Properties Of Minerals Research Articles

Improving the Nutritional, Antioxidant, and Sensory Characteristics of Ready-to-use Yellow Sauce Condiments

Objectives: The study aimed to improve the nutritional, antioxidant, and sensory attributes of yellow sauce spice blends. Methods: A qualitative survey among housewives, traders, and restaurant owners identified commonly used spice blends for yellow sauce recipes. The blend with the highest sensory acceptability index was used as the base for modeling with a Simplex Lattice mixture design. Variables included the nature and proportion of spices, with responses being total phenolic compound content and sensory acceptability index. The resulting formulation was tested for in vitro antioxidant activities (TAC, FRAP, DPPH, and °OH), water and mineral contents (Fe, Cu, P, Mg, and Ca), and physical and functional properties (color, density, water, and oil absorption capacity). Results: The survey identified four spice blend recipes, with the most accepted having a sensory acceptability index of 0.7. Optimization produced a blend of 18% Afrostyrax lepi-dophyllus, 8% Piper guineense, 38% Tetrapleura tetraptera, 31% Dichrostachys glometara, and 5% Xylopia aethiopica (Dunal) A. riche. This blend exhibited fairly pleasant acceptabil-ity (index = 0.80) and a phenolic compound content of 1398.69 Eq mg AG/100g of DM. The developed formulation showed higher levels of zinc (19 ppm) and iron (234 ppm), as well as superior Total Antioxidant Capacity (310.04 Eq mg AG/100g DM) and °OH inhibition (75.32 μg/ml) compared to the survey-derived formulation. Conclusion: The modeling of the spice blends improved some sensory, antioxidant, and mineral properties, ensuring consistent quality in the yellow sauce condiments.

Hedgehog signaling directs cell differentiation and plays a critical role in tendon enthesis healing

A high prevalence of rotator cuff tears presents a major clinical challenge. A better understanding of the molecular mechanisms underlying enthesis development and healing is needed for developing treatments. We recently identified hedgehog (Hh)-lineage cells critical for enthesis development and repair. This study revealed cell-cell communication within the Hh-lineage cell population. To further characterize the role of Hh signaling, we used mouse models to activate and inactivate the Hh pathway in enthesis progenitors. Activation of Hh target genes during enthesis development increased its mineralization and mechanical properties. Activation of Hh signaling at the injured mature enthesis promoted fibrocartilage formation, enhanced mineralization, and increased expression of chondrogenic and osteogenic markers, which implies that Hh signaling drives cell differentiation to regenerate the damaged enthesis. Conversely, deletion of Hh target genes impaired enthesis healing. In summary, this study revealed a new strategy for enthesis repair via activation of Hh signaling in endogenous cells.

Mixed Signals: interpreting mixing patterns of different soil bioturbation processes through luminescence and numerical modelling

Abstract. Soil bioturbation plays a key role in soil functions such as carbon and nutrient cycling. Despite its importance, fundamental knowledge on how different organisms and processes impact the rates and patterns of soil mixing during bioturbation is lacking. However, this information is essential for understanding the effects of bioturbation in present-day soil functions and on long-term soil evolution. Luminescence, a light-sensitive mineral property, serves as a valuable tracer for long-term soil bioturbation over decadal to millennial timescales. The luminescence signal resets (bleaches) when a soil particle is exposed to daylight at the soil surface and accumulates when the particle is buried in the soil, acting as a proxy for subsurface residence times. In this study, we compiled three luminescence datasets of soil mixing by different biota and compared them to numerical simulations of bioturbation using the ChronoLorica soil-landscape evolution model. The goal was to understand how different mixing processes affect depth profiles of luminescence-based metrics, such as the modal age, width of the age distributions and fraction of the bleached particles. We focus on two main bioturbation processes: mounding (advective transport of soil material to the surface) and subsurface mixing (diffusive subsurface transport). Each process has a distinct effect on the luminescence metrics, which we summarized in a conceptual diagram to help with qualitative interpretation of luminescence-based depth profiles. A first attempt to derive quantitative information from luminescence datasets through model calibration showed promising results but also highlighted gaps in the data that must be addressed before accurate, quantitative estimates of bioturbation rates and processes are possible. The new numerical formulations of bioturbation, which are provided in an accompanying modelling tool, provide new possibilities for calibration and more accurate simulation of the processes in soil function and soil evolution models.

