Carbonate Complexes Research Articles

A comprehensive review of soil organic carbon estimates: Integrating remote sensing and machine learning technologies

Abstract Purpose Accurately assessing soil organic carbon (SOC) content is vital for ecosystem services management and addressing global climate challenges. This study undertakes a comprehensive bibliometric analysis of global estimates for SOC using remote sensing (RS) and machine learning (ML) techniques. It showcases the historical growth and thematic evolution in SOC research, aiming to amplify the understanding of SOC estimation themes and provide scientific support for climate change adaptation and mitigation. Materials and Methods Employing extensive literature database analysis, bibliometric network analysis, and clustering techniques, the study reviews 1,761 articles on SOC estimation using RS technologies and 490 articles on SOC employing both RS and ML technologies. Results and Discussion The results indicate that satellite-based RS, particularly the Landsat series, is predominant for estimation of SOC and other associated studies, with North America, China, and Europe leading in evaluations with Africa is having low evaluations adopting RS technology. Trends in the research demonstrate an evolution from basic mapping to advanced topics such as carbon (C) sequestration, complex modeling, and big data utilization. Thematic clusters from co-occurrence analysis suggest the interplay between technology development, environmental surveys, soil properties, and climate dynamics. Conclusion The study highlights the synergy between RS and ML, with advanced ML techniques proving to be critical for accurate SOC estimation. These findings are crucial for comprehensive ecosystem SOC estimation, informed environmental management and strategic decision-making.

Characterization of identical lithium-ion battery electrodes before and after charge/discharge cycles via in-plane large-area polishing

As an effective method to fabricate a large-area cross-sectional sample for lithium-ion battery electrodes, we perform in-plane polishing of LiNi0.8Co0.15Al0.05O2(NCA) cathode samples and obtain a large cross-sectional area with a diameter of 1.5 mm. The polished cross-sections of NCA cathode particles are sufficiently flat to perform the atomic force microscopy (AFM) measurements on each cathode particle. Following AFM-based Kelvin probe force microscopy and scanning spreading resistance microscopy measurements, an identical in-plane polished NCA sample is assembled into a coin cell for the charge and discharge processes. After 90 charge/discharge cycles, the in-plane-polished sample is successfully disassembled from the coin cell without causing critical damage. In addition, a microcrack structure, which is a typical degradation feature of the cycles of NCA particles, is observed for the identical in-plane polished NCA sample. This indicates that the in-plane polishing method is effective for investigating identical NCA electrode samples before and after the charge/discharge process. Furthermore, the in-plane polishing method can be successfully applied to the large-area polishing of a Si-based anode which is a mixture of Si carbon complexes and graphite particles. This study presents a novel methodology for analyzing the degradation of lithium-ion battery electrode materials.

Simultaneous measurement of labile U(VI) concentration and (234U/238U) activity ratio using a Monophos®-based Diffusive Gradients in thin-films sampler

BackgroundIn a context of environmental monitoring around installations related to the nuclear fuel cycle, the Diffusive Gradient in Thin-films (DGT) technique captures the integrated concentration of U isotopes in their native environment, yielding comprehensive data on U origin (anthropogenic vs natural), total concentration, and mobility. However, for common deployment times (4–5 days) in moderately basic waters, none of the commercially available binding gels is adapted to measure the total U concentration. So, the development of novel DGT binding gels is timely. ResultsA new DGT sampler, using the Monophos® resin, as well as a new model for the interpretation of the DGT flux, has been successfully developed to measure the labile U concentration (which was also its total concentration) in moderately basic waters (pH ≈ 8). The model accounts for the penetration of uranyl carbonate complexes into the binding gel. Monophos-DGT samplers were able to quantify the total U concentration (accuracy >90 %) in three different mineral basic waters and in a synthetic seawater in laboratory experiments, as well as in situ in the rivers Essonne and Œuf, France. Ion interferences (e.g., Ca2+, Mg2+ and HCO3−), critical when using Chelex and Metsorb resins as binding agents, were overcome by using the new DGT sampler, thus allowing for a longer linear accumulation of U in the tested matrices and, above all, a better detection of U minor isotopes improving the potential of using DGT samplers for water source tracing through isotopic measurements. SignificanceThe use of the new DGT sampler and the new model for the interpretation of DGT flux is recommended to improve the accuracy of total U concentration determinations in field applications. Moreover, simultaneous elemental and isotopic measurements were successfully performed during field application, confirming new perspectives for environmental applications such as identification of U pollution sources by using isotopic signatures.

