Search Results (158)

This study evaluates the agronomic potential of two types of vermicompost—one produced solely from wine industry residues (WIR) and one incorporating sewage sludge (WIR + SS)—under rainfed and deficit irrigation conditions in Mediterranean vineyards. The vermicompost was obtained through a two-phase process involving initial thermophilic pre-composting, followed by vermicomposting using Eisenia fetida for 90 days. The conditions were optimized to ensure aerobic decomposition and maintain proper moisture levels (70–85%) and temperature control. This resulted in end products that met the legal standards required for agricultural use. However, population dynamics revealed significantly higher worm reproduction and biomass in the WIR treatment, suggesting superior substrate quality. When applied to grapevines, WIR vermicompost increased soil organic matter, nitrogen availability, and overall fertility. Under rainfed conditions, it improved vegetative growth, yield, and must quality, with increases in yeast assimilable nitrogen (YAN), sugar content, and amino acid levels comparable to those achieved using chemical fertilizers, as opposed to the no-fertilizer trial. Foliar analyses at veraison revealed stronger nutrient uptake, particularly of nitrogen and potassium, which was correlated with improved oenological parameters compared to the no-fertilizer trial. In contrast, WIR + SS compost was less favorable due to lower worm activity and elevated trace elements, despite remaining within legal limits. These results support the use of vermicompost derived solely from wine residues as a sustainable alternative to chemical fertilizers, in line with the goals of the circular economy in viticulture. Full article

A novel single-walled carbon nanotube (SWNT), silver (Ag) nanoparticle, and zinc benzene carboxylate (ZnBDC) metal–organic framework (MOF) composite was synthesised and systematically characterised to develop an efficient platform for mercury ion (Hg²⁺) detection. X-ray diffraction confirmed the successful incorporation of Ag nanoparticles and SWNTs without disrupting the crystalline structure of ZnBDC. Meanwhile, field-emission scanning electron microscopy and energy-dispersive spectroscopy mapping revealed a uniform elemental distribution. Thermogravimetric analysis indicated enhanced thermal stability. Electrochemical measurements (cyclic voltammetry and electrochemical impedance spectroscopy) demonstrated improved charge transfer properties. Electrochemical sensing investigations using differential pulse voltammetry revealed that the SWNTs/Ag@ZnBDC-modified glassy carbon electrode exhibited high selectivity toward Hg²⁺ ions over other metal ions (Cd²⁺, Co²⁺, Cr³⁺, Fe³⁺, and Zn²⁺), with optimal performance at pH 4. The sensor displayed a linear response in the concentration range of 0.1–1.0 nM (R² = 0.9908), with a calculated limit of detection of 0.102 nM, slightly close to the lowest tested point, confirming its high sensitivity for ultra-trace Hg²⁺ detection. The outstanding sensitivity, selectivity, and reproducibility underscore the potential of SWNTs/Ag@ZnBDC as a promising electrochemical platform for detecting trace levels of Hg2+ in environmental monitoring. Full article

In situ testing is essential in geotechnical engineering, providing valuable insights into both soil stratification and material behaviour. This paper illustrates an automated framework for deriving constitutive model parameters from in situ test data. The framework employs a graph-based approach that enhances both transparency and adaptability—transparency by explicitly tracing the computation of each parameter and adaptability by allowing users to incorporate their expertise. The study applies this framework to a marine clay test site, demonstrating its ability to determine soil parameters efficiently. Additionally, the framework is directly integrated into a finite element software, enabling seamless parameter transfer for numerical modelling. A case study is presented in which a shallow foundation is simulated to illustrate the practical application of this approach. This framework is particularly valuable in the early stages of geotechnical projects, providing detailed soil characterisation when site data is limited. Validating the accuracy of the derived parameters and incorporating additional in situ test methods are part of ongoing research. Full article