A Realistic 3D Grain-Based Modeling Approach for Reproducing the Mechanical and Failure Behavior of Brittle Granites

Exploring cracking behavior from mineral-scale do good help to understand the failure mechanism of rock materials. The present study proposes a realistic three-dimensional grain-based modeling (3D-GBM) method considering the actual distribution, geometry and mesoscopic mechanical properties of different minerals in granite samples. The geometrical characteristic and distribution were captured based on high-precision computed tomography (CT) scanning and polarized microscopy. The mesoscopic mechanical properties were measured using nanoindentation combined with the scanning electron microscope-energy dispersive spectroscopy scanning (SEM-EDS). The results indicate that the established model can realistically reproduce the mechanical and failure behavior of granite subjected to unconfined compression in terms of stress-strain curves, failure mode, crack evolution, and force transmission. Investigating crack propagation at mineral-scale shows that the relative damage degree is greater at weak boundaries (i.e., boundary related to mica) and relatively soft minerals (i.e., mica) than that of strong boundaries (i.e., quartz-quartz and quartz-feldspar) and stiffer minerals (i.e., quartz and feldspar). Grain boundaries and soft mica minerals play an important role in guiding and deflecting the crack propagation path due to the mismatch in elasticity and strength compared with the stiffer and harder minerals (i.e., quartz and feldspar).

A novel chemical chaperone ameliorates osteoblast homeostasis and extracellular matrix in osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a collagen I-related heritable family of skeletal diseases associated to extreme bone fragility and deformity. Its classical forms are caused by dominant mutations in COL1A1 and COL1A2, which encode for the protein α chains, and are characterized by impairment in collagen I structure, folding, and secretion. Mutant collagen I assembles in an altered extracellular matrix affecting mineralization and bone properties and partially accumulating inside the cells, leading to impaired trafficking and cellular stress. Recently, the chemical chaperone 4-phenylbutyrate (4-PBA) has been proposed as an innovative drug for OI based on its ability to restore intracellular homeostasis, stimulate secretion, and ameliorate collagen-producing cell functions, positively affecting bone properties. However, the limited half-life of the molecule represents a serious hurdle for its use. To efficiently target cellular stress as OI treatment, two new compounds were designed by molecular modelling based on the 4-PBA structure to increase its stability and its ability to implement protein secretion. The short butyryl fatty acid chain of 4-PBA was substituted with a nitro functional group or with a glycine, respectively. The latter, N-benzyl glycine (N-BG), showed the best docking score, less toxicity, and higher stability than 4-PBA. N-BG improved extracellular matrix quality and mineral content together with ameliorating OI cells' homeostasis by increasing ER-associated degradation pathway, reducing apoptosis, and stimulating protein secretion, thus facilitating intracellular clearance from accumulated misfolded proteins. In conclusion, N-BG represents a novel potential available compound to target altered homeostasis in OI with the aim to ameliorate the disease phenotype.

Feedback effect of the size of mineral particles on the molecular mechanisms employed by Caballeronia mineralivorans PML1(12) to weather minerals

Mineral dissolution by bacteria is thought to depend on mineral properties, solution chemistry, and the carbon sources metabolized. To investigate whether mineral particle size could impact the effectiveness of weathering and the molecular mechanisms employed by bacteria, the strain Caballeronia mineralivorans PML1(12) was considered. Through microcosm and kinetic experiments, we quantified changes in biotite dissolution, bacterial growth, siderophore biosynthesis, and acidification. The use of different solution chemistries, carbon sources, and particle sizes (from <20 to 500 µm) allowed us to decipher the relative role of acidification- and chelation-driven mineral weathering by bacteria. Results revealed a faster dissolution for smaller particles (<100 µm) that strongly affected both solution chemistry and bacterial physiology, while larger particles (>100 µm) showed a slower and steady dissolution with minimal impact on bacterial processes. These findings underscore the influence and feedback effects of particle size on the dynamics of dissolution and the mechanisms employed by bacteria.

