Predominant Metal Research Articles

Comparative Electrocatalysis of Hydrogen Production and Oxidation: Technetium versus Rhenium Tris(thiolate) Complexes

AbstractThe development of an efficient catalyst that can selectively activate and generate hydrogen molecules is in urgent demand. Inspired by the 5d rhenium‐tris(thiolate) complex that is capable of catalytically producing and oxidizing H2, the mechanisms of electrocatalytic H2 oxidation (HOR) and evolution (HER) catalyzed by the 4d technetium‐tri(thiolate) analogs, and [TcL3] (L = diphenylphosphinobenzenethiolate, a noninnocent ligand), were investigated by DFT calculations, aiming at elucidating the role of the metal in metal‐ligand cooperativity. DFT calculations anticipate high reactivity in both HOR and HER for [TcL3] beyond that of its Re counterparts. Substituting the Re metal for Tc in metal‐tris(thiolate) complexes results in a greater thiyl‐radical character in the Tc complex compared to that in Re. Even when both complexes evolve H2 with similar [ECEC] mechanisms, the proton relays behave with a distinct disparity, featuring the S ligand in the Tc species as compared to the metal‐hydride in Re. The HOR mechanism also bifurcates as [TcL3]2+ is predicted to mainly occur via the ligand‐based pathway, in contrast to the predominant metal and ligand‐based reactivity for Re. This study established the role of the metal in HER and HOR while emphasizing the utility of such metal‐DPPBT cooperativity in the catalytic process.

Degradation and Migration in Olive Oil Packaged in Polyethylene Terephthalate under Thermal Treatment and Storage Conditions

The research addresses challenges in food safety related to the migration of contaminants from plastics to food. It focused on the physicochemical and sensory degradation of olive oils packaged in polyethylene terephthalate (PET) and subjected to thermal exposure at 40 °C and 60 °C for several weeks and a subsequent 12 months of storage, as well as the stability and migration of compounds from the PET packaging itself. Olive oils (OO) from Spanish supermarkets (a mixture of refined and virgin, with commercial identifications of mild and intense) were selected and subjected to thermal treatments at 40 °C and 60 °C for 1, 2, and 3 weeks, followed by 12 months of storage. The treatments were conducted through the following two independent experiments: Experiment A focused on immediate analysis post-thermal treatment, while Experiment B included a 12-month storage period post-thermal treatment. The presence of antimony (Sb) was analyzed using acid digestion with nitric acid (HNO3) and high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS), while the metals cadmium (Cd), copper (Cu), lead (Pb), and iron (Fe) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The PET characterization was assessed using Fourier transform infrared spectroscopy in the mid-infrared range (FT-IR/MIR), carbonyl index, and differential scanning calorimetry (DSC). The results showed increases in the acidity index by 0.29%, the peroxide value by 25.92%, and the K268 coefficient by 51.22% between the control sample and the most severe treatments, with more pronounced effects observed after 12 months. Sensory quality declined, with reduced intensity of the “fruity” attribute and increased presence of the “rancid” defect. PET degradation was reflected in an increase in the carbonyl index and greater structural amorphization. Fe was the predominant metal, and Sb concentration increased after thermal treatments. The lack of studies on the raw consumption of oils packaged in PET and the concerns about the migration of compounds from the packaging to the food highlight the relevance of this research. This study provides new insights into the effects of thermal exposure and storage on the migration of PET contaminants into oils, contributing to the development of strategies to ensure food safety and product quality.

Ecological impact of heavy metal pollution on Limnodrilus cervix -abundance, bioaccumulation, and environmental dynamics in a perennial pond of Jammu, India

This study examines the ecological ramifications of heavy metal contamination on benthic invertebrate communities, with a focus on Limnodrilus cervix, in a perennial pond situated in the Raipur region of Jammu, India. The study identified 11,587 individuals of Limnodrilus cervix, showing seasonal variations in abundance. Through a multidisciplinary approach encompassing taxonomic analysis, heavy metal quantification, acute toxicity testing, and bioaccumulation assessments, the research explores the intricate dynamics between pollution and aquatic ecosystems. Findings reveal pronounced seasonal fluctuations in L. cervix populations, with copper emerging as the predominant metal. Acute toxicity tests underscore dose-dependent lead (Pb) toxicity with an LC50 value of 0.03 mg/L, while bioaccumulation experiments elucidate Pb absorption in worm tissue with a bioconcentration factor (BCF) of 0.4 at 0.005 mg/L and 0.7 at 0.01 mg/L. The study underscores the urgent need for informed management strategies to mitigate the ecological risks posed by heavy metal pollution and safeguard freshwater habitats and their inhabitants.

