Carbonate Minerals Research Articles

Rutile solubility in aqueous sodium salt solutions at high pressures and temperatures: in-situ observations using a diamond anvil cell

Knowledge of rutile (TiO2) solubility in aqueous fluids at high pressures and temperatures is of primary importance to a quantitative understanding of the high field strength elements (HFSE) transport in subduction zones. We attempted to redetermine rutile solubility in aqueous NaF solution and newly assess rutile solubility in aqueous Na2CO3 and Na2SO4 solutions through in-situ optical observations of the complete dissolution of a rutile grain in a hydrothermal diamond anvil cell (HDAC) at 823–974 °C and a pressure of approximately 0.9–1.8 GPa. The reproducibility of the experimental results in Na2CO3 solution was confirmed across individual experiments and repeated cycles within a single experiment. The rutile solubility in the aqueous sodium salt solutions was significantly higher than the previously reported solubility in pure H2O obtained with weight loss techniques using a piston–cylinder apparatus. While the increase in the solubility with added NaF was consistent with previous findings, the present results suggest that the solubility-promoting effect is smaller than previously reported. The high solubility in the aqueous sodium salt solutions may be attributed to the formation of Ti(IV) complexes with potential ligands (e.g., OH−, CO32−, SO42−, and F−) and sodium that remain to be characterized. Our findings indicate that sodium carbonate and sulfate-bearing fluids in subduction zone lithologies may play a role in efficiently transporting HFSE. A pertinent example of this could be the occurrence of carbonate and sulfate minerals in rutile-rich veins and fluid inclusions from high-pressure metamorphic rocks.

Electrochemically Assisted Calcium Silicate Utilization for Phosphate Recovery.

Electrochemical pH-swing systems have demonstrated significant potential across diverse applications, including chemical production, carbon capture, and water treatment. However, conventional systems predominantly depend on costly ion exchange membranes, which are often plagued by fouling and scaling challenges. Here, we introduce an ingenious electrochemically assisted calcium silicate (EACS) system capable of achieving a rapid pH swing from 8.5 to 10 within 1 h through the in situ utilization of H+ and OH- ions, eliminating the need for membranes. The EACS system incorporates a novel 3D-printed porous basket holder designed to house calcium silicate particles and a rod-shaped Ru-Ir anode. Under closed-circuit conditions, the packed calcium silicate reacts with H+ generated at the anode, releasing Ca2+ into bulk solution, while OH- produced at the cathode accumulates, resulting in an elevated bulk pH. This mechanism enables the EACS system to achieve exceptional phosphorus recovery efficiency (88.4%-96.6%) from various waste streams, with energy consumption as low as 24.4 kWh kg P-1. Long-term continuous flow experiments demonstrate that periodic replacement of depleted silicate minerals sustains system efficiency and stability. Furthermore, comparative analysis reveals that while carbonate and silicate minerals are functionally viable, silicate minerals exhibit superior performance in removal kinetics, product purity, and reduced carbon emissions. Notably, the effluent from the EACS system, enriched with Ca2+ and characterized by a high pH, exhibits potential for direct air carbon capture. The proposed EACS system offers a transformative approach to environmental remediation and industrial applications, leveraging the fundamental principle of pH-swing to open new avenues for sustainable solutions.

Sulfur-mediated transformation, export and mineral complexation of organic and inorganic C, N, P and Si in dryland soils

