Speciation-Driven Toxicity and Remediation of Mercury: Mechanistic Insights and Policy Implications

Speciation-Driven Toxicity and Remediation of Mercury: Mechanistic Insights and Policy Implications | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 29 October 2025 V1 Latest version Share on Speciation-Driven Toxicity and Remediation of Mercury: Mechanistic Insights and Policy Implications Authors : Naila Shah , Muhammad Awais , Mohammad Ali , and Haiyan Li [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.176177172.23880272/v1 Published Journal of Hazardous Materials Advances Version of record Peer review timeline 456 views 178 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Mercury is a worldwide spread pollutant whose effects are more related to chemical speciation rather than concentration. Changes between elemental mercury (Hg 0 ), inorganic mercury (Hg 2+ ) and organomercury species, including methylmercury (CH 3 Hg + ), Dimethyl mercury (CH 3 ) 2 Hg + ) and ethylmercury (EtHg), determine the mobility, bioavailability, and toxicity of mercury in soil, water, sludge, and air. These dynamic changes are caused by factors such as pH, redox potential, organic matter and microbial activity. Elemental mercury (Hg 0 ) causes inhalation toxicity, considered relatively less toxic but can be oxidized to inorganic mercury (Hg 2+ ), which has higher affinity for sulfhydryl groups in protein and enzymes, leading to cellular dysfunction and kidney damage. The most hazardous form is organic mercury, particularly methylmercury which easily crosses biological membranes, including the blood brain and placental barrier. Once inside the body, methyl mercury bind to thiol containing molecules contains molecules, cause sever disproportionate neurodevelopmental damage by food webs. Dimethyl mercury is even more toxic, penetrate skin and tissue rapidly, resulting in acute poisoning at extremely low exposure level. Mercury speciation has a significant impact on plant uptake, cross-species toxicity and remediation. The risks can be alleviated by phytoremediation, microbial transformation, sludge treatment, and thermal or chemical stabilization, and mitigated or inadvertently increased by specification-conscientious planning. Detection is improved by the development of analytical methods, such as HPLC-ICP-MS, CVAFS, X-ray absorption spectroscopy, and biosensors, but in situ and real time monitoring is still problematic. Speciation metrics should replace bulk mercury levels, which should be incorporated in policy systems, including the Minamata Convention. In the future, the integration of mechanistic models and field data, the creation of AI-based speciation prediction, and the implementation of low-cost biosensors are important, especially in poorly-infrastructure-equipped regions. Sustainable mercury management should be based not only on reduction of the total amount but also on conversion of mercury into less toxic and mobile states. Speciation-Driven Toxicity and Remediation of Mercury: Mechanistic Insights and Policy Implications Naila Shah 1, 2, Muhammad Awais 3, Mohammad Ali 4, Haiyan Li 1, * 1. Medical Faculty, Kunming University of Science and Technology, Kunming, 650500, China 2. Govt. Girls, Degree, College LundKhwar, Mardan, 23200, Higher Education KP, Pakistan 3. School of Life Sciences, Yunnan University, Kunming 650500, China 4. Center for Biotechnology and Microbiology, University of Swat, KP, Pakistan * For Correspondence: Haiyan Li; E-mail: [email protected] ; Graphical Abstract Highlights • Mercury exists in multiple chemical forms, or species, each of which behaves differently in the environment. These forms control how mercury is transported, transformed, and deposited across air, soil, and water systems. • The toxicity of mercury to plants, animals, and humans is strongly dependent on its speciation, with some forms being far more harmful than others. • Methylmercury is the most toxic form of mercury due to its high affinity for biological tissues. It bioaccumulates in the food chain, posing significant neurotoxic risks to humans and wildlife. • Targeting specific mercury species improves the effectiveness of phytoremediation and microbial treatments. Speciation-aware strategies boost mercury removal from contaminated soils and waters. • Advanced analytical techniques allow precise identification of different mercury species. This enables accurate tracking of mercury transformations and environmental behavior. • Policy frameworks should move beyond measuring total mercury alone. Regulations need to account for mercury speciation to better protect human health and the environment. Abstract Mercury is a worldwide spread pollutant whose effects are more related to chemical speciation rather than concentration. Changes between elemental mercury (Hg 0 ), inorganic mercury ( Hg²⁺ ) and organomercury species, including methylmercury (CH 3 Hg + ), Dimethyl mercury (CH 3 ) 2 Hg + ) and ethylmercury (EtHg), determine the mobility, bioavailability, and toxicity of mercury in soil, water, sludge, and air. These dynamic changes are caused by factors such as pH, redox potential, organic matter and microbial activity. Elemental mercury (Hg 0 ) causes inhalation toxicity, considered relatively less toxic but can be oxidized to inorganic mercury ( Hg²⁺), which has higher affinity for sulfhydryl groups in protein and enzymes, leading to cellular dysfunction and kidney damage. The most hazardous form is organic mercury, particularly methylmercury which easily crosses biological membranes, including the blood brain and placental barrier. Once inside the body, methyl mercury bind to thiol containing molecules contains molecules, cause sever disproportionate neurodevelopmental damage by food webs . Dimethyl mercury is even more toxic, penetrate skin and tissue rapidly, resulting in acute poisoning at extremely low exposure level. Mercury speciation has a significant impact on plant uptake, cross-species toxicity and remediation. The risks can be alleviated by phytoremediation, microbial transformation, sludge treatment, and thermal or chemical stabilization, and mitigated or inadvertently increased by specification-conscientious planning. Detection is improved by the development of analytical methods, such as HPLC-ICP-MS, CVAFS, X-ray absorption spectroscopy, and biosensors, but in situ and real time monitoring is still problematic. Speciation metrics should replace bulk mercury levels, which should be incorporated in policy systems, including the Minamata Convention. In the future, the integration of mechanistic models and field data, the creation of AI-based speciation prediction, and the implementation of low-cost biosensors are important, especially in poorly-infrastructure-equipped regions. Sustainable mercury management should be based not only on reduction of the total amount but also on conversion of mercury into less toxic and mobile states. Keywords Mercury speciation; Methylmercury; Toxicodynamic; Phytoremediation; Risk assessment; Minamata Convention revision. 1. Introduction Mercury is a worldwide dispersed contaminant which is very dangerous to the environment and human health due to its persistence, mobility and high toxicity (1-3). It is emitted into the atmosphere both naturally by volcanic emissions, geothermal emission and rock weathering bearing mercury and anthropogenically due to combustion of coal, artisanal and small gold mining, waste incineration, and various industrial processes (4, 5). Elemental mercury is very persistent in gaseous phase and can remain in the air for up to a year, transported over a long distance in the atmosphere after release, which contaminates even distant areas like the Arctic and high-altitude ecosystems, far from original sources (6-8). This widespread distribution leads to global contamination of air, water, and soil. Its environmental action is controlled by complicated biogeochemical cycles where it changes between elemental, inorganic and organic forms under the influence of various physiochemical and microbial processes (9, 10). This transformation of mercury’s is critical because they regulate mercury solubility, partitioning, and interaction with biological systems. Ultimately determining its mobility, persistence, and potential to bioaccumulate. The toxicity of mercury is closely linked to its chemical speciation: while elementary mercury has limited bioavailability, inorganic forms readily bind to thiol group in protein, and methylmercury is highly bio accumulative and neurotoxic, posing serious threats to aquatic food webs and human health through dietary (11, 12). Consequently, the speciation of mercury is key in determining its ecological effects, predicting health hazards to humans, and designing effective monitoring and remediation strategies to mitigate mercury pollution at both local and global scales The review summarizes the recent research on the mercury speciation and its associated environmental and biological implication. The review also examines plant uptake mechanism, emerging and conventional remediation measures, analytical methods, and policy frameworks and promotes a more speciation-focused approach to address the challenges posed by this persistent global contaminant. 2. Environmental Speciation and Fate Inorganic mercury ( Hg²⁺ ) is bound to organic matter and clay particles of soils and sediments and methylmercury (MeHg) is very bioavailable and biomagnifies via aquatic food webs [2]. An anaerobic process of microbial methylation of Hg²⁺ in sediments contributes to the production of MeHg, whereas photochemical and volatilization reduce the levels of MeHg in open water bodies (12, 16). Events of mercury depletion in arctic regions are caused by oxidation of Hg 0 using halogen and hence lead to localized deposition [8]. Modulation of mercury speciation and mobility Dissolved Organic matter (DOM) in wetlands and estuaries. Permafrost thawing caused by climatic changes can liberate the pool of heritage mercury, change species and produce more MeHg (10) The only difference between mercury and other heavy metals is that it is found in numerous chemical forms each having its own physicochemical characteristics, environmental patterns and toxicological consequences (17). This is because it is necessary to comprehend these forms to determine the dangers of mercury pollution (14). 2.1 Elemental Mercury (Hg⁰) Elemental mercury (Hg⁰) is the primary form of mercury found in the atmosphere and plays an essential role in the global mercury cycle. It is characterized by its volatility, persistence, and relative inertness under normal conditions, which facilitates its widespread distribution and ongoing re-emission among the air, land, and water (18) (9, 19). Due to its extended atmospheric lifespan and its reactivity in oxidation-reduction processes, Hg⁰ acts as a mobile carrier that connects various environmental compartments (20, 21). Hg⁰ is a liquid metal characterized by a high vapor pressure of approximately 0.00185 mm Hg at 25 °C and a very low solubility in water, around 60 µg L⁻¹. This property facilitates its rapid volatilization and extensive transport in gaseous form (18, 22). Its relatively slow reaction rate with atmospheric oxidants, including O₃, OH•, and halogen radicals such as Br• and Cl•, results in a global atmospheric residence time ranging from 0.5 to 2 years (23). in the atmosphere the natural emission discharged from geothermal escapes, volcanoes, oceanic evasion and soil venting, while anthropogenic contribution arise from coal combustion, waste incineration, metal smelting and gold mining (24, 25). This gaseous elemental mercury oxidized to divalent mercury after long range transport across continents. The oxidized species of mercury is water soluble and removed by dry/wet deposition (26). Atmospheric mercury converted back to elemental mercury by photochemical and heterogenous reaction, maintaining a dynamic redox equilibrium that regulate global deposition (9, 27). Elemental mercury interact s with soils through weak deposition on organic matter and clay after deposition temperature, pH and soil organic carbon effects the exchange process (20, 28). Warm and arid condition influence volatilization and re emission back to Hg 0 abiotic oxidation via MNO 2 and FeO 2 or humic substances may reconvert Hg 0 to Hg 2+ linking atmospheric and terrestrial pool (18). Water and air exchange is major flux controlling Hg 0 concentration in surface water. Dissolved Hg 0 undergoes oxidation to Hg 2+ through a reaction with photochemically reduced radicals or O3 while microbial activity and photoreduction regenerate Hg 0 (22, 29, 30). The volatilization from oceans and lakes returns substantial mercury to the atmosphere, making a feedback disc central to the global cycle (19). Elemental mercury dominant the atmosphere reservoir, linking aquatic and terrestrial sink in a continuous exchange (9, 27). Modeling suggests (24, 30) suggest more than 5000-6000 tons of Hg0 circulate annually in the troposphere. Dynamic like oxidation – reduction, deposition and reemission, climate variables such as temperature and radiation intensity sustain a global equilibrium (19, 20). 2.2 Inorganic Mercury (Hg²⁺) Inorganic mercury (Hg²⁺) refers to ionic and compound forms of mercury, primarily existing as HgCl₂, HgS, and Hg (OH)₂ in the environment. It is produced through the oxidation of elemental mercury (Hg⁰) or released directly from industrial discharges, chlor-alkali plants, coal combustion, and mining activities (22, 30, 31) Although less volatile than elemental mercury, inorganic mercury is highly reactive, persistent, and capable of undergoing redox cycling and transformation into organic mercury species such as methylmercury (MeHg) — the most toxic and bioaccumulative form (9, 30). In the atmosphere, inorganic mercury mainly exists as gaseous oxidized mercury (GOM, Hg²⁺) and particle-bound mercury (PBM). These are formed through oxidation of Hg⁰ by ozone (O₃), hydroxyl radicals (OH•), and halogen radicals (Br•, Cl•, I•) (19, 23). GOM and PBM have short atmospheric lifetimes (hours to days) compared with Hg⁰ (months to a year)(24) . They are efficiently removed through wet deposition (rain, snow) and dry deposition (30). This deposition represents the primary pathway for mercury transfer from the atmosphere to terrestrial and aquatic systems (18) . Once deposited, inorganic mercury enters surface waters where its speciation is governed by pH, redox conditions, chloride and sulfide concentrations, organic matter, and microbial activity (9, 20, 22). Hg²⁺ readily forms complexes with: Chloride (HgCl₂, HgCl₃⁻, HgCl₄²⁻) in marine and estuarine waters, enhancing solubility (27); Sulfides (HgS, Hg(SH)₂, Hg(SH)₃⁻) in anoxic sediments, reducing bioavailability due to formation of insoluble cinnabar (HgS) ; Dissolved organic matter (DOM) and humic substances, which can both stabilize soluble forms and act as carriers to deeper waters (20) . Under anoxic conditions, mercury is rapidly converted to HgS(s) (cinnabar or metacinnabar), a relatively stable mineral form (29). However, reoxidation during sediment resuspension or oxygenation can remobilize Hg²⁺ (25). In sediments and low-oxygen water columns, sulfate- and iron-reducing bacteria convert inorganic Hg²⁺ into methylmercury (MeHg) — the most toxic and bioaccumulative mercury species (22). Conversely, photochemical and microbial demethylation can return MeHg to inorganic forms, contributing to dynamic equilibrium (18, 31). In soils, inorganic mercury binds strongly to organic matter, sulfides, and clay minerals, resulting in limited mobility (9, 20). Mercury bioavailability in soils depends heavily on redox potential and organic carbon content—low oxygen and high organic matter promote methylation, while oxidized and mineral soils favor sequestration as HgS (20, 32). Inorganic mercury itself has limited bioaccumulation potential compared to methylmercury, but it serves as the precursor for microbial methylation. Aquatic microorganisms and periphyton uptake Hg²⁺ through passive diffusion or binding to cell walls (31). This inorganic mercury may then be bio transformed into methylmercury within biofilms and sediments, entering the aquatic food chain Thus, even though inorganic mercury is less mobile biologically, it indirectly drives long-term ecological and health risks through methylation (9, 32). A substantial fraction of deposited Hg²⁺ is not permanently buried. Through photoreduction and microbial reduction, inorganic mercury can revert to Hg⁰, returning to the atmosphere This recycling process sustains the global mercury pool and prolongs its environmental residence time (up to thousands of years) (9, 31, 33). Inorganic mercury acts as a transitional species within the global mercury cycle, the link between stable elemental mercury and bioavailable methylmercury. Its environmental fate is therefore critical for: Predicting mercury hotspots (23, 30); Designing remediation strategies (e.g., sediment capping, biochar stabilization, phytoremediation) (22, 34); Assessing compliance with the Minamata Convention(35). Persistent cycling among Hg⁰ ↔ Hg²⁺ ↔ MeHg emphasizes the need for speciation-focused monitoring rather than total mercury quantification alone (9, 35). 