Metal Interactions Research Articles

Biosorption of Cr ions from tannery effluent using microalgae proteins through metal docking with the prediction of significant protein metal interaction

Biosorption of Cr ions from tannery effluent using microalgae proteins through metal docking with the prediction of significant protein metal interaction

Trace metal interaction with thermophilic phototrophic anaerobic bacterium Chloroflexus aurantiacus

Towards improving the knowledge of possible paleo-microorganisms interaction with trace metals (micro-nutrients and toxicants), we studied adsorption of Mn, Zn, Sr, Cd, and Pb onto modern Chloroflexus aurantiacus, thermophilic anoxygenic phototrophic bacterium which could be highly abundant in the Precambiran aquatic environments. Acid-base surface titrations allowed quantifying the number of proton-active surface groups, whereas non-electrostatic linear programming method (LPM) was used to assess the surface site concentrations and adsorption reaction constants between divalent cations (Zn, Mb, Sr, Cd, Pb) and bacterial surface, based on results of pH-dependent adsorption edge and constant-pH ‘langmuirian’ adsorption experiments. The total proton/hydroxyl binding site number of Chl. aurantiacus surfaces was sizably lower than that of other phototrophic anaerobic bacteria studied previously using similar experimental and modeling approach. Divalent metals exhibited a decreasing order of adsorption affinity (Pb > Cd ≥ Zn ≥ Mn > Sr), which reflected the order of cation hydrolysis and was similar to adsorption order on other phototrophic bacteria. At the same time, adsorption of Zn increased with increasing of temperature, from 4 °C to 60 °C and was stronger under light compared to the darkness. This suggested some active metabolic control involved in this metal interaction with bacterial surfaces. Overall, Chl. aurantiacus exhibited trace metal adsorption parameters (site number and binding constants) which were lower compared to other anoxygenic phototrophic bacteria (Rhodopseudomonas palustris; Rhodobacter blasticus) and cyanobacteria. This may reflect different bioavailability of trace metals in the paleo-ocean, given that thermophilic Chl. aurantiacus are among the oldest phototrophs on the planet.

Metal Mixture Effects of Ni, Cu, and Zn in a Multispecies, Two-Trophic-Level Algal-Daphnid Microcosm Can Be Predicted From Single-Trophic-Level Effects: The Role of Indirect Toxicity.

Effect assessments of metals are mostly based on single-metal, single-species tests, thereby ignoring metal-mixture effects and indirect effects through species interactions. We tested the combined effects of metal and species interactions in two-trophic algal-daphnid microcosms. Metal-mixture effects on daphnid communities may propagate from effects on the generally more sensitive algal communities. Four different algal communities (three species each), with and without addition of the same daphnid community (three species) were exposed to single metals and one metal mixture (17:17:51 µg/L Ni:Cu:Zn). Daphnid densities were negatively affected by metals in the two-trophic test, the magnitude of which depended on the algal community composition. Algal densities were overall positively affected by the metals in the two-trophic test but negatively in the single-trophic test, illustrating an indirect positive effect in the two-trophic system due to a reduced grazing pressure. Metal effects on daphnid communities in the two-trophic test (day 21) were correlated with metal effects on the single-trophic-level algal communities during exponential growth (R2 = 0.55, p = 0.0011). This finding suggests that metal effects propagate across trophic levels due to a reduced food quantity. However, the indirect positive effects on algal densities, resulting in abundant food quantity, suggests that metal effects can also propagate to daphnids due to a reduced food quality (not measured directly). Metal-mixture interactions on daphnid densities varied during exposure, but were additive or antagonistic relative to independent action when final daphnid densities were considered (day 56). This suggests stronger indirect effects of the mixture compared with the single metals. Overall, our study highlights the dynamic aspect of community-level effects, which empirical reference models such as independent action or concentration addition cannot predict. Environ Toxicol Chem 2024;43:2350-2364. © 2024 SETAC.

