Synthesis of ternary geopolymers using prediction for effective solidification of mercury in tailings.

This study used steel slag, fly ash, and metakaolin as raw materials (SFM materials) to create silica-alumina-based geopolymers that can solidify Hg2+ when activated with sodium-based water glass. The experiments began with a triangular lattice point mixing design experiment, and the results were fitted, analyzed, and predicted. The optimum SFM material mass ratio was found to be 70% steel slag, 25% fly ash, and 5% metakaolin. The optimum modulus of the activator was identified by comparing the unconfined compressive strength and solidifying impact on Hg2+of geosynthetics with different modulus. The SFM geopolymer was then applied in the form of potting to cure the granulated mercury tailings. The inclusion of 50% SFM material generated a geosynthetic that reduced mercury transport to the surface soil by roughly 90%. The mercury concentration of herbaceous plant samples was also reduced by 78%. It indicates that the SFM material can effectively attenuate the migration transformation of mercury. Finally, characterization methods such as XPS and FTIR were used to investigate the mechanism of Hg2+ solidification by geopolymers generated by SFM materials. The possible solidification mechanisms were proposed as alkaline environment-induced mercury precipitation, chemical bonding s, surface adsorption of Hg2+ and its precipitates by the geopolymer, and physical encapsulation.

Mercury cycling in contaminated coastal environments: modeling the benthic-pelagic coupling and microbial resistance in the Venice Lagoon.

Anthropogenic activities have been releasing mercury for centuries, and despite global efforts to control emissions, concentrations in environmental media remain high. Coastal sediments can be a long-term repository for mercury, but also a secondary source, and competing processes in marine ecosystems can lead to the conversion of mercury into the toxic and bioaccumulative species methylmercury, which threatens ecosystem and human health. We investigate the fate and transport of three mercury species in a coastal lagoon affected by historical pollution using a novel high-resolution finite element model that integrates mercury biogeochemistry, sediment dynamics and hydrodynamics. The model resolves mercury dynamics in the seawater and the seabed taking into account partitioning, transport driven by water and sediment, and photochemical and microbial transformations. We simulated three years (early 2000s, 2019, and 2020) to assess the spatio-temporal distribution of mercury species concentrations and performed a sensitivity analysis to account for uncertainties. The modeled mercury species concentrations show high temporal and spatial variability, with water concentrations in some areas of the lagoon exceeding those of the open Mediterranean Sea by two orders of magnitude, consistent with available observations from the early 2000s. The results support conclusions about the importance of different processes in shaping the environmental gradients of mercury species. Due to the past accumulation of mercury in the lagoon sediments, inorganic mercury in the water is closely related to the resuspension of contaminated sediments, which is significantly reduced by the presence of benthic vegetation. The gradients of methylmercury depend on the combination of several factors, of which sediment resuspension and mercury methylation are the most relevant. The results add insights into mercury dynamics at coastal sites characterized by a combination of past pollution (i.e. sediment enrichment) and erosive processes, and suggest possible nature-based mitigation strategies such as the preservation of the integrity of benthic vegetation and morphology.

Characteristics of Gaseous Elemental Mercury in a Suburban Area of Shanghai, China.

To clarify gaseous elemental mercury (GEM) in suburban megacities in the Yangtze River Delta region, China, we observed GEM concentrations from December 2019 to November 2020 in Wujing town, a suburban area of Shanghai. The annual mean GEM concentration was 1.44 ± 0.88 ng m-3. Compared with the historical monitoring data of GEM in Shanghai over the past 10 years, the concentration of GEM showed a decreasing trend. The monthly mean concentrations of GEM showed clear seasonal variation, with higher values in the spring and winter. In spring and winter, typical Hg pollution events were observed, which could be mostly associated with increased local anthropogenic activity and temperature inversion. The results of the correlation analysis of the daily mean GEM concentrations with the AQI and backward trajectory calculations indicate that mercury pollution at monitoring sites can be affected by local, regional and interregional influences.

Neurobehavioral, neurotransmitter and redox modifications in Nauphoeta cinerea under mixed heavy metal (silver and mercury) exposure.

