Hg Concentrations Research Articles

Mercury distribution, bioaccumulation, and biomagnification in riparian ecosystems from a neotropical savanna floodplain, Araguaia River, central Brazil

Litterfall is the main source of dry deposition of mercury (Hg) into the soil in forest ecosystems. The accumulation of Hg in soil and litter suggests the possibility of transfer to terrestrial invertebrates through environmental exposure or ingestion of plant tissues. We quantified total mercury (THg) concentrations in two soil layers (organic: 0–0.2 m; mineral: 0.8–1 m), litter, fresh leaves, and terrestrial invertebrates of the Araguaia River floodplain, aiming to evaluate the THg distribution among terrestrial compartments, bioaccumulation in invertebrates, and the factors influencing THg concentrations in soil and invertebrates. The mean THg concentrations were significantly different between the compartments evaluated, being higher in organic soil compared to mineral soil, and higher in litter compared to mineral soil and fresh leaves. Soil organic matter content was positively related to THg concentration in this compartment. The order Araneae showed significantly higher Hg concentrations among the most abundant invertebrate taxa. The higher Hg concentrations in Araneae were positively influenced by the concentrations determined in litter and individuals of the order Hymenoptera, confirming the process of biomagnification in the terrestrial trophic chain. In contrast, the THg concentrations in Coleoptera, Orthoptera and Hymenoptera were not significantly related to the concentrations determined in the soil, litter and fresh leaves. Our results showed the importance of organic matter for the immobilization of THg in the soil and indicated the process of biomagnification in the terrestrial food web, providing insights for future studies on the environmental distribution of Hg in floodplains.

Soil Mercury Pollution of Hainan Island, China: Patterns, Influencing Factors, and Health Risks

Due to the rapid expansion of tourism, mining, and manufacturing, the economy of Hainan Island in southern China has experienced swift growth. However, it also brings the risk of soil pollution by mercury (Hg) as a result of increased traffic and mineral processing activities. In order to investigate the characteristics of soil Hg pollution in Hainan Island and assess the health risk, a total of 239 samples were gathered from five representative regions across the island. The findings indicate considerable fluctuations in the soil Hg concentration across the five sub-study areas, which are influenced by factors such as wind direction, mining activities, and economic development. Changjiang Li Autonomous County, situated in the downwind direction (NW) and rich in mineral resources, shows the highest soil Hg concentration (10.00–1582.50 ng·g−1). Following closely are Haikou and Sanya, the two most economically developed cities on the island, with soil Hg concentrations of 8.33–321.50 ng·g−1 and 6.04–180.50 ng·g−1, respectively. Wuzhishan Nature Reserve and Lingshui Li Autonomous County, located in the upwind area (SE), show the lowest concentrations, ranging between 10.70–104.67 ng·g−1 and 9.43–84.00 ng·g−1, respectively. Both the Single Pollution Index method and the Geo-accumulation Index method were employed to assess the level of Hg pollution. The results indicate that nearly half of the sampling sites are contaminated, in which the proportion of contaminated sites in Sanya and Haikou are the highest, but the level of contamination is low; the heavily contaminated sites are predominantly found in Changjiang Li Autonomous County. However, the low Health Risk Index (HI) ranging from 0.0001 to 0.0334 suggests that although the soil is contaminated with Hg, it does not pose a substantial non-carcinogenic risk to human health.

Changes in Carbon, Nitrogen, and Oxygen Stable Isotope Ratios and Mercury Concentrations in Killer Whales (Orcinus orca) during and after Lactation

