Hg Concentrations Research Articles

Trophic and environmental influences on trace element concentrations in Australian fur seals

Trace elements (TE) in living organisms can have detrimental health impacts depending on their concentration. As many TEs are obtained through diet, trophic niche changes associated with the impacts of anthropogenic activities and climate-change may influence exposure to top predators. The Australian fur seal (Arctocephalus pusillus doriferus; AUFS) represents the greatest resident, marine predator biomass in south-eastern Australia. With adult female foraging ranges limited to the continental shelf, their source of TEs is geographically restricted. Plasma, red blood cell and milk samples collected between 1998 and 2022 at Kanowna Island, were analysed for TEs (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, V and Zn) using inductively-coupled plasma mass-spectrometry (ICP-MS). Plasma fatty-acid profiles and ocean climate variables were used to investigate trophic and environmental influences, respectively, on TE concentrations. Estimated whole blood concentrations in lactating females were comparable to levels reported in other marine mammals, except for Se and Mn. Correlations between adult tissues were negative for Mn and positive for As, Hg and Sn while molar Se:Hg were high but within reported levels for pinnipeds. Element concentrations in pup plasma were greater than lactating females for Fe, Mn and Sn indicative of high transplacental transfer while doses of Se and As from milk exceeded tolerable effect levels for humans. Relationships with fatty-acid profiles suggest diet influenced concentrations of Cu, Hg, Mn, Sn, V and Zn in adult plasma. In addition, inter-annual variation in TE concentrations were influenced by broad-scale climate indices, including the Southern Annular Mode and the Southern Oscillation Index, and local conditions associated with the seasonally-active Bonney Upwelling. These findings suggest the TE concentrations in blood and milk of AUFS are and will continue to be affected by anticipated oceanographic changes, mediated by alterations in prey type availability, with potential impacts on the population's health.

Forest cover influences fish mercury concentrations in national parks of the western U.S.

The global prevalence of mercury (Hg) contamination and its complex biogeochemical cycling has resulted in elevated Hg concentrations in biota in remote and pristine environments. However, there is uncertainty in the relative importance of Hg deposition and landscape factors that control Hg cycling and bioaccumulation. To address this, we measured total mercury (THg) concentrations in 1344 fish across 60 subalpine lakes from 12 national parks (NPs). These parks represent three distinct high-elevation regions across the western U.S.: Cascades and Olympic Peninsula, Sierra Nevada and Great Basin, and Rocky Mountains. Within these regions, three NPs (Mount Rainier, Yosemite, and Rocky Mountain) were intensively studied representatives of each region. This study aimed to (1) assess the magnitude of mercury contamination in a collection of remote, small catchment lakes; (2) quantify the variability of fish THg concentrations among and within parks; and (3) test the relative importance of Hg inputs in comparison to landscape characteristics on lake-specific fish THg concentrations. The spatial variability in fish THg concentrations was 2.6-fold higher than variation in deposition to watersheds, suggesting that factors other than Hg delivery are important determinants of Hg accumulation in these environments. Spatially, fish THg concentrations (ng/g ww ± standard error) were lower in the Rockies (46.2 ± 5.0) and Sierra (56.5 ± 5.8) compared to the Cascades (67.8 ± 6.1). Additionally, fish THg concentrations increased with increasing conifer forest cover (Intensive parks: P < 0.0001, R2 = 0.43; All parks: P = 0.0001, R2 = 0.23) but were not correlated with wet Hg deposition across the catchment. These findings suggest that forest composition is likely an important aspect of Hg delivery to lake food webs, and although the mechanisms are unclear, could be tied to some combination of forest influences on catchment organic carbon and increased surface area for dry Hg deposition.

