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Yb (III) shows complex behavior of coordination dissolution and precipitation in carbonate solutions, but the properties of C O 3 2 − coordination and hydration to Yb (III) in the solution have not been explicated. In this work, the dissolution rule of Yb (III) with C O 3 2 − concentration has been studied. The radial distribution function and the coordination number of C O 3 2 − and H 2 O to Yb (III) were calculated by molecular dynamics simulation, and the complex ion form of Yb was obtained. The ultraviolet–visible spectrum and the ionic structures of Yb (III) complex ions were geometrically optimized and calculated by using density functional theory. Then, the experimental ultraviolet–visible spectra and density functional theory results were combined to verify the molecular dynamics calculations. The results indicate that Yb (III) undergoes precipitation in low-concentration carbonate solution, but, in high-concentration carbonate solution, Yb (III)'s carbonates will undergo dissolution. The main reason for the dissolution of Yb (III)'s carbonates is the coordination effect of C O 3 2 − on Yb (III); the coordination of carbonate on Yb (III) occurs with a C O 3 2 − concentration range of 0.4~2.0 mol· L − 1 . Yb (III) mainly exhibits [ Y b · 9 H 2 O ] 3 + hydrated form in the aqueous solution, while, in the carbonate solution, [ Y b · 9 H 2 O ] 3 + is converted into [ Y b (C O 3 ) 2 · 5 H 2 O ] − complex. [ Y b (C O 3 ) 2 · 5 H 2 O ] −  complex is the main ionic form in high-concentration carbonate solutions. The analysis method in this work provides guidance for understanding the coordination and hydration characteristics of oxyacid radicals to rare earth elements. [ABSTRACT FROM AUTHOR]

Increased use and improved methodology of carbonate clumped isotope thermometry has greatly enhanced our ability to interrogate a suite of Earth-system processes. However, interlaboratory discrepancies in quantifying carbonate clumped isotope (Δ47) measurements persist, and their specific sources remain unclear. To address interlaboratory differences, we first provide consensus values from the clumped isotope community for four carbonate standards relative to heated and equilibrated gases with 1,819 individual analyses from 10 laboratories. Then we analyzed the four carbonate standards along with three additional standards, spanning a broad range of δ47 and Δ47 values, for a total of 5,329 analyses on 25 individual mass spectrometers from 22 different laboratories. Treating three of the materials as known standards and the other four as unknowns, we find that the use of carbonate reference materials is a robust method for standardization that yields interlaboratory discrepancies entirely consistent with intralaboratory analytical uncertainties. Carbonate reference materials, along with measurement and data processing practices described herein, provide the carbonate clumped isotope community with a robust approach to achieve interlaboratory agreement as we continue to use and improve this powerful geochemical tool. We propose that carbonate clumped isotope data normalized to the carbonate reference materials described in this publication should be reported as Δ47 (I-CDES) values for Intercarb-Carbon Dioxide Equilibrium Scale.

Highlights A biochar-bacteria (2B) system was constructed based on MICP. Cd was immobilized (23.6–45.8%) in the 2B system. 2B system facilitated the formation of insoluble otavite (CdCO3). Bacteria carrying the ureC gene were boosted to lower the Cd mobility. Graphical Abstract

It is difficult to separate fluorene and phenanthene by conventional separation method owing to their similar properties. The reaction-separation coupling technique was adopted to solve the problem, in which fluorene is first converted into 9-fluorenylmethanol. The factors affecting the yield and selectivity of 9-fluorenylmethanol by one-step synthesis with potassium carbonate as catalyst were investigated for the separation of phenanthrene from anthracene residue further. The results showed that with DMSO+10% ethanol as solvent, n(fluorene)∶n(formaldehyde)∶n(potassium carbonate)=1∶1∶0.2, and reaction at 13 ℃ for 15 min, the yield of 9-fluorenemethanol is about 25% and the selectivity is higher than 84%. Ethanol can inhibit the formation of 9-fluorenyl anion, and the inorganic salt affects the mass transfer and slows down the dehydration reaction. Using the mixture of fluorene and phenanthrene with mass ratio of 1∶4 as raw material, the yield and purity of phenanthrene reaches 97.6% and 93.2% after five reaction-separation cycles, respectively; the total yield of 9-fluorenylmethanol is 66.5%, and the average purity is 95.0%.

[Carbonatotetraamminecobalt(III)] permanganate monohydrate was synthesized first in the metathesis reaction of [Co(NH3)4CO3]NO3 and NaMnO4 in aqueous solution. Its thermal dehydration at 100 °C resulted in phase-pure [Co(NH3)4CO3]MnO4 (compound 1). Compounds 1 and 2 (i.e., the hydrated form) were studied with IR, far-IR, and low-temperature Raman spectroscopies, and their vibrational modes were assigned. The lattice parameters were determined by powder X-ray diffraction (PXRD) and single crystal X-ray diffraction (SXRD) methods for the triclinic and orthorhombic compounds 1 and 2, respectively. The detailed structure of compound 2 was determined, and the role of hydrogen bonds in the structural motifs was clarified. UV studies on compounds 1 and 2 showed the distortion of the octahedral geometry of the complex cation during dehydration because of the partial loss of the hydrogen bonds between the crystal water and the ligands of the complex cation. The thermal decomposition consists of a solid phase quasi-intramolecular redox reaction between the ammonia ligands and permanganate anions with the formation of ammonia oxidation products (H2O, NO, N2O, and CO2). The solid phase reaction product is amorphous cobalt manganese oxide containing ammonium, carbonate (and nitrate) anions. The temperature-controlled thermal decomposition of compound 2 in toluene at 110 °C showed that one of the decomposition intermediates is ammonium nitrate. The decomposition intermediates are transformed into Co1.5Mn1.5O4 spinel with MnCo2O4 structure upon further heating. Solid compound 2 gave the spinel at 500 °C both in an inert and air atmosphere, whereas the sample pre-treated in toluene at 110 °C without and with the removal of ammonium nitrate by aqueous washing, gave the spinel already at 300 and 400 °C, respectively. The molten NH4NO3 is a medium to start spinel crystallization, but its decomposition stops further crystal growth of the spinel phase. By this procedure, the particle size of the spinel product as low as ~4.0 nm could be achieved for the treatments at 300 and 400 °C, and it increased only to 5.7 nm at 500 °C. The nano-sized mixed cobalt manganese oxides are potential candidates as Fischer-Tropsch catalysts.

