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Sample records for hg thg concentrations

  1. Persistent Hg contamination and occurrence of Hg-methylating transcript (hgcA) downstream of a chlor-alkali plant in the Olt River (Romania).

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    Bravo, Andrea G; Loizeau, Jean-Luc; Dranguet, Perrine; Makri, Stamatina; Björn, Erik; Ungureanu, Viorel Gh; Slaveykova, Vera I; Cosio, Claudia

    2016-06-01

    Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl(-) concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.

  2. Spatial and temporal patterns of mercury concentrations in freshwater fish across the Western United States and Canada

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    Eagles-Smith, Collin A.; Ackerman, Josh; Willacker, James J.; Tate, Michael T.; Lutz, Michelle A; Fleck, Jacob; Stewart, Robin; Wiener, James G.; Evers, David C.; Lepak, Jesse M; Davis, Jay A; Pritz, Colleen Flanagan

    2016-01-01

    Methylmercury contamination of fish is a global threat to environmental health. Mercury (Hg) monitoring programs are valuable for generating data that can be compiled for spatially broad syntheses to identify emergent ecosystem properties that influence fish Hg bioaccumulation. Fish total Hg (THg) concentrations were evaluated across the Western United States (US) and Canada, a region defined by extreme gradients in habitat structure and water management. A database was compiled with THg concentrations in 96,310 fish that comprised 206 species from 4262 locations, and used to evaluate the spatial distribution of fish THg across the region and effects of species, foraging guilds, habitats, and ecoregions. Areas of elevated THg exposure were identified by developing a relativized estimate of fish mercury concentrations at a watershed scale that accounted for the variability associated with fish species, fish size, and site effects. THg concentrations in fish muscle ranged between 0.001 and 28.4 (μg/g wet weight (ww)) with a geometric mean of 0.17. Overall, 30% of individual fish samples and 17% of means by location exceeded the 0.30 μg/g ww US EPA fish tissue criterion. Fish THg concentrations differed among habitat types, with riverine habitats consistently higher than lacustrine habitats. Importantly, fish THg concentrations were not correlated with sediment THg concentrations at a watershed scale, but were weakly correlated with sediment MeHg concentrations, suggesting that factors influencing MeHg production may be more important than inorganic Hg loading for determining fish MeHg exposure. There was large heterogeneity in fish THg concentrations across the landscape; THg concentrations were generally higher in semi-arid and arid regions such as the Great Basin and Desert Southwest, than in temperate forests. Results suggest that fish mercury exposure is widespread throughout Western US and Canada, and that species, habitat type, and region play an important

  3. Mercury and methylmercury concentrations in high altitude lakes and fish (Arctic charr) from the French Alps related to watershed characteristics.

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    Marusczak, Nicolas; Larose, Catherine; Dommergue, Aurélien; Paquet, Serge; Beaulne, Jean-Sébastien; Maury-Brachet, Régine; Lucotte, Marc; Nedjai, Rachid; Ferrari, Christophe P

    2011-04-15

    Total mercury (THg) and methylmercury (MeHg) concentrations were measured in the muscle of Arctic charr (Salvelinus alpinus) and in the water column of 4 lakes that are located in the French Alps. Watershed characteristics were determined (6 coverage classes) for each lake in order to evaluate the influence of watershed composition on mercury and methylmercury concentrations in fish muscle and in the water column. THg and MeHg concentrations in surface water were relatively low and similar among lakes and watershed characteristics play a major role in determining water column Hg and MeHg levels. THg muscle concentrations for fish with either a standardized length of 220mm, a standardized age of 5 years or for individualuals did not exceed the 0.5mg kg(-1) fish consumption advisory limit established for Hg by the World Health Organization (WHO, 1990). These relatively low THg concentrations can be explained by watershed characteristics, which lead to short Hg residence time in the water column, and also by the short trophic chain that is characteristic of mountain lakes. Growth rate did not seem to influence THg concentrations in fish muscles of these lakes and we observed no relationship between fish Hg concentrations and altitude. This study shows that in the French Alps, high altitude lakes have relatively low THg and MeHg concentrations in both the water column and in Arctic charr populations. Therefore, Hg does not appear to present a danger for local populations and the fishermen of these lakes.

  4. Spatio-temporal variations in biomass and mercury concentrations of epiphytic biofilms and their host in a large river wetland (Lake St. Pierre, Qc, Canada).

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    Hamelin, Stéphanie; Planas, Dolors; Amyot, Marc

    2015-02-01

    Within wetlands, epiphytes and macrophytes play an important role in storage and transfer of metals, through the food web. However, there is a lack of information about spatial and temporal changes in their metal levels, including those of mercury (Hg), a key priority contaminant of aquatic systems. We assessed total mercury (THg) and methylmercury (MeHg) concentrations of epiphyte/macrophyte complexes in Lake St. Pierre, a large fluvial lake of the St. Lawrence River (Québec, Canada). THg and MeHg concentrations were ten fold higher in epiphytes than in macrophytes. THg concentrations in epiphytes linearly decreased as a function of the autotrophic index, suggesting a role of algae in epiphyte Hg accumulation, and % of MeHg in epiphytes reached values as high as 74%. Spatio-temporal variability in THg and MeHg concentrations in epiphytes and macrophytes were influenced by water temperature, available light, host species, water level, dissolved organic carbon and dissolved oxygen.

  5. Basal mercury concentrations and biomagnification rates in freshwater and marine food webs: Effects on Arctic charr (Salvelinus alpinus) from eastern Canada

    Energy Technology Data Exchange (ETDEWEB)

    Velden, S. van der, E-mail: sdorn@uwaterloo.ca [Department of Biology, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1 (Canada); Dempson, J.B. [Fisheries and Oceans Canada, St. John' s, Newfoundland and Labrador, Canada, A1C 5X1 (Canada); Evans, M.S. [Environment Canada, Saskatoon, Saskatchewan, Canada, S7N 3H5 (Canada); Muir, D.C.G. [Environment Canada, Burlington, Ontario, Canada, L7R 4A6 (Canada); Power, M., E-mail: m3power@uwaterloo.ca [Department of Biology, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1 (Canada)

    2013-02-01

    Patterns of total Hg (THg) and methyl Hg (MeHg) biomagnification were investigated in six pairs of co-located lacustrine and marine food webs supporting a common predator, Arctic charr. Mercury biomagnification rates (the slope of log Hg concentration versus δ{sup 15}N-inferred trophic level) did not differ significantly between the two feeding habitats for either THg or MeHg, but THg and MeHg concentrations at the base of the food web were higher in the lacustrine environment than in the marine environment. The proportion of THg as MeHg was related to trophic level, and the relationship was statistically similar in the lacustrine and marine habitats. The biomagnification rate of MeHg exceeded that of THg in both habitats. We conclude that the known difference in Hg concentration between anadromous and non-anadromous Arctic charr is driven by differential Hg concentrations at the base of the lacustrine and marine foodwebs, and not by differential biomagnification rates. - Highlights: ► Concentrations of total mercury ([THg]) and methylmercury ([MeHg]) were measured in 6 paired lacustrine and marine food webs. ► Biomagnification rates (slopes of [THg] or [MeHg] versus δ{sup 15}N-inferred trophic level) were similar in the two habitat types. ► Mercury concentrations at the base of the food web were higher in lacustrine than in marine food webs. ► The percentage of methylated mercury increased with trophic level similarly in the two habitat types. ► The biomagnification rate of MeHg exceeded that of THg in both habitats.

  6. 基于T-Hg2+-T及G四聚体自身熄灭能力的"Turn on"型单标记DNA荧光探针用于碘离子的检测%Single-labeled "Turn on" Fluorescent Oligonucleotide Probe for Iodide Detection Based on T-Hg2+-T and Inherent Quenching Ability of G-quadruplex

    Institute of Scientific and Technical Information of China (English)

    朱颖; 刘沛; 羊小海; 何磊良; 李清照; 王青; 王柯敏; 黄晋; 刘剑波

    2012-01-01

    A simple and "Turn on" type iodide anion assay method was developed, based on the inherent quenching ability of G-quadruplex and fidelity of the " thymine-Hg2+ -thymine" binding motif. A T-rich sequence was labeled with 6-carboxyfluorescein(FAM) at its 5'-end, nearby the 3'-end was a G-rich sequence which could form G-quadruplex structure instead of traditional quenchers. Upon addition of Hg2+, T-rich sequence folded into a hairpin structure which led the G-quadruplex near to the FAM, and the FAM was quenched by the G-quadruplex owning to photoinduced electron transfer between the dye and the G-quadruplex. After the addition of iodide, the fluorescence of FAM recovered considering that iodide could bind with Hg2+. The novel method for the determination of iodide was developed in linear range of 50—500 nmol/L, with the detection limit(3σ) of 30 nmol/L. This proposed method was highly selective and other anions have no interfering effects on the determination, which was successfully applied for analysis of real samples with the recovery from 92%-109% , and the RSD<4% (n=4).%利用G四聚体可以熄灭荧光的特性以及T-Hg2+-T的特殊结构,发展了一种简便的"Turn on”型碘离子检测新方法.设计了一条5'端标有荧光基团的富T序列,3'端采用能形成G四聚体的富G序列代替传统的熄灭基团.加入汞离子后,富T序列形成T-Hg2+-T机构发生折叠,G四聚体靠近荧光基团,发生光诱导电子转移,使荧光被熄灭.若加入碘离子,碘离子会与汞离子形成较稳定的配合物,汞离子从DNA上被竞争下来,探针的荧光得以恢复,且荧光强度与50 ~ 500 nmol/L的碘离子呈良好线性关系,检出限为30 nmol/L.本方法选择性好,10倍于碘离子浓度的其它常见阴离子干扰较小.检测自来水样中碘离子的回收率为92%~ 109%,相对标准偏差RSD<4%(n=4).

  7. Importance of Dissolved Neutral Hg-Sulfides, Energy Rich Organic Matter and total Hg Concentrations for Methyl Mercury Production in Sediments

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    Drott, A.; Skyllberg, U.

    2007-12-01

    Methyl mercury (MeHg) is the mercury form that biomagnifies to the greatest extent in aquatic food webs. Therefore information about factors determining MeHg concentrations is critical for accurate risk assessment of contaminated environments. The concentration of MeHg in wetlands and sediments is the net result of: 1) methylation rates, 2) demethylation rates, and 3) input/output processes. In this study, the main controls on Hg methylation rates and total concentrations of MeHg, were investigated at eight sites in Sweden with sediments that had been subjected to local Hg contamination either as Hg(0), or as phenyl-Hg. Sediments were selected to represent a gradient in total Hg concentration, temperature climate, salinity, primary productivity, and organic C content and quality. Most sediments were high in organic matter content due to wood fibre efflux from pulp and paper industry. The pore water was analysed for total Hg, MeHg, DOC, H2S(aq), pH, DOC, Cl and Br. The chemical speciation of Hg(II) and MeHg in pore water was calculated using equilibrium models. Potential methylation and demethylation rates in sediments were determined in incubation experiments at 23° C under N2(g) for 48 h, after addition of isotopically enriched 201Hg(II) and Me204Hg. In all surface (0-20 cm) sediments there was a significant (pproduction overruled degradation and input/output processes of MeHg in surface sediments, and that % MeHg in surface sediments may be used as a proxy for net production of MeHg. To our knowledge, these are the first data showing significant positive relationships between short term (48 h) MeHg production and longer term accumulation of MeHg, across a range of sites with different properties (1). If MeHg was not normalized to total Hg, the relationship was not significant. For sub-sets of brackish waters (pproductivity freshwaters (pproductivity freshwater (p=0.048, n=6), the sum of neutral Hg-sulfides [Hg(SH)20 (aq)] and [HgS0 (aq)] in the sediment pore

  8. FEBEX II Project THG Laboratory Experiments

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    Missana, T.

    2004-07-01

    The main roles of the bentonite in a radioactive waste repository is to act as a geochemical barrier against the radionuclides migration. The effectiveness of this geochemical barrier depends on the surface properties of the solid phases and on the physico-chemical environment generated by the interaction of the solid phases with the groundwater. Within the FEBEX (Full-scale Engineered Barriers Experiment) project, a program of laboratory tests was designed to study and to understand the processes taking place in the clay barrier. Since the first stages of the project, these laboratory tests enabled to isolate different processes, making easier their interpretation, and provided fundamental parameters to be used in the Thermo Hydro Mechanical (THM) and Thermo Hydro Geochemical (THG) models. Additionally, experimental data enabled to check the predictive capability of these models. In the second phase of the project, laboratory tests focused on all those relevant aspects not sufficiently covered during FEBEX I. Particularly, the following main objectives were proposed for the THG investigations during FEBEX II : Attainment of a reliable description of the pore water chemistry at different geochemical conditions. Identification of the different types of water present in the bentonite and to determine the amount of available water for the solute transport.Evaluation of the potential effects of the extraction pressure in the chemical composition of the water obtained by squeezing methods.Study of the effects of the exchange complex in the rheological properties of the clay.Identification and modelling of the surface processes occurring in smectite, determination of the solubility constants of smectite and the formation constants of the surface complexes.Understanding of the mechanisms involved in the sorption of different radionuclides in the bentonite. Investigation of the diffusion mechanisms of conservative neutral and anionic species to have a deeper insight on the

  9. Bistable mode of THG for femtosecond laser pulse

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    Trofimov, Vyacheslav A.; Sidorov, Pavel S.; Kuchik, Igor E.

    2016-09-01

    We develop an analytical solution for the THG problem with taking into account self- and cross- modulation of interacting waves. Consideration is made in the framework of long pulse duration approximation and plane wave approximation. Using the original approach, we obtain the explicit solution of Schrödinger equations describing the THG in the framework under consideration both for zero-value amplitude of a wave with triple frequency and for its non-zero value. It should be stressed that the main feature of our approach consists in conservation laws using, which correspond to wave interaction process. We found various regimes of frequency trebling and showed that the THG process possesses a bistable feature under certain condition. We found out also the THG mode, at which the intensities of interacting waves do not change along their propagation coordinate. This leads to existence of soliton solution for THG of femtosecond laser pulses.

  10. Hg concentrations in fish from coastal waters of California and Western North America

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    Davis, Jay; Ross, John; Bezalel, Shira; Sim, Lawrence; Bonnema, Autumn; Ichikawa, Gary; Heim, Wes; Schiff, Kenneth C; Eagles-Smith, Collin A.; Ackerman, Josh

    2016-01-01

    The State of California conducted an extensive and systematic survey of mercury (Hg) in fish from the California coast in 2009 and 2010. The California survey sampled 3483 fish representing 46 species at 68 locations, and demonstrated that methylHg in fish presents a widespread exposure risk to fish consumers. Most of the locations sampled (37 of 68) had a species with an average concentration above 0.3 μg/g wet weight (ww), and 10 locations an average above 1.0 μg/g ww. The recent and robust dataset from California provided a basis for a broader examination of spatial and temporal patterns in fish Hg in coastal waters of Western North America. There is a striking lack of data in publicly accessible databases on Hg and other contaminants in coastal fish. An assessment of the raw data from these databases suggested the presence of relatively high concentrations along the California coast and in Puget Sound, and relatively low concentrations along the coasts of Alaska and Oregon, and the outer coast of Washington. The dataset suggests that Hg concentrations of public health concern can be observed at any location on the coast of Western North America where long-lived predator species are sampled. Output from a linear mixed-effects model resembled the spatial pattern observed for the raw data and suggested, based on the limited dataset, a lack of trend in fish Hg over the nearly 30-year period covered by the dataset. Expanded and continued monitoring, accompanied by rigorous data management procedures, would be of great value in characterizing methylHg exposure, and tracking changes in contamination of coastal fish in response to possible increases in atmospheric Hg emissions in Asia, climate change, and terrestrial Hg control efforts in coastal watersheds.

  11. Hg concentrations and related risk assessment in coral reef crustaceans, molluscs and fish from New Caledonia

    Energy Technology Data Exchange (ETDEWEB)

    Chouvelon, Tiphaine [Littoral Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite La Rochelle, 2 Rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France); Warnau, Michel [International Atomic Energy Agency-Marine Environment Laboratories (IAEA-MEL), 4 Quai Antoine Ier, MC-98000 (Monaco); Churlaud, Carine [Federation de Recherche en Environnement pour le Developpement Durable (FR-EDD), FR CNRS 3097, Centre Commun d' Analyses, 5 Perspectives de l' Ocean, F-17071 La Rochelle Cedex 9 (France); Bustamante, Paco [Littoral Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite La Rochelle, 2 Rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France)], E-mail: pbustama@univ-lr.fr

    2009-01-15

    There is a dramatic lack of data on Hg levels in marine organisms from tropical areas, and in particular from New Caledonia. For the first time, this study reports the total Hg concentrations in the tissues of several marine taxa from the New Caledonian lagoon. Seafood from both wild and farmed populations was considered. Hg concentrations varied over three orders of magnitudes according to factors including species, age (size/weight), trophic level, lifestyle and geographical origin. Taking into account the edible tissues, estimations of the amount of flesh that should be consumed by a 60-kg person to reach the Hg Provisional Tolerable Weekly Intake (PTWI) reveal acceptable risk for Human health in general. However, a risk was clearly identified in one site of the lagoon (i.e. Grande Rade) where high Hg concentrations were measured. These concentrations were higher than values reported in the current literature. - This work reports the first assessment of Hg levels in edible organisms from the New Caledonian lagoon and the associated risk linked to their consumption by Human.

  12. Using MOF-74 for Hg2+ removal from ultra-low concentration aqueous solution

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    Xiong, Yang Yang; Li, Jian Qiang; Gong, Le Le; Feng, Xue Feng; Meng, Li Na; Zhang, Le; Meng, Pan Pan; Luo, Ming Biao; Luo, Feng

    2017-02-01

    Mercury (Hg2+) ions have very high toxicity and widely spread as environmental pollutants. At present, many efforts have been taken to remove the hazardous materials of mercury(II) by adsorption, and it is highly desirable to develop a novel adsorbent with high adsorptive capacities. However it is still a big challenge to remove the ultra-low-concentration mercury ions from water. In this paper, MOF-74-Zn is explored for such function, showing high removal rate of Hg(II) from water without any pretreatment, especially for the ultra-trace Hg(II) ions in the ppb magnitude with the removal rate reaching to 54.48%, 69.71%, 72.26% when the initial concentration of Hg(II) is 20ppb, 40ppb, 50ppb, respectively.

  13. Reservoirs and water management influence fish mercury concentrations in the western United States and Canada

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    Willacker, James J.; Eagles-Smith, Collin A.; Lutz, Michelle A.; Tate, Michael T.; Lepak, Jesse M.; Ackerman, Josh

    2016-01-01

    Anthropogenic manipulation of aquatic habitats can profoundly alter mercury (Hg) cycling and bioaccumulation. The impoundment of fluvial systems is among the most common habitat manipulations and is known to increase fish Hg concentrations immediately following impoundment. However, it is not well understood how Hg concentrations differ between reservoirs and lakes at large spatial and temporal scales or how reservoir management influences fish Hg concentrations. This study evaluated total Hg (THg) concentrations in 64,386 fish from 883 reservoirs and 1387 lakes, across the western United States and Canada, to assess differences between reservoirs and lakes, as well as the influence of reservoir management on fish THg concentrations. Fish THg concentrations were 1.4-fold higher in reservoirs (0.13 ± 0.011 μg/g wet weight ± standard error) than lakes (0.09 ± 0.006), though this difference varied among ecoregions. Fish THg concentrations were 1.5- to 2.6-fold higher in reservoirs than lakes of the North American Deserts, Northern Forests, and Mediterranean California ecoregions, but did not differ between reservoirs and lakes in four other ecoregions. Fish THg concentrations peaked in three-year-old reservoirs then rapidly declined in 4–12 year old reservoirs. Water management was particularly important in influencing fish THg concentrations, which were up to 11-times higher in reservoirs with minimum water storage occurring in May, June, or July compared to reservoirs with minimum storage occurring in other months. Between-year changes in maximum water storage strongly influenced fish THg concentrations, but within-year fluctuations in water levels did not influence fish THg concentrations. Specifically, fish THg concentrations increased up to 3.2-fold over the range of between-year changes in maximum water storage in all ecoregions except Mediterranean California. These data highlight the role of reservoir creation and management in influencing fish

  14. Marine diet and tobacco exposure affects mercury concentrations in pregnant women (I from Baja California Sur, Mexico

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    Ramón Gaxiola-Robles

    2014-01-01

    Full Text Available Seafood provides essential polyunsaturated fatty acids (PUFA and other nutrients to pregnant women and their fetus(es while a diet rich in finfish can be a major pathway of monomethyl mercury (MeHg+ exposure. We measured total mercury concentration ([THg] in hair samples provided by 75 women in Baja California Sur (BCS to assess its relationship with age, parity, tobacco smoke exposure, and diet based on survey methodologies. Generalized linear models (GLM were used to explain the possible association of the different variables with [THg] in hair. Median [THg] in hair was 1.52 μg g−1, ranging from 0.12 to 24.19 μg g−1 and varied significantly by segment. Approximately 72% (54/75 of those evaluated exceed 1 μg g−1 [THg] and 8% (6/75 exceed 5 μg g−1 [THg] in hair. Although frequency of fish consumption contributed significantly to explaining hair [THg], fish consumption only explained 43% of [THg] in a GLM incorporating tobacco exposure and body mass index. This study establishes possible relationships among multiple potential sources of exposure and other factors related to [THg] in hair of women in the prenatal period. A more detailed examination of other sources of exposure and factors contributing to [THg] is warranted.

  15. Marine diet and tobacco exposure affects mercury concentrations in pregnant women (I) from Baja California Sur, Mexico

    Science.gov (United States)

    Gaxiola-Robles, Ramón; Bentzen, Rebecca; Zenteno-Savín, Tania; Labrada-Martagón, Vanessa; Castellini, J. Margaret; Celis, Alfredo; O’Hara, Todd; Celina Méndez-Rodríguez, Lía

    2017-01-01

    Seafood provides essential polyunsaturated fatty acids (PUFA) and other nutrients to pregnant women and their fetus(es) while a diet rich in finfish can be a major pathway of monomethyl mercury (MeHg+) exposure. We measured total mercury concentration ([THg]) in hair samples provided by 75 women in Baja California Sur (BCS) to assess its relationship with age, parity, tobacco smoke exposure, and diet based on survey methodologies. Generalized linear models (GLM) were used to explain the possible association of the different variables with [THg] in hair. Median [THg] in hair was 1.52 µgg−1, ranging from 0.12 to 24.19 µgg−1 and varied significantly by segment. Approximately 72% (54/75) of those evaluated exceed 1 µgg−1 [THg] and 8% (6/75) exceed 5 µgg−1 [THg] in hair. Although frequency of fish consumption contributed significantly to explaining hair [THg], fish consumption only explained 43% of [THg] in a GLM incorporating tobacco exposure and body mass index. This study establishes possible relationships among multiple potential sources of exposure and other factors related to [THg] in hair of women in the prenatal period. A more detailed examination of other sources of exposure and factors contributing to [THg] is warranted. PMID:28203532

  16. Mercury and Organic Matter Concentrations in Lake and Stream Sediments in relation to One Another and to Atmospheric Mercury Deposition and Climate Variations across Canada

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    Mina Nasr

    2017-01-01

    Full Text Available This article focuses on analyzing the Geological Survey of Canada (GSC data for total mercury concentrations (THg in lake and stream sediments. The objective was to quantify how sediment THg varies by (i sediment organic matter, determined by loss on ignition (LOI at 500∘C, (ii atmospheric Hg deposition (atm.Hgdep as derived from the Global/Regional Atmospheric Heavy Metals Model GRAHM2005, and (iii mean annual precipitation and mean monthly July and January temperatures (TJuly, TJan. Through regression analyses and averaging by National Topographic System tiles (NTS, 1:250,000 scale, it was found that 40, 70, and 80% of the sediment THg, LOI, and atm.Hgdep variations were, respectively, related to precipitation, TJuly, and TJan. In detail, lake sediment THg was related to atm.Hgdep and precipitation, while stream sediment THg was related to sediment LOI and TJuly. Plotting sediment THg versus sediment LOI revealed a curvilinear pattern, with highest Hg concentrations at intermediate LOI values. Analysing the resulting 10th and 90th log10THg percentiles within each 10% LOI class from 0 to 100% revealed that (i atm.Hgdep contributed to the organic component of sediment THg and (ii this was more pronounced for lakes than for streams.

  17. TOTAL MERCURY (HgT BIOACCUMULATION AND FISH FOOD HABITS IN NEGRO RIVER BASIN, AMAZON, BRAZIL

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    Jean Louchard Ferreira Soares

    2016-03-01

    Full Text Available In the Amazon, the fish is the main nutritional source for the riverine. Thus, fish have been commonly used in environmental monitoring work to be good biomonitors. This study analyzed the total mercury concentration (THg in fish of different species and feeding habits in order to investigate the existence of bioaccumulation in species in the basin of the Negro river and verify that the THg levels found are in accordance with the stipulated limit for consumption human. Sampling points were distributed in the basin of the Negro river during the period of high water. After the fisheries specimens were identified, measured and weighed. Then muscle samples were taken and subjected to acid digestion and analyzed by Cold Vapor Atomic Fluorescence Spectrophotometer - CVAFS. To research data was used analysis of variance and linear regression. A total of 264 specimens distributed into 10 species were analyzed, and the THg of the concentrations ranged from 0.030 for 1,670 mg.kg-1. The species Hoplias malabaricus, Serrasalmus rhombeus, Hemiodus immaculatus and Cichla temensis showed bioaccumulation. High concentrations of THg were found in carnivorous, piscivorous, planctívos and omnivores fish. No specimen showed mean concentrations of THg in violation to ANVISA, but this occurred in relation to FAO and WHO. keywords: Brazilian Amazon; biomonitoring; high waters; Hg.

  18. Total mercury concentrations in fish from Urrá reservoir (Sinú river, Colombia. Six years of monitoring

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    José Marrugo-Negrete

    2015-09-01

    Full Text Available Objective. The aim of this study was to monitor the total mercury (T-Hg concentrations in fish from the Urrá reservoir, after impoundment. Materials and methods. Five fish species at different trophic levels were sampled from 2004 to 2009 and analyzed by cold-vapor atomic absorption spectroscopy for T-Hg concentrations in muscle tissue. Water quality parameters were evaluated. Results. The highest (1.39±0.69 μg/g ww and lowest (0.15±0.02 μg/g ww T-Hg concentrations were detected in Hoplias malabaricus (piscivorous and Cyphocharax magdalenae (iliophagous/detritivorous respectively, whereas Leporinus muyscorum (omnivorous had an intermediate level (0.40±0.11 μg/g ww. The organic matter content in the water increased with time and depth, whereas dissolved oxygen and pH decreased. A covariance analysis (with fish length as a covariate shows a steady increase of T-Hg levels in all the studied species after impoundment. Conclusions. The T-Hg concentrations in the evaluated fish species, increased after impoundment. The water quality variables showed conditions favoring Hg methylation and its biomagnification, this last was evident in the fish food chain of the reservoir.

  19. Mercury concentrations in snapping turtles (Chelydra serpentina) correlate with environmental and landscape characteristics.

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    Turnquist, Madeline A; Driscoll, Charles T; Schulz, Kimberly L; Schlaepfer, Martin A

    2011-10-01

    Mercury (Hg) deposited onto the landscape can be transformed into methylmercury (MeHg), a neurotoxin that bioaccumulates up the aquatic food chain. Here, we report on Hg concentrations in snapping turtles (Chelydra serpentina) across New York State, USA. The objectives of this study were to: (1) test which landscape, water, and biometric characteristics correlate with total Hg (THg) concentrations in snapping turtles; and (2) determine whether soft tissue THg concentrations correlate with scute (shell) concentrations. Forty-eight turtles were sampled non-lethally from ten lakes and wetlands across New York to observe patterns under a range of ecosystem variables and water chemistry conditions. THg concentrations ranged from 0.041 to 1.50 μg/g and 0.47 to 7.43 μg/g wet weight of muscle tissue and shell, respectively. The vast majority of mercury (~94%) was in the MeHg form. Sixty-one percent of turtle muscle samples exceeded U.S. Environmental Protection Agency (U.S. EPA) consumption advisory limit of 0.3 μg Hg/g for fish. Muscle THg concentrations were significantly correlated with sulfate in water and the maximum elevation of the watershed. Shell THg concentrations were significantly correlated with the acid neutralizing capacity (ANC) of water, the maximum elevation of the watershed, the percent open water in the watershed, the lake to watershed size, and various forms of atmospheric Hg deposition. Thus, our results demonstrate that THg concentrations in snapping turtles are spatially variable, frequently exceed advisory limits, and are significantly correlated with several landscape and water characteristics.

  20. Assessing the influence of migration barriers and feeding ecology on total mercury concentrations in Dolly Varden (Salvelinus malma) from a glaciated and non-glaciated stream.

    Science.gov (United States)

    Cyr, Andrew; Sergeant, Christopher J; Lopez, Juan Andres; O'Hara, Todd

    2017-02-15

    Assimilation of mercury (Hg) into food webs is directly influenced by ecological factors such as local habitat characteristics, species feeding behavior, and movement patterns. Total Hg concentrations ([THg]) in biota from Subarctic latitudes are driven both by broad spatial processes such as long-range atmospheric transport and more local influences such as biovectors and geology. Thus, even relatively pristine protected lands such as national parks are experiencing Hg accumulation. We analyzed [THg] and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) in 104 Dolly Varden (Salvelinus malma) collected from two rivers in southeastern Alaska, upstream and downstream of apparent anadromous migration barriers in watersheds with and without glacial coverage. To assess the potential magnitude of marine-derived THg returning to freshwater, we analyzed [THg] in ten adult pink salmon from each study system. There were no differences in Dolly Varden mean [THg] between sites after the data were standardized for fork length, but unadjusted [THg] varied relative to fish size and δ(15)N values. While previous studies generally show that [THg] increases with higher δ(15)N values, we found that Dolly Varden below migration barriers and foraging on salmon eggs had the highest δ(15)N values among all sampled individuals, but the lowest [THg]. Dolly Varden residing below anadromous barriers had δ(13)C values consistent with marine influence. Since salmon eggs typically have low [Hg], our results suggest that abundant salmon populations and the dietary subsidy they provide may reduce the annual exposure to [Hg] in egg-eating stream fishes such as Dolly Varden. In addition to identifying a suitable species for freshwater Hg monitoring in southeastern Alaska, our study more broadly implies that river characteristics, location within a river, fish size, and feeding ecology are important factors influencing Hg accumulation.

  1. Long-term trends of surface-water mercury and methylmercury concentrations downstream of historic mining within the Carson River watershed

    Science.gov (United States)

    Morway, Eric; Thodal, Carl E.; Marvin-DiPasquale, Mark C.

    2017-01-01

    The Carson River is a vital water resource for local municipalities and migratory birds travelling the Pacific Flyway. Historic mining practices that used mercury (Hg) to extract gold from Comstock Lode ore has left much of the river system heavily contaminated with Hg, a practice that continues in many parts of the world today. Between 1998 and 2013, the United States Geological Survey (USGS) collected and analyzed Carson River water for Hg and methylmercury (MeHg) concentrations resulting in a sixteen year record of unfiltered total mercury (uf.THg), filtered (dissolved) Hg (f.THg), total methylmercury (uf.MeHg), filtered MeHg (f.MeHg), and particulate-bound THg (p.THg) and MeHg (p.MeHg) concentrations. This represents one of the longest continuous records of Hg speciation data for any riverine system, thereby providing a unique opportunity to evaluate long-term trends in concentrations and annual loads. During the period of analysis, uf.THg concentration and load trended downward at rates of −0.85% and −1.8% per year, respectively. Conversely, the f.THg concentration increased at a rate of 1.7% per year between 1998 and 2005, and 4.9% per year between 2005 and 2013. Trends in flow-normalized partition coefficients for both Hg and MeHg suggest a statistically significant shift from the particulate to the filtered phase. The upwardly accelerating f.THg concentration and observed shift from the solid phase to the aqueous phase among the pools of Hg and MeHg within the river water column signals an increased risk of deteriorating ecological conditions in the lower basin with respect to Hg contamination. More broadly, the 16-year trend analysis, completed 140 years after the commencement of major Hg releases to the Carson River, provides a poignant example of the ongoing legacy left behind by gold and silver mining techniques that relied on Hg amalgamation, and a cautionary tale for regions still pursuing the practice in other countries.

  2. Relationship between self-reported fish and shellfish consumption, carbon and nitrogen stable isotope values and total mercury concentrations in pregnant women (II from Baja California Sur, Mexico

    Directory of Open Access Journals (Sweden)

    Rebecca Bentzen

    2014-01-01

    Full Text Available Seafood is a valuable source of nutrients important for fetal development. However, seafood consumption is the main route of exposure to monomethyl mercury (MeHg+ for humans. MeHg+ is highly bioavailable and potentially adversely affects fetal neurodevelopment. MeHg+ exposure from fish consumption varies significantly by age and trophic level of fish consumed as well as the frequency and amount of fish consumed. This study investigates total Hg concentrations ([THg] in hair segments of pregnant Mexican women in relation to (1 self-reported frequency of fish and shellfish consumption, (2 maternal trophic level and marine diet contributions, determined using hair carbon (C and nitrogen (N stable isotopes, and (3 relates [THg] to various hair advisory thresholds. We also examined whether variation in C and N isotope values is explained by self-reported frequency of fish and shellfish consumption. A significant proportion of hair samples had [THg] higher than suggested agency thresholds and, for women within the range of the various advisory thresholds (1–20 μg g−1, the specific statistic used and threshold applied are important considerations for assessing and communicating risk. Individuals enriched in 15N (δ15N values had higher [THg] as did individuals that reported consuming fish and shellfish more frequently, suggesting that variation in [THg] can be explained by both consumer reported diet and diet as determined by C and N stable isotope assessment. However, at higher reported fish consumption levels the trophic level is maintained while [THg] is paradoxically lower. This suggests that THg exposure and assimilation are more complicated in higher fish frequency consumption categories. [THg] is more variable at the higher concentrations, possibly indicating some exposure to non-dietary Hg, heritable variations affecting Hg toxicodynamics, and BMI and tobacco exposure factors as outlined in our companion paper.

  3. Manifold and method of batch measurement of Hg-196 concentration using a mass spectrometer

    Science.gov (United States)

    Grossman, M.W.; Evans, R.

    1991-11-26

    A sample manifold and method of its use has been developed so that milligram quantities of mercury can be analyzed mass spectroscopically to determine the [sup 196]Hg concentration to less than 0.02 atomic percent. Using natural mercury as a standard, accuracy of [+-]0.002 atomic percent can be obtained. The mass spectrometer preferably used is a commercially available GC/MS manufactured by Hewlett Packard. A novel sample manifold is contained within an oven allowing flow rate control of Hg into the MS. Another part of the manifold connects to an auxiliary pumping system which facilitates rapid clean up of residual Hg in the manifold. Sample cycle time is about 1 hour. 8 figures.

  4. Analysis of THG modes for femtosecond laser pulse

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Sidorov, Pavel S.

    2017-05-01

    THG is used nowadays in many practical applications such as a substance diagnostics, and biological objects imaging, and etc. With developing of new materials and technology (for example, photonic crystal) an attention to THG process analysis grow. Therefore, THG features understanding are a modern problem. Early we have developed new analytical approach based on using the problem invariant for analytical solution construction of the THG process. It should be stressed that we did not use a basic wave non-depletion approximation. Nevertheless, a long pulse duration approximation and plane wave approximation has applied. The analytical solution demonstrates, in particular, an optical bistability property (and may other regimes of frequency tripling) for the third harmonic generation process. But, obviously, this approach does not reflect an influence of a medium dispersion on the frequency tripling. Therefore, in this paper we analyze THG efficiency of a femtosecond laser pulse taking into account a second order dispersion affect as well as self- and crossmodulation of the interacting waves affect on the frequency conversion process. Analysis is made using a computer simulation on the base of Schrödinger equations describing the process under consideration.

  5. Relationships of mercury concentrations across tissue types, muscle regions and fins for two shark species

    KAUST Repository

    O'Bryhim, Jason R.

    2017-01-31

    Mercury (Hg) exposure poses a threat to both fish and human health. Sharks are known to bioaccumulate Hg, however, little is known regarding how Hg is distributed between different tissue groups (e.g. muscle regions, organs). Here we evaluated total mercury (THg) concentrations from eight muscle regions, four fins (first dorsal, left and right pectorals, caudal-from both the inner core and trailing margin of each fin), and five internal organs (liver, kidney, spleen, heart, epigonal organ) from two different shark species, bonnethead (Sphyrna tiburo) and silky shark (Carcharhinus falciformis) to determine the relationships of THg concentrations between and within tissue groups. Total Hg concentrations were highest in the eight muscle regions with no significant differences in THg concentrations between the different muscle regions and muscle types (red and white). Results from tissue collected from any muscle region would be representative of all muscle sample locations. Total Hg concentrations were lowest in samples taken from the fin inner core of the first dorsal, pectoral, and caudal (lower lobe) fins. Mercury concentrations for samples taken from the trailing margin of the dorsal, pectoral, and caudal fins (upper and lower lobe) were also not significantly different from each other for both species. Significant relationships were found between THg concentrations in dorsal axial muscle tissue and the fin inner core, liver, kidney, spleen and heart for both species as well as the THg concentrations between the dorsal fin trailing margin and the heart for the silky shark and all other sampled tissue types for the bonnethead shark. Our results suggest that biopsy sampling of dorsal muscle can provide data that can effectively estimate THg concentrations in specific organs without using more invasive, or lethal methods.

  6. Relationships of mercury concentrations across tissue types, muscle regions and fins for two shark species.

    Science.gov (United States)

    O'Bryhim, Jason R; Adams, Douglas H; Spaet, Julia L Y; Mills, Gary; Lance, Stacey L

    2017-04-01

    Mercury (Hg) exposure poses a threat to both fish and human health. Sharks are known to bioaccumulate Hg, however, little is known regarding how Hg is distributed between different tissue groups (e.g. muscle regions, organs). Here we evaluated total mercury (THg) concentrations from eight muscle regions, four fins (first dorsal, left and right pectorals, caudal-from both the inner core and trailing margin of each fin), and five internal organs (liver, kidney, spleen, heart, epigonal organ) from two different shark species, bonnethead (Sphyrna tiburo) and silky shark (Carcharhinus falciformis) to determine the relationships of THg concentrations between and within tissue groups. Total Hg concentrations were highest in the eight muscle regions with no significant differences in THg concentrations between the different muscle regions and muscle types (red and white). Results from tissue collected from any muscle region would be representative of all muscle sample locations. Total Hg concentrations were lowest in samples taken from the fin inner core of the first dorsal, pectoral, and caudal (lower lobe) fins. Mercury concentrations for samples taken from the trailing margin of the dorsal, pectoral, and caudal fins (upper and lower lobe) were also not significantly different from each other for both species. Significant relationships were found between THg concentrations in dorsal axial muscle tissue and the fin inner core, liver, kidney, spleen and heart for both species as well as the THg concentrations between the dorsal fin trailing margin and the heart for the silky shark and all other sampled tissue types for the bonnethead shark. Our results suggest that biopsy sampling of dorsal muscle can provide data that can effectively estimate THg concentrations in specific organs without using more invasive, or lethal methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Spatial Distribution of Mercury (Hg Concentration in Agricultural Soil and Its Risk Assessment on Food Safety in China

    Directory of Open Access Journals (Sweden)

    Shanqian Wang

    2016-08-01

    Full Text Available Soil mercury (Hg pollution in some areas of China is a serious problem and has aroused a lot of attention on a local scale. However, there are few studies on Hg pollution on a national scale. This study collected 444 published papers during 2005–2015 on Hg concentrations in agricultural soil throughout China, under seven land uses, namely: dry land, paddy field, vegetable field, tea garden, orchard, traditional Chinese medicine field and tobacco field, to assess the spatial distribution of Hg concentration and evaluate its influence on food safety. The averaged Hg concentration (0.108 mg/kg was higher than its background (0.065 mg/kg, but much lower than the guidelines (GB15618-1995 II for crop production. The spatial distribution of Hg throughout China showed great variability, with some hotspots due to Hg related mining and smelting activities. According to the Environment Quality Standard for soil in China (GB15618-1995 II, 4.2% of agricultural soil should be abandoned due to Hg pollution, and 2.0% faced a high risk of Hg pollution.

  8. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

    Science.gov (United States)

    Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

    2016-01-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  9. Analysis of carrier concentration, lifetime, and electron mobility on p-type HgCdTe

    Science.gov (United States)

    Yoo, Sang Dong; Kwack, Kae Dal

    1998-03-01

    Minority carrier transport characteristics of vacancy-doped p-type HgCdTe such as carrier concentration, lifetime, and mobility are investigated. In the calculation of the carrier concentration two acceptor levels—a donor level and a trap level—were taken into account. The acceptor levels have been described by two models—two independent singly ionized levels and a divalent level with two ionization energies. When each model was examined by calculating electron mobility as a function of temperature, the latter was found to be more accurate. Electron mobility as a function of majority carrier concentration was also presented for both n-type and p-type HgCdTe with 0.225 Cd mole fraction. Steady state electron lifetime was computed assuming the acceptor levels and the trap level would act as Schokley-Read-Hall type recombination centers. The calculated results using the divalent acceptor model were in good agreement with the experimental data.

  10. Selective exploitation of large pike Esox lucius-Effects on mercury concentrations in fish populations

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Chhatra Mani [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: chhatra.sharma@gmail.com; Borgstrom, Reidar [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: reidar.borgstrom@umb.no; Huitfeldt, Jorgen Sinkaberg [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: jhu@wang.no; Rosseland, Bjorn Olav [Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As (Norway)], E-mail: bjorn.rosseland@umb.no

    2008-07-25

    The present study outlines two main trends of mercury transfer patterns through the fish community: 1) the Hg concentrations increase with increase in the trophic level, with top predators having the highest concentrations, and 2) a fast growth rate may dilute the concentrations of Hg in fish muscle tissue (growth biodilution). In 2004, an extensive reduction in number of large pike (Esox lucius L.), was initiated by selective gillnet fishing in Lake Arungen, Norway, in order to increase the pike recruitment due to an expected reduction in cannibalism. In this connection, total mercury (THg) concentrations in the fish community were studied both before (2003) and after (2005) the removal of large pike. The {delta}{sup 15}N signatures and stomach content analyses indicated that pike and perch (Perca fluviatilis L.) occupied the highest trophic position, while roach (Rutilus rutilus (L.)) was at the lower level, and rudd (Scardinius erythrophthalmus L.) at the lowest. The piscivores, pike and perch, had the highest concentrations of THg. The biomagnification rate of THg through the food web in the fish community was 0.163 ( per mille{delta}{sup 15}N), with the highest uptake rate (0.232) in perch. A significant decrease in THg concentrations was found in all fish species in 2005 compared to 2003. Removal of the top predators in an Hg contaminated lake might thus be an important management tool for reducing Hg levels in fish, thereby reducing health risk to humans.

  11. Selective exploitation of large pike Esox lucius--effects on mercury concentrations in fish populations.

    Science.gov (United States)

    Sharma, Chhatra Mani; Borgstrøm, Reidar; Huitfeldt, Jørgen Sinkaberg; Rosseland, Bjørn Olav

    2008-07-25

    The present study outlines two main trends of mercury transfer patterns through the fish community: 1) the Hg concentrations increase with increase in the trophic level, with top predators having the highest concentrations, and 2) a fast growth rate may dilute the concentrations of Hg in fish muscle tissue (growth biodilution). In 2004, an extensive reduction in number of large pike (Esox lucius L.), was initiated by selective gillnet fishing in Lake Arungen, Norway, in order to increase the pike recruitment due to an expected reduction in cannibalism. In this connection, total mercury (THg) concentrations in the fish community were studied both before (2003) and after (2005) the removal of large pike. The delta(15)N signatures and stomach content analyses indicated that pike and perch (Perca fluviatilis L.) occupied the highest trophic position, while roach (Rutilus rutilus (L.)) was at the lower level, and rudd (Scardinius erythrophthalmus L.) at the lowest. The piscivores, pike and perch, had the highest concentrations of THg. The biomagnification rate of THg through the food web in the fish community was 0.163 (per thousand delta(15)N), with the highest uptake rate (0.232) in perch. A significant decrease in THg concentrations was found in all fish species in 2005 compared to 2003. Removal of the top predators in an Hg contaminated lake might thus be an important management tool for reducing Hg levels in fish, thereby reducing health risk to humans.

  12. Mercury concentrations in eggs of red-winged blackbirds and tree swallows breeding in Voyageurs National Park, Minnesota

    Science.gov (United States)

    Robin W. Tyser,; Kristofer R. Rolfhus,; James G. Wiener,; Steve K. Windels,; Custer, Thomas W.; Dummer, Paul

    2016-01-01

    Most investigations of the environmental effects of mercury (Hg) have focused on aquatic food webs that include piscivorous fish or wildlife. However, recent investigations have shown that other species, including passerine songbirds, may also be at risk from exposure to methylmercury (MeHg). We quantified Hg concentrations in eggs of two species of songbirds, red-winged blackbirds (Agelaius phoeniceus) and tree swallows (Tachycineta bicolor), nesting in Voyageurs National Park, Minnesota, USA. Geometric mean concentrations of total Hg (THg) were lower in red-winged blackbird eggs [218 and 107 ng/g dry weight (dw) for 2012 and 2013, respectively] than in tree swallow eggs (228 and 300 ng/g dw for 2012 and 2013, respectively), presumably reflecting differences in the trophic positions of these two species. Concentrations of MeHg averaged 98.4 % of THg in red-winged blackbird eggs. Levels of THg observed in this study were well below critical toxicological benchmarks commonly applied to eggs of avian species, suggesting these breeding populations were not adversely affected by exposure to MeHg. In red-winged blackbirds, concentrations of THg in eggs collected in 2012 were twice those in eggs collected in 2013. Hg levels in eggs of both species increased with date of clutch initiation. In red-winged blackbirds, for example, temporal patterns showed that a 3-week delay in clutch initiation increased egg THg by 60 %. These observations indicate that in ovo exposure of wetland birds to MeHg can vary significantly within nesting season as well as between years.

  13. Effects of age, colony, and sex on mercury concentrations in California sea lions

    Science.gov (United States)

    McHuron, Elizibeth A; Peterson, Sarah H.; Ackerman, Josh; Melin, Sharon R.; Harris, Jeffrey D.; Costa, Daniel P.

    2016-01-01

    We measured total mercury (THg) concentrations in California sea lions (Zalophus californianus) and examined how concentrations varied with age class, colony, and sex. Because Hg exposure is primarily via diet, we used nitrogen (δ 15N) and carbon (δ 13C) stable isotopes to determine if intraspecific differences in THg concentrations could be explained by feeding ecology. Blood and hair were collected from 21 adult females and 57 juveniles from three colonies in central and southern California (San Nicolas, San Miguel, and Año Nuevo Islands). Total Hg concentrations ranged from 0.01 to 0.31 μg g−1 wet weight (ww) in blood and 0.74 to 21.00 μg g−1 dry weight (dw) in hair. Adult females had greater mean THg concentrations than juveniles in blood (0.15 vs. 0.03 μg−1 ww) and hair (10.10 vs. 3.25 μg−1 dw). Age class differences in THg concentrations did not appear to be driven by trophic level or habitat type because there were no differences in δ 15N or δ 13C values between adults and juveniles. Total Hg concentrations in adult females were 54 % (blood) and 24 % (hair) greater in females from San Miguel than females from San Nicolas Island, which may have been because sea lions from the two islands foraged in different areas. For juveniles, we detected some differences in THg concentrations with colony and sex, although these were likely due to sampling effects and not ecological differences. Overall, THg concentrations in California sea lions were within the range documented for other marine mammals and were generally below toxicity benchmarks for fish-eating wildlife.

  14. Changes in Sport Fish Mercury Concentrations from Food Web Shifts Suggest Partial Decoupling from Atmospheric Deposition in Two Colorado Reservoirs.

    Science.gov (United States)

    Wolff, Brian A; Johnson, Brett M; Lepak, Jesse M

    2017-02-01

    Partial decoupling of mercury (Hg) loading and observed Hg concentrations ([Hg]) in biotic and abiotic samples has been documented in aquatic systems. We studied two Colorado reservoirs to test whether shifts in prey for sport fish would lead to changes in [Hg] independent of external atmospheric Hg deposition. We compared sport fish total mercury concentrations ([T-Hg]) and macroinvertebrate (chironomids and crayfish) methylmercury concentrations ([MeHg]) before and after food web shifts occurred in both reservoirs. We also monitored wet atmospheric Hg deposition and sediment [T-Hg] and [MeHg] at each reservoir. We found rapid shifts in Hg bioaccumulation in each reservoir's sport fish, and these changes could not be attributed to atmospheric Hg deposition. Our study shows that trends in atmospheric deposition, environmental samples (e.g., sediments), and samples of species at the low trophic levels (e.g., chironomids and crayfish) may not accurately reflect conditions that result in fish consumption advisories for high trophic level sport fish. We suggest that in the short-term, monitoring fish [Hg] is necessary to adequately protect human health because natural and anthropogenic perturbations to aquatic food-webs that affect [Hg] in sport fish will continue regardless of trends in atmospheric deposition.

  15. Contrasting Food Web Factor and Body Size Relationships with Hg and Se Concentrations in Marine Biota

    Science.gov (United States)

    Karimi, Roxanne; Frisk, Michael; Fisher, Nicholas S.

    2013-01-01

    Marine fish and shellfish are primary sources of human exposure to mercury, a potentially toxic metal, and selenium, an essential element that may protect against mercury bioaccumulation and toxicity. Yet we lack a thorough understanding of Hg and Se patterns in common marine taxa, particularly those that are commercially important, and how food web and body size factors differ in their influence on Hg and Se patterns. We compared Hg and Se content among marine fish and invertebrate taxa collected from Long Island, NY, and examined associations between Hg, Se, body length, trophic level (measured by δ15N) and degree of pelagic feeding (measured by δ13C). Finfish, particularly shark, had high Hg content whereas bivalves generally had high Se content. Both taxonomic differences and variability were larger for Hg than Se, and Hg content explained most of the variation in Hg:Se molar ratios among taxa. Finally, Hg was more strongly associated with length and trophic level across taxa than Se, consistent with a greater degree of Hg bioaccumulation in the body over time, and biomagnification through the food web, respectively. Overall, our findings indicate distinct taxonomic and ecological Hg and Se patterns in commercially important marine biota, and these patterns have nutritional and toxicological implications for seafood-consuming wildlife and humans. PMID:24019976

  16. Mercury and selenium concentrations in the internal organs of toothed whales and dolphins marketed for human consumption in Japan.

    Science.gov (United States)

    Endo, Tetsuya; Haraguchi, Koichi; Sakata, Masakatsu

    2002-12-02

    Small cetaceans (toothed whales odontoceti and dolphins delphinidae) have been traditionally hunted along the coast of Japan and fresh red meat and blubber, as well as boiled internal organs such as liver, kidney, lung and small intestine, are still being sold for human consumption. We surveyed mercury contamination in boiled liver, kidney and lung products marketed in Japan between 1999-2001. The average +/- S.D. of total mercury (T-Hg) was 370 +/- 525 (range: 7.60 approximately 1980, n = 26) microg/g in liver, 40.5 +/- 48.5 (7.30-95.1, n = 15) microg/g in kidney and 42.8 +/- 43.8 (2.10-79.6, n = 23) microg/g in lung. A high correlation was observed between T-Hg and selenium (Se) concentrations in these organs, supporting the formation of a Hg-Se complex. The formation of a Hg-Se complex probably contribute to the detoxification of Hg for cetaceans and allows a very large accumulation of Hg in livers. The provisional permitted level of T-Hg in marine foods set by the Japanese Ministry of Health and Welfare is 0.4 microg/ g, and the provisional permitted weekly intake (PTWI) set by WHO is 5 microg/kg bw/week. The maximal T-Hg detected in boiled liver (1,980 microg/g) exceeds the permitted level by approximately 5,000 times and the consumption of only 0.15 g of liver exceeds the PTWI of 60 kg of body weight of the consumer, suggesting the possibility of an acute intoxication by T-Hg even after a single consumption of the product.

  17. Growing rice aerobically markedly decreases mercury accumulation by reducing both Hg bioavailability and the production of MeHg.

    Science.gov (United States)

    Wang, Xun; Ye, Zhihong; Li, Bing; Huang, Linan; Meng, Mei; Shi, Jianbo; Jiang, Guibin

    2014-01-01

    Rice consumption represents a major route of mercury (Hg) and methylmercury (MeHg) exposure for those living in certain areas of inland China. In this study we investigated the effects of water management on bioavailable Hg, MeHg, and sulfate-reducing bacteria (SRB, abundance and community composition) in rhizosphere soil, and total Hg (THg) and MeHg in rice plants grown under glasshouse and paddy field conditions. Aerobic conditions greatly decreased the amount of THg and MeHg taken up by rice plants and affected their distribution in different plant tissues. There were positive correlations between bioavailable Hg and THg in brown rice and roots and between numbers of SRB and MeHg in brown rice, roots, and rhizosphere soil. Furthermore, the community composition of SRB was dramatically influenced by the water management regimes. Our results demonstrate that the greatly reduced bioavailability of Hg and production of MeHg are due to decreased SRB numbers and proportion of Hg methylators in the rhizosphere under aerobic conditions. These are the main reasons for the reduced Hg and MeHg accumulation in aerobically grown rice. Water management is indicated as an effective measure that can be used to reduce Hg and MeHg uptake by rice plants from Hg-contaminated paddy fields.

  18. Concentration of Cd, Pb, Hg, and Se in Different Parts of Human Breast Cancer Tissues

    Directory of Open Access Journals (Sweden)

    Mehrnoosh Mohammadi

    2014-01-01

    Full Text Available Breast cancer is the major cause of cancer morbidity and mortality between women in the world. Metals involved in environmental toxicology are closely related to tumor growth and cancer. On the other hand, some metals such as selenium have anticarcinogenic properties. The aim of this study is to determine the concentration of cadmium, lead, mercury, and selenium in separated parts of tegmen, tumor, tumor adiposity, and tegmen adiposity of 14 breast cancer tissues which have been analyzed by graphite furnace atomic absorption (AA-670 and ICP-OES (ULTIMA 2CE. Our results show that Se and Hg have maximum and minimum concentration, respectively. Statistical analysis reveals no significant differences between metal accumulations in different parts of cancer tissues (P>0.05 and this observation might be due to the close relation of separated parts of fatty breast organ. Thus, we could conclude that a high level of these heavy metals is accumulated in Iranian cancerous breasts and their presence can be one of the reasons of cancer appearance.

  19. A Highly Sensitive and Selective Competition Assay for the Detection of Cysteine Using Mercury-Specific DNA, Hg2+ and Sybr Green I

    Directory of Open Access Journals (Sweden)

    Gang Liu

    2011-10-01

    Full Text Available We here report a rapid, sensitive, selective and label-free fluorescence detection method for cysteine (Cys. The conformation of mercury-specific DNA (MSD changes from a random coil form to a hairpin structure in the presence of Hg2+ due to the formation of a thymine-Hg2+-thymine (T-Hg2+-T complex. Cys can selectively coordinate with Hg2+ and extract it from the thymine-Hg2+-thymine complex. The hairpin structure dehybridizes and the fluorescence intensity of Sybr Green I (SG decreases upon addition of Cys because SG efficiently discriminates mercury-specific DNA and mercury-specific DNA/Hg2+ complex. The detection can be finished within 5 min with high sensitivity and selectivity. In addition, we can obtain variable dynamic ranges for Cys by changing the concentration of MSD/Hg2+.

  20. A highly sensitive and selective competition assay for the detection of cysteine using mercury-specific DNA, Hg and Sybr Green I.

    Science.gov (United States)

    Xu, Hui; Gao, Shuli; Liu, Quanwen; Pan, Dun; Wang, Lihua; Ren, Shuzhen; Ding, Min; Chen, Jingwen; Liu, Gang

    2011-01-01

    We here report a rapid, sensitive, selective and label-free fluorescence detection method for cysteine (Cys). The conformation of mercury-specific DNA (MSD) changes from a random coil form to a hairpin structure in the presence of Hg2+ due to the formation of a thymine-Hg2+ -thymine (T-Hg2+ -T) complex. Cys can selectively coordinate with Hg2+ and extract it from the thymine-Hg2+ -thymine complex. The hairpin structure dehybridizes and the fluorescence intensity of Sybr Green I (SG) decreases upon addition of Cys because SG efficiently discriminates mercury-specific DNA and mercury-specific DNA/Hg2+ complex. The detection can be finished within 5 min with high sensitivity and selectivity. In addition, we can obtain variable dynamic ranges for Cys by changing the concentration of MSD/Hg2+.

  1. Electrochemical DNA probe for Hg(2+) detection based on a triple-helix DNA and Multistage Signal Amplification Strategy.

    Science.gov (United States)

    Wang, Huan; Zhang, Yihe; Ma, Hongmin; Ren, Xiang; Wang, Yaoguang; Zhang, Yong; Wei, Qin

    2016-12-15

    In this work, an ultrasensitive electrochemical sensor was developed for detection of Hg(2+). Gold nanoparticles decorated bovine serum albumin reduction of graphene oxide (AuNP-BSA-rGO) were used as subsurface material for the immobilization of triple-helix DNA. The triple-helix DNA containing a thiol labelled single-stranded DNA (sDNA) and a thymine-rich DNA (T-rich DNA), which could be unwinded in the present of Hg(2+) to form more stable thymine-Hg(2+)-thymine (T-Hg(2+)-T) complex. T-Hg(2+)-T complex was then removed and the sDNA was left on the electrode. At this time, gold nanoparticle carrying thiol labelled cytosine-rich complementary DNA (cDNA-AuNP) could bind with the free sDNA. Meanwhile, the other free cDNA on AuNP could bind with each other in the present of Ag(+) to form the stable cytosine-Ag(+)-cytosine (C-Ag(+)-C) complex and circle amplification. Plenty of C-Ag(+)-C could form silver nanoclusters by electrochemical reduction and the striping signal of Ag could be measured for purpose of the final electrochemical detection of Hg(2+). This sensor could detect Hg(2+) over a wide concentration range from 0.1 to 130nM with a detection limit of 0.03nM.

  2. A SERS biosensor with magnetic substrate CoFe2O4@Ag for sensitive detection of Hg2+

    Science.gov (United States)

    Yang, Xia; He, Yi; Wang, Xueling; Yuan, Ruo

    2017-09-01

    Mercuric ion (Hg2+) is one toxic metal ion existed in aquatic ecosystems which would seriously damage human central nervous system and other organs. So developing an approach to sensitively detect Hg2+ in our living environment is urgent and important. In this work, a novel surface enhancement Raman spectrum(SERS) sensor is fabricated for high selective and ultrasensitive detection of Hg2+ in aqueous solution, based on a stable thymine-Hg2+-thymine (T-Hg2+-T) structure and the π-π interaction between single-stranded DNA (ssDNA) and single walled carbon nanotubes (SWCNTs). Herein, SWCNTs act as Raman labels to produce characteristic Raman peaks which can be a beacon to quantitative detect Hg2+. In the presence of Hg2+, the ssDNA can capture Hg2+ forming T-Hg2+-T structure, which makes SWCNTs leave the hot spots of the SERS-based biosensor. With this design, the Raman intensity of SWCNTs decreased with the increasing concentration of Hg2+. At the same time, CoFe2O4@Ag as active SERS substrates can effectively enhance sensitivity and uniformity of the biosensor through aggregation by magnet. Under optimal conditions, this proposed biosensor can detect Hg2+ at a range from 1 pM to 100 nM with a detection limit of 0.84 pM. With the advantages of good sensitivity, selectivity, simplicity and rapidity, the biosensor is potentially suitable for monitoring of Hg2+ in environmental applications.

  3. Identifying the sources and processes of mercury in subtropical estuarine and ocean sediments using Hg isotopic composition.

    Science.gov (United States)

    Yin, Runsheng; Feng, Xinbin; Chen, Baowei; Zhang, Junjun; Wang, Wenxiong; Li, Xiangdong

    2015-02-03

    The concentrations and isotopic compositions of mercury (Hg) in surface sediments of the Pearl River Estuary (PRE) and the South China Sea (SCS) were analyzed. The data revealed significant differences between the total Hg (THg) in fine-grained sediments collected from the PRE (8-251 μg kg(-1)) and those collected from the SCS (12-83 μg kg(-1)). Large spatial variations in Hg isotopic compositions were observed in the SCS (δ(202)Hg, from -2.82 to -2.10‰; Δ(199)Hg, from +0.21 to +0.45‰) and PRE (δ(202)Hg, from -2.80 to -0.68‰; Δ(199)Hg, from -0.15 to +0.16‰). The large positive Δ(199)Hg in the SCS indicated that a fraction of Hg has undergone Hg(2+) photoreduction processes prior to incorporation into the sediments. The relatively negative Δ(199)Hg values in the PRE indicated that photoreduction of Hg is not the primary route for the removal of Hg from the water column. The riverine input of fine particles played an important role in transporting Hg to the PRE sediments. In the deep ocean bed of the SCS, source-related signatures of Hg isotopes may have been altered by natural geochemical processes (e.g., Hg(2+) photoreduction and preferential adsorption processes). Using Hg isotope compositions, we estimate that river deliveries of Hg from industrial and urban sources and natural soils could be the main inputs of Hg to the PRE. However, the use of Hg isotopes as tracers in source attribution could be limited because of the isotope fractionation by natural processes in the SCS.

  4. Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus)

    Energy Technology Data Exchange (ETDEWEB)

    McGrew, Ashley K. [Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1619 (United States); O' Hara, Todd M. [Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1619 (United States); Wildlife Toxicology Laboratory, Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Stricker, Craig A. [U. S. Geological Survey, Fort Collins Science Center, Denver, CO 80225 (United States); Margaret Castellini, J. [Wildlife Toxicology Laboratory, Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Beckmen, Kimberlee B. [Alaska Department of Fish & Game, Fairbanks, AK (United States); Salman, Mo D. [Animal Population Health Institute, Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523-1644 (United States); Ballweber, Lora R. [Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1619 (United States)

    2015-12-01

    Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within the host. [THg] and stable isotopes (C and N) were determined for helminths, host tissues, and lumen contents from 88 wolves. Sixty-three wolves contained grossly visible helminths (71.5%). The prevalence of taeniids and ascarids was 63.6% (56/88) and 20.5% (18/88), respectively. Nine of these 63 wolves contained both taeniids and ascarids (14.3%). All ascarids were determined to be Toxascaris leonina. Taenia species present included T. krabbei and T. hydatigena. Within the GI tract, [THg] in the lumen contents of the proximal small intestine were significantly lower than in the distal small intestine. There was a significant positive association between hepatic and taeniid [THg]. Bioaccumulation factors (BAF) ranged from < 1 to 22.9 in taeniids, and 1.1 to 12.3 in T. leonina. Taeniid and ascarid BAF were significantly higher than 1, suggesting that both groups are capable of THg accumulation in their wolf host. δ{sup 13}C in taeniids was significantly lower than in host liver and skeletal muscle. [THg] in helminths and host tissues, in conjunction with stable isotope (C and N) values, provides insight into food-web dynamics of the host GI tract, and aids in elucidating ecotoxicoparasitologic relationships. Variation of [THg] throughout the GI tract, and between parasitic groups, underscores the need to further evaluate the effect(s) of feeding niche, and the nutritional needs of parasites, as they relate to toxicant exposure and distribution within the host. - Highlights: • [THg] and stable isotopes together provide insight on host-parasite-Hg interactions. • A

  5. Screening of native plant species for phytoremediation potential at a Hg-contaminated mining site.

    Science.gov (United States)

    Marrugo-Negrete, José; Marrugo-Madrid, Siday; Pinedo-Hernández, José; Durango-Hernández, José; Díez, Sergi

    2016-01-15

    Artisanal and small-scale gold mining (ASGM) is the largest sector of demand for mercury (Hg), and therefore, one of the major sources of Hg pollution in the environment. This study was conducted in the Alacrán gold-mining site, one of the most important ASGM sites in Colombia, to identify native plant species growing in Hg-contaminated soils used for agricultural purposes, and to assess their potential as phytoremediation systems. Twenty-four native plant species were identified and analysed for total Hg (THg) in different tissues (roots, stems, and leaves) and in underlying soils. Accumulation factors (AF) in the shoots, translocation (TF) from roots to shoots, and bioconcentration (BCF) from soil-to-roots were determined. Different tissues from all plant species were classified in the order of decreasing accumulation of Hg as follows: roots > leaves > stems. THg concentrations in soil ranged from 230 to 6320 ng g(-1). TF values varied from 0.33 to 1.73, with high values in the lower Hg-contaminated soils. No correlation was found between soils with low concentrations of Hg and plant leaves, indicating that TF is not a very accurate indicator, since most of the Hg input to leaves at ASGM sites comes from the atmosphere. On the other hand, the BCF ranged from 0.28 to 0.99, with Jatropha curcas showing the highest value. Despite their low biomass production, several herbs and sub-shrubs are suitable for phytoremediation application in the field, due to their fast growth and high AF values in large and easily harvestable plant parts. Among these species, herbs such as Piper marginathum and Stecherus bifidus, and the sub-shrubs J. curcas and Capsicum annuum are promising native plants with the potential to be used in the phytoremediation of soils in tropical areas that are impacted by mining.

  6. Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Lescord, Gretchen L., E-mail: glescord@gmail.com [University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6 (Canada); Kidd, Karen A. [University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6 (Canada); Kirk, Jane L. [Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Rd, Burlington, ON L7S 1A1 (Canada); O' Driscoll, Nelson J. [Acadia University, 15 University Ave, Wolfville, NS B4P 2R6 (Canada); Wang, Xiaowa; Muir, Derek C.G. [Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Rd, Burlington, ON L7S 1A1 (Canada)

    2015-03-15

    In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ{sup 13}C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ{sup 15}N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota. - Highlights: • Mercury (Hg) in Arctic char and invertebrates

  7. Genetic Polymorphisms in Glutathione (GSH- Related Genes Affect the Plasmatic Hg/Whole Blood Hg Partitioning and the Distribution between Inorganic and Methylmercury Levels in Plasma Collected from a Fish-Eating Population

    Directory of Open Access Journals (Sweden)

    Andréia Ávila Soares de Oliveira

    2014-01-01

    Full Text Available This study aims to evaluate the effects of polymorphisms in glutathione (GSH- related genes (GSTM1, GSTT1, GSTP1, GCLM, and GCLC in the distribution of Hg in the blood compartments in humans exposed to methylmercury (MeHg. Subjects (n=88, exposed to MeHg from fish consumption, were enrolled in the study. Hg species in the plasma compartment were determined by LC-ICP-MS, whereas genotyping was performed by PCR assays. Mean total Hg levels in plasma (THgP and whole blood (THgB were 10±4.2 and 37±21, whereas mean evels of plasmatic MeHg (MeHgP, inorganic Hg (IHgP, and HgP/HgB were 4.3±2.9, 5.8±2.3 µg/L, and 0.33±0.15, respectively. GSTM1 and GCLC polymorphisms influence THgP and MeHgP (multivariate analyses, P<0.050. Null homozygotes for GSTM1 showed higher THgP and MeHgP levels compared to subjects with GSTM1 (THgP β=0.22, P=0.035; MeHgP β=0.30, P=0.050 and persons carrying at least one T allele for GCLC had significant higher MeHgP (β=0.59, P=0.046. Also, polymorphic GCLM subjects had lower THgP/THgB than those with the nonvariant genotype. Taken together, data of this study suggest that GSH-related polymorphisms may change the metabolism of MeHg by modifying the distribution of mercury species iin plasma compartment and the HgP/HgB partitioning.

  8. Mercury concentrations in Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida: Patterns of spatial and temporal distribution.

    Science.gov (United States)

    Schaefer, Adam M; Titcomb, Elizabeth Murdoch; Fair, Patricia A; Stavros, Hui-Chen W; Mazzoil, Marilyn; Bossart, Gregory D; Reif, John S

    2015-08-15

    Bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, FL (IRL) have tissue mercury concentrations among the highest reported worldwide. Analysis of total mercury (THg) concentrations in blood collected between 2003 and 2012 showed a significant linear decrease over time (p=0.04). Significant differences in the spatial distribution of THg in resident IRL dolphins were also observed with a general gradient in concentration from north to south. Evaluation of local biogeochemistry and accumulation of mercury in prey species is needed to better understand factors influencing the distribution of Hg in the apex predator. Analyses of temporal and spatial patterns of exposure to THg in this sentinel species may have implications for both ecosystem and public health in the region.

  9. Anadromous char as an alternate food choice to marine animals: A synthesis of Hg concentrations, population features and other influencing factors

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Marlene S., E-mail: marlene.evans@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 11 Innovation Blvd., Saskatoon SK S7N 3H5 (Canada); Muir, Derek C.G. [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Rd., Burlington, ON L7R 4A6 (Canada); Keating, Jonathan [Environment Canada, Water Science and Technology Directorate, 11 Innovation Blvd., Saskatoon SK S7N 3H5 (Canada); Wang, Xiaowa [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Rd., Burlington, ON L7R 4A6 (Canada)

    2015-03-15

    This study was conducted to confirm sporadic measurements made over the late 1970s to the early 1990s which determined that mercury (Hg) concentrations were low in anadromous char across Arctic and subarctic Canada including northern Québec and Labrador. Over 2004–2013, anadromous char populations across northern Canada were investigated at 20 sites for Hg concentrations and life history characteristics. Hg concentrations were extremely low in anadromous char muscle, typically < 0.05 μg/g (wet weight) and, at each location, generally increased with fish length, age and nitrogen isotope (δ{sup 15}N) ratio and decreased with condition factor and %lipid; correlations with carbon isotope (δ{sup 13}C) ratio were inconsistent. Location and year were significant variables influencing Hg concentrations over the study area; longitude and latitude also were significant influencing variables. Char length, weight, age, condition factor and lipid content explained additional variance. A tendency towards higher Hg concentrations with increasing latitude may be partially related to decreasing growth of char towards the north. However, Hg concentrations in char were positively correlated with growth rates suggesting that Hg concentrations in char also were higher in the more productive study areas, including to the west where mainland riverine inputs of terrestrial carbon, nutrients, and Hg were greater. The data base for assessing time trends in char was limited by the small number of years investigated at most locations, variable fish size across years, small sample size, etc. Where temporal trends were detected, they were of increase on the long term (1970s, 1980s or early 1990s to the present) but of decrease on the short term (early 2000s to present) with Nain (Labrador) showing the converse pattern. Higher Hg concentrations were also related to lower condition factor and cooler springs. Hg concentrations in anadromous char are compared with other terrestrial, aquatic

  10. Dissolved gaseous Hg (DGM in the Mediterranean surface and deep waters

    Directory of Open Access Journals (Sweden)

    Kotnik J.

    2013-04-01

    Full Text Available Dissolved gaseous mercury (DGM was studied in surface and deep waters of the Mediterranean Sea for last 12 years during several oceanographic cruises on board the Italian research vessel Urania and covered both Western and Eastern Mediterranean Basins as well as Adriatic Sea. DGM was measured together with other mercury species (RHg - reactive Hg, THg - total Hg, MeHg - monomethyl Hg and DMeHg - dimethylmercury, and with some water quality parameters in coastal and open sea deep water profiles, however only DGM will be discussed here. DGM represents a considerable portion of THg (average of about 20 % in Mediterranean waters. Spatial and seasonal variations of measured DGM concentrations were observed in different indentified water masses as well as iwere observed. DGM was the highest in the northern Adriatic, most polluted part of the Mediterranean Sea as the consequence of Hg mining in Idrija and heavy industry of northern Italy.Generally, average DGM concentration was higher in W and E Mediteranean Deep Waters (WMDW and EMDW and Leavantine Intermediate Water (LIW than overlaying Modified Atlantic Water (MAW, however it was the highest in N Adriatic Surface waters and consequently in out flowing Adriatic Deep Waters (ADW. In deep water profiles the portion of DGM typically increased at depths with oxygen minimum and then towards the bottom, especially in areas with strong tectonic activity (Alboran Sea, Strait of Sicily, Tyrrhenian Sea, indicating its bacterial and/or geotectonic origin. A comparison of the results obtained in this study to others performed in the Mediterranean shows no significant differences. Results were also compared to the results obtained in the Pacific and Atlantic Oceans. During last oceanographic cruise in 2011 covering area between Livorno and Lipari Islands a novel method for continuous DGM determination in surface waters (Wangberg and Gardfeldt, 2011 was applied and compared to standard method.

  11. The average concentrations of As, Cd, Cr, Hg, Ni and Pb in residential soil and drinking water obtained from springs and wells in Rosia Montana area.

    Data.gov (United States)

    U.S. Environmental Protection Agency — The average concentrations of As, Cd, Cr, Hg, Ni and Pb in n=84 residential soil samples, in Rosia Montana area, analyzed by X-ray fluorescence spectrometry are...