The composition of wolframite from ores of the Porokhovskoe and Yugo-Konevskoe W greisen deposits in the Central Urals is studied using SEM-EDS and LA-ICP-MS analyses. The Porokhovskoe deposit is localized in a metamorphosed volcanosedimentary sequence of Lower Silurian age, and the Yugo-Konevskoe is enclosed in an eponymous granite pluton of Middle Permian–Lower Triassic age. Most studied wolframite grains belong to hűbnerite. The Fe/(Fe + Mn) value of wolframite varies in a range of 0.02–0.50. Wolframite from both deposits is enriched in Zn, Nb, and Mg. The wolframite from the Porokhovskoe deposit is enriched in V, Sc, Zn, and Mg and is depleted in Mo, U, rare earth elements (REEs), Nb, and Ta, compared to wolframite from the Yugo-Konevskoe deposit. It is suggested that this difference is due to the occurrence of ore veins in different rocks at different distance from the source of the ore-forming fluid, which cools down as it moves away from the source, leading to a decrease in the incorporation of trace elements by the lower-temperature wolframite. The predominance of heavy REEs over light REEs in all the studied wolframite is explained by the close ionic radii of heavy REEs to the main mineral-forming elements Fe and Mn. Full article

Current models of sedimentary environments and organic matter (OM) enrichment for the Lower Cambrian black shales in the Yangtze Platform have not yet incorporated its northern carbonate platform margin where the related research is lacked. This study focuses on the SNZ1 well in the northern carbonate platform margin, utilizing total organic carbon (TOC) content and major and trace element data to reveal the main controlling factors of OM enrichment during the Early Cambrian. The results show that the shale stratum is tentatively ascribed to the Lower Cambrian Stage 3 and that, during its deposition, the redox transitioned from anoxic to suboxic–oxic conditions, the hydrodynamic conditions weakened initially and then strengthened, the primary productivity first increased and then decreased, the paleoclimate shifted from arid–cold to warm–humid conditions, and the terrigenous clastic input gradually diminished. Overall, the OM enrichment is primarily controlled by preservation conditions. By systematically analyzing the data from the intraplatform basin to the deep-sea basin across the Yangtze Block, a model of the sedimentary environments and OM enrichment during the Early Cambrian was suggested. Additionally, this study highlights the intrinsic link between the expansion of oxygenated surface water and the Cambrian explosion. These results provide critical insights for shale gas exploration in this region. Full article

Selenium (Se) is a trace element that is beneficial in enhancing the quality of rice production. However, research on the effects of Se on rice quality under varying nitrogen (N) levels is limited and requires further investigation. This experiment utilized a randomized block design, incorporating an N fertilizer reduction and efficient application mode, with two N levels, CN (225 kg·hm⁻²) and LN (180 kg·hm⁻²), and three Se levels, HSe (0.12 kg·hm⁻²), LSe (0.06 kg·hm⁻²), and 0Se (0.00 kg·hm⁻²). The results indicated that the effects of Se on rice processing quality differ under different N levels. Selenium adversely affected the processing quality under the CN level, whereas it demonstrated some improvement at the LN level. Furthermore, Se application increased the Se content in rice by 46.48–141.82% and enhanced the taste value by 14.88–22.73%. It significantly improved the nutritional and cooking qualities of rice and positively influenced its appearance. Although N levels induced variations, their overall impact remained beneficial. Considering various indicators, applying 0.06 kg·hm⁻² of Na₂SeO₃ under the LN level yielded optimal results. This study provides valuable insights into the effects of Se on rice quality under different N levels. It provides a more scientific basis for the application of selenium fertilizer in rice. Full article

The North China Craton (NCC) experienced extensive destruction and modification of its subcontinental lithospheric mantle during the Mesozoic, a period marked by intensive tectonism, magmatism, and mineralization. Among the key manifestations of this event are the Shizhuzi magmatic complex (SMC) and related Mo-Cu-Au deposits in the Liaodong Peninsula. This study presents new zircon U-Pb ages and Hf isotope data, along with whole-rock major and trace element geochemical data. Meanwhile, by incorporating published datasets, the magmatism and mineralization of the SMC are discussed. Two-stage magmatic activity is identified in the SMC as follows: (1) Stage I (130–126 Ma) associated with mineralization, and (2) Stage II (121–117 Ma), both corresponding to the peak destruction of the NCC. The mineralized granitoids exhibit I-type affinities and formed in an extension setting. Quartz diorites within this suite were derived from the partial melting of an enriched mantle source, and the high-temperature thermal underplating associated with this process subsequently triggered partial melting of the basaltic lower crust, leading to the generation of granodiorites and monzonitic granites. These rocks experienced limited fractional crystallization (dominated by plagioclase + biotite) and are linked to Mo-Cu-Au mineralization. In contrast, the non-mineralized granitoids are high-K calc-alkaline, peraluminous A-type granites, which developed in an extremely extensional tectonic setting. They were derived from partial melting of ancient lower crust and display characteristics of highly fractionated granites, having undergone extensive crystallization differentiation involving plagioclase + K-feldspar during magmatic evolution. The mineralized and non-mineralized granitoids exhibit distinct differences in lithology, major/trace element characteristics, Hf isotopes, and degree of fractional crystallization. Our proposed two-stage magmatic model—coupled with a mineralization phase—provides significant insights into both magmatic processes and metallogenesis in the Liaodong Peninsula. It further offers key perspectives into the Early Cretaceous decratonization of the NCC in terms of its tectonic–magmatic–mineralization evolution. Full article