2.3 Methylmercury (MeHg) Methylmercury (MeHg) is the most toxic, bioavailable, and bioaccumulative form of mercury in the environment. It is a monomethylated organometallic compound (CH₃Hg⁺) primarily formed through the microbial methylation of inorganic Hg²⁺ in aquatic and terrestrial systems (9, 27). Due to its lipophilic nature and ability to cross biological membranes, MeHg easily accumulates in organisms and biomagnifies through food webs, reaching dangerous concentrations in predatory fish and humans (23, 27). The dominant process of MeHg formation is biological methylation mediated by anaerobic microorganisms, particularly sulfate-reducing, iron-reducing, and methanogenic bacteria containing the hgcA and hgcB gene cluster (36, 37). These microbes convert inorganic Hg²⁺ to MeHg using methyl donors such as methylcobalamin under anoxic and suboxic conditions (32, 38). Methylation rates depend on mercury bioavailability, temperature, redox potential, and dissolved organic matter (39, 40). Although less significant, MeHg can also be produced abiotically through photochemical and chemical methylation reactions involving humic substances or methyl iodide precursors (12). Such processes occur mainly in surface waters and wetlands (41)(13). Aquatic environments are the primary sites for MeHg production and accumulation (42). In lakes, estuaries, and oceans, MeHg forms predominantly in sediment–water interfaces and oxygen-depleted zones, where sulfate-reducing bacteria thrive (30, 37). Once produced, MeHg is partially bound to dissolved organic carbon (DOC) and colloids, enhancing its transport in water columns (16). MeHg exhibits a high affinity for plankton and detritus, facilitating its transfer into aquatic food webs (27, 38). In soils, wetlands, and rice paddies, microbial methylation of Hg²⁺ can generate significant MeHg levels(43) . Flooded, organic-rich soils favor this transformation due to low redox potential and abundant microbial activity (44). MeHg can subsequently be volatilized, adsorbed onto particulates, or leached into groundwater, contributing to secondary contamination (45). While MeHg is less volatile than Hg⁰, trace quantities can enter the atmosphere via sea spray aerosols and biogenic emissions (46). Atmospheric MeHg is mainly associated with fine particles, which can undergo long-range transport before deposition (47). MeHg is degraded via biotic and abiotic demethylation. Microbial demethylation by mercury-resistant bacteria possessing the mer operon (merB, merA) converts MeHg to Hg²⁺ or Hg⁰ (42) . Photo demethylation, driven by solar UV radiation and reactive oxygen species, converts MeHg into inorganic or elemental mercury (27). The balance between methylation and demethylation determines net MeHg accumulation (48). Environmental shifts such as eutrophication, warming, pH change can alter this balance, influencing MeHg production hotspots (44). MeHg strongly binds to thiol groups in proteins, allowing efficient uptake across cell membranes. It exhibits biomagnification factors up to 10⁶ from water to apex predators. The typical pattern is Water → Phytoplankton → Zooplankton → Fish → all Mammals (22, 48, 49). High MeHg levels in predatory fish such as tuna and swordfish are the main pathway for human exposure (50). Methylmercury has a long environmental residence time, as part of a global Hg⁰ ↔ Hg²⁺ ↔ MeHg cycle (9, 31, 42). MeHg deposited in sediments can be buried, reoxidized, or remobilized by bioturbation and climate-induced changes in redox conditions. Because MeHg is both persistent and mobile, it contributes significantly to global mercury bioavailability, particularly in aquatic food webs (9, 51). Due to its toxicity and persistence, MeHg is a key concern under the Minamata Convention on Mercury, which mandates control of mercury releases and encourages monitoring of methylmercury in fish and sediments. Developing countries face challenges due to industrial emissions, artisanal gold mining, and agricultural runoff, all of which enhance MeHg formation in aquatic systems. Future management must emphasize speciation-based monitoring and microbial gene-based indicators (hgcAB) to predict methylation potential (18, 25, 51-54). 2.4 Ethylmercury (EtHg) The other species of mercury that is an organic mercury is ethylmercury, which is structurally similar to methylmercury but that has different environmental and biological habitat (55, 56) Applications of EtHg in pharmaceuticals have included thimerosal (containing EtHg), a vaccine and medical product preservative. EtHg is excreted faster than MeHg in biological systems and therefore minimizes the chance of accumulation and resultant chronic toxicity with time. Although acute exposures may be toxic, its risk is significantly low as compared to MeHg (57, 58) Elemental Mercury (Hg⁰) Liquid metal at room temperature; volatile; long atmospheric lifetime High mobility in air; can undergo oxidation to Hg²⁺; persists globally Inhalation of vapor Neurotoxic; crosses blood–brain barrier; tremors, cognitive & motor impairment (59-61) Inorganic Mercury (Hg²⁺) Forms soluble salts and complexes with Cl⁻, OH⁻, and S²⁻; binds to soils & sediments Moderate mobility; precursor for microbial methylation Ingestion of salts; occupational exposure Corrosive; nephrotoxic; limited bioaccumulation compared to MeHg (14, 62, 63) Methyl- Mercury (MeHg) Produced by microbial methylation of Hg²⁺ in aquatic systems Highly persistent in food webs; bioaccumulates & biomagnifies Dietary intake (fish, shellfish, marine mammals) Potent neurotoxin; crosses placenta & blood–brain barrier; developmental & cognitive effects (14, 64-66) Ethyl Mercury (EtHg) Synthetic organomercury compound (e.g., i thimerosal; less stable in environment Rapidly metabolized & excreted; does not biomagnify Medical exposure (vaccines, pharmaceuticals) Lower risk of accumulation; acute toxicity possible but less hazardous than MeHg[25] (57, 58) Table 1. Key characteristics of major mercury forms 3. Toxicodynamic and Mechanism The cross of the blood brain barrier by methylmercury (MeHg) occurs through the amino acid transporters and posts in the neuronal tissues and interferes with neurodevelopment. It causes oxidative stress through depletion of glutathione, augmentation of reactive oxygen species (ROS) and mitochondrial dysfunction (67, 68). Inorganic mercury (Hg²⁺) gets deposited in kidneys, attaching to thiol-rich proteins and interfering with the functioning of the tubules. Me₂Hg is highly volatile, and lipophilic and can build up through protective mechanisms that result in fatal neurotoxicity (69). Mercury species change calcium homeostasis, block antioxidant enzyme, and cause apoptosis. The changes in DNA methylation and histone modifications are also the epigenetic effects which may influence the gene expression (69, 70). The species-specific toxicity limits are different: MeHg LOAEL in humans is approximately 0.3 0g/kg/day; Hg²⁺ + NOAEL in rodents is approximately 0.2 mg/kg/day (71-73). 3.1 Mechanisms of Cellular Uptake, Oxidative Stress, and Biomolecular Interactions The mechanistic effects of toxicodynamic of mercury are mediated by the entry of the species into the cell, the disruption of redox homeostasis, and the binding of the biomolecules that are necessary in cell functioning (32, 74, 75). The exact mechanisms involved in the reaction of Hg⁰ , Hg²⁺ and MeHg are varied, but one common theme is that mercury exhibits high affinity for groups containing thiol (-SH) and selenol (-SeH) and this explains its reactivity as well as its toxicity. Cellular Uptake Mechanisms. • Elemental Mercury ( Hg⁰ ): Hg⁰ diffuses passively across the lipid membranes, such as the blood -by barrier and the placental barrier, because of its lipophilicity. After getting in, it is quickly oxidized to Hg²⁺(76-78). • Inorganic Mercury ( Hg²⁺ ): It causes the charged ions of Hg²⁺ to not have the capacity to diffuse through the membranes (79). Absorption takes place mainly by ion transporters and endocytosis and commonly through complexation with chloride or organic ligands (80). It is also accumulated in renal proximal tubule cells in particular (81, 82). • Methylmercury (MeHg): MeHg is a volatile methionine mimic which forms complexes with cysteine. They are carried into neurons and placental tissue through neutral amino acid carriers (ex: LAT1), which allow an easy passage into the cell. This imitation describes the strong neurodevelopmental toxicity of MeHg (83-85). Oxidative Stress. All mercury species cause oxidative stress while through different mechanisms: • Mercury binding to thiol and selenol groups removes intracellular antioxidants, in particular, glutathione (GSH) (86). • Blockage of selenoenzymes like the glutathione peroxidase and thioredoxin reductase limiting detoxification of reactive oxygen species (ROS) (87). • Mitochondrial dysfunction induced by Hg2+ and MeHg interferes with electron transport, enhancing the leakage of ROS (88). • Its overall effect is oxidative stress on lipids, proteins and DNA, which causes neuronal death, renal tubular damage and systemic toxicity (89). Biomolecular-Interactions. Mercury species react with large number of biomolecules: • Proteins: Covalent interaction with cysteine amino acids changes protein folding, enzyme activity and integrity (90). • Nucleic Acids: Mercury does not directly interact with DNA: Strand breaks and oxidative stress as well as indirect action on nucleoproteins may occur (91). • Cellular Membranes: Bidirectional Cellular Membranes: ROS-induced lipid peroxidation disrupts membrane functions, which changes the ionic transport and cellular communication (92). • Signaling Pathways: Mercury disrupts the calcium homeostasis, release of neurotransmitters and kinase/phosphatase signaling which enhances cytotoxicity (93). • Phenotypes of organ-selective toxicity Speciation-dependent uptake pathways converge on common pathways of oxidative stress and biomolecular damage (94). Figure 1. Mechanistic pathways of mercury toxicodynamic: cellular uptake, oxidative stress, and biomolecular interactions. 3.2 Comparative Toxicity of Mercury Species The toxicological profile of mercury strongly depends on the speciation (95). The elemental mercury vapour, inorganic mercury salts, and methyl mercury also vary in their intake paths, organ of attack, and pathological predominant results (96). The toxicity of mercury varies substantially among its chemical forms, largely governed by differences in speciation, solubility, lipid affinity, and metabolic stability. Generally, mercury toxicity follows the order: dimethylmercury > methylmercury > ethylmercury > inorganic mercury > elemental mercury (97, 98). Dimethylmercury ((CH₃)₂Hg) is the most lethal form, displaying extreme lipid solubility and rapid cellular penetration. It can easily cross biological membranes, including the blood–brain barrier and placenta, and causes irreversible neurodegeneration even at trace exposure levels. Its delayed toxic effects, due to slow demethylation to methylmercury, make it exceptionally dangerous, with mortality often occurring weeks after exposure (99). Elemental mercury (Hg⁰) is relatively inert in the gastrointestinal tract but highly toxic upon inhalation. Approximately 80% of inhaled mercury vapor is absorbed into the bloodstream, where it diffuses into tissues, including the brain. Once oxidized to Hg²⁺, it causes oxidative stress, mitochondrial dysfunction, and enzyme inhibition, particularly of thiol-dependent antioxidant enzymes. Prolonged exposure leads to erethism, tremors, and renal impairment, though its acute lethality remains lower compared to organic species (32, 100). In contrast, inorganic mercury (Hg²⁺ and Hg⁺) species are less lipid-soluble and poorly absorbed through biological membranes. Their toxic effects are concentrated mainly in the kidneys and immune system, where they bind covalently to sulfhydryl-containing proteins in renal tubules, inducing nephrotoxicity, immune dysregulation, and oxidative damage. Chronic exposure leads to autoimmune glomerulonephritis and tubular necrosis, but limited CNS penetration confines their neurotoxic potential (101, 102). Methylmercury (CH₃Hg⁺) is the most environmentally widespread and biologically significant form. It bioaccumulates and biomagnifies in aquatic food webs, reaching toxic concentrations in fish and marine mammals consumed by humans(103, 104). Methylmercury’s high lipid solubility and affinity for thiol groups enable it to cross the blood–brain and placental barriers efficiently, leading to central nervous system (CNS) and developmental neurotoxicity. It disrupts neuronal migration, mitochondrial function, and redox homeostasis, resulting in sensory and motor deficits, cognitive impairment, and fetal developmental delays (32, 105). Ethylmercury (C₂H₅Hg⁺), principally originating from thimerosal in medical products, shows similar biochemical reactivity to methylmercury but exhibits faster metabolism and clearance (57). It is converted more readily to inorganic Hg²⁺ and evacuated within days, leading to lower tissue accumulation. Although acute high-dose exposure can induce oxidative stress, microtubule damage, and apoptosis, the risk of long-term neurotoxicity is substantially lower than that of methylmercury (106). In contrast, inorganic mercury (Hg²⁺ and Hg⁺) species are less lipid-soluble and poorly absorbed through biological membranes. Their toxic properties are concentrated mainly in the kidneys and immune system, where they bind covalently to sulfhydryl-containing proteins in renal tubules, inducing nephrotoxicity, immune dysregulation, and oxidative damage (107). Chronic exposure leads to autoimmune glomerulonephritis and tubular necrosis, but limited CNS penetration confines their neurotoxic potential (107). Overall, the comparative toxicity of mercury compounds is strongly correlated with their lipid solubility and persistence in biological systems (32). Organic mercury species generally methyl- and dimethylmercury are the most neurotoxic and bioaccumulative, whereas inorganic and elemental forms primarily target renal and immune functions. These distinctions underscore the importance of mercury speciation in environmental monitoring, toxicokinetic modeling, and public health risk assessment (55, 108). Table 2. Mercury’s toxicological profile Hg⁰ (Elemental Mercury) Inhalation of vapor ~80% absorbed via lungs; lipophilic, crosses blood–brain barrier; oxidized intracellularly to Hg²⁺ Brain, CNS Neurotoxicity: tremors, memory loss, mood changes, cognitive deficits (32, 109, 110) Hg²⁺ (Inorganic Mercury) Oral ingestion (salts), dermal contact Poor GI absorption (~7–15%); accumulates in kidneys Kidneys Nephrotoxicity: tubular necrosis, proteinuria, renal failure (111-113) MeHg (Methylmercury) Dietary (fish, seafood) >90% GI absorption; forms cysteine complexes; crosses blood–brain and placental barriers CNS, developing fetus Neurodevelopmental toxicity: cognitive impairment, motor dysfunction, sensory deficits (15, 114, 115) 3.3 Speciation dynamics in soil, water, sludge, and air There are high compartmental differences in mercury speciation because the environments or conditions that influence mercury transformations and stability are the pH, redox potential, organic matter content and microbial activity (116). Soil. In soils, most of the deposited mercury is inorganic Hg²⁺ complexed with organic materials, sulfides, and surface of minerals. Even though this binding can fix mercury, changing redox conditions, including flooding, land use alteration or thawing permafrost, may occur, and set free bound mercury into porewaters (117). Water. The most active compartments in terms of mercury transformation are aquatic systems. Hg 2+ can also be microbially methylated in the water column and sediments to produce methylmercury (MeHg), particularly under anaerobic conditions promoted by sulfate-reducing and iron-reducing bacteria (12, 118). MeHg in turn bioaccumulates in aquatic organisms and trophically magnifies (119, 120). The photochemical reactions in surface water enhance the degradation of MeHg to Hg 2+ as well as the reduction of Hg 2+ to Hg 0 , connecting aquatic processes directly to those in the atmosphere (121). Sludge and Sediments. Aquatic sediments, industrial and municipal sludge are also frequent foci of mercury [54]. Under these anaerobic conditions, high organic content, and reducing conditions have intense preference of microbial methylation of Hg 2+ Mercury bound in sludge could remain in inorganic states, although, in good microbial conditions, mercury is an important source of MeHg (12, 122, 123). The remediation of the sludge and sediment is not easy due to disturbances, i.e., a dredging or organic enrichment, which can cause mercury mobility and increase the possibility of methylation (124). Air. Elemental Hg 0 dominates mercury in the atmosphere and is long-lived and transportable on a long-range mercury cycle where it has a residence time of months to a year (125). The oxidation processes in the atmosphere, especially with the help of the halogen radical and the ozone, convert Hg 0 into the oxidized Hg 2+ that is very soluble and easily deposited by precipitation or dry deposition [58]. This process relates the atmospheric pools to the land and water systems (126). The Arctic mercury depletion events are episodic events that show how fast atmospheric Hg 0 oxidizes and deposits under certain conditions (10, 127) . When combined all these compartment-specific dynamics drive home the point that it is not the total load of mercury, but the response of speciation to local conditions that drives the overall environmental impact of mercury (128). The long-term storage centers include soil and sediments, active centers include water bodies, methylation, sludge is the hotspot of transformation, and the atmosphere serves as the main transportation medium of the earth (129). The combination of these compartments maintains the persistence of mercury and increases its role as a toxicology factor (82). 