Different Forms Of Mercury Research Articles

The Development of a Rapid, Cost-Effective, and Green Analytical Method for Mercury Speciation.

Mercury is a naturally occurring metal found in various inorganic and organic forms within the environment. Due to its high toxicity, there is global concern regarding human exposure to this element. The combination of high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS) is commonly used to analyze the different forms of mercury in a sample due to its high sensitivity and ability to selectively detect mercury. However, the traditional HPLC-ICP-MS methods are often criticized for their lengthy analysis times. In this study, we have refined the conventional approach by transitioning to ultra-high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (UHPLC-ICP-MS). This modification has resulted in significant reductions in runtime as well as reagent and argon usage, thereby offering a more rapid, environmentally friendly, and cost-effective method. We successfully adapted an HPLC-ICP-MS method to UHPLC-ICP-MS, achieving the analysis of Hg2+ and MeHg+ within 1 min with a mobile phase consumption of only 0.5 mL and a sample volume of 5.0 µL; this is a major advance compared to HPLC analysis with run times generally between 5 and 10 min. The method's performance was assessed by analyzing muscle and liver tissue samples (serving as reference material) from fish, demonstrating the versatility of the method in relation to different complex matrices.

Understanding the Impacts of Different Impurities on Elemental Mercury Removal by CaS in Chemical Looping Combustion of Coal: A First Principle Study.

CaSO4 has the advantages of abundant yield, high oxygen-carrying capacity, low cost, and no heavy metal pollution, making it promising as an oxygen carrier for chemical looping combustion (CLC). In comparison with other oxygen carriers, CaS as the reduced product of CaSO4 exhibits superior adsorption efficiency for Hg0 in the flue gas. In this paper, density functional theory (DFT) was used to investigate the adsorption mechanism of Hg0 on the adsorbent surface of CaS(001). The adsorption energies of different oxidized mercury species such as HgS, HgCl, and HgBr over the CaS surface were summarized. Furthermore, the effects of various flue gas components including SO2, H2S, S, HCl, Cl2, CO, H2, H2O, and C on Hg0 adsorption over the CaS(001) surface were evaluated. The results show that Hg0 can be adsorbed on the CaS(001) surface in a chemisorption manner with a reaction energy of -65.1 kJ/mol. The adsorption energy of different forms of mercury on the CaS(001) surface varies greatly, and mercury in the oxidized state is more easily captured by CaS. SO2 inhibits while other flue gas components promote Hg0 adsorption over the CaS surface. Overall, CaS tends to adsorb mercury in the reduction reactor and release mercury when CaS is re-oxidized to CaSO4 in the oxidation reactor. This is detrimental to mercury removal in the CLC of coal. This study sheds light on the migration and transformation of mercury in the CLC of coal with CaSO4 as the oxygen carrier.

Mercury Export From Freshwater to Estuary: Carbocentric Science Elucidates the Fate of a Toxic Compound in Aquatic Boreal Environments

The chemistry of mercury in freshwater systems, particularly man-made reservoirs, has received a great deal of attention owing to the high toxicity of the most common organic form, methylmercury. Although methylmercury bioaccumulation in reservoirs and natural lakes has been extensively studied at all latitudes, the fate of the different forms of mercury (total vs. dissolved; organic vs. inorganic) along the entire river-estuary continuum is less well documented. In fact, the difficulty of integrating the numerous parameters involved in mercury speciation in such large study areas, combined with the technical difficulties in sampling and analyzing mercury, have undoubtedly hindered advances in the field. At the same time, carbocentric science has grown exponentially in the last 25 years, and the common fate of carbon and mercury in freshwater has become increasingly clear with time. This literature review, by presenting the knowledge acquired in these two fields, aims to better understand the extent of mercury export from boreal inland waters to estuaries and to investigate the possible downstream ecotoxicological impact of reservoir creation on mercury bioavailability to estuarine food webs and local communities.