Total mercury and methylmercury in lake water in years before and after removal of mercury-polluted pulp fiber sediment

There is an elevated presence of mercury (Hg) in the biosphere because of anthropogenic activities. The resulting damage to ecosystems and human health increases dramatically when microorganisms produce highly toxic methylmercury (MeHg). Total Hg (THg), MeHg and ancillary water chemistry were measured in two connected lakes, separated by a short stream stretch, before (1996, 1998 and 2003) and after (2007, 2009 and 2010) the removal of Hg-polluted pulp fiber sediment. Over the study period, there was a decrease in sulfate in the surface water of both lakes, presumably because of declining atmospheric sulfate deposition. Together, the reductions in OM, sulfate, and Hg, resulted in decreased MeHg concentrations as well as decreased MeHg:THg ratios in the bottom water overlying the sediment. There was also a reduction in zooplankton MeHg and fish total Hg in both lakes. Multiple regressions, using the bottom water data before and after remediation from both lakes, indicated that both the yearly maximum MeHg concentration [MeHgmax] and MeHgmax:THg correlated positively with the simultaneously measured sulfate deficit (a proxy for microbial sulfate reduction) and inorganic Hg concentration (IHg=THg - MeHg). This may suggest that the removal of Hg and the decreased sulfate reduction not only led to a decrease in available Hg substrate for methylation but also disfavored the Hg methylation process. As opposed to sulfate deficit, other measurements reflecting heterotrophic microbial activity such as inorganic carbon (IC), ammonium (NH4+), and iron (Fe) did not show significant correlations with MeHg or MeHg:THg when the data from both lakes were combined.

The mercury and low molecular-weight antioxidants levels in ungulates of the Republic of Karelia

The high toxicity of mercury (Hg) poses a danger to the environment and humans, but studies of the concentration of this metal in organisms of terrestrial ecosystems are few. Ecotoxicologists also pay little attention to studying the role of antioxidant vitamins in protecting cells from toxic metals. The Republic of Karelia is one of the northwestern regions of Russia, the biogeochemical features of which can contribute to an increase in the mobility and bioavailability of Hg in food chains. The purpose of the work was to determine the concentration of Hg in the liver, kidneys, muscle and hair of ungulate mammals of the Republic of Karelia (wild boar Sus scrofa L. and moose Alces alces L.) and to analyze the relationship between the level of this toxic metal and the content of low molecular-weight antioxidants – reduced glutathione, retinol and α-tocopherol. Species and tissue-specific of the studied parameters in wild boars and moose are noted. The observations discovered by other researchers that omnivorous species accumulate more Hg in their tissues compared to herbivores, and also that this toxic metal is predominantly accumulated in the kidneys, while muscles contain a minimal amount, have been confirmed. Hg concentrations in most samples of liver and kidney of wild boars and in all samples of these same organs of moose were within the limits recorded for domestic pigs and deer, respectively. The levels of Hg we recorded in the tissues and hair of wild boars and moose were generally comparable to or lower than the levels of this metal noted in animals from other regions of Russia and other countries of the world. In wild boars and moose of Karelia, no statistically significant relationships were found between the Hg level and the content of the studied antioxidants in the internal organs. Moose were characterized by a higher content of α-tocopherol in the body than wild boars, which is a feature of this type of herbivorous ungulate mammal. The results of the study indicate a relatively low level of mercury pollution in terrestrial ecosystems in Karelia.

Heavy metal concentrations in soil and ecological risk assessment in the vicinity of Tianzhu Industrial Park, Qinghai-Tibet Plateau

Industrial parks in China are centers of intensive chemical manufacturing and other industrial activities, often concentrated in relatively small areas. This concentration increases the risk of soil pollution both within the parks and in surrounding areas. The soils of the Tibetan Plateau, known for their high sensitivity to environmental changes, are particularly vulnerable to human activity. In this study, we examined the concentrations (mg/kg) of 10 metal elements (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Se, and Zn) in soils at depths of 0–10 cm, 10–20 cm, and 20–30 cm from the surface at three distances (500 m, 1000 m, and 1500 m from the park boundary) on the east, south, west, and north sides of the Tianzhu Industrial Park on the Qinghai-Tibet Plateau. The concentrations of As, Cr, Mn, and Pb were close to the standard reference values for the Qinghai-Tibet Plateau, while Cu, Ni, Se, and Zn levels were found to be 1.6-2.2 times higher than the reference values. Cd and Hg concentrations were particularly concerning, at 8.0 and 6.5 times higher than reference values, respectively. The potential ecological risk indexes indicated persistent risk levels for Cd and Se across various directions and distances. Variations in soil depth and direction were observed for the concentrations of As, Cd, Hg, Pb, Se, and Zn, underscoring the need for regular or long-term monitoring. Cd, in particular, presents a significant hazard due to its high concentration and its propensity for uptake by plants in the study area.

