Mobility Of Metals Research Articles

Storage of household and greenhouse ashes on the surface of sandy soils: consequences for the soil environment.

In households and greenhouses, fuel combustion generates ashes that are sometimes deposited on the of soil surface. The consequences of the deposition of such wastes on soil properties are not well known. Therefore, this study determines these geochemical processes (effects of the deposition of household and greenhouse ashes on buried sandy soils) and soil-forming processes. The study reveals that the deposition of household ashes increases the pH of buried Arenosols, while greenhouse ashes do not raise the pH of buried soil. The increased pH of buried soils caused by household ashes arises from calcite dissolution, Ca and K mobilisation, and Ca and K trapping by coatings on quartz grains. In turn, pozzolanic reactions and the crystallisation of gypsum (or a mixture of calcite and gypsum) on the surface of coke in greenhouse ashes limit Ca leaching downwards in the soil profile. Soil horizons with household and greenhouse ashes are characterised by relatively high contents of metal(loid)s. Furthermore, the mobilisation of metal(loid)s is evidenced from horizons containing both types of combustion wastes downwards in the soil profiles. The contents of Mn, Ti, Zn, Cd, Sr, As, Cr, V, and Ba in sandy horizons buried by household ashes are higher than the contents of these elements in soils, reflecting the local geochemical background. For sandy horizons buried by greenhouse ashes, the enrichment of Cd, Sr, As, Cr, and Ba is noted as being relative to soils from a local geochemical background. Therefore, this study demonstrates that household and greenhouse ashes need special attention because of their potential negative environmental effects. The incineration of household ashes (and greenhouse ashes) with municipal wastes, and metal(loid)s recovery from the resulting ashes is a promising management strategy for these types of combustion wastes instead of storing them around households.

The importance of organic matter in controlling the metal variability and mobility in seagrass sediments.

Metal contamination in seagrass beds has been extensively studied in the past decades. Most of earlier studies have focused on reporting metal concentration in different compartments of seagrass ecosystem, with little attention given to the role of sediment organic matter in controlling the metal mobility and bioavailability. This study investigated metal contamination in seagrass sediments in Hainan Island, China and illustrated how various geochemical factors impact the spatial variability of the metal concentrations. Particularly, we explored how organic matter influence metal storage and mobility in the seagrass sediments. The enrichment of metals in these sediments was not only associated with levels of organic matter but also their sources. The organic matter content showed positive correlations with both metal concentrations and acid-extractable fractions of chromium, silver, and cadmium, highlighting its significant role in influencing metal accumulation and mobility in sediments. Overall, this research enhances our understanding of metal cycling within seagrass ecosystems and highlights the vital role of seagrass-derived organic matter in regulating metal dynamics.

Ecological and health risk assessments of heavy metal contamination in soils surrounding a coal power plant

Coal combustion at power plants is a significant source of environmental pollution, with the deposition of heavy metals in soils leading to extensive ecosystem contamination and exacerbating the harmful impacts of human activities. This study presents a field investigation of heavy metal concentrations in soils around a coal-fired power plant, with monitoring sites located 1.7 to 15.2km from the plant. Data collection occurred in 2015, 2020, and 2024 across 11 monitoring sites. X-ray fluorescence analysis was used to assess heavy metal concentrations in soil. A life cycle assessment (LCA) with ReCiPe method was conducted to evaluate the impacts on both ecological and human health. The results revealed that the concentrations of Pb, Zn, Cu, Ni, Mn, Cd, and Cr exceeded threshold levels set by both the World Soil Average and the Regional Geochemical Background. The correlation analysis shows that organic matter and clay content play vital roles in reducing the mobility of heavy metals in soil through adsorption. Notably, strong correlations between Pb and Cd suggest a common origin from coal seam minerals. The LCA shows that freshwater ecotoxicity, marine ecotoxicity, terrestrial ecotoxicity, and human toxicity increased by over 30% compared to the World Soil Average pollutant levels. Nickel was identified as the primary contributor to marine and freshwater ecotoxicity, while manganese had the most significant impact on human toxicity. This study provides a better understanding of the long-term consequences of heavy metal accumulation in soils near coal-fired power plant. The data on anthropogenic impacts are crucial for developing effective strategies to mitigate environmental risks associated with pollution.