Heavy metals are encountered in nature, and are used in several human endeavors, including in dental fillings. It is well known that the safety of metals depends on their chemical form, as well as the dose and route through which biological systems are exposed to them. Here, we used the Nauphoeta cinerea model to examine the mechanism by which salts of the heavy metals used in dental fillings - silver and mercury - exert their neurotoxicity. Nymphs exposed to heavy metals presented with reduced motor and exploratory abilities as they spent more time immobile, especially in the periphery of a novel object, and covered less distance compared with control nymphs. Exposure to AgNO3 and HgCl2 also exacerbated levels of oxidative stress markers (MDA & ROS) and the neurotransmitter regulators - AChE and MAO, while reducing antioxidant activity markers, both in biochemical (thiol & GST) and RT-qPCR (TRX, GST, SOD, Catalase) examinations, in neural tissues of the cockroach. The observed disruptions in neurolocomotor control, synaptic transmission and redox balance explain how heavy metal salts may predispose organisms to neurological disorders.

Mercury sources, transport, and transformation in rainfall-runoff processes: Mercury isotope approach.

Mercury (Hg) in runoff water poses significant ecological risks to aquatic ecosystems that can affect organisms. However, accurately identifying the sources and transformation processes of Hg in runoff water is challenging due to complex natural conditions. This study provides a comprehensive investigation of Hg dynamics in water from rainfall to runoff. The Hg isotope fractionation in water was characterized, which allows accurate quantification of Hg sources, transport, and transformations in rainfall-runoff processes. Δ200Hg and corrected Δ199Hg values can serve as reliable tracers for identifying Hg sources in the runoff water and the variation of δ202Hg can be explained by Hg transformation processes. During runoff migration processes, Hg from rainfall is rapidly absorbed on the land surface, while terrestrial Hg entering the water by the dissolution process becomes the primary component of dissolved mercury (DHg). Besides the dissolution and adsorption, microbial Hg(II) reduction and demethylation of MeHg were dominant processes for DHg in the runoff water that flows through the rice paddies, while photochemical Hg(II) reduction was the dominant process for DHg in the runoff water with low water exchange rates. Particulate Hg (PHg) in runoff water is dominantly originated by the terrestrial material and derived from the dissolution and adsorption process. Tracking sources and transformations of Hg in runoff water during the rainfall-runoff process provides a basis for studying Hg pollution in larger water bodies under complex environmental factors.

Rapid determination of uracil in biological fluids at mercury thin film electrode for early detection of potential 5-fluorouracil toxicity due to dihydropyrimidine dehydrogenase deficiency.

Determination of plasma uracil was reported as a method for evaluation of Dihydropyrimidine dehydrogenase (DPD) activity that is highly demanded to ensure the safe administration of 5-fluorouracil (5-FU)-based therapies to cancer patients. This work reports the development of a simple electroanalytical method based on adsorptive stripping square wave voltammetry (AdSWV) at mercury film-coated glassy carbon electrode (MF/GCE) for the highly sensitive determination of uracil in biological fluids that can be used for diagnosis of decreased DPD activity. Due to the formation of the HgII-Uracil complex at the electrode surface, the accuracy of the measurement was not affected by the complicated matrices in biological fluids including human serum, plasma, and urine. The high sensitivity of the developed method results in a low limit of detection (≈1.3 nM) in human plasma samples, falling below the practical cut-off level of 15 ng mL-1 (≈0.14 µM). This threshold concentration is crucial for predicting 5-FU toxicity, as reported in buffer, and ≤1.15% in biological samples), and accuracy (recovery percentage close to 100%).

Experimental and theoretical elucidation of the luminescence quenching mechanism in highly efficient Hg2+ and sulfadiazine sensing by Ln-MOF.

Heavy metal ions and antibiotic contamination have become a major environmental concern worldwide. The development of efficient recognition strategies of these pollutants at ultra-low concentrations in aqueous solutions as well as the elucidation of the intrinsic sensing mechanism are challenging tasks. In this work, unique luminescent Ln-MOF materials (NIIC-3-Ln) were assembled by rational ligand design. Among them, NIIC-3-Tb demonstrated highly selective luminescence quenching response toward Hg2+ and sulfadiazine (SDI) at subnanomolar concentrations in less than 7 s. In addition, a Hg2+ sensing mechanism through chelation was proposed on the basis of single-crystal X-ray diffraction analysis and Hg2+ adsorption study. The interaction mechanism of NIIC-3-Tb with SDI was revealed using a newly developed approach involving a (TD-)DFT based quantification of the charge transfer of a MOF-analyte supramolecular complex model in the ground and excited states. Effect of ultrasonic treatment on the surface morphology important for MOF sensing performance was revealed by gas adsorption experiments. The presented results indicate that NIIC-3-Ln is not only an advanced sensing material for the efficient detection of Hg2+ and SDI at ultra-low concentrations, but also opens up a new approach to study the sensing mechanism at the molecular level at ultra-low concentrations.