The transformation characteristics of mineral-associated soil components have profound impacts on their physical, biological, and chemical properties in drying-affected soils, whereas their mechanisms of sequestration and transformation remain elusive. To elucidate these phenomena, the solid-phase, water extracts (labile state, LS) and alkali-extracts (complexed state, CS) of four drying-affected soil types were examined. On average, the contents of soil organic carbon (SOC), soil total nitrogen (STN), and soil total hydrogen (STH) decreased in the order: forest > grassland > agriculture > desert. The extracted dissolved organic matter (DOM)LS, DOMCS and nutrients varied greatly among soil types, which indicated the occurrence of mineralization, sequestration, neoformation, and either export or emission. In particular, the relatively high levels of dissolved inorganic carbon (DIC)LS and relatively low levels of DICCS in agricultural soils could be ascribed to the impact of human activities, i.e., tilling and cultivation, on mineral-bound DIC, leading to its export in LS forms. The stable isotopes of δ13C-SOC and their significant relationships with DICLS and SO42‒LS+CS suggest the occurrence of carbon and sulfur sequestration through the uptake of CO2, DIC, or carbonyl sulfide (COS) following their generation from SOC or DOM mineralization. In forested and agricultural soils, the humic substances (HS) components in LS forms were subjected to a substantial degradation, whereas HSCS components remained mostly unaffected, implying their occurrence in organo-mineral protection. Overall, low soil total sulfur (STS) and sulfate (SO42‒)LS+CS contents were correlated with high amounts of soil components in both the solid and liquid phases, and vice versa. These findings suggest that microbial SO42‒ might operate in the dissolution and mineralization of HS-bound organo-minerals, which would potentially generate soil inorganic carbon (SIC) or DIC, leading to either their subsequent sequestration as carbonate minerals or their exports and emissions as DIC and CO2.

Research Progress and Ecological Implications of Soil Nematode Metabolic Footprint

Soil nematodes, as a key functional group in soil ecosystems, have a profound impact on carbon and nitrogen cycles, microbial community dynamics, and soil health. Metabolic footprint, as a core indicator for quantifying nematode ecological effects, integrates processes such as respiration, decomposition of excreta, and microbial regulation. Recent breakthroughs in molecular biology and stable isotope tracing technologies have significantly enhanced the accuracy of nematode metabolic pathway analysis. Studies have shown that interspecific differences in nematodes lead to significant variations in carbon and nitrogen transformation efficiency, for example, the organic carbon mineralization rate of fungivorous nematodes can reach 60%, while that of bacterivorous nematodes is only 30-45%. At the same time, environmental factors (such as temperature, pH) and biological interactions (such as root signaling of plants, control by predators) further affect the ecological function contributions of nematodes by regulating their metabolic activity. However, existing research still has shortcomings in the refinement of metabolic mechanisms, long-term effect assessment, and the construction of climate change response models. This article systematically reviews the research progress of nematode metabolic footprint, reveals its ecological regulatory mechanisms, and proposes that future research should focus on the integration of omics technologies and the development of cross-scale models to provide theoretical support for soil resource management and the achievement of carbon neutrality goals.

Diagenetic Evolution and Formation Mechanism of Middle to High-Porosity and Ultralow-Permeability Tuff Reservoirs in the Huoshiling Formation of the Dehui Fault Depression, Songliao Basin

The fluid action mechanism and diagenetic evolution of tuff reservoirs in the Cretaceous Huoshiling Formation of the Dehui fault depression are discussed herein. The fluid properties of the diagenetic flow are defined, and the pore formation mechanism of the reservoir space is explained by means of thin sections, X-ray diffraction, electron probes, scanning electron microscopy (SEM), cathodoluminescence, and stable carbon and oxygen isotopic composition and fluid inclusion tests. The results reveal that the tuff reservoir of the Huoshiling Formation is moderately acidic, and the physical properties of the reservoir are characterized by middle to high porosity and ultralow permeability. The pore types are complex, comprising both primary porosity and secondary porosity, with dissolution pores and devitrification pores being the most dominant. Mechanical compaction and cementation are identified as key factors reducing reservoir porosity and permeability, while dissolution and devitrification processes improve pore structure and enhance pore connectivity. Diagenetic fluids encompass alkaline fluids, acidic fluids, deep-seated CO+-rich hydrothermal fluids, and hydrocarbon-associated fluids. These fluids exhibit dual roles in reservoir evolution: acidic fluids enhance the dissolution of feldspar, tuffaceous materials, and carbonate minerals to generate secondary pores and improve reservoir quality, whereas alkaline fluids induce carbonate cementation, and clay mineral growth (e.g., illite) coupled with late-stage mineral precipitation obstructs pore throats, reducing permeability. The interplay among multiple fluid types and their varying dominance at different burial depths collectively governs reservoir evolution. This study underscores the critical role of fluid–rock interactions in controlling porosity–permeability evolution within tuff reservoirs.