3.4 Role of pH, redox potential, organic matter, microbial activity Local physicochemical and biological conditions have a very strong effect on the speciation and fate of mercury in the environment (38). The pH, redox potential (Eh), organic matter and microbial activity are some of the most important drivers that may affect the stability, solubility and transformation pathways of mercury (130). pH . Mercury speciation is very sensitive to pH (95, 131). It is one of the most critical environmental parameters controlling mercury speciation, transformation, and partitioning between aqueous and solid phases. Under acidic environments (low pH), mercury solubility increases as Hg²⁺ dominates due to proton-promoted dissolution and desorption from mineral and organic matter surfaces. This enhances the mobility and bioavailability of inorganic mercury species (95, 132). Contrarywise, at neutral to alkaline pH, mercury tends to form less soluble hydroxyl (Hg(OH)₂) or sulfide complexes (HgS), leading to precipitation or strong adsorption onto particulate matter and organic ligands, thereby reducing bioavailability. Indirectly, pH also regulates methylmercury (MeHg) formation by inducing microbial activity and redox equilibria. In moderately acidic and suboxic conditions, sulfate-reducing and iron-reducing bacteria exhibit higher methylation rates, favoring MeHg accumulation in sediments and aquatic systems (118, 133). At higher pH, demethylation and mercury-sulfide complexation dominate, limiting methylmercury formation. Furthermore, shifts in pH alter the binding affinity of mercury for dissolved organic matter (DOM), affecting both Hg²⁺ speciation and transport. Therefore, pH-dependent processes critically regulate whether mercury remains inert, adsorbed, or is transformed into its most toxic bioavailable form, methylmercury (MeHg) (47, 134-136). When the pH is low the Hg 2+ is more soluble and mobile and as such prefers the formation of chloride and hydroxide complexes. Acidic conditions also improve the release of mercury in soils and sediments, which increases its bioavailability(131). Neutral to alkaline pHs on the other hand facilitate the formation of mercury sulfides or oxides, which tend to slow down its immediate movement (137). But at alkaline pH, dissolved organic matter can complex Hg 2+ and keep it in solution, and allow it to be transported (138, 139). Redox Potential. The redox chemistry of mercury controls the interconversion of the species. Hg 2+ is stabilized under oxidizing conditions, whereas Hg 0 is promoted under reducing conditions, and can be emitted as gaseous Hg 0 into the atmosphere (140). Reduction of Hg 2+ in anoxic conditions, including flooded soils, sediment, or sludge, can be either abiotic or biotic, although more importantly, this condition offers the environment in which methylation by microorganisms can occur (12, 118, 141). Therefore, redox gradients usually regulate whether mercury will be held in the sediments, to be remobilized or converted into methylmercury (142). Instabilities in redox potential, such as those induced by seasonal flooding, organic matter degradation, or eutrophication, can therefore stimulate both mercury release and methylmercury formation. Dynamic redox–pH interactions also influence demethylation developments and the speciation balance between Hg⁰, Hg²⁺, and MeHg. Under intermediate redox conditions, partial reduction of Hg²⁺ may generate elemental mercury (Hg⁰), which can volatilize into the atmosphere and participate in long-range transport. Hereafter, redox potential regulates not only the chemical form and mobility of mercury but also its bioavailability and cycling between environmental compartments (44, 143, 144). Organic Matter . Organic matter intensely effects mercury speciation, mobility, and bio-availability across terrestrial and aquatic systems. The dissolved and particulate organic matter (DOM, POM) has both functions. On the one hand, organic matter interacts well with Hg 2+ , reducing its instant bioavailability and locking it in soils and sediments (145). Conversely, DOM may serve as a carrier, which means the transportation of mercury in the environmental compartments (146). Besides, complexity stability is directly affected by certain functional groups within organic matter (thiols, carboxyls) (147). Significantly, photochemical reactions involving photochemical reduction of Hg 2+ to Hg 0 or, for example, degradation of methylmercury with the mediation of a chemical reaction are also possible with light, and the linkage of chemical speciation with photochemical processes occurs via the mediation of a chemical reaction (121, 148). The molecular composition of organic matter, especially the abundance of reduced sulfur groups and aromatic carbon, mostly determines its ability to complex, transport, and convert mercury species. Therefore, variations in DOM source and quality (e.g., terrestrial humic vs. algal-derived) strongly affect both inorganic and methylmercury speciation and cycle (135, 149). Microbial Activity . Microbial activity is a fundamental driver of mercury speciation and transformation in the environment. Microorganisms control the balance between methylated, reduced, and oxidized mercury species, anaerobic microorganisms are involved in mercury transformation (122, 150). Methylation involves sulfate-reducing, iron-reducing, and methanogenic bacteria in the reduction of inorganic Hg 2+ to methylmercury (MeHg) via the hgcA and hgcB gene pathway (151). These genes encode key enzymes responsible for mercury uptake and methyl group transfer, making microbial methylation the dominant natural source of MeHg in aquatic ecosystems. Methylmercury, being highly lipophilic and bioavailable, subsequently enters food webs, bioaccumulating and biomagnifying to toxic levels in higher organisms. Other microbial activities involve demethylation and reduction of Hg 2+ to Hg 0 (152, 153). The net production or degradation of methylmercury is dependent on the balance of microorganism community structure, the presence of electron acceptors (i.e., sulfate, iron), and environmental conditions all of which determine the production or degradation of methylmercury (118). These conditions combine to form a dynamic structure that defines mercury speciation and fate in the environment due to the presence of pH, redox potential, organic matter and microbial activity (116, 137). Even minor changes in any parameter e.g. acidification, eutrophication, or reduction of oxygen can invite the balance to lean toward either sequestration or production of bioavailable, toxic methylmercury (154). The dynamic interchange between microbial metabolism and geochemical environments thus directs the speciation, mobility, and toxicity of mercury across ecosystems, establishing microorganisms as both sources and sinks in the global mercury cycle (144, 155). Table 3. Influence of pH, redox potential, organic matter, and microbial activity on mercury speciation and toxicity. pH Low pH increases Hg²⁺ solubility and mobility; high pH favors precipitation but enhances complexation with organic matter. Acidic conditions increase bioavailability and mobility; alkaline systems may stabilize mercury but also promote transport via dissolved organic complexes. (130, 156) Redox Potential (Eh) Oxidizing conditions stabilize Hg²⁺; reducing conditions favor Hg⁰ volatilization; anoxic conditions promote methylation. Determines whether mercury is sequestered, re-emitted to atmosphere, or transformed into toxic MeHg . (156, 157) Organic Matter (DOM/POM) Binds Hg²⁺ strongly, reducing immediate bioavailability; facilitates transport; mediates photochemical reactions. DOM can immobilize mercury but also act as a carrier, influencing exposure pathways and degradation of MeHg. (158, 159) Microbial Activity Sulfate-, iron-reducing, and methanogenic microbes methylate Hg²⁺ → MeHg; others demethylate or reduce Hg²⁺ → Hg⁰. Microbial processes control net MeHg production, the key toxic form responsible for bioaccumulation and biomagnification (160-162) 3.4 Speciation shifts during transport and transformation Mercury does not just exist in one chemical state as it circulates within environment compartments. Rather it experiences constant changes in speciation that reestablishes its mobility, persistence and toxicity in transit and transformation (127, 163, 164). Atmospheric Transport. Mercury is released into the atmosphere in the form of elemental Hg⁰ and has a potential to persist in the air months and be subjected to long-range delivery. Oxidation by halogen radicals, ozone or hydroxyl radicals during transit converts Hg is oxidized to Hg across to Hg²⁺ (164, 165). This change significantly decreases the residence time in the atmosphere because Hg²⁺ is more soluble and is readily removed by wet or dry deposition. Therefore, the atmospheric leg of the mercury transport bridges the connection between the global dispersal and the local deposition hot spots (163, 166). The Deposition to Terrestrial Systems. After being deposited on soils, Hg²⁺ can alternate among strongly bound complexes (e.g. to sulfides or organic matter) and more labile forms which partition into porewaters (167). With changing redox conditions, Hg²⁺ can be reduced back to volatiles Hg⁰ , which allows the emission of Hg back to the atmosphere (140, 168). As an alternative, in anaerobic or waterlogged soils, the Hg²⁺ can be converted through microbial methylation into methylmercury (MeHg), converting it to a much more toxic and bioavailable state (117, 141, 169). Aquatic Transformation. Rivers, lakes, and the sea systems serve as active of grounds of speciation change. The entry of Hg²⁺ into the surface waters can also be complexed with chloride or dissolved organic matter and determine its photoreactivity and solubility (116, 170). Under anoxic conditions in sediments, Hg²⁺ is subjected to microbial methylation to produce MeHg which easily enters into the food web. Photochemical reactions also redistribute speciation by lowering the Hg²⁺ to Hg⁰ , which can be recycles back into the atmosphere or by converting MeHg to less bioavailable inorganic forms (116, 171, 172). Sediments and Sludge. Mercury speciation is stabilized in other forms in deeper anoxic sediments or sludge environments. The more drastic conditions can easily encourage the formation of mercury sulfides (HgS), that is a relatively immobile mercury form. However, perturbations (e.g. dredging, eutrophication, redox chemical changes, etc.) can revert speciation and restore mercury cycling to more labile and methylatable form(133, 167, 173). Figure 2. Conceptual flowchart of mercury speciation across environmental compartments. 4. Speciation-Dependent Uptake in Plants and phytotoxicity The uptake of mercury by plants greatly relies on the chemical form of mercury and the various species have varied paths, mobility and toxicological consequences (174). Although the sum total of mercury in soils or air will give a rough estimate of contamination, it is the speciation of mercury, and not the total quantity, that determines whether mercury will be held in roots, translocated to shoots or be incorporated into edible tissues (175). Elemental-Mercury-(Hg⁰): Though less phytotoxic directly, it can be converted to reactive Hg²⁺ in the rhizosphere or leaf surfaces under light and microbial activity. Hg⁰ occurs in the air as a gaseous pollutant, and it is absorbed mainly through stomata in the leaf tissues (176). Hg⁰ is lipophilic and therefore is able to diffuse through membranes but is then oxidized to Hg²⁺ within plant cells (177). This conversion increases its affinity with thiol-binding proteins and cell wall constituents, which in most cases leads to localized accumulation (178). Increased Hg⁰ levels in the atmosphere have been correlated with decreases in photosynthetic rate, chlorophyll damage and stomatal control (176, 179). Inorganic-Mercury (Hg²⁺): The most common form of Hg in polluted soils and sediments is Hg²⁺ and its major absorption is by roots (168, 180). It is strongly attached to cell wall polysaccharides, and combines with thiols and glutathione and phytochelatins once within root tissues (181). These binding processes serve as detoxification systems but also in restricting the movement of mercury hence translocation by mercury to aerial components of the plant is reduced (182, 183). Nevertheless, in very polluted soils, oxidative stress, lipid peroxidation, and root growth inhibition is severe, which negatively affect nutrient uptake and plant productivity (184). Methyl-mercury (MeHg): More readily translocated to shoots and grains, it affects reproductive tissues and seed development. It exhibits stronger interference with protein synthesis and antioxidant enzymes than inorganic forms. MeHg is more mobile and bioavailable than Hg²⁺, despite not being found in soils and waters at concentrations greater than the latter (9, 185). Roots can take it up and move to the shoots, presumably through mimicking of amino acids and via transporters like cysteine or methionine. This property leads to food safety concerns, where the MeHg may amount in consumable parts of plants, and thus make its way to food chains on land (186, 187). MeHg causes more oxidative stress than Hg²⁺ in plant tissues, modifies antioxidant enzyme systems and compromises metabolism (9, 188).In general, Hg²⁺ is relatively immobile and accumulates in roots whereas MeHg is more likely than Hg²⁺ to translocate, and atmospheric Hg⁰ is preferentially absorbed by leaves (189). These variations highlight the importance of speciation of mercury in determining the uptake of the chemical by plants, its ecological risk, and food security effects in polluted areas (56). Mechanistic Basis of Mercury-Induced Phytotoxicity The phytotoxicity of mercury (Hg) is strongly dependent on its chemical speciation, which dictates its reactivity, bioavailability, and interaction with plant biochemical systems. Both inorganic (Hg²⁺) and organic (methylmercury, CH₃Hg⁺) forms disrupt plant physiology through redox imbalance, protein dysfunction, metabolic inhibition, and genotoxic stress (56, 183, 190). The following subsections detail the primary molecular and physiological mechanisms underlying mercury-induced phytotoxicity. Oxidative Stress and Redox Imbalance: A trademark of Hg-induced toxicity is the generation of reactive oxygen species (ROS), including superoxide radicals (O₂•⁻), hydrogen peroxide (H₂O₂), Hydroxyl radicals (•OH). Hg²⁺ and CH₃Hg⁺ disrupt electron transport chains in chloroplasts and mitochondria, leading to electron leakage and uncontrolled ROS production (191). Then ROS accumulation damages lipids (lipid peroxidation), nucleic acids, and proteins, compromising membrane integrity and enzymatic functions. Mercury binds to thiol (-SH) and selenol (-SeH) groups in enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), inhibiting their activity and thus exacerbating oxidative stress (86, 192). Inorganic Hg²⁺ primarily causes localized oxidative damage at root surfaces. While, CH₃Hg⁺, being lipophilic, penetrates membranes and induces systemic oxidative stress in leaves and reproductive tissues (193). Thiol Binding and Enzyme Inhibition: Mercury exhibits an exceptional affinity for thiol-containing biomolecules. It forms stable Hg–S or Hg–Se bonds with cysteine and selenocysteine residues in proteins, leading to enzyme inactivation (194, 195). Hg²⁺ and CH₃Hg⁺ disrupt critical enzymes in glycolysis (e.g., glyceraldehyde-3-phosphate dehydrogenase), Calvin cycle, and nitrogen assimilation (e.g., nitrate reductase). Inhibition of ATPase and H⁺-pump enzymes in membranes disturbs ion homeostasis, impairing nutrient uptake (K⁺, Ca²⁺, and Mg²⁺). Binding to thiol-rich antioxidants (e.g., glutathione, phytochelatins) depletes these molecules, lowering the redox buffering capacity of cells (196, 197). Disruption Membrane Structure and Ion Transport: Mercury alters membrane permeability and lipid composition, resulting in electrolyte leakage and impaired nutrient transport. Hg²⁺ promotes peroxidation of unsaturated fatty acids, leading to loss of membrane fluidity and selective permeability. Ion channel inhibition causes Ca²⁺ imbalance, which triggers signaling cascades that lead to programmed cell death (PCD) in roots and leaves. Hg exposure also disrupts aquaporins, affecting water transport and stomatal regulation (32, 183, 188). Photosynthetic impairments and Respiratory Metabolism: Photosynthesis is among the most sensitive targets of mercury toxicity. Hg²⁺ replaces Mg²⁺ in the chlorophyll molecule, resulting in chlorophyll degradation and chlorosis (183). Both Hg²⁺ and CH₃Hg⁺ inhibit photosystem II (PSII) electron transport and Rubisco activity, leading to reduced CO₂ fixation. Mitochondrial respiration is inhibited through Hg binding to respiratory enzymes (e.g., cytochrome c oxidase), reducing ATP generation and energy supply for cellular metabolism(183, 198). Disturbance in Hormonal Signaling and Gene Regulation: Mercury exposure alters the phytohormonal balance that regulates growth and stress responses. Elevated ethylene and abscisic acid (ABA) levels under Hg stress lead to stomatal closure and growth retardation(198). Auxin (IAA) signaling is disrupted by Hg interference with auxin transporters (PIN proteins), resulting in abnormal root architecture (199). Transcriptomic studies show upregulation of stress-related genes (e.g., HSPs, GSTs, MTs) and downregulation of photosynthetic and metabolic genes under Hg exposure. In Arabidopsis thaliana , exposure to 10 µM Hg²⁺ upregulated MT2a and PCS1 genes involved in Hg detoxification but downregulated LHCB1 and RBCS, key genes in photosynthesis (200-203). Genotoxic and Cytological Effects: Mercury causes DNA damage, chromosomal aberrations, and mitotic abnormalities due to direct interaction with DNA and associated proteins. Hg²⁺ and CH₃Hg⁺ bind to phosphate groups in DNA, leading to strand breaks and base modifications (204). Hg-induced oxidative stress contributes to 8-hydroxy-2’-deoxyguanosine (8-OHdG) formation a marker of oxidative DNA damage. Cytological manifestations include micronuclei formation, chromosome stickiness, and mitotic spindle disorganization, ultimately leading to cell death or mutagenesis (205, 206). 