Total mercury exposure through canned tuna in water sold in Quito, Ecuador.

Mercury is a toxic trace metal found in seafood products owing to its bioaccumulative and ubiquitous nature. Seafood and fish are frequently consumed, being necessary to assess its human health risk. Accordingly, this study quantified total mercury in samples of canned tuna in water from supermarkets in the Metropolitan District of Quito in Ecuador, in order to ensure that Hg content is within the maximum limits stablished in national and international regulations. Total mercury levels were measured through cold vapor atomic fluorescence spectrophotometry. Three of the most consumed tuna brands in Ecuador were analyzed, coded as A, B, and C, according to the price at which they are sold in the market (A < B < C). Results indicated that mean total mercury in different tuna brands were within the permissible limits. Total mercury concentrations were 0.14 ± 0.11mg kg-1; 0.41 ± 0.42mg kg-1; and 0.25 ± 0.22mg kg-1 for brands A, B, and C, respectively. However, for brand B the potential non-carcinogenic risk of mercury for consumers exceeded the threshold limit (> 1). When considering the highest total mercury content to which Ecuadorian population is exposed through the consumption of brand A, B, and C, the recommended weekly intake for children and adults were: A: 63g and 306g; B: 12g and 57g; C: 30g and 144g, respectively.

Tibetan Peat Records Global Major Explosive Volcanic Eruptions in the Holocene

AbstractMajor explosive volcanic eruptions were important triggers of abrupt climate changes during the Holocene and crucial sources of Hg to the atmosphere, yet there remains limited understanding regarding the long‐range transportation of this volcanic Hg and its imprint in natural archives. Here, we present a reconstruction of Holocene global volcanism based on the anomalies in Hg concentrations, accumulation fluxes, and Hg/C ratios in three high‐resolution peat profiles spanning Eurasia. Our reconstruction reveals that the two Tibetan peat profiles recorded 33 major explosive volcanic eruptions (with 11 eruptions being synchronously detected), which correspond with a French Pyrenees peat record and sulfate anomalies in polar ice cores. Additionally, the major explosive volcanic eruptions recorded in the TP peat profiles coincided with abrupt decreases in solar irradiance during the Holocene, suggesting these eruptions might have had a greater global climate impact. Our results suggest the atmospheric transport of volcanic Hg within the Northern Hemisphere and underscore the significant role played by major explosive volcanic eruptions in precipitating abrupt global climate and environmental changes during the Holocene. This study has implications for deciphering the configuration of volcanic eruption seasons, locations, and magnitudes during the Holocene and aligning the chronology of peat deposits with ice cores.

Health risks of potentially toxic elements in Cyprinus carpio in the karst plateau lake, China.

Elevated potentially toxic elements (PTEs) in aquatic products could threaten the health of ordinary consumers. Levels of chromium (Cr), arsenic (As), lead (Pb), and mercury (Hg) in Cyprinus carpio in karst plateau freshwater Lake, Caohai Lake, China were quantified using inductively coupled plasma mass spectrometry (ICP-MS) and evaluated using a risk method with Monte Carlo simulation. Levelsof Cr, As, Pb, and Hg in muscle tissue were substantially lower than those in viscera. The maximum concentration of muscle-bound Cr, As, Pb, and Hg were less than the standard references set by Chinese Food Codex (GB 2762-2022). The levels of Cr, As, Pb, and Hg in muscle tissue were independent of fish weight and length. The hazard index of all investigated elements in muscle tissue wereless than one for adults and children, whereas the target hazard quotients of muscle-bound PTEs for children were higher than those for adults. Results indicated that exposure duration was the largest contributor to the hazard quotient of Cr, As, and Hg, whereas the concentration of Pb in muscle was the most sensitive factor affecting the variation in hazard quotient of Pb. There is no risk related to the normal intake of muscle-bound Cr, Pb, As and Hg with the consumption of Cyprinus carpio. A better definition of the probability distribution for exposure duration and PTEs concentration could result in a more accurate hazard quotient. © 2024 Society of Chemical Industry.

