Search Results (34)

Copper and nickel ions play pivotal, albeit distinct, roles as essential trace elements in living systems, and primarily serve as co-factors for a range of enzymes. However, as with all trace metal ions, excessive concentrations can exert adverse toxicological properties. Interestingly, the incorporation of these in cell culture media can establish novel chemical interactions, with their speciation status markedly influencing characteristics, including cell maturation, and cellular uptake mechanisms. Thus, the primary objective of this study was to investigate and determine the speciation status (i.e., complexation) of nickel(II) and copper(II) ions by biomolecules present in RPMI 1640 mammalian cell culture medium using virtually non-invasive high-resolution proton NMR analysis, an investigation of much relevance to now routine studies of their toxicological actions towards cultured cells. Samples of the above aqueous culture medium were ¹H NMR-titrated with increasing added concentrations of 71–670 µmol/L Ni(II)(aq.), and 0.71–6.7, 7.1–67 and 71–670 µmol/L Cu(II)(aq.), in duplicate or triplicate. ¹H NMR spectra were acquired on a JEOL ECZ-600 spectrometer at 298 K. Results demonstrated that addition of increasing concentrations of Ni(II) and Cu(II) ions to the culture medium led to the selective broadening of a series of biomolecule resonances, results demonstrating their complexation by these agents. The most important complexants for Ni(II) were histidine > glutamine > acetate ≈ methionine ≈ lysine ≈ threonine ≈ branched-chain amino acids (BCAAs) > asparagine ≈ aspartate > tyrosine ≈ tryptophan, whereas for Cu(II) they were found to be histidine > glutamine > phenylalanine ≈ tyrosine ≈ nearly all remaining aliphatic metabolites (particularly the wealth of amino acids detectable) > 4-hydroxyphenylacetate (trace culture medium contaminant), in these orders. However, Cu(II) had the ability to influence the linewidths of these signals at much lower added levels (≤7 µmol/L) than that of Ni(II), the broadening effects of the latter occurring at concentrations which were approximately 10-fold greater. Virtually all of these added metal ion-induced resonance modifications were, as expected, reversible on addition of equivalent or excess levels of the chelator EDTA. From this study, changes in the co-ordination sphere of metal ions in physiological environments can give rise to marked modifications in their physicochemical properties (e.g., redox potentials, electronic charges, the potential catalytic generation of reactive oxygen species (ROS), and cell membrane passages). Moreover, given that the above metabolites may also function as potent hydroxyl radical (^●OH) scavengers, these findings suggest that generation of this aggressively reactive oxidant directly from Cu(II) and Ni(II) ions in physiologically-relevant complexes may be scavenged in a ‘site-dependent’ manner. This study is of further relevance to trace metal ion research in general since it enhances our understanding of the nature of their interactions with culture medium biomolecules, and therefore provides valuable information regarding their overall chemical and biological activities, and toxicities. Full article

As the terminal reservoir of the South-to-North Water Diversion’s Eastern Route, Dongping Lake is critical for safeguarding the northern water supply. Analysis of 33 water–sediment sites revealed the following. (1) Waterborne heavy metals (HMs) below WHO limits, confirming the good water quality. (2) Sediment HM enrichment exceeding background levels, with Cd posing high ecological risk (mean E_r = 135), and moderate overall pollution. (3) Speciation showed V, Cr, Co, Ni, Cu, Zn, and Pb predominantly in residual fractions, while Cd exhibited high bioavailability and Pb was in reducible state. Ecological risk assessment indicated that V and Cr tend not to cause environmental pollution; Co, Ni, Cu, Zn, and Pb only cause slight pollution; and Cd causes serious point-source pollution. The carcinogenic risk of surface sediments to children is not negligible. (4) Source apportionment identified industrial emissions as the primary HM contributors, with Cd deriving from agricultural runoff (phosphate fertilizers) and industrial discharges. This study offers valuable baseline information for water quality management in mega-water-transfer projects, directly supporting the Jiaodong Main Line and Yellow River Crossing operations. Full article

