Mercury Accumulation Research Articles

Mercury Accumulation in Commercial Varieties of Oryza sativa L. Cultivated in Soils of La Mojana Region, Colombia.

The Hg accumulation in different commercial varieties of Oryza sativa L. was evaluated in the region of La Mojana, Colombia, where rice cultivation has become the staple food of the population living in this area. The varieties studied were Fedearroz-473 (FA473), Fedearroz-2000 (FA2000), and Fedearroz-Mocari (FAM). Soil spiked at different Hg levels was evaluated, (130, 800, and 1500 µg kg−1) using a 32 factorial design that consisted of 3 (rice varieties) × 3 (Hg contents). The biomass, 1000-grain weight, and the accumulation of Hg in the roots, grains, and husks were determined. The highest biomass was found in the FA473 (308.76 ± 108.26 g), and the lowest was found in FAM (144.04 ± 26.45 g) in the 1500 µg kg−1 Hg soil in both cases. The weight per 1000-grains decreased significantly in the soil containing 800 µg of Hg kg−1. Hg accumulation in the organs of the evaluated varieties was higher in the roots, followed by in the husks and grains. The Hg in the rice grains of the evaluated varieties presented levels close to the permissible limit of the Chinese standard (20 μg Hg kg−1) in the evaluated soils and were only exceeded by FA473. Although in natural soil concentrations, the non-cancer health risk (HQ) from rice consumption was lower for FA473 and FAM; Hg enrichment in the soil of La Mojana region may endanger the health of future populations due to their high consumption of rice.

Migration of mercury in the food chains of the Beloosipovo biocenosis (part 1)

Introduction. Mercury and its compounds are among the most dangerous toxic substances, which makes mercury pollution one of the most urgent environmental issues. The present research objective was to study the accumulation of mercury and its impact on the terrestrial ecosystems in the area of the Beloosipovo mercury deposit (Kemerovo Region, West Siberia, Russia).
 Study objects and methods. The study used standard methods to test soil, herbs, herpetobiont insects, and small mammals. The sampling was conducted at 13 points in the cardinal directions at 0.5, 1.5, and 3 km from the pollution source. The method of atomic absorption was employed to measure the concentration of mercury in the samples prepared by the wet mineralization method.
 Results and discussion. The main components of terrestrial ecosystems revealed no excessive concentration of mercury in the soil. However, the water samples from the Belaya Osipova river demonstrated an excess in the maximum permissible concentration of mercury from 5 to 20% (0.00056–0.00074 mg/L). Further up the food chains, the concentration of mercury in organisms decreased by 1–2 orders of magnitude, depending on the sampling point. The study also revealed Siberian trout lily (Erythronium sibiricum (Fisch. et C. A. Mey) Kryl.), which is protected at the federal and regional levels, as well as several nemoral tertiary relics.
 Conclusion. The decreasing concentration of mercury in the food chains means the ecosystem is under no severe negative impact.

Effects of Polymetallic Ore Occurrences on Mercury Accumulation by Aquatic Biota in River Ecosystems

The study represents the data on metal content in the body of stoneflies Perla pallida Guerin-Meneville, 1838 (Plecoptera, Perlidae) and in muscles of the fish family Cyprinidae from the small tributaries of the Belaya River (Republic of Adygea, Northwest Caucasus) with ore mineralization of various metals including mercury. It was found that mercury (Hg) concentrations in stoneflies are corresponds to from the water basins without local Hg sources. Mercury content in stoneflies depends on season and is more intensive in early ontogenesis in winter than in the warm season. Mercury concentration in 0.01–0.72 mg/kg dry weight can cause the pathomorphological changes in the structure of organs and decrease the adaptive potential in competitive population of stoneflies, in general. The Hg concentration reached 0.09–0.69 mg/kg in the studied fish species (bleak, gudgeons, and barbels) and was similar to concentrations in stonefly larvae. This can be related with low size-weight parameters of fishes in samples as wells as with similar feeding patterns of hydrobionts.