Heavy metal contamination and potential health risks in upland rice-producing soils of rotational shifting cultivation in northern Thailand

Rotational shifting cultivation (RSC) is commonly practiced in northern Thailand for upland rice cultivation, primarily for household consumption. However, the potential health risks from heavy metal contamination in these soils have not been thoroughly explored. This study aimed to evaluate the contamination of six heavy metals (Arsenic (As), Mercury (Hg), Cadmium (Cd), Lead (Pb), Copper (Cu), and Chromium (Cr)) in upland rice across RSC fields with varying fallow periods and assess the associated health risks from rice consumption. Four RSC fields with 5, 6, 10, and 12-year fallow periods were examined. The RSC-6Y and RSC-12Y fields were used for upland rice cultivation in 2022, while the RSC-5Y and RSC-10Y fields were cultivated in 2023. The geo-accumulation index (Igeo) was calculated, and translocation factors (TF) were assessed for the transfer of heavy metals from soil to straw (TFStraw/Soil), straw to grain (TFGrain/Straw), and soil to grain (TFGrain/Soil). The results indicated that after burning vegetation in the RSC fields, the highest concentrations of Pb, Cr, and Hg were found in the ash. In RSC soils, Cu, Cr, As, Pb, and Hg levels were below reference standards, with Cd undetected. In rice grains, the order of concentration was Pb > Cu > Cr > As, with Hg and Cd undetected. Pb levels in rice grains exceeded the safety threshold. Igeo values indicated no contamination to moderate contamination across sites, with negative Igeo values for Cr and Cu, and zero values for Cd. The TF results showed limited transfer of As, Hg, and Cd from soil to rice plants (TFStraw/Soil < 0.1), but notable transfer for Pb, Cr, and Cu. Pb was readily transferred from soil to grain (TFGrain/Soil), posing a potential health risk. The study highlights potential non-carcinogenic and carcinogenic risks from heavy metal exposure, particularly Pb, and underscores the need for further research to determine contamination sources and mitigation strategies.

Risk assessment and sources associated with potentially toxic elements in suspended particulate matter: A karst river perspective in active mining area

Study regionDaiyang River Basin, a typical karst river basin impacted by mining activities in Guizhou, Southwest China. Study focusRivers are fundamental components of regional water security, but they are facing potentially toxic elements (PTEs) pollution caused by mining activities. This study investigated the concentration, behavior, risks and sources of nine PTEs in suspended particulate matter (SPM) from mining-impacted karst rivers, which are essential for the safety and management of karst water environments. New hydrological insights for the regionThe contents of Cr, Ni, Cu, Zn, As, Cd, Sb and Hg exceeded the corresponding local soil background values, with Zn and Cu being the most important pollutants. These elements caused a very high potential toxicity risk to the basin and unacceptable carcinogenic and non-carcinogenic risks to the local residents. Correlation analysis and the positive matrix factorization (PMF) model indicated that Ni, Cd, Zn and Cu were mainly derived from mixed sources of geological background and anthropogenic activities (30.95 %), Hg, Sb, and As were related to coal mining and combustion sources (28.91 %), while Pb, As, Cr and Sb were mainly contributed by natural sources (40.15 %). Furthermore, mixed sources, mining-related sources and As were identified as priority control factors in the study area. These insights can provide powerful support for decision-makers to develop control policies and reduce PTEs pollution in karst areas.

