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Sample records for hg accumulation showing

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  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. 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.

  7. 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.

  8. 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.

  9. The accumulation of heavy metals (Cd, Pb, Hg, Cr) and their state in ...

    African Journals Online (AJOL)

    ONOS

    2010-01-25

    Jan 25, 2010 ... metals (Cd, Pb, Hg and Cr) in the water and plankton of Beysehir and ... In addition, heavy metals show harmful effects ... in laboratory for a period of time for evaporation of water. ...... biochemical effects in an estuarine teleost.

  10. Translocation and accumulation of Cr, Hg, As, Pb, Cu and Ni by Amaranthus dubius (Amaranthaceae) from contaminated sites.

    Science.gov (United States)

    Mellem, John J; Baijnath, Himansu; Odhav, Bharti

    2009-05-01

    Phytoremediation is an emerging technology where specially selected and engineered metal-accumulating plants are used for bioremediation. This study was undertaken to evaluate the potential of Amaranthus dubius for phytoremediation of chromium (Cr), mercury (Hg), arsenic (As), lead (Pb), copper (Cu) and nickel (Ni). Locally gathered soil and plants of A. dubius were investigated for the metals from a regularly cultivated area, a landfill site and a waste water treatment site. Metals were extracted from the samples using microwave-digestion and analyzed using Inductively Coupled Plasma-Mass Spectroscopy. The mode of phytoremediation, effect of the metals on the plants, ability of the plant to extract metals from soil (Bioconcentration Factor) and the ability of the plants to move the metals to the aerial parts of the plants (Translocation Factor) were evaluated. The survey of the three sites showed that soils were heavily contaminated with Cr, Hg, Cu and Ni. These levels were far above acceptable standards set for soils and above the standards set for the Recommended Dietary Allowance. Specimens of A. dubius from the three sites showed that they could tolerate Hg, sequester it from the soil, and translocate it to the shoots. Cr could only be removed from the soil and stored in the roots, with limited amounts translocated to the aerial parts. Pb, As, Ni, and Cu have some degree of transportability from the soil to the roots but not to aerial parts. The ability of A. dubius to be considered for phytoremediation has to be viewed with caution because translocation of the metals to the aerial parts of the plant is limited.

  11. 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.

  12. In situ bioavailability of DDT and Hg in sediments of the Toce River (Lake Maggiore basin, Northern Italy): accumulation in benthic invertebrates and passive samplers.

    Science.gov (United States)

    Pisanello, Francesca; Marziali, Laura; Rosignoli, Federica; Poma, Giulia; Roscioli, Claudio; Pozzoni, Fiorenzo; Guzzella, Licia

    2016-06-01

    DDT and mercury (Hg) contamination in the Toce River (Northern Italy) was caused by a factory producing technical DDT and using a mercury-cell chlor-alkali plant. In this study, DDT and Hg contamination and bioavailability were assessed by using different approaches: (1) direct evaluation of sediment contamination, (2) assessment of bioaccumulation in native benthic invertebrates belonging to different taxonomic/functional groups, and (3) evaluation of the in situ bioavailability of DDT and Hg using passive samplers. Sampling sites were selected upstream and downstream the industrial plant along the river axis. Benthic invertebrates (Gammaridae, Heptageniidae, and Diptera) and sediments were collected in three seasons and analyzed for DDT and Hg content and the results were used to calculate the biota sediment accumulation factor (BSAF). Polyethylene passive samplers (PEs) for DDT and diffusive gradients in thin films (DGTs) for Hg were deployed in sediments to estimate the concentration of the toxicants in pore water. Analysis for (DDx) were performed using GC-MS. Accuracy was within ±30 % of the certified values and precision was >20 % relative standard deviation (RSD). Total mercury concentrations were determined using an automated Hg mercury analyzer. Precision was >5 % and accuracy was within ±10 % of certified values. The results of all the approaches (analysis of sediment, biota, and passive samplers) showed an increasing contamination from upstream to downstream sites. BSAF values revealed the bioavailability of both contaminants in the study sites, with values up to 49 for DDx and up to 3.1 for Hg. No correlation was found between values in sediments and the organisms. Concentrations calculated using passive samplers were correlated with values in benthic invertebrates, while no correlation was found with concentrations in sediments. Thus, direct analysis of toxicant in sediments does not provide a measurement of bioavailability. On the contrary

  13. Mercury in Pleurozium schreberi and Polytrichum commune from areas with various levels of Hg pollution--an accumulation and desorption experiment with microscopic observations.

    Science.gov (United States)

    Zawadzki, Krzysztof; Sokołowska, Katarzyna; Samecka-Cymerman, Aleksandra; Kolon, Krzysztof; Dubińska, Anna; Kempers, Alexander J

    2014-10-01

    Because of its high mobility in ecosystems, mercury is one of the main toxic threats to the environment, and its concentration must be carefully controlled. To fulfill this need, we selected terrestrial mosses with different characteristic life forms: orthotropic and endohydric Polytrichum commune and plagiotropic and ectohydric Pleurozium schreberi. The concentrations of mercury were determined in both species growing together at sites situated approximately 0.75, 1.5, 3 and 6km to the north, south, east and west, respectively of five known mercury polluters. The mercury concentrations reflected the emissions produced by the surrounding industry, reaching values of 0.44mgkg(-1) in P. schreberi and 0.79mgkg(-1) in P. commune in the vicinity of the chlor-alkali industry. To determine how long a load of Hg would remain in the mosses after mercury emitters restricted releases of Hg to the atmosphere, accumulation and desorption experiments were performed. We compared the two moss species collected from clean and moderately and heavily mercury-polluted sites. After eight days of exposure to mercury, P. schreberi accumulated up to 25mgkg(-1) of Hg, and P. commune accumulated up to 31mgkg(-1). Both in the field and in the experiment, P. commune accumulated significantly higher concentrations of Hg than did P. schreberi, most likely because of its surface morphology, which is likely to enhance the capture of metal from the atmosphere. After sixteen days of exposure, mercury changed the structure of the plasma membrane and affected organelles such as the nuclei and chloroplasts, leading to cell disintegration and death. The negative effects of mercury on the functioning of living cells appeared first in the older leaves of P. schreberi. After 64 days growing in the absence of Hg, P. schreberi clearly retained only 10-14% of the initially accumulated Hg, while P. commune retained 10-21%. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Tumor-targeted HPMA copolymer-(RGDfK)-(CHX-A''-DTPA) conjugates show increased kidney accumulation.

    Science.gov (United States)

    Borgman, Mark P; Coleman, Tomika; Kolhatkar, Rohit B; Geyser-Stoops, Sandra; Line, Bruce R; Ghandehari, Hamidreza

    2008-12-18

    N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-RGDfK conjugates targeting the alpha(v)beta(3) integrin have shown increased accumulation in solid tumors and promise for selective delivery of radiotherapeutics to sites of angiogenesis- or tumor-expressed alpha(v)beta(3) integrin. An unresolved issue in targeting radiotherapeutics to solid tumors is toxicity to non-target organs. To reduce toxicity of radiolabeled conjugates, we have synthesized HPMA copolymer-RGDfK conjugates with varying molecular weight and charge content to help identify a polymeric structure that maximizes tumor accumulation while rapidly clearing from non-targeted organs. Endothelial cell binding studies showed that copolymer conjugates of approximately 43, 20 and 10 kD actively bind to the alpha(v)beta(3) integrin. Scintigraphic images showed rapid clearance of indium-111 ((111)In) radiolabeled conjugates from the blood pool and high kidney accumulation within 1 h in tumor bearing mice. Biodistribution data confirms images with high accumulation in kidney (max 210% ID/g for 43 kD conjugate) and lower tumor accumulation (max 1.8% ID/g for 43 kD conjugate). While actively binding to the alpha(v)beta(3) integrin in vitro, HPMA copolymer-RGDfK conjugates with increased negative charge through increased CHX-A''-DTPA chelator content in the side chains causes increased kidney accumulation with a loss of tumor accumulation in vivo.

  15. Tumor-Targeted HPMA Copolymer-(RGDfK)-(CHX-A″-DTPA) Conjugates Show Increased Kidney Accumulation

    Science.gov (United States)

    Borgman, Mark P.; Coleman, Tomika; Kolhatkar, Rohit B.; Geyser-Stoops, Sandra; Line, Bruce R.; Ghandehari, Hamidreza

    2008-01-01

    N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-RGDfK conjugates targeting the αvβ3 integrin have shown increased accumulation in solid tumors and promise for selective delivery of radiotherapeutics to sites of angiogenesis- or tumor-expressed αvβ3 integrin. An unresolved issue in targeting radiotherapeutics to solid tumors is toxicity to non-target organs. To reduce toxicity of radiolabeled conjugates, we have synthesized HPMA copolymer-RGDfK conjugates with varying molecular weight and charge content to help identify a polymeric structure that maximizes tumor accumulation while rapidly clearing from non-targeted organs. Endothelial cell binding studies showed that copolymer conjugates of approximately 43, 20 and 10 kD actively bind to the αvβ3 integrin. Scintigraphic images showed rapid clearance of indium-111 radiolabeled conjugates from the blood pool and high kidney accumulation within 1 h in tumor bearing mice. Biodistribution data confirms images with high accumulation in kidney (max 210% ID/g for 43 kD conjugate) and lower tumor accumulation (max 1.8% ID/g for 43kD conjugate). While actively binding to the αvβ3 integrin in vitro, HPMA copolymer-RGDfK conjugates with increased negative charge through increased CHX-A″-DTPA chelator content in the side chains causes increased kidney accumulation with a loss of tumor binding in vivo. PMID:18687371

  16. Field controlled experiments of mercury accumulation in crops from air and soil

    Energy Technology Data Exchange (ETDEWEB)

    Niu Zhenchuan [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Zhang Xiaoshan, E-mail: zhangxsh@rcees.ac.cn [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Wang Zhangwei, E-mail: wangzhw@rcees.ac.cn [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Ci Zhijia [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)

    2011-10-15

    Field open top chambers (OTCs) and soil mercury (Hg) enriched experiments were employed to study the influence of Hg concentrations in air and soil on the Hg accumulation in the organs of maize (Zea mays L.) and wheat (Triticum aestivum L.). Results showed that Hg concentrations in foliages were correlated significantly (p < 0.05) with air Hg concentrations but insignificantly correlated with soil Hg concentrations, indicating that Hg in crop foliages was mainly from air. Hg concentrations in roots were generally correlated with soil Hg concentrations (p < 0.05) but insignificantly correlated with air Hg concentrations, indicating that Hg in crop roots was mainly from soil. No significant correlations were found between Hg concentrations in stems and those in air and soil. However, Hg concentrations in upper stems were usually higher than those in bottom stems, implying air Hg might have stronger influence than soil Hg on stem Hg accumulation. - Highlights: > Hg accumulation in crop organs was studied by OTCs and soil Hg enriched experiments. > Hg accumulation in foliages and roots was mainly from air and soil, respectively. > Air Hg had stronger influence than soil Hg on stem Hg accumulation. > Foliar Hg concentrations showed the trend of increase over growth stages. - Capsule Mercury accumulated in the aboveground organs of crop was mainly from the air.

  17. Energy release, beam attenuation radiation damage, gas production and accumulation of long-lived activity in Pb, Pb-Bi and Hg targets

    Energy Technology Data Exchange (ETDEWEB)

    Shubin, Yu.N. [IPPE, Obninsk (Russian Federation)

    1996-06-01

    The calculation and analysis of the nuclei concentrations and long-lived residual radioactivity accumulated in Pb, Pb-Bi and Hg targets irradiated by 800 MeV, 30 mA proton beam have been performed. The dominating components to the total radioactivity of radionuclides resulting from fission and spallation reactions and radiative capture by both target nuclei and accumulated radioactive nuclei for various irradiation and cooling times were analyzed. The estimations of spectral component contributions of neutron and proton fluxes to the accumulated activity were carried out. The contributions of fission products to the targets activity and partial activities of main long-lived fission products to the targets activity and partial activities of main long-lived fission products were evaluated. The accumulation of Po isotopes due to reactions induced by secondary alpha-particles were found to be important for the Pb target as compared with two-step radiative capture. The production of Tritium in the targets and its contribution to the total targets activity was considered in detail. It is found that total activities of both targets are close to one another.

  18. Chronic Rhinosinusitis Patients Show Accumulation of Genetic Variants in PARS2.

    Directory of Open Access Journals (Sweden)

    Viktor Henmyr

    Full Text Available Genetic studies of chronic rhinosinusitis (CRS have identified a total of 53 CRS-associated SNPs that were subsequently evaluated for their reproducibility in a recent study. The rs2873551 SNP in linkage disequilibrium with PARS2 showed the strongest association signal. The present study aims to comprehensively screen for rare variants in PARS2 and evaluate for accumulation of such variants in CRS-patients. Sanger sequencing and long-range PCR were used to screen for rare variants in the putative promoter region and coding sequence of 310 CRS-patients and a total of 21 variants were detected. The mutation spectrum was then compared with data from European populations of the 1000Genomes project (EUR and the Exome Aggregation Consortium (ExAC. The CRS population showed a significant surplus of low-frequency variants compared with ExAC data. Haplotype analysis of the region showed a significant excess of rare haplotypes in the CRS population compared to the EUR population. Two missense mutations were also genotyped in the 310 CRS patients and 372 CRS-negative controls, but no associations with the disease were found. This is the first re-sequencing study in CRS research and also the first study to show an association of rare variants with the disease.

  19. A new mtDNA mutation showing accumulation with time and restriction to skeletal muscle

    Energy Technology Data Exchange (ETDEWEB)

    Weber, K.; Wilson, J.N.; Taylor, L. [Middlesbrough General Hospital (United Kingdom)] [and others

    1997-02-01

    We have identified a new mutation in mtDNA, involving tRNA{sup Leu(CUN)} in a patient manifesting an isolated skeletal myopathy. This heteroplasmic A{r_arrow}G transition at position 12320 affects the T{Psi}C loop at a conserved site and was not found in 120 controls. Analysis of cultured fibroblasts, white blood cells/platelets, and skeletal muscle showed that only skeletal muscle contained the mutation and that only this tissue demonstrated a biochemical defect of respiratory-chain activity. In a series of four muscle-biopsy specimens taken over a 12-year period, there was a gradual increase, from 70% to 90%, in the overall level of mutation, as well as a marked clinical deterioration. Single-fiber PCR confirmed that the proportion of mutant mtDNA was highest in cytochrome c oxidase-negative fibers. This study, which reports a mutation involving tRNA{sup Leu(CUN)}, demonstrates clearly that mtDNA point mutations can accumulate over time and may be restricted in their tissue distribution. Furthermore, clinical deterioration seemed to follow the increase in the level of mutation, although, interestingly, the appearance of fibers deficient in respiratory-chain activity showed a lag period. 32 refs., 4 figs., 1 tab.

  20. A rare 3D chloro-laced Mn(II) metal-organic framework to show sensitive probing effect to Hg2+

    Science.gov (United States)

    Ming, Mei; Bai, Na

    2017-10-01

    Two 3D Mn(II) metal-organic frameworks (MOFs), [Mn(L-Cl)(DMA)](H2O) (1) and Mn(L-CH3)(DMA) (2) (H2L-Cl = 2,2'-dichloro-4,4'-azodibenzoic acid, H2L-CH3 = 2,2'-dimethyl-4,4'-azodibenzoic acid) were synthesized under similar solvothermal condition. Both MOFs crystallize in the orthorhombic system and show the 3D rod-packing networks in 2-fold interpenetrated pattern with sra topology. Due to the different substituent laces of MOFs (-Cl vs -CH3), only MOF 1 shows highly selective and sensitive fluorescence sensing effect for detecting Hg2+ ion.

  1. Cathepsin K null mice show reduced adiposity during the rapid accumulation of fat stores.

    Directory of Open Access Journals (Sweden)

    Marcella Funicello

    Full Text Available Growing evidences indicate that proteases are implicated in adipogenesis and in the onset of obesity. We previously reported that the cysteine protease cathepsin K (ctsk is overexpressed in the white adipose tissue (WAT of obese individuals. We herein characterized the WAT and the metabolic phenotype of ctsk deficient animals (ctsk-/-. When the growth rate of ctsk-/- was compared to that of the wild type animals (WT, we could establish a time window (5-8 weeks of age within which ctsk-/-display significantly lower body weight and WAT size as compared to WT. Such a difference was not observable in older mice. Upon treatment with high fat diet (HFD for 12 weeks ctsk-/- gained significantly less weight than WT and showed reduced brown adipose tissue, liver mass and a lower percentage of body fat. Plasma triglycerides, cholesterol and leptin were significantly lower in HFD-fed-ctsk-/- as compared to HFD-fed WT animals. Adipocyte lipolysis rates were increased in both young and HFD-fed-ctsk-/-, as compared to WT. Carnitine palmitoyl transferase-1 activity, was higher in mitochondria isolated from the WAT of HFD treated ctsk-/- as compared to WT. Together, these data indicate that ctsk ablation in mice results in reduced body fat content under conditions requiring a rapid accumulation of fat stores. This observation could be partly explained by an increased release and/or utilization of FFA and by an augmented ratio of lipolysis/lipogenesis. These results also demonstrate that under a HFD, ctsk deficiency confers a partial resistance to the development of dyslipidemia.

  2. 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.

  3. Accumulation of mercury and methylmercury by mushrooms and earthworms from forest soils.

    Science.gov (United States)

    Rieder, Stephan R; Brunner, Ivano; Horvat, Milena; Jacobs, Anna; Frey, Beat

    2011-10-01

    Accumulation of total and methyl-Hg by mushrooms and earthworms was studied in thirty-four natural forest soils strongly varying in soil physico-chemical characteristics. Tissue Hg concentrations of both receptors did hardly correlate with Hg concentrations in soil. Both total and methyl-Hg concentrations in tissues were species-specific and dependent on the ecological groups of receptor. Methyl-Hg was low accounting for less than 5 and 8% of total Hg in tissues of mushrooms and earthworms, respectively, but with four times higher concentrations in earthworms than mushrooms. Total Hg concentrations in mushrooms averaged 0.96 mg Hg kg(-1) dw whereas litter decomposing mushrooms showed highest total Hg and methyl-Hg concentrations. Earthworms contained similar Hg concentrations (1.04 mg Hg kg(-1) dw) whereas endogeic earthworms accumulated highest amounts of Hg and methyl-Hg.

  4. Accumulation of mercury and methylmercury by mushrooms and earthworms from forest soils

    Energy Technology Data Exchange (ETDEWEB)

    Rieder, Stephan R. [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland); Institute for Biogeochemistry and Pollutant Dynamics, ETH Zuerich, 8092 Zuerich (Switzerland); Brunner, Ivano [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland); Horvat, Milena [Jozef Stefan Institute, 1001 Ljubliana (Slovenia); Jacobs, Anna [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland); Department of Environmental Chemistry, University of Kassel, 37213 Witzenhausen (Germany); Frey, Beat, E-mail: beat.frey@wsl.ch [Rhizosphere Processes Group, Swiss Federal Research Institute WSL, 8903 Birmensdorf (Switzerland)

    2011-10-15

    Accumulation of total and methyl-Hg by mushrooms and earthworms was studied in thirty-four natural forest soils strongly varying in soil physico-chemical characteristics. Tissue Hg concentrations of both receptors did hardly correlate with Hg concentrations in soil. Both total and methyl-Hg concentrations in tissues were species-specific and dependent on the ecological groups of receptor. Methyl-Hg was low accounting for less than 5 and 8% of total Hg in tissues of mushrooms and earthworms, respectively, but with four times higher concentrations in earthworms than mushrooms. Total Hg concentrations in mushrooms averaged 0.96 mg Hg kg{sup -1} dw whereas litter decomposing mushrooms showed highest total Hg and methyl-Hg concentrations. Earthworms contained similar Hg concentrations (1.04 mg Hg kg{sup -1} dw) whereas endogeic earthworms accumulated highest amounts of Hg and methyl-Hg. - Highlights: > Hg and MeHg concentrations in mushrooms and earthworms at unpolluted forest soils. > Mushrooms and earthworms contained similar Hg concentrations. > MeHg was present in traces but four times higher in earthworms than in mushrooms. > Ecophysiological group influenced Hg and MeHg concentration in both receptors. - Accumulation of Hg and methyl-Hg by mushrooms and earthworms is species- and ecophysiological group dependent.

  5. Atmospheric mercury accumulation and washoff processes on impervious urban surfaces

    Science.gov (United States)

    Eckley, C.S.; Branfireun, B.; Diamond, M.; Van Metre, P.C.; Heitmuller, F.

    2008-01-01

    The deposition and transport of mercury (Hg) has been studied extensively in rural environments but is less understood in urbanized catchments, where elevated atmospheric Hg concentrations and impervious surfaces may efficiently deliver Hg to waterways in stormwater runoff. We determined the rate at which atmospheric Hg accumulates on windows, identified the importance of washoff in removing accumulated Hg, and measured atmospheric Hg concentrations to help understand the relationship between deposition and surface accumulation. The main study location was Toronto, Ontario. Similar samples were also collected from Austin, Texas for comparison of Hg accumulation between cities. Windows provided a good sampling surface because they are ubiquitous in urban environments and are easy to clean/blank allowing the assessment of contemporary Hg accumulation. Hg Accumulation rates were spatially variable ranging from 0.82 to 2.7 ng m-2 d-1 in Toronto and showed similar variability in Austin. The highest accumulation rate in Toronto was at the city center and was 5?? higher than the rural comparison site (0.58 ng m-2 d-1). The atmospheric total gaseous mercury (TGM) concentrations were less than 2?? higher between the rural and urban locations (1.7 ?? 0.3 and 2.7 ?? 1.1 ng m-3, respectively). The atmospheric particulate bound fraction (HgP), however, was more than 3?? higher between the rural and urban sites, which may have contributed to the higher urban Hg accumulation rates. Windows exposed to precipitation had 73 ?? 9% lower accumulation rates than windows sheltered from precipitation. Runoff collected from simulated rain events confirmed that most Hg accumulated on windows was easily removed and that most of the Hg in washoff was HgP. Our results indicate that the Hg flux from urban catchments will respond rapidly to changes in atmospheric concentrations due to the mobilization of the majority of the surface accumulated Hg during precipitation events. ?? 2008 Elsevier

  6. Transgenic tobacco plants accumulating osmolytes show reduced oxidative damage under freezing stress.

    Science.gov (United States)

    Parvanova, Daniela; Ivanov, Sergei; Konstantinova, Tatyana; Karanov, Emanuil; Atanassov, Atanas; Tsvetkov, Tsvetan; Alexieva, Vera; Djilianov, Dimitar

    2004-01-01

    We studied the reaction to the oxidative component of freezing in several tobacco lines, transformed with genes coding for enzymes involved in the synthesis of osmoprotectants (proline, fructan or glycine betaine) along with their wild type. The levels of some oxidative stress markers (leakage of electrolytes, hydrogen peroxide and malondialdehyde) as well as the activity of antioxidative enzymes catalase (EC 1.11.1.6.) and guaiacol peroxidase (EC 1.11.1.7.) have been followed at acclimation, 12 and 24 h freezing and at recovery. Freezing for 24 h resulted in severe damages for the wild type. A corresponding increase of electrolyte leakage, hydrogen peroxide and malondialdehyde contents, a rise of peroxidase activity and inhibition of catalase activity occurred in the non-transformants. Similar, but significantly lower trend of the same parameters has been found for the transgenic lines. Moreover, the oxidative markers returned to their normal levels when the transformants were able to recover from freezing. It could be speculated that transfer of genes, coding for accumulation of osmoprotectants, is related to reduced intensity of freezing-induced oxidative processes. Our lines and model system could serve as a good prerequisite for additional studies to gain further insights into the complex role of osmoprotectants in freezing tolerance.

  7. 10个常绿树种对砷汞铅镉铬的富积能力研究%Heavy Metal Accumulation Capability of Ten Broadleaved Tree Species to As, Hg, Pb, Cd and Cr

    Institute of Scientific and Technical Information of China (English)

    毕波; 刘云彩; 陈强; 周筑; 张学星; 孙宏

    2012-01-01

    The contents of As, Hg, Pb, Cd and Cr in leaves of ten broadleaved tree species growing in the pollution area of Kunming Steel Company were determined to compare and analyze the heavy metal accumulation capabilities of the tested tree species. The results showed that the same species had different accumulation to different elements , simultaneously different species showed quite different accumulation to the same element. As, Pb, Cd and Cr were the main heavy pollution elements in the study area, and the all the elements were correlated with each other. Considering accumulation capability totally, the heavy metal element accumulation capabilities of these ten broadleaved tree species could be ranked as Viburnum punctatum > Delavaya yunnanensis > Meliosma yunnanensis > Euonymus yunnanensis > Stranvaesia davidiana > Acer oblongum > Decaspermum fruticosum > Cyclobalanopsis glau-coides > Craibiodendron yunnanense > Olea yunnanensis.%通过对10个常绿树种在昆钢污染区和对照叶片中砷、汞、铅、镉、铬5种重金属元素含量的试验测定,分析了各个树种对重金属的富积能力.结果表明,同一树种对不同类型重金属元素的富积能力不同,不同的树种对同一类型重金属的富积能力也有很大差异;参试的10个树种均对重金属元素表现出较好的抗性和富积能力,其中对砷、汞、铅、镉、铬的富积能力最强的树种分别是鳞斑荚蒾、红果树、鳞斑荚蒾、金叶子和云南泡花树.污染物中砷、铅、铬和镉的含量占了较大比重,各重金属元素在污染时存在相互关联.按综合富积能力排序,依次是鳞斑荚蒾>茶条木>云南泡花树>云南卫矛>红果树>飞蛾槭>子楝树>滇青冈>金叶子>云南木樨榄.

  8. Triclosan exhibits a tendency to accumulate in the epididymis and shows sperm toxicity in male Sprague-Dawley rats.

    Science.gov (United States)

    Lan, Zhou; Hyung Kim, Tae; Shun Bi, Kai; Hui Chen, Xiao; Sik Kim, Hyung

    2015-01-01

    Triclosan (TCS) is considered a potent endocrine disruptor that causes reproductive toxicity in non-mammals, but it is still unclear exactly whether TCS has adverse effects on the sperm or reproductive organs in mammals. In this study, we aimed to evaluate the distribution status of TCS in male reproductive organs of rats, and seek the correlation with the TCS-induced sperm toxicity or reproductive organ damage. Male rats were intragastrically administered with TCS at a dose of 50 mg/kg, the kinetics of TCS in the plasma and reproductive organs were investigated. TCS in testes and prostates both showed a lower-level distribution compared to that in the plasma, which indicates it has no tendency to accumulate in those organs. However, TCS in the epididymides showed a longer elimination half-life (t1/2 z), a longer the mean retention time (MRT), and a lower clearance (CLZ /F) compared with those in the plasma. Besides, the ratios of mean area under the concentration-time curve (AUC)(0-96 h(epididymides/plasma)) and AUC(0-∞(epididymides/plasma)) were 1.13 and 1.51, respectively. These kinetic parameters suggest TCS has an accumulation tendency in the epididymides. Based on this, we investigated the TCS-induced sperm toxicity and histopathological changes of reproductive organs in rats. TCS was given intragastrically at doses of 10, 50, and 200 mg/kg for 8 weeks. Rats treated with the high dose (200 mg/kg) of TCS showed a significant decrease in daily sperm production (DSP), changes in sperm morphology and epididymal histopathology. Considering the histopathological change in the epididymides, TCS may induce the epididymal damage due to the epididymal accumulation of that.

  9. Distribution and accumulation of elements (As, Cu, Fe, Hg, Mn, and Zn) in tissues of fish species from different trophic levels in the Danube River at the confluence with the Sava River (Serbia).

    Science.gov (United States)

    Subotić, S; Višnjić Jeftić, Ž; Spasić, S; Hegediš, A; Krpo-Ćetković, J; Lenhardt, M

    2013-08-01

    Pikeperch (Sander lucioperca), European catfish (Silurus glanis), common carp (Cyprinus carpio), and gobies (Neogobius gymnotrachelus, Neogobius melanostomus) were collected from the Danube River (Belgrade section), and samples of liver, muscle, or whole-body composites (in the case of gobies) were analyzed for As, Cu, Fe, Hg, Mn, and Zn with inductively coupled plasma optical spectrometry to find out if there was a correlation between accumulation of these elements in predatory and prey species, as well as in pairs of species with overlapping diets. Concentrations of all analyzed elements were either higher (Cu, Fe, Mn, Zn) in liver than in muscle, or equal (As, Hg), except for Hg in carp, which was higher in muscle. Mercury concentration in liver and muscle of predators (catfish, pikeperch) was significantly (<10(-4)) higher than in prey fishes (carp and gobies). The results indicate that Hg concentration was biomagnified through the food chain. Concentrations of As, Fe, and Hg in carp liver and gobies whole-body composite were similar, but carp had significantly (<10(-4)) higher values of Zn and Cu in liver. The regression analysis and trendline equations indicate that the concentrations of all tested elements, except for As in liver, and Mn and Fe in muscle, were similar in predatory fish (pikeperch and catfish), on one hand, and in prey fish (carp and gobies), on the other hand. Distinctly high Zn concentration in carp is very common in this species due to its physiology. Concentrations of Hg and Zn were higher than the maximum acceptable concentration due to the high pollution level in this section of the Danube River, accordingly posing a risk for the human consumption of these fish species.

  10. Preventive effect of CuCl₂ on behavioral alterations and mercury accumulation in central nervous system induced by HgCl2 in newborn rats.

    Science.gov (United States)

    Moraes-Silva, L; Siqueira, L F; Oliveira, V A; Oliveira, C S; Ineu, R P; Pedroso, T F; Fonseca, M M; Pereira, M E

    2014-07-01

    This study investigated the benefits of Cu preexposition on Hg effects on behavioral tests, acetylcholinesterase (AChE) activity and Hg, and essential metal contents in the cerebrum and cerebellum of neonate rats. Wistar rats received (subcutaneous) saline or CuCl2 ·2H2O (6.9 mg/kg/day) when they were 3 to 7 days old and saline or HgCl2 (5.0 mg/kg/day) when they were 8 to 12 days old. Mercury exposure reduced the performance of rats in the negative geotaxis (3-13 days) and beaker test (17-20 days), inhibited cerebellum AChE activity (13 days), increased cerebrum and cerebellum Hg (13 days), cerebrum Cu (13 days), and cerebrum and cerebellum Zn levels (33 days). The performance of rats in the tail immersion and rotarod tests as well as Fe and Mg levels were not altered by treatments. Copper prevented all alterations induced by mercury. These results are important to open a new perspective of prevention and/or therapy for mercury exposure.

  11. 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.

  12. Clusterin: full-length protein and one of its chains show opposing effects on cellular lipid accumulation

    Science.gov (United States)

    Matukumalli, Suvarsha Rao; Tangirala, Ramakrishna; Rao, C. M.

    2017-01-01

    Proteins, made up of either single or multiple chains, are designed to carry out specific biological functions. We found an interesting example of a two-chain protein where administration of one of its chains leads to a diametrically opposite outcome than that reported for the full-length protein. Clusterin is a highly glycosylated protein consisting of two chains, α- and β-clusterin. We have investigated the conformational features, cellular localization, lipid accumulation, in vivo effects and histological changes upon administration of recombinant individual chains of clusterin. We demonstrate that recombinant α- and β-chains exhibit structural and functional differences and differ in their sub-cellular localization. Full-length clusterin is known to lower lipid levels. In contrast, we find that β-chain-treated cells accumulate 2-fold more lipid than controls. Interestingly, α-chain-treated cells do not show such increase. Rabbits injected with β-chain, but not α-chain, show ~40% increase in weight, with adipocyte hypertrophy, liver and kidney steatosis. Many, sometimes contrasting, roles are ascribed to clusterin in obesity, metabolic syndrome and related conditions. Our findings of differential localization and activities of individual chains of clusterin should help in understanding better the roles of clusterin in metabolism. PMID:28120874

  13. Trigeminal ganglion neurons of mice show intracellular chloride accumulation and chloride-dependent amplification of capsaicin-induced responses.

    Directory of Open Access Journals (Sweden)

    Nicole Schöbel

    Full Text Available Intracellular Cl(- concentrations ([Cl(-](i of sensory neurons regulate signal transmission and signal amplification. In dorsal root ganglion (DRG and olfactory sensory neurons (OSNs, Cl(- is accumulated by the Na(+-K(+-2Cl(- cotransporter 1 (NKCC1, resulting in a [Cl(-](i above electrochemical equilibrium and a depolarizing Cl(- efflux upon Cl(- channel opening. Here, we investigate the [Cl(-](i and function of Cl(- in primary sensory neurons of trigeminal ganglia (TG of wild type (WT and NKCC1(-/- mice using pharmacological and imaging approaches, patch-clamping, as well as behavioral testing. The [Cl(-](i of WT TG neurons indicated active NKCC1-dependent Cl(- accumulation. Gamma-aminobutyric acid (GABA(A receptor activation induced a reduction of [Cl(-](i as well as Ca(2+ transients in a corresponding fraction of TG neurons. Ca(2+ transients were sensitive to inhibition of NKCC1 and voltage-gated Ca(2+ channels (VGCCs. Ca(2+ responses induced by capsaicin, a prototypical stimulus of transient receptor potential vanilloid subfamily member-1 (TRPV1 were diminished in NKCC1(-/- TG neurons, but elevated under conditions of a lowered [Cl(-](o suggesting a Cl(--dependent amplification of capsaicin-induced responses. Using next generation sequencing (NGS, we found expression of different Ca(2+-activated Cl(- channels (CaCCs in TGs of mice. Pharmacological inhibition of CaCCs reduced the amplitude of capsaicin-induced responses of TG neurons in Ca(2+ imaging and electrophysiological recordings. In a behavioral paradigm, NKCC1(-/- mice showed less avoidance of the aversive stimulus capsaicin. In summary, our results strongly argue for a Ca(2+-activated Cl(--dependent signal amplification mechanism in TG neurons that requires intracellular Cl(- accumulation by NKCC1 and the activation of CaCCs.

  14. 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.

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

    Science.gov (United States)

    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

  16. Antioxidative response of Lepidium sativum L. during assisted phytoremediation of Hg contaminated soil.

    Science.gov (United States)

    Smolinska, Beata; Szczodrowska, Agnieszka

    2017-09-25

    In this study, Lepidium sativum L. was used in repeated phytoextraction processes to remove Hg from contaminated soil, assisted by combined use of compost and iodide (KI). L. sativum L. is sensitive to changes in environmental conditions and has been used in environmental tests. Its short vegetation period and ability to accumulate heavy metals make it suitable for use in repeated phytoextraction. The antioxidant enzymatic system of the plant (catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and glutathione S-transferase (GST)) was analysed, to understand the effects of increasing Hg accumulation and translocation. Phytoextraction was repeated six times to decrease Hg contamination in soil, and the efficiency of each step was assessed. The results indicate that L. sativum L. is able to take up and accumulate Hg from contaminated soil. A corresponding increase in enzymatic antioxidants shows that the plant defence system is activated in response to Hg stress. Using compost and KI increases total Hg accumulation and translocation to the above-ground parts of L. sativum L. Repeating the process decreases Hg contamination in pot experiments in all variants of the process. The combined use of compost and KI during repeated phytoextraction increases the efficiency of Hg removal from contaminated soil. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Mercury bioaccumulation in the aquatic plant Elodea nuttallii in the field and in microcosm: accumulation in shoots from the water might involve copper transporters.

    Science.gov (United States)

    Regier, Nicole; Larras, Floriane; Bravo, Andrea Garcia; Ungureanu, Viorel-Gheorghe; Amouroux, David; Cosio, Claudia

    2013-01-01

    Previous studies suggest that macrophytes might participate in bioaccumulation and biomagnification of toxic mercury (Hg) in aquatic environment. Hg bioaccumulation and uptake mechanisms in macrophytes need therefore to be studied. Amongst several macrophytes collected in an Hg contaminated reservoir in Romania, Elodea nuttallii showed a high organic and inorganic Hg accumulation and was then further studied in the laboratory. Tolerance and accumulation of Hg of this plant was also high in the microcosm. Basipetal transport of inorganic Hg was predominant, whereas acropetal transport of methyl-Hg was observed with apparently negligible methylation or demethylation in planta. Hg concentrations were higher in roots>leaves>stems and in top>middle>bottom of shoots. In shoots, more than 60% Hg was found intracellularly where it is believed to be highly available to predators. Accumulation in shoots was highly reduced by cold, death and by competition with Cu(+). Hg in E. nuttallii shoots seems to mainly originate from the water column, but methyl-Hg could also be remobilized from the sediments and might drive in part its entry in the food web. At the cellular level, uptake of Hg into the cell sap of shoots seems linked to the metabolism and to copper transporters. The present work highlights an important breakthrough in our understanding of Hg accumulation and biomagnifications: the remobilization of methyl-Hg from sediments to aquatic plants and differences in uptake mechanisms of inorganic and methyl-Hg in a macrophyte.

  18. 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.

  19. Induction by mercury compounds of brain metallothionein in rats: Hg{sup 0} exposure induces long-lived brain metallothionein

    Energy Technology Data Exchange (ETDEWEB)

    Yasutake, Akira; Nakano, Atsuhiro [Biochemistry Section, National Institute for Minamata Disease, Kumamoto (Japan); Hirayama, Kimiko [Kumamoto University, College of Medical Science (Japan)

    1998-03-01

    Metallothionein (MT) is one of the stress proteins which can easily be induced by various kind of heavy metals. However, MT in the brain is difficult to induce because of blood-brain barrier impermeability to most heavy metals. In this paper, we have attempted to induce brain MT in rats by exposure to methylmercury (MeHg) or metallic mercury vapor, both of which are known to penetrate the blood-brain barrier and cause neurological damage. Rats treated with MeHg (40 {mu}mol/kg per day x 5 days, p.o.) showed brain Hg levels as high as 18 {mu}g/g with slight neurological signs 10 days after final administration, but brain MT levels remained unchanged. However, rats exposed to Hg vapor for 7 days showed 7-8 {mu}g Hg/g brain tissue 24 h after cessation of exposure. At that time brain MT levels were about twice the control levels. Although brain Hg levels fell gradually with a half-life of 26 days, MT levels induced by Hg exposure remained unchanged for >2 weeks. Gel fractionation revealed that most Hg was in the brain cytosol fraction and thus bound to MT. Hybridization analysis showed that, despite a significant increase in MT-I and -II mRNA in brain, MT-III mRNA was less affected. Although significant Hg accumulation and MT induction were observed also in kidney and liver of Hg vapor-exposed rats, these decreased more quickly than in brain. The long-lived MT in brain might at least partly be accounted for by longer half-life of Hg accumulated there. The present results showed that exposure to Hg vapor might be a suitable procedure to provide an in vivo model with enhanced brain MT. (orig.) With 4 figs., 1 tab., 27 refs.

  20. 强烈人为作用下城镇周围汞的空间变异及其积累迁移规律%SPATIAL VARIABILITY, ACCUMULATION AND TRANSFER OF Hg IN SOILS AROUND TOWNS UNDER INTENSIVE HUMAN ACTIVITIES IN THE YANGTZE RIVER DELTA REGION, CHINA

    Institute of Scientific and Technical Information of China (English)

    王梅; 黄标; 孙维侠; 赵永存

    2011-01-01

    研究土壤中汞(Hg)元素积累的空间变异和迁移转化规律对土壤利用、环境评价和污染修复具有重要参考价值.本研究选择经济发展迅速的苏南某地为研究区域,对土壤、水稻和大气降尘中的Hg进行了详细分析.结果表明,该区域土壤全汞平均含量达1345μg kg-1,有效汞(HCl-Hg)平均含量51 μg kg-1,水稻Hg平均含量20 μg kg-1,大气Hg沉降量为5.13 g km-230 d-1.土壤和水稻高含量Hg主要积聚于城镇周边,随着与城镇距离的增加其含量逐渐减少.大气Hg沉降量在空间上变化不大.进入土壤中的Hg主要在土壤表层0~20 cm范围内富集,但直至60 cm深处依然存在积累现象,整个剖面土壤活性态汞和半活性态汞含量占全汞的比例变化不大.研究区土壤出现了明显Hg积累,导致水稻Hg吸收明显增加,不少样点超过了国家土壤环境质量二级标准(300μg kg-1)和国家食品污染物限量标准(20 μg kg-1),可能对环境和人体健康产生危害.较低的大气Hg沉降量和土壤积累的Hg已与土壤条件达到平衡的事实表明,目前Hg的积累已明显减少.今后应采取措施修复污染土壤或者通过改变作物种类来减少土壤Hg含量或抑制作物对Hg的吸收,达到环境治理的目的.%The research on spatial variability, accumulation and transfer of soil mercury (Hg) has great reference values to soil utilization, environmental assessment and polluted soil remediation. Mercury in the soil, rice and atmospheric deposition in an area with fast developing economy in the South Jiangsu was analyzed. It was found that on average, the soil total Hg was 1345 μg kg-1, available (HCl-extractable or HCl-Hg) 51 μg kg-1, Hg in rice 20 μg kg-1 and Hg in atmospheric deposition 5.13 g km-2 30 d-1. Spatially, high Hg concentrations in soil and rice were found mainly in places closely around the town, and the concentration decreased exponentially with the distance of the sampling site from

  1. Root application of selenite can simultaneously reduce arsenic and cadmium accumulation and maintain grain yields, but show negative effects on the grain quality of paddy rice.

    Science.gov (United States)

    Liao, Guojian; Xu, Yi; Chen, Cheng; Wu, Qianhua; Feng, Renwei; Guo, Junkang; Wang, Ruigang; Ding, Yongzhen; Sun, Yang; Xu, Yingming; Xia, Wei; Fan, Zhilian; Mo, Liangyu

    2016-12-01

    Most current technologies can hardly simultaneously reduce the accumulation of arsenic (As) and cadmium (Cd) in crops. In this study, root application of selenite [Se (IV)] and selenate [Se (VI)] was used to assess their abilities to reduce the accumulation of As and Cd, and maintain the yields and quality of rice grains. The results show that Se (IV) showed a weaker ability than Se (VI) to maintain the grain contents of many essential elements, but a stronger ability to decrease As and Cd contents in rice grains, and maintain the yields, photosynthesis rate and stomatal conductance, and increase the grain contents of several amino acids (AAs), total Se, selenomethionine (SeMet) and selenocysteine (SeCys). The best outcomes resulted at a relatively high application of 5 mg kg(-1) Se (IV), reflecting in the highest total Se, SeCys and SeMet content (14.95, 118.70 and 864.73 μg kg(-1), respectively) in the grains, highest grain yield, and lowest grain As and Cd content (0.36 and 0.07 mg kg(-1), respectively). In addition, the application of 1-5 mg kg(-1) Se (IV) seemed to facilitate the formation of SeMet in the grains, but most inorganic Se in the grains were transformed into SeCys and SeMet under Se (VI) treatments. This study provides a new idea to resolve the problems of high accumulation of As and Cd in rice grains and insufficiency of Se intake in China. Copyright © 2016. Published by Elsevier Ltd.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

    Mercury (Hg) associated with mixed waste generated by nuclear weapons manufacturing has contaminated vast areas of the Oak Ridge Reservation (ORR). Neurotoxic methylmercury (MeHg) has been formed from the inorganic Hg wastes discharged into headwaters of East Fork Poplar Creek (EFPC). Thus, understanding the processes and mechanisms that lead to Hg methylation along the flow path of EFPC is critical to predicting the impacts of the contamination and the design of remedial action at the ORR. In part I of our project, we investigated Hg(0) oxidation and methylation by anaerobic bacteria. We discovered that the anaerobic bacterium Desulfovibrio desulfuricans ND132 can oxidize elemental mercury [Hg(0)]. When provided with dissolved elemental mercury, D. desulfuricans ND132 converts Hg(0) to Hg(II) and neurotoxic methylmercury [MeHg]. We also demonstrated that diverse species of subsurface bacteria oxidizes dissolved elemental mercury under anoxic conditions. The obligate anaerobic bacterium Geothrix fermentans H5, and the facultative anaerobic bacteria Shewanella oneidensis MR-1 and Cupriavidus metallidurans AE104 can oxidize Hg(0) to Hg(II) under anaerobic conditions. In part II of our project, we established anaerobic enrichment cultures and obtained new bacterial strains from the DOE Oak Ridge site. We isolated three new bacterial strains from subsurface sediments collected from Oak Ridge. These isolates are Bradyrhizobium sp. strain FRC01, Clostridium sp. strain FGH, and a novel Negativicutes strain RU4. Strain RU4 is a completely new genus and species of bacteria. We also demonstrated that syntrophic interactions between fermentative bacteria and sulfate-reducing bacteria in Oak Ridge saprolite mediate iron reduction via multiple mechanisms. Finally, we tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge site, where nitrate is a major contaminant. We showed that there is an inverse

  7. 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

    Mercury (Hg) associated with mixed waste generated by nuclear weapons manufacturing has contaminated vast areas of the Oak Ridge Reservation (ORR). Neurotoxic methylmercury (MeHg) has been formed from the inorganic Hg wastes discharged into headwaters of East Fork Poplar Creek (EFPC). Thus, understanding the processes and mechanisms that lead to Hg methylation along the flow path of EFPC is critical to predicting the impacts of the contamination and the design of remedial action at the ORR. In part I of our project, we investigated Hg(0) oxidation and methylation by anaerobic bacteria. We discovered that the anaerobic bacterium Desulfovibrio desulfuricans ND132 can oxidize elemental mercury [Hg(0)]. When provided with dissolved elemental mercury, D. desulfuricans ND132 converts Hg(0) to Hg(II) and neurotoxic methylmercury [MeHg]. We also demonstrated that diverse species of subsurface bacteria oxidizes dissolved elemental mercury under anoxic conditions. The obligate anaerobic bacterium Geothrix fermentans H5, and the facultative anaerobic bacteria Shewanella oneidensis MR-1 and Cupriavidus metallidurans AE104 can oxidize Hg(0) to Hg(II) under anaerobic conditions. In part II of our project, we established anaerobic enrichment cultures and obtained new bacterial strains from the DOE Oak Ridge site. We isolated three new bacterial strains from subsurface sediments collected from Oak Ridge. These isolates are Bradyrhizobium sp. strain FRC01, Clostridium sp. strain FGH, and a novel Negativicutes strain RU4. Strain RU4 is a completely new genus and species of bacteria. We also demonstrated that syntrophic interactions between fermentative bacteria and sulfate-reducing bacteria in Oak Ridge saprolite mediate iron reduction via multiple mechanisms. Finally, we tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge site, where nitrate is a major contaminant. We showed that there is an inverse

  8. Accumulation of mercury in rice grain and cabbage grown on representative Chinese soils

    Institute of Scientific and Technical Information of China (English)

    Chun-fa LIU; Ting-qiang LI; Xiao-e YANG; Cheng-xian WU; Muhammad T. RAFIQ; Rukhsanda AZIZ; Dan-di HOU; Zhe-li DING; Zi-wen LIN; Lin-jun LOU; Yuan-yuan FENG

    2013-01-01

    A pot culture experiment was carried out to investigate the accumulation properties of mercury (Hg) in rice grain and cabbage grown in seven soil types (Udic Ferrisols, Mol isol, Periudic Argosols, Latosol, Ustic Cambosols, Calcaric Regosols, and Stagnic Anthrosols) spiked with different concentrations of Hg (CK, 0.25, 0.50, 1.00, 2.00, and 4.00 mg/kg). The results of this study showed that Hg accumulation of plants was significantly affected by soil types. Hg concentration in both rice grain and cabbage increased with soil Hg concentrations, but this increase differed among the seven soils. The stepwise multiple regression analysis showed that pH, Mn(II), particle size distribution, and cation exchange capacity have a close relationship with Hg accumulation in plants, which suggested that physico-chemical characteristics of soils can affect the Hg accumulation in rice grain and cabbage. Critical Hg concentrations in seven soils were identified for rice grain and cabbage based on the maximum safe level for daily intake of Hg, dietary habits of the population, and Hg accumulation in plants grown in different soil types. Soil Hg limits for rice grain in Udic Ferrisols, Mol isol, Periudic Argosols, Latosol, Ustic Cambosols, Calcaric Regosols, and Stagnic Anthrosols were 1.10, 2.00, 2.60, 2.78, 1.53, 0.63, and 2.17 mg/kg, respectively, and critical soil Hg levels for cabbage are 0.27, 1.35, 1.80, 1.70, 0.69, 1.68, and 2.60 mg/kg, respectively.