Indices of the DNA repair system in the brain of fish as a biomarker of inorganic mercury burden

Mercury is a widespread heavy metal that causes a stable and prolonged environmental pollution. Low concentrations of inorganic and organic mercury compounds are found in almost all water bodies. The high level of mercury bioaccumulation is a cause of tissue-specific toxicity, including neurotoxicity. Absorbed in nervous tissue mercury can cause brain disorders both in neural and glial cells. The brain of fish is considered one of the most susceptible targets for cytotoxicity of mercury in aquatic ecosystems. Taking into account that different forms of mercury have widespread distribution and exhibit a strong neurotoxic effect, the assessment of mercury cytotoxicity in the brain of fish is relevant and extremely important. Rainbow trout Oncorhynchus mykiss was exposed to mercury chloride in the dose range of 5-20 μg/L for 60 days to study the chronic exposure of low doses. In this paper, we studied the influence of inorganic mercury on oxidative stress, DNA repair proteins – ERCC1 and PARP1 in the trout’s brain. The results obtained have shown that the chronic effect of inorganic mercury causes dose-dependent oxidative stress in the fish brain. In addition, low concentrations of mercury (10 and 20 μg/L) caused a decrease in the content of ERCC1 in the brain of fish. On the contrary, the same doses have caused an increase in PARP1 expression. That is the chronic influence of low concentrations of inorganic mercury has a negative effect in the fish brain. Observed results showed that inorganic mercury has a potential for suppressing DNA repair and, therefore, increases the instability of genome. Thus, ERCC1 and PARP1 can be considered as the sensitive biomarkers of mercury cytotoxicity in the fish brain. A further study of mercury neurotoxicity is needed to find out the hazard of mercury environmental pollution as well as a validation of biomarkers of their impact.

Rethinking treatment of mercury poisoning: the roles of selenium, acetylcysteine, and thiol chelators in the treatment of mercury poisoning: a narrative review

We reevaluate the treatment of mercury poisoning, incorporating recent advances in understanding of mercury toxicity and the mercury:selenium interaction. This review focuses on: 1) the role, limitations and benefits of chelation (Unithiol, succimer and N-Acetylcysteine); 2) the role of selenium supplementation; and 3) how the different forms of mercury are impacted by use of chelation and selenium. Unithiol and succimer produce increases in urinary excretion of mercury and to a lesser degree blood and total body mercury. The primary role of N-acetylcysteine is increasing renal mercury excretion, similar to the thiol-chelators. Additional unique features of acetylcysteine include increased efflux of methylmercury from the brain, and reduced oxidative stress via increased glutathione production. The role of selenium includes: 1) restoration of selenoprotein activity, 2) protection against mitochondrial injury and DNA damage, 3) demethylation of methylmercury, 4) sequestering of mercury via Hg:Se complexes, and 5) redistribution of Hg inside organisms. Selenium may increase blood Hg, via a “sink” effect, causing a redistribution of mercury away from the brain. A combined approach for mercury poisoning treatment was developed focusing on restoration of selenoprotein function, reduction of oxidative stress and increased mercury elimination.

Spatial Differences and Influencing Factors of Dissolved Gaseous Mercury in the Yellow Sea and Bohai Sea in Spring

From 28 March to 17 April, 2018, different forms of mercury (Hg) in the Yellow Sea and Bohai Sea were measured to study the influencing factors on the distribution and transformation of Hg in spring using a shared cruise. The mean concentration of dissolved gaseous mercury (DGM) in the surface water of the Yellow and Bohai Seas was (44.3 ± 43.9) pg/L, which was close to that in mid-latitude oceans and deep seas. The ratio of DGM to THg (total mercury) was lower than in the oceans and in the Yellow and Bohai Seas in summer or fall. DGM concentrations in surface water were highest in the central part of the South Yellow Sea and were higher than those in the Bohai Sea, and their spatial distributions were consistent with RHg (reactive mercury). DGM and RHg correlated positively with water temperature in surface seawater (r = 0.506, P < 0.01; r = 0.278, P < 0.05). The concentrations of both DGM and RHg in surface water were controlled by solar radiation and water temperature. Foggy weather did not benefit the production of DGM and RHg. DGM in the bottom seawater was mainly affected by Dissolved Oxygen and water temperature (r = −0.366, P < 0.01; r = 0.331, P < 0.01), produced mainly by anaerobic reactions of the bottom seawater and sediment microorganisms. The bottom DGM concentrations in the Yellow and Bohai Seas were the highest, and DGM produced in bottom seawater and sediment plays a more important role than the surface water in spring. The concentrations of DGM and RHg in the surface and bottom water in the South Yellow Sea were all higher than those in the middle layer. Vertical variations in the North Yellow Sea and the Bohai Sea were small. The production and distribution of DGM and RHg were influenced by differences of latitude and by the Yellow Sea warm current in spring.