The changes in the stable isotope ratios of carbon (δ13C), nitrogen (δ15N), oxygen (δ18O), and mercury (Hg) concentrations in muscle and liver tissues during and after lactation were studied in killer whales stranded along the coast of Hokkaido, in the northern area of Japan (n = 16). Calf muscles displayed δ13C- and δ15N-enriched peaks and a δ18O-depleted peak during lactation. The δ13C- and δ15N-enriched peaks appear to reflect the extensive nursing of 13C- and 15N-enriched milk and the onset of weaning, whereas the δ18O-depleted peak may be attributable to the extensive nursing of 18O-depleted milk and the onset of weaning. The δ13C and δ15N values tended to gradually increase after the weaning, whereas the δ18O values tended to decrease. The δ13C and δ15N levels in calves were similar between liver and muscle samples, whereas those in mature animals were higher in liver than in muscle samples. The isotopic turnover rates of C and N may be similar between the liver and muscle tissues in calves, which are rapidly growing animals. The Hg concentrations in muscle tissues were slightly higher in small calves than in large calves, probably due to the Hg transfer across placenta. The Hg concentrations in liver and muscle samples increased with increasing body length, and those in two liver samples from mature animals exceeded the high-risk threshold for marine mammal health effects (82 μg/wet g).

Selenium-mercury interactions and relationship to aquatic toxicity: A review.

A review of the literature pertaining to selenium-mercury (Se/Hg) interactions in aquatic species was performed to provide insight into the mechanisms allowing for the reported changes in bioaccumulation and toxicity that have been observed when the two elements occur at elevated concentrations. Selenium (Se) has been shown to protect against mercury (Hg) toxicity in all animal models evaluated (fish, birds, mammals, and plants). To explore the interaction between the two elements, data are presented on concentrations of both elements in wild-caught fish at numerous locations. The data show that most fish have Se/Hg ratios >1.0. The importance of this ratio has been reported, with suggestions that the protective interaction is due in large part to the formation of HgSe. Data show that when the Se/Hg molar ratio is <1.0 in the diet of fish and animals, Hg toxicity will be expressed, provided that the Hg concentration is sufficiently high. This toxicity is likely the result of Se deficiency leading to an excess of reactive oxygen species. Laboratory fish toxicity studies reviewed show that Se toxicity can be reduced or eliminated when Hg is added to the diet in moderate amounts. Field studies have shown reduced accumulation of Hg when Se concentrations are increased. When Hg in the diet is significantly elevated (usually >10 µg/g), toxicity is expressed regardless of the Se present. Likewise, amelioration of Se toxicity by Hg occurs over a limited range. Tissue thresholds for Se toxicity have been derived primarily from studies where fish eggs were extracted from wild fish and embryo deformities were observed; however, the amount of Hg in the fish or ovaries was not considered, which could lead to uncertainty in the toxicity threshold. It is recommended that both elements be measured and evaluated when performing risk assessments and setting water quality criteria. Integr Environ Assess Manag 2024;00:1-11. © 2024 SETAC.

Magmatic evolution of the Kolumbo submarine volcano and its implication to seafloor massive sulfide formation

Seafloor massive sulfides form in various marine hydrothermal settings, particularly within volcanic arcs, where magmatic fluids may contribute to the metal budget of the hydrothermal system. In this study, we focus on the Kolumbo volcano, a submarine volcanic edifice in the central Hellenic Volcanic Arc hosting an active hydrothermal system. Diffuse sulfate-sulfide chimneys form a Zn-Pb massive sulfide mineralization with elevated As, Ag, Au, Hg, Sb, and Tl contents. These elements have similar behavior during magmatic degassing and are common in arc-related hydrothermal systems. Trace-element data of igneous magnetite, combined with whole rock geochemistry and numerical modelling, highlights the behavior of chalcophile and siderophile elements during magmatic differentiation. We report that, despite early magmatic sulfide saturation, chalcophile element contents in the magma do not decrease until water saturation and degassing has occurred. The conservation of chalcophile elements in the magma during magmatic differentiation suggests that most of the magmatic sulfides do not fractionate. By contrast, upon degassing, As, Ag, Au, Cu, Hg, Sb, Sn, Pb, and Zn become depleted in the magma, likely partitioning into the volatile phase, either from the melt or during sulfide oxidation by volatiles. After degassing, the residual chalcophile elements in the melt are incorporated into magnetite. Trace-element data of magnetite enables identifying sulfide saturation during magmatic differentiation and discrimination between pre- and post-degassing magnetite. Our study highlights how magmatic degassing contributes to the metal budget in magmatic-hydrothermal systems that form seafloor massive sulfides and shows that igneous magnetite geochemistry is a powerful tool for tracking metal-mobilizing processes during magmatic differentiation.

