Priority sources identification and risks assessment of heavy metal(loid)s in agricultural soils of a typical antimony mining watershed.

Heavy metal(loid) (HM) pollution in agricultural soils has become an environmental concern in antimony (Sb) mining areas. However, priority pollution sources identification and deep understanding of environmental risks of HMs face great challenges due to multiple and complex pollution sources coexist. Herein, an integrated approach was conducted to distinguish pollution sources and assess human health risk (HHR) and ecological risk (ER) in a typical Sb mining watershed in Southern China. This approach combines absolute principal component score-multiple linear regression (APCS-MLR) and positive matrix factorization (PMF) models with ER and HHR assessments. Four pollution sources were distinguished for both models, and APCS-MLR model was more accurate and plausible. Predominant HM concentration source was natural source (39.1%), followed by industrial and agricultural activities (23.0%), unknown sources (21.5%) and Sb mining and smelting activities (16.4%). Although natural source contributed the most to HM concentrations, it did not pose a significant ER. Industrial and agricultural activities predominantly contributed to ER, and attention should be paid to Cd and Sb. Sb mining and smelting activities were primary anthropogenic sources of HHR, particularly Sb and As contaminations. Considering ER and HHR assessments, Sb mining and smelting, and industrial and agricultural activities are critical sources, causing serious ecological and health threats. This study showed the advantages of multiple receptor model application in obtaining reliable source identification and providing better source-oriented risk assessments. HM pollution management, such as regulating mining and smelting and implementing soil remediation in polluted agricultural soils, is strongly recommended for protecting ecosystems and humans.

Simultaneous immobilization of multiple heavy metal(loid)s in contaminated water and alkaline soil inoculated Fe/Mn oxidizing bacterium.

Two strains of Fe/Mn oxidizing bacteria tolerant to high concentrations of multiple heavy metal(loid)s and efficient decontamination for them were screened. The surface of the bio-Fe/Mn oxides produced by the oxidation of Fe(II) and Mn(II) by Pseudomonas taiwanensis (marked as P4) and Pseudomonas plecoglossicida (marked as G1) contains rich reactive oxygen functional groups, which play critical roles in the removal efficiency and immobilization of heavy metal(loid)s in co-contamination system. The isolated strains P4 and G1 can grow well in the following environments: pH 5-9, NaCl 0-4%, and temperature 20-30°C. The removal efficiencies of Fe, Pb, As, Zn, Cd, Cu, and Mn are effective after inoculation of the strains P4 and G1 in the simulated water system (the initial concentrations of heavy metal(loid) were 1 mg/L), approximately reaching 96%, 92%, 85%, 67%, 70%, 54% and 15%, respectively. The exchangeable and carbonate bound As, Cd, Pb and Cu are more inclined to convert to the Fe-Mn oxide bound fractions in P4 and G1 treated soil, thereby reducing the phytoavailability and bioaccessible of heavy metal(loid)s. This research provides alternatives method to treat water and soil containing high concentrations of multi-heavy metal(loid)s.

Ultrasonic humidifier aerosols: Observed high heavy metal enrichment and a new emission control method.

Ultrasonic humidifiers are commonly used in households to maintain indoor humidity and generate a large number of droplets or spray aerosols. However, there have been various health concerns associated with humidifier use, largely due to aerosols generated during operation. Here, we investigated the size distribution, chemical composition, and charged fraction of aerosol particles emitted from commercial ultrasonic humidifiers. Heavy metals in water used for humidifiers were found to be highly enriched in the ultrasonic humidifier aerosols (UHA), with the enrichment factors ranging from 102 to 107. This enrichment may pose health concerns for the building occupants, as UHA concentrations of up to 106 particles/cm3 or 3 mg/m3 were observed. Furthermore, approximately 90% of UHA were observed to be electrically charged, for the first time according to our knowledge. Based on this discovery, we proposed and tested a new method to remove UHA by using a simple electrical field. The designed electrical field in this work can efficiently remove 81.4% of UHA. Therefore, applying this electrical field could be an effective method to significantly reduce the health risks by UHA.

