Mercury Hg Research Articles

Distribution characteristics, sources and risk assessment of heavy metals in the surface sediments from the largest tributary of the Lancang River in the Tibet Plateau, China.

Angqu, positioned in the eastern expanse of the Tibet Plateau, claims the title of the largest tributary to the Lancang River. In October and December of 2018, in the sediment of Angqu, a comprehensive investigation was conducted on nine heavy metals-arsenic (As), manganese (Mn), chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), copper (Cu), zinc (Zn), and nickel (Ni). This investigation aimed to scrutinize the spatial and temporal distribution patterns of these metals, assess the pollution status and ecological risks associated with the sediments, and delve into the sources contributing to their presence. The research results indicate that the average concentrations of As, Hg, and Cd in Angqu sediments exceed the soil background values of Tibet, while the concentrations of other heavy metals are below the soil background values of Tibet. Notably, arsenic poses potential ecological risks. In Angqu sediments, the concentrations of Mn, Cu, Ni, and Pb are generally higher in the wet season, but the seasonal variations of heavy metals in Angqu sediments are not significant. The sediments in the Angqu Basin are predominantly affected by mercury Hg, Cd, and As, with varying degrees of pollution at different sampling points. In the main stream of Angqu (City section), Hg pollution has reached above a moderate level, whereas As pollution near the tributary is only slightly polluted. The analysis of heavy metal sources reveals that there are five primary contributors to heavy metals in surface sediments of Angqu: parent material, agricultural activities, groundwater, atmospheric deposition, and other unidentified sources. Mn, Cr, Pb, and Ni are mainly derived from soil parent material, accounting for more than 50%. About 60.82% of As comes primarily from groundwater. Zn and Cd are mainly sourced from agricultural activities, accounting for 41.25% and 34.33%, respectively. Additionally, 20.6% of Hg originates from atmospheric deposition.

Telfairia Occidentalis Leaf Concentrations of Hg, Pb and Cd Planted in Old Sewage Sludge Dumpsites in Owerri Imo State

Leaves of Telfairia OCCIDENTALIS planted in abandoned Sewage Dumpsite were analyzed for mercury Hg, Lead Pb and Cadmium Cd levels. Samples were collected from three dump areas at a depth of 0-30cm, and fallow lands of about 50 meters away from the dumps were also sampled for reference. The samples were subjected to analysis and Heavy metals were determined using Atomic Absorption Spectrophotometer (AAS). The findings indicated that sewage increased the soil concentrations of Heavy Metals (0.19 Hg, 17.0 Pb, and 3.0 Cd Mg/Kg1) when compared with control (0.04 Hg, 1.4 Pb, and 0.29 Cd Mg/Kg1). These were not high when compared with established permissible limits according to FEPA WHO. These concentrations were not high to cause health challenges. Many scientist reported that not all sewage sludge contains high amount of heavy metals especially when allowed to decompose for a longer period of 4 years even without prior treatment, but repeated application can increase levels. Sewage Sludge also increased N, P, K, Ca, Mg, K and ECEC and this may triggered the reason of continuous planting by farmers in dumpsites due to the fact that sewage sludge can increase the nutrient content of soil and improves its physical and chemical properties. Organic matter content which is also of great importance in soil reaction was increased by the sewage sludge deposit. The deposit of sewage sludge added organic matter, improved the soil physical and chemical properties, at the same time increased the heavy metals levels. But the heavy metals levels were not above permissible limits for heavy metal concentrations in soils. It is therefore recommended to land spray the sludge and allowed to decompose for about 2 years before planting on it. The result was discussed in-line with heavy metals in questions and permissible limits for each.

Molecularly Imprinted Polymer-Based Nanoporous Carbon Nanocomposite for Effective Adsorption of Hg(II) Ions from Aqueous Suspensions