Favourable exploration lithofacies of hybrid sedimentary shales in the Dongpu depression, Bohai Bay Basin

Hybrid sedimentary shales (HSS) are key components of continental shale oil resources. The inherent heterogeneity of HSS lead to rapid variations in oil content and mobility, complicating sweet spot prediction. Previous studies have classified HSS lithofacies and assessed oil content. However, favourable lithofacies for oil content and mobility remains debated. This study classified the Shahejie Formation HSS from the Dongpu Depression, Bohai Bay Basin into massive argillaceous shale (Lithofacies I), bedded argillaceous shale (Lithofacies II), and laminated calcareous shale (Lithofacies III) based on sedimentary texture, mineral composition, and total organic carbon (TOC) content. The light hydrocarbon calibrated oil content (S1C), oil mobility (OSI), and micro-migration hydrocarbon content (δQ) variations among these lithofacies were conducted to determine favourable oil content and mobility lithofacies. Results show that the Lithofacies III exhibited the highest average TOC (1.56 w. t. %), hydrogen index (HI) (264 mg/g TOC), oil content (S1C = 1.81 mg/g), and oil mobility (OSI = 188 mg/g TOC). Geochemical data revealed that Lithofacies III also display the most pronounced micro-migration (average δQ = −138 mg/g TOC). TOC, Tmax, and δQ influence the oil content of HSS, with TOC being the primary factor, suggesting that shales with high organic matter abundance possess better hydrocarbon generation potential and can produce more shale oil. Conversely, δQ, clay minerals, and carbonate minerals affect oil mobility, with δQ being the dominant factor, highlighting the role of micro-migration in pore connectivity, transport, and enrichment of shale oil within the extramicro-migration and intramicro-migration units. Global comparisons show that micro-migration drives HSS oil enrichment, while sedimentary environment and tectonic setting influence oil content and mobility. This study provides new insights into key factors controlling HSS oil micro-migration and enrichment, advancing global exploration and development of HSS resources.

Coal dust particles can upregulate the expression of NLRP3 inflammasome components in rat alveolar macrophages through phagocytosis

Previous studies have demonstrated that silica can activate the NLRP3 inflammasome, and that macrophage phagocytosis is an essential step in this process. Although carbon is the primary component of coal dust particles, it also contains other impurities such as free silica, clay, sulfides, and carbonate minerals. Additional research is still necessary to discover if NLRP3 can be triggered due to the low silica content of coal dust particles. The purpose of this study is to investigate whether coal dust particles can induce the translation and transcription of NLRP3 inflammasome components in rat alveolar macrophages (NR8383) and whether Cytochalasin B may inhibit this process. According to the findings of our research, coal dust particles can upregulate the NLRP3 inflammasome components and IL-1β, a downstream inflammatory component. Furthermore, LPS and coal dust particles work in concert to raise the NLRP3 inflammasome components protein and transcript level in macrophages. Interestingly, the protein and transcript level of NLRP3 inflammasome components dramatically dropped when cells were concomitantly exposed to the actin polymerization inhibitor Cytochalasin B. This suggests that cellular uptake is required for coal dust particles to exert their pro-inflammatory effect.

Preservation and alteration of inclusion-based calcite-water oxygen isotope and clumped isotope temperature signals in calcite veins

Knowledge of the formation temperatures of geological deposits is essential for investigating their genesis. Oxygen isotope thermometry (OIT), using the temperature dependence of oxygen isotope fractionation between host carbonate mineral and mineral-forming water trapped in fluid inclusions, and clumped isotope thermometry, based on the degree of 13C and 18O clumping, are receiving increasing interest. However, only a few studies have applied combinations of these methods, and their databases are limited. In this study, we compare OIT and clumped isotope temperatures obtained for 18 samples from Mesozoic to early Cenozoic calcite veins. Our analysis indicates that the formation temperatures were preserved in the clumped isotopic compositions (16–45 °C), whereas the OIT temperatures were shifted to lower temperatures (− 2 to 33 °C). An OIT temperature shift occurred, due to a retrograde oxygen isotope exchange between the fluid inclusion water and the host calcite. These results imply that the retrograde isotope exchange should be taken into consideration, even for low-temperature carbonate deposits, if a sufficiently long time is available.