Interaction of zinc oxide nanoparticles with soil colloidal suspensions.

The properties of soil colloids determine the interaction with nanoparticles, their behavior, and destiny in the soil environment including soil solutions. This study examines how several properties of soil colloids, including pH, phosphorus content, clay minerals, and iron oxyhydroxides, influence the interaction with zinc oxide nanoparticles (ZnO-nps). For the experimental setup, four different soils were selected from the temperate climate of central Europe, in Slovakia, exhibiting pH values ranging from 4.6 to 8.0. Two concentrations of ZnO-nps suspended in water, 20 and 200 mg Zn∙L-1 were applied to the colloidal suspensions extracted from the soils and shaken for 24 hours. Then the soil colloids were separated into three fractions, 100 to 1000 nm in size, 1 to 100 nm in size, and dissolved. Concentrations of Al, Si, Fe, Mn, P, and Zn were measured in these fractions, providing a comprehensive understanding of ZnO-NP distribution and interaction with soil colloids. The study reveals that soil pH significantly affects the distribution of Zn from ZnO-nps across different size fractions. However, the concentration of Fe, Al, and Si had an even greater impact on the concentration of dissolved Zn. Additionally, behavior of Zn following ZnO-NP application is associated with soil P content, where P may stabilize the ZnO-nps. These findings enhance the knowledge of nanoparticle behavior in various soil matrices and contribute to developing more stable, efficient, and easily usable nanoparticle-based applications in environmental science and agriculture.

A Review of the Intrinsic Parameters Affecting the Elastic Characteristics of Heterogeneous Carbonate Reservoirs: Insights from Laboratory Assessments

This research provides an in-depth analysis of how various parameters such as mineralogy, density, porosity, temperature, pressure, and structural features impact the velocities of sonic waves in carbonate rocks. Our findings reveal that the mineral composition significantly influences the elastic behavior of these rocks. The density and elastic properties of minerals, especially clay minerals, play a crucial role in affecting porosity and predominant pore types. The porosity of carbonate reservoirs impacts their elastic properties, leading to variations in sonic wave velocities depending on the different pore types present. For a given porosity, the velocities can vary considerably due to the presence of diverse pore types within the pore space. Non-interconnected porosities with spherical or near-spherical shapes, along with microporosity, alter the effective elastic properties of the rock. Additionally, temperature affects the velocity-porosity relationship in rocks, with experimental results showing a decrease in P-wave velocity as temperature increases. Under reservoir conditions, wave velocity in carbonate rocks is influenced by factors such as confining pressure, temperature, gas saturation, and effective stress. Specifically, P-wave velocity increases with confining pressure as soft pores and cracks gradually close, enhancing the dry rock bulk shear modulus. Conversely, rising temperatures cause a slight decrease in velocities and an increase in attenuation. In conclusion, this study enhances our understanding of the physical properties and behavior of carbonate rocks under reservoir conditions, thereby contributing to the exploration and production of hydrocarbon resources.

Educational-creative workshops: integrating creative expression into geological learning content

How can we nurture a childlike curiosity even in adulthood, how can we constantly question ourselves about nature and the environment we live in, and last but not least, how to raise public awareness of geology in an understandable and interesting way? All these questions led to the idea and design of a workshop that includes different views of looking at nature from a scientific, practical and artistic perspective. The article presents a workshop on painting with natural pigments through which participants learn about various geological contents. In the first part of the workshop, participants learn about the entire process of making natural pigments, which includes determining a suitable mineral/rock for pigment, the pigment preparation process (crushing, grinding, and sieving), and mixing pigments with a binder into a final colour that can be used and stored. This part of the workshop introduces approaches that are comparable to scientific one. In a very practical way, participants will learn about some of the properties of rocks and minerals (colour, color of the mineral's streak, hardness, etc.) and sample preparation methods. The second part of the workshop is more creative, where participants use colouring books with geological motifs or paint freely. They explore the characteristics of pigments made from various materials, and connect new knowledge on an experiential level. One of the main aims of the workshop is to interweave and combine educational and creative content, focussing on active and experimental learning methods. The paper also shows the adaptations of the workshop to the age of the participants and the type of event (e.g. public events).