Investigating the interaction of uranium(VI) with diatoms and their bacterial community: A microscopic and spectroscopic study

Diatoms and bacteria play a vital role in investigating the ecological effects of heavy metals in the environment. Despite separate studies on metal interactions with diatoms and bacteria, there is a significant gap in research regarding heavy metal interactions within a diatom-bacterium system, which closely mirrors natural conditions. In this study, we aim to address this gap by examining the interaction of uranium(VI) (U(VI)) with Achnanthidium saprophilum freshwater diatoms and their natural bacterial community, primarily consisting of four successfully isolated bacterial strains (Acidovorax facilis, Agrobacterium fabrum, Brevundimonas mediterranea, and Pseudomonas peli) from the diatom culture. Uranium (U) bio-association experiments were performed both on the xenic A. saprophilum culture and on the four bacterial isolates. Scanning electron microscopy and transmission electron microscopy coupled with spectrum imaging analysis based on energy-dispersive X-ray spectroscopy revealed a clear co-localization of U and phosphorus both on the surface and inside A. saprophilum diatoms and the associated bacterial cells. Time-resolved laser-induced fluorescence spectroscopy with parallel factor analysis identified similar U(VI) binding motifs both on A. saprophilum diatoms and the four bacterial isolates. This is the first work providing valuable microscopic and spectroscopic data on U localization and speciation within a diatom-bacterium system, demonstrating the contribution of the co-occurring bacteria to the overall interaction with U, a factor non-negligible for future modeling and assessment of radiological effects on living microorganisms.

Associations of multiple blood metals with cardiac structure and function: A cross-sectional study in a CAD population

Coronary artery disease (CAD) is often accompanied by abnormal cardiac structure and function, leading to an increased prognostic risk. However, less is known about the associations of mixed metals with abnormal cardiac structure and function in CAD patients. Here, we aimed to investigate the associations of exposure to metal mixtures with cardiac structure and function and potential interactions in a CAD population. We conducted a cross-sectional study from Southwest China that included 1555 CAD patients. The blood concentrations of 14 metals were measured via inductively coupled plasma spectrometry. CAD was defined as at least one vessel having stenosis ≥50% the vessel diameter. Echocardiography was used for cardiac structural and functional measurements. Bayesian kernel machine regression was applied to explore the overall effect, metal weight, and dose effect. Linear regression analysis was used to analyze the effects of single metals, metal‒metal interactions and metal‒traditional interactions. Finally, we found that the negative associations of mixed metals with cardiac structure was significant when the levels of all metals were below the 60th percentile. For cardiac function, changes in metals from 50th to 75th were associated with 0.954% and 0.683% decrease in left ventricular ejection fraction and left ventricular fractional shortening, respectively. Negative associations of copper and manganese with cardiac structure and function, whereas positive associations of titanium, selenium and molybdenum with several parameters were found. Antagonistic interactions between copper and tin and between selenium and several metals (manganese, copper and aluminum) (all Pinteraction terms < 0.05) were found. In conclusion, mixed metal exposure was negatively associated with cardiac structure and function in CAD patients. The main metals contributing to this negative associations were copper and manganese. Selenium or tin supplementation may reduce the adverse associations of copper and manganese with cardiac structure and function.

Novel benzoyl and acetyl pyrazine-2-carbohydrazonamide hybrid derivatives: Experimental and theoretical insights

A series of novel benzoyl and acetyl pyrazine-2-carbohydrazonamide hybrid derivatives, namely N’-benzoylpyrazine-2-carbohydrazonamide (1), N’-(4-methylbenzoyl)pyrazine-2-carbohydrazonamide (2), N’-(2-phenylacetyl)pyrazine-2-carbohydrazonamide (3) and N’-(2-(1H-indol-3-yl)acetyl)pyrazine-2-carbohydrazonamide (4), were readily obtained using a metallic Na-assisted interaction of 2-cyanopyrazine with benzohydrazide, 4-methylbenzohydrazide, 2-phenylacetohydrazide or 2-(1H-indol-3-yl)acetohydrazide in dry MeOH. Compounds 1–4 were studied by a set of physical measurements, including FTIR, 1H NMR and UV–vis spectroscopy, while their crystal structures were elucidated by single crystal X-ray diffraction and the corresponding crystal packing was further studied in detail using the Hirshfeld surface analysis. Compounds 3 and 4 were found to adopt both the E- and Z-isomeric forms in DMSO‑d6. Molecules of the title compounds are linked via NH⋯O and NH⋯N hydrogen bonds and π⋯π interactions, yielding supramolecular aggregates. As it was found by the Hirshfeld surface analysis, molecules of 1–4 mainly interact through the H⋯X (X = H, C, N and O) and C⋯X (X = C and N) contacts. The molecular interactions were quantified and compared using DFT calculations, molecular electrostatic potential (MEP) analysis and quantum theory of atoms in molecules (QTAIM) analysis, highlighting the dominant role of hydrogen bonding interactions in governing the crystal packing.