The impact of sphygmomanometer placement and cuff placement on blood pressure measurements.

Background: Hypertension is the most significant global risk factor for mortality and morbidity, making standardized blood pressure measurement crucial. Objectives: To investigate whether the location of blood pressure monitors and the positioning of cuffs yield differing results in blood pressure measurements. Methods: Patients admitted to the Affiliated Hospital of Jiujiang College between 1 January 2022 and 30 June 2023 were enrolled in this study and randomly allocated into four groups. These groups were defined based on the positioning of monitoring equipment as follows: varied placements of cuffs on automatic blood pressure monitors, different heights for mercury column blood pressure monitors, varied heights for automatic blood pressure monitors, and different orientations for the cuff airbag tubes on electrocardiogram monitors. Blood pressure was measured and recorded for each group, followed by an analysis of the variations in readings across the different setups. Results: In the first cohort of 763 individuals, mean systolic blood pressure measured at the standard upper arm site was 128.8 ± 10.5 mmHg, compared to 125.3 ± 10.4 mmHg at the elbow fossa. The corresponding diastolic pressures were 79.2 ± 10.7 and 75.0 ± 10.6 mmHg, respectively. The difference in systolic pressure between these positions was significant at 3.48 ± 3.22 mmHg (t1 = 29.91, p1 < 0.001) and for diastolic pressure at 4.23 ± 1.31 mmHg (t2 = 88.98, p2 < 0.001). For the subsequent groups, involving 253, 312, and 225 individuals, respectively, blood pressure measurements were analyzed and compared across different methods within each group. All p-values exceeded 0.05, indicating no statistically significant differences. Conclusions: Blood pressure values measured at the elbow fossa position using an upper arm-type automatic sphygmomanometer were found to be lower than those measured at the upper arm position, with a difference of 3.48 mmHg for systolic and 4.23 mmHg for diastolic pressures. It is therefore essential to position the cuff correctly, specifically 2-3 cm above the elbow fossa, when utilizing an upper arm-type automatic sphygmomanometer for blood pressure monitoring. Conversely, the placement of the mercury column sphygmomanometer and the automated sphygmomanometer at varying heights had no significant effect on blood pressure readings. Similarly, the orientation of the electrocardiogram's cuffed balloon tube, whether facing upward or downward, did not influence blood pressure measurement outcomes.

Trends of hair Hg accumulation in reproductive-age women living in Central Russia and the calculated costs of Hg-induced IQ loss in the period between 2005 and 2021.

The objective of the present study was to retrospectively evaluate hair mercury (Hg) content in reproductive-age women living in Central Russia (Moscow and Moscow region), and to calculate the potential costs of the potential Hg-induced IQ loss in a hypothetical national birth cohort. MATERIALS AND METHODS: A total of 36,263 occupationally non-exposed women aged between 20 and 40 years living in Moscow (n = 30,626) or Moscow region (n = 5637) in the period between 2005 and 2021 participated in this study. Hair Hg content was evaluated with inductively coupled plasma-mass spectrometry (ICP-MS). Hair Hg levels in reproductive-age women were used for assessment of the potential IQ loss and its costs. RESULTS: The results demonstrate that hair Hg content in the periods between 2010 and 2015, and 2016-2021 was significantly lower than that in 2005-2009 by 26 % and 51 %, respectively. The highest hair Hg level was observed in women in 2005 (0.855 µg/g), being more than 2.5-fold higher than the lowest value observed in 2020 (0.328 µg/g). Multiple regression analysis revealed a significant inverse association between the year of analysis and hair Hg content (ß = -0.288; p < 0.001). The calculations demonstrate that in 2005 the costs of IQ loss in children exceeded 1.0 (1.6) billion USD, whereas in 2020 the costs of IQ loss accounted to approximately 0.15 (0.28) billion USD. CONCLUSION: Taken together, our data demonstrate that Hg accumulation in reproductive-age women reduced significantly in Russia from 2005 to 2021 resulting in predicted economic benefits by decreasing the costs of Hg-induced IQ loss.