Estimation of potential health risks on metals and metalloids contaminants in black goby (Gobius niger) consumption in selected niger delta coast, nigeria

IntroductionThe Niger Delta in Nigeria is subject to anthropogenic influences, impacting the quality of its water bodies, including the Sombrero River. This study aims to investigate the concentrations of metals and metalloids in Gobius niger from the Sombrero River, as these contaminants can pose risks to human health through seafood consumption. Specifically, zinc (Zn), iron (Fe), copper (Cu), lead (Pb), arsenic (As), and cadmium (Cd) were analyzed using atomic absorption spectroscopy (AAS). Materials and MethodsSamples were collected from three different stations along the Sombrero River. The concentrations of Zn, Fe, Cu, Pb, As, and Cd were determined using AAS. Hazard Quotients (HQ), Chronic Daily Intake (CDI), Hazard Index (HI), and Individual Lifetime Cancer Risk (ILCR) values were calculated to assess the potential health risks associated with consuming fish contaminated with these metals and metalloids. ResultsStation 1 had the highest Zn concentration, followed by Fe, Cu, Pb, Cd, and As, with Zn reaching 104.8 ± 1.37 mg kg−1. Station 2 exhibited a similar trend, while Station 3 had Zn as the predominant metal and metalloid. Notably, Pb, As, and Cd levels were consistently low at all stations. While Pb was within permissible limits set by FAO/WHO for contaminants in the fish samples, Zn exceeded regulatory guidelines, suggesting a potential source of contamination. Hazard Quotients (HQ) highlighted a significant risk associated with zinc, especially for children. Chronic Daily Intake values showed metals in fish consumed by adults and children were generally within safe limits, except for Zn, which exceeded Maximum Tolerable Daily Intake (MTDI). Hazard Index values pointed to a substantial long-term health risk, particularly for children due to high zinc levels. However, Individual Lifetime Cancer Risk (ILCR) values were generally below 1, indicating relatively low cancer risks from G. niger consumption for both age groups. ConclusionThis study emphasizes the need for monitoring and managing metals and metalloid pollution in the Niger Delta region to ensure safe seafood consumption and community well-being. While certain metals pose minimal health risks, it highlights the necessity of specific interventions to reduce excessive zinc exposure and safeguard long-term health in the region.

Source apportionment and risk assessment of soil heavy metals in the Huangshui River Basin using a hybrid model

Source apportionment and risk assessment of soil heavy metals (HMs) are essential for pollution control. However, inherent limitations in receptor models hinder accurate source apportionment, impacting outcomes of source-oriented risk assessment. A hybrid model was employed by combining two receptor models, absolute principal component score/multiple linear regression (APCS/MLR) and positive matrix factorization (PMF) models. Four primary pollution sources were identified, followed by an assessment of source-oriented environmental and human health risks in the Huangshui River Basin. Results revealed that Cr, Cd, and Ni average concentrations surpassed their background by 3.1, 2.1, and 1.9 times, respectively. Additionally, 54.29%, 13.34%, and 18.09% of Igeo values for Cr, Cd, and Ni were classified as “moderately contamination” or higher. Natural sources significantly influence Cu (90.2%) and As (71.4%). Cr (63.4%) and Ni (77.9%) mainly originated from agriculture and industry, respectively. Transportation sources emerged as the primary contributors to Pb (59.6%), Zn (48.6%), and Cd (47.2%). The environmental risk level in this study area remained acceptable. Ecological risk was mainly attributed to industrial activities (46.6%) and transportation (37.6%), with Cd being the predominant metal responsible for this risk. Although the noncarcinogenic risk was negligible for all populations, the carcinogenic risk demands attention, particularly concerning children. Industrial sources (67.0%) and Ni were identified as the main contributors to the carcinogenic risk. This study represents an attempt to develop a hybrid model, providing an effective approach to combine models for the accurate apportionment of pollution sources and the reduction of risks.