Conceptual modelling on water-rock reaction and genesis of high pH fluids in a typical granitoid geothermal reservoir: A case from Indus-Tsangpo Suture Zone, India

Two novel thermal springs are investigated along ITSZ of north-west Himalayas in Demchok geothermal belt. The area consists of deep-seated faults in LGB; despite being situated in ITSZ, fluid chemistry of these low-temperature springs differs significantly, specifically in terms of low TDS (161–168 mg/l) and high alkalinity, with neighbouring springs in Puga and Chumathang (∼2100 mg/l). Thermal waters are mixed type (Na–Cl–HCO3–SO4) with elemental composition influenced through silicate rock weathering and partial carbonate dissolution. Variable temperature speciation (25 °C–200 °C) indicates that in reservoir fluid, Na+ precedes over other cations, while sulfate and carbonate complexes being prominent for Mg and Ca, respectively. Aquifer boiling modelling suggests calcite scaling and silica mineral equilibration in reservoir. Environmental stable isotopes (δ18O and δD) suggest high-altitude recharge from Jamlung La (6156 m), with altitude-effect of 0.43 ‰ isotopic depletion per 100 m elevation in altitude. As only silica minerals equilibrate with thermal waters, silica, and gas geothermometers give most conservative estimate of reservoir temperature (125°−135 °C). The steep topography enables extensive lateral flow of hot fluids in outflow zone, leading to high mixing and a high water-rock ratio, which contribute to lower TDS. Conceptual modelling reveals that geothermal system is a low-enthalpic hydrothermal system controlled by joints and permeable fractures, having deep fluid circulation of meteoric waters of ∼1275 m at sub-surface, with anomalous geothermal gradient and steam migration as reservoir heat sources. These fluids closely resemble springs of Guerrero state, Mexico, exhibiting similarities in low-TDS, high-pH, and high concentration of dissolved silica.

A Greener Way of Making Cellulose Clothing

Cotton is the world's most demanding non-food crop. Cotton grows in arid countries such as India and China. However, its production consumes an enormous 250 billion tons of water annually, amplifying water scarcity. Cellulose, found in plants like wood, bamboo, and mosses, offers a sustainable alternative for textiles. Traditionally, cellulose is processed into textiles using the viscose method, which involves carbon disulfide. This process releases hydrogen sulfide, harmful to aquatic life and human health, and carbon disulfide, a hazardous pollutant affecting the reproductive system and vision. Many research groups have proposed an alternative method, which involves dissolving cellulose in dimethyl sulfoxide (DMSO) and Diazabicyclo[5.4.0]undec-7-ene (DBU) under 1 atm of CO2. DBU, with a pKaH ~ 12, deprotonates cellulose’s hydroxyl groups forming a DMSO-soluble cellulose carbonate complex that can be spun into filaments. However, DBU is costly, hazardous, and prone to hydrolysis, leading to byproducts. The objective of the research was to find a more environmentally friendly, less toxic, and cost-effective base for cellulose dissolution. Two tertiary amines, triethylamine (pKaH~9) and tripropylamine (pKaH~10.7), were tested. Due to its low basicity triethylamine failed to dissolve cellulose even under high CO2 pressure (up to 50 bar), resulting in a cloudy solution. Tripropylamine is insoluble in DMSO, therefore resulting in a phase separation of a tripropylamine layer and cellulose/DMSO layer. Additionally, 2,2,6,6-tetramethyl-piperidine was also tested at high CO2 pressure (up to 50 bar), but a biphasic solution was formed at 10 bar . This indicates that the protonated form of the base does not dissolve in DMSO. Ultimately, no alternative base was found to be sufficiently basic to deprotonate the hydroxyl groups on cellulose and promote dissolution, even at high pressure.