Harnessing the rhizosphere sponge to smooth pH fluctuations and stabilize contaminant retention in biofiltration system.

Fluctuating pH conditions can affect heavy metal mobility, thereby limiting the efficiency of biofiltration systems (BS). To address this, we developed an innovative rhizosphere sponge, biochar-based bioreactor (RBB), designed to stabilize Cd2+ removal across a pH range of 5 to 9. RBB consistently outperformed the control, achieving a notable 91.3 % Cd2+ removal at pH 5. By creating optimized oxygen and redox zoning, the rhizosphere sponge enhanced both biochar surface reactions and microbial activity. Under acidic conditions, biochar facilitated Fe2+/Mn2+ precipitation into stable (oxy)hydroxides, a process further driven by microbial oxidation. Consequently, RBB accumulated 1.54 times more Fe-Mn oxide-bound Cd than the control, effectively reducing Cd2+ mobility. Additionally, loosely bound extracellular polymeric substances claimed preferential Cd2+ sequestration after acidification. The stabilized microecology and increased ecological niches, allowing RBB to better buffer against pH fluctuations, presenting it as a robust solution for sustainable heavy metal remediation in variable environments.

The comparison of dissolved ionic forms of some metals (Fe, Cu, Cd, Pb, Zn) mobility in relation with intrinsic groundwater vulnerability in the industrial waste landfills, Croatia

The comparison of dissolved ionic forms of some metals (Fe, Cu, Cd, Pb, Zn) mobility in relation with intrinsic groundwater vulnerability in the industrial waste landfills, Croatia

Groundwater Contamination: Study on the Distribution and Mobility of Metals and Metalloids in Soil and Rocks

This study investigates the distribution and mobility of metals and metalloids (M&Ms) in soils, rocks, and groundwater within the geologically complex southwestern region of Sicily. The study aims to highlight how natural sources, like rocks and soils, can release elements potentially harmful to human health. It underlines their dual role as both natural reservoirs and active sources of M&M release, driven by leaching processes influenced by physicochemical factors such as pH and redox potential (Eh). Lithological characteristics significantly influence the retention and release of elements, with clay-rich formations exhibiting higher immobilization capacity. However, environmental parameter variations can enhance element mobilization, increasing bioavailability and the risk of groundwater contamination. Water quality analyses reveal regulatory exceedances for As, B, Ni, and Be, underscoring potential health and ecological risks. Concurrently, microbiological investigations identify diverse microbial communities capable of altering the oxidative states of specific elements through oxidation and reduction processes, further influencing their mobility. This study underscores the importance of understanding natural sources of M&Ms and their interactions with geochemical and microbiological processes for effective environmental risk assessment. The findings provide a foundation for developing integrated and sustainable water resource management strategies to mitigate contamination risks and safeguard ecosystems and public health.

Efficacy of bentonite/iron-coated sand as a sediment stabilizer in controlling cadmium, lead, zinc, and arsenic release determined using the diffusive gradients in thin film technology.

In this study, we investigated the efficiency of a bentonite/iron-coated sand (B/ICS) stabilizer in reducing the mobility and accumulation of heavy metals (Pb, Cd, Zn, and As) in contaminated sediments. Bentonite is effective in the adsorption of heavy metals, while ICS is effective in the adsorption of As. When combined, the stabilizer can be applied to mixed-contaminated sediments containing both heavy metals and As. The experimental setup involved B/ICS with sediments, followed by the analysis of heavy metal accumulation using diffusive gradients in thin-film resin gels for a period of 28days. The results obtained showed significant decreases in Pb, Cd, and Zn accumulation owing to the use of the stabilizer, particularly when its concentration was 15% of the sediment. Conversely, As accumulation did not show a decreasing trend owing to the low selectivity of the resin gel for As. Regardless, at the end of the 28-day test period, vertical distribution analysis indicated a notable decrease in heavy metal concentrations in the stabilizer layer of the contaminated sediment. These findings indicated that B/ICS is a cost-effective and efficient stabilizer for reducing heavy metal mobility in sediments. Long-term experiments are recommended to further validate these findings and optimize the use of the stabilizer in the field.