Mercury bioaccumulation in three colonial seabird species in the Gulf of Maine.

The methylated form of mercury, MeHg, is a neurotoxin that bioaccumulates and biomagnifies through aquatic food webs, reaching high concentrations in top trophic species. Many seabird species are wide-ranging and feed on forage fish, so they can be used as sentinel species to assess the level of mercury in pelagic or coastal food webs because they integrate the signal from large areas and from lower trophic levels. The Gulf of Maine provides habitat for many seabirds, including endangered roseate terns (Sterna dougalii), common terns (Sterna hirundo), and the southernmost breeding population of black guillemots (Cepphus grylle). Hg levels were assessed in down of newly hatched chicks of three seabird species to determine pre-hatching Hg exposure. Stable isotopes (δ15N, δ13C) in down and chick contour feathers grown after hatching were used as indicators of adult female diet in the period before laying the egg (down) and pre-fledging chick diet (contour feathers). Black guillemot down THg concentrations were 10.07 ± 2.88 µg/g (mean ± 1SD), 5.5× higher than common tern down (1.82 ± 0.436 µg /g), and 7.4× higher than roseate tern down (1.37 ± 0.518 µg/g). Black guillemots also had higher down feather δ15N values (15.1 ± 0.52 ‰) compared to common (13.0 ± 0.72 ‰) or roseate terns (12.8 ± 0.25 ‰), and in black guillemot down feathers, higher Hg concentrations were correlated with δ15N, an indicator of trophic level. Repeated testing of the same tissue types across multiple years is needed to monitor THg exposure for seabirds in the Gulf of Maine; additionally, monitoring species composition and Hg presence in prey species of the black guillemot population would help to determine the source of high THg concentrations in this species.

Accumulation of Per- and Polyfluoroalkyl Substances (PFAS) in Coastal Sharks from Contrasting Marine Environments: The New York Bight and The Bahamas.

Per- and polyfluoroalkyl substances (PFAS) enter the marine food web, accumulate in organisms, and potentially have adverse effects on predators and consumers of seafood. However, evaluations of PFAS in meso-to-apex predators, like sharks, are scarce. This study investigated PFAS occurrence in five shark species from two marine ecosystems with contrasting relative human population densities, the New York Bight (NYB) and the coastal waters of The Bahamas archipelago. The total detected PFAS (∑PFAS) concentrations in muscle tissue ranged from 1.10 to 58.5 ng g-1 wet weight, and perfluorocarboxylic acids (PFCAs) were dominant. Fewer PFAS were detected in Caribbean reef sharks (Carcharhinus perezi) from The Bahamas, and concentrations of those detected were, on average, ∼79% lower than in the NYB sharks. In the NYB, ∑PFAS concentrations followed: common thresher (Alopias vulpinus) > shortfin mako (Isurus oxyrinchus) > sandbar (Carcharhinus plumbeus) > smooth dogfish (Mustelus canis). PFAS precursors/intermediates, such as 2H,2H,3H,3H-perfluorodecanoic acid and perfluorooctanesulfonamide, were only detected in the NYB sharks, suggesting higher ambient concentrations and diversity of PFAS sources in this region. Ultralong-chain PFAS (C ≥ 10) were positively correlated with nitrogen isotope values (δ15N) and total mercury in some species. Our results provide some of the first baseline information on PFAS concentrations in shark species from the northwest Atlantic Ocean, and correlations between PFAS, stable isotopes, and mercury further contextualize the drivers of PFAS occurrence.

Current status of advancement in remediation technologies for the toxic metal mercury in the environment: A critical review.

