Concentration Distribution Of Elements Research Articles

A semi-arid climate's use of exploratory data analysis (EDA) as a reliable non-parametric method for geochemical mapping

In this study, exploratory data analysis (EDA) methods, specifically boxplots, were employed to examine the composition of stream sediments in the Collo area of Northeast Algeria. The region's diverse lithological formations, interactions between permanent and temporary watercourses, intermittent flash floods, rugged topography, and fluctuating climatic conditions contribute significantly to data variability. Utilizing the boxplot's capabilities, our analytical approach successfully identified outliers, recorded the actual distribution of data, and determined skewness without the need for prior data processing, often required in conventional statistical studies. The boxplot proved to be an effective tool, offering insights into the geographical distribution of elemental concentrations, including iron (Fe), zinc (Zn), copper (Cu), arsenic (As), chromium (Cr), and lead (Pb). Geochemical mapping, driven by a robust class selection mechanism developed from the boxplot, revealed strong geographical correlations. A notable northeastern anomaly, characterized by elevated concentrations of Pb, Zn, Cu, and As, aligned with known base-metal sulfide and arsenopyrite mineralization sites. Additionally, outlier data for Cr indicated proximity to a plagioclase-lherzolite intrusion and known chromite deposits. The geographical distribution of iron, corresponding with known magnetite and hematite resources, was effectively highlighted using robust class selection based on boxplot analysis. This comprehensive investigation underscores the value of EDA methods in identifying mineralization trends amid the complex variability of the Collo area.

Sources and distribution of trace elements in surface snow from coastal Zhongshan Station to Dome A (East Antarctica)

The spatial distribution and possible sources of Al, As, Cd, Fe, Mn, Pb, Sb, Ti, V, and Zn were investigated in 120 samples of surface snow collected along a ∼1260 km long traverse from coastal Zhongshan Station to the Antarctic ice sheet summit (Dome A or Dome Argus, at 4093 m a.s.l.). The chemical composition of snow samples was analyzed using microwave-assisted acid treatment with HNO3/HF to determine element concentrations, reflecting their abundance in the Earth's crust. The observed relative concentration pattern of elements in snow suggests a predominant contribution from soil and rock dust particles. The spatial distribution of total element concentrations along the traverse revealed higher values in inland areas compared to coastal areas. The annual deposition flux of elements in each sampling site indicates a significant decreasing trend in Al, Ti, Zn, Fe, Cd, As, and Pb from the coast to inland areas. Significant variations in element concentrations and fluxes observed along the Antarctic traverse suggest a notable influence of distance from the coast on snow deposition patterns. Soil dust from coastal ice-free areas and human activities in scientific stations are the primary sources of analyzed elements in coastal snow, with marine biogenic emissions playing a marginal role, likely contributing to As and Cd. The contribution of sea salt spray to surface snow element concentrations in the East Antarctic traverse is negligible. An analysis of backward trajectories confirmed that long-distance transport from the South American continent and local Antarctic research stations potentially contributes to Antarctic snow elements.

Phase Fraction Estimation in Multicomponent Alloy from EDS Measurement Data.

To perform quality assessments of both metal alloys and many other engineering materials, measurements of the volume fractions of phases or microstructure components are utilized. For this purpose, quantitative analysis of the evaluated components' distribution on metallographic specimens is often employed. Phases or components of the microstructure are identified based on the variation in signal received in the band of light seen. Problems with the correct identification of measurement results in this spectral band can be caused by the inhomogeneity of the etching when the alloy components are segregated. Additional uncertainty arises when the analyzed image pixel contains a boundary between grains of different phases. This article attempts to use the results of local chemical composition measurements as a source signal for quantitative evaluation of phase composition. For this purpose, quantitative maps of elemental concentration distributions, obtained with a Tescan Mira GMU high-resolution scanning electron microscope in QuantMap mode, were used as input data for the phase composition evaluation of an EN AC 46000 alloy sample. The X-ray microanalysis signal generation area may contain grains of more than one phase. Therefore, evaluation of the phase fractions in areas of individual measurements were calculated by looking for the minimum of the objective function, calculated as the sum of the squares of the deviations of the results of measurements of the concentration of individual elements from the weighted average values of solubilities of these elements in the phases.