Transformation of Mercurous [Hg(I)] Species during Laboratory Standard Preparation and Analysis: Implication for Environmental Analysis.

Hg(I) may control Hg redox kinetics; however, its metastable nature hinders analysis. Herein, the stability of Hg(I) during standard preparation and analysis was studied. Gravimetric analysis showed that Hg(I) was stable in its stock solution (1000 mg L-1), yet completely disproportionated when its dilute solution (10 μg L-1) was analyzed using liquid chromatography (LC)-ICPMS. The Hg(I) dimer can form through an energetically favorable comproportionation between Hg(0) and Hg(II), as supported by density functional theory calculation and traced by the rapid isotope exchange between 199Hg(0)aq and 202Hg(II). However, the separation of Hg(0) and Hg(II) (e.g., LC process) triggered its further disproportionation. Polypropylene container, increasing headspace, decreasing pH, and increasing dissolved oxygen significantly enhanced the disproportionation or redox transformations of Hg(I). Thus, using a glass container without headspace and maintaining a slightly alkaline solution are recommended for the dilute Hg(I) stabilization. Notably, we detected elevated concentrations of Hg(I) (4.4-6.1 μg L-1) in creek waters from a heavily Hg-polluted area, accounting for 54-70% of total dissolved Hg. We also verified the reductive formation of Hg(I) in Hg(II)-spiked environmental water samples, where Hg(I) can stably exist in aquatic environments for at least 24 h, especially in seawater. These findings provide mechanistic insights into the transformation of Hg(I), which are indicative of its further environmental identification.

Exploring the spatial variation of mercury in the Gulf of St. Lawrence using northern gannets as fish samplers

Mercury (Hg) is a ubiquitous and pervasive environmental contaminant with detrimental effects on wildlife, which originates from both natural and anthropogenic sources. Its distribution within ecosystems is influenced by various biogeochemical processes, making it crucial to elucidate the factors driving this variability. To explore these factors, we employed an innovative method to use northern gannets (Morus bassanus) as biological samplers of regurgitated fish in the Gulf of St. Lawrence. We assessed fish total Hg (THg) concentrations in relation to their geographical catch location as well as to pertinent biotic and anthropogenic factors. In small fish species, trophic position, calculated from compound-specific stable nitrogen isotopes in amino acids, emerged as the most influential predictor of THg concentrations. For large fish species, THg concentrations were best explained by δ13C, indicating higher concentrations in inshore habitats. No anthropogenic factors, such as pollution, shipping traffic, or coastal development, were significantly related to THg concentrations in fish. Moreover, previously published THg data in mussels sampled nearby were positively linked with THg concentrations in gannet prey, suggesting consistent mercury distribution across trophic levels in the Gulf of St. Lawrence. Our findings point to habitat-dependent variability in THg concentrations across multiple trophic levels. Our study could have many potential uses in the future, including the identification of vulnerability hotspots for fish populations and their predators, or assessing risk factors for seabirds themselves by using biologically relevant prey.

Temporal and Spatial Comparison of Mercury Bioaccumulation in the Lower Trophic Levels of a Post-glacial Lake Food Web.

