Concentrations Of Elements Research Articles

Microstructure-based simulation of constitutive behaviors in friction stir additive manufacturing

The Complex reheating phenomenon during friction stir additive manufacturing (FSAM) has a significant impact on the microstructural evolution. This, in turn, affects its mechanical properties. A flow stress model including the precipitate, solid solution and dislocation density evolution was proposed to reveal the relationship between the microstructure and constitutive behavior in FSAM of Al-Mg-Si alloys. The microstructure and mechanical properties of single-layer and multi-layer FSAM were investigated using experimental and numerical simulation methods. The results revealed that during the first reheating process, the precipitates exhibited dissolution and coarsening behavior in the heating stage. In the third reheating process, precipitates were generated during the heating stage because of the lower temperature. The multiple reheating process in FSAM promoted the generation of precipitates in the stirring zone. This phenomenon increased the yield strength from 183.46 MPa to 189.95 MPa. Meanwhile, the precipitate nucleation and growth during reheating process depleted the concentrations of Si and Mg in the matrix. A comparison of the stress-strain curves before and after the reheating process, revealed that the reheating process reduces the net flow stress in the plastic deformation stage. A decrease in the concentration of solid solution elements caused a decrease in the statistically stored dislocation density, and thereby, decreased the net flow stress.

A hydrogeochemical and isotopic approach for assessing the origin, recharge and mixing process of geothermal water in the Yinchuan Basin

The hydrogeochemistry of geothermal fluids is fundamental to reveal the genesis, recharge mechanism and circulation pattern of geothermal water. However, the origin and hydrogeochemical process of geothermal water in deep aquifer system still remain unclear. In this study, 17 water samples were analyzed to study the origin, recharge and mixing process of geothermal water in the Yinchuan basin by using a hydrogeochemical and isotopic approach. The results showed that the concentrations of major ions (SO42−, Na+, Cl−, TDS, Ca2+, K+, Mg2+ and NH4+) and trace elements (Li, F−, Br−, I−, Sr and Mn) in geothermal water are significantly greater than those in shallow water, hot spring and cold spring in the study area. The hydrochemical type of geothermal water is dominated by Cl·SO4-Na, which is mainly influenced by dissolution of halides, chlorides and sulfates under strong fluid-rock interactions. The isotope analysis demonstrated that the atmospheric precipitation in the Helan Mountain area is the major recharge source of geothermal water, the recharge elevation is 1118 m–1133 m, and the deep geothermal water is formed by a mixing process of ancient precipitation and modern precipitation. The silica-enthalpy mixing model suggested that the reservoir temperature of deep geothermal fluid is between 110 °C and 175 °C, and the mixing ratio of cold water is about 54 % to 92 %. The present study sheds some light on the genesis, recharge mechanism and hydrogeochemical evolution of geothermal water in deep aquifers, which are vital for sustainable exploitation and utilization of geothermal resources.

Investigation into the purification and regeneration of rare earth polishing powder waste via continuous solid-phase conversion

The concentration of rare earth elements (lanthanum, cerium, and praseodymium) within rare earth polishing powder waste (REPPW) typically exceeds 50 %, with the majority of impurities comprised of silicon and aluminum-related compounds. Transforming REPPW into recycled rare earth polishing powders that adhere to polishing standards in an eco-friendly and economically viable way presents a significant challenge in the industry. Traditional acid or alkaline processes predominantly recover rare earth elements as oxides, which are underutilized due to their high costs. Considering the varying forms of impurities and rare earth compounds found in REPPW, this research introduces a novel physicochemical decontamination and continuous chemical transformation process aimed at producing regenerated rare earth polishing powders. Under optimal conditions, the physicochemical two-step decontamination process achieved a rare earth recovery rate surpassing 92 %, while silicon and aluminum removal rates reached 86.12 %. During the continuous chemical transformation of REPPW, the rare earth phases in an alkaline setting followed the sequence REOF (CeO2) → RE(OH)3 → RECO3OH→RECO3F→CeLa2O3F3(CeO2), which not only facilitated phase reorganization but also enhanced the particle surface structure. Notably, these chemical transformations did not disrupt the rare earth distribution; instead, they indirectly boosted product purity and uniformly dispersed within the regenerated polishing powder particles, thereby improving polishing efficiency. Consequently, the adoption of this innovative regeneration process for polishing powders holds substantial importance for the sustainable utilization of rare earth resources.