Tracing metal sources and groundwater flow paths in the Upper Animas River watershed using rare earth elements and stable isotopes

Groundwater flow paths and processes that govern metal mobility and transport are difficult to characterize in mountainous bedrock watersheds. Despite the difficulty in holistic characterization, conceptual understanding of subsurface hydrologic and geochemical processes is key to developing remediation plans for locations affected by acid mine drainage, such as the Upper Animas River watershed in southwestern Colorado, USA. Stable isotopes of water and rare earth elements were utilized to evaluate groundwater flow and metal sources within this complex catchment. Stable isotope samples collected from draining mine adits and springs display systematic spatial variation wherein sample sites at higher elevations have greater seasonal variability than sites at lower elevations. The Upper Cement Creek watershed, where multiple draining mines are present, displays the lowest seasonal variation in stable isotopic signatures, potentially indicating the presence of a large, well-mixed volume of groundwater storage or interbasin groundwater flow. Rare earth elements display statistically significant variation between different alteration styles in the catchment. Overprinting of regional propylitic alteration is evident based on enrichment of middle rare earth elements in acidic springs and mines that are not spatially associated with surficial exposures of acid generating alteration styles. Europium anomaly and middle rare earth enrichment signatures from two flooded mine tunnels on opposite sides of a watershed divide indicate connections to the same subsurface flooded mine workings.

Sustainable remediation of abandoned coal mines using vermicompost: a case study in Ledo coal mine, India.

Coal mining in India, especially open-cast mining, substantially strengthens the economy while concurrently causing environmental deterioration, such as soil pollution with toxic chemicals and heavy metals. This study sought to examine the efficacy of vermicompost as a remediation technique for Mine Tailing Soil (MTS) in the Ledo Coal Fields. During a 120-day duration, different concentrations of vermicompost (20%, 30%, and 40%) were administered to MTS, and the impacts on soil physicochemical parameters, fertility, and plant growth were evaluated. The findings indicated substantial enhancements in soil fertility, encompassing increased nutrient availability, improved water retention, and diminished bulk density. Plant species, including Abelmoschus esculentus, Solanum lycopersicum, and Delonix regia, showed substantial growth when subjected to 20% and 30% vermicompost amendments, with the 30% treatment producing the most remarkable outcomes. Furthermore, Risk Assessment Code values for soils amended with 20%, 30%, and 40% vermicompost were markedly diminished, reducing the bioavailability and mobility of heavy metals. The data indicate that vermicompost is an efficient and sustainable method for remediating MTS, alleviating heavy metal contamination, and enhancing plant development, thus addressing the environmental hazards of coal mining.

Metal mobilisation and fines migration in pure CO2 and impure CO2-SO2-NO reactions of carbon storage site core.

Carbon dioxide geological storage is proposed as part of the solution to reach net zero emissions. The potential to mobilise heavy metals to low salinity groundwater through CO2 water rock geochemical reactions is a potential environmental risk factor, if CO2 migrates. Previous studies have focused on pure CO2 reactivity, however CO2 streams from hard to abate industries can contain gas impurities. Reservoir sandstone and mudstone drill cores from a proposed low salinity CO2 storage demonstration site were reacted at in situ conditions with pure CO2 or an impure NO-SO2-CO2 stream. Sandstones hosted Rb in illite analysed via synchrotron XFM. Arsenic (As) was hosted in pyrite; and Pb, Cr, Mn in siderite rimming intergranular pores. Mudstone contained Zn, Co, Ni, Cu, As, Pb in sphalerite, and Rb in illite and K-feldspar. In impure NO-SO2-CO2 experiments the lowered pH and oxidising conditions initially released higher concentrations of metals including Pb, Zn, Co into solution compared to pure CO2 reactions. Higher concentrations of Zn (Mn and Co) were released from sphalerite in the mudstone. Fe-chlorite, K-feldspar, and carbonate dissolution released Rb, Si, Fe, Ca, and Mg. Elevated dissolved Pb was mainly from siderite and sulphide mineral reaction in sandstones. Mobilised As was released prior to CO2 addition from desorption and ion exchange. Clay and fines migration into pores occurred in both pure and impure CO2 reactions that has the potential to impact fluid migration. A portion of metals including Fe, Ni, Cr were subsequently incorporated in precipitated Fe hydr(oxy)oxides where the co-injected NO induced oxidising conditions. Rock mineral content and the injected gas mix were the main controls on metal mobilisation to formation water. Further work should investigate new gas mixtures that may be expected in storage hubs, from blue hydrogen or from direct air capture.