Currently, pollution due to heavy metals, in particular dissolved mercury, is a major concern for society and the environment. This work aims to evaluate the current scenario regarding the removal/elimination of mercury. Mercury removal through adsorption is mainly done through artificial resins and metallic-organic frameworks. In the case of the zinc organic framework, it was able to adsorb Hg2+, reaching an adsorption capacity of 802 mg g-1. As for the Hg(0) the coconut husk was found to have the lowest equilibrium time, 30 min, and the highest adsorption capacity of 956.2 mg g-1. Experimental reports and molecular simulation indicate that the adsorption of mercury and other chemical forms occurs due to electrostatic interactions, ion exchange, precipitation, complexation, chelation, and covalent bonds, according to the material nature. The reported thermodynamic results show that, in most cases, the mercury adsorption has an endothermic nature with enthalpy levels below 40 kJ mol-1. Thermal and chemical regeneration methods lead to a similar number of 5 cycles for different materials. The presence of other ions, in particular cadmium, lead, and copper, generates an antagonistic effect for mercury adsorption. Regarding the other current technologies, it was found that mercury removal is feasible through precipitation, phytoremediation, and marine microalgae; all these methods require constant chemicals or a slow rate of removal according to the conditions. Advanced oxidative processes have noteworthy removal of Hg(0); however, Fenton processes lead to mineralization, which leads to Fe2+ and Fe3+ in solution; sonochemical processes are impossible to scale up at the current technology level; and electrochemical processes consume more energy and require constant changes of the anode and cathode. Overall, it is possible to conclude that the adsorption process remains a more friendly, economical, and greener process in comparison with other processes.

Inter- and intraspecific variability of total mercury concentrations in bats of Texas (USA).

Exposure to mercury (Hg) may cause deleterious health effects in wildlife, including bats. Texas produces more Hg pollution than any other state in the United States, yet only one study has examined Hg accumulation in bats. This study measured the concentration of total Hg (THg) in fur (n = 411) collected from ten bat species across 32 sites in eastern and central Texas, USA. Fur THg concentrations were compared among species, and when samples sizes were large enough, between sex and life stage within a species, and the proximity to coal-fired power plants. For all sites combined and species with a sample size ≥8, mean THg concentrations (µg/g dry weight) were greatest in tri-colored bats (Perimyotis subflavus; 6.04), followed by evening bats (Nycticeius humeralis; 5.89), cave myotis (Myotis velifer; 2.11), northern yellow bats (Lasiurus intermedius; 1.85), Brazilian free-tailed bats (Tadarida brasiliensis; 1.03), and red bats (Lasiurus borealis/blossevillii; 0.974), and lowest in hoary bats (Lasiurus cinereus; 0.809). Within a species, fur THg concentrations did not significantly vary between sex for the five examined species (red bat, northern yellow bat, cave myotis, evening bat, Brazilian free-tailed bat) and only between life stage in evening bats. Site variations in fur THg concentrations were observed for evening bats, tri-colored bats, and Brazilian free-tailed bats. Evening bats sampled closer to point sources of Hg pollution had greater fur THg concentrations than individuals sampled further away. Sixteen percent of evening bats and 8.7% of tri-colored bats had a fur THg concentration exceeding the 10 µg/g toxicity threshold level, suggesting that THg exposure may pose a risk to the health of bats in Texas, particularly those residing in east Texas and on the upper Gulf coast. The results of this study can be incorporated into future management and recovery plans for bats in Texas.

Mercury in the Southwestern Atlantic reef-building coral Montastraea cavernosa (Cnidaria, Scleractinia).

Coastal ecosystems, such as coral reefs, are particularly vulnerable to mercury contamination due to direct contact with terrestrial sources. Here, we evaluated, for the first time, the concentration of mercury in coral reefs in the Southwestern Atlantic using the amphi-atlantic scleractinian coral Montastraea cavernosa. Sampling was realized over an extension of 200 km along different coral reefs. Our data show mercury values ranging from 0.01 to 0.27 mg kg-1 in the tissue and 0.001-0.06 mg kg-1 in the skeleton and higher values when compared to coral worldwide. The concentration of mercury in the tissue from Todos os Santos Bay was higher than in open sea regions but also higher compared to other coral reefs of the world, while the skeleton concentration did not indicate any differences when compared to the open sea regions. The data presented is of concern as we consider the importance of coral reefs and should be used in future environmental management planning.

Effective elimination of Hg(II) from water bodies with acid-modified magnetic biomass spent coffee grounds: conditional optimization and application.