Municipal sewage sludge is a potential soil amendment rich in organic matter and nutrients, yet its reuse is often constrained by heavy metal contamination. This study evaluated six heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) in sludge collected from seven centralized wastewater treatment plants in Bangkok, Thailand, by analyzing physicochemical properties, total metal concentrations, and chemical speciation. Three ecological risk indices, the geo-accumulation index (I_geo), risk assessment code (RAC), and potential ecological risk index (PERI), were applied to assess contamination status, mobility, and ecological threat. The sludge exhibited high levels of organic matter and essential nutrients, indicating potential for agricultural reuse; however, elevated electrical conductivity at some sites may pose salinity risks if unmanaged. Speciation analysis revealed that Cd and Zn were largely present in mobile and redox-sensitive fractions, Cr and Pb were primarily in stable residual forms, and Cu and Ni occurred in moderately mobile forms influenced by environmental conditions. Across all indices, Cd consistently posed the highest ecological risk, followed by Zn, in a site-dependent manner, while Cr and Pb represented low risk. These findings provide a clearer understanding of metal behavior in sewage sludge and underscore the importance of integrating chemical speciation with multi-index risk assessment in sludge management. Incorporating such approaches into national guidelines, particularly in countries lacking established heavy metal limits, can strengthen monitoring frameworks, guide safe and sustainable reuse, and support regulatory development in contexts with limited monitoring data. Full article

The rational design of high-performance Cu-SSZ-13 catalysts with enhanced low-temperature activity represents a critical challenge for meeting stringent Euro VII emission standards in diesel aftertreatment systems. Elevating Cu loading can theoretically improve catalytic performance; however, one-time ion exchange using common CuSO₄ solution makes it hard to accomplish high Cu-ion contents. Herein, we demonstrate that the conventional ion-exchange method, adopting Cu(CH₃COO)₂ as precursor in NH₄-SSZ-13 zeolite with a low Si/Al ratio (≈6–7), can achieve higher Cu content while maintaining superior dispersion of active sites. Comprehensive characterizations reveal a dual incorporation mechanism: canonical Cu²⁺ ion exchange and unique adsorption of the [Cu(CH₃COO)]⁺ complex. In the latter case, the surface-adsorbed [Cu(CH₃COO)]⁺ ions form high-dispersion CuO_x species, while the framework-confined ones convert to active Z[Cu²⁺(OH)]⁺ ions. The Cu(CH₃COO)₂-exchanged Cu-SSZ-13 catalyst exhibits superior low-temperature SCR activity and hydrothermal stability to its CuSO₄-exchanged counterpart, making it particularly suitable for close-coupled SCR applications. Our findings provide fundamental insights into Cu speciation control in zeolites and present a scalable, industrially viable approach for manufacturing next-generation SCR catalysts capable of meeting future emission regulations. Full article

Microplastic (MP) contamination in soil is an emerging environmental concern, influencing the mobility and bioavailability of heavy metals (HMs). This study investigates how different MP types (PP, PS, PVC, HDPE, LDPE, PES, and PET-Glitter) affect HM behavior in soil, focusing on sorption/desorption, and the extraction efficiency of Pb, Cu, Co, Ni, Cr, and Cd. Soil samples incubated with MPs showed significant pH increases, particularly with PES and HDPE at 0.8 and 0.6 pH units, respectively. The extraction experiments using 0.05 M EDTA and 0.01 M CaCl₂ revealed that MPs altered metal bioavailability—with HDPE reducing Pb mobility by 15%—and increased Cd and Co mobility by 10–20%. The batch sorption tests confirmed higher Pb adsorption onto HDPE but decreased Cd and Co sorption compared to control soils without MP. These findings demonstrate that MPs act as additional sorption sites, modifying metal speciation and availability, which has critical implications for soil health, agricultural sustainability, and remediation strategies. However, results may vary based on soil type, MP aging, and environmental conditions, indicating the need for further long-term field studies. This research provides valuable insights into the complex interactions between MPs, heavy metals, and soil systems, contributing to a better understanding of pollution dynamics and risk assessment in contaminated environments. Full article

In order to comprehensively understand the content, source, speciation characteristics, and risk of heavy metals in cultivated soil of Pingshui Village, Zhaoping County, Hezhou City, this study conducted measurements on the total amounts of Cr, Ni, Cu, Zn, As, Cd, Pb, and Hg in 34 soil samples within the study area. Correlation analysis and principal component analysis were employed to investigate their sources. An improved BCR sequential extraction procedure was utilized to analyze the occurrence forms of eight heavy metals in soil samples. Ecological risks were evaluated using the geo-accumulation index (I_geo), potential ecological risk index (RI), and risk assessment code (RAC). The findings revealed that: (1) The soil heavy metals in the study area exhibited varying degrees of enrichment, primarily attributed to anthropogenic activities. (2) There was no significant difference in the speciation characteristics of the eight heavy metals in the soil of each sampling site in the study area, and the main components were all residual fraction, and the mild acid-soluble fraction of Cd and Zn accounted for a relatively high proportion in individual sampling sites, which should be paid attention to. (3) Through the results of three risk assessment methods, it is concluded that the heavy metal pollution of soil in the study area is serious, and continuous attention should be paid to the corresponding pollution prevention measures. Full article