  9. Accumulation of mercury in rice grain and cabbage grown on representative Chinese soils.

    Science.gov (United States)

    Liu, Chun-fa; Wu, Cheng-xian; Rafiq, Muhammad T; Aziz, Rukhsanda; Hou, Dan-di; Ding, Zhe-li; Lin, Zi-wen; Lou, Lin-jun; Feng, Yuan-yuan; Li, Ting-qiang; Yang, Xiao-e

    2013-12-01

    A pot culture experiment was carried out to investigate the accumulation properties of mercury (Hg) in rice grain and cabbage grown in seven soil types (Udic Ferrisols, Mollisol, Periudic Argosols, Latosol, Ustic Cambosols, Calcaric Regosols, and Stagnic Anthrosols) spiked with different concentrations of Hg (CK, 0.25, 0.50, 1.00, 2.00, and 4.00 mg/kg). The results of this study showed that Hg accumulation of plants was significantly affected by soil types. Hg concentration in both rice grain and cabbage increased with soil Hg concentrations, but this increase differed among the seven soils. The stepwise multiple regression analysis showed that pH, Mn(II), particle size distribution, and cation exchange capacity have a close relationship with Hg accumulation in plants, which suggested that physicochemical characteristics of soils can affect the Hg accumulation in rice grain and cabbage. Critical Hg concentrations in seven soils were identified for rice grain and cabbage based on the maximum safe level for daily intake of Hg, dietary habits of the population, and Hg accumulation in plants grown in different soil types. Soil Hg limits for rice grain in Udic Ferrisols, Mollisol, Periudic Argosols, Latosol, Ustic Cambosols, Calcaric Regosols, and Stagnic Anthrosols were 1.10, 2.00, 2.60, 2.78, 1.53, 0.63, and 2.17 mg/kg, respectively, and critical soil Hg levels for cabbage are 0.27, 1.35, 1.80, 1.70, 0.69, 1.68, and 2.60 mg/kg, respectively.

  10. Real and potential mercury accumulation in human scalp of adolescents: a case study.

    Science.gov (United States)

    Vieira, H C; Morgado, F; Soares, A M V M; Abreu, S N

    2015-02-01

    Mercury (Hg) concentration in human hair is used to estimate methylmercury (MeHg) exposure and establish a reference dose for MeHg intake. In this study, Hg accumulation and MeHg intake were evaluated in relation to fish consumption habits in adolescents from two coastal areas: Angra do Heroísmo (Azores archipelago) and Murtosa (Portuguese mainland). Results showed that Hg concentration and MeHg intake increased with increasing fish consumption. In spite of that, Hg concentrations remained relatively low when compared with World Health Organization "no observed adversary effect level"; therefore, risk for mercury exposure should not be considered. Adolescents revealed a similar range of Hg concentrations (0.03-2.60 μg g(-1)) in scalp hair, apart from being exposed to natural or anthropogenic Hg source (Azores and Mainland, respectively). Nevertheless, Mainland volunteers generally exhibited higher values of Hg accumulation, being approximately 50 % of the results above 1 μg g(-1). Hg concentrations increased in both adolescent groups according to the weekly rate of fish meals, however, not linearly in the highest fish consumption rates. In fact, considering the adolescents' group having over one fish meal per week, the Hg bioaccumulation pattern found in the respective scalp hair suggests the ability of the human body to induce a self-protection response, probably mitigating Hg levels in the blood when experiencing increasing Hg exposure due to fish uptake. Actual and potential mercury levels in human scalp of adolescents probably diverge as fish consumption increases, the effective Hg uptake being lower than the expected, reducing risk to human health.

  11. Geomorphic controls on mercury accumulation in soils from a historically mined watershed, Central California Coast Range, USA

    Science.gov (United States)

    Holloway, J.M.; Goldhaber, M.B.; Morrison, J.M.

    2009-01-01

    Historic Hg mining in the Cache Creek watershed in the Central California Coast Range has contributed to the downstream transport of Hg to the San Francisco Bay-Delta. Different aspects of Hg mobilization in soils, including pedogenesis, fluvial redistribution of sediment, volatilization and eolian transport were considered. The greatest soil concentrations (>30 mg Hg kg-1) in Cache Creek are associated with mineralized serpentinite, the host rock for Hg deposits. Upland soils with non-mineralized serpentine and sedimentary parent material also had elevated concentrations (0.9-3.7 mg Hg kg-1) relative to the average concentration in the region and throughout the conterminous United States (0.06 mg kg-1). Erosion of soil and destabilized rock and mobilization of tailings and calcines into surrounding streams have contributed to Hg-rich alluvial soil forming in wetlands and floodplains. The concentration of Hg in floodplain sediment shows sediment dispersion from low-order catchments (5.6-9.6 mg Hg kg-1 in Sulphur Creek; 0.5-61 mg Hg kg-1 in Davis Creek) to Cache Creek (0.1-0.4 mg Hg kg-1). These sediments, deposited onto the floodplain during high-flow storm events, yield elevated Hg concentrations (0.2-55 mg Hg kg-1) in alluvial soils in upland watersheds. Alluvial soils within the Cache Creek watershed accumulate Hg from upstream mining areas, with concentrations between 0.06 and 0.22 mg Hg kg-1 measured in soils ~90 km downstream from Hg mining areas. Alluvial soils have accumulated Hg released through historic mining activities, remobilizing this Hg to streams as the soils erode.

  12. Quantitative trait loci for mercury accumulation in maize (Zea mays L.) identified using a RIL population.

    Science.gov (United States)

    Fu, Zhongjun; Li, Weihua; Zhang, Qinbin; Wang, Long; Zhang, Xiaoxiang; Song, Guiliang; Fu, Zhiyuan; Ding, Dong; Liu, Zonghua; Tang, Jihua

    2014-01-01

    To investigate the genetic mechanism of mercury accumulation in maize (Zea mays L.), a population of 194 recombinant inbred lines derived from an elite hybrid Yuyu 22, was used to identify quantitative trait loci (QTLs) for mercury accumulation at two locations. The results showed that the average Hg concentration in the different tissues of maize followed the order: leaves > bracts > stems > axis > kernels. Twenty-three QTLs for mercury accumulation in five tissues were detected on chromosomes 1, 4, 7, 8, 9 and 10, which explained 6.44% to 26.60% of the phenotype variance. The QTLs included five QTLs for Hg concentration in kernels, three QTLs for Hg concentration in the axis, six QTLs for Hg concentration in stems, four QTLs for Hg concentration in bracts and five QTLs for Hg concentration in leaves. Interestingly, three QTLs, qKHC9a, qKHC9b, and qBHC9 were in linkage with two QTLs for drought tolerance. In addition, qLHC1 was in linkage with two QTLs for arsenic accumulation. The study demonstrated the concentration of Hg in Hg-contaminated paddy soil could be reduced, and maize production maintained simultaneously by selecting and breeding maize Hg pollution-safe cultivars (PSCs).

  13. Quantitative trait loci for mercury accumulation in maize (Zea mays L. identified using a RIL population.

    Directory of Open Access Journals (Sweden)

    Zhongjun Fu

    Full Text Available To investigate the genetic mechanism of mercury accumulation in maize (Zea mays L., a population of 194 recombinant inbred lines derived from an elite hybrid Yuyu 22, was used to identify quantitative trait loci (QTLs for mercury accumulation at two locations. The results showed that the average Hg concentration in the different tissues of maize followed the order: leaves > bracts > stems > axis > kernels. Twenty-three QTLs for mercury accumulation in five tissues were detected on chromosomes 1, 4, 7, 8, 9 and 10, which explained 6.44% to 26.60% of the phenotype variance. The QTLs included five QTLs for Hg concentration in kernels, three QTLs for Hg concentration in the axis, six QTLs for Hg concentration in stems, four QTLs for Hg concentration in bracts and five QTLs for Hg concentration in leaves. Interestingly, three QTLs, qKHC9a, qKHC9b, and qBHC9 were in linkage with two QTLs for drought tolerance. In addition, qLHC1 was in linkage with two QTLs for arsenic accumulation. The study demonstrated the concentration of Hg in Hg-contaminated paddy soil could be reduced, and maize production maintained simultaneously by selecting and breeding maize Hg pollution-safe cultivars (PSCs.

  14. [Dissolution, absorption and bioaccumulation in gastrointestinal tract of mercury in HgS-containing traditional medicines Cinnabar and Zuotai].

    Science.gov (United States)

    Zheng, Zhi-yuan; Li, Cen; Zhang, Ming; Yang, Hong-xia; Geng, Lu-jing; Li, Lin-shuai; Du, Yu-zhi; Wei, Li-xin

    2015-06-01

    α-HgS is the main component of traditional Chinese medicine cinnabar, while β-HgS is the main component of Tibetan medicine Zuotai. However, there was no comparative study on the dissolution and absorption in gastrointestinal tract and bioaccumulation in organs of mercury in Cinnabar, Zuotai, α-HgS and β-HgS. In this study, the dissolution process of the four compounds in the human gastrointestinal tract was simulated to determine the mercury dissolutions and compare the mercury dissolution of different medicines and the dissolution-promoting capacity of different solutions. To explore the absorption and bioaccumulation of cinnabar and Zuotai in organisms, mice were orally administered with clinical equivalent doses cinnabar and Zuotai. Meanwhile, a group of mice was given α-HgS and β-HgS with the equivalent mercury with cinnabar, while another group was given β-HgS and HgCl2 with the equivalent mercury with Zuotai. The mercury absorption and bioaccumulation capacities of different medicines in mice and their mercury bioaccumulation in different tissues and organs were compared. The experimental results showed a high mercury dissolutions of Zuotai in artificial gastrointestinal fluid, which was followed by β-HgS, cinnabar and α-HgS. As for the mercury absorption and bioaccumulation in mice, HgCl2 was the highest, β-HgS was the next, and a-HgS was slightly higher than cinnabar. The organs with the mercury bioaccumulation from high to low were kidney, liver and brain. This study is close to clinical practices and can provide reference for the clinical safe medication as well as a study model for the safety evaluation on heavy metal-containing medicines by observing the mercury dissolution, absorption, distribution and accumulation of mercury-containing medicines cinnabar and zuotai.

  15. Contrasting mercury accumulation patterns in tilapia (Oreochromis niloticus) and implications on somatic growth dilution.

    Science.gov (United States)

    Wang, Rui; Wang, Wen-Xiong

    2012-06-15

    Dietary ingestion constitutes a major pathway for mercury (Hg) accumulation in freshwater fish, thus the ingestion rate (IR) may greatly influence the Hg bioaccumulation through its effect on Hg influx and other biokinetic processes. To explore the complex influence of IR, we conducted long-term bioaccumulation experiments by accurately controlling the IRs in the freshwater tilapia (Oreochromis niloticus). The dietary accumulation of both inorganic mercury (Hg[II]) and methylmercury (MeHg) in tilapia under different IRs was monitored over a period of 30 days by feeding the fish with uniformly radiolabeled crustaceans. The biokinetic parameters under various IRs were concurrently determined. With the increase of IR from 0.01 g g⁻¹ d⁻¹ to 0.12 g g⁻¹ d⁻¹, the dietary assimilation efficiency of Hg(II) in the tilapia decreased by 43% while the elimination rate increased by a factor of 1.8; both biokinetic changes slowed down the overall Hg(II) bioaccumulation at high IRs. In contrast to Hg(II), the biokinetics of MeHg was not significantly influenced, but its bioaccumulation increased disproportionally with increasing IR, showing slower increase at higher IR. We then employed a biokinetic model to simulate the long-term mercury bioaccumulation patterns in tilapia at various IRs. The modeling results indicated that the growth effect could not be ignored in long-term accumulation process. A rapid growth of fish driven by food availability could significantly reduce the MeHg concentrations in the tilapia. Our results demonstrated for the first time the contrasting influences of dietary ingestion on the long-term bioaccumulation of Hg(II) and MeHg. The somatic growth dilution was much more likely to occur for MeHg than for Hg(II).

  16. The study of heavy metal pollution and accumulation in water, sediment, and fish tissue in Kizilirmak River Basin in Turkey.

    Science.gov (United States)

    Akbulut, Aydin; Akbulut, Nuray Emir

    2010-08-01

    The accumulation of heavy metals such as Pb, Hg, Co, Cr, Cu, Zn, and Br were determined in water, sediment, muscle, and gill of three fish species (Leuciscus cephalus, Capoeta tinca, Capoeta capoeta) which were collected in Kizilirmak River Basin (Delice River). The metal concentration showed a general trend of Br>Zn>Pb>Cr>Cu>Hg>Co in water and Cr>Zn>Pb>Cu>Co>Hg>Br in sediment samples while Zn>Cu>Pb>Br>Cr>Hg>Co were in muscle and Zn>Pb>Cu>Cr>Br>Hg>Co were in the gill tissue.

  17. 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.

  18. Differential transcript profiling through cDNA-AFLP showed complexity of rutin biosynthesis and accumulation in seeds of a nutraceutical food crop (Fagopyrum spp.

    Directory of Open Access Journals (Sweden)

    Gupta Nidhi

    2012-06-01

    Full Text Available Abstract Background Buckwheat, consisting of two cultivated species Fagopyrum tataricum and F. esculentum, is the richest source of flavonoid rutin. Vegetative tissues of both the Fagopyrum species contain almost similar amount of rutin; however, rutin content in seed of F. tataricum are ~50 folds of that in seed of F. esculentum. In order to understand the molecular basis of high rutin content in F. tataricum, differential transcript profiling through cDNA-AFLP has been utilized to decipher what genetic factors in addition to flavonoid structural genes contribute to high rutin content of F. tataricum compared to F. esculentum. Results Differential transcript profiling through cDNA-AFLP in seed maturing stages (inflorescence to seed maturation with 32 primer combinations generated total of 509 transcript fragments (TDFs. 167 TDFs were then eluted, cloned and sequenced from F. tataricum and F. esculentum. Categorization of TDFs on the basis of their presence/absence (qualitative variation or differences in the amount of expression (quantitative variation between both the Fagopyrum species showed that majority of variants are quantitative (64%. The TDFs represented genes controlling different biological processes such as basic and secondary metabolism (33%, regulation (18%, signal transduction (14%, transportation (13%, cellular organization (10%, and photosynthesis & energy (4%. Most of the TDFs except belonging to cellular metabolism showed relatively higher transcript abundance in F. tataricum over F. esculentum. Quantitative RT-PCR analysis of nine TDFs representing genes involved in regulation, metabolism, signaling and transport of secondary metabolites showed that all the tested nine TDFs (Ubiquitin protein ligase, ABC transporter, sugar transporter except MYB 118 showed significantly higher expression in early seed formation stage (S7 of F. tataricum compared to F. esculentum. qRT-PCR results were found to be consistent with the c

  19. 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.

  20. Evaluation of the mercury contamination in mushrooms of genus Leccinum from two different regions of the world: Accumulation, distribution and probable dietary intake.

    Science.gov (United States)

    Falandysz, Jerzy; Zhang, Ji; Wang, Yuanzhong; Krasińska, Grażyna; Kojta, Anna; Saba, Martyna; Shen, Tao; Li, Tao; Liu, Honggao

    2015-12-15

    This study focused on investigation of the accumulation and distribution of mercury (Hg) in mushrooms of the genus Leccinum that emerged on soils of totally different geochemical bedrock composition. Hg in 6 species from geographically diverse regions of the mercuriferous belt areas in Yunnan of SW China, and 8 species from the non-mercuriferous regions of Poland in Europe was measured. Also assessed was the probable dietary intake of Hg from consumption of Leccinum spp., which are traditional organic food items in SW China and Poland. The results showed that L. chromapes, L. extremiorientale, L. griseum and L. rugosicepes are good accumulators of Hg and the sequestered Hg in caps were up to 4.8, 3.5, 3.6 and 4.7 mg Hg kg(-1) dry matter respectively. Leccinum mushrooms from Poland also efficiently accumulated Hg with their average Hg content being an order of magnitude lower due to low concentrations of Hg in forest topsoil of Poland compared to the elevated contents in Yunnan. Consumption of Leccinum mushrooms with elevated Hg contents in Yunnan at rates of up to 300 g fresh product per week during the foraging season would not result in Hg intake that exceeds the provisional weekly tolerance limit of 0.004 mg kg(-1) body mass, assuming no Hg ingestion from other foods.

  1. 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.

  2. Supplementation with Sodium Selenite and Selenium-Enriched Microalgae Biomass Show Varying Effects on Blood Enzymes Activities, Antioxidant Response, and Accumulation in Common Barbel (Barbus barbus

    Directory of Open Access Journals (Sweden)

    Antonín Kouba

    2014-01-01

    Full Text Available Yearling common barbel (Barbus barbus L. were fed four purified casein-based diets for 6 weeks in outdoor cages. Besides control diet, these were supplemented with 0.3 mg kg−1 dw selenium (Se from sodium selenite, or 0.3 and 1.0 mg kg−1 from Se-enriched microalgae biomass (Chlorella, a previously untested Se source for fish. Fish mortality, growth, Se accumulation in muscle and liver, and activity of selected enzymes in blood plasma, muscle, liver, and intestine were evaluated. There was no mortality, and no differences in fish growth, among groups. Se concentrations in muscle and liver, activity of alanine aminotransferase and creatine kinase in blood plasma, glutathione reductase (GR in muscle, and GR and catalase in muscle and liver suggested that selenium from Se-enriched Chlorella is more readily accumulated and biologically active while being less toxic than sodium selenite.

  3. 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.

  4. 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.

  5. Heavy metal accumulation potential and medicinal property of Bacopa monnieri - a paradox

    Directory of Open Access Journals (Sweden)

    Nabeesa Salim

    2011-12-01

    Full Text Available Bioaccumulation of Mercury and Cadmium in Bacopa monnieri (L. Pennell, cultivated in Hoagland medium artificially contaminated with micro quantities of HgCl2 and CdCl2 is investigated. Bioaccumulation potential of B. monnieri is more towards Cd than Hg. Absorption and translocation of Hg and Cd are proportional to the availability of the metal in the growth media and period of growth. Effect of acidic pH showed enhanced accumulation while basic pH resulted in significant reduction in the accumulation of Hg and exorbitant reduction of Cd. As a result of combined treatment of HgCl2 and CdCl2, accumulation was very low in both acidic and basic pH. In addition to pH, antagonistic effect of Ca2+ present in lime water which was added to raise the pH of the growth medium also controls the accumulation and absorption of Hg and Cd ions. Bioaccumulation of Hg and Cd in B. monnieri reveals the phytoremediation potential while the bioaccumulation is hazards to health since the plant is highly medicinal and one important ingredient of many Ayurvedic preparations.

  6. 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

  7. Protective Effects of Quercetin Against HgCl₂-Induced Nephrotoxicity in Sprague-Dawley Rats.

    Science.gov (United States)

    Shin, Yu Jin; Kim, Jeong Jun; Kim, Ye Ji; Kim, Won Hee; Park, Eun Young; Kim, In Young; Shin, Han-Seung; Kim, Kyeong Seok; Lee, Eui-Kyung; Chung, Kyu Hyuck; Lee, Byung Mu; Kim, Hyung Sik

    2015-05-01

    Mercury is a well-known environmental pollutant that can cause nephropathic diseases, including acute kidney injury (AKI). Although quercetin (QC), a natural flavonoid, has been reported to have medicinal properties, its potential protective effects against mercury-induced AKI have not been evaluated. In this study, the protective effect of QC against mercury-induced AKI was investigated using biochemical parameters, new protein-based urinary biomarkers, and a histopathological approach. A 250 mg/kg dose of QC was administered orally to Sprague-Dawley male rats for 3 days before administration of mercury chloride (HgCl2). All animals were sacrificed at 24 h after HgCl2 treatment, and biomarkers associated with nephrotoxicity were measured. Our data showed that QC absolutely prevented HgCl2-induced AKI, as indicated by biochemical parameters such as blood urea nitrogen (BUN) and serum creatinine (sCr). In particular, QC markedly decreased the accumulation of Hg in the kidney. Urinary excretion of protein-based biomarkers, including clusterin, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP-1), tissue inhibitor of metalloproteinases 1 (TIMP-1), and vascular endothelial growth factor (VEGF) in response to HgCl2 administration were significantly decreased by QC pretreatment relative to that in the HgCl2-treated group. Furthermore, urinary excretion of metallothionein and Hg were significantly elevated by QC pretreatment. Histopathological examination indicated that QC protected against HgCl2-induced proximal tubular damage in the kidney. A TUNEL assay indicated that QC pretreatment significantly reduced apoptotic cell death in the kidney. The administration of QC provided significant protective effects against mercury-induced AKI.

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

    Science.gov (United States)

    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.

  9. 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).

  10. Mercury modulates selenium activity via altering its accumulation and speciation in garlic (Allium sativum).

    Science.gov (United States)

    Zhao, Jiating; Hu, Yi; Gao, Yuxi; Li, Yufeng; Li, Bai; Dong, Yuanxing; Chai, Zhifang

    2013-06-01

    Combined pollution of selenium (Se) and mercury (Hg) has been known in Wanshan district (Guizhou Province, China). A better understanding of how Se and Hg interact in plants and the phytotoxicity thereof will provide clues about how to avoid or mitigate adverse effects of Se/Hg on local agriculture. In this study, the biological activity of Se has been investigated in garlic with or without Hg exposure. Se alone can promote garlic growth at low levels (1 mg L(-1)). The promotive effect of Se in garlic can be enhanced by low Hg exposure (<0.1 mg L(-1)). When both Se and Hg are at high levels, there is a general antagonistic effect between these two elements in terms of phytotoxicity. Inductively coupled plasma mass spectrometry (ICP-MS) data suggest that Se is mainly concentrated in garlic roots, compared to the leaves and the bulbs. Se uptake by garlic in low Se medium (<0.1 mg L(-1)) can be significantly enhanced as Hg exposure levels increase (P < 0.05), while it can be inhibited by Hg when Se exposure levels exceed 1 mg L(-1). The synchrotron radiation X-ray fluorescence (SRXRF) mapping further shows that Se is mainly concentrated in the stele of the roots, bulbs and the veins of the leaves, and Se accumulation in garlic can be reduced by Hg. The X-ray absorption near edge structure (XANES) study indicates that Se is mainly formed in C-Se-C form in garlic. Hg can decrease the content of inorganic Se mainly in SeO3(2-) form in garlic while increasing the content of organic Se mainly in C-Se-C form (MeSeCys and its derivatives). Hg-mediated changes in Se species along with reduced Se accumulation in garlic may account for the protective effect of Hg against Se phytotoxicity.

  11. [Intraductal Papillary Mucinous Neoplasm (IPMN) of the Pancreas Showing High Accumulation of 18F-Fluorodeoxyglucose (FDG)--A Case Report].

    Science.gov (United States)

    Kubota, Masaru; Nishimura, Masashige; Nakatsuka, Rie; Miyazaki, Susumu; Danno, Katsuki; Motoori, Masaaki; Matsuda, Chu; Fujitani, Kazumasa; Iwase, Kazuhiro

    2015-11-01

    The diagnosis of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas includes radiographic (CT, MRI) and endoscopic evaluation (ERCP, EUS). The treatment strategy is outlined in the 2012 International Consensus Guidelines (ICG). Herein, we report a case initially not indicated for surgery. Four months after the initial diagnosis, the cystic lesion transformed into a solid mass-like lesion visible on CT. FDG-PET showed abnormal FDG uptake at the same location. Surgical resection was performed immediately, and the tumor was diagnosed as IPMN with inflammation. FDG-PET showed a false-positive diagnosis for the malignancy in this case of IPMN.

  12. 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.

  13. External monitoring of /sup 203/Hg-labelled Dirofilaria immitis microfilariae in mice and dogs

    Energy Technology Data Exchange (ETDEWEB)

    Lengemann, F.W.; Grieve, R.B.; Chmielewicz, M.; Kallfelz, F.A.; Georgi, J.R.

    1986-04-01

    Microfilariae of Dirofilaria immitis were labelled with /sup 203/Hg/sup 2 +/ in vitro and injected into irradiated mice and Beagle dogs. With irradiated mice it was possible to demonstrate microfilariae present in the blood and to detect /sup 203/Hg by external counting as long as 28 days after dosing. The /sup 203/Hg/sup 2 +/ label had a half-time of 4-5 days; the amount of stable mercury in the labelling medium strongly influenced the survival of microfilariae in vivo. In dogs, external counting showed the lungs to be a major location of microfilariae soon after reinjection into the host. Evidence was obtained that labelled microfilariae can circulate; however, the detection of dispersed microfilariae is difficult because of the relative insensitivity of the detecting system. For radiomercury the accumulation of the inorganic form in the liver and kidneys limits the long-term usefulness of /sup 203/Hg/sup 2 +/ as a label if the organism being studied also accumulates in these organs.

  14. Effects of urbanization on mercury deposition and accumulation in New England.

    Science.gov (United States)

    Chalmers, Ann T; Krabbenhoft, David P; Van Metre, Peter C; Nilles, Mark A

    2014-09-01

    We compare total mercury (HgT) loading and methylmercury (MeHg) accumulation in streams and lakes from an urbanized area (Boston, Massachusetts) to rural regions of southern New Hampshire and Maine. The maximum HgT loading, as indicated by HgT atmospheric deposition, HgT emissions, and sediment HgT concentrations, did not coincide with maximum MeHg concentrations in fish. Urbanized ecosystems were areas of high HgT loading but had low MeHg concentrations in fish. Controls on MeHg production and accumulation appeared to be related primarily to HgT loading in undeveloped areas, while ecosystem sensitivity to MeHg formation appeared to be more important in regulating accumulation of MeHg in the urban area.

  15. The linear accumulation of atmospheric mercury by vegetable and grass leaves: Potential biomonitors for atmospheric mercury pollution.

    Science.gov (United States)

    Niu, Zhenchuan; Zhang, Xiaoshan; Wang, Sen; Ci, Zhijia; Kong, Xiangrui; Wang, Zhangwei

    2013-09-01

    One question in the use of plants as biomonitors for atmospheric mercury (Hg) is to confirm the linear relationships of Hg concentrations between air and leaves. To explore the origin of Hg in the vegetable and grass leaves, open top chambers (OTCs) experiment was conducted to study the relationships of Hg concentrations between air and leaves of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.). The influence of Hg in soil on Hg accumulation in leaves was studied simultaneously by soil Hg-enriched experiment. Hg concentrations in grass and vegetable leaves and roots were measured in both experiments. Results from OTCs experiment showed that Hg concentrations in leaves of the four species were significantly positively correlated with those in air during the growth time (p  0.05). Thus, Hg in grass leaves is mainly originated from the atmosphere, and grass leaves are more suitable as potential biomonitors for atmospheric Hg pollution. The effect detection limits (EDLs) for the leaves of alfalfa and ryegrass were 15.1 and 22.2 ng g(-1), respectively, and the biological detection limit (BDL) for alfalfa and ryegrass was 3.4 ng m(-3).

  16. Genotype and growing environment interaction shows a positive correlation between substrates of raffinose family oligosaccharides (RFO) biosynthesis and their accumulation in chickpea ( Cicer arietinum L.) seeds.

    Science.gov (United States)

    Gangola, Manu P; Khedikar, Yogendra P; Gaur, Pooran M; Båga, Monica; Chibbar, Ravindra N

    2013-05-22

    To develop genetic improvement strategies to modulate raffinose family oligosaccharides (RFO) concentration in chickpea ( Cicer arietinum L.) seeds, RFO and their precursor concentrations were analyzed in 171 chickpea genotypes from diverse geographical origins. The genotypes were grown in replicated trials over two years in the field (Patancheru, India) and in the greenhouse (Saskatoon, Canada). Analysis of variance revealed a significant impact of genotype, environment, and their interaction on RFO concentration in chickpea seeds. Total RFO concentration ranged from 1.58 to 5.31 mmol/100 g and from 2.11 to 5.83 mmol/100 g in desi and kabuli genotypes, respectively. Sucrose (0.60-3.59 g/100 g) and stachyose (0.18-2.38 g/100 g) were distinguished as the major soluble sugar and RFO, respectively. Correlation analysis revealed a significant positive correlation between substrate and product concentration in RFO biosynthesis. In chickpea seeds, raffinose, stachyose, and verbascose showed a moderate broad sense heritability (0.25-0.56), suggesting the use of a multilocation trials based approach in chickpea seed quality improvement programs.

  17. 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.

  18. A comparison of winter mercury accumulation at forested and no-canopy sites measured with different snow sampling techniques

    Science.gov (United States)

    Nelson, S.J.; Johnson, K.B.; Weathers, K.C.; Loftin, C.S.; Fernandez, I.J.; Kahl, J.S.; Krabbenhoft, D.P.

    2008-01-01

    Atmospheric mercury (Hg) is delivered to ecosystems via rain, snow, cloud/fog, and dry deposition. The importance of snow, especially snow that has passed through the forest canopy (throughfall), in delivering Hg to terrestrial ecosystems has received little attention in the literature. The snowpack is a dynamic system that links atmospheric deposition and ecosystem cycling through deposition and emission of deposited Hg. To examine the magnitude of Hg delivery via snowfall, and to illuminate processes affecting Hg flux to catchments during winter (cold season), Hg in snow in no-canopy areas and under forest canopies measured with four collection methods were compared: (1) Hg in wet precipitation as measured by the Mercury Deposition Network (MDN) for the site in Acadia National Park, Maine, USA, (2) event throughfall (collected after snowfall cessation for accumulations of >8 cm), (3) season-long throughfall collected using the same apparatus for event sampling but deployed for the entire cold season, and (4) snowpack sampling. Estimates (mean ?? SE) of Hg deposition using these methods during the 91-day cold season in 2004-2005 at conifer sites showed that season-long throughfall Hg flux (1.80 ??g/m2) Mercury deposition at the MDN site (0.91 ??g/m2) was similar to that measured at other no-canopy sites in the area using the other methods, but was 3.4 times less than was measured under conifer canopies using the event sampling regime. This indicates that snow accumulated under the forest canopy received Hg from the overstory or exhibited less re-emission of Hg deposited in snow relative to open areas. The soil surface of field-scale plots were sprayed with a natural rain water sample that contained an Hg tracer (202Hg) just prior to the first snowfall to explore whether some snowpack Hg might be explained from soil emissions. The appearance of the 202Hg tracer in the snowpack (0-64% of the total Hg mass in the snowpack) suggests that movement of Hg from the soil

  19. 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.

  20. An extended study on historical mercury accumulation in lake sediment of Shanghai: The contribution of socioeconomic driver.

    Science.gov (United States)

    Yang, Jing; Chen, Ling; Steele, Joshua Caleb; Chen, Rui-Shan; Meng, Xiang-Zhou

    2016-12-01

    Rapid industrialization and urbanization has caused large emission and potential contamination of mercury (Hg) in urban environment. However, little is known about the impact of socioeconomic factor on Hg accumulation in sediment. In the present study, historical record of anthropogenic Hg deposition of Shanghai was reconstructed by using three sediment cores from three park lakes (C1: Luxun Park; C2: Fuxing island Park; C3: Xinjiangwan Park). Meanwhile, the influence of socioeconomic factor to Hg emissions and sedimentary record was calculated based on an extended STIRPAT (stochastic impacts by regression on population, affluence and technology) model. The profiles of Hg levels and fluxes in the three sediment cores showed that Shanghai has recently undergone urbanization. The anthropogenic Hg fluxes exhibited fluctuant increases from ∼1900 to present and accelerated after the establishment of the People's Republic of China in 1949 and the implementation of reform and opening up policy in 1978. The mean flux ratios of Hg in post-2000 were 2.2, 12, and 2.7 in the C1, C2 and C3 cores, respectively. The extended STIRPAT model was constructed based on strong positive relationships between socioeconomic factors and Hg fluxes, revealing that the proportion of coal consumption, the urbanization rate, and the proportion of heavy industry were the three most important driving factors for Hg accumulations in urban sediment of Shanghai.

  1. Influence of chemical speciation and biofilm composition on mercury accumulation by freshwater biofilms.

    Science.gov (United States)

    Dranguet, P; Le Faucheur, S; Cosio, C; Slaveykova, V I

    2017-01-25

    Mercury (Hg) is a pollutant of high concern for aquatic systems due to the biomagnification of its methylated form along the food chain. However, in contrast to other metals, gaining knowledge of its bioavailable forms for aquatic microorganisms remains challenging, making Hg risk assessment difficult. Ubiquitous and sessile freshwater biofilms are well known to accumulate and to transform Hg present in their ambient environment. The present study thus aims to evaluate whether non-extractable (proxy of intracellular) Hg accumulated by biofilms could be a good indicator of Hg bioavailability for microorganisms in freshwater. To that end, the link between Hg concentration and speciation, as well as biofilm composition (percentage of abiotic, biotic, chlorophyll and phycocyanin-fractions and abundance of dsrA, gcs, merA and hgcA bacterial genes) and biofilm Hg accumulation was examined. The studied biofilms were grown on artificial substrata in four reservoirs along the Olt River (Romania), which was contaminated by Hg coming from chlor-alkali plant effluents. The 0.45 μm-filterable Hg concentrations in ambient waters were measured and inorganic IHg speciation was modelled. Biofilms were analyzed for their non-extractable IHg and methylmercury (MeHg) contents as well as for their composition. The non-extractable IHg content was related, but not significantly, to the concentration of total IHg (r(2) = 0.88, p = 0.061) whereas a significant correlation was found with the predicted IHg concentration that is not bound to dissolved organic matter (r(2) = 0.95, p = 0.027), despite its extremely low concentrations (10(-25) M), showing a limitation of the thermodynamic Hg modelling to predict Hg bioavailability. The studied biofilms were different in biomass and composition and a principal component analysis showed that the non-extractable IHg content correlated with the abundance of the merA and hgcA genes, while MeHg accumulation was only linked with the abundance of the r

  2. 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.

  3. Synchrotron-based Infrared and X-ray Imaging Shows Focalized Accumulation of Cu and Zn Co-localized With Beta-amyloid Deposits in Alzheimer's Disease

    Energy Technology Data Exchange (ETDEWEB)

    Miller,L.; Wang, Q.; Telivala, T.; Smith, R.; Lanzirotti, A.; Miklossy, J.

    2006-01-01

    Alzheimer's disease (AD) is characterized by the misfolding and plaque-like accumulation of a naturally occurring peptide in the brain called amyloid beta (Abeta). Recently, this process has been associated with the binding of metal ions such as iron (Fe), copper (Cu), and zinc (Zn). It is thought that metal dyshomeostasis is involved in protein misfolding and may lead to oxidative stress and neuronal damage. However, the exact role of the misfolded proteins and metal ions in the degenerative process of AD is not yet clear. In this study, we used synchrotron Fourier transform infrared micro-spectroscopy (FTIRM) to image the in situ secondary structure of the amyloid plaques in brain tissue of AD patients. These results were spatially correlated with metal ion accumulation in the same tissue sample using synchrotron X-ray fluorescence (SXRF) microprobe. For both techniques, a spatial resolution of 5-10 microm was achieved. FTIRM results showed that the amyloid plaques have elevated beta-sheet content, as demonstrated by a strong amide I absorbance at 1625cm(-1). Using SXRF microprobe, we find that AD tissue also contains 'hot spots' of accumulated metal ions, specifically Cu and Zn, with a strong spatial correlation between these two ions. The 'hot spots' of accumulated Zn and Cu were co-localized with beta-amyloid plaques. Thus for the first time, a strong spatial correlation has been observed between elevated beta-sheet content in Abeta plaques and accumulated Cu and Zn ions, emphasizing an association of metal ions with amyloid formation in AD.

  4. 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.

  5. Distribution of mercury in metallothionein-null mice after exposure to mercury vapor: amount of metallothionein isoform does not affect accumulation of mercury in the brain.

    Science.gov (United States)

    Yasutake, Akira; Yoshida, Minoru; Honda, Akiko; Watanabe, Chiho; Satoh, Masahiko

    2012-01-01

    To examine the contribution of metallothionein (MT) to mercury accumulation in mouse tissues, 129 strain female mice and MT null mice were exposed to metallic mercury vapor at a sub-toxic level, and Hg levels in the brain, kidney and liver were determined on 1, 3 and 7 days after the exposure. After exposure to mercury vapor, significant Hg accumulation was observed in the brains of wild-type and MT-I/II null and MT-III null mice, as well as in the liver and kidneys. No strain difference was observed in the tissue Hg accumulations 24 hr after the exposure except for the kidneys, where the highest accumulation was found in MT-III null mice. Although the brains of MT-III null mice showed slightly higher Hg accumulation than the other two strains, no significant difference was observed except in the cerebrum on Day 7. Gel chromatograms of cerebrum soluble fractions revealed that a significant amount of Hg existed as an MT-bound form in all the mouse strains. On the other hand, MT-bound Hg was found as a minor fraction in soluble fractions of the kidneys and livers in wild-type and MT-III null mice. Despite a significant strain difference in total MT levels in the cerebrum, there was no difference among the three strains in the amount of Hg accumulated in the cerebrum and its distribution rates in MT fractions. The present study demonstrated that brain uptake of Hg(0) and its accumulation as Hg(2+) did not depend on the amount of MT isoform in the tissue, at least in the early phase.

  6. 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.

  7. The lncRNA MIR31HG regulates p16(INK4A) expression to modulate senescence

    DEFF Research Database (Denmark)

    Montes Resano, Marta; Nielsen, Morten M; Maglieri, Giulia

    2015-01-01

    normal conditions, MIR31HG is found in both nucleus and cytoplasm, but following B-RAF expression MIR31HG is located mainly in the cytoplasm. We show that MIR31HG interacts with both INK4A and MIR31HG genomic regions and with Polycomb group (PcG) proteins, and that MIR31HG is required for Pc...

  8. Mercury Accumulation, Structural Damages, and Antioxidant and Immune Status Changes in the Gilthead Seabream (Sparus aurata L.) Exposed to Methylmercury.

    Science.gov (United States)

    Guardiola, F A; Chaves-Pozo, E; Espinosa, C; Romero, D; Meseguer, J; Cuesta, A; Esteban, M A

    2016-05-01

    In aquatic systems, mercury (Hg) is an environmental contaminant that causes acute and chronic damage to multiple organs. In fish, practically all of the organic Hg found is in the form of methylmercury (MeHg), which has been associated with animal and human health problems. This study evaluates the impact of waterborne-exposure to sublethal concentrations of MeHg (10 μg L(-1)) in gilthead seabream (Sparus aurata). Hg was seen to accumulate in liver and muscle, and histopathological damage to skin and liver was detected. Fish exposed to MeHg showed a decreased biological antioxidant potential and increased levels of the reactive oxygen molecules compared with the values found in control fish (nonexposed). Increased liver antioxidant enzyme activities (superoxide dismutase and catalase) were detected in 2 day-exposed fish with respect to the values of control fish. However, fish exposed to MeHg for 10 days showed liver antioxidant enzyme levels similar to those of the control fish but had increased hepato-somatic index and histopathological alterations in liver and skin. Serum complement levels were higher in fish exposed to MeHg for 30 days than in control fish. Moreover, head-kidney leukocyte activities increased, although only phagocytosis and peroxidase activities showed a significant increase after 10 and 30 days, respectively. The data show that 30 days of exposure to waterborne MeHg provokes more significant changes in fish than a short-term exposure of 2 or 10 days.

  9. 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.

  10. Differential gene expression associated with dietary methylmercury (MeHg) exposure in rainbow trout (Oncorhynchus mykiss) and zebrafish (Danio rerio)

    Science.gov (United States)

    Liu, Qing; Basu, Niladri; Goetz, Giles; Jiang, Nan; Hutz, Reinhold J.; Tonellato, Peter J.; Carvan, Michael J.

    2013-01-01

    The objective of this study was to identify and evaluate conserved biomarkers that could be used in most species of teleost fish at most life-stages. We investigated the effects of sublethal methylmercury (MeHg) exposure on developing rainbow trout and zebrafish. Juvenile rainbow trout and young adult zebrafish were fed food with MeHg added at 0, 0.5, 5 and 50 ppm. Atomic absorption spectrometry was applied to measure whole body total Hg levels, and pathologic analysis was performed to identify MeHg-induced toxicity. Fish at six weeks were sampled from each group for microarray analysis using RNA from whole fish. MeHg-exposed trout and zebrafish did not show overt signs of toxicity or pathology, nor were significant differences seen in mortality, length, mass, or condition factor. The accumulation of MeHg in trout and zebrafish exhibited dose- and time-dependent patterns during six weeks, and zebrafish exhibited greater assimilation of total Hg than rainbow trout. The dysregulated genes in MeHg-treated fish have multiple functional annotations, such as iron ion homeostasis, glutathione transferase activity, regulation of muscle contraction, troponin I binding and calcium-dependent protein binding. Genes were selected as biomarker candidates based on their microarray data and their expression was evaluated by QPCR. Unfortunately, these genes are not good consistent biomarkers for both rainbow trout and zebrafish from QPCR evaluation using individual fish. Our conclusion is that biomarker analysis for aquatic toxicant assessment using fish needs to be based on tissue-, sex- and species-specific consideration. PMID:23529582

  11. 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)

  12. Total mercury and methyl-mercury contents and accumulation in polar microbial mats.

    Science.gov (United States)

    Camacho, Antonio; Rochera, Carlos; Hennebelle, Raphaëlle; Ferrari, Christophe; Quesada, Antonio

    2015-03-15

    Although polar regions are considered isolated and pristine areas, the organisms that inhabit these zones are exposed to global pollution. Heavy metals, such as mercury, are global pollutants and can reach almost any location on Earth. Mercury may come from natural, volcanic or geological sources, or result from anthropogenic sources, in particular industrial or mining activities. In this study, we have investigated one of the most prominent biological non-marine communities in both polar regions, microbial mats, in terms of their Hg and methyl-mercury (MeHg) concentrations and accumulation capacities. The main hypotheses posed argued on the importance of different factors, and to test them, we have measured Hg concentrations in microbial mats that were collected from 6 locations in different ecological situations. For this purpose, the direct anthropogenic impacts, volcanic influences, proximity to the seashore, latitudinal gradients and C contents were investigated. Our results show that, other than the direct anthropogenic influence, none of the other hypotheses alone satisfactorily explains the Hg content in microbial mats. In contrast, the MeHg contents were noticeably different between the investigated locations, with a higher proportion of MeHg on the McMurdo Ice Shelf (Antarctica) and a lower proportion on Ward Hunt Island (High Arctic). Furthermore, our results from in situ experiments indicated that the microbial mats from South Shetland Islands could quickly accumulate (48 h) Hg when Hg dissolved salts were supplied. Over short-term periods, these mats do not transform Hg into MeHg under field conditions.

