Mercury Hg Research Articles

Presencia de elementos contaminantes como Cd, As, Pb, Se y Hg en carbones de la zona Cundiboyacense, Colombia

Carbones de la zona cundiboyacence fueron estudiados, con el fin de determinar la presencia y cuantificar los contenidos de elementos contaminantes como: cadmio (Cd), arsénico (As), plomo (Pb), selenio (Se) y mercurio (Hg), estos elementos son comparados con los índices de Clarke para carbones del mismo rango. Las muestras de carbón fueron tomadas de frentes de explotación activa y son analizadas mediante análisis próximos, petrográficos y por espectrometría de masas con plasma acoplado inductivamente (ICP-MS). Los resultados revelan que las muestras analizadas presentan contenidos promedio de metales como Pb (15,5 mg•kg-1), Se (16,5 mg•kg-1), Cd (0,55 mg•kg-1) y As (16,05 mg•kg-1) por encima del promedio mundial para carbones del mismo rango y sus concentraciones son mayores a los carbones de la zona norte carbonífera de Colombia, el contenido de Hg es bajo (< 0,08 mg•kg-1). El contenido de estos elementos genera preocupación ambiental ya que de acuerdo a la Agencia de Protección Ambiental de los Estados Unidos (EPA), el límite máximo permitido para el Se, Pb y Cd es de 0.05 mg•kg-1(ppm). Se sugiere realizar estudios específicos, que permitan la recuperación previa y/o utilización.

Mercury Stoichiometric Relationships in a Subtropical Peatland

Spatially variable areas, or hotspots, of elevated mercury (Hg) concentrations in soil, water, and wildlife occur throughout the Everglades wetland ecosystem. This study investigates the stoichiometric controls of Hg relative to soil, water, and biotic components. Surface water, porewater, soil, periphyton, and Gambusia spp. (mosquitofish) were collected from hotspots and non-spot stations and analyzed for various parameters, including total mercury (THg), organic carbon (OC), total carbon (TC), total phosphorus (TP), and total nitrogen (TN) between late 2010 and early 2013. Soil nutrient ratios were significantly different between hotspot and non-hotspot stations, indicating a difference in trophic status and position along the decay continuum or differences in limiting nutrients. Overall, soil total Hg concentrations were negatively correlated with soil TC/TN, while soil TC/TP and soil TN/TP molar ratios and soil THg were negatively correlated at hotspot stations. Meanwhile, mosquitofish THg was negatively correlated with soil TC/TN molar ratio and positively correlated with soil TC/TP and TN/TP molar ratios, suggesting trophic truncation. Soil, surface water, and porewater THg, TC, and OC interactions resulted in significant differences between hotspot and non-hotspot stations and between molar ratios of C, N, and P. Periphyton-surface water THg/OC homeostasis and soil nutrient ratios significantly explained mosquitofish THg concentrations, further indicating a trophic influence on mosquitofish THg and potential hotspot dynamics. Several factors and processes including bottom-up trophic interaction and vegetation influence on Hg accumulation dynamics and food-chain length explain the development and persistence of Hg hotspot formation within the Everglades system.

Mercury Concentrations in Feathers of Adult and Nestling Osprey (Pandion haliaetus) from Coastal and Freshwater Environments of Florida.

We determined mercury (Hg) concentrations in feathers of osprey (Pandion haliaetus), both nestlings (n=95) and adults (n=110), across peninsular Florida and the Florida Keys during February-August 2014. Feathers plucked from nestlings, aged 3-7weeks, contained Hg concentrations that ranged from 0.338 to 45.79mg/kg and averaged 6.92±7.58mg/kg (mean±1SD). Feathers shed from adults contained significantly higher concentrations ranging from 0.375 to 93.65mg/kg, with an average of 17.8±16.1mg/kg. These levels were in the upper range of previously reported feather Hg concentrations of osprey and clearly show that Florida continues to have Hg hotspots that are elevated compared with many other regions. While these concentrations did not exceed levels previously reported in osprey from heavily Hg contaminated areas that showed no evidence of reproductive impairments, we cannot rule out potential individual-level effects to highly exposed nestlings after fledging. Mercury concentrations in nestlings were highest in coastal habitats of Collier and Monroe counties, where ongoing declines in osprey populations also have been documented.