Due to the release of hazardous heavy metals from various industries, water pollution has become one of the biggest challenges for environmental scientists today. Mercury Hg(II) is regarded as one of the most toxic heavy metals due to its ability to cause cancer and other health issues. In this study, a tailor-made modern eco-friendly molecularly imprinted polymer (MIP)/nanoporous carbon (NC) nanocomposite was synthesized and examined for the uptake of Hg(II) using an aqueous solution. The fabrication of the MIP/NC nanocomposite occurred via bulk polymerization involving the complexation of the template, followed by polymerization and, finally, template removal. Thus, the formed nanocomposite underwent characterizations that included morphological, thermal degradation, functional, and surface area analyses. The MIP/NC nanocomposite, with a high specific surface area of 884.9 m2/g, was evaluated for its efficacy towards the adsorptive elimination of Hg(II) against the pH solution changes, the dosage of adsorbent, initial concentration, and interaction time. The analysis showed that a maximum Hg(II) adsorption effectiveness of 116 mg/g was attained at pH 4, while the Freundlich model fitted the equilibrium sorption result and was aligned with pseudo-second-order kinetics. Likewise, thermodynamic parameters like enthalpy, entropy, and Gibbs free energy indicated that the adsorption was consistent with spontaneous, favorable, and endothermic reactions. Furthermore, the adsorption efficiency of MIP/NC was also evaluated against a real sample of condensate from the oil and gas industry, showing an 87.4% recovery of Hg(II). Finally, the synthesized MIP/NC showed promise as a selective adsorbent of Hg(II) in polluted environments, suggesting that a variety of combined absorbents of different precursors is recommended to evaluate heavy metal and pharmaceutical removals.

Coupling fluorescent probes to characterize S-containing compounds in a sulfate reducing bacteria involved in Hg methylation

The microbial methylation of inorganic mercury Hg(II) is governed by S-containing compounds such as thiols (RSH) and sulfides (S2−). Various S-containing molecules in an environmental or culture medium can be difficult to assess because of the complexity of the medium, poor stability, and low concentration ranges of sulfide and thiol compounds. Here, we applied two fluorescence spectroscopy-based methods using α, β-unsaturated ethanoylcoumarin fluorophore (DHC) for the quantification of sulfides, and monobromo (trimethylammonio) bimane (qBBr) to quantify total thiol concentrations (in extracellular and bacterial cell fractions). The potential interferences of both organic and inorganic compounds from the matrix were evaluated. In the presence of Hg species, both methods allowed the quantification of free sulfides or thiols (not forming complexes with Hg). The two methods were highly sensitive, with detection limits of 100 nM and 20 nM for thiols and sulfides, respectively. They also exhibited high selectivity for the detection of thiols or sulfides against other tested matrix compounds. Finally, both methods were applied to characterize S-containing compounds in a culture of Pseudodesulfovibrio hydrargyri strain BerOc1, a methylating sulfate-reducing bacterium (SRB) exposed to 0.1 mM of cysteine. During bacterial growth, we used (i) DHC probe to quantify sulfide concentration in the bulk fraction, (ii) qBBr for total extracellular thiols and total thiols adsorbed on the cells, and (iii) liquid chromatography-tandem mass spectrometry to track cysteine degradation and characterize other thiols. The time series until the end of BerOc1 growth showed biodegradation of cysteine, and biosynthesis of sulfides and other thiol compounds.

Adsorption and intracellular uptake of mercuric mercury and methylmercury by methanotrophs and methylating bacteria

The cell surface adsorption and intracellular uptake of mercuric mercury Hg(II) and methylmercury (MeHg) are important in determining the fate and transformation of Hg in the environment. However, current information is limited about their interactions with two important groups of microorganisms, i.e., methanotrophs and Hg(II)-methylating bacteria, in aquatic systems. This study investigated the adsorption and uptake dynamics of Hg(II) and MeHg by three strains of methanotrophs, Methylomonas sp. strain EFPC3, Methylosinus trichosporium OB3b, and Methylococcus capsulatus Bath, and two Hg(II)-methylating bacteria, Pseudodesulfovibrio mercurii ND132 and Geobacter sulfurreducens PCA. Distinctive behaviors of these microorganisms towards Hg(II) and MeHg adsorption and intracellular uptake were observed. The methanotrophs took up 55−80% of inorganic Hg(II) inside cells after 24 h incubation, lower than methylating bacteria (>90%). Approximately 80–95% of MeHg was rapidly taken up by all the tested methanotrophs within 24 h. In contrast, after the same time, G. sulfurreducens PCA adsorbed 70% but took up <20% of MeHg, while P. mercurii ND132 adsorbed <20% but took up negligible amounts of MeHg. These results suggest that microbial surface adsorption and intracellular uptake of Hg(II) and MeHg depend on the specific types of microbes and appear to be related to microbial physiology that requires further detailed investigation. Despite being incapable of methylating Hg(II), methanotrophs play important roles in immobilizing both Hg(II) and MeHg, potentially influencing their bioavailability and trophic transfer. Therefore, methanotrophs are not only important sinks for methane but also for Hg(II) and MeHg and can influence the global cycling of C and Hg.