Biochar with KMnO4-hematite modification promoted foxtail millet growth by alleviating soil Cd and Zn biotoxicity.

The excessive accumulation of Cd and Zn in soil poisons crops and threatens food safety. In this study, KMnO4-hematite modified biochar (MnFeB) was developed and applied to remediate weakly alkaline Cd-Zn contaminated soil, and the heavy metal immobilization effect, plant growth, and metal ion uptake of foxtail millet were studied. MnFeB application reduced the phytotoxicity of soil heavy metals; bioavailable acid-soluble Cd and Zn were reduced by 57.79% and 35.64%, respectively, whereas stable, non-bioavailable, residual Cd and Zn increased by 96.44% and 32.08%, respectively. The chlorophyll and total protein contents and the superoxide dismutase (SOD)activity were enhanced, whereas proline, malondialdehyde, the H2O2 content, glutathione reductase (GR), ascorbate peroxidase (APX) and catalase (CAT) activities were reduced. Accordingly, the expressions of GR, APX, and CAT were downregulated, whereas the expression of MnSOD was upregulated. In addition, MnFeB promoted the net photosynthetic rate and growth of foxtail millet plants. Furthermore, MnFeB reduced the levels of Cd and Zn in the stems, leaves, and grains, decreased the bioconcentration factor of Cd and Zn in shoots, and weakened the translocation of Cd and Zn from roots to shoots. Precipitation, complexation, oxidation-reduction, ion exchange, and π-π stacking interaction were the main Cd and Zn immobilization mechanisms, and MnFeB reduced the soil bacterial community diversity and the relative abundance of Proteobacteria and Planctomycetota. This study provides a feasible and effective remediation material for Cd- and Zn-contaminated soils.

Enhanced electrocatalytic activity in MOFs-derived 3D hollow NiCo-LDH nanocages decorated porous biochar for simultaneously ultra-sensitive electrochemical sensing of Cu2+ and Hg2.

Layered double hydroxides (LDHs) have attracted significant attention due to their compositional and structural flexibility. However, it is challenging but meaningful to design and fabricate hierarchical mixed-dimensional LDHs with synergistic effects to increase the electrical conductivity of LDHs and promote the intrinsic activity. Herein, 3D hollow NiCo-LDH nanocages decorated porous biochar (3D NiCo-LDH/PBC) has been synthesized by using ZIF-67 as precursor, which was utilized for constructing electrochemical sensing platform to realize simultaneous determination of Cu2+ and Hg2+. The 3D NiCo-LDH/PBC possessed the characteristics of hollow material and three-dimensional porous material, revealing a larger surface area, more exposed active sites, and faster electron transfer, which is beneficial to enhancing its electrochemical performance. Consequently, the developed sensor displayed good performance for simultaneously detecting Cu2+ and Hg2+ with ultra-low limit of detection (LOD) of 0.03 µg L-1 and 0.03 µg L-1, respectively. The proposed sensor also demonstrated excellent stability, repeatability and reproducibility. Furthermore, the sensor can be successfully used for the electrochemical analysis of Cu2+ and Hg2+ in lake water sample with satisfactory recovery, which is of great feasibility for practical application.

Development of a continuous electrochemical reactor incorporated with waste-derived activated carbon electrode for the effective removal of hexavalent chromium from industrial effluent.