Determination of Elements in Carrot Root by Laser Induced Breakdown Spectroscopy

The elemental composition of the carrot root was investigated by the laser induced breakdown spectroscopy by recording its emission spectrum. The recorded spectrum of carrot root pellet showed the presence of atomic lines of inorganic element as potassium (K), sodium (Na), iron (Fe), calcium (Ca), titanium (Ti), zinc (Zn), mercury (Hg), copper (Cu), magnesium (Mg), strontium (Sr), and cobalt (Co) while spectrum of fresh raw carrot depicted additional organic element as carbon (C), hydrogen (H), nitrogen (N) and oxygen (O). The produced plasma was characterized by characteristic parameters like plasma temperature, electron density, Lorentz fitting etc.

The effect of different TiO2 nanoparticles on the release and transformation of mercury in sediment

The environmental safety of both nano-TiO2 particles and mercury (Hg) pollution has been of widespread concern. Soils and sediments were the main receiving environments of nano-TiO2 and Hg. There was a strong association between nano-TiO2 with Hg compounds. Very limited research has been carried out on the impact of nano-TiO2 on the environmental behavior of Hg in sediments. The objective of this study was to investigate the effects of nano-TiO2 on the release and transformation of Hg in sediments. Two types of TiO2 nanoparticles were employed. Sediment samples were collected in the water level fluctuating zone of the Three Gorges Reservoir, China. Sediment samples spiked with HgCl2 solution were taken as Hg-contaminated sediments. The flooding experiments were conducted using capped borosilicate glass bottles containing 300 ml TiO2 suspensions (0.2 g L−1 and 0.4 g L−1) and 30 g original or Hg-contaminated sediment samples outdoors. All experiments were conducted in triplicate. Water samples were collected at determined interval times over a 60-day period. Sediments were collected on the 60th day. Total Hg (THg) and methylmercury (MHg) in both water and sediment samples and Hg speciation just in sediment samples were determined. A series of control samples without TiO2 addition were also prepared. The results showed that nano-TiO2 particles at high content (4 g kg−1) promoted the release of Hg in sediments, and the anatase particles showed a stronger effect. Methyl Hg concentrations in waters of nano-TiO2 treatments significantly decreased by the 10th day. The effect of nano-TiO2 greatly depended on anatase and rutile particles. After that, methyl Hg concentrations had no significant difference between nano-TiO2 treatments and the control, except 2 g kg−1 rutile treatment by the 20th day. The changes of Hg speciation in sediments demonstrated that nano-TiO2 inhibited the transformation of Hg-bound organic matter into the oxidated state, especially upon 2 g kg−1 rutile treatment. This was consistent with the lower MHg concentrations in the 2 g kg−1 rutile treatment. Both anatase and rutile nano-TiO2 were found to affect the release of Hg in sediment. Nano-TiO2 promoted THg release in sediments and posed an increased risk of Hg contamination in waters, especially for anatase particles. Moreover, nano-TiO2 inhibited the methylation process of Hg in sediments at the initial stage of flooding and could affect the transformation of Hg speciation in sediments, especially for low-content rutile particles.

Tuning the Adsorption of Elemental Mercury by Small Gas-Phase Palladium Clusters: First-Principles Study.

Density functional theory (DFT) calculations were performed to study the nature of interaction of elemental mercury (Hg) with small palladium clusters (Pdn, n = 1-6) using generalized gradient approximation method. Results of these calculations showed stronger binding of Hg with Pd2 cluster, which, therefore, was chosen for further investigation as presented in the latter part of the third section of this report. This extended study explains the binding mechanism of Hg with alloys of Pd dimers, PdM (M = Pd, Pt, Cu, Ag, Au) in neutral, cationic, and anionic states. Interaction energy of Hg with palladium dimer follows the trend Pd2+ > Pd2 > Pd2-. For all of the above PdM complexes, the strength of Hg binding is found to be highest in their cationic states. Mixing of Pt and Au enhances the reactivity of the cationic Pd2 dimers, decreases it for their neutral counterparts, and does not affect much in the anionic states. Natural bond orbital (NBO) analysis indicates that Hg binding takes place because of the charge transfer from its s-orbitals primarily to the d-orbitals of M atoms followed by back-donation of charges from their s-orbitals to the p-orbitals of Hg atom. Moreover, the amount of charge transfer from Hg(s)→M(d) correlates with the Hg binding energy in Hg-PdM0,± complexes. Binding of Hg in cationic Hg-PdM complexes conjointly depends on energies of the lowest unoccupied molecular orbitals of the PdM+ dimers as well as NBO partial charges on adsorbed Hg.