Selenium (Se) is an essential trace element for the human body, primarily obtained from dietary sources. The unique characteristics of Se-enriched saline–alkali soils provide valuable insights into how plants absorb and accumulate Se. The present study collected and analyzed soybean plants and rhizosphere soil samples from typical Se-enriched saline–alkali areas in Xinjiang, China to investigate how Se-enriched saline–alkali soil and the associated rhizosphere microbial community influence Se absorption in soybeans. Soybean seeds were the primary site of Se accumulation, with the Se content in the seeds being significantly correlated with that in roots (R² = 0.4926). The Se content in soybean roots and seeds increased with the total Se soil content, and a significant correlation was observed between them. Additionally, the available Se content in the soil was significantly correlated with the total Se content (R² = 0.4589). Soil factors such as Na⁺ concentration, pH, and organic matter (OM) were found to influence the structure of the microbial communities. Furthermore, higher abundances of Proteobacteria, Bacteroidota, and Bacillota in the soil were found to mitigate salt stress and enhance Se absorption in soybean plants. Thus, the rhizosphere microbial community significantly enhances soybean Se uptake. This study provides valuable insights into the mechanisms of Se accumulation in soybeans cultivated in Se-rich soils and offers guidance for cultivating Se-enriched crops. However, this study failed to quantify the differential impacts of different Se forms, such as selenite (SeO₄²⁻) and selenate (SeO₃²⁻), on microorganisms and plants. Future research should incorporate a detailed analysis of different Se forms to provide more in-depth insights into these complex interactions. Full article

Axinite crystals from the type locality (Oisans, French Alps) are considered among the more remarkable specimens known for their quality (lustre, colour, size, and purity) and crystalline forms. However, they have been the subject of only a few in-depth studies. This lack of knowledge provided the opportunity for a systematic survey of axinites from Saint-Christophe-en-Oisans, where crystals appear to cover an extensive range of Fe-Mn substitution from an Fe-rich (axinite-Fe) to a Mn-rich field (axinite-Mn) in a same crystal, with compositional variations much more significant than initially described. An in-depth characterisation of the chemical zonation of the crystals using EPMA, Raman spectroscopy, X-ray micro-fluorescence, and LA-ICP-MS was carried out on the crystals showing the most significant variability. The micro-XRF method appeared extremely useful for describing spatial variations in chemical composition at the centimetre scale and preparing other in situ methods. Fe(Mg)-Mn substitution covers a large range but the Mn-enriched growth zones are relatively thin and localised at the periphery of crystals. In addition, chemical zonations highlighted in this study also reveal contrasted incorporation of trace elements as a function of the Fe/Mn ratio (in particular, Be, HREE, Sc, Ga, In, and Co), indicating changes in fluid chemistry during the crystal growth. Full article

Phosphogypsum, a byproduct of phosphate fertilizer production, poses significant environmental challenges due to its large volume, hazardous composition, and radioactivity. Conventional disposal methods, such as stockpiling and landfilling, contribute to soil and water contamination and present risks to human health. This article explores the potential of integrating phosphogypsum into a circular economy framework, focusing on reducing environmental impacts and extracting value from this industrial waste. A detailed assessment of phosphogypsum’s chemical composition, including trace metals and radionuclides, is essential for effective management. This review paper examines safe handling, storage, and disposal strategies to minimize environmental risks. Additionally, innovative reuse applications are investigated, such as incorporating phosphogypsum into construction materials like cement, plasterboard, and concrete and its use in agriculture as a soil amendment or for land reclamation. The recovery of critical elements, particularly rare earth elements (REEs), highlights its potential to reduce waste and contribute to meeting the growing demand for strategic resources. Despite its promise, challenges remain, including chemical variability and the presence of radioactive components. This article identifies the technological and regulatory steps required to enable safe, large-scale reuse of phosphogypsum, emphasizing its role in advancing sustainable resource management within a circular economy. Full article