Variations in solar insolation caused by changes in the Earth’s orbit—specifically its eccentricity, obliquity, and precession—can leave discernible marks on the geologic record. Astrochronology leverages these markers to establish a direct connection between chronological measurements and different facets of climate change as recorded in marine sediments. This approach offers a unique window into the Earth’s climate system and the construction of high-resolution, continuous time scales. Our study involves comprehensive bulk carbonate analyses of 390 discrete samples from core SCS1, which was retrieved from the deep-sea floor of the northern South China Sea. By utilizing carbonate stratigraphic data, we have developed a carbonate stratigraphic age model. This was achieved by aligning the carbonate sequence from core SCS1 with the established carbonate standard stratigraphic time scale of the South China Sea. Subsequently, we construct an astronomically tuned time scale based on this age model. Our findings indicate that sediment records in this core have been predominantly influenced by a 20,000-year cycle (precession cycle) throughout the Late Pleistocene. We have developed an astronomical time scale extending back approximately 110,000 years from the present, with a resolution of 280 years, by tuning the carbonate record to the precession curve. Time-domain spectral analysis of the tuned carbonate time series, alongside the consistent comparability of the early Holocene low-carbonate event (11–8 kyr), underscores the reliability of our astronomical time scale. Our age model exposes intricate variations in carbonate deposition, epitomizing a typical “Pacific-type” carbonate cycle. Previous research has illustrated that precession forcing predominantly influences productivity changes in the South China Sea. The pronounced precession-related cycle observed in our record suggests that changes in productivity significantly impact carbonate content in the area under study. Furthermore, the clear precession period identified in the carbonate record of core SCS1 reflects the response of low-latitude processes to orbital parameters, implying that carbonate deposition and preservation in core SCS1 are chiefly influenced by the interplay between the Intertropical Convergence Zone (ITCZ) and the monsoon system within the precession band. Our astronomical time scale is poised to enhance paleoceanographic, paleoclimatic, and correlation studies further. Additionally, the independent evidence we provide for using proxy records for astronomical age calibration of marine sediments lends additional support to similar methods of astronomical tuning.

Quantum dots (QDs) have captured the attention of the scientific community due to their unique optical and electronic properties, leading to extensive research for different applications. They have also been employed as sensors for ionic species owing to their sensing properties. Detecting anionic species in an aqueous medium is a challenge because the polar nature of water weakens the interactions between sensors and ions. The anions bicarbonate (HCO3−), carbonate (CO32−), sulfate (SO42−), and bisulfate (HSO4−) play a crucial role in various physiological, environmental, and industrial processes, influencing the regulation of biological fluids, ocean acidification, and corrosion processes. Therefore, it is necessary to develop approaches capable of detecting these anions with high sensitivity. This study utilized CdTe QDs stabilized with cysteamine (CdTe-CYA) as a fluorescent sensor for these anions. The QDs exhibited favorable optical properties and high photostability. The results revealed a gradual increase in the QDs’ emission intensity with successive anion additions, indicating the sensitivity of CdTe-CYA to the anions. The sensor also exhibited selectivity toward the target ions, with good limits of detection (LODs) and quantification (LOQs). Thus, CdTe-CYA QDs show potential as fluorescent sensors for monitoring the target anions in water sources.

Mesozoic strata record numerous negative and positive carbon isotope excursions (CIEs). The Middle Jurassic records a negative ~0.5 ‰ CIE at the Aalenian-Bajocian boundary followed by a positive ~1.5 ‰ CIE covering the entire early Bajocian. Although these CIEs are recorded in northern and southwestern Tethys and may reflect perturbations of the global carbon cycle, they remain poorly investigated. In this study, we present new geochemical and sedimentological data from the Chaudon-Norante section in France and Murtinheira section in Portugal to better constrain the origin of the lower Bajocian CIEs. Associated with the previously published carbon isotopic composition of bulk carbonate (δ13Cbulk carbonate) we provide new carbon isotopic composition of bulk organic matter (δ13Corg) records, as well as total phosphorus content, phosphorus accumulation rates (AR), and CaCO3 and organic matter data. In contrast with previous interpretations, our results show no evidence of a carbonate production crisis during the early Bajocian. A slight increase in siliciclastic and phosphorus AR would argue for oceanic fertilization but without a parallel increase in organic matter AR. The obtained stratigraphic δ13Cbulk carbonate vs. δ13Corg patterns are distinctive and mimic previous box modeling results simulating an increase in productivity forced by higher phosphorus rates from riverine and weathered-carbon input burial. The subsequent organic carbon burial produced counter-greenhouse conditions, which in turn produced a cooling by CO2 uptake. Our results indicate that the lower Bajocian event shows several similarities with the late Valanginian positive CIE (also known as the Weissert event). An accurate comparison of both events may help for a better understanding of the origin and consequence of such carbon cycle perturbations.