Mutual Influence of Contact Processes in the Simultaneous Interaction of Active and Inert Metal Melts with ZrO2 Ceramics

Mutual Influence of Contact Processes in the Simultaneous Interaction of Active and Inert Metal Melts with ZrO2 Ceramics

Impact of nickel and alkaline earth metals interaction on sustainable carbon nanotubes generation from plastic face masks via catalytic pyrolysis

The one-pot synthesis of carbon nanotubes (CNTs) emerges as a promising approach for plastic valorization, owing to its simplicity and scalability. However, limited attention has been given to catalyst design for this method, particularly regarding the influence of Group 2 alkaline earth metal elements (X) on the Ni-based catalyst activity. This study investigates the impact of X on the catalytic activity of Ni towards sustainable CNTs synthesis using plastic face masks. The findings revealed that X influenced the carbon yield of NiMo-X catalysts and the morphology of the resultant carbon nanomaterials. Notably, NiMo-Ca demonstrated the highest carbon yield, whereas NiMo-Mg and NiMo-Ba exhibited the lowest. Furthermore, NiMo-Mg tends to produce clean and thin CNTs, while NiMo-Ba tends to yield carbon flakes with numerous irregular cokes. In addition to the effect of Ni crystallite size, which influences the transition from tubular to flake-like carbon structures, environmental factors are also considered. Specifically, NiMo-Mg generated a high CO2/CH4 environment, while NiMo-Ba exhibited slower catalytic cracking of polymeric chains from face masks, both of which were unfavorable for CNTs growth. Conversely, NiMo-Ca facilitated higher carbon recovery, likely due to its creation of a low CO2/CH4 environment via CO2 methanation. Optimization studies indicated that increasing pyrolysis temperatures and durations lead to reduced carbon yield, while cyclic pyrolysis of face masks up to five iterations enhances the reusability of NiMo-X catalysts with improved carbon recovery. Overall, this study provides valuable insights into the early pyrolytic gas formation and carbon nucleation phase, which are influenced by the surface Ni fraction and Ni polarization, as well as the later CNTs growth phase, which is related to the Ni crystallite size.

Sorption of trace metals by macro- and microplastics within intertidal sediments: Insights from a long-term field study within Burrard Inlet, British Columbia, Canada

Plastics are now the dominant fraction of anthropogenic marine debris and as a result of their long residence times, it is important to determine the threats that plastics present to marine ecosystems including their ability to sorb a diversity of environmental pollutants such as trace metals. To address this knowledge gap, this study examined the sorption of cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn) by macro- and microplastics of polyethylene terephthalate (PETE) and high-density polyethylene (HDPE) within marine intertidal sediments in a human-impacted area of Burrard Inlet (British Columbia, Canada). Trace metal sorption by macro- and microplastics was dependent on 1) polymer characteristics, notably the aging of the plastic over the duration of the field experiment as shown by the formation of new peaks via FTIR spectra; and 2) amounts of sediment organic matter, where the sorption of trace metals by the plastic particles decreased with increasing organic matter content (from 2.8 % to 15.8 %). Plastic particles play a minor role in trace metals sorption in the presence of organic matter at high concentrations as a result of competitive adsorption. Overall, the interaction of trace metals with sediment plastics was highly dynamic and to understand the key processes controlling this dynamic requires further study. This work contributed to our understanding on metal-plastic interactions in coastal intertidal sediments from urban environments and serve to support plastic pollution risk management and bioremediation studies.