To maximize the efficiency of biomass waste utilization and waste management, a novel acid-modified magnetic biomass spent coffee grounds (NiFe2O4/SCG) was obtained by pyrolysis at 473 K and co-precipitation methods and employed to eliminate bivalent mercury (Hg(II)) in water bodies. The prepared NiFe2O4/SCG adsorbent exhibits remarkable magnetism with a strength of 45.78 emu/g and can easily be separated from water via a magnetic force. The adsorption of Hg(II) over the NiFe2O4/SCG has an optimal conditions of pH = 8, T = 39 ℃, and dosage of 0.055 g/L, and the maximal adsorption capacity for Hg(II) is 167.44 mg/g via Response Surface Methodology optimization. The removal of Hg(II) over NiFe2O4/SCG primarily involves ion exchange, electrostatic attraction, and chelation; conforms to the pseudo-second-order kinetic and Langmuir models; and is an endothermic reaction. Additionally, the magnetic biomass NiFe2O4/SCG has good regeneration capability and stability. The application research reveal that inorganic salt ions, nitrogen fertilizer urea, humus, and other contaminants in different actual water bodies (river water, lake water, and the effluent of sewage treatment plant) have little effect on the adsorption of Hg(II) over the NiFe2O4/SCG. The prepared adsorbent NiFe2O4/SCG has practical application value for removing Hg(II) from water bodies.

Sulfhydryl functionalized two-dimensional Ti3C2Tx MXene for efficient removal of Hg2+ in water samples.

This study describes an adsorption method for the removal of Hg2+ from aquatic environments using sulfhydryl-functionalized Ti3C2Tx (SH-Ti3C2Tx). SH-Ti3C2Tx materials were synthesized through covalent interactions between dithiothreitol and two-dimensional Ti3C2Tx. The insertion of -SH groups increased the interlayer spacing of Ti3C2Tx, resulting in a 3-fold increase in the specific surface area of SH-Ti3C2Tx compared with the original Ti3C2Tx. The maximum Hg2+ adsorption capacity of SH-Ti3C2Tx was 3042 mg/g, which was 2.3-fold greater than that of Ti3C2Tx. After Hg2+ adsorption, SH-Ti3C2Tx was regenerated for repeated used by rinsing with HCl-thiourea. Next, SH-Ti3C2Tx was loaded onto a melamine sponge to construct SH-Ti3C2Tx adsorption columns suitable for continuous flow Hg2+ removal with extremely low flow resistance. Hg2+ removal rates exceeded 95 % when treating both high and low-concentration solutions (20 mg/L Hg2+ and 10 µg/L Hg2+). This study demonstrates the excellent adsorption-regeneration performance of SH-Ti3C2Tx, which has broad application prospects for the in-situ treatment of water contaminated with Hg2+.

Hg2+ removal characteristics of a strain of mercury-tolerant bacteria screened from heavy metal-contaminated soil in a molybdenum-lead mining area.

In this study, the mercury-tolerant strain LTC105 was isolated from a contaminated soil sample collected from a molybdenum-lead mine in Luanchuan County, Henan Province, China. The strain was shown to be highly resistant to mercury, with a minimum inhibitory concentration (MIC) of 32 mg·L-1. After a 24-h incubation in LB medium with 10 mg·L-1 Hg2+, the removal, adsorption, and volatilization rates of Hg2+ were 97.37%, 7.3%, and 90.07%, respectively, indicating that the strain had significant influence on mercury removal. Based on the results of Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), the investigation revealed that the primary function of LTC105 was to encourage the volatilization of mercury. The LTC105 strain also showed strong tolerance to heavy metals such as Mn2+, Zn2+, and Pb2+. According to the results of the soil incubation test, the total mercury removal rate of the LTC105 inoculation increased by 16.34% when the initial mercury concentration of the soil was 100 mg·L-1 and by 62.28% when the initial mercury concentration of the soil was 50 mg·kg-1. These findings indicate that LTC105 has certain bioremediation ability for Hg-contaminated soil and is a suitable candidate strain for microbial remediation of heavy metal-contaminated soil in mining areas.

Blood mercury mediates the associations between fish consumption and serum uric acid levels among Chinese adults: A nationally representative study.