Total mercury (Hg) concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotopes were quantified among aquatic invertebrate and sediment samples collected from Keuka Lake in New York's Finger Lakes region to evaluate temporal and spatial variability in Hg bioaccumulation and trophic ecology among these lower trophic levels. Hg concentrations ranged from 6.3 to 158.8ng/g (dry wt) across dreissenid mussel, zooplankton, and juvenile (< 10mm) and adult (≥ 10mm) mysid shrimp (Mysis diluviana) samples. Hg concentrations were higher in samples collected from the western basin in 2015 relative to those for samples collected from this basin in 2022 (p < 0.001). While no specific mechanisms could be identified to explain this difference, higher δ15N values for zooplankton collected in 2015 support conclusions regarding the role of zooplankton trophic status on Hg concentrations in these populations. Spatial patterns in Hg concentrations were of generally low variability among samples collected from the lake's east, west and south basins in 2022. Trophic positions as inferred by δ15N were represented by adult mysids > juvenile mysids > large zooplankton (≥ 500µm) > dreissenid mussels ≥ small zooplankton (64-500µm). Differences were evident among the regression slopes describing the relationships between sample Hg concentrations and δ15N values across the lake's three basins (p = 0.028). However, this was primarily attributed to high δ15N values measured in dreissenid mussels collected from the south basin in 2022. Biota sediment accumulation factors ranged from 0.2 to 2.3 and were highest for adult M. diluviana but mysid δ13C values generally supported a pelagic pathway of Hg exposure relative to benthic sediments. Overall, these results provide additional support regarding the contributions of lower trophic levels to Hg biomagnification in aquatic food-webs.

Ecological risk assessment of heavy metals in desulfurized seawater discharged from a coal-fired power plant in Qingdao.

Despite the prevalence of discharge of large volumes of heavy-metal-bearing seawater from coal-fired power plants into adjacent seas, studies on the associated ecological risks remain limited. This study continuously monitored concentrations of seven heavy metals (i.e. As, Cd, Cr, Cu, Hg, Pb, and Zn) in surface seawater near the outfall of a coal-fired power plant in Qingdao, China over three years. The results showed average concentrations of As, Cd, Cr, Cu, Hg, Pb, and Zn of 2.63, 0.33, 2.97, 4.63, 0.008, 0.85, and 25.00 μg/L, respectively. Given the lack of data on metal toxicity to local species, this study investigated species composition and biomass near discharge outfalls and constructed species sensitivity distribution (SSD) curves with biological flora characteristics. Hazardous concentrations for 5% of species (HC5) for As, Cd, Cr, Cu, Hg, Pb, and Zn derived from SSDs constructed from chronic toxicity data for native species were 3.23, 2.22, 0.06, 2.83, 0.66, 4.70, and 11.07 μg/L, respectively. This study further assessed ecological risk of heavy metals by applying the Hazard Quotient (HQ) and Joint Probability Curve (JPC) based on long-term heavy metal exposure data and chronic toxicity data for local species. The results revealed acceptable levels of ecological risk for As, Cd, Hg, and Pb, but unacceptable levels for Cr, Cu, and Zn. The order of studied heavy metals in terms of ecological risk was Cr > Cu ≈ Zn > As > Cd ≈ Pb > Hg. The results of this study can guide the assessment of ecological risk at heavy metal contaminated sites characterized by relatively low heavy metal concentrations and high discharge volumes, such as receiving waters of coal-fired power plant effluents.

Plackett-Burman and Box-Wilson designs for the removal of mercury (II) by cypress pines and leaves, optimizing the surrounding conditions

In this study, the removal of Hg (II) from cypress leaves and cypress pines was examined. Factors like time of contact (1–60 min), amount of biosorbent used (0.02–0.06 min), pH levels (1.2–6.52 min), initial metal concentration (100–250 ppm) temperature (20–40 min), strength of ions (0.5–1.5 M), and speed of stirring (0–250 min) were studied. Kinetic data were described using both pseudo-first-order and pseudo-second-order models. Equilibrium data were analyzed using Langmuir and Freundlich models, with the Langmuir model fitting the data best. The kinetic data were best described by the pseudo-second-order model. Thermodynamic studies showed that the removal of Hg(II) by cypress leaves was exothermic. The Plackett–Burman design (PBD) and Box–Wilson designs were used for optimization, recommending values of 250 mg/L, 5.98, 7.98 min, and 0.5 g for the variables Co (initial concentration of Hg(II) ions), pH (acidity level), contact time, and mass of KNO3 (potassium nitrate) for the removal of mercury (II) by cypress pines.