Rice straw derived cellulose nanofibers modified with L-histidine for ultra-trace fluorometric assay of Cr(VI) and Hg(II) in aqueous medium

Through this study, an effort has been made to eliminate the problems of rice straw burning and pollution due to heavy metals by utilizing cellulose nanofibers (CNFs) derived from rice straw to develop effective fluorescent sensors for detection of chromium Cr(VI) and mercury Hg(II), concurrently. CNFs were modified using L-histidine (CHIS) to yield cellulosic fluorophore, not reported hitherto. Characterization using X-ray Powder Diffraction (XRD), Field emission scanning electron microscopy (FESEM) and Thermogravimetric analysis (TGA), indicated partial impairment of crystalline structure of cellulose with conversion to CHIS, however the sensor was thermally more stable as 40% mass residue remained even after 700 °C. Fluorescence response exhibited substantial quenching with Cr(VI) and Hg(II) ions, with detection limits of 2.236 nM and 3.97 nM, respectively. The XPS studies established strong interactions of CHIS with Hg(II) ions via imine groups and Cr(VI) ions with imine as well as amine group on CHIS resulting in substantial quenching. Further, when excited at different wavelength under fluorescence microscope, CHIS indicated suppression of fluorescence effect with adsorption of heavy metal ions. The sensor was highly selective, stable with time and pH with excellent usability up to 4 cycles. Thus, CHIS present a facile and robust platform for simultaneous detection and real time monitoring of Hg(II) and Cr(VI) metal ions.

Novel Determination of Elemental Mercury in Silicate Rock by Thermal Desorption

Much importance has been given in the recent literature to the determination and speciation of mercury in contaminated mine waste and soil. Among mercury species, the concentration of elemental mercury is a key parameter for risk assessment. However, at present, a validated analytical method for the quantitation of Hg(0) in solid matrices does not exist. In the present study, the reliability of a thermal desorption technique in quantifying elemental mercury in Hg(0) amended silica glass, a reference shelf standard, and in a Hg(0)-bearing mineralized silicate rock, considered representative of mine tailings, has been addressed. Mercury release has been measured at variable temperature using a thermo-desorption method combined with a mercury vapor analyzer. The results allowed the peak temperature for the emission of free and matrix-bound Hg(0) components to be identified, suggesting that 100 °C represents a suitable temperature for Hg(0) isothermal release. Experiments with the shelf standard exposed to a specific sorbent keeping the temperature constant at 100 °C provided 90% and 98% Hg(0) recovery after 2 and 24 h, respectively. Experiments with the mineralized rock demonstrated that free elemental mercury was recovered after 6 h, while 60 h were required for the free and matrix bound Hg(0) release. The limits of detection and quantification of the method were 1.3 ng and 3.0 ng, respectively. This approach allows elemental mercury in solid matrices to be determined, allowing the quantification of Hg(0) in contaminated mine tailings and soil.

Effects of Mg doping on physical properties of zinc-blende mercury selenide HgSe compound

Structural, electronic and optical properties of Hg1-xMgxSe (x = 0, 0.25, 0.5, 0.75 and 1) alloys have been investigated by using density functional theory calculations (DFT) with the generalized gradient approximation under the Perdew–Burke–Ernzerhof (GGA-PBE) method. In fact, we have studied and discussed the structural, electronic and optical properties of the HgSe when substituting the Mercury Hg by Magnesium element (Mg). The calculated structural parameters show a decrease trend with increasing the concentration of doping by the Mg element. The obtained results for the electronic properties indicate that HgSe is a semimetal material. However, Hg1-xMgxSe (x = 0.25, 0.5, 0.75 and 1) are semiconductors. Also, such materials exhibit a direct bandgap at Γ point symmetries. The optical parameters such as real and imaginary parts of dielectric function ε(ω), the refractive index n(ω), the absorption coefficient α(ω), the reflectivity R(ω), the optical conductivity σ(ω) and the energy loss function L(ω) were also studied and discussed.

