Hg Concentrations Research Articles

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.

Mercury speciation in environmental samples associated with artisanal small-scale gold mines using a novel solid-phase extraction approach to sample collection and preservation

In artisanal small-scale gold mines (ASGM), mercury (Hg) is known to pollute nearby river waters and sediments where it can be methylated to the highly bioavailable methylmercury (MeHg). The assessment of Hg speciation in water samples has been challenging for many years, with recommended procedures often not adequately allowing for analysis of samples in a suitable timeframe. Using a novel solid-phase extraction (SPE) method for sampling and preservation of Hg species, representative speciation data can be safely and easily collected and retained for up to 4-weeks (MeHg = 115 ± 8% refrigerated and 109 ± 13% unrefrigerated storage; Hg2+ = 100 ± 14% refrigerated and 94 ± 12% unrefrigerated storage). Concentrations of MeHg in environmental water samples and drinking water were below detection limit across two ASGM sites in western Kenya and concentrations of Hg2+ were below drinking water guidelines; however, drinking water sources contribute 20–30% of the tolerable weekly intake of Hg, indicating a need to minimise exposure of Hg from dietary sources to prevent Hg poisoning. Sediments from receiving rivers at ASGM sites showed total Hg concentrations above guideline limits (0.08–1.84 mg kg−1 total Hg) along the length of the river; however, MeHg concentrations fluctuated dependent on the stagnation of the river due to damns and ponds (5.9 ± 14.3 µg kg−1 MeHg). The findings show that SPE can be used as a robust sample collection and preservation approach for Hg speciation, which can better inform mitigation measures, understand ecological and human health implications, and improve environmental monitoring.

Spatiotemporal Distribution of Mercury in Tree Rings and Soils Within Forests Surrounding Coal-Fired Power Plants

The release of mercury (Hg) from coal-fired power plants (CPPs) into local ecosystems poses substantial environmental and health hazards. This study was conducted in Chungcheong-nam-do, South Korea, a region featuring over half of the country’s coal power facilities, to estimate the impacts of CPPs on Hg distribution in forest ecosystems. By analyzing Hg concentrations in pine tree rings and soil at 21 locations around CPPs and comparing them to control sites and industrial zones, we present a nuanced understanding of the effects of CPPs on Hg concentration. The analysis of Hg concentrations in tree rings showed a significant decrease in Hg levels as the distance from the power plants increased, suggesting that CPPs primarily influence Hg distribution in trees within a 25 km radius. In contrast, soil Hg concentrations did not exhibit a clear trend. This may reflect the limitations of this study in accounting for the physicochemical properties of the soil at each sampling site. Nevertheless, the Potential Ecological Risk Index for soil Hg contamination indicated a higher risk rating within a 1 km radius of the CPPs compared to other locations. Hg concentrations in tree rings have shown a steady decline since the 1970s, suggesting the positive effects of air pollution regulations. This also highlights the value of tree core samples as effective tools for monitoring historical Hg pollution. Furthermore, the higher historical concentrations of Hg in tree rings imply that trees may have acted as sinks for atmospheric Hg in the past.

Trends and risk assessment of heavy metals in the surface sediments of river-connected lakes: A case study of Dongting Lake

This study analyzed the spatiotemporal distribution characteristics, ecological risks, biological toxicity, and sources of Cu, Zn, Pb, Cd, Hg, and As in the surface sediments of Dongting Lake, as well as the response of benthic macroinvertebrates to these pollutants. Among the three lake regions, the concentration of Cu, Zn, Pb, Cd, and As fell in the order of South Dongting Lake (SD) > East Dongting Lake (ED) > West Dongting Lake (WD), whereas the concentration of Hg fell in the order of WD > SD > ED. The concentrations of Cu, Zn, Pb, and As were 1.69–2.02 times the background values recorded in 1986, whereas the concentrations of Cd and Hg were 8.97 and 5.32 times the background values, respectively. The ecological risk was low for Cu, Zn, Pb, As but high for Hg and Cd. For Dongting Lake in aggregate, the heavy metals caused considerable ecological risk and high biotoxicity, although the situation was improving in recent years. Cd, As, Cu, Pb, Hg were mainly from agricultural sources, mining sources, tire wear and agricultural sources, industrial smelting and mining sources, industrial processing and smelting sources, respectively, and Zn was from mixed sources. A total of 66 species of benthic macroinvertebrates were identified from the sediments. From 2018 to 2022, the dominant benthic macroinvertebrates gradually shifted from the pollution-resistant in Tubificidae to those in Gammarus, Bellamya, Valvatidae, etc. Oligochaetes and Stictochironomus spp. exhibited extremely high response to heavy metals and could serve as indicator organisms of heavy metal pollution.