The effect of phytoremediation on the reduction of mercury-contaminated water from gold processing using water kale (Ipomoea aquatica Forsk)

Gold ore processing is carried out by amalgamation techniques where mercury (Hg) is used as a medium to bind gold which results in water pollution around the processing area, so it is necessary to remediate water. One way in managing mercury-contaminated water is phytoremediation of the use of water kale (ipomoea aquatica forsk) and to help the phytoremediation process, ingredients are needed that can help the growth of water kale in increasing the absorption of Hg concentrations, namely the addition of liquid NPK fertilizer. This study aims to analyze water kale without liquid NPK fertilizer, and use liquid NPK fertilizer against water kale in reducing the concentration of Hg, pH and TSS metals in water. This study used an experimental method with an experimental box (container) consisting of 4 treatments, then an Analysis of Variance (ANOVA) test of 5% and Duncan Multiple Rang Test were carried out. The results showed that liquid NPK fertilizer had an influence on reducing the concentration of Hg, pH and TSS in water. Based on the results of experiments using liquid NPK fertilizer, the best treatment results were obtained in mercury absorption by water kale and reducing Hg concentration in water, namely treatment D (contaminated water + water kale + liquid NPK fertilizer) on the 14th day, as evidenced by a decrease in Hg concentration in water by 0.56 mg / l to 0.00486 mg / l, pH 10.1 to 6.86 and TSS 1695 mg / l to 1 mg / l and an increase in nitrate levels, Phosphate and potassium in water can accelerate absorption by water kale.

Comparison of properties of brown coal and bio-mass-based substitute fuels

Due to the EU climate change strategy, there are many coal-fired heating plants looking for new fuel. One of the possibilities is biomass-based fuels. This term is quite general because the final technology can be different because of properties of different types of biomasses. The sustainable solution can be the use of biomass residues. This article is about long-term monitoring of the properties of brown coal, agglomerated herbaceous biomass from agricultural residues, and wood chips from harvesting residues. 702 samples of brown coal, 715 samples of plant pellets and 607 samples of wood chips were analyzed, which were supplied do commercial heating plant between the years 2021-2023. The water and ash content, lower heating value (LHV) and higher heating value (HHV), were analyzed. The mineral composition of the fuels was determined quarterly from mixed samples. In the case of water content, the lowest values were achieved for herbaceous pellets (11.35%), due to their previous drying. The moisture content of the wood chips fluctuated. The average was 36.34%, with a maximum deviation of up to 49.9%. The average water content in brown coal was around 28.63%. In detail, there is a seasonal influence of the weather. In the case of ash content determination, the values for brown coal and herbaceous pellets are similar (slightly above 5%), wood chips contain less ash (2.2%). The results for the wood chip samples fluctuated again. There were samples consisting of chipped logs (0.33% ash) and samples with a large proportion of forest soil (4.37%). The highest average HHV values were achieved for brown coal (18.98 MJ/kg), followed by herbaceous pellets (15.84 MJ/kg) and wood chips (11.02 MJ/kg). These differences may cause a decrease in steam output due to a limitation of space in the combustion chamber of the boiler after the retrofit. In the case of the content of nonmetallic elements, a different character of the biomass is evident, consisting of a higher oxygen content (38% vs 19%) and a lower carbon content (48% vs 68%). Biomass also contains less sulfur, but the high chlorine content of 0.12% compared to 0.02% in wood chips was determined in herbaceous pellet samples. For a heating plant, this means intensive chlorine corrosion or exceeding the emission limits of HCl. The solution can be in DSI technology. Brown coal contains more Ti, V, Li, Sr, Be, Na, Fe, and Al. The biomass contains more biogenic elements, especially Ca, K, P, and Zn, which allows the ash to be used for land application. For the combustion process, a significantly higher content of alkali has an adverse effect, causing a decrease of the melting temperature of ash, which can lead to technological problems, such as the formation of a material based on alkaline glass, which decreases heat transfer and combustion efficiency. Most often, this complication is solved by micro detonations and more frequent maintenance. The contents of Hg, Cd, and Tl in the samples were below the detection limit.