Migration and controlling factors of rare earth elements in geothermal systems on the southern Tibetan Plateau

Rare earth elements (REE) serve as effective tracers of water-rock interactions, a crucial process in the evolution of geothermal systems. However, the geochemical behavior of REE during their migration within geothermal systems, particularly the fractionation mechanism, remains poorly understood. In this study, we focus on the geochemical characteristics of REE in hot springs, host rocks, and sinters from various hot spring systems in the Yadong-Gulu rift (YGR), the largest extensional rift in the southern Tibetan Plateau. The objective is to explore the factors that control REE concentrations in hot springs and elucidate the fractionation of REE during their migration. The concentrations of REE are significantly influenced by pH, Fe oxides (oxyhydroxides), and HCO3− concentrations in central and southern hot springs, whereas high reservoir temperatures contribute to higher ΣREE concentrations in northern hyperthermal springs. REE speciation calculations show that LnO2− and LnO2H are dominant complexes in northern alkaline hot springs, while carbonate complexes (LnCO3+ and Ln(CO3)2−) prevail in central and southern spring samples. Additionally, weakly acidic hot springs exhibit a prevalence of Ln3+, LnF2+, and LnSO4+ species. The chondrite-normalized REE patterns of all hot spring samples display enrichment in MREE, which is significantly distinct from the patterns observed in host rocks and sinters enriched in LREE. The fractionation of REE in the YGR hot spring systems is primarily controlled by the following processes: (1) Temperature, pH, and relative abundance of complexing agents influence the complexation of REE and further regulate their fractionation in hot springs; (2) During water-rock interaction, preferential leaching of HREE and MREE from host rocks can lead to their enrichment in alkaline hot springs. The dissolution of iron-rich sediments plays a significant role in generating the distinctive MREE bulge pattern in acid-neutral hot springs compared to host rocks; (3) The higher stability of MREE and HREE complexes in water, as well as the preferential coprecipitation of unstable LnCO3+ complexes formed by LREE with carbonates, are key factors responsible for LREE enrichment in sinters.

Redox conditions influence the chemical composition of iron-associated organic carbon in boreal lake sediments: A synchrotron-based NEXAFS study

The global carbon and iron cycles are intimately linked as redox-sensitive iron oxides readily bind organic carbon in a variety of environmental settings, including marine and lacustrine sediments. While these iron-organic carbon complexes sequester vast quantities of organic carbon, the composition of the organic matter within them remains unknown for lacustrine environments. Here we present C K1s and Fe L3,2 edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of surface sediments and authigenic iron complexes from adjacent basins of a pristine boreal lake located in Québec, Canada, with contrasting oxygen exposure regimes. We demonstrate differences in organic carbon speciation in sediments from both basins, as well as co-localization of organic carbon and iron on a sub-micron scale in 100 nm thick samples. Differences in redox cycling across these two basins allow for a direct comparison of the effect of oscillating redox conditions on the composition of organic carbon sequestered by iron. Our results suggest that reactive organic molecules, which may be polysaccharides, were found preferentially associated with iron in the perennially oxic sediments compared to more phenol rich organics in the seasonally anoxic sediments, highlighting the importance of iron oxides in the protection and preservation of labile organic compounds. Traces of aliphatic carbon were observed in sediments from the anoxic basin, alongside carboxyl and aromatic functionalities. This carboxyl-rich aliphatic material could possibly interact with the sediment mineral matrix either through a ligand exchange mechanism between the mineral phases and the carboxyl functionalities, or via non-specific hydrophobic interactions involving the aliphatic moieties. Finally, our work also shows that OC:Fe ratios should be used with caution when inferring a binding mechanism between OC and iron oxides.

Changes in the Aggregation Behaviour of Zinc Oxide Nanoparticles Influenced by Perfluorooctanoic Acid, Salts, and Humic Acid in Simulated Waters.