Essential and toxic elements in meat of wild birds

ABSTRACTEssential and toxic elements were determined by inductively coupled plasma–atomic emission spectrometry (ICP-AES), mass spectrometry (MS), and atomic absorption (AS) in meat of 14 migratory birds originating from central and northern Europe to provide baseline data regarding game meat consumed in central Italy. In all samples analyzed, cobalt (Co) and chromium (Cr) (total) levels were <0.326 mg/kgww. For nonessential or toxic elements, arsenic (As), barium (Ba), cadmium (Cd), stannous (Sn), thallium (Tl), tellurium (Te), titanium (Ti), cerium (Ce), lantanium (La), and uranium (U) concentrations were <0.326 mg/kgww, thorium (Th) <1.63 mg/kgww, and mercury (Hg) <0.0163 mg/kgww. When detectable, lead (Pb) concentrations always exceeded maximal admissible levels for metal (0.1 mg/kg ww) established by the European Commission for meat. These findings indicate that elevated Pb concentrations in game ingested by humans may be a cause for concern.

Photochemical aqueous mercury removal: effects of DOM and DO

Photochemical reactions between mercury (Hg) and dissolved organic matter were studied to understand what conditions would promote mercury volatilisation from solution. Prepared solutions of mercury (II) nitrate and humic acid (HA) (at different ratios) were exposed to 254-nm ultraviolet irradiation and a continuous purge with nitrogen, air or oxygen gas to create three different dissolved oxygen (DO) concentrations. As HA was introduced into the system with a nitrogen purge, the overall quantity of dissolved gaseous mercury after 60 min, and subsequent mercury removal, decreased. An analysis of variance indicated that there is only a 61% confidence level that the 1:10 and the 1:100 mercury–HA ratios are statistically different, suggesting that the decrease in mercury removal as HA concentration increased cannot be solely attributed to mercury binding with sulfur or other functional groups on the HA. Experiments indicated a positive correlation of HA oxidation as DO increased with an air and oxygen purge.

Prenatal exposure to mercury and ultrasound measures of fetal growth in a Spanish birth cohort study

Introduction: Levels of mercury (Hg) has been reported as relatively high in Spanish population, including vulnerable groups such as pregnant women, fetuses, and children. There is little but sugge...

Effects of Mercury in Neurological and Cognitive Development: a Cohort Study in the Peruvian Amazon

Background: In the Amazon, artisanal gold-mining results in mercury (Hg) deposition in the soil and rivers, leading to bioaccumulation of methylmercury (MeHg) in fish. Although MeHg is a known neur...

Associations between blood mercury and head circumference at birth: modification by sex and maternal GSTM1/GSTT1 polymorphism

Introduction Some studies have reported effects of prenatal mercury (Hg) on reduced head circumference at birth; however, modifying effects of maternal glutathione S-transferase M1 (GSTM1) or gluta...

Mercury concentrations in fish from three major lakes in north Mississippi: Spatial and temporal differences and human health risk assessment

ABSTRACTThe goal of this study was to compare total mercury (Hg) concentrations in fish muscle tissue and assess consumption health risks of fish collected from three north Mississippi lakes (Sardis, Enid, and Grenada) that are extensively used for fishing and recreation. Largemouth bass (LMB; n = 64), channel catfish (CC; n = 72), and white crappie (WC; n = 100), which represent a range of trophic levels, were collected during spring 2013 and 2014. Creel data estimated that anglers harvested approximately 370,000 kg of WC, 27,000 kg of CC, and 15,000 kg of LMB from the lakes annually. Median Hg wet weight concentrations were highest in LMB (443 ng/g), followed by CC (211 ng/g) and WC (192 ng/g). Fish-Hg concentrations were lower than those reported in fish >10 years ago. There were significant differences between lakes consistent across species. Grenada length-normalized fish-Hg concentrations were higher than those from Enid and Sardis. Because existing consumption advisories for CC are length based, the lack of relationship between length and Hg concentration indicated that the recommendations may not be sufficiently protective. Further, five different risk assessment paradigms yielded hazard quotient (HQ) values suggesting that existing fish consumption advisories may be insufficient to protect adults and especially children from exposure to Hg.

Annual ambient atmospheric mercury speciation measurement from Longjing, a rural site in Taiwan.

The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60%) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000-2012.

Reducing mercury usage in artisanal gold mines using grinding and sieving

Gold extraction in primitive artisanal mines usually involves the over-usage of mercury (Hg). This practice results in significant environmental contamination, but is difficult to eliminate due to its effectiveness. Any alternative must be simple, inexpensive and visually effective. This paper proposes a novel, chemical-free method for extracting gold from gravity middlings which has potential as an effective alternative to Hg amalgamation. This method exploits the differences in relative malleability, rather than density, of gold and waste products by submitting concentrates to grinding in a rod mill. The grind products are separated through a sieve, where flattened gold particles are captured on the oversize while brittle waste reports to the fines. Recoveries often exceeded 90%, with nearly pure raw gold separated after only minutes of grinding. While recently adapted to the modern Yukon placer fields, this method has potential to reduce Hg usage by miners in more primitive settings.