5. Remediation Strategies and Speciation Shifts The remediation strategies should take into consideration speciation-related mobility and toxicity. The removal of Hg²⁺ with phytotransformation Hyperaccumulator plants Phytoremediation is a form of remediation that is sustainable. Wetlands have mosses and aquatic macrophytes that absorb mercury in water bodies. Microbial remediation entails strains that are resistant to mercury and which can methylate, demethylate and volatilize (207, 208). Biochar and activated carbon are useful sorbents to Hg²⁺ and MeHg, especially in effluents and sediments. Silica and graphene oxide nanomaterials functionalized by thiols and graphene oxide are promising selective mercury binders. Hg⁰ can be captured and MeHg degraded in complicated matrices with the aid of electrochemical and photocatalytic techniques (209, 210). 5.1 Phytoremediation The plants are natural controls of mercury cycling by means of uptake, sequestration and volatilization (211). Woody plants including Populus and Salix are extensively researched with regards to their capacity to immobilize Hg²⁺ in the roots and woody biomass (212). Other genotypes also reduce Hg²⁺ to Hg⁰, which facilitates phytovolatilization. Although this minimizes the contamination of the soil, it creates a movement toward atmospheric transport. The primary role of grasses and energy crops ( Miscanthus, Panicum virgatum ) is phytoextractors, which accumulate Hg²⁺ in the aboveground biomass without significant transformation, which implies that the results are very dependent on the safe disposal of biomass (213, 214). Wetland plants such as Phragmites australis, Typha latifolia, Eichhornia crassipes, Juncus effusus (soft rush) have been widely studied for mercury remediation in sediments and floodplains (215-217). They provide a two-sided effect: root oxygenation can inhibit the process of Hg²⁺ MeHg methylation but the accumulation of organic matter in the anaerobic rhizospheres can promote it. In this way, phytoremediation focuses mercury mainly on Hg²⁺ pools that are immobilized or volatile Hg⁰, but its effect on MeHg processes is extremely contextual (211). Among aquatic macrophytes, Lemna minor (duckweed) and Eichhornia crassipes (water hyacinth) are particularly effective for mercury removal from contaminated waters (218, 219). Studies demonstrated that Lemna minor efficiently absorbs Hg²⁺ and CH₃Hg⁺, binding mercury to thiol-rich proteins and effectively reducing dissolved concentrations. Eichhornia crassipes rapidly removes Hg²⁺ through its extensive root system and shows high tolerance in wastewater environments (220). These species are among the most promising for phytofiltration and phytostabilization in aquatic systems. Among terrestrial plants , Brassica juncea has been the most extensively investigated for mercury remediation. It shows strong tolerance to Hg²⁺ and accumulates mercury mainly in shoots and roots through phytoextraction, with some potential for limited phytovolatilization of Hg⁰ under natural redox conditions. Its effectiveness in soil systems was demonstrated by Raj in 2020 (221) and later confirmed in comparative trials of Brassicaceae species by Makarova et al., 2022 (222). Brassica napus (canola) also exhibits high root uptake and moderate translocation of Hg²⁺, making it suitable for moderately contaminated soils (223). High-biomass terrestrial species such as Helianthus annuus and Vetiveria zizanioides have been recognized for their strong mercury retention capacity. Helianthus annuus efficiently absorbs Hg²⁺ from soil, storing most of it in root tissues and reducing leachable fractions, as observed by Hein and Mi (224). Vetiver grass demonstrates exceptional tolerance to Hg contamination and retains most of the absorbed mercury in its fibrous root zone, which makes it an ideal candidate for phytostabilization and soil erosion control (225). Similarly , Lolium perenne (perennial ryegrass) contributes to mercury immobilization via rhizostabilization, with root exudates enhancing Hg–organic complex formation and limiting metal mobility (226). Crop plants have also been examined for mercury uptake potential. Oryza sativa (rice) is notable for its ability to absorb both inorganic mercury (Hg²⁺) and methylmercury (CH₃Hg⁺) in paddy soils (227). Research by Tang (228) revealed that mercury predominantly accumulates in roots, with minimal translocation to grains, indicating strong potential for phytoaccumulation and stabilization rather than complete removal. Solanum nigrum (black nightshade) has shown natural mercury tolerance and accumulation in its aerial parts under moderate soil contamination, suggesting its role as a non-hyperaccumulator species with phytoremediation potential(229). In addition, Pteris vittata (Chinese brake fern), although primarily known for arsenic uptake, has demonstrated the ability to accumulate Hg²⁺ in fronds in mixed-metal soils, indicating multi-metal remediation capacity (230). Other aquatic and semi-aquatic species also contribute to mercury removal. Trifolium repens (white clover) supports microbial communities in the rhizosphere that enhance mercury immobilization and detoxification (231, 232), while microalgal species such as Chlorella vulgaris and Spirodela polyrhiza have been reported to remove Hg²⁺ and CH₃Hg⁺ from water through biosorption and intracellular sequestration (233, 234). Collectively, these naturally occurring terrestrial and aquatic plants represent effective tools for mercury remediation, each suited to specific speciation and environmental contexts Despite extensive work on herbaceous hyperaccumulators and aquatic macrophytes, several plant categories remain underexplored in mercury phytoremediation research. Overall, the lack of studies on these plant groups reflects a combination of ecological mismatch, limited tolerance to Hg toxicity, slow growth or low biomass, and ethical constraints related to food safety. Current research remains concentrated on fast-growing, high-biomass, non-edible plants that can tolerate and immobilize mercury effectively in contaminated terrestrial and aquatic environments. 5.2 Microbial Remediation Microbes are the strongest biological agents of mercury speciation, and cause the risk-enhancing and detoxifying changes (213). The reducing bacteria ( Desulfovibrio, Geobacter ) and methylating methanogens ( Methanospirillum, Methanosarcina ) reduce Hg²⁺ to MeHg through the hgcAB pathway, which exacerbates toxicity (235). Conversely, bacteria that possess the mer operon attenuate the toxicity of mercury: merB breaks the C–Hg bond of MeHg to produce Hg²⁺ and merA breaks down Hg²⁺ to create Hg⁰ , which is less toxic but volatile. Such detoxifying changes also reduce the bioavailability and redistribute mercury back to the atmosphere. Eventual outcome of community composition, redox conditions and nutrient availability determine whether microbial remediation will increase MeHg build up or lead to detoxification (236). 5.3 GMO-Enhanced Phyto- and Microbial Systems Genetically modified organisms (GMOs) are being created to help overcome the constraints of natural species so that mercury speciation can be directed to detoxification pathways. Genetically modified plants Transgenic plants with merA and merB genes demonstrate greater ability to convert MeHg to Hg²⁺ , and then to convert Hg²⁺ to Hg⁰ (237) . Other modifications with metallothioneins and phytochelatins enhance Hg²⁺ vacuoles sequestration, reducing bioavailability (238). The shifts aim at the species that is the most toxic MeHg, and immobilization or regulated volatilization is allowed. Engineered microbes (E. coli, Pseudomonas putida, Shewanella strains) with genes of the mer operon or metallothionein can also do faster demethylation and reduction and effectively convert MeHg to Hg²⁺ to Hg⁰ to reduce, or trap Hg²⁺ in the cell(239). These systems have the potential towards bioreactors and contained remediation units but ecological release is limited due to biosafety issues (240). Combined with GMO-based approaches are a new frontier: they offer a specific direction of control of the changes in speciation, with MeHg being directly removed, and Hg 2 + being retained or volatilized in less toxic forms (241). Sludge and Thermal Treatment (Supporting Approaches) The main goal of sludge treatment is to immobilized mercury species and prevent remobilization or methylation during handling and disposal (242). Chemical stabilization is one of the most effective sludge-based remediation methods. Sulfide- and iron-based reagents, such as ferric sulfide (FeS) , iron (III) chloride , and sodium sulfide , are used to convert mobile Hg²⁺ into stable crystalline forms like mercury sulfide (HgS) , predominantly cinnabar (α-HgS) and metacinnabar (β-HgS), which exhibit extremely low solubility (Ksp ≈ 10⁻⁵³) (243, 244). This transformation minimizes the risk of mercury leaching and reduces its bioavailability in sludge-amended soils (245). The stabilization of the sludge fixes the Hg²⁺ to sulfide or organic layers, thereby decreasing its leachability, but anaerobic conditions can increase the process of microbial methylation (133). Organomercury is destroyed by thermal processes like incineration and vitrification, and the Hg²⁺ is reduced to Hg⁰ gas (246). The two methods minimize the solid-phase burdens, but tend to be redistribution of the mercury to the volatile pools unless it is combined with capture technologies (133). Thermal treatment technologies, including pyrolysis, incineration, and thermal desorption, are employed to destroy or volatilize mercury compounds from contaminated sludge, soil, and waste materials (247). The mechanisms of mercury removal depend on temperature, atmosphere (oxidizing or reducing), and the chemical form of mercury (248). Thermal desorption has been applied to contaminated soils and sediments, with removal efficiencies exceeding 90 %. It involves heating the matrix in controlled conditions (200–600 °C) to volatilize mercury, followed by gas-phase recovery through condensation or sorbent filtration (249-251). The speciation transformation of mercury during sludge and thermal treatments is central to understanding its fate and stability. Thermal processes represent both a removal and transformation technology, converting toxic and bioavailable species into recoverable elemental mercury or stable solid residues (250). However, improper process control can lead to re-volatilization or incomplete capture, causing secondary atmospheric pollution. For this reason, integrated systems combining sludge stabilization, low-temperature pyrolysis, and emission capture are preferred for sustainable mercury management. Table 4: Phytoremediation, Microbial Remediation, and GMOs – Speciation Shifts and Outcomes Woody plants Populus (poplar), Salix (willow) Hg²⁺ → immobilized (root/wood); Hg²⁺ → Hg⁰ (phytovolatilization) Stabilizes Hg²⁺ in biomass; volatilization shifts burden to atmosphere (252-254) Grasses / energy crops Miscanthus , Panicum virgatum (switchgrass) Hg²⁺ → Hg²⁺ (accumulated in aboveground tissues, minimal transformation) Extracts Hg²⁺ but requires biomass management; limited speciation change (189, 255, 256) Wetland plants / macrophytes Phragmites australis , Typha latifolia , Eichhornia crassipes Root O₂ release suppresses Hg²⁺ → MeHg; but anoxic rhizosphere may enhance methylation Outcomes depend on hydrology: may mitigate or exacerbate MeHg (118, 257, 258) Sulfate-reducing bacteria (SRB) Desulfovibrio , Desulfobacter Hg²⁺ → MeHg (via hgcAB ) Risk of enhanced MeHg production (259-261) Iron-reducing bacteria Geobacter , Shewanella Hg²⁺ → MeHg; some Hg²⁺ → Hg⁰ Dual role: both MeHg generation and detoxification (262-264) Methanogens Methanospirillum , Methanosarcina Hg²⁺ → MeHg Adds to MeHg burden in anaerobic sediments (265, 266) mer-operon bacteria Pseudomonas , Bacillus , Cupriavidus metallidurans MeHg → Hg²⁺ (merB); Hg²⁺ → Hg⁰ (merA) Detoxifies organomercury; volatilization can increase atmospheric Hg (267-269) Transgenic plants Arabidopsis thaliana , Nicotiana tabacum , GM Populus (engineered with merA/merB ) MeHg → Hg²⁺ (via merB); Hg²⁺ → Hg⁰ (via merA); Hg²⁺ sequestration in vacuoles (via metallothioneins, phytochelatins) Strong reduction of MeHg toxicity; controlled volatilization; enhanced Hg²⁺ immobilization in tissues (106, 269, 270) Engineered microbes E. coli , Pseudomonas putida , Shewanella strains with mer operon or metallothionein genes MeHg → Hg²⁺; Hg²⁺ → Hg⁰; enhanced intracellular sequestration Highly efficient detoxification, but containment and ecological release are concerns (239, 269, 271) 5.5 Comparative Perspective Phytoremediation and microbial remediation are the most applicable remediation methods to speciation control as these directly regulate the relationship between Hg²⁺ , Hg⁰ and MeHg (272). GMOs enhance these natural procedures and provide specific detoxification effects of organomercury yet regulation becomes tricky. Comparatively, bulk mercury pools are controlled in most part by sludge and thermal treatment methods whereby there is a possibility of shifting into airborne Hg⁰ (273, 274) . The remediation must be effective thus necessitating a speciation cognizant framework: the remediation must reduce the production of MeHg, immobilize the Hg²⁺ where it is possible and the volatile Hg⁰ should be managed carefully to avoid the secondary contamination (275). Impact categories (“High Risk”, “Neutral”, “Effective”, etc.) replace raw numbers for intuitive interpretation. Remediation success depends on site-specific speciation, pH, redox conditions, and organic matter content, requiring tailored strategies Figure 3. Comparative efficacy of remediation strategies by mercury form 6. Analytical Techniques Mercation needs sensitive, selective and matrix compatible methods to provide accurate mercury speciation. Cold vapor atomic fluorescence spectrometry (CVAFS) is among the gold standard methods of detecting total mercury. Hg²⁺ , MeHg, and EtHg can be separated and determined using high-performance liquid chromatography interconnected with inductively coupled plasma mass spectrometry (HPLC -ICP-MS) (276). X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) is a type of speciation of molecules in solid samples at the molecular level. GCMS can be used with volatile mercury compounds such as dimethylmercury. Electrochemical sensors provide high-speed, inexpensive Hg²⁺ detection, with the new designs having MeHg selectivity. The most recent developments are lab-on-chip systems, microfluidics, and portable mercury spectrometers to be used in the field (277). 6. Analytical Techniques for Speciation To comprehend the effects of mercury on the environment and human health it is necessary to have analytical tools to differentiate among the chemical species of mercury (120). The overall levels of mercury do not have the capacity to forecast bioavailability or toxicity, as risks posed by elemental mercury ( Hg⁰ ), inorganic divalent mercury ( Hg²⁺ ), and organomercury mercury (MeHg) are vastly different. Analysis thus becomes a key factor in monitoring changes in the air, water, soils, sediments, and biological media (278). 6.1 Chromatographic–Mass Spectrometry Coupling (HPLC-ICP-MS) HPLC-ICP-MS is extensively considered a gold standard of mercury specification. Separating individual species (e.g., Hg²⁺ , MeHg, EtHg) is done by the chromatographic step, and quantifying the species with high sensitivity (usually parts-per-trillion) is done by ICP-MS. The method has been essential in food safety research (e.g., fish and rice contamination), soil sediment interactions and bioaccumulation research (279). Its limitations though are that it is very expensive, requires well-equipped laboratories and interconversion may occur between the species in the process of extraction and sample preparation (280). 6.2 Cold Vapor Atomic Fluorescence Spectrometry (CVAFS) CVAFS continues to be used in ultra-trace detection of gaseous Hg⁰ and aqueous Hg²⁺ . It works by lowering Hg²⁺ to bare mercury vapor after which it is excited and measured through fluorescence. Among the lowest are detection limits (sub-ppt), which makes CVAFS a reference technique of monitoring the atmosphere and long-term water quality research. Its key disadvantage is that it cannot directly speciate organomercury compounds; it must first be chemically transformed to Hg²⁺ which can upset the speciation balance that researchers want to know (281). 6.3 Synchrotron-Based X-ray Absorption Spectroscopy (XAS) XAS offers in-situ coordination chemistry of mercury in a one-of-a-kind and non-destructive manner (282). It does not require the extraction of the soil, sediments, or sludge unlike the solution based methods, which allows it to be applied directly to the native chemical environment (283). It has played an important role in unveiling the manner in which Hg²⁺ attaches to sulfides, organic matter or mineral phases. The technique is, however, sensitive (ppm levels), requires the availability of synchrotron facilities, and is difficult in separating the species with low abundance in heterogeneous samples (284). 6.4 Electrochemical Sensors Mercury detection in water and wastewater Electrochemical platforms, commonly founded on anodic stripping voltammetry, have been modified to mercury. The development of nanomaterials (e.g. gold nanoparticles, graphene) has increased selectivity and sensitivity that allows detection limits to reach the low ppb range (123, 285). They are portable and cheap making them appealing as they can be deployed in the field. However, electrochemical techniques are usually sensitive to Hg²⁺ and do not solve organomercury easily, and interference of signals by complicated natural waters has also been one problem (123, 286). 