The increasing utilization of zinc oxide nanoparticles (ZnO-NPs) in many consumer products is of concern due to their eventual release into the natural environment and induction of potentially adverse impacts. The behaviour and environmental impacts of ZnO-NPs could be altered through their interactions with environmentally coexisting substances. This study investigated the changes in the behaviour of ZnO-NPs in the presence of coexisting organic pollutants (such as perfluorooctanoic acid [PFOA]), natural organic substances (i.e., humic acid [HA]), and electrolytes (i.e., NaCl and CaCl2) in simulated waters. The size, shape, purity, crystallinity, and surface charge of the ZnO-NPs in simulated water after different interaction intervals (such as 1 day, 1 week, 2 weeks, and 3 weeks) at a controlled pH of 7 were examined using various characterization techniques. The results indicated alterations in the size (such as 162.4 nm, 1 day interaction to >10 µm, 3 weeks interaction) and zeta potential (such as -47.2 mV, 1 day interaction to -0.2 mV, 3 weeks interaction) of the ZnO-NPs alone and when PFOA, electrolytes, and HA were present in the suspension. Different influences on the size and surface charge of the nanoparticles were observed for fixed concentrations (5 mM) of the different electrolytes. The presence of HA-dispersed ZnO-NPs affected the zeta potential. Such dispersal effects were also observed in the presence of both PFOA and salts due to their large aliphatic carbon content and complex structure. Cation bridging effects, hydrophobic interactions, hydrogen bonding, electrostatic interactions, and van der Waals forces could be potential interaction forces responsible for the adsorption of PFOA. The presence of organic pollutants (PFOA) and natural organic substances (HA) can transform the surface characteristics and fate of ZnO-NPs in natural and sea waters.

Assessment of Metal Impurity Partitioning and Speciation in Mineral Carbonation Processes Using FGD-Gypsum from Coal-Fired Power Plants under Distinct Operating Conditions.

The sequestration of carbon dioxide (CO2) stands as a profoundly pivotal environmental challenge, given its potential to directly contribute to the advancement of environmental, societal, and economic objectives across a multitude of nations. In the present study, we have conducted an evaluation of the metal impurity partitioning and speciation in mineral carbonation processes conducted in laboratory using flue gas desulfurization (FGD) gypsums originating from both Spanish and two Chinese coal-fired power plants, each subject to distinct fuel sources and FGD operational conditions. Of the three resultant carbonation products, two exhibited CaCO3 content in the range of 81-83%, while the third registered 76.9% CaCO3 content-a variance attributed to the occurrence of metallic impurities within the initial FGD-gypsum. The partitioning and speciation of metal impurities at all stages of CO2 conversion have enabled us to proffer four potential reaction mechanisms governing carbonation efficiency: (i) conversion of metal sulfates to metal carbonate complexes, (ii) transformation of transferable elements into metal oxides and oxyhydroxide complexes, (iii) transformation of metal sulfates into diverse metal complexes, and (iv) diverse pathways of elemental transformation. Metal impurities present in FGD-gypsum lead to the formation of complexes between As and metals, thereby affecting their activity. Higher Ca/Mn, Ca/Fe, and Ca/Al ratios in one FGD-gypsum slurry enhance Ca3(AsO4)2·8H2O activity, while in another, excess Ca facilitates Mn3(AsO4)2·8H2O formation during carbonation, with coprecipitation retaining As in carbonation products. The occurrence of metallic contaminants in FGD-gypsums may exert a substantial influence on the effectiveness of CO2 conversion, thereby impacting the feasibility of using resultant carbonation products, with potential implications for environmental leaching and diminished reusability prospects.

Localization of Iodine and Uranyl Carbonate Complex on Metal-Containing Clay Materials from Aqueous Media

Localization of Iodine and Uranyl Carbonate Complex on Metal-Containing Clay Materials from Aqueous Media

Understanding Europium and Terbium Speciation and Ion Pairing in Carbonate Complexes Using Advanced Spectroscopy Techniques