Effects of biological and environmental filtering on the community assembly of two grasslands in southern Mexico

AbstractQuestionsCommunity assembly is envisaged as filters that preclude some species in the regional pool from invading local communities. We tested whether the large floristic differences between adjacent calcicole and calcifuge grasslands are explained by either of five filters: environment (soil) or positive or negative interactions with plants and with soil biota.LocationSouthern Mexico.MethodsWe conducted a reciprocal‐transplant experiment with 20 species that were introduced to both habitats under three conditions: intact local community, without plants, and in sterilized plots. Each of the five filters mentioned above predict unique patterns in the performance (survival and growth) of plants in the six treatments. Thus, we used multimodel inference to determine which filters (patterns) were consistent with the evidence.ResultsWe detected at least one filter operating on all but four species. Survival data showed frequent support for environmental filtering, with interactions (mostly positive) playing a secondary role; however negative interactions became as frequent as environmental filtering when growth was considered.ConclusionsThe large physicochemical differences between the soils of both grasslands explain the high frequency of environmental filtering. Soils differed in nutrient availability, but also had toxic concentrations of different elements. Survival was strongly influenced by early mortality, while size was measured at the end of the experiment. It is thus likely that the differences between analyses based on survival and size reflect an ontogenetic change from positive to negative interactions. Other plants frequently facilitate seedlings, but this interaction often turns competitive over time. Soil mutualists provide nutrients that seedlings cannot access, but antagonists build up in the rhizosphere as plants age. Unlike studies that infer filters from extant plants in communities or from successful invasions, our approach provides direct evidence on which filters cause species to be absent from communities.

High-performance red mud as an electrocatalyst for nitrate reduction toward ammonia synthesis

Red mud (RM) is a solid waste generated in the aluminum industry after the extraction of alumina oxide; its multiple elements and higher pH value likely pose a severe threat to the environment after treatment. However, RM's higher concentrations of metal components, particularly Fe2O3 and rare earth elements (REEs), render RM promising for catalytic application. Hence, this work showed an efficient high-speed RM to catalyze electrocatalytic nitrate-to-ammonia reduction reaction (NARR). RM calcined at 500 °C (RM-500) exhibited excellent catalytic performance. Faradaic efficiency of ammonia (FENH3) in an electrolyte solution containing 1 mol/L NO3− achieved a maximum value of 92.3% at −0.8 V (vs. RHE). Additionally, 24-hour cycle testing and post-reaction PXRD and SEM indicated that the RM-500 electrocatalyst is stable during NARR. The RM-500 demonstrated a high FE of NH3-to-NO3− of 89.7% at 1.85 V (vs. RHE), showing great potential in the ammonia fuel cells technology and achieving the nitrogen cycle.

Assessment of proximate composition, mineral element profile and antioxidant properties of the edible oyster mushroom grown in Bangladesh