Low doses of mercuric chloride cause the main features of anti-nucleolar autoimmunity in female outbred CFW mice.

The growth of the influence of anthropogenic factors aimed on the improvement of human life has its side effect, for example, living organisms receive increasing exposure to toxic mercuric compounds. Experimental data show that mercury (Hg) salts are able to induce systemic autoimmunity in rodents. This Hg-induced autoimmune process (HgIA) is characterized by T cell-dependent polyclonal activation of B lymphocytes, increased level of serum immunoglobulin G1 (IgG1) and immunoglobulin E (IgE), production of antinucleolar autoantibodies (ANoA), and immune complex deposition in multiple organs. HgIA in mice is used as a model of human systemic autoimmune disorders. However, the dose of mercuric chloride (HgCl2) usually used in laboratory mice to induce HgIA is above the allowable limit for everyday levels of Hg exposure in humans. So, we decided to determine the lowest dose of HgCl2 that is able to trigger autoimmunity in outbred Carworth Farms Swiss Webster (CFW) mice not genetically prone to HgIA development. The lowest dose (50 µg/kg body weight (b.w.)/week) was chosen to match the World Health Organization provisional weekly tolerable intake of total Hg for humans. We also tested HgCl2 at 500 and 1500 µg/kg b.w./week (6.5- and 2-fold less than usually used for induction of HgIA in mice). We found that even the lowest dose of Hg resulted in a statistically significant increase in serum level of IgG1 after 8 weeks of treatment. HgCl2 in doses 500 and 1500 µg/kg b.w./week resulted in a significant increase in serum level of IgG1 after 4 weeks of treatment, followed by ANoA production. Sera of HgCl2-treated mice stained the regions in which the major autoantigen in HgIA, fibrillarin, was revealed. These results suggest that low doses of Hg are able to induce the main features of HgIA in genetically heterozygous mice, and that humans chronically exposed to low doses of Hg may be at risk of autoimmunity induction regardless of their genetic background.

Total atmospheric mercury deposition in forested areas in South Korea

Abstract. In this study, mercury (Hg) was sampled weekly in dry and wet deposition and throughfall and monthly in litterfall, and as it was volatilized from soil from August 2008 to February 2010 to identify the factors influencing the amount of atmospheric Hg deposited to forested areas in a temperate deciduous forest in South Korea. For this location there was no significant correlation between the estimated monthly dry deposition flux (litterfall + throughfall – wet deposition) (6.7 µg m−2 yr−1) and directly measured dry deposition (9.9 µg m−2 yr−1) likely due primarily to Hg losses from the litterfall collector. Dry deposition fluxes in cold seasons (fall and winter) were lower than in warmer seasons (spring and summer). The volume-weighted mean (VWM) Hg concentrations in both precipitation and throughfall were highest in winter, likely due to increased scavenging by snow events. Since South Korea experiences abundant rainfall in summer, VWM Hg concentrations in summer were lower than in other seasons. Litterfall fluxes were highest in the late fall to early winter, when leaves were dropped from the trees (September to November). The cumulative annual Hg emission flux from soil was 6.8 µg m−2 yr−1. Based on these data, the yearly deposition fluxes of Hg calculated using two input approaches (wet deposition + dry deposition or throughfall + litterfall) were 6.8 and 3.6 µg m−2 yr−1, respectively. This is the first reported study which measured the amount of atmospheric Hg deposited to forested areas in South Korea, and thus our results provide useful information to compare against data related to Hg fate and transport in this part of the world.

Traditional living in the Amazon: Extended breastfeeding, fish consumption, mercury exposure and neurodevelopment

Background: Features of traditional living in the Amazon Basin (high fish consumption and long breastfeeding) are likely to expose children to Mercury (Hg).Aim: To study neurodevelopment in 690 children in relation to prolonged breastfeeding and mercury exposure.Subjects and methods: Three groups of breastfeeding children were formed: Group 1 (breastfed for 6 months), Group 2 (7–12 months) and Group 3 (extending up to 24 months). Neurodevelopment was assessed as age of walking, age of talking and the Bayley Scales of Infant Development–BSID. Mercury exposure was assessed from Thimerosal-containing vaccines and fish consumption from hair Hg (HHg).Results and conclusions: HHg increased in children and decreased in mothers at 24 months. Frequency of fish consumption was significantly correlated with maternal HHg at birth (Spearman’s r = 0.8583; p = 0.0001); likewise, there was a significant correlation between duration of breastfeeding and children’s HHg (Spearman’s r = 0.15; p = 0.0018). Extended breastfeeding did not influence the Mental Development Index–MDI or Psychomotor Development Index–PDI, but maternal education and HHg (marker of fish consumption) interacted positively and significantly with both. Frequency of maternal fish consumption and education had a positive association with BSID scores; it is speculated that maternal education and nutrients in fish have an opposing effect on Hg exposure.