This study focuses on the use of three isostructural N₆O donor ligands, specifically known to form complexes with copper ions, to chelate Cu(II) from aqueous solutions. The corresponding Cu(II) complexes feature a dinuclear copper core mimicking the active site of natural superoxide dismutase (SOD) enzymes while also creating a coordination environment favorable for catalase (CAT) activity, being thus appealing as catalytic antioxidant systems. Given the critical role of copper dysregulation in the pathophysiology of Alzheimer’s disease (AD), these complexes may help mitigate the harmful effects of free Cu(II) ions: the goal is to transform copper’s reactive oxygen species (ROS)-generating properties into beneficial ROS-scavenging action. This study investigates the speciation, chelating efficiency, and metal selectivity of these ligands, as well as the antioxidant activity of the resulting complexes under aqueous and physiologically relevant conditions. Additionally, the ligands, equipped with functional groups for attaching targeting moieties, are conjugated with a small peptide that may act as an anti-aggregating agent of β-amyloid peptides, aiming to develop a multifunctional therapeutic strategy against Alzheimer’s disease. Full article

Cu-containing hierarchical SAPO-34 catalysts were synthesized by the bottom-up method using different mesoporogen templates: CTAB encapsulated within ordered mesoporous silica nanoparticles (MSNs) and sucrose. A high fraction of the Cu centers exchanged in the hierarchical SAPO-34 architecture with high mesopore surface area and volume was achieved when CTAB was embedded within ordered mesoporous silica nanoparticles. Physicochemical characterization was performed by using structural and spectroscopic techniques to elucidate the properties of hierarchical SAPO-34 before and after Cu introduction. The speciation of the Cu sites, investigated by DR UV-Vis, and the results of the catalytic tests indicated that the synergy between the textural properties of the hierarchical SAPO-34 framework, the high Cu loading, and the coordination and localization of the Cu sites in the hierarchical architecture is the key point to obtaining good preliminary results in the NO selective catalytic reduction with hydrocarbons (HC-SCR). Full article

Studying and understanding the complexity and interactions of different factors influencing stream sediment quality is necessary for the development of successful water quality management strategies. This study aims to evaluate the level of contamination by potentially toxic elements (PTEs) (As, Co, Cr, Cu, Mn, Ni, Pb, V, Zn) of the stream sediments of the Nile River. During the spring of 2019, river sediments were sampled at 23 sites along the Nile River. For each sample, one aliquot was digested in aqua regia and analyzed by ICP-MS for pseudo-total concentration, while for another aliquot, sequential extraction procedures were applied to determine chemical speciation. Compositional data analysis (CoDa) and k-means were applied to recognize the contribution of natural and anthropogenic sources, while pollution indices (EF, RAC) and sediment quality guidelines (SQGs) were applied to assess the ecological risk to biotic species. The results reveal that elements such as Cr, Mn, V and Fe, found in high concentrations in almost all samples (Cr up to 739 mg/kg, Mn up to 1942 mg/kg, V up to 507 mg/kg, Fe up to 98,519 mg/kg), have a natural origin, while the concentrations of Cu (up to 69 mg/kg), Ni (up to 88 mg/kg), Co (up to 42 mg/kg) and As (up to 9.8 mg/kg) are linked to both natural and anthropogenic processes. Sequential extraction shows that Mn, Co, Ni and, in some sites, Cu and Zn, are the most bioavailable elements. These elements present a high risk of toxicity, while the remaining elements imply a low-to-moderate risk. Full article