Features of the immune profile and polymorphism of candidate genes in children population of an industrially developed region with excessive contamination of the biological medium with mercury

Introduction. Analyzing the negative impact of technogenic chemicals on the health of the children’s population of industrially developed regions is an urgent problem of preventive medicine. Excessive accumulation of mercury in the human body causes disadaptation changes in the immune regulation of physiological processes. Therefore, the analysis of the features of the immune profile associated with polymorphic variants of candidate genes as markers of early disorders of the child population’s health status is relevant in preserving the health of the population of industrialized regions. Materials and methods. A clinical and laboratory examination of the biological environment of 215 children aged 4-6 years was carried out. The observation group consisted of 133 people living in an industrially developed region. The comparison group consisted of 82 people living in a relatively clean territory. The level of contamination of the biological medium with mercury was determined by inductively coupled plasma mass spectrometry. Identification of CD3+CD4+ -, CD3+CD8+- and CD19+ - lymphocytes was performed by flow cytofluorometry. The study of the phagocytic activity of leukocytes was carried out using formalized ram erythrocytes. The level of IgG production was determined using radial immunodiffusion by Mancini, specific IgG to mercury was carried out using allergosorbent testing with an enzyme label. Identification of single-nucleotide polymorphic variants (SNP) of the GSTA4 (rs3756980), FOXP3 (rs3761547), MTR (rs1805087), TERT (rs10054203) genes was carried out by real-time PCR. Results. Children living near the territory of the chemical industry enterprise in conditions of mercury exposure at a level not exceeding hygienic standards are characterized by an increased level of mercury contamination of urine, exceeding the reference level and the level of the comparison group by 1.8 times (p<0.05). The immune profile of children in the observation group is characterized by a decrease in the CD4+/CD8+ immunoregulatory index due to the decline of CD3+CD4+ helpers and hyperproduction of CD3+CD8+ cytotoxic lymphocytes, inhibition of the phagocytic activity of leukocytes (percentage of phagocytosis, phagocytic number, phagocytic index) against the background of an increase in CD19+ lymphocytes, serum IgG and a marker of specific sensitization - IgG to mercury (p<0.05). Changes in the immune profile of children with an increased level of mercury contamination are associated with the C-allele and TC-heterozygous and CC-homozygous genotypes of the GSTA4 gene (rs3756980), the C-allele and CC-genotype of the FOXP3 gene (rs3761547), the A-allele and AA-genotype of the MTR gene (rs1805087) (OR>1, p<0.05), the G-allele and GG-genotype of the TERT gene (rs10054203) (p<0.05). These genes are responsible for the features of detoxification processes, immunoregulation and longevity programs. Conclusion. The established features of cellular (decrease in CD4+/CD8+ due to CD3+CD4+ deficiency with simultaneous increase in CD3+CD8+, inhibition of phagocytosis) and humoral (hyperproduction of IgG, specific IgG to mercury, CD19+) immunity associated with polymorphic variants of the glutathione S-transferase GSTA4 (rs3756980), transcription factor FOXP3 (rs3761547), MTR (rs1805087), TERT telomerase (rs10054203) in children with excessive contamination of the biological medium with mercury, a complex of immune and genetic markers of the effect and sensitivity of mercury exposure is formed.

Corrigendum: Mercury Accumulation in Marine Sediments—A Comparison of an Upwelling Area and Two Large River Mouths

In the original article, there was a mistake in **Figure 2** as published. **Figure 4 was incorrectly attached instead of Figure 2**. The corrected **Figure 2** appears below. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way as the discussions and conclusions were based on the correct figure. The original article has been updated.