Potential mechanisms of cellular injury following exposure to a physiologically relevant species of inorganic mercury

Mercury is a toxic metal that is found ubiquitously in the environment. Humans are exposed to different forms of mercury via ingestion, inhalation, and/or dermal absorption. Following exposure, mercuric ions may gain access to target cells and subsequently lead to cellular intoxication. The mechanisms by which mercury accumulation leads to cellular injury and death are not understood fully. Therefore, purpose of this study was to identify the specific intracellular mechanisms that are altered by exposure to inorganic mercury (Hg2+). Normal rat kidney (NRK) cells were exposed to a physiologically relevant form of Hg2+, as a conjugate of cysteine (10 μM or 50 μM). Alterations in oxidative stress were estimated by measuring lipid peroxidation and mitochondrial oxidative stress. Alterations in actin and tubulin were measured using specific fluorescent dyes. Calcium levels were measured using Fluo-3 AM Calcium Indicator while autophagy was identified with Premo™ Autophagy Sensor LC3B-GFP. The current findings show that exposure to Hg2+ leads to enhanced oxidative stress, alterations in cytoskeletal structure, increases in intracellular calcium, and enhanced autophagy. We have established a more complete understanding of intoxication and cellular injury induced by a relevant form of Hg2+ in proximal tubule cells.

Distribution of organic and inorganic mercury in the tissues and organs of fish from the southern Baltic Sea

The aim of this study was to determine the distribution of total mercury (THg), methylmercury (CH3Hg+), and inorganic mercury (Hginorg) in the tissues and organs of fish depending on species, tissue, and organ, and their bioaccumulation in tissues and biomagnification throughout the trophic web. The study included four species of fish (herring, sprat, cod, and eel) from the southern Baltic Sea. The concentrations of the different forms of mercury were determined in tissues and internal organs. Intra-specific differences in levels of THg, CH3Hg+, and Hginorg in the tissues and organs were determined. Muscle contained the highest proportions of THg and CH3Hg+ in comparison to that in the internal organs. Differences in concentrations of THg, CH3Hg+, and Hginorg in the tissues and organs of fish were related to their preferred prey. The bioaccumulation of CH3Hg+ in the tissues and organs of predatory fish at the highest trophic levels was greater than in the liver and digestive tract of fish species at lower trophic levels, in which Hginorg predominated. The high concentrations of CH3Hg+ in eel and cod and the low levels in herring and sprat were linked with their food and the transfer of this element among species. The results suggested that the type of food, feeding habits, and trophic position were important parameters that influenced the transfer and biomagnification of mercury in fish.

Molecular mechanism of mercury-induced reproductive impairments in banded gourami, Trichogaster fasciata

Mercury is one of the key pollutants responsible for the degradation of natural aquatic ecosystems. Among the different forms of mercury that exist in the environment, mercuric chloride (HgCl2) is the dominant pollutant for freshwater environments as it is used as an ingredient in antiseptics, disinfectants and preservatives, insecticides, batteries and in metallurgical and photographic operations. Pollutant may exert their action on organisms or populations by affecting their normal endocrine function as well as reproduction. Thus, the present study tried to understand the effect of mercuric chloride (HgCl2) on reproductive function and to decipher the molecular mechanism of Hg-induced reproductive impairments of female Trichogaster fasciata. Both in vivo and in vitro experiments were performed by using ecologically relevant doses of HgCl2 and the resulting effects on follicular development, steroidogenic potentiality, aromatase activity, aromatase gene expression and steroidogenic factor-1 (SF-1) expression pattern were analysed. In vivo exposure to HgCl2 caused reproductive impairments as shown by the inhibitory role of HgCl2 on follicular development, steroid biosynthesis and SF-1 activity. In vitro experiments revealed that aromatase activity, steroidogenesis, aromatase and SF-1 expression were blocked by HgCl2. The results obtained from this study contribute to understand the molecular mechanism of HgCl2-induced reproductive impairment of T. fasciata.