  13. 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.

  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. Accumulation and evaluation of heavy metals Cu, Cd and Hg in prey species of juvenile Chinese sturgeons (Acipenser Sinensis) in the Yangtze River estuary, China%长江口中华鲟幼鱼主要饵料生物体内重金属Cu、Cd和Hg的积累与评价

    Institute of Scientific and Technical Information of China (English)

    张慧婷; 庄平; 章龙珍; 侯俊利; 张涛; 闫文罡; 冯广朋

    2011-01-01

    In order to discuss the different biological absorption of Gu, Cd and Hg, and evaluate them in food organisms for juvenile Acipenser Sinensis in Yangtze estuary, Macrobraohium nipponense, Acetes chinensis,Taenioides rubicundus, Chaeturichthys stigrnatias and Cynoglossus gracilis were collected and analyzed.Results showed that, individual pollution index (Pi) of Gu in shrimps was less than 0.5, Pi of Cu in fish was more than 0.5, and Pi of Cd and Hg in all selected prey species were more than 1. This indicated that the 5 selected prey species for juvenile Acipenser Sinensis were all contaminated by heavy metals to different extent.The shrimps were contaminated more seriouslly than fish. Compared with the historical data, the heavy metal pollution of fish in Yangtze estuary showed aggravating trend. Heavy metal pollution has been threatening juvenile Chinese sturgeon which migrate to sea via Yangtze estuary.%为评价重金属污染对长江口中华鲟幼鱼生长的影响,在长江口水域采集了日本沼虾(Macrobraohium nipponense)、中国毛虾(Acetes chinensis)、狼牙鳗虾虎鱼(Taenioides rubicundus)、矛尾虾虎鱼(Chaeturichthys stigmatias)、窄体舌鳎(Cynoglossus gracilis)等5种中华鲟幼鱼重要饵料生物,研究了Cu、Cd、Hg3种重金属元素在这些饵料生物体内的积累特征,评价了饵料生物受重金属污染的程度.结果显示,虾类Cu的单项污染指数(P)均大于0.5,鱼类Cu的P均小于0.5;5种饵料生物Cd和Hg的P均大于1.表明它们均不同程度受到重金属污染,虾类的重金属污染程度比鱼类严重.与历史资料比较发现,长江口鱼虾的重金属污染存在加重趋势,重金属污染已对洄游人海的中华鲟幼鱼构成威胁.

  16. Historical atmospheric mercury emissions and depositions in North America compared to mercury accumulations in sedimentary records

    Science.gov (United States)

    Pirrone, Nicola; Allegrini, Ivo; Keeler, Gerald J.; Nriagu, Jerome O.; Rossmann, Ronald; Robbins, John A.

    Gold and silver production in North America (included United States, Canada and Mexico) released a large amount of mercury to the atmosphere until well into this century when mercury (Hg) amalgamation was replaced by cyanide concentration. Since then, emissions from industries have been the dominant anthropogenic sources of atmospheric Hg in North America as a whole. Past Hg emissions from gold and silver extractions in North America during the 1800s do not show a clear evidence of atmospheric deposition occurred at the coring sites considered in this study. Estimated atmospheric emissions of Hg in North America peaked in 1879 (at about 1708 t yr -1) and 1920 (at about 940 t yr -1), primarily due to Hg emissions from gold and silver mining. After the Great Economic Depression (1929) Hg emissions peaked again in the 1947 (274 t yr -1), in 1970 (325 t yr -1) and in 1989 (330 t yr -1) as result of increased Hg emissions from industrial sources, though improvements in the emissions control technology in United States and Canada have been substantial. Estimates of total atmospheric deposition fluxes of Hg to water and terrestrial receptors were in the range of 14.3-19.8 μg m -2 yr -1 in North America as a whole, and averaged 135 μg m -2 yr -1 (global background + local emissions) in the Great Lakes. These values were in good agreement with recent estimates reported in literature. The comparison of atmospheric Hg deposition fluxes with Hg accumulation rates in sediment cores suggests that atmospheric deposition was the major source of Hg entering the lakes system at coring sites, however, important contributions to Lake Ontario sediment cores sites from 1940 to 1970 were likely originated from local point sources (i.e. direct discharges).

  17. Mercury accumulation and tissue-specific antioxidant efficiency in the wild European sea bass (Dicentrarchus labrax) with emphasis on seasonality.

    Science.gov (United States)

    Mieiro, C L; Dolbeth, M; Marques, T A; Duarte, A C; Pereira, M E; Pacheco, M

    2014-09-01

    The main goal of this study was to assess both mercury (Hg) accumulation and organs' specific oxidative stress responses of gills, liver and kidney of Dicentrarchus labrax with emphasis on seasonality. Fish were collected in cold and warm periods in three stations: reference, moderated and highly contaminated sites. Our results showed that seasonal factors slightly influenced Hg accumulation between year periods (cold and warm) and strongly affected organs' response basal levels. In contrast, seasonality seemed not to influence oxidative stress responses, since similar response patterns were obtained for both year periods, and moderate degree of antioxidant responses was obtained. Moreover, the oxidative stress profile may be attributed to Hg contamination degree, which showed organ-specific response and accumulation patterns. Hence, gills showed to be able to adapt to Hg contamination, and in opposition, kidney and liver demonstrated some vulnerability to Hg toxicity. The critical Hg concentrations indicated specific threshold limits for each organ. Overall, seasonality should be taken into account in monitoring programmes, helping to characterize the individuals' reference values of response and thus to discriminate between the effects induced by natural causes or by contamination.

  18. Effect of Hg, As and Pb on biomass production, photosynthetic rate, nutrients uptake and phytochelatin induction in Pfaffia glomerata.

    Science.gov (United States)

    Gupta, D K; Huang, H G; Nicoloso, F T; Schetinger, M R; Farias, J G; Li, T Q; Razafindrabe, B H N; Aryal, N; Inouhe, M

    2013-11-01

    Plantlets of Pfaffia glomerata (Spreng.) were exposed for 28 days to three different metal/metalloid (Hg, Pb and As) with different levels (Hg 1; As 25, 50, 100 and Pb 100 and 400 μM) to analyze the possible phytochelatin initiation and affects on growth and photosynthetic pigments vis-à-vis metal accumulation potential of plants. The plantlets showed significant Hg, As and Pb accumulation in roots (150, 1267.67 and 2129 μg g(-1) DW respectively); however, a low root to shoot metal translocation was observed. It was interesting to note that all tested macronutrient (Mg, K, Ca) was higher in shoots and just opposite in case of micronutrients (Cu, Fe, Zn), was recorded highest in roots. The growth of plantlets (analyzed in terms of length and dry weight) was negatively affected by various metal treatments. In addition, the level of photosynthetic pigments alters significantly in response to all metal/metalloid treatment. In response to all tested metal/metalloids in plants only As induced phytochelatins (PC2, PC3 and PC4) in roots, and in shoots, GSH was observed in all tested metal/metalloids. In conclusion, P. glomerata plantlets could not cooperatively induce phytochelatins under any of Hg and Pb levels.

  19. Study of atomic structure of liquid Hg-In alloys using ab-initio molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Nalini; Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University, Shimla(HP)-171005 (India); Thakur, Anil [Department of Physics, Govt. P. G. College Solan (HP)-173212 (India)

    2015-05-15

    Ab-initio molecular dynamics simulations are performed to study the structural properties of liquid Hg-In alloys. The interatomic interactions are described by ab-initio pseudopotentials given by Troullier and Martins. Five liquid Hg-In mixtures (Hg{sub 10}In{sub 90}, Hg{sub 30}In{sub 70}, Hg{sub 50}In{sub 50}, Hg{sub 70}In{sub 30} and Hg{sub 90}In{sub 10}) at 299K are considered. The radial distribution function g(r) and structure factor S(q) of considered alloys are compared with respective experimental results for liquid Hg (l-Hg) and (l-In). The radial distribution function g(r) shows the presence of short range order in the systems considered. Smooth curves of Bhatia-Thornton partial structure factors factor shows the presence of liquid state in the considered alloys.

  20. Formation of PdHg by reaction of palladium thin film contacts deposited onto mercuric iodide ({alpha}-HgI{sub 2}) radiation detector crystals

    Energy Technology Data Exchange (ETDEWEB)

    Medlin, D.L. [Sandia National Labs., Livermore, CA (United States); Van Scyoc, J.M. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Gilbert, T.S. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Schlesinger, T.E. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Boehme, D. [Sandia National Labs., Livermore, CA (United States); Schieber, M. [Sandia National Labs., Livermore, CA (United States); Natarajan, M. [TN Technologies, Inc., Round Rock, TX (United States); James, R.B. [Sandia National Labs., Livermore, CA (United States)

    1996-10-01

    The microstructure and phase distribution of palladium thin films sputter deposited onto {alpha}-HgI{sub 2} for use as electrical contacts in radiation detectors are investigated using electron microscopy. Our results show a limited reaction to form palladium mercuride (PdHg). It is shown that the formation of PdHg via several reaction pathways is thermodynamically feasible. (orig.).

  1. Comparison of the characteristics and mechanisms of Hg(II) sorption by biochars and activated carbon.

    Science.gov (United States)

    Xu, Xiaoyun; Schierz, Ariette; Xu, Nan; Cao, Xinde

    2016-02-01

    Two biochars were produced from bagasse and hickory chips (referred to as BB and HCB, respectively) and evaluated for their sorption ability of Hg(II) in aqueous solution. A commercial activated carbon (AC) which is commonly used for Hg(II) removal was included for comparison. Both biochars showed higher sorption capacities than AC, following the trend of BB>HCB>AC. The sorption of Hg(II) by BB and AC was mainly attributed to the formation of (COO)2Hg(II) and (O)2Hg(II). As a result, the adsorption capacity of Hg(II) by BB decreased 17.6% and 37.6% after COOH and OH were blocked, respectively and that of Hg(II) by AC decreased 6.63% and 62.2% for COOH and OH hindered, respectively. However, blocking the function groups had little effect on the Hg removal by HCB since sorption of Hg(II) by HCB was mainly resulted from the π electrons of CC and CO induced Hg-π binding. Further X-ray photoelectron spectroscopy analysis indicated the possibility of reduction of the Hg(II) to Hg(I) by phenol groups or π electrons during the removal of Hg(II) by both biochars. In conclusion, biochar is more effective than activated carbon in removing Hg(II) and there exists a high potential that biochar can be a substitute of activated carbon for removal of Hg(II) from wastewater.

  2. Accumulation of Heavy Metals in Crayfish and Fish from Selected Czech Reservoirs

    Directory of Open Access Journals (Sweden)

    Iryna Kuklina

    2014-01-01

    Full Text Available To evaluate the accumulation of aluminium, cadmium, chromium, copper, lead, mercury, nickel, and zinc in crayfish and fish organ tissues, specimens from three drinking water reservoirs (Boskovice, Landštejn, and Nová Říše and one contaminated site (Darkovské moře in the Czech Republic were examined. Crayfish hepatopancreas was confirmed to be the primary accumulating site for the majority of metals (Cu > Zn > Ni > Cd > Cr, while Hg and Cr were concentrated in abdominal muscle, and Al and Pb were concentrated in gill. Metals found in Nová Říše specimens included Cu > Zn > Ni and those found in Boskovice included Zn > Hg > Cr. Cd concentrations were observed only in Landštejn specimens, while contaminated Darkovské moře specimens showed the highest levels of accumulation (Cu > Al > Zn > Pb. The majority of evaluated metals were found in higher concentrations in crayfish: Cu > Al > Zn > Ni > Cr > Cd > Pb, with Hg being the only metal accumulating higher in fish. Due to accumulation similarities of Al in crayfish and fish gill, differences of Hg in muscle, and features noted for the remaining metals in examined tissues, biomonitoring should incorporate both crayfish and fish to produce more relevant water quality surveys.

  3. Mercury accumulation in largemouth bass (Micropterus salmoides Lacépède) within marsh ecosystems of the Florida Everglades, USA.

    Science.gov (United States)

    Julian, Paul; Gu, Binhe

    2015-01-01

    This study evaluates factors, particularly water quality related, that may influence mercury (Hg) bioaccumulation in largemouth bass (LMB, Micropterus salmoides Lacépède) within the Everglades marshes of South Florida. The investigation is an empirical analysis of ambient data from both long-term fish monitoring and marsh water quality monitoring sites across the Everglades Protection Area. Previous Hg studies of Everglade's marsh biota have focused on the role that sulfate plays in Hg bioaccumulation. While sulfate can be important under some environmental conditions, this empirical analysis in Everglades marshes showed that sulfate has little association with Hg concentrations in LMB. It is suggested that other water quality variables including water pH, alkalinity and specific conductance may have as much or more influence in the accumulation of Hg in LMB. Furthermore, tissue Hg concentration normalized to body-weight and age-specific growth rates were significantly correlated with Water Conservation Area (WCA)-1, WCA-2 and Everglades National Park (ENP) but not WCA-3. However, body condition was correlated negatively with Hg concentration only within WCA-2, WCA-3 and ENP; the relationship was not significant within WCA-1. This disparity between Hg concentration and body condition could be attributed to ecological effects including water quality and quantity conditions within each compartment of the system that are significant driving forces for biota abundance, trophic structure and distribution within the Everglades ecosystem. While water quality and quantity are important, trophic position of LMB has the potential to influence Hg accumulation dynamics. In spite of documented biogeochemical linkages to Hg accumulation, this empirical analysis did not demonstrate enough quantitative interaction to be useful for Hg management in the Everglades ecosystem.

  4. HPV16 and 18 genome amplification show different E4-dependence, with 16E4 enhancing E1 nuclear accumulation and replicative efficiency via its cell cycle arrest and kinase activation functions

    Science.gov (United States)

    Jackson, Deborah; Mahmood, Radma

    2017-01-01

    To clarify E1^E4’s role during high-risk HPV infection, the E4 proteins of HPV16 and 18 were compared side by side using an isogenic keratinocyte differentiation model. While no effect on cell proliferation or viral genome copy number was observed during the early phase of either virus life cycle, time-course experiments showed that viral genome amplification and L1 expression were differently affected upon differentiation, with HPV16 showing a much clearer E4 dependency. Although E4 loss never completely abolished genome amplification, its more obvious contribution in HPV16 focused our efforts on 16E4. As previously suggested, in the context of the virus life cycle, 16E4s G2-arrest capability was found to contribute to both genome amplification success and L1 accumulation. Loss of 16E4 also lead to a reduced maintenance of ERK, JNK and p38MAPK activity throughout the genome amplifying cell layers, with 16E4 (but not 18E4) co-localizing precisely with activated cytoplasmic JNK in both wild type raft tissue, and HPV16-induced patient biopsy tissue. When 16E1 was co-expressed with E4, as occurs during genome amplification in vivo, the E1 replication helicase accumulated preferentially in the nucleus, and in transient replication assays, E4 stimulated viral genome amplification. Interestingly, a 16E1 mutant deficient in its regulatory phosphorylation sites no longer accumulated in the nucleus following E4 co-expression. E4-mediated stabilisation of 16E2 was also apparent, with E2 levels declining in organotypic raft culture when 16E4 was absent. These results suggest that 16E4-mediated enhancement of genome amplification involves its cell cycle inhibition and cellular kinase activation functions, with E4 modifying the activity and function of viral replication proteins including E1. These activities of 16E4, and the different kinase patterns seen here with HPV18, 31 and 45, may reflect natural differences in the biology and tropisms of these viruses, as well as

  5. Thiazole derivative-modified upconversion nanoparticles for Hg2+ detection in living cells

    Science.gov (United States)

    Gu, Bin; Zhou, Yi; Zhang, Xiao; Liu, Xiaowang; Zhang, Yuhai; Marks, Robert; Zhang, Hua; Liu, Xiaogang; Zhang, Qichun

    2015-12-01

    Mercury ion (Hg2+) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg2+ in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg2+ in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by confocal microscopy. Our results demonstrated that organic-dye-functionalized UCNPs should be a good strategy for detecting toxic metal ions when studying cellular biosystems.Mercury ion (Hg2+) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg2+ in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg2+ in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Accumulation of heavy metals in the fish, Oreochromis niloticus and Poecilia latipinna and their concentration in water and sediment of dam lake of Wadi Namar, Saudi Arabia.

    Science.gov (United States)

    Ahmad, Zubair; Al-Ghanim, Khalid A; Al-Balawi, Hmoud F Al-Kahem; Al-Misned, Fahad; Maboob, Shahid; Suliman, El-Amin M

    2015-01-01

    The present study reports the accumulation of heavy metals like Cu, Hg, Cd, Pb and Cr in different tissues viz. liver, kidney, gills and muscles of Oreochromisniloticus and Poecilia latipinna from two sites in dam lake of Wadi Namar. Water and sediment samples were also collected from two sites for heavy metal analysis. Metal concentration in water and sediment samples of both the sites were observed in the following order: Cu>Cr>Pb>Cd>Hg; however, their concentration was found to be more at site 2 as compared to site 1. The order of metal accumulation in different tissues of O. niloticus and P. latipinna was in the following order: Cu>Cr>Pb>Cd>Hg at both the sites, while liver accumulated maximum amounts of metals followed by kidney, gills and muscles. The results showed the site 2 was more polluted by metals than Site 1 and O. niloticus accumulated greater amount of metals than P. latipinna.

  11. 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.

  12. 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.

  13. Fish eyes and brain as primary targets for mercury accumulation - a new insight on environmental risk assessment.

    Science.gov (United States)

    Pereira, Patrícia; Raimundo, Joana; Araújo, Olinda; Canário, João; Almeida, Armando; Pacheco, Mário

    2014-10-01

    Fish eyes and brain are highly susceptible to environmental Hg exposure but this issue is still scarcely investigated, mainly regarding methylmercury (MeHg) accumulation. Yet, Hg levels in fish lens have not been previously examined under field conditions. Total Hg (tHg), MeHg and inorganic Hg (iHg) levels were assessed in the brain, eye wall and lens of the golden grey mullet (Liza aurata) from an Hg contaminated area, both in winter and summer, together with water and sediment levels. Sampling was performed at Aveiro lagoon (Portugal) where a confined area (LAR) is severely contaminated by Hg. Fish brain, eye wall and lens accumulated higher levels of tHg, MeHg and iHg at LAR than the reference site, reflecting faithfully environmental spatial differences. The brain and eye wall responded also to the winter-summer changes found in water and sediment, accumulating higher levels of MeHg (and tHg) in winter. Contrarily, lens was unable to reflect seasonal changes, probably due to its composition and structural stability over time. The three neurosensory structures accumulated preferentially MeHg than iHg (MeHg was higher than 77% of tHg). Lens exhibited a higher retention capacity of MeHg (mean around 1 μg g(-1) at LAR), accumulating higher levels than the other two tissues. Interestingly, MeHg and iHg levels were significantly correlated for the brain and eye wall but poorly associated within the two analysed eye components. The high levels of MeHg found in the brain, eye wall and lens could compromise their functions and this needs further research.

  14. Body burden of Hg in different bio-samples of mothers in Shenyang city, China.

    Directory of Open Access Journals (Sweden)

    Min-Ming Li

    Full Text Available Hg is an accumulative and neuro-toxic heavy metal which has a wide range of adverse effects in human health. However, few studies are available on body burden of Hg level in different bio-samples of pregnant women in Chinese population. Therefore, this study evaluated Hg levels in different maternal bio-samples in Shenyang city, China and investigated the correlation of Hg levels in different bio-samples. From October to December 2008, 200 pregnant women about to deliver their babies at ShengJing Hospital (Shenyang city, northeast of China participated in this study. The geometric mean (GM of Hg levels in cord blood, maternal venous blood, breast milk, and maternal urine were 2.18 µg/L, 1.17 µg/L, 1.14 µg/L, and 0.73 µg/L, respectively, and the GM of maternal hair Hg level was 404.45 µg/kg. There was a strong correlation between cord blood and maternal blood total Hg level (r = 0.713, P<0.001. Frequency of fish consumption more than or equal to 3 times per week during pregnancy was suggested as a significant risk factor of prenatal Hg exposure (unadjusted OR 3.5, adjusted OR 2.94, P<0.05. This study provides evidence about Hg burden of mothers and the risk factors of prenatal Hg exposure in Shenyang city, China.

  15. 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.

  16. Acumulación de mercurio (Hg por caña flecha (Gynerium sagittatum (Aubl Beauv. in vitro

    Directory of Open Access Journals (Sweden)

    Rafael Esteban Ortega-Ortega

    2011-04-01

    (p ≤ 0.05 to establish significant differences between the treatments, tests of normality (Kolmogorov-Smirnov and homogeneity test Bartlett variance. The mercury analyses were performed on atomic absorption spectrophotometer Thermo Electron S4, a cell equipped with quartz windows, by the method of atomic absorption spectrometry with cold steam. The results show that the plant part that presents the greatest accumulation is the root with 55.98 mg g-1 HgT, followed by the stems, leaves 14.84 g g-1 HgT and these values ​​are related to the degree of metal concentration in the culture medium. Furthermore, the accumulation of mercury in roots and stems increased with time. In conclusion, in vitro this plant accumulates due to the high Hg concentrations in their tissues without affecting the viability of plants.Key words: Phytoremediation, removal, heavy metals.

  17. 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).

  18. 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).

  19. Prevention of La3+ on DNA Damage Caused by Hg2+ from Fish Intestines

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The aim of this study was to investigate the effects of rare earth elements (REEs) in preventing Hg2+ pollution, using fish intestinal DNA in vitro and study the mechanism of the interactions between Hg2+, La3+, the mixture of La3+ and Hg2+ and DNA by spectroscopy. The interactions between Hg2+, La3+, the mixture of La3+ and Hg2+ and DNA from fish intestine in vitro was investigate by using absorption spectrum and fluorescence emission spectrum. Ultraviolet absorption spectra indicated that the addition of Hg2+, La3+, and the mixture of La3+ and Hg2+ to DNA generated obvious hypochromic effect. Meanwhile, the 205.2 nm peak of DNA blue and the 258.2 nm peak of DNA red shifted. The hypochromic effect and peak shift was caused by these ions in an order of Hg2+>Hg2++La3+>La3+. The fluorescence emission spectra showed that as the addition of Hg2+, La3+, and the mixture of La3+ and Hg2+, the emission peak at about 416.2 nm of DNA did not obviously change, but the fluorescence intensity reduced gradually with the order in treatment was Hg2+>Hg2+ + La3+>La3+. Hg2+, La3+, and the mixture of La3+ and Hg2+ had 1.12, 0.58, and 0.81 binding sites to DNA, the fluorescence quenching of DNA caused by them all attributed to static quenching. The binding constants KA of binding sites were 3.82×104 and 4.22×102 L·mol-1;2.50×104 and 2.95×103 L·mol-1;3.05×104 and 1.00×103 L·mol-1. The results showed that La3+ could relieve destruction caused by Hg2+ on the DNA structure.

  20. Metallothionein expression in chloroplasts enhances mercury accumulation and phytoremediation capability.

    Science.gov (United States)

    Ruiz, Oscar N; Alvarez, Derry; Torres, Cesar; Roman, Laura; Daniell, Henry

    2011-06-01

    Genetic engineering to enhance mercury phytoremediation has been accomplished by expression of the merAB genes that protects the cell by converting Hg[II] into Hg[0] which volatilizes from the cell. A drawback of this approach is that toxic Hg is released back into the environment. A better phytoremediation strategy would be to accumulate mercury inside plants for subsequent retrieval. We report here the development of a transplastomic approach to express the mouse metallothionein gene (mt1) and accumulate mercury in high concentrations within plant cells. Real-time PCR analysis showed that up to 1284 copies of the mt1 gene were found per cell when compared with 1326 copies of the 16S rrn gene, thereby attaining homoplasmy. Past studies in chloroplast transformation used qualitative Southern blots to evaluate indirectly transgene copy number, whereas we used real-time PCR for the first time to establish homoplasmy and estimate transgene copy number and transcript levels. The mt1 transcript levels were very high with 183,000 copies per ng of RNA or 41% the abundance of the 16S rrn transcripts. The transplastomic lines were resistant up to 20 μm mercury and maintained high chlorophyll content and biomass. Although the transgenic plants accumulated high concentrations of mercury in all tissues, leaves accumulated up to 106 ng, indicating active phytoremediation and translocation of mercury. Such accumulation of mercury in plant tissues facilitates proper disposal or recycling. This study reports, for the first time, the use of metallothioneins in plants for mercury phytoremediation. Chloroplast genetic engineering approach is useful to express metal-scavenging proteins for phytoremediation.

  1. Biochar amendment reduced methylmercury accumulation in rice plants

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Rui; Wang, Yongjie [School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People’s Republic of China (China); Zhong, Huan, E-mail: zhonghuan@nju.edu.cn [School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People’s Republic of China (China); Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario (Canada)

    2016-08-05

    Highlights: • Biochar amendment could evidently reduce methylmercury (MeHg) levels in rice grain. • Biochar could enhance microbial production of MeHg, probably by providing sulfate. • Biochar could immobilize MeHg in soil, and reduce MeHg availability to rice plants. • Biochar amendment increased grain biomass, leading to biodilution of MeHg in grain. - Abstract: There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1–4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49–92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35–79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment.

  2. 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 ...

  3. 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.

  4. 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.

  5. 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.

  6. Influence of sulfur on the accumulation of mercury in rice plant (Oryza sativa L.) growing in mercury contaminated soils.

    Science.gov (United States)

    Li, Yunyun; Zhao, Jiating; Guo, Jingxia; Liu, Mengjiao; Xu, Qinlei; Li, Hong; Li, Yu-Feng; Zheng, Lei; Zhang, Zhiyong; Gao, Yuxi

    2017-09-01

    Sulfur (S) is an essential element for plant growth and its biogeochemical cycling is strongly linked to the species of heavy metals in soil. In this work, the effects of S (sulfate and elemental sulfur) treatment on the accumulation, distribution and chemical forms of Hg in rice growing in Hg contaminated soil were investigated. It was found that S could promote the formation of iron plaque on the root surface and decrease total mercury (T-Hg) and methylmercury (MeHg) accumulation in rice grains, straw, and roots. Hg in the root was dominated in the form of RS-Hg-SR. Sulfate treatment increased the percentage of RS-Hg-SR to T-Hg in the rice root and changed the Hg species in soil. The dominant Hg species (70%) in soil was organic substance bound fractions. Sulfur treatment decreased Hg motility in the rhizosphere soils by promoting the conversion of RS-Hg-SR to HgS. This study is significant since it suggests that low dose sulfur treatment in Hg-containing water irrigated soil can decrease both T-Hg and MeHg accumulation in rice via inactivating Hg in the soil and promoting the formation of iron plaque in rice root, which may reduce health risk for people consuming those crops. Copyright © 2017. Published by Elsevier Ltd.

  7. Show Time

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正> Story: Show Time!The whole class presents the story"Under the Sea".Everyone is so excited and happy.Both Leo and Kathy show their parentsthe characters of the play."Who’s he?"asks Kathy’s mom."He’s the prince."Kathy replies."Who’s she?"asks Leo’s dad."She’s the queen."Leo replieswith a smile.

  8. Snobbish Show

    Institute of Scientific and Technical Information of China (English)

    YIN PUMIN

    2010-01-01

    @@ The State Administration of Radio,Film and Television (SARFT),China's media watchdog,issued a new set of mles on June 9 that strictly regulate TV match-making shows,which have been sweeping the country's primetime programming. "Improper social and love values such as money worship should not be presented in these shows.Humiliation,verbal attacks and sex-implied vulgar content are not allowed" the new roles said.

  9. 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.

  10. The IDH2 R172K mutation associated with angioimmunoblastic T-cell lymphoma produces 2HG in T cells and impacts lymphoid development

    Science.gov (United States)

    Lemonnier, François; Cairns, Rob A.; Inoue, Satoshi; Li, Wanda Y.; Dupuy, Aurélie; Broutin, Sophie; Martin, Nadine; Fataccioli, Virginie; Pelletier, Romain; Wakeham, Andrew; Snow, Bryan E.; de Leval, Laurence; Pujals, Anais; Haioun, Corinne; Paci, Angelo; Tobin, Erica R.; Narayanaswamy, Rohini; Yen, Katherine; Jin, Shengfang; Gaulard, Philippe; Mak, Tak W.

    2016-01-01

    Oncogenic isocitrate dehydrogenase (IDH)1 and IDH2 mutations at three hotspot arginine residues cause an enzymatic gain of function that leads to the production and accumulation of the metabolite 2-hydroxyglutarate (2HG), which contributes to the development of a number of malignancies. In the hematopoietic system, mutations in IDH1 at arginine (R) 132 and in IDH2 at R140 and R172 are commonly observed in acute myeloid leukemia, and elevated 2HG is observed in cells and serum. However, in angioimmunoblastic T-cell lymphoma (AITL), mutations are almost exclusively restricted to IDH2 R172, and levels of 2HG have not been comprehensively measured. In this study, we investigate the expression pattern of mutant IDH2 in the AITL tumor microenvironment and measure levels of 2HG in tissue and serum of AITL patients. We find that mutant IDH2 expression is restricted to the malignant T-cell component of AITL, and that 2HG is elevated in tumor tissue and serum of patients. We also investigate the differences between the three hotspot mutation sites in IDH1 and IDH2 using conditional knock-in mouse models. These studies show that in the lymphoid system, mutations in IDH2 at R172 produce high levels of 2HG compared with mutations at the other two sites and that lymphoid development is impaired in these animals. These data provide evidence that IDH2 R172 mutations may be the only variants present in AITL because of their capacity to produce significant amounts of the oncometabolite 2HG in the cell of origin of this disease. PMID:27956631

  11. EROBATIC SHOW

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    Visitors look at plane models of the Commercial Aircraft Corp. of China, developer of the count,s first homegrown large passenger jet C919, during the Singapore Airshow on February 16. The biennial event is the largest airshow in Asia and one of the most important aviation and defense shows worldwide. A number of Chinese companies took part in the event during which Okay Airways, the first privately owned aidine in China, signed a deal to acquire 12 Boeing 737 jets.

  12. Accumulation, sources and health risks of trace metals in elevated geochemical background soils used for greenhouse vegetable production in southwestern China.

    Science.gov (United States)

    Zhang, Haidong; Huang, Biao; Dong, Linlin; Hu, Wenyou; Akhtar, Mohammad Saleem; Qu, Mingkai

    2017-03-01

    Greenhouse vegetable cultivation with substantive manure and fertilizer input on soils with an elevated geochemical background can accumulate trace metals in soils and plants leading to human health risks. Studies on trace metal accumulation over a land use shift duration in an elevated geochemical background scenario are lacking. Accumulation characteristics of seven trace metals in greenhouse soil and edible plants were evaluated along with an assessment of the health risk to the consumers. A total of 118 greenhouse surface soils (0-20cm) and 30 vegetables were collected from Kunming City, Yunnan Province, southwestern China, and analyzed for total Cd, Pb, Cu, Zn, As, Hg, and Cr content by ICP-MS and AFS. The trace metals were ordered Cu>Cd>Hg>Zn>Pb>As>Cr in greenhouse soils accumulation level, and the geo-accumulation index suggested the soil more severely polluted with Cd, Cu, Hg and Zn. The greenhouse and open-field soils had significant difference in Cd, Cr and Zn. The duration of shift from paddy to greenhouse land-use significantly influenced trace metal accumulation with a dramatic change during five to ten year greenhouse land-use, and continuous increase of Cd and Hg. A spatial pattern from north to south for Cd and Hg and a zonal pattern for Cu and Zn were found. An anthropogenic source primarily caused trace metal accumulation, where the principal component analysis/multiple linear regression indicated a contribution 61.2%. While the assessment showed no potential risk for children and adults, the hazard health risks index was greater than one for adolescents. The extended duration of land use as greenhouses caused the trace metal accumulation, rotation in land use should be promoted to reduce the health risks. Copyright © 2016. Published by Elsevier Inc.

  13. Differential patterns of accumulation and retention of dietary trace elements associated with coal ash during larval development and metamorphosis of an amphibian.

    Science.gov (United States)

    Heyes, Andrew; Rowe, Christopher L; Conrad, Phillip

    2014-01-01

    We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at "low" and "high" concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements.

  14. 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.

  15. 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

  16. Stability studies of Hg implanted YBa$_{2}$Cu$_{3}$O$_{6+x}$

    CERN Document Server

    Araújo, J P; Wahl, U; Marques, J G; Alves, E; Amaral, V S; Lourenço, A A; Galindo, V; Von Papen, T; Senateur, J P; Weiss, F; Vantomme, A; Langouche, G; Melo, A A; Da Silva, M F A; Soares, J C; Sousa, J B

    1999-01-01

    High quality YBa$_{2}$Cu$_{3}$O$_{6+x}$ (YBCO) superconducting thin films were implanted with the radioactive $^{197m}$Hg (T$_{1/2}$ = 24 h) isotope to low fluences of 10$^{13}$ atoms/cm$^{2}$ and 60 keV energy. The lattice location and stability of the implanted Hg were studied combining the Perturbed Angular Correlation (PAC) and Emission Channeling (EC) techniques. We show that Hg can be introduced into the YBCO lattice by ion implantation into unique regular sites. The EC data show that Hg is located on a highly symmetric site on the YBCO lattice, while the PAC data suggests that Hg occupies the Cu(1) site. Annealing studies were performed under vacuum and O$_{2}$ atmosphere and show that Hg starts to diffuse only above 653 K.

  17. The redox processes in Hg-contaminated soils from Descoberto (Minas Gerais, Brazil): implications for the mercury cycle.

    Science.gov (United States)

    Windmöller, Cláudia C; Durão Júnior, Walter A; de Oliveira, Aline; do Valle, Cláudia M

    2015-02-01

    Investigations of the redox process and chemical speciation of Hg(II) lead to a better understanding of biogeochemical processes controlling the transformation of Hg(II) into toxic and bioaccumulative monomethyl mercury, mainly in areas contaminated with Hg(0). This study investigates the speciation and redox processes of Hg in soil samples from a small area contaminated with Hg(0) as a result of gold mining activities in the rural municipality of Descoberto (Minas Gerais, Brazil). Soil samples were prepared by adding Hg(0) and HgCl2 separately to dry soil, and the Hg redox process was monitored using thermodesorption coupled to atomic absorption spectrometry. A portion of the Hg(0) added was volatilized (up to 37.4±2.0%) or oxidized (from 36±7% to 88±16%). A correlation with Mn suggests that this oxidation is favored, but many other factors must be evaluated, such as the presence of microorganisms and the types of organic matter present. The interaction of Hg with the matrix is suggested to involve Hg(II)-complexes formed with inorganic and organic sulfur ligands and/or nonspecific adsorption onto oxides of Fe, Al and/or Mn. The kinetics of the oxidation reaction was approximated for two first-order reactions; the faster reaction was attributed to the oxidation of Hg(0)/Hg(I), and the slower reaction corresponded to Hg(I)/Hg(II). The second stage was 43-139 times slower than the first. The samples spiked with Hg(II) showed low volatilization and a shifting of the signal of Hg(II) to lower temperatures. These results show that the extent, rate and type of redox process can be adverse in soils. Descoberto can serve as an example for areas contaminated with Hg(0).

  18. Selection of mercury accumulator plants for gold mine tailing contaminated soils

    Directory of Open Access Journals (Sweden)

    N Muddarisna

    2015-04-01

    Full Text Available Phytoremediation, which is more efficient with less side effects than conventional physical and chemical methods, is increasing in popularity as a remediation system. This paper provides a brief overview of developments in research and application of phytoremediation of soil contaminated with gold mine tailings containing mercury. Lindernia crustacea L., Digitaria radicosa Presl. Miq., Zingiber purpurium L, Paspalum conjugatum Berg., Cyperus kyllingia Endl., and Caladium bicolor Vent., that were selected for this study were planted in the planting media consisting of soil (70% and tailings (30% for 9 weeks. The results showed that after 9 weeks of planting, Paspalum conjugatum had growth rate, biomass production, Hg accumulation, and ratio of shoot Hg : root Hg higher than those of other plant species tested, both in the media consisted of amalgamation and cyanidation tailings. It can thus be concluded that Paspalum conjugatum is potential plant species for remediating mercury-contaminated soil.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. 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

  1. 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.

  2. Methylmercury production and accumulation in urban stormwater ponds and habitat wetlands.

    Science.gov (United States)

    Strickman, R J; Mitchell, C P J

    2017-02-01

    Stormwater management ponds and created habitat wetlands effectively manage erosion, flooding, and pollutant loadings while providing biodiversity and aesthetic benefits, but these structures are also potential sources of methylmercury (MeHg), a bioaccumulative neurotoxin. While MeHg accumulation has been confirmed in habitat wetlands, the extent of MeHg production and accumulation in stormwater ponds is unknown. Additionally, the fine-scale spatial variation in MeHg in these wetlands has never been explored despite the possibility that cycles of wetting and drying, and the presence of aquatic plants may stimulate methylation at their margins. To address these knowledge gaps, we compared MeHg and inorganic mercury concentrations, the percent of total mercury present as MeHg (%MeHg), and potential mercury methylation rate constants (Kmeth) in the sediments of terrestrial-aquatic transects through several stormwater and habitat wetlands. We present novel evidence confirming the in situ production of MeHg in both stormwater ponds and habitat wetlands, but observe no systematic differences across the terrestrial-aquatic gradient, suggesting that routine variations in water level do not alter MeHg production and accumulation. Stormwater ponds effectively trap mercury while converting relatively little to MeHg, as evidenced by lower MeHg concentrations, %-MeHg, and Kmeth values than habitat wetlands, but often greater inorganic Hg concentrations. The relationship of aquatic vegetation to MeHg accumulation is weak and ambiguous, suggesting plants are not strong drivers of MeHg biogeochemistry in these systems. Although the MeHg hazard associated with individual artificial wetlands is low, they may be important sources of MeHg at the landscape level. Copyright © 2016 Elsevier Ltd. All rights reserved.

  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. 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.

  5. 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

  6. 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.

  7. In vivo formation of natural HgSe nanoparticles in the liver and brain of pilot whales

    Science.gov (United States)

    To understand the biochemistry of methylmercury (MeHg) that leads to the formation of mercury-selenium (Hg-Se) clusters is a long outstanding challenge that promises to deepen our knowledge of MeHg detoxification and the role SE plays in this process. Here, we show that mercury ...

  8. In vivo formation of natural HgSe nanoparticles in the liver and brain of pilot whales

    Science.gov (United States)

    To understand the biochemistry of methylmercury (MeHg) that leads to the formation of mercury-selenium (Hg-Se) clusters is a long outstanding challenge that promises to deepen our knowledge of MeHg detoxification and the role SE plays in this process. Here, we show that mercury ...

  9. Comparison of intermittent and continuous exposures to inorganic mercury in the mussel, Mytilus edulis: accumulation and sub-lethal physiological effects.

    Science.gov (United States)

    Amachree, Dokuboba; Moody, A John; Handy, Richard D

    2014-11-01

    Aquatic organisms are often subject to intermittent exposure to pollutants in real ecosystems. This study aimed to compare mercury accumulation and the physiological responses of mussels, Mytilus edulis during continuous and intermittent exposure to the metal. Mussels were treated in a semi-static, triplicated design to either a control (no added Hg) or 50 µg l(-1) Hg as HgCl2 in continuous (daily) or intermittent (2 day exposure, 2 days in clean seawater alternately) exposure for 14 days. A time-dependent increase in Hg accumulation was observed in the continuous exposure, while the intermittent treatment showed step-wise changes in Hg concentrations with the exposure profile, especially in the gills. At the end of the experiment, tissue Hg concentrations were significantly increased in the continuous compared to the intermittent exposure for digestive gland (4 fold), gonad and remaining soft tissue (>2 fold), but not for the gill and adductor muscle. There was no observed oxidative damage at the end of the experiment as measured by the thiobarbituric acid reactive substances (TBARS) concentrations in tissues from all treatments. However, total glutathione was significantly decreased in the gill and digestive gland of both the continuous and intermittent exposure by the end of the experiment. The neutral red retention ability of the haemocytes was not affected, but total haemocyte counts were significantly decreased (<2 fold) in the intermittent compared to the continuous exposure. Histopathological examinations showed less pathology in the gill, but more inflammation in the digestive gland of mussels for the intermittent compared to the continuous exposure. Overall, the results showed that Hg accumulation from intermittent exposure was less than that of the continuous exposure regime, but the sub-lethal responses are sometimes more severe than expected in the former.

  10. 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.

  11. Accumulation, transfer, and environmental risk of soil mercury in a rapidly industrializing region of the Yangtze River Delta, China

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Biao; Yan, Lianxiang; Sun, Weixia; Zhao, Yongcun; Shi, Xuezheng [Chinese Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture; Wang, Mei [Chinese Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture; Graduate Univ. of the Chinese Academy of Sciences, Beijing (China); Weindorf, David C. [Louisiana State Univ., Baton Rouge, LA (United States). AgCenter

    2011-06-15

    Purpose: Mercury (Hg) accumulation and transfer in soil ecosystems has been altered on local, regional, and even global scales, and their environmental risk has increasingly been a concern to the public and the scientific community. Materials and methods: A county level region in Zhangjiagang County, the Yangtze River Delta (YRD) region of China and a factory with Hg-contaminated wastewater discharging within the region were selected to study the accumulation, bioavailability, and transfer of Hg from different sources in soils and crops under rapid industrialization, urbanization, and intensive agricultural activities. Regional soil samples close to and away from factories and local soil and crop samples around a typical factory were collected in the YRD region of China. Soil and crop Hg and basic soil properties were examined. Results and discussion: Significant soil Hg accumulation was found in soils away from factories regardless of Cambosols (Entisols) and Anthrosols (Inceptisols), while the mobile HCl-extractable Hg (HCl-Hg) were greater in soils closer to factories due to a decrease and increase in soil pH and organic matter. A high level of soil total Hg (T-Hg) was found around the factory, and soil and crop Hg accumulation in the vicinity of the factory was localized with an exponential decrease as distance away from the wastewater discharge outlet increased. Although Hg accumulated in these soils, the T-Hg levels at only a few sampling sites in acidic Anthrosols area were found to exceed the second most stringent critical value of Chinese Environmental Quality Standards for Soils. Conclusions: Considering the cessation of Hg-containing agrochemicals and limitation of effects of industrial activities on Hg accumulation, more attention should be paid to the changes in soil properties and crop rotations than controlling the pathways of Hg entering soils because the current environmental risk is mobilization of accumulated soil Hg. (orig.)

  12. 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.

  13. 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

  14. Dissolution, absorption and bioaccumulation in gastrointestinal tract of mercury in HgS-containing traditional medicines Cinnabar and Zuotai%含HgS传统药物朱砂和佐太中汞的胃肠道溶出及吸收蓄积研究

    Institute of Scientific and Technical Information of China (English)

    郑植元; 李岑; 张明; 杨红霞; 耿卢婧; 李林帅; 杜玉枝; 魏立新

    2015-01-01

    .Meanwhile,a group of mice was given α-Hg,S and β-HgS with the equivalent mercury with cinnabar,while another group was given β-HgS and HgCl2 with the equivalent mercury with Zuotai.The mercury absorption and bioaccumulation capacities of different medicines in mice and their mercury bioaccumulation in different tissues and organs were compared.The experimental results showed a high mercury dissolutions of Zuotai in artificial gastrointestinal fluid,which was followed byβ-HgS,cinnabar and α-HgS.As for the mercury absorption and bioaccumulation in mice,HgCl2 was the highest,β-HgS was the next,and α-HgS was slightly higher than cinnabar.The organs with the mercury bioaccumulation from high to low were kidney,liver and brain.This study is close to chnical practices and can provide reference for the clinical safe medication as well as a study model for the safety evaluation on heavy metal-containing medicines by observing the mercury dissolution,absorption,distribution and accumulation of mercury-containing medicines cinnabar and zuotai.

  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. A 6,000-years record of atmospheric mercury accumulation in the high Arctic from peat deposits on Bathurst Island, Nunavut, Canada

    DEFF Research Database (Denmark)

    Givelet, N.; Roos-Barraclough, F.; Goodsite, M. E.

    2003-01-01

    There is a growing interest in the atmospheric transport, deposition, and accumulation of anthropogenic Hg in the Arctic. To quantify the impact of industrial Hg emissions, the natural rate of atmospheric Hg accumulation must be known. Mercury concentration measurements and age dating of peat fro...

  17. MBE - growth of capped, strained HgTe, a 3D topological insulator

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Christopher; Leubner, Philipp; Bruene, Christoph; Buhmann, Hartmut; Molenkamp, Laurens [Universitaet Wuerzburg, D-97074 Wuerzburg (Germany)

    2013-07-01

    The discovery of two (2D) and three dimensional (3D) topological insulator (TI) behavior in HgTe - systems opens a large field for studying magneto transport properties of both. We grow HgTe as a 3D topological insulator by molecular beam epitaxy. Unstrained bulk HgTe is a semimetal but opens a gap of roughly 22 meV when grown fully strained on <001> CdTe substrate due to 0.3 % lattice mismatch and shows magnetotransport properties of a 3D TI. Hall measurements show electron mobilities of around 50.000 cm{sup 2}(V s){sup -1}. To increase electron mobilities, various growth optimizations have been carried out. Firstly we grew an HgCdTe buffer layer between the substrate and bulk HgTe. Different buffer thicknesses were analyzed ex-situ by HRXRD, AFM and standard Hall measurements. Secondly, we added a cap-layer of HgCdTe on top of the bulk HgTe. Doing so, we were able to raise the electron mobility of the bulk HgTe up to one order of magnitude. Time-dependent XPS measurements allowed us to hold the suppressed oxidization of the surface responsible for this effect. Through the advanced material quality we have now more prospects for better understanding of the transport properties in strained HgTe.