Influence of Complex Lithology Distribution on Fracture Propagation Morphology in Coalbed Methane Reservoir

The mineral composition in coalbed methane (CBM) reservoirs significantly influences fracture morphology, making the description of reservoir heterogeneity challenging. This study develops a fracture propagation model for CBM reservoirs that incorporates the varying mineral properties within the reservoir’s lithology. Dynamic logging data are considered to characterize rock mechanical properties, which form the basis for in situ stress estimation. Using an adjusted critical circumferential stress calculation for coal rock, the model considers the impact of complex lithology on fracture propagation. A comprehensive fractal index is introduced to capture the influence of different minerals on fracture morphology and propagation randomness. Models representing clay, quartz, and pyrite with varied compositions were constructed to explore the effects of each mineral on fracture characteristics. In single-component models, clay-rich reservoirs exhibited the highest induced fracture density, with quartz and pyrite showing approximately 65% and 20% of the fracture density observed in clay, respectively. Fractures primarily propagated toward quartz-rich regions, while pyrite significantly inhibited fracture growth. In mixed-mineral models, increasing the quartz proportion by 40% resulted in a 20 m increase in fracture length and a 30% reduction in fracture density. Fractures predominantly propagated around pyrite boundaries, demonstrating pyrite’s resistance to fracture penetration. Clay and quartz promote fracture development, whereas pyrite hinders fracture formation. The fracture inversion model presented here effectively captures the influence of complex mineral distributions on fracture morphology, offering valuable insights for optimizing fracturing production strategies.

Enhanced biological activity of ACPs/cc/cs/PVA composite bone cement: a study on degradation, mineralization, and bone repair properties

The application of calcium phosphate cement in bone repair is often limited by its restricted degradation and mineralization capabilities. Here, we developed a novel composite material integrating amorphous calcium phosphates (ACPs) and calcium citrate (CC) to enhance biological activity. The composite was combined with powdered chitosan (CS) and liquid polyvinyl alcohol (PVA) to formulate the ACPs/CC/CS/PVA bone cement. We investigated the influence of varying PVA concentrations (0.3%, 0.6%, 1.0%, and 1.5%) on the cement’s setting time, hydrophilicity, compressive strength, pH, calcium release rate, and degradation rate. We find the ACPs/CC/CS/PVA bone cement demonstrates favorable injectability and anti-washout characteristics within the PVA concentration range of 0.3–1.5%. An elevated PVA concentration is correlated with enhanced anti-washout properties and improved compressive strength, reaching 42.8 MPa, which is essential for maintaining mechanical stability at the defect site. Additionally, the 1.5% PVA cement formulation ensures an adequate calcium ion concentration (6.5–9.5 mg/L) for the beginning of bone repair. Furthermore, in vivo animal studies have confirmed the biocompatibility of the ACPs/CC/CS/PVA bone cement. Controlled release of Ca2+ and PO4 3− ions from ACPs is suggested to facilitate osteoconduction and osteogenesis, highlighting the material’s prospect in bone repair applications.