  12. The influence of external subsidies on diet, growth and Hg concentrations of freshwater sport fish: implications for management and fish consumption advisories

    Science.gov (United States)

    Lepak, J.M.; Hooten, M.B.; Johnson, B.M.

    2012-01-01

    Mercury (Hg) contamination in sport fish is a global problem. In freshwater systems, food web structure, sport fish sex, size, diet and growth rates influence Hg bioaccumulation. Fish stocking is a common management practice worldwide that can introduce external energy and contaminants into freshwater systems. Thus, stocking can alter many of the factors that influence Hg concentrations in sport fish. Here we evaluated the influence of external subsidies, in the form of hatchery-raised rainbow trout Oncorhynchus mykiss on walleye Sander vitreus diet, growth and Hg concentrations in two freshwater systems. Stocking differentially influenced male and female walleye diets and growth, producing a counterintuitive size-contamination relationship. Modeling indicated that walleye growth rate and diet were important explanatory variables when predicting Hg concentrations. Thus, hatchery contributions to freshwater systems in the form of energy and contaminants can influence diet, growth and Hg concentrations in sport fish. Given the extensive scale of fish stocking, and the known health risks associated with Hg contamination, this represents a significant issue for managers monitoring and manipulating freshwater food web structures, and policy makers attempting to develop fish consumption advisories to protect human health in stocked systems.

  13. Determination of total selenium in geological samples by HG-AFS after concentration with thiol cotton fiber

    Institute of Scientific and Technical Information of China (English)

    FAN Haifeng; WEN Hanjie; HU Ruizhong; CHANG Bin

    2008-01-01

    Standard reference material and different geological samples were dissolved by system A (the mixture of nitric and perchloric acids) and system B (mixture of nitric, perchloric and hydrofluoric acids), and total Se in all samples was measured by hydride-generation atomic fluorescence spectrometry (HG-AFS) after concentration with thiol cotton fiber (TCF). The analytical results obtained by the two digestion method are in good agreement (within the limit of errors) for most of the samples, particularly for those having recommended values. The Se concentrations determined by the two methods are of no difference, and the correlation coefficient is 0.9986; the relative standard deviation (RSD) for the determination of 0.04 (g/g Se is 10.2%. The recovery rates of systems A and B by the standard-addition method were 96%-106% and 99%-104%, respectively.

  14. Invertase-labeling gold-dendrimer for in situ amplified detection mercury(II) with glucometer readout and thymine-Hg(2+)-thymine coordination chemistry.

    Science.gov (United States)

    Qiu, Zhenli; Shu, Jian; Jin, Guixiao; Xu, Mingdi; Wei, Qiaohua; Chen, Guonan; Tang, Dianping

    2016-03-15

    A simple, low-cost transducer with glucometer readout was designed for sensitive detection of mercury(II) (Hg(2+)), coupling with thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination chemistry and invertase-functionalized gold-dendrimer nanospheres for the signal amplification. Initially, nanogold-encapsulated poly(amidoamine) dendrimers (Au DENs) were synthesized by in-situ reduction of gold(III). Thereafter, the as-prepared Au DENs were utilized for the labeling of invertase and T-rich signal DNA probe. In the presence of target Hg(2+), the functionalized Au DENs were conjugated to capture DNA probe-modified electrode via T-Hg(2+)-T coordination chemistry. Accompanying the Au DENs, the labeled invertase could hydrolyze sucrose into glucose, which could be quantitatively monitored by an external personal glucometer (PGM). The PGM signal increased with the increasing target Hg(2+) in the sample. Under the optimal conditions, our designed sensing platform exhibited good PGM responses toward target Hg(2+), and allowed the detection of Hg(2+) at a concentration as low as 4.2 pM. This sensing system also displayed remarkable specificity relative to target Hg(2+) against other competing ions, and could be applied for reliable monitoring of spiked Hg(2+) into the environmental water samples with satisfactory results. With the advantages of cost-effectiveness, simplicity, portability, and convenience, our strategy provides a tremendous potential to be a promising candidate for point-of-use monitoring of non-glucose targets by the public.

  15. Phytochelatin synthesis in response to Hg uptake in aquatic plants near a chlor-alkali factory.

    Science.gov (United States)

    Turull, Marta; Grmanova, Gabriela; Dago, Àngela; Ariño, Cristina; Díez, Sergi; Díaz-Cruz, José Manuel; Esteban, Miquel

    2017-06-01

    The effects of mercury (Hg) released from a chlor-alkali factory in aquatic plants along the Ebro River basin (NE Spain) were analysed considering the phytochelatins (PCn) and their isoforms content in these plants. These compounds were analyzed using HPLC with amperometric detection, and the macrophytes species Ceratophyllum demersum and Myriopyllum spicatum were collected in two sampling campaigns, autumn and spring, respectively. To correlate the PCn content in macrophytes with the Hg contamination, analysis of total Hg (THg) content in plants and suspended particulate matter, as well as the dissolved-bioavailable fraction of Hg in water measured by the diffusive gradient in thin film (DGT) technique were done. The results confirm the presence of PC2-Ala in extracts of C. demersum and PC2-desGly in M. spicatum, and the concentration of these thiol compounds depends clearly on the distance between the hot spot and the downstream sites: the higher the levels are, the closer the hot spot is. Since most of the Hg is hypothesized to be associated with SPM and transported downstream, our results of the DGT suggest that trace amounts of Hg in water can be released as free metal ions yielding a certain accumulation in plants (reaching the ppb level) that are enough for activation of induction of PCs. A few PCs species have been determined, at different seasons, indicating that they can be used as good indicators of the presence of bioavailable Hg in aquatic media throughout the year.

  16. International system of units traceable results of Hg mass concentration at saturation in air from a newly developed measurement procedure.

    Science.gov (United States)

    Quétel, Christophe R; Zampella, Mariavittoria; Brown, Richard J C; Ent, Hugo; Horvat, Milena; Paredes, Eduardo; Tunc, Murat

    2014-08-05

    Data most commonly used at present to calibrate measurements of mercury vapor concentrations in air come from a relationship known as the "Dumarey equation". It uses a fitting relationship to experimental results obtained nearly 30 years ago. The way these results relate to the international system of units (SI) is not known. This has caused difficulties for the specification and enforcement of limit values for mercury concentrations in air and in emissions to air as part of national or international legislation. Furthermore, there is a significant discrepancy (around 7% at room temperature) between the Dumarey data and data calculated from results of mercury vapor pressure measurements in the presence of only liquid mercury. As an attempt to solve some of these problems, a new measurement procedure is described for SI traceable results of gaseous Hg concentrations at saturation in milliliter samples of air. The aim was to propose a scheme as immune as possible to analytical biases. It was based on isotope dilution (ID) in the liquid phase with the (202)Hg enriched certified reference material ERM-AE640 and measurements of the mercury isotope ratios in ID blends, subsequent to a cold vapor generation step, by inductively coupled plasma mass spectrometry. The process developed involved a combination of interconnected valves and syringes operated by computer controlled pumps and ensured continuity under closed circuit conditions from the air sampling stage onward. Quantitative trapping of the gaseous mercury in the liquid phase was achieved with 11.5 μM KMnO4 in 2% HNO3. Mass concentrations at saturation found from five measurements under room temperature conditions were significantly higher (5.8% on average) than data calculated from the Dumarey equation, but in agreement (-1.2% lower on average) with data based on mercury vapor pressure measurement results. Relative expanded combined uncertainties were estimated following a model based approach. They ranged from 2

  17. Concentration of Mercury in Cockles (Anadara granosa and A. antiquata) Harvested from Estuaries of Western Lombok, Indonesia, and Potential Risks to Human Health.

    Science.gov (United States)

    Rahayu, Rachmawati Noviana; Irawan, Bambang; Soegianto, Agoes

    2016-01-01

    This study measured the levels of total mercury (tHg) in the whole tissues of cockles (Anadara granosa and A. antiquata) harvested from three estuaries of Western Lombok Island (WLI), Indonesia. This paper also evaluated the hazard level posed by the mercury in relation to the maximum residual limit for human consumption and to estimate the weekly intake and compare it with the provisional tolerable weekly intake (PTWI). The tHg concentrations in A. granosa ranged from 0.020 to 0.070 mg kg(-1), and those in A. antiquata were between 0.032 and 0.077 mg kg(-1) at all locations. All samples of cockles harvested from WLI contain tHg below the permissible limit for human consumption. The maximum weekly intakes for total mercury by coastal people range from 0.28 to 1.08 µg kg(-1) b.w., and they are below the recommended values of PTWI (5.6 µg kg(-1) b.w.). If it is assumed that 100% of the Hg in cockles is methyl mercury (MeHg), consumption of the indicated amounts at the measured values wouldn't exceed the MeHg PTWI (1.6 µg kg(-1) b.w.).

  18. Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus)

    Science.gov (United States)

    McGrew, Ashley K.; O'Hara, Todd M.; Stricker, Craig A.; Castellini, Margaret; Beckmen, Kimberlee B.; Salman, Mo D.; Ballweber, Lora R.

    2015-01-01

    Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within the host. [THg] and stable isotopes (C and N) were determined for helminths, host tissues, and lumen contents from 88 wolves. Sixty-three wolves contained grossly visible helminths (71.5%). The prevalence of taeniids and ascarids was 63.6% (56/88) and 20.5% (18/88), respectively. Nine of these 63 wolves contained both taeniids and ascarids (14.3%). All ascarids were determined to beToxascaris leonina. Taenia species present included T. krabbei and T. hydatigena. Within the GI tract, [THg] in the lumen contents of the proximal small intestine were significantly lower than in the distal small intestine. There was a significant positive association between hepatic and taeniid [THg]. Bioaccumulation factors (BAF) ranged from < 1 to 22.9 in taeniids, and 1.1 to 12.3 in T. leonina. Taeniid and ascarid BAF were significantly higher than 1, suggesting that both groups are capable of THg accumulation in their wolf host. δ13C in taeniids was significantly lower than in host liver and skeletal muscle. [THg] in helminths and host tissues, in conjunction with stable isotope (C and N) values, provides insight into food-web dynamics of the host GI tract, and aids in elucidating ecotoxicoparasitologic relationships. Variation of [THg] throughout the GI tract, and between parasitic groups, underscores the need to further evaluate the effect(s) of feeding niche, and the nutritional needs of parasites, as they relate to toxicant exposure and distribution within the host.

  19. Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus).

    Science.gov (United States)

    McGrew, Ashley K; O'Hara, Todd M; Stricker, Craig A; Castellini, J Margaret; Beckmen, Kimberlee B; Salman, Mo D; Ballweber, Lora R

    2015-12-01

    Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within the host. [THg] and stable isotopes (C and N) were determined for helminths, host tissues, and lumen contents from 88 wolves. Sixty-three wolves contained grossly visible helminths (71.5%). The prevalence of taeniids and ascarids was 63.6% (56/88) and 20.5% (18/88), respectively. Nine of these 63 wolves contained both taeniids and ascarids (14.3%). All ascarids were determined to be Toxascaris leonina. Taenia species present included T. krabbei and T. hydatigena. Within the GI tract, [THg] in the lumen contents of the proximal small intestine were significantly lower than in the distal small intestine. There was a significant positive association between hepatic and taeniid [THg]. Bioaccumulation factors (BAF) ranged from <1 to 22.9 in taeniids, and 1.1 to 12.3 in T. leonina. Taeniid and ascarid BAF were significantly higher than 1, suggesting that both groups are capable of THg accumulation in their wolf host. δ13C in taeniids was significantly lower than in host liver and skeletal muscle. [THg] in helminths and host tissues, in conjunction with stable isotope (C and N) values, provides insight into food-web dynamics of the host GI tract, and aids in elucidating ecotoxicoparasitologic relationships. Variation of [THg] throughout the GI tract, and between parasitic groups, underscores the need to further evaluate the effect(s) of feeding niche, and the nutritional needs of parasites, as they relate to toxicant exposure and distribution within the host. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. [Concentration of Hg, Pb, Cd, Cr and As in liver Carcharhinus limbatus (Carcharhiniformes: Carcharhinidae) captured in Veracruz, Mexico].

    Science.gov (United States)

    Mendoza-Díaz, Fernando; Serrano, Arturo; Cuervo-López, Liliana; López-Jiménez, Alejandra; Galindo, José A; Basañez-Muñoz, Agustin

    2013-06-01

    Pollution by heavy metals in marine ecosystems in the Gulf of Mexico is one of the hardest conservation issues to solve. Sharks as top predators are bioindicators of the marine ecosystem health, since they tend to bioaccumulate and biomagnify contaminants; they also represent a food source for local consumption. Thus, the objective of this study was to study the possible presence of heavy metals and a metalloid in livers of Carcharhinus limbatus. For this, a total of 19 shark livers were taken from animals captured nearby Tamihua, Veracruz, Mexico from December 2007 to April 2008. 12 out of the 19 captured sharks were males, one was an adult female, three were juvenile males, and three juvenile females. Four heavy metals (Hg, Pb, Cd, and Cr) and one metaloid (As) were analyzed in shark livers using an atomic absorption spectrophotometry with flame and hydride generator. Our results showed that the maximum concentrations found were: Hg = 0.69 mg/kg, Cd = 0.43 mg/kg, As = 27.37 mg/kg, Cr = 0.70 mg/kg. The minimum concentrations found were: As = 14.91 mg/kg, Cr = 0.35 mg/kg. The Pb could not be determined because the samples did not have the spectrophotometer minimum detectable amount (0.1 mg/kg). None of the 19 samples analyzed showed above the permissible limits established by Mexican and American laws. There was a correlation between shark size and Cr and As concentration (Pearson test). The concentration of Cr and As was observed to be higher in bigger animals. There was not a significant difference in heavy metals concentration between juveniles and adults; however, there was a difference between males and females. A higher Cr concentration was found in females when compared to males. None of the samples exceed the maximum limit established by the laws of Mexico and the United States of America. Much longer studies are needed with C. limbatus and other species caught in the region, in order to determine the degree of contaminants exposure in aquatic ecosystems

  1. Trace element concentrations in skin of free-ranging bottlenose dolphins (Tursiops truncatus) from the southeast Atlantic coast.

    Science.gov (United States)

    Stavros, Hui-Chen W; Bossart, Gregory D; Hulsey, Thomas C; Fair, Patricia A

    2007-12-15

    Concentrations of trace elements (Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sb, Se, Sn, Tl, U, V, Zn) and total mercury (THg) were determined in skin samples collected from free-ranging bottlenose dolphin (Tursiops truncatus) populations. Dolphins were captured in the estuarine waters of Charleston (CHS), South Carolina (n=74) and the Indian River Lagoon (IRL), Florida (n=75) during 2003, 2004 and 2005. A subset of the skin tissue samples were used to determine methylmercury (MeHg) levels in CHS (n=17) and IRL (n=8) bottlenose dolphins. Distributions of trace element concentrations by age (adult vs. juvenile), gender (male vs. female) and study area (CHS vs. IRL) were examined. In general, higher elemental skin concentrations were found in CHS adult males than those of IRL adult males, except for THg and MeHg. For CHS dolphins, adult females showed significantly higher THg levels than juvenile females while higher Mn levels were found in juvenile females. For IRL dolphins, adult males showed significantly higher As concentrations than that in juvenile males and females while higher Co and V levels were found in juvenile males than adult males. Of all elements measured in this study, significantly higher levels of Fe, Se and Zn concentrations in skin tissue of both dolphin populations were similar to other studies reported previously. Percentage of MeHg/THg in skin tissue of CHS and IRL dolphin was about 72% and 73%, respectively. Dietary levels of trace elements may play an important role in contributing to concentration differences for As, Co, Mn, Sb, Se, THg and Tl between CHS and IRL dolphins. Total Hg concentrations were significantly correlated with the age of CHS dolphins, while an inverse relationship was detected for Cu, Mn, Pb, U and Zn. The only significant correlation found between trace element concentration and IRL dolphins' age was Mn. Geographic differences in several trace element concentrations (As, Co, Mn, Sb, Se, THg and Tl) in skin

  2. Global versus local causes and health implications of high mercury concentrations in sharks from the east coast of South Africa.

    Science.gov (United States)

    McKinney, Melissa A; Dean, Kylie; Hussey, Nigel E; Cliff, Geremy; Wintner, Sabine P; Dudley, Sheldon F J; Zungu, M Philip; Fisk, Aaron T

    2016-01-15

    Conservation concern regarding the overharvest of global shark populations for meat and fin consumption largely surrounds documented deleterious ecosystem effects, but may be further supported by improved knowledge of possibly high levels in their edible tissues (particularly meat) of the neurotoxin, methylmercury (CH3Hg). For many regions, however, little data exist on shark tissue Hg concentrations, and reasons for Hg variation within and among species or across regions are poorly understood. We quantified total Hg (THg) in 17 shark species (total n=283) from the east coast of South Africa, a top Hg emitter globally. Concentrations varied from means of around 0.1 mg kg(-1) dry weight (dw) THg in hardnose smoothhound (Mustelus mosis) and whale (Rhincodon typus) sharks to means of over 10 mg kg(-1) dw in shortfin mako (Isurus oxyrinchus), scalloped hammerhead (Sphyrna lewini), white (Carcharodon carcharias) and ragged-tooth (Carcharias taurus) sharks. These sharks had higher THg levels than conspecifics sampled from coastal waters of the North Atlantic and North, mid-, and South Pacific, and although sampling year and shark size may play a confounding role, this result suggests the potential importance of elevated local emissions. Values of THg showed strong, species-specific correlations with length, and nearly half the remaining variation was explained by trophic position (using nitrogen stable isotopes, δ(15)N), whereas measures of foraging habitat (using carbon stable isotopes, δ(13)C) were not significant. Mercury concentrations were above the regulatory guidelines for fish health effects and safe human consumption for 88% and 70% of species, respectively, suggesting on-going cause for concern for shark health, and human consumers of shark meat.

  3. Luminescence and influence of defect concentration on excitons in $^{197}\\!$Hg / $^{197}\\!$Au-doped CdTe

    CERN Document Server

    Hamann, J; Deicher, M; Filz, T; Ostheimer, V; Strasser, F; Wolf, H; Wichert, T

    1999-01-01

    CdTe, implanted with $^{197}\\!$Hg ions, which decay to $^{197}\\!$Au with a half-life of 64.1 h, was investigated by photoluminescence (PL) spectroscopy. The results unambiguously verify the assignments of both, the donor–acceptor pair transition at 1.335 eV, which corresponds to an acceptor level with E$\\scriptstyle_{A}$=263 meV, and the recombination of excitons bound to neutral acceptors at 1.57606 eV to single Au atoms on Cd sites. In addition, the dependence of the intensities of excitonic lines on the defect concentration was investigated quantitatively. The observed intensities are well explained, assuming that a defect can only bind an exciton if there is no additional defect within the volume of the bound exciton. The ratio between the exciton radii of the Cu and Au-bound excitons R$\\scriptscriptstyle^\\textrm{Cu}_{exc}$ / R$\\scriptscriptstyle^\\textrm{Au}_{exc}$ = 1.2$\\pm$0.2 obtained from this model is in good agreement with the ratio derived from the diamagnetic shift parameters of the two correspo...

  4. Mercury in fishes from 21 national parks in the Western United States: inter- and intra-park variation in concentrations and ecological risk

    Science.gov (United States)

    Eagles-Smith, Collin A.; Willacker, James J.; Flanagan Pritz, Colleen M.

    2014-01-01

    Mercury (Hg) is a global contaminant and human activities have increased atmospheric Hg concentrations 3- to 5-fold during the past 150 years. This increased release into the atmosphere has resulted in elevated loadings to aquatic habitats where biogeochemical processes promote the microbial conversion of inorganic Hg to methylmercury, the bioavailable form of Hg. The physicochemical properties of Hg and its complex environmental cycle have resulted in some of the most remote and protected areas of the world becoming contaminated with Hg concentrations that threaten ecosystem and human health. The national park network in the United States is comprised of some of the most pristine and sensitive wilderness in North America. There is concern that via global distribution, Hg contamination could threaten the ecological integrity of aquatic communities in the parks and the wildlife that depends on them. In this study, we examined Hg concentrations in non-migratory freshwater fish in 86 sites across 21 national parks in the Western United States. We report Hg concentrations of more than 1,400 fish collected in waters extending over a 4,000 kilometer distance, from Alaska to the arid Southwest. Across all parks, sites, and species, fish total Hg (THg) concentrations ranged from 9.9 to 1,109 nanograms per gram wet weight (ng/g ww) with a mean of 77.7 ng/g ww. We found substantial variation in fish THg concentrations among and within parks, suggesting that patterns of Hg risk are driven by processes occurring at a combination of scales. Additionally, variation (up to 20-fold) in site-specific fish THg concentrations within individual parks suggests that more intensive sampling in some parks will be required to effectively characterize Hg contamination in western national parks. Across all fish sampled, only 5 percent had THg concentrations exceeding a benchmark (200 ng/g ww) associated with toxic responses within the fish themselves. However, Hg concentrations in 35 percent

  5. Determination of Hg{sup 2+} by on-line separation and pre-concentration with atmospheric-pressure solution-cathode glow discharge atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qing [Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); Zhang, Zhen [Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Wang, Zheng, E-mail: wangzheng@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China)

    2014-10-03

    Highlights: • A modified SBA-15 mesoporous silica (SH-SBA-15) was synthesized as a sorbent. • On-line SPE combined with SCGD-AES based on FIA was used to detect Hg{sup 2+} firstly. • A simple, low-cost Hg{sup 2+} analysis in a complex matrix was established. • The sensitive detection of Hg{sup 2+} was achieved with a detection limit of 0.75 μg L{sup −1}. - Abstract: A simple and sensitive method to determine Hg{sup 2+} was developed by combining solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) with flow injection (FI) based on on-line solid-phase extraction (SPE). We synthesized L-cysteine-modified mesoporous silica and packed it in an SPE microcolumn, which was experimentally determined to possess a good mercury adsorption capacity. An enrichment factor of 42 was achieved under optimized Hg{sup 2+} elution conditions, namely, an FI flow rate of 2.0 mL min{sup −1} and an eluent comprised of 10% thiourea in 0.2 mol L{sup −1} HNO{sub 3}. The detection limit of FI–SCGD-AES was determined to be 0.75 μg L{sup −1}, and the precision of the 11 replicate Hg{sup 2+} measurements was 0.86% at a concentration of 100 μg L{sup −1}. The proposed method was validated by determining Hg{sup 2+} in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310)

  6. Dielectric functions and carrier concentrations of Hg{sub 1−x}Cd{sub x}Se films determined by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, A. J.; Peiris, F. C., E-mail: peirisf@kenyon.edu [Department of Physics, Kenyon College, Gambier, Ohio 43022 (United States); Brill, G.; Doyle, K. [U.S. Army Research Laboratory, Adelphi, Maryland 20783-1197 (United States); Myers, T. H. [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)

    2015-08-17

    Spectroscopic ellipsometry, ranging from 35 meV to 6 eV, was used to determine the dielectric functions of a series of molecular beam epitaxy-grown Hg{sub 1−x}Cd{sub x}Se thin films deposited on both ZnTe/Si(112) and GaSb(112) substrates. The fundamental band gap as well as two higher-order electronic transitions blue-shift with increasing Cd composition in Hg{sub 1−x}Cd{sub x}Se, as expected. Representing the free carrier absorption with a Drude oscillator, we found that the effective masses of Hg{sub 1−x}Cd{sub x}Se (grown on ZnTe/Si) vary between 0.028 and 0.050 times the free electron mass, calculated using the values of carrier concentration and the mobility obtained through Hall measurements. Using these effective masses, we determined the carrier concentrations of Hg{sub 1−x}Cd{sub x}Se samples grown on GaSb, which is of significance as films grown on such doped-substrates posit ambiguous results when measured by conventional Hall experiments. These models can serve as a basis for monitoring Cd-composition during sample growth through in-situ spectroscopic ellipsometry.

  7. Determination of Hg(2+) by on-line separation and pre-concentration with atmospheric-pressure solution-cathode glow discharge atomic emission spectrometry.

    Science.gov (United States)

    Li, Qing; Zhang, Zhen; Wang, Zheng

    2014-10-03

    A simple and sensitive method to determine Hg(2+) was developed by combining solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) with flow injection (FI) based on on-line solid-phase extraction (SPE). We synthesized l-cysteine-modified mesoporous silica and packed it in an SPE microcolumn, which was experimentally determined to possess a good mercury adsorption capacity. An enrichment factor of 42 was achieved under optimized Hg(2+) elution conditions, namely, an FI flow rate of 2.0 mL min(-1) and an eluent comprised of 10% thiourea in 0.2 mol L(-1) HNO3. The detection limit of FI-SCGD-AES was determined to be 0.75 μg L(-1), and the precision of the 11 replicate Hg(2+) measurements was 0.86% at a concentration of 100 μg L(-1). The proposed method was validated by determining Hg(2+) in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310).

  8. Global versus local causes and health implications of high mercury concentrations in sharks from the east coast of South Africa

    Energy Technology Data Exchange (ETDEWEB)

    McKinney, Melissa A., E-mail: melissa.mckinney@uconn.edu [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Dean, Kylie; Hussey, Nigel E. [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Cliff, Geremy; Wintner, Sabine P. [KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320 (South Africa); Biomedical Resource Unit, University of KwaZulu-Natal, Durban 4000 (South Africa); Dudley, Sheldon F.J. [KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320 (South Africa); Department of Agriculture, Forestry and Fisheries, Cape Town 8012 (South Africa); Zungu, M. Philip [Department of Agriculture, Forestry and Fisheries, Cape Town 8012 (South Africa); Fisk, Aaron T. [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada)

    2016-01-15

    Conservation concern regarding the overharvest of global shark populations for meat and fin consumption largely surrounds documented deleterious ecosystem effects, but may be further supported by improved knowledge of possibly high levels in their edible tissues (particularly meat) of the neurotoxin, methylmercury (CH{sub 3}Hg). For many regions, however, little data exist on shark tissue Hg concentrations, and reasons for Hg variation within and among species or across regions are poorly understood. We quantified total Hg (THg) in 17 shark species (total n = 283) from the east coast of South Africa, a top Hg emitter globally. Concentrations varied from means of around 0.1 mg kg{sup −1} dry weight (dw) THg in hardnose smoothhound (Mustelus mosis) and whale (Rhincodon typus) sharks to means of over 10 mg kg{sup −1} dw in shortfin mako (Isurus oxyrinchus), scalloped hammerhead (Sphyrna lewini), white (Carcharodon carcharias) and ragged-tooth (Carcharias taurus) sharks. These sharks had higher THg levels than conspecifics sampled from coastal waters of the North Atlantic and North, mid-, and South Pacific, and although sampling year and shark size may play a confounding role, this result suggests the potential importance of elevated local emissions. Values of THg showed strong, species-specific correlations with length, and nearly half the remaining variation was explained by trophic position (using nitrogen stable isotopes, δ{sup 15}N), whereas measures of foraging habitat (using carbon stable isotopes, δ{sup 13}C) were not significant. Mercury concentrations were above the regulatory guidelines for fish health effects and safe human consumption for 88% and 70% of species, respectively, suggesting on-going cause for concern for shark health, and human consumers of shark meat. - Highlights: • Hg concentrations in 17 shark species from South Africa's east coast were measured. • Higher values relative to other regions suggested the importance of local

  9. A critical evaluation of the utility of eggshells for estimating mercury concentrations in avian eggs

    Science.gov (United States)

    Peterson, Sarah; Ackerman, Joshua T.; Eagles-Smith, Collin A.; Hartman, C. Alex; Herzog, Mark P.

    2017-01-01

    Eggshells are a potential tool for non-lethally sampling contaminant concentrations in bird eggs, yet few studies have examined their utility to represent mercury exposure. We assessed mercury concentrations in eggshell components for 23 bird species and determined whether they correlated with total mercury (THg) in egg contents. We designed a multi-experiment analysis to examine how THg is partitioned into eggshell components, specifically hardened eggshells, material adhered to the eggshell, and inner eggshell membranes. THg concentrations in eggshells were much lower than in egg contents, and almost all of the THg within the eggshell was contained within material adhered to eggshells and inner eggshell membranes, and specifically not within calcium-rich hardened eggshells. Despite having very little mercury, THg concentrations in hardened eggshells had the strongest correlation with egg contents among all eggshell components. However, species with the same THg concentrations in eggshells had different THg concentrations in egg contents, indicating that there is no global predictive equation among species for the relationship between eggshell and egg content THg concentrations. Further, for all species, THg concentrations in eggshells decreased with relative embryo age. Although the majority of mercury in eggshells was contained within other eggshell components and not within hardened eggshells, THg in hardened eggshells can be used to estimate THg concentrations in egg contents, if embryo age and species are addressed.

  10. Observations of atmospheric Hg species and depositions in remote areas of China

    Directory of Open Access Journals (Sweden)

    Feng X.

    2013-04-01

    Full Text Available From September 2007, we conducted continuous measurements of speciated atmospheric mercury (Hg and atmospheric mercury depositions at five remote sites in China. Four of these sites were involved in the Global Mercury Observation System (GMOS as ground-based stations. These stations were located in the northwest, southwest, northeast, and east part of China, respectively, which represent the regional atmospheric Hg budgets in different areas of China. The preliminary results showed that mean TGM concentrations were in the range of 1.60 – 2.88 ng m-3, with relatively higher levels observed at sites in Eastern China and Southwestern China and lower levels at sites in Northeastern and Northwestern China. TGM concentrations at remote sites of China were also higher than those reported from background sites in North America and Europe, and this is corresponding very well with the Chinese great anthropogenic Hg emissions. Gaseous oxidized mercury (GOM and particulate bounded mercury (PBM were in the ranges of 3.2 – 7.4 pg m−3 and 19.4 – 43.5 pg m-3, respectively. The preliminary result on precipitation showed mean precipitation THg concentrations were in the range of 2.7 – 18.0 ng L-1.

  11. Atmospheric total gaseous mercury (TGM concentrations and wet and dry deposition of mercury at a high-altitude mountain peak in south China

    Directory of Open Access Journals (Sweden)

    H. Zhang

    2009-11-01

    Full Text Available China is regarded as the largest contributor of mercury (Hg to the global atmospheric Hg budget. However, concentration levels and depositions of atmospheric Hg in China are poorly known. Continuous measurements of atmospheric total gaseous mercury (TGM were carried out from May 2008 to May 2009 at the summit of Mt. Leigong in south China. Wet and dry deposition fluxes of Hg were also calculated following collection of precipitation, throughfall and litterfall. Atmospheric TGM concentrations averaged 2.80±1.51 ng m−3, which was highly elevated compared to global background values but much lower than semi-rural and industrial/urban areas in China, indicating great emissions of Hg in central, south and southwest China. Seasonal and diurnal variations of TGM were observed, which reflected variations in source intensity, deposition processes and meteorological factors. Wet deposition of Hg was quite low, while its dry deposition of Hg (litterfall + throughfall-direct wet deposition constituted a major portion of total deposition (~88% for total mercury (THg and 84% for methyl mercury (MeHg. This highlights the importance of vegetation to Hg atmospheric cycling. In a remote forest ecosystem of China, dry deposition of TGM, especially gaseous elemental mercury (GEM, was very important for the depletion of atmospheric Hg. Elevated TGM level in ambient air may accelerate the foliar uptake of Hg through air which may partly explain the elevated Hg dry deposition fluxes observed in Mt. Leigong.

  12. Total- and methyl-mercury concentrations and methylation rates across the freshwater to hypersaline continuum of the Great Salt Lake, Utah, USA

    Science.gov (United States)

    Johnson, William P.; Swanson, Neil; Black, Brooks; Rudd, Abigail; Carling, Gregory; Fernandez, Diego P.; Luft, John; Van Leeuwen, Jim; Marvin-DiPasquale, Mark C.

    2015-01-01

    We examined mercury (Hg) speciation in water and sediment of the Great Salt Lake and surrounding wetlands, a locale spanning fresh to hypersaline and oxic to anoxic conditions, in order to test the hypothesis that spatial and temporal variations in Hg concentration and methylation rates correspond to observed spatial and temporal trends in Hg burdens previously reported in biota. Water column, sediment, and pore water concentrations of methylmercury (MeHg) and total mercury (THg), as well as related aquatic chemical parameters were examined. Inorganic Hg(II)-methylation rates were determined in selected water column and sediment subsamples spiked with inorganic divalent mercury (204Hg(II)). Net production of Me204Hg was expressed as apparent first-order rate constants for methylation (kmeth), which were also expanded to MeHg production potential (MPP) rates via combination with tin reducible ‘reactive’ Hg(II) (Hg(II)R) as a proxy for bioavailable Hg(II). Notable findings include: 1) elevated Hg concentrations previously reported in birds and brine flies were spatially proximal to the measured highest MeHg concentrations, the latter occurring in the anoxic deep brine layer (DBL) of the Great Salt Lake; 2) timing of reduced Hg(II)-methylation rates in the DBL (according to both kmeth and MPP) coincides with reduced Hg burdens among aquatic invertebrates (brine shrimp and brine flies) that act as potential vectors of Hg propagation to the terrestrial ecosystem; 3) values ofkmeth were found to fall within the range reported by other studies; and 4) MPP rates were on the lower end of the range reported in methodologically comparable studies, suggesting the possibility that elevated MeHg in the anoxic deep brine layer results from its accumulation and persistence in this quasi-isolated environment, due to the absence of light (restricting abiotic photo demethylation) and/or minimal microbiological demethylation.

  13. Temporal changes in Hg, Pb, Cd and Zn environmental concentrations in the southern Baltic Sea sediments dated with 210Pb method

    Directory of Open Access Journals (Sweden)

    Tamara Zalewska

    2015-01-01

    Full Text Available The article presents data on heavy metal – Hg, Pb, Cd and Zn – distribution in the layers of marine sediments from the off-shore areas of the southern Baltic Sea: Gdańsk Deep, SE Gotland Basin and Bornholm Deep. Depth profiles of metal concentrations were converted to time-based profiles using the 210Pb dating method and verified by 137Cs distribution in the vertical profile. The linear sedimentation rates in the Gdańsk Deep and SE Gotland Basin are similar, 0.18 cm yr−1 and 0.14 cm yr−1, respectively, while the region of the Bornholm Deep is characterized by a greater sedimentation rate: 0.31 cm yr−1. Regarding anthropogenic pressure, Gdańsk Deep receives the largest share among the analyzed regions. The maximal metal concentrations detected in this area were Zn – 230 mg kg−1, Pb – 77 mg kg−1, Cd – 2.04 mg kg−1 and Hg – 0.27 mg kg−1. The least impact of anthropogenic pressure was noticeable in SE Gotland Basin. The combination of sediment dating with the analysis of vertical distribution of heavy metals in sediments benefited in the determination of target metal concentrations used in environmental status assessments. Reference values of heavy metal concentrations in marine sediments were determined as: Zn – 110 mg kg−1, Pb – 30 mg kg−1, Cd – 0.3 mg kg−1 and Hg – 0.05 mg kg−1 from the period of minor anthropogenic pressure. Basing on the determined indices: enrichment factor (EF, geoaccumulation indicator (Igeo and contamination factor (CF the status of marine environment was assessed regarding the pollution with heavy metals.

  14. Mercury Concentrations in Fish and Sediment within Streams are Influenced by Watershed and Landscape Variables including Historical Gold Mining in the Sierra Nevada, California

    Science.gov (United States)

    Alpers, C. N.; Yee, J. L.; Ackerman, J. T.; Orlando, J. L.; Slotton, D. G.; Marvin-DiPasquale, M. C.

    2015-12-01

    We compiled available data on total mercury (THg) and methylmercury (MeHg) concentrations in fish tissue and streambed sediment from stream sites in the Sierra Nevada, California, to assess whether spatial data, including information on historical mining, can be used to make robust predictions of fish fillet tissue THg concentrations. A total of 1,271 fish from five species collected at 103 sites during 1980-2012 were used for the modeling effort: 210 brown trout, 710 rainbow trout, 79 Sacramento pikeminnow, 93 Sacramento sucker, and 179 smallmouth bass. Sediment data were used from 73 sites, including 106 analyses of THg and 77 analyses of MeHg. The dataset included 391 fish (mostly rainbow trout) and 28 sediment samples collected explicitly for this study during 2011-12. Spatial data on historical mining included the USGS Mineral Resources Data System and publicly available maps and satellite photos showing the areas of hydraulic mine pits and other placer mines. Modeling was done using multivariate linear regression and multi-model inference using Akaike Information Criteria. Results indicate that fish THg, accounting for species and length, can be predicted using geospatial data on mining history together with other landscape characteristics including land use/land cover. A model requiring only geospatial data, with an R2 value of 0.61, predicted fish THg correctly with respect to over-or-under 0.2 μg/g wet weight (a California regulatory threshold) for 108 of 121 (89 %) size-species combinations tested. Data for THg in streambed sediment did not improve the geospatial-only model. However, data for sediment MeHg, loss on ignition (organic content), and percent of sediment less than 0.063 mm resulted in a slightly improved model, with an R2 value of 0.63. It is anticipated that these models will be useful to the State of California and others to predict areas where mercury concentrations in fish are likely to exceed regulatory criteria.

  15. Final report on CCQM-K70: Determination of Hg in natural water at a concentration level required by the European environmental quality standard (EQS)

    Science.gov (United States)

    Schiel, Detlef; Rienitz, Olaf

    2011-01-01

    This comparison 'Hg in natural water' was a follow-up to the pilot studies CCQM-P100.1 and CCQM-P100.2. The aim of this comparison was to demonstrate the capability of national metrology institutes to measure the Hg mass concentration in a natural water sample at the very low concentration level of γ(Hg) ≈ 70 ng/L as required by the EQS. In this way it served to help implement the European Water Framework Directive (WFD). This comparison was an activity of the Inorganic Analysis Working Group (IAWG) of CCQM and was piloted by Physikalisch-Technische Bundesanstalt (PTB, Braunschweig, Germany) with the help of the co-organizers Bundesanstalt für Materialforschung und -prüfung (BAM, Berlin, Germany), Laboratoire National de Métrologie et d'Essais (LNE, Paris, France), and the Joint Research Centre-Institute for Reference Materials and Measurements (EC-JRC-IRMM, Geel, Belgium). The following laboratories participated in this key comparison (in alphabetical order): BAM (Germany) EC-JRC-IRMM (European Union) KRISS (Republic of Korea) LGC (United Kingdom) LNE (France) NIST (United States of America) NMIA (Australia) NRC (Canada) PTB (Germany) SP (Sweden) The majority of participants applied isotope dilution mass spectrometry (IDMS) using sector field or quadrupole inductively coupled plasma MS (ICP-MS) in combination with cold vapour (CV) generation as the analytical technique. NRC reported a combined result of ID-CV-ICP-MS and CV atomic absorption spectrometry (CV-AAS). SP applied a standard addition method on a sector field ICP-MS, while BAM made use of an external 5-point calibration on a CV atomic fluorescence spectrometer (AFS). The key comparison reference value (KCRV) was agreed upon during the IAWG meeting in April 2010 at BIPM as the sum of the added Hg content calculated from the gravimetric sample preparation and the Hg matrix content of the water used for sample preparation (determined and validated on two independent pathways). Accordingly the degrees

  16. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  17. Hg transfer from contaminated soils to plants and animals

    NARCIS (Netherlands)

    Rodrigues, S.M.; Henriques, B.; Reis, A.T.; Duarte, A.C.; Pereira, E.; Romkens, P.F.A.M.

    2012-01-01

    Understanding the transfer of mercury (Hg) from soil to crops is crucial due to Hg toxicity and Hg occurrence in terrestrial systems. Previous research has shown that available Hg in soils contributes to plant Hg levels. Plant Hg concentrations are related to soil conditions and plant characteristic

  18. Tellurite suspended nanowire surrounded with large holes for single-mode SC and THG generations

    Science.gov (United States)

    Liao, Meisong; Qin, Guanshi; Yan, Xin; Chaudhari, Chitrarekha; Suzuki, Takenobu; Ohishi, Yasutake

    2011-05-01

    For a suspended nanowire, the holes surrounding the core are expected to be as large as possible to propagate the light at wavelengths as long as possible. However, the fabrication of nanowire surrounded with large holes is still a challenge so far. In this paper, a method which involves pumping positive pressure of nitrogen gas in both the cane fabrication and fiber-drawing processes, is proposed. A suspended nanowire, with a core diameter of 480 nm and an unprecedented large diameter ratio of holey region to core (DRHC) of at least 62, is fabricated in the length of several hundred meters. Owing to the large holes, the confinement loss of the suspended nanowire is insignificant when the wavelength of light propagated in it is 1700 nm. Additionally, the tube-shaped glass cladding of the suspended nanowire shifts the singlemode cutoff wavelength to 810 nm, which is much shorter than the cutoff wavelength, 1070 nm, of a naked nanowire with the same diameter. A single-mode supercontinuum (SC) generation covering a wavelength range of 900-1600 nm is obtained under 1064 nm pump pulse with the peak power as low as 24 W. A single-mode third harmonic generation (THG) is observed by this nanowire under the pump of a 1557 nm femtosecond fiber laser. This work indicates that the suspended nanowire with large holes can provide high nonlinearity together with single-mode propagation, which leads to interesting applications in compact nonlinear devices.

  19. Immunomodulation the marine green mussel Perna viridis exposed to sub-lethal concentrations of Cu and Hg.

    Science.gov (United States)

    Thiagarajan, R; Gopalakrishnan, S; Thilagam, H

    2006-10-01

    Environmental pollution is a growing concern and, more importantly, pollution of the aquatic ecosystem is alarming. Marine pollution may be one of the reasons for disease incidence in marine organisms, which is caused due to adverse effects of pollutants on the immune system. Bivalves are commonly used as bio-indicators of marine pollution, and immunomodulation due to toxicants is one of the important bio-markers used. Perna viridis too have been used as a bio-indicator, but this study is, to our knowledge, a first report on immunomodulation produced by metals, in P. viridis. Animals were exposed to copper and mercury at their sub-lethal concentrations of 20 microg L(-1) and 10 microg L(-1), respectively. Immune parameters including phenoloxidase, reactive oxygen species generation, and phagocytosis were monitored. The study period was for 25 days (chronic long-term exposure) and objectives established whether metals produced immunomodulation and to understand the effects of long-term exposure on immunomodulation. Results showed that both metals adversely affected immune parameters studied and, interestingly, there appears to be some level of recovery (depuration) from the toxic effects of metals.

  20. Total mercury concentrations in anadromous Northern Dolly Varden from the northwestern Canadian Arctic: A historical baseline study

    Energy Technology Data Exchange (ETDEWEB)

    Tran, L., E-mail: l5tran@uwaterloo.ca [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Reist, J.D. [Fisheries and Oceans Canada, Winnipeg, Manitoba R3T 2N6 (Canada); Power, M., E-mail: m3power@uwaterloo.ca [Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-03-15

    Previous research has documented the significance of total mercury (THg) as a northern contaminant in general and of fish in particular. While much research has been devoted to documenting both spatial and temporal changes in THg in consumed fish, little effort has been directed at understanding patterns of THg in Dolly Varden (Salvelinus malma), a prized subsistence species throughout the western North American Arctic. Here we report historical THg concentrations for anadromous Dolly Varden from 10 populations in the Yukon and Northwest Territories sampled across a range of latitudes (67–69°N) and longitudes (136–141°W) between the years 1988–91. Unadjusted mean THg concentrations ranged from 15 to 254 ng/g wet weight. Length-adjusted THg concentrations were significantly different among sites, but were not related to latitude or longitude. Within and among populations, THg was significantly related to fork-length, age, δ{sup 15}N, and δ{sup 13}C, with the variation in THg found among populations being best explained by size. The data serve as an important baseline against which future changes in THg levels in this important subsistence fishery may be compared to determine the significance of any observed trends. - Highlights: • THg were measured in Dolly Varden from the Yukon and Northwest Territories. • Length-adjusted THg concentrations were not related to latitude or longitude. • Among-population variation in THg was best explained by fork-length. • Length-adjusted THg concentrations were related to age, δ{sup 15}N, and δ{sup 13}C. • Mean THg were below Health Canada’s consumption guideline for commercial fish.

  1. Pan-Arctic concentrations of mercury and stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) in marine zooplankton.

    Science.gov (United States)

    Pomerleau, Corinne; Stern, Gary A; Pućko, Monika; Foster, Karen L; Macdonald, Robie W; Fortier, Louis

    2016-05-01

    Zooplankton play a central role in marine food webs, dictating the quantity and quality of energy available to upper trophic levels. They act as "keystone" species in transfer of mercury (Hg) up through the marine food chain. Here, we present the first Pan-Arctic overview of total and monomethylmercury concentrations (THg and MMHg) and stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) in selected zooplankton species by assembling data collected between 1998 and 2012 from six arctic regions (Laptev Sea, Chukchi Sea, southeastern Beaufort Sea, Canadian Arctic Archipelago, Hudson Bay and northern Baffin Bay). MMHg concentrations in Calanus spp., Themisto spp. and Paraeuchaeta spp. were found to increase with higher δ(15)N and lower δ(13)C. The southern Beaufort Sea exhibited both the highest THg and MMHg concentrations. Biomagnification of MMHg between Calanus spp. and two of its known predators, Themisto spp. and Paraeuchaeta spp., was greatest in the southern Beaufort Sea. Our results show large geographical variations in Hg concentrations and isotopic signatures for individual species related to regional ecosystem features, such as varying water masses and freshwater inputs, and highlight the increased exposure to Hg in the marine food chain of the southern Beaufort Sea.

  2. Performance curves comparison of THG efficiency in CsLiB6O10 on flattened Gaussian and Gaussian beams

    Institute of Scientific and Technical Information of China (English)

    Li Wang(王丽); Jianhua Xue(薛建华)

    2003-01-01

    The conversion efficiency of THG on the flattened Gaussian and Gaussian beams is obtained in detail numerical stimulation for CsLiB6O10. The conversion efficiencies of 86.7% and 96% of the flattened Gaussian are larger than those of Gaussian beams of 72.6% and 88% under type I and type Ⅱ(1) phase matching. The efficiencies affected by the pump intensity, polarization rate, crystal lengths and orders of the flattened Gaussian beams were presented.

  3. Pan-Arctic concentrations of mercury and stable isotope ratios of carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) in marine zooplankton

    Energy Technology Data Exchange (ETDEWEB)

    Pomerleau, Corinne, E-mail: corinne.pomerleau@umanitoba.ca [Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Greenland Institute of Natural Resources, Kivioq 2, Nuuk 3900, Greenland (Denmark); Stern, Gary A.; Pućko, Monika [Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Foster, Karen L. [Foster Environmental, Peterborough, ON K9J 8L2 (Canada); Macdonald, Robie W. [Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC V8L 4B2 (Canada); Fortier, Louis [Québec-Océan, Département de Biologie, Université Laval, Québec, QC G1V 0A6 (Canada)

    2016-05-01

    Zooplankton play a central role in marine food webs, dictating the quantity and quality of energy available to upper trophic levels. They act as “keystone” species in transfer of mercury (Hg) up through the marine food chain. Here, we present the first Pan-Arctic overview of total and monomethylmercury concentrations (THg and MMHg) and stable isotope ratios of carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) in selected zooplankton species by assembling data collected between 1998 and 2012 from six arctic regions (Laptev Sea, Chukchi Sea, southeastern Beaufort Sea, Canadian Arctic Archipelago, Hudson Bay and northern Baffin Bay). MMHg concentrations in Calanus spp., Themisto spp. and Paraeuchaeta spp. were found to increase with higher δ{sup 15}N and lower δ{sup 13}C. The southern Beaufort Sea exhibited both the highest THg and MMHg concentrations. Biomagnification of MMHg between Calanus spp. and two of its known predators, Themisto spp. and Paraeuchaeta spp., was greatest in the southern Beaufort Sea. Our results show large geographical variations in Hg concentrations and isotopic signatures for individual species related to regional ecosystem features, such as varying water masses and freshwater inputs, and highlight the increased exposure to Hg in the marine food chain of the southern Beaufort Sea. - Highlights: • Assessment of Pan-Arctic variability in zooplankton Hg concentrations • Increased exposure to Hg in the marine food chain of the southern Beaufort Sea • Zooplankton plays a central role in the Hg pathway within Arctic marine food webs.

  4. Hair and Bone as Predictors of Tissular Mercury Concentration in the Western Alaska Red Fox, Vulpes vulpes

    Science.gov (United States)

    Dainowski, BH; Duffy, LK; McIntyre, J; Jones, P

    2015-01-01

    We evaluated if total mercury (THg) concentrations of keratin-based and bone-based tissues can predict THg concentrations in skeletal muscle, renal medulla, renal cortex, and liver. The THg concentration in matched tissues of 65 red foxes, Vulpes vulpes, from western Alaska was determined. Hair THg concentration had a significant positive correlation with liver, renal medulla, renal cortex, and muscle. The THg concentration for males and females is moderately predictive of THg concentration in the renal cortex and liver for these foxes based on R2 values (R2 = 0.61 and 0.63, respectively). Bone is weakly predictive of THg concentration in muscle (R2 = 0.36), but not a reliable tissue to predict THg concentration in liver (R2 = 0.28), renal cortex (R2 = 0.33), or renal medulla (R2 = 0.29). These results confirm the potential use of trapped animals, specifically foxes, as useful Arctic sentinel species to inform researchers about patterns in THg levels over time as industrialization of the Arctic continues. PMID:25777958

  5. Dehydroepiandrosterone (DHEA) is an anabolic steroid like dihydrotestosterone (DHT), the most potent natural androgen, and tetrahydrogestrinone (THG).

    Science.gov (United States)

    Labrie, Fernand; Luu-The, Van; Martel, Céline; Chernomoretz, Ariel; Calvo, Ezequiel; Morissette, Jean; Labrie, Claude

    2006-07-01

    We have recently taken advantage of the unique power of DNA microarrays to compare the genomic expression profile of tetrahydrogestrinone (THG) with that of dihydrotestosterone (DHT), the most potent natural androgen, thus clearly demonstrating that THG is an anabolic steroid. In 2004, the U.S. Controlled Substances Act has been modified to include androstenedione (4-dione) as an anabolic steroid. However, despite the common knowledge that dehydroepiandrosterone (DHEA) is the precursor of testosterone, DHEA has been excluded from the list of anabolic steroids. We thus used the same DNA microarray technology to analyze the expression profile of practically all the 30,000 genes of the mouse genome modulated by DHEA and DHT in classical androgen-sensitive tissues. Daily subcutaneous injections of DHT (0.1mg) or DHEA (3mg) for 1 month in gonadectomized C57BL6/129 SV mice increased ventral prostate, dorsal prostate, seminal vesicle and preputial gland weight (p or =30%), in the prostate (ventral+dorsal), seminal vesicles and preputial glands, respectively, compared to tissues from gonadectomized control animals. After 7 days of daily treatment with DHEA and DHT, 629, 919 and 562 probe sets were commonly modulated in the same tissues while after 27 days of treatment, 1195, 5127 and 2883 probe sets were modulated, respectively. In analogy with the data obtained with THG, the present microarray data provide an extremely precise and unquestionable genomic signature and proof of the androgenic/anabolic activity of DHEA. Such data add to the literature showing that DHEA is transformed into androgens in the human peripheral tissues as well as in laboratory animal species, including the monkey, thus exerting potent androgenic/anabolic activity. The present microarray approach to identify anabolic compounds is applicable to all potential androgenic/anabolic compounds.

  6. Beaver Ponds Increase Methylmercury and Nutrients Concentrations in Canadian Shield Streams

    Science.gov (United States)

    Roy, V.; Amyot, M.; Carignan, R.

    2007-12-01

    Beaver populations and the number of beaver dams are currently increasing in many Canadian regions. Since natural and anthropogenic impoundments have historically been identified as sources of the potent neurotoxin methylmercury (MeHg), beaver dams could also increase MeHg levels in streams. During summer 2006, we collected water samples upstream and downstream from twenty beaver dams of the Laurentians, located on the Canadian Shield. Samples were analysed for total Hg, MeHg and other chemical variables including DOC, TP, TDP, TN, and major ions. Significant increases of nutrients (DOC, TP, TDP, TN) and ammonium concentrations and depletions of oxygen, nitrate and sulphate concentrations between inlet and outlet show that beaver ponds provide environmental conditions that can favour methylation of inorganic mercury. Heterogeneity of the ratio MeHg/THg at the outlet among our sites was well explained by the estimated age of the impoundment, with methylation capacity of beaver ponds decreasing with age. Further, the geographic location of beaver ponds influenced water chemistry at the outlet, as we observed a dichotomy between northern and southern sites; these differences were based mainly on forest composition. On average, beaver impoundments increased MeHg concentrations by 5.7 fold, total Hg concentrations by 1.6 fold and nutrients concentrations by 2-3 fold. Overall, our results suggest that beaver dams may considerably increase MeHg and nutrients levels in downstream ecosystems. The impact of beavers on the cycling of contaminants and nutrients in boreal watersheds should therefore be considered in the management of their populations.

  7. Total mercury concentrations in anadromous Northern Dolly Varden from the northwestern Canadian Arctic: a historical baseline study.

    Science.gov (United States)

    Tran, L; Reist, J D; Power, M

    2015-03-15

    Previous research has documented the significance of total mercury (THg) as a northern contaminant in general and of fish in particular. While much research has been devoted to documenting both spatial and temporal changes in THg in consumed fish, little effort has been directed at understanding patterns of THg in Dolly Varden (Salvelinus malma), a prized subsistence species throughout the western North American Arctic. Here we report historical THg concentrations for anadromous Dolly Varden from 10 populations in the Yukon and Northwest Territories sampled across a range of latitudes (67-69°N) and longitudes (136-141°W) between the years 1988-91. Unadjusted mean THg concentrations ranged from 15 to 254 ng/g wet weight. Length-adjusted THg concentrations were significantly different among sites, but were not related to latitude or longitude. Within and among populations, THg was significantly related to fork-length, age, δ(15)N, and δ(13)C, with the variation in THg found among populations being best explained by size. The data serve as an important baseline against which future changes in THg levels in this important subsistence fishery may be compared to determine the significance of any observed trends.

  8. 烟台近海海域经济类海洋生物体内Sn、Hg的含量分析%Study on Concentrations of Sn, Hg in Some Edible Marine Organisms in Yantai Coastal Areas

    Institute of Scientific and Technical Information of China (English)

    邵立娜; 任宗明; 张高生; 陈琳琳; 刘东艳; 王子健; 赵建平

    2011-01-01

    To evaluate the contamination of Sn and Hg in the seafood in Yantai coastal areas,three kinds of wild shrimps and crabs were collected from three zones located in the coast in July ,2009. At the same time, seven kinds of mollusks were purchased from the local market. The concentrations of Sn and Hg in the samples were analyzed using an Agilent 7500i inductively coupled plasma-mass spectrometer (ICP-MS). The results showed that Sn and Hg concentrations in all the samples were different,with the ranges of 0.375-0.570 mg· kg -1 and 0.060-0.340 mg· kg -1 ( d.w.) and the average values of 0.470 and 0.140 mg· kg -1, respectively. For the mollusk samples, Concha ostreae was highly enriched with Sn, with the value of 0.570 mg·kg-1, while Mytilus edulis was obviously enriched with Hg,with the value of 0.340 mg·kg-1. The value of P1 was 1.13, which indicated that Mytilus edulis was seriously polluted. The concentrations of Sn and Hg in Chamys farreri and Sol sricus were the lowest, respectively. For the collected samples, the average concentrations of Sn and Hg in Oratosquilla oratoria ,Alpheus brevicristatus and Carpilius convexus in the background area were all lower than those in sewage outfall area and port area, the average concentrations of Sn were 0.520 mg·kg-1 ( port area) ,0.470 mg·kg -1 (sewage outfall area) and 0.290 mg· kg -1 ( background area ), the average concentrations of Hg were: 0.160 mg·kg -1 ( port area ),0.157 mg· kg-1 (sewage outfall area)and 0.137 mg·kg-1 (background area). Compared with other reports, the Sn level in the studied marine organisms was moderate ,but the Hg level was a little higher. However, the concentrations of Sn and Hg in the studied marine seafood were all below the limit for agriculture product safety requirements for non-environmental pollution products, except Hg in Mytilus edulis (the national standards of Sn haven't been established). The results suggested that the coastal areas studied were not significantly

  9. Microbial Oxidation of Hg(0) - Its Effect on Hg Stable Isotope Fractionation and Methylmercury Production

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Nathan [Rutgers Univ., New Brunswick, NJ (United States); Barkay, Tamar [Rutgers Univ., New Brunswick, NJ (United States); Reinfelder, John [Rutgers Univ., New Brunswick, NJ (United States)

    2016-06-28

    relationship between Hg concentrations and rates of denitrification in enrichment cultures. In part III of our project, we examined in more detail the effects of microbial interactions on Hg transformations. We discovered that both sulfate reducing and iron reducing bacteria coexist in freshwater sediments and both microbial groups contribute to mercury methylation. We showed that mercury methylation by sulfate reducing and iron reducing bacteria are temporally and spatially separated processes. We also discovered that methanogens can methylate mercury. We showed that Methanospirillum hungatei JF-1 methylated Hg at comparable rates, but with higher yields, than those observed for sulfate-reducing bacteria and iron-reducing bacteria. Finally, we demonstrated that syntrophic interactions between different microbial groups increase mercury methylation rates. We showed that Hg methylation rates are stimulated via inter-species hydrogen and acetate transfer (i) from sulfate-reducing bacteria to methanogens and (ii) from fermenters to the sulfate-reducing bacteria. In part IV of the project, we studied Hg bioavailability and Hg isotope fractionation. We demonstrated that thiol-bound Hg is bioavailable to mercury resistant bacteria. We found that uptake of Hg from Hg-glutathione and Hg-cysteine complexes does not require functioning glutathione and cystine/cysteine transport systems. We demonstrated that a wide range of methylmercury complexes (e.g. MeHgOH, MeHg-cysteine, and MeHg-glutathione) are bioavailable to mercury resistant bacteria. The rate of MeHg demethylation varies more between different species of mercury resistant bacteria than among MeHg complexes. We showed that microbial demethylation of MeHg depends more on the species of microorganism than on the types and relative concentrations of thiols or other MeHg ligands present. Finally, we demonstrated that Hg methylation by Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132 imparts mass

  10. Microbial Oxidation of Hg(0) - Its Effect on Hg Stable Isotope Fractionation and Methylmercury Production

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Nathan [Rutgers Univ., New Brunswick, NJ (United States); Barkay, Tamar [Rutgers Univ., New Brunswick, NJ (United States); Reinfelder, John [Rutgers Univ., New Brunswick, NJ (United States)

    2016-06-28

    relationship between Hg concentrations and rates of denitrification in enrichment cultures. In part III of our project, we examined in more detail the effects of microbial interactions on Hg transformations. We discovered that both sulfate reducing and iron reducing bacteria coexist in freshwater sediments and both microbial groups contribute to mercury methylation. We showed that mercury methylation by sulfate reducing and iron reducing bacteria are temporally and spatially separated processes. We also discovered that methanogens can methylate mercury. We showed that Methanospirillum hungatei JF-1 methylated Hg at comparable rates, but with higher yields, than those observed for sulfate-reducing bacteria and iron-reducing bacteria. Finally, we demonstrated that syntrophic interactions between different microbial groups increase mercury methylation rates. We showed that Hg methylation rates are stimulated via inter-species hydrogen and acetate transfer (i) from sulfate-reducing bacteria to methanogens and (ii) from fermenters to the sulfate-reducing bacteria. In part IV of the project, we studied Hg bioavailability and Hg isotope fractionation. We demonstrated that thiol-bound Hg is bioavailable to mercury resistant bacteria. We found that uptake of Hg from Hg-glutathione and Hg-cysteine complexes does not require functioning glutathione and cystine/cysteine transport systems. We demonstrated that a wide range of methylmercury complexes (e.g. MeHgOH, MeHg-cysteine, and MeHg-glutathione) are bioavailable to mercury resistant bacteria. The rate of MeHg demethylation varies more between different species of mercury resistant bacteria than among MeHg complexes. We showed that microbial demethylation of MeHg depends more on the species of microorganism than on the types and relative concentrations of thiols or other MeHg ligands present. Finally, we demonstrated that Hg methylation by Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132 imparts mass

  11. Long-distance transport of Hg, Sb, and As from a mined area, conversion of Hg to methyl-Hg, and uptake of Hg by fish on the Tiber River basin, west-central Italy

    Science.gov (United States)

    Gray, John E.; Rimondi, Valentina; Costagliola, Pilario; Vaselli, Orlando; Lattanzi, Pierfranco

    2014-01-01

    Stream sediment, stream water, and fish were collected from a broad region to evaluate downstream transport and dispersion of mercury (Hg) from inactive mines in the Monte Amiata Hg District (MAMD), Tuscany, Italy. Stream sediment samples ranged in Hg concentration from 20 to 1,900 ng/g, and only 5 of the 17 collected samples exceeded the probable effect concentration for Hg of 1,060 ng/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in Tiber River sediment varied from 0.12 to 0.52 ng/g, and although there is no established guideline for sediment methyl-Hg, these concentrations exceeded methyl-Hg in a regional baseline site (Sb (Sb) and for protection against chronic effects to aquatic wildlife (150 μg/L for As and 5.6 μg/L for Sb). Concentrations of Hg in freshwater fish muscle ranged from 0.052–0.56 μg/g (wet weight), mean of 0.17 μg/g, but only 17 % (9 of 54) exceeded the 0.30 μg/g (wet weight) USEPA fish muscle guideline recommended to protect human health. Concentrations of Hg in freshwater fish in this region generally decreased with increasing distance from the MAMD, where fish with the highest Hg concentrations were collected more proximal to the MAMD, whereas all fish collected most distal from Hg mines contained Hg below the 0.30 μg/g fish muscle guideline. Data in this study indicate some conversion of inorganic Hg to methyl-Hg and uptake of Hg in fish on the Paglia River, but less methylation of Hg and Hg uptake by freshwater fish in the larger Tiber River.

  12. Lower than expected mercury concentration in piscivorous African sharptooth catfish Clarias gariepinus (Burchell)

    Energy Technology Data Exchange (ETDEWEB)

    Desta, Zerihun [Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432, As (Norway) and Awassa University, Faculty of Natural Sciences, Department of Applied Biology, P.O. Box 5, Awassa (Ethiopia)]. E-mail: zerihun.desta@gmail.com; Borgstrom, Reidar [Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432, As (Norway); Rosseland, Bjorn Olav [Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432, As (Norway); Dadebo, Elias [Awassa University, Faculty of Natural Sciences, Department of Applied Biology, P.O. Box 5, Awassa (Ethiopia)

    2007-04-15

    The concentrations of total mercury (THg), stable isotopes of nitrogen ({delta}{sup 15}N) and carbon ({delta}{sup 13}C), and the diet of the African sharptooth catfish Clarias gariepinus in Lake Awassa, Ethiopia, were studied from January 2003 to February 2004. Values of the {delta}{sup 15}N were used as an index of trophic position in four length groups and compared to actual stomach contents. The diet of C. gariepinus within the length range of 201-600 mm L {sub T} mainly consisted of the small barb Barbus paludinosus, aquatic insects, and mollusks. The proportion of fish prey in the diet was 60% by volume, irrespective of fish size. The differences in {delta}{sup 15}N values of individuals within and between length classes were less than 3 per mille , and were not significantly related to total length, showing the similarity in trophic niche of the different sizes, which corresponded to recorded stomach contents. Mercury concentrations were in the range of 0.002-0.154 mg kg{sup -1} ww, and had no significant relationship to total length. Hence, even large specimens of C. gariepinus have Hg values below the WHO threshold of 0.2 mg kg{sup -1} ww. The slope of the regression line between log [Hg] and {delta}{sup 15}N was small, 0.06, indicating the absence of trophic shifts and biomagnification of Hg in larger specimens in our samples. The low Hg concentrations in C. gariepinus compared to the Hg concentrations in other piscivorous fish species in Lake Awassa, such as Barbus intermedius and B. paludinosus, may be due to its dependence on invertebrate preys at small size, diet switching towards low Hg prey fish at larger size, and growth biodilution owing to higher growth rate.

  13. Electron Concentration in the Near-Surface Graded-Gap Layer of MBE n-Hg1- x Cd x Te ( x = 0.22-0.40) Determined from the Capacitance Measurements of MIS-Structures

    Science.gov (United States)

    Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.; Grigor'ev, D. V.; Lyapunov, D. V.

    2017-05-01

    Capacitance-voltage (C-V) characteristics of MIS structures based on the graded-gap n-Hg1- x Cd x Te ( x = 0.22-0.40) grown by molecular-beam epitaxy were experimentally studied in the temperature range of 9-77 K. The concentrations of majority charge carriers in the near-surface layer of the semiconductor are determined from the capacitance value at the minimum of the (C-V) characteristic due to the high-frequency behavior of the capacitance characteristics of the structures with graded-gap layers with respect to the recharge time of surface states. The electron concentration in the near-surface layer of the graded-gap n-Hg1- x Cd x Te at x = 0.22-0.23 in the working layer, found from the value of the capacitance at the minimum, considerably exceeds the integral electron concentration determined by the Hall method. With an increase in the composition in the working layer to x = 0.30-0.40, the difference in the values of the electron concentrations decreases substantially for the near-surface layers with close compositions on the surface. The results obtained are explained by the appearance of additional native defects of donor type in the near-surface graded-gap layer, and this effect is most clearly manifested at large composition gradients in the graded-gap layer. The results of processing of experimental C-V characteristics are in qualitative agreement with the results of studying the electron concentration distribution over the film thickness performed by the Hall method.

  14. Trace elements concentrations (Zn, Cu, Pb, Cd, As and Hg in the Mediterranean mussel (Mytilus galloprovincialis and evaluation of mussel quality and possible human health risk from cultivated and wild sites of the southeastern Adriatic Sea, Montenegro

    Directory of Open Access Journals (Sweden)

    Jović Mihajlo

    2011-01-01

    Full Text Available The Mediterranean mussel Mytilus galloprovincialis (L was collected from the fall 2005 to the winter 2009 from the six sites on the Montenegrin coastline. Two wild samples were collected from the open sea coastline, and two cultivated and two wild were from the Boka Kotorska Bay. The mussels soft tissue was analyzed for zinc (Zn, copper (Cu, lead (Pb, cadmium (Cd, arsenic (As and total mercury (Hg. Concentrations of these metals ranged from 135.5-210 for Zn, 6.2-14.5 for Cu, 4.0-11.5 for Pb, 1.7-2.1 for Cd, 5.8-12.4 for As and 0.11-0.51 for Hg, in mg kg-1 dry weight. The metals were found to be present in the samples at different levels, but not in concentrations higher than maximum residual levels prescribed by the European Union (EU and US Food and Drug Administration (USFDA regulations for seafood. This indicates that the consumption of wild or cultivated mussels from the studied area is safe in moderate quantities.

  15. Structural studies of a bacterial tRNA(HIS guanylyltransferase (Thg1-like protein, with nucleotide in the activation and nucleotidyl transfer sites.

    Directory of Open Access Journals (Sweden)

    Samantha J Hyde

    Full Text Available All nucleotide polymerases and transferases catalyze nucleotide addition in a 5' to 3' direction. In contrast, tRNA(His guanylyltransferase (Thg1 enzymes catalyze the unusual reverse addition (3' to 5' of nucleotides to polynucleotide substrates. In eukaryotes, Thg1 enzymes use the 3'-5' addition activity to add G-1 to the 5'-end of tRNA(His, a modification required for efficient aminoacylation of the tRNA by the histidyl-tRNA synthetase. Thg1-like proteins (TLPs are found in Archaea, Bacteria, and mitochondria and are biochemically distinct from their eukaryotic Thg1 counterparts TLPs catalyze 5'-end repair of truncated tRNAs and act on a broad range of tRNA substrates instead of exhibiting strict specificity for tRNA(His. Taken together, these data suggest that TLPs function in distinct biological pathways from the tRNA(His maturation pathway, perhaps in tRNA quality control. Here we present the first crystal structure of a TLP, from the gram-positive soil bacterium Bacillus thuringiensis (BtTLP. The enzyme is a tetramer like human THG1, with which it shares substantial structural similarity. Catalysis of the 3'-5' reaction with 5'-monophosphorylated tRNA necessitates first an activation step, generating a 5'-adenylylated intermediate prior to a second nucleotidyl transfer step, in which a nucleotide is transferred to the tRNA 5'-end. Consistent with earlier characterization of human THG1, we observed distinct binding sites for the nucleotides involved in these two steps of activation and nucleotidyl transfer. A BtTLP complex with GTP reveals new interactions with the GTP nucleotide in the activation site that were not evident from the previously solved structure. Moreover, the BtTLP-ATP structure allows direct observation of ATP in the activation site for the first time. The BtTLP structural data, combined with kinetic analysis of selected variants, provide new insight into the role of key residues in the activation step.

  16. Impacts of Land Use and Hydrology on Methylmercury Concentrations in Water in Prairie Wetlands

    Science.gov (United States)

    Hall, B.; Bates, L.; van der Kamp, G.

    2010-12-01

    Prairie wetlands situated across the Great Plains of North America possess many characteristics of ecosystems that offer ideal conditions for high rates of methylmercury (MeHg) production, including unique chemical and physical characteristics and high hydrologic variation. We explored two possible factors that may influence MeHg concentrations in water from ephemeral wetlands in central Saskatchewan: the roles that fluctuating water levels and the type of land use adjacent to wetland ponds may have in controlling MeHg concentrations. We sampled 28 wetland ponds for MeHg and THg concentrations and ancillary chemical characteristics. Wetland ponds were located in areas that fell into four land use categories and two hydrology patterns. Land use groupings included lands converted to native grasslands prior to 1995, land converted to native grasslands in 2004, land cultivated using non-organic methods, and land cultivated using certified organic methods. Based on the water level data during the preceding decade (2000-2009), we were able to categorize two types of patterns in respect to water levels: “Mainly Wet”- ponds which either did not dry up at all over the course of each summer or stayed wet until October of each year and “Mainly Dry” - ponds which dried up in the earlier parts of each summer. MeHg in whole water ranged from 0.110 ng L-1 to 2.617 ng L-1. Forward stepwise multiple linear regression on data from all ponds determined sulphate and dissolved organic carbon (DOC) concentrations, as well as specific UV absorption (SUVA; a measure of DOC quality) to be significant variables predicting MeHg concentrations in whole water. We did observe differences in MeHg and %MeHg concentrations in Type III wetland ponds when data were grouped into land use categories, although the differences were generally not significant. Average whole water MeHg concentrations and %MeHg were lowest in water from ponds that have recently been converted to grasslands compared

  17. Biogeochemical analysis of ancient Pacific Cod bone suggests Hg bioaccumulation was linked to paleo sea level rise and climate change

    Directory of Open Access Journals (Sweden)

    Maribeth S. Murray

    2015-02-01

    Full Text Available Deglaciation at the end of the Pleistocene initiated major changes in ocean circulation and distribution. Within a brief geological time, large areas of land were inundated by sea-level rise and today global sea level is 120 m above its minimum stand during the last glacial maximum. This was the era of modern sea shelf formation; climate change caused coastal plain flooding and created broad continental shelves with innumerable consequences to marine and terrestrial ecosystems and human populations. In Alaska, the Bering Sea nearly doubled in size and stretches of coastline to the south were flooded, with regional variability in the timing and extent of submergence. Here we suggest how past climate change and coastal flooding are linked to mercury bioaccumulation that could have had profound impacts on past human populations and that, under conditions of continued climate warming, may have future impacts. Biogeochemical analysis of total mercury (tHg and 13C/15N ratios in the bone collagen of archaeologically recovered Pacific Cod (Gadus macrocephalus bone shows high levels of tHg during early/mid-Holocene. This pattern cannot be linked to anthropogenic activity or to food web trophic changes, but may result from natural phenomena such as increases in productivity, carbon supply and coastal flooding driven by glacial melting and sea-level rise. The coastal flooding could have led to increased methylation of Hg in newly submerged terrestrial land and vegetation. Methylmercury is bioaccumulated through aquatic food webs with attendant consequences for the health of fish and their consumers, including people. This is the first study of tHg levels in a marine species from the Gulf of Alaska to provide a time series spanning nearly the entire Holocene and we propose that past coastal flooding resulting from climate change had the potential to input significant quantities of Hg into marine food webs and subsequently to human consumers.

  18. Hg0 absorption in potassium persulfate solution

    Institute of Scientific and Technical Information of China (English)

    YE Qun-feng; WANG Cheng-yun; WANG Da-hui; SUN Guan; XU Xin-hua

    2006-01-01

    The aqueous phase oxidation of gaseous elemental mercury (Hg0) by potassium persulfate (KPS) catalyzed by Ag+was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured by cold vapor atom absorption (CVAA) and ion chromatograph (IC), respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate (SN), temperature, Hg0 concentration in the reactor inlet and tertiary butanol (TBA), free radical scavenger, on the removal efficiency of Hg0 were studied. The results showed that the removal efficiency of Hg0 increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg0 was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO3. High Hg0 concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed.