Influence of biochar feedstock blends on soil enzyme activity, nutrient cycling, lettuce biomass accumulation and photosynthesis

The thermal conversion of municipal sewage sludge (MSS) offers significant potential for sustainable waste management, particularly through the production of biochar. This study investigates the properties and soil application effects of three biochar types produced via pyrolysis: (i) pure sewage sludge (100%), (ii) sewage sludge blended with sawdust (50%+50%), and (iii) sewage sludge combined with sawdust and zeolite (50%+45%+5%). These biochars were applied at rates of 2.5% and 7.5% (w/w) to arable soil and assessed in an 8-week greenhouse experiment using lettuce (Lactuca sativa L. var. Brilant) as a model crop. The sewage sludge biochar was characterized by high nitrogen, phosphorus, and water-extractable calcium but exhibited low organic matter and organic carbon content. It enhanced soil enzyme activities related to carbon and nitrogen mineralization without affecting microbial respiration. However, at 7.5% application rate, this biochar caused the highest chlorophyll b content in lettuce, despite acidifying the soil. Adding sawdust to the pyrolysis feedstock significantly increased organic matter, organic carbon (with reduced recalcitrance), and the C: N ratio of biochar. This biochar formulation promoted microbial activity (as indicated by changes in soil respiration) and nutrient cycling, particularly through increased glucosidase activity. Conversely, addition of zeolite to the pyrolysis feedstock reduced the organic matter and organic carbon content while increasing biochar recalcitrance and nutrient immobilization, particularly of sulfur, ammonium, phosphorus, and calcium. At the 7.5% dose, the sawdust + zeolite-enriched biochar improved soil pH and potentially enhanced nutrient retention. However, it did not stimulate microbial enzyme activity or respiration, leading to lower photosynthetic pigment levels and reduced biomassin lettuce, especially at higher application rate. For short-term soil applications under the conditions of this pot trial, the sewage sludge-sawdust biochar demonstrated the most beneficial effects, rapidly stimulating microbial activity and nutrient transformation. In contrast, the sewage sludge-sawdust-zeolite biochar limited nutrient availability and plant growth, suggesting it may be less suitable for immediate soil and plant nutrition. Long-term studies are needed to fully assess the implications of these biochar types for sustainable agriculture. This study highlights the importance of feedstock composition and selection in tailoring biochar properties to meet specific soil and crop requirements.

Carbon Dioxide Capture in Rocks Of The Oceanic Floor

To explain each of the processes involved. Starting with carbon sequestration from the processing of carbon dioxide from the atmosphere, its management and optimal conditions, mineral carbonation of ocean floor rocks, and the conditions of oceanic ridges. To outline a proposal that allows the process of carbon dioxide capture and carbonation by injection into ocean floor rocks to be sustainable.

How Acid Iron Dissolution in Aged Dust Particles Responds to the Buffering Capacity of Carbonate Minerals during Asian Dust Storms.

Aerosol deposition significantly impacts ocean ecosystems by providing bioavailable iron (Fe). Acid uptake during the transport of Fe-containing particles has been shown to cause Fe dissolution. However, carbonate in dust particles affects the Fe acidification process, influencing Fe dissolution. Here, we carried out atmospheric observations and modeling to show that Fe solubility substantially increased from locations near dust sources to downwind regions in aged dust particles with pH > 3, driven by proton-promoted dissolution. We found that Fe solubility remained low when Ca solubility was under 45 ± 5%, but increased with Ca solubility when it was above 45 ± 5%. Moreover, we found that Fe dissolved in aqueous Ca-nitrate coatings on Fe-containing dust particles. Our results suggest that the mixing state and buffering capacity of carbonate and Fe minerals should be represented in atmospheric biogeochemical models to more accurately simulate acid Fe dissolution processes.