Mercury biomagnification in the food web of Agami Pond, Kaw-Roura Nature Reserve, French Guiana

Freshwater ecosystems are among the most important ecosystems worldwide, however, over the last centuries, anthropogenic pressures have had catastrophic effects on them. Mercury (Hg) is one of the main environmental contaminants which globally affect ecosystems and particularly freshwater wildlife. While Hg originates from natural sources, anthropogenic activities such as agriculture, biomass combustion, and gold mining increase its concentrations.Gold mining activities are the main drivers of Hg emission in tropical ecosystems and are responsible for up to 38% of global emissions. Once in its methylated form (MeHg), mercury biomagnifies through the trophic chain and accumulates in top predators. Due to the toxicity of MeHg, long-lived predators are even more subjected to chronic effects as they accumulate Hg over time.In the present study we quantified Hg contamination in two top predators, the Black caiman Melanosuchus niger and the Agami heron Agamia agami, and in their prey in the Kaw-Roura Nature Reserve in French Guiana and evaluated the biomagnification rate in the trophic chain.Our results show that despite a TMF in the range of others in the region (4.38 in our study), top predators of the ecosystem present elevated concentrations of Hg. We have found elevated Hg concentrations in the blood of adult Black caiman (2.10 ± 0.652 μg g−1 dw) and chicks of Agami heron (1.089 ± 0.406 μg g−1 dw). These findings highlight the need to better evaluate the potential impact of Hg in freshwater top predators, especially regarding reprotoxic effects.

A Comprehensive Assessment of the Ecological State of the Transboundary Irtysh River (Kazakhstan, Central Asia)

The diverse anthropogenic load on the transboundary Irtysh River necessitates an assessment of its ecological state, which was the goal of this work. We conducted this research in July 2023 in the upper and lower reaches of the Kazakh part of the Irtysh basin. We determined transparency; temperature; pH; salinity (TDS); oxygen, N-NO3, N-NO2, N-NH4, PO4, Mn, Fe, Si, Cd, Cu, Zn, Pb, Cr, Co, and Hg contents; permanganate index; and zooplankton variables at 27 stations. We assessed the ecological state of the river by comparing the contents of pollutants with their maximum permissible concentrations (MPCfw), Classification Scales, and bioindications. An excess of MPCfw was detected for N-NO2, Cu, and Fe and locally for Cr and Zn. According to the Classification Scales, most analysed variables corresponded to slightly polluted waters; N-NO2, Cr, and Zn corresponded to moderately and heavily polluted waters. Zooplankton was represented by 82 species, with an average abundance of 6728 individuals/m3, biomass of 2.81 mg/m3, Shannon index of 1.99–2.08 bit, ∆-Shannon of 0.09, and average individual mass of 0.0019 mg. The spatial distribution of abiotic and biotic variables indicated increased organic and toxic pollution downstream in the Irtysh. Potential sources of pollution of the Irtysh basin are discussed.

Uncontrolled Post-Industrial Landfill-Source of Metals, Potential Toxic Compounds, Dust, and Pathogens in Environment-A Case Study.