NUTRITIVE AND ANTI-NUTRITIONAL VALUES OF SKINNED EDIBLE BULLFROG PYXICEPHALUS ADSPERSUS FOR AQUAFEED

An investigation on proximate, mineral and anti-nutrition properties of Pyxicephalus adspersus was conducted with the view to evaluating its appropriateness as aquafeed source and food source. Standard analytical methods were used to determine proximate, minerals (macro and micro nutrients) and selected anti-nutrients. Pyxicephalus adspersus samples were purchased and treated to skinning and oven drying at 60oC. Triplicate samples were analysed. The proximate composition showed crude protein content of 34.29%, ash 8.18%, while dry matter, moisture, crude fibre, crude lipid, and NFE were 93.12%, 5.60%, 11.82%, 16.79% and 22.04%, respectively. Pyxicephalus adspersus was found to have values (mg/100g) of phosphorus 29.20, calcium 10.60, potassium 4.52, sodium 1.50, and magnesium 1.28. Anti-nutritional compositions (mg/100g) were 5.40, 2.68, 2.06, and 3.05 for tannin, oxalate, saponin and alkaloid, respectively. This result shows that Pyxicephalus adspersus could be used as protein source in meeting aquafeed standard without adverse effects. The crude protein (34.20%) content can be used to substitute the most expensive fishmeal in aquafeed and livestock. Also, the carbohydrate content of 22.04% suggests that it is a good source of energy.

Mineral and Microbial Properties Drive the Formation of Mineral-Associated Organic Matter and Its Response to Increased Temperature.

A comprehensive understanding of the formation of mineral-associated organic matter (MAOM) is a prerequisite for the sustainable management of soil carbon (C) and the development of effective long-term strategies for C sequestration in soils. Nevertheless, the precise manner by which microbial and mineral properties drive MAOM formation efficiency and its subsequent response to elevated temperature at the regional scale remains unclear. Here, we employed isotopically labelled laboratory incubations (at 15°C and 25°C) with soil samples from a ~3000 km transect across the Tibetan Plateau to elucidate the mechanisms underlying MAOM formation and its temperature response. The results indicated that both mineral protection and microbial properties were critical predictors of MAOM formation across the geographic gradient. The efficiency of MAOM formation was found to increase with the content of iron (Fe) oxides and their reactivity [i.e., the ratio of poorly crystalline Fe oxides to total Fe oxides (Feo:Fed)] but to decrease with the relative abundance of Gammaproteobacteria and Actinobacteria across the plateau. Moreover, a notable decline in MAOM formation efficiency was observed under elevated temperatures, which was concomitant with a reduction in the content and reactivity of Fe oxides, as well as the microbial assimilation of the labelled substrate. The attenuation of mineral-organic associations was identified as the primary factor contributing to the warming-induced reduction in MAOM formation. These findings highlight the necessity of incorporating organo-mineral associations and microbial properties into Earth System Models to accurately project soil C dynamics under changing climate.

Thermoelastic Properties of Seifertite at High Pressures and Temperatures: Implications for Negative Velocity Discontinuities in the D" Layer

AbstractNegative velocity discontinuities are often observed at the base of the D'' layer, yet their formation mechanisms remain elusive. Here, we present the first investigation of thermoelastic properties of SiO2‐seifertite under 30–200 GPa and 1,000–4,000 K using first‐principles molecular dynamics simulations. We find that the compressional and shear wave velocities of seifertite are 2.0%–4.3% and 7.4%–11.3% lower, respectively, than those of CaCl2‐type SiO2 in the D'' layer. The reductions in VS across the phase transition are significantly larger than previous estimates from density functional theory results. Incorporating the elastic properties of other minerals, we demonstrate that the presence of SiO2 in the accumulated subducted oceanic crust and the associated VS reductions can contribute to the negative velocity discontinuities observed in the D'' layer. The observed low seismic velocities at the base of the lower mantle can be matched if 19–27 vol.% SiO2 is present in the D'' region.

The Photothermal Synergistic Mechanism of Rock Varnish Photoconductance Under Laser Irradiation.

Rock varnishes, complex structures formed by long-term deposition on rocks, exhibit unique light absorption characteristics and are widely distributed across arid environments on Earth's surface. The varnishes possess the ability to absorb and convert photons from solar radiation into electrons, which represents a newly discovered fundamental energy form in nature, with further elucidation required regarding the underlying mechanism of how semiconductor minerals respond to light radiation. The regulations governing the photoconductive responses of samples from the Alashan region in Gobi, China, and the mechanisms exhibited by rock rock varnishes under various bias voltages and irradiation wavelengths (532 nm, 808 nm, and 1064 nm) were studied. The photoconductivity response is positively correlated with the applied external bias, and the response caused by shorter wavelengths is larger. The synergistic effect was quantitatively assessed by monitoring and fitting the correlation between photoconductivity, temperature, and time during laser irradiation. As an effective method to study the fundamental physical properties of semiconductor minerals, the photoconductivity testing will help to establish a fundamental framework for investigating the intrinsic physical characteristics of natural rock varnishes.