Phase composition and numerical model of low-pressure pulse carburized layer in 15Cr14Co12Mo5Ni2W steel

Aerospace engine gear steel, 15Cr14Co12Mo5Ni2W steel, requires carburizing heat treatment to achieve operational performance. However, predicting the carbon concentration during the vacuum carburizing process poses significant challenges. This paper aims to design and establish a predictive model for the carbon concentration during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel. Given the complex phase transformations during the vacuum carburizing process caused by the ultra-high alloy content of 15Cr14Co12Mo5Ni2W steel, vacuum short-term intense carburization and diffusion experiments were designed. Characterization methods such as XRD, scanning electron microscopy, electron probe microanalysis, EBSD, and FIB+TEM were used to study the microstructure, phase composition, phase constituents, and distribution of element concentrations during the vacuum carburizing process. Subsequently, a carbon concentration distribution calculation model considering carbide changes during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel was established. Boundary conditions for carbon absorption during the intense carburization process of 15Cr14Co12Mo5Ni2W steel were proposed, and the relationship between surface carbon concentration and boundary conditions was determined through experiments. Using the method of forward calculation with least squares fitting of experimental data, the diffusion coefficient of carbon in the austenite of 15Cr14Co12Mo5Ni2W steel and the rate of carbon exchange between carbides and the matrix were derived, providing a more precise predictive tool for optimizing the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel.

Concentration-Gradient Structural LiFe0.5Mn0.5PO4/C Prepared via Co-precipitation Reaction for Advanced Lithium-Ion Batteries.

The intrinsically low electronic conductivity and slow ion diffusion kinetics limit further development of olivine LiFexMn1-xPO4 cathode materials. In this paper, with the aim of improving the performance of such materials and alleviating the Jahn-Taller effect of Mn3+ ion, a bimetallic oxalate precursor with gradient distribution of elemental concentration followed with an efficient process is applied to synthesize LiFe0.5Mn0.5PO4 nanocomposite. The results shown that with certain structural modulation of the precursor, the discharge capacity of synthesized LiFe0.5Mn0.5PO4 increased from 149 mAh g-1 to 156 mAh g-1 at 0.1 C, the cycling capacity was also remarkably improved. the Fe0.5Mn0.5C2O4 ⋅ 2H2O-1 precursor with gradient distribution of elemental concentration effectively restricts the reaction between electrode material and electrolyte, thereby alleviates the dissolution of Mn3+ ion, reduces the decay of capacity and improves the stability of the material.

Conditions of formation of Vikhoreva river and Ust-Vikhorevsky bay hydrochemical regime (Ust-Ilimsk reservoir)

Relevance. The necessity to control the hydrochemical regime of water bodies significantly affected by anthropogenic impacts. Aim. To study the spatial distribution of major ions and trace element concentrations and identify natural and anthropogenic formation factors of the hydrochemical composition of the Vikhoreva river and Ust-Vikhorevsky bay of the Ust-Ilimsk reservoir. Objects. Waters of the Vikhoreva river before and after inflow of wastewater from the Bratsk industrial zone, waters of the Ust-Vikhorevsky bay (Vikhorevskaya and Burdoyskaya parts) of the Ust-Ilimsk reservoir. Methods. Determination of micronutrients concentrations in water was performed by inductive coupled plasma mass spectrometry, mercury – by atomic absorption method. Cations and anions were determined using standard methods accepted in hydrochemical studies, Sorg – by titrimetric method, oxygen – by iodometric method. Results. In the Vihoreva river water after wastewater inflow from the Bratsk industrial zone, significant transformations of its hydrochemical composition were detected. Along the water area of river decrease of O2 concentrations (up to 0.3 mg O2/l) and increase of Сorg (up to 131 mg/l), SO42– (up to 262 mg/l), K+ (up to 10.6 mg/l), Cl– (up to 220 mg/l), Na+ (up to 240 mg/l), Mn (up to 248.5 mg/l), Cr (up to 7.4 mg/l), to a lesser extent Al (up to 224.1 mg/l), Co (up to 0.26 mg/l), Cu (up to 5.4 mg/l), Zn (up to 43.2 mg/l), Cd (up to 0.126 mg/l), Pb (up to 0.40 mg/l), Hg (up to 0.0032 mg/l) are observed. In surface waters of the Ust-Vikhorevsky bay concentrations of most components of the main ionic composition and trace elements decrease, as compared to the Vikhoreva river water. Maximum concentrations of Mn (511.5 mg/l), Fe (1567.2 mg/l), Co (0.80 mg/l), Pb (0.77 mg/l) were detected in bottom waters. The main ionic composition and trace element concentrations in the Vihoreva river water are determined primarily by anthropogenic factor. At the same time, the hydrochemical regime of the river is effected by natural factors. Inflow of both waters of the highly polluted and forming waters of the channel part of the Ust-Ilimsk reservoir impacts the hydrochemistry of the Ust-Vikhorevsky bay.