6.5 Biosensors and Emerging Approaches Another new direction is biosensors, which are microbial strains engineered, enzyme-based assays or systems of DNA aptamers (287). They include species-selective bioindication (e.g., MeHg or Hg²⁺ ) and possible real-time, field-capable monitoring. Although it seems to be promising, biosensors are usually affected by stability problems, environmental variability sensitivity, and the absence of regulatory validation. However, they are being integrated with microfluidics, nanotechnology and even AI-based signal processing very fast (288). 6.6 Current Challenges and Outlook One of the issues that are common in all the methods is that mercury species are very dynamic. Redox changes or methylation/demethylation can be caused by sampling, storage and chemical extraction resulting in artifactual results (289). In situ speciation mapping is rare, particularly of complex systems such as sediments and sludge. Moreover, the current means of study are often limited to high resource facilities, and leave major gaps in the developmental nations where exposed people are at the highest risk of mercury exposure (290). Future strategy involves smaller size of HPLC-ICP-MS, increased use of portable CVAFS, next generation biosensors and hybrid technologies involving the use of electrochemical and optical sensors. There is also the incorporation of the speciation analysis with geochemical modeling and risk assessment models, - so that regulatory limits are not merely in the quantity of mercury, but that it is in what form (278). Table 5. Comparison of Mercury Speciation Analysis Methods HPLC-ICP-MS ppt–ppb Resolves organomercury; quantitative, highly sensitive Costly; lab-based; possible-species inter conversion during prep Water, food, tissues, soils, sediments (291) CVAFS sub-ppt Ultra-trace Hg⁰/Hg²⁺ detection; atmospheric & aqueous gold standard Cannot directly detect MeHg/EtHg Air, water (292) XAS (synchrotron) ppm Insitu speciation; preserves native environment Limited sensitivity; synchrotron access required Soils, sediments, sludge (293) Electrochemical Sensors ppb Portable, low-cost, rapid Matrix interference; mainly Hg²⁺ only Water, wastewater (294, 295) Biosensors ppb–low ppt Selective, field-deployable, species-specific Still experimental; stability concerns Aquatic systems, sediments (pilot studies) (296) Figure 4. Analytical techniques Linking Mercury Speciation to Environmental Media (Enhanced Clarity) 7. Policy, Risk Assessment, and Governance The Minamata Convention is designed to cut down on anthropogenic emissions of mercury and safeguard the vulnerable groups. Nonetheless, most regulatory limits rely on total mercury which ignores toxicity which depends on speciation. There is need to have speciation-sensitive risk assessment to be able to model exposure more accurately, particularly in rice-eating populations and artisan gold mining communities (297, 298). 7.1 Global Progress and Current Limitations The introduction of Minamoto Convention on Mercury in 2013 was a best twist in efforts of curbing mercury pollution in most parts of the world. Being the first international treaty to undergo a holistic approach to mercury, it has offered a valuable legal basis of cutting down on emissions, eliminating mercury-added items, and the artisanal and small-scale mining of gold (299, 300). However, even with this development, there is a significant shortcoming, namely that the Convention and most national laws are still based on aggregate mercury stocks and not chemical forms. By doing this, this method ignores the fact that the toxicity, bioavailability and environmental persistence of mercury differ significantly among species (299). Considering mercury as one, global governance undermines the actual health and environmental risks in the areas where the processes of methylation prevail (11). 7.2 Risk Assessment Frameworks and Gaps Existing risk assessment schemes within the present global context has the same weakness. In most countries, the environmental quality standards, food safety and water guidelines are pegged on bulk levels of mercury (301). It has taken some steps forward - especially in such areas as North America and Europe, where fish consumption warnings are now made with reference to methylmercury, but no international system exists globally to stipulate and enforce methylmercury-specification thresholds. Consequently, the inhabitants of mercury sensitive areas, especially those that consume fish and rice as staple foods, continue experiencing the hazards of methylmercury which are not visible in the total mercury reporting (302). In a similar manner, remediation projects are still considered as successful primarily based on the premise of the overall mercury reduction, although there is evidence that some interventions have the ability to effect geochemical changes in a manner that leads to higher levels of methylation and risk to the ecology. Remediation can seem effective on paper when there is no direct observation of speciation prior to intervention and after but it exposes communities as vulnerable (303). 7.3 Monitoring Disparities and Global Inequities Another issue that is faced in international regulation is the asymmetry of the monitoring capacity. Such specialized methods as HPLC-ICP-MS or X-ray absorption spectroscopy procedures obtained on a synchrotron are confined in richer nations and research-oriented organizations. Much of the world is forced to depend on bulk mercury testing and is thus incapable of identifying hotspots of methylmercury, or long-term changes in species at species level (55). Such inequity does not only undermine the comparability of international datasets but also the efficiency of Minamata Convention which requires proper reporting on national levels (304). In the absence of fair access to speciation monitoring mechanisms, the global mercury management is likely to fulfill the role of enforcing inequality by exposing vulnerable groups to insufficient protection and underrepresentation in global considerations (55). 7.4 Climate Change and Emerging Risks The global governance is also reactive, looking at the current emissions and pollution without much consideration to the developmental forces of speciation (305). Improved by climate change and terrestrial land-use, the risks of mercury are likely to grow through the increasing speed of microbial methylation and growing contamination hotspots (6). The processes of permafrost thawing, reservoir formation, wetland growth, and hydrology are also known to have environments favorable to the formation of methylmercury, but few policy frameworks incorporate them (306). In the absence of proactive strategies to think how global change will modify mercury speciation and exposure routes, global evaluations may be underestimated to be underestimated in the future, especially in food-insecure regions where exposure through diet is already high (305, 307). 7.5 Future Global Directions The only way to seal these cracks is by switching into a system of global governance which is explicitly speciation-sensitive (308). The adaptation of the Minamata Convention in future must promote reporting of methylmercury and other species in addition to the total mercury and global standards must be aligned to show the risks of the species in food, water, and sediments (54). Developing capacity at the global level is crucial and it will necessitate international financing and collaboration to assist in providing laboratories, training and technology transfer (309). Meanwhile, it is important to introduce predictive models helping to integrate climate, hydrology, and biogeochemistry in global policy development and in order to predict the hotspots and intervene in advance (310). Lastly, the strategy of risk communication should be enhanced in a way that the communities across the world learn that not all mercury is identical and that the counsel is translated into a community-specific and culturally competent advice (311). The MeHg and Hg²⁺ speciation is actively developed in regional monitoring programs, which allows specific advice (168, 311, 312). Safety guidelines of food must include specification data especially of rice, fish, and shellfish (278). Mercury levels of occupational exposure of the vapor (Hg 0 ) are different across the world, and more stringent levels are produced in accordance with neurobehavioral research (313). Biomonitoring based on community-based monitoring of hair, blood and rice specimens aids in speciation-based intervention (312). An additional way of integrating data on speciation, exposure pathways and remediation efficacy into dynamic risk models and the adaptive policy frameworks of the future is necessary. 8. Conclusion Without chemical speciation, it is impossible to comprehend and alleviate mercury pollution. In atmospheric transportation to neurotoxicity, in food crop poisoning to microbial cleaning, speciation rules the behavior, risk and response potential of mercury. Understanding mercury speciation is therefore essential for developing effective remediation strategies, including phytoremediation and microbial methods that are tailored to specific mercury forms, as well as for employing advanced analytical techniques that allow precise monitoring of mercury transformations in different environmental compartments. Furthermore, incorporating speciation-based understandings into regulatory frameworks is critical, as reliance merely on total mercury measurements may underestimate ecological and human health risks. Moving forward, integrating speciation-aware strategies in both research and policy will enhance the safety, efficiency, and sustainability of mercury management efforts worldwide. Speciation does not happen by chance rather it is the determinant. 8. Declarations Acknowledgements This work was supported by the Medical Joint Special Project of Kunming University of Science and Technology-The First People’s Hospital of Anning (KUST-AN2023006Y) and the project of People’s Hospital of Wuding County. Conflicts of Interest: “The authors declare no conflict of interest.” Author Contributions: Conceptualization: Haiyan Li: Writing – original draft: Naila Shah: Writing – review & editing: Naila Shah, Muhammad Awais and Haiyan Li: Visualization: Naila Shah, Muhammad Awais: Supervision: Haiyan Li 9. Supplementary Material (if applicable) Figures, tables, datasets, or extended methods Upload separately during submission REFERENCES ( Naila endnote prepared list) 1. Pant R, Mathpal N, Chauhan R, Singh A, Gupta A. A review of mercury contamination in water and its impact on public health. Mercury Toxicity Mitigation: Sustainable Nexus Approach. 2024:93-115.2. Zhou Y, Li S, Tang W, Zhong H. Mercury transformations by reactive oxygen species: Occurrence, detection, evidence, and challenges. Critical Reviews in Environmental Science and Technology. 2025;55(13):977-1000.3. Chen Y, Wang Z, Fang Y, Wang G, Zhou F, Yu J, et al. Occurrence and microbial remediation of polycyclic aromatic hydrocarbons and heavy metals pollution in soils. World Journal of Microbiology and Biotechnology. 2025;41(8):280.4. Gworek B, Dmuchowski W, Baczewska-Dąbrowska AH. Mercury in the terrestrial environment: a review. Environmental Sciences Europe. 2020;32(1):128.5. Rana MN, Tangpong J, Rahman MM. Toxicodynamics of lead, cadmium, mercury and arsenic-induced kidney toxicity and treatment strategy: a mini review. Toxicology reports. 2018;5:704-13.6. Janowska B, Szymański K, Sidełko R, Siebielska I, Walendzik B. Assessment of mobility and bioavailability of mercury compounds in sewage sludge and composts. Environmental research. 2017;156:394-403.7. Handschuh‐Wang S, Wang T, Gancarz T, Liu X, Wang B, He B, et al. The liquid metal age: a transition from Hg to Ga. Advanced Materials. 2024;36(45):2408466.8. Kim K-H, Kabir E, Jahan SA. A review on the distribution of Hg in the environment and its human health impacts. Journal of hazardous materials. 2016;306:376-85.9. Sonke JE, Angot H, Zhang Y, Poulain A, Björn E, Schartup A. Global change effects on biogeochemical mercury cycling. Ambio. 2023;52(5):853-76.10. Dastoor A, Angot H, Bieser J, Christensen JH, Douglas TA, Heimbürger-Boavida L-E, et al. Arctic mercury cycling. Nature Reviews Earth & Environment. 2022;3(4):270-86.11. Różański SŁ, Castejón JMP, Fernández GG. Bioavailability and mobility of mercury in selected soil profiles. Environmental Earth Sciences. 2016;75(13):1065.12. Regnell O, Watras CJ. Microbial mercury methylation in aquatic environments: a critical review of published field and laboratory studies. Environmental science & technology. 2018;53(1):4-19.13. Basu N, Bastiansz A, Dórea JG, Fujimura M, Horvat M, Shroff E, et al. Our evolved understanding of the human health risks of mercury. Ambio. 2023;52(5):877-96.14. Budnik LT, Casteleyn L. Mercury pollution in modern times and its socio-medical consequences. Science of the Total Environment. 2019;654:720-34.15. Zafar A, Javed S, Akram N, Naqvi SAR. Health risks of mercury. Mercury toxicity mitigation: sustainable nexus approach: Springer; 2024. p. 67-92.16. Wang J, Xie Q, Xiang Y, Xue J, Jiang T, Zhang C, et al. Anthropogenic activities enhance mercury methylation in sediments of a multifunctional lake: Evidence from dissolved organic matter and mercury-methylating microorganisms. Journal of Hazardous Materials. 2024;466:133505.17. Ali H, Khan E, Ilahi I. Environmental chemistry and ecotoxicology of hazardous heavy metals: environmental persistence, toxicity, and bioaccumulation. Journal of chemistry. 2019;2019(1):6730305.18. Kumar A, Kumar V, Bakshi P, Parihar RD, Radziemska M, Kumar R. Mercury in the natural environment: Biogeochemical cycles and associated health risks. Journal of Geochemical Exploration. 2024;267:107594.19. Saiz-Lopez A, Cuevas CA, Acuña AU, Añel JA, Mahajan AS, de la Torre L, et al. Role of the stratosphere in the global mercury cycle. Science Advances. 2025;11(2):eads1459.20. Miller HR, Driscoll CT, Hinckley E-LS. Mercury cycling in the US Rocky Mountains: a review of past research and future priorities. Biogeochemistry. 2024;167(1):1-20.21. Ray S, Vashishth R, Mukherjee AG, Gopalakrishnan AV, Sabina EP. Mercury in the environment: Biogeochemical transformation, ecological impacts, human risks, and remediation strategies. Chemosphere. 2025;381:144471.22. Du J, Yuan Y, Li J, Zhang S, Ren Y. Preliminary study on mercury pollution affecting soil bacteria near a mercury mining area. Frontiers in Microbiology. 2025;16:1539059.23. Lim SH, Kim Y, Motta LC, Yang EJ, Rhee TS, Hong JK, et al. Near surface oxidation of elemental mercury leads to mercury exposure in the Arctic Ocean biota. Nature Communications. 2024;15(1):7598.24. Geyman BM, Thackray CP, Jacob DJ, Sunderland EM. Impacts of volcanic emissions on the global biogeochemical mercury cycle: Insights from satellite observations and chemical transport modeling. Geophysical Research Letters. 2023;50(21):e2023GL104667.25. Okeke TE, Ewuim SC, Uhuo C, Ononye BU, Akunne CE, Okafor KP. Evaluating the ecological consequences of heavy metal contamination in soil induced by spent engine oil and palm oil mill effluents for sustainable development. Sustain Soc Dev. 2024;2(2):2410.26. Janssen SE, Kotalik CJ, Willacker JJ, Tate MT, Pritz CMF, Nelson SJ, et al. Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae. Environmental Science & Technology. 2024;58(30):13444-55.27. Zhang Y, Zhang P, Song Z, Huang S, Yuan T, Wu P, et al. An updated global mercury budget from a coupled atmosphere-land-ocean model: 40% more re-emissions buffer the effect of primary emission reductions. One Earth. 2023;6(3):316-25.28. Davies TC. An updated review of the salient geomedical aspects of mercury for enhancement of data quality in simulation modelling and other prognostic applications: Africa case descriptions. Frontiers in Analytical Science. 2023;3:1069678.29. Yang L, Yu B, Han D, Zhang K, Liu H, Xiao C, et al. Decoding the marine biogeochemical cycling of mercury by stable mercury isotopes. Critical Reviews in Environmental Science and Technology. 2023;53(22):1935-56.30. Bieser J, Amptmeijer D, Daewel U, Kuss J, Soerensen AL, Schrum C. The 3D biogeochemical marine mercury cycling model MERCY v2. 0–linking atmospheric Hg to methyl mercury in fish. Geoscientific Model Development Discussions. 2022;2022:1-59.31. Amos HM, Zhang Y. Global biogeochemical cycling of mercury: a critical review. Chem Rev. 2015;115:3760-808.32. Wu Y-S, Osman AI, Hosny M, Elgarahy AM, Eltaweil AS, Rooney DW, et al. The toxicity of mercury and its chemical compounds: molecular mechanisms and environmental and human health implications: a comprehensive review. Acs Omega. 2024;9(5):5100-26.33. Driscoll CT, Mason RP, Chan HM. Mercury as a global pollutant: sources, pathways, and effects. Environ Sci Technol. 2019;53:10548-66.34. Obrist D, Kirk JL, Zhang L. A review of global mercury cycles and transformations. Nat Rev Earth Environ. 2021;2:380-401.35. Toda E, Have Ct, Pacyna JM. The Minamata Convention: A tool for global regulation of mercury pollution. Chemistry International. 2020;42(4):10-8.36. Parks JM, Johs A, Podar M, Bridou R, Hurt Jr RA, Smith SD, et al. The genetic basis for bacterial mercury methylation. Science. 2013;339(6125):1332-5.37. Gilmour CC, Podar M, Bullock AL, Graham AM, Brown SD, Somenahally AC, et al. Mercury methylation by novel microorganisms from new environments. Environmental science & technology. 2013;47(20):11810-20.38. Bravo AG, Cosio C. Biotic formation of methylmercury: A bio–physico–chemical conundrum. Limnology and Oceanography. 2020;65(5):1010-27.39. Li Y, Chen L, Liang S, Zhou H, Liu Y-R, Zhong H, et al. Looping mercury cycle in global environmental–economic system modeling. Environmental Science & Technology. 