The chemical composition of FeCrAl alloy significantly influences its thermal-mechanical as well as anti-corrosive properties. This study investigates the impact of silicon and yttrium additions on the thermal-mechanical properties and high-temperature oxidation resistance of FeCrAl alloy. The results indicate that thermal conductivity gradually decreases with the incorporation of Y or Si into the lattice, whereas the mechanical strength of the alloy can be enhanced through the addition of Y. A trace amount of Y can improve the alloy’s high-temperature oxidation resistance by mitigating the spallation of the surface oxidation film and promoting the growth of the film, characterized by heterogeneous chemical composition and microstructure. It is observed that Y possesses a higher charge density than FeCrAl, suggesting that Y can lose electrons more readily than other elements, which implies a reduction in oxygen diffusion. Full article

Trace elemental water chemistry in aquatic systems is primarily derived from the underlying geology of surrounding watersheds. Trace elements can be absorbed from the environment and become permanently incorporated into certain calcified structures of fish. Comparison of the trace elemental chemistry of these structures with the chemical signature of water from the watershed in which a fish was captured can help identify movement patterns. The goal of this study was to create a relatively fine scale baseline for the trace elemental water chemistry of the Chattahoochee, Ocmulgee, Oconee, and Savannah rivers within the Piedmont ecoregion of Georgia, U.S., and to distinguish any trace elements that may be useful in delineating different reaches. Principal component analysis was used to analyze ratios of Ba:Ca, Mg:Ca, Mn:Ca, Na:Ca, and Sr:Ca from samples in each river. Results suggest that Ba:Ca and Sr:Ca ratios may be useful in delimiting river reaches in each system. In addition, Na:Ca and Mn:Ca ratios may have some utility in further differentiating reaches in the Chattahoochee and Savannah rivers, respectively. The ability of these elements to differentiate reaches within these rivers lends support for their utility in fish microchemistry studies to help better understand and manage fish in these systems. Full article

The continuous cooling transformation (CCT) curves of undercooled austenite serve as crucial references for obtaining desired microstructures and properties in metallic materials (particularly deformed metals) through heat treatment. In this study, static and dynamic CCT curves were constructed for experimental steels micro-doped with rare earth element Ce by combining temperature-dilatometric curves recorded after austenitization at 900 °C with microstructural characterization and microhardness measurements. Comparative analyses were conducted on the microstructures and microhardness of three experimental steels with varying Ce contents subjected to sizing (reducing) diameter deformation at 850 °C and 950 °C. The CCT experimental results revealed that the microhardness of the tested steels increased with cooling rates. Notably, dynamic CCT specimens cooled at 50 °C/s to room temperature following superheated deformation exhibited 56.7 HV5 higher microhardness than static CCT specimens, accompanied by increased martensite content. The reduction of deformation temperature from 950 °C to 850 °C resulted in the expansion of the bainitic phase region. The incorporation of trace Ce elements demonstrated a significant enhancement in the microhardness of 30MnNbRE steel. This research proposes an effective processing route for improving strength-toughness combination in microalloyed oil well tubes: introducing trace Ce additions followed by sizing (reducing) diameter deformation at 950 °C and subsequent ultra-fast cooling at 50 °C/s to room temperature. This methodology facilitates the production of high-strength/toughness steels containing abundant martensitic microstructures. Full article