Recent advances in nanomaterial developments for efficient removal of Hg(II) from water.

"Water" contamination by mercury Hg(II) has become the biggest concern due to its severe toxicities on public health. There are different conventional techniques like ion exchange, reverse osmosis, and filtration that have been used for the elimination of Hg(II) from the aqueous solutions. Although, these techniques have some drawbacks during the remediation of Hg(II) present in water. Adsorption could be a better option for the elimination of Hg(II) from the aqueous solutions. "Conventional adsorbents" like zeolite, clay, and activated carbons are inefficient for this purpose. Recently, nanomaterials have attracted attention for the elimination of Hg(II) from the aqueous solutions due to high porosity, better surface properties, and high efficiency. In this review, a thorough discussion has been carried out on the synthesis and characterization of nanomaterials along with mechanisms involved in the elimination of Hg(II) from aqueous solutions.

Revisiting some overlooked registered Thai traditional medicine preparations: an alert to a regulatory affair

ObjectiveThis study evaluated the heavy metal identity and content of registered Thai Traditional medicine (TTM) preparations in Thailand to ensure consumer safety.MethodsBoth qualitative and quantitative information about the elemental composition of the heavy metal content in each TTM crude drug and the heavy metal content in some registered TTM preparations in Thailand was performed. Seven kinds of mineral-based TTM crude drugs, namely realgar, orpiment, Chinese powder, Sen, vermilion, natural vermilion, and cinnabar, were analyzed with X-ray diffraction and scanning electron microscopy and energy-dispersive spectroscopy techniques to determine the type of metal and elemental composition to confirm their chemical formulas. Furthermore, the number of heavy metals, such as arsenic (As), lead (Pb), and mercury (Hg), was in three samples of realgar-containing preparations; one sample of Sen-containing preparation, and eight samples of cinnabar-containing preparations. Heavy metals were determined with inductively coupled plasma-optical emission spectrometry.ResultsIt was observed that realgar and orpiment consisted of arsenic sulfide (AsS) and arsenic trisulfide (As2S3), respectively. Both crude drugs contained approximately 50% of As. Vermilion, natural vermilion, and cinnabar consisted of mercuric sulfide (HgS), with Hg accounting for approximately 66%. Sen consisted of Pb (II, IV) oxide (Pb3O4) with an approximate Pb percentage of 80%. However, Pb was absent in Chinese powder and consisted mainly of calcium carbonate (CaCO3). A traditional detoxification procedure can reduce the amount of As and Hg in processed crude drugs by at least 20%.ConclusionsPb was higher in some TTM preparations, and no CaCO3 was detected in Chinese powder. Our results raise concerns on both safety and efficacy to consumers and alert public health policymakers that they should implement regulations so that the quality (authenticity) and quantity of elemental medicine used in traditional medicine are correctly labeled and within permissible limits to prevent threats to consumers.

Effect of Plant Growth-Promoting Bacteria on Biometrical Parameters and Antioxidant Enzymatic Activities of Lupinus albus var. Orden Dorado Under Mercury Stress.

Heavy metal contamination of soils is a large-scale environmental problem. It leads to significant disqualification of the territory, in addition to being a source of the potential risk to human health. The exposure of plants to mercury (Hg) generates responses in its growth and their oxidative metabolism. The impact of increasing concentrations of Hg on the development of Lupinus albus var. Orden Dorado seedlings has been studied, as well as the plant’s response to the maximum concentration of Hg that allows its development (16 μg ml–1). The result shows that only the inoculum with plant growth promoting bacteria (PGPB) allows the biometric development of the seedling (root length, weight, and number of secondary roots) and prevents the toxic effects of the heavy metal from aborting the seedlings. Specifically, treatments with strains 11, 20 (Bacillus toyonensis), 48 (not determined), and 76 (Pseudomonas syringae) are interesting candidates for further PGPB-assisted phytoremediation trials as they promote root biomass development, through their PGPB activities. The plant antioxidant response has been analyzed by quantifying the catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) enzyme activity in the root, under 16 μg ml–1 of HgCl2 and different PGPB treatments. Results show that, although Hg stress generally induces enzyme activity, strains 31 and 69I (Pseudomonas corrugata) and 18 and 43 (Bacillus toyonensis) can keep SOD and APX levels close to those found in control without Hg (p < 0.01). Strain 18 also shows a significant reduction of GR to control levels without Hg. The present work demonstrates the benefit of PGPB treatments in situations of high Hg stress. These findings may be a good starting point to justify the role of PGPB naturally isolated from bulk soil and the rhizosphere of plants subjected to high Hg pressure in plant tolerance to such abiotic stress conditions. More studies will be needed to discover the molecular mechanisms behind the phytoprotective role of the strains with the best results, to understand the complex plant-microorganism relationships and to find effective and lasting symbioses useful in bioremediation processes.