A Novel Perspective on the Role of Hydroxyl Radicals in Soil Organic Carbon Mineralization within the Detritusphere: Stimulating C-Degrading Enzyme Activities.

Detritusphere is a hotspot of carbon cycling in terrestrial ecosystems, yet the mineralization of soil organic carbon (SOC) within this microregion associated with reactive oxygen species (ROS) remains unclear. Herein, we investigated ROS production and distribution in the detritusphere of six representative soils and evaluated their contributions to SOC mineralization. We found that ROS production was significantly correlated with several soil chemical and biological factors, including pH, water-soluble phenols, water-extractable organic carbon, phenol oxidase activity, surface-bound or complexed Fe(II) and Fe(II) in low-crystalline minerals, highly crystalline Fe(II)-bearing minerals, and SOC. These factors collectively contributed to 99.6% of the variation in ROS production, as revealed by redundancy analyses. Among ROS, hydroxyl radicals (•OH) were key contributors to SOC mineralization, responsible for 10.4%-38.7% of CO2 emissions in ROS quenching experiments. Inhibiting •OH production decreased C-degrading enzyme activities, indicating that •OH stimulates CO2 emissions by increasing enzyme activity. Structural equation modeling further demonstrated that •OH promotes C-degrading enzyme activities by degrading water-soluble phenols to unlock the "enzyme latch" and by increasing SOC availability to upregulate C-degrading gene expression. These pathways contributed equally to SOC mineralization and exceeded its direct effect. These findings provide detailed insight into the mechanistic pathways of •OH-mediated carbon dynamics within the detritusphere.

Exploring Geochemical Characteristics of Composite Geothermal Reservoirs for Sustainable Utilization: A Case Study of the Northwestern Shandong Geothermal Area in China

Presently, geothermal resources have been globally recognized as an indispensable component of the energy system due to their sustainability. However, previous studies on geothermal reservoirs focus primarily on single reservoirs, lacking a systematic investigation of composite geothermal reservoirs. The geothermal reservoirs in the northwestern Shandong geothermal area in China are primarily of sandstone and karst types, characterized by extensive distributions, shallow burial depths, high water temperatures, and high water abundance, holding considerable potential for exploitation. This study explored the hydrochemical, isotopic, and circulation characteristics of geothermal fluids in the composite geothermal reservoirs in the study area using methods like hydrogeochemistry and geothermal geology. The purpose is to determine the geochemical differences in geothermal fluids across the composite geothermal reservoirs and provide scientific support for subsequently efficient and sustainable exploitation and utilization of geothermal resources in the study area. The composite geothermal reservoirs in the study area are composed of porous sandstone geothermal reservoirs (also referred to as sandstone reservoirs) in the upper part and karst-fissured geothermal reservoirs (also referred to as karst reservoirs) in the lower part. The results show that the geothermal fluids in the sandstone and karst reservoirs are primarily of Na-Cl-SO4 and Na-Ca-Cl-SO4 types, respectively. The hydrochemical composition of geothermal fluids in the karst reservoirs is principally influenced by the precipitation–dissolution equilibrium of carbonate and sulfate minerals, while that in the sandstone reservoirs is predominantly influenced by the precipitation–dissolution equilibrium of carbonate and silicate minerals, as well as cation exchange reactions. The temperatures of the karst reservoirs were calculated at 52.9–82.09 °C using geothermometers. Given the cold-water mixing ratios range from 89% to 96%, the corrected reservoir temperatures vary from 200 to 225 °C. In contrast, the temperatures of the sandstone reservoirs were calculated at 60.54–85.88 °C using geothermometers. These reservoirs exhibit cold water mixing ratios ranging from 85% to 90%, and their corrected reservoir temperatures vary from 150 to 200 °C accordingly. The circulation depths of geothermal fluids in the karst and sandstone reservoirs range from 1107.28 to 1836.69 m and from 1366.60 to 2102.29 m, respectively. The study area is primarily recharged by meteoric water from Mount Tai and the Lushan and Yishan mountains (collectively referred to as the Tai-Lu-Yi mountains) to the southeast of the study area. Investigating the differences in geochemical characteristics of geothermal fluids in composite geothermal reservoirs in the study area is significant for balancing the exploitation and supply of geothermal resources, optimizing the exploitation and utilization modes, and promoting the efficient and sustainable exploitation and utilization of geothermal resources in the study area.