Being a recognized carcinogen, hexavalent chromium is hazardous to both human and environmental health. Thus, it is imperative to regulate and oversee their levels in a variety of industries, including textiles, dyes, pigments, and metal finishing. This study strives to reduce Cr(VI) in wastewater by using capacitive deionization in conjunction with an activated carbon-based electrode and a continuous electrochemical reactor (CER). Activated carbon derived from rubberwood sawdust demonstrated excellent properties, including a high surface area of 1157 m2 g-1. The electrical conductivity and mechanical stability of the electrode were enhanced by the incorporation of synthesized expanded graphite (EG) into the AC. Key parameters were optimized via systematic batch electroreduction experiments with an optimal response surface design. The efficacy of the fabricated CER was proved when it successfully reduced Cr(VI) in a 5 mg L-1 solution within 15 min under optimized conditions, in contrast to the considerably longer durations anticipated by conventional methods. Validation of these findings was done by treating industrial wastewater of 30 mg L-1 in the CER. The electroreduction of Cr(VI) followed the Langmuir isotherm with a maximum capacity of 13.491 mg g-1 and pseudo-second-order kinetics. These results indicate that the combined use of the modified AC electrode and CER holds potential as a sustainable and economical approach to effectively eliminate Cr(VI) from wastewater.

Scenedesmus sp. as a phycoremediation agent for heavy metal removal from landfill leachate in a comparative study: batch, continuous, and membrane bioreactor (MBR).

Improper disposal of municipal solid waste led to the release of heavy metals into the environment through leachate accumulation, causing a range of health and environmental problems. Phycoremediation, using microalgae to remove heavy metals from contaminated water, was investigated as a promising alternative to traditional remediation methods. This study explored the potential of Scenedesmus sp. as a phycoremediation agent for heavy metal removal from landfill leachate. The study was conducted in batch, continuous, and membrane bioreactor (MBR). In the batch system, Scenedesmus sp. was added to the leachate and incubated for 15 days before the biomass was separated from the suspension. In the continuous system, Scenedesmus sp. was cultured in a flow-through system, and the leachate was continuously fed into the system with flow rates measured at 120, 150, and 180 mL/h for 27 days. The MBR system was similar to the continuous system, but it incorporated a membrane filtration step to remove suspended solids from the treated water. The peristaltic pump was calibrated to operate at five different flow rates: 0.24 L/h, 0.30 L/h, 0.36 L/h, 0.42 L/h, and 0.48 L/h for the MBR system and ran for 24 h. The results showed that Scenedesmus sp. was effective in removing heavy metals such as lead (Pb), cobalt (Co), chromium (Cr), nickel (Ni), and zinc (Zn) from landfill leachate in all three systems. The highest removal efficiency was observed for Ni, with a removal of 0.083 mg/L in the MBR and 0.068 mg/L in batch mode. The lowest removal efficiency was observed for Zn, with a removal of 0.032 mg/L in the MBR, 0.027 mg/L in continuous mode, and 0.022 mg/L in batch mode. The findings depicted that the adsorption capacity varied among the studied metal ions, with the highest capacity observed for Ni (II) and the lowest for Zn (II), reflecting differences in metal speciation, surface charge interactions, and affinity for the adsorbent material. These factors influenced the adsorption process and resulted in varying adsorption capacities for different metal ions. The study also evaluated the biomass growth of Scenedesmus sp. and found that it was significantly influenced by the initial metal concentration in the leachate. The results of this study suggest that Scenedesmus sp. can be used as an effective phycoremediation agent for removing heavy metals from landfill leachate.

Soil quality and heavy metal contamination in an open dumpsite in Navrongo, Ghana.