Analysis of heavy metal characteristics and health risks of edible mushrooms in the mid-western region of China

This study determined the content of metal elements (As, Cd, Cr, Hg, Pb) in 9 edible mushrooms using ICP-MS, and evaluated the harm of long-term consumption of edible mushrooms to human health. The results showed that the concentrations of metal elements decreased in the order of Cd > As > Cr > Pb > Hg in edible mushrooms. The concentrations of Cd, As, Pb, and Hg were 22.95%, 8.20%, 1.64%, and 3.28% higher, respectively, than the maximum standards in China, whereas Cr did not exceed the limit. The detection rate of metal elements in Morchella esculenta (L.) Pers (M. esculenta), and Agaricus blazei Murill (A. blazei) were relatively high. The results of single factor evaluation and target hazard coefficient (THQ, HI) indicated that Dictyophora indusiata (Vent.ex Pers) Fisch (D. indusiata), A. blazei and M. esculenta were the main sources of risk. In addition, the HI values in ascending order were: Pb (0.43) < Cr (0.68) < Hg (0.92) < Cd (7.21) < As (14.02), indicating that Cd and As were the primary sources of health risks in edible mushrooms. To ensure food safety, it is recommended to strengthen the supervision of edible mushrooms, make reasonable choices, and reduce exposure levels of heavy metal pollution.

Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA

Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by various source inputs to the lake and complex biogeochemistry. Here, we leverage Hg and Pb stable isotopes to track relative changes in metal source contributions to Great Salt Lake over time. Mercury and Pb concentrations increase in sediments deposited after 1920 and peak between 1965 and 1995, following closure of several local smelters and the onset of increased emission controls. The nominal associations above are confirmed via Hg stable isotopes in pre-1920 background sediments, which reflect atmospheric inputs from regional and global origin, whereas Hg and Pb stable isotopes together indicate that elevated metal concentrations in mid-late 20th century sediments reflect increased mining/smelting inputs. The observed minimal rebound towards pre-1920 Pb isotope signatures in 21st century sediments indicates that mining/smelting inputs, though reduced, remain a primary source of Pb to Great Salt Lake. In contrast, the more pronounced rebound of Hg stable isotope signatures to pre-1920 values indicate a greater contribution of atmospheric inputs of regional/global origin to current Hg inputs, though Hg concentrations are ~10 times greater than pre-1920 background values due to global increases in atmospheric Hg concentrations or possibly slow recovery from local contamination. The importance of regional/global Hg sources to the system suggests that reductions in Hg bioaccumulation in the open water food webs of Great Salt Lake are more dependent on national and global reductions in Hg emissions and management strategies to limit methylmercury production within system. This work highlights the utility of using coupled Hg and Pb stable isotope values to assess trace metal pollution sources and pathways in aquatic systems.

Mercury monitoring in farmed Pacific bluefin tuna (Thunnus orientalis) using liquid asymmetric-electrode plasma optical emission spectroscopy: Ventricle tissue as a potential indicator

Tuna muscle is known to contain high levels of mercury, necessitating the monitoring of mercury concentrations in farmed fish at production sites. There is currently no straightforward in on-site method for testing whether the mercury levels in farmed tuna exceed regulatory limits. This study investigated the potential application of liquid asymmetric-electrode plasma optical emission spectroscopy (LAEP-OES) to estimate mercury concentrations in the tissues of cultured Pacific bluefin tuna at aquaculture farms. No significant differences in mercury concentrations were observed between the ventricle tissue and biopsied tissue from tuna bleeding site (TTBS), which can be harvested without reducing the market value of farmed tuna (Hg concentration of the ventricle tissue and the TTBS, median: 0.41 and 0.40 mg/kg, respectively). In addition, the relationship between mercury concentrations in the ventricle tissue and in the edible portions of three tuna fish was examined. The findings showed that total mercury level in the edible tissues varied, with the ratio of the mercury level in edible tissues to that in the ventricle ranging from 0.39 to 1.08. A positive correlation was observed between the average total mercury levels in edible tissues and ventricle tissue. These results suggest that determining the total mercury level in the ventricle, which is typically discarded at processing sites, may serve as a convenient proxy for quality control and monitoring purposes using the LAEP-OES method. However, larger sample sizes are needed to validate the proposed approach more robustly.