Evaluation of vulnerability of Suillus variegatus and Suillus granulatus mushrooms to sequester mercury in fruiting bodies

ABSTRACTThis work determined the mercury (Hg) contents and bioconcentration potential of two Suillus mushrooms, and the probable dietary intake of this element from a mushroom meal. The determination of total Hg content of fungal and soil samples was performed using cold-vapour atomic absorption spectroscopy by a direct sample thermal decomposition coupled with gold wool trap of Hg and its further desorption and quantitative measurement at a wavelength of 253.7 nm. The median values of Hg contents (mg kg−1 dry biomass) in 213 specimens of S. variegatus from 12 background areas varied widely from 0.087 to 0.51 for caps and from 0.041 to 0.24 for stipes. In 52 specimens of S. granulatus, the Hg contents ranged from 0.30 to 0.41 for caps and from 0.058 to 0.14 for stipes. Both species could be classified as moderate accumulators of Hg and the median bioconcentration factor values ranged from 7.0 to 14 (caps) and 2.1 to 13 (stipes) for S. variegatus and 9.5 (caps) and 1.3 (stipes) for S. granulatus. The estimated intake rates of Hg with the consumption of 300-g caps were from 0.0026 to 0.015 per capita or from 0.000037 to 0.00022 mg kg−1 body mass and this do not indicate any cause for concern associated with eating a meal once or more in a week during the mushrooming season.

Uji Toksisitas Letal dan Subletal Logam Berat Merkuri (Hg) Terhadap Ikan Nilem (Osteochilus hasselti)

Mercury (Hg) is a heavy metal could pollute the river. Hg impacts on aquatic organism chronically. The influence of chemical toxic on aquatic organisms could be determined using toxicity (lethal and sublethal) tests. Osteochilus hasselti could be an object for toxicity test. A research, aiming to find LC50-96h concentration, was to find letal and subletal effects of Hg on erythrocyte and hematocryte changes. An experimental method applied Completely Randomized Design. The research was devided into 3 stages, i.e. preliminary, lethal toxicity (LC50-96h) and sublethal toxicity tests, in triplicates. Sampling of sublethal test was performed after an exposure time of 96 h (4 days) and 288 h (12 days). Lethal toxicity test data were analyzed as probit and data from sublethal toxicity test were F-tested. The result showed that LC50-96h of Hg on Osteochilus hasselti was 0.39 mg/L. The sublethal effect of Hg decreased erythrocyte ad hematocryte counts in parallel with increasing its concentration and its exposure time.Keywords: Hg, toxicity, LC50-96 hours, erythrocytes, hematocrits.

Impacts of forest harvesting on mobilization of Hg and MeHg in drained peatland forests on black schist or felsic bedrock.

Forest harvesting, especially when intensified harvesting method as whole-tree harvesting with stump lifting (WTHs) are used, may increase mercury (Hg) and methylmercury (MeHg) leaching to recipient water courses. The effect can be enhanced if the underlying bedrock and overburden soil contain Hg. The impact of stem-only harvesting (SOH) and WTHs on the concentrations of Hg and MeHg as well as several other variables in the ditch water was studied using a paired catchment approach in eight drained peatland-dominated catchments in Finland (2008-2012). Four of the catchments were on felsic bedrock and four on black schist bedrock containing heavy metals. Although both Hg and MeHg concentrations increased after harvesting in all treated sites according to the randomized intervention analyses (RIAs), there was only a weak indication of a harvest-induced mobilization of Hg and MeHg into the ditches. Furthermore, no clear differences between WTHs and SOH were found, although MeHg showed a nearly significant difference (p = 0.06) between the harvesting regimes. However, there was a clear bedrock effect, since the MeHg concentrations in the ditch water were higher at catchments on black schist than at those on felsic bedrock. The pH, suspended solid matter (SSM), dissolved organic carbon (DOC), and iron (Fe) concentrations increased after harvest while the sulfate (SO4-S) concentration decreased. The highest abundances of sulfate-reducing bacteria (SRB) were found on the sites with high MeHg concentrations. The biggest changes in ditch water concentrations occurred first 2years after harvesting.