Approaching mercury distribution in burial environment using PLS-R modelling

Mercury environmental cycle and toxicology have been widely researched. Given the long history of mercury pollution, researching mercury trends in the past can help to understand its behaviour in the present. Archaeological skeletons have been found to be useful sources of information regarding mercury loads in the past. In our study we applied a soil multi-sampling approach in two burials dated to the 5th to 6th centuries AD. PLRS modelling was used to elucidate the factors controlling mercury distribution. The model explains 72% of mercury variance and suggests that mercury accumulation in the burial soils is the result of complex interactions. The decomposition of the bodies not only was the primary source of mercury to the soil but also responsible for the pedogenetic transformation of the sediments and the formation of soil components with the ability to retain mercury. The amount of soft tissues and bone mass also resulted in differences between burials, indicating that the skeletons were a primary/secondary source of mercury to the soil (i.e. temporary sink). Within burial variability seems to depend on the proximity of the soil to the thoracic area, where the main mercury target organs were located. We also conclude that, in coarse textured soils, as the ones studied in this investigation, the finer fraction (i.e. silt + clay) should be analysed, as it is the most reactive and the one with the higher potential to provide information on metal cycling and incipient soil processes. Finally, our study stresses the need to characterise the burial soil environment in order to fully understand the role of the interactions between soil and skeleton in mercury cycling in burial contexts.

Templated synthesis of CuCo2O4-modified g-C3N4 heterojunctions for enhanced photoreduction of Hg2+ under visible light

BackgroundThe accumulation of mercury (II) ions (Hg2+) in wastewater causes critical impacts on human health and the whole environment. MethodsThis study report an efficient synthesis of CuCo2O4/g-C3N4 p-n heterojunction by templated growth via triblock copolymer F-127 and mesoporous silica MCM-41 for enhanced photoreduction of Hg2+. Significant FindingsThe 22.6 nm CuCo2O4 nanoparticles were anchored on g-C3N4 at minor content (0.5−2.0 wt. %) as observed by TEM analysis. The formed heterojunctions exhibited mesoporous surface textures with high specific surface areas. In addition, the visible-light harvesting of g-C3N4 was improved by adding CuCo2O4 due to the reduction of the bandgap energy from 2.77 to 2.17 eV. The complete visible-light photocatalytic reduction of Hg2+ utilizing 1.5 wt.% CuCo2O4-modified g-C3N4 was realized with a tremendous rate of 286.5 µmol min−1 after dose tuning at 1.5 gL−1. The enhanced catalytic presentation of this innovative CuCo2O4/g-C3N4 is denoted to the significant separation of photoinduced carriers through the p-n heterojunction's interface. The bearable photocatalytic reduction of Hg2+ for five cycles was also established for the regenerated photocatalyst.

PENGARUH PEMBERIAN EKSTRAK ETANOL KULIT BUAH MANGGIS (Garcinia mangostana, L.) TERHADAP PENURUNAN KADAR LOGAM MERKURI PADA GINJAL MENCIT GALUR SWISS WEBSTER

<p><em>Mangosteen (Garcinia mangostana L.) is known as a plant rich in antioxidants and has various pharmacological activities. This study aims to determine the activity of the ethanolic extract of G. mangostana L. to decrease mercury levels in the kidneys. Mangosteen rind was extracted using 96% ethanol using the maceration method to form a thick extract. The experimental animals used in this study were Swiss Webster strain mice which were grouped into normal group (CMC suspension 0.5%), negative control (induction of HgCl2 solution), positive control (induction of HgCl2 solution followed by administration of curcumin at a dose of 100mg/KgBW). , and the test group was given mangosteen peel extract at a dose of 200mg/kgBW, 400mg/kgBW, 600mg/kgBW. In the test group, mice were induced using HgCl2 for 14 days, followed by administration of ethanol extract of mangosteen rind for 24 days. Observations were made with kidney organ surgery and observations were made using Atomic Absorption Spectrophotometry (AAS) and analyzed using ANOVA. The test results showed mercury accumulation in the negative, positive control group, and the test doses of 200, 400 and 600mg/kgBW, respectively, were 44.3mg/kg, 7.3mg/kg, 36.46mg/kg, 35.7mg/kg. kg and 31.34mg/kgBW with an effective dose of 600mg/KgBW.</em></p>

Recent Advances on the Development of Chemosensors for the Detection of Mercury Toxicity: A Review

