Mercury Sulfide Research Articles

Methylation of mercury and tin by estuarine microbial mats

After tin and mercury salts were added to estuarine microbial mats increasing amounts of methyltin and methylmercury, respectively, were formed over a 30 to 100 hour time period. Inhibition of the methylation by molybdate, a metabolic inhibitor of sulfate reduction, stimulation by pyruvate addition and lack of methylation by sterilized mats, were evidence that sulfate reducing bacteria within the mats were responsible for the tin and mercury methylation. Methyl mercury was formed from mercuric chloride and mercuric cysteine, but not from mercuric sulfide. We suggest that mercury bound to organic complexes in anoxic sediments is likely methylated by microbial mats. Since estuarine meiofauna and macrofauna fed on microbial mats, the methylmercury and methyltin formed by microbial mats could be an important avenue for the entrance of these compounds into the marine food web.

Anticipation of Large Intrinsic Spin Hall Conductivity in Mercury Chalcogenides: A First‐Principles Study

AbstractThe report carried out detailed first‐principle calculations of Mercury chalcogenides (HgX; X = Te, Se and S) using density functional theory, verifying the bulk band inversion property with different exchange‐correlation functionals. The Wannier function method is used to study the non‐trivial topology of HgX systems, spin Berry curvature, and intrinsic spin Hall conductivity. Quantized intrinsic spin Hall conductivity is observed in the HgX systems. Large intrinsic spin Hall conductivity is found in the systems due to a strong spin Berry curvature accumulation near the triply degenerate points in the Brillouin zone. Calculation shows that the intrinsic spin Hall conductivity for all three HgX systems has stable plateaus, with Mercury Telluride having a maximum width of up to 1.05 eV. The maximum intrinsic spin Hall conductivity of –931/e () is obtained in mercury sulfide, higher than the reported values for spin Hall conductivity and the plateau width in typical topological insulators such as , , and as well as in transition metal pnictides (TaX, X = As, P and N) and transition metal iridates.

Biopolymer-enhanced delivery of reactive sulfide reagents for in-situ mercury remediation of heterogeneous contaminated soils

Mercury pollution from natural and anthropogenic sources demands effective remediation. This study focuses on optimizing a chemical stabilization approach using sulfur-containing compounds to create stable mercury sulfide (HgS) and immobilize elemental mercury in polluted soils. We propose using xanthan gum biopolymer to enhance the in-situ delivery of sulfide microparticles, overcoming soil heterogeneities due to its non-Newtonian behavior. Stability tests indicated that increased biopolymer concentration enhances particle stability due to the viscous and shear-thinning behavior of the polymer solutions. Various combinations (12 solutions) of xanthan polymer, pyrite microparticles, and sulfide-containing reagents were tested in batch experiments. Pyrite microparticles slightly reduced the xanthan solution's viscosity while retaining its non-Newtonian character. All solutions effectively transformed liquid mercury droplets into cinnabar, demonstrating successful mercury stabilization. Notably, solutions containing PIAX and SIPX, xanthate organosulfur compounds, significantly reduced the dissolved concentration of elemental mercury. Column experiments demonstrated xanthan gum's superior performance for in-situ injection of pyrite microparticles and sulfide mixtures into the soil compared to conventional water injection. At a polymer concentration of 4 g/L, a stable displacement front and an 88 % recovery of the initially injected particle-suspension density were achieved. The combined effects of xanthate's floating behavior and xanthan gum's shear-thinning nature substantially enhanced the delivery of pyrite microparticles in porous media for soil mercury remediation. This combination reduced the aqueous elemental mercury concentration in artificially polluted sand by up to 97 %, particularly with the xanthate organosulfur compound, PIAX. Xanthate has a higher potential to react with elemental mercury to form cinnabar compared to sodium thiosulfate. Additionally, the pyrite microparticles, rendered hydrophobic in xanthate solutions, integrated into the mercury droplets, forming a black paste. This study introduces a promising approach for efficient elemental mercury stabilization in contaminated soils by integrating biopolymers, reactive soluble compounds, and pyrite microparticles for sustainable decontamination.