  18. Accumulation and distribution of mercury in fruiting bodies by fungus Suillus luteus foraged in Poland, Belarus and Sweden.

    Science.gov (United States)

    Saba, Martyna; Falandysz, Jerzy; Nnorom, Innocent C

    2016-02-01

    Presented in this paper is result of the study of the bioconcentration potential of mercury (Hg) by Suillus luteus mushroom collected from regions within Central, Eastern, and Northern regions of Europe. As determined by cold-vapor atomic absorption spectroscopy, the Hg content varied from 0.13 ± 0.05 to 0.33 ± 0.13 mg kg(-1) dry matter for caps and from 0.038 ± 0.014 to 0.095 ± 0.038 mg kg(-1) dry matter in stems. The Hg content of the soil substratum (0-10 cm layer) underneath the fruiting bodies showed generally low Hg concentrations that varied widely ranging from 0.0030 to 0.15 mg kg(-1) dry matter with mean values varying from 0.0078 ± 0.0035 to 0.053 ± 0.025 mg kg(-1) dry matter, which is below typical content in the Earth crust. The caps were observed to be on the richer in Hg than the stems at ratio between 1.8 ± 0.4 and 5.3 ± 2.6. The S. luteus mushroom showed moderate ability to accumulate Hg with bioconcentration factor (BCF) values ranging from 3.6 ± 1.3 to 42 ± 18. The consumption of fresh S. luteus mushroom in quantities up to 300 g week(-1) (assuming no Hg ingestion from other foods) from background areas in the Central, Eastern, and Northern part of Europe will not result in the intake of Hg exceeds the provisional weekly tolerance limit (PTWI) of 0.004 mg kg(-1) body mass.

  19. Mercury induced the Accumulation of Amyloid Beta (Aβ) in PC12 Cells: The Role of Production and Degradation of Aβ

    OpenAIRE

    Song, Ji-Won; Choi, Byung-Sun

    2013-01-01

    Extracellular accumulation of amyloid beta protein (Aβ) plays a central role in Alzheimer’s disease (AD). Some metals, such as copper, lead, and aluminum can affect the Aβ accumulation in the brain. However, the effect of mercury on Aβ accumulation in the brain is not clear. Thus, this study was proposed to estimate whether mercury concentration affects Aβ accumulation in PC12 cells. We treated 10, 100, and 1000 nM HgCl2 (Hg) or CH3HgCl2 (MeHg) for 48 hr in PC12 cells. After treatment, Aβ40 i...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Novel methodology for the study of mercury methylation and reduction in sediments and water using 197Hg radiotracer.

    Science.gov (United States)

    Ribeiro Guevara, Sergio; Zizek, Suzana; Repinc, Urska; Pérez Catán, Soledad; Jaćimović, Radojko; Horvat, Milena

    2007-03-01

    Mercury tracers are powerful tools that can be used to study mercury transformations in environmental systems, particularly mercury methylation, demethylation and reduction in sediments and water. However, mercury transformation studies using tracers can be subject to error, especially when used to assess methylation potential. The organic mercury extracted can be as low as 0.01% of the endogenous labeled mercury, and artefacts and contamination present during methylmercury (MeHg) extraction processes can cause interference. Solvent extraction methods based on the use of either KBr/H2SO4 or HCl were evaluated in freshwater sediments using 197Hg radiotracer. Values obtained for the 197Hg tracer in the organic phase were up to 25-fold higher when HCl was used, which is due to the coextraction of 197Hg2+ into the organic phase during MeHg extraction. Evaluations of the production of MeHg gave similar results with both MeHg extraction procedures, but due to the higher Hg2+ contamination of the controls, the uncertainty in the determination was higher when HCl was used. The Hg2+ contamination of controls in the HCl extraction method showed a nonlinear correlation with the humic acid content of sediment pore water. Therefore, use of the KBr/H2SO4 method is recommended, since it is free from these interferences. 197Hg radiotracer (T1/2=2.673 d) has a production rate that is about 50 times higher than that of 203Hg (T1/2=46.595 d), the most frequently used mercury radiotracer. Hence it is possible to obtain a similar level of performance to 203Hg when it is used it in short-term experiments and produced by the irradiation of 196Hg with thermal neutrons, using mercury targets with the natural isotopic composition. However, if the 0.15% natural abundance of the 196Hg isotope is increased, the specific activity of the 197Hg tracer can be significantly improved. In the present work, 197Hg tracer was produced from mercury 51.58% enriched in the 196Hg isotope, and a 340-fold

  5. 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...

  6. 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.

  7. Effects of salinity and humic acid on the sorption of Hg on Fe and Mn hydroxides.

    Science.gov (United States)

    Liang, Peng; Li, Yi-Chun; Zhang, Chan; Wu, Sheng-Chun; Cui, Hao-Jie; Yu, Shen; Wong, Ming H

    2013-01-15

    The objective of this study was to investigate the influence of humic acid (HA) and salinity on adsorption of Hg on the amorphous and crystalline of iron and manganese hydroxides. The results show that the adsorption of Hg(2+) on Fe and Mn hydroxides was inhibited in marine system due to the formation of stable, nonsorbing aqueous HgCl(2) complexes in solution. Moreover, Cl(-) inhibited the Hg(2+) adsorption more severely on amorphous than crystalline hydroxides. The addition of HA inhibited Hg(2+) adsorption on Fe and Mn hydroxides in freshwater system might be attributed to the competition between Hg(2+) and HA on adsorption to Fe and Mn hydroxides. In contrast, the addition of HA promoted Hg(2+) adsorption on Fe and Mn hydroxides in the marine system, which might be due to the addition of humic acid resulted in the reaction between Cl(-) and HA, and therefore the reducing of Cl(-) promoted more Hg(2+) on Fe and Mn hydroxides. In addition, the influence of HA on Hg(2+) adsorption on Fe and Mn hydroxides are more visible for crystalline than amorphous hydroxides.

  8. 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.

  9. Sources and cycling of mercury in the paleo Arctic Ocean from Hg stable isotope variations in Eocene and Quaternary sediments

    Science.gov (United States)

    Gleason, J. D.; Blum, J. D.; Moore, T. C.; Polyak, L.; Jakobsson, M.; Meyers, P. A.; Biswas, A.

    2017-01-01

    Mercury stable isotopic compositions were determined for marine sediments from eight locations in the Arctic Ocean Basin. Mass dependent fractionation (MDF) and mass independent fractionation (MIF) of Hg stable isotopes were recorded across a variety of depositional environments, water depths, and stratigraphic ages. δ202Hg (MDF) ranges from -2.34‰ to -0.78‰; Δ199Hg (MIF) from -0.18‰ to +0.12‰; and Δ201Hg (MIF) from -0.29‰ to +0.05‰ for the complete data set (n = 33). Holocene sediments from the Chukchi Sea and Morris Jesup Rise record the most negative Δ199Hg values, while Pleistocene sediments from the Central Arctic Ocean record the most positive Δ199Hg values. The most negative δ202Hg values are recorded in Pleistocene sediments. Eocene sediments (Lomonosov Ridge) show some overlap in their Hg isotopic compositions with Quaternary sediments, with a sample of the Arctic Ocean PETM (56 Ma) most closely matching the average Hg isotopic composition of Holocene Arctic marine sediments. Collectively, these data support a terrestrially-dominated Hg source input for Arctic Ocean sediment through time, although other sources, as well as influences of sea ice, atmospheric mercury depletion events (AMDEs), and anthropogenic Hg (in core top samples) on Hg isotopic signatures must also be considered.

  10. Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)

    Science.gov (United States)

    Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

    2002-01-01

    Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.

  11. Hg(0) Removal Using Se(0)-doped Montmorillonite from Selenite(IV)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jooyoup [Univ. of Cincinnati, Ohio (United States); Kim, Yongjin [Korea Institute of Industrial Technology, Chonan (Korea, Republic of)

    2013-12-15

    Potassium methylselenite (KSeO{sub 2}(OCH{sub 3})) was reduced to elemental selenium, Se(0), and then doped onto montmorillonite K 10 (MK10) clay to examine the interaction between elemental mercury (Hg(0)) vapor and Se(0) in an effort to understand the possible heterogeneous reaction of Hg(0) vapor and Se(0) solid. The clay was used as a cost-effective support material for uniform dispersion of Se(0). The Se(0)-doped MK10 showed an excellent reaction performance with Hg(0) under an inert nitrogen gas at 70 and 140 .deg. C in our lab-scale fixed-bed system. However, the precursor, KSeO{sub 2}(OCH{sub 3})-doped MK10 showed a negligible reaction performance with Hg(0), suggesting that the oxidation state of selenium plays a key role in the reaction of Hg(0) vapor and selenium compounds.

  12. Growth and characterization of HgI2, PbI2 and PbI2:HgI2 layered semiconductors

    Directory of Open Access Journals (Sweden)

    Manoel E.R.

    1999-01-01

    Full Text Available This paper presents a methodology for the preparation of a-HgI2 by Physical Vapor Transport and of PbI2 crystals using the Bridgman technique. The results of the growth of HgI2 diluted in PbI2 by the Bridgman technique are shown for the first time, its limit of solubility having been determined at 600 ppm of HgI2 in the PbI2 matrix. Optical absorption, photoluminescence and electrical conductivity measurements show that the crystals prepared are of good crystalline quality.

  13. 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...

  14. 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.

  15. 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.

  16. The influence of Parachlorella beyerinckii CK-5 on the absorption and excretion of methylmercury (MeHg) in mice.

    Science.gov (United States)

    Uchikawa, Takuya; Yasutake, Akira; Kumamoto, Yoshimitsu; Maruyama, Isao; Kumamoto, Shoichiro; Ando, Yotaro

    2010-02-01

    Chlorella (Parachlorella beyerinckii CK-5), previously identified as Chlorella vulgaris CK-5, is a unicellular green algae that has for many years been used as a nutritional supplement. In order to investigate the effects of methylmercury (MeHg) detoxification by Chlorella, we examined the absorption and excretion of MeHg in mice. Female C57BL/6N mice were randomly divided into three groups of five, and were housed in metabolism cages. Mice were orally administered MeHg chloride at doses of 5 mg (4 mg Hg)/kg body weight with or without 100 mg/mouse of P. beyerinckii powder (BP), and were assigned to either a MeHg group or MeHg + BP group, accordingly. Twenty-four hr after oral administration, feces and urine were collected, and blood, liver, and kidney samples were obtained. Total mercury contents in the samples obtained were determined using an atomic absorption method. The amounts of Hg excreted in feces and urine of the MeHg + BP group were increased nearly 1.9 and 2.2-fold compared with those of the MeHg group. On the other hand, blood and organ Hg levels were not significantly different between two groups. These results suggest that the intake of BP may induce the excretion of Hg both in feces and urine, although it does not affect MeHg absorption from the gastrointestinal tract. The effect of BP on the tissue mercury accumulation may become evident in a long-term experiment.

  17. Accumulation, subcellular distribution and toxicity of inorganic mercury and methylmercury in marine phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yun [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

    We examined the accumulation, subcellular distribution, and toxicity of Hg(II) and MeHg in three marine phytoplankton (the diatom Thalassiosira pseudonana, the green alga Chlorella autotrophica, and the flagellate Isochrysis galbana). For MeHg, the inter-species toxic difference could be best interpreted by the total cellular or intracellular accumulation. For Hg(II), both I. galbana and T. pseudonana exhibited similar sensitivity, but they each accumulated a different level of Hg(II). A higher percentage of Hg(II) was bound to the cellular debris fraction in T. pseudonana than in I. galbana, implying that the cellular debris may play an important role in Hg(II) detoxification. Furthermore, heat-stable proteins were a major binding pool for MeHg, while the cellular debris was an important binding pool for Hg(II). Elucidating the different subcellular fates of Hg(II) and MeHg may help us understand their toxicity in marine phytoplankton at the bottom of aquatic food chains. - Highlights: > The inter-species toxic difference of methylmercury in marine phytoplankton can be explained by its total cellular or intracellular accumulation. > The inter-species toxic difference of inorganic mercury in marine phytoplankton can be explained by its subcellular distribution. > Heat-stable protein was a major binding pool for MeHg, while the cellular debris was an important binding pool for Hg(II). - The inter-species difference in methylmercury and inorganic mercury toxicity in phytoplankton can be explained by cellular accumulation and subcellular distribution.

  18. "Reactive" optical sensor for Hg(2+) and its application in environmental aqueous media and biological systems.

    Science.gov (United States)

    Chen, Zhi; Chen, Jiayun; Pan, Dong; Li, Hongwei; Yao, Yunhui; Lyu, Zu; Yang, Liting; Ma, Li-Jun

    2017-03-01

    A new rhodamine B-based "reactive" optical sensor (1) for Hg(2+) was synthesized. Sensor 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg(2+) over 14 other metal ions with a hypersensitivity (detection limits are 27.6 nM (5.5 ppb) and 6.9 nM (1.4 ppb), respectively) in neutral buffer solution. To test its applicability in the environment, sensor 1 was applied to quantify and visualize low levels of Hg(2+) in tap water and river water samples. The results indicate sensor 1 is a highly sensitive fluorescent sensor for Hg(2+) with a detection limit of 1.7 ppb in tap water and river water. Moreover, sensor 1 is a convenient visualizing sensor for low levels of Hg(2+) (0.1 ppm) in water environment (from colorless to light pink). In addition, sensor 1 shows good potential as a fluorescent visualizing sensor for Hg(2+) in fetal bovine serum and living 293T cells. The results indicate that sensor 1 shows good potential as a highly sensitive sensor for the detection of Hg(2+) in environmental and biological samples. Graphical Abstract A new rhodamine B-based "reactive" optical sensor (1) for Hg(2+) was synthesized. 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg(2+) over 14 other metal ions with a hypersensitivity in water environment. And it is a convenient visualizing probe for low levels of Hg(2+) in environment aqueous media, fetal bovine serum and living 293T cells.

  19. Dissolved organic matter reduces algal accumulation of methylmercury

    Science.gov (United States)

    Luengen, Allison C.; Fisher, Nicholas S.; Bergamaschi, Brian A.

    2012-01-01

    Dissolved organic matter (DOM) significantly decreased accumulation of methylmercury (MeHg) by the diatom Cyclotella meneghiniana in laboratory experiments. Live diatom cells accumulated two to four times more MeHg than dead cells, indicating that accumulation may be partially an energy-requiring process. Methylmercury enrichment in diatoms relative to ambient water was measured by a volume concentration factor (VCF). Without added DOM, the maximum VCF was 32 x 104, and the average VCF (from 10 to 72 h) over all experiments was 12.6 x 104. At very low (1.5 mg/L) added DOM, VCFs dropped by approximately half. At very high (20 mg/L) added DOM, VCFs dropped 10-fold. Presumably, MeHg was bound to a variety of reduced sulfur sites on the DOM, making it unavailable for uptake. Diatoms accumulated significantly more MeHg when exposed to transphilic DOM extracts than hydrophobic ones. However, algal lysate, a labile type of DOM created by resuspending a marine diatom in freshwater, behaved similarly to a refractory DOM isolate from San Francisco Bay. Addition of 67 μM L-cysteine resulted in the largest drop in VCFs, to 0.28 x 104. Although the DOM composition influenced the availability of MeHg to some extent, total DOM concentration was the most important factor in determining algal bioaccumulation of MeHg.

  20. In vivo formation of natural HgSe nanoparticles in the liver and ...

    Science.gov (United States)

    To understand the biochemistry of methylmercury (MeHg) that leads to the formation of mercury-selenium (Hg-Se) clusters is a long outstanding challenge that promises to deepen our knowledge of MeHg detoxification and the role SE plays in this process. Here, we show that mercury selenide (HgSe) nanoparticles in the liver and brain of long-finned pilot whales are attached to Se-rich structures and possibly act as a nucleation point for the formation of large Se-Hg clusters, which can grow with age to over 5 µm in size. The detoxification mechanism is fully developed from the early age of the animals, with particulate Hg found already in juvenile tissues. As a consequence of MeHg detoxification, Se-methionine, the selenium pool in the system is depleted in the efforts to maintain essential levels of Se-cysteine. This study provides evidence of so far unreported depletion of bioavailable Se pool, a plausible driving mechanism of demonstrated neurotoxic effects of MeHg in the organism affected by its high dietary intake. We investigated in vivo formation of natural HgSe particles in a pod of stranded long-finned pilot whales (Globicephala melas), with age of the animal and the potency of the environmentally relevant dose of dietary MeHg to disrupt the Se-proteins synthesis. This has been previously investigated despite the substantial indications of the interaction between Hg and Se, and therefore we conducted a multi-method analytical approach on brain and liv

  1. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    Science.gov (United States)

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom.

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. 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...

  7. Magnetically recoverable fluorescence chemosensor for the adsorption and selective detection of Hg2+ in water.

    Science.gov (United States)

    Lv, Qiang; Li, Gang; Cheng, Zhuhong; Lu, Hong; Gao, Xiaoxia

    2014-01-01

    In order to conveniently and effectively detect the heavy metal ion Hg(2+) existing in water, a magnetic fluorescence chemosensor has been strategically prepared by immobilizing a Rhodamine B derivative RhB-tris(2-aminoethyl)amine on Fe3O4@SiO2-Au@PSiO2 composites via gold particles. The adsorption and detection for Hg(2+) ions were investigated with fluorophotometry. This chemosensor shows high sensitivity and high selectivity for Hg(2+) over other metal cations owing to the ring opening of the rhodamine fluorophore selectively induced by Hg(2+). In addition, the presence of Fe3O4 in the sensor also facilitates the magnetic separation of the Fe3O4@SiO2-Au-Hg(2+)@PSiO2 from the solution.

  8. 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.

  9. Influence of Ga and Hg on microstructure and electrochemical corrosion behavior of Mg alloy anode materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effects of Hg and Ga on the electrochemical corrosion behavior of Mg-5%Hg (molar fraction) alloys were investigated by the measurement of polarization curves and galvanostatic test. The microstructure of the alloys and the corroded surface of the specimens were investigated by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. It can be concluded that the addition of 1%Ga (molar fraction) reduces corrosion current density from 26.98 mA/cm2 to 2.34 mA/cm2;while the addition of 1%Hg (molar fraction) increases corrosion current density. The addition of Ga and Hg both promotes the electrochemical activity of the alloys and the influence of Ga is more effective than Hg. Mg-5%Hg-1%Ga alloy has the best electrochemical activity, showing mean potential of-1.992 V. The activation mechanism of the magnesium alloy produced by Hg and Ga was put forward. Magnesium atoms are dissolved in liquid Hg and Ga to form amalgam and undergo severe oxidation at the amalgam/electrolyte interface.

  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. Accumulation of mercury by aufwuchs in Wisconsin seepage lakes: Implications for monitoring

    Science.gov (United States)

    Cope, W. Gregory; Rada, Ronald G.

    1992-01-01

    We examined temporal variation in the total Hg content of aufwuchs (attached algae) collected from artificial substrates in 11 seepage lakes in north-central Wisconsin and its relation to the Hg content of resident yellow perch Perca flavescens from the lakes. Dry weight concentrations of Hg in aufwuchs varied temporally, as follows: summer/fall 1985 > summer 1985 > spring/summer 1986. Areal concentrations of Hg during the 1985 sampling periods were greater than concentrations during the spring/summer 1986 period, but did not differ from each other. The analyses of aufwuchs do not indicate potential accumulation of Hg in fish in these lakes.

  12. 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...

  13. 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

  14. 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.

  15. 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...

  16. Toxic metal dispersion in mining areas: from point source to diffusion pollution. The case of the Mt. Amiata Hg mining district (Southern Tuscany - Italy): new results.

    Science.gov (United States)

    Colica, Antonella; Chiarantini, Laura; Rimondi, Valentina; Benvenuti, Marco; Costagliola, Pilario; Lattanzi, Pierfranco; Paolieri, Mario; Rinaldi, Massimo

    2016-04-01

    Rivers draining mining areas may contribute to the diffusion of contaminants through their dispersion and accumulation into different morphological river units. The Paglia River's catchment (southern Tuscany) hosts the SE portion of the Mt. Amiata mercury district, the third most important worldwide (exploited from 1880 to 1980 with a total production of 100,000 tonnes Hg) before becoming a tributary of the Tiber River, which directly flows into Mediterranean Sea. The goals of this study are: 1) to recognize and distinguish different morphological units along the Paglia River watercourse, 2) to determine spatial/temporal distribution and concentration of Hg (and other toxic elements, particularly As) in different units. The analysis of morphological units was made by mapping their evolution from the beginning of mining activity (1883) to present day along 43 km of the Paglia watercourse defining eleven morphological sections across this river, and one across one of its tributaries, the Siele Creek, which drains various Hg mines located upstream. Four fundamental morphological/sedimentary unit types have been distinguished: stream sediments, bar, floodplain, and terraces. The latter occur in various orders and age: Pleistocenic, pre-mining (i.e., dating before 1880), and coeval to the mining activity. A total of 100 samples were taken from the various units in the selected transects, georeferenced and then analyzed for their Hg and As contents by ICP-OES. Arsenic contents generally never exceed 10 mg/kg. The observed ranges are: stream sediments 4.1÷8.2 mg/kg; bars 4.1÷6.6 mg/kg; floodplains 3.8÷6.6 mg/kg; terrace coeval with mining activity 3.2÷10.1 mg/kg. Hg contents in present-day stream sediments and bars are extremely variable (0.2÷27.5 and 1.4÷22.4 mg/kg respectively), and show a sharp increase at the confluence with Siele Creek. Floodplain sediments may reach up to 98 mg/kg. Terraces coeval with mining activity also show variable Hg contents (0.1÷66

  17. 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...

  18. Screening of chelating ligands to enhance mercury accumulation from historically mercury-contaminated soils for phytoextraction.

    Science.gov (United States)

    Wang, Jianxu; Xia, Jicheng; Feng, Xinbin

    2017-01-15

    ligand for phytoextraction due to its great potential to enhance Hg accumulation in plants while decreasing bioavailable Hg concentration in the soil.

  19. 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.

  20. Control of Mercury Accumulation And Mobility in a Forest Soil as Indicated by δ13C

    Science.gov (United States)

    Bajracharya, U.; Jackson, B.; Feng, X.

    2015-12-01

    Mobility and cycling of mercury (Hg) in soils is important. Hg leaching results in its transport to wetlands, where Hg methylates and bioaccumulates through aquatic food webs. It has been shown that Hg cycle in soil is controlled by organic matter (OM) quantity as well as quality. The latter is indicated by increase of Hg/C ratio as C/N decreases by decomposition. Here we investigate the Hg-C relationship in a temperate forest soil in Hanover, NH, with a focus of examining the control of OM quality on soil Hg accumulation and mobility. We use δ13C as an indicator of carbon quality. The soil samples from A, B and C horizons were separated into six particle size fractionations from <25 µm to 1 mm. Both the bulk soil and particle size separates were analyzed for Hg concentrations, carbon content (C%), δ13C, and Hg partition coefficient (Kd =mg gSoil-1/mg Lsolution-1). We found that the bulk Hg concentration decreases significantly with increasing δ13C (R2=0.90, p <0.0001), but Hg/C increases with δ13C (R2=0.59, p =0.009). Both Hg/C and δ13C increase with soil depth, and at a given horizon, they both increase with decreasing particle size. These results indicate that high Hg/C ratios are associated with aged, decomposed, and low quality OM. Mostly likely, this accumulation of Hg in older OM is a result of retention of Hg upon carbon loss during soil respiration. However, the relationship between particle size and Hg/C is significantly different among different horizons; the most prominent relationship occurs at the deepest C horizon. This cross effect of horizon and particle size cannot be explained by normal aging of the OM through decomposition, pointing to mechanisms of changing in Hg bonding characteristics with OM aging or particle aggregation. The measured Kd value decreased with increasing δ13C (R2=0.43, p =0.0031), indicating that Hg associated with older OM is more subject to leaching compared to younger, fresher OM. This association can also be

  1. Excitation spectra and ground-state properties from density functional theory for the inverted band-structure systems $\\beta$-HgS, HgSe, and HgTe

    CERN Document Server

    Delin, A

    2002-01-01

    We have performed a systematic density-functional study of the mercury chalcogenide compounds $\\beta$-HgS, HgSe, and HgTe using an all-electron full-potential linear muffin-tin orbital (FP-LMTO) method. We find that, in the zinc-blende structure, both HgSe and HgTe are semimetals whereas $\\beta$-HgS has a small spin-orbit induced band gap. Our calculated relativistic photoemission and inverse photoemission spectra (PES and IPES, respectively) reproduce very well the most recently measured spectra, as do also our theoretical optical spectra. In contrast to the normal situation, we find that the local density approximation (LDA) to the density functional gives calculated equilibrium volumes in much better agreement with experiment than does the generalized gradient corrected functional (GGA). We also address the problem of treating relativistic $p$ electrons with methods based on a scalar-relativistic basis set, and show that the effect is rather small for the present systems.

  2. Mercury accumulation and metallothionein expression from aquafeeds by Litopenaeus vannamei Boone, 1931 under intensive aquaculture conditions.

    Science.gov (United States)

    Soares, T M; Coutinho, D A; Lacerda, L D; Moraes, M O; Rebelo, M F

    2011-02-01

    This study describes the accumulation of Hg and metallothionein gene expression in Litopenaeus vannamei Boone, 1931 with aquafeeds as the major source of Hg. Trials were conducted under controlled conditions in experimental tank facilities with high (indoor tanks) and low (outdoor tanks) Hg aquafeeds concentrations. Aquafeeds were the sole source of Hg for the shrimps and concentrations varied from 5.4 to 124 ng.g-1 d.w.. In the three animal fractions analysed; muscle (6,3 - 15,9 ng.g-1); hepatopancreas (5,1 - 22,0 ng.g-1) and exoskeleton (3,0 - 16,2 ng.g-1), Hg concentrations were significantly lower in the outdoor trials submitted to Hg-poor aquafeeds. Maximum shrimp muscle Hg concentrations were low (36.4 ng.g-1 w.w.) relative to maximum permissible concentrations for human consumption and Hg content in muscle and hepatopancreas were significantly correlated with Hg content in aquafeeds. Highest Hg concentrations in the exoskeleton of animals exposed to Hg-richer aquafeed, suggested that a detoxification mechanism is taking place. On the other hand the metallothionein suffered no variation in its relative expression in any of the experiments, meaning that the contact with feed containing the observed Hg concentrations were not sufficient to activate gene transcription. It was not possible, under the experimental design used, to infer Hg effects on the biological performance of the animals.

  3. Mercury accumulation and metallothionein expression from aquafeeds by Litopenaeus vannamei Boone, 1931 under intensive aquaculture conditions

    Directory of Open Access Journals (Sweden)

    TM. Soares

    Full Text Available This study describes the accumulation of Hg and metallothionein gene expression in Litopenaeus vannamei Boone, 1931 with aquafeeds as the major source of Hg. Trials were conducted under controlled conditions in experimental tank facilities with high (indoor tanks and low (outdoor tanks Hg aquafeeds concentrations. Aquafeeds were the sole source of Hg for the shrimps and concentrations varied from 5.4 to 124 ng.g-1 d.w.. In the three animal fractions analysed; muscle (6,3 - 15,9 ng.g-1; hepatopancreas (5,1 - 22,0 ng.g-1 and exoskeleton (3,0 - 16,2 ng.g-1, Hg concentrations were significantly lower in the outdoor trials submitted to Hg-poor aquafeeds. Maximum shrimp muscle Hg concentrations were low (36.4 ng.g-1 w.w. relative to maximum permissible concentrations for human consumption and Hg content in muscle and hepatopancreas were significantly correlated with Hg content in aquafeeds. Highest Hg concentrations in the exoskeleton of animals exposed to Hg-richer aquafeed, suggested that a detoxification mechanism is taking place. On the other hand the metallothionein suffered no variation in its relative expression in any of the experiments, meaning that the contact with feed containing the observed Hg concentrations were not sufficient to activate gene transcription. It was not possible, under the experimental design used, to infer Hg effects on the biological performance of the animals.

  4. Seasonal and diurnal variations of Hg° over New England

    Directory of Open Access Journals (Sweden)

    J. D. Hegarty

    2007-11-01

    Full Text Available Factors influencing diurnal to interannual variability in Hg° over New England were investigated using multi-year measurements conducted by the AIRMAP program at the Thompson Farm (TF coastal site, an inland elevated site at Pac Monadnock (PM, and one summer of measurements on Appledore Island (AI in the Gulf of Maine. Mixing ratios of Hg° at TF showed distinct seasonality with maxima in March and minima in October. In comparison, Hg° at AI tracked the trend at TF but with higher minima, while at PM the diurnal and annual cycles were dampened. In winter, Hg° was correlated most strongly with CO and NOy, indicative of anthropogenic emissions as their primary source. Our analysis indicates that Hg° had a regional background level of ~160 fmol/mol, a summertime dry deposition velocity of ~0.20 cm s−1, and a ~16 day lifetime in the coastal boundary layer. The influence of oceanic emissions on ambient Hg° levels was identified using the Hg°-CHBr3 correlation at both TF and AI. Moreover, the lower Hg° levels and steeper decreasing warm season trend at TF (0.5–0.6 fmol/mol d−1 compared to PM (0.2–0.3 fmol/mol d−1 likely reflected the impact of marine halogen chemistry. Large interannual variability in warm season Hg° levels in 2004 versus 2005/2006 may be due to the role of precipitation patterns in influencing surface evasion of Hg°. In contrast, changes in wintertime maximum levels of Hg° were small compared to drastic reductions in CO, CO2, NOy, and SO2 from 2004/2005 to 2006/2007. These trends could be explained by a homogeneous surface distribution of Hg° over the North American continent in winter and/or rapid removal of mercury released from anthropogenic sources. We caution that during warmer winters, the Hg°-CO slope possibly reflects the ratio of Hg° loss relative to changes in CO more than their emission ratio.

  5. Seasonal and diurnal variations of Hg° over New England

    Directory of Open Access Journals (Sweden)

    J. D. Hegarty

    2008-03-01

    Full Text Available Factors influencing diurnal to interannual variability in Hg° over New England were investigated using multi-year measurements conducted by AIRMAP at the Thompson Farm (TF coastal site, an inland elevated site at Pac Monadnock (PM, and two month measurements on Appledore Island (AI in the Gulf of Maine. Mixing ratios of Hg° at TF showed distinct seasonality with maxima in March and minima in October. Hg° at AI tracked the trend at TF but with higher minima, while at PM the diurnal and annual cycles were dampened. In winter, Hg° was correlated most strongly with CO and NOy, indicative of anthropogenic emissions as their primary source. Our analysis indicates that Hg° had a regional background level of ~160 fmol/mol in winter, a dry deposition velocity of ~0.20 cm s−1 with a ~16 day lifetime in the coastal boundary layer in summer. The influence of oceanic emissions on ambient Hg° levels was identified using the Hg°-CHBr3 correlation at both TF and AI. Moreover, the lower Hg° levels and steeper decreasing warm season trend at TF (0.5–0.6 fmol/mol d−1 compared to PM (0.2–0.3 fmol/mol d−1 likely reflected the impact of marine halogen chemistry. Large interannual variability in warm season Hg° levels in 2004 versus 2005/2006 may be due to the role of precipitation patterns in influencing surface evasion of Hg°. In contrast, changes in wintertime maximum levels of Hg° were small compared to drastic reductions in CO, CO2, NOy, and SO2 from 2004/2005 to 2006/2007. These trends could be explained by a homogeneous distribution of Hg° over North American in winter due to its long lifetime and/or rapid removal of reactive mercury from anthropogenic sources. We caution that during warmer winters, the Hg°-CO slope possibly reflects Hg° loss relative to changes in CO more than their emission ratio.

  6. Phase diagrams and microscopic structures of (Hg,Cd)Te, (Hg,Zn)Te, and (Cd,Zn)Te alloys

    Science.gov (United States)

    Patrick, R. S.; Chen, A.-B.; Sher, A.; Berding, M. A.

    1988-01-01

    A cluster theory based on the quasi-chemical approximation has been applied to study the local correlation bond-length distribution, and phase diagrams of the II-VI pseudobinary alloys Hg(1 - x)Cd(x)Te, Hg(1 - x)Zn(x)Te, and Cd(1 - x)Zn(x)Te. The cluster energy is calculated by letting it relax in some effective alloy medium and then considering the contributions from the strain and chemical energies. Two different models are presented to simulate the alloy medium. While both models show that all three alloys have nearly random distributions, the signs of the local correlation prove to be sensitive to the alloy medium chosen for the energy calculation. Good agreement is found between experiment and the bond lengths and phase diagrams in both models.

  7. The lncRNA MIR31HG regulates p16(INK4A) expression to modulate senescence.

    Science.gov (United States)

    Montes, Marta; Nielsen, Morten M; Maglieri, Giulia; Jacobsen, Anders; Højfeldt, Jonas; Agrawal-Singh, Shuchi; Hansen, Klaus; Helin, Kristian; van de Werken, Harmen J G; Pedersen, Jakob S; Lund, Anders H

    2015-04-24

    Oncogene-induced senescence (OIS) can occur in response to oncogenic insults and is considered an important tumour suppressor mechanism. Here we identify the lncRNA MIR31HG as upregulated in OIS and find that knockdown of MIR31HG promotes a strong p16(INK4A)-dependent senescence phenotype. Under normal conditions, MIR31HG is found in both nucleus and cytoplasm, but following B-RAF expression MIR31HG is located mainly in the cytoplasm. We show that MIR31HG interacts with both INK4A and MIR31HG genomic regions and with Polycomb group (PcG) proteins, and that MIR31HG is required for PcG-mediated repression of the INK4A locus. We further identify a functional enhancer, located between MIR31HG and INK4A, which becomes activated during OIS and interacts with the MIR31HG promoter. Data from melanoma patients show a negative correlation between MIR31HG and p16(INK4A) expression levels, suggesting a role for this transcript in cancer. Hence, our data provide a new lncRNA-mediated regulatory mechanism for the tumour suppressor p16(INK4A).

  8. Barrier formation at graded HgTe/CdTe heterojunctions

    Science.gov (United States)

    Goren, D.; Asa, G.; Nemirovsky, Y.

    1996-11-01

    Numerical calculations of graded HgTe/CdTe heterojunction (HJ) band diagrams at equilibrium are presented and discussed. The calculations are performed in the entire compositional range (0HJs are examined as a function of the graded region width and the graded region doping profiles. The graded region width and doping profiles were found to be the two main factors that determine whether barriers are formed as well as their shape and magnitude. The calculated results indicate that epitaxial ohmic HgTe contacts to extrinsic CdTe are possible, provided that the graded region is wider than one micron, and that it has the same doping type as the doping of the substrate with equal or higher absolute value. Further numerical calculations take into consideration the possible existence of distributed interface charges in the graded region of the HJ. It is shown that by assuming a classical transport over the potential barrier, the effective graded interface charge can be determined from the zero bias differential resistance of the HJ. Experimental transport measurements of metalorganic chemical vapor deposition (MOCVD) grown HgTe/p-CdTe graded HJs show a varying degree of rectification, indicating variations in the graded interface charge distributions which result from different MOCVD growth conditions.

  9. 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.

  10. Effects of metals doping on the removal of Hg and H2S over ceria

    Science.gov (United States)

    Ling, Lixia; Zhao, Zhongbei; Zhao, Senpeng; Wang, Qiang; Wang, Baojun; Zhang, Riguang; Li, Debao

    2017-05-01

    The effects of Mn and Fe doping into the CeO2(111) surface on the simultaneous removal of Hg and H2S was investigated, a density functional theory calculation with the on-site Coulomb interaction taken into account was adopted. The adsorptions of Hg-containing species on perfect CeO2(111), Mn/CeO2(111) and Fe/CeO2(111) surfaces were studied, the results showed that Mn and Fe dopants facilitated Hg adsorption, and more charge transferred from Hg atom to the metal doped surfaces; HgS preferred to adsorb on the perfect surface with the dissociated mode, while with the molecular mode on Mn/CeO2(111) and Fe/CeO2(111) surfaces. The reaction mechanism show that the dissociated S by H2S can easily react with Hg leading to the formation of HgS on Mn/CeO2(111) and Fe/CeO2(111) surfaces, which is crucial to capture mercury.

  11. 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.

  12. 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.

  13. Accumulation of metallic elements by Amanita muscaria from rural lowland and industrial upland regions.

    Science.gov (United States)

    Lipka, Krzysztof; Falandysz, Jerzy

    2017-03-04

    This study was carried out on the accumulation and occurrence of Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Rb, Sr and Zn in the mushroom Amanita muscaria and forest topsoil from two lowland sites in the Tuchola Pinewoods in the north-central region and an upland site in the Świetokrzyskie Mountains in the south-central region of Poland. Topsoil from the upland location showed Ag, Al, Ba, Ca, Cd, Co, Cu, Fe, Hg, Na and Zn at significantly higher concentration levels (pseudo-total fraction and often also the labile or extractable fraction) than at both lowland locations, where topsoil was richer in Mg, and similar in Rb. Amanita muscaria from the upland region differed from individuals collected in the lowland sites by higher concentration levels of Cd, Cu, Hg and Mn in caps. This could be related to higher concentration levels of the metallic elements in topsoil in the upland region. On other side, A. muscaria from the upland site was poorer in Co and Fe in caps, and in Ca, Co, Fe and Sr in stipes. In spite of the differences in content of the geogenic metallic elements in topsoil between the lowland and upland locations, A. muscaria from both regions was able to regulate uptake and accumulation of Ag, Al, Ba, Ca, K, Mg, Na, Rb and Zn, which were at similar concentration levels in caps but not necessarily in stipes.

  14. 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)

  15. 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.

  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. Hg(2+) mediated quinazoline ensemble for highly selective recognition of Cysteine.

    Science.gov (United States)

    Anand, Thangaraj; Sivaraman, Gandhi; Chellappa, Duraisamy

    2014-04-05

    A fluorimetric sensor for Hg(2+) ion and Cysteine based on quinazoline platform was designed and synthesized by one step reaction and characterized by using common spectroscopic methods. Time Dependent Density Functional Theory calculations shows that probe behaves as "ON-OFF" fluorescent quenching sensor via electron transfer/heavy atom effect. Receptor was found to exhibit selective fluorescence quenching behavior over the other competitive metal ions, and also the receptor-Hg(2+) ensemble act as an efficient "OFF-ON" sensor for Cysteine. Moreover this sensor has also been successfully applied to detection of Hg(2+) in natural water samples with good recovery.

  18. [AuHg(o-C6H4PPh22I]: A Dinuclear Heterometallic Blue Emitter

    Directory of Open Access Journals (Sweden)

    José M. López-de-Luzuriaga

    2015-02-01

    Full Text Available The heteronuclear AuI/HgII complex [AuHg(o-C6H4PPh22I] (1 was prepared by reacting of [Hg(2-C6H4PPh22] with [Au(tht2]ClO4 (1:1 and NaI in excess. The heterometallic compound 1 has been structurally characterized and shows an unusual blue luminescent emission in the solid state. Theoretical calculations suggest that that the origin of the emission arises from the iodide ligand arriving at metal-based orbitals in a Ligand to Metal-Metal Charge Transfer transition.

  19. Abundancias químicas de dos binarias de HgMn

    Science.gov (United States)

    Gonzalez, E. J.; González, J. F.; Collado, A. E.

    We present the results of the abundance analysis of two HgMn single-line binary systems: NGC 2287-106 and NGC 6025-14. The spectroscopic ob- servations have been carried out at the Complejo Astronómico el Leon-cito (CASLEO) with the REOSC spectrograph in cross-dispersion mode, cov- ering the spectral range 3800-5800 ≈. Compared to the Sun, NGC 6025-14 shows great overabundances of Hg, Mn, P, Ga and Xe, while Hg, Mn, Sr, Pt and Zr are overabundant in NGC 2287-106. FULL TEXT IN SPANISH

  20. Induced superconductivity in the surface state of mercury telluride (HgTe)

    Energy Technology Data Exchange (ETDEWEB)

    Maier, Luis; Knott, Daniel; Ames, Christopher; Bruene, Christoph; Leubner, Philipp; Oostinga, Jeroen; Buhmann, Hartmut; Molenkamp, Laurens W. [Physikalisches Institut (EP3), Universitaet Wuerzburg, 97074 Wuerzburg (Germany)

    2012-07-01

    It has been recently shown that the strained epitaxial growth of bulk HgTe layers opens a band gap in the normally semi-metallic material. This means that strained HgTe meets all prerequisites of a topological insulator, i.e. surface states and an insulating bulk, which does not contribute to transport measurements. The interfaces between topological insulators and superconductors are especially interesting due to the possibility of creation and detection of majorana fermions. Our current work is focussing on investigating contacts between strained HgTe and Nb as a superconducting material. First results show proximity effect and multiple sub gap features which are discussed in detail.

  1. 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.

  2. Mercury accumulation of three Lactarius mushroom species.

    Science.gov (United States)

    Falandysz, Jerzy

    2017-01-01

    Accumulation, distribution and potential dietary intake of mercury accumulated by mushrooms of Lactarius species L. delicious, L. volemus and L. deterrimus were studied in the Pomerania region of Poland. In total, 212 fruiting bodies and 106 underlying topsoil samples were analyzed. Analysis indicated that the concentrations of Hg were at low levels both in mushrooms and forest topsoils for a majority of the locations investigated. L. volemus that grew in soils with only a slightly elevated contamination (0.11±0.07mgkg(-1) of dried soil), very efficiently accumulated Hg in fruiting bodies and concentration levels were at 3.7±1.3mgkg(-1) of dry biomass in caps and at 1.9±0.9mgkg(-1) of dry biomass in stipes. Consumption of mushrooms foraged from the Sobowidz forest, which is close to a foundry using ferrous and non-ferrous metals could result in a Hg intake that exceeds the current statutory limits.

  3. [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.

  4. 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.

  5. Mechanism of Hg(II) Immobilization in Sediments by Sulfate-Cement Amendment.

    Science.gov (United States)

    Serrano, Susana; Vlassopoulos, Dimitri; O'Day, Peggy A

    2016-04-01

    Reactive amendments such as Portland and super-sulfate cements offer a promising technology for immobilizing metalloid contaminants such as mercury (Hg) in soils and sediments through sequestration in less bioavailable solid forms. Tidal marsh sediments were reacted with dissolved Hg(II) in synthetic seawater and fresh water solutions, treated with Portland cement and FeSO4 amendment, and aged for up to 90 days. Reacted solids were analyzed with bulk sequential extraction methods and characterized by powder X-ray diffraction (XRD), electron microscopy, and synchrotron X-ray absorption spectroscopy at the Hg LIII- and S K-edge. In amended sediments, XRD, SEM and sulfur K-edge XANES indicated formation of gypsum in seawater experiments or ettringite-type (Ca6Al2(SO4)3(OH)12(.)26H2O) phases in fresh water experiments, depending on the final solution pH (seawater ∼8.5; freshwater ∼10.5). Analysis of Hg EXAFS spectra showed Cl and Hg ligands in the first- and second-coordination shells at distances characteristic of a polynuclear chloromercury(II) salt, perhaps as a nanoparticulate phase, in both seawater and fresh water experiments. In addition to the chloromercury species, a smaller fraction (∼20-25%) of Hg was bonded to O atoms in fresh water sample spectra, suggesting the presence of a minor sorbed Hg fraction. In the absence of amendment treatment, Hg sorption and resistance to extraction can be accounted for by relatively strong binding by reduced S species present in the marsh sediment detected by S XANES. Thermodynamic calculations predict stable aqueous Hg-Cl species at seawater final pH, but higher final pH in fresh water favors aqueous Hg-hydroxide species. The difference in Hg coordination between aqueous and solid phases suggests that the initial Hg-Cl coordination was stabilized in the cement hydration products and did not re-equilibrate with the bulk solution with aging. Collectively, results suggest physical encapsulation of Hg as a polynuclear

  6. Hg0 evasion from boreal mires determined with chamber methods and a novel REA design

    Science.gov (United States)

    Osterwalder, Stefan; Fritsche, Johannes; Åkerblom, Staffan; Nilsson, Mats B.; Alewell, Christine; Bishop, Kevin

    2015-04-01

    Anthropogenic mercury has accumulated in superficial organic soils of boreal mires, hotspots of methylmercury production. We hypothesize that emission from the peat surface is an important factor in regulating the pool of mercury in mires and ultimately the loading of methylmercury to surface waters. To test this hypothesis, we used both dynamic flux chambers (DFCs) and a dual-intake, single analyzer Relaxed Eddy Accumulation (REA) system to quantify the land-atmosphere exchange of elemental mercury (Hg0) from a mixed acid mire system situated near Vindeln in the county of Västerbotten, Sweden. Teflon and polycarbonate DFCs were used to (i) investigate the effect of sulfur and nitrogen addition as well as warming and changed moisture regimes on Hg0 flux and (ii) to quantify typical all-day summertime fluxes. The novel REA design was developed for long-term, all-year flux monitoring and uses twin inlets at the same level for simultaneous accumulation of up and downdrafts on a pair of gold traps which are then analyzed sequentially on the same detector while another pair of gold traps takes over the accumulation. The exchange of Hg0 from the peatland surface was measured continuously with DFC during cloudless conditions in July 2014 and averaged 0.62 ± 1.3 ng m-2 h-1. The flux revealed a significant diurnal pattern and a strong linear relationship with air temperature inside (R2= 0.65, p levels in the soil are too long because up to now the emission of Hg from the mire surface to the atmosphere has been ignored.