Large concentrically laminated carbonate grains (here referred to as pisoids) have been observed sporadically throughout the geological record and in modern environments. Explanations for how these grains form have varied widely in different settings, although microbial effects are often involved. In Ore Lake, a ~1 km2 flow-through lake in southeast Michigan, one to four centimeter oblong calcite pisoids are observed in both lake bottom shallows and mounded as a small spit near the primary outflow. In section mm-scale light and more porous along with and dark and more dense concentric laminations are apparent. Here we use field observations, petrography, water chemistry, and stable isotopes to understand their formation. Measurements of pisoid calcite δ18O and lake water δ18O indicate that precipitation occurs in waters between roughly 19 – 28°C. These warm temperatures imply that pisoid growth happens almost entirely within the summer, contrary to prior work that suggested wintertime precipitation was important. Pisoid δ18O values largely overlap with coexisting lake bivalve values, suggesting that pisoid precipitation is in equilibrium. In contrast, pisoid δ13C is as much as 8 ‰ more positive than bivalve δ13C due to photosynthetic effects. We propose that the laminations in these pisoids arise from different rates of formation within the warm months, rather than large seasonal differences. A decline in lake alkalinity beginning in late spring likely coincides with more rapid growth, with slower growth mediated by cyanobacteria continuing through the summer. This range of observations enables the use of Ore Lake as a potential model for understanding pisoid formation throughout the geological record.

Oil recovery could be impacted by the relation between vertical permeability (Kv) and horizontal permeability (Kh) (Kv/Kh). 4816 plugs that have been getting hold of 18 wells of Mishrif formation in the West Qurna oilfield were used. Kv/Kh data provided some scatter, but the mean is ~1. Kv/Kh =1 was used for the Petrel model before upscaling according to the heterogeneity of each layer. Kv/Kh values for Mishrif Formation in West Qurna Oilfield are 0.8 for relatively homogeneous, 0.4 for heterogeneous rock, and 0.1 for cap rocks (CRII). Eclipse TM was used for reservoir simulation. PVT and SCAL data enhanced the simulation process. The results showed that the reduction of Kv/Kh to 0.9 for the mA unit would reduce the recovery factor (RF) by ~0.9% and continuing lowering would reduce RF more, while the same reduction would reduce RF by ~1% in the mB1 unit. The reduction would be 0.8, which increases RF by ~0.5% for the mB2U unit, while there was no effect on RF in the CRII unit whatever the reductions.

The KDR (karst development rate) of rocks and their PCR(porosity of carbonate rocks) are common research topics in Jinfo Mountain. The use of traditional carbonate research methods (TCRMs) for karst studies has been shown to be costly and time-consuming. Therefore, this study attempted to find a new, reliable, low-cost, and time-saving method for karst research. The Jinfo Mountain area is a typical carbonate rock area that is suitable for karst research. In this study, many images of rock samples from the Jinfo Mountain were obtained using rock-polarizing microscopes, which provided a good basis for the karst study of Jinfo Mountain. Furthermore, in this study, image analysis technology was used to find the karst development rate of rocks and their porosity. To ensure the accuracy of these research results, we compared the research results obtained using the image analysis techniques with those obtained using TCRM. The comparison showed that the image analysis technology is a feasible research techniques for studying karst in the Jinfo Mountain area. Furthermore, it has good reference significance for other karst study outside the Jinfo Mountain area.

Carbonate reservoirs exhibit complex pore structure, which significantly affects the elastic properties and seismic response, as well as the prediction of physical parameters. As one of the main factors impacting fluid prediction, pore structure parameter directly involves in few inversion methods. In order to directly predict pore structure parameter in inversion, a novel quantitative reflection coefficient formula is proposed, that integrate Russell's poroelasticity theory with Sun's petrophysical model. This formula separates fluid bulk modulus from porosity and pore structure parameter, allowing for accurate determination of pore-fluid distribution through Bayesian framework. Both theoretical model analysis and multi-component digital core experiments of carbonates validate the importance of pore structure parameter on fluid identification. The practical application of carbonate reservoirs in Sichuan Basin demonstrates that the proposed fluid factor, eliminating the prediction illusion caused by heterogeneity in porosity and pore structure parameter within strata, provides more precise and reliable predictions compared to the Russell fluid factor. Furthermore, the similarity between the Russell fluid factor obtained directly from the Russell approximation and the Russell fluid factor calculated indirectly from the proposed method confirms the stability and accuracy of the new reflection coefficient formula.