Mushrooms have been considered as a therapeutic and nutrient-rich foods in numerous countries for years due to their significant levels of nutritional components, vitamins and antioxidants. This study aimed to assess the nutrient content, mineral profile and antioxidant properties of eight different kinds of oyster mushrooms (Pleurotus sp.) cultivated in Bangladesh. The mushrooms were analyzed for their moisture content, carbohydrates, proteins, fats, fibers, ash, vitamin A, and vitamin C. The mineral profile included sodium, potassium, calcium, and iron, as well as heavy metals. Antioxidant activities were evaluated through various methods, including phenolic, flavonoid and tannin content, total antioxidant activity, and DPPH (2,2-diphenyl-1-picryl-hydrazyl) scavenging capacity. The findings revealed that the mushrooms under investigation were high in carbohydrate (ranges between 45.25 and 63.22 g/100 g), protein (23.48–33.16 g/100 g) and dietary fiber (42.87–52.31 g/100 g). The total ash content was ranged from 7.28 to 9.41 g/100 g and vitamin C content was 0.020–0.416 mg/100 g. Interestingly, all of the mushrooms had a lower fat content (0.91–2.6%). The mineral profile indicated the presence of varying concentrations of essential elements. Hazardous heavy metals, such as Cd and Cr were not detected in the mushroom sample, while As and Pb were detected but lower than the tolerance levels. The oyster mushrooms exhibited high levels of phenolic, flavonoid, and tannin contents, as well as significant antioxidant capacity. A methanol extract of the oyster mushrooms exhibited scavenging activity against DPPH in a dose dependent manner with the highest capacity (75.4%) obtained at a concentration of 0.2 mg/ml. Our result suggests that these studied oyster mushrooms could be a good source of nutrition and antioxidants, which could be used as functional foods.

Trace element transport by volcanic gases at Vulcano (Sicily, Italy) – Speciation, deposition and fluxes

The geochemistry of trace elements in volcanic gas emissions at Vulcano (Sicily, Italy) was investigated. Trace element concentrations in 94–412 °C fumarole gases span over 10 orders of magnitude, from ~0.01 pmol/mol to ~300 μmol/mol, with some metalloids (B, Si) being the most abundant, followed by alkali, alkaline earth, and certain transition metals, and rare earth elements typically displaying the lowest concentrations. Thermodynamic modeling predicts most trace elements to be transported as chloride, hydroxide, and mixed hydroxy-chloro gas species (LiCl, KCl, NaCl, RbCl and CsCl, Be(OH)2, Mg(OH)2, MgCl2, CaCl2, SrCl2, CaCl(OH), TiOCl2, VOCl, VOCl2, VOCl3, NbOCl3, Cr(OH)3, CrCl3, Fe(OH)2, FeCl2 Co(OH)2, CoCl2, Ni(OH)2 to NiCl2, Cd(OH)2, CdCl2, Re(OH)3, ReCl3, ZnCl2, AgCl, WO2(OH)2, Al(OH)3, Si(OH)4, B(OH)4, TlO, GaCl3, SbCl, MnCl2, CuCl). Sulfide, hydrate, and elemental gas species are also important for some elements (Cd, AuS, Hg, PbS2, BiS, Bi, AsS, As2S3, TeS, SeH, SeS). However, for many trace elements, speciation remains uncertain or unknown due to a lack of thermodynamic data. Upon cooling and decompression of the volcanic gas, most trace elements are predicted to reach gas-solid equilibrium, resulting in the formation of secondary minerals. At high temperatures (~700–1000 °C), the mineral assemblage forming is dominated by quartz, Ca-Na-K feldspars, and Mg-pyroxene, containing minor concentrations of other alkali and alkaline earth metals. Further cooling and decompression leads to the formation of minerals including magnetite, pyrite, chalcocite, and chalcopyrite together with other less abundant oxides (V, Cr, Ga, W, and Sn) and sulfides (Zn, Pb, Ni, Co, Cd, Mo, Ag, As, and Bi), and eventually a range of sulfates and sulfosalts (Li, K, Na, Rb, Cs, Be, Mg, Ca, Sr, Bi, Mn, Fe, Zn, Pb, and Sn) at the lowest temperatures (~100–300 °C). For most trace elements, fumarole emission concentrations reflect higher gas-solid equilibrium temperatures than those observed during sampling, suggesting gas-solid equilibria at high temperatures followed by incomplete re-equilibration upon further cooling near the surface.Trace element fluxes span over eight orders of magnitude, ranging from >100 kg/day to ~1·10−6 kg/day. Silica, Al, and B consistently exhibit the highest fluxes, followed by alkali and alkaline earth metals, various transition metals and metalloids, with rare earth elements and actinides displaying the lowest fluxes. Generally, the trace element fluxes are lower compared to neighboring Stromboli and Etna, except for Pb, Bi, B, As, Sb, and Te.