  19. 珠江入海口海产品中总汞与甲基汞含量特征及食用风险%Concentration Characteristics and Edible Risk of Total Mercury and Methylmercury in Marine Products from the Pearl River Estuary

    Institute of Scientific and Technical Information of China (English)

    高志强; 张毅强; 李杰; 陈来国; 刘明; 赵伟; 许振成

    2015-01-01

    Methylmercury is one of the bioaccumulation environmental contaminants and eating marine products is the main source to expose to methylmercury. Thus, 11 different kinds of marine products were captured from the Pearl River Estuary in spring, 2015. The concentrations of total mercury (THg) and methylmercury (MeHg) were determined using direct combustion-atomic absorption spectrometry and KOH/CH3OH digestion-gas chromatography (GC)-cold atomic fluorescence (CVAFS) to study the distribution characteristics of mercury in different kinds of marine products and to evaluate the risk of mercury exposure. The results showed that the concentrations of THg and MeHg in the marine products were 27.1μg·kg-1 to 231.4μg·kg-1 (dry weight, the same here after in this paper) and the THg ranged from 21.7μg·kg-1 to 197.0μg·kg-1 (dry weight, the same here after in this paper), and the proportion of MeHg in THg ranged from 70.2 % to 92.9%. Compared to marine products of other domestic districts, the THg and MeHg concentrations in fish of the Pearl River Estuary were significantly higher, while the THg and MeHg concentrations in shellfish presented in an intervallic way, and in crustacean were similar. The MeHg and THg concentrations in different marine products decreased as fish (152±75.1 μg·kg-1, 127±58.0 μg·kg-1) > crustacean (87.7±44.2 μg·kg-1, 63.4±34.1 μg·kg-1) > shellfish (29.7±7.2μg·kg-1, 24.3±3.2 μg·kg-1), probably because they were in different levels of the food chain. The results indicated that the concentrations of MeHg and THg in the same kinds of marine products were related to the water layer in which their preys lived, with a tendency that the fish which preyed in the lower-middle layer or bottom layer>the loligo (Loligo chinensis) which preyed in the upper-middle layer. The MeHg and THg concentrations in marine products did not exceed the maximum allowed level set by domestic or international organizations. By the consumption of marine products

  20. Facile fabrication of an electrochemical aptasensor based on magnetic electrode by using streptavidin modified magnetic beads for sensitive and specific detection of Hg(2.).

    Science.gov (United States)

    Wu, Dan; Wang, Yaoguang; Zhang, Yong; Ma, Hongmin; Pang, Xuehui; Hu, Lihua; Du, Bin; Wei, Qin

    2016-08-15

    In this work, a novel electrochemical aptasensor was developed for sensitive and specific detection of Hg(2+) based on thymine-Hg(2+)-thymine (T-Hg(2+)-T) structure via application of thionine (Th) as indicator signal. For the fabrication of the aptasensor, streptavidin modified magnetic beads (Fe3O4-SA) was firmly immobilized onto the magnetic glassy carbon electrode (MGCE) benefited from its magnetic character. Then biotin labeled T-riched single stranded DNA (Bio-ssDNA) connected with Fe3O4-SA specifically and steadily because of the specific binding capacity between streptavidin and biotin. The stable structure of T-Hg(2+)-T formed in the present of Hg(2+) provided convenience for the intercalation of Th. The detection of Hg(2+) was achieved by recording the differential pulse voltammetry (DPV) signal of Th. Under optimal experimental conditions, the linear range of the fabricated electrochemical aptasensor was 1-200nmol/L, with a detection limit of 0.33nmol/L. Furthermore, the proposed aptasensor may find a potential application for the detection of Hg(2+) in real water sample analysis.

  1. Highly Sensitive Fluorometric Hg2+ Biosensor with a Mercury(Ⅱ)-Specific Oligonucleotide (MSO) Probe and Water-Soluble Graphene Oxide (WSGO)

    Institute of Scientific and Technical Information of China (English)

    Liu Xingfen; Miao Likun; Jiang Xu; Ma Yanwen; Fan Quli; Huang Wei

    2011-01-01

    A highly sensitive and selective, "turn-on" and simple Hg2+ biosensor is reported by using water-soluble gra-phene oxide (WSGO) and dye-labeled mercury(Ⅱ)-specific oligonucleotide (MSO) probe. The probe is rich of thymine (T) and can readily form the stem-loop structure which consists of the T-Hg2+-T configuration. In the ab-sence of Hg2+, the probe exists as a random coil conformation which can be readily adsorbed on the surface of WSGO by strong noncovalent binding of bases, as a result, the fluorescence of the dye labeled on the terminus of the MSO is strongly quenched by the efficient electron/energy transfer from the dye to WSGO. Upon addition of Hg2+, the formation of the T-Hg2+-T structure releases the MSO from the surface of WSGO, resulting in a restora-tion of the fluorescence of dye-labeled MSO probe. Based on this observation, a highly sensitive and selective Hg2+ sensor is developed, which can work with "turn-on" mode in aqueous solutions at room temperature. By using the fluorometric method, the limit of detection for Hg2+ can reach picomolar range (187 pmol·L-1), and it is demonstrated that the biosensor is highly selective and only minimally perturbed by a wide range of non-specific metal ions.

  2. Chemical thermodynamics of Hg1201 and Hg1223 phases

    Science.gov (United States)

    Tsuchiya, Tetsuo; Fueki, Kazuo; Koyama, Tadashi

    1998-03-01

    The decomposition equilibrium of Hg1201 and Hg1223 was studied using a thermomicrobalance. A thermodynamic diagram representing the stability domains of Hg1201 and Hg1223 was constructed. Using the diagram, it was shown that Hg1201 is metastable at 800°C and that Hg1223 is stable at 660°C due to the formation of an atmosphere of mercury vapor and oxygen formed by the decomposition of excess HgO. Chemical analysis revealed that the valence of Hg is +2 regardless of the oxygen content. The dependence of Tc on the oxygen content was also studied.

  3. Mercury concentrations in lean fish from the Western Mediterranean Sea: Dietary exposure and risk assessment in the population of the Balearic Islands.

    Science.gov (United States)

    Llull, Rosa Maria; Garí, Mercè; Canals, Miquel; Rey-Maquieira, Teresa; Grimalt, Joan O

    2017-10-01

    The present study reports total mercury (THg) and methylmercury (MeHg) concentrations in 32 different lean fish species from the Western Mediterranean Sea, with a special focus on the Balearic Islands. The concentrations of THg ranged between 0.05mg/kg ww and 3.1mg/kg ww (mean 0.41mg/kg ww). A considerable number of the most frequently fish species consumed by the Spanish population exceed the maximum levels proposed by the European legislation when they originate from the Mediterranean Sea, such as dusky grouper (100% of the examined specimens), common dentex (65%), conger (45%), common sole (38%), hake (26%) and angler (15%), among others. The estimated weekly intakes (EWI) in children (7-12 years of age) and adults from the Spanish population (2.7µg/kg bw and 2.1µg/kg bw, respectively) for population only consuming Mediterranean fish were below the provisional tolerable weekly intake (PTWI) of THg established by EFSA in 2012, 4µg/kg bw. However, the equivalent estimations for methylmercury, involving PTWI of 1.3µg/kg bw, were two times higher in children and above 50% in adults. For hake, sole, angler and dusky grouper, the most frequently consumed fish, the estimated weekly intakes in both children and adults were below the maximum levels accepted. These intakes correspond to maximum potential estimations because fish from non-Mediterranean origin is often consumed by the Spanish population including the one from the Balearic Islands. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Human hair mercury levels in the Wanshan mercury mining area, Guizhou Province, China.

    Science.gov (United States)

    Li, Ping; Feng, Xinbin; Qiu, Guangle; Shang, Lihai; Li, Guanghui

    2009-12-01

    The total mercury (T-Hg) and methyl mercury (Me-Hg) concentrations in the hair were measured to evaluate mercury (Hg) exposure for the residents in Da-shui-xi Village (DSX) and Xia-chang-xi Village (XCX) in the Wanshan Hg mining area, Guizhou Province, Southwestern China. The mean concentrations in the hair of DSX residents were 5.5 ± 2.7 μg/g and 1.9 ± 0.9 μg/g for T-Hg and Me-Hg, respectively. The concentrations in the hair of XCX residents were 3.3 ± 1.4 μg/g and 1.2 ± 0.5 μg/g for T-Hg and Me-Hg, respectively. Hair Me-Hg concentrations were significantly correlated to T-Hg (r = 0.42, P < 0.01) in the two sites; on average, hair Me-Hg concentration accounted for 40 and 44% of T-Hg for DSX and XCX residents, respectively. Age has no obvious correlation with hair Hg and the hair Hg levels showed a significant gender difference, with higher T-Hg and Me-Hg concentrations in the hair from males than females. The rice collected from the two sites showed high levels of T-Hg and Me-Hg concentration. The results indicated a certain Hg exposure for the residents in DSX and XCX in the Wanshan Hg mining area.

  5. Results Of Hg Speciation Testing On DWPF SMECT-1, SMECT-3, And SMECT-5 Samples

    Energy Technology Data Exchange (ETDEWEB)

    Bannochie, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-01-07

    The Savannah River National Laboratory (SRNL) was tasked with preparing and shipping samples for Hg speciation by Eurofins Frontier Global Sciences, Inc. in Seattle, WA on behalf of the Savannah River Remediation (SRR) Mercury Task Team. The thirteenth shipment of samples was designated to include Defense Waste Processing Facility (DWPF) Slurry Mix Evaporator Condensate Tank (SMECT) from Sludge Receipt and Adjustment Tank (SRAT) Batch 736 and 738 samples. Triplicate samples of each material were prepared for this shipment. Each replicate was analyzed for seven Hg species: total Hg, total soluble (dissolved) Hg, elemental Hg [Hg(0)], ionic (inorganic) Hg [Hg(I) and Hg(II)], methyl Hg [CH3Hg-X, where X is a counter anion], ethyl Hg [CH3CH2-Hg-X, where X is a counter anion], and dimethyl Hg [(CH3)2Hg]. The difference between the total Hg and total soluble Hg measurements gives the particulate Hg concentration, i.e. Hg adsorbed to the surface of particulate matter in the sample but without resolution of the specific adsorbed species. The average concentrations of Hg species in the aqueous samples derived from Eurofins reported data corrected for dilutions performed by SRNL are tabulated.

  6. N-doped TiO2 based visible light activated label-free photoelectrochemical biosensor for detection of Hg(2+) through quenching of photogenerated electrons.

    Science.gov (United States)

    Han, Qianqian; Wang, Kewei; Xu, Lijun; Yan, Xiang; Zhang, Kunchi; Chen, Xing; Wang, Qinglin; Zhang, Lan; Pei, Renjun

    2015-06-21

    A novel photoelectrochemical (PEC) biosensor was fabricated based on N-doped TiO2 for the detection of Hg(2+) through the quenching of photogenerated electrons. The N-doped TiO2 was synthesized by a sol-gel method with urea and tetrabutyl titanate as the N and Ti sources. Compared with the undoped TiO2, the N-doped TiO2 showed an enhanced photocurrent response under visible light (λ > 420 nm). The sensing surface was functionalized with 5'-amino-modified T-rich oligonucleotides. The photoelectrochemical biosensor bound Hg(2+) on the surface by a highly specific T-Hg(2+)-T recognition. Hg(2+) on the surface of the N-doped TiO2 film withdrew the photogenerated electrons and decreased the recorded current signal. The dynamic linear range for Hg(2+) has been determined to be as low as 2-6 μM.

  7. The interaction rainfall vs. weight as determinant of total mercury concentration in fish from a tropical estuary.

    Science.gov (United States)

    Barletta, M; Lucena, L R R; Costa, M F; Barbosa-Cintra, S C T; Cysneiros, F J A

    2012-08-01

    Mercury loads in tropical estuaries are largely controlled by the rainfall regime that may cause biodilution due to increased amounts of organic matter (both live and non-living) in the system. Top predators, as Trichiurus lepturus, reflect the changing mercury bioavailability situations in their muscle tissues. In this work two variables [fish weight (g) and monthly total rainfall (mm)] are presented as being important predictors of total mercury concentration (T-Hg) in fish muscle. These important explanatory variables were identified by a Weibull Regression model, which best fit the dataset. A predictive model using readily available variables as rainfall is important, and can be applied for human and ecological health assessments and decisions. The main contribution will be to further protect vulnerable groups as pregnant women and children. Nature conservation directives could also improve by considering monitoring sample designs that include this hypothesis, helping to establish complete and detailed mercury contamination scenarios.

  8. Thymine rich-DNA sensing probe for Hg2+detection%富含胸腺嘧啶DNA传感探针对水体中Hg2+的检测

    Institute of Scientific and Technical Information of China (English)

    肖慧; 杨婵; 赵珍; 家意; 刘凤; 周银香徐思嘉; 许庭琦; 何婧琳; 曹忠

    2015-01-01

    Mercury is one of the most toxic heavy metals that present in environment. Therefore, a sensitive and se-lective sensing system for mercury detection is highly demanded. This paper described a fluorescent sensor using a label free Hg2+specific DNA probe(43mer-T18Stem) and an intercalation dye SYBR Green I(SG). As is known to all, Hg2+can specifically interact with thymine base to form strong and stable thymine-Hg2+-thymine (T-Hg2+-T) com-plexes. This specific T-Hg2+-T formation affected the hybridization of the Hg2+specific probe and the intercalation of SG. The proposed sensor showed a linear response in the range of 4.000×10-7~2.000×10-6 mol/L of Hg2+with a detec-tion limit of 3.900×10-8 mol/L. The sensor revealed good recovery rates from 98.72%to 102.8%, indicating that the sensing system can be utilized for the determination of Hg2+in real samples.%该工作以富含大量胸腺嘧啶(Thymine,T)核酸单链为识别分子,SYBR Green I (SG)为荧光基团,建立了一种简单、灵敏的荧光增强法检测Hg2+。由于T-Hg2+-T键的形成,富T单链自我折叠或者两两配对形成双链DNA结构,当溶液中的SG嵌入DNA双链中时,SG荧光强度显著增强。实验结果表明,SG荧光强度随着Hg2+浓度的增加而增加。在最优实验条件下,SG的荧光强度与Hg2+的浓度在4.000×10-7~2.000×10-6 mol/L范围内呈线性关系,检出限为3.900×10-8 mol/L。该方法在含5.0%湘江水实际样品中获得的回收率为98.72%~104.5%,因此该传感器可用于实际湘江水样品中Hg2+的测量。

  9. Mercury pollution in fish from South China Sea: levels, species-specific accumulation, and possible sources.

    Science.gov (United States)

    Liu, Jinling; Xu, Xiangrong; Yu, Shen; Cheng, Hefa; Hong, Yiguo; Feng, Xinbin

    2014-05-01

    Both total mercury (THg) and methylmercury (MeHg) levels in fish collected from South China Sea (SCS) were studied to understand Hg pollution in Chinese tropical marine ecosystems. The average THg concentrations in fish species ranged from 39.6 μg/kg for rabbitfish (Siganus fuscessens) to 417 μg/kg for thornfish (Terapon jarbua), while those of MeHg varied from 13 μg/kg (rabbitfish) to 176 μg/kg (thornfish). The median values of MeHg/THg ratios in different fish species ranged from 36 to 85%. Significant inter-species differences of THg and MeHg in fish were observed due to feeding habits and fish sizes. Overall, carnivorous fish had higher levels of THg, MeHg and MeHg/THg ratios than omnivorous and herbivorous fish. High Hg levels in fish of the SCS were probably related to Hg input from atmospheric deposition and anthropogenic activities.

  10. Determination of As,Hg,Cd,Pb and Bi in gold concentrates by AFS%原子荧光光谱法测定金精矿中的砷汞镉铅铋

    Institute of Scientific and Technical Information of China (English)

    王菊; 陈永红; 苏广东; 孟宪伟; 王立臣

    2015-01-01

    研究建立了采用原子荧光光谱仪测定金精矿中砷、汞、镉、铅、铋的方法。通过对比实验选择了水浴溶样法作为砷、汞、铋的预处理方法,选择了盐酸、硝酸、高氯酸和氢氟酸混酸溶样法作为砷、铋、镉、铅的预处理方法。经过条件实验分别确定了两种预处理方法的最小称样量、试剂用量、水浴溶样法溶样时间、混酸溶样法定容介质酸度等最佳实验条件。该方法加入标准物质回收率为92.54%~125.10%,精密度(RSD,n=11)均小于10%,准确度小于8%。%The paper established a determination method of As,Hg,Cd,Pb and Bi in gold concentrates by AFS. Contrast test chose water bath dissolution as the pretreatment method of As,Hg and Bi,and the mixed acids dissolution with hydrochloric acid,nitric acid,perchloric acid and hydrofluoric acid for the pretreatment of As,Cd,Pb and Bi. Conditional experiments settled such optimal conditions as the minimum test portion weight,agent dosage,time for wa-ter bath dissolution and constant volume medium acidity respectively for the two pretreatment methods.The recovery rate with addition of standard substance is 92.54 % to 125.10 %,the precision rate(RSD,n=11) is less than 10%,and accuracy is less than 8 %.

  11. Uptake of HgCl{sub 2} and MeHgCl in an insect cell line (Aedes albopictus C6/36)

    Energy Technology Data Exchange (ETDEWEB)

    Braeckman, B.; Cornelis, R.; Rzeznik, U.; Raes, H. [Univ. of Ghent (Belgium)

    1998-10-01

    The authors studied the uptake mechanism of mercuric chloride (Hg) and methylmercuric chloride (MeHg) in Aedes albopictus C6/36 cells. The uptake kinetics, together with the effect of temperature and a metabolic inhibitor (2,4-dinitrophenol) on the mercury accumulation, were examined. Both amounts of internalized Hg and MeHg increased linearly with the extracellular concentration. Initially, the influx rate was high for both metal species but MeHg was found to accumulate seven times faster than Hg. At longer exposure times it leveled off for Hg, while for MeHg, the intracellular concentration decreased. Hg toxicity was not significantly influenced by elevated temperatures; in contrast there was a marked decrease of the LC{sub 50/24 h} value for MeHg. On the other hand, Hg accumulation was temperature dependent but MeHg was not. The different toxicity and uptake rate of both mercury compounds can be explained in terms of membrane permeability and target site. For Hg the main target seems to be the plasma membrane, while MeHg readily crosses this barrier and reacts with intracellular targets. 2,4-Dinitrophenol had no effect on the accumulation of Hg but that of MeHg was doubled.

  12. Mercury accumulation in marine bivalves: Influences of biodynamics and feeding niche

    Energy Technology Data Exchange (ETDEWEB)

    Pan Ke [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong); Wang Wenxiong, E-mail: wwang@ust.hk [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong)

    2011-10-15

    Differences in the accumulation of mercury (Hg) in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, oysters Saccostrea cucullata, green mussels Perna viridis, and black mussels Septifer virgatus, were investigated. The bivalves displayed different patterns of Hg accumulation in terms of the body concentrations of methylmercury (MeHg) and total Hg (THg), as well as the ratio of MeHg to THg. Parameters of the biodynamics of the accumulation of Hg(II) and MeHg could reflect the species-dependent Hg concentrations in the bivalves. With the exception of black mussels, we found a significant relationship between the efflux rates of Hg(II) and the THg concentrations in the bivalves. The interspecific variations in the MeHg to THg ratio were largely controlled by the relative difference between the elimination rates of Hg(II) and MeHg. Stable isotope ({delta}{sup 13}C) analysis indicated that the five bivalve species had contrasting feeding niches, which may also affect the Hg accumulation. - Highlights: > Significant difference in Hg accumulation and MeHg:THg ratio in different bivalves. > THg concentrations in the bivalves were generally related to the efflux rates of Hg(II). > Elimination of Hg(II) and MeHg controlled the interspecific variation in MeHg:THg ratio. > MeHg and THg concentrations reflect the interaction of Hg biodynamics and food. - The species-specific body concentrations of MeHg and THg in bivalves reflect the complicated interaction between the biodynamics of Hg(II) and MeHg and the different food sources.

  13. HgZnTe-based detectors for LWIR NASA applications

    Science.gov (United States)

    Patten, Elizabeth A.; Kalisher, Murray H.

    1990-01-01

    The initial goal was to grow and characterize HgZnTe and determine if it indeed had the advantageous properties that were predicted. Researchers grew both bulk and liquid phase epitaxial HgZnTe. It was determined that HgZnTe had the following properties: (1) microhardness at least 50 percent greater than HgCdTe of equivalent bandgap; (2) Hg annealing rates of at least 2 to 4 times longer than HgCdTe; and (3) higher Hg vacancy formation energies. This early work did not focus on one specific composition (x-value) of HgZnTe since NASA was interested in HgZnTe's potential for a variety of applications. Since the beginning of 1989, researchers have been concentrating, however, on the liquid phase growth of very long wavelength infrared (VLWIR) HgZnTe (cutoff approx. equals 17 microns at 65K) to address the requirements of the Earth Observing System (EOS). Since there are no device models to predict the advantages in reliability one can gain with increased microhardness, surface stability, etc., one must fabricate HgZnTe detectors and assess their relative bake stability (accelerated life test behavior) compared with HgCdTe devices fabricated in the same manner. Researchers chose to fabricate HIT detectors as a development vehicle for this program because high performance in the VLWIR has been demonstrated with HgCdTe HIT detectors and the HgCdTe HIT process should be applicable to HgZnTe. HIT detectors have a significant advantage for satellite applications since these devices dissipate much less power than conventional photoconductors to achieve the same responsivity.

  14. Hg-Mask Coronagraph

    Science.gov (United States)

    Bourget, P.; Veiga, C. H.; Vieira Martins, R.; Assus, P.; Colas, F.

    In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).

  15. Bioindication of volcanic mercury (Hg) deposition around Mt Etna (Sicily)

    Science.gov (United States)

    Martin, R.; Witt, M. L.; Sawyer, G. M.; Watt, S.; Bagnato, E.; Calabrese, S.; Aiuppa, A.; Delmelle, P.; Pyle, D. M.; Mather, T. A.

    2012-12-01

    Mt. Etna is a major natural source of Hg to the Mediterranean region. Total mercury concentrations, [Hg]tot, in Castanea sativa (sweet chestnut) leaves sampled 7-13 km from Etna's vents (during six campaigns in 2005-2011) were determined using atomic absorption spectroscopy. [Hg]tot in C. sativa was greatest on Etna's SE flank reflecting Hg deposition from the typically overhead volcanic plume. When adjusted for leaf age, [Hg]tot in C. sativa also increased with recent eruptive activity. [Hg]tot in C. sativa was not controlled by [Hg]tot in soils, which instead was greatest on the (upwind) NW flank and correlated strongly with soil organic matter (% Org). Our results suggest that at least ~1% of Hg emitted from Etna is deposited proximally, supporting recent measurement and model results which indicate that GEM (Hg0; the dominant form of Hg in high temperature magmatic gases) is oxidised rapidly to RGM and Hgp in ambient temperature volcanic plumes. Samples of C. sativa and soils were also collected in July and September 2012 alongside SO2 and acid gas diffusion tube samples. These new samples will enable us to investigate Hg accumulation over a single growth season with reference to the exposure of vegetation to volcanic gases and particles.

  16. Mercury accumulation in periphyton of eight river ecosystems

    Science.gov (United States)

    Bell, A.H.; Scudder, B.C.

    2007-01-01

    In 2003, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program and U.S. Environmental Protection Agency studied total mercury (THg) and methylmercury (MeHg) concentrations in periphyton at eight rivers in the United States in coordination with a larger USGS study on mercury cycling in rivers. Periphyton samples were collected using trace element clean techniques and NAWQA sampling protocols in spring and fall from targeted habitats (streambed surface-sediment, cobble, or woody snags) at each river site. A positive correlation was observed between concentrations of THg and MeHg in periphyton (r2 = 0.88, in log-log space). Mean MeHg and THg concentrations in surface-sediment periphyton were significantly higher (1,333 ng/m2 for MeHg and 53,980 ng/m2 for THg) than cobble (64 ng/m2 for MeHg and 1,192 ng/m2 for THg) or woody snag (71 ng/m2 for MeHg and 1,089 ng/m2 for THg) periphyton. Concentrations of THg in surface-sediment periphyton had a strong positive correlation with concentrations of THg in sediment (dry weight). The ratio of MeHg:THg in surface-sediment periphyton increased with the ratio of MeHg:THg in sediment. These data suggest periphyton may play a key role in mercury bioaccumulation in river ecosystems. ?? 2007 American Water Resources Association.

  17. Hg/HgO electrode and hydrogen evolution potentials in aqueous sodium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, Ryan A.; Zhu, Wenhua H.; Payne, Robert U.; Cahela, Donald R.; Tatarchuk, Bruce J. [Center for Microfibrous Materials Manufacturing, Department of Chemical Engineering, 230 Ross Hall, Auburn University, Auburn, AL 36849 (United States)

    2006-10-27

    The Hg/HgO electrode is usually utilized as a reference electrode in alkaline solution such as for development of an alkaline hydrogen electrode. The reference electrode provides a suitable reference point but is available from few commercial vendors and suffers from inadequate documentation on potential in varying electrolytes. A new numerical method uses activity, activity coefficients, and a few correlated empirical equations to determine the potential values in both dilute and concentrated sodium hydroxide solutions at temperatures of 0-90{sup o}C and at concentrations of 0.100-12.8mol kg{sub H{sub 2}O}{sup -1}. The computed potentials of the Hg/HgO electrodes versus a normal hydrogen electrode (NHE) at 25{sup o}C and 1atm are 0.1634V for 0.100m, 0.1077V for 1.00m, and 0.0976V for 1.45m NaOH solutions. The Hg/HgO reduction potential further changes to -0.0751V versus NHE and hydrogen evolution potential changes to -0.9916V versus NHE in a solution of 30.0wt.% NaOH at 80{sup o}C. The calculated values are compared with the measured data at 25 and 75{sup o}C. The experimental data agree well with the numerical values computed from the theoretical and empirical equations. (author)

  18. Hg/HgO electrode and hydrogen evolution potentials in aqueous sodium hydroxide

    Science.gov (United States)

    Nickell, Ryan A.; Zhu, Wenhua H.; Payne, Robert U.; Cahela, Donald R.; Tatarchuk, Bruce J.

    The Hg/HgO electrode is usually utilized as a reference electrode in alkaline solution such as for development of an alkaline hydrogen electrode. The reference electrode provides a suitable reference point but is available from few commercial vendors and suffers from inadequate documentation on potential in varying electrolytes. A new numerical method uses activity, activity coefficients, and a few correlated empirical equations to determine the potential values in both dilute and concentrated sodium hydroxide solutions at temperatures of 0-90 °C and at concentrations of 0.100-12.8 mol k gH2O-1 . The computed potentials of the Hg/HgO electrodes versus a normal hydrogen electrode (NHE) at 25 °C and 1 atm are 0.1634 V for 0.100m, 0.1077 V for 1.00m, and 0.0976 V for 1.45m NaOH solutions. The Hg/HgO reduction potential further changes to -0.0751 V versus NHE and hydrogen evolution potential changes to -0.9916 V versus NHE in a solution of 30.0 wt.% NaOH at 80 °C. The calculated values are compared with the measured data at 25 and 75 °C. The experimental data agree well with the numerical values computed from the theoretical and empirical equations.

  19. Mercury methylation in paddy soil: source and distribution of mercury species at a Hg mining area, Guizhou Province, China

    Science.gov (United States)

    Zhao, Lei; Anderson, Christopher W. N.; Qiu, Guangle; Meng, Bo; Wang, Dingyong; Feng, Xinbin

    2016-04-01

    Rice paddy plantation is the dominant agricultural land use throughout Asia. Rice paddy fields have been identified as important sites for methylmercury (MeHg) production in the terrestrial ecosystem and a primary pathway of MeHg exposure to humans in mercury (Hg) mining areas. We compared the source and distribution of Hg species in different compartments of the rice paddy during a complete rice-growing season at two different typical Hg-contaminated mining sites in Guizhou province, China: an abandoned site with a high Hg concentration in soil but a low concentration in the atmosphere and a current-day artisanal site with a low concentration in soil but a high concentration in the atmosphere. Our results showed that the flux of new Hg to the ecosystem from irrigation and atmospheric deposition was insignificant relative to the pool of old Hg in soil; the dominant source of MeHg to paddy soil is in situ methylation of inorganic Hg (IHg). Elevated MeHg concentrations and the high proportion of Hg as MeHg in paddy water and the surface soil layer at the artisanal site demonstrated active Hg methylation at this site only. We propose that the in situ production of MeHg in paddy water and surface soil is dependent on elevated Hg in the atmosphere and the consequential deposition of new Hg into a low-pH anoxic geochemical system. The absence of depth-dependent variability in the MeHg concentration in soil cores collected from the abandoned Hg mining site, consistent with the low concentration of Hg in the atmosphere and high pH of the paddy water and irrigation water, suggested that net production of MeHg at this site was limited. We propose that the concentration of Hg in ambient air is an indicator for the risk of MeHg accumulation in paddy rice.

  20. Tracing anthropogenic Hg and Pb input using stable Hg and Pb isotope ratios in sediments of the central Portuguese Margin

    NARCIS (Netherlands)

    Mil-Holmens, M.; Blum, J.; Canário, J.; Caetano, M.; Costa, A.M.; Lebreiro, S.M.; Trancoso, M.; Richter, T.O.; de Stigter, H.; Johnson, M.; Branco, V.; Cesário, R.; Mouro, F.; Mateus, M.; Boer, W.; Melo, Z.

    2013-01-01

    Three short marine sediment cores from the Cascais Submarine Canyon (CSC; cores 252-32 and 252-35) and the Estremadura Spur (core 252-16) on the central Portuguese Margin were analysed for Hg, Pb, Al, and Mn concentrations, and both Pb and Hg stable isotope compositions, in order to reconstruct tren

  1. Novel thymine-functionalized MIL-101 prepared by post-synthesis and enhanced removal of Hg(2+) from water.

    Science.gov (United States)

    Luo, Xubiao; Shen, Tingting; Ding, Lin; Zhong, Weiping; Luo, Jianfeng; Luo, Shenglian

    2016-04-05

    A novel thymine-functionalized MIL-101 (MIL-101-Thymine) material was synthesized using a post-synthesis method to remove mercury at a high efficiency. MIL-101-Thymine was successfully prepared in this work and was confirmed by several characterization methods, such as (13)C nuclear magnetic resonance, X-ray diffraction, and infrared spectroscopy. The Hg(2+) adsorption agreed well with the Langmuir model, and the maximum adsorption capacity was 51.27mg/g. The adsorption rate fit with the pseudo-second-order kinetic model. Furthermore, MIL-101-Thymine exhibited excellent selectivity towards Hg(2+) over other cations, and the maximum value of the selective coefficient reached 947.34; this result is very likely due to the highly selective interactions of T-Hg(2+)-T in MIL-101-Thymine. The result of X-ray photoelectron spectroscopy also showed that Hg(2+) was coordinated with the N of thymine in MIL-101-Thymine. Moreover, the results of the thermogravimetric analysis and adsorption experiments showed that the Hg atom was two-coordinated with the thymine group. MIL-101-Thymine was used to remove trace Hg(2+) in real water samples, and satisfactory recoveries were obtained.

  2. Simple analysis of total mercury and methylmercury in seafood using heating vaporization atomic absorption spectrometry.

    Science.gov (United States)

    Yoshimoto, Keisuke; Anh, Hoang Thi Van; Yamamoto, Atsushi; Koriyama, Chihaya; Ishibashi, Yasuhiro; Tabata, Masaaki; Nakano, Atsuhiro; Yamamoto, Megumi

    2016-01-01

    This study aimed to develop a simpler method for determining total mercury (T-Hg) and methylmercury (MeHg) in biological samples by using methyl isobutyl ketone (MIBK) in the degreasing step. The fat in the samples was extracted by MIBK to the upper phase. T-Hg transferred into the water phase. This was followed by the extraction of MeHg from the water phase using HBr, CuCl2 and toluene. The MeHg fraction was reverse-extracted into L-cysteine-sodium acetate solution from toluene. The concentrations of T-Hg and MeHg were determined by heating vaporization atomic absorption spectrometry. Certified reference materials for T-Hg and MeHg in hair and fish were accurately measured using this method. This method was then applied to determine T-Hg and MeHg concentrations in the muscle, liver and gonads of seafood for the risk assessment of MeHg exposure. The mean T-Hg and MeHg concentrations in squid eggs were 0.023 and 0.022 µg/g, and in squid nidamental glands 0.052 and 0.049 µg/g, respectively. The MeHg/T-Hg ratios in the eggs and nidamental glands of squid were 94.4% and 96.5%, respectively. The mean T-Hg and MeHg concentrations in the gonads of sea urchins were 0.043 and 0.001 µg/g, respectively, with a MeHg/T-Hg ratio of 3.5%. We developed an efficient analytical method for T-Hg and MeHg using MIBK in the degreasing step. The new information on MeHg concentration and MeHg/T-Hg ratios in the egg or nidamental glands of squid and gonads of sea urchin will also be useful for risk assessment of mercury in seafood.

  3. Removal of Hg~0 with sodium chlorite solution and mass transfer reaction kinetics

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The absorption behavior of Hg0 was studied experimentally by using sodium chlorite solution(NaClO2) as the absorbent in a bubble reactor.Primary influencing factors on removal efficiency of Hg0 such as NaClO2 concentration,pH,reaction temperature and the concentration of Hg0 were investigated.The results indicated that 72.91% of Hg0 removal efficiency could be achieved in acidic NaClO2 solution.The removal mechanism of Hg0 was proposed by analyzing of Hg2+ concentration in ab-sorption solution after reaction and comparing the electrode potentials between NaClO2 species and Hg2+/Hg0.The experimental results of mass transfer-reaction kinetics on oxidation of Hg0 by NaClO2 solution showed that with the increase of NaClO2 concentration and the decrease of pH value,the enhancement factor(E) and ratio of KG(Hg0)/kG(Hg0) increased and the liquid phase mass transfer resistance decreased,which is benefit to the mass transfer adsorption reaction.Although the increase of reaction temperature could improve the enhancement factor(E),but the ratio of KG(Hg0)/kG(Hg0) decreased;as a result,the liquid phase mass transfer resistance increased,therefore,the reaction rate for removal of Hg0 decreased.

  4. Maternal-fetal distribution of mercury ( sup 203 Hg) released from dental amalgam fillings

    Energy Technology Data Exchange (ETDEWEB)

    Vimy, M.J.; Takahashi, Y.; Lorscheider, F.L. (Univ. of Calgary, Alberta (Canada))

    1990-04-01

    In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.

  5. Enrichment of Pb, Hg and Cr in cultured carp otolith

    African Journals Online (AJOL)

    AJL

    2012-01-26

    Jan 26, 2012 ... record the pollution condition at the sampling time. ... aquatic organisms are aquatic algae, zooplankton .... element cannot show that Hg concentration in otolith ..... from Atlantic croaker along an estuarine pollution gradient.

  6. tRNA[superscript His] guanylyltransferase (THG1), a unique 3;#8242;-5;#8242; nucleotidyl transferase, shares unexpected structural homology with canonical 5;#8242;-3;#8242; DNA polymerases

    Energy Technology Data Exchange (ETDEWEB)

    Hyde, Samantha J.; Eckenroth, Brian E.; Smith, Brian A.; Eberley, William A.; Heintz, Nicholas H.; Jackman, Jane E.; Doublié, Sylvie (OSU); (Vermont)

    2011-11-07

    All known DNA and RNA polymerases catalyze the formation of phosphodiester bonds in a 5' to 3' direction, suggesting this property is a fundamental feature of maintaining and dispersing genetic information. The tRNA{sup His} guanylyltransferase (Thg1) is a member of a unique enzyme family whose members catalyze an unprecedented reaction in biology: 3'-5' addition of nucleotides to nucleic acid substrates. The 2.3-{angstrom} crystal structure of human THG1 (hTHG1) reported here shows that, despite the lack of sequence similarity, hTHG1 shares unexpected structural homology with canonical 5'-3' DNA polymerases and adenylyl/guanylyl cyclases, two enzyme families known to use a two-metal-ion mechanism for catalysis. The ability of the same structural architecture to catalyze both 5'-3' and 3'-5' reactions raises important questions concerning selection of the 5'-3' mechanism during the evolution of nucleotide polymerases.

  7. Modeling interactions of Hg(II) and bauxitic soils.

    Science.gov (United States)

    Weerasooriya, Rohan; Tobschall, Heinz J; Bandara, Atula

    2007-11-01

    The adsorptive interactions of Hg(II) with gibbsite-rich soils (hereafter SOIL-g) were modeled by 1-pK surface complexation theory using charge distribution multi-site ion competition model (CD MUSIC) incorporating basic Stern layer model (BSM) to account for electrostatic effects. The model calibrations were performed for the experimental data of synthetic gibbsite-Hg(II) adsorption. When [NaNO(3)] > or = 0.01M, the Hg(II) adsorption density values, of gibbsite, Gamma(Hg(II)), showed a negligible variation with ionic strength. However, Gamma(Hg(II)) values show a marked variation with the [Cl(-)]. When [Cl(-)] > or = 0.01M, the Gamma(Hg(II)) values showed a significant reduction with the pH. The Hg(II) adsorption behavior in NaNO(3) was modeled assuming homogeneous solid surface. The introduction of high affinity sites, i.e., >Al(s)OH at a low concentration (typically about 0.045 sites nm(-2)) is required to model Hg(II) adsorption in NaCl. According to IR spectroscopic data, the bauxitic soil (SOIL-g) is characterized by gibbsite and bayerite. These mineral phases were not treated discretely in modeling of Hg(II) and soil interactions. The CD MUSIC/BSM model combination can be used to model Hg(II) adsorption on bauxitic soil. The role of organic matter seems to play a role on Hg(II) binding when pH>8. The Hg(II) adsorption in the presence of excess Cl(-) ions required the selection of high affinity sites in modeling.

  8. Ultrasensitive electrochemical sensor for Hg(2+) by using hybridization chain reaction coupled with Ag@Au core-shell nanoparticles.

    Science.gov (United States)

    Li, Zongbing; Miao, Xiangmin; Xing, Ke; Peng, Xue; Zhu, Aihua; Ling, Liansheng

    2016-06-15

    A novel electrochemical biosensor for Hg(2+) detection was reported by using DNA-based hybridization chain reaction (HCR) coupled with positively charged Ag@Au core-shell nanoparticles ((+)Ag@Au CSNPs) amplification. To construct the sensor, capture probe (CP ) was firstly immobilized onto the surface of glass carbon electrode (GCE). In the presence of Hg(2+), the sandwiched complex can be formed between the immobilized CP on the electrode surface and the detection probe (DP) modified on the gold nanoparticles (AuNPs) based on T-Hg(2+)-T coordination chemistry. The carried DP then opened two ferrocene (Fc) modified hairpin DNA (H1 and H2) in sequence and propagated the happen of HCR to form a nicked double-helix. Numerous Fc molecules were formed on the neighboring probe and produced an obvious electrochemical signal. Moreover, (+)Ag@Au CSNPs were assembly onto such dsDNA polymers as electrochemical signal enhancer. Under optimal conditions, such sensor presents good electrochemical responses for Hg(2+) detection with a detection limit of 3.6 pM. Importantly, the methodology has high selectivity for Hg(2+) detection.

  9. Mercury accumulation in Yellowfin tuna (Thunnus albacares) with regards to muscle type, muscle position and fish size.

    Science.gov (United States)

    Bosch, Adina C; O'Neill, Bernadette; Sigge, Gunnar O; Kerwath, Sven E; Hoffman, Louwrens C

    2016-01-01

    The concentrations and relationships between individual mercury species and total mercury were investigated in different muscle parts and sizes of Yellowfin tuna (Thunnus albacares). Fourteen Yellowfin tuna caught in the South Atlantic off the coast of South Africa had an average total Hg (tHg) concentration of 0.77 mg/kg wet weight. No differences were detected (p > 0.05) in tHg, MethylHg (MeHg) or inorganic Hg (iHg) accumulation among the four white muscle portions across the carcass, but both tHg and iHg were found in higher concentrations (p < 0.001) in dark muscle than white muscle. Positive linear correlations with fish weight were found for both tHg (r = 0.79, p < 0.001) and MeHg (r = 0.75, p < 0.001) concentrations. A prediction model was formulated to calculate toxic MeHg concentrations from measured tHg concentrations and fish weight (cMeHg = 0.073 + 1.365 · tHg-0.008 · w). As sampling sites and subsampling methods could affect toxicity measurements, we provide recommendations for sampling guidelines.

  10. The Upside to Hg-DOM Associations for Water Quality: Removal of Hg from Solution Using Coagulaion with Metal-Based Salts

    Science.gov (United States)

    Henneberry, Y.; Kraus, T. E.; Fleck, J.; Krabbenhoft, D. P.; Horwath, W. R.

    2011-12-01

    This study assessed the potential use of metal-based coagulants to remove dissolved mercury (Hg) from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however those studies used high concentrations of Hg, which did not reflect naturally occurring concentrations of Hg. Filtered water collected from an agricultural drain in the Sacramento-San Joaquin Delta (Delta) was treated with three industrial-grade coagulants (ferric chloride, ferric sulfate, and polyaluminum chloride) to determine their efficacy in removing both inroganic (IHg) and methylmercury (MeHg) from the water column. The Delta suffers from elevated surface water Hg concentrations and as a result is listed as an imparied water body. Coagulants removed up to 85% of DOM from solution. In the absence of DOM, all three coagulants released IHg into solution, however in the presence of DOM the coagulants removed up to 97% of IHg and 80% of MeHg. Results suggest that the removal of Hg is mediated by DOM-coagulant interactions. There was a preferential association of IHg with the more aromatic, higher molecular weight fraction of DOM but no such relationship was found for MeHg. This study offers new fundamental insights regarding large-scale removal of Hg at environmentally relevant concentrations. Research using isotopically labeled Hg is providing insight into whether coagulation can remove recently added Hg (e.g. atmospheric deposition) from solution and whether once formed, the floc can remove additional Hg from the water column.

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

    Science.gov (United States)

    Ukonmaanaho, Liisa; Starr, Mike; Kantola, Marjatta; Laurén, Ari; Piispanen, Juha; Pietilä, Heidi; Perämäki, Paavo; Merilä, Päivi; Fritze, Hannu; Tuomivirta, Tero; Heikkinen, Juha; Mäkinen, Jari; Nieminen, Tiina M

    2016-04-01

    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 2 years after harvesting.

  12. 40 CFR 75.38 - Standard missing data procedures for Hg CEMS.

    Science.gov (United States)

    2010-07-01

    ... reduces the concentration of Hg emitted to the atmosphere (including circulating fluidized bed units that... concentration data have been obtained following initial certification, the owner or operator shall provide substitute data for Hg concentration in accordance with the procedures in ( 75.33(b)(1) through (b)(4...

  13. Mercury (Hg) in meteorites: variations in abundance, thermal release profile, mass-dependent and mass-independent isotopic fractionation

    CERN Document Server

    Meier, Matthias M M; Marty, Bernard

    2016-01-01

    We have measured the concentration, isotopic composition and thermal release profiles of Mercury (Hg) in a suite of meteorites, including both chondrites and achondrites. We find large variations in Hg concentration between different meteorites (ca. 10 ppb to 14'000 ppb), with the highest concentration orders of magnitude above the expected bulk solar system silicates value. From the presence of several different Hg carrier phases in thermal release profiles (150 to 650 {\\deg}C), we argue that these variations are unlikely to be mainly due to terrestrial contamination. The Hg abundance of meteorites shows no correlation with petrographic type, or mass-dependent fractionation of Hg isotopes. Most carbonaceous chondrites show mass-independent enrichments in the odd-numbered isotopes 199Hg and 201Hg. We show that the enrichments are not nucleosynthetic, as we do not find corresponding nucleosynthetic deficits of 196Hg. Instead, they can partially be explained by Hg evaporation and redeposition during heating of ...

  14. Hg localisation in Tillandsia usneoides L. (Bromeliaceae), an atmospheric biomonitor

    Energy Technology Data Exchange (ETDEWEB)

    Filho, G.M.A. [Instituto de Pesquisas Jardim Botanico do Rio de Janeiro (Brazil). Programa Zona Costeira; Andrade, L.R.; Farina, M. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Ciencias Biomedicas, Departamento de Anatomia; Malm, O. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Biofisica Carlos Chagas Filho, Laboratorio de Radioisotopos Eduardo Penna Franca

    2002-07-01

    The Spanish moss, Tillandsia usneoides, has been applied as an atmospheric biomonitor of Hg contamination, although the mechanism of metal plant accumulation has not been understood until now. In the present work, analytical scanning electron microscopy (SEM) was used to localize Hg in T. usneoides exposed to a Hg-air-contaminated area during 15 days. After this period, Hg was determined by the flow injection mercury system, and plants were prepared for SEM observation and energy-dispersive X-ray analysis. A concentration of 2702{+-}318{mu}g Hgg{sup -1} was determined in exposed plants. The presented microanalytical results demonstrated that Hg was partly associated with atmospheric particles deposited upon the plant surface, but it was highly absorbed by the scales, stem and leaves surfaces and less absorbed by epidermal cells of T. usneoides. No Hg was detected in mesophyll parenchyma or in vascular system cells. The great surface adsorption area provided by the scales, in addition to the characteristics of T. usneoides morphology, especially of the node region, are suggested to confer the great capability of T. usneoides in Hg holding. (author)

  15. Hg SOIL GAS AND Hg SOIL DISTRIBUTION AROUND FORMER „ZRINSKI“ MINE ON MT. MEDVEDNICA, CROATIA

    Directory of Open Access Journals (Sweden)

    Nataša Jug

    2008-12-01

    Full Text Available The purpose of this study is to present the field and laboratory researches, statistical analyses and graphical displays of the results of Hg soil gas and Hg soil distribution in the area around former mining site „Zrinski“ on Mt. Medvednica. The values of overall Hg concentrations in the soil gas show lognormal distribution, and their spatial distribution outlines the connection with the present Pb-Ag-Zn mineralization and confirms anthropogenic origin of uneven landscape relief (waste rock clusters. Regression analysis of the dependence between Hg contents in the soil gas and the distance from the mine entrance (correlation coefficient r also points to the considerable spatial dependence. Hg soil contents show as well distribution similar to lognormal, and there is a slight correlation when compared with Hg soil gas content. Concentrations are mostly within background values, except in the immediate vicinity of the mine entrance where the values are significantly higher due to the mineralization influence concentrated in the waste-rock clusters. Soil pollution caused by mercury is of local character with the spreading tendency to the south-west because of the dominant relief influence. Mercury found in the soil of the research location derives from the present mineral body and former mining activities, while possible anthropogenic atmospheric inputs from remote sources can not be proven on the basic of conducted research studies (the paper is published in Croatian.

  16. Mechanistic understanding of MeHg-Se antagonism in soil-rice systems: the key role of antagonism in soil

    Science.gov (United States)

    Wang, Yongjie; Dang, Fei; Evans, R. Douglas; Zhong, Huan; Zhao, Jiating; Zhou, Dongmei

    2016-01-01

    Methylmercury (MeHg) accumulation in rice has great implications for human health. Here, effects of selenium (Se) on MeHg availability to rice are explored by growing rice under soil or foliar fertilization with Se. Results indicate that soil amendment with Se could reduce MeHg levels in soil and grain (maximally 73%). In contrast, foliar fertilization with Se enhanced plant Se levels (3-12 folds) without affecting grain MeHg concentrations. This evidence, along with the distinct distribution of MeHg and Se within the plant, demonstrate for the first time that Se-induced reduction in soil MeHg levels (i.e., MeHg-Se antagonism in soil) rather than MeHg-Se interactions within the plant might be the key process triggering the decreased grain MeHg levels under Se amendment. The reduction in soil MeHg concentrations could be mainly attributed to the formation of Hg-Se complexes (detected by TEM-EDX and XANES) and thus reduced microbial MeHg production. Moreover, selenite and selenate were equally effective in reducing soil MeHg concentrations, possibly because of rapid changes in Se speciation. The dominant role of Se-induced reduction in soil MeHg levels, which has been largely underestimated previously, together with the possible mechanisms advance our mechanistic understanding about MeHg dynamics in soil-rice systems.

  17. Phytoextraction of HG by parsley (Petroselinum crispum) and its growth responses.

    Science.gov (United States)

    Bibi, Asma; Farooq, Umar; Naz, Sadia; Khan, Afsar; Khan, Sara; Sarwar, Rizwana; Mahmood, Qaisar; Alam, Arif; Mirza, Nosheen

    2016-01-01

    The effect of mercury (Hg) on the growth and survival of parsley (Petroselinum crispum) was explored at various treatments. The plants were grown in pots having Hoagland's solution to which various Hg treatments were applied and placed under greenhouse conditions. The treatments were: no metal applied (control) and six doses of Hg as mercuric chloride for 15 days. Linear trend of Hg accumulation was noted in roots, stems, and leaves with increasing Hg treatments. The maximum Hg concentration in root, stem and leaf was 8.92, 8.27, and 7.88 at Hg treatments of 25 mg l(-1), respectively. On the whole, Hg accumulation in different plant parts was in the following order: leaves > stem > roots. Linear trend was also observed for Bioaccumulation Factor (BF) and Translocation Factor (TF) with increasing Hg concentrations in the growth medium. The highest respective BFHg and TFHg values were 9.32 and 2.02 for the Hg treatments of 25 and 50 mg l(-1). In spite of the reduced growth in the presence of Hg, the plant has phytoremediation potential. It is recommended that parsley should not be cultivated in Hg contaminated sites in order to avoid dietary toxicity.

  18. Lupinus albus plants acquire mercury tolerance when inoculated with an Hg-resistant Bradyrhizobium strain.

    Science.gov (United States)

    Quiñones, Miguel A; Ruiz-Díez, Beatriz; Fajardo, Susana; López-Berdonces, Miguel A; Higueras, Pablo L; Fernández-Pascual, Mercedes

    2013-12-01

    One strain of Bradyrhizobium canariense (L-7AH) was selected for its metal-resistance and ability to nodulate white lupin (Lupinus albus L.) plants, from a collection of rhizobial strains previously created from soils of the Almadén mining district (Spain) with varying levels of Hg contamination. Plants were inoculated with either strain L-7AH (Hg-tolerant) or L-3 (Hg-sensitive, used as control), and watered with nutrient solutions supplemented with various concentrations (0-200 μM) of HgCl2 in a growth chamber. L. albus inoculated with L-7AH were able to nodulate even at the highest concentration of Hg while those inoculated with L-3 had virtually no nodules at Hg concentrations above 25 μM. Plants inoculated with L-7AH, but not those with the control strain, were able to accumulate large amounts of Hg in their roots and nodules. Nodulation with L-7AH allowed plants to maintain constant levels of both chlorophylls and carotenoids in their leaves and a high photosynthetic efficiency, whereas in those inoculated with L-3 both pigment content and photosynthetic efficiency decreased significantly as Hg concentration increased. Nitrogenase activity of plants nodulated with L-7AH remained fairly constant at all concentrations of Hg used. Results suggest that this symbiotic pair may be used for rhizoremediation of Hg-contaminated soils. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  19. High removal efficacy of Hg(II) and MeHg(II) ions from aqueous solution by organoalkoxysilane-grafted lignocellulosic waste biomass.

    Science.gov (United States)

    Saman, Norasikin; Johari, Khairiraihanna; Song, Shiow-Tien; Kong, Helen; Cheu, Siew-Chin; Mat, Hanapi

    2017-03-01

    An effective organoalkoxysilanes-grafted lignocellulosic waste biomass (OS-LWB) adsorbent aiming for high removal towards inorganic and organic mercury (Hg(II) and MeHg(II)) ions was prepared. Organoalkoxysilanes (OS) namely mercaptoproyltriethoxylsilane (MPTES), aminopropyltriethoxylsilane (APTES), aminoethylaminopropyltriethoxylsilane (AEPTES), bis(triethoxysilylpropyl) tetrasulfide (BTESPT), methacrylopropyltrimethoxylsilane (MPS) and ureidopropyltriethoxylsilane (URS) were grafted onto the LWB using the same conditions. The MPTES grafted lignocellulosic waste biomass (MPTES-LWB) showed the highest adsorption capacity towards both mercury ions. The adsorption behavior of inorganic and organic mercury ions (Hg(II) and MeHg(II)) in batch adsorption studies shows that it was independent with pH of the solutions and dependent on initial concentration, temperature and contact time. The maximum adsorption capacity of Hg(II) was greater than MeHg(II) which respectively followed the Temkin and Langmuir models. The kinetic data analysis showed that the adsorptions of Hg(II) and MeHg(II) onto MPTES-LWB were respectively controlled by the physical process of film diffusion and the chemical process of physisorption interactions. The overall mechanism of Hg(II) and MeHg(II) adsorption was a combination of diffusion and chemical interaction mechanisms. Regeneration results were very encouraging especially for the Hg(II); this therefore further demonstrated the potential application of organosilane-grafted lignocellulosic waste biomass as low-cost adsorbents for mercury removal process.

  20. Uptake of Hg2+ by picocyanobacteria in natural water from four Andean lakes

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    Diéguez M.C.

    2014-07-01

    Full Text Available In lake food webs, planktonic bacteria and algae represent the greatest bioconcentration step for Hg2+ and monomethyl-Hg (MeHg. As they are the most abundant organisms in planktonic trophic webs and also the main food resource for herbivorous plankton, they can mobilize large amounts of Hg to higher trophic levels. In Andean Patagonian lakes (Argentina, dissolved organic matter (DOM concentration and character, coupled with photo-reactions, play a central role in the complexation of Hg2+ in the water column and can even regulate the uptake of Hg2+ by planktonic algae. In this investigation we evaluated the DOM character of natural waters (NW from four Andean lakes and studied its influence on the uptake of 197Hg2+ in a strain of the picocyanobacteria Synechococcus by using Hg2+ labeled with 197Hg2+. The uptake of radiolabeled Hg2+ by Synechococcus showed different magnitude in NW of lakes Moreno, El Trébol, Morenito and Escondido. Increasing lake DOM concentration reduced the bioavailability of Hg2+ as indicated by the lower uptakes rates found in NW with higher complexity and concentration of the DOM pool. Uptakes of Hg2+ by this picocyanobacteria contrasted among NW from pelagic (surface and bottom and littoral compartments of Lake Escondido which suggest that the entry of this metal may be highly variable even in the same environment. The study of the uptake of radiolabeled Hg2+ in a set of dilutions of NW from Lake Escondido demonstrated that the bioavailability of Hg2+ decrease with increasing DOM concentration.

  1. Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) by hydrolyzed acrylamide-grafted PET films.

    Science.gov (United States)

    Rahman, Nazia; Sato, Nobuhiro; Sugiyama, Masaaki; Hidaka, Yoshiki; Okabe, Hirotaka; Hara, Kazuhiro

    2014-01-01

    Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) using hydrolyzed acrylamide (AAm)-grafted polyethylene terephthalate (PET) films was examined to explore the potential reuse of waste PET materials. Selective recovery of Hg(II) from a mixture of soft acids with similar structure, such as Hg(II) and Pb(II), is important to allow the reuse of recovered Hg(II). An adsorbent for selective Hg(II) adsorption was prepared by γ-ray-induced grafting of AAm onto PET films followed by partial hydrolysis through KOH treatment. The adsorption capacity of the AAm-grafted PET films for Hg(II) ions increased from 15 to 70 mg/g after partial hydrolysis because of the reduction of hydrogen bonding between -CONH2 groups and the corresponding improved access of metal ions to the amide groups. The prepared adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The absorbent film showed high selectivity for the adsorption of Hg(II) over Pb(II) throughout the entire initial metal concentration range (100-500 mg/L) and pH range (2.2-5.6) studied. The high selectivity is attributed to the ability of Hg(II) ions to form covalent bonds with the amide groups. The calculated selectivity coefficient for the adsorbent binding Hg(II) over Pb(II) was 19.2 at pH 4.5 with an initial metal concentration of 100 mg/L. Selective Hg(II) adsorption equilibrium data followed the Langmuir model and kinetic data were well fitted by a pseudo-second-order equation. The adsorbed Hg(II) and Pb(II) ions were effectively desorbed from the adsorbent film by acid treatment, and the regenerated film showed no marked loss of adsorption capacity upon reuse for selective Hg(II) adsorption.

  2. Bioaccumulation of Hg in the mushroom Pleurotus ostreatus

    Energy Technology Data Exchange (ETDEWEB)

    Bressa, G.; Cima, L.; Costa, P.

    1988-10-01

    The possibility of utilizing industrial, urban, and other wastes for the growth of a product which is directly edible by humans is fascinating. However, it is possible that many wastes containing toxic substances, for example, heavy metals, could reach the food chain and produce adverse effects on human health. To this end, we studied the possibility of bioaccumulation of Hg by a mushroom, Pleurotus ostreatus, grown on an artificial compost containing this element. Concentrations of 0.05, 0.1, and 0.2 mg/kg of Hg as Hg(NO/sub 3/)/sub 2/.H/sub 2/O were added to three groups of the same compost, successively inoculated with the mycelia of the mushroom. Higher concentrations strongly reduced the growth of the mycelia and therefore were not utilized. The concentrations of Hg in the substrate and in the mushroom were evaluated by AAS. The range of the accumulation factor was found to be 65-140, i.e., very marked. This finding suggests that the cultivation of P. ostreatus on substrates containing Hg from industrial and urban wastes could involve possible risks to human health.

  3. [Experimental Research of Hg (II) Removal from Aqueous Solutions of HgCl2 with Nano-TiO2].

    Science.gov (United States)

    Zhou, Xiong; Zhang, Jin-yang; Wang, Ding-yong; Qin, Cai-qing; Xu, Feng; Luo Cheng-zhong; Yang, Xi

    2016-01-15

    Mercury removal from aqueous solutions of HgCl2 was studied by indoor simulation experiments, and the effects of three different diameter of particles of Nano-TiO2 ( Nano-Titanium Dioxide) at different dosage, pH, adsorption time and the initial concentration of Hg2+ on the mercury adsorption from simulated wastewater were investigated. The single factor experiments showed that the optimal conditions were: 7.5 g x L(-1) of 5 nm TiO2 or 2.0 g x L(-1) of 100 nm TiO2, pH 8.0, initial concentration of Hg2+ 15 x mg x L(-1) adsorption time 5 min, and under these conditions the adsorption rates reached 99.5% and 99.3%, relatively. When the content of 25 nm TiO2 was 10 g x L(-1), and the other conditions were pH 8.0, initial concentration of Hg2+ 15 mg x L(-1), adsorption time 60 min, the adsorption rate was 62.8%. The Hg(II) removal effects of the TiO2 particles with different diameters followed the order of 100 nm TiO2 > 5 nm TiO2 > 25 nm TiO2. Component adsorption results showed that the 5 nm TiO2 component adsorption effect was superior to its single adsorption effect, while there was little difference between 100 nm TiO2 component adsorption effect and its single adsorption effect. The results of orthogonal experiments indicated that the influencing factors of the adsorption rate followed the order of pH > the initial concentration of Hg2+ > time > dosage. The optimal experiment scheme was: pH 8.0, a dosage of 100 nm Nano-TiO2 of 2.0 g x L(-1) an initial Hg2+ concentration of 25 mg x L(-1) and adsorption time of 10 min. Under the experimental conditions, the maximum adsorption rate reached 99.9%, at the same time, the equilibrium concentration of Hg(II) was 0.033 mg x L(-1) adsorptive capacity was 26.95 mg x g(-1). The adsorption isotherm was in line with the Langmuir isotherm equation, indicating that the Hg(II) uptake by 100 nm Nano-TiO2 was typical monolayer adsorption.

  4. Spatial distribution and accumulation of Hg in soil surrounding a Zn/Pb smelter.

    Science.gov (United States)

    Wu, Qingru; Wang, Shuxiao; Wang, Long; Liu, Fang; Lin, Che-Jen; Zhang, Lei; Wang, Fengyang

    2014-10-15

    Nonferrous metal smelting is an important atmospheric mercury (Hg) emission source that has significant local and global impacts. To quantify the impact of Hg emission from non-ferrous metal smelter on the surrounding soil, an integrated model parameterizing the processes of smelter emission, air dispersion, atmospheric deposition and Hg accumulation in soil was developed. The concentrations of gaseous elemental Hg (GEM) around the smelter and the spatial distribution of Hg in the surrounding soil were measured and compared with the model results. Atmospheric deposition of Hg emitted from the smelter was identified as the main source of Hg accumulation in the surrounding soil. From 1960 to 2011, the smelter emitted approximately 105 t of Hg into the atmosphere, of which 15 t deposited locally and resulted in an increase of Hg concentration in soil from 0.12 to 1.77 mg kg(-1). A detailed examination of wind rose and model data suggested that the area within 1.0-1.5 km northwest and southeast of the smelter was most severely impacted. It was estimated that the smelter operation from 1969 to 1990, when large scale emission controls were not implemented, resulted in 6450 μg m(-2)yr(-1) of Hg net deposition and a model simulated increase of 0.40 mg kg(-1) of Hg accumulation in the soil. During the period from 1991 to 2011, atmospheric Hg emission from the smelter alone increased the average concentration in soil from 0.41 mg kg(-1) to 0.45 mg kg(-1). In the past 50 years, over 86% of Hg emitted from this smelter went into the global pool, indicating the importance of controlling Hg emissions from non-ferrous metal smelters.

  5. Capability of Catfish (Clarias gariepinus to Accumulate Hg2+ From Water

    Directory of Open Access Journals (Sweden)

    Heny Suseno

    2015-12-01

    Full Text Available Mercury is hazardous contaminant that can be accumulated by aquatic organisms such as fishes, mussels etc. Catfish is one of source of animal protein but it also can accumulate Hg2+ from water that used in aquaculture. Due to less information about capability of catfish to accumulate Hg2+, therefore we studied bioaccumulation of Hg2+ that used biokinetic approach (aqueous uptake-rate, and elimination-rate.  Nuclear application technique was applied in this study by using radiotracer of 203Hg.  A simple kinetic model was then constructed to predict the bioaccumulation capability of   by catfish. The result of experiments were shown that the uptake rate of difference Hg2+ concentration were 79.90 to 101.22 ml.g-1.d-1. Strong correlation between uptake rates with increasing Hg2+concentration. In addition, the elimination rates were range 0.080 – 0.081 day-1. The biology half time (t1/2b of Hg2+ in whole body catfish were 8.50 – 8.63 days.  However, no clear correlation  between elimination rate with increasing concentration of Hg2+. The calculation of Bio Concentration Factor (BCF shown catfish have capability to accumulated Hg maximum 1242.69 time than its concentration in water

  6. Chemical thermodynamics of the Hg1212 phase

    Science.gov (United States)

    Tsuchiya, Tetsuo; Fueki, Kazuo

    1997-02-01

    The single phase of Hg1212 was synthesized by the simple oxide method using starting materials containing HgO 16% in excess. Stability regions of Hg1212 and pure HgO were determined by measuring the decomposition temperature as a function of oxygen partial pressure, and thermodynamic diagrams showing the stability domains of HgO and Hg1212 were constructed. The thermodynamical condition of formation of Hg1212 was discussed using the diagrams. It was found by chemical analysis that the valence of Hg is always 2 + and the valence of Ce changes with the oxygen content. TC (zero) changed from 122 to 118 K when the oxygen content was increased from 6.10 to 6.22.

  7. [Mercury concentration in breast milk of women from northwest Mexico; possible association with diet, tobacco and other maternal factors].

    Science.gov (United States)

    Gaxiola-Robles, Ramón; Zenteno-Savín, Tania; Labrada-Martagón, Vanessa; Celis de la Rosa, Alfredo de Jesús; Acosta Vargas, Baudillo; Méndez-Rodríguez, Lía Celina

    2013-01-01

    Objetivo: Determinar los niveles de mercurio total (THg) en leche de mujeres del Noroeste de México y su posible asociación con factores maternos, la dieta y el tabaco. Método: El estudio se realizó en leches donadas por 108 mujeres de Baja California Sur. Se estratificaron en tres grupos de 36 donantes según el número de gesta. Se exploraron datos generales, hábito tabáquico, exposición al humo de tabaco ambiental, ingesta de mariscos y pescados. Los niveles de THg fueron cuantificados utilizando espectrofotometría de absorción atómica. La diferencia entres grupos se evaluó con estadística no paramétrica. Para explicar la posible asociación de las diferentes variables estudiadas y las concentraciones de THg en la leche, se realizaron modelos lineales generalizados. Resultados: Los niveles de THg fueron desde 1.23 ?g/L en las primigestas (GI) a 2,96 ?g/L para las mujeres con 3 o más gestas (GIII) (p = 0,07). En el grupo de GI encontramos una concentración del THg 175% mayor (p = 0,02) entre las mujeres que no comen pescado, en comparación con las que si comen pescado. En el modelo lineal generalizado ajustado por las concentraciones de THg, las variables fueron: edad, número de embarazos, duración de la lactancia y exposición al tabaco (p =?0,05). Conclusiones: El consumo de pescado fue el factor que mejor ajustó los modelos en relación a los niveles de THg. El aporte de Hg por la dieta que se pudo asociar fue bajo, por lo que el consumo de pescado de las costas de Baja California Sur es seguro. El tabaco, incrementa las concentraciones de Hg en la leche materna, por lo que debe de limitarse su hábito durante el embarazo y la lactancia.

  8. Mercury (Hg) exposure and its effects on Saudi breastfed infant's neurodevelopment.

    Science.gov (United States)

    Al-Saleh, Iman; Nester, Michael; Abduljabbar, Mai; Al-Rouqi, Reem; Eltabache, Chafica; Al-Rajudi, Tahreer; Elkhatib, Rola

    2016-01-01

    This cross-sectional study analyzed mercury (Hg) levels in healthy Saudi mothers and their infants (age 3-12 months) and examined the influence of Hg on the infants' neurodevelopment using screening tools, such as the Denver Developmental Screening Test II (DDST-II) and Parents' Evaluation of Developmental Status (PEDS). A total of 944 mothers and their 944 infants were recruited from 57 Primary Health Care Centers (PHCCs) in Riyadh. The total Hg (THg) levels were measured in the mothers' and infants' urine (UTHg-M and UTHg-I) and hair (HTHg-M and HTHg-I) samples and in the breast milk and mothers' blood. Methylmercury (MeHg) levels were determined in hair samples from the mothers (MeHg-M) and infants (MeHg-I). Only 40.1% of the infants were breast-fed when enrolled, and 59.9% had stopped breastfeeding. Only 1.8% of the mothers and 0.3% of the infants had MeHg levels above the Environmental Proection Agency (EPA) reference dose (1 μg/g), with low medians of 0.132 and 0.091 μg/g dw, respectively, but the MeHg levels were significantly associated with infant DDST-II performance. The levels of corrected UTHg-M for creatinine (Cr), HTHg-M, HTHg-I, and HMeHg-M, however, displayed an association with infant PEDS performance. The medians and percentage of the tested population that exceeded the recommended limits for Hg in urine and hair set by the World Health Organization (5 μg/g Cr) and EPA (1 μg/g) were 0.695 μg/g Cr and 3% UTHg, 0.118 μg/g dw and 4.1% HTHg-M, 0.101 μg/g dw and 2.8% HTHg-I, and 0.132 μg/g dw and 1.8% HMeHg-M. Our study provides evidence of an association between some Hg measures and delays in infant neurodevelopment, despite their low levels and regardless of the infant's breastfeeding status. The results are of potential concern, because delayed psychomotor or mental performance in infants could be an indicator of later neurocognitive development in children, which may persist into adulthood, as shown in other studies. The absence of local

  9. Enhanced Hg{sup 2+} removal and Hg{sup 0} re-emission control from wet fuel gas desulfurization liquors with additives

    Energy Technology Data Exchange (ETDEWEB)

    Tingmei Tang; Jiang Xu; Rongjie Lu; Jingjing Wo; Xinhua Xu [Zhejiang University, Hangzhou (China). Department of Environmental Engineering

    2010-12-15

    Secondary atmospheric pollutions may result from wet flue gas desulfurization (FGD) systems caused by the reduction of Hg{sup 2+} to Hg{sup 0}. The present study employed three agents: Na{sub 2}S, 2,4,6-trimercaptotiazine, trisodium salt nonahydrate (TMT) and sodium dithiocarbamate (DTCR) to precipitate aqueous Hg{sup 2+} in simulated desulfurization solutions. The effects of the precipitator's dosing quantity, the initial pH value, the reaction temperature, the concentrations of Cl{sup -} and other metal ions (e.g. Cu{sup 2+} and Pb{sup 2+}) on Hg{sup 2+} removal were studied. A linear relationship was observed between Hg{sup 2+} removal efficiency and the increasing precipitator's doses along with initial pH. The addition of chloride and metal ions impaired the Hg{sup 2+} removal from solutions due to the complexation of Cl{sup -} and Hg{sup 2+} as well as the chelating competition between Hg{sup 2+} and other metal ions. Based on a comprehensive comparison of the treatment effects, DTCR was found to be the most effective precipitating agent. Moreover, all the precipitating agents were potent enough to inhibit Hg{sup 2+} reduction as well as Hg{sup 0} re-emission from FGD liquors. More than 90% Hg{sup 2+} was captured by precipitating agents while Hg{sup 2+} reduction efficiency decreased from 54% to just less than 3%. The additives could efficiently control the secondary Hg{sup 0} pollution from FGD liquors. 21 refs., 6 figs.

  10. [Using atomic fluorescence spectrometry to study the spatial distribution of As and Hg in orchard soils].

    Science.gov (United States)

    Zhao, Xi-Mei; Lü, Chun-Yan; Liu, Qing; Zhu, Xi-Cun

    2014-02-01

    Aqua regia digestion, double channels-atomic fluorescence spectrometry method was used to determine the concentrations of As and Hg in orchard soils of Qixia City - the main apple production area of Shandong province. Validate The detection limitation, accuracy and precision of the method were validated, the spatial distribution was analyzed, and the characteristics of As and Hg pollution in Qixia orchard soils were assessed. The results showed that the range of As concentration in Qixia soils is between 2.79 and 20.93 mg x kg(-1), the average concentration is 10.59 mg x kg(-1), the range of Hg concentration in Qixia soil is between 0.01 and 0.79 mg x kg(-1), the average concentration is 0.12 mg x kg(-1). The variation of As concentration in soils is small, whereas that of Hg concentration is large. Frequency distribution graphics of As and Hg showed that the concentration of As in soils is according with the normal distribution approximately and the concentrations are mostly between 7 and 15 mg x kg(-1), the concentration of Hg in soil isn't according with the normal distribution and the concentrations are mostly between 0.03 and 0.21 mg x kg(-1). The correlations between the concentrations of As or Hg in soils and the nutrient are not significant and there is no significant correlation even between As and Hg. Based on the environmental technical terms for green food production area, the As concentration in orchard soil of Qixia City is at clean level, but there are 4.76% of sample points with Hg pollution index exceeding 1, and this should be attracted the attention of the administrators.

  11. HCN Producing Bacteria Enable Sensing Of Non-Bioavailable Hg Species by the Whole Cell Biosensor

    Science.gov (United States)

    Horvat, M.; Rijavec, T.; Koron, N.; Lapanje, A.

    2015-12-01

    Bacteria play an important role in Hg transformation reactions. The production of cyanide (HCN) and other secondary metabolites seems to be key elements involved in these transformations. Current hypotheses link the role of HCN production to growth inhibition of nonHCN producing competitor organisms (role of an antimicrobial agent). Our past investigations showed that HCN production did not correlate with antimicrobial activity and since pK value of HCN is very high (pK = 9,21), it can be expected that most of the produced HCN is removed from the microenvironment. This way, the expected inhibitory concentrations can hardly be reached. Accordingly, we proposed a new concept, where the ability of complexation of transient metals by HCN served as a regulation process for the accessibility of micro-elements. In our study, we focused on the presence of HCN producing bacteria and carried it out in the Hg contaminated environment connected to the Idrija Mercury Mine, Slovenia. We characterised the isolates according to the presence of Hg resistance (HgR), level of HCN production and genetic similarities. In laboratory setups, using our merR whole cell based biosensor, we determined the transformation of low bioavailable Hg0 and HgS forms into bioavailable Hg by these HCN producing bacteria. We observed that HgR strains producing HCN had the highest impact on increased Hg bioavailability. In the proposed ecological strategy HgR HCN producing bacteria increase their competitive edge over non-HgR competitors through the increase of Hg toxicity. Due to their activity, Hg is made available to other organisms as well and thus enters into the ecosystem. Finally, using some of the characteristics of bacteria (e.g. Hg resistance genetic elements), we developed a fully automated sensing approach, combining biosensorics and mechatronics, to measure the bioavailability of Hg in situ.

  12. Impacts of Activated Carbon Amendment on Hg Methylation, Demethylation and Microbial Activity in Marsh Soils

    Science.gov (United States)

    Gilmour, C. C.; Ghosh, U.; Santillan, E. F. U.; Soren, A.; Bell, J. T.; Butera, D.; McBurney, A. W.; Brown, S.; Henry, E.; Vlassopoulos, D.