Experimental investigations of colloid-associated metal mobility in mine-impacted wetland sediment.

Metal mining operations can release toxic metals to surrounding environments where site-specific conditions control the movement of contaminants. Colloid-facilitated transport, the transport of contaminants with small, mobile particles, has been recognized as a potential contaminant transport vector in groundwater, but it remains unclear under what conditions it is important and whether neutral, metal-rich mine drainage from legacy mining impacts this transport vector. This work presents a set of laboratory column experiments that study the effect of colloids on metal mobility in saturated, wetland sediment that has been receiving neutral mine drainage for nearly a century, using mixed and single metal input solutions at neutral pH. Results indicate that colloid-facilitated transport is only important when small (<0.01μm) colloids, most likely formed from organic matter, are present. Larger particles were found to be generally immobile, so could aid in the immobilization of metal contaminants. These findings imply that colloid-facilitated transport is an important transport vector in mine-impacted wetland sediment and should be considered when remediating mine sites.

Mobilization of porewater Pb and Zn in response to seasonal wetting and drying within contaminated floodplains.

The mobility and bioavailability of metal contaminants such as lead (Pb) and zinc (Zn) is impacted by their interactions with other sediment constituents such as iron (Fe), sulfur (S), and organic matter, which depend on sediment redox conditions. Understanding the role that water level fluctuations have on redox conditions and subsequent impacts on metal mobility is critical for predicting impacts of increased wetting and drying cycles resulting from climate-related changes or management actions. This study measured the sediment-porewater partitioning of Pb and Zn in the Coeur d'Alene River basin downstream of the Bunker Hill Superfund Site under both flooded and seasonally dry conditions. The results show that both time of year and hydrology are important when considering metal exposure risks in contaminated floodplains. For Pb, seasonal spring flooding appears to mobilize dissolved Pb in both seasonally inundated and permanently inundated areas due to increases in sediment-derived Pb that undergo desorption processes from suspended Fe and DOC. For Zn, oxygenation of floodplain sediments in the fall drives elevated dissolved Zn year-round due to limited ZnS precipitation. Wetting-drying cycles had a significant impact on Zn mobility, which could be exacerbated by climate-driven hydrological changes or floodplain management actions.

Immobilization or mobilization of heavy metal(loid)s in lake sediment-water interface: Roles of coupled transformation between iron (oxyhydr)oxides and natural organic matter.

Iron (Fe) (oxyhydr)oxides and natural organic matter (NOM) are active substances ubiquitously found in sediments. Their coupled transformation plays a crucial role in the fate and release risk of heavy metal(loid)s (HMs) in lake sediments. Therefore, it is essential to systematically obtain relevant knowledge to elucidate their potential mechanism, and whether HMs provide immobilization or mobilization effect in this ternary system. In this review, we summarized (1) the bidirectional effect between Fe (oxyhydr)oxides and NOM, including preservation, decomposition, electron transfer, adsorption, reactive oxygen species production, and crystal transformation; (2) the potential roles of coupled transformation between Fe and NOM in the environmental behavior of HMs from kinetic and thermodynamic processes; (3) the primary factors affecting the remediation of sediments HMs; (4) the challenges and future development of sediment HM control based on the coupled effect between Fe and NOM from theoretical and practical perspectives. Overall, this review focused on the biogeochemical coupling cycle of Fe, NOM, and HMs, with the goal of providing guidance for HMs contamination and risk control in lake sediment.

Mechanisms activating trace heavy metals in the rhizosphere microenvironment of Amaranthus hypochondriacus L.