The increasing proximity of the Dudumbia dumpsite, an open dumpsite in Navrongo, Ghana, to human settlements necessitates an investigation of the soil quality to safeguard the environment from heavy metal toxicity. This study examined the impact of waste dumping activities on the physicochemical properties of the soil, as well as the level of heavy metal (Pb, Cd, Ni, Cr, As, Hg, Cu, Mn, and Zn) contamination and associated risks. Various contamination and risk assessment tools were used, including the geoaccumulation index (Igeo), pollution load index (PLI), potential ecological risk (Er), and potential ecological risk index (PERI). The study found significant improvements in notable soil attributes such as phosphorus (P), organic carbon (C), total nitrogen (N), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), and effective cation exchange capacity, with percentage increases ranging from 50.8 to 2078.3%. Igeo values ranged from 2.07 to 6.20, indicating contamination levels from moderate to extreme. The PLI and PERI values were 16.241 and 1810, respectively. The Er values for the heavy metals ranged from 36 to 607, indicating ecological risk levels from low to very high, with Cd and Hg posing very high risks. These results suggest that while the dumpsite soil shows improvements in some characteristics favourable for plant cultivation, waste dumping significantly contributes to heavy metal contamination. The soil at the dumpsite is deteriorated and poses significant health risks, particularly due to Cd and Hg. Therefore, remediation efforts should prioritise mitigating the risks posed by Cd and Hg.

Underlying mechanism of Dendrobium huoshanense resistance to lead stress using the quantitative proteomics method.

Lead affects photosynthesis and growth and has serious toxic effects on plants. Here, the differential expressed proteins (DEPs) in D. huoshanense were investigated under different applications of lead acetate solutions. Using label-free quantitative proteomics methods, more than 12,000 peptides and 2,449 proteins were identified. GO and KEGG functional annotations show that these differential proteins mainly participate in carbohydrate metabolism, energy metabolism, amino acid metabolism, translation, protein folding, sorting, and degradation, as well as oxidation and reduction processes. A total of 636 DEPs were identified, and lead could induce the expression of most proteins. KEGG enrichment analysis suggested that proteins involved in processes such as homologous recombination, vitamin B6 metabolism, flavonoid biosynthesis, cellular component organisation or biogenesis, and biological regulation were significantly enriched. Nearly 40 proteins are involved in DNA replication and repair, RNA synthesis, transport, and splicing. The effect of lead stress on D. huoshanense may be achieved through photosynthesis, oxidative phosphorylation, and the production of excess antioxidant substances. The expression of 9 photosynthesis-related proteins and 12 oxidative phosphorylation-related proteins was up-regulated after lead stress. Furthermore, a total of 3 SOD, 12 POD, 3 CAT, and 7 ascorbate-related metabolic enzymes were identified. Under lead stress, almost all key enzymes involved in the synthesis of antioxidant substances are up-regulated, which may facilitate the scavenging of oxygen-free radical scavenging. The expression levels of some key enzymes involved in sugar and glycoside synthesis, the phenylpropanoid synthesis pathway, and the terpene synthesis pathway also increased. More than 30 proteins involved in heavy metal transport were also identified. Expression profiling revealed a significant rise in the expression of the ABC-type multidrug resistance transporter, copper chaperone, and P-type ATPase with exposure to lead stress. Our findings lay the basis for research on the response and resistance of D. huoshanense to heavy metal stress.

Association between heavy metals exposure and persistent infections: the mediating role of immune function.

Introduction: Persistent infections caused by certain viruses and parasites have been associated with multiple diseases and substantial mortality. Heavy metals are ubiquitous environmental pollutants with immunosuppressive properties. This study aimed to determine whether heavy metals exposure suppress the immune system, thereby increasing the susceptibility to persistent infections. Methods: Using data from NHANES 1999-2016, we explored the associations between heavy metals exposure and persistent infections: Cytomegalovirus (CMV), Epstein-Barr Virus (EBV), Hepatitis C Virus (HCV), Herpes Simplex Virus Type-1 (HSV-1), Toxoplasma gondii (T. gondii), and Toxocara canis and Toxocara cati (Toxocara spp.) by performing logistic regression, weighted quantile sum (WQS) and Bayesian kernel machine regression (BKMR) models. Mediation analysis was used to determine the mediating role of host immune function in these associations. Results: Logistic regression analysis revealed positive associations between multiple heavy metals and the increased risk of persistent infections. In WQS models, the heavy metals mixture was associated with increased risks of several persistent infections: CMV (OR: 1.58; 95% CI: 1.17, 2.14), HCV (OR: 2.94; 95% CI: 1.68, 5.16), HSV-1 (OR: 1.25; 95% CI: 1.11, 1.42), T. gondii (OR: 1.97; 95% CI: 1.41, 2.76), and Toxocara spp. (OR: 1.76; 95% CI: 1.16, 2.66). BKMR models further confirmed the combined effects of heavy metals mixture and also identified the individual effect of arsenic, cadmium, and lead. On mediation analysis, the systemic immune inflammation index, which reflects the host's immune status, mediated 12.14% of the association of mixed heavy metals exposure with HSV-1 infection. Discussion: The findings of this study revealed that heavy metals exposure may increase susceptibility to persistent infections, with the host's immune status potentially mediating this relationship. Reducing exposure to heavy metals may have preventive implications for persistent infections, and further prospective studies are needed to confirm these findings.