A biodynamic model predicting copper and cadmium bioaccumulation in caddisflies: Linkages between field studies and laboratory exposures.

Hydropsyche and Arctopsyche are filter-feeding caddisflies (Order: Trichoptera; Family: Hydropsychidae) that are commonly used to monitor metal exposures in rivers. While tissue residue concentrations provide important bioaccumulation data regarding metal bioavailability, they do not provide information regarding the mechanisms of uptake and loss, or exposure history. This study examined the physiological processes that control Cu and Cd uptake and loss using a biokinetic bioaccumulation model. Larvae of each taxon were experimentally exposed to either water or food enriched with stable isotopes (65Cu and 106Cd). Dissolved Cu uptake (ku) was similar between species (2.6-3.4 L-1g 1d-1), but Cd uptake was 3-fold higher in Hydropsyche than Arctopsyche (1.85 L-1g 1d-1 and 0.60 L-1g 1d-1, respectively). Cu and Cd efflux rates (ke) were relatively fast (0.14 d-1-0.24 d-1) in both species, and may explain, in part, their metal tolerance to mine-impacted rivers. Food ingestion rates (IR), assimilation efficiency (AE) of 65Cu and 106Cd from laboratory diets were also derived and used in a biodynamic model to quantify the relative contribution of dissolved and dietary exposure routes. Results from the biodynamic model were compared to tissue concentrations observed in a long-term field study and indicated that because dissolved Cu and Cd exposures accounted for less than 20% of body concentrations of either taxon, dietary exposure was the predominant metal pathway. An estimation of exposure history was determined using the model to predict steady state concentrations. Under constant exposure conditions (dissolved plus diet), steady state concentrations were reached in less than 30 days, an outcome largely influenced by rapid efflux (ke).

Phosphorus recovery from calcium phosphate enriched activated sludge

This study explores the potential of activated sludge from wastewater treatment plants (WWTP) as an alternative source of phosphorus, vital for fertilisers and other products, compared to large-scale phosphorus mining. The research focuses on analysing optimal conditions and the impact of activated sludge characteristics on phosphorus release from calcium phosphate compounds, particularly hydroxyapatite (HAP). Using batch reactor experiments with varying pH and contact time, the results reveal that lower pH values, particularly pH 4, result in higher phosphorus release. The study also finds that calcium, the predominant metal content in activated sludge, plays a vital role in bonding with phosphates and forming new compounds, effectively reducing phosphorus concentration in the solution. Moreover, the VSS/TSS value in the activated sludge has no significant effect on phosphorus release, but interventions occur at high VSS/TSS values. The reaction rate coefficient is calculated at 0.00033/min at pH 4. Overall, this research emphasises the potential of phosphorus recovery from calcium phosphate enriched activated sludge and underscores the importance of optimising pH and considering activated sludge characteristics for efficient phosphorus release.

Impact of a phosphate compound on plant metal uptake when low molecular weight organic acids are present in artificially contaminated soils

A phosphate compound can stabilize cadmium (Cd), lead (Pb), and zinc (Zn)-contaminated soils, although its effectiveness in reducing metal availability and plant uptake when low molecular weight organic acids (LMWOAs) are present is uncertain but nonetheless worth evaluating. Here, 3 % NaH2PO4 (a P compound), tartaric acid (TA), oxalic acid (OA), and mixtures of P and TA/OA are used to evaluate Indian spinach (Basella Alba L.) for soil Cd, Pb, and Zn availability and absorption. Additionally, soil metal immobilization options were examined. Of these treatments, P plus low TA (P-TA2), followed by P, decreased shoot Cd, Pb, and Zn the most, with values of 1.03, 2.52, and 104.50 mg kg−1, respectively, somewhat greater than threshold values of WHO, particularly for Pb and Zn. After harvest, P-TA2 contained >2.44, >321.70, and >290.22 mg kg−1 of total oxidizable and residual Cd, Pb, and Zn, showing that 48 %, 80 %, and 58 % of soil metals were immobilized and not taken up by the plant. P-TA2′s zeta potential, followed by P, became steadily more negative as pH increased, confirming that electrostatic adsorption was the main metal immobilization process, notably in P-TA2. However, in XRD studies, P alone generated Cd phosphate, pyromorphite, and hopeite, showing that sorption and precipitation were the predominant metal immobilization mechanisms. Finally, P-TA2 is the best in immobilizing and inhibiting metals in contaminated soils for plant absorption. Since rhizotropic LMWOAs may impact Cd, Pb, and Zn mineral stability, they should be addressed when treating Cd, Pb, and Zn-contaminated soils with P for plant growth studies.