    2015-12-01

    In-situ sorbent amendments are a low-impact approach for remediation of contaminants in sediments, particular in habitats like wetlands that provide important ecosystem services. Laboratory microcosm trials (Gilmour et al. 2013) and early field trials show that activated carbon (AC) can effectively increase partitioning of both inorganic Hg and methylmercury to the solid phase. Sediment-water partitioning can serve as a proxy for Hg and MeHg bioavailability in soils. One consideration in using AC in remediation is its potential impact on organisms. For mercury, a critical consideration is the potential impact on net MeHg accumulation and bioavailability. In this study, we specifically evaluated the impact of AC on rates of methylmercury production and degradation, and on overall microbial activity, in 4 different Hg-contaminated salt marsh soils. The study was done over 28 days in anaerobic, sulfate-reducing slurries. A double label of enriched mercury isotopes (Me199Hg and inorganic 201Hg) was used to separately follow de novo Me201Hg production and Me199Hg degradation. AC amendments decreased both methylation and demethylation rate constants relative to un-amended controls, but the impact on demethylation was stronger. The addition of 5% (dry weight) regenerated AC to soil slurries drove demethylation rate constants to nearly zero; i.e. MeHg sorption to AC almost totally blocked its degradation. The net impact was increased solid phase MeHg concentrations in some of the soil slurries with the highest methylation rate constants. However, the net impact of AC amendments was to increase MeHg (and inorganic Hg) partitioning to the soil phase and decrease concentrations in the aqueous phase. AC significantly decreased aqueous phase inorganic Hg and MeHg concentrations after 28 days. Overall, the efficacy of AC in reducing aqueous MeHg was highest in the soils with the highest MeHg concentrations. The AC addition did not significantly impact microbial activity, as

  13. Sediment accumulation and mercury (Hg) flux in Avicennia marina forest of Deep Bay, China

    Science.gov (United States)

    Li, Ruili; Chai, Minwei; Guo, Meixian; Qiu, Guo Yu

    2016-08-01

    To investigate the rate of sediment accumulation and mercury (Hg) flux in Avicennia marina forest of Deep Bay, China, sediment cores were analyzed. The results showed that Hg concentrations were much higher at all depths compared to the background level. A high correlation between Hg and total organic carbon (TOC) indicated their similar anthropogenic origin. Sedimentation rate was estimated to be 1.38 cm a-1 by 210Pb geochronology. The increase in the mass sediment accumulation rates was rapid (range: 0.5-0.94 g cm-2 a-1), and the Hg fluxes ranged between 76 and 116 ng cm-2 a-1 during the last three decades. The reduction in both Hg concentrations and flux during the last decade may be due to the adoption of contamination control policies. Our results support the notion that the Hg fluxes determined from the sediment cores reveal the effects of anthropogenic influences from the areas around Deep Bay.

  14. New technique for quantification of elemental Hg in mine wastes and its implications for mercury evasion into the atmosphere.

    Science.gov (United States)

    Jew, Adam D; Kim, Christopher S; Rytuba, James J; Gustin, Mae S; Brown, Gordon E

    2011-01-15

    Mercury in the environment is of prime concern to both ecosystem and human health. Determination of the molecular-level speciation of Hg in soils and mine wastes is important for understanding its sequestration, mobility, and availability for methylation. Extended X-ray absorption fine structure (EXAFS) spectroscopy carried out under ambient P-T conditions has been used in a number of past studies to determine Hg speciation in complex mine wastes and associated soils. However, this approach cannot detect elemental (liquid) mercury in Hg-polluted soils and sediments due to the significant structural disorder of liquid Hg at ambient-temperature. A new sample preparation protocol involving slow cooling through the crystallization temperature of Hg(0) (234 K) results in its transformation to crystalline α-Hg(0). The presence and proportion of Hg(0), relative to other crystalline Hg-bearing phases, in samples prepared in this way can be quantified by low-temperature (77 K) EXAFS spectroscopy. Using this approach, we have determined the relative concentrations of liquid Hg(0) in Hg mine wastes from several sites in the California Coast Range and have found that they correlate well with measured fluxes of gaseous Hg released during light and dark exposure of the same samples, with higher evasion ratios from samples containing higher concentrations of liquid Hg(0). Two different linear relationships are observed in plots of the ratio of Hg emission under light and dark conditions vs % Hg(0), corresponding to silica-carbonate- and hot springs-type Hg deposits, with the hot springs-type samples exhibiting higher evasion fluxes than silica-carbonate type samples at similar Hg(0) concentrations. Our findings help explain significant differences in Hg evasion data for different mine sites in the California Coast Range.

  15. New technique for quantification of elemental hg in mine wastes and its implications for mercury evasion into the atmosphere

    Science.gov (United States)

    Jew, A.D.; Kim, C.S.; Rytuba, J.J.; Gustin, M.S.; Brown, Gordon E.

    2011-01-01

    Mercury in the environment is of prime concern to both ecosystem and human health. Determination of the molecular-level speciation of Hg in soils and mine wastes is important for understanding its sequestration, mobility, and availability for methylation. Extended X-ray absorption fine structure (EXAFS) spectroscopy carried out under ambient P-T conditions has been used in a number of past studies to determine Hg speciation in complex mine wastes and associated soils. However, this approach cannot detect elemental (liquid) mercury in Hg-polluted soils and sediments due to the significant structural disorder of liquid Hg at ambient-temperature. A new sample preparation protocol involving slow cooling through the crystallization temperature of Hg(0) (234 K) results in its transformation to crystalline ??-Hg(0). The presence and proportion of Hg(0), relative to other crystalline Hg-bearing phases, in samples prepared in this way can be quantified by low-temperature (77 K) EXAFS spectroscopy. Using this approach, we have determined the relative concentrations of liquid Hg(0) in Hg mine wastes from several sites in the California Coast Range and have found that they correlate well with measured fluxes of gaseous Hg released during light and dark exposure of the same samples, with higher evasion ratios from samples containing higher concentrations of liquid Hg(0). Two different linear relationships are observed in plots of the ratio of Hg emission under light and dark conditions vs % Hg(0), corresponding to silica-carbonate- and hot springs-type Hg deposits, with the hot springs-type samples exhibiting higher evasion fluxes than silica-carbonate type samples at similar Hg(0) concentrations. Our findings help explain significant differences in Hg evasion data for different mine sites in the California Coast Range. ?? 2011 American Chemical Society.

  16. Mercury in stream water at five Czech catchments across a Hg and S deposition gradient

    Science.gov (United States)

    Navrátil, Tomáš; Shanley, James B.; Rohovec, Jan; Oulehle, Filip; Krám, Pavel; Matoušková, Šárka; Tesař, Miroslav; Hojdová, Maria

    2015-01-01

    The Czech Republic was heavily industrialized in the second half of the 20th century but the associated emissions of Hg and S from coal burning were significantly reduced since the 1990s. We studied dissolved (filtered) stream water mercury (Hg) and dissolved organic carbon (DOC) concentrations at five catchments with contrasting Hg and S deposition histories in the Bohemian part of the Czech Republic. The median filtered Hg concentrations of stream water samples collected in hydrological years 2012 and 2013 from the five sites varied by an order of magnitude from 1.3 to 18.0 ng L− 1. The Hg concentrations at individual catchments were strongly correlated with DOC concentrations r from 0.64 to 0.93 and with discharge r from 0.48 to 0.75. Annual export fluxes of filtered Hg from individual catchments ranged from 0.11 to 13.3 μg m− 2 yr− 1 and were highest at sites with the highest DOC export fluxes. However, the amount of Hg exported per unit DOC varied widely; the mean Hg/DOC ratio in stream water at the individual sites ranged from 0.28 to 0.90 ng mg− 1. The highest stream Hg/DOC ratios occurred at sites Pluhův Bor and Jezeří which both are in the heavily polluted Black Triangle area. Stream Hg/DOC was inversely related to mineral and total soil pool Hg/C across the five sites. We explain this pattern by greater soil Hg retention due to inhibition of soil organic matter decomposition at the sites with low stream Hg/DOC and/or by precipitation of a metacinnabar (HgS) phase. Thus mobilization of Hg into streams from forest soils likely depends on combined effects of organic matter decomposition dynamics and HgS-like phase precipitation, which were both affected by Hg and S deposition histories.

  17. Superconducting Hg-Based Mixed Oxides and Oxyfluorides

    Science.gov (United States)

    Antipov, E. V.

    2000-09-01

    Syntheses under high pressure and under controlled mercury and oxygen partial pressures of different members of the HgBa2Can-1CunO2n+2+δ series have been developed. There are two main parameters influencing Tc in this family: width of a perovskite slab (n) and concentration (δ) of the extra oxygen located in the Hg layer. The increase of Tc with n occurs until the third member, while after that it decreases. All the members of the series exhibit similar cupola shaped dependencies of Tc vs. δ. Strongly overdoped high members of the series with n = 3-5 were prepared only using high pressure technique and BaO2 as an internal oxidizer. Neutron powder diffraction experiments were carried out for monophase oxygenated HgBa2CuO4F4+δ and fluorinated HgBa2CuO4Fδ samples with different extra oxygen or fluorine content and Tc values. Fluorinated series also exhibits the cupola -like behavior for the Tc vs. δ dependence. NPD showed twice the amount of extra fluorine in comparison with those for the oxygenated Hg-1201 phases with close Tc's. The exchange of the extra oxygen by double amount of fluorine causes shortening of the apical Cu-O distances, while the in-plane ones, as well as Tc, do not vary. The influence of the external pressure on the structure and Tc of Hg-1201 strongly depends on the doping level. The increase of the extra oxygen content on going from underdoped to overdoped state results in the larger compression of the apical Cu-O and Ba-OHg distances while the HgO2 dumbbell as well as the distance between Ba and O from the (CuO2) layers becomes practically pressure independent. These results together with the data for fluorinated materials allow to elucidate the crucial structural features responsible for the Tc variation under high pressure.

  18. Overcoming phytoremediation limitations. A case study of Hg contaminated soil

    Science.gov (United States)

    Barbafieri, Meri

    2013-04-01

    Phytoremediation is a broad term that comprises several technologies to clean up water and soil. Despite the numerous articles appearing in scientific journals, very few field applications of phytoextraction have been successfully realized. The research here reported on Phytoextraction, the use the plant to "extract" metals from contaminated soil, is focused on implementations to overcome two main drawbacks: the survival of plants in unfavorable environmental conditions (contaminant toxicity, low fertility, etc.) and the often lengthy time it takes to reduce contaminants to the requested level. Moreover, to overcome the imbalance between the technology's potential and its drawbacks, there is growing interest in the use of plants to reduce only the fraction that is the most hazardous to the environment and human health, that is to target the bioavailable fractions of metals in soil. Bioavailable Contaminant Stripping (BCS) would be a remediation approach focused to remove the bioavailable metal fractions. BCS have been used in a mercury contaminated soil from Italian industrial site. Bioavailable fractions were determined by sequential extraction with H2O and NH4Cl.Combined treatments of plant hormone and thioligand to strength Hg uptake by crop plants (Brassica juncea and Helianthus annuus) were tested. Plant biomass, evapotranspiration, Hg uptake and distribution following treatments were compared. Results indicate the plant hormone, cytokinine (CK) foliar treatment, increased evapotranspiration rate in both tested plants. The Hg uptake and translocation in both tested plants increased with simultaneous addition of CK and TS treatments. B. juncea was the most effective in Hg uptake. Application of CK to plants grown in TS-treated soil lead to an increase in Hg concentration of 232% in shoots and 39% in roots with respect to control. While H. annuus gave a better response in plant biomass production, the application of CK to plants grown in TS-treated soil lead to

  19. 活性染料染色用高浓液体有机固色剂HG的开发和应用%Development and Application on High-concentrated Organic Fixing Agent HG Used in Reactive Dyeing

    Institute of Scientific and Technical Information of China (English)

    徐蔚; 魏巍; 陆海英; 庄永祥; 杨军浩

    2012-01-01

    The passage introduces a high-concentrated organic fixing agent HC~ which was applicable to all kinds of reactive dyes, including Dyeing at Low Liquor Ratio. Perfect tinctorial yield and reproducibility were achieved when used on different structured reactive dyes. It was act as fixing agent when dyeing in the reactive dyes. It consumes only 1/8~1/10 compared with Sodium carbonate and shortened 20-30 minutes with excellent leveling effect and low dyeing disadvantages. Furthermore, owing to the less consumption, the textile is easier to wash, cutting down the washing times, eliminating acid wash and saving great: amount on energy as well as working hours. It only consumes half of the water compared with Sodium carbonate techniques and 1/3 of gas consumption. This can greatly reduce amount of waste water and alkali content. Different from the Substitution alkali which was sold in the market, it is a high concentrated and organic liquid. In its molecular structure, the carbon chain of hydrophobic groups is shorter, water-soluble groups and hydrophilic group are included, which plays important role in the buffer solution system regarding fluxing, penetrating, dispersing, retarding and migrating.%该文介绍了一种自主研发的高浓液体有机固着剂HG,它适用于各种类型的活性染料的染色,也适用于小浴比染色新工艺。对各种结构的活性染料能得到较高的给色量和良好的重现性。它在活性染料染色时用作固色剂,其用量仅为纯碱的1/8~1/10,加碱时间缩短为20~30min,匀染效果佳,可大幅降低染色疵病率。同时,由于用量少,染色后的织物易于洗涤,可以减少水洗道数,省去酸洗,节约了大量的水和汽及工时,用水量仅为纯碱工艺的1/2,蒸汽用量仅是纯碱工艺的1/3,减少了污水和污水中碱剂含量。它和已进入市场的代碱剂有所不同,它是高浓液体的、有机的,它的分子结构中疏抽№

  20. Mother-embryo isotope (δ 15 N, δ 13 C) fractionation and mercury (Hg) transfer in aplacental deep-sea sharks : aplacental shark isotope fractionation and hg

    OpenAIRE

    Le Bourg, B.; Kiszka, J.; Bustamante, P.

    2014-01-01

    Stable carbon (δ13C) and nitrogen (δ15N) isotopic values and total mercury (Hg) concentrations were analysed in muscle and liver of mothers and embryos of two aplacental shark species, Squalus megalops and Centrophorus moluccensis. Embryos of the two species had similar or lower isotopic values than their respective mothers, the only exception being for δ13C, which was higher in the liver of C. moluccensis embryos than in their mothers. Hg concentrations were systematically lower in embryos c...

  1. Local chemical composition of HgBaCaCuO high-temperature superconductors

    Science.gov (United States)

    Alméras, P.; Dell'Orto, T.; Coluzza, C.; Almeida, J.; Margaritondo, G.; Xue, Y. Y.; Meng, R. L.; Chu, C. W.

    1994-07-01

    The microchemical composition and the electronic structure of the two superconductors HgBa2Ca2Cu3O8+δ (Hg-1223) and HgBa2Ca1Cu2O6+δ (Hg-1212) were analyzed with the technique of photoemission with high spatial resolution. This enabled primary spectral peaks to be separated from their satellites due to local charging induced by the primary photon beam. Each sample contains superconducting and impurity phases with inhomogeneous spatial distributions. The oxygenation-induced increase in the critical temperature is related to a increase in the Cu-O plane carrier concentration.

  2. Mercury Transport During Snowmelt in Three Mountain Watersheds in Northern Utah, USA

    Science.gov (United States)

    Packer, B. N.; Carling, G. T.; Tingey, D. G.

    2015-12-01

    Mercury (Hg) transport during snowmelt is widely recognized as a significant source of Hg to high elevation lakes and streams. However, it is not well understood to what extent Hg is associated with suspended sediment versus dissolved organic matter during snowmelt runoff. To investigate Hg transport during snowmelt, we collected samples for filtered and unfiltered total Hg (THg) and dissolved organic carbon (DOC) in snowpack and snowmelt runoff across three snow-dominated watersheds in northern Utah: Logan River, Provo River, and Little Cottonwood Creek. The watersheds were selected to cover a range of geologic and hydrologic conditions typical of the Rocky Mountain region. Initial results show that snowpack THg concentrations were similar across the watersheds (0.87 - 1.69 ng/L) but river THg concentrations were highly variable. The Provo River showed the highest THg concentrations approaching 6 ng/L during peak flows, whereas maximum THg concentrations in the Logan River were <2 ng/L. Little Cottonwood Creek showed intermediate THg concentrations. THg and DOC showed strong positive correlation in the Provo River (R2=0.68) but were not correlated in the Logan River (R2=0.04). Notably, the Provo River showed the highest fraction of "dissolved" THg (calculated as the fraction of filtered/unfiltered concentration) averaging 75% compared with the other sites where the "dissolved" fraction was <45%. These results suggest that the majority of THg is transported in association with DOC in the Provo River but is more strongly associated with suspended sediments in the Logan River and Little Cottonwood Creek. These findings have implications for understanding Hg cycling in the Provo River watershed where Jordanelle Reservoir has fish consumption advisories due elevated Hg concentrations. The dissolved load of THg, possibly associated with DOC, is likely methylated in Jordanelle Reservoir where it bio-accumulates up the food web.

  3. Assessing anthropogenic sources of mercury in soil in Wanshan Hg mining area, Guizhou, China.

    Science.gov (United States)

    Dai, Zhihui; Feng, Xinbin; Zhang, Chao; Wang, Jingfu; Jiang, Taiming; Xiao, Houjun; Li, Yu; Wang, Xun; Qiu, Guangle

    2013-11-01

    Long-term mining and smelting activities brought a series of environmental issues into soils in Wanshan mercury (Hg) mining area (WMMA), Guizhou, China. Several studies have been published on the concentrations of Hg in local soils, but a comprehensive assessment of the mass of Hg in soil induced by anthropogenic activities, as presented in this paper, has not been previously conducted. Three districts of WMMA were chosen as the study areas. We summarized previous published data and sampled 14 typical soil profiles to analyze the spatial and vertical distributions of Hg in soil in the study areas. The regional geologic background, direct and indirect Hg deposition, and Hg-polluted irrigation water were considered as the main sources of Hg contaminations in local soils. Furthermore, the enrichment factor (EF) method was applied to assess the extent of anthropogenic input of Hg to soil. Titanium (Ti) was chosen to be the reference element to calculate the EF. Generally, the elevated values of EF were observed in the upper soil layers and close to mine wastes. The total budget of Hg in soil contributed from anthropogenic sources was estimated to be 1,227 t in arable soil and 75 t in natural soil. Our data showed that arable soil was the major sink of anthropogenic Hg in the study area.

  4. A regenerative ratiometric electrochemical biosensor for selective detecting Hg²⁺ based on Y-shaped/hairpin DNA transformation.

    Science.gov (United States)

    Jia, Jing; Chen, Hong Guo; Feng, Ji; Lei, Jing Lei; Luo, Hong Qun; Li, Nian Bing

    2016-02-18

    Inspired by dual-signaling ratiometric mechanism which could reduce the influence of the environmental change, a novel, convenient, and reliable method for the detection of mercury ions (Hg(2+)) based on Y-shaped DNA (Y-DNA) was developed. Firstly, the Y-DNA was formed via the simple annealing way of using two different redox probes simultaneously, omitting the multiple operation steps on the electrode. The Y-DNA was immobilized on the gold electrode surface and then an obvious ferrocene (Fc) signal and a weak methylene blue (MB) signal were observed. Upon addition of Hg(2+), the Y-DNA structure was transformed to hairpin structure based on the formation of T-Hg(2+)-T complex. During the transformation, the redox MB gets close to and the redox Fc gets far away from the electrode surface, respectively. This special design allows a reliable Hg(2+) detection with a detection range from 1 nM to 5 μM and a low detection limit down to 0.094 nM. Furthermore, this biosensor exhibits good selectivity and repeatability, and can be easily regenerated by using L-cysteine. This study offers a simple and effective method for designing ratiometric biosensors for detecting other ions and biomolecules.

  5. Food preferences and Hg distribution in Chelonia mydas assessed by stable isotopes.

    Science.gov (United States)

    Bezerra, M F; Lacerda, L D; Rezende, C E; Franco, M A L; Almeida, M G; Macêdo, G R; Pires, T T; Rostán, G; Lopez, G G

    2015-11-01

    Mercury (Hg) is a highly toxic pollutant that poses in risk several marine animals, including green turtles (Chelonia mydas). Green turtles are globally endangered sea turtle species that occurs in Brazilian coastal waters as a number of life stage classes (i.e., foraging juveniles and nesting adults). We assessed total Hg concentrations and isotopic signatures ((13)C and (15)N) in muscle, kidney, liver and scute of juvenile green turtles and their food items from two foraging grounds with different urban and industrial development. We found similar food preferences in specimens from both areas but variable Hg levels in tissues reflecting the influence of local Hg backgrounds in food items. Some juvenile green turtles from the highly industrialized foraging ground presented liver Hg levels among the highest ever reported for this species. Our results suggest that juvenile foraging green turtles are exposed to Hg burdens from locally anthropogenic activities in coastal areas.

  6. Hg removal and the effects of coexisting metals in forward osmosis and membrane distillation.

    Science.gov (United States)

    Wu, Chia-Yu; Chen, Shiao-Shing; Zhang, Dai-Zhou; Kobayashi, Jun

    2017-06-01

    In this study, we investigate the rejection of Hg, Cd, and Pb and the effect of coexisting metals on Hg removal through forward osmosis (FO) and membrane distillation (MD) in order to establish a more effective water treatment process. The results of our laboratory experiment indicate that more than 97% of the rejection for each metal is achieved through the FO system, and this rejection is the highest among previous studies using membrane filtrations. Moreover, we examine the matrix effect of the coexisting Cd and Pb on the rejection of Hg in the FO system. Hg(2+) rejection increases with increase in the concentration of the coexisting metals. Furthermore, we study the effect of the Hg concentration and the water temperature on rejection of Hg(2+). Indeed, the rejection of Hg(2+) is achieved above 95% under any condition. However, approximately 1-10 ppb Hg from the feed solution remains in the draw solution due to permeation. Therefore, we use a FO-MD hybrid system. Approximately 100% rejection of Hg(2+) and a stable water flux are achieved. Thus, the FO-MD hybrid system is considered an important alternative to previous studies using membrane filtration for heavy metals removal.

  7. EDTA and urease effects on Hg accumulation by Lepidium sativum.

    Science.gov (United States)

    Smolińska, Beata; Cedzyńska, Krystyna

    2007-11-01

    The phytoextraction process was conducted under laboratory conditions with the use of garden cress plants (Lepidium sativum). The experiment was carried out in a model soil, which was characterized before conducting the process. Inorganic forms of mercury (HgCl(2), HgSO(4), Hg(NO(3))(2)) were used for contamination of the soil. The phytoextraction process was conducted after EDTA application to the soil and after urease application. Also the influence of simultaneous addition of ethylenediaminetetraacetic acid (EDTA) and urease into the soil on phytoextraction process was measured. In all variants of phytoextraction process the total mercury concentrations in roots, stems and leaves of garden cress were determined. The result showed that garden cress accumulated mercury from soil. The overall maximum concentration of mercury in its compounds was found in roots of the plant. In all cases, before addition of urease and EDTA, the translocation process and distribution of mercury in the plant tissues were limited. The addition of urease caused an increase of enzyme activity in the soil and at the same time caused an increase of mercury concentration in plant tissues. Application of EDTA increased solubility of mercury and caused an increase of metal accumulation by plants. After simultaneous addition of EDTA and urease into the soil garden cress accumulated about 20% of total mercury concentration in the soil. Most of mercury compounds were accumulated in leaves and stems of the plants (46.0-56.9% of total mercury concentration in the plant tissues).

  8. Using Simple Science to Influence Corporate Responsibility—A Lesson from Mercury (Hg)

    Science.gov (United States)

    Filippelli, G. M.

    2016-12-01

    Mercury (Hg) is a powerful neurotoxin with wide environmental distribution. Typical population exposure to Hg comes from fish consumption, with fish being the final ecological endpoint of Hg magnification after a series of biogeochemical processes. The emission of Hg from coal-fired power plants has been strongly implicated as a key source of environmental Hg, and thus the target for various public policy initiatives in the US and abroad. We conducted a study of Hg distribution in surface soils over a broad area of central Indiana (US) to understand the major sources of Hg to local fish, and to assess the potential role of policy compliance in reducing Hg. We found a plume-like distribution pattern for soil Hg, with values exceeding 400 ppb Hg in the heart of the plume, and reducing to background concentration of about 30 ppb outside of the plume. The plume covered hundreds of square kilometers, was centered directly over the downtown area of Indianapolis (a city of roughly 1 million inhabitants), and could be roughly backtracked to a source in the southwest corner of the city, coincident with a large coal-fired utility plant that has the highest reported emissions of Hg in the area. Evidence of this link between a local source of Hg and net Hg deposition, with related implications for Hg runoff to local stream, biomagnification to fish, and fish consumption advisories was reported in regional newspapers and eventually published in scientific journals. But importantly, these findings were used by an NGO (the Beyond Coal campaign by Indiana branch of the Sierra Club) at a critical time to influence a decision by the owner of the power plant of whether to comply with the Hg policy rule by either adding higher technology scrubbing technologies to the plant or simply to convert the plant over to natural gas as the fuel source (a costlier choice upfront). The utility chose the latter option, and with the permanent elimination of Hg emissions, the net measurable effects

  9. Total mercury and methylmercury in high altitude surface snow from the French Alps.

    Science.gov (United States)

    Marusczak, Nicolas; Larose, Catherine; Dommergue, Aurélien; Yumvihoze, Emmanuel; Lean, David; Nedjai, Rachid; Ferrari, Christophe

    2011-09-01

    Surface snow samples were collected weekly from the 31st of December 2008 to the 21st of June 2009 from Lake Bramant in the French Alps. Total mercury (THg), total dissolved mercury (THgD), methylmercury (MeHg) and particle distributions in surface snow were analyzed. Results showed that THg concentrations, MeHg concentrations and particle load increased with snow surface temperature, which is an indicator of rising temperatures as the season progresses. Significant correlations between MeHg and snow surface temperature and MeHg and total particles greater than 10 μm were observed. This suggests that the MeHg found in the snow originates from atmospheric deposition processes rather than in situ snowpack sources. This study suggests that an important post-winter atmospheric deposition of MeHg and THg occurs on summital zones of the French Alps and it is likely that this contamination originates from the surrounding valleys.

  10. Fractionation, distribution and transport of total mercury and Methylmercury in rivers and tributaries around Wanshan Hg mining district, Guizhou Province, Southwestern China

    Science.gov (United States)

    Feng, X.; Zhang, H.; Larssen, T.; Vogt, R.; Rothenberg, S. E.

    2009-12-01

    The Wanshan mercury (Hg) mining area in Guizhou, China, was one of the world's largest Hg producing regions. Numerous tailings containing mine quarry or calcines still remain, leaching Hg to local rivers and streams and potentially impacting the local population. This study focuses on the regional distribution and temporal variation of aqueous Hg fractions in the 5 main watercourses draining the Wanshan Hg mining and smelting area, covering more than 700 square kilometers. Highly elevated concentrations of total Hg in water samples were found slightly downstream from the Hg mine and smelter tailings, while concentrations decreased sharply to a level well below 50 ng L-1 (US EPA Hg concentration standard for protection of fresh water), within 6-8 km. Total Hg concentrations ranged from extremely high (up to 12 492 ng L-1) just below the calcine tailings, to near the detection level (1.9 ng L-1) in tributary streams. Total Hg levels were correlated with particulate Hg (R2 = 0.996-0.999, Pmethylmercury (MeHg) were inversely related to distance from Hg mine tailings (mine waste calcines), suggesting that mine waste calcines were an important source of both inorganic and MeHg to the downstream environment.

  11. Mass Dependent Fractionation of Hg Isotopes in Source Rocks, Mineral Deposits and Spring Waters of the California Coast Ranges, USA

    Science.gov (United States)

    Smith, C. N.; Kesler, S. E.; Blum, J. D.; Rytuba, J. J.

    2007-12-01

    We present here the first study of the isotopic composition of Hg in rocks, ore deposits, and active hydrothermal systems from the California Coast Ranges, one of Earth's largest Hg-depositing systems. The Franciscan Complex and Great Valley Sequence, which form the bedrock in the California Coast Ranges, are intruded and overlain by Tertiary volcanic rocks including the Clear Lake Volcanic Sequence. These rocks contain two types of Hg deposits, hot-spring deposits that form at shallow depths (geothermal systems that release Hg to the present surface. The Franciscan Complex and Great Valley Sequence contain clastic sedimentary rocks with higher concentrations of Hg than volcanic rocks of the Clear Lake Volcanic Field. Mean Hg isotope compositions for all three rock units are similar, although the range of values in Franciscan Complex rocks is greater than in either Great Valley or Clear Lake rocks. Hot spring and silica-carbonate Hg deposits have similar average isotopic compositions that are indistinguishable from averages for the three rock units, although δ202Hg values for the Hg deposits have a greater variance than the country rocks. Precipitates from dilute spring and saline thermal waters in the area have similarly large variance and a mean δ202Hg value that is significantly lower than the ore deposits and rocks. These observations indicate there is little or no isotopic fractionation during release of Hg from its source rocks into hydrothermal solutions. Isotopic fractionation does appear to take place during transport and concentration of Hg in deposits, especially in their uppermost parts. Boiling of hydrothermal fluids is likely the most important process causing of the observed Hg isotope fractionation. This should result in the release of Hg with low δ202Hg values into the atmosphere from the top of these hydrothermal systems and a consequent enrichment in heavy Hg isotopes in the upper crust through time.

  12. Mercury (Hg) in meteorites: Variations in abundance, thermal release profile, mass-dependent and mass-independent isotopic fractionation

    Science.gov (United States)

    Meier, Matthias M. M.; Cloquet, Christophe; Marty, Bernard

    2016-06-01

    We have measured the concentration, isotopic composition and thermal release profiles of Mercury (Hg) in a suite of meteorites, including both chondrites and achondrites. We find large variations in Hg concentration between different meteorites (ca. 10 ppb to 14,000 ppb), with the highest concentration orders of magnitude above the expected bulk solar system silicates value. From the presence of several different Hg carrier phases in thermal release profiles (150-650 °C), we argue that these variations are unlikely to be mainly due to terrestrial contamination. The Hg abundance of meteorites shows no correlation with petrographic type, or mass-dependent fractionation of Hg isotopes. Most carbonaceous chondrites show mass-independent enrichments in the odd-numbered isotopes 199Hg and 201Hg. We show that the enrichments are not nucleosynthetic, as we do not find corresponding nucleosynthetic deficits of 196Hg. Instead, they can partially be explained by Hg evaporation and redeposition during heating of asteroids from primordial radionuclides and late-stage impact heating. Non-carbonaceous chondrites, most achondrites and the Earth do not show these enrichments in vapor-phase Hg. All meteorites studied here have however isotopically light Hg (δ202Hg = ∼-7 to -1) relative to the Earth's average crustal values, which could suggest that the Earth has lost a significant fraction of its primordial Hg. However, the late accretion of carbonaceous chondritic material on the order of ∼2%, which has been suggested to account for the water, carbon, nitrogen and noble gas inventories of the Earth, can also contribute most or all of the Earth's current Hg budget. In this case, the isotopically heavy Hg of the Earth's crust would have to be the result of isotopic fractionation between surface and deep-Earth reservoirs.

  13. Toxic effects of HgCl2 on the growth and oogonium formation in Oedogonium hatei.

    Science.gov (United States)

    Singh, H V

    2001-01-01

    The effect of mercuric chloride on the germination and growth of swarmers and subsequent induction of oogonia was studied in Oedogonium hatei Kam. (Oedogoniales, Chorophyceae). HgCl2 within the concentration range of 0.01 to 1.0 mg/l produced a progressive increase in the initiation of germination and reduction in the growth of the alga. The percentage of oogonia formed, and mature oogonia developed, decreased linearly with a rise in the concentrations of HgCl2 employed. The results showed that 1 mg/l HgCl2 was highly toxic to the growth and/or multiplication of zoospores and further development of sexual structures in O. hatei. The germination of zoospores and growth of germlings were so severely affected that induction of oogonia remained completely inhibited at 1 mg/l HgCl2. Moreover, 2 mg/l of HgCl2 was lethal to the asexual zoospores.

  14. Mercury and Methylmercury Related to Historical Mercury Mining in Three Major Tributaries to Lake Berryessa, Upper Putah Creek Watershed, California

    Science.gov (United States)

    Sparks, G. C.; Alpers, C. N.; Horner, T. C.; Cornwell, K.; Izzo, V.

    2016-12-01

    The relative contributions of total mercury (THg) and methylmercury (MeHg) from upstream historical mercury (Hg) mining districts were examined in the three largest tributaries to Lake Berryessa, a reservoir with water quality impaired by Hg. A fish consumption advisory has been issued for the reservoir; also, in a study of piscivorous birds at 25 California reservoirs, blood samples from Lake Berryessa grebes had the highest THg concentration state-wide. The third and fourth largest historical Hg-producing mining districts in California are within the study area. These mining districts are located within the Pope Creek, Upper Putah Creek, and Knoxville-Eticuera Creeks watersheds. Downstream of the reservoir, Lower Putah Creek drains into the Yolo Bypass, a major source of THg and MeHg to the Sacramento-San Joaquin Delta. Study objectives included: (1) determining if tributaries downstream of historical Hg mining districts and draining to the reservoir are continuing sources of THg and MeHg; (2) characterizing variability of water and streambed sediment parameters in upstream and downstream reaches of each creek; and (3) estimating loads of suspended sediment, THg, and MeHg entering the reservoir from each tributary. Water samples were collected from October 2012 to September 2014 during non-storm and storm events along each tributary and analyzed for general water quality field parameters; unfiltered THg and MeHg; total suspended solids; and total particulate matter. Discharge measurements were made at the time of sample collection; flow and concentration data were combined to compute daily loads. To determine spatial variability, 135 streambed sediment samples were analyzed for THg, organic content (loss on ignition), and grain-size distribution. All three tributaries contribute THg and MeHg to the reservoir. Some consistent spatial trends in THg (water) concentrations were observed over multiple sampling events; THg (water) decreased from upstream to downstream

  15. Evaluating hair as a predictor of blood mercury: the influence of ontogenetic phase and life history in pinnipeds

    Science.gov (United States)

    Peterson, Sarah H.; McHuron, Elizabeth A.; Kennedy, Stephanie N.; Ackerman, Josh; Rea, Lorrie D.; Castellini, J. Margaret; O'Hara, Todd M.; Costa, Daniel P.

    2016-01-01

    Mercury (Hg) biomonitoring of pinnipeds increasingly utilizes nonlethally collected tissues such as hair and blood. The relationship between total Hg concentrations ([THg]) in these tissues is not well understood for marine mammals, but it can be important for interpretation of tissue concentrations with respect to ecotoxicology and biomonitoring. We examined [THg] in blood and hair in multiple age classes of four pinniped species. For each species, we used paired blood and hair samples to quantify the ability of [THg] in hair to predict [THg] in blood at the time of sampling and examined the influence of varying ontogenetic phases and life history of the sampled animals. Overall, we found that the relationship between [THg] in hair and blood was affected by factors including age class, weaning status, growth, and the time difference between hair growth and sample collection. Hair [THg] was moderately to strongly predictive of current blood [THg] for adult female Steller sea lions (Eumetopias jubatus), adult female California sea lions (Zalophus californianus), and adult harbor seals (Phoca vitulina), whereas hair [THg] was poorly predictive or not predictive (different times of year) of blood [THg] for adult northern elephant seals (Mirounga angustirostris). Within species, except for very young pups, hair [THg] was a weaker predictor of blood [THg] for prereproductive animals than for adults likely due to growth, variability in foraging behavior, and transitions between ontogenetic phases. Our results indicate that the relationship between hair [THg] and blood [THg] in pinnipeds is variable and that ontogenetic phase and life history should be considered when interpreting [THg] in these tissues.

  16. Mercury biomagnification in three geothermally-influenced lakes differing in chemistry and algal biomass

    Energy Technology Data Exchange (ETDEWEB)

    Verburg, Piet, E-mail: piet.verburg@niwa.co.nz; Hickey, Christopher W.; Phillips, Ngaire

    2014-09-15

    Accumulation of Hg in aquatic organisms is influenced not only by the contaminant load but also by various environmental variables. We compared biomagnification of Hg in aquatic organisms, i.e., the rate at which Hg accumulates with increasing trophic position, in three lakes differing in trophic state. Total Hg (THg) concentrations in food webs were compared in an oligotrophic, a mesotrophic and a eutrophic lake with naturally elevated levels of Hg associated with geothermal water inputs. We explored relationships of physico-chemistry attributes of lakes with Hg concentrations in fish and biomagnification in the food web. Trophic positions of biota and food chain length were distinguished by stable isotope {sup 15}N. As expected, THg in phytoplankton decreased with increasing eutrophication, suggesting the effect of biomass dilution. In contrast, THg biomagnification and THg concentrations in trout were controlled by environmental physico-chemistry and were highest in the eutrophic lake. In the more eutrophic lake frequent anoxia occurred, resulting in favorable conditions for Hg transfer into and up the food chain. The average concentration of THg in the top predator (rainbow trout) exceeded the maximum recommended level for consumption by up to 440%. While there were differences between lakes in food chain length between plankton and trout, THg concentration in trout did not increase with food chain length, suggesting other factors were more important. Differences between the lakes in biomagnification and THg concentration in trout correlated as expected from previous studies with eight physicochemical variables, resulting in enhanced biomagnification of THg in the eutrophic lake. - Highlights: • Relationships between Hg biomagnification and 11 variables in 3 lakes. • Hg in trout too high for consumption in two geothermally-influenced lakes. • Hg biomagnification was highest in the most eutrophic lake. • First study to compare Hg biomagnification in

  17. Variations and constancy of mercury and methylmercury accumulation in rice grown at contaminated paddy field sites in three Provinces of China.

    Science.gov (United States)

    Li, B; Shi, J B; Wang, X; Meng, M; Huang, L; Qi, X L; He, B; Ye, Z H

    2013-10-01

    Many paddy fields have been contaminated by mercury (Hg) in mining areas of China. In this study, twenty-six rice cultivars and three Hg contaminated paddy fields in different geographic regions were selected for field trials and aimed to investigate the variations and similarities in total Hg (THg) and methylmercury (MeHg) accumulations in brown rice (seeds) across sites. Our results revealed widescale cultivar variation in THg (13-52 ng g(-1) at Wanshan) and MeHg (3.5-23 ng g(-1)) accumulation and %MeHg (17.7-89%) in seeds. The ability to translocate is an important factor in the levels of THg and MeHg in seed. Cultivar tended to stability in THg accumulation across sites. Some cultivars accumulated lower concentrations of both THg and MeHg in seeds at fields seriously contaminated by Hg. Present results suggest that appropriate cultivar selection is a possible way to reduce THg and MeHg accumulation in seeds of rice grown in Hg-contaminated regions.

  18. Spatial and temporal distributions of total and methyl mercury in precipitation in core urban areas, Chongqing, China

    Directory of Open Access Journals (Sweden)

    Y. M. Wang

    2012-04-01

    Full Text Available The spatial and temporal distribution patterns of mercury (Hg in precipitation were investigated in the core urban areas of Chongqing, China. During the period form July 2010 to June 2011, total mercury (THg and methyl mercury (MeHg concentrations in precipitation were analyzed from three sampling sites. Our results suggest that the volume-weight mean THg and MeHg concentrations in precipitation were 30.67 ng l−1 and 0.31 ng l−1, respectively. The proportion of MeHg in THg ranged from 0.1% to 7.6% with a mean value of 1.3%. THg and MeHg concentrations showed seasonal variations, while the highest THg value was measured in winter. Contrarily, the highest MeHg concentration was observed in autumn. Additionally, a geographically gradual decline of THg concentration in precipitation was observed from the city center to the suburb, then to the exurb. 5 mm rainfall might be a threshold for the full wash-out capability. Rainfall above 5 mm may have a diluting effect for the concentrations of Hg. Moreover, the current research implies that the coal combustion and motor vehicles could be the dominant sources for Hg in the precipitation.

  19. Bioaccumulation of As, Cd, Cr, Hg(II), and MeHg in killifish (Fundulus heteroclitus) from amphipod and worm prey.

    Science.gov (United States)

    Dutton, Jessica; Fisher, Nicholas S

    2011-08-15

    Elevated metal levels in fish are a concern for the fish themselves, their predators, and possibly humans who consume contaminated seafood. Metal bioaccumulation models often rely on assimilation efficiencies (AEs) of ingested metals and loss rate constants after dietary exposure (k(ef)s). These models can be used to better understand processes regulating metal accumulation and can be used to make site-specific predictions of metal concentrations in animal tissues. Fish often consume a varied diet, and prey choice can influence these two parameters. We investigated the trophic transfer of As, Cd, Cr, Hg(II), and methylmercury (MeHg) from a benthic amphipod (Leptocheirus plumulosus) and an oligochaete (Lumbriculus variegatus) to killifish (Fundulus heteroclitus) using gamma-emitting radioisotopes. Except for MeHg, AEs varied between prey type. AEs were highest for MeHg (92%) and lowest for Cd (2.9-4.5%) and Cr (0.2-4%). Hg(II) showed the largest AE difference between prey type (14% amphipods, 24% worms). For Cd and Hg(II) k(ef)s were higher after consuming amphipods than consuming worms. Tissue distribution data shows that Cd and Hg(II) were mainly associated with the intestine, whereas As and MeHg were transported throughout the body. Calculated trophic transfer factors (TTFs) suggest that MeHg is likely to biomagnify at this trophic step at all ingestion rates, whereas As, Cd, Cr, and Hg(II) will not. Data collected in this study and others indicate that using one prey item to calculate AE and k(ef) could lead to an over- or underestimation of these parameters.

  20. Growth, properties and applications of HgCdTe

    Science.gov (United States)

    Schmit, J. L.

    1983-12-01

    This paper provides primarily a review of the methods used to grow HgCdTe with a summary of some of its basic properties and applications. Methods of crystal growth fall generally into three classes: growth from the melt, from solution and from the vapor phase. All three methods have been and are being used to grow HgCdTe. The high vapor pressure of HgCdTe at the melting point, combined with a large segregation coefficient, have effectively limited the use of Czochralski or zone melting techniques, but two melt growth techniques have survived: (1) a variation of Bridgman growth called quench-anneal wherein a dendritic crystal is formed by quenching the melt and is homogenized by solid state recrystallization below the melting point, (2) a variation of freezing from a large volume called slush-growth wherein a melt is held in a temperature gradient for several weeks while a crystal grows. Growth from solution has taken the form of liquid phase epitaxy (LPE) on CdTe with the LPE systems including growth from Hg-rich, HgTe-rich and Te-rich solutions and using tipping, vertical dipping, vertical sliding and horizontal sliding. Vapor phase growth is very promising but is not yet in production. Techniques include growth by isothermal close spaced epitaxy in which HgTe is transported isothermally by chemical potential onto CdTe, molecular beam epitaxy (MBE) in which elements are evaporated in a high vacuum, and metal organic chemical vapor deposition (MOCVD) in which some of the metal atoms are carried to the substrate bound to organic radicals before being freed by pyrolysis. In all these methods, control of Hg pressure is a major concern. The fundamental properties discussed briefly are those of prime interest to detector manufacturers: energy gap ( Eg), intrinsic carrier concentration ( ni), and electrical activity of dopants. A reasonable fit to the Eg data from ˜ 20 papers is given by Eg = -0.302+1.93x+5.35×10 -4T(1-2x)-0.810x 2+0.832x 3. This gap, combined with k

  1. Folic acid functionalized silver nanoparticles with sensitivity and selectivity colorimetric and fluorescent detection for Hg2+ and efficient catalysis

    Science.gov (United States)

    Su, Dongyue; Yang, Xin; Xia, Qingdong; Zhang, Qi; Chai, Fang; Wang, Chungang; Qu, Fengyu

    2014-09-01

    In this research, folic acid functionalized silver nanoparticles (FA-AgNPs) were selected as a colorimetric and a ‘turn on’ fluorescent sensor for detecting Hg2+. After being added into Hg2+, AgNPs can emit stable fluorescence at 440 nm when the excitation wavelength is selected at 275 nm. The absorbance and fluorescence of the FA-AgNPs could reflect the concentration of the Hg2+ ions. Thus, we developed a simple, sensitive analytical method to detect Hg2+ based on the colorimetric and fluorescence enhancement of FA-AgNPs. The sensor exhibits two linear response ranges between absorbance and fluorescence intensity with Hg2+ concentration, respectively. Meanwhile, a detection limit of 1 nM is estimated based on the linear relationship between responses with a concentration of Hg2+. The high specificity of Hg2+ with FA-AgNPs interactions provided the excellent selectivity towards detecting Hg2+ over other metal ions (Pb2+, Mg2+, Zn2+, Ni2+, Cu2+, Co2+, Ca2+, Mn2+, Fe2+, Cd2+, Ba2+, Cr6+ and Cr3+). This will provide a simple, effective and multifunctional colorimetric and fluorescent sensor for on-site and real-time Hg2+ ion detection. The proposed method can be applied to the analysis of trace Hg2+ in lake water. Additionally, the FA-AgNPs can be used as efficient catalyst for the reduction of 4-nitrophenol and potassium hexacyanoferrate (III).

  2. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    Science.gov (United States)

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ202Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ202Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206Pb/207Pb and 208Pb/207Pb isotopic compositions during these periods. Data for Δ199Hg and Δ201Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ199Hg and Δ201Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger.

  3. Kinetics and mechanism of jack bean urease inhibition by Hg2+

    Directory of Open Access Journals (Sweden)

    Du Nana

    2012-12-01

    Full Text Available Abstract Background Jack bean urease (EC 3.5.1.5 is a metalloenzyme, which catalyzes the hydrolysis of urea to produce ammonia and carbon dioxide. The heavy metal ions are common inhibitors to control the rate of the enzymatic urea hydrolysis, which take the Hg2+ as the representative. Hg2+ affects the enzyme activity causing loss of the biological function of the enzyme, which threatens the survival of many microorganism and plants. However, inhibitory kinetics of urease by the low concentration Hg2+ has not been explored fully. In this study, the inhibitory effect of the low concentration Hg2+ on jack bean urease was investigated in order to elucidate the mechanism of Hg2+ inhibition. Results According to the kinetic parameters for the enzyme obtained from Lineweaver–Burk plot, it is shown that the Km is equal to 4.6±0.3 mM and Vm is equal to 29.8±1.7 μmol NH3/min mg. The results show that the inhibition of jack bean urease by Hg2+ at low concentration is a reversible reaction. Equilibrium constants have been determined for Hg2+ binding with the enzyme or the enzyme-substrate complexes (Ki =0.012 μM. The results show that the Hg2+ is a noncompetitive inhibitor. In addition, the kinetics of enzyme inhibition by the low concentration Hg2+ has been studied using the kinetic method of the substrate reaction. The results suggest that the enzyme first reversibly and quickly binds Hg2+ and then undergoes a slow reversible course to inactivation. Furthermore, the rate constant of the forward reactions (k+0 is much larger than the rate constant of the reverse reactions (k-0. By combining with the fact that the enzyme activity is almost completely lost at high concentration, the enzyme is completely inactivated when the Hg2+ concentration is high enough. Conclusions These results suggest that Hg2+ has great impacts on the urease activity and the established inhibition kinetics model is suitable.

  4. Emission Spectra of Working Mixtures of a HgBr/HgCl Excimer Lamp

    Science.gov (United States)

    Malinin, A. N.; Guĭvan, N. N.; Shimon, L. L.

    2000-12-01

    A study of emission spectra of a gas-discharge plasma produced in a HgBr/HgCl excimer lamp, which is filled with multicomponent working mixtures at atmospheric pressure (HgBr2 and HgCl2 with additions of molecular nitrogen and xenon), are reported. A gas-discharge plasma was produced by high-frequency (pulses ˜100 ns long with a repetition rate of up to 2000 Hz) barrier and surface discharges, which took place simultaneously. Emission of HgBr* and HgCl* excimer molecules, the second positive system of molecular oxygen, and helium and xenon lines in the UV, visible, and IR spectral regions was observed. The strongest emission of HgBr* and HgCl* molecules (the emission intensities were in the ratio 10:1) was observed in the HgBr2: HgCl2: N2: He mixture. Regularities in spectral and integrated characteristics of gas-discharge plasma emission are discussed.

  5. HgTe-CdTe SUPERLATTICES

    OpenAIRE

    Smith, D; Mcgill, T.

    1984-01-01

    We report on a theoretical study of the electronic properties of HgTe-CdTe superlattices. The band gap as a function of layer thickness, effective masses normal to the layer plane and tunneling length are compared to the corresponding (Hg, Cd)Te alloys. We find that the superlattice possesses a number of properties that may make it superior to the corresponding alloy as an infrared material.

  6. Synthesis of current data for Hg in areas of geologic resource extraction contamination and aquatic systems in China.

    Science.gov (United States)

    Qiu, Guangle; Feng, Xinbin; Jiang, Guibin

    2012-04-01

    China has become the largest contributor of anthropogenic atmospheric mercury (Hg) in the world owing to its fast growing economy and the largest of populations. Over the last two decades, Hg has become of increasing environmental concern in China and much has been published on its distribution, transportation, methylation, and bioaccumulation in aquatic systems and areas of geologic resource extraction contaminated sites, such as coal-fired power plants, non-ferrous smelters, Hg mining and retorting sites, Au amalgam, landfills, chemical plants, etc.. Environmental compartments, like soil, water, air, and crop from areas of geologic resource extraction contamination, especially from Hg mining regions, exhibit elevated values of total-Hg and MMHg. Risk assessments indicate that the consumption of rice, which has a high bioaccumulation of MMHg, has become the dominant pathway of MMHg exposure of inhabitants living in Hg mining areas. Low concentrations less than 5ngl(-1) in total-Hg can be observed in rivers from remote areas, however, high concentrations that reached 1600ngl(-1) in total-Hg can be found in rivers from industrial and urban areas. The studies of hydropower reservoirs of southwest China indicated the old reservoirs act as net sinks for total-Hg and net sources of MMHg, while newly established ones act as net sinks for both total-Hg and MMHg, which is in sharp contrast to the evolution of biomethylation in reservoirs established in the boreal belt of North America and Eurasia. Fish from those reservoirs have relatively low levels of total-Hg, which do not exceed the maximum total-Hg limit of 0.5mgkg(-1) recommended by WHO. Currently, however, there is still a large data gap regarding Hg even in the areas mentioned above in China, which results in poor understanding of its environmental biogeochemistry. Moreover, for a better understanding of human and environmental health effects caused by the fast growing economy, long-term Hg monitoring campaigns are

  7. Hg-contaminated terrestrial spiders pose a potential risk to songbirds at Caddo Lake (Texas/Louisiana, USA).

    Science.gov (United States)

    Gann, Gretchen L; Powell, Cleveland H; Chumchal, Matthew M; Drenner, Ray W

    2015-02-01

    Methylmercury (MeHg) is an environmental contaminant that can have adverse effects on wildlife. Because MeHg is produced by bacteria in aquatic ecosystems, studies of MeHg contamination of food webs historically have focused on aquatic organisms. However, recent studies have shown that terrestrial organisms such as songbirds can be contaminated with MeHg by feeding on MeHg-contaminated spiders. In the present study, the authors examined the risk that MeHg-contaminated terrestrial long-jawed orb weaver spiders (Tetragnatha sp.) pose to songbirds at Caddo Lake (Texas/Louisiana, USA). Methylmercury concentrations in spiders were significantly different in river, wetland, and open-water habitats. The authors calculated spider-based wildlife values (the minimum spider MeHg concentrations causing physiologically significant doses in consumers) to assess exposure risks for arachnivorous birds. Methylmercury concentrations in spiders exceeded wildlife values for Carolina chickadee (Poecile carolinensis) nestlings, with the highest risk in the river habitat. The present study indicates that MeHg concentrations in terrestrial spiders vary with habitat and can pose a threat to small-bodied nestling birds that consume large amounts of spiders at Caddo Lake. This MeHg threat to songbirds may not be unique to Caddo Lake and may extend throughout the southeastern United States. © 2014 SETAC.

  8. 46 CFR 53.05-1 - Safety valve requirements for steam boilers (modifies HG-400 and HG-401).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Safety valve requirements for steam boilers (modifies HG... requirements for steam boilers (modifies HG-400 and HG-401). (a) The pressure relief valve requirements and the safety valve requirements for steam boilers must be as indicated in HG-400 and HG-401 of section IV...

  9. Investigation of Hg uptake and transport between paddy soil and rice seeds combining Hg isotopic composition and speciation

    Directory of Open Access Journals (Sweden)

    C. Feng

    2016-02-01

    Full Text Available Abstract Human consumption of rice constitutes a potential toxicological risk in mercury (Hg polluted areas such as Hg mining regions in China. It is recognized to be an important source of Hg for the local human diet considering the efficient bioaccumulation of methylmercury (MeHg in rice seed. To assess Hg sources and uptake pathways to the rice plants, Hg speciation and isotopic composition were investigated in rice seeds and their corresponding paddy soils from different locations within the Wanshan Hg mining area (Guizhou Province, China. A large variation of Hg speciation is observed in rice seeds and paddy soils irrespective of the sampling location. Mass dependent fractionation (MDF of Hg in rice seeds differs by up to ∼4.0 ‰ in δ202Hg values, while mass independent fractionation (MIF of Hg isotopes remains constant (Δ199Hg ∼ 0‰. Hg isotopic composition in rice seeds covaries with that of paddy soils but exhibits lighter isotopic signature (δ202Hg. Such isotopic offset is mainly attributed to plant uptake and translocation processes. Also, seeds containing higher MeHg (MeHg/total Hg > 50% have significantly heavier Hg isotopes suggesting that MeHg uptake and transport to the seed in such rice plants is facilitated compared to inorganic Hg.

  10. Salt-marsh plants as potential sources of Hg0 into the atmosphere

    Science.gov (United States)

    Canário, João; Poissant, Laurier; Pilote, Martin; Caetano, Miguel; Hintelmann, Holger; O'Driscoll, Nelson J.

    2017-03-01

    To assess the role of salt-marsh plants on the vegetation-atmospheric Hg0 fluxes, three salt marsh plant species, Halimione portulacoides, Sarcocornia fruticosa and Spartina maritima were selected from a moderately contaminated site in the Tagus estuary during May 2012. Total mercury in stems and leaves for each plant as well as total gaseous mercury and vegetation-air Hg0 fluxes were measured over two continuous days. Mercury fluxes were estimated with a dynamic flux Tedlar® bag coupled to a high-resolution automated mercury analyzer (Tekran 2537A). Other environmental parameters such as air temperature, relative humidity and net solar radiation were also measured aside. H. portulacoides showed the highest total mercury concentrations in stems and leaves and the highest average vegetation-air Hg0 flux (0.48 ± 0.40 ng Hg m-2 h-1). The continuous measurements converged to a daily pattern for all plants, with enhanced fluxes during daylight and lower flux during the night. It is noteworthy that throughout the measurements a negative flux (air-vegetation) was never observed, suggesting the absence of net Hg0 deposition. Based on the above fluxes and the total area occupied by each species we have estimated the total amount of Hg0 emitted from this salt-marsh plants. A daily emission of 1.19 mg Hg d-1 was predicted for the Alcochete marsh and 175 mg Hg d-1 for the entire salt marsh area of the Tagus estuary.

  11. Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea).

    Science.gov (United States)

    Lapanje, A; Drobne, D; Nolde, N; Valant, J; Muscet, B; Leser, V; Rupnik, M

    2008-06-01

    The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10microg Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed.

  12. Identification of Potential Sources of Mercury (Hg in Farmland Soil Using a Decision Tree Method in China

    Directory of Open Access Journals (Sweden)

    Taiyang Zhong

    2016-11-01

    Full Text Available Identification of the sources of soil mercury (Hg on the provincial scale is helpful for enacting effective policies to prevent further contamination and take reclamation measurements. The natural and anthropogenic sources and their contributions of Hg in Chinese farmland soil were identified based on a decision tree method. The results showed that the concentrations of Hg in parent materials were most strongly associated with the general spatial distribution pattern of Hg concentration on a provincial scale. The decision tree analysis gained an 89.70% total accuracy in simulating the influence of human activities on the additions of Hg in farmland soil. Human activities—for example, the production of coke, application of fertilizers, discharge of wastewater, discharge of solid waste, and the production of non-ferrous metals—were the main external sources of a large amount of Hg in the farmland soil.

  13. Zuotai and HgS differ from HgCl2 and methyl mercury in Hg accumulation and toxicity in weanling and aged rats.

    Science.gov (United States)

    Zhang, Bin-Bin; Li, Wen-Kai; Hou, Wei-Yu; Luo, Ya; Shi, Jing-Zhen; Li, Cen; Wei, Li-Xin; Liu, Jie

    2017-09-15

    Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl2) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Relationship between localization of gold mining areas and hair mercury levels in people from Bolivar, north of Colombia.

    Science.gov (United States)

    Olivero-Verbel, Jesús; Caballero-Gallardo, Karina; Marrugo Negrete, Jose; Negrete-Marrugo, José

    2011-12-01

    Mercury (Hg) is a heavy metal that, once in the environment, is bioaccumulated and biomagnified through food chain impacting ecosystems. The aim of this study was to evaluate total Hg (T-Hg) concentrations in individuals along Cauca and Magdalena Rivers in Colombia, where most gold mining activities take place. A total of 1,328 hair samples were collected and analyzed for T-Hg using atomic absorption spectroscopy. T-Hg concentrations ranged from 0.01 to 20.14 μg/g. Greatest levels were detected in La Raya (5.27 ± 0.32 μg/g), Achi (2.44 ± 0.22 μg/g), and Montecristo (2.20 ± 0.20 μg/g), places that are located near gold mines. Concentrations decreased with the distance from main mining areas. Only 0.75% of the individuals had T-Hg levels above 10 μg/g. Men had significantly higher T-Hg levels than women, and correlation analysis revealed moderately weak but significant relationships between T-Hg and weight (R = 0.111, P mining, monitoring, and educational programs are necessary to protect health of people living near Colombian rivers.

  15. [Temporal and spatial variation of mercury in water of agro-forestry and livestock compound watershed in the three Gorges Reservoir Area].

    Science.gov (United States)

    Zhao, Zheng; Wang, Ya; Mu, Zhi-jian; Wang, Ding-yong

    2015-01-01

    The temporal and spatial distribution of mercury (Hg) in four different sources of stream (aquaculture wastewater, bare land, forestry land and agro-forestry land) and well water of an agro-forestry and livestock compound watershed in the Three Gorge Reservoir region was studied during the period from March 2013 to March 2014. The total mercury (THg) concentrations ranged 9.95-15.26 ng x L(-1) with an average of (11.95 +/- 1.87) ng x L(-1), and the THg concentration decreased in the order of bare land > aquaculture wastewater> forestry land > agro-forestry land > well water. The total methylmercury (TMeHg) concentrations ranged 0.120-0.441 ng x L(-1) with an average of (0.232 +/- 0.099) ng x L(-1), and the TMeHg concentration decreased in the order of aquaculture wastewater > agro-forestry land > forestry land > bare land > well water. THg and TMeHg in well water were both dominated by the dissolved fraction, whereas for other sources of stream, the particulate phase accounted for the major fraction of THg and TMeHg. The THg concentrations in winter and spring were significant higher than those in summer and fall, however, no obvious seasonal trend of TMeHg distribution was observed. Comprehensive analysis showed human activities and weather conditions such as air temperature and precipitation etc. were the main reasons for the difference of temporal and spatial distribution of THg and TMeHg.

  16. Mercury export to the Arctic Ocean from the Mackenzie River, Canada.

    Science.gov (United States)

    Emmerton, Craig A; Graydon, Jennifer A; Gareis, Jolie A L; St Louis, Vincent L; Lesack, Lance F W; Banack, Janelle K A; Hicks, Faye; Nafziger, Jennifer

    2013-07-16

    Circumpolar rivers, including the Mackenzie River in Canada, are sources of the contaminant mercury (Hg) to the Arctic Ocean, but few Hg export studies exist for these rivers. During the 2007-2010 freshet and open water seasons, we collected river water upstream and downstream of the Mackenzie River delta to quantify total mercury (THg) and methylmercury (MeHg) concentrations and export. Upstream of the delta, flow-weighted mean concentrations of bulk THg and MeHg were 14.6 ± 6.2 ng L(-1) and 0.081 ± 0.045 ng L(-1), respectively. Only 11-13% and 44-51% of bulk THg and MeHg export was in the dissolved form. Using concentration-discharge relationships, we calculated bulk THg and MeHg export into the delta of 2300-4200 kg yr(-1) and 15-23 kg yr(-1) over the course of the study. Discharge is not presently known in channels exiting the delta, so we assessed differences in river Hg concentrations upstream and downstream of the delta to estimate its influence on Hg export to the ocean. Bulk THg and MeHg concentrations decreased 19% and 11% through the delta, likely because of particle settling and other processes in the floodplain. These results suggest that northern deltas may be important accumulators of river Hg in their floodplains before export to the Arctic Ocean.

  17. Local probing of Hg neighboorhood in HgBa$_{2}$CuO$_{4+\\delta}$

    CERN Document Server

    Correia, J G; Loureiro, S M; Toulemonde, P; Le Floc'h, S; Bordet, P; Capponi, J J; Gatt, R; Tröger, W; Ctortecka, B; Butz, T; Haas, H; Marques, J G; Soares, J C

    2000-01-01

    Electric field gradients (EFG) on mercury sites of the Hg1201 high-TC superconductors were measured with the perturbed angular correlation (PAC) technique. In Hg1201 samples where PAC detects higher oxygen content the EFGs have decreased to lower values indicating an elongation of the Hg-apical oxygen dumb-bell. On the same samples the asymmetry parameter of the EFG becomes non-zero below 100 K, showing that the charge distribution near the Hg-apical oxygen chain becomes non-axially symmetric at low temperature.

  18. Complexation of Hg with phytochelatins is important for plant Hg tolerance.

    Science.gov (United States)

    Carrasco-Gil, Sandra; Alvarez-Fernández, Ana; Sobrino-Plata, Juan; Millán, Rocío; Carpena-Ruiz, Ramón O; Leduc, Danika L; Andrews, Joy C; Abadía, Javier; Hernández, Luís E

    2011-05-01

    Three-week-old alfalfa (Medicago sativa), barley (Hordeum vulgare) and maize (Zea mays) were exposed for 7 d to 30 µm of mercury (HgCl(2) ) to characterize the Hg speciation in root, with no symptoms of being poisoned. The largest pool (99%) was associated with the particulate fraction, whereas the soluble fraction (SF) accounted for a minor proportion (phytochelatins (PCs) in root SF, which was particularly varied in alfalfa (eight ligands and five stoichiometries), a species that also accumulated homophytochelatins. Spatial localization of Hg in alfalfa roots by microprobe synchrotron X-ray fluorescence spectroscopy showed that most of the Hg co-localized with sulphur in the vascular cylinder. Extended X-ray Absorption Fine Structure (EXAFS) fingerprint fitting revealed that Hg was bound in vivo to organic-S compounds, i.e. biomolecules containing cysteine. Albeit a minor proportion of total Hg, Hg-PCs complexes in the SF might be important for tolerance to Hg, as was found with Arabidopsis thaliana mutants cad2-1 (with low glutathione content) and cad1-3 (unable to synthesize PCs) in comparison with wild type plants. Interestingly, high-performance liquid chromatography-electrospray ionization-time of flight analysis showed that none of these mutants accumulated Hg-biothiol complexes.

  19. In Situ Behavioral Response of Common Loons Associated with Elevated Mercury (Hg Exposure

    Directory of Open Access Journals (Sweden)

    Joseph J. Nocera

    1998-12-01

    Full Text Available Common Loons (Gavia immer in Nova Scotia, Canada have the highest blood mercury (Hg concentrations of any loon population in North America. Previous studies have shown that exposure to varying levels of Hg in prey is associated with changes in pre-nesting adult behavior. We report here the first association of sublethal blood Hg contamination with changes in behavior of Common Loon young. As Hg levels in their blood rise, the amount of time that chicks spend brooding (by back-riding decreases (P = 0.004 and time spent preening increases (P = 0.003. The sum increase in energy expenditure is not being compensated for with expected increases in feeding rates or begging. We suggest that such altered time-activity budgets may disrupt the energetic balance of young. Our results show that variation in time spent back-riding is associated with changes in fledging rates. Adult behavior did not significantly vary with Hg, but results are suggestive that an association may exist. We also show that monitoring the time-activity budgets of very young chicks can serve to indicate the effects Hg concentrations in their blood. We confirm the hypothesis that loons and other upper trophic level predators could be at risk from elevated levels of bioavailable Hg. This may help to explain the chronically low productivity of such contaminated sites as Kejimkujik and allow for more focused management initiatives.

  20. The longitudinal translocation characters and the influencing factors of Hg, Cd in the soil

    Directory of Open Access Journals (Sweden)

    Zhang Yujuan

    2006-11-01

    Full Text Available Combining the methods of simulation test and field survey, the longitudinal distribution and the influencing factors of Hg and Cd in the profile in the typical sewage irrigation area were studied in this paper and the result shows: (1 the content distribution of Hg, Cd in the superficial soil profile was higher than that in the bottom and the content decreased with the increase of the depth, the translocation ability of the Hg, Cd in the garden mould and cinnamon soil were lower than that in the paddy soil and fluve-aquic soil, the longitudinal translocation ability of the Cd in the soil profile was stronger than that of Hg; (2 Hg was accumulated in the different soil and has the highest accumulation rate in the paddy soil and the lowest in the cinnamon soil; the translocation order of the Cd in the different was: garden mould > paddy soil > cinnamon soil > fluve-aquic soil; (3 the concentration of Hg, Cd in the soil leacheate increased with the concentration increase of Hg, Cd in the sewage, the migration rate increased with the roughness of the soil quality and decreased with the increase of pH and soil organic matter.

  1. Hg(II) removal from aqueous solutions by bacillus subtilis biomass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue Song; Li, Fei Yan; He, Wen; Miao, Hua Hua [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang (China)

    2010-01-15

    The biosorption of Hg(II) from aqueous solutions using Bacillus subtilis biomass was investigated in this study. The adsorbent was characterized by FTIR. Various factors including solution pH, initial concentration of Hg(II), contact time, reaction temperature and ionic strength were taken into account and promising results were obtained. An initial solution pH of 5.0 was most favorable for Hg(II) removal. The kinetic data was also analyzed using pseudo first order and pseudo second order equations. The results suggested that Hg(II) bioadsorption was best represented by the pseudo second order equation. Freundlich, Langmuir and Langmuir-Freundlich isotherms for the present systems were analyzed. The most satisfactory interpretation for the equilibrium data at different temperatures was given by the Langmuir-Freundlich isotherm. The effect of ionic strength on bioadsorption was significant. Bacillus subtilis biomass could serve as low cost adsorbent to remove Hg(II) from aqueous solutions, especially at lower concentrations of Hg(II) (<20 mg Hg/L). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. HgO-added YBa2Cu3O7- superconductors

    Indian Academy of Sciences (India)

    Mangalesh Dixit; Shovit Bhattacharya; Rajneesh Mohan; Kiran Singh; P S R Krishna; Vilas Shelke; N K Gaur; R K Singh

    2004-08-01

    The HgO-added YBa2Cu3O7- (YBCO) superconductor has been studied for its structural and superconducting properties. Polycrystalline YBCO samples were synthesized through solid-state reaction method by adding HgO in different concentrations without using oxygen annealing. All the samples showed a sharp superconducting transition temperature around 90 K. The X-ray diffraction patterns of all the samples revealed monophasic Y-123 nature. The structural studies were carried out by neutron scattering and Rietveld analysis. The neutron scattering revealed that Hg is not incorporated in the Y-123 system and has shown optimum oxygen concentration. The significant role played by the HgO is to provide oxygen ambient through its decomposition, thus changing the oxygen balance in favour of high Cu-valence state.

  3. Magnetic fields of HgMn stars

    CERN Document Server

    Hubrig, S; Ilyin, I; Korhonen, H; Schoeller, M; Savanov, I; Arlt, R; Castelli, F; Curto, G Lo; Briquet, M; Dall, T H

    2012-01-01

    The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. We re-analyse available spectropolarimetric material by applying the moment technique on spectral lines of inhomogeneously distributed elements separately. Furthermore, we present new determinations of the mean longitudinal magnetic field for the HgMn star HD65949 and the hotter analog of HgMn stars, the PGa star HD19400, using FORS2 installed at the VLT. We also give new measurements of the eclipsing system AR Aur with a primary star of HgMn peculiarity which were obtained with the SOFIN spectropolarimeter installed at the Nordic Optical Telescope. We downloaded from the ESO archive the publically available HARPS spectra for eight HgMn stars and one normal and one superficially normal B-type star obtained in 2010. The application of the moment technique to the HARPS and SOFIN spectra allowed us to study the presence of the longitudina...

  4. HgCdTe barrier infrared detectors

    Science.gov (United States)

    Kopytko, M.; Rogalski, A.

    2016-05-01

    In the last decade, new strategies to achieve high-operating temperature (HOT) detectors have been proposed, including barrier structures such as nBn devices, unipolar barrier photodiodes, and multistage (cascade) infrared detectors. The ability to tune the positions of the conduction and valence band edges independently in a broken-gap type-II superlattices is especially helpful in the design of unipolar barriers. This idea has been also implemented in HgCdTe ternary material system. However, the implementation of this detector structure in HgCdTe material system is not straightforward due to the existence of a valence band discontinuity (barrier) at the absorber-barrier interface. In this paper we present status of HgCdTe barrier detectors with emphasis on technological progress in fabrication of MOCVD-grown HgCdTe barrier detectors achieved recently at the Institute of Applied Physics, Military University of Technology. Their performance is comparable with state-of-the-art of HgCdTe photodiodes. From the perspective of device fabrication their important technological advantage results from less stringent surface passivation requirements and tolerance to threading dislocations.

  5. Spatial-temporal dynamics and sources of total Hg in a hydroelectric reservoir in the Western Amazon, Brazil.

    Science.gov (United States)

    Pestana, I A; Bastos, W R; Almeida, M G; de Carvalho, D P; Rezende, C E; Souza, C M M

    2016-05-01

    Damming rivers to construct hydroelectric reservoirs results in a series of impacts on the biogeochemical Hg cycle. For example, modifying the hydrodynamics of a natural watercourse can result in the suspension and transport of Hg deposits in the water column, which represents an exposure risk for biota. The objective of this study was to evaluate the influences of seasonality on the dispersion of total Hg in the Hydroelectric Power Plant (HPP)-Samuel Reservoir (Porto Velho/Brazil). Sampling campaigns were performed during the three following hydrological periods characteristic of the region: low (Oct/2011), ebbing (May/2012), and high (Feb/2013) water. Sediment profiles, suspended particulate matter (SPM), and aquatic macrophytes (Eicchornia crassipes and Oryza spp.) were collected, and their Hg concentrations and isotopic and elemental C and N signatures were determined. The drainage basin significantly influenced the SPM compositions during all the periods, with a small autochthonous influence from the reservoir during the low water. The highest SPM Hg concentrations inside the reservoir were observed during the high water period, suggesting that the hydrodynamics of this environment favor the suspension of fine SPM, which has a higher Hg adsorption capacity. The Hg concentrations in the sediment profiles were ten times lower than those in the SPM, indicating that large particles with low Hg concentrations were deposited to form the bottom sediment. Hg concentrations were higher in aquatic macrophyte roots than in their leaves and appeared to contribute to the formation of SPM during the low water period. In this environment, Hg transport mainly occurs in SPM from the Jamari River drainage basin, which is the primary source of Hg in this environment.

  6. Magnetic properties of fluorinated Pb-doped Hg-1223 high Tc superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hamdan, N.M.; Sastry, P.V.P.S.S.; Schwartz, J.

    2001-09-23

    Fluorination of Pb-doped HgBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Hg-1223) system was investigated. Structural and magnetic measurements reveal that fluorine addition promotes the phase formation, optimize the charge carrier concentration, and enhance flux pinning. We report an increase in both the transition temperature and the critical current density through controlled fluorine incorporation. Even a possible change in the pinning mechanism in this technologically important system is suggested.