Temporal variation of mercury levels in fish, soil, and sediments in an Amazon reservoir: insights from 35years of river impoundment in Pará State, Brazil.

The increase of mercury (Hg) concentrations in abiotic and biotic compartments of aquatic ecosystems following the river impoundment for building a hydroelectric reservoir is one of many environmental and social impacts that the construction of hydroelectric plants can trigger. Yet, long-term studies in Amazon reservoirs are still scarce. The present study aimed to understand the effects of dam impoundment in THg concentrations in an Amazon reservoir up to 35years of its creation. On March 2019 (35th year after filling), samples of fish, soil, and sediments were collected in the Tucuruí reservoir. Total mercury (THg) concentrations were determinate in those samples and compared with data extract from previous studies referring to the 6th, 16th and 18th years after the reservoir filling. Fish from different guilds at the 6th year after filling the Tucuruí reservoir had high THg concentrations, and those decreased in the 16th and 18th years, then the concentrations increased again in the 35th year after filling. For soils and sediments, a decline in THg concentrations was observed. These results differ from previous studies that predicted that Hg concentrations in fish would return to natural concentrations within 30years in temperate zones and no decline of THg concentrations would be observed for Amazonian reservoirs. The Tocantins river drainage basin has been subjected to multiple anthropic disturbances and land use changes over the past decades, such as the implementation of new hydroelectric plants, deforestation, and fires, which can explain our observations. This study contributes valuable long-term insights into the dynamics of Hg concentrations in an Amazonian reservoir, highlighting the complex interactions between environmental changes and Hg accumulation over decades.

Volatilization and cleaning recovery of Pb, Se and Hg in acid sludge of copper smelting system during vacuum distillation

The high lead acid sludge, containing a small amount of selenium and mercury, is a hazardous waste product of the copper smelting system. Improper disposal of this waste can cause serious harm to the environment. In this study, the method of vacuum distillation was proposed for treating the high lead acid sludge. The study aimed to investigate the volatilization rule of selenium, mercury, and lead in the acid sludge during vacuum distillation, as well as to purify PbSe and metallic lead. The results indicated that under 5 Pa, Hg and Se commence volatilizing at 300 ℃, the content of Hg in volatile substances remains relatively constant after reaching 400 ℃, demonstrating nearly complete volatilization at this temperature with a ratio of 92.93 %. Similarly, selenium almost completely volatilizes at 800 ℃ with a ratio of 96.74 %, while lead does so at around 1000 ℃ with a ratio of approximately 99.27 %. Mercury at 400 ℃ can be recovered as mercury selenide. Lead selenide can be achieved at 800 ℃, while lead sulfate can be decomposed and purified at 1000 ℃ to obtain metallic lead with a purity higher than 99 %. The method can properly treat and recover mercury, selenium, lead and other elements in the acid sludge with short process and no pollution, which provides a new cleaning approach for high lead acid sludge.