Carbon capture and storage in underground formations might be considered as a relevant technology to curb anthropogenic climate gas emissions. However, carbon dioxide ( CO 2 ) injection can lead to severe rock-fluid interactions depending on the thermodynamic conditions, rock and fluids composition. The progressive dissolution of CO 2 in the formation brine results in mineral dissolution/precipitation processes that may drastically change the properties of the reservoir. This study is an attempt to get a deeper understanding of the dissolution/precipitation processes in a heterogeneous limestone at microscopic and macroscopic levels by a synergy between Isothermal Titration Calorimetry (ITC) and core flooding experiments with in-situ imaging to quantify uneven displacement fronts and understand the influence of reactions on a larger scale. Rock-fluid and fluid-fluid interactions, evaluated by ITC experiments, indicate that the carbonate dissolution is unfavorable with respect to enthalpy change but thermodynamically favorable with respect to entropy change (cations and hydrogen carbonate increase in the brine). Core flooding experiments with in-situ imaging by PET/CT show that complex pore structures cause a variation in the availability and ratio of the reactive fluid throughout the porous medium, hence, non-uniform dissolution was confirmed at core scale. The synergy between microcalorimetry and core flooding provides relevant insights into the dissolution of heterogeneous carbonate rocks at both microscopic and macroscopic scales. [ABSTRACT FROM AUTHOR]

Ikaite (CaCO 3 ·6H 2 O) and monohydrocalcite (CaCO 3 ·H 2 O; MHC) are hydrated carbonates that form at frigid (<9 °C) temperatures. During gradual heating and dehydration, the more thermodynamically stable anhydrous calcite replaces and pseudomorphs ikaite and MHC. Previously, ikaite pseudomorphs have been identified in the sedimentary record by characteristic replacive macro- and microtextures and interpreted as evidence for near-freezing marine paleotemperatures. Prior to this study, we lacked an understanding of isotopic exchange during mineral dehydration necessary to interpret isotopic compositions of such fabrics. Specifically, do the stable isotopic compositions of ikaite pseudomorphs preserve the primary environmental signal, or are they altered during mineral transformation? Through heating experiments of MHC from Ikka Fjord, we find that δ18O CARB and Δ 47 decreased, while δ13C CARB remained nearly unchanged during progressive dehydration. An oxygen isotopic exchange model fitted to experimental data suggests that the isotopic changes reflected partial re-equilibration of δ18O CARB and Δ 47 towards the new diagenetic conditions due to oxygen equilibrium exchange between CO 3 2− and H 2 O within the MHC lattice. However, this process never reaches full equilibrium, an effect we argue reflects the fact that structural H 2 O escapes the solid carbonate structure faster than isotopic exchange can reach equilibrium. In addition, labelled water experiments demonstrated that oxygen isotopic exchange also occurs with secondary external waters during dehydration. We apply this new framework to interpret the isotopic compositions of Pleistocene ikaite pseudomorphs from Mono Lake (CA, USA) high-stand deposits, which have undergone subaerial dehydration. Specifically, dehydration diagenetic overprinting of Δ 47 similar to the results of our controlled heating experiments can explain the warm temperatures, 6–26 °C, recorded by ikaite pseudomorphs and the higher δ18O CARB recorded by ikaite pseudomorph compared to other Pleistocene Mono Lake calcite tufas. We show that Mono Lake ikaite pseudomorph tufa isotopic data can be explained in a model scenario where approximately coeval precursor ikaite and other calcite tufas in Pleistocene Mono Lake formed from similar fluid compositions but at different water temperatures, likely related to changing seasons. In summary, we show that the isotopic composition of ikaite and MHC pseudomorphs can be used for paleoclimate reconstruction of water temperature, δ18O CARB , δ18O fluid , and δ13C CARB when considering dehydration diagenetic effects. [ABSTRACT FROM AUTHOR]

The hydrocarbon source rocks of the marine carbonates of the Ordovician Majiagou Formation in the Ordos Basin are generally in the high-overmature stage and are, therefore, not suitable for hydrocarbon thermal simulation experiments. Their hydrocarbon generation potential and hydrocarbon generation characteristics are not clearly understood. Meanwhile, Nordic Cambrian carbonates are similar in lithology, parent material type, and sedimentary age, and are in the low evolution stage, which is suitable for hydrocarbon thermal simulation experiments. Therefore, in this study, we selected the Nordic carbonates for the gold tube thermal simulation experiment to analyze the content and geochemical characteristics of the thermal simulation products. The experimental results are also compared and analyzed with the characteristics of thermal simulation products of Pingliang Formation mud shale (contemporaneous with the Majiagou Formation) and Shanxi Formation coal (in the upper part of the Majiagou Formation), which are similar to the Majiagou Formation in the Ordos Basin. The results showed that the Nordic carbonate has different hydrocarbon production characteristics from the mud shale of the Pingliang Formation of the same parent material type, and although the hydrocarbon production yields of the two are not very different, the carbonate still produces methane at 600 °C. The hydrocarbon production yield of the Nordic carbonates is almost equivalent to that of type-II2 kerogen, indicating that the hydrocarbon production yield is not related to lithology and only to the organic matter type; however, the Nordic carbonate can produce a large amount of H2S. The alkane carbon isotope changes are mainly controlled by the degree of thermal evolution, showing gradual heaviness with increasing temperature. No carbon isotope sequence reversal occurred during the thermal simulation, and its distribution range is roughly the same as that of the alkane carbon isotope composition of the mud shale of the Pingliang Formation. The ethane carbon isotope composition is as heavy as −21.2‰ at the high-temperature stage, showing similar coal-type gas characteristics. The addition of calcium sulphate (CaSO4) causes the TSR reaction to occur, which has a significant impact on the methane content under high maturity conditions, reducing its content by more than 50% at 600 °C. However, the addition of CaSO4 increases the yield of heavy hydrocarbon gases, such as ethane, and promotes the production of C6-14 hydrocarbons and C14+ hydrocarbons at high-temperature stages, and the addition of CaSO4 substantially increases the yield of H2, CO2, and H2S. The thermal simulation results have implications for the hydrocarbon formation mechanism of the early Paleozoic marine carbonate formation system in the stacked basins of the Ordos Basin and the Tarim Basin in China. [ABSTRACT FROM AUTHOR]