Compact Fano-Type Liquid Metamaterial Resonator for High-Precision Temperature Sensing

In this paper, a liquid metal mercury (Hg) based high quality-factor (Q-factor) liquid electromagnetic metamaterial unit, the Hg Fano resonator, is designed for the high-precision temperature sensing application. Such Fano resonance in the Hg-resonator is excited by the microstrip-line coupling and the resonance frequency is sensitive to the background temperature changes. Based on the high Q-factor and the temperature-sensitive features of Hg-Fano resonator, the high-precision temperature sensing performance is discussed and achieved, with numerical and experimental demonstrations. The experimental sensitivity of 11.7 MHz/°C and figure-of-merit (FOM) of 0.4/°C are obtained. The proposed compact Hg-Fano resonator-based sensor can be widely used for the wireless temperature sensing area.

In vitro and in silico Studies Reveal Bacillus cereus AA-18 as a Potential Candidate for Bioremediation of Mercury-Contaminated Wastewater.

Mercury (Hg) pollution is a worldwide problem and increasing day by day due to natural and anthropogenic sources. In this study, mercury-resistant (HgR) bacterial isolates were isolated from industrial wastewater of Ittehad Chemicals Ltd., Kala Shah Kaku, Lahore, Pakistan. Out of 65 bacterial isolates, five isolates were screened out based on showing resistance at 30–40 μg/ml against HgCl2. Selected Hg-resistant bacterial isolates were characterized as Bacillus subtilis AA-16 (OK562835), Bacillus cereus AA-18 (OK562834), Bacillus sp. AA-20 (OK562833), Bacillus paramycoides AA-30 (OK562836), and Bacillus thuringiensis AA-35 (OK562837). B. cereus AA-18 showed promising results in the resistance of HgCl2 (40 μg/ml) due to the presence of merA gene. Scanning electron microscopy (SEM) analysis of immobilized B. cereus AA-18 showed the accumulation Hg on the cell surface. The inoculation of immobilized B. cereus AA-18 remediated 86% Hg of industrial wastewater up to 72 h at large scale (p < 0.05). In silico analysis showed structural determination of MerA protein encoded by merA gene of B. cereus AA-18 (OK562598) using ProtParam, Pfam, ConSurf Server, InterPro, STRING, Jpred4, PSIPRED, I-TASSER, COACH server, TrRosetta, ERRAT, VERIFY3D, Ramachandran plot, and AutoDock Vina (PyRx 8.0). These bioinformatics tools predicted the structural-based functional homology of MerA protein (mercuric reductase) associated with mer operon harboring bacteria involved in Hg-bioremediation system.

A Simplified Drying Procedure for Analysing Hg Concentrations

Mercury (Hg) in peatlands remains a problem of global interest. To mitigate the risks of this neurotoxin, accurate assessments of Hg in peat are needed. Treatment of peat that will be analysed for Hg is, however, not straightforward due to the volatile nature of Hg. The drying process is of particular concern since Hg evasion increases with the temperature. Samples are, therefore, often freeze-dried to limit Hg loss during the drying processes. A problem with freeze-drying is that cost and equipment resources can limit the number of samples analysed in large projects. To avoid this bottleneck, we tested if drying in a 60 °C-degree oven could be an acceptable alternative to freeze-drying. We both freeze-dried and oven-dried (60 °C) 203 replicate pairs of peat samples, and then examined the differences in total Hg concentration. The Hg concentration differed significantly between the two drying methods with a median Hg deficit in oven-dried samples of 4.2%. Whether a 4.2% deficit of Hg depends on one’s purpose. The lower median Hg concentration in oven-dried samples has to be weighed against the upside efficiently drying large sets of peat samples. By freeze-drying a subset of the samples, we fitted a function to correct for Hg loss during oven-drying (y=0.96x+0.08). By applying this correction, the freeze-drying bottleneck could oven-dry large-scale inventories of total Hg in peatlands with results equivalent to freeze-drying, but only have to freeze-dry a subset.