Mercury Detection in Novel Foods by a Smart Pocket Sensor

AbstractMercury is one of the most well‐known toxic contaminants of natural and anthropogenic origin in aquatic ecosystems that can bioaccumulate in vegetal and animal organisms. In this work, we propose a smart detection system for Hg(II) ions by square wave anodic stripping voltammetry at nanocomposite graphite screen‐printed electrodes, as an analytical tool to be applied in food quality control. The nanocomposite surfaces were obtained by the modification of screen‐printed graphite electrodes with poly(l‐aspartic acid) and gold nanoparticles and were characterized by means of electrochemical techniques. An exhaustive study of the experimental conditions involved both in the electropolymerization and in the voltammetric stripping measurements was addressed to develop a reliable method capable of measuring Hg(II) concentration in the low μg/L range, both in conventional and drop configurations. The sensor was integrated in a smart setup, comprising a Sensit Smart pocket instrument connected to a smartphone, thus proving its applicability for in situ analysis due to its cost‐effectiveness. The analytical significance of the developed sensor was assessed by detecting Hg(II) in novel food samples.

Uptake, Efflux, and Sequestration of Mercury in the Asian Clam, Corbicula fluminea, at Environmentally Relevant Concentrations, and the Implications for Mercury Remediation

(1) Mercury (Hg) is a persistent, ubiquitous contaminant that readily biomagnifies into higher trophic level species in aquatic environments across the globe. It is crucial to understand the movement of environmentally relevant concentrations of Hg in impacted freshwater streams to minimize risks to ecological and human health. (2) The bioconcentration kinetics of aqueous Hg exposure (20, 100, and 200 ng/L) in the invasive Asian Clam, Corbicula fluminea, were measured. A toxicokinetic model, the first parameterized for Hg accumulation in freshwater clams, was developed to estimate uptake and efflux parameters and compared to previous parameter values estimated for other mollusk species. (3) Results demonstrated that even at low Hg concentrations, Corbicula record signals of contamination through bioconcentration, and both direct measurement and toxicokinetic models demonstrate large Hg bioconcentration factors (as high as 1.34 × 105 mL/g dry tissue), similar to partitioning coefficients seen in engineered Hg sorbents. (4) Our study found that Corbicula accumulated Hg at aqueous concentrations relevant to impacted streams, but well below regulatory drinking water limits, demonstrating their utility as a sensitive sentinel species and potential bioremediator.

Magma Degassing andGoldMineralizationinthe Alkaline Intrusion- HostedGiltEdgeGoldDeposit,NorthernBlackHills, SouthDakota,USA

Gold mineralization in the Gilt Edge deposit was closely associated with magmatic differentiation and the formation of a Tertiary alkaline intrusive complex within the Lead–Deadwood dome.. Fluid inclusions and trace element geochemistry were used to study fluid evolution and determine sources. Quartz disseminated in unaltered trachyte porphyry hosts two populations of primary inclusions: 1) hypersaline i S–L–V a red hematite crystal and 2) mixtures of L–V and V– L that record phase separation at ~700oC. Whereas samples of hydrothermal quartz collected from in ore zones within and beyond structures (e.g., fault and breccia zones) contain dominant populations of V–L and L–V inclusions, respectively. Mineralization in structures formed from complex fluids of magmatic origin based on inclusions containing five transparent salt crystals and opaque crystals with cubic and round habits that have homogenization temperatures (Th) 650oC and salinities 63 wt.% NaCl equiv. In contrast, broader areas of disseminated mineralization in argillized and propylitized rocks contain hydrothermal quartz hosting large populations of L–V inclusions with Th of 200o360oC and salinities of 10–30 wt.% NaCl equiv., which reflect fluid mixing. Trace element concentrations are significantly higher in samples from structures and define zones of near surface Ag–As–Zn–Pb and deep Au–W–Mo–Cu. Whereas low trace element concentrations characterize propylitized quartz trachyte porphyry, except for high concentrations of Sb and Hg that occur at depth and likely track the retreat of isotherms as the hydrothermal system collapsed. These data show that during differentiation in a deep magma chamber, volatile-rich low-density fluids were periodically degassed into preexisting structures that were reactivated. Gold deposition during four stages of mineralization likely occurred due to boiling, changes in oxygen fugacity, and fluid mixing.