The quantitative and objective characterization of dissolution intensity in fossil planktonic foraminiferal shells could be used to reconstruct past changes in bottom water carbonate ion concentration. Among proxies measuring the degree of dissolution of planktonic foraminiferal shells, X‐ray micro‐Computed Tomography (CT) based characterization of apparent shell density appears to have good potential to facilitate quantitative reconstruction of carbonate chemistry. However, unlike the well‐established benthic foraminiferal B/Ca ratio‐based proxy, only a regional calibration of the CT‐based proxy exists based on a limited number of data points covering mainly low‐saturation state waters. Here we determined by CT‐based proxy the shell dissolution intensity of planktonic foraminifera Globigerina bulloides, Globorotalia inflata, Globigerinoides ruber, and Trilobatus sacculifer from a collection of core top samples in the Southern Atlantic covering higher saturation states and assessed the reliability of CT‐based proxy. We observed that the CT‐based proxy is generally controlled by deep‐water Δ[CO32– ${{\mathrm{C}\mathrm{O}}_{3}}^{2\mbox{--}}$] like the B/Ca proxy, but its effective range of Δ[CO32– ${{\mathrm{C}\mathrm{O}}_{3}}^{2\mbox{--}}$] is between −20 and 10 µmolkg−1. In this range, the CT‐based proxy appears directly and strongly related to deep‐water Δ[CO32– ${{\mathrm{C}\mathrm{O}}_{3}}^{2\mbox{--}}$], whereas we note that in some settings, there appears to be a secondary influence on B/Ca which we suggest may be due to elevated alkalinity from carbonate dissolution in sediments. On the other hand, the CT‐based proxy is affected by supralysoclinal dissolution in areas with high productivity. Like the B/Ca proxy, the CT‐based proxy requires species‐specific calibration, but the effect of species‐specific shell difference in susceptibility to dissolution on the proxy is small. Key Points: Planktonic foraminiferal shell dissolution intensity was determined by Computed Tomography (CT)‐based proxy using core top samples in the Southern Atlantic OceanThe characteristics and reliability of CT‐based proxy were compared with conventional proxyThe CT‐based proxy is available for reconstructing deep seawater carbonate ion concentration under the appropriate condition [ABSTRACT FROM AUTHOR]

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Methane seeps are typified by the formation of authigenic carbonates, many of which exhibit corrosion surfaces and secondary porosity believed to be caused by microbial carbonate dissolution. Aerobic methane oxidation and sulfur oxidation are two processes capable of inducing carbonate corrosion at methane seeps. Although the potential of aerobic methanotrophy to dissolve carbonate was confirmed in laboratory experiments, this process has not been studied in the environment to date. Here, we report on a carbonate corrosion experiment carried out in the REGAB Pockmark, Gabon‐Congo‐Angola passive margin, in which marble cubes were deployed for 2.5 years at two sites (CAB‐B and CAB‐C) with apparent active methane seepage and one site (CAB‐D) without methane seepage. Marble cubes exposed to active seepage (experiment CAB‐C) were found to be affected by a new type of microbioerosion. Based on 16S rRNA gene analysis, the biofilms adhering to the bioeroded marble mostly consisted of aerobic methanotrophic bacteria, predominantly belonging to the uncultured Hyd24‐01 clade. The presence of abundant 13C‐depleted lipid biomarkers including fatty acids (n‐C16:1ω8c, n‐C18:1ω8c, n‐C16:1ω5t), various 4‐mono‐ and 4,4‐dimethyl sterols, and diplopterol agrees with the dominance of aerobic methanotrophs in the CAB‐C biofilms. Among the lipids of aerobic methanotrophs, the uncommon 4α‐methylcholest‐8(14)‐en‐3β,25‐diol is interpreted to be a specific biomarker for the Hyd24‐01 clade. The combination of textural, genetic, and organic geochemical evidence suggests that aerobic methanotrophs are the main drivers of carbonate dissolution observed in the CAB‐C experiment at the REGAB pockmark. [ABSTRACT FROM AUTHOR]

The Ordovician reservoirs in the Tahe oilfield are dominated by fractured-vuggy carbonate reservoirs, of which fault-karst reservoirs are a hot topic in recent years. Fault-karst reservoirs feature high production, large burial depth, and strong heterogeneity under the control of faulting and karstification. Based on geological, logging, and seismic data, this study classified the Ordovician fault-karst reservoirs in the Yuejin block of the Tahe oilfield into three types, namely karst-cave, dissolved-vug, and fractured types, and established the integrated identification criteria of the three types of reservoirs. This study characterized karst caves, dissolved vugs, and multi-scale faults through seismic wave impedance inversion and frequency-domain detection of multi-scale faults. 3D geological models of different types of reservoirs were built using the combined deterministic and stochastic methods and characterized the spatial distribution of multi-scale faults, karst caves, dissolved vugs, and physical property parameters of reservoir. This study established the method for the geological modeling of fault-karst reservoirs, achieved the quantitative characterization and revealed the heterogeneity of fault-karst reservoirs. The karst-cave and dissolved-vug types are high in porosity and act as reservoirs, while the fractured type is high in permeability and act as flow pathway. This study lays the foundation for the development index prediction, well emplacement, and efficient development of the fault-karst carbonate reservoirs. [ABSTRACT FROM AUTHOR]