Size distribution and source-specific risks of atmospheric elements in Dalian, a coastal city in north China

Trace elements in particles play an essential role in particle-related health and environmental effects and were recognized as primary source tracers. An understanding of the size-segregated elemental composition is critical for accurate source attribution and risk evaluation. The present study investigated the characteristics of 28 elements in the size-fractioned particles of a coastal megacity in north China. The size distribution of element concentration posed bimodal peak mode, and the proportion of most trace elements tended to increase with the decreasing particle size, especially toxic metals like Hg, Ga, Tl, As, Pb, Se, and Cd. Source attribution based on the size-segregated concentrations was conducted by positive matrix factorization. Natural sources such as crust and sea spray aerosol dominated the trace element concentration in the large particles, while anthropogenic sources such as traffic, biomass, coal combustion, and industry contributed the majority in the fine particles. The source-specific exposure risk calculation based on the size-segregated dataset showed a noncarcinogenic risk (HQ) of 6.62 for children, mainly contributed by Tl and As from biomass burning, petrochemical refining, and coal combustion. Compared with larger particles, the finer particles generated a higher HQ and carcinogenic risk, especially particles smaller than 0.49 μm. Fine particles primarily emitted from the petrochemical industry and coal combustion brought out the largest HQ, while fine particles from vehicle traffic and the petrochemical industry contributed the largest carcinogenic risk. Transport of sea spray aerosol contributed a considerable amount of the carcinogenic risk in the coastal urban area.

Assessing the spatial distribution of elemental concentrations in surface sediments of Lake Victoria, Kenya: implications for ecological health and management.

Lacustrine sediment quality indicates the effects of both natural and anthropogenic activities on the ecosystem and communities. Despite its ecological importance, myriad complexities, and potential contaminant sources, the spatial distribution of surficial sediments in Lake Victoria's Winam Gulf has never been comprehensively documented. The purpose of this study was to assess the spatial distribution, pathways, and ecological risk of metal elements in the lake using a sediment matrix. Sediment samples were collected throughout the gulf in November 2022. The concentrations of Al, As, Cd, Co, Cr, Cu, Fe, K, Mn, Mo, Ni, P, Pb, Sb, Sn, Ti, Tl, U, and Zn were compared to different contamination metrics and ecological risk assessment indices. The average concentrations were in the following decreasing order: Zn > > > Cr > > Cu > Ni > Pb > Co > As > Cd with mean (± SD) of 185 ± 45mgkg-1, 56 ± 15mgkg-1, 45 ± 16mgkg-1, 37 ± 11mgkg-1, 24 ± 5mgkg-1, 20 ± 7mgkg-1, 3.9 ± 1.3mgkg-1, 0.30 ± 0.09mgkg-1, respectively, with strong indications of anthropogenic sources. Average concentrations were in the following decreasing order: Zn > > > Cr, Cu, Ni, Pb, Co, As, and Cd levels (mean ± SD) were 185 ± 45mgkg-1, 56 ± 15mgkg-1, 45 ± 16mgkg-1, 37 ± 11mgkg-1, 24 ± 5mgkg-1, 20 ± 7mgkg-1, 3.9 ± 1.3mgkg-1 and 0.30 ± 0.09mgkg-1 with strong indications of anthropogenic sources. The geo-accumulation index (Igeo) and enrichment factor categorisation schemes, respectively, classified these as uncontaminated (level 0) and depletion to minimal enrichment (level 1), while the ecological risk analysis classified them as "low risk". The mouth of the Nyando River, as well as Kisumu, Kendu, and Homa bays, were the most element-enriched and should be prioritised for focused monitoring and remediation. As a result, targeted land management of urban, industrial, transportation, and agricultural areas offers the opportunity to reduce sediment inputs into the lake ecosystem.