Electrochemical and Spectroscopic Investigations of Bismuth(III) Pharmaceuticals with L-Glutathione

Due to the importance of L-cysteine in the human system, the interaction of metals with this amino acid are worthy of investigation by various methods. In this laboratory1, we have investigated the interaction of bismuth(III) compounds with L-cysteine by both cyclic voltammetry and UV-VIS spectroscopy in an attempt to understand the role of bismuth in treating gastrointestinal maladies.2 The addition of bismuth(III) compounds to solutions of L-cysteine causes a negative potential shift for bismuth(III) reduction as an indication of complex formation between bismuth(III) and L-cysteine. This interaction is also evident by the appearance of a UV-VIS spectroscopic band at 340 nm (Bi-sulfur bond). Even at low pH values (pH 1.0), electrochemical studies show evidence of some kind of interaction even when there is no 340 nm band. These investigations have been conducted at pH 1.00 and 3.00 to simulate conditions in the human stomach and at pH 7.40 MOPS [(3-N-morpholino)propanesulfonic acid] to simulate general physiological conditions, in particular the intestinal tract. Recent work has involved extension of this work to L-glutathione, a tripeptide incorporating L-cysteine, under similar conditions. As might be expected, these interactions are considerably more complicated than those involving L-cysteine. As an example, there is a considerable positive potential shift for the reduction of bismuth(III) citrate in the presence of L-glutathione on the first and second voltammetric sweeps at gold and glassy carbon electrodes. This behavior evidently reflects the rather long (several seconds) time required for the re-formation of the bismuth complex with L-glutathione after its reductive ligand (L-glutathione) loss during bismuth(III) reduction on the first sweep. In addition, there is evidence of a film buildup on the electrode surface as observed by peak current increases during multiple potential sweeps. These observations are planned for inclusion in this symposium presentation.References T. Cheek and D. Peña, J. Electrochem. Soc., 167, 155522 (2020)Li, R. Wang, and H. Sun, Acc. Chem. Res., 52, 216 (2019).

Catalytic particles formation from thin nickel films for the synthesis of multi-walled carbon nanotubes

We have investigated the formation of a catalyst for the synthesis of multi-walled carbon nanotubes (MWCNT) using nickel-on-titanium thin films. Nickel decomposes into nanoparticles in the synthesis setup prior to MWCNT growing through the plasma enhanced chemical vapor deposition method. Oxidation and reduction of the catalyst are conducted to control the morphology of the formed nanoparticles array. In this case, the redox treatments required preventing the formation of silicides and Ti–Ni alloys are combined with the well-known effect of low-temperature disintegration (dewetting) of thin films. Detailed studies using a combination of Auger, atomic force, scanning (SEM), and transmission electron microscopy (TEM) show the interaction of metals on a silicon substrate, the influence of treatments parameters on the catalyst's state. The features and morphology of MWCNT synthesized on the obtained catalysts were studied via Raman spectroscopy, SEM and TEM. Overall, showing a link between the catalyst formation process and MWCNT growth, we demonstrate a technological and versatile method for controlling of nanotube growth for various applications.

Elevated Heavy Metal(loid) Blood and Feather Concentrations in Wetland Birds from Different Trophic Levels Indicate Exposure to Environmental Pollutants