Computational framework for the evaluation of the composition and degradation state of metal heritage assets by deep learning

The accurate assessment of the material constitution and degradation in newly discovered archaeological artefacts is paramount for the decisions surrounding a thorough treatment of the object during the restoration and conservation stages. The laboratories possess competent experts and complex devices to perform this analysis properly. Nevertheless, a timely hint of an artificial intelligence assistant regarding the chemical composition and corrosion compound localization of a metal asset could save additional time and resources. The present paper proposes such a computational framework based on deep learning techniques that, on the base of its automatic determination of the chemical concentration of the predominant metal from a microscope image, can subsequently independently also recognize and delineate the corrosion spots of the products specific to that metal. The experiments have been performed on iron and copper heritage items from the Oltenia Museum, Romania. The results suggest that, even with an economic training information in terms of microscope images and annotations, the artificial intelligence framework can provide on-site support for an early examination of metal heritage assets.

Evaluation of microstructure, mechanical properties, and corrosion resistance for Ti-doped inconel 625 alloy produced by laser directed energy deposition

Additive manufacturing (AM) technology has opened up new opportunities to efficiently synthesize alloys and produce near-net shape components. In this study, Ti-doped Inconel 625 materials were produced to promote in-situ alloying between pre-alloyed Inconel 625 and elemental Ti powders by laser directed energy deposition, a predominant metal AM technique. The microstructure, mechanical properties, and corrosion resistance were evaluated before and after Ti addition and heat treatment (solutionization followed by aging). It was found that Ti addition alone did not cause significant change in microstructure. However, heat treatment caused migration of segregation species from interdendritic regions to intermetallic precipitates which occupy grain boundaries, and it modestly increased the average grain size for Ti-doped samples. Crystallographic analysis revealed a very strong cubic texture of Ti-doped Inconel 625 which only slightly decreased after heat treatment. Without heat treatment, the addition of Ti was not found to be beneficial to tensile properties of Inconel 625, due to the formation of thin Ti oxide films. However, the combination of Ti addition and heat treatment led to modest increase in hardness and tensile strength compared to the as-built Ti-free case, which is believed to result from the effects of Ti solid solution hardening, precipitation hardening, and dissolution of oxide films. Also, the combined effects can explain the pronounced increase of ductility for Ti-doped Inconel 625 after heat treatment, where the beneficial effect from oxide film dissolution could be dominant. In addition, under the as-built condition, corrosion resistance was found to be slightly higher for Ti-doped materials, but after heat treatment it dropped for Ti-doped materials while almost did not change for Ti-free case.

Philosophical health and wuxing ontology.

In recent years, a new form of health has emerged, namely philosophical health. This novel concept is part of the philosophical counseling movement and relies on the philosophical method called the SMILE-PH interview, which draws heavily from continental philosophy, including phenomenology. Reflecting on the link between health and philosophy brings us to an ancient healthcare tradition that actively relies on philosophy: Chinese healthcare and its founding wuxing, or five phases ontology. The aim of this study is to interpret philosophical health from the standpoint of wuxing ontology. We used the multiple meanings of the five phases to interpret the six concepts of SMILE-PH interview method. Then, we monitored how applying the SMILE-PH involves a parent phase triggering for the counselee. Last, we focused our analysis on the triggered phase and conceptualized them into philosophical health. The SMILE-PH topics are located in a specific phase, namely the Metal phase (xin), which is described by the concepts of connection, existence, identity, meaning in one's life, and spirituality. The one-phase structure of SMILE-PH fosters the triggering of its parent phase: the predominant Metal phase character of the SMILE-PH interview will promote the appearance of Earth phase answers. Conceptualizing the Earth phase into philosophical health adds the following aspects to the latter: emotional stability, the feeling of plenitude, and sharing without a transactional mindset. We obtained a clear perspective of the place of SMILE-PH in wuxing ontology and added a new layer to philosophical health. The other phases of wuxing ontology remain to be tested and integrated into philosophical health.