The MoS2/rGO embed in macro-porous PAN gel as a novel DGT binding phase for the rapid and accurate detection of trace Hg(II)

The development of binding gels with a fast uptake rate, high capacity, and good selectivity could be beneficial for trace Hg(II) detection based on the DGT technology. In this study, a novel PAN@MoS2/rGO-DGT was assembled by using the nanocomposite embedded in polyacrylonitrile membrane (PAN@MoS2/rGO) as the binding phase. The interior regular finger-like macropore of the gel provided a convenient channel for the rapid mass diffusion of Hg(II), and the abundant sulfur offered the paramount driving force for trapping Hg(II). These endowed the PAN@MoS2/rGO with an impressive reaction rate, capacity, and selectivity toward Hg(II) and featured the PAN@MoS2/rGO-DGT with excellent diffusion rate (D) and adaptability in the complex matrixes across a wide range of pH, ion strength, common cations. However, the uptake of Hg(II) was influenced by the high content of chloride, thus a calibrated model was established based on the chloride concentration to correct the accumulated mass and D. After that, the high accuracy of this method was confirmed through the good consistency between Hg(II) concentration assessed by DGT and in bulk solution when the DGT was deployed to the river water, seawater, and domestic wastewater at the static and dynamic Hg(II) concentration. Field trials in the prawn farming seawater and lake water also showed a negligible deviation of Hg(II) content from the DGT and the conventional method, acquiring the actual Hg(II) level as 1.07-3.69 ng/L. The findings highlighted the application potential of macropore PAN gel hybrid with nanocomposite as a promising binding phase for trace Hg(II) or other pollutant detection.

Interplay and long-lasting effects of maternal low-level Pb, Hg, and Cd exposures on offspring cognition

Lead (Pb), mercury (Hg), and cadmium (Cd) are prevalent and persistent environmental contaminants, causing detrimental effects on millions of individuals worldwide. Our previous research demonstrated that early-life exposure to low-level Pb, Hg, and Cd mixtures may lead to cognitive impairments. However, the association and interaction among low levels of Pb, Hg, or Cd exposure remains unclear. In this study, a two-level full factorial design (5.481, 0.036, and 2.132 mg/L for Pb, Hg, and Cd respectively) was conducted to assess the interplay among maternal Pb, Hg, and Cd exposure on offspring cognition. Following exposure during pregnancy and lactation, a competitive absorption among Pb, Hg, and Cd was observed. Maternal exposure to each metal alone resulted in higher blood and brain concentrations of Pb, Hg, and Cd in offspring compared to co-exposure at equivalent levels. However, behavioral experiments conducted in the Morris water maze and novel object recognition test revealed maternal Pb, Hg, and Cd exposure synergistically impaired offspring's spatial cognition and recognition memory. Importantly, this dysfunction persisted into middle age even without exposure after adulthood. Moreover, the open field test and elevated plus maze indicated maternal low-level Pb, Hg, and Cd co-exposure triggered risk-taking behavior in weaning offspring, with a significant main effect for Pb exposure. No long-lasting effect on risk-taking behavior was detected in middle-aged offspring. Further investigation into molecular mechanisms showed that the dysregulation of corticosterone reaction and immune response might be the potential mechanism underlying Pb, Hg, and Cd co-exposure-induced cognitive impairments. Our study highlights the synergistic and long-lasting effects of multiple heavy metal exposures,underscoring the urgency to prevent exposure to metal mixtures among children and women of childbearing age.

Novel Zn-based Metal Coordination Polymer for Ultrafast Capture and Electrochemical Sensing of Hg(Ⅱ)

The electrochemical sensor shows great promise in the detection of trace Hg(Ⅱ), of which the performance could be significantly enhanced by the functionalized material with the merits of effective and ultrafast capture for Hg(Ⅱ). In this study, the novel metal coordination polymers (MCPs) was synthesized by the 2-thio-barbituric acid as the organic ligand to modify the electrochemical sensor to address this issue. The as-prepared material was composed of regular flakes with a polyhedral and well-defined crystal structure, the successful loading of the abundant sulfurous group (7.49% of the total mass) endowed the Zn-TBA with the capability to efficiently uptake (97.4-99.9%) Hg(Ⅱ) at 500mg/L under a wider pHs as well as the high content of coexisting cations and anions, highlighted the excellent capacity, strong environmental adaptability, and selectivity. Notably, the superfast mass transfer was revealed in the adsorption kinetics test, in which the Hg(Ⅱ) content was effectively reduced from 50mg/L to 14 μg/L within 20s to meet the national emission standards. Based on this, Zn-TBA modified the carbon cloth (Zn-TBA/CC) and the glass carbon electrode (Zn-TBA/GCE) was prepared, thereinto, the current response of Zn-TBA/CC was approximately 60 times that of the pristine electrode. A strong positive correlation (R2=0.998) relationship could be attained across the content of 0.25-3μM, achieving the detection limit to be 0.29μM. The impressive performance was maintained in the complex matrices and regeneration test. In addition, Zn-TBA/CC exhibited better physical properties, charge transfer ability, and sensing properties than Zn-TBA/GCE, highlighting the advantages of CC as a flexible sensor substrate. Finally, the stable recovery (90-98.5%) in the spiked actual surface water confirmed that the two established methods possessed a promising application potential in capturing and detecting the trace Hg(Ⅱ) with high accuracy and precision. This study extended the application of MCPs in the electrochemical sensor and provided an available analysis method to trap and determine the metal content.