The research assessed the exposure to total mercury (THg), lead (Pb), and arsenic (As) in Colombian wetland species of different trophic levels Platalea ajaja, Dendrocygna autumnalis and Nannopterum brasilianus. The results show high THg blood levels in P. ajaja (811.00 ± 349.60 µg L–1) and N. brasilianus (209.50 ± 27.92 µg L–1) with P. ajaja possibly exhibiting adverse effects. Blood Pb concentration was high in D. autumnalis (212.00 ± 208.10 µg L–1) and above the threshold for adverse effects, suggesting subclinical poisoning. Levels of blood As were below the assumed threshold for detrimental effect (20 μg L−1). The mean concentration of feather THg was below the assumed natural background levels (5 µg g−1) for all three species. Feather Pb levels exceeded the levels for assumed threshold effects in all sampled N. brasilianus (7.40 ± 0.51 µg g–1). Results for feather As concentration were below the threshold for adverse impacts in all species, although a positive correlation between As and THg concentrations was detected in P. ajaja feathers. The overall results could help understand how metal(loid)s biomagnify through trophic levels and how wetland species may serve as environmental indicators. By exploring the interactions of metal(loid)s within different matrices and body, this study offers insights into the dynamics of contaminant accumulation and distribution in the environment. This concept can be applied to wetlands worldwide, where bird species can serve as indicators of ecosystem health and the presence of contaminants such as heavy metals and metalloids.

Reproducing wrought grain structure in additive IN718 through nanosecond laser induced cavitation

Pulsed laser assisted additive manufacturing has been demonstrated as a promising technology for controlling grain structure in 3D-printing processes. The integration of a nanosecond laser onto a wire arc additive manufacturing tool has enabled the localized printing of Inconel 718 with grain sizes meeting ASTM 9 standards (average measured grain size of 13.7μm) for wrought material within a single bead under solidification conditions that would otherwise produce 340μm columnar grains. The observed grain refinement holds promise, provided scale up is possible, for overcoming the highly anisotropic mechanical properties and microcracking associated with large columnar grains of Inconel 718 that have long stood in the way of leveraging the advantages of direct energy deposition printing techniques of difficult to machine alloys. Experiments on large bead sizes allowed for decoupling surface versus bulk nanosecond laser/liquid metal interaction mechanisms to determine that the source of the observed grain refinement is the collapse of cavitation bubbles originating from acoustic waves generated by momentum transfer into the melt of an ablation plasma. Additionally, experiments that increased the cavitation bubble density within the mushy zone during solidification by tuning the nanosecond laser scan path went beyond the 25 times reduction in grain size to a 70 times factor of refinement with a minimum average grain diameter approaching 4μm.

Menadione sodium bisulfite as an efficient anti-corrosion additive for mild steel in acid corrosion: Electrochemical, surface morphological and theoretical studies

The corrosion inhibition behavior of Menadione Sodium Bisulfite (MSB) in 1.0 M HCl medium was evaluated using weight loss, electrochemical techniques (Tafel polarisation and Electrochemical impedance spectra), surface analysis (SEM and EDX), Density Functional Theory (DFT), Noncovalent interaction- Reduced Density Gradient (NCI-RDG) and Monte Carlo (MC) simulation techniques. Weight loss measurement showed that as inhibitor concentration increased, the corrosion rate decreased which means that a protective film formed on the metal surface. At 300 ppm, the inhibitor showed a maximum inhibition efficiency of 89.7 %. Tafel polarisation studies indicate that the inhibitor is mixed-type in nature. The inhibitor adsorption on the mild steel is the best fit for the Langmuir isotherm model. As the weak interaction of sodium and oxygen in the inhibitor molecules, the inhibitor exhibits two distinct equilibrium behaviors. (i) inhibitor with sodium (solid-state) and inhibitor without sodium (in liquid-state). These two behaviors were theoretically investigated using DFT and MD simulation studies. The inhibitor and metal interaction is further supported using these theoretical studies. The electron population of the inhibitor was analyzed using molecular electrostatic potential, NCI-RDG, Fukui function, and natural bond orbital analysis. These studies further give an understating of the inhibitor and metal interactions.