Using UAVs to collect filtered water samples for mineral exploration: Will it take off?

The advent of unmanned aerial vehicle (UAV) assisted surface water sampling and ongoing technological advances in sampling and data acquisition, offers many opportunities to conduct high-quality hydrogeochemical surveys with low cost, high efficiency, and reduced human interactions. Hydrogeochemical mineral exploration is one area that could greatly benefit from a UAV sampling revolution, with survey sites often located in highly remote areas with limited existing infrastructure. Currently, a lack of point source filtration and complicated physiochemical data acquisition hinder mainstream UAV deployment in the context of hydrogeochemical studies. The aim of this paper is to provide guidance on effective UAV sampling methods and physiochemical data collection for use in surface water hydrogeochemical mineral exploration. To date, case study surveys have utilized sampling systems where sampled waters are filtered after collection or analyzed for ‘total’ (unfiltered) concentrations. This paper details a methodology for point-source filtration of water samples using a UAV system to recover filter sample aliquots for the determination of ‘dissolved’ (<0.45 μm) trace element concentrations and compares UAV methods to conventional sampling strategies. This study systematically compares the quality of analytical data collected from lakes, ponds, and rivers in the Long Lake area of southern Ontario, using conventional manual sampling (from a boat or canoe) and a series of UAV-based sampling methodologies. The waters sampled within the study area are highly meteoric and show evidence of solute input from water-rock interaction with local country rocks. The results of this study show that in general, conventional sampling methodologies are statistically comparable to samples collected using UAVs. However, there is some evidence of element variation related to lake stratification, with dissolved Cu concentrations higher in samples collected at depth compared to those from the surface. Similarly, samples filtered after collection typically have lower concentrations of Fe and Mn, potentially resulting from precipitation before filtration. An enclosed sampling system offered from peristaltic pumping with in-line filtration removes the potential for contamination from the surrounding environment and from the UAV itself.

Microstructural evolution of high-nickel steel during quenching, lamellarizing, and tempering heat treatment

To investigate the influence of Quenching, Lamellarizing and Tempering (QLT) heat treatment processes on the microstructural evolution of nickel alloyed steel, samples were subjected to quenching at 870 °C, followed by Lamellarizing from 720 °C to 780 °C, and tempering at 580 °C. The results indicate that the QLT treatment produces a multiphase microstructure consisting of tempered martensite and stabilized retained austenite. Lamellarizing at 770 °C produced a more uniform microstructure with reduced low-angle grain boundaries compared to 720 °C. Energy-dispersive spectroscopy (EDS) identified higher alloy element concentrations in retained austenite, contributing to its stability and enhancing low-temperature toughness. The results demonstrate that QLT heat treatment effectively modifies the microstructural characteristics and mechanical properties, offering a method to optimize material performance for specific applications.

The corrosion products of proprietary and generic orthodontic fixed lingual retainers and their in-vitro cytotoxicity.