The increasing demand for critical metals essential for renewable energy technologies necessitates efficient and environmentally sustainable extraction methods. Ilmenite (FeTiO₃) and similar ore deposits serve as abundant sources of primary elements while also incorporating a suite of strategically significant trace elements, including REEs and Hf, among others. Mixer–settler units are extensively utilized in metal purification processes. It is important to develop approaches for tracking the metal’s extraction process online and optimizing flow dynamics. One widely adopted technique for evaluating the flow dynamics of the various components is the residence time distribution (RTD) measurement, which provides insights into the hydrodynamic behavior of process reactors. This study explored the application of radiotracer techniques for online monitoring of solvent extraction processes in hydrometallurgy, focusing on Hf recovery. A mixer–settler system was employed using di(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and the 1M HNO₃ aqueous phase of Ti ore. The radiotracer ¹⁸¹Hf was synthesized via neutron activation and introduced into the system to track phase distribution and RTD. Real-time monitoring revealed over 95% extraction efficiency within 133 min (8000 s). The RTD studies validated system performance using perfect mixers in series and axial dispersion models. The calculated mean residence time of 100 min (6000 s) closely aligned with the theoretical 104 min (6240 s), confirming the model accuracy. The findings demonstrate the viability of radiotracers in monitoring solvent extraction, offering real-time insights into flow dynamics and extraction efficiency. Full article

The Cambrian period marks a crucial phase in the initial subduction of the Proto-Tethys Ocean beneath the East Kunlun Orogen. Studying the I-type granites and mafic–ultramafic rocks formed during this period can provide valuable insights into the early Paleozoic tectonic evolution of the region. This paper incorporates petrology, LA-ICP-MS zircon U-Pb geochronology, and whole-rock major and trace element data obtained from the Kekesha intrusion in the eastern section of the East Kunlun Orogen. The formation age, petrogenesis, and magmatic source region of the intrusion are revealed, and the early tectonic evolution process of the subduction of the Proto-Tethys Ocean is discussed. The Kekesha intrusion includes four main rock types: gabbro, gabbro diorite, quartz diorite, and granodiorite. The zircon U-Pb ages are 515.7 ± 7.4 Ma for gabbro, 508.9 ± 9.8 Ma for gabbro diorite, 499.6 ± 4.0 Ma for quartz diorite, and 502.3 ± 9.3 Ma and 501.6 ± 6.2 Ma for granodiorite, respectively, indicating that they were formed in the Middle Cambrian. The geochemical results indicate that the gabbro belongs to the high-Al calc-alkaline basalt series, the gabbro diorite belongs to the medium-high-K calc-alkaline basalt series, the quartz diorite belongs to the quasi-aluminous medium-high-K calc-alkaline I-type granite series, and the granodiorite belongs to the weakly peraluminous calc-alkaline I-type granite series, all of which belong to the medium-high-K calc-alkaline series that have undergone varying degrees of differentiation and contamination. Gabbro and gabbro diorite exhibit significant enrichment in light rare earth elements (LREEs), depletion in heavy rare earth elements (HREEs), and an enhanced negative anomaly in Eu (Europium). Compared to gabbro and gabbro diorite, quartz diorite and granodiorite exhibit more pronounced enrichment in LREEs, more significant depletion in HREEs, and an enhanced negative anomaly in Eu. All four rock types are enriched in large-ion lithophile elements (LILEs) such as Cs, Rb, Th, Ba, and U, and are depleted in high-field-strength elements (HFSEs) such as Nb, Ta, and Ti. This indicates that these rocks originated from the same or similar mixed mantle source regions, and that they are formed in the island-arc tectonic environment. This paper suggests that the gabbro and gabbro diorite are mainly derived from the basic magma formed by partial melting of the lithospheric mantle metasomatized by subducted slab melt in the oceanic crust subduction zone and mixed with a small amount of asthenosphere mantle material. Quartz diorite results from the crystal fractionation of basic magma and experiences crustal contamination during magmatic evolution. Granodiorite forms through the crystal fractionation of basic magma, mixed with partial melting products from quartz diorite. While the lithology of the intrusions differs, their geochemical characteristics suggest they share the same tectonic environment. Together, they record the geological processes associated with island-arc formation in the East Kunlun region, driven by the northward subduction of the Proto-Tethys Ocean during the Early Paleozoic. Based on regional tectonic evolution, it is proposed that the Proto-Tethys Ocean began subducting northward beneath the East Kunlun block from the Middle Cambrian. The Kekesha intrusion formed between 516 and 500 Ma, marking the early stages of Proto-Tethys Ocean crust subduction. Full article