Biomonitoring of Mercury and Lead Levels in the Blood of Children Living near a Tropical River Impacted by Artisanal and Small-Scale Gold Mining in Colombia.

(1) Background: Mercury and lead contamination resulting from various anthropogenic activities represents a global environmental problem and a considerable risk to the health of the human population. (2) Methods: The objective of this research was to evaluate the concentrations of mercury (Hg) and Lead (Pb) in the blood of the child population in the municipalities in the Atrato River basin using a direct Hg analyzer and graphite furnace atomic absorption spectrometry. (3) Results: In total, 171 children (5-14 years of age) were taken into account, and 18.71% (32) of the children had concentrations of Hg and Pb above the permissible values established by the WHO. In the municipality of UN, 19 children had blood Hg concentrations between 5.29 and 17.71 μg/L. In CA, two children had concentrations of 5.03 and 8.43 μg/L, separately. In the case of Pb, seven children showed concentrations between 3.60 and 4.83 μg/dL in the municipality of RQ, three in UN (3.59, 3.61, and 4.60 μg/dL), and one in Carmen de Atrato (5.47 μg/dL). (4) Conclusions: The levels of Hg and Pb in the blood of children living in the riparian areas of the Atrato River basin are related to gold mining activities in the basin and the consumption of contaminated fish.

Trace element contamination biomonitoring: A comparative study between the polychaetes Alitta virens and Hediste diversicolor

Trace elements (TEs) remain of significant toxicological concern as many are critical for global decarbonisation. TEs accumulate in sediments so benthic polychaetes (e.g. Hediste diversicolor and Alitta virens) are highly relevant for ecotoxicology. However, ecological/biological differences could influence TE accumulation and biomonitoring suitability. Exploiting multiple sympatric populations (Solent, UK), we measure sediment and tissue concentrations generating EFs (enrichment factors), AEIs (Adverse Effects Indexes) and tissue bioaccumulation factors. We also assess stable isotope compositions to elucidate diet influences. Despite diverse anthropogenic activity in the Solent, the majority of TEs present low levels of sediment contamination at the sites. For Ni, Pb and As, a combination of mean AEIs >1 and some sediment concentrations exceeding SQVs (Sediment Quality Values) indicate a slight toxicological risk. For Cu and Hg, high EFs and AEI scores confirm they are the greatest risk, thus requiring source identification/control. However, only mean As tissue concentrations reflect contaminated sites, therefore, identifying the As-source(s) is also a priority. Sediment and tissue concentration relationships were generally negative and not significant for both species. Although a significant negative relationship for Cd for A. virens requires further investigation, the lack of evidence for TE bioaccumulation from sediment may limit both species' biomonitoring suitability for low-contamination sites. Species differences in tissue concentration were also TE specific: H. diversicolor had significantly higher concentrations for Ag, Cu, Hg, Ni and Zn, whilst the reverse was true for Cd, Fe, Cr and As. Whilst ecological differences and that feeding sources are site and species-specific (as evidenced by C, N and S stable isotopes analysis) cannot be ignored, the diverse tissue concentrations strongly suggest different TE regulation strategies per species. Together these data will be important for ecotoxicologists and regulators to select the ‘best’ polychaete biomonitor and assess TE toxicity under future global decarbonisation trajectories for TE inputs.

Presence of Mercury in an Arid Zone of Mexico: A Perspective Based on Biomonitoring of Mammals from Three Trophic Guilds.