Characterizing the Stoichiometry of Individual Metal Sulfide and Phosphate Colloids in Soils, Sediments, and Industrial Processes by Inductively Coupled Plasma Time-of-Flight Mass Spectrometry.

Size and purity of metal phosphate and metal sulfide colloids can control the solubility, persistence, and bioavailability of metals in environmental systems. Despite their importance, methods for detecting and characterizing the diversity in the elemental composition of these colloids in complex matrices are missing. Here, we develop a single-particle inductively coupled plasma time-of-flight mass spectrometry (sp-icpTOF-MS) approach to characterize the elemental compositions of individual metal phosphate and sulfide colloids extracted from complex matrices. The stoichiometry was accurately determined for particles of known composition with an equivalent spherical diameter of ≥∼200 nm. Assisted by machine learning (ML), the new method could distinguish particles of the copper sulfides covellite (CuS), chalcocite (Cu2S), and chalcopyrite particles (CuFeS2) with 75% (for Cu2S) to 99% (for CuFeS2) accuracy. Application of the sp-icpTOF-MS method to particles recovered from natural samples revealed that iron sulfide (FeS) particles in lake sediment contained ∼4% copper and zinc impurities, whereas pure pyrite (FeS2) was identified in hydraulic fracturing wastewater and confirmed by selected area electron diffraction. Colloidal mercury in an offshore marine sediment was present as pure mercury sulfide (HgS), whereas geogenic HgS recovered from an industrial process contained ∼0.08 wt % silver per Hg, enabling source apportionment of these colloids using ML. X-ray absorption spectroscopy confirmed that Hg was predominantly present as metacinnabar (β-HgS) in the industrial process sample. The determination of impurities in individual colloids, such as zinc and copper in FeS, and silver in HgS may enable improved assessment of their origin, reactivity, and bioavailability potential.

Solid-structured phosphine sulfide as a new precursor in the synthesis of mercury sulfide quantum dots

Tricyclohexylphosphine sulfide (Cy)3PS, a solid-structured phosphine sulfide precursor, was used for the first time in the synthesis of sphere-shaped colloidally stable β-HgS CQDs. DFT calculations applying the TPSS-D3/def2-TZVP level of theory in the gas phase showed that the chemical reactivity of the titled precursor is similar to that of TOPS. The nanocrystals produced using HgCl2/(Cy)3PS/THF were colloidally stable, possessing near- and mid-infrared absorptions. As the reaction time increased, the first excitonic peaks were redshifted in the near-infrared window between 0.8 and 1.1 µm. Meanwhile, the red shifting of the mid-wavelength intraband (1Se‐1Pe) absorption peaks was between 3.9 and 4.8 µm. A good agreement between the diameters calculated using the atomistic tight-binding approach and those obtained using TEM was observed. The concentration and molar absorption coefficient (ε400) of the prepared QDs were determined as well. An increase in the ε400 of the quantum dots with increasing reaction time was shown. XPS elemental analysis showed that HgS NCs with a nearly equal atomic ratio of Hg:S were poorly colloidally stable, and their FT-IR spectra had no intraband absorptions in the mid-IR window. Meanwhile, high colloidally stable and mid-wavelength intraband absorption peaks in the FT-IR spectra were shown for mercury-rich HgS CQDs.

The binding effects and mechanisms of dissolved organic matter (DOM) on the fate of mercury in sludge anaerobic digestion combined with thermal hydrolysis