The aim of this case study was the evaluation of the selected metals' concentration, potential toxic compound identification, cytotoxicity analysis, estimation of the airborne dust concentration, biodiversity, and number of microorganisms in the environment (leachate, soil, air) of the biggest uncontrolled post-industrial landfills in Poland. Based on the results obtained, preliminary solutions for the future management of post-industrial objects that have become an uncontrolled landfill were indicated. In the air, the PM1 fraction dominated, constituting 78.1-98.2% of the particulate matter. Bacterial counts were in the ranges of 9.33 × 101-3.21 × 103 CFU m-3 (air), 1.87 × 105-2.30 × 106 CFU mL-1 (leachates), and 8.33 × 104-2.69 × 106 CFU g-1 (soil). In the air, the predominant bacteria were Cellulosimicrobium and Stenotrophomonas. The predominant fungi were Mycosphaerella, Cladosporium, and Chalastospora. The main bacteria in the leachates and soils were Acinetobacter, Mortierella, Proteiniclasticum, Caloramator, and Shewanella. The main fungi in the leachates and soils were Lindtneria. Elevated concentrations of Pb, Zn, and Hg were detected. The soil showed the most pronounced cytotoxic potential, with rates of 36.55%, 63.08%, and 100% for the A-549, Caco-2, and A-549 cell lines. Nine compounds were identified which may be responsible for this cytotoxic effect, including 2,4,8-trimethylquinoline, benzo(f)quinoline, and 1-(m-tolyl)isoquinoline. The microbiome included bacteria and fungi potentially metabolizing toxic compounds and pathogenic species.

Study of water quality in ex-mining pits for fish cultivation in Gunung Mas regency, Central Kalimantan

Ex-mining pit is a wide expanse, often becomes a problem, especially for the environment. Lack of information about the use of mining pits for fishing activities, especially for the studies on the quality of mining pits to support the growth of cultivated fish. This research was conducted in the village of Tanjung Riu, Gunung Mas Regency, Central Kalimantan Province, using two ex-mining ponds belonging to the community. The results show that the water quality for both mine pits with water parameters for: dissolved oxygen (DO) on average 6.09 mg/l – 7.45 mg/l, pH 2.94 – 3.54, Biological Oxygen Demand (BOD) 4.78 mg/L, temperature 30 -32 oC, turbidity 51.7-53.5 NTU, value of Total Dissolved Solids (TDS) 0.003 – 0.017 gr/L, mercury (Hg) content of 0.000247 mg/l - 0.000359 mg/l, the depth of the pool is 1.7 m – 2.74 m. The abundance of plankton is between 869 - 1106 cells/L, and abundance of benthos is between 264 - 352 ind/m2. The range of pond water quality based on second-class national water quality standards, which is suitable for fish cultivation with moderate abundance of plankton.

The levels of mercury (Hg) and arsenic (As) in wild boar’s liver (Sus scrofa) in eleven hunting areas from the Republic of North Macedonia

The monitors have recently been defined as the organisms in which changes in known characteristics can be measured to assess the extent of the environmental contamination. Among the numerous game species, the wild boar as omnivore is characterized as an exceptionally good biomonitor. The concentrations of one heavy metal (Hg) and one metalloid (As) were measured using cold vapor atomic absorption spectrometer and atomic absorption spectrophotometry in the liver tissue of free-living wild boars. From 11 hunting areas locations that cover the whole territory of North Macedonia in a period of 7 years (2016-2022) a total of 608 wild boar liver samples were harvested during the regular hunting season. The mean concentration of Hg from 11 hunting grounds ranged from 12.7 μg/kg to 68.8 μg/kg, and mean concentration for all was 45.67 μg/kg. The average concentration of As ranged from 22 μg/kg to 55.3 μg/kg, and mean concentration for all was 33.1 μg/kg. For mercury, 6.56% or 40 of the total number of samples (608) exceeded the maximum allowed limits, and for arsenic none of the examined samples exceeded the allowed limit. For both elements a statistically significant difference was determined in relation to the years, with irregular oscillations from year to year. The mean values for mercury and arsenic are encouraging and generally indicate the relatively low contamination in the territory of the Republic of North Macedonia. However, the statistical differences due to the year as a factor suggest there is the need for the further research.

A Comparative Study of Mercury Bioaccumulation in Bivalve Molluscs from a Shallow Estuarine Embayment.