The Geological Characteristics of Low‐Permeability Sandstone Uranium Deposit in Ordos Basin, North China: Implications of Cause of Low Permeability and Corresponding In Situ Leaching Methods

ABSTRACTThis study delves into the low‐permeability sandstone uranium deposits in China's Ordos Basin, examining the Daying and Bayinqinggeli deposits. Employing x‐ray diffraction, clay mineral analysis, x‐ray fluorescence, core porosity, gas permeability tests, micrometre computed tomography (CT), and scanning electron microscopy (SEM), the research reveals the low‐permeability genesis of these uranium deposits. The findings highlight a high presence of clay minerals, with Daying from 11.5% to 31.5%, and Bayinqinggeli at about 10%. Dense calcareous interlayers are common, with carbonate minerals like calcite and dolomite filling pore spaces and cementing rock‐forming minerals, reducing pore sizes and ineffective connectivity, creating dead pore spaces and lowered permeability. The study concludes that the high montmorillonite content and calcareous cementation are the main causes of low permeability, providing a theoretical basis for future permeability enhancement and sustainable exploitation of uranium resources.

Photoactivation of oxidative degradation and mineralization of ceftriaxone with excilamp radiation

Among organic compounds resistant to biodegradation, antibiotics are of particular interest because their constantly increasing consumption has resulted in their presence in almost all components of aquatic ecosystems. With the use of advanced oxidation processes, it is possible to achieve conversion not only of target compounds but also of their reaction intermediates, which are often more toxic. Close attention is paid to the use of persulfates as precursors of reactive oxygen species, which are activated via combined methods involving ultraviolet radiation. Modern mercury-free sources include KrCl exilamps emitting quasi-monochromatic radiation. This study is the first to examine the kinetics of oxidation of a β-lactam antibiotic (ceftriaxone) and mineralization of total organic carbon by persulfate under the UVC radiation of a KrCl exilamp. Different oxidative systems were comparatively evaluated. The efficiency of target compound degradation was found to increase in the series {S2O82-} << {UV} < {Fe2+/S2O82-} < {UV/S2O82-} < {UV/Fe2+/S2O82-}. The total organic carbon was mineralized only in the oxidative systems {UV/Fe2+/S2O82-} > {UV/S2O82-}. The optimal conditions for complete conversion of ceftriaxone and deep mineralization of total organic carbon (43–60%) in the {UV/Fe2+/S2O82-} system were achieved at a molar ratio of [S2O82-]:[Fe2+] = 10. Both sulfate radical anions and hydroxyl radicals were shown to participate in ceftriaxone degradation and mineralization of total organic carbon. The obtained results indicate the viability of using the UVC radiation of a KrCl exilamp in the combined oxidative system {UV/Fe2+/S2O82-} for effective degradation of β-lactam antibiotics.

Mineral Carbonation for Carbon Sequestration: A Case for MCP and MICP

Mineral carbonation is a prominent method for carbon sequestration. Atmospheric carbon dioxide (CO2) is trapped as mineral carbonate precipitates, which are geochemically, geologically, and thermodynamically stable. Carbonate rocks can originate from biogenic or abiogenic origin, whereby the former refers to the breakdown of biofragments and the latter precipitation out of water. Carbonates can also be formed through biologically controlled mechanisms (BCMs), biologically mediated mechanisms (BMMs), and biologically induced mechanisms (BIMs). Microbial carbonate precipitation (MCP) is a BMM occurring through the interaction of organics (extracellular polymeric substances (EPS), cell wall, etc.) and soluble cations facilitating indirect precipitation of carbonate minerals. Microbially induced carbonate precipitation (MICP) is a BIM occurring via different metabolic pathways. Enzyme-driven pathways (carbonic anhydrase (CA) and/or urease), specifically, are promising for the high conversion to calcium carbonate (CaCO3) precipitation, trapping large quantities of gaseous CO2. These carbonate precipitates can trap CO2 via mineral trapping, solubility trapping, and formation trapping and aid in CO2 leakage reduction in geologic carbon sequestration. Additional experimental research is required to assess the feasibility of MICP for carbon sequestration at large scale for long-term stability of precipitates. Laboratory-scale evaluation can provide preliminary data on preferable metabolic pathways for different materials and their capacity for carbonate precipitation via atmospheric CO2 versus injected CO2.