Nonferrous metal smelting is a potential emission source of trace elements. However, it is vital to identify the dominant factors in determining toxic element (TE) spatial distribution and migration behaviors. We hypothesize that soil clay is the key factor in agricultural land around nonferrous metal smelting areas. Hence, this study focused on Qingyuan Town, a typical nonferrous metal smelting base. From this site, 95 soil samples (0–20 cm) were collected from cultivated land around the nonferrous metal smelters. Eight soil samples were analyzed for TE speciation and clay minerals in hot spot and non-hot spot areas following the TE distribution. A geographical detector (Geodor) showed that the distributions of total and exchangeable TE were affected by multiple factors (clay, CaO, and Fe₂O₃). X-ray diffraction (XRD) showed that the clay was mainly comprised of an illite and smectite mixed layer (67.13%), illite (15.38%), chlorite (9.25%), and kaolinite (8.25%). Moreover, correlation analysis showed that the exchangeable As was positively correlated with illite (R² = 0.76, at p < 0.01 level), kaolinite (R² = 0.43, at p < 0.01 level), and chlorite (R² = 0.59, at p < 0.01 level) in the hot spot, but negatively correlated with a mixed layer of illite and smectite (R² = 0.83, at p < 0.01 level). In contrast, the cases of Cd, Cu, Pb, and Zn presented an opposite tread with As. The positive matrix factorization (PMF) results showed that the contribution rate of nonferrous metal smelting to soil As was 42.90% and those of Cd, Cu, Pb, and Zn were 84.90%, 56.40%, 59.90%, and 59.20%, respectively. These results can provide guidance for controlling the TE risk associated with agricultural land management. Full article

Mineralogical analysis and laboratory-based leaching tests coupled with speciation modeling were undertaken to quantify the potential for short-term acid generation and the release of trace elements from soils heavily contaminated with mine waste at Rio Tinto. Three different waste materials were considered as case studies: roasted pyrite, copper slags, and leached sulfide ores. The results showed elevated values of net acid generation (up to 663 mmol H⁺/kg), the major pools being potential sulfidic acidity and acidity retained in jarosite. Remarkable contents of As and toxic heavy metals were found especially in the slag-contaminated soil. Copper, Zn, and Pb were the most abundant metals in the acid leach solutions resulting from mine soil-water interaction, with peak values of 55.6 mg L⁻¹, 2.77 mg L⁻¹, and 2.62 mg L⁻¹, respectively. Despite the high total contents of trace elements occurring in soil, the mobile fraction was limited to maximum release values of 12.60% for Cd and 10.27% for Cu, according to the test leaching. Speciation calculations indicated that free metal ions (M²⁺) and sulfate species (MSO₄⁰) accounted for most of the dissolved load. Acid soil drainage is a secondary source of acid and heavy metals in the mine site and, therefore, an effective land reclamation program should ensure that acidity and metal mobility are reduced to environmentally sustainable levels. Full article

The widespread use of wood preservatives, such as chromated copper arsenate (CCA), alkaline copper quaternary (ACQ), and copper azole (CA), may cause environmental pollution problems. Comparative studies on the effect of CCA-, ACQ-, and CA-treated wood on soil contamination are rarely reported, and the behavior of soil metal(loid) speciation affected by preservatives has been poorly understood. Soils under the CCA-, ACQ-, and CA-treated boardwalks were collected to investigate metal(loid) distribution and speciation at the Jiuzhaigou World Natural Heritage site. The results showed that the maximum mean concentrations of Cr, As, and Cu were found in soils under the CCA, CCA, and CCA plus CA treatments and reached 133.60, 314.90, and 266.35 mg/kg, respectively. The Cr, As, and Cu contamination in soils within a depth of above 10 cm was high for all types of boardwalks and limited in the horizontal direction, not exceeding 0.5 m. Cr, As, and Cu in soils were mainly present as residual fractions in all profiles and increased with depth. The proportion of non-residual As in soil profiles under CCA- and CCA plus CA-treatment and exchangeable Cu in CA- and CCA plus CA-treatment were significantly higher than those in the profiles under the other preservative treatments. The distribution and migration of Cr, As, and Cu within soils were influenced by the preservative treatment of trestles, in-service time of trestles, soil properties (e.g., organic matter content), geological disasters (e.g., debris flow), and elemental geochemical behavior. With the CCA treatment for trestles successively replaced by ACQ and CA treatments, the types of contaminants were reduced from a complex of Cr, As, and Cu to a single type of Cu, achieving a reduction in total metal content, toxicity, mobility, and biological effectiveness, thus reducing environmental risks. Full article