Mercury Speciation and Stable Isotopes in Emperor Penguins: First Evidence for Biochemical Demethylation of Methylmercury to Mercury-Dithiolate and Mercury-Tetraselenolate Complexes

Apex marine predators, such as toothed whales and large petrels and albatrosses, ingest mercury (Hg) primarily in the form of methylmercury (MeHg) via prey consumption, which they detoxify as tiemannite (HgSe). However, it remains unclear how lower trophic level marine predators, termed mesopredators, with elevated Hg concentrations detoxify MeHg and what chemical species are formed. To address this need, we used high energy-resolution X-ray absorption near edge structure spectroscopy paired with nitrogen (N) and Hg stable isotopes to identify the chemical forms of Hg, Hg sources, and species-specific δ202Hg isotopic values in emperor penguin, a mesopredator feeding primarily on Antarctic silverfish. The penguin liver contains variable proportions of MeHg and two main inorganic Hg complexes (IHg), Hg-dithiolate (Hg(SR)2) and Hg-tetraselenolate (Hg(Sec)4), each characterized by specific isotopic values (δ202MeHg = 0.3 ± 0.2‰, δ202Hg(SR)2 = −1.6 ± 0.2‰, δ202Hg(Sec)4 = −2.0 ± 0.1‰). Using δ15N as a tracer of food source, we show that Hg(SR)2 is likely not obtained through dietary intake, but rather is present as a biochemical demethylation product. Furthermore, on average, female penguins transferred Hg to the egg strictly as MeHg in the egg albumen but as mixtures of MeHg and IHg in the membrane (89% and 11%, respectively) and yolk (32% MeHg and 68% Hg(Sec)4). Despite IHg species in eggs, MeHg is still the main species quantitatively transferred by the mother to the chick because of the disproportionate mass of the MeHg-rich albumen compared to the yolk. This work highlights the transformation of MeHg to Hg(SR)2 during demethylation for the first time in multicellular organisms, but further work is needed to understand the formation of Hg(SR)2 in the presence of relatively abundant Se biomolecules in lower trophic level predator species.

Contamination and health risk assessment of potentially toxic elements in rice (Oryza sativa) and soil from Ashanti Region.

Anthropogenic activities release potentially toxic elements into the environment, which contaminate the food chain. The main objective of this research was to analyze the concentrations of As, Cd, Cr, Hg, and Pb in rice grains and soils, establish their correlation and transfer factors between soil and rice grains as well as evaluate their human health risk from consumption of rice cultivated in the Asante Akim area. The levels of As, Cd, Cr, Hg, and Pb in soil and rice samples were assayed using an Agilent 7700 Series inductively coupled plasma-mass spectrophotometer. The mean heavy metal content in soil was 7.5, 0.52, 0.47, 1.30, and 8.69mg/kg for As, Cd, Cr, Hg, and Pb, respectively. Mean levels of the potentially toxic elements in rice were 0.082, 0.27, 0.48, 0.028, and 0.14mg/kg for As, Cd, Cr, Hg, and Pb, respectively. Soil pollution indices showed that the soils were unpolluted with the potentially toxic elements studied. The concentrations of the potentially toxic elements in rice were below the maximum allowable concentration (MAC) recommended by the Codex Alimentary Commission except Cd which was marginally higher than the MAC. Dietary exposure to the elements to consumers was assessed by comparing the estimated daily intake (EDI) to the provisional tolerable daily intake (PTDI). The estimated daily intake values for As, Cd, Cr, Hg, and Pb were 1.45 × 10-4, 4.8 × 10-4, 8.5 × 10-4, 4.95 × 10-5, and 2.4 × 10-4, respectively. The HQ for all the potentially toxic elements was less than the permissible value of 1, suggesting that the consumption of rice from the study area constitutes no potential non-carcinogenic health risk to the population. This study is unique because the risk is evaluated from rice that is directly consumed, and this gives a clearer picture of the risk to humans. Regular monitoring studies should be conducted to ascertain the levels of heavy metals in rice cultivated in the area since heavy metals can accumulate and the concentrations could increase to toxic levels with time.