2022;56(5):2861-79.40. Gustin MS, Obrist D. Atmospheric chemistry and transport of mercury. Environ Sci Technol. 2020;54:8509-32.41. Chen CY, Evers DC. Global mercury impact synthesis: Processes in the Southern Hemisphere. Ambio. 2023;52(5):827-32.42. Schartup AT, Thackray CP, Qureshi A, Dassuncao C, Gillespie K, Hanke A, et al. Climate change and overfishing increase neurotoxicant in marine predators. Nature. 2019;572(7771):648-50.43. Li F, Liu W, Hu C, Tang M, Zhang Y, Ho HC, et al. Global association of greenness exposure with risk of nervous system disease: A systematic review and meta-analysis. Science of the Total Environment. 2023;877:162773.44. Wang H, Li T, Wang G, Peng Y, Zhang Q, Wang X, et al. Significant spatiotemporal changes in atmospheric particulate mercury pollution in China: Insights from meta-analysis and machine-learning. Science of the Total Environment. 2024;955:177184.45. Biester HU, Rodríguez MP, Calean A, Sindlev MB, Lüskow F, Stimac I, et al. Dissolved and particulate methylated mercury in a highly productive area of the Southern Ocean. Authorea Preprints. 2025.46. Sun S, Zhang Y, Li J. Westerlies-driven transboundary transport of atmospheric mercury to the Tibetan Plateau. Sci Total Environ. 2024;992:162435.47. Zhang Y, Song Z, Huang S, Zhang P, Peng Y, Wu P, et al. Global health effects of future atmospheric mercury emissions. Nature Communications. 2021;12(1):3035.48. Barkay T, Gu B. Demethylation─ the other side of the mercury methylation coin: a critical review. ACS Environmental Au. 2021;2(2):77-97.49. Calleja JG. Characterization of mercury (Hg) chemical species and biological ligands produced by phytoplankton: Université de Pau et des Pays de l’Adour; 2022.50. Gojkovic Z, Simansky S, Sanabria A, Márová I, Garbayo I, Vílchez C. Interaction of naturally occurring phytoplankton with the biogeochemical cycling of mercury in aquatic environments and its effects on global Hg pollution and public health. Microorganisms. 2023;11(8):2034.51. Arias AH, Botte SE. Coastal and deep ocean pollution: crc Press London; 2020.52. Selin H, Keane SE, Wang S, Selin NE, Davis K, Bally D. Linking science and policy to support the implementation of the Minamata Convention on Mercury. Ambio. 2018;47(2):198-215.53. Bank MS. The mercury science-policy interface: History, evolution and progress of the Minamata Convention. Science of The Total Environment. 2020;722:137832.54. Gustin MS, Evers DC, Bank MS, Hammerschmidt CR, Pierce A, Basu N, et al. Importance of integration and implementation of emerging and future mercury research into the Minamata Convention. ACS Publications; 2016.55. Basu M. Impact of Mercury and Its Toxicity. Mercury Toxicity: Challenges and Solutions. 2023:95.56. Kumar V, Umesh M, Shanmugam MK, Chakraborty P, Duhan L, Gummadi SN, et al. A retrospection on mercury contamination, bioaccumulation, and toxicity in diverse environments: current insights and future prospects. Sustainability. 2023;15(18):13292.57. Dórea JG. Low-dose Thimerosal (ethyl-mercury) is still used in infantsvaccines: Should we be concerned with this form of exposure? Journal of Trace Elements in Medicine and Biology. 2018;49:134-9.58. Wu Y, Mao Y, Liu G, Li Y, Guo Y, Liu Y, et al. Analytical methods, occurrence, fate, and toxicity of ethylmercury in the environment: review and outlook. Reviews of Environmental Contamination and Toxicology. 2023;261(1):9.59. Nittler LR, Chabot NL, Grove TL, Peplowski PN. The chemical composition of Mercury. Mercury: The view after MESSENGER. 2018;21:30-51.60. Montoya AJ, Lena JC, Windmöller CC. Adsorption of gaseous elemental mercury on soils: Influence of chemical and/or mineralogical characteristics. Ecotoxicology and Environmental Safety. 2019;170:98-106.61. Padalkar PP, Chakraborty P, Chennuri K, Jayachandran S, Sitlhou L, Nanajkar M, et al. Molecular characteristics of sedimentary organic matter in controlling mercury (Hg) and elemental mercury (Hg0) distribution in tropical estuarine sediments. Science of the total environment. 2019;668:592-601.62. García-Sánchez M, Klouza M, Holečková Z, Tlustoš P, Száková J. Organic and inorganic amendment application on mercury-polluted soils: effects on soil chemical and biochemical properties. Environmental Science and Pollution Research. 2016;23(14):14254-68.63. Li J, Li X, Alsaedi A, Hayat T, Chen C. Synthesis of highly porous inorganic adsorbents derived from metal-organic frameworks and their application in efficient elimination of mercury (II). Journal of colloid and interface science. 2018;517:61-71.64. Peng X, Yang Y, Yang S, Li L, Song L. Recent advance of microbial mercury methylation in the environment. Applied Microbiology and Biotechnology. 2024;108(1):235.65. Aschner M, Syversen T. Methylmercury: recent advances in the understanding of its neurotoxicity. Therapeutic drug monitoring. 2005;27(3):278-83.66. Pacyna JM. Recent advances in mercury research. The Science of the total environment. 2020;738:139955.67. Afzal S, Abdul Manap AS, Attiq A, Albokhadaim I, Kandeel M, Alhojaily SM. From imbalance to impairment: the central role of reactive oxygen species in oxidative stress-induced disorders and therapeutic exploration. Frontiers in pharmacology. 2023;14:1269581.68. Azevedo LF, Karpova N, Rocha BA, Barbosa Junior F, Gobe GC, Hornos Carneiro MF. Evidence on neurotoxicity after intrauterine and childhood exposure to organomercurials. International Journal of Environmental Research and Public Health. 2023;20(2):1070.69. Khalid M, Abdollahi M. Epigenetic modifications associated with pathophysiological effects of lead exposure. Journal of Environmental Science and Health, Part C. 2019;37(4):235-87.70. Bjørklund G, Pivina L, Dadar M, Semenova Y, Chirumbolo S, Aaseth J. Mercury exposure, epigenetic alterations and brain tumorigenesis: a possible relationship? Current Medicinal Chemistry. 2020;27(39):6596-610.71. Krata A, Vassileva E, Bulska E. Reference measurements for total mercury and methyl mercury content in marine biota samples using direct or species-specific isotope dilution inductively coupled plasma mass spectrometry. Talanta. 2016;160:562-9.72. Stern AH. A revised probabilistic estimate of the maternal methyl mercury intake dose corresponding to a measured cord blood mercury concentration. Environmental health perspectives. 2005;113(2):155-63.73. Organization WH. Guidelines for drinking-water quality: World health organization; 2004.74. Notariale R, Infantino R, Palazzo E, Manna C. Erythrocytes as a model for heavy metal-related vascular dysfunction: the protective effect of dietary components. International journal of molecular sciences. 2021;22(12):6604.75. Ellwanger JH, Ziliotto M, Chies JAB. Toxicogenomics of Arsenic, Lead and Mercury: The Toxic Triad. Pollutants. 2025;5(3):18.76. Park J-D, Zheng W. Human exposure and health effects of inorganic and elemental mercury. Journal of preventive medicine and public health. 2012;45(6):344.77. Liu Y, Wang Y. Elemental mercury removal from flue gas using heat and Co2+/Fe2+ coactivated oxone oxidation system. Chemical Engineering Journal. 2018;348:464-75.78. Xing Y, Yan B, Lu P, Cui X, Li L, Wang M. Purification of Hg0 from flue gas by wet oxidation method and its mechanism: a review. Environmental Science and Pollution Research. 2017;24(34):26310-23.79. Chen J, Gu Z, Perez-Aguilar JM, Luo Y, Tian K, Luo Y. Molecular dynamics simulations reveal efficient heavy metal ion removal by two-dimensional Cu-THQ metal-organic framework membrane. Scientific Reports. 2025;15(1):199.80. Thévenod F, Fels J, Lee W-K, Zarbock R. Channels, transporters and receptors for cadmium and cadmium complexes in eukaryotic cells: myths and facts. Biometals. 2019;32(3):469-89.81. Chevalier RL. The proximal tubule is the primary target of injury and progression of kidney disease: role of the glomerulotubular junction. American Journal of Physiology-Renal Physiology. 2016;311(1):F145-F61.82. Spiller HA. Rethinking mercury: the role of selenium in the pathophysiology of mercury toxicity. Clinical toxicology. 2018;56(5):313-26.83. Man Y, Wang B, Wang J, Cai K, Rinklebe J, Zhang L, et al. New insights into mehg accumulation in rice (Oryza sativa L.): evidence from cysteine. Environmental Science & Technology. 2024;58(13):5942-51.84. Gaccioli F, Aye IL, Roos S, Lager S, Ramirez VI, Kanai Y, et al. Expression and functional characterisation of System L amino acid transporters in the human term placenta. Reproductive Biology and Endocrinology. 2015;13(1):57.85. Pan J, Li X, Wei Y, Ni L, Xu B, Deng Y, et al. Advances on the influence of methylmercury exposure during neurodevelopment. Chemical Research in Toxicology. 2022;35(1):43-58.86. Farina M, Aschner M. Glutathione antioxidant system and methylmercury-induced neurotoxicity: An intriguing interplay. Biochimica et Biophysica Acta (BBA)-General Subjects. 2019;1863(12):129285.87. Benhar M. Roles of mammalian glutathione peroxidase and thioredoxin reductase enzymes in the cellular response to nitrosative stress. Free Radical Biology and Medicine. 2018;127:160-4.88. Ahmad S, Mahmood R. Mercury chloride toxicity in human erythrocytes: enhanced generation of ROS and RNS, hemoglobin oxidation, impaired antioxidant power, and inhibition of plasma membrane redox system. Environmental Science and Pollution Research. 2019;26(6):5645-57.89. Tejchman K, Kotfis K, Sieńko J. Biomarkers and mechanisms of oxidative stress—last 20 years of research with an emphasis on kidney damage and renal transplantation. International journal of molecular sciences. 2021;22(15):8010.90. Ahmad S, Khan H, Shahab U, Rehman S, Rafi Z, Khan MY, et al. Protein oxidation: an overview of metabolism of sulphur containing amino acid, cysteine. Front Biosci (Schol Ed). 2017;9(1):71-87.91. Sharma K, Devi P, Kumar P, Dey A, Dwivedi P. Hazardous phytotoxic nature of reactive oxygen species in agriculture. Reactive oxygen species: Prospects in plant metabolism: Springer; 2023. p. 135-46.92. Iqbal MJ, Kabeer A, Abbas Z, Siddiqui HA, Calina D, Sharifi-Rad J, et al. Interplay of oxidative stress, cellular communication and signaling pathways in cancer. Cell Communication and Signaling. 2024;22(1):7.93. Chaudhary MR, Chaudhary S, Sharma Y, Singh TA, Mishra AK, Sharma S, et al. Aging, oxidative stress and degenerative diseases: mechanisms, complications and emerging therapeutic strategies. Biogerontology. 2023;24(5):609-62.94. Orozco-Hernández JM, Gómez-Oliván LM, Elizalde-Velázquez GA, Rosales-Pérez KE, Cardoso-Vera JD, Heredia-García G, et al. Fluoxetine-induced neurotoxicity at environmentally relevant concentrations in adult zebrafish Danio rerio. Neurotoxicology. 2022;90:121-9.95. Reis AT, Davidson CM, Vale C, Pereira E. Overview and challenges of mercury fractionation and speciation in soils. TrAC Trends in Analytical Chemistry. 2016;82:109-17.96. Humaira KT. Sources and effect of mercury on human health: a review. 2016.97. Ke T, Tinkov AA, Skalny AV, Santamaria A, Rocha JB, Bowman AB, et al. Epigenetics and methylmercury-induced neurotoxicity, evidence from experimental studies. Toxics. 2023;11(1):72.98. Aljerf L, Almasri N. Mercury toxicity: ecological features of organic phase of mercury in biota-Part I. Archives of Organic and Inorganic Chemical Sciences. 2018;3(3):324-31.99. Novo JP, Martins B, Raposo RS, Pereira FC, Oriá RB, Malva JO, et al. Cellular and molecular mechanisms mediating methylmercury neurotoxicity and neuroinflammation. International journal of molecular sciences. 2021;22(6):3101.100. Zupančič M, Šušteršič M, Bavec Š, Gosar M. Oral and inhalation bioaccessibility of potentially toxic elements in household dust from former Hg mining district, Idrija, Slovenia. Environmental Geochemistry and Health. 2021;43(9):3505-31.101. Cegarra-Navarro J-G, Bolisani E, Cepeda-Carrión G. Linking good counter-knowledge with bad counter knowledge: the impact of evasive knowledge hiding and defensive reasoning. Journal of Knowledge Management. 2022;26(8):2038-60.102. Uddin S, Khanom S, Islam MR. Environmental mercury exposure—a continuing challenge. Mercury toxicity: challenges and solutions: Springer; 2023. p. 3-32.103. Kidd K, Clayden M, Jardine T. Bioaccumulation and biomagnification of mercury through food webs. Wiley Online Library; 2012. p. 455-500.104. Kozak N. Mercury accumulation in fish and lake food webs: From molecules to ecosystems. 2023.105. Doroudian M. Application of Metallomics Techniques to Probe the Biotransformation of Toxic Metals in the Bloodstream-Organ System. 2024.106. Ye M, Xiang Y, Gong J, Wang X, Mao Z, Liu Z. Monitoring Hg2+ and MeHg+ poisoning in living body with an activatable near-infrared II fluorescence probe. Journal of Hazardous Materials. 2023;445:130612.107. Zalups RK, Lash LH. Interactions between glutathione and mercury in the kidney, liver, and blood. Toxicology of Metals, Volume I: CRC Press; 2023. p. 145-63.108. Basu M. Impact of mercury and its toxicity on health and environment: a general perspective. mercury toxicity: Challenges and solutions: Springer; 2023. p. 95-139.109. Bilge S. Neurotoxicity, Types, Clinical Manifestations, Diagnosis and. Neurotoxicity: New Advances. 2022:173.110. Gogia N, Kumar P. Mercury poisoning: effects on the central nervous system. Heavy Metal Toxicity and Neurodegeneration: Elsevier; 2025. p. 55-76.111. Gao Z, Wu N, Du X, Li H, Mei X, Song Y. Toxic nephropathy secondary to chronic mercury poisoning: clinical characteristics and outcomes. Kidney International Reports. 2022;7(6):1189-97.112. Tarnowska M. Evaluation of skin absorption of inorganic ions with regard to their physicochemical properties: Université de Lyon; 2019.113. Shahid M, Khalid S, Bibi I, Bundschuh J, Niazi NK, Dumat C. A critical review of mercury speciation, bioavailability, toxicity and detoxification in soil-plant environment: Ecotoxicology and health risk assessment. Science of the total environment. 2020;711:134749.114. Jeste SS. Neurodevelopmental behavioral and cognitive disorders. CONTINUUM: Lifelong Learning in Neurology. 2015;21(3):690-714.115. Dos Santos AA, Hort MA, Culbreth M, López-Granero C, Farina M, Rocha JB, et al. Methylmercury and brain development: A review of recent literature. Journal of trace elements in medicine and biology. 2016;38:99-107.116. Stenzler B. A Conceptual Framework Describing Mercury Bioavailability to Microbes Through Redox Zones: Université d’Ottawa/University of Ottawa; 2022.117. Amin S, Khan S, Sarwar T, Nawab J, Khan MA. Mercury methylation and its accumulation in rice and paddy soil in degraded lands: A critical review. Environmental Technology & Innovation. 2021;23:101638.118. Zhao W, Gan R, Xian B, Wu T, Wu G, Huang S, et al. Overview of methylation and demethylation mechanisms and influencing factors of mercury in water. Toxics. 2024;12(10):715.119. Gojkovic Z, Skrobonja A, Funk C, Garbayo I, Vílchez C. The role of microalgae in the biogeochemical cycling of methylmercury (MeHg) in aquatic environments. Phycology. 2022;2(3):344-62.120. Oros A. Bioaccumulation and trophic transfer of heavy metals in marine fish: Ecological and ecosystem-level impacts. Journal of Xenobiotics. 2025;15(2):59.121. Si L, Branfireun BA, Fierro J. Chemical oxidation and reduction pathways of mercury relevant to natural waters: a review. Water. 2022;14(12):1891.122. Ma M, Du H, Wang D. Mercury methylation by anaerobic microorganisms: a review. Critical Reviews in Environmental Science and Technology. 2019;49(20):1893-936.123. Ali S, Mansha M, Baig N, Khan SA. Recent trends and future perspectives of emergent analytical techniques for mercury sensing in aquatic environments. The Chemical Record. 2022;22(7):e202100327.124. Soetan O, Nie J, Viteritto M, Feng H. Evaluation of sediment dredging in remediating toxic metal contamination—a systematic review. Environmental Science and Pollution Research. 2023;30(27):69837-56.125. Beckers F, Rinklebe J. Cycling of mercury in the environment: Sources, fate, and human health implications: A review. Critical Reviews in Environmental Science and Technology. 2017;47(9):693-794.126. Schlemmer L, Hohenegger C. Modifications of the atmospheric moisture field as a result of cold‐pool dynamics. Quarterly Journal of the Royal Meteorological Society. 2016;142(694):30-42.127. Douglas TA, Loseto LL, Macdonald RW, Outridge P, Dommergue A, Poulain A, et al. The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review. Environmental chemistry. 2012;9(4):321-55.128. Barbieri F, Zavattini B, Marchetto D, de Ferri L, Pojana G, editors. Surface Sea Water Monitoring of Micro-and Mesoplastics in a Northern Adriatic Coastal Area. 18 TH INTERNATIONAL CONFERENCE ON CHEMISTRY AND THE ENVIRONMENT-BOOK OF ABSTRACTS; 2023: European Chemical Society.129. Wang Y, Zhou C, Zhang H, Ma S, Lou Z, Raskin L, et al. Transformation, Transport, and Storage of Major Elements in Municipal Solid Waste Disposal Sites. 2024.130. Li Y, Gong X. Effects of dissolved organic matter on the bioavailability of heavy metals during microbial dissimilatory iron reduction: a review. Reviews of Environmental Contamination and Toxicology Volume 257. 2021:69-92.131. Mladenova EK, Dakova IG, Tsalev DL, Karadjova IB. Mercury determination and speciation analysis in surface waters. Central European Journal of Chemistry. 2012;10(4):1175-82.132. Skyllberg U. Chemical speciation of mercury in soil and sediment. Environmental chemistry and toxicology of mercury. 2012:219-58.133. Wang Y. Investigating the Microbial Mechanisms of Mercury Methylation: Community Composition and Biogeochemical Interactions 2025.134. Dieguez MdC, Arcagni M, Rizzo A, Perez Catán S, Soto Cárdenas C, Horvat M, et al. Mercury in aquatic systems of North Patagonia (Argentina): Sources, processes, and trophic transfer. Freshwaters and Wetlands of Patagonia: Ecosystems and Socioecological Aspects. 2022:163-94.135. Liu M, Zhou C, Zhang Q, Raymond PA, Li X, Mason RP, et al. Fish trawling and climate perturbations threaten the largest marine mercury sink. Nature Sustainability. 