Dissolved organic matter (DOM) plays an important role in regulating the fate of mercury (Hg), e.g., mobility, bioavailability, and toxicity. Clarifying the role of DOM in binding Hg in the treatment processes of sewage sludge is important for relieving Hg contamination risks in land applications. However, the impacts of DOM on Hg binding in sewage sludge are still unclear. In this study, we investigated the evolution of Hg and its speciation in full-scale sludge anaerobic digestion (AD) with thermal hydrolysis. The role of DOM in binding Hg(II) was further analyzed. The results showed that AD with thermal hydrolysis led to an increase in the Hg content in the sludge (from 3.72 ± 0.47 mg/kg to 10.75 ± 0.16 mg/kg) but a decrease in Hg mobility (the mercury sulfide fraction increased from 60.56 % to 79.78 %). Further adsorption experiments revealed that at equivalent DOM concentrations, DOM with a low molecular weight (MW<1 kDa) in activated sludge, DOM with a medium molecular weight (1 kDa<MW<5 kDa) in thermally hydrolyzed sludge, and DOM with a high molecular weight (MW> 5 kDa) in both anaerobically digested sludge and conditioned sludge showed high binding amounts of Hg(II), with 1372.54, 535.28, 942.09 and 801.51 mg Hg/g DOM, respectively. Parallel factor analysis (PARAFAC) and fluorescence quotient (FQ) results showed that tryptophan-like and tyrosine-like substances had high binding affinities for Hg(II). Furthermore, X-ray photoelectron spectroscopy (XPS) indicated that the reduced organic sulfur contained in the DOM was potentially bound to Hg through the interactions of Hg-S and Hg-O. These results indicated that DOM may play special roles in regulating Hg speciation. The association between DOM and Hg(II), such as the significant positive correlation (p < 0.05) between the dissolution rate of Hg(II) and release of tryptophan-like substances during thermal hydrolysis, suggested the potential way for removing Hg from sludge.

Analytical Study of Polychrome Clay Sculptures in the Five-Dragon Taoist Palace of Wudang, China

During the Ming Dynasty, the Five-Dragon Palace functioned as a royal Taoist temple set atop one of China’s holiest Taoist mountains, Wudang Mountain. Two tower polychrome sculptures with exquisite craftsmanship have remained over the centuries. In this study, the painting materials and the techniques used to construct these sculptures were analyzed through multiple characterization methods, including optical microscope (OM) observations, micro-Raman spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), X-ray diffraction (XRD), micro-Fourier-transform infrared spectroscopy (μ−FTIR), and pyrolysis–gas chromatography/mass spectrometry (Py−GC/MS). The results revealed that the pigments used in these sculptures included red pigments, which were composed of mercury (II) sulfide (cinnabar or vermillion), minium (Pb3O4), and hematite (Fe2O3); green pigments, which included atacamite and botallackite (Cu2Cl(OH)3), and blue pigments, which comprised smalt (CoO·nSiO2) and azurite (Cu3(CO3)2(OH)2). The white base layer was composed of quartz and mica minerals combined with gypsum or plant fiber, and the gold foil was adhered to the surface using heated tung oil. In addition, a special multi−layer technique was applied, with red under the golden gilding, white under the blue layer, and gray and black under the green layer. Drying oil was used as a binder for lead-containing pigments. This study offers substantial proof of reliable techniques to use in the continuing conservation of these sculptures, and it also serves as a foundation to determine if they can be dated to the late Ming or early Qing Dynasty (17th century).

The Origin and Course of the Blood Supply to the Lower Eyelid Orbital Fat: Anatomical Study and Clinical Significance.

The aim of this study is to investigate the origin and course of the orbital fat arterial supply in the lower eyelid using traditional anatomy and three-dimensional computed tomography (CT). Twenty-seven cadaver heads were infused with mercury sulfide contrast media through the ophthalmic artery, maxillary artery, transverse facial artery, and facial artery. CT images were obtained after contrast agent injection, three-dimensional CT scans were reconstructed, and the cadaver heads were dissected. Forty-five qualified hemifaces showed that the orbital fat arterial supply in the lower eyelid originates primarily from the inferomedial muscular trunk (IMT) of the ophthalmic artery and the orbital branch of the infraorbital artery. The medial branch of the IMT terminated at the medial fat pad (35.6%) or the orbital floor (64.4%). The lateral branch terminated at the inferior oblique (IO) muscle (28.9%) or the central and lateral fat pads (17.8%). In 53.3%, the lateral branch extended to the anterior part of the lateral fat pad and terminated in the orbital wall or the zygomaticoorbital foramina. The orbital branch of the infraorbital artery coursed between the orbital floor and the orbital fat, providing supply to the IO muscle, inferior rectus (IR) muscle, nasolacrimal duct, and orbital fat. This study elucidated the origin and course of the orbital fat arterial supply in the lower eyelid, which may help to avoid reducing the blood supply of the orbital fat pedicles during surgery. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Preparation and anti-inflammatory effect of mercury sulphide nanoparticle-loaded hydrogels