Biotechnological approaches for enhancement of heavy metal phytoremediation capacity of plants.

Heavy metals are extremely hazardous for human health due to their toxic effects. They are non-biodegradable in nature, thus remain in the environment and enter and accumulate in the human body through biomagnification; hence, there is a serious need of their remediation. Phytoremediation has emerged as a green, sustainable, and effective solution for heavy metal removal and many plant species could be employed for this purpose. Plants are able to sequester substantial quantity of heavy metals, in some cases thousands of ppm, due to their robust physiology enabling high metal tolerance and anatomy supporting metal ion accumulation. Identification and modification of potential target genes involved in heavy metal accumulation have led to improved phytoremediation capacity of plants at the molecular level. The introduction of foreign genes through genetic engineering approaches has further enhanced phytoremediation capacity manifolds. This review gives an insight towards improving the phytoremediation efficiency through a better understanding of molecular mechanisms involved, expression of different proteins, genetic engineering approaches for transgenic production, and genetic modifications. It also comprehends novel omics tools such as genomics, metabolomics, proteomics, transcriptomics, and genome editing technologies for improvement of phytoremediation ability of plants.

Copper, lead, and cadmium monitoring via the small-spotted catshark (Scyliorhinus canicula; Linnaeus, 1758): space-time driven variability in Western Mediterranean populations.

The philopatric and sedentary nature of female S. canicula, its high abundance as a bycatch and resilience to regular exploitation by bottom trawl fisheries and its widespread distribution, makes it a potentially good candidate as a biomonitor species. To evaluate this potential, microwave-assisted extraction (MAE) and Graphite Furnace Atomic Absorption Spectrometry (GF-AAS) were used to analyse Pb, Cd, and Cu in muscle tissue of individuals captured in the Western Mediterranean (Alicante, Spain). A monthly assessment of the concentration of these three analytes was conducted from November 2019 to November 2020 with 300 individuals. Results showed the existence of slightly higher mean concentrations during warmer seasons for Pb and Cd with mean concentrations for Pb and Cu peaking in Autumn 2019 and during Spring 2020 in the case of Cd. Significant differences in analyte concentrations found between non-consecutive months suggested gradual variability in time. Although space-wise, time-persistent concentration hotspots were observed throughout the sample area, the magnitude of these appeared to be variable in time and should be evaluated in future studies.

Economic valuation and characterization of heavy metal contamination in Dal Lake Srinagar, Kashmir, India.