The harmful impact of mercury on biological systems is of great concern. Regardless of the efforts made by the regulating agencies, a decrease in Hg2+ concentration has not been realized, and hence mercury accumulation in the environment remains of utmost concern. Designing novel and efficient probes for recognition and detection of toxic metals in environmental samples has been of primary importance. Among the available techniques, probe designs involving the study of spectral properties has been preferred because of its obvious ease of instrumentation. Furthermore, occurrence of significant changes in the visible portion of electronic spectra enables detection by the naked eye, thereby endorsing the preference for development of probes with off-on binary responses to aid in the in-field sample analysis. The prominence is further streamlined to the use of fluorescence to help characterize on-response the cellular detection of Hg2+ with ease. In order to overcome the problem of developing efficient probes or sensors bearing fluorescence on-response mechanism that can work effectively in physiological conditions, various methodologies, such as chemo-dosimetric reaction mechanisms for the designing of new luminescent ligands, are being adopted. Additionally, modified charge transfer processes are also being considered for optical detection of the mercury (II) ion. In this review, all such possible techniques have been discussed in detail.

Evaluation of mercury bioavailability and phytoaccumulation by means of a DGT technique and of submerged aquatic plants in an aquatic ecosystem situated in the vicinity of a cinnabar mine

The ability of submerged aquatic plants (Elodea canadensis, Myriophyllum spicatum, Ceratophyllum demersum) and a natant plant (Eichhornia crassipes) to bioaccumulate mercury was evaluated in a laboratory experiment as well as in a real aquatic ecosystem situated in the vicinity of a cinnabar mine. Moreover, the ability of the diffusive gradients in the thin films technique (DGT) to predict mercury bioavailability for selected aquatic plants was tested. The submerged plants had sufficient bioaccumulation capacity for long-term phytoaccumulation of mercury in a real aquatic ecosystem. The determined bioaccumulation factor was greater than 1000. On average, the submerged plant leaves accumulated 13 times more mercury than the leaves of the natant aquatic plants. Chlorides at concentrations up to 200 mg/L had no statistically significant effect on mercury accumulation, nevertheless, the presence of humic acid in the water environment resulted in its significant (p < 0.002) decrease. A strong positive correlation (r > 0.66) was determined between mercury concentration in the input parts (leaves and/or roots) of the aquatic plants and the flow of mercury into DGT units.

Effects of forest fires on mercury accumulation in soil at the artisanal small-scale gold mining.

In response to the Minamata Convention on Mercury, international organizations, governments, nonprofit organizations, and other institutions as well as individuals have worked to promote the development and implementation of safe and environmentally healthy practices, processes, and products. It is expected that the accumulation of mercury in the natural environment will decrease in volume each year. However, even after Hg ceases to be used, the Hg already accumulated in forests will continue to pose an ecological risk. Forest fires are serious events, partly because they release accumulated Hg from the environment. In this study, the effects of forest fires on the accumulation and chemical species of Hg in soil, related to the mobilization of Hg, were investigated. The research was conducted in secondary forests located near artisanal small-scale gold mining sites, where Hg is used for the amalgamation of gold in Camarines Norte, Philippines. The results showed that the original Hg accumulation level in the burned forest was not as high as that in the control forest, and that burn severity might have affected only the surface soil (0-5cm). However, the proportion of water-soluble Hg, which was derived from ash, was increased by fire. Therefore, it is suggested that forest fires not only increase the release of Hg into the atmosphere but also increase the outflow risk to the aquatic system through rainfall.

Phytoavailability and transfer of mercury in soil-pepper system: Influencing factors, fate, and predictive approach for effective management of metal-impacted spiked soils