We successfully prepared mercury sulphide nanoparticle hydrogels by physical encapsulation method. The successfully prepared mercuric sulphide nanoparticle hydrogel was a zinc folate hydrogel, which showed an obvious porous structure with interconnected and uniformly distributed pores and a pore size range of about 20 μm. The maximum drug loading of the hydrogels was 3%, and the in vitro cumulative release degree was in accordance with the first-order kinetic equation Mt = 149.529 (1 − e−0.026 t ). The particles in mercuric sulphide nanoparticle hydrogels significantly down-regulated the expression of the cell surface co-stimulatory molecule CD86 (p < .0001). Meanwhile, the inflammatory response was regulated through the NF-κB pathway in LPS-induced inflammatory cells. Later, it was observed that mercuric sulphide nanoparticle hydrogels could significantly counteract the inflammatory and immune models through a mouse ear swelling model, a rat foot-plantar swelling model and a rheumatoid arthritis model. This design targets the immunomodulatory, and anti-inflammatory effects through nanocomposite hydrogel technology. It reduces the drawbacks of low mercury utilisation and susceptibility to accumulation of toxicity. It aims to provide an experimental basis for the development of mercuric sulphide and the treatment of inflammatory and immune-related diseases. Highlights Mercury sulphide nanoparticle hydrogel has an optimal mercury sulphide nanoparticle content of 2%, is structurally homogeneous and stable, and does not exhibit significant liver or kidney toxicity. Mercuric sulphide nanoparticle hydrogel exerts anti-inflammatory effects in cells and rats, and regulates the expression of macrophage surface molecules and factors related to the NF-κB pathway. Mercuric sulphide nanoparticle hydrogel improves the condition of ankle synovial joints in a rat model of rheumatoid arthritis.

Mercuric sulfide nanoparticles suppress the neurobehavioral functions of Caenorhabditis elegans through a Skp1-dependent mechanism

Cinnabar is the naturally occurring mercuric sulfide (HgS) and concerns about its safety have been grown. However, the molecular mechanism of HgS-related neurotoxicity remains unclear. S-phase kinase-associated protein 1 (Skp1), identified as the target protein of HgS, plays a crucial role in the development of neurological diseases. This study aims to investigate the neurotoxic effects and molecular mechanism of HgS based on Skp1 using the Caenorhabditis elegans (C. elegans) model. We prepared the HgS nanoparticles and conducted a comparative analysis of neurobehavioral differences in both wild-type C. elegans (N2) and a transgenic strain of C. elegans (VC1241) with a knockout of the SKP1 homologous gene after exposure to HgS nanoparticles. Our results showed that HgS nanoparticles could suppress locomotion, defecation, egg-laying, and associative learning behaviors in N2 C. elegans, while no significant alterations were observed in the VC1241 C. elegans. Furthermore, we conducted a 4D label-free proteomics analysis and screened 504 key proteins significantly affected by HgS nanoparticles through Skp1. These proteins play pivotal roles in various pathways, including SNARE interactions in vesicular transport, TGF-beta signaling pathway, calcium signaling pathway, FoxO signaling pathway, etc. In summary, HgS nanoparticles at high doses suppress the neurobehavioral functions of C. elegans through a Skp1-dependent mechanism.

Initial investigations of rubricated inscriptions from Roman Sicily: Comparing the material evidence with ancient writers’ ideals

Although the polychromy of ancient statuary has become a regular topic in archaeological discussions, in part thanks to archaeometrical analyses, little attention has been given to such aspects in the field of epigraphy. The aim of this paper is to identify analytically the red pigments employed in inscriptions from southeastern Sicily in the Roman period (1st-6th c. CE), and to investigate the relationship between actual material practice and ancient terminology. Minimally invasive identification of cinnabar (mercuric sulphide) on some funerary and honorific inscriptions aligns with Pliny’s statement on the use of “minium”. However, other less expensive lead-containing pigments were detected, suggesting that different materials were used in different contexts and according to various practices. It appears from this preliminary study that choices of ancient red pigments can provide additional information for understanding epigraphic cultures.

Identification of Skp1 as a target of mercury sulfide for neuroprotection.