To assess the corrosion products and cytotoxicity of generic and proprietary fixed lingual retainers (FLRs). Seven FLRs were investigated. Wires were submersed in solution for 34 days, at 37°C, under constant agitation. A proportion of this solution was analyzed to determine the concentration of metallic ions leaching off the wires. The remainder was diluted to 5%, 10% and 20% followed by exposure to human gingival fibroblasts and analysis of cytotoxicity of the wires. Three wires (Dentaflex, Universal, and AZDent) released excessive concentrations of lead, two wires (MeshMark and Orthoflex) released excessive concentrations of nickel, and one wire (Universal) released excessive concentrations of molybdenum into solution. No statistically significant difference was found between the wires analyzed (P = .24). Slight cytotoxicity was noted in only one wire (Dentaflex) at a 20% dilution of eluent. This was also the wire which released the highest concentration of lead into solution. All other wires, at all concentrations, were deemed noncytotoxic, but five samples overall were deemed statistically significant (P < .0024). A statistically significant difference existed between wires (P = .013) and concentrations analyzed (P < .001). Metals were released in differing quantities from all wires, with some elemental concentrations measuring more than that deemed acceptable in drinking water in Australia. A trend toward increased cell viability across samples was found with only one demonstrating cytotoxicity. There was no indication that generic FLRs were more or less biocompatible than their proprietary counterparts.

Effect of Ce co-doping on radiation resistance behavior and laser performance of Er/Yb/Ce co-doped high-phosphorous polarization-maintaining silica fiber

Er/Yb/Ce co-doped high-phosphorus silica fiber core glasses with varying Ce2O3 concentrations were prepared and systematically studied. Based on this research, optimized Er/Yb/Ce co-doped high-phosphorus polarization-maintaining silica fibers were subsequently fabricated using the modified chemical vapor deposition (MCVD) technique and hole drilling method. The study confirmed that there is an optimal range of Ce doping concentrations for spectral performance, Ce doping effectively suppressing the formation of P-related defects during X-ray irradiation, and the dynamic valence state transformation of Ce3+/Ce4+ ions during irradiation enhanced the radiation-resistant properties, as demonstrated through radiation-induced absorption (RIA), electron paramagnetic resonance (EPR), and L3-edge X-ray absorption near edge structure (XANES) spectra. The homemade fiber, with optimized element concentrations, exhibited high laser efficiency comparable to commercial high-power fibers. Furthermore, the radiation-induced background loss of the fiber was 0.16 dB/m under 60 krad γ-rays at a low dose rate of 100 rad/h, and the radiation-induced gain variation (RIGV) was 0.019 dB/krad.

Quantitative Analysis of Complex Aluminum Electrolytes by X-Ray Fluorescence.

The future production of electrolytic aluminum will be characterized by low temperature, low carbon emissions, and environmental friendliness, which will result in a more complex electrolyte system. Real-time analysis of electrolytes can significantly enhance the efficiency of the electrolytic process. However, accurately analyzing the composition of complex aluminum electrolytes online has been a technical challenge. This research primarily focuses on determining the ingredient contents of complex aluminum electrolytes based on elemental concentrations measured using X-ray fluorescence (XRF) according to an applicable standard. Calibration curves were established based on 53 standard samples of complex aluminum electrolytes to establish relationships between XRF fluorescence intensity and real concentrations. Analysis conducted on industrial complex electrolytes confirms that these newly constructed curves effectively reduce relative errors to less than 3%. Additionally, a feasible solution is proposed for determining the cryolite ratio (CR) in aluminum electrolytes using XRF. Results demonstrate an average deviation as low as approximately 0.02, fully meeting industrial production requirements. This technique offers numerous benefits including rapid analysis, ease of use, and cost savings.

Paleo-ecological quality status induced by natural and anthropogenic impacts in the last 2000 years: a multidisciplinary approach in the outer region of Sepetiba Bay (SE Brazil)