Comparison of the efficacy of carbonation and conventional curing for remediation of copper-contaminated soils by ladle slag

Soil contamination poses an increasing challenge for global sustainable development. Traditional remediation methods, such as using ordinary Portland cement (OPC) for treating contaminated soils, are limited by high CO2 emissions, significant energy consumption, and natural resource depletion. A sustainable approach utilizing steel production waste (ladle slag, LS) to efficiently remediate copper (Cu)-contaminated soils was proposed in this study. The efficacy of this remediation using carbonation and conventional curing methods was compared. Cu-contaminated soils, spiked with varying initial concentrations, were treated with 10 % LS and subjected to both conventional and carbonation curing for different durations. Leaching behavior, strength development, and chemical and mineral properties of LS-remediated Cu-contaminated soils were assessed. The results demonstrated that both CO2 and conventional curing significantly reduced Cu leaching in contaminated soils by 4–5 orders of magnitude compared to untreated soils. CO2 curing achieved these reductions in a shorter time (56–72 hours) than conventional curing (28–56 days). Additionally, CO2 curing sequestered up to 8 % CO2 in the soils. However, higher Cu concentrations hindered carbonation reactions, lowering CO2 sequestration. While CO2 curing improved soil strength, increased initial Cu concentration diminished this effect. During CO2 curing, the formation of Ca- and Mg-carbonates contributed to microstructural densification and binding, thereby improving strength. These carbonates also encapsulated Cu, preventing its leaching. In contrast, the addition of Cu enhanced hydration reactions and improved the strength development of Cu-contaminated soils subjected to conventional curing. Conventional curing produced calcium aluminum silicate hydrate, which effectively bound soil particles, filled pores, and encapsulated Cu, reducing its leaching.

Investigation on the development of Novel PAM structure as high-performance clay inhibitor in HT/HP conditions by using functional groups

Polyacrylamide (PAM) molecular structures are not stable at higher temperatures, limiting their effectiveness in water-based drilling fluid (WBDF) applications. This study focuses on identifying functional groups that can enhance the thermal stability of PAM structure. It presents a comprehensive and comparative analysis of the swelling inhibition capacity of both low and high molecular weight (MW) PAM-based polymers at high temperature and high pressure (HT/HP). The mechanism by which modified PAM interacts with and adsorbs to the clay (Na-MMT) surface is examined, along with an analysis of the surface properties of the clay minerals. Therefore, molecular dynamic (MD) simulation results revealed that the Novel PAM polymers with high MW containing ethyl and benzyl groups demonstrate greater stability and more controlled deformation behavior compared to conventional PAM at HT conditions. Surface modification and hydrophobic effects were observed in the interactions between polymers and Na-MMT. Low MW PAM-based polymers showed larger fluctuations in d-spacing, indicating various or more disruptive interactions. In contrast, the insertion of high MW PAM-based polymer resulted in significantly narrower and lower d-spacing fluctuation ranges. The Novel PAM exhibited superior performance, providing lower d-spacing fluctuations compared to both low MW PAM-based polymers and standard PAM. Across a temperature range from 300 to 600°K, the Novel PAM consistently improved polymer adsorption on the Na-MMT surface compared to standard PAM. Indicating that the modifications effectively reduce the interaction between Na-MMT particles and water molecules while enhancing the interaction between the polymer and Na-MMT, potentially leading to more stable structures in HT/HP environments. The enhanced stability suggests that Novel PAM is more suitable for WBDF applications, as it is less prone to structural changes and can maintain its integrity under harsh conditions. The modifications provide the polymer with better resilience, potentially leading to improved performance in practical applications.