Molecular Evidence for Occurrence of Heavy Metal and Antibiotic Resistance Genes Among Predominant Metal Tolerant Pseudomonas sp. and Serratia sp. Prevalent in the Teesta River.

Riverine ecosystems polluted by pharmaceutical and metal industries are potential incubators of bacteria with dual resistance to heavy metals and antibiotics. The processes of co-resistance and cross resistance that empower bacteria to negotiate these challenges, strongly endorse dangers of antibiotic resistance generated by metal stress. Therefore, investigation into the molecular evidence of heavy metal and antibiotic resistance genes was the prime focus of this study. The selected Pseudomonas and Serratia species isolates evinced by their minimum inhibitory concentration and multiple antibiotic resistance (MAR) index showed significant heavy metal tolerance and multi-antibiotic resistance capability, respectively. Consequently, isolates with higher tolerance for the most toxic metal cadmium evinced high MAR index value (0.53 for Pseudomonas sp., and 0.46 for Serratia sp.) in the present investigation. Metal tolerance genes belonging to PIB-type and resistance nodulation division family of proteins were evident in these isolates. The antibiotic resistance genes like mexB, mexF and mexY occurred in Pseudomonas isolates while sdeB genes were present in Serratia isolates. Phylogenetic incongruency and GC composition analysis of PIB-type genes suggested that some of these isolates had acquired resistance through horizontal gene transfer (HGT). Therefore, the Teesta River has become a reservoir for resistant gene exchange or movement via selective pressure exerted by metals and antibiotics. The resultant adaptive mechanisms and altered phenotypes are potential tools to track metal tolerant strains with clinically significant antibiotic resistance traits.

Bioremediation competence of Aspergillus flavus DDN on pond water contaminated by mining activities.

This research was performed to evaluate the possibilities of reducing the physicochemical properties of polluted pond water situated around the magnesite mine tailing through indigenous metal tolerant fungi. The physicochemical analysis results revealed that most of the physicochemical properties of pond water sample were crossing the permissible limits. From the muddy pond soil sample, Aspergillus flavus DDN was identified (through molecular characterization) as predominant metal tolerant fungal strain and it showed resistance to Cr(VI), Pb(II), Zn(II), Cd(II), and Mg(IV) up to 1000μgmL-1 concentrations. This strain also effectively reduced (through biosorption) these metals in a short duration of the bioremediation process. In a lab-scale bioremediation study, the A. flavus DDN significantly reduced most of the physicochemical parameters crossing the permissible limit in polluted pond water in the presence of FM1 minimal media in 10 days of incubation. The dissolved oxygen level was significantly increased up to 74.91% from 5.86±0.39 to 10.25±0.95 in 10 days of treatment. The metal reduction and other physicochemical properties reduction were directly related to the biomass of A. flavus DDN. These findings suggest that A. flavus DDN can remove pollutants from magnesite mine tailing polluted pond water because elevated fungal biomass resulted in the highest percentage of pollutant reduction from the sample.

Determination of Heavy Metal Pollution in the Dankran River in the Bekwai Municipality of Ghana

Water pollution has been a major issue across the globe because of industrial activities to meet the needs of people. Many chemicals are released into the environment through these processes, which affect human health and the environment. Hence, the study aimed to assess the concentration of heavy metals (Cu, Zn, Mn, Ni, Hg, and Fe) and the physicochemical and biological properties of the Dankra River. The samples were taken from three locations, Konyaw, Jumako, and Anwiankwanta, and subjected to standard laboratory tests using Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). Results revealed that the Dankran river was not polluted with the selected heavy metals under study. The physicochemical properties, the biological oxygen demand (BOD), chemical oxygen demand (COD), and nitrogen, phosphorus, and potassium (NPK) concentrations were all within the allowable healthy limits according to WHO standards. Iron was the predominant metal in the Dankran river, with the highest concentration of 6.5913 mg/l. Thus, the river is safe to use, but there is a need for regular monitoring to support life. The order of concentration of the investigated metals follows this pattern in descending order: Fe > Mn > Cu > Zn > Ni > Hg.