Petrographic Analysis of Mafic and Ultramafic Rocks in Northern Thailand: Implications for CO2 Mineralization and Enhanced Rock Weathering Approach

Mafic and ultramafic rocks have become a promising approach for atmospheric carbon dioxide (CO2) reduction, as they are major sources of CO2-reactive minerals, i.e., olivine, pyroxene, plagioclase, and serpentine. The minerals potentially sequester CO2 by turning it into a stable solid phase through carbon mineralization in the rock weathering process. However, detailed descriptions and evaluations of the target formations are lacking. This study investigates the mineralogical composition and microtextural characteristics of representative mafic and ultramafic rocks observed in northern Thailand, using a petrographic analysis. The results show that variations in CO2-reactive mineral assemblages of rocks certainly affect their theoretical CO2 uptake potential. Ultramafic rocks tend to sequester larger amounts of CO2 than mafic rocks. The microtextural observation reveals the mineral size ranges of 0.05–5 mm for ultramafic and mafic intrusive rocks and 0.01–2 mm for mafic extrusive and metamorphosed rocks. Reducing the rock size to be equal to the average size of the reactive minerals could be considered one of the practical designs in enhanced rock weathering activities. Understanding the mineralogical and textural characteristics of target rocks thus plays a crucial role in further georesource exploration and engineering designs, supporting climate action strategies on various scales.

Transport of particulate mercury along the reservoir- downstream - estuary continuum during the water-sediment regulation scheme period of Yellow River in 2018.

Transport of particulate mercury along the reservoir- downstream - estuary continuum during the water-sediment regulation scheme period of Yellow River in 2018.

Carbon Sequestration of Alkaline Olivine Basalt in the Yangtze River Basin of China: Carbonation Mechanism and CO2 Storage Potential

Summary As the largest carbon-emitting region in China, the feasibility of basalt geological carbon sequestration in the Yangtze River Basin is an important way to address regional carbon neutrality. In this study, we carried out carbonation reactions in a closed experimental setup using synthetic formation water to test the basalt-CO2 interaction by using the alkaline olivine basalt from the Yangtze River Basin of China. We used scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and inductively coupled plasma mass spectrometry (ICP-MS) to characterize the solid and liquid phases before and after the reaction and to obtain the carbonation degree. Comparing the mineral characteristics with those of the unreacted samples, the results consistently show a reduction in silicate minerals and an increase in carbonate minerals, regardless of reaction conditions or time. The experimental results show that the CO2 consumption rate during the carbon sequestration process of basalt in the Yangtze River Basin has a characteristic time threshold, and after 180 days of reaction, the rate tends to stabilize under all reaction conditions. In addition, the percentage of CO2 consumed under high-pressure conditions was significantly greater than under low-pressure conditions. Considering the limitations of traditional potential calculation methods, we propose a new calculation method for predicting the CO2 sequestration potential of basalt based on the analysis and summary of changes in mineral content after the reaction. According to this calculation, the potential total CO2 reserves of Cenozoic and Mesozoic alkaline basalt distributed in southeastern China are estimated to be 2.117 billion tons of CO2, approximately equivalent to China’s carbon emissions for 2 years, providing support for the feasibility of basalt carbon sequestration in China. While these findings support the potential of basalt carbon sequestration in the region, further research is needed to validate these estimates under field conditions, considering the differences in reactive surface area between powdered and in-situ basalts.

Stabilization of red mud using mineral carbonation

Stabilization of red mud using mineral carbonation