Remediation of Heavy Metal Pollution from Coal Mine Effluent Using Metal-Organic Frameworks (MOF): Impact of Water Media, Operational Factors and Metal Characteristics

The energy sector is the sector that generates the highest amount of environmental contamination, especially in water sources, mostly in the case of coal-based energy production. The aim of this study was to examine a significant contamination source, heavy metal contamination, in coal mining effluents. The current investigation introduces an MOF platform based on zirconium clusters and isophthalic acid with NH2-MIP-SO3H mixed amine and sulfonic acid functional groups in order to remove the most common heavy metal ions in coal mining effluents, including Hg, Cd, Pb, and Cu ions. The water matrix and the operational conditions were identified to be very influential in the removal process, such as the pH of water, the initial metal concentration and operating time. NH2-MIP-SO3H offers a great removal efficiency of metals starting from 745.83 mg/g for Cd, 673.67 mg/g for Cu, 589.85 mg/g for Hg, and 481.66 mg/g for Pb ions, with the Langmuir equation for equilibrium and pseudo-second-order equation for kinetics being the ideal models to express the equilibrium and kinetic data, respectively. A significant impact of water pH was found to occur, with the NH2-MIP-SO3H platform performing best at pH 6. Reuse of NH2-MIP-SO3H demonstrates excellent reusability, sustaining 90% of initial performance over eight regeneration cycles. The interaction of functional group-functional metal was the dominant mechanism in the removal process. The NH2-MIP-SO3H unique approach to heavy metal removal provides a very hopeful outlook for additional investigations in larger-scale studies.

Phosphine versus Carbene Metal Interactions: Bond Energies.

A variety of different ground-state structures of carbene and phosphine groups 1 and 2 cationic, group 11 cationic, and group 10 neutral complexes were studied using density functional theory (DFT) and correlated molecular orbital theory (CCSD(T)) methods. Geometries of complexes with phosphines were studied and compared to available experimental data. Among the three analyzed phosphine ligands, PH3, PMe3, and PPh3, PH3 was found to have noticeably smaller ligand binding energies (LBEs, ΔH298 K). PPh3 has the greatest LBEs with group 2 dications. The difference in LBEs for PMe3 and PPh3 in complexes with group 1 monocations and transition-metal (TM) complexes was significantly less pronounced. The stability and reactivity of phosphine complexes were analyzed and compared with those of previously studied N-heterocyclic carbenes (NHC). PH3 has smaller LBEs compared to NHC carbenes. The lower LBEs correlate with the hardness for M(11)+ complexes and correlate with both the hardness and ionic radii for the M(1)+ and M(2)2+ complexes. The presence of additional PH3 substituents on the metal center makes the LBE smaller compared to their unsubstituted or less substituted analogs. The presence of NH3 in a structure causes a smaller effect on binding, and, except for carbene-PtNH3, an increase in LBE was observed. Composite-correlated molecular orbital theory (G3MP2) was used to predict the LBE of various Lewis acidic ligands with PH3 and NHCs to contrast their binding behavior. Binding either phosphine or carbene to metal diamine complexes caused ligand exchange and transfer of NH3 to an outer coordination sphere.

Dynamic interaction of heavy metals and mineralogical shifts in stream sediments exposed to MSW landfill leachate in a semi-arid basaltic terrain

Investigating concentrations and spatial patterns of physicochemical parameters in landfill leachate and their profound impacts on stream sediments is an important issue for environmental sustainability. Therefore, the present study showed that the specifics landfill leachate and its interactions with stream sediments within the unique geological context of semi-arid basaltic terrain of the Deccan Volcanic Province in Pune, India. Employing advanced geo-accumulation indices and crystal phase differentiation methods, the study unveils the intricate metamorphosis of heavy metals and mineralogical composition, tracing the transformative journey from leachate to sediments. Noteworthy revelations emerge, particularly in the striking associations between heavy metals and the mineralogical composition, which encompasses primary and secondary minerals (calcite, quartz, and Fe–Mg oxides). These findings underscore the acceleration of weathering processes within this distinctive geological milieu. The 'geo-accumulation index' exhibits pronounced elevations in proximity to the landfill site, with persistence downstream, reliant upon the evolving weathering and accumulation dynamics. The lower reaches of the study area have higher concentrations of various heavy metals (Fe, Mn, Zn, Cr, Cu, Ni, Co, Hg, As, and Cd). These heavy metals are primarily sequestered within silt-dominated sediments conquered by augite, olivine and plagioclase minerals. Present research reveals the complex interplay between heavy metals in leachate and their physical and chemical interactions with sedimentary materials. These gradational shifts in mineralogy and geochemistry serve as compelling evidence of the transformative impact of leachate discharge within the distinctive basaltic geological framework. This study offers valuable insights into the complex environmental processes occurring at the intersection of landfill leachate and natural geological formations, enhancing the understanding of the dynamic geochemical interactions that shape this semi-arid basaltic terrain.