Soil heavy metal activation is closely related to rhizosphere soil pH, O2 and enzyme activity levels. In this study, we used laser ablation inductively coupled plasmamass spectrometry (ICPMS), planar optode (PO), soil in situ enzyme spectrum analysis, and the diffusive gradients in thin films (DGT) method to investigate heavy metal accumulation in Amaranthus hypochondriacus L. growing in polluted soil (Cd, Pb and Zn) and unpolluted soil, as well as dissolved oxygen (DO), pH, soil enzyme activity, and trace heavy metal dynamics in rhizosphere and nonrhizosphere soils. The results revealed that the growth of A. hypochondriacus was significantly inhibited under combined Cd, Pb, and Zn stress, with the most pronounced effects on root and branch biomass. Radial oxygen loss (ROL) and alkalization occurred in the roots of A. hypochondriacus, which were influenced primarily by root growth and environmental conditions. The enzyme activity patterns indicated that acid phosphatase (ACP), alkaline phosphatase (ALP), and β-glucosidase (BG) activities were primarily associated with the root system and that the activities of these enzymes were relatively low in nonrooted soil. Under heavy metal stress, the ACP, ALP and BG activities in the hotspots of soil increased. DO, pH, and soil enzyme activity were significantly correlated with the presence of heavy metals Cd, Pb, and Zn, influencing the mobilization mechanisms of trace metals in the rhizosphere. These findings lay the groundwork for understanding the impact of root-induced alterations in O2, pH, and soil enzyme activity on the mobility of trace heavy metals in soil.

Optimizing soil remediation with multi-functional L-PH hydrogel: Enhancing water retention and heavy metal stabilization in farmland soil.

Agricultural soils face severe challenges, including water scarcity and heavy metal contamination. Optimizing soil remediation efficiency while minimizing inputs is essential. This study assessed the water retention and heavy metal adsorption properties of L-PH hydrogel through aqueous experiments. Fourier Transform Infrared (FTIR) and X-ray Photoelectron Spectroscopy (XPS) elucidated the adsorption mechanisms. The results showed that L-PH hydrogel exhibited high water absorption efficiency, with Zn2+ removed via electrostatic interactions and cation exchange, and Cd2+ and Cu2+ adsorbed through coordination complexation. Soil experiments tested water retention and heavy metal leaching under various application methods (M1=0-10cm mixed, M2=10-20cm mixed, T1=5-10cm layered, T2=10-15cm layered) and rates (NL=0%, L1=0.1%, L2=0.2%, L3=0.5%). L-PH reduced water infiltration, enhanced soil water retention, and decreased heavy metal mobility across all treatments. The highest water retention was observed in the M1 method. Under M1L1, cumulative leaching of Cd2+, Cu2+, and Zn2+ decreased by 68.84%, 33.44%, and 83.60%, respectively. Two-way ANOVA revealed that application rate had a greater effect on leaching than the method. FTIR and XRD analyses showed that at low concentrations (L1, L2), L-PH formed coordination bonds with Cd2+ and Cu2+, creating Cd(HCOO)2·2(NH2)2CO and Cu(HCOO)(OH) in the soil. Zn2+ was stabilized through adsorption and precipitation, forming Zn(OH)2, thereby reducing leaching. Higher concentrations of L-PH may have further interacted with Zn, leading to dissolution and adsorption/precipitation processes. Redundancy analysis (RDA) analysis suggests that an increase in organic carbon and moisture content in soil aggregates larger than 2mm, along with a decrease in bioavailable heavy metals, may enhance heavy metal stabilization, reducing their movement and leaching. This study offers valuable insights into addressing the twin challenges of water scarcity and heavy metal pollution.

Dynamic responses and adsorption mechanisms of Chlamydomonas reinhardtii extracellular polymeric substances under Cd, Cu, Pb, and Zn exposure.