Assessment of heavy metal composition of Ogbujilekwe Stream Watershed in Nimo, Njikoka L.G.A. of Anambra State

The study on heavy metals was conducted at the Ogbujilekwe stream watershed. The study aimed to ascertain the heavy metal content of the watershed and the water from the nearby stream and to find out if there is any relationship between the heavy metals in the watershed and that in the waters sample. The experiment was laid out using Randomized Complete Block Design. The heavy metals that were investigated in this research work are Copper (Cu), Mercury (Hg), Lead (Pb) and Zinc (Zn). The result of mean values of the heavy metals shows that the heavy metals were significant and Cu followed by Hg was the most significant at p&lt; 0.005. Also, Hg in soil was above the permissible limit for soil samples. Results from the mean values of the water samples also showed that all the heavy metals were significant in water, and mercury was the most significant heavy metal. From correlation analysis of the heavy metals in soil and water, only mercury in the soil had a positive correlation with mercury in water, and an increase in other heavy metals in the water had no relationship with the watershed. The mercury pollution in the water can therefore be attributed to the discharge from the watershed.

Levels of Heavy Metals Contamination (As, Cd, Hg, Pb) in Some Human Consumption Water Sources in Agbangnizoun and Za-Kpota Town Halls, Southern Benin

In the current decades, the increasing presence of metallic contaminants in water for human consumption has become a major public health concern. This concern is even more pronounced in rural areas such as in the Town Halls of Agbangnizoun and Za-Kpota where the majority of households use surface water, wells and tanks to satisfy their daily drinking water needs, without any prior treatment, due to the low level of access to drinking water supplied by the State. This study aims at assessing the levels of contamination of these resources in mercury (Hg), cadmium (Cd), lead (Pb) and arsenic (As). The mercury was determined using the cold vapor technique by the Direct Mercury Analyzer (DMA-80) while lead and cadmium were analyzed by molecular absorption spectrophotometry by the DR 3900. The Arsenic was extracted by distillation using the silver diethyldithiocarbamate method then measured by molecular spectrophotometry technique. The results show that surface waters contain great quantities of metals than well and cistern waters. Lead (220.97 &amp;plusmn; 9.45 &amp;micro;g/L) and cadmium (20.13 &amp;plusmn; 0.17 &amp;micro;g/L) in surface waters have levels above WHO guidelines and B&amp;eacute;nin standards. On the other hand, there is no significant difference between the metal concentrations of well and cistern waters at the 5% threshold compared to the borehole water (witness sample). Significant correlations are established between toxic metals (Pb and Cd) and physical parameters (turbidity and suspended matters) at the threshold of 1 %. As for mercury (Hg) and arsenic (As), the concentrations are very lower than these of Cd and Pb and below the quantification limit of the device. These results confirm that the surface waters consumed by the populations of the Town Halls of Agbangnizoun and Za-Kpota do not respect drinking water standards.

Concentrations and Species of Mercury in Municipal Sludge of Selected Chinese Cities and Potential Mercury Emissions From Sludge Treatment and Disposal

Municipal sewage has been identified as an important source of mercury (Hg) to the environment, and sewage sludge is the major sink of sewage-borne Hg. Knowledge of Hg species in sludge and potential Hg emissions during sludge treatment/disposal is still limited. A survey on Hg concentrations and species in sewage sludge of 16 provinces and municipalities in China was conducted. Hg was detected in all sewage sludge samples, with total Hg (THg) concentrations ranging from 0.3 to 7.7 mg/kg. Results from sequential chemical extractions (SCE) indicated that sludge-borne Hg mainly occurred in the form of Hg sulfide, with a small amount of organo-chelated Hg (Hg-OM) and HgO, and a negligible amount of soluble Hg. Thermal decomposition results indicated that Hg is generally released from sludge at a temperature range of 200–400°C, with the highest release at 250–350°C (38%–86%), consistent with the thermal decomposition of HgS, Hg-OM, and HgO. THg in sewage samples under ventilation at room temperature remained constant over a month period, indicating negligible Hg emission under such conditions. The mass loading of sludge-borne THg in China for year 2019 was estimated to be 30 tons, about 3.6% of the total anthropogenic THg released (including direct and secondary anthropogenic releases) in China. At the temperature range for sludge incineration, sludge carbonization, and sludge/brick/cement production, most of the Hg in sludge will be released to air due to thermal decomposition of Hg compounds. As such, Hg-capture systems are essential in sludge treatment processes involving high temperatures.