  7. Mercury methylation and reduction potentials in marine water: An improved methodology using {sup 197}Hg radiotracer

    Energy Technology Data Exchange (ETDEWEB)

    Koron, Neza [National Institute of Biology, Marine Biology Station, Fornace 41, 6330 Piran (Slovenia); Bratkic, Arne [Department of Environmental Sciences, ' Jozef Stefan' Institute, Jamova 39, 1000 Ljubljana (Slovenia); Ribeiro Guevara, Sergio, E-mail: ribeiro@cab.cnea.gov.ar [Laboratorio de Analisis por Activacion Neutronica, Centro Atomico Bariloche, Av. Bustillo km 9.5, 8400 Bariloche (Argentina); Vahcic, Mitja; Horvat, Milena [Department of Environmental Sciences, ' Jozef Stefan' Institute, Jamova 39, 1000 Ljubljana (Slovenia)

    2012-01-15

    A highly sensitive laboratory methodology for simultaneous determination of methylation and reduction of spiked inorganic mercury (Hg{sup 2+}) in marine water labelled with high specific activity radiotracer ({sup 197}Hg prepared from enriched {sup 196}Hg stable isotope) was developed. A conventional extraction protocol for methylmercury (CH{sub 3}Hg{sup +}) was modified in order to significantly reduce the partitioning of interfering labelled Hg{sup 2+} into the final extract, thus allowing the detection of as little as 0.1% of the Hg{sup 2+} spike transformed to labelled CH{sub 3}Hg{sup +}. The efficiency of the modified CH{sub 3}Hg{sup +} extraction procedure was assessed by radiolabelled CH{sub 3}Hg{sup +} spikes corresponding to concentrations of methylmercury between 0.05 and 4 ng L{sup -1}. The recoveries were 73.0{+-}6.0% and 77.5{+-}3.9% for marine and MilliQ water, respectively. The reduction potential was assessed by purging and trapping the radiolabelled elemental Hg in a permanganate solution. The method allows detection of the reduction of as little as 0.001% of labelled Hg{sup 2+} spiked to natural waters. To our knowledge, the optimised methodology is among the most sensitive available to study the Hg methylation and reduction potential, therefore allowing experiments to be done at spikes close to natural levels (1-10 ng L{sup -1}). - Highlights: Black-Right-Pointing-Pointer Inorganic mercury methylation and reduction in marine water were studied. Black-Right-Pointing-Pointer High specific activity {sup 197}Hg was used to label Hg{sup 2+} spikes at natural levels. Black-Right-Pointing-Pointer Methylmercury extraction had 73% efficiency for 0.05-4 ng L{sup -1} levels. Black-Right-Pointing-Pointer High sensibility to assess methylation potentials, below 0.1% of the spike. Black-Right-Pointing-Pointer High sensibility also for reduction potentials, as low as 0.001% of the spike.

  8. Mercury and selenium in stranded Indo-Pacific humpback dolphins and implications for their trophic transfer in food chains.

    Directory of Open Access Journals (Sweden)

    Duan Gui

    Full Text Available As top predators in the Pearl River Estuary (PRE of China, Indo-Pacific humpback dolphins (Sousa chinensis are bioindicators for examining regional trends of environmental contaminants in the PRE. We examined samples from stranded S. chinensis in the PRE, collected since 2004, to study the distribution and fate of total mercury (THg, methylmercury (MeHg and selenium (Se in the major tissues, in individuals at different ages and their prey fishes from the PRE. This study also investigated the potential protective effects of Se against the toxicities of accumulated THg. Dolphin livers contained the highest concentrations of THg (32.34±58.98 µg g(-1 dw and Se (15.16±3.66 µg g(-1 dw, which were significantly different from those found in kidneys and muscles, whereas the highest residue of MeHg (1.02±1.11 µg g(-1 dw was found in dolphin muscles. Concentrations of both THg and MeHg in the liver, kidney and muscle of dolphins showed a significantly positive correlation with age. The biomagnification factors (BMFs of inorganic mercury (Hginorg in dolphin livers (350× and MeHg in muscles (18.7× through the prey fishes were the highest among all three dolphin tissues, whereas the BMFs of Se were much lower in all dolphin tissues. The lower proportion of MeHg in THg and higher Se/THg ratios in tissues were demonstrated. Our studies suggested that S. chinensis might have the potential to detoxify Hg via the demethylation of MeHg and the formation of tiemannite (HgSe in the liver and kidney. The lower threshold of hepatic THg concentrations for the equimolar accumulation of Se and Hg in S. chinensis suggests that this species has a greater sensitivity to THg concentrations than is found in striped dolphins and Dall's porpoises.

  9. Complexation of Hg with phytochelatins is important for plant Hg tolerance

    National Research Council Canada - National Science Library

    CARRASCO‐GIL, SANDRA; ÁLVAREZ‐FERNÁNDEZ, ANA; SOBRINO‐PLATA, JUAN; MILLÁN, ROCÍO; CARPENA‐RUIZ, RAMÓN O; LEDUC, DANIKA L; ANDREWS, JOY C; ABADÍA, JAVIER; HERNÁNDEZ, LUÍS E

    2011-01-01

    Three‐week‐old alfalfa ( Medicago sativa ), barley ( Hordeum vulgare ) and maize ( Zea mays ) were exposed for 7 d to 30  µ m of mercury (HgCl 2 ) to characterize the Hg speciation in root, with no symptoms of being poisoned...

  10. Temporal Characteristics of Emission of Working Mixtures of a HgBr/HgCl Excimer Lamp

    Science.gov (United States)

    Malinin, A. N.; Guĭvan, N. N.; Shimon, L. L.; Polyak, A. V.; Zubrilin, N. G.; Shchedrin, A. I.

    2001-12-01

    Results of a study of temporal characteristics of the emission of gas-discharge plasma of atmospheric pressure in multicomponent mixtures (mercury dibromide and dichloride with helium and additions of molecular nitrogen and xenon) of working media of HgBr/HgCl excimer lamps are presented. Gas-discharge plasma was produced and components of the working mixture were excited by high-frequency barrier and surface discharges occurring simultaneously. The repetition rate of the pumping pulse and its duration are 1000 Hz and ˜100 ns, respectively. It is found that the amplitude and the length of emission pulses and their trailing edge are modified in HgBr2: HgCl2: Xe: He and HgBr2: HgCl2: N2: He mixtures when xenon and molecular nitrogen are added, as compared to a HgBr2: HgCl2: He mixture. Regularities observed in temporal characteristics of gas-discharge plasma emission are discussed.

  11. Ground-state potential energy curves of LiHg, NaHg, and KHg revisited

    Science.gov (United States)

    Thiel, Linda; Hotop, Hartmut; Meyer, Wilfried

    2003-11-01

    We present the results of large-scale CCSD(T) calculations on the potential energy curves for the ground states of LiHg, NaHg, and KHg. In these calculations, the Hg20+ core is simulated by a pseudopotential which has been adjusted to reproduce experimental excitation and ionization energies of the Hg atom at the coupled-cluster level. Moreover, we apply a weighted multiproperty fitting procedure to determine reliable potentials for LiHg, NaHg, and KHg which reproduce the available experimental results. In the case of LiHg, this best-fit potential is based solely on experimental data and its agreement with our calculated potential supports our computational procedure. For NaHg and KHg the experimental data had to be complemented by theoretical results in order to fix a best-fit potential. Our potentials and those proposed previously are evaluated by comparing calculated scattering cross sections and vibrational energy levels with the available experimental data.

  12. Sensing Hg(II) in vitro and in vivo using a benzimidazole substituted BODIPY.

    Science.gov (United States)

    Madhu, Sheri; Sharma, Dharmendar Kumar; Basu, Santanu Kumar; Jadhav, Sameer; Chowdhury, Arindam; Ravikanth, Mangalampalli

    2013-10-07

    A multisignaling Hg(II) sensor based on a benzimidazole substituted BODIPY framework was designed, which displays excellent selectively toward Hg(II) in vitro and in vivo. Optical and fluorogenic measurements in solution reveal that the sensor can detect mercury ions at submicromolar concentrations, with high specificity. The detection of Hg(II) is associated with a blue-shift in optical spectra and a simultaneous increase in the fluorescence quantum yield of the sensor, which is attributed to a decrease in charge delocalization and inhibition of photoinduced electron transfer upon binding to Hg(II). Using several spectroscopic measurements, it is shown that the binding mechanism involves two sensor molecules, where lone pairs of the benzimidazole nitrogen coordinate to a single mercury ion. The utility of this BODIPY sensor to detect Hg(II) in vivo was demonstrated by fluorescence imaging and spectroscopy of labeled human breast adenocarcinoma cells. While average emission intensity of the sensor over a large number of cells increases with incubated mercury concentrations, spatially resolved fluorescence spectroscopy performed on individual cells reveals clear spectral blue-shifts from a subensemble of sensors, corroborating the detection of Hg(II). Interestingly, the emission spectra at various submicrometer locations within cells exhibited considerable inhomogeneity in the extent of blue-shift, which demonstrates the potential of this sensor to monitor the local (effective) concentration of mercury ions within various subcellular environments.

  13. Quasiparticle excitations in superdeformed {sup 192}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Carpenter, M.P.; Janssens, R.V.F. [and others

    1995-08-01

    The nucleus {sup 192}Hg plays a pivotal role for superdeformation in the mass 190 region, since calculations of single-particle levels show large shell-gaps for the superdeformed (SD) shape at N = 112 and Z = 80. As a result, {sup 192}Hg is referred to as the doubly magic SD nucleus for the A = 190 region. In previous studies, only one superdeformed band was observed in this nucleus, and this fact was cited as indirect evidence that large shell gaps do indeed exist at the proposed particle numbers.

  14. Electric field gradients in Hg compounds

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

    2012-01-01

    We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved by compar......We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved...

  15. Studies on photoinduced effects in pulse-electrodeposited Ag/Hg-1212/CdSe hetero-nanostructures

    Indian Academy of Sciences (India)

    D D Shivagan; P M Shirage; S H Pawar

    2002-05-01

    Metal/superconductor/semiconductor (Ag/Hg-1212/CdSe) hetero-nanostructures have been fabricated using pulse-electrodeposition technique and are characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The junction capacitance of Ag/Hg-1212, Hg-1212/CdSe and Ag/Hg-1212/CdSe heterojunctions is measured in dark and under laser irradiation at room temperature. The nature of the junction formed and built-in-junction potentials were determined. The increase in carrier concentration across the junction due to photo-irradiation has been observed.

  16. HgNO3 sensitivity of AlGaN/GaN field effect transistors functionalized with phytochelating peptides

    Science.gov (United States)

    Rohrbaugh, Nathaniel; Hernandez-Balderrama, Luis; Kaess, Felix; Kirste, Ronny; Collazo, Ramon; Ivanisevic, Albena

    2016-06-01

    This study examined the conductance sensitivity of AlGaN/GaN field effect transistors in response to varying Hg/HNO3 solutions. FET surfaces were covalently functionalized with phytochelatin-5 peptides in order to detect Hg in solution. Results showed a resilience of peptide-AlGaN/GaN bonds in the presence of strong HNO3 aliquots, with significant degradation in FET ID signal. However, devices showed strong and varied response to Hg concentrations of 1, 10, 100, and 1000 ppm. The gathered statistically significant results indicate that peptide terminated AlGaN/GaN devices are capable of differentiating between Hg solutions and demonstrate device sensitivity.

  17. Characterization of Hg-phytochelatins complexes in vines (Vitis vinifera cv Malbec) as defense mechanism against metal stress.

    Science.gov (United States)

    Spisso, Adrian A; Cerutti, Soledad; Silva, Fernanda; Pacheco, Pablo H; Martinez, Luis D

    2014-06-01

    An approach to understand vines (Vitis vinifera) defense mechanism against heavy metal stress by isolation and determination of Hg-phytochelatins (PCs) complexes was performed. PCs are important molecules involved in the control of metal concentration in plants. PCs complex toxic metals through -SH groups and stores them inside cells vacuole avoiding any toxic effect of free metals in the cytosol. The Hg-PCs identification was achieved by determination of Hg and S as hetero-tagged atoms. A method involving two-dimensional chromatographic analysis coupled to atomic spectrometry and confirmation by tandem mass spectrometry is proposed. An approach involving size exclusion chromatography coupled to inductively coupled plasma mass spectrometry on roots, stems, and leaves extracts describing Hg distribution according to molecular weight and sulfur associations is proposed for the first time. Medium-low molecular weight Hg-S associations of 29-100 kDa were found, suggesting PCs presence. A second approach employing reversed-phase chromatography coupled to atomic fluorescence spectrometry analysis allowed the determination of Hg-PCs complexes within the mentioned fractions. Chromatograms showed Hg-PC2, Hg-PC3 and Hg-PC4 presence only in roots. Hg-PCs presence in roots was confirmed by ESI-MS/MS analysis.

  18. 40 CFR 60.45Da - Standard for mercury (Hg).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for mercury (Hg). 60.45Da... for mercury (Hg). (a) For each coal-fired electric utility steam generating unit other than an IGCC... gases that contain mercury (Hg) emissions in excess of each Hg emissions limit in paragraphs...

  19. MBE Growth and Characterization of Hg Based Compounds and Heterostructures

    Science.gov (United States)

    2002-06-03

    The molecular beam epitaxy ( MBE ) growth of Mercury Cadmium Telluride (Hg(1-x)Cd(x)Te) alloys and type III HgTe/Hg(1-x)Cd(x)Te heterostructures has...been discussed, including similarities and differences between the (0 0 1) and (1 1 2)Beta orientations. Furthermore, the MBE growth of HgTe-based

  20. Removal and recovery of Hg(II) from aqueous solution using chitosan-coated cotton fibers.

    Science.gov (United States)

    Qu, Rongjun; Sun, Changmei; Ma, Fang; Zhang, Ying; Ji, Chunnuan; Xu, Qiang; Wang, Chunhua; Chen, Hou

    2009-08-15

    Two types of chitosan-coated cotton fibers (SCCH and RCCH) were applied to remove and recover Hg(II) ions in aqueous solution. The adsorption kinetics and isotherms of the two fibers for Hg(II) were investigated at different temperatures. The results revealed that the adsorption kinetic processes of SCCH and RCCH fibers for Hg(II) followed the pseudo second-order model at lower temperatures and the pseudo first-order model at higher temperatures. Both the Langmuir and Freundlich models well described the adsorption isotherms of SCCH and RCCH fibers for Hg(II) in the temperature range studied. SCCH and RCCH fibers selectively adsorbed Hg(II) from binary ion systems in the presence of Pb(II), Cu(II), Ni(II), Cd(II), Zn(II), Co(II), Mn(II) and Ag(I). Increased temperature was beneficial to adsorption. The recovery of Hg(II) from aqueous solutions was also studied as a function of sample flow rate and volume, concentration and volume of eluent, elution rate, quantity of adsorbents added and concomitant ions. The results showed that the two fibers efficiently enriched and recovered Hg(II) in the presence of alkali and alkaline earth metals and some heavy metals under optimum conditions. The RCCH fiber exhibited better stability than the SCCH fiber following repeated use.

  1. Kinetics of Hg(II) adsorption and desorption in calcined mussel shells.

    Science.gov (United States)

    Peña-Rodríguez, Susana; Fernández-Calviño, David; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Núñez-Delgado, Avelino; Fernández-Sanjurjo, María José; Alvarez-Rodríguez, Esperanza

    2010-08-15

    The potential use of calcined mussel shells to purify water contaminated with mercury was evaluated. The Hg(II) adsorption and desorption kinetics were studied in batch-type and stirred-flow chamber experiments. The adsorption/desorption experiments revealed some differences between the batches of shells used. The batch of shells that displayed the greatest capacity to adsorb Hg(II), via a highly irreversible reaction, also contained more Fe and Al than the other batches. The results of the stirred-flow chamber experiments indicated a high degree of irreversibility in the process of Hg(II) adsorption in the mussel shell, and that Hg(II) was rapidly retained. The results of these experiments also revealed that the efficiency of depuration differed depending on the length of time that the system was used: when the system was operated for 55 min, depurating 162 mL of inflowing water g(-1) mussel shell, a 90% reduction in the initial concentration of Hg(II) was obtained; use of the system for 90 min, depurating 265 mL water g(-1) mussel shell, produced a 75% reduction in the initial Hg(II), and use of the system for 162.5 min, depurating 487 mL of water g(-1) mussel shell, resulted in a 50% reduction in the initial Hg(II).

  2. Phenylselenolate Mercury Alkyl Compounds, PhSeHgMe and PhSeHgEt: Molecular Structures, Protolytic Hg-C Bond Cleavage and Phenylselenolate Exchange.

    Science.gov (United States)

    Yurkerwich, Kevin; Quinlivan, Patrick J; Rong, Yi; Parkin, Gerard

    2016-01-08

    The phenylselenolate mercury alkyl compounds, PhSeHgMe and PhSeHgEt, have been structurally characterized by X-ray diffraction, thereby demonstrating that both compounds are monomeric with approximately linear coordination geometries; the mercury centers do, nevertheless, exhibit secondary Hg•••Se intermolecular interactions that serve to increase the coordination number in the solid state. The ethyl derivative, PhSeHgEt, undergoes facile protolytic cleavage of the Hg-C bond to release ethane at room temperature, whereas PhSeHgMe exhibits little reactivity under similar conditions. Interestingly, the cleavage of the Hg-C bond of PhSeHgEt is also more facile than that of the thiolate analogue, PhSHgEt, which demonstrates that coordination by selenium promotes protolytic cleavage of the mercury-carbon bond. The phenylselenolate compounds PhSeHgR (R = Me, Et) also undergo degenerate exchange reactions with, for example, PhSHgR and RHgCl. In each case, the alkyl groups preserve coupling to the (199)Hg nuclei, thereby indicating that the exchange process involves metathesis of the Hg-SePh/Hg-X groups rather than metathesis of the Hg-R/Hg-R groups.

  3. The application of 199Hg NMR and 199mHg perturbed angular correlation (PAC) spectroscopy to define the biological chemistry of HgII

    DEFF Research Database (Denmark)

    Iranzo, Olga; Thulstrup, Peter Waaben; Ryu, Seung-baek;

    2007-01-01

    H values and at peptide/HgII ratios of 3:1 with an unusual trigonal thiolate coordination mode. The resulting HgII complexes are good water-soluble models for HgII binding to the protein MerR. We have carried out a parallel study using 199Hg NMR and 199mHg perturbed angular correlation (PAC) spectroscopy...... to characterize the distinct species that are generated under different pH conditions and peptide TRI L9C/HgII ratios. These studies prove for the first time the formation of [Hg{(TRI L9C)2-(TRI L9C H)}], a dithiolate-HgII complex in the hydrophobic interior of the three-stranded coiled coil (TRI L9C)3. 199Hg NMR...... and 199mHg PAC data demonstrate that this dithiolate-HgII complex is different from the dithiolate [Hg(TRI L9C)2], and that the presence of third -helix, containing a protonated cysteine, breaks the symmetry of the coordination environment present in the complex [Hg(TRI L9C)2]. As the pH is raised...

  4. Characterization of Electronic Materials HgZnSe and HgZnTe Using Innovative and Conventional Techniques

    Science.gov (United States)

    Tanton, George; Kesmodel, Roy; Burden, Judy; Su, Ching-Hua; Cobb, Sharon D.; Lehoczky, S. L.

    2000-01-01

    HgZnSe and HgZnTe are electronic materials of interest for potential IR detector and focal plane array applications due to their improved strength and compositional stability over HgCdTe, but they are difficult to grow on Earth and to fully characterize. Conventional contact methods of characterization, such as Hall and van der Paw, although adequate for many situations are typically labor intensive and not entirely suitable where only very small samples are available. To adequately characterize and compare properties of electronic materials grown in low earth orbit with those grown on Earth, innovative techniques are needed that complement existing methods. This paper describes the implementation and test results of a unique non-contact method of characterizing uniformity, mobility, and carrier concentration together with results from conventional methods applied to HgZnSe and HgZnTe. The innovative method has advantages over conventional contact methods since it circumvents problems of possible contamination from alloying electrical contacts to a sample and also has the capability to map a sample. Non- destructive mapping, the determination of the carrier concentration and mobility at each place on a sample, provides a means to quantitatively compare, at high spatial resolution, effects of microgravity on electronic properties and uniformity of electronic materials grown in low-Earth orbit with Earth grown materials. The mapping technique described here uses a 1mm diameter polarized beam of radiation to probe the sample. Activation of a magnetic field, in which the sample is placed, causes the plane of polarization of the probe beam to rotate. This Faraday rotation is a function of the free carrier concentration and the band parameters of the material. Maps of carrier concentration, mobility, and transmission generated from measurements of the Faraday rotation angles over the temperature range from 300K to 77K will be presented. New information on band parameters

  5. Magnetic fields of HgMn stars

    DEFF Research Database (Denmark)

    Hubrig, S.; Gonzalez, J. F.; Ilyin, I.

    2012-01-01

    Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have fai...

  6. Mercury in the gold mining district of San Martin de Loba, South of Bolivar (Colombia).

    Science.gov (United States)

    Olivero-Verbel, Jesus; Caballero-Gallardo, Karina; Turizo-Tapia, Alexi

    2015-04-01

    Gold mining is responsible for most Hg pollution in developing countries. The aims of this study were to assess the levels of total Hg (T-Hg) in human hair, fish, water, macrophyte, and sediment samples in the gold mining district of San Martin de Loba, Colombia, as well as to determine fish consumption-based risks for T-Hg ingestion. T-Hg levels were measured by electrothermal atomization and atomic absorption spectroscopy. The overall mean T-Hg level in hair for humans in the mining district of San Martin de Loba was 2.12 μg/g, whereas for the reference site, Chimichagua, Cesar, it was 0.58 μg/g. Mean T-Hg levels were not different when considered within localities belonging to the mining district but differed when the comparison included Chimichagua. T-Hg levels in examined locations were weakly but significantly associated with age and height, as well as with fish consumption, except in San Martin de Loba. High T-Hg concentrations in fish were detected in Pseudoplatystoma magdaleniatum, Caquetaia kraussii, Ageneiosus pardalis, Cyrtocharax magdalenae, and Triportheus magdalenae, whereas the lowest appeared in Prochilodus magdalenae and Hemiancistrus wilsoni. In terms of Hg exposure due to fish consumption, only these last two species offer some guarantee of low risk for Hg-related health problems. Water, floating macrophytes, and sediments from effluents near mining sites also had high Hg values. In mines of San Martin de Loba and Hatillo de Loba, for instance, the geoaccumulation index (I(geo)) for sediments reached values greater than 6, indicating extreme pollution. In short, these data support the presence of a high Hg-polluted environment in this mining district, with direct risk for deleterious effects on the health of the mining communities.

  7. Relationship Between Soil Properties and Different Fractions of Soil Hg

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing, China. Results showed that clay (< 2 m) could increase water-soluble Hg (r = 0.700*). Soil organic matter (OM) could enhance the increase of elemental Hg (r = 0.674*). The higher the base saturation percentage (BSP), the more the residual Hg (r = 0.684*). Organic Hg, the sum of acid-soluble organic Hg. and alkali-soluble Hg, was positively affected by silt (2~20μm) but negatively affected by pH, with the direct path coefficients amounting to 1.0487 and 0.5121, respectively. The positive effect of OM and negative effect of BSP on organic Hg were the most significant, with the direct path coefficients being 0.7614 and -0.8527, respectively. The indirect effect of clay (< 2 μm) via BSP (path coefficient = 0.4186) was the highest, showing that the real influencing factor in the effect of clay (< 2 μm) on acid-soluble organic Hg was BSP. Since the available Hg fraction, water-soluble Hg, was positively affected by soil clay content, and the quite immobile and not bioavailable residual Hg by soil BSP, suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils.

  8. Can Nassarius reticulatus be used as a bioindicator for Hg contamination? Results from a longitudinal study of the Portuguese coastline.

    Science.gov (United States)

    Coelho, J P; Pimenta, J; Gomes, R; Barroso, C M; Pereira, M E; Pardal, M A; Duarte, A

    2006-06-01

    The focus of this work is to explore the use of the netted whelk, Nassarius reticulatus (L.), as an indicator of mercury (Hg) contamination, by assessing the concentration of Hg in the sediments and in the whelk along the entire Portuguese coast. Total Hg concentrations ranged from below the detection limit (0.01 ng absolute mercury) up to 0.87 mg kg(-1) dry weight (dwt) in sediments and between 0.06 and 1.02 mg kg(-1) (dwt) for organisms, with no significant differences between males and females. Although organic mercury was not detected in the sediments, it represented, on average, 52% of the total Hg in the whelk tissues, and as high as 88% in some cases, suggesting mercury accumulation from dietary intake. Significant negative correlations were found between the total Hg concentrations in the sediments and the log(10) of Hg concentrations in whelk tissues males (r=-0.64; P<0.01) and females (r=-0.52; P<0.01) indicating that the species is a poor indicator of Hg contamination. Nevertheless, since the highest concentrations of organic mercury in the whelk tissues were found in the least contaminated areas, this species must be highly relevant in the trophic web, namely on the possible biomagnification of mercury. The high dietary mercury accumulation from feeding on carrion and the low bioavailability of mercury to whelks in estuarine sediments may be the basis of the mercury accumulation pattern in N. reticulatus.

  9. Invertebrate mercury bioaccumulation in permanent, seasonal, and flooded rice wetlands within California's Central Valley

    Science.gov (United States)

    Ackerman, Joshua T.; Miles, A. Keith; Eagles-Smith, Collin A.

    2010-01-01

    We examined methylmercury (MeHg) bioavailability in four of the most predominant wetland habitats in California's Central Valley agricultural region during the spring and summer: white rice, wild rice, permanent wetlands, and shallowly-flooded fallow fields. We sampled MeHg and total mercury (THg) concentrations in two aquatic macroinvertebrate taxa at the inlets, centers, and outlets of four replicated wetland habitats (8 wetlands total) during two time periods bounding the rice growing season and corresponding to flood-up and pre-harvest (96 total samples). In general, THg concentrations (mean ± standard error) in Notonectidae (Notonecta, back swimmers; 1.18 ± 0.08 µg g− 1 dry weight [dw]) were higher than in Corixidae (Corisella, water boatmen; 0.89 ± 0.06 µg g− 1 dw, MeHg: 0.74 ± 0.05 µg g− 1 dw). MeHg concentrations were correlated with THg concentrations in Corixidae (R2 = 0.80) and 88% of THg was in the MeHg form. Wetland habitat type had an important influence on THg concentrations in aquatic invertebrates, but this effect depended on the sampling time period and taxa. In particular, THg concentrations in Notonectidae, but not Corixidae, were higher in permanent wetlands than in white rice, wild rice, or shallowly-flooded fallow fields. THg concentrations in Notonectidae were higher at the end of the rice growing season than near the time of flood-up, whereas THg concentrations in Corixidae did not differ between time periods. The effect of wetland habitat type was more prevalent near the end of the rice growing season, when Notonectidae THg concentrations were highest in permanent wetlands. Additionally, invertebrate THg concentrations were higher at water outlets than at inlets of wetlands. Our results indicate that although invertebrate THg concentrations increased from the time of flood-up to draw-down of wetlands, temporarily flooded habitats such as white rice, wild rice, and shallowly-flooded fallow fields did not

  10. Human exposure to methylmercury through rice intake in mercury mining areas, Guizhou province, China.

    Science.gov (United States)

    Feng, Xinbin; Li, Ping; Qiu, Guangle; Wang, Shaofeng; Li, Guanghui; Shang, Lihai; Meng, Bo; Jiang, Hongmei; Bai, Weiyang; Li, Zhonggen; Fu, Xuewu

    2008-01-01

    The toxicity of methylmercury (Me-Hg) has caused widespread public human concern as a result of several widely publicized disasters. Me-Hg is highly toxic, and the nervous system is its principal target tissue for humans. Although the general population is primarily exposed to Me-Hg through contaminated fish and marine mammals, in Hg mining areas a long history of mining activities can produce serious Hg pollution to the local environment In a study of 98 persons from the Wanshan Hg mining area, hair Me-Hg levels indicated Me-Hg exposure. Rice, the staple food of the local inhabitants also showed high total Hg (T-Hg) and Me-Hg levels. The geometric mean concentration of T-Hg and mean concentration of Me-Hg in rice samples collected from 3 villages in Wanshan Hg mining area were 36.2 (ranging from 4.9 to 214.7), and 8.5 (ranging from 1.9 to 27.6) microg/kg, respectively, which were significantly elevated compared to the rice samples collected from a reference area, where the mean T-Hg and Me-Hg concentrations were 7.0 (3.2-15.1) and 2.5 (0.8-4.3) microg/kg, respectively. Pork meat, vegetable, and drinking water samples collected in Wanshan Hg mining area contained highly elevated T-Hg, but very low levels of Me-Hg. The relationships between the estimated rice Me-Hg intake and hair Me-Hg levels (r = 0.65, p levels indeed was the main route of Me-Hg exposure for the local residents in the Wanshan Hg mining area. From our study, we can conclude that the main human exposure to Me-Hg via food consumption is not restricted to fish, but in some cases in mining areas of China to frequent rice meals.

  11. Mercury (Hg) emissions from domestic biomass combustion for space heating.

    Science.gov (United States)

    Huang, Jiaoyan; Hopke, Philip K; Choi, Hyun-Deok; Laing, James R; Cui, Huailue; Zananski, Tiffany J; Chandrasekaran, Sriraam Ramanathan; Rattigan, Oliver V; Holsen, Thomas M

    2011-09-01

    Three mercury (Hg) species (gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and fine particulate-bound mercury (PBM(2.5))) were measured in the stack of a small scale wood combustion chamber at 400°C, in the stack of an advanced wood boiler, and in two areas influenced by wood combustion. The low temperature process (lab-scale) emitted mostly GEM (∼99% when burning wood pellets and ∼95% when burning unprocessed wood). The high temperature wood boiler emitted a greater proportion of oxidized Hg (approximately 65%) than the low temperature system. In field measurements, mean PBM(2.5) concentrations at the rural and urban sites in winter were statistically significantly higher than in warmer seasons and were well correlated with Delta-C concentrations, a wood combustion indictor measured by an aethalometer (UV-absorbable carbon minus black carbon). Overall the results suggest that wood combustion may be an important source of oxidized mercury (mostly in the particulate phase) in northern climates in winter.

  12. Estimating atmospheric mercury concentrations with lichens.

    Science.gov (United States)

    Vannini, Andrea; Nicolardi, Valentina; Bargagli, Roberto; Loppi, Stefano

    2014-01-01

    The uptake kinetics of elemental gaseous Hg (Hg(0)) in three species of epiphytic lichens (Pseudevernia furfuracea, Evernia prunastri, and Xanthoria parietina) were investigated under four different Hg concentrations (10, 15, 30, and 45 μg/m(3)) and three different temperatures (10, 20, and 30 °C) with the aim of evaluating the lichen efficiency for Hg(0) accumulation and their potential use in the estimate of atmospheric concentrations of this metal in the field. The results showed that under our experimental conditions the lichens accumulated Hg according to exposure time and that the metal is not released back to the atmosphere after Hg(0) was removed from the air (clearance). Pseudevernia furfuracea showed the highest Hg accumulation capacity and Evernia prunastri showed the lowest, but in these species the metal uptake kinetics was affected by temperature. Xanthoria parietina showed an intermediate metal accumulation capacity and a Hg accumulation rate independent of temperature (in the range 10-30 °C). The use of first-order kinetics equations for Hg uptake in X. parietina and available field data on Hg bioaccumulation in this species allowed reliable estimates of atmospheric Hg concentrations in the environment.

  13. Mercury in gray wolves (Canis lupus) in Alaska: increased exposure through consumption of marine prey.

    Science.gov (United States)

    McGrew, Ashley K; Ballweber, Lora R; Moses, Sara K; Stricker, Craig A; Beckmen, Kimberlee B; Salman, Mo D; O'Hara, Todd M

    2014-01-15

    Mercury (Hg) bioaccumulates in the tissues of organisms and biomagnifies within food-webs. Gray wolves (Canis lupus) in Alaska primarily acquire Hg through diet; therefore, comparing the extent of Hg exposure in wolves, in conjunction with stable isotopes, from interior and coastal regions of Alaska offers important insight into their feeding ecology. Liver, kidney, and skeletal muscle samples from 162 gray wolves were analyzed for total mercury (THg) concentrations and stable isotopic signatures (δ(13)C, δ(15)N, and δ(34)S). Median hepatic THg concentrations were significantly higher in wolves with coastal access compared to wolves from interior Alaska. Stable isotope ratios, in conjunction with THg concentrations, provide strong evidence that coastal wolves are utilizing marine prey representing several trophic levels. The utilization of cross-ecosystem food resources by coastal wolves is clearly contributing to increased THg exposure, and may ultimately have negative health implications for these animals. © 2013 Elsevier B.V. All rights reserved.

  14. Mercury in gray wolves (Canis lupus) in Alaska: Increased exposure through consumption of marine prey

    Science.gov (United States)

    McGrew, Ashley K.; Ballweber, Lora R.; Moses, Sara K.; Stricker, Craig A.; Beckmen, Kimberlee B.; Salman, Mo D.; O’Hara, Todd M.

    2013-01-01

    Mercury (Hg) bioaccumulates in the tissues of organismsand biomagnifies within food-webs. Graywolves (Canis lupus) in Alaska primarily acquire Hg through diet; therefore, comparing the extent of Hg exposure inwolves, in conjunction with stable isotopes, from interior and coastal regions of Alaska offers important insight into their feeding ecology. Liver, kidney, and skeletal muscle samples from 162 graywolves were analyzed for total mercury (THg) concentrations and stable isotopic signatures (δ13C, δ15N, and δ34S).Median hepatic THg concentrations were significantly higher in wolves with coastal access compared to wolves from interior Alaska. Stable isotope ratios, in conjunction with THg concentrations, provide strong evidence that coastal wolves are utilizing marine prey representing several trophic levels. The utilization of cross-ecosystem food resources by coastal wolves is clearly contributing to increased THg exposure, and may ultimately have negative health implications for these animals.

  15. Mercury in gray wolves (Canis lupus) in Alaska: Increased exposure through consumption of marine prey

    Science.gov (United States)

    McGrew, Ashley K.; Ballweber, Lora R.; Moses, Sara K.; Stricker, Craig A.; Beckmen, Kimberlee B.; Salman, Mo D.; O’Hara, Todd M.

    2013-01-01

    Mercury (Hg) bioaccumulates in the tissues of organisms and biomagnifies within food-webs. Gray wolves (Canis lupus) in Alaska primarily acquire Hg through diet; therefore, comparing the extent of Hg exposure in wolves, in conjunction with stable isotopes, from interior and coastal regions of Alaska offers important insight into their feeding ecology. Liver, kidney, and skeletal muscle samples from 162 gray wolves were analyzed for total mercury (THg) concentrations and stable isotopic signatures (δ13C, δ15N, and δ34S). Median hepatic THg concentrations were significantly higher in wolves with coastal access compared to wolves from interior Alaska. Stable isotope ratios, in conjunction with THg concentrations, provide strong evidence that coastal wolves are utilizing marine prey representing several trophic levels. The utilization of cross-ecosystem food resources by coastal wolves is clearly contributing to increased THg exposure, and may ultimately have negative health implications for these animals. PMID:24056451

  16. Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

    Energy Technology Data Exchange (ETDEWEB)

    Lapanje, A. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia)], E-mail: ales.lapanje@bf.uni-lj.si; Drobne, D. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Nolde, N. [Institute Jozef Stefan, Department of Environmental Sciences, Jamova 39, 1000 Ljubljana (Slovenia); Valant, J. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Muscet, B. [Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia); Leser, V. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Rupnik, M. [Institute of Public Health, Prvomajska 1, 2000 Maribor (Slovenia); Faculty of Medicine, University of Maribor, Slomskov trg 15, 2000 Maribor (Slovenia)

    2008-06-15

    The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10 {mu}g Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed. - Isopods (Porcellio scaber) as well as their bacterial gut community from a mercury-polluted site are mercury tolerant.

  17. Organ-specific accumulation, transportation, and elimination of methylmercury and inorganic mercury in a low Hg accumulating fish.

    Science.gov (United States)

    Peng, Xiaoyan; Liu, Fengjie; Wang, Wen-Xiong

    2016-08-01

    Low mercury (Hg) concentrations down to several nanograms Hg per gram of wet tissue are documented in certain fish species such as herbivorous fish, and the underlying mechanisms remain speculative. In the present study, bioaccumulation and depuration patterns of inorganic Hg(II) and methylmercury (MeHg) in a herbivorous rabbitfish Siganus canaliculatus were investigated at organ and subcellular levels following waterborne or dietary exposures. The results showed that the efflux rate constants of Hg(II) and MeHg were 0.104 d(-1) and 0.024 d(-1) , respectively, and are probably the highest rate constants recorded in fish thus far. The dietary MeHg assimilation efficiency (68%) was much lower than those in other fish species (∼90%). The predominant distribution of MeHg in fish muscle was attributable to negligible elimination of MeHg from muscle (rabbitfish was partly explained by its unique biokinetics. Environ Toxicol Chem 2016;35:2074-2083. © 2016 SETAC.

  18. MBE HgCdTe heterostructure detectors

    Science.gov (United States)

    Schulman, Joel N.; Wu, Owen K.

    1990-01-01

    HgCdTe has been the mainstay for medium (3 to 5 micron) and long (10 to 14 micron) wavelength infrared detectors in recent years. Conventional growth and processing techniques are continuing to improve the material. However, the additional ability to tailor composition and placement of doped layers on the tens of angstroms scale using molecular beam epitaxy (MBE) provides the opportunity for new device physics and concepts to be utilized. MBE-based device structures to be discussed here can be grouped into two categories: tailored conventional structures and quantum structures. The tailored conventional structures are improvements on familiar devices, but make use of the ability to create layers of varying composition, and thus band gap, at will. The heterostructure junction can be positioned independently of doping p-n junctions. This allows the small band gap region in which the absorption occurs to be separated from a larger band gap region in which the electric field is large and where unwanted tunneling can occur. Data from hybrid MBE/liquid phase epitaxy (LPE)/bulk structures are given. Quantum structures include the HgTe-CdTe superlattice, in which the band gap and transport can be controlled by alternating thin layers (tens of angstroms thick) of HgTe and CdTe. The superlattice has been shown to exhibit behavior which is non-alloy like, including very high hole mobilities, two-dimensional structure in the absorption coefficient, resonant tunneling, and anisotropic transport.

  19. Hg Vetical Transference in Soil—Water System

    Institute of Scientific and Technical Information of China (English)

    GUOYIJUN; MOUSUSEN; 等

    1998-01-01

    Hg vertial transference in soil-water system was studied by analyzing Hg vertical ditribution in soil column after adding Hg and one of the two leacheates,deionzied water or acid rain,into soil column.The results indicated that Hg was hardly transferable in puple soil.About 86%-88% of the total soil Hg was distributed in the top layer (0-2cm) and to Hg was detected in the leakage when the purple soil column was leached by deionized water and simulated acid rain.But Hg was more movalbe in yellow soil with only about 20%-22% of the total soil Hg distributed in the top layer (0-2cm),and about 17%-25% washed out from the soil column by deionized water and simulted acid rain,Incremant in soil bulk density colud reduce Hg leaching,thus the more the Hg kept in soil,the less the Hg leached into underground water,Deionized water and acid rain almost played the same role in leaching Hg.Bentioint was most effecient in preventing Hg from vertcal transferring in the soil coulumn.

  20. Factors affecting Hg (II adsorption in soils from the Rio Negro basin (Amazon

    Directory of Open Access Journals (Sweden)

    Patricia Miretzky

    2005-06-01

    Full Text Available Mercury (II adsorption studies in top soils (top 10 cm from the Rio Negro basin show this process depends strongly on some selected parameters of the aqueous phase in contact with the soils. Maximum adsorption occurred in the pH range 3.0-5.0 (>90%. Dissolved organic matter shows an inhibitory effect on the availability of Hg (II to be adsorbed by the soils, whereas a higher chloride content of the solution resulted in a lower adsorption of Hg (II at pH 5.0. Soils with higher organic matter content were less affected by changes in the salinity. An increase in the initial Hg (II concentration increased the amount of Hg (II adsorbed by the soil and decreased the time needed to reach equilibrium. A Freundlich isotherm provided a good model for Hg (II adsorption in the two types of soil studied. The kinetics of Hg (II adsorption on Amazonian soils showed to be very fast and followed pseudo-second order kinetics. An environmental implication of these results is discussed under the real scenario present in the Negro River basin, where acidic waters are in contact with a soil naturally rich in mercury.

  1. Dynamic and static adsorption and desorption of Hg(II) ions on chitosan membranes and spheres.

    Science.gov (United States)

    Vieira, Rodrigo S; Beppu, Marisa M

    2006-05-01

    The adsorption and desorption of Hg(II) ions was studied using static and dynamic methods, employing membranes and spheres of chitosan as the adsorbent. The quantity of adsorption was influenced by chitosan crosslinking and by the adsorbent shape. The Langmuir model was applied to fit the experimental equilibrium data. Glutaraldehyde-crosslinked membranes presented a lower desorption capacity, when compared to natural membranes, but could be regenerated for use in successive cycles. Dynamic adsorption experiments suggested that the adsorption capacity depended mainly on adsorbent geometry, due to differences between surface area to mass ratio and initial concentration of Hg(II) ions. The adsorption capacity determined by the dynamic method was 65% and 77% for membranes and spheres, respectively of the value obtained static method results. A process combining dynamic adsorption and static desorption can be used to concentrate the Hg(II) ions by a factor of nearly seven (7x), when compared to the initially treated volume.

  2. Spatial and temporal variation of total mercury and methylmercury in lacustrine wetland in Korea.

    Science.gov (United States)

    Kim, Moon-Kyung; Lee, Young-Min; Zoh, Kyung-Duk

    2015-05-01

    The spatial and temporal variations of total mercury (THg) and methylmercury (MeHg) concentrations (n = 120, respectively) in water and sediments of the Yangsuri lacustrine wetland in Korea were measured. The average concentrations of THg and MeHg in surface water were 2.04 ± 1.97 and 0.05 ± 0.05 ng L(-1), respectively. The concentrations of THg and MeHg in sediments ranged from 1.28 to 85.83 and ≤0.01 to 0.35 ng g(-1), respectively, and varied depending on the location. In the vegetated zone located near residential areas, the highest concentrations of THg and MeHg in both surface water and sediments were obtained near the residential areas, especially during the fall season. This result might be due to increased methylation rate of Hg by water turnover in the fall season. While THg and MeHg concentrations in water were not correlated, they were significantly correlated in sediment (r = 0.75; P levels of mercury, especially MeHg in the wetlands, and freshwater fish species in Korea.

  3. A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento-San Joaquin Delta of California, USA

    Science.gov (United States)

    Drexler, Judith; Alpers, Charles N.; Neymark, Leonid; Paces, James B.; Taylor, Howard E.; Fuller, Christopher C.

    2016-01-01

    In this paper, we provide the first record of millennial patterns of Pb and Hg concentrations on the west coast of the United States. Peat cores were collected from two micro-tidal marshes in the Sacramento-San Joaquin Delta of California. Core samples were analyzed for Pb, Hg, and Ti concentrations and dated using radiocarbon, 210Pb, and 137Cs. Pre-anthropogenic concentrations of Pb and Hg in peat ranged from 0.60 to 13.0 µg g-1and from 6.9 to 71 ng g-1, respectively. For much of the past 6000+ years, the Delta was free from anthropogenic pollution, however, beginning in ~1425 CE, Hg and Pb concentrations, Pb/Ti ratios, Pb enrichment factors (EFs), and HgEFs all increased. Pb isotope compositions of the peat suggest that this uptick was likely caused by smelting activities originating in Asia. The next increases in Pb and Hg contamination occurred during the California Gold Rush (beginning ~1850 CE), when concentrations reached their highest levels (74 µg g-1 Pb, 990 ng g-1 Hg; PbEF = 12 and HgEF = 28). Lead concentrations increased again beginning in the ~1920s with the incorporation of Pb additives in gasoline. The phase-out of lead additives in the late 1980s was reflected in Pb isotope ratios and reductions in Pb concentrations in the surface layers of the peat. The rise and fall of Hg contamination was also tracked by the peat archive, with the highest Hg concentrations occurring just before 1963 CE and then decreasing during the post-1963 period. Overall, the results show that the Delta was a pristine region for most of its ~6700-year existence; however, since ~1425 CE, it has received Pb and Hg contamination from both global and regional sources.

  4. A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento-San Joaquin Delta of California, USA.

    Science.gov (United States)

    Drexler, Judith Z; Alpers, Charles N; Neymark, Leonid A; Paces, James B; Taylor, Howard E; Fuller, Christopher C

    2016-05-01

    In this paper, we provide the first record of millennial patterns of Pb and Hg concentrations on the west coast of the United States. Peat cores were collected from two micro-tidal marshes in the Sacramento-San Joaquin Delta of California. Core samples were analyzed for Pb, Hg, and Ti concentrations and dated using radiocarbon and (210)Pb. Pre-anthropogenic concentrations of Pb and Hg in peat ranged from 0.60 to 13.0μgg(-1)and from 6.9 to 71ngg(-1), respectively. For much of the past 6000+ years, the Delta was free from anthropogenic pollution, however, beginning in ~1425CE, Hg and Pb concentrations, Pb/Ti ratios, Pb enrichment factors (EFs), and HgEFs all increased. Pb isotope compositions of the peat suggest that this uptick was likely caused by smelting activities originating in Asia. The next increases in Pb and Hg contamination occurred during the California Gold Rush (beginning ~1850CE), when concentrations reached their highest levels (74μgg(-1) Pb, 990ngg(-1) Hg; PbEF=12 and HgEF=28). Lead concentrations increased again beginning in the ~1920s with the incorporation of Pb additives in gasoline. The phase-out of lead additives in the late 1980s was reflected in changes in Pb isotope ratios and reductions in Pb concentrations in the surface layers of the peat. The rise and subsequent fall of Hg contamination was also tracked by the peat archive, with the highest Hg concentrations occurring just before 1963CE and then decreasing during the post-1963 period. Overall, the results show that the Delta was a pristine region for most of its ~6700-year existence; however, since ~1425CE, it has received Pb and Hg contamination from both global and regional sources.

  5. Ultrasensitive detection of Hg{sup 2+} using oligonucleotide-functionalized AlGaN/GaN high electron mobility transistor

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Junjie [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Li, Jiadong; Miao, Bin; Wu, Dongmin, E-mail: dmwu2008@sinano.ac.cn [i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wang, Jine; Pei, Renjun, E-mail: rjpei2011@sinano.ac.cn [Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-08-25

    An oligonucleotide-functionalized ion sensitive AlGaN/GaN high electron mobility transistor (HEMT) was fabricated to detect trace amounts of Hg{sup 2+}. The advantages of ion sensitive AlGaN/GaN HEMT and highly specific binding interaction between Hg{sup 2+} and thymines were combined. The current response of this Hg{sup 2+} ultrasensitive transistor was characterized. The current increased due to the accumulation of Hg{sup 2+} ions on the surface by the highly specific thymine-Hg{sup 2+}-thymine recognition. The dynamic linear range for Hg{sup 2+} detection has been determined in the concentrations from 10{sup −14} to 10{sup −8} M and a detection limit below 10{sup −14} M level was estimated, which is the best result of AlGaN/GaN HEMT biosensors for Hg{sup 2+} detection till now.

  6. Measuring Hg and MeHg fluxes from dynamic systems using high resolution in situ monitoring - case study: the Sacramento-San Joaquin Delta

    Science.gov (United States)

    Fleck, J. A.; Bergamaschi, B. A.; Downing, B. D.; Lionberger, M. A.; Schoellhamer, D.; Boss, E.; Heim, W.; Stephenson, M.

    2006-12-01

    Quantifying net loads in tidal systems is difficult, time consuming, and often very expensive. Owing to the relatively rapid nature of tidal exchange, numerous measurements are required in a brief amount of time to accurately quantify constituent fluxes between a tidal wetland and its surrounding waters. Further complicating matters, the differences in chemical concentrations of a constituent between the flood and ebb tides are often small, so that the net export of the constituent is orders of magnitude smaller than the bulk exchange in either direction over the tidal cycle. Thus, high-resolution sampling coupled with high-sensitivity instruments over an adequate amount of time is required to accurately determine a net flux. These complications are exacerbated for mercury species because of the difficulties related to clean sampling and trace-level analysis. The USGS currently is collecting data to determine the fluxes of total mercury (Hg) and methyl-Hg (MeHg) in dissolved and particulate phases at Browns Island in the San Francisco Bay-Delta, a tidally influenced estuarine system. Our field deployment package consists of an upward-looking current profiler to quantify water flux, and an array of other instruments measuring the following parameters: UV absorption, DO, pH, salinity, temperature, water depth, optical backscatter, fluorescence, and spectral attenuation. Measurements are collected at 30-minute intervals for seasonal, month-long deployments in the main slough of Brown's Island. We infer Hg and MeHg concentrations by using multivariate analysis of spectral absorbance and fluorescence properties of the continuous measurements, and comparing them to those of discrete samples taken hourly over a 25-hour tidal cycle for each deployment. Preliminary results indicate that in situ measurements can be used to predict MeHg concentrations in a tidal wetland slough in both the filtered (r2=0.96) and unfiltered (r2=0.95) fractions. Despite seasonal differences in

  7. Superconductivity in Hg-Substituted BaPb0.75Bi0.25O3

    Institute of Scientific and Technical Information of China (English)

    Yong-Liang Chen; Ya-Jing Cui; Yong Zhang; Cui-Hua Cheng; Yong Zhao

    2008-01-01

    A series of Hg-doped BaPb0.75Bi0.25O3 with a nominal composition of BaPb0.75-xHgxBi0.25O3 (x=0 to 0.40 with 0.05 intervals) have been synthesized by solid-state reaction. These compounds exhibit a cubic perovskite-related structure with the lattice parameter being expanded by Hg doping. Superconducting transition temperature Tc and superconducting volume fraction are suppressed by Hg doping in the low doping level region (0≤ x ≤0.25). However, further increasing Hg content makes the superconductivity recovered at x>0.3. The superconductivity suppression in Hg-doped BaPb0.75Bi0.25O3 can be explained by the decrease of electron carrier concentration as well as the band- narrowing-induced electron localization.

  8. Responses of membrane protection enzyme system of tobacco leaves on Hg, Cd and Pb stresses in soil.

    Science.gov (United States)

    Yan, Chong Ling; Lin, Peng; Wang, Xiao Rong

    2002-09-01

    Pot experiment was used to study the responses of membrane protection enzyme system of tobacco leaves on Hg, Cd and Pb stresses in soil. The results showed that POD activity gradually increased with increasing concetrations of Hg, Cd and Pb. CAT and SOD activity gradually decreased under three heavy metals common existing and SOD variation curve showed unimodal curve under single or two elements existing with increase of concentration of Hg, Cd and Pb. The effects of Hg, Cd and Pb in soil: three elemets together > two elements together > single element only. The effects resulted in an imbalance--activated oxygen produce and scavenge and physiological biochemical process disorder. There was a synergistic action for the effect of Hg, Cd and Pb in soil on membrane protection enzyme system in tobacco leaves.

  9. Distribution of total mercury and methylmercury around the small-scale gold mining area along the Cikaniki River, Bogor, Indonesia.

    Science.gov (United States)

    Tomiyasu, Takashi; Kodamatani, Hitoshi; Hamada, Yuriko Kono; Matsuyama, Akito; Imura, Ryusuke; Taniguchi, Yoko; Hidayati, Nuril; Rahajoe, Joeni Setijo

    2017-01-01

    This study investigates the distribution of total mercury (T-Hg) and methylmercury (MeHg) in the soil and water around the artisanal and small-scale gold mining (ASGM) area along the Cikaniki River, West Java, Indonesia. The concentration of T-Hg and MeHg in the forest soil ranged from 0.07 to 16.7 mg kg(-1) and from Mercury deposited on the soil surface can be trapped and retained by organic matter and subjected to methylation. The slope of the line obtained for the T-Hg vs. TOC plot became larger near the ASGM villages, implying a higher rate of mercury deposition in these areas. In contrast, the plots of MeHg vs. TOC fell along the same trend line regardless of the distance from the ASGM village. Organic carbon content may be a predominant factor in controlling MeHg formation in forest soils. The T-Hg concentration in the river water ranged from 0.40 to 9.6 μg L(-1). River water used for irrigation can prove to be a source of mercury for the paddy fields. The concentrations of Hg(0) and Hg(2+) in river water showed similar variations as that observed for the T-Hg concentration. The highest Hg(0) concentration of 3.2 μg L(-1) can be attributed to the waste inflow from work sites. The presence of Hg(0) in river water can become a source of mercury present in the atmosphere along the river. MeHg concentration in the river water was found to be 0.004-0.14% of T-Hg concentration, which was considerably lower than the concentrations of other Hg species. However, MeHg comprised approximately 0.2% of the T-Hg in paddy field soil. Mercury deposited from the atmosphere and the river water can be subjected to methylation. Paddy fields are very important ecosystems; therefore, the effect of MeHg on these ecosystems and human beings should be further investigated.

  10. Process of [sup 196]Hg enrichment

    Science.gov (United States)

    Grossman, M.W.; Mellor, C.E.

    1993-04-27

    A simple rate equation model shows that by increasing the length of the photochemical reactor and/or by increasing the photon intensity in said reactor, the feedstock utilization of [sup 196]Hg will be increased. Two preferred embodiments of the present invention are described, namely (1) long reactors using long photochemical lamps and vapor filters; and (2) quartz reactors with external UV reflecting films. These embodiments have each been constructed and operated, demonstrating the enhanced utilization process dictated by the mathematical model (also provided).

  11. Process of .sup.196 Hg enrichment

    Science.gov (United States)

    Grossman, Mark W.; Mellor, Charles E.

    1993-01-01

    A simple rate equation model shows that by increasing the length of the photochemical reactor and/or by increasing the photon intensity in said reactor, the feedstock utilization of .sup.196 Hg will be increased. Two preferred embodiments of the present invention are described, namely (1) long reactors using long photochemical lamps and vapor filters; and (2) quartz reactors with external UV reflecting films. These embodiments have each been constructed and operated, demonstrating the enhanced utilization process dictated by the mathematical model (also provided).

  12. Magnetic fields of HgMn stars

    DEFF Research Database (Denmark)

    Hubrig, S.; González, J. F.; Ilyin, I.

    2012-01-01

    Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have...... failed to detect magnetic fields, indicating an upper limit on the longitudinal field between 8 and 15G. In these LSD studies, assumptions were made that all spectral lines are identical in shape and can be described by a scaled mean profile. Aims. We re-analyse the available spectropolarimetric material...

  13. Of Variability, or its Absence, in HgMn Stars

    CERN Document Server

    Turcotte, S

    2003-01-01

    Current models and observations of variability in HgMn stars disagree. We present here the models that argue for pulsating HgMn stars with properties similar to those of Slowly Pulsating B Stars. The lack of observed variable HgMn stars suggests that some physical process is missing from the models. Some possibilities are discussed.

  14. Effects of Hg and Cu on the activities of soil acid phosphatase

    Institute of Scientific and Technical Information of China (English)

    XU Dong-mei; CHEN Bo; LIU Wen-li; LIU Guang-shen; LIU Wei-ping

    2007-01-01

    Comparative study on the activity and kinectic properties of acid phosphatase (ACPase) of three soils amended with Hg and Cu at constant temperature and humidity was carried out. The results indicated that the inhibition on ACPase of the three sample soils by Hg and Cu varied with the content of soil organic matter and pH, where, Soil 1 was the most seriously contaminated due to its lowest content of organic matter and the lowest pH among three samples, Soil 2 took the second place, and Soil 3was the least contaminated. Except Soil 3, the activity of soil ACPase tended to increase along with the contact time under the same type and the same concentration of heavy metal. In particular the Vmax values of ACPase in all three samples decreased with increasing Hg and Cu concentration, whereas the Km values were affected weakly. According to the change of Vmax and Km values,Cu and Hg had the same inhibition effect on soil ACPase. Both of them may be a type of compound of non-competitive and anti-competitive inhibition. Statistic analyses indicated that activities of soil ACPase and Vmax values could serve as bioindicator to partially denote the heavy metal Hg and Cu contamination degree.

  15. Toxicity Effect of Hg2+ and Cr(Ⅵ)on Alga Growth in Eutrophic Water%Hg2+与Cr(Ⅵ)对富营养化水体中藻类生长的毒性效应

    Institute of Scientific and Technical Information of China (English)

    毕东苏; 钱春龙

    2007-01-01

    [Objective]The toxicity effect of Hg2+ and Cr(Ⅵ)on alga growth in eutrophic water was studied to provide reference for biomonitoring and bioremediation of eutrophic water.[Method]The mother liquid of alga,which was separated from the eutrophic water,were put into the solutions of Hg2+and Cr(Ⅵ)with different concentrations and their mixture solution,respectively.And the toxicity effect of Hg2+ and Cr(Ⅵ)on the growth and propagation of alga in eutrophic water was observed.[Result]The alga in eutrophic water performed rather sensitive to Cr(Ⅵ)and when its concentration Was over 1 ms/L,threre was obvious effect on alga growth.The alga Was not very sensitive to Hg2+ when its concentration was lower, but its toxicity became stronger and stronger when its concentration increased to some extent and the toxicity effect of Cr(Ⅵ)on alga growth was inst on the centrary. When the ion concentration was lower than 10 ms/L,the toxicity of Hg2+ on alga was lower than that of Cr(Ⅵ).When the concentration was over 10 ms/L,the toxieity of Hg2+ exceeded that of Cr(Ⅵ).The toxicity of ion mixture solution of Hg2+ and Cr(Ⅵ)had synergism inhibition on alga,which could be performed only when the concentration was over4 mg/L.[Conclusion]The toxicity of heavy metal on alga not only related to the alga cell,but also related to the concentration of heavy metal ion.

  16. Cytotoxicity of dental composite (co)monomers and the amalgam component Hg(2+) in human gingival fibroblasts.

    Science.gov (United States)

    Reichl, Franz-Xaver; Simon, Sabine; Esters, Magalie; Seiss, Mario; Kehe, Kai; Kleinsasser, Norbert; Hickel, Reinhard

    2006-08-01

    Unpolymerized resin (co)monomers or mercury (Hg) can be released from restorative dental materials (e.g. composites and amalgam). They can diffuse into the tooth pulp or the gingiva. They can also reach the gingiva and organs by the circulating blood after the uptake from swallowed saliva. The cytotoxicity of dental composite components hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (Bis-GMA) as well as the amalgam component Hg(2+) (as HgCl(2)) and methyl mercury chloride (MeHgCl) was investigated on human gingival fibroblasts (HGFs) at two time intervals. To test the cytotoxicity of substances, the bromodeoxyuridine (BrdU) assay and the lactate dehydrogenase (LDH) assay were used. The test substances were added in various concentrations and cells were incubated for 24 or 48 h. The EC(50) values were obtained as half-maximum-effect concentrations from fitted curves. Following EC(50) values were found [BrdU: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 8.860 (0.440)/6.600(0.630), TEGDMA 1.810(0.130)/1.220(0.130), UDMA 0.120(0.010)/0.140(0.010), BisGMA 0.060(0.004)/0.040(0.002), HgCl(2) 0.015(0.001)/0.050(0.006), and MeHgCl 0.004(0.001)/0.005(0.001). Following EC(50) values were found [LDH: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 9.490(0.300)/7.890(1.230), TEGDMA 2.300(0.470)/1.950(0.310), UDMA 0.200(0.007)/0.100(0.007), BisGMA 0.070(0.005)/0.100(0.002), and MeHgCl 0.014(0.006)/0.010(0.003). In both assays, the following range of increased toxicity was found for composite components (24 and 48 h): HEMA < TEGDMA < UDMA < BisGMA. In both assays, MeHgCl was the most toxic substance. In the BrdU assay, Hg(2+) was about fourfold less toxic than MeHgCl but Hg(2+) was about fourfold more toxic than BisGMA. In the BrdU test, a significantly (P<0.05) decreased toxicity was observed for Hg(2+) at 48 h, compared to the 24 h Hg(2+)-exposure. A time depending

  17. Fully relativistic coupled cluster and DFT study of electric field gradients at Hg in 199Hg compounds

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

    2012-01-01

    We investigate the magnitude and interplay of relativistic and electron correlation effects on the electric field gradient (EFG) at the position of Hg in linear and bent HgL2 (L=CH3, Cl, Br, I) and trigonal planar [HgCl3]- complexes using four-component relativistic Dirac-Coulomb (DC) and non...

  18. A laboratory-incubated redox oscillation experiment to investigate Hg fluxes from highly contaminated coastal marine sediments (Gulf of Trieste, Northern Adriatic Sea).

    Science.gov (United States)

    Emili, A; Carrasco, L; Acquavita, A; Covelli, S

    2014-03-01

    Mercury (Hg) mobility at the sediment-water interface was investigated during a laboratory incubation experiment conducted with highly contaminated sediments (13 μg g(-1)) of the Gulf of Trieste. Undisturbed sediment was collected in front of the Isonzo River mouth, which inflows Hg-rich suspended material originating from the Idrija (NW Slovenia) mining district. Since hypoxic and anoxic conditions at the bottom are frequently observed and can influence the Hg biogeochemical behavior, a redox oscillation was simulated in the laboratory, at in situ temperature, using a dark flux chamber. Temporal variations of several parameters were monitored simultaneously: dissolved Hg (DHg) and methylmercury (MeHg), O2, NH4 (+), NO3 (-) + NO2 (-), PO4 (3-), H2S, dissolved Mn(2+), dissolved inorganic and organic carbon (DIC and DOC). Under anoxic conditions, both Hg (665 ng m(2) day(-1)) and MeHg (550 ng m(2) day(-1)) fluxed from sediments into the water column, whereas re-oxygenation caused concentrations of MeHg and Hg to rapidly drop, probably due to re-adsorption onto Fe/Mn-oxyhydroxides and enhanced demethylation processes. Hence, during anoxic events, sediments of the Gulf of Trieste may be considered as an important source of DHg species for the water column. On the contrary, re-oxygenation of the bottom compartment mitigates Hg and MeHg release from the sediment, thus acting as a natural "defence" from possible interaction between the metal and the aquatic organisms.

  19. The Chevrel phase HgMo6S8

    Directory of Open Access Journals (Sweden)

    Michel Potel

    2009-05-01

    Full Text Available The crystal structure of HgMo6S8, mercury(II hexamolybdenum octasulfide, is based on (Mo6S8S6 cluster units (overline{3} symmetry interconnected through interunit Mo—S bonds. The Hg2+ cations occupy large voids between the different cluster units and are covalently bonded to two S atoms. The Hg atoms and one S atom lie on sites with crystallographic overline{3} and 3 symmetry, respectively. Refinement of the occupancy factor of the Hg atom led to the composition Hg0.973 (3Mo6S8.

  20. Heavy metal and mineral concentrations and their relationship to histopathological findings in the bowhead whale (Balaena mysticetus)

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Cheryl [Institute of Arctic Biology, University of Alaska Fairbanks, 311 Irving I Building, Fairbanks, Alaska 99775 (United States); Department of Wildlife Management, North Slope Borough, P.O. Box 69, Barrow, Alaska 99723 (United States)], E-mail: Cheryl.Rosa@north-slope.org; Blake, John E. [Institute of Arctic Biology, University of Alaska Fairbanks, 311 Irving I Building, Fairbanks, Alaska 99775 (United States); Bratton, Gerald R. [Department of Veterinary Integrated Biosciences, Texas A and M University, College Station Texas 77843 (United States); Dehn, Larissa-A. [Institute of Arctic Biology, University of Alaska Fairbanks, 311 Irving I Building, Fairbanks, Alaska 99775 (United States); Alaska Department of Fish and Game, Division of Commercial Fisheries, 1300 College Road, Fairbanks, Alaska 99712 (United States); Gray, Matthew J. [Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, Tennessee 37996 (United States); O' Hara, Todd M. [Institute of Arctic Biology, University of Alaska Fairbanks, 311 Irving I Building, Fairbanks, Alaska 99775 (United States)

    2008-07-25

    The bowhead whale (Balaena mysticetus) is a species endangered over much of its range that is of great cultural significance and subsistence value to the Inuit of Northern Alaska. This species occupies subarctic and arctic regions presently undergoing significant ecological change and hydrocarbon development. Thus, understanding the health status of the Bering-Chukchi-Beaufort Sea (BCBS) stock of bowhead whales is of importance. In this study, we evaluated the concentrations of six essential and non-essential elements (Zn, tHg, Ag, Se, Cu and Cd) in liver and kidney of bowhead whales (n = 64). These tissues were collected from the Inuit subsistence hunt in Barrow, Wainwright and Kaktovik, Alaska between 1983 and 2001. Reference ranges of these elements (including previously reported data from 1983-1997) were developed for this species as part of a health assessment effort, and interpreted using improved aging techniques (aspartic acid racemization and baleen isotopic {sup 13}C methods) to evaluate trends over time with increased statistical power. Interactions between element concentrations and age, sex and harvest season were assessed. Age was found to be of highest significance. Sex and harvest season did not effect the concentrations of these elements, with the exception of renal Se levels, which were significantly higher in fall seasons. In addition, histological evaluation of tissues from whales collected between 1998-2001 was performed. Associations between concentrations of Cd in kidney and liver and scored histopathological changes were evaluated. Liver Cd concentration was strongly associated with the degree of lung fibromuscular hyperplasia (P = 0.001) and moderately associated with the degree of renal fibrosis (P = 0.03). Renal Cd concentration influenced the degree of lung fibromuscular hyperplasia and renal fibrosis (P = 0.01). A significant age effect was found for both pulmonary fibromuscular hyperplasia and renal fibrosis, indicating age may be a

  1. iUTAH Summer Research: Analyzing diel variations of MeHg in the Provo River, Utah

    Science.gov (United States)

    Hamilton, G. L.; Packer, B. N.; Carling, G. T.; Checketts, H. N.; Shepherd Barkdull, N.

    2016-12-01

    iUTAH is an interdisciplinary research program aimed at strengthening science for Utah's water future and funded by the National Science Foundation. iUTAH is comprised of three research areas with an overarching goal of understanding how Utah's water system operates as an integrated physical, chemical, biological, and social system. During the Summer of 2016, I participated in the iUTAH (Innovative Urban Transitions and Aridregion Hydro-sustainability) iFellows undergraduate research program. iUTAH provided the opportunity to conduct research at Brigham Young University with graduate students studying trace metal dynamics in the Provo River, Utah, USA. This report presents the chemical system evaluation of methylmercury (MeHg) during diurnal variations from snowmelt runoff. Water samples were collected during peak discharge from Soapstone Basin, a site along the Upper Provo River watershed, every hour over a 24-hour (diel) period. Sampling began at 1200 hours on June 1 and ended at 1100 hours on June 2, 2016. The results of the Provo River MeHg analysis showed dissolved MeHg had a concentration variance of 0.027 ng/L and particulate MeHg had a concentration variance of 0.056 ng/L. The variances during the diel cycle represent more than a two-fold change in concentration. The hourly MeHg concentration levels demonstrated an inverse relationship with gage height indicative of dilution. The purpose of the study is to develop a more thorough understanding of short-term variances over time and the potential affect on long-term interpretations of MeHg fluctuations in the river. The Provo River flows through Jordanelle Reservoir where there is a mercury advisory for two fish species. MeHg is a bioaccumulative neurotoxin that humans are primarily exposed to by the consumption of contaminated fish. The strong correlation between the levels of MeHg in water and fish make the river concentrations an important factor.

  2. A selective colorimetric Hg2+ probe featuring a styryl dithiaazacrown containing platinum (II) terpyridine complex through modulation of the relative strength of ICT and MLCT transitions.

    Science.gov (United States)

    Chung, Sung-Kuang; Tseng, Yong-Ren; Chen, Chan-Yu; Sun, Shih-Sheng

    2011-04-04

    A series of platinum(II) terpyridine complexes featuring an aminostilbene donor-acceptor framework was synthesized. The complex with a dithiaazacrown moiety exhibits a highly sensitive and selective colorimetric response to a Hg(2+) cation through modulation of the relative strength of ICT and MLCT transitions. The results from (1)H NMR titration suggest the existence of a weak Pt(II)···Hg(II) metallophilic interaction at low Hg(2+) concentration.

  3. Mercury and selenium levels, and their molar ratios in several species of commercial shrimp in Japan regarding the health risk of methylmercury exposure.

    Science.gov (United States)

    Hoang, Van Anh Thi; Sakamoto, Mineshi; Yamamoto, Megumi

    2017-01-01

    The Japanese shrimp industry depends on importing shrimp from other countries. However, little information is available on mercury speciation and selenium (Se) concentrations in commercial shrimp available in Japan. The present study determined the concentrations of total mercury (T-Hg), methylmercury (MeHg), and Se in the muscles (wet weight) of imported and domestic commercial shrimp from Kumamoto and Kagoshima prefectures to obtain information for assessing the risk of MeHg exposure. The median concentrations of T-Hg, MeHg and Se in shrimp imported from three different countries were, respectively: black tiger shrimp (n = 18), 15.8, 14.4, and 415 ng/g; Vannamei shrimp (n = 25), 11.4, 11.2, and 292 ng/g; and white shrimp (n = 26), 26.8, 26.1, and 396 ng/g. There were significant differences in T-Hg and MeHg concentrations between shrimp imported from different countries. The median concentrations of T-Hg, MeHg and Se in shrimp of Japanese origin were, respectively: Shiba shrimp (n = 10), 15.9, 15.0, and 270 ng/g; Kuruma shrimp (n = 10), 79.9, 75.9, and 390 ng/g; and Ashiaka shrimp (n = 10), 36.1, 34.1, and 303 ng/g. The percentages of MeHg in T-Hg were between 90% and 99%, with MeHg levels in the imported and domestic commercial shrimp lower than the Japanese regulation of 300 ng/g for fish. The mean Se/T-Hg molar ratios (16-160) were comparatively higher than those previously reported in fish. Overall, this survey suggests that shrimp commercially available in Japan will not pose a particularly high risk regarding MeHg exposure to consumers.

  4. Fluvial geomorphology and aquatic-to-terrestrial Hg export are weakly coupled in small urban streams of Columbus, Ohio

    Science.gov (United States)

    Sullivan, S. Mažeika P.; Boaz, Lindsey E.; Hossler, Katie

    2016-04-01

    Although mercury (Hg) contamination is common in stream ecosystems, mechanisms governing bioavailability and bioaccumulation in fluvial systems remain poorly resolved as compared to lentic systems. In particular, streams in urbanized catchments are subject to fluvial geomorphic alterations that may contribute to Hg distribution, bioaccumulation, and export across the aquatic-to-terrestrial boundary. In 12 streams of urban Columbus, Ohio, we investigated the influence of fluvial geomorphic characteristics related to channel geometry, streamflow, and sediment size and distribution on (1) Hg concentrations in sediment and body burdens in benthic larval and adult emergent aquatic insects and (2) aquatic-to-terrestrial contaminant transfer to common riparian spiders of the families Pisauridae and Tetragnathidae via changes in aquatic insect Hg body burdens as well as in aquatic insect density and community composition. Hydrogeomorphic characteristics were weakly related to Hg body burdens in emergent insects (channel geometry) and tetragnathid spiders (streamflow), but not to Hg concentrations in sediment or benthic insects. Streamflow characteristics were also related to emergent insect density, while wider channels were associated with benthic insect community shifts toward smaller-bodied and more tolerant taxa (e.g., Chironomidae). Thus, our results provide initial evidence that fluvial geomorphology may influence aquatic-to-terrestrial contaminant Hg transfer through the collective effects on emergent insect body burdens as well as on aquatic insect community composition and abundance.

  5. Seasonal variations in metallic mercury (Hg0) vapor exchange over biannual wheat-corn rotation cropland in the North China Plain

    Science.gov (United States)

    Sommar, Jonas; Zhu, Wei; Shang, Lihai; Lin, Che-Jen; Feng, Xinbin

    2016-04-01

    Air-surface gas exchange of Hg0 was measured in five approximately bi-weekly campaigns (in total 87 days) over a wheat-corn rotation cropland located on the North China Plain (NCP) using the relaxed eddy accumulation (REA) technique. The campaigns were separated over the duration of a full-year period (2012-2013) aiming to capture the flux pattern over essential growing stages of the planting system with a low homogeneous topsoil Hg content ( ˜ 45 ng g-1). Contrasting pollution regimes influenced air masses at the site and corresponding Hg0 concentration means (3.3 in late summer to 6.2 ng m-3 in winter) were unanimously above the typical hemispheric background of 1.5-1.7 ng m-3 during the campaigns. Extreme values in bi-directional net Hg0 exchange were primarily observed during episodes of peaking Hg0 concentrations. In tandem with under-canopy chamber measurements, the above-canopy REA measurements provided evidence for a balance between Hg0 ground emissions and uptake of Hg0 by the developed canopies. During the wheat growing season covering ˜ 2 / 3 of the year at the site, net field-scale Hg0 emission prevailed for periods of active plant growth until canopy senescence (mean flux: 20.0 ng m-3), showing the dominance of Hg0 soil efflux during warmer seasons. In the final vegetative stage of corn and wheat, ground and above-canopy Hg0 flux displayed inversed daytime courses with a near mid-day maximum (emission) and minimum (deposition), respectively. In contrast to wheat, Hg0 uptake of the corn canopy at this stage offset ground Hg0 emissions with additional removal of Hg0 from the atmosphere. Differential uptake of Hg0 between wheat (C3 species) and corn (C4 species) foliage is discernible from estimated Hg0 flux (per leaf area) and Hg content in mature cereal leaves, being a factor of > 3 higher for wheat (at ˜ 120 ng g-1 dry weight). Furthermore, this study shows that intermittent flood irrigation of the air-dry field induced a short pulse of Hg0 emission

  6. Species- and habitat-specific bioaccumulation of total mercury and methylmercury in the food web of a deep oligotrophic lake.