Mercury (Hg) has been extensively studied due to its impact on the environment and health, but its effects on wild mammal populations are still poorly known. Therefore, the use of biomonitors has gained importance. Our objective was to report and compare, for the first time, the amount of mercury in small mammals belonging to three trophic guilds and to provide an initial toxicology perspective in the Mezquital Valley, a critically polluted area of Central Mexico. We quantified total Hg from the hair and liver of a nectarivorous bat (Leptonycteris yerbabuenae), an insectivorous bat (Corynorhinus townsendii) and a granivorous mouse (Peromyscus melanophrys) using atomic absorption spectrometry during the dry and rainy seasons. We compared the mercury concentrations between seasons, species and matrices. In all species, the average mercury content was higher in hair than liver, and there was no correlation between matrices. There was no difference in mercury content among species. Hg concentrations in the livers of P. melanophrys and C. townsendii were lower during the dry season than the rainy season, suggesting a seasonal decline in mercury availability. All of the values detected were below the neurotoxicity threshold reported in small mammals (10 ppm); however, we propose constant monitoring of Hg in their environment and confirm the utility of these species as biomonitors.

Pollution of Heavy Metals in Topsoil of Remote Mountainous Areas in Western Yunnan-Guizhou Plateau

Heavy metals from anthropogenic emissions have had a negative impact on the ecological environment in remote regions. A total of 69 topsoil samples were collected from 13 remote mountainous areas in the western Yunnan-Guizhou Plateau at altitudes of 2 563-4 037 m, and the concentrations of ten heavy metals in the samples were determined. Enrichment characteristics and pollution sources of heavy metals in topsoil were discussed by referencing the enrichment factor （EF）, positive matrix factorization （PMF）, and Pb isotopes. The results showed that the average concentrations of Al, Fe, Cu, V, and Zn in the topsoil were lower than the soil background values in Yunnan Province； the average concentrations of Ni and Pb were similar to the background values； and the average concentrations of Cd, Cr, and Hg were 1.8-3.6 times higher than the background values. The average EF values of Pb, Cr, and Ni were 3.8, 3.4, and 2.3, respectively, showing moderate enrichment according to the EF classification criteria； the average EF values of Cd and Hg were 15.2 and 10.0, reflecting significant enrichment； and the average EF values of the other metals ranged from 1.1 to 1.9, displaying none-weak enrichment. Combining the comparisons of heavy metal concentrations and ratios in topsoil and bedrock and the EF and PMF results, Al, Fe, V, Cr, Cu, Ni, and Zn in topsoil were considered primarily from detrital sources, and the spatial concentration variations of the metals should have been mainly regulated by the parent material. Cadmium, Hg, and Pb were obviously polluted by anthropogenic emissions, and the main sources were non-ferrous metal smelting and coal combustion. The areas with relatively high Cd, Hg, and Pb pollution were mainly distributed in the Jiaozi snow mountain, Bitahai watershed, Luoji Mountain, and Laojun Mountain areas. Anthropogenic emissions contributed 23.8% of the accumulation of heavy metals in the topsoil.

Machine learning-assisted risk evaluation of heavy metals in the Hainan gold mining region, China.

This study employed machine learning (ML) to thoroughly investigate the impact of informal mining activities on the distribution and pollution status of heavy metals in soils near private gold mines in Hainan Province, southern China, a region known for its ecological sensitivity and economic importance. By systematically collecting surface soil samples and samples at depths of 0.5-1m from 175 drilling sites, a comprehensive quantitative analysis was conducted on major heavy metal elements, including lead (Pb), copper (Cu), cadmium (Cd), nickel (Ni), mercury (Hg), chromium (Cr), arsenic (As), and zinc (Zn). Combined with evaluation methods such as the Pollution Load Index (PLI), Normalized Pollution Index (NIPI), and Ecological Risk Index (ERI), the study revealed a high level of soil pollution at informal mining sites. The findings indicated that the average concentrations of Pb, Cd, Hg, As, and Zn in surface soils significantly exceeded the background values for soils in China, with a pronounced positive correlation observed between these heavy metal elements in both surface and deep soil profiles (r > 0.5). Furthermore, leveraging the heavy metal content in surface soils and the constructed environmental indicators, the predictive accuracy for metal content in deep soils was found to range from R2 = 0.27 to 0.68, suggesting that informal mining activities have led to substantial variations in metal content across different soil profiles. Through the application of a random forest model for predictive analysis of the PLI, NIPI, and ERI, high prediction accuracy was achieved (R2 = 0.78, 0.86, and 0.60, respectively). The study demonstrates that informal mining activities not only elevate the risk of soil pollution but also alter the distribution patterns of heavy metals. Also, this study provides a crucial foundation for the scientific assessment of soil quality and potential environmental hazards, while also affirming the efficacy of ML techniques in forecasting soil quality parameters.