Extracellular polymeric substances (EPS) can effectively attenuate heavy metal mobility in aquatic ecosystems and reduce metal toxicity to cells. However, a systematic study of microalgae EPS responses and their adsorption behaviors, characteristics, and mechanisms under different heavy metal exposures has not been performed. In this study, EPS extracted from Chlamydomonas reinhardtii CC-125 was analyzed for compositional changes (monosaccharides and proteins) under Cd, Cu, Pb, and Zn treatments. The EPS adsorption capacities and mechanisms for the four metal ions were also investigated. Cd (10 mg/L), Cu (5 mg/L), and Zn (5 mg/L) exposure induced changes in the microalgal EPS composition and structure, and a protein/polysaccharide ratio of greater than 1 was found. This result indicated the crucial role of proteins in stress resistance. In contrast, Pb stress resulted in an increase of 532.64% and 117.48% in proteins and polysaccharides, respectively, with galactose and glucose playing key roles in this process. A fluorescence analysis revealed that Cd/Pb exposure reduced the tryptophan and tyrosine levels in the EPS, while Cu/Zn only weakened tryptophan. As a biosorbent, the adsorption capacity of the EPS for the four metals followed the order of Pb > Cd > Cu > Zn. The fluorescence quenching titration results revealed that fluorescent compounds in the EPS had the strongest complexation ability with Pb (logKSV: 8.16 × 103), followed by Cu (logKSV: 1.79 × 103), while their abilities for Cd and Zn were weaker. A spectroscopic analysis indicated that the primary functional groups involved in EPS binding with Pb/Cd and Cd/Zn were protein carboxyl groups (C=O/O-C=O) and glycosidic bonds (C-OH/C-O-C), respectively. This study elucidates the response strategies and adsorption mechanisms of the C. reinhardtii EPS to different metals and provides a basis for environmental heavy metal pollution bioremediation.

Exploring the impact of fulvic acid and humic acid on heavy metal availability to alfalfa in molybdenum contaminated soil

Humic substances, such as Fulvic acid (FA) and humic acid (HA), are widely used for the remediation of heavy metal-contaminated soils due to their ability to enhance metal mobility and facilitate plant uptake. In this study, we conducted a pot experiment with alfalfa to investigate the effects of FA and HA amendments on the mobility of molybdenum (Mo) in the soil, its uptake by alfalfa plants, and subsequent changes in the microbial community. The results demonstrated that both FA and HA influence Mo accumulation in the soil and plants. Specifically, HA treatment increased Mo concentrations in alfalfa shoots and roots by 1.08–1.19 times and 1.19–2.43 times, respectively, compared to the control. In contrast, FA enhanced Mo concentrations in alfalfa roots (1.05–1.58 times) but reduced Mo levels in the shoots (0.78–0.85 times). Furthermore, the addition of FA and HA altered the chemical speciation of Mo in the soil, promoting the conversion of reducible and oxidizable fraction to more exchangeable and residual fraction. As a result, the proportion of non-residual Mo fractions (exchangeable, reducible, and oxidizable) decreased from 87.48% to 80.30-87.35%, while residual fractions increased from 12.52% to 12.65–19.70%. Additionally, the structure of the soil bacterial community was primarily influenced by changes in soil properties such as cation exchange capacity, available phosphorus, and ammonium nitrogen levels. This finding highlight the potential of FA and HA to enhance Mo availability, uptake, and translocation in alfalfa, suggesting that their application could be an effective strategy for phytoremediation of Mo-contaminated soils, particularly when alfalfa is used as a hyperaccumulator.

Impact of offshore energy activities on trace elements content and mobility in marine sediments.

The offshore oilfields in the North Sea area are increasingly employed for projects beyond oil production, like carbon capture and storage (CCS). Still, the fossil fuel production from mature fields is significant. It has raised environmental concerns associated with discharging produced waters (PW) and drilling mud into the sea. These discharges, which may be highly saline and contain production chemicals, vary significantly in metals and particulate content. Due to density and release depth, the plume is assumed to sink towards the seafloor. Also, a single oilfield can input up to 7.5 tons of Ba, 675kg of Fe, and 619kg of P into the water column through PW. Therefore, this study investigates the impact of these discharges on seafloor sediments around two Danish oilfields, assesses the mobility of metals within these sediments, and evaluates the environmental status. PW samples were collected at the discharge outlets from the platforms. Sediment cores were taken near the two oil platforms and from control sites. Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and an optimized BCR sequential extraction, we analyzed the composition and distribution of 24 elements in sediment samples. The results revealed significant differences in total extracted concentrations between sediments near the platforms and those from distant locations and stratigraphically older samples, with relevant levels of Br, Ba, and Sn near the platforms (averaged 14, 27, and 0.1ppb, respectively). Sediment quality indices showed considerable enrichment and geo-accumulation of toxic metals, particularly at one of the platform sites. However, cumulative indices did not display significant pollution anomalies. Therefore, our findings suggest that oil extraction activities may increase the availability of toxic metals in nearby sediments, potentially impacting marine ecosystems.