PurposeSome marine organisms can be used as Biological Quality Elements to estimate the degree of environmental impact and to monitor the health of benthic habitats. Organisms with mineralized protections, such as benthic foraminifera, can provide helpful information on the evolution of the coastal system over a long period and determine the Paleo-Ecological Quality Status (Paleo-EcoQS). This work aims at reconstructing the Paleo-EcoQS in the heavily anthropized Sepetiba Bay (SB; Rio de Janeiro State, SE Brazil).Materials and methodsThis work is based on a multiproxy approach, including textural, geochemical, and foraminiferal data along the core SP11 retrieved near the Pico da Marambaia (a mountain on the tip of the Marambaia Barrier Island). Geochemical analyses encompassing total organic carbon (TOC), total sulfur (S), total nitrogen (N), calcium carbonate (CaCO3), stable isotopes in organic matter (OMδ13C, and OMδ15N) and elemental concentrations as well as 201Pb, 137Cs, and radiocarbon dating were performed to characterize the Paleo-EcoQS in the bay.ResultsThe values of the Paleo-EcoQS.st (standardized Paleo-EcoQS) index in core SP11 indicate that the paleoenvironmental quality varied from moderate to good between ≈50 AD and ≈1500 AD and from good to high between the ~ 1920s and ~ 1990s. Since the 1990s, the Paleo-EcoQS.st has deteriorated considerably, probably due to the deposition of contaminated dredging material in nearby areas. Ballast water discharge may have introduced alien species, such as Ammonia buzasi, into the SB.ConclusionsThe results obtained in core SP11, compared to those of another core (i.e., SP8) from a nearby area, suggest that the reference level of maximum environmental quality is not always reached in a period before industrialization in coastal ecosystems with significant interaction with the ocean; natural factors, related, for example, to sedimentary dynamic processes or geomorphological changes, can lead to unexpected results.

Effect of inorganic salt composition on strength, microstructure and leaching toxicity of coal-based solid waste backfill materials

This study explores the potential of coal-fired slag, desulfurized gypsum and modified magnesium slag as cementing agents for coal-based solid waste backfill materials. Inorganic salts like CaCl2, Na2SO4 and Na2SiO3 were used as excitants to investigate their combined impact on the mechanical properties, microstructure and leaching risk of hazardous elements from the coal-based solid waste backfill materials. The findings show that the addition of inorganic salt boosts the alkalinity within the liquid-phase reaction system. This disrupted the hydration-blocking membrane, accelerating the dissolution and reaction rate of the silica-alumina mineral components within the cementitious material. Concurrently, the inorganic salt ions consumed the early alkaline hydration products, destroying the hydration reaction equilibrium and facilitating the formation of hydration products like AFt, C-S-H gel, C-A-S-H gel, and Friedel's salt. This increase in the solid-phase volume content and microscopic densities in the reaction system improved the early mechanical properties of the coal-based solid waste backfill materials. Additionally, after a 28-day curing period, the leaching concentration of deleterious elements in the coal-based solid waste backfill material containing inorganic salt components was below the permissible concentration limit of the Class III groundwater quality standard. This eco-friendly backfill material is promising for mine backfilling, a potential substitute for traditional cement-based backfill material.

Honey Enriched with Additives Alleviates Behavioral, Oxidative Stress, and Brain Alterations Induced by Heavy Metals and Imidacloprid in Zebrafish.

Environmental concerns have consistently been a focal point for the scientific community. Pollution is a critical ecological issue that poses significant threats to human health and agricultural production. Contamination with heavy metals and pesticides is a considerable concern, a threat to the environment, and warrants special attention. In this study, we investigated the significant issues arising from sub-chronic exposure to imidacloprid (IMI), mercury (Hg), and cadmium (Cd), either alone or in combination, using zebrafish (Danio rerio) as an animal model. Additionally, we assessed the potential protective effects of polyfloral honey enriched with natural ingredients, also called honey formulation (HF), against the combined sub-chronic toxic effects of the three contaminants. The effects of IMI (0.5 mg·L-1), Hg (15 μg·L-1), and Cd (5 μg·L-1), both individually and in combination with HF (500 mg·L-1), on zebrafish were evaluated by quantifying acetylcholinesterase (AChE) activity, lipid peroxidation (MDA), various antioxidant enzyme activities like superoxide dismutase and glutathione peroxidase (SOD and GPx), 2D locomotor activity, social behavior, histological and immunohistochemical factors, and changes in body element concentrations. Our findings revealed that all concentrations of pollutants may disrupt social behavior, diminish swimming performances (measured by total distance traveled, inactivity, and swimming speed), and elevate oxidative stress (OS) biomarkers of SOD, GPx, and MDA in zebrafish over the 21-day administration period. Fish exposed to IMI and Hg + Cd + IMI displayed severe lesions and increased GFAP (Glial fibrillary acidic protein) and S100B (S100 calcium-binding protein B) protein expression in the optic tectum and cerebellum, conclusively indicating astrocyte activation and neurotoxic effects. Furthermore, PCNA (Proliferating cell nuclear antigen) staining revealed reduced cell proliferation in the IMI-exposed group, contrasting with intensified proliferation in the Hg + Cd group. The nervous system exhibited significant damage across all studied concentrations, confirming the observed behavioral changes. Moreover, HF supplementation significantly mitigated the toxicity induced by contaminants and reduced OS. Therefore, the exposure to chemical mixtures offers a more complete picture of adverse impacts on aquatic ecosystems and the supplementation with bioactive compounds can help to reduce the toxicity induced by exposure to environmental pollutants.