Dal Lake, the world-famous tourist attraction has been polluted by allochthonous and autochthonous sources, as a result the heavy metal (HMs) concentrations within the water body has reached the toxic levels which is endangering the lives of the people. A study was carried out during the year 2021 (i) to determine the concentration of HMs (molybdenum: Mo, arsenic: Ar, cadmium: Cd, lead: Pb) at the four designated sites of Dal Lake, and (ii) a public survey (400 persons) involving economic valuation of water body in terms of recreational use and other benefits. The highest values of biological oxygen demand (BOD) and chemical oxygen demand (COD) within the Dal Lake were recorded at site A, which were 31 ± 1.10 mg/l and 76 ± 0.64, respectively. Similarly, maximum nitrate nitrogen was found at site A (865 ± 0.86 µg/l). The highest value of Pb was reported (6.828 ± 0.003 ppb) from site A whereas, the lowest from site B (2.492 ± 0.002 ppb). The mean values of Mo concentrations (in ppb) were found to be 2.538 ± 0.002, 1.703 ± 0.003, 3.627 ± 0.004 and 4.787 ± 0.002 at the four sites respectively. The observed values of HMs (in ppb) were much higher than the permissible values (WHO, 2006) and those reported earlier. A huge amount of money (Rs 16,18,66,000/) is being generated from the floating gardens of Dal Lake, calculated by TCM and CVM methods. During the survey, 68 % of people showed a willingness to pay (WTP) for the restoration of the Dal Lake and improved services (mean value: Rs 62,852.20/). Thus, the monitoring and assessment were done to find out how the Dal Lake contributes to the economy of the state by way of its different services and the major attraction for tourists besides the possible reasons for the deterioration of water quality, in order to find a long-lasting solution for the sustainable conservation of Dal Lake.

Analyzing the impact of heavy metal exposure on osteoarthritis and rheumatoid arthritis: an approach based on interpretable machine learning.

Introduction: This investigation leverages advanced machine learning (ML) techniques to dissect the complex relationship between heavy metal exposure and its impacts on osteoarthritis (OA) and rheumatoid arthritis (RA). Utilizing a comprehensive dataset from the National Health and Nutrition Examination Survey (NHANES) spanning from 2003 to 2020, this study aims to elucidate the roles specific heavy metals play in the incidence and differentiation of OA and RA. Methods: Employing a phased ML strategy that encompasses a range of methodologies, including LASSO regression and SHapley Additive exPlanations (SHAP), our analytical framework integrates demographic, laboratory, and questionnaire data. Thirteen distinct ML models were applied across seven methodologies to enhance the predictability and interpretability of clinical outcomes. Each phase of model development was meticulously designed to progressively refine the algorithm's performance. Results: The results reveal significant associations between certain heavy metals and an increased risk of arthritis. The phased ML approach enabled the precise identification of key predictors and their contributions to disease outcomes. Discussion: These findings offer new insights into potential pathways for early detection, prevention, and management strategies for arthritis associated with environmental exposures. By improving the interpretability of ML models, this research provides a potent tool for clinicians and researchers, facilitating a deeper understanding of the environmental determinants of arthritis.

Assessment of heavy metal contamination in the surface sediments, seawater and organisms of the Pearl River Estuary, South China Sea.

Coastal heavy-metal contamination poses significant risks to marine ecosystems and human health, necessitating comprehensive research for effective mitigation strategies. This study assessed heavy-metal pollution in sediments, seawater, and organisms in the Pearl River Estuary (PRE), with a focus on Cd, Cu, Pb, Zn, As, Hg, and Cr. A notable reduction in heavy metal concentrations in surface sediments was observed in 2020 compared to 2017 and 2018, likely due to improved pollution management and COVID-19 pandemic restrictions. Spatial analysis revealed a positive correlation between elevated heavy-metal concentrations (Cu, Pb, Zn, Cd, and As) and areas with significant human activity. Source analysis indicated that anthropogenic activities accounted for 63 % of the heavy metals in sediments, originating from industrial effluents, metal processing, vehicular activities, and fossil fuel combustion. Cd presented a high ecological risk due to its significant enrichment in surface sediments. Organisms in the PRE were found to be relatively enriched with Hg and Cu, with average As concentrations slightly exceeding the Chinese food-health criterion. This study identified high-risk ecological zones and highlighted Cd as the primary pollutant in the PRE. The findings demonstrate the effectiveness of recent pollution control measures and emphasize the need for ongoing monitoring and mitigation to safeguard marine ecosystems and human health.