Lanthanide (Ln) elements are critical materials that are typically extracted/mined together. Their separation by solvent extraction from acidic media is well known; however, there are few studies in basic media with carbonate anions. We investigated the complexation of Eu(III) and Tb(III) carbonates as solids and solutions in alkaline K2CO3, wherein we sought to access a Tb(IV) carbonate complex through ozonolysis. L3‐edge XANES of Eu and Tb carbonate solids, colorless solutions, and a red‐hued Tb solution (obtained by ozonolysis) all showed Ln(III) cations. The absence of evidence for a Tb(IV) complex was confirmed through XAS and EPR analyses, despite the solution exhibiting a deep red color. For solids and solutions, EXAFS results indicate molecular Ln(III)‐carbonato anions. In terms of the Eu(III) carbonate coordination number, the coordination does not change upon dissolution of the solid sample. Furthermore, EXAFS for the solutions revealed evidence for the association of potassium cations with the Ln(III)‐carbonato anions. This direct observation of contact ion pairing by EXAFS at room temperature is rare. The insights into Ln(III) carbonate complexation and solution speciation afforded by XANES‐EXAFS, FT‐IR, and EPR provides perspectives that serve as benchmarks for future computational and experimental efforts focused on caustic‐side solvent extraction of Ln(III) ions.

Sedimentary dolomite in Western Australia and the dolomite problem: Genesis of channel and playa uranium deposits

ABSTRACTQuaternary to Recent sedimentary dolomite in groundwater calcrete and saltmarsh sediments of Lake Way and Lake Maitland, Western Australia, provide new information about the formation of low‐temperature dolomite. Dolomite can form through numerous pathways depending on the depositional and diagenetic environment. Many pathways involve microbial processes and/or the presence of a nucleation substrate which help overcome kinetic barriers preventing precipitation in the laboratory. Petrographic, mineralogical, hydrogeochemical and stable isotopic data in this study reveal the importance of Mg‐clays as nucleation sites for dolomite precipitation in a range of aquifer environments. There is also a close association between authigenic Mg‐clays, dolomite and the potassium–uranyl–vanadate ore mineral carnotite in channel and playa uranium deposits. It is interpreted that evaporation‐driven precipitation of dolomite establishes a positive feedback loop promoting the dissociation of aqueous uranyl–carbonate complexes and concomitant increase in carnotite saturation. Critical to this model is the presence of authigenic Mg‐clays because they facilitate dolomite precipitation and promote carnotite nucleation by concentrating potassium ions on clay surfaces via adsorption. This Mg‐clay–dolomite–carnotite relationship is widespread throughout Western Australian channel and playa uranium deposits and has been observed in similar deposits in Namibia and Botswana. In addition to this economic implication, Mg‐clay mediated nucleation of dolomite potentially has global relevance as a precipitation mechanism for low temperature dolomite in sedimentary deposits where detrital and/or authigenic Mg‐clays are present. Maturation of sedimentary dolomite from disordered high‐calcian dolomite to ordered low‐calcian dolomite occurs very early in the meteoric realm making it resistant to alteration during burial diagenesis. Diagenetic resistance may be further increased by early meteoric silicification related to the degradation of associated Mg‐clays. These findings indicate that Mg‐clay associated sedimentary dolomite has potential to retain a primary isotopic signature indicative of its origin, making it a useful recorder of palaeoenvironmental conditions.

Geological structure of the Strelnica Massif (Muráň Plateau, Central Slovakia) based on new biostratigraphical data and geological mapping

The Strelnica massif is a part of the Muráň Plateau near Tisovec town. The massif is of prolonged triangular shape and is sharply defined by faults from all sides: the Muráň fault (line) on the SE side, the Mýto-Tisovec fault system from the SW side and a thrust/fault line with unclear character in the Martinová valley on the N side. The massif was supposed to be built by Lower to Middle Triassic carbonate complexes, however our new biostratigraphic data had proven that in fact most of these light grey carbonates belong mostly to Upper Triassic, which makes necessary the reinterpretation of the structure of the whole massif. Despite of new and more complicated structural interpretation, our new age data are in better agreement with earlier works from the Tisovec quarry as it was in earlier geological maps. Our mapping works also confirmed, that the Strelnica massif itself is built by two facially very different blocks: a deep-water type of succession with Reifling and Raming type limestones and a strongly tectonically reduced succesion from probably lower Carnian up to Liassic age. These two blocks are in tectonic contact along a fault line and both are lying on the Lower Triassic shaley complex which forms the basal horizon of the Muráň nappe. The Muráň fault (line) is covered by Quaternary deposits in the aera, but in addition we suppose also at least two newer fault systems: a NNW-SSE normal fault system, parallel with the Mýto-Tisovec fault system in the Rimava valley and a roughly WNW-ESE system with probable sinistral strike-slip kinematics. Both systems were locally known from the Tisovec quarry, or the structural measurements from the Dielik cave in the NE part of the massif, however not mapped in the whole massif.