Analysis of surface roughness and oxidation of FeNi-based metal amorphous nanocomposite alloys

We report on a systematic investigation of newly developed (Fe 70 Ni 30 ) 80 Nb 4 B 14 Si 2 metal amorphous nanocomposites (MANCs) and the factors affecting their surface roughness, including oxide formation and phase evolution during the nanocrystallization process. Analysis of surface roughness using atomic force microscopy (AFM) revealed an average roughness of 9.33 nm after heat treatment compared with as-cast amorphous ribbons, which exhibited a roughness of 4.21 nm. A surface oxide layer thickness has been determined using X-ray photoelectron spectroscopy (XPS). For samples annealed at 400 °C for 1 h, 450 °C for 1 h, and 550 °C for 3 h in air, the average surface oxide layer thickness was determined to be 10.9, 11.7, and 54.4 nm, respectively. It was observed that oxygen is enriched at the outermost surface and decreases rapidly as the XPS sputtering depth increases. Fe-oxide appeared as a predominant metal oxide at the top surface, followed by the presence of Nb oxide. A boron content increase was observed at the interface between the top surface oxide layer and the bulk of the sample. A protective surface oxide layer on FeNi-MANCs, such as observed in this work, can provide sufficient electrical insulation to reduce interlaminate eddy current losses and lower overall losses in magnetic components. • Surface roughness and oxidation of FeNi-based metal amorphous nanocomposites. • Surface roughness in amorphous ribbon using atomic force microscopy (AFM). • Crystallization and activation energies in metal amorphous nanocomposite ribbons. • Phase fractions in metal amorphous nanocomposite ribbons. • Surface oxides partitioning in amorphous and nanocrystalline alloys.

Elucidation of Metal Local Environments in Single-Atom Catalysts Based on Carbon Nitrides.

The ability to tailor the properties of metal centers in single-atom heterogeneous catalysts depends on the availability of advanced approaches for characterization of their structure. Except for specific host materials with well-defined metal adsorption sites, determining the local atomic environment remains a crucial challenge, often relying heavily on simulations. This article reports an advanced analysis of platinum atoms stabilized on poly(triazine imide), a nanocrystalline form of carbon nitride. The approach discriminates the distribution of surface coordination sites in the host, the evolution of metal coordination at different stages during the synthesis of the material, and the potential locations of metal atoms within the lattice. Consistent with density functional theory predictions, simultaneous high-resolution imaging in high-angle annular dark field and bright field modes experimentally confirms the preferred localization of platinum in-plane in the corners of the triangular cavities. X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and dynamic nuclear polarization enhanced 15 N nuclear magnetic resonance (DNP-NMR) spectroscopies coupled with density functional theory (DFT) simulations reveal that the predominant metal species comprise Pt(II) bound to three nitrogen atoms and one chlorine atom inside the coordination sites. The findings, which narrow the gap between experimental and theoretical elucidation, contribute to the improved structural understanding and provide a benchmark for exploring the speciation of single-atom catalysts based on carbon nitrides.

Environmental impact of fish farming: assessment of metal contamination and sediment geochemistry at three aquaculture areas from the eastern Aegean coast.

Metal contamination and geochemistry of surface sediments were assessed at three aquaculture sites from the eastern Aegean coast. The chlorophyll degradation products and organic carbon levels were used as indicators of eutrophication status. In Akköy, higher Hg, Pb, and Cd levels were observed around the cages, while maximum concentrations of other elements were determined at stations situated near the Büyük Menderes River estuary. Metal concentrations were less than the central Aegean coast background levels other than Zn, Ni, and Cr in Akköy. Several approximations have been utilized to evaluate potential toxicity of sediments and sediment quality guidelines (SQG) were used to estimate the risks for aquatic life. Ni was the only metal with concentrations exceeding all SQG values, which indicates the highest adverse biological effect in Ildır, Akköy, and occasionally toxic in Güllük. Based on QPEL and QTEL, Ni and Cr were the predominant metal contaminants in all areas. Similarly, Cr and Ni account for the most of the all sediment toxicity in the aquaculture areas according to toxic risk index. It is concluded that sediments around the fish farms are affected by growing input of elements because of aquaculture activity. The levels of chlorophyll degradation products showed oligotrophic and mesotrophic conditions in the three studied aquaculture areas.