Toxic effects of trace metal(loid) mixtures on aquatic organisms

The co-occurrence of metal (loid)s in realistic aquatic environments necessitates the evaluation of their combined effects. However, the generality of the additive effect hypothesis is contentious, particularly due to metal(loid)-metal(loid) interactions. The absence of systematic evaluation approaches restricts our ability to draw overall conclusions and make reliable predictions. In this study, we reviewed 1473 effect sizes from 38 publications, and classified all responses into seven main categories (from molecular to individual levels) according to their toxicological significance. Our meta-analysis revealed that metal(loid) mixtures had significant effects on aquatic organisms (33 %, 95 % CI 28 %–39 %, P < 0.05), along with significant response heterogeneity (Qt = 690,319.62, P < 0.0001; I2 = 99.95 %). Concurrently, we developed a Random Forest machine learning model to predict adverse effects and identify key variables. These two methods demonstrated that the toxicity of metal(loid) mixtures is primarily linked to the choice of toxicity endpoints, and the characteristics of metal(loid) mixtures. Our findings underscore the potential of combining meta-analysis with machine learning, a more systematic approach, to enhance the understanding and prediction of the adverse effects of metal(loid) mixtures, and they offer guidance for risk assessment and policy-making in complex environmental scenarios.

The critical role of organic matter for cadmium-lead interactions in soil: Mechanisms and risks

Understanding the interaction mechanisms between complex heavy metals and soil components is a prerequisite for effectively forecasting the mobility and availability of contaminants in soils. Soil organic matter (SOM), with its diverse functional groups, has long been a focal point of research interest. In this study, four soils with manipulated levels of SOM, cadmium (Cd) and lead (Pb) were subjected to a 90-day incubation experiment. The competitive interactions between Cd and Pb in soils were investigated using Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray adsorption near-edge structure (XANES) analysis. Our results indicate that Pb competed with Cd for adsorption sites on the surface of SOM, particularly on carboxyl and hydroxyl functional groups. Approximately 22.6 % of Cd adsorption sites on humus were occupied by Pb. The use of sequentially extracted exchangeable heavy metals as indicators for environment risk assessments, considering variations in soil physico-chemical properties and synergistic or antagonistic effects between contaminants, provides a better estimation of metal bioavailability and its potential impacts. Integrating comprehensive contamination characterization of heavy metal interactions with the soil organic phase is an important advancement to assess the environmental risks of heavy metal dynamics in soil compared to individual contamination assessments.

Heavy Metal Interactions with Neuroglia and Gut Microbiota: Implications for Huntington's Disease.

Huntington's disease (HD) is a rare but progressive and devastating neurodegenerative disease characterized by involuntary movements, cognitive decline, executive dysfunction, and neuropsychiatric conditions such as anxiety and depression. It follows an autosomal dominant inheritance pattern. Thus, a child who has a parent with the mutated huntingtin (mHTT) gene has a 50% chance of developing the disease. Since the HTT protein is involved in many critical cellular processes, including neurogenesis, brain development, energy metabolism, transcriptional regulation, synaptic activity, vesicle trafficking, cell signaling, and autophagy, its aberrant aggregates lead to the disruption of numerous cellular pathways and neurodegeneration. Essential heavy metals are vital at low concentrations; however, at higher concentrations, they can exacerbate HD by disrupting glial-neuronal communication and/or causing dysbiosis (disturbance in the gut microbiota, GM), both of which can lead to neuroinflammation and further neurodegeneration. Here, we discuss in detail the interactions of iron, manganese, and copper with glial-neuron communication and GM and indicate how this knowledge may pave the way for the development of a new generation of disease-modifying therapies in HD.