Mercury sulfide (HgS) exerts extensive biological effects on neuronal function. To investigate the direct target of HgS in neuronal cells, we developed a biotin-tagged HgS probe (bio-HgS) and employed an affinity purification technique to capture its target proteins. Then, we identified S-phase kinase-associated protein 1 (Skp1) as a potential target of HgS. Unexpectedly, we discovered that HgS covalently binds to Skp1 through a "Cys62-HgS-Cys120" mode. Moreover, our findings revealed that HgS inhibits the ubiquitin-protease system through Skp1 to up-regulate SNAP-25 expression, thereby triggering synaptic vesicle exocytosis to regulate locomotion ability in C. elegans. Collectively, our findings may promote a comprehensive interpretation of the pharmacological mechanism of mercury sulfide on neuroprotective function.

Red Dyes from West to East in Medieval Europe: From Portuguese Manuscript Illuminations to Romanian Textiles

Red is the color par excellence, its symbolism being linked with protection and magic through its primary attributes, fire and blood. It was the predominant color from the earliest times, certainly during the Greek and Roman periods and into Medieval Europe, until blue became a competitor around the 13th century. Mineral pigments, like iron oxides, were the first red sources, used to draw lines, dots, or spots on cave walls or stones. Later, other mineral red pigments were also exploited: Cinnabar, natural mercury sulfide, since the Neolithic, and realgar, arsenic trisulfide, in Ancient Egypt. Scientific investigation revealed that, although inorganic pigments were mainly used in painting, iron oxides and cinnabar were also the first available sources for coloring textiles. Plant dyes have been known since the Neolithic, exploited by people living in climatically mild areas rich in vegetation. Their use is strongly connected with two other fundamental textile processes: Spinning and weaving. Scholarly literature indicates Egyptian privet (henna, Lawsonia inermis) as the oldest red vegetal source used. Although widely known as a source of brown, the dried leaves, when powdered and treated with lime water, yield an intense orange red, which is efficient for dyeing the body — skin and hair — and textiles of animal origin. Madder (Rubia tinctorum or relatives) was the first dye to be reported from archaeological European Bronze and Iron Ages textiles preserved in the Hallstatt salt mines, Scandinavian bog sites, and other European burials. Apart from madder, the most widely appreciated red dye sources in the European Classical period were kermes (Kermes vermilio and K. ilicis), purple (species of sea snails from the Muricidae family), and extracts of red tree resins, as dragon’s blood (e.g. Dracaena draco, Dracaena cinnabari, and Daemonorops draco). These sources were used for textile dyeing and as organic pigments in paintings.

The Chemical Nature of Mercury and Copper Sulfides and Its Implication for Bioavailability Assessments in Sediments

Sulfur chemistry plays an important role in regulating the bioavailability of heavy metals (HMs) because HM sulfides are extremely insoluble in sediments. However, quantifying HM sulfides in sediments has been difficult because they are considered acid-extractable (AE). Previous studies also found that Hg and Cu behaved differently from other HMs in sediments. This study investigated the chemical nature of Hg and Cu sulfides and the causes of Hg and Cu anomalies in sediments. The results indicated that Hg and Cu sulfides are not mono-sulfides (HS− or S=) but bi-sulfides (S2=), which are non-acid-extractable (NAE) under nitrogen. These results explain the Hg and Cu anomalies compared to other HMs and facilitate a procedure to quantify Hg and Cu sulfides in sediments. We analyzed the AE and NAE fractions of Hg, Cu, and Zn under nitrogen in the sediments of Apalachicola Bay, North Florida. Zn was included for comparison because Zn sulfide is mono-sulfide. The NAE Hg and Cu were, on average, 97.9 ± 2.7% and 84.6%, respectively, of the total, much higher than that of Zn (24.3% of the total) in the sediments, as expected. The NAE fractions of Hg and Cu were sulfides and thus could be excluded from the bioavailability assessments.