    Science.gov (United States)

    Arcagni, Marina; Juncos, Romina; Rizzo, Andrea; Pavlin, Majda; Fajon, Vesna; Arribére, María A; Horvat, Milena; Ribeiro Guevara, Sergio

    2017-09-08

    Niche segregation between introduced and native fish in Lake Nahuel Huapi, a deep oligotrophic lake in Northwest Patagonia (Argentina), occurs through the consumption of different prey. Therefore, in this work we analyzed total mercury [THg] and methylmercury [MeHg] concentrations in top predator fish and in their main prey to test whether their feeding habits influence [Hg]. Results indicate that [THg] and [MeHg] varied by foraging habitat and they increased with greater percentage of benthic diet and decreased with pelagic diet in Lake Nahuel Huapi. This is consistent with the fact that the native creole perch, a mostly benthivorous feeder, which shares the highest trophic level of the food web with introduced salmonids, had higher [THg] and [MeHg] than the more pelagic feeder rainbow trout and bentho-pelagic feeder brown trout. This differential THg and MeHg bioaccumulation observed in native and introduced fish provides evidence to the hypothesis that there are two main Hg transfer pathways from the base of the food web to top predators: a pelagic pathway where Hg is transferred from water, through plankton (with Hg in inorganic species mostly), forage fish to salmonids, and a benthic pathway, as Hg is transferred from the sediments (where Hg methylation occurs mostly), through crayfish (with higher [MeHg] than plankton), to native fish, leading to one fold higher [Hg]. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Accumulation of total mercury and methylmercury in rice plants collected from different mining areas in China.

    Science.gov (United States)

    Meng, Mei; Li, Bing; Shao, Jun-juan; Wang, Thanh; He, Bin; Shi, Jian-bo; Ye, Zhi-hong; Jiang, Gui-bin

    2014-01-01

    A total of 155 rice plants were collected from ten mining areas in three provinces of China (Hunan, Guizhou and Guangdong), where most of mercury (Hg) mining takes place in China. During the harvest season, whole rice plants were sampled and divided into root, stalk & leaf, husk and seed (brown rice), together with soil from root zone. Although the degree of Hg contamination varied significantly among different mining areas, rice seed showed the highest ability for methylmercury (MeHg) accumulation. Both concentrations of total mercury (THg) and MeHg in rice plants were significantly correlated with Hg levels in soil, indicating soil is still an important source for both inorganic mercury (IHg) and MeHg in rice plants. The obvious discrepancy between the distribution patterns of THg and MeHg reflected different pathways of IHg and MeHg accumulation. Water soluble Hg may play more important role in MeHg accumulation in rice plants.

  8. Mass Independent Fractionation of Hg Isotopes Preserved in the Precambrian

    Science.gov (United States)

    Thibodeau, A. M.; Bergquist, B. A.; Kah, L. C.; Ono, S.; Ghosh, S.; Hazen, R. M.

    2013-12-01

    Mercury (Hg) is a photochemically active, redox-sensitive, chalcophilic metal with complex biogeochemistry that displays a wide range of mass-dependent (MDF) and mass-independent (MIF) stable isotopic fractionation. In the past decade, Hg isotopes have emerged as important tracers of both the sources and cycling of Hg in the modern environment. However, their utility as environmental proxies in ancient rocks remains largely unexplored. The potential of Hg isotopes to inform Precambrian environments derives from the observation that Hg isotopes with odd atomic mass numbers (199Hg and 201Hg) undergo large MIF by the magnetic isotope effect (MIE) and smaller MIF through the nuclear volume effect (NVE). Small MIF produced via NVE has been observed for numerous transformations and is characterized by MIF ratios (Δ199Hg/Δ201Hg) of about 1.6. Large Hg-MIF driven by MIE has been observed during photochemical transformations and is characterized by Δ199Hg/Δ201Hg ratios between 1 and 1.3. This MIF signal is sensitive to a range of environmental conditions, including the amount and type of solar radiation, the presence and type of complexing organic ligands, and the Hg/dissolved organic carbon (DOC) ratio. Thus, it is hoped that Hg-MIF signals may indirectly record changes in atmospheric composition or seawater chemistry if preserved in marine sedimentary records. Previous work has clearly demonstrated that Hg-MIF signals are preserved in Archean and Paleoproterozoic marine shales and massive sulfide deposits. Here, we present evidence that such signals are also preserved in marine shales of mid-Proterozoic age, including the ~1.3 Ga Sulky formation (Dismal Lakes Group, NW Arctic), the ~1.45 Ga Greyson Shale (Belt Basin, Montana), and the ~1.5 Ga Katalsy formation (Kypry Group, Eastern European Platform). We observe that the Greyson shale and shales within the Sulky formation yield negative Hg-MIF with Δ199Hg/Δ201Hg ratios close to 1 and that Kaltasy group sediments

  9. Differential mercury transfer in the aquatic food web of a double basined lake associated with selenium and habitat

    Science.gov (United States)

    Arcagni, Marina; Campbell, Linda; Arribére, María A.; Marvin-DiPasquale, Mark; Rizzo, Andrea; Guevara, Sergio Ribeiro

    2013-01-01

    Food web trophodynamics of total mercury (THg) and selenium (Se) were assessed for the double-basined ultraoligotrophic system of Lake Moreno, Patagonia. Each basin has differing proportions of littoral and pelagic habitats, thereby providing an opportunity to assess the importance of habitat (e.g. food web structure or benthic MeHg production) in the transfer of Hg and Se to top trophic fish species. Pelagic plankton, analyzed in three size classes (10–53, 53–200, and > 200 μm), had very high [THg], exceeding 200 μg g− 1 dry weight (DW) in the smallest, and a low ratio of MeHg to THg (0.1 to 3%). In contrast, [THg] in littoral macroinvertebrates showed lower values (0.3 to 1.8 μg g− 1 DW). Juvenile and small fish species feeding upon plankton had higher [THg] (0.2 to 8 μg g− 1 muscle DW) compared to large piscivore fish species (0.1 to 1.6 μg g− 1 muscle DW). Selenium concentrations exhibited a much narrower variation range than THg in the food web, varying from 0.5 to 2.7 μg g− 1 DW. Molar Se:Hg ratios exceeded 1 for the majority of organisms in both basins, with most ratios exceeding 10. Using stable nitrogen isotopes as indicator of trophic level, no significant correlations were found with [THg], [Se] or Se:Hg. The apparent lack of biomagnification trends was attributed to elevated [THg] in plankton in the inorganic form mostly, as well as the possibility of consistent Se supply reducing the biomagnification in the food web of the organic portion of THg.

  10. Superdeformation studies in {sup 191}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Crowell, B. [and others

    1995-08-01

    Superdeformation in the A {approximately} 190 region was first observed in {sup 191}Hg from an experiment performed at ATLAS using the Argonne Notre Dame {gamma}-ray facility. We recently revisited the study of superdeformation in this nucleus using Gammasphere and the {sup 160}Gd({sup 36}S,5n) and {sup 174}Yb({sup 22}Ne,5n) reactions at 172 and 120 MeV in order to populate and measure states in the second well. The goal of the experiment was to identify new bands in the data, and thus allow us to gain understanding on the relative placement of single particle orbitals near the N = 112 SD shell gap. From an analysis of the data, the three previously identified SD bands were extended, and their feeding into the yrast states delineated. Two new SD bands were observed and preliminary evidence for a third new band was obtained as well.

  11. Magnetism, chemical spots, and stratification in the HgMn star phi Phoenicis

    CERN Document Server

    Makaganiuk, V; Piskunov, N; Jeffers, S V; Johns-Krull, C M; Keller, C U; Rodenhuis, M; Snik, F; Stempels, H C; Valenti, J A

    2011-01-01

    Mercury-manganese (HgMn) stars have been considered as non-magnetic and non-variable chemically peculiar (CP) stars for a long time. However, recent discoveries of the variability in spectral line profiles suggested an inhomogeneous surface distribution of chemical elements in some HgMn stars. From the studies of other CP stars it is known that magnetic field plays a key role in the formation of surface spots. All attempts to find magnetic fields in HgMn stars yielded negative results. In this study, we investigate a possible presence of the magnetic field in phi Phe (HD 11753) and reconstruct surface distribution of chemical elements that show variability in spectral lines. We also test a hypothesis that magnetic field is concentrated in chemical spots and look into the possibility that some chemical elements are stratified with depth in the stellar atmosphere.

  12. Diffusion Mechanism for Arsenic in Intrinsic and Extrinsic Conditions in HgCdTe

    Science.gov (United States)

    Grenouilloux, T.; Ferron, A.; Péré-Laperne, N.; Mathiot, D.

    2017-09-01

    Due to its low diffusivity and high activation rate, arsenic has become the dopant of choice in p/n HgCdTe high operating temperature technology. Its diffusion mechanism, however, remains imprecise. In this work, arsenic diffusion was studied in molecular beam epitaxy HgCdTe structures consisting of alternatively As-doped and intrinsic layers grown on a CdZnTe substrate. The diffusion coefficient of As was extracted from secondary ion mass spectroscopy concentration profiles. Annealings were performed for different temperatures, mercury partial pressures ( P Hg), annealing times and cadmium atomic fractions. Fermi-level effect on diffusion was observed, indicating extrinsic conditions for diffusion at high As concentration. Based on the variation of As diffusivity with P Hg and As concentration, we propose that As diffusion occurs on both II and VI sublattices. Our results are consistent with the fact that AsVI diffusion is assisted by the Te interstitial, introducing donor levels in the bandgap, while AsII diffusion is assisted by the cation vacancy.

  13. Hydrogen sensor based on Au and YSZ/HgO/Hg electrode for in situ measurement of dissolved H2 in high-temperature and -pressure fluids.

    Science.gov (United States)

    Zhang, R H; Hu, S M; Zhang, X T; Wang, Y

    2008-11-15

    Gold as a hydrogen-sensing electrode for in situ measurement of dissolved H2 in aqueous solutions under extreme conditions is reported. The dissolved H2 sensor, constructed with a Au-based sensing element and coupled with a YSZ/HgO/Hg electrode, is well suited for determining dissolved H2 concentrations of aqueous fluids at elevated temperatures and pressures. The Au electrode is made of Au wire mounted in a quartz bar, which can be pressurized and heated in the high-pressure and -temperature conditions. The Au-YSZ sensor has been tested for its potential response to the concentrations of dissolved H2 in fluids by using a flow-through reactor at high temperatures up to 400 degrees C and pressures to 38 MPa. Good sensitivity and linear response between the hydrogen concentrations in the fluids and the H2 sensor potentials are reported for hydrogen gas in the concentration range of 0.1-0.001 M H2 in aqueous fluids at temperatures up to 340 degrees C and 30 MPa. Nernstian response of the cell potential to dissolved H2 in fluids was determined at 340 degrees C and 30 MPa, described as follows: DeltaE = 0.9444 + 0. 0603 log m H2 The experimental results indicate that the Au-YSZ/HgO/Hg cell can be used to measure the solubility of H2 in aqueous fluid at temperatures and pressures near to the critical state of water. Thus, this type of Au hydrogen sensor could be easily used for in situ measurement of H2 in hydrothermal fluids in a high-pressure vessel, or at midocean ridge, due to its structure of compression resistance.

  14. [Resonance scattering detection of trace Hg2+ using aptamer modified AuSe nanoalloy].

    Science.gov (United States)

    Jiang, Zhi-liang; Zhang, Yi; Qin, Hui-min; Zhou, Lian-ping; Liang, Ai-hui; Wang, Peng-fei; Ouyang, Hui-xiang

    2011-05-01

    Under the condition of sodium citrate as stabilizer, the gold-selenium (AuSe) nano-alloy was prepared by sodium borohydride reduction procedure, and was modified by single-strand aptamer to obtain an aptamer nano-alloy probe (apta-AuSe) for Hg(II). In pH 6.8 Na2HPO4-NaH2PO4 buffer solution and in the presence of NaCl of 33 mmol L(-1), the Apta-AuSe probe is not aggregation. The apta-AuSe interacts with Hg2+ to form stable double-strand T-Hg(II)-T mismatches and to release AuSe nano-alloy particles from the probe. The released AuSe nano-alloy particles (20:1) aggregated to form bigger clusters that resulted in the resonance scattering (RS) intensity (I590 nm) increasing at 590 nm. The increased intensity delta I590 nm was proportional to the Hg2+ concentration from 1.3 to 1466 nmol L(-1), with a detection limit of 0.74 nmol L(-1). The regress equation was delta I590 nm = 0.603c + 2.0. Thus, a new resonance scattering (RS) spectroscopy of apta-AuSe was applied to the analysis of trace mercury ion. This simple, rapid, selective and sensitive aptamer AuSe nano-alloy RS assay was applied to the determination of Hg2+ in wastewater, with satisfactory results.

  15. Hg(II) removal from aqueous solution by bayberry tannin-immobilized collagen fiber.

    Science.gov (United States)

    Huang, Xin; Liao, Xuepin; Shi, Bi

    2009-10-30

    A novel adsorbent was prepared by immobilizing barberry tannin (BT) onto collagen fiber, which was found effective to remove Hg(II) from aqueous solution. The bayberry tannin-immobilized collagen fiber (BTICF) shows high adsorption capacity to Hg(II) in a wide pH range of 4.0-9.0, and a maximum adsorption capacity (198.49 mg/g) was reached at pH 7.0 and 303 K when the initial concentration of Hg(II) was 200.0 mg/L. The adsorption isothermal and kinetic data were well fitted by the Langmuir equation and the pseudo-first-order rate equation, respectively. The adsorption mechanism of BTICF to Hg(II) was proved to follow a chelating reaction. The BTICF can be easily regenerated with 0.1M lactic acid after adsorption process and recycled at least 4 times without the loss of adsorption capacity. These facts indicate that BTICF can be used as a low-cost adsorbent for effective removal of Hg(II) from aqueous solutions.

  16. Search for improved surface treatment procedures in fabrication of HgI/sub 2/ X-ray spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Levi, A.; Burger, A.; Nissenbaum, J. (Hebrew Univ., Jerusalem (Israel). School of Applied Science and Technology); Schieber, M. (Hebrew Univ., Jerusalem (Israel). School of Applied Science and Technology; EG and G, Inc., Santa Barbara, CA (USA)); Burshtein, Z. (Israel Atomic Energy Commission, Beersheba. Nuclear Research Center-Negev)

    1983-07-15

    The influence of various fabrication parameters on the surface quality of HgI/sub 2/ X-ray spectrometers has been studied in detail. Exposure of etched HgI/sub 2/ to ambient atmosphere for proportional 24 h may reduce the electron surface recombination velocity by almost an order of magnitude. Reduction of the etching solution temperature (KI in water) to about 0/sup 0/C and an increase of the KI concentration to proportional 20 wt.% are also important.

  17. Search for improved surface treatment procedures in fabrication of HgI/sub 2/ x-ray spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Levi, A.; Burger, A.; Nissenbaum, J.; Schieber, M.; Burshtein, Z.

    1980-01-01

    The influence of various fabrication parameters on the surface quality of HgI/sub 2/ x-ray spectrometers was studied in detail. Exposure of etched HgI/sub 2/ to ambient atmosphere for approx. 24 hours may reduce the electron surface recombination velocity by almost an order of magnitude. Reduction of the etching solution temperature (KI in water) to about 0/sup 0/C and an increase of the KI concentration to approx. 20 wt % are also important.

  18. Relationship Between Soil Properties and Different Fractions of Soil Hg

    Institute of Scientific and Technical Information of China (English)

    WUHONGTAO; YUGUIFEN; 等

    2001-01-01

    Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing,China,Results showed that clay(<2m) could increase water-soluble Hg(r=0.700*).Soil organic matter (OM) could enhance the increase of elemental Hg(r=0.674*),The higher the base saturation percentage (BSP) ,the more the residual Hg(R=0.684*) .Organic Hg,the sum of said-soluble organic He and alkali-soluble Hg,was positively affected by silt(2-20μm)but negatively affected by pH,with the direct path coefficients amounting to 1.0487 and 0.5121,respectively .The positive effect of OM and negative effect of BSP on organic Hg were the most significant ,with the direct path coefficients being 0.7614 and -0.8527,respectively. The indirect effect of clay(<2μm) iva BSP (path coefficient=0.4186) was the highest,showing that the real influencing factor in the effect of clay(<2μm) via BSP (path coefficient=0.4186) was the highest,showing that the real influencing factor in the effect of clay(<2μm) on acid-soluble organic Hw was BSP.since the available Hg fraction,water-soluble Hg,was positively affected by soil clay content,and the quite immobile and not bioavailable residual Hg by soil BSP,suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils.

  19. Impacts of Mercury Pollution Controls on Atmospheric Mercury Concentration and Occupational Mercury Exposure in a Hospital.

    Science.gov (United States)

    Li, Ping; Yang, Yan; Xiong, Wuyan

    2015-12-01

    Mercury (Hg) and Hg-containing products are used in a wide range of settings in hospitals. Hg pollution control measures were carried out in the pediatric ward of a hospital to decrease the possibility of Hg pollution occurring and to decrease occupational Hg exposure. Total gaseous Hg (TGM) concentrations in the pediatric ward and hair and urine Hg concentrations for the pediatric staff were determined before and after the Hg pollution control measures had been implemented. A questionnaire survey performed indicated that the pediatric staff had little understanding of Hg pollution and that appropriate disposal techniques were not always used after Hg leakage. TGM concentrations in the pediatric ward and urine Hg (UHg) concentrations for the pediatric staff were 25.7 and 22.2% lower, respectively, after the Hg pollution control measures had been implemented than before, which indicated that the control measures were effective. However, TGM concentrations in the pediatric ward remained significantly higher than background concentrations and UHg concentrations for the pediatric staff were remained significantly higher than the concentrations in control group, indicating continued existence of certain Hg pollution.

  20. Anti-aggregation-based spectrometric detection of Hg(II) at physiological pH using gold nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Rajeshwari, A.; Karthiga, D.; Chandrasekaran, Natarajan; Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com

    2016-10-01

    An efficient detection method for Hg (II) ions at physiological pH (pH 7.4) was developed using tween 20-modified gold nanorods (NRs) in the presence of dithiothreitol (DTT). Thiol groups (-SH) at the end of DTT have a higher affinity towards gold atoms, and they can covalently interact with gold NRs and leads to their aggregation. The addition of Hg(II) ions prevents the aggregation of gold NRs due to the covalent bond formation between the -SH group of DTT and Hg(II) ions in the buffer system. The changes in the longitudinal surface plasmon resonance peak of gold NRs were characterized using a UV–visible spectrophotometer. The absorption intensity peak of gold NRs at 679 nm was observed to reduce after interaction with DTT, and the absorption intensity was noted to increase by increasing the concentration of Hg(II) ions. The TEM analysis confirms the morphological changes of gold NRs before and after addition of Hg(II) ions in the presence of DTT. Further, the aggregation and disaggregation of gold NRs were confirmed by particle size and zeta potential analysis. The developed method shows an excellent linearity (y = 0.001 x + 0.794) for the graph plotted between the absorption ratio and Hg(II) concentration (1 to 100 pM) under the optimized conditions. The limit of detection was noted to be 0.42 pM in the buffer system. The developed method was tested in simulated body fluid, and it was found to have a good recovery rate. - Highlights: • Tween-20 modified gold NRs used as a probe for Hg(II) at physiological pH. • TEM, particle size and surface charge analysis confirm the aggregation and • disaggregation of NRs • The sensitivity of the probe for Hg(II) ions detection was 0.42 pM. • Hg(II) estimation in simulated body fluids with good recovery.

  1. A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento–San Joaquin Delta of California, USA

    Energy Technology Data Exchange (ETDEWEB)

    Drexler, Judith Z., E-mail: jdrexler@usgs.gov [U.S. Geological Survey, California Water Science Center, 6000 J Street, Placer Hall, Sacramento, CA 95819-6129 (United States); Alpers, Charles N., E-mail: cnalpers@usgs.gov [U.S. Geological Survey, California Water Science Center, 6000 J Street, Placer Hall, Sacramento, CA 95819-6129 (United States); Neymark, Leonid A., E-mail: lneymark@usgs.gov [U.S. Geological Survey, Box 25046, MS963, Denver Federal Center, Denver, CO 80225 (United States); Paces, James B., E-mail: jbpaces@usgs.gov [U.S. Geological Survey, Box 25046, MS963, Denver Federal Center, Denver, CO 80225 (United States); Taylor, Howard E., E-mail: hetaylor@usgs.gov [U.S. Geological Survey, 3215 Marine Street, Suite E-127, Boulder, CO 80303 (United States); Fuller, Christopher C., E-mail: ccfuller@usgs.gov [U.S. Geological Survey, 345 Middlefield Road, MS465, Menlo Park, CA 94025 (United States)

    2016-05-01

    In this paper, we provide the first record of millennial patterns of Pb and Hg concentrations on the west coast of the United States. Peat cores were collected from two micro-tidal marshes in the Sacramento–San Joaquin Delta of California. Core samples were analyzed for Pb, Hg, and Ti concentrations and dated using radiocarbon and {sup 210}Pb. Pre-anthropogenic concentrations of Pb and Hg in peat ranged from 0.60 to 13.0 μg g{sup −1}and from 6.9 to 71 ng g{sup −1}, respectively. For much of the past 6000 + years, the Delta was free from anthropogenic pollution, however, beginning in ~ 1425 CE, Hg and Pb concentrations, Pb/Ti ratios, Pb enrichment factors (EFs), and HgEFs all increased. Pb isotope compositions of the peat suggest that this uptick was likely caused by smelting activities originating in Asia. The next increases in Pb and Hg contamination occurred during the California Gold Rush (beginning ~ 1850 CE), when concentrations reached their highest levels (74 μg g{sup −1} Pb, 990 ng g{sup −1} Hg; PbEF = 12 and HgEF = 28). Lead concentrations increased again beginning in the ~ 1920s with the incorporation of Pb additives in gasoline. The phase-out of lead additives in the late 1980s was reflected in changes in Pb isotope ratios and reductions in Pb concentrations in the surface layers of the peat. The rise and subsequent fall of Hg contamination was also tracked by the peat archive, with the highest Hg concentrations occurring just before 1963 CE and then decreasing during the post-1963 period. Overall, the results show that the Delta was a pristine region for most of its ~ 6700-year existence; however, since ~ 1425 CE, it has received Pb and Hg contamination from both global and regional sources. - Highlights: • Micro-tidal peats were used to trace Pb and Hg contamination through the millennia. • Anthropogenic Pb and Hg were first evident in California in ~ 1425 CE. • Pb isotopes suggest early contamination may be from ore smelting in China

  2. Mercury speciation and selenium in toothed-whale muscles.

    Science.gov (United States)

    Sakamoto, Mineshi; Itai, Takaaki; Yasutake, Akira; Iwasaki, Toshihide; Yasunaga, Genta; Fujise, Yoshihiro; Nakamura, Masaaki; Murata, Katsuyuki; Chan, Hing Man; Domingo, José L; Marumoto, Masumi

    2015-11-01

    Mercury accumulates at high levels in marine mammal tissues. However, its speciation is poorly understood. The main goal of this investigation was to establish the relationships among mercury species and selenium (Se) concentrations in toothed-whale muscles at different mercury levels. The concentrations of total mercury (T-Hg), methylmercury (MeHg), inorganic mercury (I-Hg) and Se were determined in the muscles of four toothed-whale species: bottlenose dolphins (n=31), Risso's dolphins (n=30), striped dolphins (n=29), and short-finned pilot whales (n=30). In each species, the MeHg concentration increased with increasing T-Hg concentration, tending to reach a plateau. In contrast, the proportion of MeHg in T-Hg decreased from 90-100% to 20-40%. The levels of T-Hg and Se showed strong positive correlations. Se/I-Hg molar ratios rapidly decreased with the increase of I-Hg and reached almost 1 in all species. These results suggested that the demethylated MeHg immediately formed Se/I-Hg equimolar complex of mercury selenide (HgSe) in their muscles. In addition, an X-ray absorption fine structure analysis (XAFS) of a bottlenose dolphin muscle confirmed that the dominant chemical form of the Se/I-Hg equimolar complex was HgSe. HgSe was mainly localized in cells near the endomysium using electron probe microanalysis (EPMA). These results suggested that the demethylated MeHg finally deposits within muscle cells of bottlenose dolphin as an inert HgSe.

  3. Mercury risk in poultry in the Wanshan Mercury Mine, China.

    Science.gov (United States)

    Yin, Runsheng; Zhang, Wei; Sun, Guangyi; Feng, Zhaohui; Hurley, James P; Yang, Liyuan; Shang, Lihai; Feng, Xinbin

    2017-11-01

    In this study, total mercury (THg) and methylmercury (MeHg) concentrations in muscles (leg and breast), organs (intestine, heart, stomach, liver) and blood were investigated for backyard chickens, ducks and geese of the Wanshan Mercury Mine, China. THg in poultry meat products range from 7.9 to 3917.1 ng/g, most of which exceeded the Chinese national standard limit for THg in meat (50 ng/g). Elevated MeHg concentrations (0.4-62.8 ng/g) were also observed in meat products, suggesting that poultry meat can be an important human MeHg exposure source. Ducks and geese showed higher Hg levels than chickens. For all poultry species, the highest Hg concentrations were observed in liver (THg: 23.2-3917.1 ng/g; MeHg: 7.1-62.8 ng/g) and blood (THg: 12.3-338.0 ng/g; MeHg: 1.4-17.6 ng/g). We estimated the Hg burdens in chickens (THg: 15.3-238.1 μg; MeHg: 2.2-15.6 μg), ducks (THg: 15.3-238.1 μg; MeHg: 3.5-14.7 μg) and geese (THg: 83.8-93.4 μg; MeHg: 15.4-29.7 μg). To not exceed the daily intake limit for THg (34.2 μg/day) and MeHg (6 μg/day), we suggested that the maximum amount (g) for chicken leg, breast, heart, stomach, intestine, liver, and blood should be 1384, 1498, 2315, 1214, 1081, 257, and 717, respectively; the maximum amount (g) for duck leg, breast, heart, stomach, intestine, liver, and blood should be 750, 1041, 986, 858, 752, 134, and 573, respectively; and the maximum amount (g) for goose leg, breast, heart, stomach, intestine, liver, and blood should be 941, 1051, 1040, 1131, 964, 137, and 562, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Influence of humic acid on adsorption of Hg(II) by vermiculite.

    Science.gov (United States)

    do Nascimento, Fernando Henrique; Masini, Jorge Cesar

    2014-10-01

    Geochemical mobility of Hg(II) species is strongly affected by the interactions of these compounds with naturally occurring adsorbents such as humic acids, clay minerals, oxides, etc. Interactions among these sorbents affect their affinity for Hg(II) and a full understanding of these processes is still lacking. The present work describes the influence of a humic acid (HA) sample on the adsorption of Hg(II) by vermiculite (VT). Adsorption isotherms were constructed to evaluate the affinity of Hg(II) by VT, HA, VT modified with humic acid (VT-HA), and VT-HA in presence of soluble humic acid (VT-HA + HA). All experiments were made at pH 6.0 ± 0.1 in 0.02 M NaNO3 and 25.0 ± 0.5 °C for initial Hg(II) concentrations from 1.0 to 100 μM. Determinations of Hg(II) were made by square wave voltammetry automated by sequential injection analysis, an approach that enables the determination of the free plus labile fractions of Hg(II) in HA suspensions without the need for laborious separation steps. The adsorption isotherms were fitted to Langmuir and Freundlich equations, showing that HA was the material with the higher adsorption capacity (537 ± 30 μmol g(-1)) in comparison with VT and VT-HA (44 ± 3 and 51 ± 11 μmol g(-1), respectively). Adsorption order was HA > VT-HA + HA > VT = VT-HA. At pH 6.0 the interaction of HA with VT is weak and only 14% of C initially added to the suspension was effectively retained by the mineral. Desorption of Hg(II) in acidic medium (0.05 M HCl) was higher in binary (VT-HA) and ternary (VT-HA + HA) systems in comparison with that of VT and HA alone, suggesting that interactions between VT and HA are facilitated in acidic medium, weakening the binding to Hg(II).

  5. Oxidative stress in MeHg-induced neurotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Farina, Marcelo, E-mail: farina@ccb.ufsc.br [Departamento de Bioquimica, Centro de Ciencias Biologicas, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil); Aschner, Michael [Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN (United States); Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN (United States); Rocha, Joao B.T., E-mail: jbtrocha@yahoo.com.br [Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS (Brazil)

    2011-11-15

    Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically

  6. Lithography process for patterning HgI2 photonic devices

    Science.gov (United States)

    Mescher, Mark J.; James, Ralph B.; Hermon, Haim

    2004-11-23

    A photolithographic process forms patterns on HgI.sub.2 surfaces and defines metal sublimation masks and electrodes to substantially improve device performance by increasing the realizable design space. Techniques for smoothing HgI.sub.2 surfaces and for producing trenches in HgI.sub.2 are provided. A sublimation process is described which produces etched-trench devices with enhanced electron-transport-only behavior.

  7. Epitaxial growth of HgTe by a MOVPE process

    Energy Technology Data Exchange (ETDEWEB)

    Irvine, S.J.C.; Mullin, J.B.; Royle, A. (Royal Signals and Radar Establishment, Malvern (UK))

    1982-03-01

    Epitaxial layers of HgTe have been grown onto insulating CdTe substrates by the pyrolysis of (C/sub 2/H/sub 5/)/sub 2/Te in the presence of Hg vapour using a H/sub 2/ flow system. Temperature-dependent Hall effect and conductivity measurements have shown that the electrical properties of the layers are comparable with good quality bulk HgTe.

  8. A fluorescent chemodosimeter for Hg2+ based on a spirolactam ring-opening strategy and its application towards mercury determination in aqueous and cellular media.

    Science.gov (United States)

    Kumar, Kempahanumakkagaari Suresh; Ramakrishnappa, Thippeswamy; Balakrishna, R Geetha; Pandurangappa, Mallingappagari

    2014-01-01

    A novel fluorescent chemosensor rhodamine B phenyl hydrazide (RBPH) for Hg(2+) was designed and synthesized. This probe is highly sensitive, selective, and irreversible for Hg(2+) and exhibits fluorescent response at 580 nm. RBPH also displayed detectable color change from colorless to pink upon treatment with Hg(2+). This property has been utilized as naked eye detection for Hg(2+) in various industrial samples. Fluorescence microscopic experiments demonstrated that this chemosensor is cell permeable and can be used for fluorescence imaging of Hg(2+) in cellular media. This probe can detect Hg(2+) with good linear relationships from 1 to 100 nM with r = 0.99983 and the limit of detection were found to be 0.019 nM with ± 0.91 % RSD at 10 nM concentrations.

  9. Perturbed angular correlations studies in the HgBa$_2$CaCu$_2$O$_{6+\\delta}$ high-T$_c$ superconductor

    CERN Document Server

    Mendonca, Tania Melo; Haas, Heinz; Odier, Philippe; Tavares, Pedro; SIlva, Manuel Ribeiro; Lopes, Armandina; Darie, Celine; Araujo, Joao Pedro

    2011-01-01

    The electric field gradients at $^{199m}$Hg nuclei have been measured via the perturbed angular correlation (PAC) technique, allowing a full characterization of the Hg neighborhood charge distribution at high oxygen doping on the Hg planes. The PAC technique has been applied to investigate the effect of high oxygen pressure during the measurement. Polycrystalline HgBa$_2$CaCu$_2$O$_{6+\\delta}$ (Hg-1212) samples have been annealed at 152 bar pressurized oxygen. The influence of oxygen pressure during the experiment was then investigated by measuring the samples at atmospheric pressure and under 152 bar oxygen pressure. The present set of PAC experiments shows that at high oxygen concentrations there is a non-uniform oxygen distribution. Moreover, the Hg environment is not free from oxygen and the results hint to a new type of ordering.

  10. Bioaccumulation and biomagnification of mercury in African lakes: The importance of trophic status

    Energy Technology Data Exchange (ETDEWEB)

    Poste, Amanda E., E-mail: amanda.poste@niva.no [Norwegian Institute for Water Research, Gaustadalléen 21, 0349 Oslo (Norway); Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Muir, Derek C.G. [Aquatic Contaminants Research Division, Environment Canada, 867 Lakeshore Drive, Burlington, ON L7R 4A6 (Canada); Guildford, Stephanie J.; Hecky, Robert E. [Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Large Lakes Observatory, University of Minnesota Duluth, 2205 East Fifth Street, Duluth, MN 55812 (United States)

    2015-02-15

    Despite the global prevalence of both mercury (Hg) contamination and anthropogenic eutrophication, relatively little is known about the behavior of Hg in eutrophic and hypereutrophic systems or the effects of lake trophic status on Hg uptake and trophodynamics. In the current study we explore Hg trophodynamics at 8 tropical East African study sites ranging from mesotrophic to hypereutrophic, in order to assess the influence of lake trophic status on Hg uptake and biomagnification. Comprehensive water, plankton and fish samples were collected for analysis of total mercury (THg) and stable carbon and nitrogen isotopic ratios. We found evidence that uptake of THg into phytoplankton tended to be lower in higher productivity systems. THg concentrations in fish were generally low, and THg trophic magnification factors (TMFs; representing the average increase in contaminant concentrations from one trophic level to the next) ranged from 1.9 to 5.6. Furthermore TMFs were significantly lower in hypereutrophic lakes than in meso- and eutrophic lakes, and were negatively related to chlorophyll a concentrations both across our study lakes, and across African lakes for which literature data were available. These observations suggest that THg concentrations were strongly influenced by trophic status, with year-round high phytoplankton and fish growth rates reducing the potential for high THg in fish in these productive tropical lakes. - Highlights: • We characterized Hg in water and biota from 8 East African study sites. • Hg concentrations in fish were low and should not pose a risk to human consumers. • Hg uptake and biomagnification rates were negatively related to trophic status. • Growth dilution in phytoplankton and consumer trophic levels led to low fish Hg.

  11. A NIR fluorescent probe for the rapid detection of Hg2+ in living cells and in vivo mice imaging

    Science.gov (United States)

    Wang, Jiaoliang; Long, Liping; Xia, Li; Fang, Fang

    2017-06-01

    A near-infrared fluorescent probe NIR-Hg, for the detection of Hg2+ ion, has been synthesized directly by condensing Changsha dye with 4-Phenyl-3-thiosemicarbazide and the structure has fully characterized by 1HNMR, 13CNMR, and ESI-MS. The probe has been designed on the basis of the reaction that Hg2+ ion promotes thiosemicarbazide to oxazole in aqueous media and had been induced to produce turn-on fluorescence via an irreversible spirolactam ring-opening process. The probe NIR-Hg has exhibited fast response (1 min), high sensitivity with 44-fold fluorescence intensity enhancement under six equivalent amounts of Hg2+ added, high selectivity over other related metal ions and a low detection limit of 5.8 × 10-8 M in the phosphate buffer. The linear response range covers the concentration of Hg2+ from 5 × 10-7 to 5 × 10-6 M. In addition, the probe has good cell-membrane permeability, which is suitable for fluorescence imaging for Hg2+ in living cells and in vivo mice.

  12. Experiments with a New 201Hg+ Ion Clock

    Science.gov (United States)

    Burt, E. A.; Taghavi-Larigani, S.; Lea, S. N.; Prestage, J. D.; Tjoelker, R. L.

    2009-04-01

    In this paper we describe a new clock based on 201Hg+. All previous mercury ion clocks have been based on 199Hg+. We have recently completed construction of the 201Hg+ clock and will describe modifications to the design of our existing 199Hg+ clocks to accommodate the new isotope. We will also describe initial spectroscopic measurements of the hyperfine manifold, and possible future experiments. One experiment could place a limit on variations in the strong interaction fundamental constant ratio mq/ΛQCD.REFID="9789812838223_0043FN001">

  13. Dissecting the effect of anions on Hg2+ detection using a FRET based DNA probe.

    Science.gov (United States)

    Kiy, Mehmet Murat; Zaki, Ahmed; Menhaj, Arsalsan Beg; Samadi, Azadeh; Liu, Juewen

    2012-08-07

    Many biosensors have been developed to detect Hg(2+) using thymine-rich DNA. While sensor response to various cations is often studied to demonstrate selectivity, the effect of anions has been largely overlooked. Anions may compete with DNA for metal binding and thus produce a false negative result. Anions cannot be added alone; the cation part of a salt may cause DNA compaction and other effects, obscuring the role of anions. We find that the sensitivity of a FRET-based Hg(2+) probe is independent of Na(+) concentration. Therefore, by using various sodium salts, any change in sensitivity can be attributed solely to the effect of anions. Halide salts, sulfides, and amines are strong inhibitors; anions containing oxo or hydroxyl groups (e.g. nitrate, sulfate, phosphate, carbonate, acetate, and citrate) do not interfere with Hg(2+) detection even at 100 mM concentration. Mercury hydrolysis and its diffusion into polypropylene containers can also strongly affect the detection results. We conclude that thymine-rich DNA should be useful for Hg(2+) detection in many environmental water samples.

  14. Temperature-driven massless Kane fermions in HgCdTe crystals

    Science.gov (United States)

    Teppe, F.; Marcinkiewicz, M.; Krishtopenko, S. S.; Ruffenach, S.; Consejo, C.; Kadykov, A. M.; Desrat, W.; But, D.; Knap, W.; Ludwig, J.; Moon, S.; Smirnov, D.; Orlita, M.; Jiang, Z.; Morozov, S. V.; Gavrilenko, V. I.; Mikhailov, N. N.; Dvoretskii, S. A.

    2016-08-01

    It has recently been shown that electronic states in bulk gapless HgCdTe offer another realization of pseudo-relativistic three-dimensional particles in condensed matter systems. These single valley relativistic states, massless Kane fermions, cannot be described by any other relativistic particles. Furthermore, the HgCdTe band structure can be continuously tailored by modifying cadmium content or temperature. At critical concentration or temperature, the bandgap collapses as the system undergoes a semimetal-to-semiconductor topological phase transition between the inverted and normal alignments. Here, using far-infrared magneto-spectroscopy we explore the continuous evolution of band structure of bulk HgCdTe as temperature is tuned across the topological phase transition. We demonstrate that the rest mass of Kane fermions changes sign at critical temperature, whereas their velocity remains constant. The velocity universal value of (1.07+/-0.05) × 106 m s-1 remains valid in a broad range of temperatures and Cd concentrations, indicating a striking universality of the pseudo-relativistic description of the Kane fermions in HgCdTe.

  15. Removal of Cd (II and Hg(II by chelating resin Chelex-100

    Directory of Open Access Journals (Sweden)

    Afaf Amara-Rekkab

    2015-03-01

    Full Text Available A sensitive, simple method for the determination of amounts of mixture of Hg2+and Cd2+ by spectrophotometry was described based on the formation of the Hg2+- Cd2+- PAN complex in water media. Optimal conditions such as reagent amounts, and pH for the Hg2+- Cd2+ determination were reported. It was found that the 2:1 PAN- Hg2+- Cd2+ complex dominate at pH 13.0. In another hand, the sorption of mixture mercury (II and cadmium (II from aqueous medium on a chelating resin Chelex 100 was studied in batch mode. Since the extraction kinetic was obtained, with a mixture of 0.1 g of resin and 5 mL of mixture at 1 mmol/L of initial concentration, extraction equilibrium was reached within 20 min of mixing. The influence of some parameters such as initial mixture ions concentrations, initial pH of aqueous solution, ion strength and the amounts of resin have been studied at fixed temperature (20±1°C. The optimum pH value level for quantitative sorption was up to 2.6. The best performance obtained was 97.1% of extraction yield equivalent to 15.65 mg/g of resin. The pseudo-first- order, pseudo-second-order models and the intra-particle diffusion model were used to describe the kinetic data and rate constants were evaluated.

  16. Determination of Hg and diet identification in otter (Lontra longicaudis) feces

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira Josef, Carla [Centro de Energia Nuclear na Agricultura - CENA-USP, Universidade de Sao Paulo, Av. Centenario 303, 13400-970 Piracicaba, Sao Paulo (Brazil)], E-mail: carlajosef@hotmail.com; Ramos Adriano, Leonardo; Franca, Elvis Joacir de; Gustinelli Arantes de Carvalho, Gabriel [Centro de Energia Nuclear na Agricultura - CENA-USP, Universidade de Sao Paulo, Av. Centenario 303, 13400-970 Piracicaba, Sao Paulo (Brazil); Ferreira, Jose Roberto [Centro de Energia Nuclear na Agricultura - CENA-USP, Universidade de Sao Paulo, Av. Centenario 303, 13400-970 Piracicaba, Sao Paulo (Brazil); Polo de Pesquisa e Desenvolvimento Regional do Centro Sul - APTA, Agencia Paulista de Tecnologia dos Agronegocios. Rua Alberto Coral 1500, 13400-000 Piracicaba, Sao Paulo (Brazil)

    2008-04-15

    An analytical procedure for the determination of Hg in otter (Lontra longicaudis) feces was developed, to separate fish scales for the identification of the animal diet. Samples were washed with ultra-pure water and the suspension was sampled and transferred for digestion. The solubilization was performed with nitric-perchloric acid mixture, and detection carried out by the atomic fluorescence spectrometry (AFS). The quality of the analytical procedure was assessed by analyzing in-house standard solutions and certified reference materials. Total Hg concentrations were in the range of 7.6-156 ng g{sup -1} (July 2004), 25.6-277 ng g{sup -1} (January 2005) and 14.6-744 ng g{sup -1} (May 2005) that is approximately the same order of magnitude for all samples collected in two reservoirs at the Tiete River, Brazil. Although Hg concentrations varied with sampling periods and diet, high levels were correlated to the percentage of carnivorous fish scales present in the otter feces. - The importance of otter feces preparation for Hg analysis, focusing the food web.

  17. PENCEMARAN LOGAM BERAT MERKURI (Hg PADA AIRTANAH

    Directory of Open Access Journals (Sweden)

    Thomas Triadi Putranto

    2012-02-01

    Full Text Available The earth consists largely of water because the land area is smaller than the ocean. Human beings on this earthcan not escape the need for water. Water is the main requirement for the process of life on the earth.Relatively clean water that is coveted by men, whether for purposes of daily life, for industrial purposes, for thecleanliness of city sanitation, as well as for agricultural purposes and so forth. Heavy metal pollution is a veryserious issue to be handled, because of adverse environmental and ecosystem in general. Heavy metallic elementis the element which has a density of more than 5 gr/cm3. Hg has a density of 13.55 gr/cm3. Disaster is anoutbreak of Minamata mercury poisoning in people who eat fish contaminated by mercury in Minamata Japan,and this event is known as Minamata Disease. Efforts to tackle the heavy metal pollution can actually be doneusing a chemical process or by microorganism such as microbes and bacteria.

  18. Imobilisasi TiO2 ke dalam Resin Penukar Kation dan Aplikasinya sebagai Fotokatalis dalam Proses Fotoreduksi Ion Hg2+

    Directory of Open Access Journals (Sweden)

    Rosyid Ridho

    2017-03-01

    kenaikan fotoreduksi pada ion Hg(II, akan tetapi pada pH yang lebih tinggi dari 4 menyebabkan terjadinya penurunan efektivitas fotoreduksi terhadap ion Hg(II.   Kata kunci : Fotokatalis, TiO2-resin, Ion Hg(II   Abstract To develop TiO2 photoreduction photocatalyst in order to decrease the Hg(II ion concentrate, in this research, it has been done the TiO2-Resin photocatalyst preparation with the characterization and application to Hg(II ion photoreduction process. This preparation was done with ion exchange method which followed by studied calcinations at certain temperature. The preparation has been studied the influence of titanium isopropoxide concentrate toward TiO2-Resin which has been characterized by using X-Ray Diffraction(XRD and Thermografimetry (TGA. In Hg(II ion photoreduction process, it has been studied the influence of photocatalyst mass, the content of TiO2 which immobilized into sulfonated polystyrene (resin, the ion Hg(II concentrate, and the pH influence. The photoreduction process has been done in the closed reactor that equipped by UV lamp, and uses the irradiating a mixture which contents of Hg(II ion solution and TiO2-Resin photocatalyst powder, with the stirring at certain time. The result of photoreduction was calculated based on the difference between the earlier Hg(II ion concentrate and unreduced Hg(II ion. The determining of unreduced Hg(II ion concentrate was done by using cold vapor atomic absorption spectrophotometry (CV-AAS. The preparation result showed that the higher isopropoxide titanium that was added into sulfonated polystyrene, the higher the content of TiO2 that was formed in TiO2-Resin. the result of photocatalyst test showed that the using using of TiO2-Resin photocatalyst can increase the result of Hg(II ion photoreduction  which the increase is higher than TiO2 powder. The added of photocatalyst by the higher mass, adds the photoreduction effectiveness toward the Hg(II ion. The higher the Hg(II concentrate that added, the

  19. Hg-coordination studies of oligopeptides containing cysteine, histidine and tyrosine by $^{199m}$Hg-TDPAC

    CERN Document Server

    Ctortecka, B; Mallion, S; Butz, T; Hoffmann, R

    1999-01-01

    In order to study the interaction of histidine- and tyrosine- containing peptide chains with Hg(II), the nuclear quadrupole interaction (NQI) of /sup 199m/Hg in the Hg complexes of the oligopeptides alanyl-alanyl-histidyl-alanyl-alanine-amid (AAHAA-NH /sub 2/) and alanyl-alanyl-tyrosyl-alanyl-alanine-amid (AAYAA-NH/sub 2/) was determined by time differential perturbed angular correlation and is compared with previous data on alanyl-alanyl-cysteyl-alanyl- alanyl (AACAA-OH). The /sup 199m/Hg-NQIs depend on the oligopeptide to Hg(II) stoichiometry and indicate that two-fold and four-fold coordinations occur for the bound Hg(II). (12 refs).

  20. 40 CFR 75.81 - Monitoring of Hg mass emissions and heat input at the unit level.

    Science.gov (United States)

    2010-07-01

    ... cubic meter (µg/scm); and (2) A flow monitoring system; and (3) A continuous moisture monitoring system... Hg concentration monitoring system (as defined in § 72.2 of this chapter) or a sorbent trap monitoring system (as defined in § 72.2 of this chapter), to measure the mass concentration of total...

  1. Mercury concentrations and pools in four adjacent coniferous and deciduous upland forests in Beijing, China

    Science.gov (United States)

    Zhou, Jun; Wang, Zhangwei; Zhang, Xiaoshan; Gao, Yu

    2017-05-01

    Understanding of forest mercury (Hg) pools is important for quantifying the global atmospheric Hg removal. We studied gaseous elemental Hg (GEM) concentrations, litterfall Hg depositions, and pool sizes in four adjacent stands at Mount Dongling to assess Hg dynamics in the forested catchment and the potential of Hg release during wildfires. The average GEM concentration was 2.5 ± 0.5 ng m-3, about 1.5 times of the background levels in the Northern Hemisphere. In all four stands, Hg concentrations increase in the following order: bole wood < branch/twig < bark < mineral soil < needles/leaves < litterfall < Oi litter < Oe soil < Oa organic soil. The Hg pools of aboveground biomass were comparable in the forests of larch, oak, and Chinese pine, which were much greater than that of mixed broadleaf stands due to lower biomass. The total Hg pools in ecosystems were similar in the four stands, because of the comparable Hg pool in the soil horizons (0-40 cm), which accounted for over 97% of the total ecosystem Hg storage in the four stands. Although Hg pools of the forest ecosystem in north China were comparable to North America and North Europe, Hg storage in forests constituted a high threat for large Hg emission pulses to the atmosphere by wildfires. The potential Hg emissions from the combustion at the four stands were ranged from 0.675 to 1.696 mg m-2.

  2. Mercury in water and biomass of microbial communities in hot springs of Yellowstone National Park, USA

    Science.gov (United States)

    King, S.A.; Behnke, S.; Slack, K.; Krabbenhoft, D.P.; Nordstrom, D.K.; Burr, M.D.; Striegl, R.G.

    2006-01-01

    Ultra-clean sampling methods and approaches typically used in pristine environments were applied to quantify concentrations of Hg species in water and microbial biomass from hot springs of Yellowstone National Park, features that are geologically enriched with Hg. Microbial populations of chemically-diverse hot springs were also characterized using modern methods in molecular biology as the initial step toward ongoing work linking Hg speciation with microbial processes. Molecular methods (amplification of environmental DNA using 16S rDNA primers, cloning, denatured gradient gel electrophoresis (DGGE) screening of clone libraries, and sequencing of representative clones) were used to examine the dominant members of microbial communities in hot springs. Total Hg (THg), monomethylated Hg (MeHg), pH, temperature, and other parameters influential to Hg speciation and microbial ecology are reported for hot springs water and associated microbial mats. Several hot springs indicate the presence of MeHg in microbial mats with concentrations ranging from 1 to 10 ng g-1 (dry weight). Concentrations of THg in mats ranged from 4.9 to 120,000 ng g-1 (dry weight). Combined data from surveys of geothermal water, lakes, and streams show that aqueous THg concentrations range from l to 600 ng L-1. Species and concentrations of THg in mats and water vary significantly between hot springs, as do the microorganisms found at each site. ?? 2006.

  3. Graphene-Rhodamine Nanoprobe for Colorimetric and Fluorimetric Hg(2+) Ion Assay.

    Science.gov (United States)

    Mohan, Anju; Neeroli Kizhakayil, Renuka

    2016-06-08

    This article reveals the first ever prospective application of Graphene-Rhodamine array (GRH) as a colorimetric and fluorimetric sensor for Hg(2+) ions. The duality of Graphene to undergo π-π and dispersive interactions with Rhodamine as well as to act as a selective adsorbent for Hg(2+) is conceptualized in this study. These interactions lead to decrease in absorbance of the dye in the presence of graphene, which is restored when kept in contact with Hg(2+) ions. The feasibility of the mechanism has been proved using EDTA as the coordinating ligand. It is noteworthy that all the optical variations occurred in the visible scale of the electromagnetic spectrum. The GRH array exhibited higher sensitivity toward the target ion with a limit of detection of 2 ppb. A perfect linear variation of absorbance at 554 nm with Hg(2+) concentration was observed in 0-1000 nM range, enabling the use of the system as a quantitative sensor for the test ion. The commendable selectivity of the array toward Hg(2+) ion has been investigated by observing the optical response in the presence of other environmentally relevant metal ions. A reversible turn off and turn on INHIBIT logic gate has been proposed which extends the scope of the designed array for the development of automated chemical systems. The fluorescence resonance energy transfer (FRET) ability of graphene paves the backbone for the fluorimetric detection. Fluorimetric strategy yielded a much lower limit of detection of 380 ppt using this probe, which makes a significant advance in trace detection of Hg(2+) ions.

  4. Elucidation of the defence mechanism in microalgae Chlorella sorokiniana under mercury exposure. Identification of Hg-phytochelatins.

    Science.gov (United States)

    Gómez-Jacinto, Verónica; García-Barrera, Tamara; Gómez-Ariza, José Luis; Garbayo-Nores, Inés; Vílchez-Lobato, Carlos

    2015-08-01

    Algae and aquatic macrophytes are capable of accumulating heavy metals up to concentrations several orders of magnitude higher than those existing in their surrounding environment. Investigation of mercury toxicology in microalgae is of great interest from ecological point of view, since they could be used as bioindicator to evaluate aquatic ecosystems affected by Hg pollution. In this study, we have performed an exposure experiment focused on the biological response of microalgae Chlorella sorokiniana, a unicellular model organism, to Hg-induced toxicity. The culture was exposed to different concentrations of this element for nine days, namely 0.5, 1, 5 and 10mg L(-1) of HgCl2 (as Hg). To achieve a better understanding of the biological mechanisms triggered by Hg-induced toxicity in this alga a metallomic approach based on SEC-ICP-ORS-MS was applied to survey biomarkers of biological response to mercury contamination in surface water. In addition, the combination of RP-HPLC-ICP-ORS-MS and RP-HPLC-ESI-QqQ-TOF-MS was applied to identify, for the first time, two Hg-binding phytochelatins in this aquatic organism, using cell extracts from microalgae exposed to inorganic mercury.

  5. Highly Selective Hg (II Ion Detection Based on Linear Blue-Shift of the Maximum Absorption Wavelength of Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Li Ping Wu

    2012-01-01

    Full Text Available A new method of detecting Hg (II ion with silver nanoparticles (AgNPs is developed in this contribution. When Hg (II ions were added into AgNPs solution, the solution displayed rapid color change and blue shift of the maximum absorption wavelength (Δλ, which was in proportion to the Hg (II ion concentration over the range of 2.0 × 10−7–6.0 × 10−6 mol/L, with detection limit (3σ of 6.6 × 10−9 mol/L. Under the same experimental conditions, other metal ions did not interfere. Thus, we propose a rapid, simple and highly selective method for detecting Hg (II ion.

  6. Possible link between Hg and Cd accumulation in the brain of long-finned pilot whales (Globicephala melas)

    Energy Technology Data Exchange (ETDEWEB)

    Gajdosechova, Zuzana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Brownlow, Andrew [SAC Wildlife Unit, Inverness (United Kingdom); Cottin, Nicolas T.; Fernandes, Mariana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Read, Fiona L. [Oceanlab, University of Aberdeen, Main Street, Newburgh AB41 6AA (United Kingdom); Urgast, Dagmar S.; Raab, Andrea; Feldmann, Jörg; Krupp, Eva M. [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom)

    2016-03-01

    The bioaccumulation of metals was investigated by analysis of liver, kidney, muscle and brain tissue of a pod of 21 long-finned pilot whales (Globicephala melas) of all ages stranded in Scotland, UK. The results are the first to report cadmium (Cd) passage through the blood–brain barrier of pilot whales and provide a comprehensive study of the long-term (up to 35 years) mammalian exposure to the environmental pollutants. Additionally, linear accumulation of mercury (Hg) was observed in all studied tissues, whereas for Cd this was only observed in the liver. Total Hg concentration above the upper neurochemical threshold was found in the sub-adult and adult brains and methylmercury (MeHg) of 2.2 mg/kg was found in the brain of one individual. Inter-elemental analysis showed significant positive correlations of Hg with selenium (Se) and Cd with Se in all studied tissues. Furthermore, differences in the elemental concentrations in the liver and brain tissues were found between juvenile, sub-adult and adult groups. The highest concentrations of manganese, iron, zinc, Se, Hg and MeHg were noted in the livers, whereas Cd predominantly accumulated in the kidneys. High concentrations of Hg and Cd in the tissues of pilot whales presented in this study reflect ever increasing toxic stress on marine mammals. - Highlights: • Trace elements were measured in a pod of 21 pilot whales stranded in Scotland. • Bioaccumulation of mercury and methyl mercury was found in all studied tissues. • Cadmium age related accumulation was observed in the liver and brain tissues. • Cadmium-selenium correlations suggest formation of cadmium-selenium complexes.

  7. Mercury bioaccumulation in estuarine fishes: Novel insights from sulfur stable isotopes

    Science.gov (United States)

    Willacker, James J.; Eagles-Smith, Collin A.; Ackerman, Joshua T.

    2017-01-01

    Estuaries are transitional habitats characterized by complex biogeochemical and ecological gradients that result in substantial variation in fish total mercury concentrations (THg). We leveraged these gradients and used carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes to examine the ecological and biogeochemical processes underlying THg bioaccumulation in fishes from the San Francisco Bay Estuary. We employed a tiered approach that first examined processes influencing variation in fish THg among wetlands, and subsequently examined the roles of habitat and within-wetland processes in generating larger-scale patterns in fish THg. We found that δ34S, an indicator of sulfate reduction and habitat specific-foraging, was correlated with fish THg at all three spatial scales. Over the observed ranges of δ34S, THg concentrations in fish increased by up to 860% within wetlands, 560% among wetlands, and 291% within specific impounded wetland habitats. In contrast, δ13C and δ15N were not correlated with THg among wetlands and were only important in low salinity impounded wetlands, possibly reflecting more diverse food webs in this habitat. Together, our results highlight the key roles of sulfur biogeochemistry and ecology in influencing estuarine fish THg, as well as the importance of fish ecology and habitat in modulating the relationships between biogeochemical processes and Hg bioaccumulation.

  8. Mercury Bioaccumulation in Estuarine Fishes: Novel Insights from Sulfur Stable Isotopes.

    Science.gov (United States)

    Willacker, James J; Eagles-Smith, Collin A; Ackerman, Joshua T

    2017-02-21

    Estuaries are transitional habitats characterized by complex biogeochemical and ecological gradients that result in substantial variation in fish total mercury concentrations (THg). We leveraged these gradients and used carbon (δ(13)C), nitrogen (δ(15)N), and sulfur (δ(34)S) stable isotopes to examine the ecological and biogeochemical processes underlying THg bioaccumulation in fishes from the San Francisco Bay Estuary. We employed a tiered approach that first examined processes influencing variation in fish THg among wetlands, and subsequently examined the roles of habitat and within-wetland processes in generating larger-scale patterns in fish THg. We found that δ(34)S, an indicator of sulfate reduction and habitat specific-foraging, was correlated with fish THg at all three spatial scales. Over the observed ranges of δ(34)S, THg concentrations in fish increased by up to 860% within wetlands, 560% among wetlands, and 291% within specific impounded wetland habitats. In contrast, δ(13)C and δ(15)N were not correlated with THg among wetlands and were only important in low salinity impounded wetlands, possibly reflecting more diverse food webs in this habitat. Together, our results highlight the key roles of sulfur biogeochemistry and ecology in influencing estuarine fish THg, as well as the importance of fish ecology and habitat in modulating the relationships between biogeochemical processes and Hg bioaccumulation.

  9. SO2/Hg removal from flue gas by dry FGD

    Institute of Scientific and Technical Information of China (English)

    Wang Fan; Wang Hongmei; Zhang Fan; Zhu Jinwei; Tian Gang; Liu Yu; Mao Jixian

    2012-01-01

    To study the mechanism of SO2 and Hg removal from flue gas,an experimental packed bed reactor was designed to simulate the dry FGD,where a mixture of lime and fly ash in ratio 1∶3 w/w was used as the SO2 and Hg sorbent,and steam at temperature of 100 ℃ was applied for activation of the sorbent,while the activation time set to 20 min.The experimental factors including the SO2/Hg sorbent characteristics,50% breakthrough time for SO2/Hg removal,sorbent packed bed depth and reaction temperature were investigated.The experimental results show that after steam activation,the BET specific surface area and specific pore volume increased from 37.8 to 45.5 m2/g and from 0.42 to 0.51 cm3/g,respectively.With activation of the sorbent by steam,the 50% breakthrough times of SO2 and Hg removal increased from 34 to 42 min and from 23 to 45 min,respectively.When the packed bed depth was increased from 5 to 25 mm,the 50% breakthrough times for Hg and SO2 removal increased from 12 to 52 min and from 6 to 47 min,respectively.With the increase of the reaction temperature,the 50% breakthrough of SO2/Hg removal decreased accordingly.Steam activation can efficiently improve SO2/Hg removal simultaneously.

  10. Quantitative imaging of D-2-hydroxyglutarate (D2HG in selected histological tissue areas by a novel bioluminescence technique

    Directory of Open Access Journals (Sweden)

    Nadine Fabienne Voelxen

    2016-03-01

    Full Text Available AbstractPatients with malignant gliomas have a poor prognosis with average survival of less than one year. Whereas in other tumor entities the characteristics of tumor metabolism are successfully used for therapeutic approaches, such developments are very rare in brain tumors, notably in gliomas. One metabolic feature characteristic of gliomas, in particular diffuse astrocytomas and oligodendroglial tumors, is the variable content of D-2-hydroxyglutarate (D2HG, a metabolite, which was discovered first in this tumor entity. D2HG is generated in large amounts due to various gain-of–function mutations in the isocitrate dehydrogenases IDH-1 and IDH-2. Meanwhile, D2HG has been detected in several other tumor entities including intrahepatic bile-duct cancer, chondrosarcoma, acute myeloid leukemia, and angioimmunoblastic T-cell lymphoma. D2HG is barely detectable in healthy tissue (< 0.1 mM, but its concentration increases up to 35 mM in malignant tumor tissues. Consequently, the oncometabolite D2HG has gained increasing interest in the field of tumor metabolism. To facilitate its quantitative measurement without loss of spatial resolution at a microscopical level, we have developed a novel bioluminescence assay for determining D2HG in sections of snap-frozen tissue. The assay was verified independently by photometric tests and liquid chromatography / mass spectrometry (LC/MS. The novel technique allows the microscopically resolved determination of D2HG in a concentration range of 0 – 10 µmol/g tissue (wet weight. In combination with the already established bioluminescence imaging techniques for ATP, glucose, pyruvate, and lactate, the novel D2HG assay enables a comparative characterization of the metabolic profile of individual tumors in a further dimension.

  11. Mercury and methylmercury dynamics in a coastal plain watershed, New Jersey, USA

    Science.gov (United States)

    Barringer, J.L.; Riskin, M.L.; Szabo, Z.; Reilly, P.A.; Rosman, R.; Bonin, J.L.; Fischer, J.M.; Heckathorn, H.A.

    2010-01-01

    The upper Great Egg Harbor River watershed in New Jersey's Coastal Plain is urbanized but extensive freshwater wetlands are present downstream. In 2006-2007, studies to assess levels of total mercury (THg) found concentrations in unfiltered streamwater to range as high as 187 ng/L in urbanized areas. THg concentrations were water with THg that exceeds the drinking water standard (2,000 ng/L). THg concentrations were lower (Methylmercury (MeHg) concentrations in unfiltered streamwater ranged from 0.17 ng/L at a forest/wetlands site to 2.94 ng/L at an urban site. The percentage of THg present as MeHg increased as the percentage of forest + wetlands increased, but also was high in some urban areas. MeHg was detected only in groundwater water/sediment interface. Atmospheric deposition is presumed to be the main source of Hg to the wetlands and also may be a source to groundwater, where wastewater inputs in urban areas are hypothesized to mobilize Hg deposited to soils. ?? 2010 US Government.

  12. Mercury species in formerly contaminated soils and released soil gases.

    Science.gov (United States)

    Sysalová, Jiřina; Kučera, Jan; Drtinová, Barbora; Červenka, Rostislav; Zvěřina, Ondřej; Komárek, Josef; Kameník, Jan

    2017-02-01

    Total mercury (T-Hg), elemental mercury (Hg(0)), methylmercury (MeHg(+)), phenylmercury (PhHg(+)), and gaseous elemental mercury (GEM) species were determined in soils formerly contaminated by different processes from two sites in the Czech Republic. Analytical methods involved atomic absorption spectrometry (AAS) using a single-purpose Advanced Mercury Analyser AMA-254 and radiochemical neutron activation analysis (RNAA) for T-Hg determination, a thermal desorption method was used for Hg(0) determination, gas chromatography coupled with atomic fluorescence spectrometry (GC-AFS) was employed for assay of MeHg(+) and PhHg(+), while GEM measurement was carried out using a portable Zeeman-AAS device Lumex RA-915(+). The first sampling site was in the surroundings of a former PhHgCl-based fungicide processing plant next to Příbram (central Bohemia). Although the use of Hg-based fungicides as seed mordant have been banned, and their production stopped at the end of 1980's, highly elevated Hg contents in soil are still observed in the vicinity of the former plant, reaching T-Hg values >13mgkg(-1). The second sampling site was an abandoned mining area named Jedová hora Hill near Hořovice (central Bohemia), where cinnabar (HgS) was occasionally mined as by-product of Fe ores hematite and siderite. Mining activities have been stopped here in 1857. Very high contents of T-Hg are still found at this site, up to 144mgkg(-1). In most cases we found a statistically significant correlation between T-Hg and Hg(0) values regardless of the pollution source. On the contrary, insignificant correlation was observed neither between T-Hg and GEM values, nor between GEM and Hg(0). Concentrations of the investigated organomercury species were above a limit of detection (LOD) only in the most contaminated samples, where their levels were about two to three orders of magnitude lower compared to those of T-Hg.

  13. Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon

    Science.gov (United States)

    Lewis, Ariel S.; Huntington, Thomas G.; Marvin-DiPasquale, Mark C.; Amirbahman, Aria

    2016-01-01

    Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment.

  14. Biogeochemical factors affecting the distribution, speciation, and transport of Hg species in the Deûle and Lys Rivers (Northern France).

    Science.gov (United States)

    Daye, Mirna; Kadlecova, Milada; Ouddane, Baghdad

    2015-02-01

    The Deûle River is a highly polluted River by heavy metals caused by the historical discharges of ore minerals from the former ore smelter "Metaleurop." The potential mercury (Hg) pollution in the Deûle River implicates the importance of Hg distribution study in the river. As well as to configure the different biogeochemical factors that control the distribution and the potential transport of Hg to distant places. Four different sites were studied as follows: D-A (Deûle River, a site located upstream the river), D-B (Deûle River, a site located near a Zn, Pb, Cu, and Ni smelter that closed in 2003), L-C (Lys River, a site located upstream the confluence of the Deûle River with Lys River), and L-D (downstream the rivers confluence). Different Hg analyses were performed including total mercury in sediment (HgTS), methylmercury (MeHg) in sediment, total mercury in pore water (HgTPW), total mercury in surface water (HgTD), and total suspended particulate Hg in water (HgTP). HgTS decreases downstream from the Deûle River sites with a mean value of 11 ± 0.34 mg/kg to Lys River site (L-D) with a mean value of 0.53 ± 0.02 mg/kg at the confluence. The unaffected side of the Lys River, localized before the confluence (L-C), is characterized by low HgTS of an average value of 0.042 ± 0.003 mg/kg and high % MeHg reaching 4.2 %. Whereas, the highly contaminated Deûle sites are designated by low % MeHg with an average value of 0.053 %. Low pristine environments like that found in L-C site with more favorable biogeochemical conditions of lower concentrations of HgTS, sulfides, and Corg host more active biotic methylation than that of the highly polluted Deûle sites with high concentrations of HgTS and sulfides concentrations. Methylation in D-B (the closet site to Metaleurop smelter) is an old and recent methylation activity that has contributed to MeHg accumulation in the sediments as opposed to the exclusive recent events of methylation in Lys sites. MeHg

  15. Inorganic arsenic - SPE HG-AAS method for RICE tested in-house and collaboratively

    DEFF Research Database (Denmark)

    Rasmussen, Rie Romme; Qian, Yiting; Sloth, Jens Jørgen

    As) and the methylated species monomethylarsonic acid (MA) and dimethylarsinic acid (DMA). Dietary intake of iAs is of special concern due to its carcinogenicity to humans, whereas DMA and MA are considered of less toxicological importance. Rice grains and rice-based products are staple foods in many countries...... spectrometry (ICP-MS) analysis. The SPE separation step was tested collaboratively, where the laboratories (N=10) used either HG-AAS or ICPMS for iAs determination in a wholemeal rice powder. The trial gave satisfactory results (HorRat value of 1.6) and did not reveal significant difference (t test, p>0.......05) between HG-AAS and ICP-MS quantification. The iAs concentration in 36 rice samples purchased on the Danish retail market varied (0.03–0.60 mg/kg), with the highest concentration found in a red rice sample....

  16. Vapour pressure of components made by the presence of HgS(s,alpha) in an oil/gas reservoir and consequences for the produced gas

    Energy Technology Data Exchange (ETDEWEB)

    Oestvold, T.; Gustavsen, Oe.; Grande, K.; Aas, N.; Olsvik, Mimmi Kjetsaa

    2006-03-15

    A thermodynamic analysis is presented on how components made from HgS (s,alpha), existing in a oil/gas reservoir, will distribute themselves between gas, water, liquid and solid components as a function of temperature and pressure. The consequence of the formation of mercury containing components on gas injection and on gas quality is discussed. Since equilibrium is established in the model calculation, other gas components in the gas phase and components in condensed phases present will also influence the composition of the gas. Six cases are considered in the calculation: 1) HgS(s,alpha) - Ar(g), 2) HgS(s,alpha) - Ar (g) - water with 10-4 molal NaCl at pH = 7, 3) HgS(s,alpha) - CH{sub 4}(g), 4) HgS(s,alpha) - CH{sub 4} (g) - water with 10-4 molal NaCl at pH = 7 and 5) HgS(s,alpha) - natural gas - water with 10-4 molal NaCl at pH = 7, 6) HgS(s,alpha) - natural gas - water with 10-4 molal NaCl and 5*10-5 molal NO-3- at pH = 7. When HgS(s,alpha) is present in an oil reservoir at 170 deg C and 200 bar, these calculations show that the major components formed are: H{sub 2}(g), H{sub 2}S(g), Hg(l) and Hg(g) together with carbon. Mercury in the gas phase in the cases 1) is 4*10-7 bar and is determined by the evaporation and decomposition HgS(g) in the reservoir. In case 2) P{sub Hg} = 5.7*10-4 bar mainly determined by the formation of sulphate in the water phase. In the cases 3), 4) and 5) these calculations show that the major components formed are: H{sub 2}(g), H{sub 2}S(g), Hg(l) and Hg(g) together with carbon, and the gas phase is dominated by Hg(g) at approx. *10-3 bar. The water phase may contain Hg(CH{sub 3}NH{sub 2}){sub 2}2+ if NO{sub 3}- for some reasons is introduced into the formation water, and the very carcinogenic dimethyl mercury compound, C{sub 2}HgH{sub 6}, can be formed in the gas phase. Both compounds, however, in insignificant low concentration/partial pressure. (Author)

  17. Removal of Hg{sup 0} from flue gases in wet FGD by catalytic oxidation with air - An experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Andrej Stergarsek; Milena Horvat; Peter Frkal; Jost Stergarsek [' Jozef Stefan' Institute, Ljubljana (Slovenia)

    2010-11-15

    Research efforts are being focused on the development of mercury removal technologies, mainly directed to two alternative approaches: (I) the enhancement of homogeneous oxidation in the flue gases of Hg{sup 0} to water soluble Hg{sup 2+} by the addition of chlorides or bromides to the boiler or; (ii) the adsorption of Hg{sup 2+} and Hg{sup 0} on impregnated activated carbon (AC). A third option gaining more attention lately is based on the oxidation and retention of dissolved Hg{sup 0} in the wet flue gas desulphurisation (FGD) system. The experimental evidence of the present work showed that Hg{sup 0} present in the gaseous phase can be dissolved and oxidized to a high degree (70-90%) by air together with SO{sub 3}{sup 2-} in wet FGD solutions. Transition metals such as Fe{sup 2+} and Mn{sup 2+} act as catalysts, chloride enhances the reaction, while some oxosulphur compounds, e.g. tetrathionate, inhibit the oxidation. A combination of several catalysts at a concentration of sulphite (SO{sub 3}{sup 2-}) below 100 mg L{sup -1} and an adequate redox potential of the solution can assure reasonable mercury removal even in the presence of oxidation inhibiting compounds. The main competitive reactions that govern final Hg{sup 0} removal in the FGD are as follows: (1) oxidation of Hg{sup 0} together with SO{sub 2} with air, enhanced by catalysts; (2) removal of catalysts by precipitation in the form of Fe(OH){sub 3} and eventually as MnO{sub 2} (to overcome this problem continuous addition of catalysts to the solution is required); (3) reduction of Fe{sup 3+} by tetrathionate to Fe{sup 2+} which (4) may reduce Hg{sup 2+} to Hg{sup 0} and probably (5) the complexation of Hg{sup 2+} by anions present which may play an important role in the mechanism by complexing the product(s) of the Hg{sup 0} oxidation reaction. 35 refs., 10 figs., 7 tabs.

  18. Determination of MeHg sources to fish in the St. Louis River, MN, USA, using Hg stable isotopes

    Science.gov (United States)

    Mercury contamination in the Great Lakes region has become a prevalent concern due to elevated methylmercury (MeHg) levels in fish. While atmospheric deposition of Hg is ubiquitous, releases from legacy point-sources give rise to numerous Areas of Concern (AOCs) across the Great ...

  19. Spatial trend and pollution assessment of total mercury and methylmercury pollution in the Pearl River Delta soil, South China.

    Science.gov (United States)

    Chen, Laiguo; Xu, Zhencheng; Ding, Xiaoyong; Zhang, Weidong; Huang, Yumei; Fan, Ruifang; Sun, Jiaren; Liu, Ming; Qian, Donglin; Feng, Yongbin

    2012-07-01

    Total mercury (THg) and methylmercury (MeHg) were measured in large number of soil samples collected from areas with different types of land use, different depth in the Pearl River Delta (PRD) of South China. THg and MeHg concentrations ranged from 16.7 to 3320ngg(-1) and 0.01 to 1.34ngg(-1), respectively. THg levels are highest in the top 0-20cm soil layer, and decrease from the surface to bottom layer soil. Spatial variation was observed with different types of land use. Urban parks had the highest concentrations and the other areas tended to decrease in the order of residential areas, industrial areas, vegetable fields, cereal fields, and woodlands. Temporal variation was also noted, and two relatively high THg contamination zones located in the northwestern part of the PRD have significantly expanded over the last two decades. Both THg and MeHg concentrations were correlated significantly with soil organic matter (OM), but not with soil pH. THg pollution status was evaluated using two assessment methods.