Impact of microbial activity on fluoride release from sediments in areas with high fluoride groundwater: Mechanisms, sources and the lithology diversity

This study explores the interplay between microbial activity and sediment lithology in influencing fluoride release from sediments. Sediment samples, collected from Yuncheng Basin: a region known for significant groundwater fluoride contamination, exhibit fluoride concentrations well above the global average, ranging from 206.2 mg/kg to 780.9 mg/kg. These samples comprising silt, silt loam, and sandy loam, are enriched with minerals such as quartz, calcite, albite, chlorite, and illite.Microbial batch incubation reveals that microbial activity significantly enhances fluoride release, particularly in silt loam sediments. The results from sequential extraction first timely identified that the carbonate-bound and Fe-Al-bound fluoride fractions are the most affected forms of fluoride by microbial activity, highlighting the roles of mineral dissolution and desorption in fluoride mobilization.Further batch incubation experiments demonstrate significant increases in fluoride concentrations, especially in silt loam sediments, indicating the role of microbial processes in accelerating fluoride release. Additionally, the study unveils diverse patterns of dissolved elemental concentrations during incubation, with varying release patterns for calcium, magnesium, iron, aluminum, and manganese. These findings illustrate the complex biogeochemical interactions that govern fluoride mobilization in these sediments.Sequential extraction studies further elucidate the intricate mechanisms of fluoride release, with microbial activity primarily influencing the release of carbonate-bound and Fe-Al-bound fluoride. This study also sheds light on the co-dissolution of fluoride and calcium, offering valuable insights into geochemical processes driven by microbial interactions within the sediment matrix.

Assessment of heavy metal pollution in soil-parent material relationship across ecosystems.

The works of assessing the pollution posed by metals in agricultural areas in developing countries are limited. This study aims to assess metal concentrations and pollution indices of parent materials and soils representing the mantle and oceanic crust units of the ophiolite in the Eastern Mediterranean region, specifically in Kahramanmaraş Province. A total of 88 samples, comprising 44 soil (0-30cm) and 44 parent material (90 + cm), were collected from the study area. Arsenic (As), mercury (Hg), selenium (Se), uranium (U), molybdenum (Mo), tin (Sn), and cesium (Cs) concentrations were analyzed in these samples, along with the reference metal, iron (Fe). Pollution levels were assessed using enrichment factor (EF) and contamination factor (CF) calculations. Results showed that elemental concentrations (Hg, Se, U, Mo, Sn, and Cs) in soils from the mantle and oceanic crust generally reflected those of the parent material. However, the average As concentration in soils from oceanic crust and mantle units was notably elevated, showing a 3 to fourfold increase compared to the parent material. Based on pollution index values, soils from these units demonstrated a moderate level of enrichment (2 < EF < 5) for As, while other elements (Hg, Se, U, Mo, Sn, and Cs) fell into the low enrichment class (EF < 2). Furthermore, the CF index indicated significant contamination (3 < CF < 6) for As. These findings suggest As contamination in soils from different units of the ophiolite (mantle and oceanic crust), potentially resulting from agricultural chemicals like pesticides and fertilizers.