  7. 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.

  8. Transition state kinetics of Hg(II) adsorption at gibbsite-water interface.

    Science.gov (United States)

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

    2007-08-25

    Kinetics of adsorption plays a pivotal factor in determining the bio-availability and mobility of Hg(II) in the environment. The kinetics of Hg(II) adsorption on gibbsite was examined as a function of pH, temperature and electrolyte type. Adsorption of Hg(II) was highly non-linear where the rate of Hg(II) retention was rapid initially and was followed by gradual or somewhat slow retention behavior with increasing contact time. The respective rate constants designated as k(1) (S-1: fast step) and k(2) (S-2: slow step). Always k(1) follows the order: k(1)(CIO)(4) >/= k(1)(NO3)(4) > k(1)(Cl). Such a relationship was not observed for the S-2 route. A two-step reaction model with pseudo-first order kinetics successfully described the adsorption rates of Hg(II) on gibbsite. Arrhenius and Erying models determined the thermodynamic parameters at activation states, which correspond to S-1 and S-2 routes. In a given system, always the activation energies showed a decrease with the pH. Gibbs free energy (DeltaG(#)), enthalpy (DeltaH(#)), and entropy (DeltaS(#)) values of activation states were almost similar both in NaClO(4) and NaNO(3) which signal a similar Hg(II) adsorptive mechanism on gibbsite. The configurations of different Hg(II)-surface complexes were elucidated by transmission vibration spectroscopy.

  9. Low-Roughness Plasma Etching of HgCdTe Masked with Patterned Silicon Dioxide

    Science.gov (United States)

    Ye, Z. H.; Hu, W. D.; Yin, W. T.; Huang, J.; Lin, C.; Hu, X. N.; Ding, R. J.; Chen, X. S.; Lu, W.; He, L.

    2011-08-01

    A novel mask technique utilizing patterned silicon dioxide films has been exploited to perform mesa etching for device delineation and electrical isolation of HgCdTe third-generation infrared focal-plane arrays (IRFPAs). High-density silicon dioxide films were deposited at temperature of 80°C, and a procedure for patterning and etching of HgCdTe was developed by standard photolithography and wet chemical etching. Scanning electron microscopy (SEM) showed that the surfaces of inductively coupled plasma (ICP) etched samples were quite clean and smooth. Root-mean-square (RMS) roughness characterized by atomic force microscopy (AFM) was less than 1.5 nm. The etching selectivity between a silicon dioxide film and HgCdTe in the samples masked with patterned silicon dioxide films was greater than 30:1. These results show that the new masking technique is readily available and promising for HgCdTe mesa etching.

  10. 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.

  11. 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.

  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. 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.

  14. Accumulation of mercury, selenium and PCBs in domestic duck brain, liver and egg from a contaminated area with an investigation of their redox responses.

    Science.gov (United States)

    Cheng, Jinping; Zhao, Wenchang; Wang, Qian; Liu, Xiaojie; Wang, Wenhua

    2013-05-01

    PCBs and methylmercury (MeHg) are two of the most ubiquitous contaminants in the Qingzhen (QZ) area of Guizhou province. The estimated tolerable daily intakes (TDIs) of total mercury (T-Hg), MeHg, PCBs and Se from contaminated rice, eggs and fish by Chinese people in QZ showed that both MeHg and PCBs exceeded the corresponding safety limits. Pearson's correlation analyses of mercury and Se in all duck tissues showed that there were high correlations with T-Hg or MeHg and Se in QZ samples. However, the molar ratio between T-Hg and Se in brain tissues was close to 1, suggesting that Se is antagonistic to mercury toxicity only in brain tissues. Biochemical analyses showed that both superoxide dismutase and glutathione peroxidase increased in the brain, whereas in the liver and egg these enzymes decreased. However, lipid peroxidation and H2O2 generation in liver and egg tissues showed contrary responses, where significant increases in these tissues were seen relative to controls. Mercury and PCBs co-accumulation in liver and egg tissues gave rise to large numbers of free radicals as well as aggravated alkyl free radicals, superoxide radical and nitric oxide, thereby resulting in oxidative stress in these tissues. It can be concluded that an adaptive response of the redox defense system is present in brain tissues, as opposed to a general break down of the redox defense system in liver and egg. The results obtained in this study will provide basic information on exposure and risk assessment in local residents.

  15. EDTA and hydrochloric acid effects on mercury accumulation by Lupinus albus.

    Science.gov (United States)

    Rodríguez, Luis; Alonso-Azcárate, Jacinto; Villaseñor, José; Rodríguez-Castellanos, Laura

    2016-12-01

    The efficiency of white lupine (Lupinus albus) to uptake and accumulate mercury from a soil polluted by mining activities was assessed in a pot experiment with chemically assisted phytoextraction. The mobilizing agents tested were ethylenediaminetetracetic acid (EDTA) and hydrochloric acid (HCl). Two doses of each amendment were used (0.5 and 1.0 g of amendment per kg of soil), and unamended pots were used as a control. Addition of HCl to the soil did not negatively affect plant biomass, while the use of EDTA led to a significant decrease in plant growth when compared to that found for non-treated pots, with plants visually showing symptoms of toxicity. The addition of hydrochloric acid increased root, shoot and total plant Hg uptake of white lupine by 3.7 times, 3.1 times and 3.5 times, respectively, in relation to non-amended plants. The greatest efficiency was obtained for the highest HCl dose. EDTA led to higher concentrations of total plant Hg than that found with the control, but, due to the aforementioned decrease in plant biomass, the Hg phytoextraction yield was not significantly increased. These results were attributed to the capability of both amendments to form stable Hg complexes. The concentration of Hg in the water of the soil pores after the phytoextraction experiment was very low for all treatments, showing that risks derived from metal leaching could be partially avoided by using doses and chemicals suitable to the concentration of metal in the soil and plant performance.

  16. 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.

  17. Induction by mercury compounds of metallothioneins in mouse tissues: inorganic mercury accumulation is not a dominant factor for metallothionein induction in the liver.

    Science.gov (United States)

    Yasutake, Akira; Nakamura, Masaaki

    2011-06-01

    Among the naturally occurring three mercury species, metallic mercury (Hg(0)), inorganic mercury (Hg(II)) and methylmercury (MeHg), Hg(II) is well documented to induce metallothionein (MT) in tissues of injected animals. Although Hg(0) and MeHg are considered to be inert in terms of directly inducing MT, MT can be induced by them after in vivo conversion to Hg(II) in an animal body. In the present study we examined accumulations of inorganic mercury and MT inductions in mouse tissues (brain, liver and kidney) up to 72 hr after treatment by one of three mercury compounds of sub-lethal doses. Exposure to mercury compounds caused significant mercury accumulations in mouse tissues examined, except for the Hg(II)-treated mouse brain. Although MeHg caused the highest total mercury accumulation in all tissues among mercury compounds, the rates of inorganic mercury were less than 10% through the experimental period. MT inductions that depended on the inorganic mercury accumulation were observed in kidney and brain. However, MT induction in the liver could not be accounted for by the inorganic mercury accumulation, but by plasma IL6 levels, marked elevation of which was observed in Hg(II) or MeHg-treated mouse. The present study demonstrated that MT was induced in mouse tissues after each of three mercury compounds, Hg(0), Hg(II) and MeHg, but the induction processes were different among tissues. The induction would occur directly through accumulation of inorganic mercury in brain and kidney, whereas the hepatic MT might be induced secondarily through mercury-induced elevation in the plasma cytokines, rather than through mercury accumulation in the tissue.

  18. Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

    Energy Technology Data Exchange (ETDEWEB)

    Baldi, Franco, E-mail: baldi@unive.it [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Gallo, Michele; Marchetto, Davide [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Faleri, Claudia [Department of Environmental Science ‘G. Sarfatti’, University of Siena, 53100 Siena (Italy); Maida, Isabel; Fani, Renato [Dipartimento di Biologia Evoluzionistica, Via Romana, 17, University of Florence, 50125 Florence (Italy)

    2013-08-15

    A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l{sup −1} HgCl{sub 2} and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified

  19. 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.

  20. 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...

  1. 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.

  2. Bonding and Moessbauer Isomer Shifts in (Hg,Pb)—1223 Cuprate

    Institute of Scientific and Technical Information of China (English)

    高发明; 田永君; 谌岩; 李东春; 董海峰; 张思远

    2003-01-01

    By using the chemical bond theory of dielectric description,the chemical bond parameters of(Hg,Pb)-1223 were calculated.The results show that the(Ba,Sr)-O and Ca-0 types of bond have higher ionic character,while the Cu-O and(Hg,Pb)-0 types of bond have more covalent character.Moessbauer isomer shifts of 57Fe and 119Sn doped in(Hg,Pb)-1223 were calculated by using the chemical environmental factor,he,defined by covalency and electronic polarizability.Four valence state tin and three valence iron sites were identified in 57Fe and 119Sn doped(Hg,Pb)-1223 superconductor.It can be concluded that all of the Fe atoms substitute the Cu at square planar Cu(1) site,Whereas Sn prefers to substitute the square pyramidal Cu(2) site.

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

    Science.gov (United States)

    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.

  4. 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.

  5. A benzothiazole-based fluorescent probe for distinguishing and bioimaging of Hg(2+) and Cu(2).

    Science.gov (United States)

    Gu, Biao; Huang, Liyan; Su, Wei; Duan, Xiaoli; Li, Haitao; Yao, Shouzhuo

    2017-02-15

    A new benzothiazole-based fluorescent probe 2-(benzo[d]thiazol-2-yl)-4-(1,3- dithian-2-yl)phenol (BT) with two different reaction sites, a thioacetal group (site 1 for Hg(2+)), and O and N atoms of the benzothiazole dye (site 2 for Cu(2+)), was designed and synthesized. The probe BT showed ratiometric fluorescent response to Hg(2+) and fluorescence quenching behavior to Cu(2+), which induces naked-eye fluorescent color changes from green to blue and colorless, respectively. Moreover, it displayed highly sensitivity and selectivity toward Hg(2+) and Cu(2+) without interference from other metal ions. The sensing mechanisms were also confirmed by (1)H NMR titration, mass spectrum and Job's plot analyses. Finally, probe BT was successfully used for fluorescent imaging of Hg(2+) and Cu(2+) in living cells, demonstrating its potential applications in biological science.

  6. Photodegradation of petroleum under Na and Hg lamps by EPR

    Energy Technology Data Exchange (ETDEWEB)

    Mauro, Eduardo di; Melo, Fernando Alves de; Turini, Marilene; Campos, Ariana de [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. of Physics; Guedes, Carmen Luisa Barbosa [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. of Chemistry; Mangrich, Antonio Salvio [Universidade Federal do Parana (UFPR), PR (Brazil). Dept. of Chemistry

    2002-07-01

    Full text: The environment has become frequent victim of the action of pollutants. This situation has been stimulating several scientific works in the attempt to monitor the self-defence of the environment and minimise the effects caused by these pollutants. The petroleum and its derived, among the several substances that attack the environment, occupy a distinction place in the pollution picture. In the present work, we studied the photodegradation of the Arabian Light and Brazilian (Campos Basin- RJ) oils. Sample of theses oils were irradiated by different time periods in a reactor equipped with Na and Hg vapour lamps, whose emission spectra have different features. The irradiated and non-irradiated samples were subjected to Electron Paramagnetic Resonance (EPR) analysis in a BRUKER (ESP-300) equipment, which operates in the X band (9 GHz) at room temperature. The EPR spectra showed similar features to the two oils. The EPR spectra are composed of a intense signal (one line) with g (spectroscopic factor) about two relative to free radicals and groups of eight lines correspondent to vanadyl porphyrinic compounds (VO{sup 2+}). The parameters of spin Hamiltonian were determined to the two detected paramagnetic species. The two oils irradiated by Na and Hg lamps showed variations in the values of g and {delta}H (linewidth) of the paramagnetic species. The changes in the parameters are the most significant in Brazilian petroleum samples irradiated by Hg lamp. The modifications in the linewidth of free radicals of the Arabian Light petroleum have the same tendency to the two utilised lamps. (author)

  7. 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.

  8. Mercury accumulation in Devils Lake, North Dakota effects of environmental variation in closed-basin lakes on mercury chronologies

    Science.gov (United States)

    Lent, R.M.; Alexander, C.R.

    1997-01-01

    Sediment cores were collected from lakes in the Devils Lake Basin in North Dakota to determine if mercury (Hg) accumulation chronologies from sediment-core data are good indicators of variations in Hg accumulation rates in saline lakes. Sediment cores from Creel Bay and Main Bay, Devils Lake were selected for detailed analysis and interpretation. The maximum Hg concentration in the Creel Bay core was 0.15 micrograms per gram at 8 to 9 centimeters. The maximum Hg concentration in the Main Bay core was 0.07 micrograms per gram at 5 to 7 centimeters. The general decreases in Hg concentrations with depth are attributed to historic variations in atmospheric Hg deposition rate. Hg stratigraphies combined with 210Pb and 137Cs dating analyses yield Hg chronologies that indicate a general increase in Hg accumulation rates in Devils Lake since the middle of the 19th century. Mean modern Hg accumulation rates in Creel Bay were 4.9 nanograms per square centimeter per year, and rates in Main Bay were 1.8 nanograms per square centimeter per year. Mean preindustrial Hg accumulation rates in Creel Bay were 1.2 nanograms per square centimeter per year, and rates in Main Bay were 1.6 nanograms per square centimeter per year. Relatively low Hg concentrations in recent sediments in the Devils Lake Basin, along with similarities in Hg accumulation rates between lakes in the Devils Lake Basin and other lakes in the northern interior of North America, indicate that local sources of Hg are not important sources of Hg. Results of the study indicate that accurate Hg chronologies are discernible in sediment cores collected from saline lakes. However, spatial and temporal variations in lake level and water chemistry common to saline lakes make interpretation of radioisotopic and geochemical chronologies difficult. Hg geochemistry in Devils Lake, and presumably in other saline lakes, is dynamic. The results of this study indicate that the absolute amount of sediment transported to Devils Lake

  9. [Absorption of Hg in typical farmland soils in the Linglong gold mining area].

    Science.gov (United States)

    Wang, Fei; Wang, Ming; Tang, Jing-Chun; Zhang, Lei

    2011-09-01

    This study focused on the adsorption properties of Hg in 2 typical farmland soils in the Linglong gold mining area in Yantai area of China. The adsorption-desorption of Hg(II) research result showed higher adsorption of Hg in neutral soil with the value of 201.38 microg/g than that in acid soil with the value of 156.9 microg/g. The desorption of Hg in both soils was low with neutral soil showing a higher desorption ratio (13%) than acid soil (12%). Hg(II) adsorption isotherms were well fitted by Langmuir and Freundlich equation in the acid soil, with the correlation coefficient r value of 0.995 6 and 0.982 6, respectively. Langmuir equation can best describe Hg(II) adsorption isotherm in the neutral soil and acid soil, with the r value of 0.995 6 and 0.955 9, respectively. The adsorption was a bi-phasic process which started with a fast-adsorption phase and a slow-adsorption phase. The adsorption amount and rate of Hg in the fast reaction phase were much larger than that in the slow one. The adsorption kinetic can be better fitted by Elovich equation with correlation coefficient of 0.971 4 and 0.967 2, respectively. At pH 3.0 - 5.5, the equilibrium adsorption amount of Hg(II) increased with higher pH, and then decreased when the pH reached 6.5.

  10. 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.

  11. 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.

  12. Long-term Hg pollution-induced structural shifts of bacterial community in the terrestrial isopod (Porcellio scaber) gut

    Energy Technology Data Exchange (ETDEWEB)

    Lapanje, Ales, E-mail: ales@ifb.s [Institute of Physical Biology, Ljubljana (Slovenia); Zrimec, Alexis [Institute of Physical Biology, Ljubljana (Slovenia); Drobne, Damjana [Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana (Slovenia); Rupnik, Maja [Institute of Public Health Maribor, Maribor (Slovenia)

    2010-10-15

    In previous studies we detected lower species richness and lower Hg sensitivity of the bacteria present in egested guts of Porcellio scaber (Crustacea, Isopoda) from chronically Hg polluted than from unpolluted environment. Basis for such results were further investigated by sequencing of 16S rRNA genes of mercury-resistant (Hg{sup r}) isolates and clone libraries. We observed up to 385 times higher numbers of Hg{sup r} bacteria in guts of animals from polluted than from unpolluted environment. The majority of Hg{sup r} strains contained merA genes. Sequencing of 16S rRNA clones from egested guts of animals from Hg-polluted environments showed elevated number of bacteria from Pseudomonas, Listeria and Bacteroidetes relatives groups. In animals from pristine environment number of bacteria from Achromobacter relatives, Alcaligenes, Paracoccus, Ochrobactrum relatives, Rhizobium/Agrobacterium, Bacillus and Microbacterium groups were elevated. Such bacterial community shifts in guts of animals from Hg-polluted environment could significantly contribute to P. scaber Hg tolerance. - Chronic environmental mercury pollution induces bacterial community shifts and presence of elevated number as well as increased diversity of Hg-resistant bacteria in guts of isopods.

  13. 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...

  14. 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.

  15. Carbon Monoxide Accumulation in the Extravehicular Mobility Unit

    Science.gov (United States)

    Conkin, J.; Norcrosss, J. R.; Alexander, D. J.; Sanders, R. W.; Makowski, M. S.

    2016-01-01

    Introduction: Life support technology in large closed systems like submarines and space stations catalyzes carbon monoxide (CO) to carbon dioxide, which is easily removed. However, in a small system like the Extravehicular Mobility Unit (EMU), spacesuit, CO from exogenous (contaminated oxygen (O (sub 2) supply) and endogenous (human metabolism) sources will accumulate in the free suit volume. The free volume becomes a sink for CO that is rebreathed by the astronaut. The accumulation through time depends on many variables: the amount absorbed by the astronaut, the amount produced by the astronaut (between 0.28 and 0.34 ?moles per hour per kilogram)[1], the amount that enters the suit from contaminated O (sub 2), the amount removed through suit leak, the free volume of the suit, and the O (sub 2) partial pressure[2], just to list a few. Contamination of the EMU O (sub 2) supply with no greater than 1 part per million CO was the motivation for empirical measurements from CO pulse oximetry (SpCO) as well as mathematical modeling of the EMU as a rebreather for CO. Methods: We developed a first-order differential mixing equation as well as an iterative method to compute CO accumulation in the EMU. Pre-post measurements of SpCO (Rad-57, Masimo Corporation) from EMU ground training and on-orbit extravehicular activities (EVAs) were collected. Results: Initial modeling without consideration of the astronaut as a sink but only the source of CO showed that after 8 hours breathing 100 percent O (sub 2) with a 10 milliliter per minute (760 millimeters Hg at 21 degrees Centigrade standard) suit leak, an endogenous production rate of 0.23 moles per hour per kilogram for a 70 kilogram person with 42 liters (1.5 cubic feet) free suit volume resulted in a peak CO partial pressure (pCO) of 0.047 millimeters Hg at 4.3 pounds per square inch absolute (222 millimeters Hg). Preliminary results based on a 2008 model[3] with consideration of the astronaut as a sink and source of CO

  16. Efficient removal and highly selective adsorption of Hg2+ by polydopamine nanospheres with total recycle capacity

    Science.gov (United States)

    Zhang, Xiulan; Jia, Xin; Zhang, Guoxiang; Hu, Jiamei; Sheng, Wenbo; Ma, Zhiyuan; Lu, Jianjiang; Liu, Zhiyong

    2014-09-01

    This study reported a new method for efficient removal of Hg2+ from contaminated water using highly selective adsorptive polydopamine (PDA) nanospheres, which were uniform and had a small diameter (150-200 nm). The adsorption isotherms, kinetics, thermodynamics were investigated. Also, the effects of ionic strength, co-existing ions on removing ability of PDA nanospheres for Hg2+ were studied. Adsorption of Hg2+ was very fast and efficient as adsorption equilibrium was completed within 4 h and the maximum adsorption capacities were 1861.72 mg/g, 2037.22 mg/g, and 2076.81 mg/g at 298 K, 313 K, and 328 K respectively, increasing with increasing of temperature. The PDA nanospheres exhibited highly selective adsorption of Hg2+ and had a total desorption capacity of 100% in hydrochloric acid solution, pH 1. The results showed that the structure of PDA nanospheres remained almost unchanged after recycling five times. Furthermore, X-ray photoelectron spectroscopy (XPS) was employed to determine the elements of PDA nanospheres before and after Hg2+ adsorption. Considering their efficient and highly Hg2+ selective adsorption, total recycle capacity, and high stability, PDA nanospheres will be feasible in a number of practical applications.

  17. [Heavy metals contents and Hg adsorption characteristics of mosses in virgin forest of Gongga Mountain].

    Science.gov (United States)

    Liang, Peng; Yang, Yong-Kui; He, Lei; Wang, Ding-Yong

    2008-06-01

    Seven main moss species in the Hailuogou virgin forest of Gongga Mountain were sampled to determine their heavy metals (Hg, Cr, Cd, Ni, Pb, Cu, Mn, Zn and Fe) content, and two widely distributed species, Pleurozium schreberi (Brid.) Mitt. and Racomitrium laetum Besch., were selected to study their Hg adsorption characteristics. The results showed that the heavy metals contents in the mosses were lower than the background values in Europe and America, except that the Cd had a comparable value, which indicated that the atmosphere in study area was not polluted by heavy metals and good in quality. The Hg adsorption by P. schreberi and R. laetum was an initiative and rapid process, with the equilibrium reached in about two hours, and could be well fitted by Freundlich and Langmuir equations. Based on Langmuir equation, the maximum Hg adsorption capacities of P. schreberi and R. laetum were 15.24 and 8.19 mg x g(-1), respectively, suggesting that the two mosses had a good capacity of Hg adsorption, and could be used as the bio-monitors of atmospheric Hg pollution.

  18. Rhubarb Anthraquinones Protect Rats against Mercuric Chloride (HgCl2-Induced Acute Renal Failure

    Directory of Open Access Journals (Sweden)

    Dan Gao

    2016-03-01

    Full Text Available Mercury (Hg causes severe nephrotoxicity in subjects with excess exposure. This work attempted to identify whether a natural medicine—rhubarb—has protective effects against mercuric chloride (HgCl2-induced acute renal failure (ARF, and which of its components contributed most to the treatment. Total rhubarb extract (TR were separated to the total anthraquinones (TA, the total tannins (TT and remaining component extract (RC. Each extract was orally pre-administered to rats for five successive days followed by HgCl2 injection to induce kidney injury. Subsequently, renal histopathology and biochemical examinations were performed in vitro to evaluate the protective effects. Pharmacological studies showed that TR and TA, but not TT or RC manifested significant protection activity against HgCl2-induced ARF. There were also significant declines of serum creatine, urea nitrogen values and increases of total protein albumin levels in TR and TA treated groups compared to HgCl2 alone (p < 0.05. At last, the major components in TA extract were further identified as anthraquinones by liquid chromatography coupled mass spectroscopy. This study thus provides observational evidences that rhubarb could ameliorate HgCl2-induced ARF and its anthraquinones in particular are the effective components responsible for this activity in rhubarb extract.

  19. 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

    , obtained by combining results from conventional Hall measurements of the free carrier concentration with Faraday rotation measurements, will also be presented. One example of how this type of information was derived is illustrated in the following figure which shows Faraday rotation vs wavelength modeled for Hg(l-x)ZnxSe at a temperature of 300K and x=0.07. The plasma contribution, total Faraday rotation, and interband contribution to the Faraday rotation, are designated in the Figure as del(p), FR tot, and del(i) respectively. Experimentally measured values of FR tot, each indicated by + , agree acceptably well with the model at the probe wavelength of 10.6 microns. The model shows that at the probe wavelength, practically all the rotation is due to the plasma component, which can be expressed as delta(sub p)= 2pi(e(sup 3))NBL/c(sup 2)nm*(sup 2) omega(sup 2). In this equation, delta(sub p) is the rotation angle due to the free carrier plasma, N is the free carrier concentration, B the magnetic field strength, L the thickness of the sample, n the index of refraction, omega the probe radiation frequency, c the speed of light, e the electron charge, and m* the effective mass. A measurement of N by conventional techniques, combined with a measurement of the Faraday rotation angle allows m* to be accurately determined since it is an inverse square function.

  20. RF magnetron sputtering deposition of CdTe passivation on HgCdTe

    Science.gov (United States)

    Rutkowski, Jaroslaw; Adamiec, Krzysztof; Rogalski, Antoni

    1998-04-01

    In this study, we report the RF magnetron sputtering growth and characterization of CdTe passivant on bulk n-type HgCdTe. Our investigations include the HgCdTe surface preparation and in-situ pretreatment, deposition-induced surface damage, interface charge, CdTe film stoichiometry, and thermal stability. The metal-insulator-semiconductor test structures are processed and their electrical properties are measured by capacitance-voltage characteristics. The heterostructures are also characterized by reflectance measurement. In order to investigate the passivation properties of CdTe/HgCdTe heterostructures, we have modeled the band diagram of abrupt CdTe/HgCdTe heterojunction. The effect of sputtering growth condition parameters is also reported. The sputtering CdTe layers, exhibit excellent dielectric, insulating and mechano- chemical properties, as well as interface properties. The interfaces are characterized by slight accumulation and a small hysteresis. A carefully controlled growth process and surface pretreatment tailored to the specific material are required in order to obtain near flat band conditions on n- type materials. Additional informations on surface limitations are obtained from analyzing the I-V characteristics of photodiodes with metal gates covering the p-n junction surface location.

  1. 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

  2. Historical anthropogenic contributions to mercury accumulation recorded by a peat core from Dajiuhu montane mire, central China.

    Science.gov (United States)

    Li, Yuanping; Ma, Chunmei; Zhu, Cheng; Huang, Run; Zheng, Chaogui

    2016-09-01

    Mercury (Hg) accumulation records spanning the last 16,000 years before present (yr BP, relative to AD 1950) were derived from a peat core collected from Dajiuhu mire, central China. The natural Hg concentration and accumulation rate (free from anthropogenic influence) were 135.5 ± 53.9 ng g(-1) and 6.5 ± 4.5 μg m(-2) yr(-1), respectively. The increase in Hg flux that started from a core depth of 96.5 cm (3358 cal yr BP) is independent of soil erosion and organic matter content. We attribute this to an increase in atmospheric Hg deposition derived from regional anthropogenic activities. Anthropogenic Hg accumulation rates (Hg-ARA) in the pre-industrial period peaked during the Ming and the early Qing dynasties (582-100 cal yr BP), with Hg-ARA of 9.9-24.6 and 10.7-24.4 μg m(-2) yr(-1), respectively. In the industrial interval (post∼1850 AD), Hg-ARA increased progressively and reached 32.7 μg m(-2) yr(-1) at the top of the core. Our results indicate the existence of regional atmospheric Hg pollution spanning the past ∼3400 years, and place recent Hg enrichment in central China in a broader historical context.

  3. Species-specific accumulation of methyl and total mercury in sharks from offshore and coastal waters of Korea.

    Science.gov (United States)

    Kim, Sang-Jo; Lee, Hyun-Kyung; Badejo, Abimbola C; Lee, Won-Chan; Moon, Hyo-Bang

    2016-01-15

    Limited information is available on mercury (Hg) levels in various shark species consumed in Korea. The methyl-Hg (Me-Hg) and total Hg concentrations in all shark species ranged from 0.08 to 4.5 (mean: 1.2) mg/kg wet weight and from 0.1 to 7.0 (mean: 1.4) mg/kg wet weight, respectively. Inter-species differences in Hg accumulation were found among the species; however, Hg accumulation was homogenous between dorsal and pectoral fins within species. The highest Hg levels were found in aggressive carnivore shark species. Trophic position was important in determining Hg accumulation for aggressive carnivore sharks. Approximately 80% of shark species exceeded the safety limits for Me-Hg established by domestic and international authorities. The mean estimated daily intake of Me-Hg (1.3 μg/kg body weight/day) for Korean populations consuming various sharks was higher than the guidelines proposed by international regulatory authorities, suggesting that excessive shark fin consumption may pose potential health risks for Koreans.

  4. 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.

  5. 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.

  6. Evaluation of species-specific dissimilarities in two marine fish species: mercury accumulation as a function of metal levels in consumed prey.

    Science.gov (United States)

    Mieiro, C L; Coelho, J P; Pacheco, M; Duarte, A C; Pereira, M E

    2012-07-01

    The aim of this research was to compare mercury (Hg) accumulation (total and organic) and tissue distribution in two marine fish species with contrasting feeding tactics. Thus, juvenile specimens of European sea bass and Golden grey mullet were surveyed in an estuary historically affected by Hg discharges. Total Hg was preferentially accumulated in intestine, muscle, and liver, whereas gills and brain presented the lowest Hg levels observed in both species. Significant differences between species were only verified for muscle, with D. labrax's levels being greater than L. aurata's. Muscle accounted for >87% of the Hg relative tissue burden, whereas liver did not exceed 11%. Organic Hg accumulation occurred mainly in liver and muscle, with D. labrax evidencing significantly greater loads. Moreover, organic Hg in consumed prey items was also significantly greater in D. labrax. Accumulation of organic Hg in liver, intestine, and muscle seemed to vary as a function of the consumed prey items contamination, suggesting fish feeding strategies as the dominant factor determining metal accumulation. For both fish species, a stable ratio was observed between Hg increments from the reference to the contaminated site, possibly indicating that the organic Hg content of diet may regulate the internal levels of this contaminant. Thus, this ratio might prove to be a useful contamination predictor tool in early life stages of fish.

  7. 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.

  8. Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J.A., E-mail: jay@sfei.org [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Looker, R.E. [San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street, Suite 1400, Oakland, CA 94612 (United States); Yee, D. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Marvin-Di Pasquale, M. [U.S. Geological Survey, Water Resources Division/MS 480, 345 Middlefield Road, Menlo Park, CA 94025 (United States); Grenier, J.L. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Austin, C.M. [San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street, Suite 1400, Oakland, CA 94612 (United States); McKee, L.J.; Greenfield, B.K. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Brodberg, R. [California Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1001 I Street, Sacramento, CA 95812 (United States); Blum, J.D. [Department of Geological Sciences, University of Michigan, 1100 North University Avenue, Ann Arbor, MI 48109 (United States)

    2012-11-15

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  9. Mercury accumulation rates in Caço Lake, NE Brazil during the past 20.000 years

    Science.gov (United States)

    de Lacerda, Luiz Drude; Turcq, Bruno; Sifeddine, Abdel; Cordeiro, Renato Campello

    2017-08-01

    Total Hg, TC, TN, goethite and siderite distributions in sediment cores from two locations across Caçó Lake (Brazil) identified paleoclimate factors that had affected the Hg deposition in this shallow tropical lake and its relationship with past climate and basin processes. Concentrations and fluxes of Hg were maximum in the Last Glacial Maximum (LGM), with averages of 397 ng g-1 and 24.3 μg m-2 yr-1, respectively, decreasing during the Heinrich Stadial 1 (H1) and further during the Meltwater pulse 1A (MWP-1A). The higher values during LGM and H1 were strongly associated with dust deposition as observed in Greenland ice cores. After a period of lower values, there was a significant increase of concentrations and fluxes during the Younger Dryas (193 ng g-1 and 4.1 μg m-2 yr-1), still associated in part with dust deposition but also being influenced by the high volcanic activity of this period. Concentrations and fluxes decreased again to the lowest values during the Holocene from about 9500 to 2000 cal yr BP (114 ng g-1 and 1.25 μg m-2 yr-1). Analyses of 210Pb dated shorter cores shows increasing Hg accumulation rates during the past century, larger than in other period in the past but could not evidence the influence of colonial gold mining as suggested by earlier studies.

  10. Synthesis and Crystal Structure of New Coordination Compound Mn2Hg4(SCN)12%新型配合物Mn2Hg4(SCN)12的合成与晶体结构分析

    Institute of Scientific and Technical Information of China (English)

    李广慧; 方奇; 薛刚; 于文涛

    2005-01-01

    A new inorganic coordination compound Mn2Hg4(SCN)12 was synthesized. The grown crystals were characterized by elemental analysis, infrared spectroscopic analysis and powder crystal X-ray diffraction in detail. The crystal structure of Mn2Hg4(SCN)12 was determined by single-crystal X-ray diffraction. It belongs to monoclinic system, P21/c space group. The cell dimensions are: a=1.171 6 nm, b=1.431 05 nm, c=2.105 1 nm,β=100.738°,and Z=4. In the structure of it, half of Mn2+ cations have five-coordinate number, and other half of Mn2+ cations have six-coordinate number; 3/4 of Hg2+ cations are coordinated by four SCN-, 1/4 of Hg2+ cations are coordinated by three SCN- and one NCS-, all the coordination geometry of Hg2+ show slightly distorted tetrahedrons. CCDC:244939.

  11. 实验室条件下Hg2+胁迫对集球藻生理生化特性的影响%Study on the physiological and biochemical properties of Palmellococcus sp. subjected to Hg2 + stress in laboratory condition

    Institute of Scientific and Technical Information of China (English)

    王文欣; 饶本强

    2012-01-01

    重金属污染是当今世界最为关注的生态环境问题之~。在实验室条件下,以一种从荒漠土壤中分离的单细胞绿藻——集球藻(Palmellococcussp.)为试验材料,研究Hg2+胁迫对集球藻生理生化特性的影响。结果表明:与对照相比,Hg2+胁迫明显抑制了集球藻的生长和光合活性,表现为藻体生物量(叶绿素a)和叶绿素荧光参数(Fv/Fm)均发生显著性下降。随Hg2+胁迫剂量加大,集球藻细胞内可溶性糖出现一定程度的积累,而HS2+胁迫明显抑制细胞内可溶性蛋白质的合成。集球藻细胞抗氧化活性的测定结果表明,Hg2+胁迫导致集球藻细胞MDA含量明显升高,SOD和CAT活性亦呈现增大的变化趋势。研究结果对于更好地理解荒漠土壤绿藻对重金属胁迫的耐受性及其适应机制提供了有意义的参考。%Heavy metal pollution is one of the most common ecological and environmental problems faced in current world. In this study, we selected one species of single cellular green alga, Palmelloeoccus sp. , separated from desert soil, as experimental material to investigate the effect of Hg2 + stress on its physiological and biochemical properties in laboratory condition. Our results showed that Hg2 + stress obviously inhibited the growth and photosynthetic activity of Palmelloeoccus sp. There were evident decreases in biomass (chlorophyll a) and chlorophyll fluorescence parameter (Fv/Fm) of the treated cells compared to the control cells. It also indicated that the soluble saccharide content of the treated algal cells present accumulation to some extent along with Hg2 + concentration addition, while Hg2 + stress evi- dently restrained the synthesis of cellular soluble protein of Palmelloeoecus sp. The results from examination of antioxidant activities of Palmellococcus sp. subjected to Hg2 + treatments validated that Hg2 + stress had a significantly deleterious effect on

  12. Aqueous solvation of Hg(OH)2: energetic and dynamical density functional theory studies of the Hg(OH)2-(H2O)n (n = 1-24) structures.

    Science.gov (United States)

    Amaro-Estrada, J I; Maron, L; Ramírez-Solís, A

    2013-09-19

    A systematic study of the hydration of Hg(OH)2 by the stepwise solvation approach is reported. The optimized structures, solvation energies, and incremental free energies of 1-24 water molecules interacting with the solute have been computed at the B3PW91 level using 6-31G(d,p) basis sets for the O and H atoms. The mercury atom was treated with the Stuttgart-Köln relativistic core potential in combination with an extended optimized valence basis set. One to three direct Hg-water interactions appear along the solvation process. The first solvation shell is fully formed with 24 water molecules. A stable pentacoordinated Hg trigonal bipyramid structure appears for n > 15. Density functional theory (DFT) Born-Oppenheimer molecular dynamics simulations showed the thermal stability of the Hg(OH)2-(H2O)24 structure at room temperature and the persistence of the trigonal bipyramid coordination around Hg. The Gibbs free energy for the first solvation shell is significantly larger for the fully solvated Hg(OH)2 than the one previously obtained for the HgCl2 case, due to σ-acceptor and π-donor properties involving the hydroxyl groups of the solute. This suggests that the transmembrane passage of Hg(OH)2 into the cell via simple diffusion is less favorable compared to the case when the metal is coordinated with two Cl groups.

  13. Mercury species accumulation and trophic transfer in biological systems using the Almadén mining district (Ciudad Real, Spain) as a case of study.

    Science.gov (United States)

    Patiño Ropero, M J; Rodríguez Fariñas, N; Mateo, R; Berzas Nevado, J J; Rodríguez Martín-Doimeadios, R C

    2016-04-01

    The impact of mercury (Hg) pollution in the terrestrial environments and the terrestrial food chains including the impact on human food consumption is still greatly under-investigated. In particular, studies including Hg speciation and detoxification strategies in terrestrial animals are almost non-existing, but these are key information with important implications for human beings. Therefore, in this work, we report on Hg species (inorganic mercury, iHg, and monomethylmercury, MeHg) distribution among terrestrial animal tissues obtained from a real-world Hg exposure scenario (Almadén mining district, Spain). Thus, we studied Hg species (iHg and MeHg) and total selenium (Se) content in liver and kidney of red deer (Cervus elaphus; n = 41) and wild boar (Sus scrofa; n = 16). Similar mercury species distribution was found for both red deer and wild boar. Major differences were found between tissues; thus, in kidney, iHg was clearly the predominant species (more than 81%), while in liver, the species distribution was less homogeneous with a percentage of MeHg up to 46% in some cases. Therefore, Hg accumulation and MeHg transfer were evident in terrestrial ecosystems. The interaction between total Se and Hg species has been evaluated by tissue and by animal species. Similar relationships were found in kidney for both Hg species in red deer and wild boar. However, in liver, there were differences between animals. The possible underlying mechanisms are discussed.

  14. [HG-AFS determination of selenium in Moringa oleifera].

    Science.gov (United States)

    Huang, Guo-qing; Xiao, Zi-jun

    2007-02-01

    The Se content in Moringa oleifera was studied by hydride generation atom fluorescence spectrometry (HG-AFS) with wet digestion. The effects of the way of digestion, the work condition of apparatus, the reaction medium and acidity, and the reducing agent and masking agent on the determination of Se were investigated. And the operating condition of apparatus was optimized. The results showed that the detection limit of Se in this method was 0.42 ng x mL(-1) in the linear ranger of 0-120 ng x mL(-1), the relative standard deviation was 3.53% (n = 11), and the recovery of the method was 95.2%-104.6%. It was showed that the method was very sensitive, simple, rapid and accurate.

  15. Modeling IRA Accumulation and Withdrawals

    OpenAIRE

    Sabelhaus, John

    2000-01-01

    Empirical analysis of IRA accumulation and withdrawal patterns is limited because information about IRA balances and flows is not available for a sample of taxpayers. This paper combines survey data on IRA balances with individual tax return data on IRA flows to study IRA accumulation and withdrawal patterns across cohorts. The analysis shows that IRA rules such as penalties for early withdrawals and minimum distribution requirements have predictable effects on IRA flows. The estimated propen...

  16. First principle study of the interaction of elemental Hg with small neutral, anionic and cationic Pd ( = 1-6) clusters

    Indian Academy of Sciences (India)

    Shamoon Ahmad Siddiqui; Nadir Bouarissa

    2013-11-01

    Density functional theory (DFT)-based calculations have been performed so as to study the interaction of elemental mercury (Hg) with small neutral, cationic and anionic palladium clusters (Pd, = 1-6). Results of these calculations clearly indicate that frontier molecular orbital (FMO) theory is a useful method to predict the selectivity of Hg adsorption. Binding energies of Hg on cationic Pd clusters are generally found to be greater than those on neutral and anionic clusters. Results of natural bond orbital (NBO) analysis show that the flow of electrons in the neutral and charged complexes is mainly due to s orbitals of Hg. NBO analysis also indicates that, in most of the cases, the binding energies of Hg with Pdn clusters are directly proportional to charge transfer, i.e., greater the charge transfer, higher is the binding energy.

  17. Long-term Hg pollution-induced structural shifts of bacterial community in the terrestrial isopod (Porcellio scaber) gut.

    Science.gov (United States)

    Lapanje, Ales; Zrimec, Alexis; Drobne, Damjana; Rupnik, Maja

    2010-10-01

    In previous studies we detected lower species richness and lower Hg sensitivity of the bacteria present in egested guts of Porcellio scaber (Crustacea, Isopoda) from chronically Hg polluted than from unpolluted environment. Basis for such results were further investigated by sequencing of 16S rRNA genes of mercury-resistant (Hgr) isolates and clone libraries. We observed up to 385 times higher numbers of Hgr bacteria in guts of animals from polluted than from unpolluted environment. The majority of Hgr strains contained merA genes. Sequencing of 16S rRNA clones from egested guts of animals from Hg-polluted environments showed elevated number of bacteria from Pseudomonas, Listeria and Bacteroidetes relatives groups. In animals from pristine environment number of bacteria from Achromobacter relatives, Alcaligenes, Paracoccus, Ochrobactrum relatives, Rhizobium/Agrobacterium, Bacillus and Microbacterium groups were elevated. Such bacterial community shifts in guts of animals from Hg-polluted environment could significantly contribute to P. scaber Hg tolerance.

  18. A fluorescent probe based upon anthrancene-dopamine thioether for imaging Hg(2+) ions in living cells.

    Science.gov (United States)

    Feng, Wenjie; Xia, Qing; Zhou, Haiyan; Ni, Yun; Wang, Liulin; Jing, Su; Li, Lin; Ji, Wei

    2017-05-15

    A novel anthrancene-dopamine thioether L compound was designed as fluorescent probe for detecting Hg(2+) in living cells sample. L exhibits a good sensitive and selective recognition towards Hg(2+) ions in the presence of other important relevant metal ions and amino acids in HEPES solution. The addition of Hg(2+) causes a marked enhancement in the fluorescence emission intensity with the detection limit as low as 1.1×10(-6)M, combining with obvious colormetric change from colorless to pale brown. Mechanistic studies show that catechol group and sulfur atom in L all participate in the coordination with Hg(2+), though catechol group contributes mainly to chelation-enhanced fluorescence enhancement and sulfur atom to selectivity. Furthermore, L demonstrates good cell permeability and compatibility for sensitive fluorescent detection of Hg(2+) in HepG2 cells. This present probe will have broad applications in biological imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. A correlative study of hydrogen peroxide accumulation after mercury or copper treatment observed in root nodules of Medicago truncatula under light, confocal and electron microscopy.

    Science.gov (United States)

    Górska-Czekaj, Magdalena; Borucki, Wojciech

    2013-01-01

    Heavy metal stress affects both, nodulation and nitrogen fixation of legumes. Mercury triggers disturbances in cellular structure and metabolism but its influence on ROS generation is poorly understood. Copper is redox active metal which in opposition to mercury is an essential micronutrient for plants. Excess of copper is cytotoxic, as it participates in ROS generation via Fenton-type reaction. The present work describes changes in hydrogen peroxide (H₂O₂) accumulation in response to monthly stress caused by mercury (6 mg/L HgCl₂) or copper (60 mg/L CuCl₂) in root nodules. H₂O₂ accumulation viewed with a light microscopy was detected by the use of diaminobenzidine (DAB). 2',7'-Dichlorofluorescein diacetate (H2DCF-DA) was used as a probe for the intracellular localization of H₂O₂ with a confocal laser scanning system. H₂O₂ detection under transmission electron microscopy was performed by the use of cerium method. Histochemical localization and light and confocal microscopy investigations revealed that under Hg or Cu treatments distinct amount of H₂O₂ accumulated mainly in the interzone and nitrogen-fixing zone. Under normal conditions H₂O₂ accumulated predominantly in the interzone. Electron microscopy observations showed H₂O₂ accumulation under Hg or Cu- treatments around peribacteroid membranes of mature symbiosomes located within nitrogen-fixing zone. It should be underlined that under normal conditions H₂O₂ was not detected at the peribacteroid membranes. The main result of our observations is increased accumulation of H₂O₂ in response to mercury and copper treatments at the peribacteroidal membranes, to our knowledge shown for the first time. Therefore, our results revealed that an overproduction of H₂O₂ in response to copper or mercury-treatment may account for lowering of nitrogen fixation rates in heavy-metal affected root nodules. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. In vivo formation of natural HgSe nanoparticles in the liver and brain of pilot whales

    Science.gov (United States)

    Gajdosechova, Zuzana; Lawan, Mohammed M.; Urgast, Dagmar S.; Raab, Andrea; Scheckel, Kirk G.; Lombi, Enzo; Kopittke, Peter M.; Loeschner, Katrin; Larsen, Erik H.; Woods, Glenn; Brownlow, Andrew; Read, Fiona L.; Feldmann, Jörg; Krupp, Eva M.