Stress evolution in enamel coating/Ni-based alloy systems during isothermal oxidation

This paper utilizes a coupled chemomechanical model that integrates chemical reactions, diffusion, and mechanical deformation to describe the high-temperature interfacial reactions and stress evolution within an enamel coating/Ni-based super-alloy system. Through finite element simulation, we conduct a comprehensive analysis of multiple reactions and processes at the interface. Experimental characterization of the concentration distribution of various elements is employed to verify the accuracy of the proposed chemomechanical model. Additionally, the simulation reveals that the interface region experiences compressive circumferential stress, which can potentially lead to interfacial failure due to buckling. On the other hand, the enamel coating undergoes tensile circumferential stress, resulting in the formation of vertical surface cracks. These findings hold practical implications for the development of advanced coatings with enhanced durability and performance. Future research can further optimize coating design and enhance the reliability of high-temperature applications based on these results.

Risk assessment and pollution loads of potentially toxic elements in water of four rivers flowing into the Mediterranean Sea

One of the main sources of metal accumulation in the marine environment is transport by rivers. Using data from 2014 to 2017 for various stations, this study analysed the distribution of potential toxic element (PTE) concentrations in surface waters, the pollution loads and the water quality index of the large rivers flowing into the Mediterranean Sea (Manavgat, Göksu, Seyhan and Ceyhan). 13 different elements (As, Cd, Cr, Co, Cu, Fe,Pb, Li, Mn, Ni, Se, Zn, Al) were determined within the scope of the study. While the estimation of risk assessments for both adults and children via dermal and ingestion pathways using the United States Environmental Agency (USEPA) formulas. Pollution indexes such as Chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI) and carcinogenic risk (CR) were calculated. Additionally, water quality index (WQI), pollution load ındex (PLI) and contamination factors (CF) were also determined. Since it is a detailed monitoring study of three years, all findings are evaluated using average values for each river. The highest mean PTE concentrations across all rivers were found at stations S4 (Seyhan), S1 and M1 (Manavgat) with Ni (0.1895) > Se (0.0618) > Al (0.0598), respectively. The values of PLI were found to be generally high (3−6) and very high (>6) in all studied rivers. Additionally, these rivers are subject to significant contamination with Pb, as CF>5, indicating very high levels of contamination, was found as a minimum of 166 for Pb in all rivers. Considering all risk assessments, it is concluded that children are more sensitive to ingestion and dermal exposure pathways than adults, and their carcinogenic risk is 4.5 times greater than adults. Besides, according to the statistical analysis, the strong and weak correlation of Al with other elements indicates that the source of the pollution is natural and anthropogenic processes, respectively.

Surfactant-Assisted synthesis of α-and β-Ag2WO4 modified with Sulphur, Phosphorous, and boron and their applications in wastewater elimination

The surfactant cetyltrimethylammonium bromide (CTAB) was utilized to synthesize a combination of α and β-Ag2WO4 phases, which were accordingly doped with 20 % nonmetallic moieties including phosphorous (p), boron (B), and sulphur (S) via a mild precipitation route. Through characterization tools, information was obtained on surface and elemental concentration distribution, vibration, optical, morphological, and electronic properties. These materials were used as nanoadsorbents and photocatalysts. The S doped Ag2WO4 adsorbent (SAgW) has the best removal results (98.7 %) and it follows the Freundlich model of adsorption isotherm. The kinetics of dye adsorption follow the pseudo-second-order kinetic model. It was shown to achieve removal percentages of 98.6 % for indigo carmine dye (IC) and 98.8 % for methyl red dye (MR), demonstrating that the presence of other dyes has no effect on the removal percentage. AgW (CTAB-assisted synthesis) demonstrated high photocatalytic oxidation of IC at 20 mg/L in only 40 min with first-order kinetics of 0.12 min−1, exceeding that of PAgW by 6 times.