2025:1-14.136. Manceau A, Bustamante P, Richy E, Cherel Y, Janssen SE, Glatzel P, et al. Mercury speciation and stable isotopes in emperor penguins: First evidence for biochemical demethylation of methylmercury to mercury-dithiolate and mercury-tetraselenolate complexes. Journal of Hazardous Materials. 2025;485:136499.137. Ariya PA, Amyot M, Dastoor A, Deeds D, Feinberg A, Kos G, et al. Mercury physicochemical and biogeochemical transformation in the atmosphere and at atmospheric interfaces: A review and future directions. Chemical reviews. 2015;115(10):3760-802.138. Richard J-H. Mercury contaminated groundwater: speciation analysis, modeling, and remediation: Technische Universität Carolo-Wilhelmina zu Braunschweig; 2016.139. Wang Y, Huang Z, Sheng L, Ma Y. Effect of modified humic acid residue on the adsorption and passivation of Hg2+/Pb2+ in solution and soil. Journal of Molecular Liquids. 2023;377:121581.140. Shah V, Jacob DJ, Thackray CP, Wang X, Sunderland EM, Dibble TS, et al. Improved mechanistic model of the atmospheric redox chemistry of mercury. Environmental Science & Technology. 2021;55(21):14445-56.141. Beckers F. Mobilization, Methylation, and Ethylation of Mercury in Contaminated Floodplain Soils under Controlled Laboratory Redox Conditions as Influenced by Potential Immobilizing Agents as well as Mobilization of Mercury under Field Conditions: Dissertation, Wuppertal, Bergische Universität, 2019; 2019.142. Bigham GN, Murray KJ, Masue‐Slowey Y, Henry EA. Biogeochemical controls on methylmercury in soils and sediments: Implications for site management. Integrated environmental assessment and management. 2016;13(2):249-63.143. Gutensohn M, Schaefer JK, Yunda E, Skyllberg U, Bjorn E. The combined effect of Hg (II) speciation, thiol metabolism, and cell physiology on methylmercury formation by Geobacter sulfurreducens. Environmental Science & Technology. 2023;57(18):7185-95.144. Gilmour CC, Bullock AL, McBurney A, Podar M, Elias DA. Robust mercury methylation across diverse methanogenic Archaea. MBio. 2018;9(2):10.1128/mbio. 02403-17.145. Chen W, Yu Z, Yang X, Wang T, Li Z, Wen X, et al. Unveiling the role of dissolved organic matter on the Hg phytoavailability in biochar-amended soils. International Journal of Environmental Research and Public Health. 2023;20(4):3761.146. Balta I, Lemon J, Gadaj A, Cretescu I, Stef D, Pet I, et al. The interplay between antimicrobial resistance, heavy metal pollution, and the role of microplastics. Frontiers in Microbiology. 2025;16:1550587.147. Rao B, Simpson C, Lin H, Liang L, Gu B. Determination of thiol functional groups on bacteria and natural organic matter in environmental systems. Talanta. 2014;119:240-7.148. Lamborg CH, Hansel CM, Bowman KL, Voelker BM, Marsico RM, Oldham VE, et al. Dark reduction drives evasion of mercury from the ocean. Frontiers in Environmental Chemistry. 2021;2:659085.149. Graham AM. Dissolved organic matter interactions with mercury in the Florida Everglades. Mercury and the Everglades A Synthesis and Model for Complex Ecosystem Restoration: Volume II–Aquatic Mercury Cycling and Bioaccumulation in the Everglades: Springer; 2019. p. 87-108.150. Lin C, Yee N, Barkay T. Microbial transformations in the mercury cycle. Environmental chemistry and toxicology of mercury. 2012:155-91.151. Bravo AG, Peura S, Buck M, Ahmed O, Mateos-Rivera A, Herrero Ortega S, et al. Methanogens and iron-reducing bacteria: the overlooked members of mercury-methylating microbial communities in boreal lakes. Applied and environmental microbiology. 2018;84(23):e01774-18.152. Eltarahony M, Ibrahim E, Hegazy G, Sabry A. Microbial remediation of mercury: an overview. Mercury toxicity: Challenges and solutions. 2023:201-34.153. Qin A, Ran S, He T, Yin D, Xu Y. The effects of different soil component couplings on the methylation and bioavailability of mercury in soil. Toxics. 2023;11(11):942.154. Bargagli R, Rota E. Mercury biogeochemistry and biomagnification in the Mediterranean Sea: Current knowledge and future prospects in the context of climate change. Coasts. 2024;4(1):89-107.155. Wang Y, Wu P, Zhang Y. Climate-driven changes of global marine mercury cycles in 2100. Proceedings of the National Academy of Sciences. 2023;120(2):e2202488120.156. Gu B, Bian Y, Miller CL, Dong W, Jiang X, Liang L. Mercury reduction and complexation by natural organic matter in anoxic environments. Proceedings of the National Academy of Sciences. 2011;108(4):1479-83.157. Karuppasamy MB, Krishnan GG. Behaviour of Mercury Emissions, Biogeochemical Cycle, and. Bioremediation of Toxic Metal (loid) s. 2022:237.158. Zhang Y, Liu J, Ge Z, Ou C, Wei J, Liu H, et al. The binding effects and mechanisms of dissolved organic matter (DOM) on the fate of mercury in sludge anaerobic digestion combined with thermal hydrolysis. Water Research. 2024;259:121845.159. Mazrui NM, Jonsson S, Thota S, Zhao J, Mason RP. Enhanced availability of mercury bound to dissolved organic matter for methylation in marine sediments. Geochimica et Cosmochimica Acta. 2016;194:153-62.160. Mazrui NM. The Interaction of Mercury and Methylmercury with Reduced Sulfur: Implications for the Transformation of Mercury and Methylmercury in the Environment: University of Connecticut; 2016.161. Wu Q, Wang B, Hu H, Bravo AG, Bishop K, Bertilsson S, et al. Sulfate-reduction and methanogenesis are coupled to Hg (II) and MeHg reduction in rice paddies. Journal of hazardous materials. 2023;460:132486.162. Durand A, Maillard F, Foulon J, Chalot M. Interactions between Hg and soil microbes: microbial diversity and mechanisms, with an emphasis on fungal processes. Applied microbiology and biotechnology. 2020;104(23):9855-76.163. Selin H, Selin NE. Mercury stories: Understanding sustainability through a volatile element: MIT Press; 2020.164. Spurgeon DJ, Lahive E, Schultz CL. Nanomaterial transformations in the environment: effects of changing exposure forms on bioaccumulation and toxicity. Small. 2020;16(36):2000618.165. Hao R, Wang Z, Tang C, Gao Z, Yuan B, Yang W, et al. Reaction behavior and cost-effectiveness of halogen radicals in Hg0 removal: Performance, kinetics, and mechanism. ACS ES&T Engineering. 2020;1(1):66-75.166. Tatz MJ. Investigating the Relationship between Mercury, Urbanization, and Salmonella spp. in the American White Ibis (Eudocimus albus): University of Georgia; 2022.167. Zanuttini G. Mercury mobilization potential from highly contaminated alluvial soils. 2017.168. Mahato P, Saha S, Das P, Agarwalla H, Das A. An overview of the recent developments on Hg 2+ recognition. RSC advances. 2014;4(68):36140-74.169. by Rice IU. 11 Impact of Sulfur on Biogeochemical. Methylmercury Accumulation in Rice: Process and Regulation. 2024:184.170. Diano A. 3D printing of molecularly imprinted polymers for biomolecule removal: Politecnico di Torino; 2025.171. Gallorini A, Loizeau J-L. Mercury methylation in oxic aquatic macro-environments: a review. Journal of Limnology. 2021;80(2).172. Si L. Environmentally-relevant Photochemical Reactions of Oxidized Mercury Species with Selected Organics: McGill University; 2011.173. Aziz HA, Ariffin KS, Wang M-HS, Wang LK. Dredging and mining operations, management, and environmental impacts. Industrial Waste Engineering: Springer; 2024. p. 333-96.174. Chen J, Yang ZM. Mercury toxicity, molecular response and tolerance in higher plants. Biometals. 2012;25(5):847-57.175. Mei L, Zhu Y, Zhang X, Zhou X, Zhong Z, Li H, et al. Mercury-induced phytotoxicity and responses in upland cotton (Gossypium hirsutum L.) seedlings. Plants. 2021;10(8):1494.176. Liu Y, Liu G, Wang Z, Guo Y, Yin Y, Zhang X, et al. Understanding foliar accumulation of atmospheric Hg in terrestrial vegetation: progress and challenges. Critical Reviews in Environmental Science and Technology. 2022;52(24):4331-52.177. Sun X, Du H, Mao Q, Li P, Agathokleous E, Ma M. Mechanisms of Hg0 Uptake, Transport, Distribution, and Redistribution in the Leaves of Hg Bioindicator Tillandsia Usneoides (Spanish Moss). Environmental Science & Technology. 2025.178. Rubino FM. Toxicity of glutathione-binding metals: a review of targets and mechanisms. Toxics. 2015;3(1):20-62.179. Mao Q, Tang L, Ji W, Rennenberg H, Hu B, Ma M. Elevated CO2 and soil mercury stress affect photosynthetic characteristics and mercury accumulation of rice. Ecotoxicology and environmental safety. 2021;208:111605.180. Purna P. Phytomanagement of contaminated soils using hemp: fate and mobility of mercury: Ghent University; 2024.181. Das U, Rahman MA, Ela EJ, Lee K-W, Kabir AH. Sulfur triggers glutathione and phytochelatin accumulation causing excess Cd bound to the cell wall of roots in alleviating Cd-toxicity in alfalfa. Chemosphere. 2021;262:128361.182. Tran TAT, Dinh QT, Zhou F, Zhai H, Xue M, Du Z, et al. Mechanisms underlying mercury detoxification in soil–plant systems after selenium application: A review. Environmental Science and Pollution Research. 2021;28(34):46852-76.183. Roychoudhury A, Chakraborty S. Cellular and molecular phytotoxicity of Lead and Mercury. Cellular and Molecular Phytotoxicity of Heavy Metals: Springer; 2020. p. 373-87.184. Ameen F, Mumtaz S, Ali B, Hussain I, Hafeez A, Gul A, et al. The impact of Cu-polluted and organic soil on the fibrous plant; insights into plant growth promotion, antioxidant defences system, and oxidative stress. Functional Plant Biology. 2023;50(8):623-32.185. Liu G, Cai Y, O’Driscoll N. Environmental chemistry and toxicology of mercury: John Wiley & Sons; 2011.186. Moe LA. Amino acids in the rhizosphere: from plants to microbes. American journal of botany. 2013;100(9):1692-705.187. Angon PB, Islam MS, Das A, Anjum N, Poudel A, Suchi SA. Sources, effects and present perspectives of heavy metals contamination: Soil, plants and human food chain. Heliyon. 2024;10(7).188. Rajendran S, Kamaludeen SPB, Subramanian A. Antioxidant defense mechanism in plants exposed to mercury toxicity: response, tolerance and remediation. Mercury toxicity mitigation: sustainable nexus approach: Springer; 2024. p. 225-45.189. Chen X, Yu B, Wang X, Zhu R, Zhang L. The uptake and in-vivo migration of Hg by plants: A critical review. Reviews in Environmental Science and Bio/Technology. 2025;24(1):145-65.190. Franić M, Galić V. As, cd, Cr, Cu, Hg: Physiological implications and toxicity in plants. Plant Metallomics and Functional Omics: A System-Wide Perspective: Springer; 2019. p. 209-51.191. Sarafian TA. Methylmercury-induced generation of free radicals: biological implications. Metal ions in biological systems. 2018:415-44.192. Rupa SA, Patwary MAM, Matin MM, Ghann WE, Uddin J, Kazi M. Interaction of mercury species with proteins: towards possible mechanism of mercurial toxicology. Toxicology research. 2023;12(3):355-68.193. Flora SJ. Structural, chemical and biological aspects of antioxidants for strategies against metal and metalloid exposure. Oxidative medicine and cellular longevity. 2009;2(4):191-206.194. de Maria MB. Mass spectrometry investigations of interactions of thiols and selenols with mercury and gold compounds: Université de Pau et des Pays de l’Adour; 2023.195. Wang F, Lemes M, Khan M. Metallomics of mercury: Role of thiol-and selenol-containing biomolecules. Environmental chemistry and toxicology of mercury. 2012:517-44.196. Barbosa NV, Nogueira CW, Nogara PA, de Bem AF, Aschner M, Rocha JB. Organoselenium compounds as mimics of selenoproteins and thiol modifier agents. Metallomics. 2017;9(12):1703-34.197. Salbitani G, Maresca V, Cianciullo P, Bossa R, Carfagna S, Basile A. Non-protein thiol compounds and antioxidant responses involved in bryophyte heavy-metal tolerance. International Journal of Molecular Sciences. 2023;24(6):5302.198. Sandhi A, Siddique AB, Vithanage M. Mercury Toxicity: Plant Response and Tolerance. Heavy Metal Toxicity and Tolerance in Plants: A Biological, Omics, and Genetic Engineering Approach. 2023:349-71.199. Dai Z-H, Guan D-X, Bundschuh J, Ma LQ. Roles of phytohormones in mitigating abiotic stress in plants induced by metal (loid) s As, Cd, Cr, Hg, and Pb. Critical Reviews in Environmental Science and Technology. 2023;53(13):1310-30.200. Ahmad J, Ali AA, Iqbal M, Ahmad A, Qureshi MI. Proteomics of mercury-induced responses and resilience in plants: A review. Environmental Chemistry Letters. 2022;20(5):3335-55.201. Ahmad J, Ali AA, Iqbal M, Qureshi MI. Mercury-induced changes in plant proteomes. Authorea Preprints. 2024.202. Shukla T, Khare R, Kumar S, Lakhwani D, Sharma D, Asif MH, et al. Differential transcriptome modulation leads to variation in arsenic stress response in Arabidopsis thaliana accessions. Journal of hazardous materials. 2018;351:1-10.203. Zhou J, Obrist D, Dastoor A, Jiskra M, Ryjkov A. Vegetation uptake of mercury and impacts on global cycling. Nature Reviews Earth & Environment. 2021;2(4):269-84.204. Onyido I, Norris AR, Buncel E. Biomolecule− mercury interactions: Modalities of DNA base− mercury binding mechanisms. remediation strategies. Chemical reviews. 2004;104(12):5911-30.205. Parida L, Patel TN. Systemic impact of heavy metals and their role in cancer development: a review. Environmental Monitoring and Assessment. 2023;195(6):766.206. Crespo-López ME, Macêdo GL, Pereira SI, Arrifano GP, Picanco-Diniz DL, do Nascimento JLM, et al. Mercury and human genotoxicity: critical considerations and possible molecular mechanisms. Pharmacological research. 2009;60(4):212-20.207. Pawlaczyk A, Maćkiewicz E, Szynkowska MI. Speciation of trace elements and its importance in environmental and biomedical sciences. Recent Advances in Trace Elements. 2018:501-43.208. Bajger G, Konieczka P, Namieśnik J. Speciation of trace element compounds in samples of biota from marine ecosystems. Chemical Speciation & Bioavailability. 2011;23(3):125-42.209. Gomez-Eyles JL, Yupanqui C, Beckingham B, Riedel G, Gilmour C, Ghosh U. Evaluation of biochars and activated carbons for in situ remediation of sediments impacted with organics, mercury, and methylmercury. Environmental science & technology. 2013;47(23):13721-9.210. Liu D, Li B, Wu J, Liu Y. Photocatalytic oxidation removal of elemental mercury from flue gas. A review. Environmental Chemistry Letters. 2020;18(2):417-31.211. Tiodar ED, Văcar CL, Podar D. Phytoremediation and microorganisms-assisted phytoremediation of mercury-contaminated soils: challenges and perspectives. International Journal of Environmental Research and Public Health. 2021;18(5):2435.212. Masarovičová E, Kráľová K. Woody species in phytoremediation applications for contaminated soils. Phytoremediation: Management of Environmental Contaminants, Volume 6: Springer; 2019. p. 319-73.213. Dauda IO. Phytoremediation potential of sweet sorghum in mercury-contaminated soil: University of South Africa (South Africa); 2020.214. Rusinowski S, Krzyżak J, Sitko K, Kalaji H, Jensen E, Pogrzeba M. Cultivation of C4 perennial energy grasses on heavy metal contaminated arable land: Impact on soil, biomass, and photosynthetic traits. Environmental Pollution. 2019;250:300-11.215. Zhang T. The use of macrophytes for heavy metal pollution control in urban wetlands: Middlesex Polytechnic; 2025.216. Greger M. Aquatic Macrophytes. Metals in the Environment: Analysis by Biodiversity. 2001:259.217. Mbanga O. Evaluation of mercury accumulation and biotransportation in wetland plants affected by gold mining and industrial activities: University of the Witwatersrand, Johannesburg (South Africa); 2017.218. Santacoloma-Londono S, Rivera-Pedraza MC, Orejuela-Viveros BP, Buitrago-González ME, Martínez-Martina MA, Rodríguez-Correa AM, et al. Optimization of the Efficiency of Mercury Phytoremediation with Eichhornia Crassipes and Lemna Minor in Water Contaminated by Gold Mining. Polish Journal of Environmental Studies. 2025.219. Shirinpur-Valadi A, Hatamzadeh A, Sedaghathoor S. Study of the accumulation of contaminants by Cyperus alternifolius, Lemna minor, Eichhornia crassipes, and Canna× generalis in some contaminated aquatic environments. Environmental Science and Pollution Research. 2019;26(21):21340-50.220. Monroy-Licht A, Méndez-Cuadro D, Olivero-Verbel J. Elemental mercury accumulation in Eichhornia crassipes (Mart.) Solms-Laubach. Environmental Science and Pollution Research. 2023;30(4):9898-913.221. Raj D, Kumar A, Maiti SK. Brassica juncea (L.) Czern.(Indian mustard): a putative plant species to facilitate the phytoremediation of mercury contaminated soils. International Journal of Phytoremediation. 2020;22(7):733-44.222. Makarova AS, Nikulina E, Fedotov P. Induced phytoextraction of mercury. Separation & Purification Reviews. 2022;51(2):174-94.223. Cao X, Wang X, Tong W, Gurajala HK, Lu M, Hamid Y, et al. Distribution, availability and translocation of heavy metals in soil-oilseed rape (Brassica napus L.) system related to soil properties. Environmental Pollution. 2019;252:733-41.224. Hien TTD, Mi NTT. Comparison of sunflower mv-005 and vetiver grass in soil decontamination and evaluation of the effective microorganisms amendment in phytoremediation. Journal of Science Technology and Food. 2021;21(2):53-61.225. Hidayat A, Wahyuningsih E, Indriyatno I. Effect of Compost and NPK Fertilizer on Mercury (Hg) Absorption by Vetiver (Vetiveria zizanioides L.) on Gold Tailings Media in Seloto Village, Taliwang District, West Sumbawa Regency. East Asian Journal of Multidisciplinary Research. 2025;4(9):4727-36.226. Leudo AM, Cruz Y, Montoya-Ruiz C, Delgado MdP, Saldarriaga JF. Mercury phytoremediation with Lolium perenne-Mycorrhizae in contaminated soils. Sustainability. 2020;12(9):3795.227. Li Y, Zhao J, Guo J, Liu M, Xu Q, Li H, et al. Influence of sulfur on the accumulation of mercury in rice plant (Oryza sativa L.) growing in mercury contaminated soils. Chemosphere. 