    2016-01-01

    To understand the biochemistry of methylmercury (MeHg) that leads to the formation of mercury-selenium (Hg-Se) clusters is a long outstanding challenge that promises to deepen our knowledge of MeHg detoxification and the role Se plays in this process. Here, we show that mercury selenide (HgSe) nanoparticles in the liver and brain of long-finned pilot whales are attached to Se-rich structures and possibly act as a nucleation point for the formation of large Se-Hg clusters, which can grow with age to over 5 μm in size. The detoxification mechanism is fully developed from the early age of the animals, with particulate Hg found already in juvenile tissues. As a consequence of MeHg detoxification, Se-methionine, the selenium pool in the system is depleted in the efforts to maintain essential levels of Se-cysteine. This study provides evidence of so far unreported depletion of the bioavailable Se pool, a plausible driving mechanism of demonstrated neurotoxic effects of MeHg in the organism affected by its high dietary intake. PMID:27678068

  1. In vivo formation of natural HgSe nanoparticles in the liver and brain of pilot whales

    Science.gov (United States)

    Gajdosechova, Zuzana; Lawan, Mohammed M.; Urgast, Dagmar S.; Raab, Andrea; Scheckel, Kirk G.; Lombi, Enzo; Kopittke, Peter M.; Loeschner, Katrin; Larsen, Erik H.; Woods, Glenn; Brownlow, Andrew; Read, Fiona L.; Feldmann, Jörg; Krupp, Eva M.

    2016-09-01

    To understand the biochemistry of methylmercury (MeHg) that leads to the formation of mercury-selenium (Hg-Se) clusters is a long outstanding challenge that promises to deepen our knowledge of MeHg detoxification and the role Se plays in this process. Here, we show that mercury selenide (HgSe) nanoparticles in the liver and brain of long-finned pilot whales are attached to Se-rich structures and possibly act as a nucleation point for the formation of large Se-Hg clusters, which can grow with age to over 5 μm in size. The detoxification mechanism is fully developed from the early age of the animals, with particulate Hg found already in juvenile tissues. As a consequence of MeHg detoxification, Se-methionine, the selenium pool in the system is depleted in the efforts to maintain essential levels of Se-cysteine. This study provides evidence of so far unreported depletion of the bioavailable Se pool, a plausible driving mechanism of demonstrated neurotoxic effects of MeHg in the organism affected by its high dietary intake.

  2. 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

  3. 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.

  4. 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.

  5. Phenological development stages variation versus mercury tolerance, accumulation, and allocation in salt marsh macrophytes Triglochin maritima and Scirpus maritimus prevalent in Ria de Aveiro coastal lagoon (Portugal).

    Science.gov (United States)

    Anjum, Naser A; Ahmad, Iqbal; Válega, Mónica; Figueira, Etelvina; Duarte, Armando C; Pereira, Eduarda

    2013-06-01

    Efficient and sustainable management of rapidly mounting environmental issues has been the focus of current intensive research. The present study aimed to investigate the impact of plant phenological development stage variation on mercury (Hg) tolerance, accumulation, and allocation in two salt marsh macrophytes Triglochin maritima and Scirpus maritimus prevalent in historically Hg-contaminated Ria de Aveiro coastal lagoon (Portugal). Both plant samples and the sediments vegetated by monospecific stands of T. maritima and S. maritimus were collected from reference (R) and sites with moderate (M) and high (H) Hg contamination in Laranjo bay within Ria de Aveiro lagoon. Hg tolerance, uptake, and allocation in T. maritima and S. maritimus, physico-chemical traits (pH, redox potential, and organic matter content) and Hg concentrations in sediments vegetated by these species were impacted differentially by phenological development stages variation irrespective of the Hg contamination level. In T. maritima, Hg concentration increased with increase in Hg contamination gradient where root displayed significantly higher Hg followed by rhizome and leaf maximally at H. However, in S. maritimus, the highest Hg concentration was perceptible in rhizome followed by root maximally at M. Between the two studied plant species, S. maritimus displayed higher Hg tolerance index (depicted by higher plant dry mass allocated to reproductive stage) and higher available Hg at M (during all growth stages) and H (during senescent stage) when compared to T. maritimus. Both plant species proved to be Hg excluder (low root/rhizome-leaf Hg translocation). Additionally, T. maritima also acted as Hg stabilizer while, S. maritimus as Hg accumulator. It can be inferred from the study that (a) the plant phenological development stage variations significantly influenced plant Hg sensitivity by impacting sediment chemistry, plant growth (in terms of plant dry mass), Hg accumulation, and its subsequent

  6. Chemical substitution of Cd ions by Hg in CdSe nanorods and nanodots: Spectroscopic and structural examination

    Energy Technology Data Exchange (ETDEWEB)

    Prudnikau, Anatol [Institute for Physico-Chemical Problems, Belarussian State University, 220030 Minsk (Belarus); Artemyev, Mikhail, E-mail: m_artemyev@yahoo.com [Institute for Physico-Chemical Problems, Belarussian State University, 220030 Minsk (Belarus); Laboratory of Nano-Bioengineering, Moscow Engineering Physics Institute, 31 Kashirskoe sh., 115409 Moscow (Russian Federation); Molinari, Michael; Troyon, Michel [Universite de Reims Champagne-Ardenne, 51100 Reims (France); Sukhanova, Alyona; Nabiev, Igor [Universite de Reims Champagne-Ardenne, 51100 Reims (France); Laboratory of Nano-Bioengineering, Moscow Engineering Physics Institute, 31 Kashirskoe sh., 115409 Moscow (Russian Federation); Baranov, Alexandr V.; Cherevkov, Sergey A.; Fedorov, Anatoly V. [Saint-Petersburg State University of Information Technologies, Mechanics and Optics, St.-Petersburg 197101 (Russian Federation)

    2012-06-05

    Highlights: Black-Right-Pointing-Pointer We studied cadmium-by-mercury chemical substitution in CdSe nanocrystals. Black-Right-Pointing-Pointer Zinc blende CdSe quantum dots can be easily converted to isostructural Cd{sub x}Hg{sub 1-x}Se. Black-Right-Pointing-Pointer Wurtzite CdSe QDs require longer time to convert to a zinc blende Cd{sub x}Hg{sub 1-x}Se. Black-Right-Pointing-Pointer Wurtzite CdSe nanorods transform to nanoheterogeneous luminescent Cd{sub x}Hg{sub 1-x}Se rods. - Abstract: The chemical substitution of cadmium by mercury in colloidal CdSe quantum dots (QDs) and nanorods has been examined by absorption, photoluminescence and Raman spectroscopy. The crystalline structure of original CdSe QDs used for Cd/Hg substitution (zinc blende versus wurtzite) shows a strong impact on the optical and structural properties of resultant Cd{sub x}Hg{sub 1-x}Se nanocrystals. Substitution of Cd by Hg in isostructural zinc blende CdSe QDs converts them to ternary Cd{sub x}Hg{sub 1-x}Se zinc blende nanocrystals with significant NIR emission. Whereas, the wurtzite CdSe QDs transformed first to ternary nanocrystals with almost no emission followed by slow structural reorganization to a NIR-emitting zinc blende Cd{sub x}Hg{sub 1-x}Se QDs. CdSe nanorods with intrinsic wurtzite structure show unexpectedly intense NIR emission even at early Cd/Hg substitution stage with PL active zinc blende Cd{sub x}Hg{sub 1-x}Se regions.

  7. 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">

  8. Effects of the soil microbial community on mobile proportions and speciation of mercury (Hg) in contaminated soil.

    Science.gov (United States)

    Száková, Jiřina; Havlíčková, Jitka; Šípková, Adéla; Gabriel, Jiří; Švec, Karel; Baldrian, Petr; Sysalová, Jiřina; Coufalík, Pavel; Červenka, Rostislav; Zvěřina, Ondřej; Komárek, Josef; Tlustoš, Pavel

    2016-01-01

    The precise characterization of the behavior of individual microorganisms in the presence of increased mercury contents in soil is necessary for better elucidation of the fate of mercury in the soil environment. In our investigation, resistant bacterial strains isolated from two mercury contaminated soils, represented by Paenibacillus alginolyticus, Burkholderia glathei, Burkholderia sp., and Pseudomonas sp., were used. Two differently contaminated soils (0.5 and 7 mg kg(-1) total mercury) were chosen. Preliminary soil analysis showed the presence of methylmercury and phenylmercury with the higher soil mercury level. Modified rhizobox experiments were performed to assess the ability of mercury accumulating strains to deplete the mobile and mobilizable mercury portions in the soil by modification; microbial agar cultures were used rather than the plant root zone. A sequential extraction procedure was performed to release the following mercury fractions: water soluble, extracted in acidic conditions, bound to humic substances, elemental, and bound to complexes, HgS and residual. Inductively coupled plasma mass spectrometry (ICP-MS) and a single-purpose atomic absorption spectrometer (AMA-254) were applied for mercury determination in the samples and extracts. Gas chromatography coupled to atomic fluorescence spectrometry (GC-AFS) was used for the determination of organomercury compounds. The analysis of the microbial community at the end of the experiment showed a 42% abundance of Paenibacillus sp. followed by Acetivibrio sp., Brevibacillus sp., Cohnella sp., Lysinibacillus sp., and Clostridium sp. not exceeding 2% abundance. The results suggest importance of Paenibacillus sp. in Hg transformation processes. This genus should be tested for potential bioremediation use in further research.

  9. Anthropogenic impact of mercury accumulation in fish from the Rio Madeira and Rio Negro rivers (Amazonia).

    Science.gov (United States)

    Dórea, José G; Barbosa, Antonio C

    2007-03-01

    Fish is an important concentrator of mono-methyl mercury and the main route to human contamination. We compared fish Hg bioaccumulation (within similar weight ranges) in two Amazonian river habitats during high-water seasons. The Rio Madeira has been greatly impacted by agriculture, alluvial gold extraction, and a hydroelectric reservoir, whereas the Rio Negro is much less affected by these human activities. The species at the top of the food web, Hoplias malabaricus (piscivorous; 80-668 ng Hg/g) and Cichla spp. (piscivorous; 42-747 ng Hg/g) showed the highest range of Hg concentrations. Nonpiscivorous species with comparable weight range, such as Potamorhina latior (detritivorous; 20-157 ng Hg/g) and Myleus torquatus (herbivorous; 2-182 ng Hg/g), had lower Hg concentrations. Triportheus elongatus (omnivorous; 5-350 ng Hg/g), with the lowest weight range, also showed a low range of Hg concentrations. Despite the Rio Madeira's higher sediment load as well as environmental impacts (deforestation, agriculture, hydroelectric reservoir, and alluvial gold mining) on natural Hg release, fish Hg bioaccumulation was no different between the two river habitats for nonpiscivorous species. In this small observational study only the species at the top of the food web (M. torquatus, Cichla spp, T. elongatus) showed higher mean Hg concentrations in the Rio Madeira than the dominantly wilderness habitat of the Rio Negro.

  10. Novel methodology for the study of mercury methylation and reduction in sediments and water using {sup 197}Hg radiotracer

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro Guevara, Sergio; Perez Catan, Soledad [Centro Atomico Bariloche, Laboratorio de Analisis por Activacion Neutronica, Bariloche (Argentina); Zizek, Suzana; Repinc, Urska; Jacimovic, Radojko; Horvat, Milena [Jozef Stefan Institute, Department of Environmental Sciences, Ljubljana (Slovenia)

    2007-03-15

    Mercury tracers are powerful tools that can be used to study mercury transformations in environmental systems, particularly mercury methylation, demethylation and reduction in sediments and water. However, mercury transformation studies using tracers can be subject to error, especially when used to assess methylation potential. The organic mercury extracted can be as low as 0.01% of the endogenous labeled mercury, and artefacts and contamination present during methylmercury (MeHg) extraction processes can cause interference. Solvent extraction methods based on the use of either KBr/H{sub 2}SO{sub 4} or HCl were evaluated in freshwater sediments using {sup 197}Hg radiotracer. Values obtained for the {sup 197}Hg tracer in the organic phase were up to 25-fold higher when HCl was used, which is due to the coextraction of {sup 197}Hg{sup 2+} into the organic phase during MeHg extraction. Evaluations of the production of MeHg gave similar results with both MeHg extraction procedures, but due to the higher Hg{sup 2+} contamination of the controls, the uncertainty in the determination was higher when HCl was used. The Hg{sup 2+} contamination of controls in the HCl extraction method showed a nonlinear correlation with the humic acid content of sediment pore water. Therefore, use of the KBr/H{sub 2}SO{sub 4} method is recommended, since it is free from these interferences. {sup 197}Hg radiotracer (T{sub 1/2} = 2.673 d) has a production rate that is about 50 times higher than that of {sup 203}Hg (T{sub 1/2} = 46.595 d), the most frequently used mercury radiotracer. Hence it is possible to obtain a similar level of performance to {sup 203}Hg when it is used it in short-term experiments and produced by the irradiation of {sup 196}Hg with thermal neutrons, using mercury targets with the natural isotopic composition. However, if the 0.15% natural abundance of the {sup 196}Hg isotope is increased, the specific activity of the {sup 197}Hg tracer can be significantly improved. In

  11. Photoelectric properties of defect chalcogenide HgGa2X4 (x=S, Se, Te)

    Science.gov (United States)

    Sharma, Ramesh; Dwivedi, Shalini; Sharma, Yamini

    2016-05-01

    We present results of ab initio study of ordered vacancy compounds of mercury. The electronic structure, charge density, optical and transport properties of the semiconductor family HgGa2X4 (X=S, Se, Te) are calculated using the full potential linearized augmented plane wave method which is based on the density functional theory. A direct bandgap is observed in these compounds, which reduces in the order S>Se>Te. From the density of states it is observed that there is strong hybridization of Hg-d, Ga-d and X-p states. The optical properties show a red shift with increasing size and atomic no. of the chalcogenide atoms. We have also reported the transport properties of mercury thiogallates for the first time. The selenide compound exhibits n-type nature whereas HgGa2S4 and HgGa2Te4 show p-type behavior. The power factor and ZT for the HGS increases at low temperatures, the figure of merit is highest for HgGa2Se4 (1.17) at 19 K.

  12. The characterization of HG10MNN and an evaluation of suitability for use in naval applications

    Energy Technology Data Exchange (ETDEWEB)

    Hawxhurst, K.L.; Westerberg, J.M., E-mail: m166918@usna.edu; Woertz, J.C., E-mail: woertz@usna.edu

    2016-06-15

    Highlights: • HG10MNN alloy showed good strength, hardness and ductility compared to NAB. • In air, four point bending fatigue tests suggest an endurance limit between 8 and 10 ksi. • As compared to NAB, HG10MNN has excellent casting and corrosion behavior. - Abstract: An initial mechanical evaluation and standard material characterization were conducted for the stainless steel alloy HG10MNN in order to evaluate its use in naval and marine applications. HG10MNN is a newly developed stainless steel designed for improved resistance to mechanical and thermal fatigue. This material could eventually replace the Nickel–Aluminum–Bronze (NAB) currently used in many naval propulsion systems, however, additional testing is required to validate the alloy's performance characteristics. Although stainless steels are commonly used in marine applications, there is insufficient HG10MNN documentation to permit its use in naval ship design. This investigation also involved an evaluation of castability and machinability to determine whether the material could be formed into the complex shapes required in a modern naval construction. Initial results showed that the alloy exhibits a fully austenitic microstructure in the as-cast condition, while maintaining acceptable mechanical properties and superior castability as compared to NAB.

  13. 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.

  14. 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).

  15. Mechanism of Hg-C Protonolysis in the Organomercurial Lyase MerB

    Energy Technology Data Exchange (ETDEWEB)

    Parks, Jerry M [ORNL; Guo, Hong [ORNL; Liang, Liyuan [ORNL; Miller, Susan M [ORNL; Summers, Anne O [ORNL; Smith, Jeremy C [ORNL

    2009-01-01

    Demethylation is a key reaction in global mercury cycling. The bacterial organomercurial lyase, MerB, catalyzes the demethylation of a wide range of organomercurials via Hg-C protonolysis. Two strictly conserved cysteine residues in the active site are required for catalysis, but the source of the catalytic proton and the detailed reaction mechanism have not been determined. Here, the two major proposed reaction mechanisms of MerB are investigated and compared using hybrid density functional theory calculations. A model of the active site was constructed from an X-ray crystal structure of the Hg(II)-bound MerB product complex. Stationary point structures and energies characterized for the Hg-C protonolysis of methylmercury rule out the direct protonation mechanism in which a cysteine residue delivers the catalytic proton directly to the organic leaving group. Instead, the calculations support a two-step mechanism in which Cys96 or Cys159 first donates a proton to Asp99, enabling coordination of two thiolates with R-Hg(II). At the rate-limiting transition state, Asp99 protonates the nascent carbanion in a trigonal planar, bis thiol-ligated R-Hg(II) species to cleave the Hg-C bond and release the hydrocarbon product. Reactions with two other substrates, vinylmercury and cis-2-butenyl-2-mercury, were also modeled, and the computed activation barriers for all three organomercurial substrates reproduce the trend in the experimentally observed enzymatic reaction rates. Analysis of atomic charges in the rate-limiting transition state structure using Natural Population Analysis shows that MerB lowers the activation free energy in the Hg-C protonolysis reaction by redistributing electron density into the leaving group and away from the catalytic proton.

  16. Hg(II Coordination Polymers Based on N,N’-bis(pyridine-4-ylformamidine

    Directory of Open Access Journals (Sweden)

    Wayne Hsu

    2016-04-01

    Full Text Available Reactions of N,N’-bis(pyridine-4-ylformamidine (4-Hpyf with HgX2 (X = Cl, Br, and I afforded the formamidinate complex {[Hg(4-pyf2]·(THF}n, 1, and the formamidine complexes {[HgX2(4-Hpyf]·(MeCN}n (X = Br, 2; I, 3, which have been structurally characterized by X-ray crystallography. Complex 1 is a 2D layer with the {44·62}-sql topology and complexes 2 and 3 are helical chains. While the helical chains of 2 are linked through N–H···Br hydrogen bonds, those of 3 are linked through self-complementary double N–H···N hydrogen bonds, resulting in 2D supramolecular structures. The 4-pyf- ligands of 1 coordinate to the Hg(II ions through one pyridyl and one adjacent amine nitrogen atoms and the 4-Hpyf ligands of 2 and 3 coordinate to the Hg(II ions through two pyridyl nitrogen atoms, resulting in new bidentate binding modes. Complexes 1–3 provide a unique opportunity to envisage the effect of the halide anions of the starting Hg(II salts on folding and unfolding the Hg(II coordination polymers. Density function theory (DFT calculation indicates that the emission of 1 is due to intraligand π→π * charge transfer between two different 4-pyf- ligands, whereas those of 2 and 3 can be ascribed to the charge transfer from non-bonding p-type orbitals of the halide anions to π * orbitals of the 4-pyf- ligands (n→π *. The gas sorption properties of the desolvated product of 1 are compared with the Cu analogues to show that the nature of the counteranion and the solvent-accessible volume are important in determining their adsorption capability.

  17. Detoxification of Hg(II) from aqueous and enzyme media: Pristine vs. tailored calcium alginate hydrogels.

    Science.gov (United States)

    Sarkar, Kangkana; Ansari, Zarina; Sen, Kamalika

    2016-10-01

    Calcium alginate (CA) hydrogels were tailored using phenolic compounds (PC) like, thymol, morin, catechin, hesperidin, during their preparation. The PC incorporated gels show modified surface features as indicated by scanning electron microscopic images (SEM). The rheological studies show that excepting the hesperidin incorporated gels all the other kinds including calcium alginate pristine have similar mechanical strength. The hesperidine incorporated CA gels had the maximum capacity to adsorb Hg. The Freundlich adsorption isotherms show higher values of adsorption capacity for all PC incorporated CA beads than the pristine CA (PCA). The hesperidin incorporated CA gels were found to show the best adsorption condition at neutral pH and an optimum contact time of 2.5h at 25°C. Considering the possibility of ingested Hg detoxification from human alimentary tract, the hesperidin and morin incorporated CA beads were further modified through incorporation of cod liver oil as the digestion time of fat in stomach is higher. In vitro uptake capacities of Hg in pepsin and pancreatin containing enzyme media were studied with hesperidin and morin incorporated beads and their corresponding fat incorporated beads also. In the pepsin medium, there was no uptake by hesperidin and fat-hesperidin incorporated beads, which is possibly due to the higher acidity of the medium. But in pancreatin medium Hg was taken up by both kinds of beads. Morin and morin-fat incorporated beads were efficient to uptake Hg from both the pepsin and pancreatin medium. The tailored CA beads may therefore serve as efficient scaffolds to rescue Hg ingested individuals.

  18. Accumulation of mercury in Typha domingensis under field conditions.

    Science.gov (United States)

    Lominchar, M A; Sierra, M J; Millán, R

    2015-01-01

    Typha species is a common wetland plant used in the treatment of urban and industrial effluents. But, despite their widespread implementation, there are not many studies based on the behaviour of this plant growing in an areas affected by mercury. The present work investigates the ability of Typha domingensis to accumulate mercury under field conditions. The study area was along the Valdeazogues river which flows through the Almadén mining district (Ciudad Real, Spain) that is considered the largest mercury reservoir in the world. The mercury concentration in different plant fractions was measured as well as the available and total concentration in the bottom sediments. The results showed that the highest mercury concentrations were found in the belowground organs. T. domingensis had a high efficiency to accumulate mercury in their organs although available metal concentrations in the environment did not exceed 0.16 mg kg(-1). Bioaccumulation factors (BAF) ranged between 121 and 3168 in roots. Furthermore, significant correlations were found between mercury concentration in all plant organs and Hg in sediments (both total and available). These results demonstrated that T. domingensis could be used as a biomonitor as well as in phytoextraction technology in areas affected by mercury. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Toxicity and Traces of Hg, Pb and Cd in the Hepatopancreas, Gills and Muscles of Perna viridis from Jakarta Bay, Indonesia.

    Science.gov (United States)

    Irnidayanti, Y

    2015-02-01

    Heavy metals contamination on the coast of Jakarta Bay has led to the level of pollution and can cause toxicity to organisms living in the sea, i.e., green mussels. Green mussels have the ability to detoxify metals entering their bodies. Their ability to accumulate metals is higher than other aquatic animals. This is due to their sedentary life which prevents them from avoiding the effects of pollution and their high tolerance to certain metals. The high concentration of metal content would be toxic to the cell because metal ions can act as oxidants and bind to organic and protein molecules. The results of the study showed that traces of heavy metals were detected in the hepatopancreas, gills, muscles and gonads organs of the mussels living in the waters of Muara Angke. Lead (Pb) and cadmium (Cd) were found in all four organs, while mercury (Hg) was not detected in the muscles. Traces of Hg and Cd were not detected in hepatopancreas, gills, muscles and gonads of green mussels in Panimbang, while Pb was detected by 0.00 1 in the male gonads and 0.01 in hepatopancreas. The concentration of Pb in the male gonads are still below the acceptable limit and concentration of Pb in the hepatopancreas is relatively equivalent to the acceptable limit. Metal detection in the organs above shows that the Muara Angke waters tend to be polluted and have an impact on the mussels weight loss as a result of heavy metal toxicity.

  20. HPLC-MS/MS analyses show that the near-Starchless aps1 and pgm leaves accumulate wild type levels of ADPglucose: further evidence for the occurrence of important ADPglucose biosynthetic pathway(s alternative to the pPGI-pPGM-AGP pathway.

    Directory of Open Access Journals (Sweden)

    Abdellatif Bahaji

    Full Text Available In leaves, it is widely assumed that starch is the end-product of a metabolic pathway exclusively taking place in the chloroplast that (a involves plastidic phosphoglucomutase (pPGM, ADPglucose (ADPG pyrophosphorylase (AGP and starch synthase (SS, and (b is linked to the Calvin-Benson cycle by means of the plastidic phosphoglucose isomerase (pPGI. This view also implies that AGP is the sole enzyme producing the starch precursor molecule, ADPG. However, mounting evidence has been compiled pointing to the occurrence of important sources, other than the pPGI-pPGM-AGP pathway, of ADPG. To further explore this possibility, in this work two independent laboratories have carried out HPLC-MS/MS analyses of ADPG content in leaves of the near-starchless pgm and aps1 mutants impaired in pPGM and AGP, respectively, and in leaves of double aps1/pgm mutants grown under two different culture conditions. We also measured the ADPG content in wild type (WT and aps1 leaves expressing in the plastid two different ADPG cleaving enzymes, and in aps1 leaves expressing in the plastid GlgC, a bacterial AGP. Furthermore, we measured the ADPG content in ss3/ss4/aps1 mutants impaired in starch granule initiation and chloroplastic ADPG synthesis. We found that, irrespective of their starch contents, pgm and aps1 leaves, WT and aps1 leaves expressing in the plastid ADPG cleaving enzymes, and aps1 leaves expressing in the plastid GlgC accumulate WT ADPG content. In clear contrast, ss3/ss4/aps1 leaves accumulated ca. 300 fold-more ADPG than WT leaves. The overall data showed that, in Arabidopsis leaves, (a there are important ADPG biosynthetic pathways, other than the pPGI-pPGM-AGP pathway, (b pPGM and AGP are not major determinants of intracellular ADPG content, and (c the contribution of the chloroplastic ADPG pool to the total ADPG pool is low.

  1. 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.

  2. Environmental impact of CO2, Rn, Hg degassing from the rupture zones produced by Wenchuan M s 8.0 earthquake in western Sichuan, China.

    Science.gov (United States)

    Zhou, Xiaocheng; Chen, Zhi; Cui, Yueju

    2016-10-01

    The concentrations and flux of CO2, (222)Radon (Rn), and gaseous elemental mercury (Hg) in soil gas were investigated based on the field measurements in June 2010 at ten sites along the seismic rupture zones produced by the May 12, 2008, Wenchuan M s 8.0 earthquake in order to assess the environmental impact of degassing of CO2, Rn and Hg. Soil gas concentrations of 344 sampling points were obtained. Seventy measurements of CO2, Rn and Hg flux by the static accumulation chamber method were performed. The results of risk assessment of CO2, Rn and Hg concentration in soil gas showed that (1) the concentration of CO2 in the epicenter of Wenchuan M s 8.0 earthquake and north end of seismic ruptures had low risk of asphyxia; (2) the concentrations of Rn in the north segment of seismic ruptures had high levels of radon, Maximum was up to level 4, according to Chinese code (GB 50325-2001); (3) the average geoaccumulation index I geo of soil Hg denoted the lack of soil contamination, and maximum values classified the soil gas as moderately to strongly polluted in the epicenter. The investigation of soil gas CO2, Rn and Hg degassing rate indicated that (1) the CO2 in soil gas was characterized by a mean [Formula: see text] of -20.4 ‰ and by a mean CO2 flux of 88.1 g m(-2) day(-1), which were in the range of the typical values for biologic CO2 degassing. The maximum of soil CO2 flux reached values of 399 g m(-2) day(-1) in the epicenter; (2) the soil Rn had higher exhalation in the north segment of seismic ruptures, the maximum reached value of 1976 m Bq m(-2) s(-1); (3) the soil Hg flux was lower, ranging from -2.5 to 18.7 n g m(-2) h(-1) and increased from south to north. The mean flux over the all profiles was 4.2 n g m(-2) h(-1). The total output of CO2 and Hg degassing estimated along seismic ruptures for a survey area of 18.17 km(2) were approximately 0.57 Mt year(-1) and 688.19 g year(-1). It is recommended that land-use planners should

  3. MicroCT vs. Hg porosimetry: microporosity in commercial stones

    Science.gov (United States)

    Fusi, N.; Martinez-Martinez, J.; Barberini, V.; Galimberti, L.

    2009-04-01

    Decay of rocks, due both to extrinsic and intrinsic factors, can show up in several different forms, such as neoformation of minerals, decohesion of grains and/or crystals, magnification of previous defects, new discontinuities, etc. Intrinsic factors include the type of material, its properties and microstructure, in particular porosity and microporosity. Extrinsic factors relate to atmosphere and usage of the material itself. Rock degradation has several heavy consequences for commercial stones, such as increase of permeability, loss of material, loss of mechanical strength; these consequences are of crucial importance for conservation of historical buildings. Aim of this study is to compare microporosity of some massive commercial stones by means of X ray microtomography, a non destructive technique, and Hg porosimetry. Nine of the most used Spanish limestones and dolostones have been analysed. The lithotypes have been chosen for their homogeneous mineralogical composition (calcitic or dolomitic) and for their low porosity; some of them have been widely used in Spain for historical buildings. Different lithotypes have been described in thin section: Ambarino (A) and Beige Serpiente (BS): brecciated dolostone, composed by microcrystalline dolomitic clasts, in a dolomitic and/or calcitic microcrystalline matrix. Amarillo Triana (AT): yellow dolomitic marble, with fissures filled up by calcite and Fe oxides. Blanco Alconera (BA): a white-pink homogeneous limestone, with veins. Blanco Tranco (BT): a homogeneous white calcitic marble, without any fissures and/or fractures. Crema Valencia (CV): a pinkish limestone, characterized by abundant stilolythes, filled mainly by quartz (80%) and kaolin (11%). Gris Macael (GM): a calcitic marble wiht darker and lighter beds, conferring a strong anisotropy. Rojo Cehegin (RC): a red fossiliferous limestone with white calcitic veins. Travertino Blanco (TB): a massive white calcitic travertine. Prismatic samples of about 2x1x1 cm

  4. Simultaneous removal of Hg0 and HCN from the yellow phosphorus tail gas

    Science.gov (United States)

    Li, Yanan; Wang, Xueqian

    2017-08-01

    Transition metal oxides supported on TiO2 were synthesized by a sol-gel method and implied to simultaneous removal of Hg0 and HCN under low temperature and micro-oxygen conditions. The results show that catalysts that modified by manganese oxide have superior catalytic oxidation activity for both the removal of elemental mercury (Hg0) and HCN. Furthermore, the O2 can promote in the removal reaction process. The fresh and used catalysts were characterized by BET and XPS. The catalyst characterization indicated that the catalyst possessed a large specific surface area and the chemisorbed oxygen participated in the catalytic oxidation reaction. The MnOx/TiO2 catalyst was demonstrated to a good catalytic oxidant for simultaneous removal of elemental mercury (Hg0) and HCN under micro-oxygen conditions.

  5. Turn-On Fluorescent Chemosensor for Hg2+ Based on Multivalent Rhodamine Ligands

    Directory of Open Access Journals (Sweden)

    Xuemei Wang

    2012-12-01

    Full Text Available Rhodamine-based fluorescent chemosensors 1 and 2 exhibit selective fluorescence enhancement to Fe3+ and Hg2+ over other metal ions at 580 nm in CH3CN/H2O (3/1, v/v solution. Bis(rhodamine chemosensor 1, under optimized conditions (CH3CN/HEPES buffer (0.02 M, pH = 7.0 (95/5, v/v, shows a high selectivity and sensitivity to Hg2+, with a linear working range of 0–50 μM, a wide pH span of 4–10, and a detection limit of 0.4 μM Hg2+.

  6. 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.

  7. Textured α-HgI2 ceramics for sensitive X-ray detection

    Science.gov (United States)

    Rault, Mathieu; Binet, Laurent; Gourier, Didier; Wallez, Gilles; Ponpon, Jean-Pierre; Biava, Dominique; Inglese, Jean-Marc; Barboux, Philippe

    2016-02-01

    In the prospect of manufacturing ionizing radiation detectors, dense ceramics of α-HgI2 with a strong preferred orientation were elaborated. X-ray diffraction showed that most crystallites exhibited their crystal c-axis perpendicular to the ceramic plane, which should be favorable for optimum electrical transport properties. Dark current densities about 2 nA mm-2 (under 0.2 V μm-1 bias) were measured and were shown to arise mostly from the release of carriers from trap defects (Poole-Frenkel emission). The X-ray sensitivity ≈1600 nC mGy-1 cm-2 and the μτ value ≈ 3 × 10-5 cm2 V-1 were comparable to those of other forms of polycrystalline HgI2. The HgI2 ceramics also exhibited a perfectly linear response as a function of the X-ray dose.

  8. Pattern of mercury accumulation in different tissues of migratory and resident birds: Western reef heron (Egretta gularis) and Siberian gull (Larus heuglini) in Hara International Wetland-Persian Gulf.

    Science.gov (United States)

    Majidi, Yousef; Bahramifar, Nader; Ghasempouri, Seyed Mahmoud

    2015-01-01

    The Hara Mangrove Forest of the Persian Gulf is undergoing increasing pollution from industrial, municipal, and petroleum sources; however, little research in ecotoxicology has been carried out in this ecosystem. In the present study, mercury distribution and accumulation were investigated in muscle, liver, kidney, and feather of the resident Western reef heron (n = 15) and the migratory Siberian gull (n = 15). We also evaluated the relation between Hg concentrations, sex, and age (juvenile vs. adult). Results showed that the highest concentrations of Hg were recorded in the feather (35 ± 0.14-3.0 ± 0.27 mg kg(-1) dw) and at 3.7-, 1.6-, and 1.3-fold in muscle, kidney, and liver, respectively. Concentrations of mercury in tissues of migratory birds were two times higher than in resident birds; geographical differences and feeding habits were used to explain these variations. We found a weak relationship between Hg concentrations in feathers and internal tissues (r ≤ 0.50); conversely, liver presented strong positive correlations with other soft tissues, especially kidney (p > 0.05; r = 0.82). Results showed that sex and age have no significant effects on T-Hg accumulation in these birds (p > 0.05; r mercury pollution in this region.

  9. 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).

  10. Highly Sensitive Fluorescence Probe Based on Functional SBA-15 for Selective Detection of Hg2+

    Directory of Open Access Journals (Sweden)

    Wang Xiaoyu

    2010-01-01

    Full Text Available Abstract An inorganic–organic hybrid fluorescence chemosensor (DA/SBA-15 was prepared by covalent immobilization of a dansylamide derivative into the channels of mesoporous silica material SBA-15 via (3-aminopropyltriethoxysilane (APTES groups. The primary hexagonally ordered mesoporous structure of SBA-15 was preserved after the grafting procedure. Fluorescence characterization shows that the obtained inorganic–organic hybrid composite is highly selective and sensitive to Hg2+ detection, suggesting the possibility for real-time qualitative or quantitative detection of Hg2+ and the convenience for potential application in toxicology and environmental science.

  11. 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。

  12. Effects of an Applied Magnetic Field on the Directional Solidification of Hg(1-x)Zn(x)Se Alloys

    Science.gov (United States)

    Cobb, S. D.; Lehoczky, S. L.; Szofran, F. R.; Jones, K. S.

    1999-01-01

    Directionally solidified Hg(0.9)Zn(0.1)Se alloys were studied as an alternative to HgCdTe for the detection of electromagnetic radiation because of predicted improvements in lattice stability. Several boules were grown using a modified Bridgman-Stockbarger method and in an applied magnetic field. Axial compositional profiles showed mass transfer was primarily diffusion controlled. Radial compositional variations were greatly reduced when solidification occurred in an applied magnetic field. Microstructural characteristics and dislocation etch pit densities were greatly improved over HgTe based alloys. The extreme importance of processing conditions on defect generation was illustrated by comparing ampoule configurations and thermal profiles.

  13. Synthesis and characterization of La11+xHg45-x and RE11Hg44.5 (RE = Nd, Sm) as hettotypes of the Sm11Cd45 structure type

    Science.gov (United States)

    Tambornino, Frank; Schwärzer, Kuno; Hoch, Constantin

    2016-10-01

    The mercury-rich amalgams La11+xHg45-x and RE11Hg44.5 (space group F4bar3m (No. 216), La11+xHg45-x : a = 21.9342(19) Å, RE = Nd: a = 21.7384(14) Å; RE = Sm: a = 21.6555(4) Å), were synthesized by dissolving the respective rare earth metals in a mercury surplus and subsequently distilling off the excess. The compounds were characterized by single crystal and powder X-ray methods together with ab-initio band structure calculations. Both crystal structures deviate significantly and in different ways from their common aristotype, the Sm11Cd45 structure type. In La11+xHg45-x (x = 0.7(1)) two crystallographic sites show mixed occupancy, whereas in RE11Hg44.5 one of the Hg positions is fully unoccupied. Their band structures exhibit typical broad Hg d states at low energies, and a strong mixing of s and p states indicates a mercury sublattice with high connectivity.

  14. Heavy metal tolerance (Cr, Ag and Hg in bacteria isolated from sewage

    Directory of Open Access Journals (Sweden)

    Agostinho A. de Lima e Silva

    2012-12-01

    Full Text Available Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr, silver (Ag and mercury (Hg. Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%. Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerantBacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr. Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria.

  15. Heavy metal tolerance (Cr, Ag AND Hg) in bacteria isolated from sewage

    Science.gov (United States)

    Lima de Silva, Agostinho A.; de Carvalho, Márcia A. Ribeiro; de Souza, Sérgio A. L; Dias, Patrícia M. Teixeira; da Silva Filho, Renato G.; de Meirelles Saramago, Carmen S.; de Melo Bento, Cleonice A.; Hofer, Ernesto

    2012-01-01

    Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr), silver (Ag) and mercury (Hg). Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%). Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerant Bacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr). Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria. PMID:24031994

  16. 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 ...

  17. 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

  18. Catalytic oxidation of Hg(0) by MnOx-CeO2/γ-Al2O3 catalyst at low temperatures.

    Science.gov (United States)

    Wang, Pengying; Su, Sheng; Xiang, Jun; You, Huawei; Cao, Fan; Sun, Lushi; Hu, Song; Zhang, Yun

    2014-04-01

    MnOx-CeO2/γ-Al2O3 (MnCe) selective catalytic reduction (SCR) catalysts prepared by sol-gel method were employed for low-temperature Hg(0) oxidation on a fixed-bed experimental setup. BET, XRD and XPS were used to characterize the catalysts. MnCe catalysts exhibited high Hg(0) oxidation activity at low temperatures (100-250 °C) under the simulated flue gas (O2, CO2, NO, SO2, HCl, H2O and balanced with N2). Only a small decrease in mercury oxidation was observed in the presence of 1200 ppm SO2, which proved that the addition of Ce helped resist SO2 poisoning. An enhancing effect of NO was observed due to the formation of multi-activity NOx species. The presence of HCl alone had excellent Hg(0) oxidation ability, while 10 ppm HCl plus 5% O2 further increased Hg(0) oxidation efficiency to 100%. Hg(0) oxidation on the MnCe catalyst surface followed the Langmiur-Hinshelwood mechanism, where reactions took place between the adsorbed active species and adsorbed Hg(0) to form Hg(2+). NH3 competed with Hg(0) for active sites on the catalyst surface, hence inhibiting Hg(0) oxidation. This study shows the feasibility of a single-step process integrating low-temperature SCR and Hg(0) oxidation from the coal combustion flue gas.

  19. Thermal Cycle Annealing and its Application to Arsenic-Ion Implanted HgCdTe

    Science.gov (United States)

    2014-06-26

    doping profile, as shown in Figure 3. The TCA treatment on the unimplanted epilayers showed an exponential defect reduction proportional to the...Chamonal, P. Castelein, J. Zanatta, M. Tchagaspanian, A. Papon, J. Barnes, F. Henry, S. Gout , G. Bourgeois, C. Pautet and P. Fougeres, "HgCdTe FPAs

  20. 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

  1. Comparative proteomic study and functional analysis of translationally controlled tumor protein in rice roots under Hg2+ stress

    Institute of Scientific and Technical Information of China (English)

    Feijuan Wang; Yongshen Shang; Ling Yang; Cheng Zhu

    2012-01-01

    So far,very little is known about mercury stress-induced intercellular metabolic changes in rice roots at the proteome level.To investigate the response of rice roots to mercury stress,changes in protein expression in rice roots were analyzed using a comparative proteomics approach.Six-leaf stage rice seedlings were treated with 50 μmol/L HgCl2 for 3 hr; 29 protein spots showed a significant changes in abundance under stress when compared with the Hg2+-tolerant rice mutant and wild type (Zhonghua 11).Furthermore,all these protein spots were identified by mass spectrometry to match 27 diverse protein species.The identified proteins were involved in several processes,including stress response,redox homeostasis,signal transduction,regulation and metabolism; some were found to be cellular structure proteins and a few were unknown.Among the up-regulated proteins,OsTCTP (translationally controlled tumor protein) was chosen to perform hetereologous expression in yeast which was presumed to participate in the Hg2+ tolerance of rice,providing evidence for its role in alleviating Hg2+ damage.Among the many tests,we found that OsTCTP-overexpressed yeast strains were more resistant to Hg2+ than wild-type yeast.Thus,we propose that OsTCTP contributes to Hg2+ resistance.Here we present,for the first time,the functional characterization of OsTCTP in connection with Hg2+ stress in plants.

  2. Evaluation on the stability of Hg in ABS disk CRM during measurements by wavelength dispersive X-ray fluorescence spectrometry.

    Science.gov (United States)

    Ohata, Masaki; Kidokoro, Toshihiro; Hioki, Akiharu

    2012-01-01

    The stability of Hg in an acrylonitrile-butadiene-styrene disk certified reference material (ABS disk CRM, NMIJ CRM 8116-a) during measurements by wavelength dispersion X-ray fluorescence (WD-XRF) analysis was evaluated in this study. The XRF intensities of Hg (L(α)) and Pb (L(α)) as well as the XRF intensity ratios of Hg (L(α))/Pb (L(α)) observed under different X-ray tube current conditions as well as their irradiation time were examined to evaluate the stability of Hg in the ABS disk CRM. The observed XRF intensities and the XRF intensity ratios for up to 32 h of measurements under 80 mA of X-ray tube current condition were constant, even though the surface of the ABS disk CRM was charred by the X-ray irradiation with high current for a long time. Moreover, the measurements on Hg and Pb in the charred disks by an energy dispersive XRF (ED-XRF) spectrometer showed constant XRF intensity ratios of Hg (L(α))/Pb (L(α)). From these results, Hg in the ABS disk CRM was evaluated to be sufficiently stable for XRF analysis.

  3. Papillary thyroid carcinoma shows elevated levels of 2-hydroxyglutarate.

    Science.gov (United States)

    Rakheja, Dinesh; Boriack, Richard L; Mitui, Midori; Khokhar, Shama; Holt, Shelby A; Kapur, Payal

    2011-04-01

    Elevated levels of D: -2-hydroxyglutarate (D: -2-HG) occur in gliomas and myeloid leukemias associated with mutations of IDH1 and IDH2. L: -2-Hydroxyglutaric aciduria, an inherited metabolic disorder, predisposes to brain tumors. Therefore, we asked whether sporadic cancers, without IDH1 or IDH2 hot-spot mutations, show elevated 2-hydroxyglutarate levels. We retrieved 15 pairs of frozen papillary thyroid carcinoma (PTC) and adjacent non-neoplastic thyroid, and 14 pairs of hyperplastic nodule (HN) and adjacent non-hyperplastic thyroid. In all lesions, exon 4 sequencing confirmed the absence of known mutations of IDH1 and IDH2. We measured 2-hydroxyglutarate by liquid chromatography-tandem mass spectrometry. Compared to normal thyroid, PTCs had significantly higher D: -2-HG and L: -2-hydroxyglutarate (L: -2-HG) levels, and compared to HNs, PTCs had significantly higher D: -2-HG levels. D: -2-HG/L: -2-HG levels were not significantly different between HNs and normal thyroid. Further studies should clarify if elevated 2-hydroxyglutarate in PTC may be useful as cancer biomarker and evaluate the role of 2-hydroxyglutarate in cancer biology.

  4. Colorimetric and fluorescent sensor for selective sensing of Hg{sup 2+} ions in semi aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Udhayakumari, Duraisamy [Organic and Polymer Synthesis Laboratory, Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015 (India); Velmathi, Sivan, E-mail: velmathis@nitt.edu [Organic and Polymer Synthesis Laboratory, Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015 (India)

    2013-04-15

    A highly sensitive and selective detection of Hg{sup 2+} ion with simple salophen probe was developed. In DMSO: water (40:60, v/v) solution, Hg{sup 2+} ions coordinate with imine and shows color turn-off from yellow to colorless. Receptor 1 showed its ability for sensing Hg{sup 2+} cations sensitively through three channels: colorimetric, UV–vis and fluorescence spectroscopy. Hg{sup 2+} ions coordinate to the imine (Receptor 1) through NONO binding site forming 1:1 complex. It exhibits fluorescent 'Turn-on' behavior based on solvent polarity. The detection limit of our receptor with mercury is 1 μg L{sup −1}. -- Graphical abstract: A highly sensitive and rapid detection of Hg{sup 2+} with simple salophen probe was developed. In DMSO: water (40:60, v/v) solution, Hg{sup 2+} ions coordinate with imine and shows color turn-off from yellow to colorless. Receptor 1 showed its ability for sensing Hg{sup 2+} cations sensitively through three channels: colorimetric, UV–vis and Fluorescence Spectroscopy. Hg{sup 2+} ions coordinate to the imine (Receptor 1) through the NONO binding site forming 1:1 complex. It exhibits fluorescent 'Turn-on' behavior based on solvent polarity. The detection limit of our receptor with mercury is 1 μg L{sup −1}. Highlights: ► Hg{sup 2+} ions coordinate with imine and shows color turn-off from yellow to colorless. ► The binding constant of the receptor 1 (DMSO) with Hg{sup 2+} ion (DMSO) is 1.35×10{sup 5}. ► Hg{sup 2+} ions coordinate to the imine through NONO binding site forming 1:1 complex. ► The receptor 1 shows fluorescent 'Turn-on' behavior based on solvent polarity. ► The detection limit of receptor 1 with mercury is 1 μg L{sup −1}.