Chalks are non-clastic type of carbonate sedimentary rocks. Any applied axial load would lead to a deformation of the sediments by the depletion of the pore fluids. This results in compaction which is a process in which the compressive strength of the rock is exceeded and plastic deformation occurs, resulting in irreversible reduction of porosity. In this work, a time-dependent deformation in chalks known as creep is presented. A reduction from 30 MPa to 5 MPa pore pressure in 100 minutes (0.25 MPa/min) was termed rapid loading. The same pressure was depleted for about 8333 minutes (0.003 MPa/min) and regarded as a slow loading. At the lower value of 5 MPa, the samples were left to deform under constant stress for some time. It was observed that when loaded rapidly, the deformation accumulated at the creep stage was higher; observed mainly at the transient creep phase, compared to when loaded slowly. The results of the experiments show that other parameters such as uniaxial compaction modulus both in the elastic and plastic regions, creep strain and creep rate are all loadingrate dependent. Hence, it could be inferred that if creep is porosity dependent, then it is load-rate dependent. Also, creep rate is highest for rapid loading and lowest for slow loading, while values for intermediate loading were in-between. The loading rate has to be widely different for variations in accumulated strains to differ with time. [ABSTRACT FROM AUTHOR]

Cerium is the most sought-after rare earth element (REE) for application in high-tech electronic devices and versatile nanomaterials. In this research, biomass-free spent culture media of Aspergillus niger and Neurospora crassa containing precipitant ligands (oxalate, carbonate) were investigated for their potential application in biorecovery of Ce from solution. Precipitation occurred after Ce3+ was mixed with biomass-free spent culture media and >99% Ce was recovered from media of both organisms. SEM showed that biogenic crystals with distinctive morphologies were formed in the biomass-free spent medium of A. niger. Irregularly-shaped nanoparticles with varying sizes ranging from 0.5 to 2 μm and amorphous biominerals were formed after mixing the carbonate-laden N. crassa supernatant, resulting from ureolysis of supplied urea, with Ce3+. Both biominerals contained Ce as the sole metal, and X-ray diffraction (XRD) and thermogravimetric analyses identified the biominerals resulting from the biomass-free A. niger and N. crassa spent media as cerium oxalate decahydrate [Ce 2 (C 2 O 4) 3 ·10H 2 O] and cerium carbonate [Ce 2 (CO 3) 3 ·8H 2 O], respectively. Thermal decomposition experiments showed that the biogenic Ce oxalates and carbonates could be subsequently transformed into ceria (CeO 2). FTIR confirmed that both amorphous and nanoscale Ce carbonates contained carbonate (CO 3 2−) groups. FTIR-multivariate analysis could classify the biominerals into three groups according to different Ce concentrations and showed that Ce carbonate biominerals of higher purity were produced when precipitated at higher Ce3+ concentrations. This work provides new understanding of fungal biotransformations of soluble REE species and their biorecovery using biomass-free fungal culture systems and indicates the potential of using recovered REE as precursors for the biosynthesis of novel nanomaterials. [Display omitted] • Biomass-free spent fungal media achieved >99% biorecovery of cerium from solution. • Carbonate-laden N. crassa media precipitated Ce carbonate [Ce 2 (CO 3) 3 ·8H 2 O]. • Oxalate-laden A. niger media precipitated Ce oxalate decahydrate [Ce 2 (C 2 O 4) 3 ·10H 2 O]. • Biogenic Ce oxalates and carbonates were thermally transformed into ceria (CeO 2). • Demonstration of REE biorecovery by biomass-free fungal culture systems. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Understanding carbon cycling in blue carbon ecosystems is key to sequestrating more carbon in these ecosystems to mitigate climate change. However, limited information is available on the basic characteristics of publications, research hotspots, research frontiers, and the evolution of topics related to carbon cycling in different blue carbon ecosystems. Here, we conducted bibliometric analysis on carbon cycling in salt marsh, mangrove, and seagrass ecosystems. The results showed that interest in this field has dramatically increased with time, particularly for mangroves. The USA has substantially contributed to the research on all ecosystems. Research hotspots for salt marshes were sedimentation process, carbon sequestration, carbon emissions, lateral carbon exchange, litter decomposition, plant carbon fixation, and carbon sources. In addition, biomass estimation by allometric equations was a hotspot for mangroves, and carbonate cycling and ocean acidification were hotspots for seagrasses. Topics involving energy flow, such as productivity, food webs, and decomposition, were the predominant areas a decade ago. Current research frontiers mainly concentrated on climate change and carbon sequestration for all ecosystems, while methane emission was a common frontier for mangroves and salt marshes. Ecosystem-specific research frontiers included mangrove encroachment for salt marshes, ocean acidification for seagrasses, and aboveground biomass estimation and restoration for mangroves. Future research should expand estimates of lateral carbon exchange and carbonate burial and strengthen the exploration of the impacts of climate change and restoration on blue carbon. Overall, this study provides the research status of carbon cycling in vegetated blue carbon ecosystems, which favors knowledge exchanges for future research. [ABSTRACT FROM AUTHOR]

Ionophore‐based carbonate‐selective sensors have become reliable analytical tools due to their high selectivity and versatility of applications. Nonetheless, successful examples of their implementation in nanoscale devices are yet to be found in the literature. Herein we describe the first attempt to develop carbonate sensors with ionophores using ion‐selective nanoemulsions. Classical chromoionophore‐based sensors were shown to perform poorly upon transfer to the nanoscale. We hypothesize that this is caused by the heightened surface activity of the ion‐ionophore complex. This challenge is overcome by the addition of a positively charged solvatochromic dye X3+ to the aqueous phase instead of the sensing particles. The presence of this dye facilitates transfer of carbonate from the particle surface into the sensor bulk, which is followed by an unexpected change of fluorescence with the emergence of a new peak at longer wavelengths, allowing for a ratiometric signal transduction. We have found that this spectral change originates from dye hyper‐polarization by the charged moiety of carbonate complex with the ionophore, in analogy to earlier work with protamine nanosensors. The dye‐coextraction‐based sensing protocol is shown to be reversible and selective with regard to both anionic and cationic interferences present in the sample and forms the foundation for further mechanistic advances for anion sensing with ionophores. [ABSTRACT FROM AUTHOR]