Mercury induced community tolerance in microbial biofilms is related to pollution gradients in a long-term polluted river

The net toxicity of different forms of mercury, in the long-term during their transformation processes, leads to the selection of resistant bacterial cells and this result in community tolerance which is pollution induced. Accordingly, based on profiles of a bacterial community structure, analysis of Hg resistant culturable bacteria and quantification of merA genes, we assessed development of pollution induced community tolerance in a mercury-polluted gradient in the Idrijca River. TTGE analysis did not show effects of mercury pollution to bacterial community diversity, while quantification of merA genes showed that merA genes can be correlated precisely (R2=0.83) with the total concentration of mercury in the biofilm microbial communities in the pollution gradient.

Identification of Potential Serum Biomarkers in Mercury-Treated Mice Using a Glycoproteomic Approach

Mercury is a well-recognized health hazard and a deleterious environmental contaminant. Exposure to mercury can cause neurotoxic manifestations, nephrotoxicity, and immune function alterations; however, the mechanisms and related proteins responsible for these effects are still unclear. Our goal is to understand the relationship between the toxicity of mercury and the proteins affected by this toxic heavy metal and to define biomarkers for mercury intoxication. Two different forms of mercury, organic methylmercury or inorganic mercury sulfide, were orally administered to the mice for 4 weeks. To reduce complexity of the serum proteome, we enriched glycoproteins from mice serum with lectin concanavalin A resin, and the tryptic peptides of the purified glycoproteins were subjected to nanoultra performance liquid chromatography-Quadrupole time-of-flight for identification and label-free quantification. In this study, we characterized approximately 209 proteins from mice serum, and, among them, 21 proteins were differentially expressed in organic methylmercury-treated mice serum compared with the control group. Two proteins, serum amyloid P component (SAP) and inter α-trypsin inhibitor heavy chain 4 (ITI-H4), were upregulated in organic methylmercury-treated mice and confirmed with different doses of both types of mercury by Western blot analysis. Results of immunohistochemistry also confirmed the validity of SAP and ITI-H4 as biomarker candidates for organic methylmercury exposure. Findings of this study may assist in understanding the relationship between toxicity of mercury and upregulated proteins in mouse serum. Furthermore, the proteins identified here might be used as biomarker candidates in mercury intoxication.

English

Mercury is one of the most toxic elements of periodic table. It is a non-degradable environmental pollutant. Mercury has been used in dental amalgams since a long time. However concerns of mercury toxicity from this source have been debated. This article provides with an overview of the toxicology of the different forms of mercury to which human exposure occurs, and addresses methods to safely handle mercury waste generated in dental clinics.

Achieving the Great Lakes Initiative Mercury Limits in Oil Refinery Effluent

To meet the stringent Great Lakes Initiative (GLI) wastewater discharge mercury (Hg) limit of 1.3 ppt (ng/L), mercury removal technologies need to be identified and investigated. The goals of this study were to (1) identify and assess available wastewater treatment technologies for mercury removal from an oil refinery wastewater; and (2) conduct bench-scale tests to provide comparable, transparent, and uniform results to assess their performance at low mercury concentrations. The study found that many tested technologies were able to achieve the GLI mercury target concentration at the bench-scale, albeit with different efficiencies and engineering implications. These results demonstrate that at this scale there is no fundamental physical or chemical barrier to achieving < 1.3 ng Hg/L in the tested wastewater. The study also found that some technologies were effective on particulate mercury whereas others were effective on dissolved mercury. One emerging treatment technology was found to be effective on both particulate and dissolved mercury. Three mercury-removal technologies--ultrafiltration (particulate mercury), adsorption (dissolved mercury), and an emerging reactive filtration technology (particulate and dissolved mercury)--are recommended for further study. This research offers treatment alternatives for different forms of mercury in an oil refinery wastewater, which might be applicable to other types of mercury-containing wastewater.