Plants in coastal ecosystems are primarily known as natural sinks of trace metals and their importance for phytoremediation is well established. Salvadora persica L., a medicinally important woody crop of marginal coasts, was evaluated for the accumulation of metal pollutants (viz. Fe, Mn, Cu, Pb, Zn, and Cr) from three coastal areas of Karachi on a seasonal basis. Korangi creek, being the most polluted site, had higher heavy metals (HM’s) in soil (Fe up to 17,389, Mn: 268, Zn: 105, Cu: 23, Pb: 64.7 and Cr up to 35.9 mg kg⁻¹) and S. persica accumulated most of the metals with >1 TF (translocation factor), yet none of them exceeded standard permissible ranges except for Pb (up to 3.1 in roots and 3.37 mg kg⁻¹ in leaves with TF = 11.7). Seasonal data suggested that higher salinity in Clifton and Korangi creeks during pre- and post-monsoon summers resulted in lower leaf water (ΨW_o) and osmotic potential at full turgor (ΨS_o) and bulk elasticity (ε), higher leaf Na⁺ and Pb but lower extractable concentrations of other toxic metals (Cr, Cu, and Zn) in S. persica. Variation in metal accumulation may be linked to metal speciation via specific transporters and leaf water relation dynamics. Our results suggested that S. persica could be grown on Zn, Cr and Cu polluted soils but not on Pb affected soils as its leaves accumulated higher concentrations than the proposed limits. Full article

The concentrations of total suspended particles (TSPs) on four buildings near a steel plant’s bulk material storage site for iron ore, coal, limestone, and sinter were evaluated for summer and winter, where the concentrations were 58 (17–55) μg m⁻³ and 125 (108–155) μg m⁻³, respectively. A multivariate regression analysis of meteorological parameters with TSP concentrations indicates that temperature, wind speed, and frequency of rainfall are potential predictors of TSP concentrations, where the respective p values for the model are p = 0.005, p = 0.049, and p = 0.046. The strong correlation between usual co-pollutants, CO, NO₂, and NO_X with TSP concentrations, as indicated by the Pearson correlation values of 0.87, 0.86, and 0.77, respectively, implies substantial pollution from mobile sources. The weak correlation of SO₂ with TSP concentrations rules out a significant pollution contribution from power plants. The speciation of TSPs in winter showed the percentage proportions of water-soluble ions, metal elements, and carbon content in winter as 60%, 15%, and 25%, while in summer, they were 68%, 14%, and 18%, respectively. Water-soluble ions were the most significant composition for both seasons, where the predominant species in summer and winter are SO₄²⁻ and NO₃⁻, respectively. In the TSP metal elements profile, the proportion of natural origin ones exceeded those from anthropogenic sources. The health risk assessment indicates a significant cancer risk posed by chromium, while that posed by other metal elements including Co, Ni, As, and Pb are insignificant. Additionally, all metal elements’ chronic daily occupational exposure levels were below the reference doses except for Cu and Zn. Insights from this investigation can inform decisions on the design of the TSP-capturing mechanism. Specifically, water sprays to capture the water-soluble portion would substantially reduce the amplified concentrations of TSPs, especially in winter. Full article

An appropriate fertilization strategy is essential for improving micronutrient supply, crop nutrition, yield and quality. Comparative effects of different application strategies of micronutrient fertilizer were evaluated in two contrasting sites/soils (upper slope Chernozem and lower slope Solonetz) within a farm field located in the Brown soil zone of Saskatchewan, Canada. The study objective was to examine the impact of Cu, Zn, and B fertilizer application strategies on their mobility, bioavailability and fate in the soil as well as crop yield responses. The application strategies were broadcast, broadcast and incorporation, seed row banding, and foliar application of Cu, Zn, and B on wheat, pea, and canola, respectively. The study was laid out in a randomized complete block design (RCBD) with four treatment replicates for a specific crop and site. Crop biomass yields were not significantly influenced by micronutrient placement strategies at both sites. Pea tissue Zn concentration (35.2 mg Zn kg⁻¹ grain and 5.15 mg Zn kg⁻¹ straw) was increased by broadcast and incorporation of Zn sulfate on the Solonetz soil. Residual levels of soil extractable available Cu were increased significantly to 3.18 mg Cu kg⁻¹ soil at Chernozem and 2.53 mg Cu kg⁻¹ soil Solonetz site with the seed row banding of Cu sulfate. The PRS™-probe supply of Cu (1.84 µm Cu/cm²) and Zn (1.18 µm Zn/cm²) were significantly higher with broadcast application of corresponding micronutrient fertilizer in the Chernozem soil. Both the chemical and spectroscopic speciation revealed that carbonate associated Cu and Zn were dominant species that are likely to control the bioavailability of these micronutrients under field conditions. Full article