The Impact of Climatic Characteristics on Increasing Soil Salinity in Manathira District Center

The climate plays a crucial role in shaping soil characteristics. High temperatures during summer can lead to increased evaporation of soil moisture, resulting in drier and more fragmented soils. This process often leads to higher salt concentrations, altering the soil's properties. In the study area, the soil is categorized into four types: river shoulder soil, river basin soil, riverine island soil, and desert gypsum soil. These soil types are significantly influenced by environmental factors, both natural and anthropogenic. Soil, being a fundamental component of the environment that supports life, is essential for the survival of humans, plants, and animals. In the Najaf Governorate, the soil is vital for agriculture, supporting the growth of various important crops, including vegetables and fruits. However, the soil's natural and human-induced changes have led to a noticeable deterioration in its quality, rendering much of the land unsuitable for agriculture due to high concentrations of saline elements. The natural factors impacting the soil in the study area include climate, soil properties, and water resources, while human activities have further exacerbated these effects. As a result, the soil, particularly in cultivated and uncultivated basins, has seen a rise in the levels of total dissolved salts, sodium, magnesium, calcium, potassium, sulfate, and chloride, often exceeding global standards. In contrast, the soils of river shoulders have remained within acceptable limits.

Laser-Induced Breakdown Spectroscopy Applied to the Quantification of K, Ca, Mg and Mn Nutrients in Organo-Mineral, Mineral P Fertilizers and Rock Fertilizers

A low-cost laser-induced breakdown spectroscopy (LIBS) instrument equipped with a charge-coupled device (CCD) was tested in the atmospheric environment for the quantification of K, Ca, Mg, and Mn in some organo–mineral fertilizers, mineral P fertilizers, and rock fertilizers of various compositions and origins, using flame atomic absorption spectrometry (FAAS) as the reference technique. The correlation analysis performed between each CCD pixel and the corresponding element concentration measured by FAAS allowed to choose the most appropriate K, Ca, Mg and Mn emission lines for LIBS analysis. The normalization process applied to LIBS spectra to correct physical matrix effects and small fluctuations was able to increase the linear correlation of the calibration curves between LIBS data and FAAS data by an average of 0.15 points of the R-value for all elements of interest. The R values of calibration curves were 0.97, 0.96, 0.86 and 0.84, for K, Ca, Mg and Mn, respectively. The limits of detection (LOD) were 66 mg/kg (K), 35 mg/kg (Ca), 5.4 mg/kg (Mg) and 0.8 mg/kg (Mn) when using LIBS in the quantification model. The cross-validation (leave-one-out) analysis yielded an absolute average error of 12% (K), 21% (Ca), 8% (Mg) and 13% (Mn) when LIBS data were correlated to FAAS ones. These results showed that the calibration models used were close to the optimization limit and satisfactory for K, Ca, Mg, and Mn quantification in the fertilizers and rocks examined.

Boosting photoelectrochemical water splitting performance via nanostructured Ag-CuO thin films

Undoped and doped copper oxide (CuO) with silver (Ag) was prepared using the SILAR technique on the ITO substrate to generate green hydrogen from the water-splitting process. The (−111) and (111) were the most intense reflections of crystallographic planes observed in pure and Ag-doped CuO thin films. Ag doping within the crystal structure of pristine leads to increasing the crystallite size. FESEM images show homogeneity and uniform distribution for the pure and Ag-doped CuO thin films that confirm the particles have small sizes, give more features and are responsible for the target application. The doping process affected the energy band gap where it was 2.2 eV for the pure sample then descended to 1.9 eV as doping reached 5 % concentration of Ag element. The photoelectrochemical testing showed that the Ag 5 % content photoelectrode has a high value of photocurrent density approximately ∼ - 5 mA/cm2.