  20. Differential influences of Cu and Zn chronic exposure on Cd and Hg bioaccumulation in an estuarine oyster.

    Science.gov (United States)

    Liu, Fengjie; Wang, Wen-Xiong

    2014-03-01

    In this study, the effects of Cu and Zn exposure, alone and in combination, on the bioaccumulation of Cd and Hg were investigated in an estuarine oyster Crassostrea hongkongensis under different salinity gradients. We showed that Zn, but not Cu, exposure significantly enhanced the Cd bioaccumulation. In contrast, both Cu and Zn exposure significantly enhanced the Hg bioaccumulation. Combined exposure and salinity did not affect the metal interactions in oysters. The increased tissue concentrations of Cd or Hg were associated with their increased storage in inducible metal-binding ligands (e.g. metallothionein-like proteins, MTLP) by Cu/Zn exposure. The differential roles of Cu and Zn exposure in Cd and Hg bioaccumulation resulted from their contrasting ligand induction and affinities. Analysis of field collected oysters indicated that Cu/Zn exposure was a significant contributor to tissue concentrations of Cd, Cu and Hg. Overall, biochemical/physiological changes of the animals chronically exposed to metal stressors played a key role in affecting tissue concentrations of other metals. One metal's ability to enhance the bioaccumulation of other metals depended upon the relative affinities of the metals for MTLP.

  1. Methylmercury and sulfate-reducing bacteria in mangrove sediments from Jiulong River Estuary, China

    Institute of Scientific and Technical Information of China (English)

    Hao Wu; Haoliang Lu; Zhenhua Ding; Yang Liu; Jinling Liu; Haiyu Yan; Jiayong Pan; Liuqiang Li; Huina Lin; Guanghui Lin

    2011-01-01

    Estuaries are important sites for mercury (Hg) methylation, with sulfate-reducing bacteria (SRB) thought to be the main Hg methylators. Distributions of total mercury (THg) and methylmercury (MeHg) in mangrove sediment and sediment core from Jiulong River Estuary Provincial Mangrove Reserve, China were determined and the possible mechanisms of Hg methylation and their controlling factors in mangrove sediments were investigated. Microbiological and geochemical parameters were also determined.Results showed that SRB constitute a small fraction of total bacteria (TB) in both surface sediments and the profile of sediments. The content ofTHg, MeHg, TB, and SRB were (350± 150) rig/g, (0.47 ± 0.11) ng/g, (1.4 ×1011 ± 4.1 × 109) cfu/g dry weight (dw), and (5.0 × 106 ± 2.7 × 106) cfu/g dw in surficial sediments, respectively, and (240 ± 24) ng/g, (0.30 ± 0.15) ng/g, (1.9 × 1011± 4.2 × 1010) cfu/g dw, and (1.3× 106 ± 2.0 × 106) cfu/g dw in sediment core, respectively. Results showed that THg, MeHg, TB, MeHg/THg, salinity and total sulfur (TS) increased with depth, but total organic matter (TOM), SRB, and pH decreased with depth. Concentrations of MeHg in sediments showed significant positive correlation with THg, salinity, TS, and MeHg/THg, and significant negative correlation with SRB, TOM, and pH. It was concluded that other microbes, rather than SRB, may also act as main Hg methylators in mangrove sediments.

  2. Mother-embryo isotope (δ15N, δ13C) fractionation and mercury (Hg) transfer in aplacental deep-water sharks

    OpenAIRE

    Le Bourg, Baptiste; Kiszka, Jeremy; Bustamante, Paco

    2014-01-01

    International audience; Stable carbon (δ13C) and nitrogen (δ15N) isotopic values and total mercury (Hg) concentrations were analysed in muscle and liver of mothers and embryos of two aplacental shark species, Squalus megalops and Centrophorus moluccensis. Embryos of the two species had similar or lower isotopic values than their respective mothers, the only exception being for δ13C, which was higher in the liver of C. moluccensis embryos than in their mothers. Hg concentrations were systemati...

  3. Comparative assessment of Azolla pinnata and Vallisneria spiralis in Hg removal from G.B. Pant Sagar of Singrauli Industrial region, India.

    Science.gov (United States)

    Rai, Prabhat Kumar; Tripathi, B D

    2009-01-01

    The aim of the present work was to monitor the Hg pollution in water and sediments of G.B. Pant Sagar located in Singrauli Industrial Region, India and to suggest the efficient aquatic plants for its phytoremediation. The study assessed the comparative potential of a free floating water fern Azolla pinnata and submerged aquatic macrophyte Vallisneria spiralis to purify waters polluted by Hg. Six days laboratory experiments have been conducted to mark the percentage removal of Hg at initial concentration of 0.1, 0.5, 1.0 and 3.0 mg L(-1). The percentage removal of Hg was higher for A. pinnata (80-94%) than V. spiralis (70-84%). Likewise, the Hg accumulated in dry mass was much higher for A. pinnata and a high correlation (R(2) = 0.91 for A. pinnata and 0.99 for V. spiralis) was obtained between applied Hg doses and accumulated amounts in biomass. A concentration dependent decrease in chlorophyll a, protein, RNA, DNA and nutrients (NO(3-) and PO(4)(3-)) uptake was detected in A. pinnata and V. spiralis due to Hg toxicity. The decrease was more prominent in Azolla than Vallisneria. The results recommended the use of A. pinnata and V. spiralis to ameliorate the industrial effluents (thermal power, chlor-alkali and coal mine effluent) contaminated with Hg.

  4. Oxygen ordering in the high-T$_c$ superconductor HgBa$_2$CaCu$_2$O$_{6+\\delta}$ as revealed by perturbed angular correlation

    CERN Document Server

    Mendonca, Tania Melo; Haas, Heinz; Odier, Philippe; Tavares, Pedro; Silva, Manuel Ribeiro; Lopes, Armandina; Pereira, Andre; Goncalves, Joao Nuno; Amaral, Joao; Darie, Celine; Araujo, Joao Pedro

    2011-01-01

    Lattice sites and collective ordering of oxygen atoms in HgBa$_2$CaCu$_2$O$_{6+\\delta}$ were studied using the perturbed angular correlation (PAC) technique at ISOLDE/CERN. The electric field gradients (EFG) at $^{199m}$Hg nuclei have been measured as functions of oxygen doping on the Hg planes, above and below T$_c$. In comparison with the results obtained for oxygen and fluorine doping in Hg-1201, the analysis shows a different oxygen ordering exhibited by Hg-1212. Moreover, for all studied cases, the experimental results show that at a local scale there is non-uniform oxygen distribution. A series of ab initio EFG calculations allowed to infer that at low concentrations, regions without oxygen coexist with regions where O$_{2\\delta}$ dumbbell molecules are located at the center of the Hg mesh. On the other side, at high concentrations, O$_{2\\delta}$ dumbbell molecules coexist with single O$_\\delta$ atoms occupying the center of the Hg mesh. The present results suggest that oxygen sits on the Hg planes in t...

  5. RESPONSES OF MEMBRANE PROTECTION ENZYME SYSTEM OF TOBACCO LEAVES ON Hg, Cd AND Pb STRESSES IN SOIL%烟草叶片膜保护酶系统对土壤Hg,Cd,Pb胁迫的响应

    Institute of Scientific and Technical Information of China (English)

    严重玲; 林鹏; 王晓蓉

    2002-01-01

    采用盆栽实验,就烟草膜保护酶系统对土壤Hg,Cd,Pb胁迫的响应进行研究.结果表明:随着Hg,Cd,Pb浓度的增加,POD活性逐渐增加,CAT活性逐渐减小,SOD活性在三种元素共同作用时逐渐下降,在元素单一或两两作用时,SOD活性呈单峰曲线,但总体水平仍较低.土壤Hg,Cd,Pb的这种影响表现出三元素共同作用>两两元素作用>单一元素作用.影响的结果造成活性氧产生与清除之间的不平衡,致使相关生理生化过程紊乱.三种重金属对烟草活性氧清除系统的影响表现出明显地协同作用.%Pot experiment was used to study the responses of membrane protection enzyme system of tobac-co loves on Hg, Cd and Pb stresses in soil. The results showed that POD activity gradually increased with in-creasing concetrations of Hg, Cd and Pb. CAT and SOD activity gradually decreased under three heavy metalscommon existing and SOD variation curve showed unimodal curve under single or two elements existing withincrease of concentration of Hg, Cd and Pb. The effects of Hg, Cd and Pb in soil: three elemets together>twoelements together>single element only. The effects resulted in an imbalance -- activated oxygen produce andscavenge and physiological biochemical process disorder. There was a synergistic action for the effect of Hg, Cdand Pb in soil on membrane protection enzyme system in tobacco leaves.

  6. [Distribution of Mercury in Plants at Water-Level-Fluctuating Zone in the Three Gorges Reservoir].

    Science.gov (United States)

    Liang, Li; Wang, Yong-min; Li, Xian-yuan; Tang, Zhen-ya; Zhang, Xiang; Zhang, Cheng; WANG, Ding-yong

    2015-11-01

    The mercury (Hg) distribution and storage in plants at water-level-fluctuating zone (WLFZ) in the Three Gorges Reservoir were investigated by analyzing the total mercury(THg) and methylmercury ( MeHg) levels in different parts of plants collected from three typical sites including Shibaozhai, Zhenxi and Hanfeng Lake in WLFZ. The results indicated that THg and MeHg concentrations in plants ranged from (1.62 ± 0.57) to (49.42 ± 3.93) μg x kg(-1) and from (15.27 ± 7.09) to (1 974.67 ± 946.10) ng x kg(-1), respectively. In addition, THg levels in different plant parts followed the trend: root > leaf > stem, and similar trend for MeHg was observed with the highest level in root. An obvious spatial distribution was also found with the THg and MeHg levels in plants in Hanfeng higher than those in the same plants in the other two sampling sites (Shibaozhai and Zhenxi), and there was a difference of THg and MeHg storage in plants in various attitudes. The corresponding THg and MeHg storages were 145.3, 166.4, 124.3 and 88.2 mg x hm(-2), and 1.9, 2.7, 3.6 and 3.2 mg x hm(-2) in 145-150, 150-160, 160-170 and 170-175 m attitudes. The accumulation ability of dominant plants in WLFZ for THg (bioaccumulation factor, BAF 1).

  7. Viscosity Relaxation in Molten HgZnTe

    Science.gov (United States)

    Baird, James K.

    2002-01-01

    Because of its narrow electronic band-gap, HgZnTe solid solutions have been proposed as effective detectors for infrared radiation. To produce the best single crystals of these materials for this application, knowledge of the phase diagram that governs the freezing of the liquid is essential. Besides the phase diagram, however, some information concerning the thermophysical properties of the melt, such as viscosity, density, specific heat, and enthalpy of mixing, can also be useful. Of these thermophysical properties, the viscosity is perhaps of the most interest scientifically. Measurements using the oscillating cup method have shown that the isothermal melt requires tens of hours of equilibration time before a steady value of the viscosity can be achieved. Over this equilibration time, which depends upon temperature, the viscosity can increase by as much as a factor of two before reaching a steady state. We suggest that this relaxation phenomenon may be due to a slight polymerization of Te atoms in the melt. To account for the time dependence of the viscosity in the HgZnTe melt, we propose that the liquid acts as a solvent that favors the formation of Te atom chains. We suggest that as the melt is cooled from a high temperature to the temperature for measurement of the viscosity, a free radical polymerization of Te atoms begins. To estimate this average molecular weight, we use a simple free radical polymerization mechanism, including a depolymerization step, to calculate the time dependence to the concentration of each Te polymer molecular weight fraction. From these molecular weight fractions, we compute the weight average molecular weight of the distribution. Using the semi-empirical relation between average molecular weight and viscosity, we obtain a formula for the time dependence of the viscosity of the melt. Upon examining this formula, we find that the viscosity achieves a steady value when a balance is achieved between the rate of formation of the chains

  8. Biokinetics of Hg and Pb accumulation in the encapsulated egg of the common cuttlefish Sepia officinalis: Radiotracer experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lacoue-Labarthe, T., E-mail: tlacouel@gmail.com [Littoral, Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite de La Rochelle, 2 rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France); Warnau, M., E-mail: warnaumichel@yahoo.com [International Atomic Energy Agency - Marine Environment Laboratories, 4 Quai Antoine Ier, MC-98000 (Monaco); Metian, M. [Littoral, Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite de La Rochelle, 2 rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France); International Atomic Energy Agency - Marine Environment Laboratories, 4 Quai Antoine Ier, MC-98000 (Monaco); Oberhaensli, F. [International Atomic Energy Agency - Marine Environment Laboratories, 4 Quai Antoine Ier, MC-98000 (Monaco); Rouleau, C. [Institut Maurice-Lamontagne, 850 Route de la Mer, C.P. 1000, Mont-Joli, Quebec (Canada); Bustamante, P., E-mail: pbustama@univ-lr.fr [Littoral, Environnement et Societes (LIENSs), UMR 6250, CNRS-Universite de La Rochelle, 2 rue Olympe de Gouges, F-17042 La Rochelle Cedex 01 (France)

    2009-12-01

    Uptake and depuration kinetics of dissolved {sup 203}Hg and {sup 210}Pb were determined during the entire embryonic development of the eggs of the cuttlefish, Sepia officinalis (50 d at 17 {sup o}C). {sup 203}Hg and {sup 210}Pb were accumulated continuously by the eggs all along the development time reaching load/concentration ratio (LCR) of 467 {+-} 43 and 1301 {+-} 126 g, respectively. During the first month, most of the {sup 203}Hg and {sup 210}Pb remained associated with the eggshell indicating that the latter acted as an efficient shield against metal penetration. From this time onwards, {sup 203}Hg accumulated in the embryo, indicating that it passed through the eggshell, whereas {sup 210}Pb did not cross the chorion during the whole exposure time. It also demonstrated that translocation of Hg associated with the inner layers of the eggshell is a significant source of exposure for the embryo. This study highlighted that the maturing embryo could be subjected to the toxic effects of Hg in the coastal waters where the embryonic development is taking place.

  9. An investigation for the HgCdTe cleaning process

    Science.gov (United States)

    Lan, Tian-Yi; Wang, Nili; Zhao, Shuiping; Liu, Shi-Jia; Li, Xiang-Yang

    2014-11-01

    A new cleaning process for HgCdTe was designed - which used the improved SC-1,SC-2 and Br2- C2H5OH solutions as the main cleaning fluid and applied mega sound waves in the cleaning process. By analyzing the test results carried out on the HgCdTe surface, it was found that the material of HgCdTe for the application of new cleaning process was better than the one for the application of conventional cleaning process in the minority carrier lifetime, residual organic contamination, responsivity and specific detectivity.

  10. Doping and Diffusion in HgCdTe

    Science.gov (United States)

    1991-01-28

    In’i, -InT. Te - 1.8 ( - 3 .5 )h ( + 2.9 - 6/) TeT1’- Tej . 4 Hg rich HgCdTe Hg - 1.8 + 1.2 + 1.4 - 2p H - ’g, - H g j.. ’TI - tetrahedral position...A. Anderson, Appl. Phys. Lett. 53, 11.81 (1988). B. D. Patterson, Rev. Mod. Phys. 60, 69 (1988). 60 V. A. Singh , C. Weigel, J. W. Corbett, and L. M

  11. Assessment of Hg contamination and exposure to miners and schoolchildren at a small-scale gold mining and recovery operation in Thailand.

    Science.gov (United States)

    Umbangtalad, S; Parkpian, P; Visvanathan, C; Delaune, R D; Jugsujinda, A

    2007-12-01

    Gold extracted by Hg-amalgamation process, which can cause both health and environmental problems, is widespread in South East Asia including Myanmar, Laos, Cambodia, and Thailand. Small-scale gold mining operations have been carried out since the year 2000 in Phanom Pha District, Phichit Province, Thailand. Since no data is available for evaluating Hg exposure, an investigation of mercury (Hg) contamination and exposure assessment was carried out at this mine site. Environmental monitoring illustrated the total Hg in water was as high as 4 microg/l while Hg in sediment ranged between 102 to 325 microg/kg dry weight. Both Hg deposition from the air (1.28 microg/100 cm(2)/day) and concentration in surface soil (20,960 microg/kg dry weight) were elevated in the area of amalgamation. The potential of Hg exposure to miners as well as to schoolchildren was assessed. The concentrations of Hg in urine of 79 miners who were directly (group I) or indirectly (group II) involved in the gold recovery operation were 32.02 and 20.04 microg/g creatinine, respectively, which did not exceed regulatory limits (35 microg/g creatinine). Hair Hg levels in both groups (group I and group II) also were not significantly higher than the non-exposed group. In terms of risk factors, gender and nature of food preparation and consumption were the two significant variables influencing the concentration of Hg in urine of miners (P < 0.05). A hazard quotient (HQ) was estimated based on the inorganic Hg exposure of individual miners. The HQ values of group I were in a range 16 to 218 times higher than the safety level set as 1. By comparison the group II HQ index was very low (0.03-0.39). The miners in group I who worked and ate food from this area experienced potentially high exposure to Hg associated with the mining process. In a second Hg exposure assessment, a group of 59 schoolchildren who attended an elementary school near the gold mine site was evaluated for Hg exposure. A slightly higher

  12. Mercury correlations among blood, muscle, and hair of northern elephant seals during the breeding and molting fasts

    Science.gov (United States)

    Peterson, Sarah; Ackerman, Josh; Costa, Daniel P.

    2016-01-01

    Mercury (Hg) biomonitoring and toxicological risk assessments for marine mammals commonly sample different tissues, making comparisons to toxicity benchmarks and among species and regions difficult. Few studies have examined how life history events, such as fasting, influence the relationship between total Hg (THg) concentrations in different tissues. We evaluated the relationships between THg concentrations in blood, muscle, and hair of female and male northern elephant seals (Mirounga angustirostris) at the start and end of the breeding and molting fasts. The relationships between tissues varied among tissue pairs and differed by sampling period and sex. Blood and muscle were generally related at all time periods; however, hair, an inert tissue, did not strongly represent the metabolically active tissues (blood and muscle) at all times of year. The strongest relationships between THg concentrations in hair and those in blood or muscle were observed during periods of active hair growth (end of the molting period) or during time periods when internal body conditions were similar to those when the hair was grown (end of the breeding fast). Our results indicate that THg concentrations in blood or muscle can be translated to the other tissue type using the equations we developed, but that THg concentrations in hair were generally a poor index of internal THg concentrations except during the end of fasting periods.

  13. Incorporation of inorganic mercury (Hg{sup 2+}) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: The role of different plankton size fractions and species assemblages

    Energy Technology Data Exchange (ETDEWEB)

    Soto Cárdenas, Carolina, E-mail: sotocardenascaro@gmail.com [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina); Diéguez, Maria C. [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina); Ribeiro Guevara, Sergio [Laboratorio de Análisis por Activación Neutrónica, CAB, CNEA, Av. Bustillo Km 9.5, 8400, San Carlos de Bariloche, Río Negro (Argentina); Marvin-DiPasquale, Mark [United States Geological Survey, 345 Middlefield Rd./MS 480, Menlo Park, CA 94025 (United States); Queimaliños, Claudia P. [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina)

    2014-10-01

    In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg{sup 2+}) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg{sup 2+} by four plankton fractions (picoplankton: 0.2–2.7 μm; pico + nanoplankton: 0.2–20 μm; microplankton: 20–50 μm; and mesoplankton: 50–200 μm) obtained from four Andean Patagonian lakes, using the radioisotope {sup 197}Hg{sup 2+}. Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg{sup 2+} in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico + nanoplankton play a central role leading the incorporation of Hg{sup 2+} in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg{sup 2+} by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg{sup 2+} observed in all the plankton fractions. - Highlights: • Hg{sup 2+} incorporation in lake plankton fractions was studied using the isotope {sup 197}Hg{sup 2+}. • Hg{sup 2

  14. Four-year record of mercury wet deposition in one typical industrial city in southwest China

    Science.gov (United States)

    Qin, Caiqing; Wang, Yongmin; Peng, Yulong; Wang, Dingyong

    2016-10-01

    During the period from December 2010 to November 2014, long-term monitoring of Hg wet deposition was conducted at three sites in Chongqing. The four-year volume-weighted mean concentrations (VWC) of total mercury (THg) and methylmercury (MeHg) in precipitation were 34.25 ng L-1 and 0.48 ng L-1, respectively. The average annual wet deposition fluxes were 37.83 ± 11.53 μg m-2 yr-1 for THg and 0.61 ± 0.19 μg m-2 yr-1 for MeHg. Besides, the average proportion of MeHg in THg was 1.41%. These data were well ahead of values observed in most of other areas. The annual VWC of Hg rose remarkably in 2012 and then reached a plateau or climbed mildly in the following 2 years, while its annual wet deposition fluxes saw an upward trend throughout the whole period. In addition, the high figures of Hg concentration were generally found in the non-monsoon seasons, but its elevated wet deposition fluxes normally appeared in the rainy seasons. These characteristics of inter-annual and seasonal changes for VWC and fluxes were observed at every sampling site in this study as well. Besides, there were significantly spatial distributions for VWC and fluxes of THg in the descending order of the downtown (NA), the suburban (BB) and the controlled site (JY). While for MeHg, BB had the largest values, followed by NA and JY. So apart from THg load, the formation of MeHg was influenced by other factors in Chongqing, like the concentration of reactive mercury (RHg) in precipitation. Additionally, particulate bound mercury (PHg) is the dominant form among various Hg species, and atmospheric Hg is effectively eliminated during the initial period of the rain event and the below-cloud scavenging is the predominant mechanism contributing Hg to precipitation.

  15. The significance of cephalopod beaks in marine ecology studies: Can we use beaks for DNA analyses and mercury contamination assessment?

    Science.gov (United States)

    Xavier, José Carlos; Ferreira, Sónia; Tavares, Sílvia; Santos, Nuno; Mieiro, Cláudia Leopoldina; Trathan, Phil N; Lourenço, Sílvia; Martinho, Filipe; Steinke, Dirk; Seco, José; Pereira, Eduarda; Pardal, Miguel; Cherel, Yves

    2016-02-15

    Cephalopod beaks found in the diet of predators have been a major source of scientific information. In this study, we evaluated the usefulness of DNA and contaminants analysis (total mercury - T-Hg) in cephalopod beaks in order to assess their applicability as tools in marine ecology studies. We concluded that, when applying DNA techniques to cephalopod beaks from Antarctic squid species, when using flesh attached to those beaks, it was possible to obtain DNA and to successfully identify cephalopod species; DNA was not found on the beaks themselves. This study also showed that it is possible to obtain information on T-Hg concentrations in beaks: the T-Hg concentrations found in the beaks were 6 to 46 times lower than in the flesh of the same cephalopod species. More research on the relationships of mercury concentrations in cephalopod beaks (and other tissues), intra- and inter-specifically, are needed in the future.

  16. A simultaneous multiple species acute toxicity test comparing relative sensitivities of six aquatic organisms to HgCl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    McCrary, J.E.; Heagler, M.G. [McNeese State Univ., Lake Charles, LA (United States). Dept. of Biological and Environmental Science

    1995-12-31

    In the last few years there has been concern in the scientific community about observed declines in some amphibian species. These population declines could be reflecting a global phenomenon due to a general class sensitivity or may be part of a natural cycle. The suggestion of an overall greater sensitivity of amphibians is not supported. Studies show that amphibians, as a class, are neither more or less susceptible than fish to environmental conditions. Mercury has been found to be one of the most toxic of the heavy metals introduced into amphibian breeding waters. Six aquatic species were simultaneously exposed in a comparative acute toxicity test with mercury chloride: three amphibians, Rana catesbeiana (bullfrog), R. clamitans (green frog), and R. sphenocephala (southern leopard frog, formally classified as R. utricularia); two fish, Gambusia affinis (mosquitofish) and Notemigonus crysoleucas (golden shiner); one aquatic aligochaete, Lumbriculus variegatus (aquatic earthworm). The five test concentrations used were 1.4, 3.9, 12.0, 110.0, and 487.0 {micro}g Hg/L respectively. Ten organisms per species were randomly placed into the six test tanks (control and five concentrations), each species in a separate chamber. The resultant LC50-96hr values produced the following rank order: R. sphenocephala, 6.59 {micro}g Hg/L; R. clamitans, 14.7 {micro}g Hg/L; N. crysoleucas, 16.75 {micro}g Hg/L; L. variegatus, 43.72,ug Hg/L; G. affinis, 52.62 {micro}g Hg/L; R. catesbeiana, 63.36 {micro}g Hg/L. No general organism class sensitivity trend, for amphibians, was developed from this data, contrary to the implicit suggestions of some researchers.

  17. Impacts of TCDD and MeHg on DNA methylation in zebrafish (Danio rerio) across two generations.

    Science.gov (United States)

    Olsvik, Pål A; Williams, Timothy D; Tung, Hui-shan; Mirbahai, Leda; Sanden, Monica; Skjaerven, Kaja H; Ellingsen, Ståle

    2014-09-01

    This study aimed to investigate whether dioxin (TCDD) and methylmercury (MeHg) pose a threat to offspring of fish exposed to elevated concentrations of these chemicals via epigenetic-based mechanisms. Adult female zebrafish were fed diets added either 20 μg/kg 2,3,7,8 TCDD or 10 mg/kg MeHg for 47 days, or 10 mg/kg 5-aza-2'-deoxycytidine (5-AZA), a hypomethylating agent, for 32 days, and bred with unexposed males in clean water to produce F1 and F2 offspring. Global DNA methylation, promoter CpG island methylation and target gene transcription in liver of adult females and in 3 days post fertilization (dpf) F1 and F2 embryos were determined with HPLC, a novel CpG island tiling array containing 54,933 different probes and RT-qPCR, respectively. The results showed that chemical treatment had no significant effect on global DNA methylation levels in F1 (MeHg and TCDD) and F2 (MeHg) embryos and only a limited number of genes were identified with altered methylation levels at their promoter regions. CYP1A1 transcription, an established marker of TCDD exposure, was elevated 27-fold in F1 embryos compared to the controls, matching the high levels of CYP1A1 expression observed in F0 TCDD-treated females. This suggests that maternal transfer of TCDD is a significant route of exposure for the F1 offspring. In conclusion, the selected doses of TCDD and MeHg, two chemicals often found in high concentrations in fish, appear to have only modest effects on DNA methylation in F1 (MeHg and TCDD) and F2 (MeHg) embryos of treated F0 females.

  18. Quantum Calorimeters Based on HgCdTe Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's next generation of x-ray observation missions require x-ray calorimeters with superior energy resolution. Semimetallic HgTe has already proven itself as an...

  19. Quantum Calorimeters Based on HgCdTe Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's next generation of x-ray observation missions require x-ray calorimeters with superior energy resolution. Semimetallic HgTe has already proven itself as an...

  20. Properties of Light Hg, Pb and Po Isotopes

    CERN Document Server

    Muntian, I

    2003-01-01

    Quality of mass description for three different theoretical mass models is studied. Masses and deformations for Po, Pb and Hg isotopes are compared with experimental data. Gap in the proton single particle energy spectrum is discussed.

  1. Horizontal Branch stars as AmFm/HgMn stars

    CERN Document Server

    Michaud, G

    2008-01-01

    Recent observations and models for horizontal branch stars are briefly described and compared to models for AmFm stars. The limitations of those models are emphasized by a comparison to observations and models for HgMn stars.

  2. Interaction of Hg Atom with Bare Si(111) Surface

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-Jun; LIU Ying

    2006-01-01

    To evaluate the interaction between Hg atom and bare Si(111) surface, three types of silicon cluster models of Si4H7, Si7H10 and Si16H20 together with their Hg complexes were studied by using hybrid (U)B3LYP density functional theory method. Optimized geometries and energies for Hg atom on different adsorption sites indicate that: 1) the binding energies at different adsorption sites are small (ranging from ~3 to 8 kJ/mol dependent on the adsorption sites), suggesting a weak interaction between Hg atom and silicon surface; 2) the most favorable adsorption site is the on top (T) site. By analyzing their natural bonding orbitals, the possible reason of this difference is suggested.

  3. The sub-cellular fate of mercury in the liver of wild mullets (Liza aurata)--Contribution to the understanding of metal-induced cellular toxicity.

    Science.gov (United States)

    Araújo, Olinda; Pereira, Patrícia; Cesário, Rute; Pacheco, Mário; Raimundo, Joana

    2015-06-15

    Mercury is a recognized harmful pollutant in aquatic systems but still little is known about its sub-cellular partitioning in wild fish. Mercury concentrations in liver homogenate (whole organ load) and in six sub-cellular compartments were determined in wild Liza aurata from two areas - contaminated (LAR) and reference. Water and sediment contamination was also assessed. Fish from LAR displayed higher total mercury (tHg) organ load as well as in sub-cellular compartments than those from the reference area, reflecting environmental differences. However, spatial differences in percentage of tHg were only observed for mitochondria (Mit) and lysosomes plus microsomes (Lys+Mic). At LAR, Lys+Mic exhibited higher levels of tHg than the other fractions. Interestingly, tHg in Mit, granules (Gran) and heat-denaturable proteins was linearly correlated with the whole organ. Low tHg concentrations in heat stable proteins and Gran suggests that accumulated levels might be below the physiological threshold to activate those detoxification fractions.

  4. Human exposure to mercury in San Jorge river basin, Colombia (South America).

    Science.gov (United States)

    Olivero, Jesus; Johnson, Boris; Arguello, Eduardo

    2002-04-22

    During May-September 1999 human hair samples were collected from the village of Caimito, a fishing community of the state of Sucre (Colombia), in the San Jorge River basin area, and analyzed for total mercury (t-Hg) by cold vapor atomic absorption spectroscopy. T-Hg was measured in both male and female people aged 15-65 years, whose diet mainly consists of fish collected in nearby marshes. Average hair t-Hg concentration in people from Caimito was 4.91 +/- 0.55 microg/g (n = 94), similar to the value previously detected in fishermen living in the gold mining area, 50 km east. Males had similar t-Hg concentrations (4.31 +/- 0.42 microg/g; n = 56) to females (5.78 +/- 1.21 microg/g; n = 38) and there was no difference in t-Hg levels between groups of different age. Mercury content in hair was weakly but significantly associated (R = 0.20, P = 0.05) with fish consumption.

  5. A comparative study of accumulated total mercury among white muscle, red muscle and liver tissues of common carp and silver carp from the Sanandaj Gheshlagh Reservoir in Iran.

    Science.gov (United States)

    Khoshnamvand, Mehdi; Kaboodvandpour, Shahram; Ghiasi, Farzad

    2013-01-01

    The Sanandaj Gheshlagh Reservoir (SGR) is a mercury polluted lake that is located in the West of Iran. Common carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix) are the most abundant fishes in the SGR. A total of 48 common and silver carps (24 each) were captured randomly, using 50×6 m gill net (mesh size: 5×5 cm) during July to December 2009. Each month, the levels of accumulated total mercury (T-Hg) in white muscle, red muscle and liver tissues of these fishes were measured using an Advanced Mercury Analyzer (Model; Leco 254 AMA, USA) on the dry weight basis. There were no statistically significant differences between T-Hg concentrations in white muscle, red muscle and liver in common carp in comparison with similar tissues in silver carp (P>0.05). The content of T-Hg in liver tissue of both species was lower than of white and red muscle tissues. Higher levels of accumulated T-Hg were observed during summer. Results showed that T-Hg concentrations in common and silver carps target tissues were strongly dependent on age, length and weight (Ptissues of all samples with weights of over 850 g were greater than those limits established by WHO and FAO (500 ng g(-1)). Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Cardiac dysfunction in HgCl2-induced nephrotic syndrome.

    Science.gov (United States)

    Moreira-Rodrigues, Mónica; Henriques-Coelho, Tiago; Moura, Cláudia; Vasques-Nóvoa, Francisco; Sampaio-Maia, Benedita; Pestana, Manuel; Leite-Moreira, Adelino F

    2010-03-01

    The experimental model of HgCl(2) injection is characterized by a systemic autoimmune disease which leads to the development of nephrotic syndrome (NS). NS seems to be accompanied by cardiovascular alterations, since patients with NS present an increased incidence in cardiac disease. The aim of our work was to study the effects of HgCl(2)-induced NS on myocardial function and morphometry. Normotensive Brown-Norway rats were injected with HgCl(2) (1 mg/kg, HgCl(2) group; n = 6, subcutaneous) or the vehicle (control group; n = 6, subcutaneous) on days 0, 2, 4, 7, 9 and 11. The animals were placed in metabolic cages for evaluation of urinary excretion of noradrenaline, sodium, total proteins, albumin and creatinine. Fourteen and 21 days after the first HgCl(2) injection, left ventricle (LV) hemodynamics was evaluated through pressure micromanometers in basal and isovolumetric heartbeats. The heart and gastrocnemius muscle weights and tibial length were also examined. In an additional group of animals cardiac dimensions and ejection fraction were assessed by echocardiography and LV apoptosis and fibrosis were studied. HgCl(2)-injected rats presented proteinuria, albuminuria, hyperlipidemia, anemia, sodium retention and ascites at day 14. These alterations were accompanied by LV hemodynamic changes only in isovolumetric heartbeats. Similarly, on day 21, HgCl(2)-injected rats presented proteinuria, albuminuria, hyperlipidemia, anemia, but no sodium retention or ascites. These animals presented LV systolic and diastolic dysfunction in both basal and isovolumetric heartbeats, as well as cardiac atrophy, LV fibrosis and an increase in myocyte apoptosis. In conclusion, HgCl(2)-induced NS is accompanied by LV dysfunction and can be a promising model for studying the link between NS and cardiac disease.

  7. Searching for Line Profile Variability in HgMn Stars

    CERN Document Server

    Turcotte, S; Knoglinger, P

    2002-01-01

    Spectra of four non-magnetic chemically peculiar late B type stars (HgMn) stars are analysed to detect periodic spectral line variations (LPVs). A procedure developed to study LPVs in Slowly Pulsating B stars has been adopted as pulsational properties of HgMn stars should be expected to be similar. In the preliminary results discussed here no conclusive evidence for periodic LPVs was uncovered. A more sensitive re-analysis of the data is under way.

  8. First observation of excited states in 173Hg93

    CERN Document Server

    O'Donnell, D; Scholey, C; Bianco, L; Capponi, L; Carroll, R J; Darby, I G; Donosa, L; Drummond, M; Ertugral, F; Greenlees, P T; Grahn, T; Hauschild, K; Herzan, A; Jakobsson, U; Jones, P; Joss, D T; Julin, R; Juutinen, S; Ketelhut, S; Labiche, M; Leino, M; Lopez-Martens, A; Mullholland, K; Nieminen, P; Peura, P; Rahkila, P; Rinta-Antila, S; Ruotsalainen, P; Sandzelius, M; Saren, J; Saygi, B; Simpson, J; Sorri, J; Thornthwaite, A; Uusitalo, J

    2012-01-01

    The neutron-deficient nucleus 173Hg has been studied following fusion-evaporation reactions. The observation of gamma rays decaying from excited states are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighbouring neutron-deficient Hg nuclei. In addition to the gamma-ray spectroscopy, the alpha decay of this nucleus has been measured yielding superior precision to earlier measurements.

  9. Resonance Scattering Detection of Trace Hg2+ Using Aptamer-modified AuPd Nanoalloy Probe as Catalyst

    Institute of Scientific and Technical Information of China (English)

    刘庆业; 范燕燕; 梁爱惠; 蒋治良

    2011-01-01

    The 5 nm AuPd nanoalloy in mole ratio of Au:Pd=32 : 1 was prepared, using sodium citrate as the stabilizing agent and NaBH4 as the reductant. The AuPd nanoalloy was modified by the aptamer to prepare an aptamer- AuPd (AptAuPd) probe for resonance scattering (RS) detection of 5.(Y-1250 nmol/L Hg2+. The AptAuPd-Hg2+ aptamer reaction solution was filtrated by membrane, and the AptAuPd in the filtrate exhibited strong catalytic ef- fect on the slow NiP particle reaction between NiCI2 and NaHzPO2, and the NiP particles showed a RS peak at 508 nm. The RS intensity decreased when Hg2+ concentration increased. The decreased RS intensity was linear to Hg2+ concentration in the range of 0.5--1250 nmol/L. The RS assays were used to determine Hg2+ in real samples, with good results.

  10. Effect of salinity and temperature on the adsorption of Hg(II) from aqueous solutions by a Ca-montmorillonite.

    Science.gov (United States)

    Green-Ruiz, C

    2009-01-01

    Use of clay minerals for removing mercury is an effective technology for the treatment of industrial wastewaters and can become an effective tool for the remediation of coastal ecosystems polluted with this metal. Calcic montmorillonite was employed for adsorbing Hg(II) ions from aqueous solutions at different conditions of salinity (0, 20 and 35 g NaCl L(-1)), temperature (15, 25 and 35 degrees C), and initial concentrations (0.25, 0.50, 1.00, 2.50, 5.00 and 10.00 mg Hg L(-1)). It was observed that 0.4 g dry weight of montmorillonite removed from 0.02 mg g(-1) (at 0.25 mg L(-1) of Hg(II)) to 0.68 mg g(-1) (at 10.0 mg L(-1) of Hg(II)) at 25 degrees C, salinity of 0 g NaCl L(-1) and pH of 6. The initial concentration of Hg(II) and salinity had an effect on the behaviour of the adsorption process, which was temperature independent. The data fit well the Freundlich adsorption isotherm, indicating that heterogeneous conditions prevail in this process.

  11. Comparison of total Hg results in sediment samples from Rio Grande reservoir determine by NAA and CV AAS

    Energy Technology Data Exchange (ETDEWEB)

    Franklin, Robson L., E-mail: robsonf@cetesbnet.sp.gov.br [Centro Tecnologico de Saneamento Basico (ELAI/CETESB), SP, Sao Paulo (Brazil). Laboratorio de Quimica Inorganica; Bevilacqua, Jose Eduardo [Centro Tecnologico de Saneamento Basico (CETESB), SP, Sao Paulo (Brazil). UNIFIEO - Centro Universitario FIEO; Favaro, Deborah I.T., E-mail: defavaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Laboratorio de Analise por Ativacao Neutronica (LAN/CRPq)

    2011-07-01

    The Rio Grande reservoir is located in the Metropolitan area of Sao Paulo and it is used for recreation purposes and as source water for drinking water production. During the last decades has been detected mercury contamination in the sediments of this reservoir, mainly in the eastern part, near the main affluent of the reservoir, in the Rio Grande da Serra and Ribeirao Pires counties. In the present study bottom sediment samples were collected in four different sites into four sampling campaigns during the period of September 2008 to January 2010. The samples were dried at room temperature, ground and passed through a 2 mm sieve. Total Hg determination in the sediment samples was carried out by two different analytical techniques: neutron activation analysis (NAA) and cold vapor atomic absorption spectrometry (CV AAS). The methodology validation, in terms of precision and accuracy, was performed by reference materials, and presented a recovery of 83 to 108%. The total Hg results obtained by both analytical techniques ranged from 3 to 71 mg kg-1 and were considered similar by statistical analysis, even though NAA technique furnishes the total concentration while CV AAS using the 3015 digestion procedure characterizes only the bioavailable Hg. These results confirm that both analytical techniques were suitable to detect the Hg concentration levels in the Rio Grande sediments studied. The Hg levels in the sediment of the Rio Grande reservoir confirm the anthropogenic origin for this element in this ecosystem. (author)

  12. Kinetics of Hg(II) exchange between organic ligands, goethite, and natural organic matter studied with an enriched stable isotope approach.

    Science.gov (United States)

    Jiskra, Martin; Saile, Damian; Wiederhold, Jan G; Bourdon, Bernard; Björn, Erik; Kretzschmar, Ruben

    2014-11-18

    The mobility and bioavailability of toxic Hg(II) in the environment strongly depends on its interactions with natural organic matter (NOM) and mineral surfaces. Using an enriched stable isotope approach, we investigated the exchange of Hg(II) between dissolved species (inorganically complexed or cysteine-, EDTA-, or NOM-bound) and solid-bound Hg(II) (carboxyl-/thiol-resin or goethite) over 30 days under constant conditions (pH, Hg and ligand concentrations). The Hg(II)-exchange was initially fast, followed by a slower phase, and depended on the properties of the dissolved ligands and sorbents. The results were described by a kinetic model allowing the simultaneous determination of adsorption and desorption rate coefficients. The time scales required to reach equilibrium with the carboxyl-resin varied greatly from 1.2 days for Hg(OH)2 to 16 days for Hg(II)-cysteine complexes and approximately 250 days for EDTA-bound Hg(II). Other experiments could not be described by an equilibrium model, suggesting that a significant fraction of total-bound Hg was present in a non-exchangeable form (thiol-resin and NOM: 53-58%; goethite: 22-29%). Based on the slow and incomplete exchange of Hg(II) described in this study, we suggest that kinetic effects must be considered to a greater extent in the assessment of the fate of Hg in the environment and the design of experimental studies, for example, for stability constant determination or metal isotope fractionation during sorption.

  13. Crystal structure of K[Hg(SCN)3] - a redetermination.

    Science.gov (United States)

    Weil, Matthias; Häusler, Thomas

    2014-09-01

    The crystal structure of the room-temperature modification of K[Hg(SCN)3], potassium tri-thio-cyanato-mercurate(II), was redetermined based on modern CCD data. In comparison with the previous report [Zhdanov & Sanadze (1952 ▶). Zh. Fiz. Khim. 26, 469-478], reliability factors, standard deviations of lattice parameters and atomic coordinates, as well as anisotropic displacement parameters, were revealed for all atoms. The higher precision and accuracy of the model is, for example, reflected by the Hg-S bond lengths of 2.3954 (11), 2.4481 (8) and 2.7653 (6) Å in comparison with values of 2.24, 2.43 and 2.77 Å. All atoms in the crystal structure are located on mirror planes. The Hg(2+) cation is surrounded by four S atoms in a seesaw shape [S-Hg-S angles range from 94.65 (2) to 154.06 (3)°]. The HgS4 polyhedra share a common S atom, building up chains extending parallel to [010]. All S atoms of the resulting (1) ∞[HgS2/1S2/2] chains are also part of SCN(-) anions that link these chains with the K(+) cations into a three-dimensional network. The K-N bond lengths of the distorted KN7 polyhedra lie between 2.926 (2) and 3.051 (3) Å.

  14. Self-powered sensor for trace Hg2+ detection.

    Science.gov (United States)

    Wen, Dan; Deng, Liu; Guo, Shaojun; Dong, Shaojun

    2011-05-15

    A self-powered electrochemical sensor has been facilely designed for sensitive detection of Hg(2+) based on the inhibition of biocatalysis process of enzymatic biofuel cell (BFC) for the first time. The as-prepared one-compartment BFC, which was consisted of alcohol dehydrogenase supported on single-walled carbon nanohorns-based mediator system as the anode and bilirubin oxidase as the cathodic biocatalyst, generated an open circuit potential (V(oc)) of 636 mV and a maximum power density of 137 μW cm(-2). It was interestingly found that the presence of Hg(2+) would affect the performance of the constructed BFC (e.g., V(oc)). Taking advantage of the inhibitive effect of Hg(2+), a novel self-powered Hg(2+) sensor has been developed, which showed a linear range of 1-500 nM (R(2) = 0.999) with a detection limit of 1 nM at room temperature. In addition, this BFC-type sensor exhibited good selectivity for Hg(2+) against other common environmental metal ions, and the feasibility of the method for Hg(2+) detection in actual water samples (i.e., tap, ground, and lake water) was demonstrated with satisfactory results.

  15. Phytoremediation of Hg and Cd from industrial effluents using an aquatic free floating macrophyte Azolla pinnata.

    Science.gov (United States)

    Rai, Prabhat Kumar

    2008-01-01

    The level of heavy metal pollution in Singrauli, an industrial region in India, was assessed and the phytoremediation capacity of a small water fern, Azolla pinnata R.BR (Azollaceae), was observed to purify waters polluted by two heavy metals, i.e., mercury (Hg) and cadmium (Cd) under a microcosm condition. Azolla pinnata is endemic to India and is an abundant and easy-growing free-floating water fern usually found in the rice fields, polluted ponds, and reservoirs of India. The fern was grown in 24 40-L aquariums containing Hg2+ and Cd2+ ions each in concentrations of 0.5, 1.0, and 3.0 mgL(-1) during the course of this study. The study revealed an inhibition of Azolla pinnata growth by 27.0-33.9% with the highest in the presence of Hg (II) ions at 0.5 mgL(-1) in comparison to the control After 13 days of the experiment, metal contents in the solution were decreased up to 70-94%. In the tissues of Azolla pinnata, the concentration of selected heavy metals during investigation was recorded between 310 and 740 mgKg(-1) dry mass, with the highest levelfoundfor Cd (II) treatment at 3.0 mgL(-1) containing a metal solution.

  16. Carrier behavior of HgTe under high pressure revealed by Hall effect measurement

    Institute of Scientific and Technical Information of China (English)

    胡廷静; 崔晓岩; 李雪飞; 王婧姝; 吕秀梅; 王棱升; 杨景海; 高春晓

    2015-01-01

    We investigate the carrier behavior of HgTe under high pressures up to 23 GPa using in situ Hall effect measurements. As the phase transitions from zinc blende to cinnabar, then to rock salt, and finally to Cmcm occur, all the parameters change discontinuously. The conductivity variation under compression is described by the carrier parameters. For the zinc blende phase, both the decrease of carrier concentration and the increase of mobility indicate the overlapped valence band and conduction band separates with pressure. Pressure causes an increase in the hole concentration of HgTe in the cinnabar phase, which leads to the carrier-type inversion and the lowest mobility at 5.6 GPa. In the phase transition process from zinc blende to rock salt, Te atoms are the major ones in atomic movements in the pressure regions of 1.0–1.5 GPa and 1.8–3.1 GPa, whereas Hg atoms are the major ones in the pressure regions of 1.5–1.8 GPa and 3.1–7.7 GPa. The polar optical scattering of the rock salt phase decreases with pressure.

  17. Methylmercury concentrations in six fish species from two Colombian rivers.

    Science.gov (United States)

    Alvarez, Santiago; Jessick, Ashley M; Palacio, Jaime A; Kolok, Alan S

    2012-01-01

    The objective of this study was to determine whether fish collected from the La Miel or Nechí Rivers (Colombia) differed in muscle methyl mercury (meHg) concentration. Two fish from six different species were collected from markets adjacent to each river. Overall, fish collected from the market adjacent to the Nechí River contained higher levels of meHg. This result however is being driven by very high meHg concentrations in four individual fish, three of which are Pimelodid, long-whiskered catfish. These catfish may represent ideal sentinel organism for the detection of meHg contamination in Colombian rivers.

  18. Anisotropic silver nanoparticles deposited on zeolite a for selective Hg2+ colorimetric sensing and antibacterial studies

    Directory of Open Access Journals (Sweden)

    Khorshidi Alireza

    2015-01-01

    Full Text Available Silver nanoparticles deposited on the surface of zeolite A were prepared via post ion-exchange reduction, and reduction-deposition methods. Formation of the silver nanoparticles on the surface of zeolite A was verified by surface plasmon spectra using diffuse reflectance spectroscopy and ultraviolet-visible spectroscopy. Morphology of the prepared samples was characterized by X-ray diffraction and scanning electron microscopy. Furthermore, silver nanoparticles deposited on the zeolite A, after fixation of Rhodamine B dye molecules over themselves, were successful in detecting Hg2+ ions selectively. After treatment with the so-obtained sensor, color change from colorless to pink was visible to the naked eye for the Hg2+ solution concentrations down to 1.0×10-8 mol.L-1. Antibacterial tests demonstrated the multifunctional application of the silver nanoparticles deposited on zeolite A.

  19. Distributions of total mercury and methylmercury in surface sediments and fishes in Lake Shihwa, Korea.

    Science.gov (United States)

    Oh, Sehee; Kim, Moon-Kyung; Yi, Seung-Muk; Zoh, Kyung-Duk

    2010-02-01

    The concentrations of total mercury (THg) and methylmercury (MeHg) in the sediments of Lake Shihwa, an artificial salt lake in Korea located near two large industrial complexes, were determined to investigate the state of Hg contamination in the lake sediments and the effect of local Hg source. THg and MeHg concentrations in the sediments, monitored for 2 years, ranged from 0.02 to 0.28 microg g(-1) and rain events and water gate operation may be additional important factors regulating Hg level and distribution in lake sediments. The levels of THg in fish species in this lake ranged from 9.8 to 35 ng g(-1), suggesting that the bioavailability of sediment Hg in the lake may be low. Although the THg concentrations in Lake Shihwa sediment were lower than those in other foreign study sites, they were higher than in neighboring coastal regions, and are constantly increasing. This result indicates that the nearby industrial complexes may be the major source of Hg found in the sediments of Lake Shihwa. Copyright 2009 Elsevier B.V. All rights reserved.

  20. On the impedance of galvanic cells—XVII. The mechanism of the Zn2+/Zn(Hg) electrode reaction

    NARCIS (Netherlands)

    Sluyters-Rehbach, M.; Ijzermans, A.B.; Timmer, B.; Griffioen, J.B.; Sluyters, J.H.

    1966-01-01

    A theory is presented of the complex behaviour of the streaming zinc amalgam electrode in a Zn2+ solution. It is assumed that the Zn2+/Zn+ and the Zn+/Zn(Hg) electrode reactions occur at potentials where at the dropping amalgam electrode the Zn2+-resp. Zn-concentration at the electrode surface is vi

  1. Mercury distribution in sediment along urban-rural gradient around Shanghai (China): implication for pollution history.

    Science.gov (United States)

    Yang, Jing; Chen, Ling; Shi, Wei-Ling; Liu, Li-Zao; Li, Yue; Meng, Xiang-Zhou

    2015-02-01

    The increasing levels of heavy metals in the environment generally related with the rapid industrialization and urbanization. Mercury (Hg) is a global toxin with wide concerns, and China gradually becomes the main producer, consumer, and emitter of Hg in the world. However, few historical data are available on the occurrence of Hg in Chinese urban areas. Here, we collected 35 lake surface sediment samples from 35 public parks and 1 sediment core in the Luxun Park in Shanghai, a hyper-urbanization city in China, to determine the spatial and vertical distributions of total mercury (THg) and methylmercury (MeHg) and to explore the Hg pollution history with the industrial development. Higher concentrations of Hg and MeHg and greater Hg enrichment were found in urban areas compared with suburban area with the following order: central urban core area > developed urban area > developing urban area > suburban area. The THg concentration in the sediment core showed an increasing trend from 1876 to 2000 and a decreasing trend from 2000 to 2012, coinciding with the process of industrialization and urbanization in Shanghai. However, THg fluxes unceasingly increased from 1876 to present probably attributed to coal consumption in the suburban area and transportation agglomeration in the central urban core area. Unlike THg, no significant variations for MeHg with time and the maximum value (0.17 μg/kg) appeared in 1947. The methylation ratio of MeHg to THg in the sediment is pretty low, and more studies are needed to further understand the fate of Hg in the environment.

  2. Subcellular localization of several heavy metals of Hg,Cd and Pb in human liver

    Institute of Scientific and Technical Information of China (English)

    CHEN Chunying; ZHANG Peiqun; CHAI Zhifang

    2005-01-01

    Liver, as an important metabolic and detoxicological organ of human body, can be used as a good bioindicator for evaluating body burden of environmental pollutants. Its elemental contents and their chemical forms are closely related to the status of human health and disease. In this paper, the liver samples collected from normal subjects were separated to different subcellular fractions of nuclei, mitochondria, lysosome, microsome and cytosol by differential centrifugation. Then their concentrations of heavy metals of As, Pb, Cd, and Hg were determined by atomic absorption and atomic fluorescent spectroscopy. Our results show no significant difference with literature ones when comparing their gross concentrations. In the case of their subcellular distribution, the Hg concentrations are higher in mitochondrial, microsomal and cytosolic fractions; the Cd concentrations are higher in cytosolic and mitochondrial fractions, while As highest in nuclear fraction. The highest concentration of Pb is found in microsomal fraction with similarity to Fe. Mercury in liver is mainly in the form of inorganic, and methylmercury ranged from 9% to 50% with the average value of 20.9%(13.3%. These results indicate that the cellular distribution and the accumulated target organelles are quite different among these heavy metals, which suggest their various pathways and toxic mechanism in vivo.

  3. Hg $L_{3}$ edge absorption study of the $HgBa_{2}CuO_{4}\\delta$ superconductor

    CERN Document Server

    Ziyu, Wu; Bianconi, A

    2001-01-01

    The HgBa/sub 2/CuO/sub 4+ delta / superconductor has been studied by high resolution Hg L/sub 3/ X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectrum has been simulated by full multiple-scattering calculations in order to explore the origin of different features in the experimental spectrum. The experimental Hg L/sub 3/-edge spectrum could be well reproduced by considering a cluster of 85 atoms, containing 10 shells, within a radius of about 7 AA from the central Hg atom. The low energy spectral feature in the XANES spectrum is found to be due to a transition from the Hg p states to the electronic states hybridized with higher shell Ba atoms. This implies that the transition features in the Hg L/sub 3/- edge XANES are strongly influenced by medium range order effects unlike the case of L/sub 3/ edge of 3d transition metals where short- range order is enough to describe the main transition features. (25 refs).

  4. GNAQPMS-Hg v1.0, a global nested atmospheric mercury transport model: model description, evaluation and application to trans-boundary transport of Chinese anthropogenic emissions

    Directory of Open Access Journals (Sweden)

    H. S. Chen

    2014-10-01

    Full Text Available Atmospheric mercury (Hg is a toxic pollutant and can be transported over the whole globe due to its long lifetime in the atmosphere. For the purpose of assessing Hg hemispheric transport and better characterizing regional Hg pollution, a global nested atmospheric Hg transport model (GNAQPMS-Hg has been developed. In GNAQPMS-Hg, the gas and aqueous phase Hg chemistry representing the transformation among three forms of Hg: elemental mercury (Hg(0, divalent mercury (Hg(II, and primary particulate mercury (Hg(P are calculated. A detailed description of the model, including mercury emissions, gas and aqueous phase chemistry, and dry and wet deposition is given in this study. Worldwide observations including extensive data in China have been collected for model evaluation. Comparison results show that the model reasonably simulates the global mercury budget and the spatial–temporal variation of surface mercury concentrations and deposition. Overall, model predictions of annual total gaseous mercury (TGM and wet deposition agree with observations within a factor of two, and within a factor of five for oxidized mercury and dry deposition. The model performs significantly better in North America and Europe than in East Asia. This can probably be attributed to the large uncertainties in emission inventories, coarse model resolution and to the inconsistency between the simulation and observation periods in East Asia. Compared to the global simulation, the nested simulation shows improved skill at capturing the high spatial variability of Hg concentrations and deposition over East Asia. In particular, the root mean square error (RMSE of simulated Hg wet deposition over East Asia is reduced by 24% in the nested simulation. Model sensitivity studies indicate that Chinese primary anthropogenic emissions account for 30 and 62% of surface mercury concentrations and deposition over China, respectively. Along the rim of the western Pacific, the contributions

  5. Incorporation of inorganic mercury (Hg2+) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: the role of different plankton size fractions and species assemblages

    Science.gov (United States)

    Soto Cárdenas, Carolina; Diéguez, Maria C.; Ribeiro Guevara, Sergio; Marvin-DiPasquale, Mark; Queimaliños, Claudia P.

    2014-01-01

    In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg2+) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg2+ by four plankton fractions (picoplankton: 0.2–2.7 μm; pico + nanoplankton: 0.2–20 μm; microplankton: 20–50 μm; and mesoplankton: 50–200 μm) obtained from four Andean Patagonian lakes, using the radioisotope 197Hg2+. Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg2+ in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico + nanoplankton play a central role leading the incorporation of Hg2+ in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg2+ by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg2+ observed in all the plankton fractions.

  6. [Influence of inorganic ions and humic acid on the removal of Pb(II) and Hg(II) in water by zero-valent iron].

    Science.gov (United States)

    Shi, Qiu-Ling; Zhou, Xin; Zhang, Jin-Zhong; Qiu, Xin-Kai

    2014-08-01

    The effects of Ca2+, Cl- and humic acid (HA) on the removal rates of Pb(II) and Hg(II) in water by zero-valent (ZVI) and the kinetic characteristics were studied, and the removal mechanism of Pb(II) and Hg(II) by ZVI were preliminarily investigated using X-ray diffraction (XRD). The results indicated that the removal mechanism of Pb(II) might mainly be attributed to the adsorption and co-precipitation of ZVI, while that of Hg(II) might mainly be attributed to the oxidation-reduction of ZVI. With the increase of Ca2+ concentration, the removal rates of Hg(II) and Pb(II) showed the trends of gradual increase and slight decrease, respectively. The Hg(II) removal increased with increasing Cl- concentration, whereas no obvious increase in Pb(II) removal was observed. The removal rates of Hg(II) and Pb(II) showed the trends of slow increase and slow decrease with increasing HA concentration, respectively. When Ca2+, Cl- and HA coexisted, the removal rates of Hg(II) and Pb(II) reached 99.71% and 97.95%, respectively. The removal processes of Pb(II) and Hg(II) could be described by pseudo first-order reaction kinetic equations when Ca2+, Cl- and HA existed alone and in combination. The removal rate constant of Pb(II) was the maxinum (0.024 0 min(-1)) when 5 mg x L(-1) HA existed alone, whereas that of Hg(II) was the maximum (0.0169 min(-1)) when 0.80 mmol x L(-1) Ca2+ existed alone.

  7. Cytotoxicity of dental composite (co)monomers and the amalgam component Hg{sup 2+} in human gingival fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Reichl, Franz-Xaver; Simon, Sabine; Esters, Magalie; Seiss, Mario [Ludwig-Maximilians-University of Munich, Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Kehe, Kai [Bundeswehr Institute of Pharmacology and Toxicology, Munich (Germany); Kleinsasser, Norbert [University of Regensburg, Department of Otolaryngology - Head and Neck Surgery, Regensburg (Germany); Hickel, Reinhard [Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany)

    2006-08-15

    Unpolymerized resin (co)monomers or mercury (Hg) can be released from restorative dental materials (e.g. composites and amalgam). They can diffuse into the tooth pulp or the gingiva. They can also reach the gingiva and organs by the circulating blood after the uptake from swallowed saliva. The cytotoxicity of dental composite components hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (Bis-GMA) as well as the amalgam component Hg{sup 2+} (as HgCl{sub 2}) and methyl mercury chloride (MeHgCl) was investigated on human gingival fibroblasts (HGFs) at two time intervals. To test the cytotoxicity of substances, the bromodeoxyuridine (BrdU) assay and the lactate dehydrogenase (LDH) assay were used. The test substances were added in various concentrations and cells were incubated for 24 or 48 h. The EC{sub 50} values were obtained as half-maximum-effect concentrations from fitted curves. Following EC{sub 50} values were found [BrdU: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 8.860 (0.440)/6.600(0.630), TEGDMA 1.810(0.130)/1.220(0.130), UDMA 0.120(0.010)/0.140(0.010), BisGMA 0.060(0.004)/0.040(0.002), HgCl{sub 2} 0.015(0.001)/0.050(0.006), and MeHgCl 0.004(0.001)/0.005(0.001). Following EC{sub 50} values were found [LDH: mean (mmol/l); SEM in parentheses; n=12]: (24 h/48 h) HEMA 9.490(0.300)/7.890(1.230), TEGDMA 2.300(0.470)/1.950(0.310), UDMA 0.200(0.007)/0.100(0.007), BisGMA 0.070(0.005)/0.100(0.002), and MeHgCl 0.014(0.006)/0.010(0.003). In both assays, the following range of increased toxicity was found for composite components (24 and 48 h): HEMA < TEGDMA < UDMA < BisGMA. In both assays, MeHgCl was the most toxic substance. In the BrdU assay, Hg{sup 2+} was about fourfold less toxic than MeHgCl but Hg{sup 2+} was about fourfold more toxic than BisGMA. In the BrdU test, a significantly (P<0.05) decreased toxicity was observed for Hg{sup 2+} at 48 h, compared to the 24 h

  8. Mercury contamination in deposited dust and its bioaccumulation patterns throughout Pakistan.

    Science.gov (United States)

    Eqani, Syed Ali Musstjab Akber Shah; Bhowmik, Avit Kumar; Qamar, Sehrish; Shah, Syed Tahir Abbas; Sohail, Muhammad; Mulla, Sikandar I; Fasola, Mauro; Shen, Heqing

    2016-11-01

    Mercury (Hg) contamination of environment is a major threat to human health in developing countries like Pakistan. Human populations, particularly children, are continuously exposed to Hg contamination via dust particles due to the arid and semi-arid climate. However, a country wide Hg contamination data for dust particles is lacking for Pakistan and hence, human populations potentially at risk is largely unknown. We provide the first baseline data for total mercury (THg) contamination into dust particles and its bioaccumulation trends, using scalp human hair samples as biomarker, at 22 sites across five altitudinal zones of Pakistan. The human health risk of THg exposure via dust particles as well as the proportion of human population that are potentially at risk from Hg contamination were calculated. Our results indicated higher concentration of THg in dust particles and its bioaccumulation in the lower Indus-plain agricultural and industrial areas than the other areas of Pakistan. The highest THg contamination of dust particles (3000ppb) and its bioaccumulation (2480ppb) were observed for the Lahore district, while the highest proportion (>40%) of human population was identified to be potentially at risk from Hg contamination from these areas. In general, children were at higher risk of Hg exposure via dust particles than adults. Regression analysis identified the anthropogenic activities, such as industrial and hospital discharges, as the major source of Hg contamination of dust particles. Our results inform environmental management for Hg control and remediation as well as the disease mitigation on potential hotspots.

  9. Methyl mercury concentrations in edible fish and shellfish from Dunedin, and other regions around the South Island, New Zealand.

    Science.gov (United States)

    Sadhu, Ashish K; Kim, Jonathan P; Furrell, Hamish; Bostock, Ben

    2015-12-15

    Methyl mercury (MeHg) concentrations were determined in edible fish and shellfish available in local markets in Dunedin, New Zealand. While most of the fish species were sourced in Dunedin, some specimens of fish were also collected from waters off Picton, around Stewart Island and also off-shore of the South Island in the Puysegur and Subantarctic regions. The concentrations of MeHg were analysed in 25 different fish species and shellfish (103 muscle tissue samples). Total mercury (HgT) levels were also analysed in a few (n=12) selected fish samples. Most of the Hg was in the form of MeHg (≥ 96%). Higher MeHg concentrations were found in fish at higher trophic levels, particularly in predatory fish species such as ling, school shark, spiny dogfish and albacore tuna. Concentrations of MeHg in all samples ranged from 0.002 to 2.515 μg MeHg/g.

  10. Assessment of Cu, Pb and Hg Contamination in Bottom Sediments Of Surface Water in XuZhou

    Institute of Scientific and Technical Information of China (English)

    王晓; 韩宝平; 朱雪强

    2004-01-01

    Pollution of heavy metals Cu,Pb and Hg is assessed using geo-accumulation index in this paper. The result shows that the bottom sediments of surface water in Xuzhou is polluted by these heavy metals to deferent degrees, of which the Jinma River is the most serious, and then the Kuihe River, the abandoned Yellow River, and the Jinghang Canal. The Yunlong Lake has also been polluted by Hg. The three kinds of heavy metals in the order of concentration is Hg>Cu>Pb. The pollution degree and the type of element is closely related with industrial structure in Xuzhou.

  11. Interface Lattice Engineering of Si Composite Wafers for Large-Format HgCdTe Infrared Focal Plane Arrays

    Science.gov (United States)

    2012-08-07

    sessile dislocation. Examples of such sessile dislocation coalescence are the Lomer lock a 2 [011̄] + a 2 [101] → a 2 [110], (2.22) or a Lomer-Cottrell...Hg droplets condensing on to the layer. This will leave concentric circular marks where the Hg drop forms and evaporates away as seen in figure 5.2(d...sake, also assume that bα+ bβ = bsessile, where the result is a sessile dislocation. Finally, stipulate that when is near a side wall, α dislocations

  12. Mercury levels and estimated total daily intakes for children and adults from an electronic waste recycling area in Taizhou, China: Key role of rice and fish consumption.

    Science.gov (United States)

    Tang, Wei; Cheng, Jinping; Zhao, Wenchang; Wang, Wenhua

    2015-08-01

    In order to assess the potential health risks of Hg pollution, total mercury (T-Hg) and methyl mercury (MeHg) concentrations were determined in air, dust, surface soil, crops, poultry, fish and human hair samples from an electronic waste (e-waste) recycling area in Taizhou, China. High concentrations of T-Hg and MeHg were found in these multiple matrices, and the mean concentration was 30.7 ng/m(3) of T-Hg for atmosphere samples, 3.1 μg/g of T-Hg for soil, 37.6 μg/g of T-Hg for dust, 20.3 ng/g of MeHg for rice and 178.1 ng/g of MeHg for fish, suggesting that the e-waste recycling facility was a significant source of Hg. The inorganic Hg (I-Hg) levels (0.84 μg/g) in hair samples of e-waste workers were much higher than that in the reference samples. Pearson's correlation coefficients showed that strong positive correlations (phair I-Hg and time staying in industrial area (r=0.81) and between MeHg and fish consumption frequency (r=0.91), imply that workers were mainly exposed to Hg vapor through long-time inhalation of contaminated air and dust, while other population mainly exposed to MeHg through high-frequency fish consumption. The estimated daily intakes of Hg showed that dietary intake was the major Hg exposure source, and Hg intakes from rice and fish were significantly higher than from any other foods. The estimated total daily intakes (TDIs) of MeHg for both children (696.8 ng/(kg·day)) and adults (381.3 ng/(kg·day)) greatly exceeded the dietary reference dose (RfD) of 230 ng/(kg·day), implying greater health risk for humans from Hg exposures around e-waste recycling facilities.

  13. Mercury (Hg) burden in children: The impact of dental amalgam

    Energy Technology Data Exchange (ETDEWEB)

    Al-Saleh, Iman, E-mail: iman@kfshrc.edu.sa [Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, PO Box: 3354, Riyadh 11211 (Saudi Arabia); Al-Sedairi, Al anoud [Department of Zoology, College of Science, King Saud University, PO Box: 24452, Riyadh 11495 (Saudi Arabia)

    2011-07-15

    The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine ({mu}g/g creatinine) and micrograms per liter ({mu}g/L). We found that children with amalgam fillings (N = 106) had significantly higher UHg-C levels than children without (N = 76), with means of 3.763 {mu}g/g creatinine versus 3.457 {mu}g/g creatinine, respectively (P = 0.019). The results were similar for UHg (P = 0.01). A similar pattern was also seen for HHg, with means of 0.614 {mu}g/g (N = 97) for children with amalgam versus 0.242 {mu}g/g (N = 74) for those without amalgam fillings (P = 0). Although the mean NHg was higher in children without amalgam (0.222 {mu}g/g, N = 61) versus those with (0.163 {mu}g/g, N = 101), the relationship was not significant (P = 0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (P < 0.01). In contrast, a significant inverse relationship was seen between NHg levels and dental amalgam fillings (P = 0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and

  14. Mercury concentrations in different tissues of turtle and caiman species from the Rio Purus, Amazonas, Brazil.

    Science.gov (United States)

    Eggins, Sam; Schneider, Larissa; Krikowa, Frank; Vogt, Richard C; Da Silveira, Ronis; Maher, William

    2015-12-01

    Total mercury (Hg) concentrations of muscle, liver, blood, and epidermal keratin were measured in typically consumed, economically and culturally important species of turtle (Podocnemis unifilis and Podocnemis expansa) and caiman (Melanosuchus niger and Caiman crocodilus) from the Rio Purus in the Amazon basin, Brazil. Methylmercury (MeHg) concentrations were also measured in muscle tissue, representing the first analysis of MeHg concentrations in Amazonian reptile species. In muscle tissues Hg was mostly MeHg (79-96%) for all species. No correlations existed between animal size and total Hg or MeHg concentrations for any species other than M. niger, possibly as a result of growth dilution or the evolution of efficient Hg elimination mechanisms. Significant linear correlations were found between total Hg concentrations in all pairs of nonlethally sampled tissues (keratin and blood) and internal tissues (muscle and liver) for M. niger and between keratin and internal tissues for P. expansa, indicating that nonlethally sampled tissues can be analyzed to achieve more widespread and representative monitoring of Hg bioaccumulation in Amazonian reptiles. Although mean Hg concentrations in muscle for all species were below the World Health Organization guideline for safe consumption (500 µg kg(-1)), mean concentrations in caiman liver were above the safe limit for pregnant women and children (200 µg kg(-1)). No significant differences were found between total Hg and MeHg concentrations in tissues from wild-caught and farm-raised P. expansa, suggesting that farming may not reduce Hg exposure to humans. © 2015 SETAC.

  15. Spectroscopic variability and magnetic fields of HgMn stars

    CERN Document Server

    Hubrig, S; Ilyin, I; Korhonen, H; Savanov, I S; Dall, T; Schoeller, M; Cowley, C R; Briquet, M; Arlt, R

    2011-01-01

    The discovery of exotic abundances, chemical inhomogeneities, and weak magnetic fields on the surface of late B-type primaries in spectroscopic binaries has important implications not only for our understanding of the formation mechanisms of stars with Hg and Mn peculiarities themselves, but also for the general understanding of B-type star formation in binary systems. The origin of the abundance anomalies observed in late B-type stars with HgMn peculiarity is still poorly understood. The connection between HgMn peculiarity and membership in binary and multiple systems is supported by our observations during the last decade. The important result achieved in our studies of a large sample of HgMn stars is the finding that most HgMn stars exhibit spectral variability of various chemical elements, proving that the presence of an inhomogeneous distribution on the surface of these stars is a rather common characteristic and not a rare phenomenon. Further, in the studied systems, we found that all components are che...

  16. Are there tangled magnetic fields on HgMn stars?

    CERN Document Server

    Kochukhov, O; Piskunov, N; Jeffers, S V; Johns-Krull, C M; Keller, C U; Rodenhuis, M; Snik, F; Stempels, H C; Valenti, J A

    2013-01-01

    Several recent spectrophotometric studies failed to detect significant global magnetic fields in late-B HgMn chemically peculiar stars, but some investigations have suggested the presence of strong unstructured or tangled fields in these objects. We used detailed spectrum synthesis analysis to search for evidence of tangled magnetic fields in high-quality observed spectra of 8 slowly rotating HgMn stars and one normal late-B star. We also evaluated recent sporadic detections of weak longitudinal magnetic fields in HgMn stars based on the moment technique. Our analysis of the Zeeman broadening of magnetically sensitive spectral lines reveals no evidence of tangled magnetic fields in any of the studied HgMn or normal stars. We infer upper limits of 200-700 G for the mean magnetic field modulus -- much smaller than the field strengths implied by studies based on differential magnetic line intensification and quadratic field diagnostics. The new HARPSpol longitudinal field measurements for the extreme HgMn star H...

  17. Hydrological mobilization of mercury and dissolved organic carbon in a snow-dominated, forested watershed: Conceptualization and modeling

    Science.gov (United States)

    Schelker, J.; Burns, Douglas A.; Weiler, M.; Laudon, H.

    2011-01-01

    The mobilization of mercury and dissolved organic carbon (DOC) during snowmelt often accounts for a major fraction of the annual loads. We studied the role of hydrological connectivity of riparian wetlands and upland/wetland transition zones to surface waters on the mobilization of Hg and DOC in Fishing Brook, a headwater of the Adirondack Mountains, New York. Stream water total mercury (THg) concentrations varied strongly (mean = 2.25 ?? 0.5 ng L -1), and the two snowmelt seasons contributed 40% (2007) and 48% (2008) of the annual load. Methyl mercury (MeHg) concentrations ranged up to 0.26 ng L-1, and showed an inverse log relationship with discharge. TOPMODEL-simulated saturated area corresponded well with wetland areas, and the application of a flow algorithm based elevation-above-creek approach suggests that most wetlands become well connected during high flow. The dynamics of simulated saturated area and soil storage deficit were able to explain a large part of the variation of THg concentrations (r2 = 0.53 to 0.72). In contrast, the simulations were not able to explain DOC variations and DOC and THg concentrations were not correlated. These results indicate that all three constituents, THg, MeHg, and DOC, follow different patterns at the outlet: (1) the mobilization of THg is primarily controlled by the saturation state of the catchment, (2) the dilution of MeHg suggests flushing from a supply limited pool, and (3) DOC dynamics follow a pattern different from THg dynamics, which likely results from differing gain and/or loss processes for THg and/or DOC within the Fishing Brook catchment. Copyright 2011 by the American Geophysical Union.

  18. Numerical modeling of HgCdTe solidification: effects of phase diagram double-diffusion convection and microgravity level

    Science.gov (United States)

    Bune, Andris V.; Gillies, Donald C.; Lehoczky, Sandor L.

    1997-07-01

    A numerical model of HgCdTe solidification was implemented using finite the element code FIDAP. Model verification was done using both experimental data and numerical test problems. The model was used to eluate possible effects of double- diffusion convection in molten material, and microgravity level on concentration distribution in the solidified HgCdTe. Particular attention was paid to incorporation of HgCdTe phase diagram. It was found, that below a critical microgravity amplitude, the maximum convective velocity in the melt appears virtually independent on the microgravity vector orientation. Good agreement between predicted interface shape and an interface obtained experimentally by quenching was achieved. The results of numerical modeling are presented in the form of video film.