Fish consumption can increase purine load in human body, and the enrichment of mercury in fish may affect the glomerular filtration function, both resulting in increased serum uric acid (SUA) levels. The data of blood mercury (BHg), fish consumption frequency and SUA levels of 7653 participants aged 18 years or older was from China National Human Biomonitoring (2017-2018). The associations between fish consumption frequency, ln-transformed BHg and SUA levels were explored through weighted multiple linear regressions. The mediating effect of BHg levels between fish consumption frequency and SUA levels was evaluated by mediation analysis. We found that both the fish consumption frequency and BHg were positively associated with SUA levels in both sexes. Compared to participants who had never consumed fish, participants who consumed fish once a week or more had higher SUA levels [ß (95% confidence interval, CI): 20.39 (2.16, 38.62) in males; ß (95% CI): 10.06 (0.76, 19.37) in females] and ln-transformed BHg [ß (95% CI): 0.97 (0.61, 1.34) in males; ß (95% CI): 0.84 (0.63, 1.05) in females]. Each 1-unit increase in ln-transformed BHg, the SUA levels rose by 4.78 (95% CI: 0.01, 9.54) µmol/L for males and 3.81 (95% CI: 1.60, 6.03) µmol/L for females. The association between fish consumption with SUA levels was mediated by ln-transformed BHg with the percent mediated of 34.66% in males and 26.58% in females. It revealed that BHg played mediating roles in the elevation of SUA levels caused by fish consumption. This study's findings could promote the government to intervene in mercury pollution in fish, so as to ensure the safety of fish consumption.

Environmental implications of dental restorative materials on the zebrafish Danio rerio: Are dental chair drainage systems an emerging environmental threat?

This study aimed to evaluate the environmental impact of dental materials: commercial composite Tetric EvoCeram®, glass ionomer Equia Forte® HT Fil, laboratory-prepared composite, alkasite Cention® Forte, amalgam Amalcap® Plus, and samples from dental chair drainage systems (DCDS). Methacrylate monomers were detected in the eluates of experimental and commercials composites, and alkasite. In DCDS samples solely mercury was found at concentrations of 0.08-1.86 µg/L. The experimental composite (48 h incubation) exhibited the highest toxicity on zebrafish Danio rerio (LC50=0.70 g/L), followed by amalgam (LC50=8.27 g/L) < Tetric EvoCeram® (LC50=10.94 g/L) < Equia Forte® HT Fil (LC50=24.84 g/L) < Cention® Forte (LC50=32.22 g/L). Exposure of zebrafish to DCDS samples resulted in decreased larval body length and increased occurrences of edema and blood accumulation. The results obtained highlight the need for additional monitoring and further research on the release of unreacted monomers and mercury from dental materials and their environmental impact.

Methylmercury Concentrations More Strongly Associated With Trait Variation Than Food Web Position in Plethodontid Salamanders.

Salamanders serve as bioindicators of mercury (Hg) in both terrestrial and aquatic habitats and are an important link in the food web between low-trophic prey and higher-trophic predators. We investigated the drivers of methylmercury (MeHg) exposure in three common plethodontid salamander species in New York State, USA, including comparisons among regions, habitat types (terrestrial and semiaquatic), and color morphs of Plethodon cinereus (striped and unstriped). Nonlethal tail samples were collected from one terrestrial species (P. cinereus) and two semiaquatic species (Eurycea bislineata and Desmognathus spp.) in the Adirondack Mountains (ADK) and the Finger Lakes National Forest (FLNF) regions. Samples were analyzed for MeHg and stable isotopes, including δ15N and δ13C which are proxies of trophic position and diet, respectively. Despite elevated biota Hg concentrations typically found in the ADK, salamander MeHg concentrations did not differ by region in the terrestrial species and one of the semiaquatic species. In addition, diet and trophic level did not explain MeHg exposure in salamanders. Semiaquatic salamanders exhibited higher MeHg concentrations than terrestrial salamanders in the FLNF only. Within species, only snout-vent length predicted MeHg concentrations in E. bislineata with few other variables significant as predictors of MeHg concentrations in path models. Among P. cinereus individuals in the FLNF, the striped morph had greater MeHg concentrations than the unstriped morph, and food web tracers were not different between morphs. Overall, New York State salamander Hg concentrations were elevated compared to other locations where these species are present. The present study establishes baseline Hg data in salamanders for future assessments of changes in Hg bioavailability to forests of New York State. Environ Toxicol Chem 2024;00:1-13. © 2024 SETAC.