  5. Application of Epithermal Neutron Activation Analysis to Investigate Accumulation and Adsorption of Mercury by Spirulina platensis Biomass

    CERN Document Server

    Mosulishvili, L M; Khizanishvili, A I; Frontasyeva, M V; Kirkesali, E I; Aksenova, N G

    2004-01-01

    Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamics of accumulation of Hg was investigated over several days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was carried out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations \\sim 100 {\\mu}g/l.

  6. Effect of a boron implantation on the electrical properties of epitaxial HgCdTe with different material composition

    Science.gov (United States)

    Lyapunov, D. V.; Pishchagin, A. A.; Grigoryev, D. V.; Korotaev, A. G.; Voitsekhovskii, A. V.; Kokhanenko, A. P.; Iznin, I. I.; Savytskyy, H. V.; Bonchik, A. U.; Dvoretskii, S. A.; Mikhailov, N. N.

    2016-08-01

    In this work the experimental results of investigations of the dynamics of accumulation and spatial distribution of electrically active radiation defects when irradiating epitaxial films of Hg1-xCdxTe (MCT) with different material composition (x). The films, grown by molecular beam epitaxy (MBE) were irradiated by B ions at room temperature in the radiation dose range 1012 -1015 ions/cm2 and with ion energy 100 keV. The results give the differences in implantation profiles, damage accumulation and electrical properties as a function of the material composition of the films.

  7. 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.

  8. Volatile (As and Hg) and non-volatile (Pb and Cd) toxic heavy metals analysis in rhizome of Zingiber officinale collected from different locations of North Western Himalayas by Atomic Absorption Spectroscopy.

    Science.gov (United States)

    Gupta, S; Pandotra, P; Gupta, A P; Dhar, J K; Sharma, G; Ram, G; Husain, M K; Bedi, Y S

    2010-10-01

    Ginger is an important ingredient of spice and herbals. The monitoring of toxic heavy metals in the rhizome of ginger is important for protecting public health against the hazards of metal toxicity. The concentration of volatile and non-volatile metals (As, Hg, Pb and Cd), in the soil and rhizome of Zingiber officinale were analyzed using AAS. Soil analysis profile showed uniformity in the metal contents, in active root zone and subsoil, except mercury, which was present in higher quantity in one, out of the four sectors, of the field. The infield metal content in the soil in increasing order was, cadmium < arsenic < lead < mercury. In ginger rhizome the volatile toxic heavy metals arsenic (As) and mercury (Hg) varied from not detected to 0.13 μg/g and 0.01 to 0.42 μg/g, respectively. The non-volatile metals lead (Pb) and cadmium (Cd) ranged from 0.06 to 0.64 μg/g and 0.002 to 0.03 μg/g, respectively(.) The results illustrated the findings that soil is the major but not the only source of metal accumulation in the plants. In our study, the volatile metal content (As, Hg) was found more in rhizomes collected from Himachal Pradesh while the non-volatile metals were predominant in samples from Uttarakhand.

  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. 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)

  11. 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.

  12. 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

  13. MeHg Developing Exposure Causes DNA Double-Strand Breaks and Elicits Cell Cycle Arrest in Spinal Cord Cells

    Directory of Open Access Journals (Sweden)

    Fabiana F. Ferreira

    2015-01-01

    Full Text Available The neurotoxicity caused by methylmercury (MeHg is well documented; however, the developmental neurotoxicity in spinal cord is still not fully understood. Here we investigated whether MeHg affects the spinal cord layers development. Chicken embryos at E3 were treated in ovo with 0.1 μg MeHg/50 μL saline solution and analyzed at E10. Thus, we performed immunostaining using anti-γ-H2A.X to recognize DNA double-strand breaks and antiphosphohistone H3, anti-p21, and anti-cyclin E to identify cells in proliferation and cell cycle proteins. Also, to identify neuronal cells, we used anti-NeuN and anti-βIII-tubulin antibodies. After the MeHg treatment, we observed the increase on γ-H2A.X in response to DNA damage. MeHg caused a decrease in the proliferating cells and in the thickness of spinal cord layers. Moreover, we verified that MeHg induced an increase in the number of p21-positive cells but did not change the cyclin E-positive cells. A significantly high number of TUNEL-positive cells indicating DNA fragmentation were observed in MeHg-treated embryos. Regarding the neuronal differentiation, MeHg induced a decrease in NeuN expression and did not change the expression of βIII-tubulin. These results showed that in ovo MeHg exposure alters spinal cord development by disturbing the cell proliferation and death, also interfering in early neuronal differentiation.

  14. MeHg Developing Exposure Causes DNA Double-Strand Breaks and Elicits Cell Cycle Arrest in Spinal Cord Cells

    Science.gov (United States)

    Ferreira, Fabiana F.; Ammar, Dib; Bourckhardt, Gilian F.; Kobus-Bianchini, Karoline; Müller, Yara M. R.; Nazari, Evelise M.

    2015-01-01

    The neurotoxicity caused by methylmercury (MeHg) is well documented; however, the developmental neurotoxicity in spinal cord is still not fully understood. Here we investigated whether MeHg affects the spinal cord layers development. Chicken embryos at E3 were treated in ovo with 0.1 μg MeHg/50 μL saline solution and analyzed at E10. Thus, we performed immunostaining using anti-γ-H2A.X to recognize DNA double-strand breaks and antiphosphohistone H3, anti-p21, and anti-cyclin E to identify cells in proliferation and cell cycle proteins. Also, to identify neuronal cells, we used anti-NeuN and anti-βIII-tubulin antibodies. After the MeHg treatment, we observed the increase on γ-H2A.X in response to DNA damage. MeHg caused a decrease in the proliferating cells and in the thickness of spinal cord layers. Moreover, we verified that MeHg induced an increase in the number of p21-positive cells but did not change the cyclin E-positive cells. A significantly high number of TUNEL-positive cells indicating DNA fragmentation were observed in MeHg-treated embryos. Regarding the neuronal differentiation, MeHg induced a decrease in NeuN expression and did not change the expression of βIII-tubulin. These results showed that in ovo MeHg exposure alters spinal cord development by disturbing the cell proliferation and death, also interfering in early neuronal differentiation. PMID:26793240

  15. 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.

  16. Accumulation of mercury and cadmium in rice from paddy soil near a mercury mine.

    Science.gov (United States)

    Li, W C; Ouyang, Y; Ye, Z H

    2014-11-01

    Paddy soil and rice (Oryza sativa L.) in the Wanshan mining area in Guizhou Province, China, have been contaminated by toxic trace metals such as cadmium (Cd) and mercury (Hg). The present study examined correlations between the types and physicochemical parameters of the soil and the contents of trace metals and the different forms of Hg in rice. The health risks of consuming contaminated rice from the Wanshan mining area were also assessed. Sequential extraction procedures were used to investigate the chemical behavior of Hg in the soil. The results showed that Hg and Cd were the most abundant trace metals in the Wanshan mining area. The toxic methylmercury (MeHg) content was substantial in brown rice, and the total amounts of total Hg (THg), diethylenetriaminepentaacetic acid-Hg, and water-soluble Hg varied in the rhizosphere and non-rhizosphere soils. An antagonistic interaction between Mn in brown rice, straw, and husk and MeHg in brown rice was also shown. An analysis of calculated dietary intake, target hazard quotients, and hazard indexes showed a potential risk of transferring Hg, MeHg, and Cd to humans when rice from the Wanshan mining area is consumed. Therefore, it must be concluded that consuming contaminated rice near the Wanshan mining area is a potential threat to human health.

  17. A new approach to understand methylmercury (CH3Hg) sources and transformation pathways: Compound-specific carbon stable isotope analysis by GC-C-IRMS

    Science.gov (United States)

    Baya, P. A.; Point, D.; Amouroux, D. P.; Lebreton, B.; Guillou, G.

    2015-12-01

    Methylmercury (CH3Hg) is a potent neurotoxin which is readily assimilated by organisms and bio-accumulates in aquatic food webs. In humans, consumption of CH3Hg contaminated marine fish is the major route of mercury exposure. However, our understanding of CH3Hg transformation pathways is still incomplete. To close this knowledge gap, we propose to explore the stable carbon isotopic composition (δ13C) of the methyl group of CH3Hg for a better understanding of its sources and transformation mechanisms. The method developed for the determination of the δ13C value of CH3Hg in biological samples involves (i) CH3Hg selective extraction, (ii) derivatization, and (iii) separation by gas chromatography (GC) prior to analysis by combustion isotope ratio mass spectrometry (C-IRMS). We present the figures of merit of this novel method and the first δ13C signatures for certified materials (ERM-CE464, BCR414) and biological samples at different marine trophic levels (i.e., tuna fish, zooplankton). The implications of this new approach to trace the pathways associated with Hg methylation and the mechanisms involved will be discussed.

  18. Inhibition of Zn(II binding type IA topoisomerases by organomercury compounds and Hg(II.

    Directory of Open Access Journals (Sweden)

    Bokun Cheng

    Full Text Available Type IA topoisomerase activities are essential for resolving DNA topological barriers via an enzyme-mediated transient single strand DNA break. Accumulation of topoisomerase DNA cleavage product can lead to cell death or genomic rearrangement. Many antibacterial and anticancer drugs act as topoisomerase poison inhibitors that form stabilized ternary complexes with the topoisomerase covalent intermediate, so it is desirable to identify such inhibitors for type IA topoisomerases. Here we report that organomercury compounds were identified during a fluorescence based screening of the NIH diversity set of small molecules for topoisomerase inhibitors that can increase the DNA cleavage product of Yersinia pestis topoisomerase I. Inhibition of relaxation activity and accumulation of DNA cleavage product were confirmed for these organomercury compounds in gel based assays of Escherichia coli topoisomerase I. Hg(II, but not As(III, could also target the cysteines that form the multiple Zn(II binding tetra-cysteine motifs found in the C-terminal domains of these bacterial topoisomerase I for relaxation activity inhibition. Mycobacterium tuberculosis topoisomerase I activity is not sensitive to Hg(II or the organomercury compounds due to the absence of the Zn(II binding cysteines. It is significant that the type IA topoisomerases with Zn(II binding domains can still cleave DNA when interfered by Hg(II or organomercury compounds. The Zn(II binding domains found in human Top3α and Top3β may be potential targets of toxic metals and organometallic complexes, with potential consequence on genomic stability and development.

  19. Ecological and biological determinants of methylmercury accumulation in tropical coastal fish.

    Science.gov (United States)

    Seixas, Tércia G; Moreira, Isabel; Malm, Olaf; Kehrig, Helena A

    2013-02-01

    This research investigated whether environmental conditions, biological fish characteristics and anthropogenic impacts influenced mercury (Hg) assimilation into the muscle tissue of two fish species from two Brazilian bays, Ilha Grande Bay and Guanabara Bay. Fish and superficial water were collected in different periods. Hg was determined by CV-AAS. Methylmercury (MeHg) was identified and quantified by ECD-GC. Chlorophyll a concentrations in the water column indicated that Ilha Grande Bay and Guanabara Bay were oligotrophic and eutrophic, respectively. Hg in fish ranged from 2.10 to 870.17 μg kg(-1) dry wt. in Ilha Grande Bay and 40.90 to 809.24 μg kg(-1) dry wt. in Guanabara Bay. Slight differences were found between the length-normalized Hg concentrations and its percent of Hg in a voracious predator from the bays. In Guanabara Bay, where the presence of a chlor-alkali plant causes Hg input, the iliophagous fish species showed the highest length-normalized Hg concentrations and the voracious predator the lowest. Iliophagous fish is consumed by voracious predator and, consequently, acts as their MeHg food supply. Iliophagous fish from Ilha Grande Bay presented a higher percent of MeHg (80.0 %) than specimens from Guanabara Bay (54.5 %). This fact suggests that more MeHg was transferred from iliophagous fish to voracious predator in Ilha Grande Bay. At Guanabara Bay, the bioproduction is greater than that at Ilha Grande Bay, presenting the highest biomass in it ecosystem, which may subsequently dilute Hg and reduce its availability to the biota; i.e., influencing in Hg and MeHg availability throughout the food chain. Consequently, more MeHg is available in the aquatic environment of Ilha Grande Bay.

  20. Investigation of biogeochemical controls on the formation, uptake and accumulation of methylmercury in rice paddies in the vicinity of a coal-fired power plant and a municipal solid waste incinerator in Taiwan.

    Science.gov (United States)

    Su, Yen-Bin; Chang, Wei-Chun; Hsi, Hsing-Cheng; Lin, Chu-Ching

    2016-07-01

    Recent studies have shown that rice consumption is another critical route of human exposure to methylmercury (MeHg), the most toxic and accumulative form of mercury (Hg) in the food web. Yet, the mechanisms that underlie the production and accumulation of MeHg in the paddy ecosystem are still poorly understood. In 2013 and 2014, we conducted field campaigns and laboratory experiments over a rice growing season to examine Hg and MeHg cycling, as well as associated biogeochemistry in a suite of paddies close to a municipal solid waste incinerator and a coal-fired power plant station in Taiwan. Concentrations of total Hg and MeHg in paddy soil and rice grain at both sites were low and found not to exceed the control standards for farmland soil and edible rice in Taiwan. However, seasonal variations of MeHg concentrations observed in pore water samples indicate that the in situ bioavailability of inorganic Hg and activity of Hg-methylating microbes in the rhizosphere increased from the early-season and peaked at the mid-season, presumably due to the anoxia created under flooded conditions and root exudation of organic compounds. The presence of Hg-methylators was also confirmed by the hgcA gene detected in all root soil samples. Subsequent methylation tests performed by incubating the root soil with inorganic Hg and an inhibitor or stimulant specific for certain microbes further revealed that sulfate-reducers might have been the principal Hg-methylting guild at the study sites. Interestingly, results of hydroponic experiments conducted by cultivating rice in a defined nutrient solution amended with fixed MeHg and varying levels of MeHg-binding ligands suggested that chemical speciation in soil pore water may play a key role in controlling MeHg accumulation in rice, and both passive and active transport pathways seem to take place in the uptake of MeHg in rice roots.

  1. Propensity to metal accumulation and oxidative stress responses of two benthic species (Cerastoderma edule and Nephtys hombergii): are tolerance processes limiting their responsiveness?

    Science.gov (United States)

    Marques, Ana; Piló, David; Araújo, Olinda; Pereira, Fábio; Guilherme, Sofia; Carvalho, Susana; Santos, Maria Ana; Pacheco, Mário; Pereira, Patrícia

    2016-05-01

    The chronic exposure of benthic organisms to metals in sediments can lead to the development of tolerance mechanisms, thus diminishing their responsiveness. This study aims to evaluate the accumulation profiles of V, Cr, Co, Ni, As, Cd, Pb and Hg and antioxidant system responses of two benthic organisms (Cerastoderma edule, Bivalvia; Nephtys hombergii, Polychaeta). This approach will provide clarifications about the ability of each species to signalise metal contamination. Organisms of both species were collected at the Tagus estuary, in two sites with distinct contamination degrees (ALC, slightly contaminated; BAR, highly contaminated). Accordingly, C. edule accumulated higher concentrations of As, Pb and Hg at BAR compared to ALC. However, antioxidant responses of C. edule were almost unaltered at BAR and no peroxidative damage occurred, suggesting adjustment mechanisms to the presence of metals. In contrast, N. hombergii showed a minor propensity to metal accumulation, only signalising spatial differences for As and Pb and accumulating lower concentrations of metals than C. edule. The differences in metal accumulation observed between species might be due to their distinctive foraging behaviour and/or the ability of N. hombergii to minimise the metal uptake. Despite that, the accumulation of As and Pb was on the basis of the polychaete antioxidant defences inhibition at BAR, including CAT, SOD, GR and GPx. The integrated biomarker response index (IBRv2) confirmed that N. hombergii was more affected by metal exposure than C. edule. In the light of current findings, in field-based studies, the information of C. edule as a bioindicator should be complemented by that provided by another benthic species, since tolerance mechanisms to metals can hinder a correct diagnosis of sediment contamination and of the system's health. Overall, the present study contributed to improve the lack of fundamental knowledge of two widespread and common estuarine species, providing

  2. Propensity to metal accumulation and oxidative stress responses of two benthic species (Cerastoderma edule and Nephtys hombergii): are tolerance processes limiting their responsiveness?

    KAUST Repository

    Marques, Ana

    2016-02-24

    The chronic exposure of benthic organisms to metals in sediments can lead to the development of tolerance mechanisms, thus diminishing their responsiveness. This study aims to evaluate the accumulation profiles of V, Cr, Co, Ni, As, Cd, Pb and Hg and antioxidant system responses of two benthic organisms (Cerastoderma edule, Bivalvia; Nephtys hombergii, Polychaeta). This approach will provide clarifications about the ability of each species to signalise metal contamination. Organisms of both species were collected at the Tagus estuary, in two sites with distinct contamination degrees (ALC, slightly contaminated; BAR, highly contaminated). Accordingly, C. edule accumulated higher concentrations of As, Pb and Hg at BAR compared to ALC. However, antioxidant responses of C. edule were almost unaltered at BAR and no peroxidative damage occurred, suggesting adjustment mechanisms to the presence of metals. In contrast, N. hombergii showed a minor propensity to metal accumulation, only signalising spatial differences for As and Pb and accumulating lower concentrations of metals than C. edule. The differences in metal accumulation observed between species might be due to their distinctive foraging behaviour and/or the ability of N. hombergii to minimise the metal uptake. Despite that, the accumulation of As and Pb was on the basis of the polychaete antioxidant defences inhibition at BAR, including CAT, SOD, GR and GPx. The integrated biomarker response index (IBRv2) confirmed that N. hombergii was more affected by metal exposure than C. edule. In the light of current findings, in field-based studies, the information of C. edule as a bioindicator should be complemented by that provided by another benthic species, since tolerance mechanisms to metals can hinder a correct diagnosis of sediment contamination and of the system’s health. Overall, the present study contributed to improve the lack of fundamental knowledge of two widespread and common estuarine species, providing

  3. 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.

  4. 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...

  5. 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...

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Mercury accumulation in sea lamprey (Petromyzon marinus) from Lake Huron

    Science.gov (United States)

    Madenjian, Charles P.; Johnson, Nicholas S.; Siefkes, Michael J.; Dettmers, John M.; Blum, Joel D.; Johnson, Marcus W.

    2014-01-01

    We determined whole-fish total mercury (Hg) concentrations of 40 male and 40 female adult sea lampreys (Petromyzon marinus) captured in the Cheboygan River, a tributary to Lake Huron, during May 2011. In addition, bioenergetics modeling was used to explore the effects of sex-related differences in activity and resting (standard) metabolic rate (SMR) on mercury accumulation. The grand mean for Hg concentrations was 519 ng/g (standard error of the mean = 46 ng/g). On average, males were 16% higher in Hg concentration than females. Bioenergetics modeling results indicated that 14% higher activity and SMR in males would account for this observed sex difference in Hg concentrations. We concluded that the higher Hg concentration in males was most likely due to higher rate of energy expenditure in males, stemming from greater activity and SMR. Our findings have implications for estimating the effects of sea lamprey populations on mercury cycling within ecosystems, as well as for the proposed opening of sea lamprey fisheries. Eventually, our results may prove useful in improving control of sea lamprey, a pest responsible for substantial damage to fisheries in lakes where it is not native.

  11. Mercury accumulation in sea lamprey (Petromyzon marinus) from Lake Huron.

    Science.gov (United States)

    Madenjian, Charles P; Johnson, Nicholas S; Siefkes, Michael J; Dettmers, John M; Blum, Joel D; Johnson, Marcus W

    2014-02-01

    We determined whole-fish total mercury (Hg) concentrations of 40 male and 40 female adult sea lampreys (Petromyzon marinus) captured in the Cheboygan River, a tributary to Lake Huron, during May 2011. In addition, bioenergetics modeling was used to explore the effects of sex-related differences in activity and resting (standard) metabolic rate (SMR) on mercury accumulation. The grand mean for Hg concentrations was 519 ng/g (standard error of the mean=46 ng/g). On average, males were 16% higher in Hg concentration than females. Bioenergetics modeling results indicated that 14% higher activity and SMR in males would account for this observed sex difference in Hg concentrations. We concluded that the higher Hg concentration in males was most likely due to higher rate of energy expenditure in males, stemming from greater activity and SMR. Our findings have implications for estimating the effects of sea lamprey populations on mercury cycling within ecosystems, as well as for the proposed opening of sea lamprey fisheries. Eventually, our results may prove useful in improving control of sea lamprey, a pest responsible for substantial damage to fisheries in lakes where it is not native.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Nuclear response and phase transformation of melt grown, SbI/sub 3/-doped HgI/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Nissenbaum, J.; Shilo, I.; Burger, A.; Levi, A. (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)); Keller, L.; Wagner, C.N.J. (California Univ., Los Angeles (USA). Dept. of Material Science and Engineering)

    1983-07-15

    Slow solidification of 1.5 wt.% SbI/sub 3/-doped HgI/sub 2/ yielded a large-grained polycrystalline boule which in thin section exhibited transparent areas. When these areas were contacted with aquadag, a nuclear radiation counter was produced which showed severe polarization effects. Slow solidification of undoped HgI/sub 2/ had no transparent areas. Detector fabricated from sliced sections of that boule gave no response nuclear radiation. In a crystallographic and a thermodynamic study of SbI/sub 3/-doped HgI/sub 2/, it was found that an orange-colored high-temperature phase, which is crystallographically identical to the known yellow phase, appeared in all SbI/sub 3/-doped HgI/sub 2/ samples.

  17. A Terbium Metal-Organic Framework for Highly Selective and Sensitive Luminescence Sensing of Hg(2+) Ions in Aqueous Solution.

    Science.gov (United States)

    Xia, Tifeng; Song, Tao; Zhang, Gege; Cui, Yuanjing; Yang, Yu; Wang, Zhiyu; Qian, Guodong

    2016-12-19

    A series of isomorphic lanthanide metal-organic frameworks (MOFs) Ln(TATAB)⋅(DMF)4 (H2 O)(MeOH)0.5 (LnTATAB, Ln=Eu, Tb, Sm, Dy, Gd; H3 TATAB=4,4',4''-s-triazine-1,3,5-triyltri-p-aminobenzoic acid) have been solvothermally synthesized and structurally characterized. Among these MOFs, TbTATAB exhibits good water stability and a high fluorescence quantum yield. Because mercury ions (Hg(2+) ) have a high affinity to nitrogen atoms, and the space between multiple nitrogen atoms from triazine and imino groups is suitable for interacting with Hg(2+) ions, TbTATAB shows highly selective and sensitive detection of Hg(2+) in aqueous solution with a detection limit of 4.4 nm. Furthermore, it was successfully applied to detect Hg(2+) ions in natural water samples. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. 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.

  19. /sup 203/Hg and other gamma-emitting radio-isotopes as labels for Dirofilaria immitis microfilariae

    Energy Technology Data Exchange (ETDEWEB)

    Lengemann, F.W.; Grieve, R.B.; Chmielewicz, M.; Georgi, J.R.

    1986-04-01

    The in vitro uptake of gamma-emitting radionuclides by microfilariae of Dirofilaria immitis was investigated. Radionuclides tested were /sup 133/Ba, /sup 207/Bi, /sup 82/Br, /sup 109/Cd, /sup 51/Cr, /sup 60/Co, /sup 59/Fe, /sup 203/Hg, /sup 125/I, /sup 54/Mn, /sup 32/P, /sup 125/Sb, /sup 46/Sc, /sup 75/Se and /sup 65/Zn. Only /sup 207/Bi, /sup 59/Fe, /sup 203/Hg, /sup 54/Mn and /sup 46/Sc showed more than 2% of the available radioactivity to bind to the microfilariae. When tested for retention in vitro only /sup 203/Hg showed retention levels approaching 90%. Moreover, when dimethyl-sulphoxide was incorporated into the medium at levels of 1% (v/v) the uptake of /sup 203/Hg could be increased by 3-5 times; no other radio-isotope tested responded in this manner. The uptake of /sup 203/Hg was directly related to temperature and time of incubation. Mercury, as mercuric chloride, was toxic to the microfilariae and represents an impediment to the incorporation of high levels of /sup 203/Hg in microfilariae.

  20. 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.

  1. Removal of Hg(II) by poly(1-vinylimidazole)-grafted Fe3O4@SiO2 magnetic nanoparticles.

    Science.gov (United States)

    Shan, Chao; Ma, Zhiyao; Tong, Meiping; Ni, Jinren

    2015-02-01

    Fe3O4@SiO2 magnetic nanoparticles modified by grafting poly(1-vinylimidazole) oligomer (FSPV) was fabricated as a novel adsorbent to remove Hg(II) from water. Fourier transform infra-red spectroscopy confirmed the successful grafting of oligomer, and thermogravimetric analysis showed FSPV had a high grafting yield with organic content of 22.8%. Transmission electron microscopy image displayed that FSPV particles were polymer-coated spheres with size of 10-20 nm. With saturation magnetization of 44.7 emu/g, FSPV particles could be easily separated from water with a simple magnetic process in 5 min. The Hg(II) adsorption capacity of FSPV was found to be 346 mg/g at pH 7 and 25 °C in 10 mM NaCl. Moreover, the removal of Hg(II) by FSPV was not obviously affected by solution pH (from 4 to 10) or humic acid (up to 8 mg/L as TOC). The presence of seven common ions including Na(+), K(+), Ca(2+), Mg(2+), Cl(-), NO3(-), and SO4(2-) (up to 100 mM ionic strength) slightly increased the adsorption of Hg(II) by FSPV. X-ray photoelectron spectroscopy analysis revealed that the N atom of the imidazole ring was responsible for the bonding with Hg(II), whereas the bonding of Hg with N did not result in cleavage of Hg-Cl bond in HgCl2 and HgClOH. The regeneration of Hg(II)-loaded FSPV could be achieved with 0.5 M HCl rapidly in 10 min, and the removal of Hg(II) maintained above 94% in five consecutive adsorption-desorption cycles. Therefore, FSPV could serve as a promising adsorbent for Hg(II) removal from water.

  2. Methodological considerations regarding the use of inorganic {sup 197}Hg(II) radiotracer to assess mercury methylation potential rates in lake sediment

    Energy Technology Data Exchange (ETDEWEB)

    Perez Catan, Soledad [Laboratorio de Analisis por Activacion Neutronica, Comision Nacional de Energia Atomica, Centro Atomico Bariloche, 8400 Bariloche (Argentina); Guevara, Sergio Ribeiro [Laboratorio de Analisis por Activacion Neutronica, Comision Nacional de Energia Atomica, Centro Atomico Bariloche, 8400 Bariloche (Argentina)], E-mail: ribeiro@cab.cnea.gov.ar; Marvin-DiPasquale, Mark [US Geological Survey, 345 Middlefield Rd./MS 480, Menlo Park, CA 94025 (United States); Magnavacca, Cecilia [Centro Atomico Ezeiza, Comision Nacional de Energia Atomica, Presbitero Gonzalez y Aragon No. 15, B1802AYA, Ezeiza, Buenos Aires (Argentina); Cohen, Isaac Marcos [Departamento de Ingenieria Quimica, Facultad Regional Buenos Aires, Universidad Tecnologica Nacional, Medrano 951 (C1179AAQ) Buenos Aires (Argentina); Arribere, Maria [Laboratorio de Analisis por Activacion Neutronica, Comision Nacional de Energia Atomica, Centro Atomico Bariloche, 8400 Bariloche (Argentina)

    2007-09-15

    Methodological considerations on the determination of benthic methyl-mercury (CH{sub 3}Hg) production potentials were investigated on lake sediment, using {sup 197}Hg radiotracer. Three methods to arrest bacterial activity were compared: flash freezing, thermal sterilization, and {gamma}-irradiation. Flash freezing showed similar CH{sub 3}Hg recoveries as thermal sterilization, which was both 50% higher than the recoveries obtained with {gamma}-ray irradiation. No additional radiolabel was recovered in kill-control samples after an additional 24 or 65 h of incubation, suggesting that all treatments were effective at arresting Hg(II)-methylating bacterial activity, and that the initial recoveries are likely due to non-methylated {sup 197}Hg(II) carry-over in the organic extraction and/or [{sup 197}Hg]CH{sub 3}Hg produced via abiotic reactions. Two CH{sub 3}Hg extraction methods from sediment were compared: (a) direct extraction into toluene after sediment leaching with CuSO{sub 4} and HCl and (b) the same extraction with an additional back-extraction step to thiosulphate. Similar information was obtained with both methods, but the low efficiency observed and the extra work associated with the back-extraction procedure represent significant disadvantages, even tough the direct extraction involves higher Hg(II) carry over.

  3. Methodological considerations regarding the use of inorganic 197Hg(II) radiotracer to assess mercury methylation potential rates in lake sediment

    Science.gov (United States)

    Perez, Catan S.; Guevara, S.R.; Marvin-DiPasquale, M.; Magnavacca, C.; Cohen, I.M.; Arribere, M.

    2007-01-01

    Methodological considerations on the determination of benthic methyl-mercury (CH3Hg) production potentials were investigated on lake sediment, using 197Hg radiotracer. Three methods to arrest bacterial activity were compared: flash freezing, thermal sterilization, and ??-irradiation. Flash freezing showed similar CH3Hg recoveries as thermal sterilization, which was both 50% higher than the recoveries obtained with ??-ray irradiation. No additional radiolabel was recovered in kill-control samples after an additional 24 or 65 h of incubation, suggesting that all treatments were effective at arresting Hg(II)-methylating bacterial activity, and that the initial recoveries are likely due to non-methylated 197Hg(II) carry-over in the organic extraction and/or [197Hg]CH3Hg produced via abiotic reactions. Two CH3Hg extraction methods from sediment were compared: (a) direct extraction into toluene after sediment leaching with CuSO4 and HCl and (b) the same extraction with an additional back-extraction step to thiosulphate. Similar information was obtained with both methods, but the low efficiency observed and the extra work associated with the back-extraction procedure represent significant disadvantages, even tough the direct extraction involves higher Hg(II) carry over. ?? 2007 Elsevier Ltd. All rights reserved.

  4. Methodological considerations regarding the use of inorganic 197Hg(II) radiotracer to assess mercury methylation potential rates in lake sediment.

    Science.gov (United States)

    Pérez Catán, Soledad; Guevara, Sergio Ribeiro; Marvin-DiPasquale, Mark; Magnavacca, Cecilia; Cohen, Isaac Marcos; Arribere, María

    2007-09-01

    Methodological considerations on the determination of benthic methyl-mercury (CH(3)Hg) production potentials were investigated on lake sediment, using (197)Hg radiotracer. Three methods to arrest bacterial activity were compared: flash freezing, thermal sterilization, and gamma-irradiation. Flash freezing showed similar CH(3)Hg recoveries as thermal sterilization, which was both 50% higher than the recoveries obtained with gamma-ray irradiation. No additional radiolabel was recovered in kill-control samples after an additional 24 or 65 h of incubation, suggesting that all treatments were effective at arresting Hg(II)-methylating bacterial activity, and that the initial recoveries are likely due to non-methylated (197)Hg(II) carry-over in the organic extraction and/or [(197)Hg]CH(3)Hg produced via abiotic reactions. Two CH(3)Hg extraction methods from sediment were compared: (a) direct extraction into toluene after sediment leaching with CuSO(4) and HCl and (b) the same extraction with an additional back-extraction step to thiosulphate. Similar information was obtained with both methods, but the low efficiency observed and the extra work associated with the back-extraction procedure represent significant disadvantages, even tough the direct extraction involves higher Hg(II) carry over.

  5. Effect of surface fields on the dynamic resistance of planar HgCdTe mid-wavelength infrared photodiodes

    Science.gov (United States)

    He, Kai; Zhou, Song-Min; Li, Yang; Wang, Xi; Zhang, Peng; Chen, Yi-Yu; Xie, Xiao-Hui; Lin, Chun; Ye, Zhen-Hua; Wang, Jian-Xin; Zhang, Qin-Yao

    2015-05-01

    This work investigates the effect of surface fields on the dynamic resistance of a planar HgCdTe mid-wavelength infrared photodiode from both theoretical and experimental aspects, considering a gated n-on-p diode with the surface potential of its p-region modulated. Theoretical models of the surface leakage current are developed, where the surface tunnelling current in the case of accumulation is expressed by modifying the formulation of bulk tunnelling currents, and the surface channel current for strong inversion is simulated with a transmission line method. Experimental data from the fabricated devices show a flat-band voltage of V F B = - 5.7 V by capacitance-voltage measurement, and then the physical parameters for bulk properties are determined from the resistance-voltage characteristics of the diode working at a flat-band gate voltage. With proper values of the modeling parameters such as surface trap density and channel electron mobility, the theoretical R 0 A product and corresponding dark current calculated from the proposed model as functions of the gate voltage Vg demonstrate good consistency with the measured values. The R 0 A product remarkably degenerates when Vg is far below or above VFB because of the surface tunnelling current or channel current, respectively; and it attains the maximum value of 5.7 × 10 7 Ω . cm 2 around the transition between surface depletion and weak inversion when V g ≈ - 4 V , which might result from reduced generation-recombination current.

  6. 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

  7. Gate-Defined Wires in HgTe Quantum Wells: From Majorana Fermions to Spintronics

    Directory of Open Access Journals (Sweden)

    Johannes Reuther

    2013-08-01

    Full Text Available We introduce a promising new platform for Majorana zero modes and various spintronics applications based on gate-defined wires in HgTe quantum wells. Because of the Dirac-like band structure for HgTe, the physics of such systems differs markedly from that of conventional quantum wires. Most strikingly, we show that the subband parameters for gate-defined HgTe wires exhibit exquisite tunability: Modest gate voltage variation allows one to modulate the Rashba spin-orbit energies from zero up to about 30 K, and the effective g factors from zero up to giant values exceeding 600. The large achievable spin-orbit coupling and g factors together allow one to access Majorana modes in this setting at exceptionally low magnetic fields while maintaining robustness against disorder. As an additional benefit, gate-defined wires (in HgTe or other settings should greatly facilitate the fabrication of networks for refined transport experiments used to detect Majoranas, as well as the realization of non-Abelian statistics and quantum information devices.

  8. Required composition uniformity of Hg1-xCdxTe substrate for focal plane arrays

    Science.gov (United States)

    Gopal, Vishnu

    1996-10-01

    This paper presents a comparison of theoretically predicted spatial NETD and mean temporal NETD as a function of the composition uniformity of Hg(subscript 1-x)Cd(subscript x)Te substrate used in the fabrication of IR detector arrays. The prediction of the spatial NETD is based on the residual spatial noise left behind in the FPA after implementing a linear two point nonuniformity compensation algorithm. The effect of using an optical filter on the spatial NETD is also included to show that the specifications on the composition uniformity of the Hg(subscript 1-x)Cd(subscript x)Te substrate can be partially relaxed by using an optical filter whose cut-off wavelength is less than the cutoff wavelength of the photodiodes of mean response. The composition uniformity leading to temporal noise rather than the spatial noise limited performances are suggested to be indicating the required composition uniformity of Hg(subscript 1-x)Cd(subscript x)Te substrate for focal plane arrays (FPA). The results are presented for both MWIR and LWIR HgCdTe hybrid FPAs.

  9. Silole-infiltrated photonic crystal films as effective fluorescence sensor for Fe3+ and Hg2+.

    Science.gov (United States)

    Zhang, Yuqi; Li, Xiangdong; Gao, Loujun; Qiu, Jianhua; Heng, Liping; Tang, Ben Zhong; Jiang, Lei

    2014-02-24

    We develop a highly effective silole-infiltrated photonic crystal (PC) film fluorescence sensor with high sensitivity, good selectivity and excellent reproducibility for Fe(3+) and Hg(2+) ions. Hexaphenylsilole (HPS) infiltrated PCs show amplified fluorescence due to the slow photon effect of PC because the emission wavelength of HPS is at the blue band edge of the selected PC's stopband. The fluorescence can be quenched significantly by Fe(3+)/Hg(2+) ions owing to electron transfer between HPS and metal ions. The amplified fluorescence enhances the sensitivity of detection, with a detection limit of 5 nM for Fe(3+)/Hg(2+) ions. The sensor is negligibly responsive to other metal ions and can easily be reproduced by rinsing with pure water due to the special surface wettability of PC. As a result, a highly effective Fe(3+)/Hg(2+) ions sensor based on HPS-infiltrated PC film has been achieved, which will be important for effective and practical detection of heavy metal ions.

  10. Applications of organo-silica nanocomposites for SPNE of Hg(II)

    Science.gov (United States)

    Kaur, Anupreet

    2016-02-01

    An analytical method using modified SiO2 nanoparticles as solid-phase extractant has been developed for the preconcentration of trace amounts of Hg(II) in different water samples. Conditions of the analysis such as preconcentration factor, effect of pH, sample volume, shaking time, elution conditions and effects of interfering ions for the recovery of analyte were investigated. The adsorption capacity of nanometer SiO2-APTMS was found to be 181.42 µmol g-1 at optimum pH and the detection limit (3σ) was 0.45 µg L-1. The extractant showed rapid kinetic sorption. The adsorption equilibrium of Hg(II) on nanometer SiO2-APTMS was achieved just in 15 min. Adsorbed Hg(II) was easily eluted with 4 mL of 2.0 M hydrochloric acid. The maximum preconcentration factor was 75. The method was applied for the determination of trace amounts of Hg(II) in various synthetic samples and water samples.

  11. 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).

  12. ITER helium ash accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, J.T.; Hillis, D.L.; Galambos, J.; Uckan, N.A. (Oak Ridge National Lab., TN (USA)); Dippel, K.H.; Finken, K.H. (Forschungszentrum Juelich GmbH (Germany, F.R.). Inst. fuer Plasmaphysik); Hulse, R.A.; Budny, R.V. (Princeton Univ., NJ (USA). Plasma Physics Lab.)

    1990-01-01

    Many studies have shown the importance of the ratio {upsilon}{sub He}/{upsilon}{sub E} in determining the level of He ash accumulation in future reactor systems. Results of the first tokamak He removal experiments have been analysed, and a first estimate of the ratio {upsilon}{sub He}/{upsilon}{sub E} to be expected for future reactor systems has been made. The experiments were carried out for neutral beam heated plasmas in the TEXTOR tokamak, at KFA/Julich. Helium was injected both as a short puff and continuously, and subsequently extracted with the Advanced Limiter Test-II pump limiter. The rate at which the He density decays has been determined with absolutely calibrated charge exchange spectroscopy, and compared with theoretical models, using the Multiple Impurity Species Transport (MIST) code. An analysis of energy confinement has been made with PPPL TRANSP code, to distinguish beam from thermal confinement, especially for low density cases. The ALT-II pump limiter system is found to exhaust the He with maximum exhaust efficiency (8 pumps) of {approximately}8%. We find 1<{upsilon}{sub He}/{upsilon}{sub E}<3.3 for the database of cases analysed to date. Analysis with the ITER TETRA systems code shows that these values would be adequate to achieve the required He concentration with the present ITER divertor He extraction system.

  13. [Concentrations of mercury in ambient air in wastewater irrigated area of Tianjin City and its accumulation in leafy vegetables].

    Science.gov (United States)

    Zheng, Shun-An; Han, Yun-Lei; Zheng, Xiang-Qun

    2014-11-01

    Gaseous Hg can evaporate and enter the plants through the stomata of plat leaves, which will cause a serious threat to local food safety and human health. For the risk assessment, this study aimed to characterize atmospheric mercury (Hg) as well as its accumulation in 5 leafy vegetables (spinach, edible amaranth, rape, lettuce, allium tuberosum) from sewage-irrigated area of Tianjin City. Bio-monitoring sites were located in paddy (wastewater irrigation for 30 a), vegetables (wastewater irrigation for 15 a) and grass (control) fields. Results showed that after long-term wastewater irrigation, the mean values of mercury content in paddy and vegetation fields were significantly higher than the local background value and the national soil environment quality standard value for mercury in grade I, but were still lower than grade II. Soil mercury contents in the studied control grass field were between the local background value and the national soil environment quality standard grade I . Besides, the atmospheric environment of paddy and vegetation fields was subjected to serious mercury pollution. The mean values of mercury content in the atmosphere of paddy and vegetation fields were 71.3 ng x m(-3) and 39.2 ng x m(-3), respectively, which were markedly higher than the reference gaseous mercury value on the north sphere of the earth (1.5-2.0 ng x m(-3)). The mean value of ambient mercury in the control grass fields was 9.4 ng x m(-3). In addition, it was found that the mercury content in leafy vegetables had a good linear correlation with the ambient total gaseous mercury (the data was transformed into logarithms as the dataset did not show a normal distribution). The comparison among 5 vegetables showed that the accumulations of mercury in vegetables followed this order: spinach > edible amaranth > allium tuberosum > rape > lettuce. Median and mean values of mercury contents in spinach and edible amaranth were greater than the hygienic standard for the allowable

  14. Mercury accumulation in sharks from the coastal waters of southwest Florida.

    Science.gov (United States)

    Rumbold, Darren; Wasno, Robert; Hammerschlag, Neil; Volety, Aswani

    2014-10-01

    As large long-lived predators, sharks are particularly vulnerable to exposure to methylmercury biomagnified through the marine food web. Accordingly, nonlethal means were used to collect tissues for determining mercury (Hg) concentrations and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) from a total of 69 sharks, comprising 7 species, caught off Southwest Florida from May 2010 through June 2013. Species included blacknose (Carcharhinus acronotus), blacktip (C. limbatus), bull (C. leucas), great hammerhead (Sphyrna mokarran), lemon (Negaprion brevirostris), sharpnose (Rhizoprionodon terraenovae), and tiger sharks (Galeocerdo cuvier). The sharks contained Hg concentrations in their muscle tissues ranging from 0.19 mg/kg (wet-weight basis) in a tiger shark to 4.52 mg/kg in a blacktip shark. Individual differences in total length and δ(13)C explained much of the intraspecific variation in Hg concentrations in blacknose, blacktip, and sharpnose sharks, but similar patterns were not evident for Hg and δ(15)N. Interspecific differences in Hg concentration were evident with greater concentrations in slower-growing, mature blacktip sharks and lower concentrations in faster-growing, young tiger sharks than other species. These results are consistent with previous studies reporting age-dependent growth rate can be an important determinant of intraspecific and interspecific patterns in Hg accumulation. The Hg concentrations observed in these sharks, in particular the blacktip shark, also suggested that Hg may pose a threat to shark health and fitness.

  15. Analysis of mercury and other heavy metals accumulated in lichen Usnea antarctica from James Ross Island, Antarctica.

    Science.gov (United States)

    Zvěřina, Ondřej; Láska, Kamil; Cervenka, Rostislav; Kuta, Jan; Coufalík, Pavel; Komárek, Josef

    2014-12-01

    The study was designed to investigate the content and distribution of selected heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Fe, Pb and Zn) in samples of fruticose macrolichen Usnea antarctica from James Ross Island. A special emphasis was devoted to mercury and its species (elemental mercury and methylmercury). It was found that mercury contents were relatively high (up to 2.73 mg kg(-1) dry weight) compared to other parts of the Antarctic Peninsula region, while the concentrations of most other elements were within reported ranges. Mercury contents in lichens originating from the interior were higher than those from the coast, which is probably the result of local microclimate conditions. Similar trends were observed for Hg(0) and MeHg(+), whose contents were up to 0.14 and 0.098 mg kg(-1) dry weight, respectively. While mercury did not show a significant correlation with any other element, the mutual correlation of some litophile elements probably refers to the influence on thalli of resuspended weathered material. The influence of habitat and environmental conditions could play an essential role in the bioaccumulation of contaminants rather than just the simple presence of sources. Thus, the study of the thalli of this species can bring a new perspective on the interpretation of contaminant accumulation in lichens of the polar region.

  16. Hubungan Paparan Merkuri (Hg Dengan Kejadian Gangguan Fungsi HatiPada Pekerja Tambang Emas di Wonogiri

    Directory of Open Access Journals (Sweden)

    Nikie Astorina Yunita Dewanti

    2013-12-01

    Full Text Available Background: Traditional gold mining activities that using WOA/ amalgamation can cause Hg emissions to the environment. The emissions could raise mercury poisoning in the environment and human. Liver as a major part of the metabolism and accumulation of Hg in the human body, so that Hg could lead to liver damage. In the previous research, Hg exposure in male rats caused hepatotoxicosis. Average blood mercury levels of workers was 53.5 μg/m3. Objective: To determine the association between mercury (Hg exposure and theoccurance of liver dysfunction on gold mine workers at Jendi Village, sub-district Selogiri, Wonogiri District. Methods: It was a cross-sectional study, total sample were 41 workers. The data obtained from the results of laboratory tests of blood samples and the results of the interview respondents.Data would be analyzed using biavariate and multivariate statstic test. Results:There was 41.16% of respondents were miners, processors as well as grates, the average of working period was 10 years, work duration 6 hours a  day and 6 days a week. 97.56% of respondents have blood mercury levels above normal (U.S. EPA: 5.8 ppb. Elevated levels of SGOT experienced by 24.4% of respondents , SGPT 17.1% of  respondents and ALP 58.8% of  respondents or as much as 68.3% of respondents having liver disfunction. There was no difference incidence of liver dysfunction seen from the type of work (p value = 0.459, There was no assossiation between  work duration, work period and blood mercury  levels with the incidence of liver disfunction in workers (p value = 0.148; 0.408 and 0.608. There was a relationship between blood mercury levels with SGPT as an indicator of liver dysfunction (p value = 0.042 Conclusion: Overall, the data did not provide strong evidence that mercury exposure associated with incidence of liver disfunction.   Keywords: mercury exposure, liver disfunction, SGOT, SGPT, ALP

  17. 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.