REE-phosphate mineralization stages and conditions of monazite formation in the ore veins in the northern part of Ditrău Alkaline Massif (Eastern Carpathians, Romania)

In terms of rare earth potential, the Ditrău Alkaline Massif (Romania) is one of the most prospective formations in Europe. The REE mineralization occurs as mineralized ore veins and is most prominent in the northern (Jolotca) and eastern (Belcina) parts of the Massif. The ore veins of Jolotca area outcrop over a larger area than the Belcina ones, and are predominantly rich in LREE minerals. The most important REE minerals in the Jolotca veins are phosphates, of which monazite (Mnz) (group) is by far the most abundant, while xenotime (Xtm) occur only sporadically. The monazite-xenotime mineral assemblages are the products of at least three successive mineralization stages: (1) Mnz1 followed by Xtm1 (the vast majority of REE phosphates formed in this stage); (2) Mnz2 + Xtm2 (as inclusions in apatite) and Mnz3 + Xtm3 (as interstitial phases), the two assemblages are texturally distinct but their synchronous formation is likely; (3) Mnz4 scattered in magnetite veins (no xenotime formed in this stage). The chemical composition of the phases formed in each stage supports their hydrothermal origin. The alteration characteristics, reaction patterns and internal textural features of the monazite-xenotime assemblages reflect the metasomatizing effect of each hydrothermal stage. Three fluid types with different compositions were identified in the earliest Mnz1 phase: An H2O-NaCl-CO2 type (2–4 mol% CO2, 10–22 wt% NaCleq., Th: 225–350 °C), an H2O-NaCl type (10–22 wt% NaCleq., Th: 160–330 °C) and an H2O-NaCl-CaCl2 type (23–25 wt% NaCleq., Th: 150–250 °C). Combining Y-in monazite thermometry data with isochores of primary originated fluid inclusions indicate <500 MPa pressures and 200–420 °C temperature conditions for formation of Mnz1. The observed REE patterns of monazites were most probably resulted by a temperature derived fractionation of REEs carried as carbonate complexes in hydrothermal fluids by the effect of successive metasomatic flushing.

Геохимическая характеристика озера Чваниха, памятника природы Кировской области

The article presents characteristics of the abiotic components (water and bottom sediments) of the karst Lake Chvanikha. The lake is located in the Nolinsky district of the Kirov region and has the status of the hydrological natural monument of regional significance. The results are based on precision analytic data (obtained by ICP-MS, X-ray fluorescence analysis, chemical methods, photometry, etc.) and on thermodynamic calculations (Visual-MINTEQ. ver. 3.1). The composition of the waters indirectly indicates to the development of carbonate karst (mainly the dissolution of dolomite) in the upper rock strata at the base of the lake basin and to the presence of minor gypsum interlayers at depth. The concentrations of dissolved forms of trace elements do not exceed the MPCs of harmful substances in the waters of fishery basins and generally corresponds to the average contents in the rivers of the world. The base forms of trace elements in water are their free ions (for Sr, Ba, Fe, Mn, Zn, Ni, Co, Cd) and carbonate complexes (for Pb and Cu). The bottom sediments are represented of fine quartz sands, which overlap the karst rocks. In the absence of a significant technogenic impact, the poor grade of sand’s ferruginization determines low contents of potential pollutants (Cu, Zn, Pb, Cd, As, Mo, Ni, Cr, V), typical for quartz sands.

Probing Correlation of Optical Emission and Defect Sites in Hexagonal Boron Nitride by High-Resolution STEM-EELS.

Optically bright emitters in hexagonal boron nitride (hBN) often acting as a source of a single-photon are mostly attributed to point-defect centers, featuring localized intra-bandgap electronic states. Although vacancies, anti-sites, and impurities have been proposed as candidates, the exact physical and chemical nature of most hBN single-photon emitters (SPEs) within the visible region are still up for debate. Combining site-specific high-angle annular dark-field imaging (HAADF) with electron energy loss spectroscopy (EELS), we resolve and identify a few carbon substitutions among neighboring hBN hexagons, all within the same sample region, from which typical defect emission is observed. Our experimental results are further supported by first-principles calculations, through which the stability and possible optical transitions of the proposed carbon-defect complex are assessed. The presented correlation between optical emission and defects provides valuable information toward the controlled creation of emitters in hBN, highlighting carbon complexes as another probable cause of its visible SPEs.