Mercury (Hg) contamination and accumulation in food crops is a global threat posing potential health risk to humans. However, Hg phytoavailability in soil-pepper system and its influencing factors largely remain unknown. In this study, a greenhouse pot experiment was conducted to grow peppers using 21 Chinese agricultural soils with varied soil properties and aged Hg levels. Mercury concentration in pepper leaves and fruits ranged from 0.021 to 0.057 mg kg−1 and 0.005–0.022 mg kg−1 respectively, while fruit Hg content in three soils (Anhui, Hubei, Beijing) exceeded the safety limit. Fruit Hg concentration was better positively correlated with soil Mg(NO3)2-extractable Hg content (r = 0.7, P < 0.0001) than soil total Hg content (r = 0.45, P < 0.0001). Highest bioconcentration factor (BCF, ratio of Hg plant to Hg soil) yielded in acidic soils, while the lowest BCF occurred in alkaline soils. Path analysis indicated available-Hg (R2 = 0.40) and total-Hg (R2 = 0.40) had direct positive effects on the pepper fruit Hg concentration, while direct negative effects including pH (R2 = −0.86), organic matter (R2 = −0.7), crystalline-Fe (R2 = −0.68). Those agreed with the stepwise multiple linear regression analysis which yielded a regression predictive model (R2 = 0.73, P < 0.0001). Soil available-Hg, total-Hg, pH, organic matter and crystalline-Fe & Mn were the most influencing factors of Hg phytoavailability. These results provide new insights into the phytoavailability of Hg in soil-pepper system, thus facilitating the management of pepper cultivation in Hg-enriched soils.

Predicted Near-Future Oceanic Warming Enhances Mercury Toxicity in Marine Copepods.

The effects of acute mercury exposure (118µg/L) on the marine copepod Tigriopus japonicus were examined at 22 and 25°C for 24h and compared with controls. Mercury accumulation and seven genes related to antioxidant/stress responses were analyzed after exposure. The 24-h LC50 value decreased in the warmer environment and mercury accumulation was elevated. Under both temperatures, mercury significantly affected the expression of all analyzed genes and probably caused oxidative stress. Intriguingly, at the same mercury concentration, most genes were upregulated at the higher relative to the lower temperature, and the copepods likely initiated more compensatory reactions to counteract increased mercury toxicity associated with the warmer temperature. Overall, this study suggests a molecular mechanism by which marine copepods could respond to future oceanic warming and mercury pollution.

Association between Chromosome 4 and mercury accumulation in muscle of the three-spined stickleback (Gasterosteus aculeatus).

Anthropogenic stressors, such as pollutants, act as selective factors that can leave measurable changes in allele frequencies in the genome. Metals are of particular concern among pollutants, because of interference with vital biological pathways. We use the three‐spined stickleback as a model for adaptation to mercury pollution in natural populations. We collected sticklebacks from 21 locations in Flanders (Belgium), measured the accumulated levels of mercury in the skeletal muscle tissue, and genotyped the fish by sequencing (GBS). The spread of muscle mercury content across locations was considerable, ranging from 21.5 to 327 ng/g dry weight (DW). We then conducted a genome‐wide association study (GWAS) between 28,450 single nucleotide polymorphisms (SNPs) and the accumulated levels of mercury, using different approaches. Based on a linear mixed model analysis, the GWAS yielded multiple hits with a single top hit on Chromosome 4, with eight more SNPs suggestive of association. A second approach, a latent factor mixed model analysis, highlighted one single SNP on Chromosome 11. Finally, an outlier test identified one additional SNP on Chromosome 4 that appeared under selection. Out of all ten SNPs we identified as associated with mercury in muscle, three SNPs all located on Chromosome 4 and positioned within a 2.5 kb distance of an annotated gene. Based on these results and the genome coverage of our SNPs, we conclude that the selective effect of mercury pollution in Flanders causes a significant association with at least one locus on Chromosome 4 in three‐spined stickleback.

Bioaccumulated Mercury by Several Types of Plants in Ex-Traditional Gold Processing Area, Gogorea Village, Buru Island

This study examines the accumulation of metallic mercury by several types of plants in the traditional gold processing area in the village of Gogore, Buru district. The plants that were sampled in this study were guava, lempuyang gajah, and harendong bulu. These three plant species were chosen because they dominate the vegetation in the gold processing area. The analysis results showed that the lempuyang gajah was the plant that accumulated the highest mercury metal, namely in the roots of 16.79 ppm and the leaves of 15.03 ppm. Guava plants accumulated metal mercury in the roots and leaves of 11.73 ppm and 9.90 ppm, respectively. Meanwhile, harendong plants accumulated mercury in the roots and leaves of 2.59 ppm and 10.39 ppm, respectively. The BCF values ​​of guava, lempuyang gajah, and harendong bulu plants were 1.58, 0.41, and 0.39, respectively. Meanwhile, the TF values ​​of the three plants were 0.84, 0.89, and 4.01, respectively. From these results, it can be concluded that the three plants can accumulate mercury in high enough concentrations, so these three types of plants are categorized as hyper tolerant plants and accumulators.