Importance of the drying method in crystalline phase formation and metallic elements distribution of glycine complexes

In this work, for the first time, the multi mineral complexes composed of three and four elements FeII, MnII, CuII & ZnII and CuII, MnII & ZnII, respectively) bounded to glycine have been produced to be used as a feed additive for farm animals. To the best of our knowledge, all products were synthesized for the first time as novel compounds containing several transition metals. The impact of the drying procedure on the microstructure, chemical composition and crystalline phase was evaluated using different analytical techniques. The trace element concentration distributions and homogeneity were also studied. A single crystal of dehydrated metal glycinate compound was synthesized from drying of glycine and a multi-metal sulphate solution under room temperature. On the other hand, both spray drying and spray granulation of this similar solution results to the formation of crystalline powders. The crystalline powders obtained present a typical metal-sulphate-glycinate dehydrated crystalline form and a homogeneous distribution of the metals within the product particles. The developed products have been compared and their differences have been underlined.

Rapid assessment of elemental concentrations using pXRF and remote sensing on a dried lakebed

This study aimed to i) explore the land-use effect (former lakebed, pasture, and agricultural areas) on elemental concentrations, enrichment factors (EFs), and geo-accumulation indices (Igeos), ii) provide X-ray diffractograms of the primary minerals and identify the clay minerals dominant in each land-use scenario, iii) map the spatial distribution of elemental concentration, EFs, and Igeos using Digital Soil Mapping (DSM) approaches. We collected a total of 240 soil samples. Our findings highlight that vermiculite was a common clay-sized mineral, and aragonite, gypsum, and calcite were dominant primary minerals in each land-use. The remote sensing data (Sentinel-2 MSI and Landsat-8 OLI) were used to calculate some environmental covariates useful for digital mapping of elemental concentrations, EFs, and Igeos. The highest concordance correlation coefficient (CCC) was found in the prediction of Hg (CCC = 0.79) using remote sensing data based on Sentinel-2 with the Random forest (RF) model. There is neither threat in terms of Cu, Zn, and Pb nor the impact of anthropogenic activities in their distribution under each land-use scenario. The study area was enriched with Hg, Cd, and Ni (very high, EF = 20–40), followed by Cr (significant, EF = 5.88) and As (moderate, EF = 2.08). A similar trend was also found for Igeos across the study area. We conclude that the distribution of elemental concentration, EFs, and Igeos were significantly affected by the shrinking of the Burdur Lake and the different land-use scenarios in this semi-arid region.

First assessment of Rare Earth Element organotropism in Solea solea in a coastal area: The West Gironde Mud Patch (France)

Few studies exist on concentration and internal distribution of Rare Earth Elements (REEs) in marine fishes. REEs organotropism was determined in common sole (Solea solea) from the West Gironde Mud Patch (WGMP; N-E Atlantic Coast, France). The highest ∑REEs concentrations occurred in liver (213 ± 49.9 μg kg−1 DW) and gills (119 ± 77.5 μg kg−1 DW) followed by kidneys (57.7 ± 25.5 μg kg−1 DW), whereas the lowest levels were in muscles (4.53 ± 1.36 μg kg−1 DW) of Solea solea. No significant age- or sex-related differences were observed. The organotropism varied among groups of REEs. Light and heavy REEs preferentially accumulated in liver and gills, respectively. All considered organs showed different normalized REEs patterns, suggesting differences in internal distribution processes between organs. Further work should address: (1) baseline levels worldwide, and (2) factors controlling uptake and organ-specific concentration of REEs.