Chitin/calcium carbonate complex microparticles and their effects on polylactic acid composite films

Chitin/calcium carbonate complex microparticles and their effects on polylactic acid composite films

A new subterranean species of Oncopodura Carl &amp;amp; Lebedinsky, 1905 (Collembola, Entomobryomorpha, Oncopoduridae) from a cave in Northeastern Iran

A new species of Oncopodura (Collembola, Entomobryomorpha, Oncopoduridae) from the Moghan cave in northeastern Iran, built in a carbonate complex of Kopet Dag mountain range, is described. Oncopodura moghanensis sp. nov. can be distinguished from other congeners by (1) 6 long subequal lobes in PAO, each subdivided into 3–6 fingers, (2) dens with 7 dorsal feather-like macrosetae; at basal part with 1 dorsoexternal and 2 dorsointernal hooks, at the distal part with 1 dorsoexternal and 3 dorsointernal hooks, (3) distal part of manubrium with long feather like macrosetae reaching middle part of dens, and (4) mucro with 4 teeth, apical tooth very sharp, and 2 scales at its basal half. A table with diagnostic characters of species related to the Oncopodura moghanensis sp. nov. and an updated key to the world species of Oncopodura are provided.

Variable responses of mineral-bound soil organic carbon to land cover change in southern China’s coastal wetlands

The formation of mineral-bound organic carbon (OC) complexes is important for the long-term preservation of soil organic carbon (SOC) in wetlands. Many coastal wetlands globally have been threatened by plant invasion and land development, but information on the effects on mineral-bound OC is limited. We measured the soil contents of Ca-OC, Fe(Al)–OC and residual OC across 21 coastal wetlands in southern China that have gone through the same sequence of land cover change, from native mudflats (MFs) to Spartina alterniflora marshes (SAs) then to earthen aquaculture ponds (APs). Residual-OC was the main component of SOC (74.1–78.2 %), followed by Fe(Al)–OC (18.4–22.8 %) and Ca-OC (<3.5 %). All three components in the soil increased when MFs were converted to SAs, but decreased in subsequent conversion of SAs to APs. Land cover change affected Fe(Al)–OC the most, but SOC storage increased more strongly with increasing Ca-OC. Nitrogen supply in the form of NH4+-N and clay content both positively affected the changes in mineral-bound OC. Our results suggest that different land cover change scenarios had different effects on the amounts of mineral-bound OC and their liability to microbial turnover, resulting in different degrees of SOC preservation and carbon emissions.

Multi-Sensor Satellite Remote-Sensing Data for Exploring Carbonate-Hosted Pb-Zn Mineralization: Akhlamad Area, Razavi Khorasan, North East Iran

The exploration of Pb-Zn mineralization in carbonate complexes during field campaign is a challenging process that consumes high expenses and time to discover high prospective zones for a detailed exploration stage. In this study, multi-sensor remote-sensing imagery from Landsat-8, Sentinel-2, and ASTER were utilized for Pb-Zn mineralization prospectivity mapping in the Akhlamad carbonate complex area, Razavi Khorasan, NE Iran. Due to the presence of carbonate formations and various evidence of Pb-Zn mineralization, this area was selected. Band composition, band ratio, principal component analysis (PCA), and SAM techniques for mapping alteration minerals as well as lineament analysis were implemented. Subsequently, a fuzzy logic model for identifying the prospective zones of Pb-Zn mineralization using multi-sensor remote-sensing satellite images was designed. The weight of each exploratory layer was determined using the fuzzy hierarchical method and the integration process of the information layers was performed using fuzzy operators. Finally, the existing mineral indications were used to evaluate and validate the obtained mineral potential map. The outcome of this investigation suggested several high-potential zones for Pb-Zn exploration in the study area.