The influence of mercury speciation and its transformation in growth medium on the accumulation efficiency by white mustard

ABSTRACT Mercury is the most dangerous pollutant prone to the formation of the toxic forms. Therefore, the problem of cleaning mercury contaminated areas seems to be very relevant. Numerous works have been published on the study of mercury uptake depending on the type of plants and natural conditions, but less attention was paid to studying the influence of element’s speciation on their accumulation ability. In the present work, the results of laboratory experiments on the assessment of accumulation efficiency of white mustard growing in medium with artificially introduced mercury species such as HgCl2, CH3Hg Cl and HgS are discussed and bioconcentration factors were evaluated while maintaining plant viability. It was shown that methylmercury is the most intensively accumulated specie while mercury sulphide is more imbibed than HgCl2 during 3 months experiment in spite of its negligible solubility in water. Based on the assumption that the cause of such a phenomenon is associated with the transformation of mercury species in the process of the plants growth, mercury speciation in the growing environment has been studied in dynamics and the results obtained confirmed this suppose. It appeared that HgCl2 and HgS are transformed into other chemical forms.

Beautiful, Magic, Lethal: a Social Perspective of Cinnabar Use and Mercury Exposure at the Valencina Copper Age Mega-site (Spain)

Today, mercury is a matter of concern for health and environmental authorities across western countries, and legislation has been passed and programs have been implemented for its total elimination from human activity. But this was not always the case: mercury and its compounds have been highly appreciated and used since remote times all over the world with very diverse purposes ranging from decorative, medicinal, metallurgical and symbolic. In particular, cinnabar (HgS, mercury sulfide), a mineral of an intense red color, has been considered in many cultures as an exotic raw material, highly valued and associated with the elites and sacred practice. In this paper, we examine one such case, set almost 5000 years ago, in Copper Age Iberia, by investigating mercury exposure through human bone. The study presented here includes a total of 170 samples from 70 different human individuals and 22 animals (plus one soil sample) from the Copper Age mega-site of Valencina, south-western Spain. It is the largest ever single-site study of exposure to mercury based on human bone in combination with cinnabar use. Abnormally high values are recorded in some individuals dating between 2900 and 2650 BC, especially in those buried in remarkable tombs belonging to the social elite of this period, but high levels of mercury are also recorded in the rest of the population. Three lines of interpretation are used to explain these results, including the manipulation of cinnabar (grinding it into powder, mixing it with other substances, using it for the decoration of objects, buildings and the human body), its direct consumption through ingestion or inhalation by a ‘special’ social group and the contribution of environmental factors. Based on the currently available evidence, which is carefully reviewed, Valencina represents the most intense and prolonged case of exposure to mercury recorded in human history, which makes it an important site to assess the long and complex history of use of this substance.

The effects of chlorine-containing species on cinnabar: A density functional theory investigation into the surface adsorption reactivity of mercury sulfide

First-principles computations can be used to noninvasively probe semiconductor surfaces and describe mechanisms and transformations that occur on those surfaces. One such material of interest is the chalcogenide mercury sulfide (HgS), also known as cinnabar. Cinnabar (α-HgS) and its synthetic counterpart (vermilion) have been used as bright red pigments since antiquity and are important sulfide materials in the field of art conservation. However, it has been known since Roman times that these pigments can darken when exposed to light. It has been hypothesized that Cl2 and other chlorine-containing materials are involved in the photodegradation of cinnabar surfaces. Here we use first-principles density functional theory (DFT) to probe the adsorption reactivity of Cl-containing adsorbates on HgS surfaces, as DFT yields information at the atomistic level and can link changes in surface structure to changes in electronic states. Specifically, we model single adsorbates interacting with corrugated and flat HgS surfaces to probe the initial step in the photodegradation mechanism. This allows us to not only assess the strength of adsorption and any corresponding adsorbate dissociations, but also link these adsorption and dissociation events to key changes in the electronic band structure that may act as spectroscopic identifiers in the degradation pathway of chalcogenide semiconductors that contain photoreactive metals.