In estuarine food webs, bivalve molluscs transfer nutrients and pollutants to higher trophic levels. Mercury (Hg) pollution is ubiquitous, but it is especially elevated in estuaries historically impacted by industrial activities, such as those in the U.S. Northeast. Monomethylmercury (MeHg), the organic form of Hg, is highly bioaccumulative and transferable in the food web resulting in the highest concentrations in the largest and oldest marine predators. Patterns of Hg concentrations in marine bivalve molluscs, however, are poorly understood. In this study, inorganic Hg (iHg), MeHg, and the total Hg (THg) in soft tissues of the northern quahogs (Mercenaria mercenaria), eastern oysters (Crassostrea virginica), and ribbed mussels (Geukensia demissa) from eastern Long Island sound, a temperate estuary of the western North Atlantic Ocean was investigated. In all three species, concentrations of THg remained similar between the four sampling months (May, June, July, and September), and were mostly independent of animal size. In quahogs, MeHg and iHg displayed significant (p < 0.05) positive (iHg in May and June) and negative (MeHg in July and September) changes with shell height. Variability in concentrations of THg, MeHg, and iHg, both inter- and intra-specifically was high and greater in quahogs and oysters (THg: 37, 39%, MeHg: 28, 39%, respectively) than in mussels (THg: 13%, MeHg: 20%). The percentage of THg that was MeHg (%MeHg) was also highly variable in the three species (range: 10-80%), highlighting the importance of measuring MeHg and not only THg in molluscs.

Mercury bioaccumulation and its relationship with trophic biomarkers in a Mediterranean elasmobranch mesopredator

Human activity has led to increased concentrations of mercury (Hg) in the world's oceans. Mercury can bioaccumulate and biomagnify in animal tissues via trophic transfer, thus, becoming most pronounced in larger and older predators. Here, we measured Hg concentrations and their relationship with stable isotopes-based proxies of trophic level (δ13C and δ15N values) in multiple tissues of Mustelus spp. from the Mediterranean Sea. We found higher Hg concentrations in muscle than in liver and fin tissues. The relationship between Hg concentrations and δ15N values in muscle suggested repeated foraging for low trophic level and Hg-poor prey, and biomagnification of Hg at higher trophic levels. Seasonal variations in δ13C values could indicate shifts in primary production sources and/or in local prey availability. The HBVSe index suggested no risk to human health, however the safe meal limit recommendations are 4.5 and 2.2 portions per month for adults and children, respectively.

Assessment of Potential Human Health Risk Associated With Heavy Metals in Soil – Vegetables System Irrigated by Rift Valley Lake Ziway, Ethiopia

Metal contamination of vegetables is a major concern, especially in areas where irrigation has been used for a long time. The Central Ethiopian Rift Valley Region is highly affected due to the heavy use of agrochemicals throughout the year. Although some studies have been conducted on the concentration and level of heavy metal pollution, little attention has been paid to their impact on human health. This study determined the concentrations of nine metals (As, Cd, Cr, Co, Cu, Hg, Ni, Pb, and Zn) in a soils and vegetables (tomatoes and onions) irrigated by Lake Ziway, Ethiopia. An inductively coupled plasma optical emission spectrometer (ICP-OES) was used to determine the heavy metal levels. Moreover, the study evaluated the health risks associated with consuming contaminated vegetables by employing major indices, including non-carcinogenic and carcinogenic risks. The results showed that the mean concentrations of Pb, As, Hg, and Cr in all tomato and onion samples and the average Zn, Pb, Cd, and Hg levels in all soil samples exceeded the FAO/WHO threshold. Non-carcinogenic health risk estimates showed that As, Pb, Hg, and Co for children and Pb and Co for adults had THQ values greater than 1, indicating the possibility of systemic health risks. Carcinogenic health risk showed that Ni posed a risk of developing cancer for both adults and children, with values ranging from 10−3 to 10−1. In addition, children are likely to have a higher cancer risk due to exposure to As and Cr. Therefore, it is crucial to raise awareness among stakeholders and implement effective monitoring policies to safeguard public health both within and beyond the study area.