Functional genomics and taxonomic insights into heavy metal tolerant novel bacterium Brevibacterium metallidurans sp. nov. NCCP-602T isolated from tannery effluent in Pakistan.

The strain designated NCCP-602T was isolated from tannery effluent, and displayed aerobic, gram-positive, rod-shaped cells that were characterized by oxidase negative, catalase positive, and non-motile features. The most favourable growth conditions were observed at a temperature of 30°C, pH 7.0, and NaCl concentration of 1% (w/v). It tolerated heavy metals at high concentrations of chromium (3600 ppm), copper (3300 ppm), cadmium (3000 ppm), arsenic (1200 ppm) and lead (1500 ppm). The results of phylogenetic analysis, derived from sequences of the 16S rRNA gene, indicated the position of strain NCCP-602T within genus Brevibacterium and showed that it was closely related to Brevibacterium ammoniilyticum JCM 17537T. Strain NCCP-602 T formed a robust branch that was clearly separate from closely related taxa. A comparison of 16S rRNA gene sequence similarity and dDDH values between the closely related type strains and strain NCCP-602T provided additional evidence supporting the classification of strain NCCP-602T as a distinct novel genospecies. The polar lipid profile included diphosphatidylglycerol, glycolipid, phospholipids and amino lipids. MK-7 and MK-8 were found as the respiratory quinones, while anteiso-C15:0, iso-C15:0, iso-C16:0, iso-C17:0, and anteiso-C17:0 were identified as the predominant cellular fatty acids (> 10%). Considering the convergence of phylogenetic, phenotypic, chemotaxonomic, and genotypic traits, it is suggested that strain NCCP-602 T be classified as a distinct species Brevibacterium metallidurans sp. nov. within genus Brevibacterium with type strain NCCP-602T (JCM 18882T = CGMCC1.62055T).

Adsorption and ion exchange of toxic metals by Brazilian clays: clay selection and studies of equilibrium, thermodynamics, and binary ion exchange modeling.

In this study, four Brazilian clays (Bofe, Verde-lodo, commercial Fluidgel, and expanded commercial vermiculite) were evaluated for their adsorptive capacity and removal percentage in relation to different toxic metals (Ni2+, Cd2+, Zn2+, and Cu2+). The best results were obtained by expanded vermiculite, with cadmium removal reaching values of 95%. The most promising clay was modified by the sodification process, and the metal cadmium was used to evaluate the ion exchange process. The clays expanded vermiculite (EV) and VNa-sodified vermiculite were evaluated by equilibrium study at 25, 35, and 45 °C. At 25 °C, EV obtained a maximum adsorption capacity of 0.368 mmol/g and sodified vermiculite 0.480 mmol/g, which represents an improvement of 30.4% in modified clay capacity. At 45 °C, the sodified vermiculite reached 0.970 mmol/g adsorption capacity. The Langmuir, Redlich-Peterson Freundlich, and Dubinin-Raduskevich models were adjusted to the results. Langmuir provided the best fit among the models. The thermodynamic quantities (ΔS, ΔH, and ΔG) demonstrated that the process is spontaneous and endothermic and the metal is captured by physisorption and chemisorption in the studied temperature range. For the ion exchange equilibrium, the binary Langmuir and binary Langmuir-Freundlich models were adjusted to the expanded vermiculite and sodified vermiculite isotherms, respectively. Both models were predictive. Thermal analysis indicated good heat resistance even after material modification. The apparent and real densities demonstrated that after each treatment or contamination, the clayey material undergoes contraction in its structure. An improved efficiency of the adsorbent was found after sodification.

Protective Role of Polyethylene Glycol Towards the Damaging Effects of Cadmium.