Characteristics, Source Apportionment, and Health Risk of Heavy Metals in the Soils of Peri-urban Shanghai Chongming Island.

Heavy metals resulting from human activities pose significant threats to human health and the soil ecosystem. In the current study, 917 soil samples from Chongming Island in Shanghai, China, were examined for eight heavy metals. The sources of contamination were identified by using a Positive Matrix Factorization (PMF) model. Meanwhile, spatial interpolation and Moran's I index were applied to validate the model in terms of spatial linkages. The results revealed that the average concentrations of As, Cd, Hg, Pb, Cr, Cu, Zn, and Ni in the soil were 8.87, 0.19, 0.06, 28.75, 76.01, 37.74, 88.93, and 30.33 mg kg-1, respectively. The PMF analysis proved that heavy metals in the soil of the study area are mainly influenced by traffic sources (Cr and Pb), industrial sources (Zn, Cd, and Cu), station sources (Hg), and natural sources (As and Ni), with contribution rates of 22.23, 26.25, 36.38, and 15.14%, respectively. The combination of Moran's index and the spatial analysis method not only verified the analytical results of the receptor model on the one hand but also served as a supplementary explanation for the sources of heavy metals in the soil. The health risk assessment indicated that noncarcinogenic values were below the threshold values. The total carcinogenic risk (R T) of different heavy metals has a descending order of Cr > As > Ni > Cd. The R T values of multiple heavy metals for children and adults were 5.28 × 10-04 and 4.10 × 10-05, respectively, which were close to the risk threshold. Therefore, attention should be paid to the health risks, especially for children's skin contact, which is the main exposure pathway.

Unexpected anthropogenic emission decreases explain recent atmospheric mercury concentration declines.

Anthropogenic activities emit ~2,000 Mg y-1 of the toxic pollutant mercury (Hg) into the atmosphere, leading to long-range transport and deposition to remote ecosystems. Global anthropogenic emission inventories report increases in Northern Hemispheric (NH) Hg emissions during the last three decades, in contradiction with the observed decline in atmospheric Hg concentrations at NH measurement stations. Many factors can obscure the link between anthropogenic emissions and atmospheric Hg concentrations, including trends in the reemissions of previously released anthropogenic ("legacy") Hg, atmospheric sink variability, and spatial heterogeneity of monitoring data. Here, we assess the observed trends in gaseous elemental mercury (Hg0) in the NH and apply biogeochemical box modeling and chemical transport modeling to understand the trend drivers. Using linear mixed effects modeling of observational data from 51 stations, we find negative Hg0 trends in most NH regions, with an overall trend for 2005 to 2020 of -0.011 ± 0.006 ng m-3 y-1 (±2 SD). In contrast to existing emission inventories, our modeling analysis suggests that annual NH anthropogenic emissions must have declined by at least 140 Mg between the years 2005 and 2020 to be consistent with observed trends. Faster declines in 95th percentile Hg0 values than median values in Europe, North America, and East Asian measurement stations corroborate that the likely cause is a decline in nearby anthropogenic emissions rather than background legacy reemissions. Our results are relevant for evaluating the effectiveness of the Minamata Convention on Mercury, demonstrating that existing emission inventories are incompatible with the observed Hg0 declines.