Glutathione as an antioxidant in inorganic mercury induced nephrotoxicity

Heavy metal toxicity represents an uncommon but clinically significant medical condition, which if unrecognized or inappropriately treated results in significant morbidity and mortality. Among heavy metals, mercury is recognized as a potent and widely distributed toxicant having the ability to accumulate at various levels of food chain besides possessing ability to cross placental and blood-brain barrier. Symptom picture of mercury (Hg 2+ ) toxicity is characterized mainly by a series of renal disorders. Mechanism of inorganic mercury toxicity includes production of reactive oxygen species (ROS) capable of damaging lipids in membrane, proteins or enzymes in tissues, and DNA to induce oxidative stress as balance between generation, and elimination of ROS is essential for maintaining the functional integrity of a cell. Mitigation of endogenous mercury depends as a part on the presence of antioxidants such as glutathione - most abundant intracellular non-protein thiol that plays a central role in the maintenance of cellular redox status by quenching free radicals generated during oxidative stress. Ability of a cell to survive the threat posed by endogenous mercury represents a biological adaptation fundamental to survival. This review describes the current understanding and the mechanisms involved by different forms of mercury in eliciting their toxicity in kidney along with the knowledge of major intracellular reductant that plays important role in the mitigation of mercury toxicity for the maintenance of homeostasis within the body of living organisms.

Science and strategies to reduce mercury risks: a critical review

Despite decades of scientific research and policy actions to control mercury, exposure to toxic methylmercury continues to pose risks to humans and the environment. This article critically reviews the linkages between scientific advancements and mercury reduction policies aimed at reducing this risk, focusing on the challenges that mercury poses as an issue that crosses both spatial and temporal scales. Scientific aspects of the mercury issue at various spatial and temporal scales are reviewed, and policy examples at global, national and local scale are analysed. Policy activity to date has focused on the mercury problem at a single level of spatial scale, and on near-term timescales. Efforts at the local scale have focused on monitoring levels in fish and addressing local contamination issues; national-scale assessments have addressed emissions from particular sources; and global-scale reports have integrated long-range transport of emissions and commercial trade concerns. However, aspects of the mercury issue that cross the political scale (such as interactions between different forms of mercury) as well as contamination problems with long timescales are at present beyond the reach of current policies. It is argued that these unaddressed aspects of the mercury problem may be more effectively addressed by (1) expanded cross-scale policy coordination on mitigation actions and (2) better incorporating adaptation into policy decision-making to minimize impacts.

Mercury Concentration of Whole Blood and Red Blood Cell in Taiwan Residents

PP-31-151 Background/Aims: People are exposed to different forms of mercury (Hg), and about 80% of methylmercury (MeHg) in blood is associated with red blood cells (RBC), where it is largely bound to hemoglobin. We aimed at measuring the Hg concentration in whole blood (WB) and RBC and evaluating their correlation in Taiwan residents. Methods: We recruited 43 volunteers (18 male and 23 female) aged between 19 and 48 years who were not exposed to Hg. Samples of blood (5 mL) were collected and 3 mL RBC was obtained at the same time. The amount of total Hg in WB and RBC is determined by using cold vapor atomic absorption spectroscopy. The WB and RBC samples were treated by microwave-assisted digestion to reach complete solubilization before determination. Results: We found 95% of Hg kept in RBC, the concentration of Hg in WB and RBC was 5.91 ± 2.81 and 11.22 ± 5.68 ng/g, respectively. A high correlation of Hg concentration between WB and RBC was observed (r = 0.93, P < 0.001), this correlation was higher in males (r = 0.95) than that in females (r = 0.90). We divided volunteers into 2 groups by median of age; both WB and RBC Hg concentrations were found almost the same in these 2 metrics. The Hg concentration of WB observed in males was higher than in females (6.14 vs. 5.72 ng/g, P = 0.34), however, in RBC, the results showed adverse direction (10.47 vs. 11.80, P = 0.28). Conclusion: We found the WB and RBC Hg concentrations in Taiwan residents were 5.91 ± 2.81 and 11.22 ± 5.68 ng/g, respectively, this level was higher as compared with the residents of United States and European countries.