Selenium-amended biochar mitigates inorganic mercury and methylmercury accumulation in rice (Oryza sativa L.)

Rice, as a dominant crop in China and Asia, can be a major route of methylmercury (MeHg) exposure for humans in inland China, especially in those living in mercury (Hg) polluted areas. Soil is the most prominent MeHg accumulation source for rice grains. The development of management practices to reduce MeHg in rice grains is crucial. This study explored the mitigation effect of biochar (BC) and sodium selenite-amended biochar (BC + Se) on MeHg production in paddy soil and accumulation in rice. Mercury-contaminated soil was treated with 1% and 5% of both BC and BC + Se. Soil MeHg concentration slightly increased under 1% BC/BC + Se compared to control soil but decreased at the rate of 5%. Moreover, soil phytoavailable MeHg (P–MeHg) diminished as the amount of Se-amended BC increased. BC + Se effectively mitigated MeHg accumulation in rice grains. The highest average contents of MeHg and inorganic Hg (IHg) in rice seeds were found in the control samples, followed by the 1%-BC, 5%-BC, 1%-BC + Se, and 5%-BC + Se samples. Under the 5%-BC + Se treatment, rice MeHg levels were reduced significantly (94%) compared to the control, and P–MeHg concentrations in soil were lower than all the other experimental groups throughout the rice-growing season. These results demonstrate the effectiveness of BC + Se in reducing MeHg and IHg accumulation in rice and could be employed for remediation of Hg polluted paddies.

Mercury Accumulation in Marine Sediments – A Comparison of an Upwelling Area and Two Large River Mouths

Understanding marine mercury (Hg) biogeochemistry is crucial, as the consumption of Hg-enriched ocean fish is the most important pathway of Hg uptake in humans. Although ocean sediments are seen as the ultimate Hg sink, marine sediment studies on Hg accumulation are still rare. In this context, studying Hg behavior in the marine environment, especially in upwelling environments, is of particular interest due to its importance in these great upwelling regions for the global fishery. There are contradictory statements about the fate of Hg in upwelling regions. Some studies have suggested high biotic reduction of oxidized Hg and gaseous elemental mercury evasion to the atmosphere. More recent work has suggested that in upwelling regions, where productivity is high, evasion of gaseous elemental mercury is diminished due to scavenging and sedimentation of Hg by organic particles. In this study, we compared Hg concentrations and accumulation rates in the past ∼4,300 and 19,400 years derived from sediment cores collected in the Peruvian upwelling region (Peru Margin) and compared them with those of two other cores collected from the sediment fan of the Amazon and a core from the Congo Basin, which is influenced by both seasonal coastal upwelling and discharge from the river. Median Hg concentrations were higher at the Peru Margin (90.7 μg kg–1) and in the Congo Basin (93.4 μg kg–1) than in the Amazon Fan (35.8 μg kg–1). The average Hg accumulation rates in sediments from the Peru Margin (178 μg m–2 yr–1) were factors of ∼4 and ∼39 times higher than those from the Congo Basin (46.7 μg m–2 yr–1) and Amazon Fan (4.52 μg m–2 yr–1), respectively. Principal component analysis (PCA) of the geochemical data set reveals that Amazon Fan sediments are strongly influenced by the deposition of terrestrial material, which is of less importance in the Congo Basin and of minor importance in Peru Margin sediments. Accordingly, Hg export to sediments in upwelling areas largely surpasses that in fans of large rivers that drain large terrestrial catchments. The high Hg accumulation rates in the sediments from the upwelling area and the minor influence of terrestrial Hg fluxes there suggest that atmospheric-derived Hg in upwelling areas is effectively exported to the sediments through scavenging by organic particles.