Mycoremediation of heavy metals by Curvularia lunata from Buckingham Canal, Neelankarai, Chennai.

The spread and mobilization of toxic heavy metals in the environment have increased to a harmful level in recent years as a result of the fast industrialization occurring all over the world to meet the demands of a rising population. This research aims to analyze and evaluate the mycoremediation abilities of fungal strains that exhibit tolerance to heavy metals, gathered from water samples at Buckingham Canal, Neelankarai, Chennai. Water samples were examined for heavy metal analysis, and the highest toxic heavy metals, Zn, Pb, Mn, Cu, and Cr, were recorded. Three fungal strains were isolated and named EBPL1000, EBPL1001, and EBPL1002 were selected by primary screening (100ppm) for further studies. Out of three fungal isolates, EBPL1000 grew in all five heavy metal concentrations and showed 2100ppm as the highest Maximum Tolerance Concentration toward Lead, 2000ppm tolerance in Zinc and Manganese, 1700ppm in Chromium, and 1500ppm in copper, respectively. The fungal isolate EBPL1000 was identified as Curvularia lunata with 100% percentage identity and query coverage. The Biosorption result reveals that lead is the highest biosorbed heavy metal with 79.99% at 100ppm concentration while copper is the lowest biosorbed with 24.11% heavy metal at 500ppm concentration. The uptake of Manganese by Curvularia lunata biomass was the highest (5.64mg/g) of all heavy metal's uptake at 100ppm concentration. The lowest uptake of heavy metals was copper (0.43mg/g) at 500ppm concentration, and the growth profile study under heavy metals stress conditions shows the order of Pb > Mn > Zn > Cr > Cu at 60h of time intervals at 100ppm concentration. In addition to the research, FTIR analysis and Molecular Docking studies provide credence to the idea that Curvularia lunata has high biosorption potential and uptake or removal of toxic heavy metals at low cost and in an eco-friendly way from the contaminated environment.

The Use of Diatomite-Based Composites for the Immobilization of Toxic Heavy Metals in Industrial Wastes Using Post-Flotation Sediment as an Example.

Composite materials based on diatomite (DT) with the addition of biochar (BC), dolomite (DL), and bentonite (BN) were developed. The effect of chemical modification on the chemical structure of the resulting composites was investigated, and their influence on heavy metal immobilization and the ecotoxicity of post-flotation sediments was evaluated. It was demonstrated that the chemical modifications resulted in notable alterations to the chemical properties of the composites compared to pure DT and mixtures of DT with BC, DL, and BN. An increase in negative charge was observed in all variants. The addition of BC introduced valuable chemically and thermally resistant organic components into the composite. Among the chemical modifications, composites with the addition of perlite exhibited the lowest values of negative surface charge, which was attributed to the dissolution and transformation of silicon compounds and traces of kaolinite during their initial etching with sodium hydroxide. The materials exhibited varying efficiencies in metal immobilization, which is determined by both the type of DT additive and the type of chemical modification applied. The greatest efficacy in reducing the mobility of heavy metals was observed in the PFS with the addition of DT and BC without modification and with the addition of DT and BC after the modification of H2SO4 and H2O2: Cd 8% and 6%; Cr 71% and 69%; Cu 12% and 14%; Ni 10% and Zn 15%; and 4% and 5%. In addition, for Zn and Pb, good efficacy in reducing the content of mobile forms of these elements was observed for DT and DL without appropriate modification: 4% and 20%. The highest reduction in ecotoxicity was observed in the PFS with the addition of DT and BC, followed by BN and DL, which demonstrated comparable efficacy to materials with DT and BN.