This study aimed to evaluate the role of drought-induced changes in the effects of cadmium (Cd) in plants. Cd is the most hazardous and important environmental pollutant. Water deficit is the most common environmental stress encountered by plants and affects most of the plant functions. The present study assessed the effect of Cd and water deficit on Capsicum frutescens seedlings in single and combined treatments. The seedlings of Capsicum were grown in a hydroponic solution and treated with Cd. The seedlings were subjected to water deficit with the help of polyethylene glycol (PEG). The other set of seedlings was treated with combined Cd + PEG. In the absence of PEG, maximum Cd accumulation was observed. The root and shoot growth of the seedlings were affected under all treatments with maximum inhibition in Cd. Pigment, protein and sugar contents and nitrate reductase activity decreased significantly in all treatments, while proline content increased. Induction of oxidative damage occurred through the formation of free radicals which caused alteration in electrolyte leakage, lipid peroxidation and activities of antioxidant enzymes, viz. superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase and non-enzymatic non-protein thiol content and ascorbic acid in the stressed seedlings. Water deficit buttressed the toxic effect of Cd on chilli seedlings.

Mitigating pb toxicity in Sesbania sesban L. through activated charcoal supplementation: a hydroponic study on enhanced phytoremediation.

BACKGROUND: Soil contamination by heavy metals is a critical environmental challenge, with Pb being of particular concern due to its propensity to be readily absorbed and accumulated by plants, despite its lack of essential biological functions or beneficial roles in cellular metabolism. Within the scope of phytoremediation, the use of plants for the decontamination of various environmental matrices, the present study investigated the potential of activated charcoal (AC) to enhance the tolerance and mitigation capacity of S. sesban seedlings when exposed to Pb. The experiment was conducted as a factorial arrangement in a completely randomized design in hydroponic conditions. The S. sesban seedlings were subjected to a gradient of Pb concentrations (0, 0.02, 0.2, 2, and 10 mg/L) within the nutrient solution, alongside two distinct AC treatments (0 and 1% inclusion in the culture media). The study reached its conclusion after 60 days. RESULTS: The seedlings exposed to Pb without AC supplementation indicated an escalation in peroxidase (POX) activity, reactive oxygen species (ROS), and malondialdehyde (MDA) levels, signaling an increase in oxidative stress. Conversely, the incorporation of AC into the treatment regime markedly bolstered the antioxidative defense system, as evidenced by the significant elevation in antioxidant capacity and a concomitant reduction in the biomarkers of oxidative stress (POX, ROS, and MDA). CONCLUSIONS: With AC application, a notable improvement was observed in the chlorophyll a, total chlorophyll, and plant fresh and dry biomass. These findings illuminate the role of activated charcoal as a viable adjunct in phytoremediation strategies aimed at ameliorating heavy metal stress in plants.

Structural alterations in scales of Capoeta capoeta (Güldenstädt, 1773) from heavy metal-contaminated river water.

Heavy metal pollution, especially in freshwater, is a serious problem for aquatic organisms and human health. In this study, the scales of Capoeta capoeta living in the Karasu River (Turkey), which is estimated to be contaminated with pollutants, especially heavy metals, were examined for structural anomalies. Two stations on the river were selected for this purpose. Fish and surface water samples were taken at the stations. The heavy metal analyses were carried out in the water and the fish tissue. Heavy metal pollution was detected in the surface water. It was also observed that some heavy metals (As, Cu, Cd, Cr, Mn, Pb, Ni, Zn) accumulate in the fish tissue. Significant structural differences were observed on the dorsal surface of the scales, such as interrupted primary radii, damaged circuli, damaged focus, damaged anterior scale margin, broken focus, deformed scale structure, scattered chromatophores, dilatation of primary radii, loss of focus, damaged annuli, symmetry shift in the lateral line canal, eroded circuli, damaged posterior scale margin, double focus, branching in the primary radii, asymmetric circuli, incomplete annuli and interrupted secondary radii in each of the fish collected from the contaminated site. Heavy metals are suspected to be responsible for the structural anomalies in the scales. Based on these observations, it can be said that fish scales can be used as an effective indicator of water quality.