Metal concentration, source, and health risk assessment of PM2.5 in children's bedrooms: Rural versus urban areas

The objective of this study is to gain a better understanding of the metal characteristics, sources, and health risks of children's exposure to PM2.5 and related metals in children's bedrooms in urban and rural areas. PM2.5 personal environmental monitoring samplers were used to collect both indoor and outdoor PM2.5 in urban and rural areas in Taiwan. Al, Cd, Cr, Mn, Pb, V, and Zn were analyzed by inductively coupled plasma mass spectrometry. Source apportionment of metals in PM2.5 was carried out with factor analysis (FA). Health risk assessment of metals was performed on children via inhalation. The average indoor PM2.5 concentrations were 11.9 ± 5.2 μg/m3 and 11.9 ± 4.7 μg/m3 in urban and rural areas, respectively. The most predominant metal indoors in urban areas was Al, followed by Zn, Pb, Mn, V, Cr, and Cd, with a similar result in rural areas. The results from FA indicated that traffic emission and oil combustion in the outside environment were major pollution sources to indoor Mn, V, and Zn; corrosion of building material could be a contributor to Al, Cd, and Pb; pollution sources were different to Cr in two areas. The carcinogenic risk for indoor Cr(VI) via inhalation was higher in urban areas (boy: 6.61E-06; girl: 6.18E-06) than that in rural areas (boy: 2.80E-06; girl: 2.62E-06). These findings will help us to further understand the pollution sources, health risks, and control strategies for metals in PM2.5 in children's bedrooms for reducing adverse health effects, including in rural areas.

Sphalerite‐galena replacement in sodium chloride solution: A thermodynamic approach

AbstractConsidering the material balances of the constituents including solid phases, replacement reaction of the sphalerite‐galena pair in chloride solution is examined quantitatively under equilibrium conditions of 250°C, water saturation vapor pressure, and initial Cl concentration of 1 mol/L. NaCl+PbCl2 solution with solid sphalerite, dissolves and releases both total Zn and total S of 1.26 × 10−5 mol/L into the solution under without or lower PbCl2 concentration. If the PbCl2 concentration is higher than 1.32 × 10−6 mol/L, precipitation of galena as replacement occurs, suggesting that sphalerite has an ability to trap a lower concentration of Pb. If PbCl2 concentration of the solution is higher than 1.32 × 10−6 mol/L, the majority of Pb deposited as galena with using sulfur originated from solid sphalerite dissolved, and the amount of Zn from sphalerite equivalent to the amount of galena deposited releases into the solution. On the other hand, NaCl+ZnCl2 solution with solid galena under the same environmental conditions, dissolves and releases both total Pb and total S of 6.43 × 10−6 mol/L into the solution under without or lower ZnCl2 concentration. Over the ZnCl2 concentration of 6.40 × 10−5 mol/L in the solution, precipitation of sphalerite occurs, indicating that galena cannot trap a low concentration of Zn. Zinc would drain away from the hydrothermal depositional environment under the presence of only galena. These relationships are controlled mainly by the reaction of predominant metal chloride or metal hydroxide species in the solution. Sphalerite is a good scavenger for Pb, but galena is not for Zn.

Trace Element’s Speciation in the Water and Bottom Sediments of the Pirogovo Reservoir

The composition and speciation of trace elements were studied in surface and interstitial waters along with solid phase of bottom sediments to characterize the abiotic segment of the Pirogovo Reservoir. It was found that the concentrations of metals in surface waters did not exceed the MACs for fishery basins, excluding Zn and Cu (2–9 and up to 2 MACs, respectively). According to thermodynamic calculations, the predominant metal speciation in water is free ions (Sr, Ba, Zn, Ni, Co, and Cd), as well as fulvate and carbonate complexes of Cu and Pb, respectively. Interstitial waters showed a regular increase of the fraction of the sulfate complexes of trace elements in loamy sediments. The solid phase of the latter as well was characterized by low anomalous concentrations of Zn, Cd, Co, and Ni. According to the data of extraction, the metals were either fixed in bottom sediments within crystal structure of silicates or bound to oxides and hydroxides of iron and manganese, excluding Cd and Mn, which are characterized by a considerable role of their exchangeable and bound to carbonates fraction in the particulate matter.