Flotation performance and adsorption mechanism of monazite after the transformation of hydrogen-based mineral phase by octyl hydroxamic acid

This study investigated the laws affecting flotation properties of monazite minerals after roasting pretreatment. The flotation performance and adsorption mechanism of monazite after roasting were investigated systematically through simulation tests, which included micro-flotation tests, Brunauer–Emmett–Teller (BET) analysis, contact angle measurement, zeta potential analysis, scanning electron microscopy energy dispersive spectroscopy, Fourier transform infrared analysis, X-ray photoelectron spectroscopy, and DFTB+. The results of the microflotation tests indicated that octyl hydroxamic acid (OHA) had a superior recovery effect on monazite at a pH of ∼9. The flotation performance of OHA on monazite was significantly better than those of salicylhydroxamic acid (SHA) and benzohydroxamic acid (BHA) under the same conditions. A molecular model of monazite after roasting was simulated and structurally optimized using DFTB+. The adsorption energies were calculated for SHA, BHA, and OHA, which confirmed the strong and stable adsorption of OHA on the surface of monazite after roasting.

Why can Palhinhaea cernua (lycophyte) grow closer to fumaroles in highly acidic solfatara fields?

Palhinhaea cernua, a lycophyte, and Dicranopteris linearis, a fern, are commonly observed in solfatara fields in Kyushu, Japan, but their distribution trends are different. The aim of this study was to determine why P. cernua is more abundant in areas closer to fumaroles from both a soil and plant perspective. Samples of P. cernua and D. linearis, as well as their respective growing soils, were collected, and the mineral properties, including the concentration of various mineral elements and inorganic anions and δ15N, were determined. P. cernua was better adapted to soil with lower pH, higher soluble aluminum concentrations, and poorer calcium and phosphorus concentrations than D. linearis. A positive correlation was observed between shoot nitrogen concentration and both shoot sulfur concentration and soil water-soluble sulfur concentration in P. cernua, implying the involvement of sulfur in nitrogen acquisition in P. cernua. The results also suggested that D. linearis mainly uses soil NO3-N, while P. cernua uses NH4-N, which is predominant and excessive in the solfatara fields, particularly near the fumaroles. This high preference for NH4-N in P. cernua was confirmed through a cultivation experiment. While D. linearis prefers NO3-N and distributes further from fumaroles, P. cernua may have survived in the solfatara fields by utilizing NH4-N and sulfur, which are abundant near fumaroles where competition from other plant species is minimal.

Sorption-desorption of rare earth metal cations by ferromanganese crusts of Govorov’s guyote of the Magellanic Mountains of the Pacific Ocean

The article presents the results of experimental studies on the sorption and desorption of rare earth metal (REM) cations by cobalt-rich ferromanganese crusts (CMC) of Govorov’s guyot. It has been established that the sorption of REM cations occurs on the ore minerals KMK – Fe-vernadite, vernadite, Mn-feroxygite, goethite. The crusts are characterized by a high exchange capacity – 1.78–3.57 mg-eq/g, which increases in a series: (Dy Gd Lu Sm Nd Y, La Eu) Ce. The sorption of REM cations proceeds by an ion exchange equivalent irreversible mechanism. The exchange complex of ore minerals consists of Na+, K+, Ca2+, Mg2+ cations, which contribute 97‒98% to their total capacity. The crusts are characterized by the group sorption of REM cations from multicomponent aqueous solutions of metal salts. The selectivity of ore manganese and ferruginous minerals of crusts to REM cations is significantly higher than to the main cations of ocean water. From experimental data on the desorption of sorbed REM cations with NaCl solution, their irreversible absorption by ore minerals follows, and the strengthening of the chemical bond of sorbed REM cations with the main structural elements of these minerals over time. An important property of ore minerals, primarily manganese minerals, is their chemical and structural stability in aqueous solutions of electrolytes. This suggests the repeated use of ferromanganese crusts as sorbents of REM cations.