing the chemical weathering of rocks and minerals, which can lead to more CO2 consumption. However, role of plants in enhancing chemical weathering and contributing to CO2 removal has not been considered when calculating the artificial sink. This paper reviews relevant studies on the carbon sinks from weathering and forest biomass in China and synthesizes the research on how plants affecting weathering in natural ecosystems. Based on this, we estimate the atmospheric CO2 consumption from afforestation-enhanced weathering in China. If afforestation increases the natural weathering rate by a factor of four on average, the national carbon sink through weathering could increase by 33 %. This increase in carbon sink capacity amounts to 35 million tonnes CO2/y and represents ∼1/6 of China’s afforestation biomass carbon sink during 2014–2018. The significant contribution underscores the need for further comprehensive research into the carbon sink effect of afforestation-enhanced weathering in the future. Understanding how afforestation, global warming, and other anthropogenic activities interact to affect weathering will provide insights to accurately evaluate the role of large-scale afforestation in China’s efforts to meet its “dual-carbon” goals and mitigate global warming.