CHARACTERISTICS OF DISEASE SYMPTOMS EXPERIENCED BY COMMUNITIES AROUND MINE SITES AND GEOTHERMAL MANIFESTATION AREAS IN DRIEN MANGKO VILLAGE, WOYLA DISTRICT, ACEH BARAT DISTRICT

According to WHO, mercury is a metallic element that occurs naturally and is classified into 3 main groups, namely liquid and gas, inorganic mercury such as mercury chloride, mercury acetate, mercury sulfide, and organic mercury. The research was conducted in November involving 32 respondents from gold mining communities and the research location was in Drien Mangko Village, Woyla District, West Aceh Regency. Samples were taken from communities around gold mining in the gold mining area and around the mine. Sample measurement by providing a prepared questionnaire. The results of the research showed that the acute clinical symptoms of the community were that the majority of respondents experienced symptoms of headache and swelling of the salivary glands (18 respondents), vomiting (14 respondents), chest tightness and bloody urine (12 respondents), numbness in the mouth (10 respondents), loose teeth. easy to fall out (9 respondents), difficulty breathing (8 respondents), pelvic pain (6 respondents), nausea (5 respondents), loss of sense of smell (2 respondents) and dark gums (1 respondent). Meanwhile, chronic toxicity symptoms recorded include somatosensory disorders in gold processing workers. The majority of workers experience hearing loss (18 respondents), irritability (5 respondents), and headaches (3 respondents).

Direct Uptake and Intracellular Dissolution of HgS Nanoparticles: Evidence from a Bacterial Biosensor Approach.

Mercury sulfide nanoparticles (HgSNPs), which occur widely in oxic and anoxic environments, can be microbially converted to highly toxic methylmercury or volatile elemental mercury, but it remains challenging to assess their bioavailability. In this study, an Escherichia coli-based whole-cell fluorescent biosensor was developed to explore the bioavailability and microbial activation process of HgSNPs. Results show that HgSNPs (3.17 ± 0.96 nm) trigger a sharp increase in fluorescence intensity of the biosensor, with signal responses almost equal to that of ionic Hg (Hg(II)) within 10 h, indicating high bioavailability of HgSNP. The intracellular total Hg (THg) of cells exposed to HgSNPs (200 μg L-1) was 3.52-8.59-folds higher than that of cells exposed to Hg(II) (200 μg L-1), suggesting that intracellular HgSNPs were only partially dissolved. Speciation analysis using size-exclusion chromatography (SEC)-inductively coupled plasma mass spectrometry (ICP-MS) revealed that the bacterial filtrate was not responsible for HgSNP dissolution, suggesting that HgSNPs entered cells in nanoparticle form. Combined with fluorescence intensity and intracellular THg analysis, the intracellular HgSNP dissolution ratio was estimated at 22-29%. Overall, our findings highlight the rapid internalization and high intracellular dissolution ratio of HgSNPs by E. coli, and intracellular THg combined with biosensors could provide innovative tools to explore the microbial uptake and dissolution of HgSNPs.

Mercury concentrations in Antarctic zooplankton with a focus on the krill species, Euphausia superba

The Antarctic is the most isolated region in the world; nevertheless, it has not avoided the negative impact of human activity, including the inflow of toxic mercury (Hg). Hg deposited in the Antarctic marine environment can be bioavailable and accumulate in the food web, reaching elevated concentrations in high-trophic-level biota, especially if methylated. Zooplankton, together with phytoplankton, are critical for the transport of pollutants, including Hg to higher trophic levels. For the Southern Ocean ecosystem, one of the key zooplankton components is the Antarctic krill Euphausia superba, the smaller euphausiid Thysanoessa macrura, and the amphipod Themisto gaudichaudii – a crucial food source for most predatory fish, birds, and mammals. The main goal of this study was to determine the Hg burden, as well as the distribution of different Hg forms, in these dominant Antarctic planktonic crustaceans. The results showed that the highest concentrations of Hg were found in T. gaudichaudii, a typically predatory taxon. Most of the Hg in the tested crustaceans was labile and potentially bioavailable for planktivorous organisms, with the most dangerous methylmercury (MeHg) accounting for an average of 16 % of the total mercury. Elevated Hg concentrations were observed close to the land, which is influenced by the proximity to penguin and pinniped colonies. In areas near the shore, volcanic activity might be a possible cause of the increase in mercury sulfide (HgS) content. The total Hg concentration increased with the trophic position and ontogenetic stage of predation, specific to adult organisms. In contrast, the proportion of MeHg decreased with age, indicating more efficient demethylation or elimination. The Hg magnification kinetics in the study area were relatively high, which may be related to climate-change induced alterations of the Antarctic ecosystem: additional food sources and reshaped trophic structure.