• We designed a glass vessel for stepwise dissolution experiments. • The apparatus can conduct relatively simple experiments compared to conventional methods. • Using this method, it seems possible to reconstruct the migration history of marine fish relatively easily. Isotopes and trace elements extracted from fish otoliths have been widely used to understand different fish habitats. Otoliths can track the life-long histories of fish habitats and can supplement the information that is often difficult to reconstruct using tagging methods. Due to the advancement of radiocarbon measurement techniques, small quantities can be prepared for this purpose, and radiocarbon can be used to understand the migration history by referring to the variations of radiocarbon in the surface ocean. One major drawback of otolith isotope methods is the length of time it takes to collect samples by milling before each sample can be measured by accelerator mass spectrometry. Sequential acid digestion systems can potentially offer a solution whereby each dissolution step can provide information of otolith growth. Here we designed a glass apparatus that can be used for this purpose. We tested the otoliths from the western Pacific roughy (Hoplostethus japonicus) caught in Suruga Bay off the coast of Japan to see if their otoliths can provide reliable information in reconstructing their life history. The results show radiocarbon concentrations in the otoliths gradually decreased, indicating the habitat depth of analyzed individuals gradually shifted from deep to shallow water demonstrating the promise of this method to understand fish habitats. This is consistent with expected behavior considering the oceanography of the region. Thus, stepwise dissolution using a newly designed glass apparatus, proposed here, can aid marine fish ecological studies using otoliths. [ABSTRACT FROM AUTHOR]

Geothermal energy is a kind of renewable, sustainable and clean energy resource. Geothermal energy is abundant in carbonate reservoirs. However, low matrix permeability limits its exploitation. The supercritical carbon dioxide (SC--CO2) jet fracturing is expected to efficiently stimulate the carbonate geothermal reservoirs and achieve the storage of CO2 simultaneously. In this paper, we established a transient seepage and fluid-thermo-mechanical coupled model to analyze the impact performance of SC-CO2 jet fracturing. The mesh-based parallel code coupling interface was employed to couple the fluid and solid domains by exchanging the data through the mesh interface. The physical properties change of SC-CO2 with temperature were considered in the numerical model. Results showed that SC-CO2 jet fracturing is superior to water-jet fracturing with respect to jetting velocity, particle trajectory and penetrability. Besides, stress distribution on the carbonate rock showed that the tensile and shear failure would more easily occur by SC-CO2 jet than that by water jet. Moreover, pressure and temperature control the jet field and seepage field of SC-CO2 simultaneously. Increasing the jet temperature can effectively enhance the impingement effect and seepage process by decreasing the viscosity and density of SC-CO2. The key findings are expected to provide a theoretical basis and design reference for applying SC-CO2 jet fracturing in carbonate geothermal reservoirs. [ABSTRACT FROM AUTHOR]

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Perseverance explored two geological units on the floor of Jezero Crater over the first 420 Martian days of the Mars2020 mission. These units, the Máaz and Séítah formations, are interpreted to be igneous in origin, with traces of alteration. We report the detection of carbonate phases along the rover traverse based on laser‐induced breakdown spectroscopy (LIBS), infrared reflectance spectroscopy (IRS), and time‐resolved Raman (TRR) spectroscopy by the SuperCam instrument. Carbonates are identified through direct detection of vibrational modes of CO3 functional groups (IRS and TRR), major oxides content, and ratios of C and O signal intensities (LIBS). In Séítah, the carbonates are consistent with magnesite‐siderite solid solutions (Mg# of 0.42–0.70) with low calcium contents (<5 wt.% CaO). They are detected together with olivine in IRS and TRR spectra. LIBS and IRS also indicate a spatial association of the carbonates with clays. Carbonates in Máaz are detected in fewer points, as: (a) siderite (Mg# as low as 0.03); (b) carbonate‐containing coatings, enriched in Mg (Mg# ∼0.82) and spatially associated with different salts. Overall, using conservative criteria, carbonate detections are rare in LIBS (∼30/2,000 points), IRS (∼15/2,000 points), and TRR (1/150 points) data. This is best explained by (a) a low carbonate content overall, (b) small carbonate grains mixed with other phases, (c) intrinsic complexity of in situ measurements. This is consistent with orbital observations of Jezero crater, and similar to compositions of carbonates previously reported in Martian meteorites. This suggests a limited carbonation of Jezero rocks by locally equilibrated fluids. Plain Language Summary: Carbonates are mineral phases that generally form by alteration of primary, magmatic minerals. This alteration process may occur under a variety of environmental conditions, which affect the resulting carbonate phase: its abundance, composition, spatial distribution and the mineral phases it is associated with. Consequently, carbonates keep track of the environmental conditions under which they formed, and in particular, the amount of CO2 and liquid water involved in their formation. Understanding the history of both water and CO2 on Mars is critical to better understand the evolution of the red planet and its atmosphere, but also the origin of the water on Earth, and possibly the origin of life. Since the beginning of the Mars2020 mission in Jezero Crater, the SuperCam instrument has analyzed more than 200 rocks of the crater floor, and detected carbonates along Perseverance's traverse. Carbonates are found in low amounts, and are therefore complex to identify; we use SuperCam's combination of investigation techniques and a specifically developed methodology to strengthen the identification of carbonate phases and their characterization. Even though Jezero crater hosted a lake billions of years ago, the detected carbonates appear to have formed in smaller amounts of water, after the lake had disappeared. Key Points: Carbonates are detected along Perseverance's traverse in Jezero Crater with SuperCam using laser‐induced breakdown spectroscopy, IR and Raman spectroscopyCarbonate abundance is low overall, consistent with the weak carbonate signatures observed from orbit in the explored unitsThe detected carbonates have variable compositions within the magnesite‐siderite series, and likely reflect multiple alteration episodes [ABSTRACT FROM AUTHOR]