Exploration of Aqueous Phyllanthus amarus Leaf Extract as a Protective Agent in Mercury Chloride-Exposed Wistar Rats: A Neurobehavioural Study

Mercury (Hg) exposure is known to damage vital components of the central nervous system primarily through oxidative stress. Although Phyllanthus amarus (PA) is reported to be rich in antioxidants, there is a dearth of relevant research evidence to show its protective activity against Mercuric chloride (HgCl2)-induced neurotoxicity. Accordingly, this study was designed to investigate the possible protective activity of aqueous Phyllanthus amarus leaf extract (APALE) in HgCl2-exposed rats using standard neurobehavioral assessments. Thirty adult Wistar rats were randomized into six groups of five rats each viz: A: Control, distilled water; B: HgCl2 (4 mg/kg body wt.); C: APALE (200 mg/kg body wt.) + HgCl2 (4 mg/kg); D: APALE (400 mg/kg body wt.) + HgCl2 (4 mg/kg); E: APALE (200 mg/kg body wt.); F: APALE (400 mg/kg body wt.). All administrations were through an orogastric tube for 14 days. Thereafter, neurobehavioral tests (open field, novel object and Y-maze) were done and experimental rats were sacrificed by cervical dislocation. Body, brain and cerebellar weights were examined across all groups. HgCl2 exposure significantly (p&lt;0.0.05) decreased whole body weight across experimental groups. Similarly, a reduction in brain and cerebellar weight was observed. Significant neurobehavioral alterations to locomotion, discrimination index and cognition/memory, induced by HgCl2, were observed across experimental groups. However, protection against the deleterious effects induced by HgCl2 was observed following pretreatment with APALE. Conclusively, these findings show that APALE demonstrated potent protective activity against HgCl2-induced neurotoxicity and may be useful in the management of Hg toxicity and other related disorders.

Analisis Kandungan Merkuri (Hg) pada Badan Air, Sedimen dan Biota yang Terdampak Aktivitas Pertambangan Emas di Kabupaten Parigi Moutong

Parigi Moutong District is one of the regencies in Central Sulawesi province with the highest number of illegal mining activities. Unlicensed mining activities generally use mercury as an extracting agent and gold processing waste is generally disposed of in rivers or other water bodies. The purpose of this study was to analyze the levels of heavy metal mercury (Hg) in water bodies, sediments, and marine biota in gold mining areas in Parigi Moutong District. The sampling method was carried out by random sampling method, while the analysis of mercury content in samples of river water, sediment, and biota was carried out using atomic absorption spectroscopy (AAS). From the results of the study, it was found that mercury levels in water and sediment samples were still below the quality standard value which were 0.001 mg/Kg and 0.13 mg/Kg, respectively, while the mercury levels in all biota samples had exceeded the quality standard values ​(0.03 mg/Kg). This indicates that mercury has accumulated in the food chain in the water near the mine site.

Identification of Cyanide in Sediment of River in Hulawa Village

(1) Background: mining activities in Hulawa Village have caused heavy metal contamination in the surrounding environmental ecosystem. This is caused by the waste from gold processing which is dumped directly into the river body. The purpose of this study was to determine the Cyanide content in the sediment river in Hulawa Village; (2) Methods: this research is a descriptive study, using a purposive sampling method, with the sampling location at the midpoint of the river. This research was conducted in August-September 2020. The sediment sampling technique used the JPHA guidelines, and the cyanide examination in the sediment used the AAS test; (3) Result: the sediment samples obtained were then taken to the WLN laboratory in Manado to be tested for cyanide content. The test results showed that the cyanide content in the sediment was &lt;0.5 mg/kg; (4) Conclusion: apart from heavy metal Mercury (Hg), the river in Hulawa Village has also been polluted by heavy metal Cyanide (CN). Cyanide content is still less than 0.5 mg/kg due to its not yet intensive use. However, if used continuously by miners, the possibility of cyanide accumulating in large quantities cannot be avoided, and this can have a health impact on the people in Hulawa Village.