Ecophysiological effects of mercury bioaccumulation and biochemical stress in the deep-water mesopredator Etmopterus spinax (Elasmobranchii; Etmopteridae)

Mercury (Hg) is a non-essential metal that can have toxic effects on the fitness of organisms and tends to bioaccumulate with age and to biomagnify in higher trophic levels. Few studies have assessed oxidative stress and neurotoxicity in deep-water sharks. This study evaluated early ontogenetic changes and physiological effects (antioxidant defences, oxidative damage, aerobic metabolism and neurotransmission functions) of Hg accumulation in the white muscle and brain tissues of the velvet belly lantern shark Etmopterus spinax from the southern Iberian coast (NE Atlantic). Results suggested that the low mercury concentrations observed may induce acute effects in E. spinax before they reach sexual maturity. We found different Hg concentrations in E. spinax: [Hg] males > [Hg] females; [Hg] muscle > [Hg] brain. Females appeared to have higher redox capability translated into higher activities and levels of antioxidant defences than males. However, higher levels of oxidative damage were also observed in females. Whilst the mechanisms underlying these effects remain unknown, these results suggest differences in mercury accumulation between tissues and sex, and potentially deleterious effects on oxidative stress status and neurophysiology of E. spinax, potentially impairing swimming performance and reproduction, which could subsequently impact on the health of both individuals and population.

Bluefin tuna reveal global patterns of mercury pollution and bioavailability in the world's oceans

Bluefin tuna (BFT), highly prized among consumers, accumulate high levels of mercury (Hg) as neurotoxic methylmercury (MeHg). However, how Hg bioaccumulation varies among globally distributed BFT populations is not understood. Here, we show mercury accumulation rates (MARs) in BFT are highest in the Mediterranean Sea and decrease as North Pacific Ocean > Indian Ocean > North Atlantic Ocean. Moreover, MARs increase in proportion to the concentrations of MeHg in regional seawater and zooplankton, linking MeHg accumulation in BFT to MeHg bioavailability at the base of each subbasin's food web. Observed global patterns correspond to levels of Hg in each ocean subbasin; the Mediterranean, North Pacific, and Indian Oceans are subject to geogenic enrichment and anthropogenic contamination, while the North Atlantic Ocean is less so. MAR in BFT as a global pollution index reflects natural and human sources and global thermohaline circulation.

Mercury accumulation in muscle and liver tissue and human health risk assessment of two resident freshwater fish species in Flanders (Belgium): a multilocation approach.

Detrimental effects of chemical pollution-primarily caused by human activities-on aquatic ecosystems have increasingly gained attention. Because of its hydrophobic qualities, mercury is prone to easily bioaccumulate and biomagnify through the food chain, decreasing biodiversity and eventually also affecting humans. In the present study, accumulated mercury concentrations were measured in muscle and liver tissue of perch (Perca fluviatilis) and European eel (Anguilla anguilla) collected at 26 sampling locations in Flemish (Belgian) waterbodies, allowing a comparison of these species within a variety of environmental situations. Furthermore, effects of size and weight have been assessed, expected to influence accumulation and storage of pollutants. Mercury concentrations in perch ranged up to 1.7 μg g-1 dw (median: 0.29 μg g-1 dw) in muscle and from 0.02 to 0.77 μg g-1 dw (median: 0.11 μg g-1 dw) in liver tissue. For eel, these concentrations were between 0.07 and 1.3 μg g-1 dw (median: 0.39 μg g-1 dw) and between 0.08 and 1.4 μg g-1 dw (median: 0.55 μg g-1 dw) respectively. We found a correlation of accumulated mercury with length in perch, independent of location. Furthermore, a significant difference in accumulated mercury concentrations between the targeted species was measured, with the highest mean concentrations per dry weight in eel liver and muscle tissue. In perch, higher concentrations were found in muscle compared to liver tissue, while in eel, liver tissue showed the highest concentrations. These findings were further considered with concentrations corrected for lipid content, excluding the fat compartment, which is known to a hold negligible portion of the total and methyl mercury concentrations. This confirmed our previous conclusions, except for mercury concentrations in eel. Here there was no longer a significant difference between muscle and liver concentrations. Finally, health risk analyses revealed that only frequent consumption of local eel (> 71 g day-1) could pose risks to humans.