Characterizing visual field loss from past mercury exposure in an Indigenous riverine community (Grassy Narrows First Nation, Canada): a cluster-based approach

BackgroundBetween 1962 and 1975, a chlor-alkali plant in Canada discharged approximately 9 metric tons of mercury (Hg) into the Wabigoon River. Over the following decades, biomarkers of Hg exposure of persons from Grassy Narrows First Nation (Asubpeeschoseewagong Anishinabek), located downriver from the discharge, reflected Hg concentrations in fish. Hg exposure is known to target the calcarine fissure, resulting in visual field (VF) loss. Most studies and clinical reports focus solely on peripheral VF loss; little is known about the impact of Hg on the central and paracentral portions. The present study sought to characterize the patterns of VF loss with respect to past and current Hg.MethodsA 28-year hair-Hg (HHg) database, created from a 1970–97 government biomonitoring program, served to select study participants with ≥ 4 year-based HHg measurements (n = 81). Blood-Hg was assessed for current exposure. Light sensitivity thresholds across the VF were analyzed monocularly, using a Humphrey Field Analyzer (HFA). Following post-hoc exclusions, based on HFA interpretation indices, 65 participants were retained. Both eyes were combined for analyses (n = 130 eyes). Unsupervised hierarchical clustering of HFA plot data was used to identify patterns of VF loss. A series of mixed effects models (MEM) were performed to test the associations for current Hg exposure with respect to HFA interpretation indices and clusters, as well as for longitudinal past Hg exposure.ResultsThe clustering approach decomposed the light sensitivity deficits into 5 concentric clusters, with greatest loss in the peripheral clusters. No relation was observed between any of the cluster scores and current blood-Hg. VF deficits increased with past Hg exposure. Longitudinal MEM showed that HHg was significantly (p < 0.05) associated with all peripheral, paracentral, and central cluster scores, as well as with HFA interpretation indices.ConclusionsPast Hg exposure in Grassy Narrows First Nation was associated with present day VF loss. The cluster-based location-specific approach identified patterns of VF loss associated with long-term Hg exposure, in both the peripheral and the central areas. The functional implications of this type of visual loss should be investigated.

Concurrent measurements of atmospheric Hg in outdoor and indoor at a megacity in Southeast Asia: First insights from the region

Atmospheric mercury (Hg) is a critical indoor (ID) air pollutant and necessitates stringent monitoring. However, studies have primarily focused on Hg outdoors (OD) compared to ID, with no investigations conducted within the Southeast Asia (SEA) region. In this study, total gaseous Hg (TGM) concentrations and human exposure levels were investigated across various site characteristics in Ho Chi Minh City (HCMC), a megacity in SEA. The measured TGM concentrations for OD and ID were 5.12 ± 6.87 ng m−3 (1.20–48.7 ng m−3) and 34.5 ± 60.3 ng m−3 (1.26–271.9 ng m−3). The overall ID/OD ratio was 5.01 (0.77–9.3), signifying markedly elevated ID TGM concentrations. This ratio increases in the following order: shopping malls (1.50) < hospitals (3.21) < chemical laboratories (5.76) < households (11.7). Notably, sites associated with Hg incidents and the utilization of Hg-contained chemicals demonstrate notably high ID/OD levels, ranging from 8.0 to 40.1. The use of Hg-containing chemicals within the chemical laboratory serves as a significant contributor to heightened ID TGM levels. Non-combustion Hg sources, therefore, play an important role in inducing the ID TGM level. The hazard index (HQ) values observed for ID and OD were 0.1 and 0.01, respectively, indicating a negligible risk of exposure to TGM within the study area. However, HQ values recorded within laboratory environments employing Hg-associated chemicals and dental hospitals were 1–17 times greater compared to other sites. The present work provides new insight into the non-combustion ID source of TGM and was helpful for upcoming studies in exploring potential sources of TGM in megacities.

Traces of the past: assessing the impact of potentially toxic elements from an abandoned mine on groundwater and agricultural soil in San Luis Potosí, México.