Trace Metal Elements (TMEs) in Groundwater Around the Former Industrial Gold Mine of Poura in Burkina Faso – West Africa

The objective of this study is to assess the quality of groundwater around the first industrial mine in Burkina Faso, whose activities have been closed since 1999. The diagnosis of pollution by trace metal elements of groundwater around the old Poura gold mine was carried out through the determination of the contents of Trace Metal Elements (TME) at MP-AES and the measurements of the physicochemical parameters in situ on 38 samples of borehole water. These data made it possible to calculate the pollution risk index, to establish correlations between the different physicochemical parameters on the one hand and with the trace metal elements on the other hand, from the Pearson matrix and to carry out a multivariate statistical analysis, in particular that in principal components (PCA), with a view to determining the origin of the polluting elements. The results obtained made it possible to identify four samples of groundwater with an acidic pH (GWF18 (6.44), GWF19 (6.39), GWF23 (6.1) and GWP01 (5.99)) and 34 samples of groundwater whose Cd, Al, Fe, As, Pb, or Hg contents are higher than the standards in force in Burkina Faso. The Pollution risk Index (PI) indicates that 35 groundwater samples are slightly polluted and 3 groundwater samples are very heavily polluted (GWP01 (PI = 456%), GWF06 (PI = 132.5%), GWF03 (PI = 105.1%)). The Pearson correlation matrix and the principal component analysis (PCA) show that the origin and mobilization of the trace metal elements involved (Al, As, Cd, Cr, Fe, Hg and Pb) are linked to natural mineralization and anthropogenic activities such as mining and agricultural activities, favored by the infiltration of water into the subsoil through geological structures such as fractures and faults.

Unveiling mercury exposure sources in e-waste recycling with biomonitoring - A Portuguese case study

Abstract Background Mercury (Hg), a global pollutant, poses risks to both human and environmental health. The management and recycling of electrical and electronic waste (e-waste) is recognized as having the potential to promote workers’ exposure to this pollutant. Human biomonitoring (HBM) is a tool that can be used to evaluate exposure and monitor the health of workers. The objective of this study was to characterize exposure of workers from an e-waste recycling company and to analyze the relevance that HBM holds in the detailed characterization of exposure. Methods A cross-sectional observational study was conducted using data collected within the framework of the European Human Biomonitoring Initiative (HBM4EU). Data from environmental monitoring (settled dust) and biological monitoring (urine and hair) of 30 workers potentially exposed to Hg were analyzed in comparison with 12 unexposed workers from other occupational settings (controls). Results Exposed workers did not exhibit significantly higher concentrations of Hg in urine when compared to control workers. We found a significantly positive correlation between the concentration of Hg in urine (ρ = 0.688; p ≤ 0.001) and hair (ρ = 0.470; p ≤ 0.01) and the consumption of fish and shellfish. Conclusions Diet appears to be the most significant source of Hg in this context. These results suggest the importance of information and dietary habits to prevent mercury exposure. HBM stands out as an essential tool for identifying the most relevant exposure sources and risk management measures for workers and the general population. Key messages • Diet appears to be the most significant Hg source in workers from a Portuguese e-waste company. • HBM stands out as essential for identifying the most relevant exposure sources and risk management.