BaCo0.4Fe0.4Zr0.1Y0.1O3−σ Cathode Performance for Proton Conducting Solid Oxide Fuel Cells with BaZr0.8−xCexY0.1Yb0.1O3−δ Electrolytes

BaCo0.4Fe0.4Zr0.1Y0.1O3−σ (BCFZY) is a proton, oxygen-ion, and electron-hole conducting cathode material for intermediate temperature solid oxide fuel cells. Its electrode reaction mechanism in air with moisture is not well understood. In this study, three types of symmetrical cells with the same BCFZY cathode were fabricated over three related proton conducting electrolytes: BaZr0.8−xCexY0.1Yb0.1O3−δ (x = 0.1, 0.4, and 0.7). The cathode shows similar performance over three different electrolytes in dry air but different responses to moisture introduction. The differences are hypothesized to relate to the mutual diffusion at the cathode/electrolyte interface. Such a hypothesis is supported by different techniques such as XRD Rietveld refinement of BCFZY cathode in mixtures with different electrolytes after firing, energy-dispersive X-ray spectroscopy (EDS) line scanning for element concentration distribution at the cathode/electrolyte interface, as well as electrochemical test for a related BaCoFeO-type cathode with Zr replaced by Ce.

Combustion aerosols and suspended dust with controlled processes in Lhasa: Elemental analysis and size distribution characteristics

To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa, the present study focused on the size distribution and chemical characteristics of particulate matter (PM) emission resulting from 7 types of non-fossil pollution sources. We investigated the concentration and size distribution of trace elements from 7 pollution sources collected in Lhasa. Combining Lhasa's atmospheric particulate matter data, enrichment factors (EFs) have been calculated to examine the potential impact of those pollution sources on the atmosphere quality of Lhasa. The highest mass concentration of total elements of biomass combustion appeared at PM0.4, and the second highest concentration existed in the size fraction 0.4–1 µm; the higher proportion (12 %) of toxic metals was produced by biomass combustion. The elemental composition of suspended dust and atmospheric particulate matter was close (except for As and Cd); the highest concentration of elements was all noted in PM2.5-10 (PM3-10). Potassium was found to be one of the main biomass markers. The proportion of Cu in suspended dust is significantly lower than that of atmospheric particulate matter (0.53 % and 3.75 %), which indicates that there are other anthropogenic sources. The EFs analysis showed that the Cr, Cu, Zn, and Pb produced by biomass combustion were highly enriched (EFs > 100) in all particle sizes. The EFs of most trace elements increased with decreasing particle size, indicating the greater influence of humanfactors on smaller particles.

BaCo0.4Fe0.4Zr0.1Y0.1O3-Σ Cathode Performance for Proton Conducting Solid Oxide Fuel Cells with BaZr0.8-XCexY0.1Yb0.1O3-Δ Electrolytes

BaCo0.4Fe0.4Zr0.1Y0.1O3-σ (BCFZY) is a proton, oxygen-ion, and electron-hole triple conducting cathode material for solid oxide fuel cells. Its electrode reaction mechanism including the rate-limiting step in air with moisture are not well understood. Therefore, we fabricated three types of symmetric cells with the same BCFZY cathode over three related proton conducting electrolytes: BaZr0.8-xCexY0.1Yb0.1O3-δ (x = 0.1, 0.4, and 0.7; Fig.1 are SEM images showing the surface of three different electrolytes). The cathode shows different electrochemical behaviors for the three electrochemical cells including the response to the introduction of moisture. The differences are hypothesized to relate to mutual diffusion at the cathode/electrolyte interface, which are tested by various techniques such as XRD Rietveld refinement of BCFZY cathode in mixtures with different electrolytes after firing, thermogravimetric analysis (TGA) for oxygen vacancy concentration and hydration behavior, electrical conductivity relaxation (ECR) for conductivity changes between dry and moist atmosphere, and energy-dispersive X-ray spectroscopy (EDS) line scanning for element concentration distribution at the cathode/electrolyte interface.Fig1. SEM images of electrolytes (a) BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (Ce-rich), (b) BaZr0.4Ce0.4Y0.1Yb0.1O3-δ (ZrCe-bal) and (c) BaZr0.7Ce0.1Y0.1Yb0.1O3-δ (Zr-rich) Figure 1