  19. Mercury (Hg2+) effect on enzyme activities and hepatopancreas histostructures of juvenile Chinese mitten crab Eriocheir sinensis

    Science.gov (United States)

    Zhao, Yanmin; Wang, Xinhua; Qin, Yanwen; Zheng, Binghui

    2010-05-01

    We studied the effects of mercury (Hg2+) on antioxidant and digestive enzyme activities in terms of LC50 value and on hepatopancreas histostructures of juvenile Chinese mitten crabs Eriocheir sinensis in 40-day exposure to various concentrations of Hg2+ (0, 0.01, 0.05, 0.10, 0.20, and 0.30 mg/L). The results show that the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) significantly increased in the concentrations of 0.01 and 0.05 mg/L, while that of enzyme decreased in 0.10, 0.20 and 0.30 mg/L treatments. Meanwhile, Hg2+ disrupted the histostructures of the hepatopancreas, causing decreases in activities of pepsin, tryptase, amylase, and cellulose, which are synthesized in the hepatopancreas. Moreover, as the Hg2+ concentration increased, the survival rate of the crabs decreased, worst at 56.57% in 0.30 mg/L. Therefore, although crabs are able to tolerate low levels of mercury pollution, high levels lead to cellular injury and tissue damage in hepatopancreas, which then loses some of its vital physiological functions such as absorption, storage, and secretion.

  20. Competitive adsorption of Cd, Cu, Hg and Pb by agricultural soils of the Changjiang and Zhujiang deltas in China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Soils can often be contaminated simultaneously by more than one heavy metal. The sorption-desorption behavior of a metal in a soil will be affected by the presence of other metals. Therefore, selective retention and competitive adsorption of the soils to heavy metals can affect their availability and movement through the soils. In this study, the simultaneous competitive adsorption of four heavy metals (Cd, Cu, Hg, and Pb) on ten agricultural soils collected from the Changjiang and Zhujiang deltas,China was assessed. The results showed that the competition affected the behavior of heavy metal cations in such a way that the soils adsorbed less Cd and Hg, and more Pb and Cu with increasing total metal concentrations, regardless of the molar concentration applied. As the applied concentrations increased, Pb and Cu adsorption increased, while Cd and Hg adsorption decreased.The adsorption sequence most found was Pb>Cu>Hg>Cd. The maximum adsorption capacity for the heavy metal cations was calculated, and affected markedly by soil properties. The results suggest that Hg and Cd have higher mobility associated to the lower adsorption and that Pb and Cu present the opposite behavior. Significant correlations were found between the maximum adsorption capacity of the metals and pH value and exchangeable acid, suggesting that soil pH and exchangeable acid were key factors controlling the solubility and mobility of the metals in the agricultural soils.

  1. Growth and characterization of Hg(1-x)Zn(x)Se

    Science.gov (United States)

    Andrews, R. N.

    1986-01-01

    Hg sub 1-xZn sub xSe alloys of composition x=0.10 were grown in a Bridgman-Stockbarger growth furnace at translation rates of 0.3 and 0.1 micron sec. The axial and radial composition profiles were determined using precision density measurements and IR transmission-edge-mapping, respectively. A more radially homogeneous alloy was produced at the slower growth rate, while the faster growth rate produced more axially homogeneous alloys. A determination of the electrical properties of the Hg sub 1-xZn sub xSe samples in the temperature range 300K-20K was also made. Typical carrier concentrations were on the order of magnitude of 10 to the 18th power cu/cm, and remained fairly constant as a function of temperature. A study was also made of the temperature dependence of the resistivity and Hall mobility. The effect of annealing in a selenium vapor on both the IR transmission and the electrical properties was determined. Annealing was effective in reducing the number of native donor defects and at the resulting lower carrier concentrations, charge carrier concentration was shown to be a function of temperature. Annealing caused the mobility to increase, primarily at the lower temperature, and the room temperature resistivity to increase. Annealing was also observed to greatly enhance the % IR transmittance of the samples. This was due primarily to the effect of annealing on decreasing the charge carrier concentration.

  2. Mercury concentrations of bluegill (Lepomis macrochirus) vary by sex

    Science.gov (United States)

    Madenjian, Charles P.; Francis, James T.; Braunscheidel, Jeffrey J.; Bohr, Joseph R.; Geiger, Matthew J.; Knottnerus, G. Mark

    2015-01-01

    Patterns in relative differences in contaminant concentrations between the sexes across many species of fish may reveal clues for important behavioral and physiological differences between the sexes, and may also be useful in developing fish consumption advisories and efficient designs for programs meant to monitor contaminant levels in fish. We determined skin-off fillet and whole-fish total mercury (Hg) concentrations of 28 adult female and 26 adult male bluegills (Lepomis macrochirus) from Squaw Lake, Oakland County, Michigan (MI), USA. Bioenergetics modeling was used to quantify the effect of growth dilution on the difference in Hg concentrations between the sexes. On average, skin-off fillet and whole-fish Hg concentrations were 25.4% higher and 26.6% higher, respectively, in females compared with males. Thus, the relative difference in Hg concentrations between the sexes for skin-off fillets was nearly identical to that for whole fish. However, mean skin-off fillet Hg concentration (363 ng/g) was 2.3 times greater than mean whole-fish Hg concentration (155 ng/g). Males grew substantially faster than females, and bioenergetics modeling results indicated that the growth dilution effect could account for females having 14.4% higher Hg concentrations than males. Our findings should be useful in revising fish consumption advisories.

  3. Mercury pollution in Rana Chensinensis in Weisha River reach, in the upstream region of Songhua River

    Institute of Scientific and Technical Information of China (English)

    WANG Ning; ZHU Yanming; SHENG Lianxi; MENG Dan

    2005-01-01

    Twice a year continuous samples of Rana Chensinensis and sediments have been collected near gold mine in the upstream region of Songhua River from 2000 to 2002, for analyzing the total mercury (THg), methylmercury (MeHg) concentration and correlation in sediments, muscles, livers of the frog. The study indicates that THg and MeHg concentrations in polluted samples near the gold mine are higher than those in unpolluted ones. THg and MeHg concentrations are higher in autumn, in female, and in livers than those in spring, in male, in muscles respectively. The order of concentration degree in the frog organizations is as follows: liver>muscle>ovum>Fallopian tube. MeHg is the main form of mercury (Hg) existing in autumn, while inorganic Hg is in spring. There is no distinct difference of CMeHg/CTHg between male and female, livers and muscles. The correlation between MeHg concentrations in the river sediments and in the frog's livers and muscles are significant, which is related to disorderly discharge of Hg.

  4. Phase transition study in a [Cu2HgI4 : 0.AgI] mixed composite system

    Indian Academy of Sciences (India)

    Noorussaba; Afaq Ahmad

    2010-08-01

    A novel composite superionic system, [Cu2HgI4 : 0.AgI], ( = 0.2, 0.4, 0.6 mol wt.%), was prepared. A [Cu2HgI4] system was used as the host. Electrical conductivity was measured to study the transition behaviour at frequencies of 100 Hz, 120 Hz, 1 kHz and 10 kHz in the temperature range 90–170°C using a Gen Rad 1659 RLC Digibridge. Conductivity increased sharply during the – phase transition. Upon increasing the dopant-to-host ratio, the conductivity of the superionic system exhibited Arrhenius (thermally activated)-type behaviour. DTA, DTG, TGA and X-ray powder diffraction were performed to confirm doping effect and transition in the host. The phase transition temperature increased with an increase in the dopant concentration. Activation energies in eV for pre- and post-transition phase behaviour are also reported. Due to an interaction between [Cu2HgI4] and AgI, the addition of AgI to [Cu2HgI4] shifted the phase transition of the host [Cu2HgI4].

  5. Adsorption of Hg(II from Aqueous Solution Using Adulsa (Justicia adhatoda Leaves Powder: Kinetic and Equilibrium Studies

    Directory of Open Access Journals (Sweden)

    Mohd Aslam

    2013-01-01

    Full Text Available The ability of Adulsa leaves powder (ALP to adsorb Hg(II from aqueous solutions has been investigated through batch experiments. The ALP biomass was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The experimental parameters that were investigated in this study included pH, adsorbent dosage, and effect of contact time along with initial metal ion concentration. The adsorption process was relatively fast, and equilibrium was achieved after 40 min of contact time. The maximum removal of Hg(II, 97.5% was observed at pH 6. The adsorption data were correlated with Langmuir, Freundlich, and Temkin isotherms. Isotherms results were amply fitted by the Langmuir model determining a monolayer maximum adsorption capacity (qm of ALP biomass equal to 107.5 mg g−1 and suggesting a functional group-limited sorption process. The kinetic process of Hg(II adsorption onto ALP biomass was tested by applying pseudofirst-order, pseudosecond-order, Elovich, and intraparticle-diffusion models to correlate the experimental data and to determine the kinetic parameters. It was found that the pseudosecond order kinetic model for Hg(II adsorption fitted very well. The rate determining step is described by intraparticle diffusion model. These studies considered the possibility of using Adulsa plant leaves biomass as an inexpensive, efficient, and environmentally safe adsorbent for the treatment of Hg(II contaminated wastewaters.

  6. Selective adsorption of Hg(II) by γ-radiation synthesized silica-graft-vinyl imidazole adsorbent.

    Science.gov (United States)

    Sun, Jian; Chen, Zhimin; Ge, Mengyi; Xu, Ling; Zhai, Maolin

    2013-01-15

    Silica-based adsorbent was prepared by γ-radiation induced grafting of vinyl imidazole (VIM) onto the silanized silica, which was silanized by chlorotrimethylsilane (TMCS). The effects of monomer concentration and absorbed dose on the grafting yield were investigated to optimize the reaction conditions. Thermodynamic analysis, FTIR analysis and XPS spectra manifested that VIM was successfully grafted onto the silica surface. The SS-g-VIM adsorbent had excellent selectivity for Hg(II) adsorption in mixture divalent cationic metal solution and a high adsorption capacity of Hg(II). The theoretical maximum adsorption capacity was calculated to be 355.9 mg g(-1) (1.774 mmol g(-1)) in HgCl(2)/HNO(3) solution at pH 5 at room temperature. The adsorption kinetics and adsorption isotherm were investigated. It was found that the Langmuir isotherm model fitted well with the adsorption process and the adsorption of Hg(II) onto SS-g-VIM adsorbent could be considered as a spontaneous, endothermic and chemical sorption process. The comprehensive results suggested that SS-g-VIM adsorbent has potential application for the removal of Hg(II) from wastewater.

  7. Highly enhanced adsorption for the removal of Hg(II) from aqueous solution by Mercaptoethylamine/Mercaptopropyltrimethoxysilane functionalized vermiculites.

    Science.gov (United States)

    Tran, Lytuong; Wu, Pingxiao; Zhu, Yajie; Yang, Lin; Zhu, Nengwu

    2015-05-01

    Vermiculites modified with Mercaptoethylamine (MEA) and 3-Mercaptopropyltrimethoxysilane (MPTMS) were used as effective adsorbents for the removal of Hg(II) from aqueous solution. The physicochemical characteristics of the pristine and functionalized vermiculites were analyzed by XRD, BET, FTIR, SEM, TEM and Zeta potentials, confirming that the vermiculite was successfully functionalized by the organic ligands containing the thiol (SH) metal-chelating groups. Batch adsorption experiments demonstrated that the factors such as initial pH, contact time, temperature, coexisting cations and initial Hg(II) concentration could significantly influence the adsorption behaviors typically for VER and MEA-VER, whereas the adsorption capacity of MPTMS-VER showed negligible dependence on such factors. The maximum adsorption capacity of Hg(II) ions was greatly improved after functionalization, which was in the order of MPTMS-VER>MEA-VER>VER (286.29 μg g(-1), 176.33 μg g(-1), 99.95 μg g(-1), respectively). The adsorption isotherm could be well described with Langmuir model and the kinetic studies indicated that the adsorption process fitted well with the pseudo-second-order model. The calculated thermodynamic parameters suggested that the adsorption process was feasible and spontaneous. The adsorption mechanism of Hg(II) on thiol groups was studied through XPS analysis. Considering the favorable adsorption capacities, thiol-functionalized vermiculites show a promising application in the removal of Hg(II) from wastewater.

  8. Projected Hg dietary exposure of 3 bird species nesting on a contaminated floodplain (South River, Virginia, USA).

    Science.gov (United States)

    Wang, Jincheng; Newman, Michael C

    2013-04-01

    Dietary Hg exposure was modeled for Carolina wren (Thryothorus ludovicianus), Eastern song sparrow (Melospiza melodia), and Eastern screech owl (Otus asio) nesting on the contaminated South River floodplain (Virginia, USA). Parameterization of Monte-Carlo models required formal expert elicitation to define bird body weight and feeding ecology characteristics because specific information was either unavailable in the published literature or too difficult to collect reliably by field survey. Mercury concentrations and weights for candidate food items were obtained directly by field survey. Simulations predicted the probability that an adult bird during breeding season would ingest specific amounts of Hg during daily foraging and the probability that the average Hg ingestion rate for the breeding season of an adult bird would exceed published rates reported to cause harm to other birds (>100 ng total Hg/g body weight per day). Despite the extensive floodplain contamination, the probabilities that these species' average ingestion rates exceeded the threshold value were all <0.01. Sensitivity analysis indicated that overall food ingestion rate was the most important factor determining projected Hg ingestion rates. Expert elicitation was useful in providing sufficiently reliable information for Monte-Carlo simulation.

  9. Tolerance and hyperaccumulation of a mixture of heavy metals (Cu, Pb, Hg, and Zn) by four aquatic macrophytes.

    Science.gov (United States)

    Romero-Hernández, Jorge Alberto; Amaya-Chávez, Araceli; Balderas-Hernández, Patricia; Roa-Morales, Gabriela; González-Rivas, Nelly; Balderas-Plata, Miguel Ángel

    2017-03-04

    In the present investigation, four macrophytes, namely Typha latifolia (L.), Lemna minor (L.), Eichhornia crassipes (Mart.) Solms-Laubach, and Myriophyllum aquaticum (Vell.) Verdc, were evaluated for their heavy metal (Cu, Pb, Hg, and Zn) hyperaccumulation potential under laboratory conditions. Tolerance analyses were performed for 7 days of exposure at five different treatments of the metals mixture (Cu(+2), Hg(+2), Pb(+2), and Zn(+2)). The production of chlorophyll and carotenoids was determined at the end of each treatment. L. minor revealed to be sensitive, because it did not survive in all the tested concentrations after 72 hours of exposure. E. crassipes and M. aquaticum displayed the highest tolerance to the metals mixture. For the most tolerant species of aquatic macrophytes, The removal kinetics of E. crassipes and M. aquaticum was carried out, using the following mixture of metals: Cu (0.5 mg/L) and Hg, Pb, and Zn 0.25 mg/L. The obtained results revealed that E. crassipes can remove 99.80% of Cu, 97.88% of Pb, 99.53% of Hg, and 94.37% of Zn. M. aquaticum withdraws 95.2% of Cu, 94.28% of Pb, 99.19% of Hg, and 91.91% of Zn. The obtained results suggest that these two species of macrophytes could be used for the phytoremediation of this mixture of heavy metals from the polluted water bodies.

  10. Gold nanoparticles generated through "green route" bind Hg2+ with a concomitant blue shift in plasmon absorption peak.

    Science.gov (United States)

    Radhakumary, C; Sreenivasan, K

    2011-07-21

    We discuss here a quick, simple, economic and ecofriendly method through a completely green route for the selective detection of Hg(2+) in aqueous samples. Here we exploited the ability of chitosan to generate gold nanoparticles and subsequently to act as a stabilizer for the formed nanoparticles. When chitosan stabilized gold nanoparticles (CH-Au NPs) are interacted with Hg(2+) a blue shift for its localized surface plasmon resonance absorbance (LSPR) band is observed. The blue shift is reasoned to be due to the formation of a thin layer of mercury over gold. A concentration as low as 0.01 ppm to a maximum of 100 ppm Hg(2+) can be detected based on this blue shift of the CH-Au NPs. While all other reported methods demand complex reaction steps and costly chemicals, the method we reported here is a simple, rapid and selective approach for the detection of Hg(2+). Our results also show that the CH-Au NPs have excellent selectivity to Hg(2+) over common cations namely, Pb(2+), Cd(2+), Mn(2+), Fe(2+), Ag(1+), Ce(4+), Ni(2+), and Cu(2+).

  11. Mercury contamination and stable isotopes reveal variability in foraging ecology of generalist California gulls

    Science.gov (United States)

    Peterson, Sarah; Ackerman, Josh; Eagles-Smith, Collin A.

    2017-01-01

    Environmental contaminants are a concern for animal health, but contaminant exposure can also be used as a tracer of foraging ecology. In particular, mercury (Hg) concentrations are highly variable among aquatic and terrestrial food webs as a result of habitat- and site-specific biogeochemical processes that produce the bioaccumulative form, methylmercury (MeHg). We used stable isotopes and total Hg (THg) concentrations of a generalist consumer, the California gull (Larus californicus), to examine foraging ecology and illustrate the utility of using Hg contamination as an ecological tracer under certain conditions. We identified four main foraging clusters of gulls during pre-breeding and breeding, using a traditional approach based on light stable isotopes. The foraging cluster with the highest δ15N and δ34S values in gulls (cluster 4) had mean blood THg concentrations 614% (pre-breeding) and 250% (breeding) higher than gulls with the lowest isotope values (cluster 1). Using a traditional approach of stable-isotope mixing models, we showed that breeding birds with a higher proportion of garbage in their diet (cluster 2: 63–82% garbage) corresponded to lower THg concentrations and lower δ15N and δ34S values. In contrast, gull clusters with higher THg concentrations, which were more enriched in 15N and 34S isotopes, consumed a higher proportion of more natural, estuarine prey. δ34S values, which change markedly across the terrestrial to marine habitat gradient, were positively correlated with blood THg concentrations in gulls. The linkage we observed between stable isotopes and THg concentrations suggests that Hg contamination can be used as an additional tool for understanding animal foraging across coastal habitat gradients.

  12. Assessment of Individual and Combined Toxicities of Four Non-Essential Metals (As, Cd, Hg and Pb in the Microtox Assay

    Directory of Open Access Journals (Sweden)

    Paul B. Tchounwou

    2006-03-01

    Full Text Available Although most researches with non-essential metals (NEMs have been done with single or individual metals, in reality, organisms are often exposed to multiple contaminants at the same time through the air, food and water. In this study, we tested the toxicity of four NEMs, As, Cd, Pb, and Hg, individually and as a composite mixture using the microtox bioassay. This assay uses the reduction of bioluminescence of the bacterium Vibrio fischeri as a measure of toxicity. The concentrations of each chemical in the mixture were based on multiples of their maximum contaminant levels (MCLs set by the U.S. EPA. The highest concentration of exposure was 20 times the MCL, which translated into 200, 100, 40 and 300 ppb for As, Cd, Hg and Pb, respectively. The ratio for the mixture from these concentrations was 10:5:2:15 for As, Cd, Hg and Pb, respectively. Among the individual metals tested, the ranking of toxicity was Hg>Pb>Cd>As based on the EC50 values of 109, 455, 508 and 768 ppb for Hg, Pb, Cd and As, respectively. The EC50 for the composite mixture was 495% MCL which translated into nominal concentrations of 49, 25, 10 and 74 ppb for As, Cd, Hg, and Pb, respectively. Overall, the EC50 value of each NEM within the mixture was lower than the EC50 of the individual chemical; an evidence of synergism for the mixture. The individual toxic units (TU were 0.06, 0.05, 0.09, and 0.16 for As, Cd Hg, and Pb, respectively and the summed toxic unit (TU was 0.37 (less than 1. This study provides needed scientific data necessary for carrying out complete risk assessment of As, Cd, Hg, and Pb mixtures of some priority compounds.

  13. Burrowing dragonfly larvae as biosentinels of methylmercury in freshwater food webs.

    Science.gov (United States)

    Haro, Roger J; Bailey, Sean W; Northwick, Reid M; Rolfhus, Kristofer R; Sandheinrich, Mark B; Wiener, James G

    2013-08-06

    We assessed the utility of larval burrowing dragonflies (Odonata: Anisoptera: Gomphidae) as biosentinels of methylmercury (MeHg) contamination. Gomphids were the most abundant family of dragonflies sampled during 2008-2010 from 17 lakes in four national parks of the northwestern Laurentian Great Lakes region. Ten species of burrowing gomphids were sampled; 13 lakes contained 3 or more species, and 2 species of Gomphus co-occurred in 12 lakes. Most of the total Hg (THg) in whole, late-instar larvae was MeHg, with mean percent MeHg exceeding 60% in 16 lakes. Mean MeHg in larvae of a given species varied greatly among lakes, ranging from 4 to 109 ng g(-1) dry weight. Methylmercury levels in larvae, however, were much less variable within a given lake and species. The mean concentration of MeHg in burrowing gomphids was positively correlated with mean MeHg concentration in unfiltered lake water. Mean concentrations of THg and MeHg in multispecies assemblages of Gomphus were also positively correlated with mean THg in coexisting prey fish and game fishes. We recommend-and provide guidance on-the application of burrowing gomphids as biosentinels of MeHg contamination, which can extend the bioassessment of MeHg to fishless fresh waters.

  14. Human exposure and risk assessment associated with mercury pollution in the Caqueta River, Colombian Amazon.

    Science.gov (United States)

    Olivero-Verbel, Jesus; Carranza-Lopez, Liliana; Caballero-Gallardo, Karina; Ripoll-Arboleda, Adriana; Muñoz-Sosa, Diego

    2016-10-01

    Mercury (Hg) is a global contaminant posing severe risks to human health worldwide. The aim of this study was to assess the levels of total Hg (T-Hg) in human hair and fish in the Caqueta River, at the Colombian Amazon, as well as to determine fish consumption-based risks for T-Hg ingestion. T-Hg levels were measured using a direct mercury analyzer. The overall mean T-Hg level in hair for humans in the Caqueta River sample (n = 200) was 17.29 ± 0.61 μg/g (1.2 to 47.0 μg/g). Ninety-four percent of the individuals had hair T-Hg concentrations greater than the WHO threshold level (5 μg/g), and 79 % displayed levels higher than 10 μg/g. Average Hg concentrations in fish varied between 0.10-0.15 μg/g and 0.10-1.60 μg/g, for noncarnivorous and carnivorous species, respectively. Based on the maximum allowable fish consumption rate for adults, most carnivorous species should be avoided in the diet, as their target hazard quotient ranged from 2.96 up to 31.05, representing a risk for Hg-related health problems. In the light of existing evidence for elevated Hg levels in the indigenous population of the Colombian Amazon, carnivorous fish should be restricted as part of the diet, and breastfeeding should be reduced to protect children health. Most importantly, gold mining activities directly on rivers demand immediate attention from the national government to avoid extensive damage on the environment and human health.

  15. Evaluating mercury biomagnification in fish from a tropical marine environment using stable isotopes (delta13C and delta15N).

    Science.gov (United States)

    Al-Reasi, Hassan A; Ababneh, Fuad A; Lean, David R

    2007-08-01

    Concentrations of total mercury (T-Hg) and methylmercury (MeHg) were measured in zooplankton and 13 fish species from a coastal food web of the Gulf of Oman, an arm of the Arabian Sea between Oman and Iran. Stable isotope ratios (delta13C and delta15N) also were determined to track mercury biomagnification. The average concentration of T-Hg in zooplankton was 21 +/- 8.0 ng g(-1) with MeHg accounting 10% of T-Hg. Total mercury levels in fish species ranged from 3.0 ng g(-1) (Sardinella longiceps) to 760 ng g(-1) (Rhizoprionodon acutus) with relatively lower fraction of MeHg (72%) than that found in other studies. The average trophic difference (Deltadelta13C) between zooplankton and planktivorous fish (Selar crumenopthalmus, Rastrelliger kanagurta, and S. longiceps) was higher (3.4 per thousandth) than expected, suggesting that zooplankton may not be the main diet or direct carbon source for these fish species. However, further sampling would be required to compensate for temporal changes in zooplankton and the influence of their lipid content. Trophic position inferred by delta15N and and slopes of the regression equations (log10[T-Hg] = 0.13[delta15N] - 3.57 and log10[MeHg] = 0.14[delta15N] - 3.90) as estimates of biomagnification indicate that biomagnification of T-Hg and MeHg was lower in this tropical ocean compared to what has been observed in arctic and temperate ecosystems and tropical African lakes. The calculated daily intake of methylmercury in the diet of local people through fish consumption was well below the established World Health Organization (WHO) tolerable daily intake threshold for most of the fish species except Euthynnus affinis, Epinephelus epistictus, R. acutus, and Thunnus tonggol, illustrating safe consumption of the commonly consumed fish species.

  16. Mercury concentrations in amphipods and fish of the Saint Lawrence River (Canada) are unrelated to concentrations of legacy mercury in sediments.

    Science.gov (United States)

    Hodson, Peter V; Norris, Kristin; Berquist, Michelle; Campbell, Linda M; Ridal, Jeffrey J

    2014-10-01

    Past industrial activity at Cornwall, Ontario, Canada has contaminated Lake Saint Francis, a fluvial lake on the Saint Lawrence River, with mercury (Hg). A spatial survey of Hg concentrations in sediments, amphipods, and yellow perch (Perca flavescens) in 2008 inferred current sources of Hg to the lake and spatial variations in risks to human consumers. Patterns of total and methyl Hg concentrations in sediment reflected upstream inputs, declining concentrations downstream, and highest concentrations at north shore sites near industrial sources; concentrations were lowest on the south shore because river currents limit north-south advective exchange. Surprisingly, concentrations of total or methyl Hg in sediments and pore water were unrelated to concentrations in amphipods and yellow perch. Concentrations in biota, and risks to consumers of fish, were highest at north shore sites near tributaries, and not at the most contaminated industrial sites. These results suggest that 'legacy' Hg in surficial sediments is not bioavailable to aquatic biota; tributaries and atmospheric deposition are possible sources of bioavailable Hg; and that sediment remediation would not resolve issues of Hg in fish. Fish consumption advisories for the entire lake based on single samples of fish could over- or under-protect consumers, depending on sampling location. To understand the actual risk to fish consumers for a large and complex lake system with multiple sources of Hg, more intensive sampling is needed to assess the spatial distribution of risk.

  17. Tail-end Hg capture on Au/carbon-monolith regenerable sorbents.

    Science.gov (United States)

    Izquierdo, M Teresa; Ballestero, Diego; Juan, Roberto; García-Díez, Enrique; Rubio, Begoña; Ruiz, Carmen; Pino, M Rosa

    2011-10-15

    In this work, a regenerable sorbent for Hg retention based on carbon supported Au nanoparticles has been developed and tested. Honeycomb structures were chosen in order to avoid pressure drop and particle entrainment in a fixed bed. Carbon-based supports were selected in order to easily modify the surface chemistry to favour the Au dispersion. Results of Hg retention and regeneration were obtained in a bench scale experimental installation working at high space velocities (for sorbent, 53,000 h(-1); for active phase, 2.6 × 10(8) h(-1)), 120 °C for retention temperature and Hg inlet concentration of 23 ppbv. Gold nanoparticles were shown to be the active phase for mercury capture through an amalgamating mechanism. The mercury captured by the spent sorbent can be easily released to be disposed or reused. Mercury evolution from spent sorbents was followed by TPD experiments showing that the sorbent can be regenerated at temperatures as low as 220 °C.

  18. Solid phase extraction and determination of sub-ppb levels of hazardous Hg2+ ions.

    Science.gov (United States)

    Shamsipur, Mojtaba; Shokrollahi, Ardeshir; Sharghi, Hashem; Eskandari, Mohammad Mehdi

    2005-01-31

    A simple, rapid and reliable method has been developed to selectively separate and concentrate ultra trace amounts of mercury(II) ions from aqueous samples for its highly sensitive measurement by cold vapor atomic absorption spectrometry (CV-AAS). The Hg(2+) ions were adsorbed selectively and quantitatively during the passage of aqueous samples through octadecyl silica membrane disks modified by isopropyl 2-[(isopropoxycarbothiolyl)disulfanyl]ethane thioate (IIDE). The retained Hg(2+) ions were then stripped from the disk with minimal amounts of 0.5 M hydrobromic acid (two 8 ml portions) as eluent, and determined by CV-AAS. The break-through volume of the method is greater than 3000 ml, which results in enrichment factors >150. Maximum capacity of the membrane disks modified with 10mg of the ligand was found to be 350+/-30 microg of mercury(II), and the limit of detection is 0.005 ng ml(-1). The effect of various cationic interferences on the recovery of mercury in binary mixtures was studied. The method was applied to the recovery of Hg(2+) ions from different synthetic and tap water samples, as well as the determination of mercury in human hair samples.

  19. Facilitated transport of Hg(II) through novel activated composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Paez-Hernandez, M.E. [Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Materiales, Area de Ciencia de los Materiales, Col. Reynosa-Tamaulipas (Mexico); Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Pachuca, Hidalgo (Mexico); Aguilar-Arteaga, K. [Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Pachuca, Hidalgo (Mexico); Valiente, M. [Universitat Autonoma de Barcelona, Departament de Quimica, Unitat Analitica, Centre GTS, Facultat de Ciencies, Bellaterra, Barcelona (Spain); Ramirez-Silva, M.T. [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de Quimica, Area de Quimica Analitica, Laboratorio R-105, Col. Vicentina, Mexico D.F. (Mexico); Romero-Romo, M.; Palomar-Pardave, M. [Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Materiales, Area de Ciencia de los Materiales, Col. Reynosa-Tamaulipas (Mexico)

    2004-10-01

    The results presented in this work deal with the prime application of activated composite membranes (ACMs) for the transport of Hg(II) ions in a continuous extraction-re-extraction system using di-(2-ethylhexyl)dithiophosphoric acid (DTPA) as carrier. The effects of variables such as the pH, the nature of the acid and the concentration of the casting solutions on the transport of Hg(II) are also investigated. When the ACM was prepared with a 0.5 M DTPA solution and when the feed solution contained 2.5 x 10{sup -4} M Hg(II) in 0.1 M HCl, the amount of mercury extracted was greater than 76%. The re-extracted mercury was subsequently recovered by means of a stripping phase comprising 0.3 M thiourea solution in 2 M H{sub 2}SO{sub 4}, yielding 54% of the initial amount of mercury after transport had taken place for 180 min. (orig.)

  20. Graphene field-effect transistors with tunable sensitivity for high performance Hg (II) sensing

    Science.gov (United States)

    Li, Peng; Liu, Baijun; Zhang, Dongzhi; Sun, Yan'e.; Liu, Jingjing

    2016-10-01

    Graphene field-effect transistors (FETs) capped with ionophore were fabricated to demonstrate the highly sensitive and selective detection of Hg (II) ions in solution. We systematically investigated the ion detection performances and sensing mechanism of this 2D material. Due to its ambipolar nature, graphene can work as either an n-type or a p-type sensor when a gate voltage is applied to switch its carrier characteristic, resulting in completely different sensing performances. The strong dependence of sensitivity on gate voltage was also investigated. Graphene FETs in optimal regimes were able to detect Hg2+ down to 0.1 ppb, one-fold lower than the World Health Organization tolerance level. Hg2+ ions can be effectively detected over a wide range of concentration (from 0.1 ppb to 1000 ppb) with graphene conductance change following the Langmuir isotherm for molecules adsorption on surface, and the time constant for ion adsorption extracted was only 3.5 s, approximately. The transfer characteristics of graphene FETs capped with mercury ionophore did not show obvious change by the existence of arsenite ions, demonstrating good selectivity. Our results illustrate the potential utility of ionophore integrated graphene FETs for monitoring heavy metal ions in solution.

  1. N-containing Ag(I) and Hg(II) complexes: a new class of antibiotics.

    Science.gov (United States)

    Sabounchei, Seyyed Javad; Shahriary, Parisa

    2013-01-01

    Several classes of antimicrobial compounds are presently available; microorganism's resistance to these drugs constantly emerges. In order to prevent this serious medical problem, the elaboration of new types of antibacterial agents or the expansion of bioactivity of the naturally known biosensitive compounds is a very interesting research problem. The synthesis and characterization of metal complexes with organic bioactive ligands is one of the promising fields for the search. The biological activities of the metal complexes differ from those of either the ligand or the metal ion. The results obtained thus far have led to the conclusion that structural factors, which govern antimicrobial activities, are strongly dependent on the central metal ion. A review of papers dealing with the Ag(I) and Hg(II) complexes of N donor ligands is presented. These metal complexes of N-chelating ligands have attracted considerable attention because of their interesting physicochemical properties and pronounced biological activities. This review will mainly focus on the preparation procedures and antibacterial properties of free organic ligands and the corresponding complexes. Finally, a research about antimicrobial properties of new Hg(II) complexes with 5-methyl-5-(4-pyridyl)-2,4-imidazolidenedione (L) and various halogen ions, HgL2X2 (X = Cl¯ (49), Br¯ (50), and I¯ (51)), is reported. Noteworthy antimicrobial activities, evaluated by minimum inhibitory concentration, for these complexes were observed.

  2. Crystal structure of Hg2SO4 – a redetermination

    Directory of Open Access Journals (Sweden)

    Matthias Weil

    2014-09-01

    Full Text Available The crystal structure of mercury(I sulfate (or mercurous sulfate, Hg2SO4, was re-determined based on modern CCD data. In comparison with the previous determination from Weissenberg film data [Dorm (1969. Acta Chem. Scand. 23, 1607–1615], all atoms were refined with anisotropic displacement parameters, leading to higher precision in terms of bond lengths and angles [e.g. Hg—Hg = 2.5031 (7 compared to 2.500 (3Å]. The structure consists of alternating rows along [001] of Hg22+ dumbbells (generated by inversion symmetry and SO42− tetrahedra (symmetry 2. The dumbbells are linked via short O—Hg—Hg—O bonds to the sulfate tetrahedra into chains extending parallel to [20-1]. More remote O—Hg—Hg—O bonds connect these chains into a three-dimensional framework.

  3. Characterization studies of purified HgI{sub 2} precursors

    Energy Technology Data Exchange (ETDEWEB)

    Schieber, M. E-mail: Schieber@vms.huji.ac.il; Zuck, A.; Sanguinetti, S.; Montalti, M.; Braiman, M.; Melekhov, L.; Nissenbaum, J.; Grilli, E.; Guzzi, M.; Turchetta, R.; Dulinski, W.; Husson, D.; Riester, J.L

    1999-06-01

    The ability of HgI{sub 2} powders, used as precursors in mercuric iodide crystal growth, to produce high-quality detectors may be predicted by non-destructive methods like photoluminescence. In fact, it is possible to correlate the presence and the intensity ratio of specific bands in the photoluminescence spectrum of a HgI{sub 2} crystal to its impurity content and stoichiometry. These quantities determine the detector grade that may be achieved using that starting material. Nine different HgI{sub 2} precursors, obtained by different purification methods, have been characterized. The lowest impurity content is achieved via poly-ethylene treatment, which gives also a powder of relatively good stoichiometric quality.

  4. Anti-aggregation-based spectrometric detection of Hg(II) at physiological pH using gold nanorods.

    Science.gov (United States)

    Rajeshwari, A; Karthiga, D; Chandrasekaran, Natarajan; Mukherjee, Amitava

    2016-10-01

    An efficient detection method for Hg (II) ions at physiological pH (pH7.4) was developed using tween 20-modified gold nanorods (NRs) in the presence of dithiothreitol (DTT). Thiol groups (-SH) at the end of DTT have a higher affinity towards gold atoms, and they can covalently interact with gold NRs and leads to their aggregation. The addition of Hg(II) ions prevents the aggregation of gold NRs due to the covalent bond formation between the -SH group of DTT and Hg(II) ions in the buffer system. The changes in the longitudinal surface plasmon resonance peak of gold NRs were characterized using a UV-visible spectrophotometer. The absorption intensity peak of gold NRs at 679nm was observed to reduce after interaction with DTT, and the absorption intensity was noted to increase by increasing the concentration of Hg(II) ions. The TEM analysis confirms the morphological changes of gold NRs before and after addition of Hg(II) ions in the presence of DTT. Further, the aggregation and disaggregation of gold NRs were confirmed by particle size and zeta potential analysis. The developed method shows an excellent linearity (y=0.001x+0.794) for the graph plotted between the absorption ratio and Hg(II) concentration (1 to 100pM) under the optimized conditions. The limit of detection was noted to be 0.42pM in the buffer system. The developed method was tested in simulated body fluid, and it was found to have a good recovery rate. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Mercury bioaccumulation in wood frogs developing in seasonal pools

    Science.gov (United States)

    Loftin, Cynthia S.; Calhoun, Aram J. K.; Nelson, Sarah J.; Elskus, Adria; Simon, Kevin S.

    2012-01-01

    Seasonal woodland pools contribute significant biomass to terrestrial ecosystems through production of pool-breeding amphibians. The movement of amphibian metamorphs potentially transports toxins bioaccumulated during larval development in the natal pool into the surrounding terrestrial environment. We documented total mercury (THg) in seasonal woodland pool water, sediment, litter, and Lithobates sylvaticus LeConte (Wood Frog) in Acadia National Park, ME. THg concentrations in pool water varied over the study season, increasing during April—June and remaining high in 2 of 4 pools upon October refill. Water in pools surrounded by softwoods had lower pH, greater dissolved organic carbon, and greater THg concentrations than pools surrounded by hardwoods, with seasonal patterns in sediment THg but not litter THg. THg increased rapidly from near or below detection in 1–2 week old embryos (<0.2 ng; 0–0.49 ppb wet weight) to 17.1–54.2 ppb in tadpoles within 6 weeks; 7.2–42.0% of THg was methyl Hg in tadpoles near metamorphosis. Metamorphs emigrating from seasonal pools may transfer mercury into terrestrial food webs.

  6. Hydrothermal synthesis of alpha- and beta-HgS nanostructures

    Science.gov (United States)

    Galain, Isabel; María, Pérez Barthaburu; Ivana, Aguiar; Laura, Fornaro

    2017-01-01

    We synthesized HgS nanostructures by the hydrothermal method in order to use them as electron acceptors in hybrid organic-inorganic solar cells. We employed different mercury sources (HgO and Hg(CH3COO)2) and polyvinylpyrrolidone (PVP) or hexadecanethiol (HDT) as stabilizing/capping agent for controlling size, crystallinity, morphology and stability of the obtained nanostructures. We also used thiourea as sulfur source, and a temperature of 180 °C during 6 h. Synthesized nanostructures were characterized by powder X-Ray Diffraction, Diffuse Reflectance Infrared Fourier Transform and Transmission Electron Microscopy. When PVP acts as stabilizing agent, the mercury source has influence on the size -but not in morphology- of the beta-HgS obtained nansostructures. HDT has control over nanostructures' size and depending on the relation Hg:HDT, we obtained a mixture of alpha and beta HgS which can be advantageous in the application in solar cells, due their absorption in different spectral regions. The smallest nanostructures obtained have a mean diameter of 20 nm when using HDT as capping agent. Also, we deposited the aforementioned nanostructures onto flat glass substrates by the spin coating technique as a first approach of an active layer of a solar cell. The depositions were characterized by atomic force microscopy. We obtained smaller particle deposition and higher particle density -but a lower area coverage (5%) - in samples with HDT as capping agent. This work presents promising results on nanostructures for future application on hybrid solar cells. Further efforts will be focused on the deposition of organic-inorganic layers.

  7. Mercury (Hg) burden in children: the impact of dental amalgam.

    Science.gov (United States)

    Al-Saleh, Iman; Al-Sedairi, Al Anoud

    2011-07-15

    The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine (μg/g creatinine) and micrograms per liter (μg/L). We found that children with amalgam fillings (N=106) had significantly higher UHg-C levels than children without (N=76), with means of 3.763 μg/g creatinine versus 3.457 μg/g creatinine, respectively (P=0.019). The results were similar for UHg (P=0.01). A similar pattern was also seen for HHg, with means of 0.614 μg/g (N=97) for children with amalgam versus 0.242 μg/g (N=74) for those without amalgam fillings (P=0). Although the mean NHg was higher in children without amalgam (0.222 μg/g, N=61) versus those with (0.163 μg/g, N=101), the relationship was not significant (P=0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (Pdental amalgam fillings (P=0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and/or nephrotoxic effects of such an increased Hg on children should be a cause of concern, and further investigation is warranted. Our

  8. Crystal Growth of Solid Solution HgCdTe Alloys

    Science.gov (United States)

    Lehoczky, Sandor L.

    1997-01-01

    The growth of homogenous crystals of HgCdTe alloys is complicated by the large separation between their liquidus and solidus temperatures. Hg(1-x)Cd(x)Te is representative of several alloys which have electrical and optical properties that can be compositionally tuned for a number of applications. Limitations imposed by gravity during growth and results from growth under reduced conditions are described. The importance of residual accelerations was demonstrated by dramatic differences in compositional distribution observed for different attitudes of the space shuttle that resulted in different steady acceleration components.

  9. Natural Hg isotopic composition of different Hg compounds in mammal tissues as a proxy for in vivo breakdown of toxic methylmercury.

    Science.gov (United States)

    Perrot, Vincent; Masbou, Jeremy; Pastukhov, Mikhail V; Epov, Vladimir N; Point, David; Bérail, Sylvain; Becker, Paul R; Sonke, Jeroen E; Amouroux, David

    2016-02-01

    In the last decade, specific attention has been paid to total mercury (HgT) stable isotopic composition, especially in natural samples such as aquatic organisms, due to its potential to track the cycle of this toxic element in the environment. Here, we investigated Hg Compound Specific stable Isotopic Composition (CSIC) of natural inorganic Hg (iHg) and methylmercury (MMHg) in various tissues of aquatic mammals (Beluga whale from the Arctic marine environment and seals from the freshwater lake Baikal, Russia). In seals' organs the variation in mass dependent fractionation (MDF, δ(202)Hg) for total Hg was significantly correlated to the respective fraction of iHg and MMHg compounds, with MMHg being enriched by ∼ 3‰ in heavier isotopes relative to iHg. On the other hand, we observe insignificant variation in Hg mass independent isotope fractionation (MIF, Δ(199)Hg) among iHg and MMHg in all organs for the same mammal species and MMHg in prey items. MIF signatures suggest that both MMHg and iHg in aquatic mammals have the same origin (i.e., MMHg from food), and are representative of Hg photochemistry in the water column of the mammal ecosystem. MDF signatures of Hg compounds indicate that MMHg is demethylated in vivo before being stored in the muscle, and the iHg formed is stored in the liver, and to a lesser extent in the kidney, before excretion. Thus, Hg CSIC analysis in mammals can be a powerful tool for tracing the metabolic response to Hg exposure.

  10. Mercury exposure associated with altered plasma thyroid hormones in the declining western pond turtle (Emys marmorata) from California mountain streams

    Science.gov (United States)

    Meyer, Erik; Eagles-Smith, Collin A.; Sparling, Donald; Blumenshine, Steve

    2014-01-01

    Mercury (Hg) is a global threat to wildlife health that can impair many physiological processes. Mercury has well-documented endocrine activity; however, little work on the effects of Hg on the thyroid hormones triiodothyronine (T3) and thyroxine (T4) in aquatic wildlife exists despite the fact that it is a sensitive endpoint of contaminant exposure. An emerging body of evidence points to the toxicological susceptibility of aquatic reptiles to Hg exposure. We examined the endocrine disrupting potential of Hg in the western pond turtle (Emys marmorata), a long-lived reptile that is in decline throughout California and the Pacific Northwest. We measured total Hg (THg) concentrations in red blood cells (RBCs) and plasma T3 and T4 of turtles from several locations in California that have been impacted by historic gold mining. Across all turtles from all sites, the geometric mean and standard error THg concentration was 0.805 ± 0.025 μg/g dry weight. Sampling region and mass were the strongest determinants of RBC THg. Relationships between RBC THg and T3 and T4 were consistent with Hg-induced disruption of T4 deiodination, a mechanism of toxicity that may cause excess T4 levels and depressed concentrations of biologically active T3.

  11. Genome-Wide Association Study to Identify Genes Related to Renal Mercury Concentrations in Mice

    DEFF Research Database (Denmark)

    Alkaissi, Hammoudi; Ekstrand, Jimmy; Jawad, Aksa

    2016-01-01

    BACKGROUND: Following human mercury (Hg) exposure, the metal accumulates with considerable concentrations in kidney, liver, and brain. Although the toxicokinetics of Hg has been studied extensively, factors responsible for inter-individual variation in humans are largely unknown. Differences...... in accumulation of renal Hg between inbred mouse strains suggest a genetic inter-strain variation regulating retention or/and excretion of Hg. A.SW, DBA/2 and BALB/C mouse strains accumulate higher amounts of Hg than B10.S. OBJECTIVES: To find candidate genes associated with regulation of renal Hg concentrations...... enhanced by the Pprc1 (Nrf1 and Nrf2) were included for gene expression analysis. RESULTS: Renal Hg concentrations differed significantly between A.SW and B10.S mice and between males and females within each strain. QTL analysis showed a peak logarithm of odds ratio score 5.78 on chromosome 19 (p = 0...

  12. Geochemical influences and mercury methylation of a dental wastewater microbiome.

    Science.gov (United States)

    Rani, Asha; Rockne, Karl J; Drummond, James; Al-Hinai, Muntasar; Ranjan, Ravi

    2015-08-14

    The microbiome of dental clinic wastewater and its impact on mercury methylation remains largely unknown. Waste generated during dental procedures enters the sewer system and contributes a significant fraction of the total mercury (tHg) and methyl mercury (MeHg) load to wastewater treatment facilities. Investigating the influence of geochemical factors and microbiome structure is a critical step linking the methylating microorganisms in dental wastewater (DWW) ecosystems. DWW samples from a dental clinic were collected over eight weeks and analyzed for geochemical parameters, tHg, MeHg and bacterio-toxic heavy metals. We employed bacterial fingerprinting and pyrosequencing for microbiome analysis. High concentrations of tHg, MeHg and heavy metals were detected in DWW. The microbiome was dominated by Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi and many unclassified bacteria. Significant correlations were found between the bacterial community, Hg levels and geochemical factors including pH and the predicted total amount (not fraction) of neutral Hg-sulfide species. The most prevalent known methylators included Desulfobulbus propionicus, Desulfovibrio desulfuricans, Desulfovibrio magneticus and Geobacter sulfurreducens. This study is the first to investigate the impact of high loads of Hg, MeHg and other heavy metals on the dental clinic wastewater microbiome, and illuminates the role of many known and unknown sulfate-reducing bacteria in Hg methylation.

  13. An analytical protocol for the determination of total mercury concentrations in solid peat samples

    DEFF Research Database (Denmark)

    Roos-Barraclough, F; Givelet, N; Martinez-Cortizas, A

    2002-01-01

    and Pseudevernia furfuracea) are particularly efficient Hg retainers. The disproportionally high Hg concentrations in these species can cause considerable variation in Hg concentrations within a peat slice. The variation of water content (1.6% throughout 17-cm core, 0.97% in a 10 x 10 cm slice), bulk density (40...... AMA 254, capable of determining mercury concentrations in solid samples. Finally, an analytical protocol for the determination of Hg concentrations in solid peat samples is proposed. This method allows correction for variation in factors such as vegetation type, bulk density, water content and Hg...... concentration in individual peat slices. Several subsamples from each peat slice are air dried, combined and measured for Hg using the AMA254, using a program of 30 s (drying), 125 s (decomposition) and 45 s (waiting). Bulk density and water content measurements are performed on every slice using separate...

  14. Variations in stable isotope fractionation of Hg in food webs of Arctic lakes.

    Science.gov (United States)

    Gantner, Nikolaus; Hintelmann, Holger; Zheng, Wang; Muir, Derek C

    2009-12-15

    Biotic and abiotic fractionation of mercury (Hg) isotopes has recently been shown to occur in aquatic environments. We determined isotope ratios (IRs) of Hg in food webs (zooplankton, chironomids, Arctic char) and sediments of 10 Arctic lakes from four regions and investigated the extent of Hg isotope fractionation. Hg IRs were analyzed by multicollector inductively coupled plasma mass spectrometry (MC-ICP/MS). Hg mass independent fractionation (MIF; Delta(199)Hg) and mass dependent fractionation (MDF; delta(202)Hg) were calculated and compared among samples. IRs of Hg in sediment were characterized mainly by MDF and low MIF (Delta(199)Hg -0.37 to 0.74 per thousand). However, all biota showed evidence of MIF, most pronounced in zooplankton (Delta(199)Hg up to 3.40 per thousand) and char (Delta(199)Hg up to 4.87 per thousand). Zooplankton takes up highly fractionated MeHg directly from the water column, while benthic organisms are exposed to sedimentary Hg, which contains less fractionated Hg. As evidenced by delta(13)C measurements, benthic chironomids make up a large proportion of char diet, explaining in part why MIF(char) meteor impact crater lake (Pingualuk) reflects a "pure" atmospheric Hg signature, which is modified only by aqueous in-lake processes. All other lakes are also affected by terrestrial Hg inputs and sediment processes.

  15. Synthesis of undoped and manganese-doped hgte nanoparticles using [Hg(TeCH2CH2NMe2)2] as a single source precursor.

    Science.gov (United States)

    Kedarnath, Gotluru; Dey, Sandip; Jain, Vimal K; Dey, Gautam K; Kadam, Ramakant M

    2008-09-01

    The Reaction of [HgCl2(tmeda)] with NaTeCH2CH2NMe2 gave a mercury tellurolate, [Hg(TeCH2CH2. NMe2)2] (1) as a yellow crystalline solid, which was characterized by elemental analysis, UV-vis, mass and NMR (1H, 13C, 125Te, 199Hg) spectroscopy. Thermolysis of 1 in hexadecylamine (HDA) at 90 degrees C in the absence and presence of Mn(OAc)2.4H2O gave undoped and Mn-doped HgTe nanoparticles which were characterized by XRD, EDAX, TEM, EPR and magnetic measurements. These particles could be synthesized with mean particle size of 6-7 nm (from TEM). Manganese substitution at Hg site in HgTe lead to a linear decrease in lattice parameter with increasing concentration of Mn. Magnetization measurements showed ferromagnetic ordering at room temperature with very small coercive field (Hc, 50 Oe) for Hg0.973 Mn0.027 Te sample. This sample also exhibited distinct ferromagnetic resonance (FMR) in the EPR spectrum.

  16. Spatial distribution of dissolved Pb,Hg,Cd,Cu and As in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Characteristics of the spatial distribution of selected dissolved heavy metals were analyzed during large scale surveys from August 12 to 25.2003 in the Bohai Sea.Dissolved Pb was the only element with average concentrations higher than the grade-one sea water quality standard of China.The spatial distribution of dissolved Pb in surface water was similar to those of Cd,Cu and As,where the isopleths generally indicated decreasing values from the bays to the central areas.Only for Hg did the high concentrations not only appear in Liaodong Bay,Bohai Bay and Laizhou Bay,but also in the Central Area,viz.not only in inshore but also in offshore areas.Vertical distributions of dissolved Pb,Cd,Cu and As were largely uniform,while that of dissolved Hg increased with depth.We infer that the input of pollutants from land was the main influencing factor for the detected distribution patterns of dissolved heavy metals,followed by the dynamics of sea water,release from bottom sediments and biochemical processes.Comparing with historical data,average concentrations of dissolved heavy metals appear to decline in recent years.

  17. Taguchi optimization approach for Pb(II) and Hg(II) removal from aqueous solutions using modified mesoporous carbon

    Energy Technology Data Exchange (ETDEWEB)

    Zolfaghari, Ghasem; Esmaili-Sari, Abbas [Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Mazandaran, P.O. Box: 46414-356 (Iran, Islamic Republic of); Anbia, Mansoor, E-mail: anbia@iust.ac.ir [Research Laboratory of Nanoporous Materials, Faculty of Chemistry, Iran University of Science and Technology, Farjam Street, Narmak, Tehran 16846 (Iran, Islamic Republic of); Younesi, Habibollah [Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Mazandaran, P.O. Box: 46414-356 (Iran, Islamic Republic of); Amirmahmoodi, Shahram [Research Laboratory of Nanoporous Materials, Faculty of Chemistry, Iran University of Science and Technology, Farjam Street, Narmak, Tehran 16846 (Iran, Islamic Republic of); Ghafari-Nazari, Ali [Loabiran Company, Research and Development Group, Shiraz (Iran, Islamic Republic of)

    2011-09-15

    Graphical abstract: The effect of agitation time (min) (A), initial concentration (mg/l) (B), dose of adsorbent (g/l) (C), temperature ({sup o}C) (D), and pH of solution (E), on the S/N ratio in the removal of lead (II) (left) and mercury (II) (right) by zinc oxide-modified mesoporous carbon CMK-3. Circles on figures indicate optimum conditions for adsorption process. Highlights: {yields} Using the Taguchi method, the removal of Pb(II) and Hg(II) by zinc oxide-modified CMK-3(Zn-OCMK-3) was optimized. {yields} The CMK-3 had high surface area which can accommodate ZnO in a spreading manner. {yields} The results suggest that Zn-OCMK-3 can be effectively used for remediation of Pb (97.25%) and Hg (99%). {yields} Removal of Pb(II) and Hg(II) were highly concentration dependent. - Abstract: Using the Taguchi method, this study presents a systematic optimization approach for removal of lead (Pb) and mercury (Hg) by a nanostructure, zinc oxide-modified mesoporous carbon CMK-3 denoted as Zn-OCMK-3. CMK-3 was synthesized by using SBA-15 and then oxidized by nitric acid. The zinc oxide was loaded to the modified CMK-3 by the equilibrium adsorption of Zn(II) ions from aqueous solution followed by calcination to convert zinc nitrate to zinc oxide. The CMK-3 had porous structure and high specific surface area which can accommodate zinc oxide in a spreading manner, the zinc oxide connects to the carbon surface via oxygen atoms. The controllable factors such as agitation time, initial concentration, temperature, dose and pH of solution have been optimized. Under optimum conditions, the pollutant removal efficiency (PRE) was 97.25% for Pb(II) and 99% for Hg(II). The percentage contribution of each controllable factor was also determined. The initial concentration of pollutant is the most influential factor, and its value of percentage contribution is up to 31% and 43% for Pb and Hg, respectively. Our results show that the Zn-OCMK-3 is an effective nanoadsorbent for lead and mercury

  18. Selective separation of Hg(II) and Cd(II) from aqueous solutions by complexation-ultrafiltration process.

    Science.gov (United States)

    Zeng, Jian Xian; Ye, Hong Qi; Huang, Nian Dong; Liu, Jun Feng; Zheng, Li Feng

    2009-07-01

    Complexation-ultrafiltration process was investigated to separate selectively Hg(II) and Cd(II) from binary metal solutions by using poly (acrylic acid) sodium salt as a complexing agent. Effects of operating parameters on selective separation factors (beta(Cd/Hg)) of the both metals have been examined in detail. Results indicated that loading rate, pH, concentration of salt added and low-molecular competitive complexing agent affect significantly beta(Cd/Hg) value. Further, a concentration experiment was carried out according to the previous optimum parameters. Rejection coefficient of mercury is close to 1, while that of cadmium is about 0.1. The experiment was characterized by good effectiveness, and enabled the rapid linear increase of mercury concentration and very slow increase of cadmium concentration in the retentate. Then, a diafiltration technique was applied to separate further the both metals. Cadmium concentration in the retentate declines sharply with the diafiltration volume, whereas for mercury it is the contrary.

  19. Prediction of fish and sediment mercury in streams using landscape variables and historical mining

    Science.gov (United States)

    Alpers, Charles N.; Yee, Julie L.; Ackerman, Josh; Orlando, James; Slotton, Darrell G.; Marvin-DiPasquale, Mark C.

    2016-01-01

    Widespread mercury (Hg) contamination of aquatic systems in the Sierra Nevada of California, U.S., is associated with historical use to enhance gold (Au) recovery by amalgamation. In areas affected by historical Au mining operations, including the western slope of the Sierra Nevada and downstream areas in northern California, such as San Francisco Bay and the Sacramento River–San Joaquin River Delta, microbial conversion of Hg to methylmercury (MeHg) leads to bioaccumulation of MeHg in food webs, and increased risks to humans and wildlife. This study focused on developing a predictive model for THg in stream fish tissue based on geospatial data, including land use/land cover data, and the distribution of legacy Au mines. Data on total mercury (THg) and MeHg concentrations in fish tissue and streambed sediment collected during 1980–2012 from stream sites in the Sierra Nevada, California were combined with geospatial data to estimate fish THg concentrations across the landscape. THg concentrations of five fish species (Brown Trout, Rainbow Trout, Sacramento Pikeminnow, Sacramento Sucker, and Smallmouth Bass) within stream sections were predicted using multi-model inference based on Akaike Information Criteria, using geospatial data for mining history and landscape characteristics as well as fish species and length (r2 = 0.61, p size resulted in an improved fit (r2 = 0.63, p < 0.001). These models can be used to estimate THg concentrations in stream fish based on landscape variables in the Sierra Nevada in areas where direct measurements of THg concentration in fish are unavailable.

  20. Multiyear total and methyl mercury exports from two major sub-Arctic rivers draining into Hudson Bay, Canada.

    Science.gov (United States)

    Kirk, Jane L; St Louis, Vincent L

    2009-04-01

    From 2003 to 2007, concentrations of total mercury and methylmercury (THg and MeHg) were continuously measured in two Canadian sub-Arctic rivers (the Nelson and the Churchill) that drain into western Hudson Bay. THg and MeHg concentrations were low in the Nelson River (mean i standard deviation, 0.88 +/- 0.33 and 0.05 +/- 0.03 ng L(-1), respectively). The Churchill River, however, had high concentrations of Hg, particularly MeHg (1.96 +/- 0.8 and 0.18 +/- 0.09 ng L(-1), respectively) and hence may be an important source of MeHg to organisms feeding in the Churchill River estuary. A large portion of THg in the Nelson River was particulate-bound (39 +/- 23%), while in the Churchill River, most was in the dissolved form (78 +/- 15%) and is likely dissolved organic carbon (DC)-bound Hg originating in the surrounding wetlands. In fact, both the Nelson and Churchill Rivers had high DOC concentrations and were therefore large exporters of DOC to Hudson Bay (1480 +/- 723 and 392 +/- 309 x 10(3) t year(-1), respectively) compared to rivers to the south and east Despite high Churchill River Hg concentrations, due to large Nelson River flows, average THg and MeHg exports to Hudson Bay from the Churchill River (37 +/- 28 and 4 +/- 4 kg year(-1), respectively) were about one-third and half the Nelson River exports (113 +/- 52 and 9 +/- 4 kg year(-1)). Interestingly, combined Hg exports to Hudson Bay from Nelson and Churchill River discharge are comparable to THg inputs from Hudson Bay springtime snowmelt (177 +/-140 kg year(-1)) but are approximately 13 times greater than MeHg snowmelt inputs (1 +/- 1 kg year(-1)). Although Hg inputs from rivers and snowmelt together may account for a large portion of the THg pool in Hudson Bay, these inputs account for a lesser portion of the MeHg pool, thus highlighting the importance of water column Hg(ll) methylation as a source of MeHg to Hudson Bay marine food webs.

  1. Multi Year Total and Methyl Mercury Exports from Two Major Sub Arctic Rivers Draining into Hudson Bay, Canada

    Science.gov (United States)

    Kirk, J. L.; St. Louis, V. L.

    2009-05-01

    From 2003 to 2007, concentrations of total and methyl mercury (THg and MeHg), were continuously measured in two Canadian sub Arctic rivers (the Nelson and the Churchill) that drain into western Hudson Bay. THg and MeHg concentrations were low in the Nelson River (mean ± standard deviation; 0.88±0.33 and 0.05±0.03 ng/L, respectively). The Churchill River, however, had high concentrations of Hg, particularly MeHg (1.96±0.8 and 0.18±0.09 ng/L, respectively), and hence may be an important source of MeHg to organisms feeding in the Churchill River estuary. A large portion of THg in the Nelson River was particulate- bound (39±23%), while in the Churchill River, most was in the dissolved form (78±15%) and is likely DOC-bound Hg originating in surrounding wetlands. In fact, both the Nelson and Churchill Rivers had high DOC concentrations and were therefore large exporters of DOC to Hudson Bay (1480±723 and 392±309 x 103 tonnes/year, respectively) compared to rivers to the south and east. Despite high Churchill River Hg concentrations, due to large Nelson River flows, average THg and MeHg exports to Hudson Bay from the Churchill River (37±28 and 4±4 kg/year, respectively) were ˜ one third and half Nelson River exports (113±52 and 9±4 kg/year). Interestingly, combined Hg exports to Hudson Bay from Nelson and Churchill River discharge are comparable to THg inputs from Hudson Bay spring-time snowmelt (177±140 kg/year) but are approximately 13 times greater than MeHg snowmelt inputs (1±1 kg/year). Although Hg inputs from rivers and snowmelt together may account for a large portion of the THg pool in Hudson Bay, these inputs account for a lesser portion of the MeHg pool, thus highlighting the importance of water column Hg(II) methylation as a large source of MeHg to Hudson Bay marine foodwebs.

  2. Effects of small hydropower plants on mercury concentrations in fish.

    Science.gov (United States)

    Cebalho, Elaine C; Díez, Sergi; Dos Santos Filho, Manoel; Muniz, Claumir Cesar; Lázaro, Wilkinson; Malm, Olaf; Ignácio, Aurea R A

    2017-08-16

    Although the impacts of large dams on freshwater biota are relatively well known, the effects of small hydropower plants (SHP) are not well investigated. In this work, we studied if mercury (Hg) concentrations in fish rise in two tropical SHP reservoirs, and whether similar effects take place during impoundment. Total Hg concentrations in several fish species were determined at two SHP in the Upper Guaporé River basin floodplain, Brazil. In total, 185 specimens were analysed for Hg content in dorsal muscle and none of them reported levels above the safety limit (500 μg kg(-1)) for fish consumption recommended by the World Health Organisation (WHO). The highest levels of Hg (231 and 447 μg kg(-1)) were found in carnivorous species in both reservoirs. Mercury increased as a function of standard length in most of the fish populations in the reservoirs, and higher Hg concentrations were found in fish at the reservoir compared with fish downstream. The high dissolved oxygen concentrations and high transparency of the water column (i.e. oligotrophic reservoir) together with the absence of thermal stratification may explain low Hg methylation and low MeHg levels found in fish after flooding. Overall, according to limnological characteristics of water, we may hypothesise that reservoir conditions are not favourable to high net Hg methylation.

  3. 46 CFR 53.01-5 - Scope (modifies HG-100).

    Science.gov (United States)

    2010-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING HEATING BOILERS General Requirements § 53.01-5 Scope (modifies HG-100). (a) The regulations in this part apply to steam heating boilers, hot water boilers (which include hot water heating boilers and hot water supply...

  4. Decay from the superdeformed bands in {sup 194}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Henry, R.G.; Khoo, T.L.; Carpenter, M.P. [and others

    1995-08-01

    Superdeformed bands in {sup 194}H g were studied using the early implementation of Gammasphere. The response functions for the Ge detectors were measured for the first time as part of this experiment. Experiments were performed with both a backed target (where the residue stopped in the Au backing) and a thin target (where the residue recoiled into vacuum). This will permit measurements of the decay times of the quasicontinuum {gamma}rays. The spectrum in coincidence with the yrast SD band in {sup 194}Hg reveals the same features as found in the quasicontinuum structure in {sup 192}Hg. These features include: statistical {gamma}rays feeding the SD band, a pronounced E2 peak from transitions feeding the SD band, a Ml/E2 bump at low energies that is associated with the last stages of feeding of the superdeformed band, and a quasicontinuous distribution from {gamma}rays linking SD and normal states, including a sizable clustering of strength around 1.7 MeV. The remarkable similarity of the spectra coincident with SD bands in {sup 192,194}Hg provides additional support for a statistical process for decay out of the SD states. This similarity contrasts with differences observed in the spectrum coincident with the SD band in the odd-even {sup 191}Hg, confirming the predictions about the role of pairing (in normal states) in influencing the shape of the decay-out spectrum.

  5. Emission and gain studies of the Tl-Hg excimer

    Energy Technology Data Exchange (ETDEWEB)

    Chilukuri, S.; Nayfeh, M.H.

    1978-11-01

    The pressure and temperature dependence of the Tl-Hg excimer emission in the visible from an rf excited discharge has been studied. The gain of the system in the blue band at 4585 A is probed with an Ar-ion laser. With gain sensitivity limited to 1/2% due to beam steering and defocusing effects, the system has no gain.

  6. Hypotension is 100 mm Hg on the Battlefield

    Science.gov (United States)

    2011-10-01

    corroborate the predictive value of admission metabolic acidosis on patient survival. We also were able to show that an SBP of 110 mm Hg after injury was... metabolic acidosis , complications, length of stay, intensive care unit days, and ventilator days all increased. The implication of our result suggested

  7. Experimental study of 199Hg spin anti-relaxation coatings

    CERN Document Server

    Chowdhuri, Z; Horras, M; Kirch, K; Krempel, J; Lauss, B; Mtchedlishvili, A; Rebreyend, D; Roccia, S; Schmidt-Wellenburg, P; Zsigmond, G

    2013-01-01

    We report on a comparison of spin relaxation rates in a $^{199}$Hg magnetometer using different wall coatings. A compact mercury magnetometer was built for this purpose. Glass cells coated with fluorinated materials show longer spin coherence times than if coated with their hydrogenated homologues. The longest spin relaxation time of the mercury vapor was measured with a fluorinated paraffin wall coating.

  8. Ion Beam Nanostructuring of HgCdTe Ternary Compound

    Science.gov (United States)

    Smirnov, Aleksey B.; Savkina, Rada K.; Udovytska, Ruslana S.; Gudymenko, Oleksandr I.; Kladko, Vasyl P.; Korchovyi, Andrii A.

    2017-05-01

    Systematic study of mercury cadmium telluride thin films subjected to the ion beam bombardment was carried out. The evolution of surface morphology of (111) Hg1 - x Cd x Te ( x 0.223) epilayers due to 100 keV B+ and Ag+ ion irradiation was studied by AFM and SEM methods. X-ray photoelectron spectroscopy and X-ray diffraction methods were used for the investigation of the chemical compound and structural properties of the surface and subsurface region. It was found that in the range of nanoscale, arrays of holes and mounds on Hg0.777Cd0.223Te (111) surface as well as the polycrystalline Hg1 - x Cd x Te cubic phase with alternative compound ( x 0.20) have been fabricated using 100 keV ion beam irradiation of the basic material. Charge transport investigation with non-stationary impedance spectroscopy method has shown that boron-implanted structures are characterized by capacity-type impedance whereas for silver-implanted structures, an inductive-type impedance (or "negative capacitance") is observed. A hybrid system, which integrates the nanostructured ternary compound (HgCdTe) with metal-oxide (Ag2O) inclusions, was fabricated by Ag+ ion bombardment. The sensitivity of such metal-oxide-semiconductor hybrid structure for sub-THz radiation was detected with NEP 4.5 × 10-8 W/Hz1/2at ν ≈ 140 GHz and 296 K without amplification.

  9. Thermodynamics limits the reactivity of BrHg radical with volatile organic compounds

    Science.gov (United States)

    Dibble, Theodore S.; Schwid, Abraham C.

    2016-08-01

    Mercury emissions to the atmosphere primarily consist of Hg(0), which tends not to enter ecosystems until it is oxidized. Atomic bromine initiates oxidation of Hg(0) via the BrHg intermediate, but the further reactions of BrHg are just beginning to be explored. Here we use quantum chemistry to determine that hydrogen abstraction from hydrocarbons by BrHg is so endothermic as to be irrelevant. Bonds between BrHg and carbon atoms are so weak that BrHg addition to carbon-carbon double bonds atoms will be somewhat ineffective in leading to further reactions.

  10. Isotopic Composition of Gaseous Elemental Mercury (Hg0) at Various Sites in Japan

    Science.gov (United States)

    Yamakawa, A.; Moriya, K.; Yoshinaga, J.

    2015-12-01

    Mercury (Hg) is a toxic heavy metal, which exists in various chemical forms in the environmental system. In the atmosphere, Hg exists in three forms (Hg0(g), Hg+2(g), and Hg(p)). Hg0(g) is the dominant species of atmospheric Hg, accounting for >95% of the total Hg in the atmosphere. Because Hg0(g) is highly volatile and has limited solubility in water, it cannot be easily removed by wet or dry deposition processes. Therefore, the residence time of Hg0(g) in the atmosphere is relatively long (1 to 2 years), allowing long-range transport from mercury emission source(s). Conversely, Hg+2(g) and Hg(p) are effectively removed from the atmosphere through wet and dry depositions. The determination of mercury source attribution using quantitative data is challenging because Hg0(g) may be deposited on an area upon oxidation to Hg+2(g) and associated with aerosols and particulates to form Hg(p) while the global cycling of Hg0(g). Over the last decade, the development of analytical methods of highly precise Hg isotopic measurements demonstrated mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) of Hg isotopes in environmental samples. For instance, MDF of Hg isotopes is thought to occur during various natural and industrial Hg transformations. MIF of Hg isotopes is observed during abiotic reduction, photochemical and non-photochemical, and physical and chemical processes. Such processes lead to differences in the Hg isotopic composition of different emission sources, both natural and anthropogenic, and atmospheric processes (i.e., transportation, oxidation/reduction, deposition, and reemission). Therefore, Hg isotopic compositions could be used to trace the sources and processes of atmospheric Hg. For securing the reliability and accuracy of atmospheric Hg isotope data, the methods of collection, pretreatment, and isotopic measurement for Hg0(g) were developed to obtain high recovery yield of samples with no Hg isotopic fractionation during each

  11. Demonstrating the Model Nature of the High-Temperature Superconductor HgBa2CuO4+d

    Energy Technology Data Exchange (ETDEWEB)

    Barisic, Neven; Li, Yuan; Zhao, Xudong; Cho, Yong-Chan; Chabot-Couture, Guillaume; Yu, Guichuan; Greven, Martin; /SLAC, SSRL /Boskovic Inst., Zagreb /Stanford U., Phys. Dept. /Jilin U. /Stanford U., Appl. Phys. Dept.

    2008-09-30

    The compound HgBa{sub 2}CuO{sub 4+{delta}} (Hg1201) exhibits a simple tetragonal crystal structure and the highest superconducting transition temperature (T{sub c}) among all single Cu-O layer cuprates, with T{sub c} = 97 K (onset) at optimal doping. Due to a lack of sizable single crystals, experimental work on this very attractive system has been significantly limited. Thanks to a recent breakthrough in crystal growth, such crystals have now become available. Here, we demonstrate that it is possible to identify suitable heat treatment conditions to systematically and uniformly tune the hole concentration of Hg1201 crystals over a wide range, from very underdoped (T{sub c} = 47 K, hole concentration p {approx} 0.08) to overdoped (T{sub c} = 64 K, p {approx} 0.22). We then present quantitative magnetic susceptibility and DC charge transport results that reveal the very high-quality nature of the studied crystals. Using XPS on cleaved samples, we furthermore demonstrate that it is possible to obtain large surfaces of good quality. These characterization measurements demonstrate that Hg1201 should be viewed as a model high-temperature superconductor, and they provide the foundation for extensive future experimental work.

  12. Taguchi optimization approach for Pb(II) and Hg(II) removal from aqueous solutions using modified mesoporous carbon.

    Science.gov (United States)

    Zolfaghari, Ghasem; Esmaili-Sari, Abbas; Anbia, Mansoor; Younesi, Habibollah; Amirmahmoodi, Shahram; Ghafari-Nazari, Ali

    2011-09-15

    Using the Taguchi method, this study presents a systematic optimization approach for removal of lead (Pb) and mercury (Hg) by a nanostructure, zinc oxide-modified mesoporous carbon CMK-3 denoted as Zn-OCMK-3. CMK-3 was synthesized by using SBA-15 and then oxidized by nitric acid. The zinc oxide was loaded to the modified CMK-3 by the equilibrium adsorption of Zn(II) ions from aqueous solution followed by calcination to convert zinc nitrate to zinc oxide. The CMK-3 had porous structure and high specific surface area which can accommodate zinc oxide in a spreading manner, the zinc oxide connects to the carbon surface via oxygen atoms. The controllable factors such as agitation time, initial concentration, temperature, dose and pH of solution have been optimized. Under optimum conditions, the pollutant removal efficiency (PRE) was 97.25% for Pb(II) and 99% for Hg(II). The percentage contribution of each controllable factor was also determined. The initial concentration of pollutant is the most influential factor, and its value of percentage contribution is up to 31% and 43% for Pb and Hg, respectively. Our results show that the Zn-OCMK-3 is an effective nanoadsorbent for lead and mercury pollution remediation. Langmuir and Freundlich adsorption isotherms were used to model the equilibrium adsorption data for Pb(II) and Hg(II).

  13. Molecular beam epitaxy of CdTe and HgCdTe on large-area Si(100)

    Science.gov (United States)

    Sporken, R.; Lange, M. D.; Faurie, Jean-Pierre

    1991-09-01

    The current status of molecular beam epitaxy (MBE) of CdTe and HgCdTe on Si(100) is reviewed. C