Sorption of Phenyl Mercury, Methyl Mercury, and Inorganic Mercury onto Chitosan and Barbital Immobilized Chitosan: Spectroscopic, Potentiometric, Kinetic, Equilibrium, and Selective Desorption Studies

The objective of the study was to elucidate the binding of Hg2+, methyl mercury, and phenyl mercury on chitosan and barbital-immobilized chitosan by potentiometric titration and XPS and FTIR spectroscopy. Adsorption experiments were conducted at room temperature (30 °C) to optimize the percentage removal of different forms of mercury, and the data were fitted to Langmuir and Freundlich adsorption isotherms. Speciation of inorganic, methyl, and phenyl mercury was achieved by sequentially eluting inorganic mercury using 0.1 N perchloric acid followed by methyl mercury using 0.015 N NaCl and finally phenyl mercury using 0.05 N EDTA. Potentiometric titration data and a pKa spectrum approach showed the presence of self-assembled amine/protonated amine, amine, and hydroxyl/amine functional groups. The total number of functional groups was found to be 158.05 mol·g−1 and 68.6 mol·g−1 for barbital-immobilized chitosan and chitosan, respectively, suggesting that a larger number of binding sites are available in barbital-immobilized chitosan for bonding to mercury. FTIR, pH, and XPS studies show that the possible functional groups in the metal binding include amino functional groups in the case of chitosan and amide groups in the case of barbital-immobilized chitosan. The peak areas of XPS Hg 4f spectra show greater adsorption for Hg using barbital-immobilized chitosan as adsorbent compared to chitosan.

Sensing mercury for biomedical and environmental monitoring.

Mercury is a very toxic element that is widely spread in the atmosphere, lithosphere, and surface water. Concentrated mercury poses serious problems to human health, as bioaccumulation of mercury within the brain and kidneys ultimately leads to neurological diseases. To control mercury pollution and reduce mercury damage to human health, sensitive determination of mercury is important. This article summarizes some current sensors for the determination of both abiotic and biotic mercury. A wide array of sensors for monitoring mercury is described, including biosensors and chemical sensors, while piezoelectric and microcantilever sensors are also described. Additionally, newly developed nanomaterials offer great potential for fabricating novel mercury sensors. Some of the functional fluorescent nanosensors for the determination of mercury are covered. Afterwards, the in vivo determination of mercury and the characterization of different forms of mercury are discussed. Finally, the future direction for mercury detection is outlined, suggesting that nanomaterials may provide revolutionary tools in biomedical and environmental monitoring of mercury.

Mercury pollution: an emerging problem and potential bacterial remediation strategies

Heavy metal toxicity represents an uncommon but clinically significant medical condition, which if unrecognized or inappropriately treated results in significant morbidity and mortality. Mercury is recognized as a potent and widely distributed toxicant in the global environment having ability to accumulate at various levels of food chain besides possessing ability to cross placental and blood–brain barrier. It has been seen that bacteria growing near mercury polluted sites have evolved various means of resistance based on the expression of different genes of mer operon against different forms of mercury. Microbe based remediation/detoxification of mercury is on forefront due to low cost and less health hazardous compared to physicochemical based strategies, which are cost intensive and hazardous to human health. However, strategies based on the modern aspects of biological technologies employing mer operon genes in different combination are needed to be designed for exploitation in the remediation of mercury completely from mercury contaminated environments.

Health implications of mercury exposure in children

Mercury is a ubiquitous environmental toxin that can produce a wide range of health effects in humans. It is found in three chemical forms: organic, inorganic and elemental (mercury). The sources of exposure are also markedly different for the different forms of mercury. Diet, especially fish and other seafood, is the main source of exposure of the general public to organic mercury. Dental amalgam is the most important source for elemental mercury vapour in the general population. Inorganic mercury compounds are known as 'mercuric salts', which are sometimes used in skin-lightening creams and as antiseptic creams and ointments. Though its use has been banned in some countries, these products are still available on the world market. Each mercury form possesses a different risk to human health. Mercury can be transferred prenatally to the developing foetus via the placenta or postnatally from breast milk to the nursing infant. Children are potentially more susceptible to mercury than adults due to differences in the stages of brain development and organ growth that occur during the foetal, infant and childhood developmental periods. The objective of this paper is to review the relevant literature concerning transplacental and lactational exposure to mercury, taking into account mercury speciation, in order to have a critical assessment of its adverse health effects. Attention is also given to available studies in Saudi Arabia where skin-lightening creams, dental amalgam and thimerosal are still in use.