Comparison of Grain Size Trend Analysis and Multi-Index Pollution Assessment of Marine Sediments of the Gülbahçe Bay, Aegean Sea

In this study, 46 elements plus total carbonate and total organic carbon contents were measured in 48 sea bottom sediments to determine the pollution levels in the study area and their source to understand better the natural and anthropogenic processes in the study area. Also current flows and sediment transport pathways inferred using multidisciplinary methods by interrelation between grain size trend analysis, shallow seismic and acoustic doppler current profiler analysis to unravel the hydro-sedimentary processes in a micro-tidal environment. Four main factors that were affecting the study area were identified as lithogenic factor (50.6%) anthropogenic factor caused by untreated domestic waste (13.2%), anthropogenic factor caused by marine traffic/port activities (9.3%) and anthropogenic factor caused by small-scale industrial activities (with 6.9% of the total variance). The main source of metals in the study area were determined as untreated domestic waste discharges (total organic carbon and sulfur), maritime traffic/harbor activities (copper and zinc), and discharges of other wastes caused by urbanization. The main metal element that poses the most significant risk for benthic organisms was determined as nickel in the study area. All environmental indices showed non to moderate pollution existing in Gülbahçe Bay. It has been observed that most prominent feature of the distribution of elemental concentrations and assessment of pollution indices were that the pollutants carried inwards to Gülbahçe Bay from Izmir Central Bay with inflows, following the sediment transport directions.

Modeling and mapping the spatial variability of soil micronutrients in the Tigris basin

BackgroundCrop production is negatively impacted by excess and lack of soil micronutrients. Due to anthropogenic and natural factors, soil micronutrients vary greatly in space, necessitating time- and money-consuming large-scale sampling. Therefore, modeling their spatial distributions and forecasting in non-sampled areas are essential for high crop production. MethodsIn this study, regional variations in soil micronutrient content of the Upper Tigris Basin were modeled to produce local change maps for the development of site-specific nutrient management systems. The concentrations of extractable zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) in soil samples taken at 388 different sites between 0 and 20 cm deep were determined. Using variogram and kriging analyses, the spatial distribution of the micro element concentrations was modeled and mapped in a GIS environment. ResultsThe micronutrients demonstrated significant variability with a high coefficient of variation (CV > 35%). It was found that the spatial dependence of the samples ranged from low for Fe and Cu to high for Zn and Mn. The spatial distribution of soil micronutrients was influenced by soil texture in addition to distance. Overall, the results demonstrated that the management of site-specific micronutrients may be aided by the integration of geostatistics and GIS, which is particularly beneficial in terms of effective management of the lands and the optimal use of inputs. ConclusionOverall, the findings showed that the integration of geostatistics and GIS may be helpful in the management of site-specific micronutrients, which is especially advantageous in terms of efficient management of the lands and the best use of inputs.

Formation of the Transition Zone "Matrix Alloy - Reinforcing Granules" in the Process of Solid-Liquid Synthesis of Composite Material

Casted composite materials have found certain application in mechanical engineering. Their advantages are lower cost due to the use of casting technology (solid-liquid synthesis), absence of any restriction on the shape and weight of parts. It is known that the transition zone between the matrix alloy and reinforcing phase plays an important role on the level of mechanical properties of cast composites. So, the aim of the study is investigations of transition zone formation during the infiltration of matrix alloy into the frame formed by the reinforcing phase. Copper based alloy was used as a matrix alloy and cast-iron granules were used as a reinforcing phase. Cast composite materials have been exposed for different time during the synthesis. Specimens were studied using electron microscopy. Results on the concentration distribution of main elements (Si, Fe, Cu) in a transition zone are presented. It is shown that the formation of transition zone starts during the infiltration process with further its growth during the exposition at the synthesis temperature. It is established that the formation of the transition zone takes place not only due to elements diffusion but as well due to the dissolution of granules of reinforcing phase. Experiments carried out allow establishing some peculiarities of the transition zone formation. To achieve required level of mechanical properties it is necessary to control the melt temperature and duration of the synthesis of cast composite materials.