2017;182:293-300.228. Tang Z, Fan F, Wang X, Shi X, Deng S, Wang D. Mercury in rice (Oryza sativa L.) and rice-paddy soils under long-term fertilizer and organic amendment. Ecotoxicology and Environmental Safety. 2018;150:116-22.229. Zhao R, Cao X, Li X, Li T, Zhang H, Cui X, et al. Ecological toxicity of Cd, Pb, Zn, Hg and regulation mechanism in Solanum nigrum L. Chemosphere. 2023;313:137447.230. Yang C, Qiu G, Xiaoli Q, Xu X, Pu S, Xu Z, et al. Uptake, Transfer, and Accumulation of Mercury in Pteris Vittata L. Under the Influence of Mercuric Chloride. Under the Influence of Mercuric Chloride.231. Roy D, Sreekanth D, Pawar D. Aquatic, Semi-Aquatic and Submerged Weeds. Biodegradation Technology of Organic and Inorganic Pollutants. 2022:195.232. Manier N, Deram A, Le Curieux F, Marzin D. Comparison between new wild plant Trifolium repens and Vicia faba on their sensitivity in detecting the genotoxic potential of heavy metal solutions and heavy metal-contaminated soils. Water, Air, and Soil Pollution. 2009;202(1):343-52.233. Singh H, Kumar D, Soni V. Copper and mercury induced oxidative stresses and antioxidant responses of Spirodela polyrhiza (L.) Schleid. Biochemistry and Biophysics Reports. 2020;23:100781.234. Ruamsin C, Sonjaroon W, Khumwan S, Thamchaipenet A, Roongsattham P. Comparative Physiological Responses of Lemna aequinoctialis and Spirodela polyrhiza to Mercury Stress: Implications for Biomonitoring and Phytoremediation. Plants. 2025;14(18):2859.235. Robles ME, Oh Y, Haque MT, Jeon M, Kim L-H. Soil Mercury Pollution in Nature-Based Solutions Across Various Land Uses: A Review of Trends, Treatment Outcomes, and Future Directions. Applied Sciences. 2025;15(12):6502.236. Begum S, Rath SK, Rath CC. Applications of microbial communities for the remediation of industrial and mining toxic metal waste: a review. Geomicrobiology Journal. 2022;39(3-5):282-93.237. Meng D, Song Z, Liu J, Ji L, Chen C, Wang C. Evaluating the Accumulation of Grain Mercury in Engineered Rice Lines Containing merA and merB Genes Under an Organic Mercury-Enriched Condition. Plants. 2024;14(1):66.238. Rahman MA, Kabir AH, Mandal A, Roy SK, Song Y, Ji HC, et al. Glutathione restores Hg-induced morpho-physiological retardations by inducing phytochelatin and oxidative defense in alfalfa. Biology. 2020;9(11):364.239. Naguib MM, El-Gendy AO, Khairalla AS. Microbial diversity of mer operon genes and their potential rules in mercury bioremediation and resistance. The Open Biotechnology Journal. 2018;12(1).240. Chandran P, Suresh S, Balasubramain B, Gangwar J, Raj AS, Aarathy U, et al. Biological treatment solutions using bioreactors for environmental contaminants from industrial waste water. Journal of Umm Al-Qura University for Applied Sciences. 2025;11(2):185-207.241. Raj D, Maiti SK. Sources, toxicity, and remediation of mercury: an essence review. Environmental monitoring and assessment. 2019;191(9):566.242. Liu J, Lu H, Wang H, Mo J, Deng Y. Mercury fractions transformation during sludge thermal treatment: implications for mercury release and stabilization in municipal sludge. Journal of Soils and Sediments. 2024;24(11):3750-9.243. Bard AJ, Parsons R, Jordan J. Zinc, Cadmium, and Mercury. Standard Potentials in Aqueous Solution: Routledge; 2017. p. 249-86.244. Chen Y, Yin Y, Shi J, Liu G, Hu L, Liu J, et al. Analytical methods, formation, and dissolution of cinnabar and its impact on environmental cycle of mercury. Critical Reviews in Environmental Science and Technology. 2017;47(24):2415-47.245. Azeem B. Converting Wastewater Sludge into Slow-Release Fertilizers via Biochar and Encapsulation Technologies. Applied Sciences. 2025;15(20):10954.246. Wang J. Elimination of Mercury Methylation in Elemental Sulfur-Reducing Bacteria-Enriched Sludge: Discovery, Mechanism Study, and Potential Application: Hong Kong University of Science and Technology (Hong Kong); 2021.247. Hou D, Gu Q, Ma F, O’Connell S. Life cycle assessment comparison of thermal desorption and stabilization/solidification of mercury contaminated soil on agricultural land. Journal of Cleaner Production. 2016;139:949-56.248. Ling L, Fan M, Wang B, Zhang R. Application of computational chemistry in understanding the mechanisms of mercury removal technologies: a review. Energy & Environmental Science. 2015;8(11):3109-33.249. Zhao T, Yu Z, Zhang J, Qu L, Li P. Low-thermal remediation of mercury-contaminated soil and cultivation of treated soil. Environmental Science and Pollution Research. 2018;25(24):24135-42.250. Sierra MJ, Millán R, López FA, Alguacil FJ, Cañadas I. Sustainable remediation of mercury contaminated soils by thermal desorption. Environmental Science and Pollution Research. 2016;23(5):4898-907.251. Park M-o, Kim M-H, Hong Y. The kinetics of mercury vaporization in soil during low-temperature thermal treatment. Geoderma. 2020;363:114150.252. Sommar JO, Shi X, Tang X, Sun G, Lin C-J, Feng X. Atmospheric mercury: recent advances in theoretical, computational, experimental, observational, and isotopic understanding to decipher its redox transformations in the upper and lower atmosphere and interactions with Earth surface reservoirs. Atmospheric Chemistry and Physics. 2025;25(19):12233-334.253. Gopakumar DA, Parameswaranpillai J, George JJ, CD MD. Nanomaterials for Air and Water Purification: John Wiley & Sons; 2024.254. Dickmann DI, Kuzovkina J. Poplars and willows of the world, with emphasis on silviculturally important species. Poplars and willows: Trees for society and the environment: CABI Wallingford UK; 2014. p. 8-91.255. Xie A, Wu W. Emerging nanosensor technologies for the rapid detection of heavy metal contaminants in agricultural soils. Analytical Methods. 2025.256. Usman MK, Saidu M, Usman G, Agboola PO, Onwuchekwa C, Onwuchekwa N, et al. Eco-Friendly Nanomaterials for Remediation of Microplastics and Heavy Metals in Wetland Ecosystems: Emerging Technologies and Environmental Considerations. African Journal of Environmental Sciences and Renewable Energy. 2025;20(1):54-86.257. Morari F, Dal Ferro N, Cocco E. Municipal wastewater treatment with Phragmites australis L. and Typha latifolia L. for irrigation reuse. Boron and heavy metals. Water, Air, & Soil Pollution. 2015;226(3):56.258. Hsu-Kim H, Eckley CS, Achá D, Feng X, Gilmour CC, Jonsson S, et al. Challenges and opportunities for managing aquatic mercury pollution in altered landscapes. Ambio. 2018;47(2):141-69.259. Khan F, Momtaz S, Abdollahi M. The relationship between mercury exposure and epigenetic alterations regarding human health, risk assessment and diagnostic strategies. Journal of Trace Elements in Medicine and Biology. 2019;52:37-47.260. Date SS, Parks JM, Rush KW, Wall JD, Ragsdale SW, Johs A. Kinetics of enzymatic mercury methylation at nanomolar concentrations catalyzed by HgcAB. Applied and environmental microbiology. 2019;85(13):e00438-19.261. Singh SB, Carroll-Portillo A, Lin HC. Desulfovibrio in the gut: the enemy within? Microorganisms. 2023;11(7):1772.262. Khan S, Galstyan H, Abbas M, Wenjing X. Advanced biotechnology strategies for detoxification of persistent organic pollutants and toxic elements in soil. Chemosphere. 2023;345:140519.263. Bobojonov KS, Umataliyevna UK, Asanaliyevna SZ, Muxsimovna AM, Mamadjanovna TF, Shavkatovna AM, et al. Priority toxic metals arsenic, cadmium, mercury, and lead in ecosystems: a review of sources, toxicity, and regulatory approaches. Chemical Review and Letters. 2025:883-902.264. Liu C-b, Zhang L, Wu Q, Qu G-b, Yin Y-g, Hu L-g, et al. Mutual detoxification of mercury and selenium in unicellular Tetrahymena. Journal of Environmental Sciences. 2018;68:143-50.265. Fuhrmann BC, Beutel MW, O’Day PA, Tran C, Funk A, Brower S, et al. Effects of mercury, organic carbon, and microbial inhibition on methylmercury cycling at the profundal sediment-water interface of a sulfate-rich hypereutrophic reservoir. Environmental Pollution. 2021;268:115853.266. Alqahtani MA. Modulation of Aryl Hydrocarbon Receptor-Regulated Genes by Methylmercury. 2025.267. Sharma K, Devi P, Dey SR, Kumar P. Mercury phytovolatilization: an overview of the mechanism and mitigation. Role of green chemistry in ecosystem restoration to achieve environmental sustainability. 2024:325-31.268. Alviz-Gazitua P, Durán RE, Millacura FA, Cárdenas F, Rojas LA, Seeger M. Cupriavidus metallidurans CH34 possesses aromatic catabolic versatility and degrades benzene in the presence of mercury and cadmium. Microorganisms. 2022;10(2):484.269. Golysheva AA, Litvinenko LV, Ivshina IB. Diversity of Mercury-Tolerant Microorganisms. Microorganisms. 2025;13(6):1350.270. Kotrba P. Transgenic approaches to enhance phytoremediation of heavy metal-polluted soils. Plant-based remediation processes: Springer; 2013. p. 239-71.271. Atashgahi S, Sánchez-Andrea I, Heipieper HJ, van der Meer JR, Stams AJ, Smidt H. Prospects for harnessing biocide resistance for bioremediation and detoxification. Science. 2018;360(6390):743-6.272. Younas H, Nazir A, Bareen Fe. From sources to solutions: integrated approaches for Cd, Hg, and Pb remediation-a comprehensive review. Plant and Soil. 2025;510(1):1-47.273. Förstner U. Inorganic sediment chemistry and elemental speciation. Sediments: CRC Press; 2020. p. 61-105.274. Robinson NJ, Winge DR. Copper metallochaperones. Annual review of biochemistry. 2010;79(1):537-62.275. Tait AJ. Novel Approaches to the Investigation and Remediation of the Environmental Impacts of Mercury in the Environment: The University of Manchester (United Kingdom); 2021.276. Suvarapu LN, Baek S-O. Recent studies on the speciation and determination of mercury in different environmental matrices using various analytical techniques. International Journal of Analytical Chemistry. 2017;2017(1):3624015.277. Filippidou M-K, Chatzandroulis S. Microfluidic devices for heavy metal ions detection: A review. Micromachines. 2023;14(8):1520.278. Amde M, Yin Y, Zhang D, Liu J. Methods and recent advances in speciation analysis of mercury chemical species in environmental samples: a review. Chemical Speciation & Bioavailability. 2016;28(1-4):51-65.279. Wang J, Shan Q, Liang X, Guan F, Zhang Z, Huang H, et al. Levels and human health risk assessments of heavy metals in fish tissue obtained from the agricultural heritage rice-fish-farming system in China. Journal of hazardous materials. 2020;386:121627.280. Sarker A, Kim J-E, Islam ARMT, Bilal M, Rakib MRJ, Nandi R, et al. Heavy metals contamination and associated health risks in food webs—a review focuses on food safety and environmental sustainability in Bangladesh. Environmental Science and Pollution Research. 2022;29(3):3230-45.281. Hu J, Li J, Qi J, Chen J. Highly selective and effective mercury (II) fluorescent sensors. New Journal of Chemistry. 2015;39(2):843-8.282. Hesabizadeh T. Selenium Nanoparticles Synthesized by Pulsed Laser Ablation in Liquids for Antimicrobial Applications: University of Arkansas at Little Rock; 2025.283. Berry N. Development of a Lightning Strike Simulator with In-Situ Loading: University of Washington; 2025.284. Kozachuk MS. Synchrotron Radiation Analysis of Daguerreotypes: Surface Characterization, Electrocleaning, and Preservation: The University of Western Ontario (Canada); 2019.285. Szymczyk A, Popiołek M, Krzemiński J, Olszewski M, Ziółkowski R, Malinowska E. Identification of medium-and mechanism-related pitfalls towards improved performance and applicability of electrochemical mercury (II) aptasensors. Microchimica Acta. 2024;191(4):189.286. Pramanik R. A review on fluorescent molecular probes for Hg2+ Ion detection: mechanisms, strategies, and future directions. ChemistrySelect. 2025;10(7):e202404525.287. Bollella P, Katz E. Biosensors—Recent advances and future challenges. Sensors. 2020;20(22):6645.288. Liu R, Li J, Salena BJ, Li Y. Aptamer and DNAzyme based colorimetric biosensors for pathogen detection. Angewandte Chemie International Edition. 2025;64(4):e202418725.289. Chen CY, Driscoll CT, Eagles-Smith CA, Eckley CS, Gay DA, Hsu-Kim H, et al. A critical time for mercury science to inform global policy. ACS Publications; 2018.290. Francisco López A, Heckenauer Barrón EG, Bello Bugallo PM. Contribution to understanding the influence of fires on the mercury cycle: Systematic review, dynamic modelling and application to sustainable hypothetical scenarios. Environmental Monitoring and Assessment. 2022;194(10):707.291. Patriarca M, Barlow N, Cross A, Hill S, Robson A, Taylor A, et al. Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages. Journal of Analytical Atomic Spectrometry. 2022;37(3):410-73.292. Karadjova I, Dakova I, Yordanova T, Vasileva P. Nanomaterials for elemental speciation. Journal of Analytical Atomic Spectrometry. 2016;31(10):1949-73.293. Mino L, Borfecchia E, Segura-Ruiz J, Giannini C, Martinez-Criado G, Lamberti C. Materials characterization by synchrotron x-ray microprobes and nanoprobes. Reviews of Modern Physics. 2018;90(2):025007.294. Shi Y, Li D-h, Zhang C, Wang Z-r, Wang Y-r, Chen R-k, et al. A selenium nanozyme: Light/mercury dual-enhanced oxidase mimicry for simultaneous ultra-sensitive detection and efficient removal of mercury ions, and superior photocatalytic bacterial disinfection. Water Research. 2025:123988.295. Bin Jardan YA, Mostafa AM, Barker J, Ali ABH, El-Wekil MM. Preparation of 6, 8-dithiooctanoic acid-functionalized copper nanoclusters with near-infrared emission: application for determination of melamine in food matrices. Journal of Cluster Science. 2025;36(4):134.296. Dekker AG, Pinnel N, Gege P, Briottet X, Peters S, Turpie KR, et al. Feasibility Study for an Aquatic Ecosystem Earth Observing System Version 1.2. Feasibility study for an aquatic ecosystem Earth observing system. 2018.297. Sodeno R. Analysis of the Minamata Convention on Mercury in the Context of Sustainable Development Goals (SDGs). Global Environmental Research. 2020.298. Selin H, Selin NE. From Stockholm to Minamata and beyond: Governing mercury pollution for a more sustainable future. One Earth. 2022;5(10):1109-25.299. Carocci A, Rovito N, Sinicropi MS, Genchi G. Mercury toxicity and neurodegenerative effects. Reviews of environmental contamination and toxicology. 2013:1-18.300. Ii T. Imagining Tōhoku: Perceptions and Policies of Postwar Rural Northeastern Japan: University of Hawai’i at Manoa; 2025.301. Uddin S, Khanom S, Islam MR. Mercury contamination in food—an overview. Mercury Toxicity: Challenges and Solutions. 2023:33-70.302. Guo Y, Lundebye A-K, Li N, Ergon Å, Pang S, Jiang Y, et al. Comparative assessment of food safety regulations and standards for arsenic, cadmium, lead, mercury and iodine in macroalgae used as food and feed in China and Europe. Trends in Food Science & Technology. 2023;141:104204.303. Burger J, Gochfeld M, Bunn A, Downs J, Jeitner C, Pittfield T, et al. Functional remediation components: a conceptual method of evaluating the effects of remediation on risks to ecological receptors. Journal of Toxicology and Environmental Health, Part A. 2016;79(21):957-68.304. Schwartz M, Smits K, Phelan T. Quantifying mercury use in artisanal and small-scale gold mining for the Minamata Convention on Mercury’s national action plans: Approaches and policy implications. Environmental Science & Policy. 2023;141:1-10.305. Galaz V. Global environmental governance, technology and politics: the Anthropocene gap. Global Environmental Governance, Technology and Politics: Edward Elgar Publishing; 2014.306. Gordon J, Quinton W, Branfireun B, Olefeldt D. Mercury and methylmercury biogeochemistry in a thawing permafrost wetland complex, Northwest Territories, Canada. Hydrological Processes. 2016;30(20):3627-38.307. Li C, Wu M, Tang W, Yu B, Saiz-Lopez A, Poulain A, et al. Aligning global mercury mitigation with climate action. Nature Communications. 2025;16(1):7826.308. Glasser F. Cements in radioactive waste disposal. 2013.309. Van Oijen M, Barcza Z, Confalonieri R, Korhonen P, Kröel-Dulay G, Lellei-Kovács E, et al. Incorporating biodiversity into biogeochemistry models to improve prediction of ecosystem services in temperate grasslands: Review and roadmap. Agronomy. 2020;10(2):259.310. Qiu H, Li T, Zhang B. The impact of climate change on the earth system and its simulation predictions: Progress, challenges, and future directions. Geographical Research Bulletin. 2024;3:231-46.311. Cao Z, Wang S, Luo P, Xie D, Zhu W. Watershed ecohydrological processes in a changing environment: Opportunities and challenges. Water. 2022;14(9):1502.312. Zevallos-Aliaga D, De Graeve S, Obando-Chávez P, Vaccari NA, Gao Y, Peeters T, et al. Highly sensitive whole-cell mercury biosensors for environmental monitoring. Biosensors. 2024;14(5):246.313. Fields CA, Borak J, Louis ED. Mercury-induced motor and sensory neurotoxicity: systematic review of workers currently exposed to mercury vapor. Critical reviews in toxicology. 2017;47(10):815-48. Information & Authors Information Version history V1 Version 1 29 October 2025 Peer review timeline Published Journal of Hazardous Materials Advances Version of Record 1 May 2026 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords mercury speciation methylmercury phytoremediation risk assessment toxicodynamic Authors Affiliations Naila Shah Kunming University of Science and Technology View all articles by this author Muhammad Awais Yunnan University View all articles by this author Mohammad Ali University of Swat View all articles by this author Haiyan Li [email protected] Kunming University of Science and Technology View all articles by this author Metrics & Citations Metrics Article Usage 456 views 178 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Naila Shah, Muhammad Awais, Mohammad Ali, et al. Speciation-Driven Toxicity and Remediation of Mercury: Mechanistic Insights and Policy Implications. Authorea . 29 October 2025. DOI: https://doi.org/10.22541/au.176177172.23880272/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. 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