Anti-resorptive and anabolic treatments can be used sequentially to treat osteoporosis, but their effects on bone composition are incompletely understood. Osteocytes may influence bone tissue composition with sequential therapies because bisphosphonates diffuse into the canalicular network and anabolic treatments increase osteocyte lacunar size. Cortical bone composition of osteopenic, ovariectomized (OVX) rats was compared to that of Sham-operated rats and OVX rats given monotherapy or sequential regimens of single approved anti-osteoporosis medications. Adult female Sprague-Dawley rats were OVX (N = 37) or Sham-OVXd (N = 6). After 2 months, seven groups of OVX rats were given three consecutive 3-month periods of treatment with vehicle (V), h-PTH (1-34) (P), alendronate (A), or raloxifene (R), using the following orders: VVV, PVV, RRR, RPR, AAA, AVA, and APA. Compositional properties around osteocyte lacunae of the left tibial cortex were assessed from Raman spectra in perilacunar and non-perilacunar bone matrix regions. Sequential treatments involving parathyroid hormone (PTH) caused lower mean collagen maturity relative to monotherapies. Mean mineral:matrix ratio was 2.2% greater, mean collagen maturity was 1.4% greater, and mean carbonate:phosphate ratio was 2.2% lower in the perilacunar than in the non-perilacunar bone matrix region (all P

Abstract In the early stages of exploration, with only a limited amount of data available, it is difficult to evaluate a reservoir and optimize the sequence of the development plan. The score system is often used to rank the reservoir based on multidisciplinary factors that combine geology, production, and economics. However, current methods that are widely employed to classify the reservoir, such as analogy or single parameter, are qualitative or inaccurate, especially for carbonate gas reservoirs with complex geological conditions. In this study, we developed a score system using a data-driven approach to rank carbonate gas reservoirs in the Sichuan Basin. We developed two approaches, expert scoring and the random forest, to rank the quality of the reservoir, which agreed well with the field development plan. The expert scoring approach, which is highly dependent on the experience of experts in this area, is more suitable for reservoirs with limited data available, especially in the early exploration stage. The random forest model, which is more robust and able to reduce uncertainty from experience, is more suitable for developed areas with sufficient data. The developed score system can help rank new resource recovery and optimize the development plan in the Sichuan Basin.

Cryogenic cave carbonates have been described from several formerly or presently glaciated karst caves. In most of these occurrences, they precipitated as loose grains or aggregates with various morphologies and sizes. Here, we report on a new speleothem type (cryogenic ridges) identified in Sohodoalele Mici Cave (SW Romania) within a large chamber near the entrance shaft. This study was motivated by the presence of a network of calcite ridges over the stalactites’ surface and by the observation that during winter, these speleothems are covered by a thin ice layer. The higher δ18O (−3.5 to –1‰) and δ13C (0 to 7‰) values found in the calcite ridges relative to δ18O (–7.5 to –4‰) and δ13C (–9 to –2‰) values of calcite from the inner stalactite indicate that the ridges are of cryogenic origin and formed during relatively rapid carbonate precipitation associated with evaporative cooling and freezing of the water. Four U-series ages suggest that the stalactites with ridges formed during cold winters of the Holocene, when cave air temperatures dropped below freezing.

Ultrasound-assisted dissolution of U3O8 powder in carbonate solution was explored to determine if and how ultrasound act during the dissolution. The variation of U3O8 solid particles and uranyl complexes under ultrasound treatment and magnetic stirring was observed in carbonate media. The results show that the use of ultrasound can increase the solubility and dissolution rate of U3O8 powder than that under magnetic stirring. The crush of U3O8 particles and the reduction of the activation energy (Ea, kJ/mol) of U3O8 dissolution reaction were observed, which both play an important role in the ultrasonic-assisted dissolution of U3O8 in carbonate-peroxide solution. Meanwhile, there is no observation of the ultrasound effect on the distribution of uranyl species and hydrolysis of uranyl complexes during the ultrasound treatment in carbonate-peroxide solution. Although the generation of ·OH radicals under ultrasound (22 ± 2 kHz) was observed, the oxidation of ·OH had little effect on the dissolution of U3O8 in the carbonate-peroxide solution system.

The planar title compound 4,5-dimethyl-1,3-dioxol-2-one, C5H6O3, 1, crystallizes with its molecular C2 axis coincident with a crystallographic mirror plane in space group P21/m. In the plane defined by the b axis and an ac face diagonal, antiparallel linear strands of 1, formed by simple translation, associate to form sheets with close H...H and O...O intermolecular contacts. Between the sheets, parallel strands of 1 place the carbonyl O atom near the five-membered ring centroid of a neighboring molecule with close O...O and O...C contacts.