The study was conducted in Cerritos, San Luis Potosí, México, near the Guaxcama mine, focused on environmental contamination (groundwater and agricultural soil) from antimony (Sb), arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg). In March 2022, 20 agricultural soil and 16 groundwater samples were collected near the historically cinnabar (HgS)- and arsenopyrite (FeAsS)-rich Guaxcama mine. Hydride generation atomic fluorescence spectrometry (HG-AFS) for As, cold vapor atomic fluorescence spectrometry (CV-AFS) for Hg, and inductively coupled plasma optical emission spectrometry (ICP-OES) for Cd, Pb, and Sb were used for the determinations of potentially toxic elements (PTEs). While concentrations of Cd, Hg, Pb, and Sb in groundwater were below detection limits, As levels exhibited a range from 40.9 ± 1.4 to 576.0 ± 1.0µg/L, exceeding permissible limits for drinking water (10µg/L). In agricultural soil, As was between 7.67 ± 0.16 and 24.1 ± 0.4µg/g, Hg ranged from 0.203 ± 0.018 to 2.33 ± 0.19µg/g, Cd from 2.53 ± 0.90 to 2.78 ± 0.01µg/g, and Pb from 11.7 ± 1.2 to 34.3 ± 4.1µg/g. Only one study area surpassed the Mexican As soil limit of 22µg/g. Sequential extraction (four-step BCR procedure) indicated significant As bioavailability in soil (fractions 1 and 2) ranging from 3.66 to 10.36%, heightening the risk of crop transfer, in contrast to the low bioavailability of Hg, showing that fractions 1, 2, and 3 were below the limit of quantification (LOQ). Crucial physicochemical parameters in soil, including nitrate levels, pH, and organic matter, were pivotal in understanding contamination dynamics. Principal component analysis highlighted the influence of elements like Fe and Ca on phytoavailable As, while Pb and Cd likely originated from a common source. Ecological risk assessments underscored the significant impact of pollution, primarily due to the concentrations of Cd and Hg. Non-cancer and cancer risks to residents through As poisoning via contaminated water ingestion also were found. The hazard index (HI) values varied between 4.0 and 82.2 for adults and children. The total incremental lifetime cancer risk (TILCAR) values for adults ranged from 7.75E - 04 to 1.06E - 02, whereas for children, the values were from 2.47E - 04 to 3.17E - 03.

Antioxidant and Antibacterial Screening and Hg(II) Sensing, Activities of Cu(II)pyridine-2,6-dicarboxylate Complexes.

In this study five different complexes of Cu(II) were synthesized for the purpose of environmentally notorious mercury sensing and preliminary biological screening. Pyridine-2,6-dicarboxylic acid (also known as dipicolinic acid, and abbreviated as H2DPA), 3-phenyl pyrazole (3-ppz), 4-iodo-1H-pyrazole (4-ipz), 4-nitropyrazole (4-npz), 4-bromopyrazole (4-bpz), and 4-chloropyrazole (4-cpz) were chosen as potential ligands. The synthesized complexes labelled as 1-5, namely [Cu(DPA)(3-ppz)], [Cu(DPA)(4-ipz)], [Cu(DPA)(4-npz)], [Cu(DPA)(4-bpz)], [Cu(DPA)(4-cpz)], were proposed based on spectroscopic data (FTIR, TGA, and UV-visible spectroscopy). These complexes feature C=O functionalities that are not involved in coordination and may be used for further applications. The isolated complexes were utilized for detecting Hg(II) ions in water samples. Various concentrations of Hg(II) ions were prepared for detection purposes, and changes in absorption concerning complexes 1-5 were determined using UV-Visible spectroscopy. It was found that complexes 3 and 4 exhibit efficient sensing abilities towards Hg(II) ions. The antibacterial activities of complexes 1-5 were assessed against S. typhi and E. coli. The complexes 1 and 3 displayed good antibacterial activities against S. typhi (13.67, and 13.56 mm, respectively) while complexes 1, 2 and 4 were found to be efficient against E. coli (11.6, 12.66, 11.31 mm, respectively). The absorption maxima of 2,2-diphenyl-1-picryhydrazyl (DPPH) at 517 nm, considerably shifted upon addition of complexes 1-5. The results reveal that the complexes possess potential free radical scavenging abilities.