  18. Variance and covariance of accumulated displacement estimates.

    Science.gov (United States)

    Bayer, Matthew; Hall, Timothy J

    2013-04-01

    Tracking large deformations in tissue using ultrasound can enable the reconstruction of nonlinear elastic parameters, but poses a challenge to displacement estimation algorithms. Such large deformations have to be broken up into steps, each of which contributes an estimation error to the final accumulated displacement map. The work reported here measured the error variance for single-step and accumulated displacement estimates using one-dimensional numerical simulations of ultrasound echo signals, subjected to tissue strain and electronic noise. The covariance between accumulation steps was also computed. These simulations show that errors due to electronic noise are negatively correlated between steps, and therefore accumulate slowly, whereas errors due to tissue deformation are positively correlated and accumulate quickly. For reasonably low electronic noise levels, the error variance in the accumulated displacement estimates is remarkably constant as a function of step size, but increases with the length of the tracking kernel.

  19. Differential protein expression of hepatic cells associated with MeHg exposure: deepening into the molecular mechanisms of toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Cuello, Susana; Madrid, Yolanda; Luque-Garcia, Jose L.; Camara, Carmen [Complutense University of Madrid, Department of Analytical Chemistry, Faculty of Chemistry, Madrid (Spain); Ramos, Sonia [Institute of Food Science, Technology and Nutrition, Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain)

    2012-08-15

    Understanding the molecular mechanisms underlying MeHg toxicity and the way in which this molecule interacts with living organisms is a critical point since MeHg represents a well-known risk to ecosystems and human health. We used a quantitative proteomic approach based on stable isotopic labeling by amino acids in cell culture in combination with SDS-PAGE and nanoflow LC-ESI-LTQ for analyzing the differential protein expression of hepatic cells associated to MeHg exposure. Seventy-eight proteins were found de-regulated by more than 1.5-fold. We identified a number of proteins involved in different essential biological processes including apoptosis, mitochondrial dysfunction, cellular trafficking and energy production. Among these proteins, we found several molecules whose de-regulation has been already related to MeHg exposure, thus confirming the usefulness of our discovery approach, and new ones that helped to gain a deeper insight into the biomolecular mechanisms related to MeHg-induced toxicity. Overexpression of several HSPs and the proteasome 26S subunit itself showed the proteasome system as a molecular target of toxic MeHg. As for the interaction networks, the top ranked was the nucleic acid metabolism, where many of the identified de-regulated proteins are involved. (orig.)

  20. Differential protein expression of hepatic cells associated with MeHg exposure: deepening into the molecular mechanisms of toxicity.

    Science.gov (United States)

    Cuello, Susana; Ramos, Sonia; Madrid, Yolanda; Luque-Garcia, Jose L; Cámara, Carmen

    2012-08-01

    Understanding the molecular mechanisms underlying MeHg toxicity and the way in which this molecule interacts with living organisms is a critical point since MeHg represents a well-known risk to ecosystems and human health. We used a quantitative proteomic approach based on stable isotopic labeling by amino acids in cell culture in combination with SDS-PAGE and nanoflow LC-ESI-LTQ for analyzing the differential protein expression of hepatic cells associated to MeHg exposure. Seventy-eight proteins were found de-regulated by more than 1.5-fold. We identified a number of proteins involved in different essential biological processes including apoptosis, mitochondrial dysfunction, cellular trafficking and energy production. Among these proteins, we found several molecules whose de-regulation has been already related to MeHg exposure, thus confirming the usefulness of our discovery approach, and new ones that helped to gain a deeper insight into the biomolecular mechanisms related to MeHg-induced toxicity. Overexpression of several HSPs and the proteasome 26S subunit itself showed the proteasome system as a molecular target of toxic MeHg. As for the interaction networks, the top ranked was the nucleic acid metabolism, where many of the identified de-regulated proteins are involved.

  1. Using mercury isotopes to understand the bioaccumulation of Hg in the subtropical Pearl River Estuary, South China.

    Science.gov (United States)

    Yin, Runsheng; Feng, Xinbin; Zhang, Junjun; Pan, Ke; Wang, Wenxiong; Li, Xiangdong

    2016-03-01

    Coastal and estuarine regions are important areas of mercury pollution. Therefore, it is important to properly characterize the sources and bioaccumulation processes of mercury in these regions. Here, we present mercury stable isotopic compositions in 18 species of wild marine fish collected from the Pearl River Estuary (PRE), south China. Our results showed variations in mass-independent fractionation (Δ(199)Hg: +0.05 ± 0.10‰ to +0.59 ± 0.30‰) with a Δ(199)Hg/Δ(201)Hg of ∼1.26, suggesting that aqueous MeHg underwent photo-degradation prior to incorporation into the food chain. For the results, we discovered small but significant differences of Δ(199)Hg values among herbivorous, demersal, and carnivorous fish, indicating that different feeding guilds of fish may have incorporated MeHg with various degrees of photo-demethylation. The consistent mercury isotope compositions between fish feeding habitat and mercury sources in the estuary provide potentially important findings on the transformation and bioaccumulation of this toxic metal in subtropical coastal environments.

  2. [Mercury and copper accumulation during last fifty years and their potential ecological risk assessment in sediment of mangrove wetland of Shenzhen, China].

    Science.gov (United States)

    Li, Rui-Li; Chai, Min-Wei; Qiu, Guo-Yu; He, Bei

    2012-12-01

    The processes of sediment transport and deposition can record some relative anthropogenic information in gulf region. Chronological analysis of the sediment core collected from mangrove wetland in Shenzhen Bay showed that the sedimentation rate was about 1.38 cm x a(-1). Soil buck density, pH, electrical conductivity (EC) and total organic carbon (TOC) changed in range of 0.36-0.71 g x cm(-3), 6-7, 2.93 x 10(3) -4.97 x 10(3) microS x cm(-1), and 1.5% - 3.8%, respectively. With the increase of soil depth, the soil buck density and EC increased gradually. However, the TOC decreased, with no significant change of pH. Contents of Hg and Cu in the whole depth of core ranged between 92-196 ng x g(-1) and 29-83 microg x g(-1), respectively. And both of them in sediment increased firstly and then decreased with the increasing soil depth. At 14 cm depth, contents of Hg and Cu reached up to the highest levels. Correspondingly, the ecological risk of Hg and Cu changed similarly with the contents of Hg and Cu. At 14 cm depth, the ecological risk indexes of Hg and Cu were at the highest levels of 39.10 and 13.85, respectively. The potential ecological risks of both Hg and Cu in sediments were mild. The rapid economical development of Hong Kong in 1960-1985 and Shenzhen in 1985-2000 contributed much to the Hg and Cu accumulation in mangrove wetland of Shenzhen Bay, China. Since the year of 2000, the reduction in contents of Hg and Cu has been expected as a consequence of the adoption of contamination control policies, improving the environment for growth of mangrove. In conclusion, the variations of core sediment heavy metal contents and its ecological risk assessment along the vertical profile reveal the interaction processes and extent of anthropogenic influences from the areas around the Shenzhen Bay and the catchments.

  3. Mercury accumulation in peatbogs at Czech sites with contrasting pollution histories.

    Science.gov (United States)

    Zuna, M; Ettler, V; Šebek, O; Mihaljevič, M

    2012-05-01

    Mercury (Hg) concentrations and accumulation patterns were studied in (210)Pb-dated peat cores from three ombrotrophic sites in the Czech Republic with contrasting emission histories (Novodomské rašeliniště, ND, and Bílá Smědá, BS, in the polluted northern parts of the country, and Jezerní slať, JS, in a relatively pristine southern part of the Czech Republic). The Hg concentration varied significantly between sites. Whereas the sites in the northern part of the Czech Republic yielded a range of higher Hg concentrations (50-750 μg kg(-1) for ND and 30-600 μg kg(-1) for BS), a Hg concentration range of 40-220 μg kg(-1) was reported at JS. At the northern localities, the highest Hg concentrations were detected at depths of 5-10 cm, corresponding to the period between the early 1960s until the late 1980s. In contrast, the highest Hg values at JS were observed at a depth of 10-15 cm, corresponding to the period between the early 1950s and the early 1970s. The maximum Hg accumulation rates were approximately 2× higher at the northern localities (ND: 106 μg m(-2)yr(-1), BS: 90 μg m(-2)yr(-1), JS: 43 μg m(-2)yr(-1)). Although a decrease in the Hg concentration can be observed in the youngest segments of all the peat cores, a slight increase in Hg accumulation rates in the most recent peat segments (living Sphagnum moss) has been reported for all three sites (40-44 μg m(-2)yr(-1)), which is approximately 2× higher than in peat bogs in western and northern Europe. This observation may either be related to a real recent increase in Hg emissions in Central Europe (active coal mining and burning and limited Hg pollution control in thermal power plants) or could indicate a preferential Hg binding mechanism in the living moss at the surface of the peat.

  4. Influence of catchment vegetation on mercury accumulation in lake sediments from a long-term perspective.

    Science.gov (United States)

    Rydberg, Johan; Rösch, Manfred; Heinz, Emanuel; Biester, Harald

    2015-12-15

    Organic matter (OM) cycling has a large impact on the cycling of mercury (Hg) in the environment. Hence, it is important to have a thorough understanding on how changes in, e.g., catchment vegetation - through its effect on OM cycling - affect the behavior of Hg. To test whether shifts in vegetation had an effect on Hg-transport to lakes we investigated a sediment record from Herrenwieser See (Southern Germany). This lake has a well-defined Holocene vegetation history: at ~8700years BP Corylus avellana (hazel) was replaced by Quercus robur (oak), which was replaced by Abies alba (fir) and Fagus sylvatica (beech) ~5700years BP). We were particularly interested in testing if coniferous vegetation leads to a larger export of Hg to aquatic systems than deciduous vegetation. When hazel was replaced by oak, reduced soil erosion and increased transport of DOM-bound mercury from the catchment resulted in increases in both Hg-concentrations and accumulation rates (61ngg(-1) and 5.5ngcm(-2)yr.(-)(1) to 118ngg(-1) and 8.5ngcm(-2)yr.(-)(1)). However, even if Hg-concentrations increased also in association with the introduction of fir and beech (173ngg(-1)), as a result of higher Hg:C, there was no increase in Hg-accumulation rates (7.6ngcm(-2)yr.(-)(1)), because of a decreased input of OM. At around 2500years BP Hg-accumulation rates and Hg-concentration indicated an additional input of Hg to the sediment (316ngg(-1) and 10.3ngcm(-2)yr.(-)(1)), which might be due to increased human activities in the area, e.g., forest burning or mining. Our results contrast those of several paired-catchment studies that suggest a higher release of Hg from coniferous than deciduous forest, and there is a need for studies with a long-term perspective to increase our understanding of the effects of slow and gradual processes on mercury cycling. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. 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

  6. 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...

  7. 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...

  8. The Health Show

    OpenAIRE

    Swann, David

    2011-01-01

    Dr David Swann interviewed on The Health Show, Series 1, Episode 5, 2011 for BBC World about the award-winning 21st Century Nursing Bag. BBC World News reaches 241million people every week, available in 296 million homes, 1.8 million hotel rooms and has the highest average viewership on a weekday of any international news channel. The Health Show is a new 26-part series for BBC World News covering the most important news stories from around the world.

  9. Fractionation distribution and preliminary ecological risk assessment of As, Hg and Cd in ornithogenic sediments from the Ross Sea region, East Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Chuangneng [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Liu, Xiaodong, E-mail: ycx@ustc.edu.cn [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Nie, Yaguang [Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026 (China); Emslie, Steven D. [Department of Biology and Marine Biology, University of North Carolina Wilmington, 601S. College Road, Wilmington, NC 28403 (United States)

    2015-12-15

    To evaluate mobility of toxic elements and their potential ecological risk caused by seabird biovectors, the fractionation distributions of arsenic (As), mercury (Hg) and cadmium (Cd) were investigated in three ornithogenic sediment profiles from the Ross Sea region, East Antarctica. The results show residual As holds a dominant position, and Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions, indicating weak mobility of As and Hg. However, exchangeable Cd occupies a considerable proportion in studied samples, suggesting Cd has strong mobility. The preliminary evaluation of Sediment Quality Guidelines (SGQs) shows adverse biological effects may occur occasionally for As and Cd, and rarely for Hg. Using Risk Assessment Code (RAC), the ecological risk is assessed at moderate, low and very high for As, Hg and Cd pollution, respectively. Organic matter derived from guano is the main factor controlling the mobility of Hg and Cd through adsorption and complexation. - Highlights: • Residual As holds a dominant position in ornithogenic sediments. • Hg mainly derives from residual, organic matter-bound and humic acid-bound fractions. • Exchangeable Cd occupies a considerable proportion in ornithogenic sediments. • TOC is the main factor controlling the mobility of Hg and Cd in studied sediments.

  10. 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...

  11. Accumulation properties of inorganic mercury and organic mercury in the red-crowned crane Grus japonensis in east Hokkaido, Japan.

    Science.gov (United States)

    Teraoka, Hiroki; Okamoto, Erika; Kudo, Moe; Nakayama, Shouta M M; Ikenaka, Yoshinori; Ishizuka, Mayumi; Endo, Tetsuya; Kitazawa, Takio; Hiraga, Takeo

    2015-12-01

    The red-crowned (Japanese) crane Grus japonensis is native to east Hokkaido, Japan, in contrast to the East Asia mainland. Previously, we reported that red-crowned cranes in Hokkaido were highly contaminated with mercury in the 1990s and that the contamination rapidly decreased to a moderate level in the 2000s. In the present study, we determined levels of organic mercury (O-Hg) in the liver and kidney of cranes in east Hokkaido in comparison with levels of total mercury (T-Hg). T-Hg levels in the kidneys were higher than those in the livers in adults but not in subadults and juveniles; however, the reverse was the case for O-Hg even for adults. The ratio of O-Hg to T-Hg in both the liver and kidney decreased as T-Hg increased in the three developmental stages. While the ratios of O-Hg to T-Hg in the liver and kidney of adults were significantly lower than those of juveniles, the ratios were similar for adults and juveniles in a lower range of T-Hg. The ratio of selenium (Se) to T-Hg decreased as T-Hg increased in both the liver and kidney, irrespective of stages. Mercury burdens in feathers were about 59% and 67% of the total body burdens for juveniles and adults, respectively. Furthermore, ratios of carbon and nitrogen stable isotopes to T-Hg varied greatly, with no relation to mercury level in the liver. The results suggest slow accumulation of inorganic mercury in the kidney of red-crowned cranes in east Hokkaido, Japan.

  12. 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.

  13. 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.

  14. 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.

  15. A new fluorescent pyrene–pyridine dithiocarbamate probe: A chemodosimeter to detect Hg{sup 2+} in pure aqueous medium and in live cells

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Vikram; Srivastava, Priyanka [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221005 (India); PrakashVerma, Shiv [Centre for Genetic Disorders, Faculty of Science, Banaras Hindu University, Varanasi-221005 (India); Misra, Arvind [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221005 (India); Das, Parimal [Centre for Genetic Disorders, Faculty of Science, Banaras Hindu University, Varanasi-221005 (India); Singh, Nanhai, E-mail: nsinghbhu@gmail.com [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221005 (India)

    2014-10-15

    A new pyrene–pyridine dithiocarbamate based fluorescent chemodosimeter, potassium (pyren-1-ylmethyl)(pyridin-2-ylmethyl)dithiocarbamate (L1) has been designed and synthesized. The chemodosimeter shows high selectivity and sensitivity (5.2 ppb) for Hg{sup 2+} in pure aqueous medium in which emission intensity was quenched by ≈80% due to the formation of new cyclized species, 1. The probe behaves as a chemodosimeter for Hg{sup 2+} ions and forms Hg{sup 2+} triggered cyclised imidazoline species with approximate detection time of 50 s and exhibits both colorimetric and fluorometric changes on detection of Hg{sup 2+} ion. Color of the probe (L1) changed from green to colorless visible to the naked eye and from green to dark blue upon the addition of Hg{sup 2+} ions under UV light. The Hg{sup 2+} triggered cyclization reaction was confirmed by spectral data analysis and a single crystal structure determination of the cyclised entity 2 obtained from the model compound potassium benzyl(pyridin-2-ylmethyl) dithiocarbamate (L2). L1 finds its application for detection of Hg{sup 2+} ions on paper strips, and in BSA (bovine serum albumin) medium. L1 is also applicable for the monitoring of Hg{sup 2+} ion in NIH3T3 live cells. - Highlights: • Efficient chemodosimeter to detect Hg{sup 2+} ions in pure aqueous medium. • Hg{sup 2+} triggered cyclisation and formation of imidazoline species. • Probe exhibit both colorimetric and fluorometric changes • Probe is applicable to detect Hg{sup 2+} in live cells and on cellulose paper strips.

  16. 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.

  17. A Fashion Show

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    <正>Story: The yearly fashion show day.The children take turns to walk on the stage and show the class their favorite clothes.Now it’s Joe’s and Phoebe’s turn.Joe walks on the stage and says,“My shorts are blue.Do you like my blue shorts?”On the other side of the stage, Phoebe is wearing her favorite pink skirt.“My skirt is pink.Do you like my pink skirt?”asks

  18. 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.

  19. On not showing scalps

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2016-01-01

    proposed by Janet Marstine, the editor of the Routledge Companion to Museum Ethics, I show how the museum succeeded in engaging users in questions of museum ethics. However, this specific debate on human remains in museums developed into an encounter between a global, museological discourse...

  20. Violence and TV Shows

    OpenAIRE

    ÖZTÜRK, Yrd. Doç. Dr. Şinasi

    2008-01-01

    This study aims to discuss theories on theviolent effects of TV shows on viewers, especiallyon children. Therefore, this study includes a briefdiscussion of definitions of violence, discussionof violence theories, main results of researcheson televised violence, measuring TV violence,perception of televised violence, individualdifferences and reactions to TV violence,aggressiveness and preferences for TV violence.

  1. Honored Teacher Shows Commitment.

    Science.gov (United States)

    Ratte, Kathy

    1987-01-01

    Part of the acceptance speech of the 1985 National Council for the Social Studies Teacher of the Year, this article describes the censorship experience of this honored social studies teacher. The incident involved the showing of a videotape version of the feature film entitled "The Seduction of Joe Tynan." (JDH)

  2. A Visionary Show

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Seduction. Distinction. Relax. Pulsation. These are the "style universes" on display at Première Vision, heralded as "The World’s Premiere Fabric Show." Started more than 35 years ago by 15 French weavers, Première Vision has expanded beyond its

  3. Honored Teacher Shows Commitment.

    Science.gov (United States)

    Ratte, Kathy

    1987-01-01

    Part of the acceptance speech of the 1985 National Council for the Social Studies Teacher of the Year, this article describes the censorship experience of this honored social studies teacher. The incident involved the showing of a videotape version of the feature film entitled "The Seduction of Joe Tynan." (JDH)

  4. 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.

  5. 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.

  6. Market Survey and Risk Assessment for Trace Metals in Edible Fungi and the Substrate Role in Accumulation of Heavy Metals.

    Science.gov (United States)

    Huang, Qingqing; Jia, Yan; Wan, Yanan; Li, Huafen; Jiang, Rongfeng

    2015-07-01

    Levels of cadmium (Cd), arsenic (As), mercury (Hg), lead (Pb), iron (Fe), and zinc (Zn) were investigated in 285 samples of 9 species of edible fungi (Lentinus edodes, Auricularia auricula, Pleurotus ostreatus, Tremella fuciformis, Flammulina velutipes, Agrocybe chaxinggu, Armillaria mellea, Agaricus bisporus, and Pholiota nameko), which were collected from markets in Beijing, China. In addition, edible fungi and culture substrates were collected from 7 cultivation bases to examine the role of the substrate in trace metal accumulation. Trace metal concentrations were determined on a dry weight basis. Data showed that all the edible fungi contained trace metals, the levels of which varied among species, and there were significant positive correlations between trace metal (Cd, Pb, and As) concentrations in mushrooms and their substrates. The concentrations of Cd, As, Hg, Pb, Fe, and Zn in the tested fungi ranged from 0.005 to 13.8 mg/kg, nd to 1.62 mg/kg, nd to 0.506 mg/kg, 0.011 to 22.1 mg/kg, 46.3 to 2514 mg/kg, and 14.6 to 289 mg/kg, respectively. In general, concentrations of Cd, As, Hg, Pb, Fe, and Zn were relatively high in L. edodes, whereas Tremella fuciformis and P. nameko had relatively low levels of trace metals. Furthermore, the estimated weekly intake of trace metals was calculated and compared with the WHO/FAO provisional tolerable weekly intake. The estimated weekly intake of Cd, As, Hg, Pb, Fe, and Zn from consuming edible fungi was lower than the provisional tolerable weekly intake. This paper reports information about trace metal concentrations in edible fungi collected from Beijing, China. This paper provides useful information for consumers and regulators about levels of trace metals in edible fungi. © 2015 Institute of Food Technologists®

  7. Contrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean.

    Science.gov (United States)

    Dirtu, Alin C; Malarvannan, Govindan; Das, Krishna; Dulau-Drouot, Violaine; Kiszka, Jeremy J; Lepoint, Gilles; Mongin, Philippe; Covaci, Adrian

    2016-04-01

    Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ(13)C and δ(15)N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ(15)N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation.

  8. Shanghai Shows Its Heart

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The city known as China’s economic powerhouse showed a more caring face as host of the Special Olympic Games Between October 2 and 11,the Special Olympics Summer Games were hosted in Shanghai,the first time the 40-year-old athletic com- petition for people with intellectual disabilities came to a developing country. This Special Olympics was also larger than all previous games in temps of the number of athletes.

  9. Analysis of protein expression in developmental toxicity induced by MeHg in zebrafish.

    Science.gov (United States)

    Cuello, Susana; Ximénez-Embún, Pilar; Ruppen, Isabel; Schonthaler, Helia B; Ashman, Keith; Madrid, Yolanda; Luque-Garcia, Jose L; Cámara, Carmen

    2012-11-21

    Mercury toxicity and its implications in development are a major concern, due to the major threat to ecosystems and human health that this compound represents. Although some of the effects of methylmercury (MeHg) exposure have been extensively studied, the molecular mechanisms of interaction between this compound and developing organisms are still not completely understood. To provide further insights into these mechanisms, we carried out a quantitative proteomic study (iTRAQ) using zebrafish larvae exposed to 5 μg L(-1) and 25 μg L(-1) MeHg as a model. In this study, a multidimensional approach combining isoelectric focusing (IEF) and strong cation exchange (SCX) followed by reversed phase liquid chromatography prior to MALDI TOF/TOF analysis was employed, which resulted in a substantial increase in proteome coverage. Among the proteins identified, 71 were found de-regulated by more than 1.5-fold, and implicated in embryonic development, protein synthesis, calcium homeostasis and energy production. Furthermore, morphological and histological analysis of exposed larvae was carried out, reflecting changes such as smaller swim bladder, remaining yolk, bent body axis and accumulation of blood in the heart, among others.

  10. New Results from a Search for the Electric Dipole Moment (EDM) of 99Hg

    Science.gov (United States)

    Heckel, Blayne

    2015-05-01

    The measurement of a nonzero EDM of an atom or elementary particle, at current levels of experimental sensitivity, would imply CP violation beyond the CKM matrix of the Standard Model. Additional sources of CP violation have been proposed to help explain the matter-antimatter asymmetry observed in our universe and the magnitude of ΘQCD, the strength of CP-violation in the strong interaction, remains unknown. We have recently completed a set of measurements on the EDM of 199Hg, sensitive to both new sources of CP violation and ΘQCD.The experiment compares the phase accumulated by precessing Hg atom spins in vapor cells with electric fields parallel and anti-parallel to a common magnetic field. The statistical sensitivity of new measurements represents a factor of 3 to 4 improvement over previous results. A description of the EDM experiment and the data, along with the current state of the systematic error analysis, will be presented. This work was supported by NSF Grant PHY-1306743 and by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under Award Number DE-FG02-97ER41020.

  11. 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.

  12. Comparative study of the metal accumulation in Hysterothalycium reliquens (nematode) and Paraphilometroides nemipteri (nematode) as compared with their doubly infected host, Nemipterus peronii (Notched threadfin bream).

    Science.gov (United States)

    Mazhar, Roshan; Shazili, Noor Azhar; Harrison, Faizah Shaharom

    2014-10-01

    In February 2013, forty-seven Notched threadfin bream, the Nemipterus peronii, were sampled from the eastern coastal waters of the South China Sea. The concentration of various elements, namely cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), strontium (Sr), manganese (Mn), selenium (Se), Lead (Pb), nickel (Ni), aluminum (Al), arsenic (As), iron (Fe), and Zinc (Zn) were analyzed in the liver, muscle, and kidney organs of the host, as well as in their parasites Hysterothalycium reliquens (nematode) and the Paraphilometroides nemipteri (nematode), using inductively coupled plasma mass spectrometry (ICP-MS). The former group of parasites showed highest accumulation capacity for Cr, Cu, Fe, Mn, Se, Ni, and Zn while the latter group had high accumulation potential of As, Hg, Cd, Al, Pb, and Sr. The divergence in heavy-metal accumulation profiles of both nematodes is linked with the specificity of microhabitats, cuticle morphology, and interspecific competition. The outcome of this study indicates that both parasite models can be used for biomonitoring of metal pollution in marine ecosystems.

  13. Desorption of Hg(II) and Sb(V) on extracellular polymeric substances: effects of pH, EDTA, Ca(II) and temperature shocks.

    Science.gov (United States)

    Zhang, Daoyong; Lee, Duu-Jong; Pan, Xiangliang

    2013-01-01

    Extracellular polymeric substances (EPS) existed ubiquitously in biological systems affect the mobility and availability of heavy metals in the environments. The adsorption-desorption behaviors of Hg(II) and Sb(V) on EPS were investigated. The sorption rates follow Sb(V) > Hg(II), and the desorption rates follow reverse order. Applications of ethylene diamine tetraacetic acid (EDTA), Ca(II) and pH shocks affect desorption rates and desorbed quantities of Hg(II) from EPS-Hg complex. Temperature shock minimally affects the desorption rate of Hg(II). Conversely, the EPS-Sb complex is stable subjected to EDTA, Ca(II), temperature or pH shocks. The excitation-emission matrix (EEM) fluorescence spectroscopy and fast-Fourier (FT-IR) analysis showed that Hg(II) and Sb(V) principally interacted with polysaccharides and protein-like compounds in the EPS, respectively. The EPS-Hg complex presents a time bomb that may release high levels of Hg(II) in short time period under environmental shocks.

  14. Estimation of some heavy metals in polluted well water and mercury accumulation in broiler organs

    Directory of Open Access Journals (Sweden)

    Hussein Khamis Hussein

    2013-10-01

    Full Text Available The aim of this study was to investigate the relationship between the concentrations of heavy metals in well water and bioaccumulation of the most abundant metals in chicken tissues in some areas in the province of Mecca Almokaramah, Saudi Arabia. Among the heavy metals (Cd, Zn, Cr, Mn, Cu Hg, Pb and Ni studied, mercury (Hg revealed highest in concentration in well waters. The concentration of mercury in the ground water, beside in liver, kidney, muscle and blood samples of ten chickens from each of four poultry- production farms were estimated using atomic absorption spectrophotometer. The results showed that the kidney followed by liver had the highest bioaccumulation of mercury in all farm samples. The level of mercury in the ground water was 7.06µg/L. The relationship between mercury accumulation levels in the kidney and those in the liver tissues were proportionally correlated and altered with elevation in the antioxidant enzyme activities such as AST and ALT. These elevated enzymatic activities were induced by the level of toxicity. There was a significant elevation in the level of liver and kidney malondialdhyde (MDA, while the activities of antioxidant enzymes superoxide dismutase and catalase (SOD and CAT were significantly decreased. Biochemical observations were supplemented by histopathological examination of liver and kidney sections.

  15. Bacterial accumulation in viscosity gradients

    Science.gov (United States)

    Waisbord, Nicolas; Guasto, Jeffrey

    2016-11-01

    Cell motility is greatly modified by fluid rheology. In particular, the physical environments in which cells function, are often characterized by gradients of viscous biopolymers, such as mucus and extracellular matrix, which impact processes ranging from reproduction to digestion to biofilm formation. To understand how spatial heterogeneity of fluid rheology affects the motility and transport of swimming cells, we use hydrogel microfluidic devices to generate viscosity gradients in a simple, polymeric, Newtonian fluid. Using video microscopy, we characterize the random walk motility patterns of model bacteria (Bacillus subtilis), showing that both wild-type ('run-and-tumble') cells and smooth-swimming mutants accumulate in the viscous region of the fluid. Through statistical analysis of individual cell trajectories and body kinematics in both homogeneous and heterogeneous viscous environments, we discriminate passive, physical effects from active sensing processes to explain the observed cell accumulation at the ensemble level.

  16. Photocatalytic oxidation removal of Hg0 using ternary Ag/AgI-Ag2CO3 hybrids in wet scrubbing process under fluorescent light

    Science.gov (United States)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    A series of ternary Ag/AgI-Ag2CO3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg0 removal in a wet scrubbing reactor. The hybrids were characterized by N2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg0 removal. NO exhibited significant effect on Hg0 removal in comparison to SO2. Among these ternary Ag/AgI-Ag2CO3 hybrids, Ag/AgI(0.1)-Ag2CO3 showed the highest Hg0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag2CO3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (rad O2-) may play a key role in Hg0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg0 removal over Ag/AgI(0.1)-Ag2CO3 hybrid under fluorescent light was proposed.

  17. Not a "reality" show.

    Science.gov (United States)

    Wrong, Terence; Baumgart, Erica

    2013-01-01

    The authors of the preceding articles raise legitimate questions about patient and staff rights and the unintended consequences of allowing ABC News to film inside teaching hospitals. We explain why we regard their fears as baseless and not supported by what we heard from individuals portrayed in the filming, our decade-long experience making medical documentaries, and the full un-aired context of the scenes shown in the broadcast. The authors don't and can't know what conversations we had, what documents we reviewed, and what protections we put in place in each televised scene. Finally, we hope to correct several misleading examples cited by the authors as well as their offhand mischaracterization of our program as a "reality" show.

  18. Accumulation by Conservation

    NARCIS (Netherlands)

    Büscher, Bram; Fletcher, Robert

    2014-01-01

    Following the financial crisis and its aftermath, it is clear that the inherent contradictions of capitalist accumulation have become even more intense and plunged the global economy into unprecedented turmoil and urgency. Governments, business leaders and other elite agents are frantically searchin

  19. 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.

  20. Nitrogen and sulfur co-doped carbon dots for highly selective and sensitive detection of Hg (II) ions.

    Science.gov (United States)

    Li, Libo; Yu, Bin; You, Tianyan

    2015-12-15

    Nitrogen and sulfur co-doped carbon dots (N,S/C-dots) with high fluorescence quantum yields (FLQY, 25%) was successfully synthesized by a one-step microwave-assisted method. In comparison with nitrogen doped C-dots (N/C-dots) prepared using the same method, the resulting N,S/C-dots featured small particle size, uniform surface state, insensitive FL properties to excitation wavelengths and environmental conditions, negligible cytotoxicity and excellent biocompatibility. Simultaneous doping of N and S effectively promoted electron-transfer and coordination interaction between N,S/C-dots and Hg(2+). Thus, when used as fluorescence probe for Hg(2+) label-free detection, the resulting N,S/C-dots showed good detection sensitivity and ion selectivity. The limit of detection was 2 μM; among 15 metal ions investigated, only Fe(3+) showed interference to the Hg(2+) detection. Fortunately, this interference could be effectively shielded using a chelating agent sodium hexametaphoshpate. The applicability of N,S/C-dots as fluorescence probe for Hg(2+) detection in lake water and tap water was demonstrated. Finally, based on its favorable features of negligible cytotoxicity and excellent biocompatibility, the N,S/C-dots were successfully applied to probe Hg(2+) in living cells, which broaden its application in biological system.

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. A dansyl based fluorescence chemosensor for Hg2+ and its application in the complicated environment samples

    Science.gov (United States)

    Zhou, Shuai; Zhou, Ze-Quan; Zhao, Xuan-Xuan; Xiao, Yu-Hao; Xi, Gang; Liu, Jin-Ting; Zhao, Bao-Xiang

    2015-09-01

    We have developed a novel fluorescent chemosensor (DAM) based on dansyl and morpholine units for the detection of mercury ion with excellent selectivity and sensitivity. In the presence of Hg2+ in a mixture solution of HEPES buffer (pH 7.5, 20 mM) and MeCN (2/8, v/v) at room temperature, the fluorescence of DAM was almost completely quenched from green to colorless with fast response time. Moreover, DAM also showed its excellent anti-interference capability even in the presence of large amount of interfering ions. It is worth noting that DAM could be used to detect Hg2+ specifically in the Yellow River samples, which significantly implied the potential applications of DAM in the complicated environment samples.

  8. High precision strain mapping of topological insulator HgTe/CdTe

    Science.gov (United States)

    Haas, Benedikt; Thomas, Candice; Jouneau, Pierre-Henri; Bernier, Nicolas; Meunier, Tristan; Ballet, Philippe; Rouvière, Jean-Luc

    2017-06-01

    Topological insulators (TIs) represent a class of matter associated with unique electronic and spin properties held by chiral and massless Dirac fermions. The lattice mismatch between the HgTe layer and the CdTe substrate, which is the reason for the TI properties in HgTe/CdTe, is less than 0.4%. Measuring it necessitates an extremely sensitive technique, while a nanometric spatial resolution is mandatory to characterize the strain gradient across the layers. In this letter, we demonstrate the use of nano-beam precession electron diffraction to map the strain of the whole stack, thus experimentally addressing the strain distribution in such systems. Strain maps with a precision of 0.03% and a spatial resolution of 1.9 nm show good agreement with finite element simulations of the expected strain. Strain values and gradients are within the intervals predicted to yield the TI properties of the material.

  9. Showing Value (Editorial

    Directory of Open Access Journals (Sweden)

    Denise Koufogiannakis

    2009-06-01

    Full Text Available When Su Cleyle and I first decided to start Evidence Based Library and Information Practice, one of the things we agreed upon immediately was that the journal be open access. We knew that a major obstacle to librarians using the research literature was that they did not have access to the research literature. Although Su and I are both academic librarians who can access a wide variety of library and information literature from our institutions, we belong to a profession where not everyone has equal access to the research in our field. Without such access to our own body of literature, how can we ever hope for practitioners to use research evidence in their decision making? It would have been contradictory to the principles of evidence based library and information practice to do otherwise.One of the specific groups we thought could use such an open access venue for discovering research literature was school librarians. School librarians are often isolated and lacking access to the research literature that may help them prove to stakeholders the importance of their libraries and their role within schools. Certainly, school libraries have been in decline and the use of evidence to show value is needed. As Ken Haycock noted in his 2003 report, The Crisis in Canada’s School Libraries: The Case for Reform and Reinvestment, “Across the country, teacher-librarians are losing their jobs or being reassigned. Collections are becoming depleted owing to budget cuts. Some principals believe that in the age of the Internet and the classroom workstation, the school library is an artifact” (9. Within this context, school librarians are looking to our research literature for evidence of the impact that school library programs have on learning outcomes and student success. They are integrating that evidence into their practice, and reflecting upon what can be improved locally. They are focusing on students and showing the impact of school libraries and

  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. Interactions between photoexcited NIR emitting CdHgTe quantum dots and graphene oxide

    Science.gov (United States)

    Jagtap, Amardeep M.; Varade, Vaibhav; Konkena, Bharathi; Ramesh, K. P.; Chatterjee, Abhijit; Banerjee, Arup; Pendyala, Naresh Babu; Koteswara Rao, K. S. R.

    2016-02-01

    Hydrothermally grown mercury cadmium telluride quantum dots (CdHgTe QDs) are decorated on graphene oxide (GO) sheets through physisorption. The structural change of GO through partial reduction of oxygen functional groups is observed with X-ray photoelectron spectroscopy in GO-QDs composites. Raman spectroscopy provides relatively a small change (˜1.1 times) in D/G ratio of band intensity and red shift in G band from 1606 cm-1 to 1594 cm-1 in GO-CdHgTe QDs (2.6 nm) composites, which indicates structural modification of GO network. Steady state and time resolved photoluminescence (PL) spectroscopy shows the electronic interactions between photoexcited near infrared emitting CdHgTe QDs and GO. Another interesting observation is PL quenching in the presence of GO, and it is quite effective in the case of smaller size QDs (2.6 nm) compared to the larger size QDs (4.2 nm). Thus, the observed PL quenching is attributed to the photogenerated electron transfer from QDs to GO. The photoexcited electron transfer rate decreases from 2.2 × 109 to 1.5 × 108 s-1 with increasing particle size from 2.6 to 4.2 nm. Photoconductivity measurements on QDs-GO composite devices show nearly 3 fold increase in the current density under photo-illumination, which is a promising aspect for solar energy conversion and other optoelectronic applications.

  12. 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

  13. 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.

  14. 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.

  15. Efficient removal and highly selective adsorption of Hg{sup 2+} by polydopamine nanospheres with total recycle capacity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiulan [School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang bingtuan, Shihezi University, Shihezi 832003 (China); Jia, Xin, E-mail: jiaxin@shzu.edu.cn [School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang bingtuan, Shihezi University, Shihezi 832003 (China); Zhang, Guoxiang [Gansu Dayu Water-saving Group Co., Ltd, Jiuquan 735000 (China); Hu, Jiamei; Sheng, Wenbo; Ma, Zhiyuan; Lu, Jianjiang; Liu, Zhiyong [School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang bingtuan, Shihezi University, Shihezi 832003 (China)

    2014-09-30

    Highlights: • The PDA nanospheres with uniform diameter of 150–200 nm were used to remove Hg{sup 2+} efficiently and selectively. • The desorption capacity of PDA nanospheres was 100% in pH 1. • The structure and removal capacity of PDA nanospheres remained almost unchanged after recycling five times. - Abstract: This study reported a new method for efficient removal of Hg{sup 2+} from contaminated water using highly selective adsorptive polydopamine (PDA) nanospheres, which were uniform and had a small diameter (150–200 nm). The adsorption isotherms, kinetics, thermodynamics were investigated. Also, the effects of ionic strength, co-existing ions on removing ability of PDA nanospheres for Hg{sup 2+} were studied. Adsorption of Hg{sup 2+} was very fast and efficient as adsorption equilibrium was completed within 4 h and the maximum adsorption capacities were 1861.72 mg/g, 2037.22 mg/g, and 2076.81 mg/g at 298 K, 313 K, and 328 K respectively, increasing with increasing of temperature. The PDA nanospheres exhibited highly selective adsorption of Hg{sup 2+} and had a total desorption capacity of 100% in hydrochloric acid solution, pH 1. The results showed that the structure of PDA nanospheres remained almost unchanged after recycling five times. Furthermore, X-ray photoelectron spectroscopy (XPS) was employed to determine the elements of PDA nanospheres before and after Hg{sup 2+} adsorption. Considering their efficient and highly Hg{sup 2+} selective adsorption, total recycle capacity, and high stability, PDA nanospheres will be feasible in a number of practical applications.

  16. Public medical shows.

    Science.gov (United States)

    Walusinski, Olivier

    2014-01-01

    In the second half of the 19th century, Jean-Martin Charcot (1825-1893) became famous for the quality of his teaching and his innovative neurological discoveries, bringing many French and foreign students to Paris. A hunger for recognition, together with progressive and anticlerical ideals, led Charcot to invite writers, journalists, and politicians to his lessons, during which he presented the results of his work on hysteria. These events became public performances, for which physicians and patients were transformed into actors. Major newspapers ran accounts of these consultations, more like theatrical shows in some respects. The resultant enthusiasm prompted other physicians in Paris and throughout France to try and imitate them. We will compare the form and substance of Charcot's lessons with those given by Jules-Bernard Luys (1828-1897), Victor Dumontpallier (1826-1899), Ambroise-Auguste Liébault (1823-1904), Hippolyte Bernheim (1840-1919), Joseph Grasset (1849-1918), and Albert Pitres (1848-1928). We will also note their impact on contemporary cinema and theatre.

  17. The Great Cometary Show

    Science.gov (United States)

    2007-01-01

    its high spatial and spectral resolution, it was possible to zoom into the very heart of this very massive star. In this innermost region, the observations are dominated by the extremely dense stellar wind that totally obscures the underlying central star. The AMBER observations show that this dense stellar wind is not spherically symmetric, but exhibits a clearly elongated structure. Overall, the AMBER observations confirm that the extremely high mass loss of Eta Carinae's massive central star is non-spherical and much stronger along the poles than in the equatorial plane. This is in agreement with theoretical models that predict such an enhanced polar mass-loss in the case of rapidly rotating stars. ESO PR Photo 06c/07 ESO PR Photo 06c/07 RS Ophiuchi in Outburst Several papers from this special feature focus on the later stages in a star's life. One looks at the binary system Gamma 2 Velorum, which contains the closest example of a star known as a Wolf-Rayet. A single AMBER observation allowed the astronomers to separate the spectra of the two components, offering new insights in the modeling of Wolf-Rayet stars, but made it also possible to measure the separation between the two stars. This led to a new determination of the distance of the system, showing that previous estimates were incorrect. The observations also revealed information on the region where the winds from the two stars collide. The famous binary system RS Ophiuchi, an example of a recurrent nova, was observed just 5 days after it was discovered to be in outburst on 12 February 2006, an event that has been expected for 21 years. AMBER was able to detect the extension of the expanding nova emission. These observations show a complex geometry and kinematics, far from the simple interpretation of a spherical fireball in extension. AMBER has detected a high velocity jet probably perpendicular to the orbital plane of the binary system, and allowed a precise and careful study of the wind and the shockwave

  18. Enhanced accumulation and storage of mercury on subtropical evergreen forest floor: Implications on mercury budget in global forest ecosystems

    Science.gov (United States)

    Wang, Xun; Lin, Che-Jen; Lu, Zhiyun; Zhang, Hui; Zhang, Yiping; Feng, Xinbin

    2016-08-01

    Forest ecosystems play an important role in the global cycling of mercury (Hg). In this study, we characterized the Hg cycling at a remote evergreen broadleaf (EB) forest site in southwest China (Mount Ailao). The annual Hg input via litterfall is estimated to be 75.0 ± 24.2 µg m-2 yr-1 at Mount Ailao. Such a quantity is up to 1 order of magnitude greater than those observed at remote temperate/boreal (T/B) forest sites. Production of litter biomass is found to be the most influential factor causing the high Hg input to the EB forest. Given their large areal coverage, Hg deposition through litterfall in EB forests is appropriately 9 ± 5 Mg yr-1 in China and 1086 ± 775 Mg yr-1 globally. The observed wet Hg deposition at Mount Ailao is 4.9 ± 4.5 µg m-2 yr-1, falling in the lower range of those observed at 49 T/B forest sites in North America and Europe. Given the data, the Hg deposition flux through litterfall is approximately 15 times higher than the wet Hg deposition at Mount Ailao. Steady Hg accumulation in decomposing litter biomass and Hg uptake from the environment were observed during 25 months of litter decomposition. The size of the Hg pool in the organic horizon of EB forest floors is estimated to be up to 2-10 times the typical pool size in T/B forests. This study highlights the importance of EB forest ecosystems in global Hg cycling, which requires further assessment when more data become available in tropical forests.

  19. 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

  20. 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

  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. HgL(3) XANES Study of Mercury Methylation in Shredded Eichhornia Crassipes

    Energy Technology Data Exchange (ETDEWEB)

    Rajan, M.; Darrow, J.; Hua, M.; Barnett, B.; Mendoza, M.; Greenfield, B.K.; Andrews, J.C.

    2009-05-21

    Eichhornia crassipes (water hyacinth) is a non-native plant found in abundance in the Sacramento-San Joaquin River Delta (hereafter called Delta). This species has become a problem, clogging waterways and wetlands. Water hyacinth are also known to accumulate mercury. Recent attempts to curb its proliferation have included shredding with specialized boats. The purpose of this research is to better understand the ability of water hyacinth to phytoremediate mercury and to determine the effect of shredding and anoxic conditions on mercury speciation in plant tissue. In the field assessment, total mercury levels in sediment from the Dow Wetlands in the Delta were found to be 0.273 {+-} 0.070 ppm Hg, and levels in hyacinth roots and shoots from this site were 1.17 {+-} 0.08 ppm and 1.03 {+-} 0.52 ppm, respectively, indicating bioaccumulation of mercury. Plant samples collected at this site were also grown in nutrient solution with 1 ppm HgCl{sub 2} under (1) aerobic conditions, (2) anaerobic conditions, and (3) with shredded plant material only. The greatest accumulation was found in the roots of whole plants. Plants grown in these conditions were also analyzed at Stanford Synchrotron Radiation Laboratory using Hg L{sub 3} X-ray Absorption Near Edge Spectroscopy (XANES), a method to examine speciation that is element-specific and noninvasive. Least-squares fitting of the XANES data to methylated and inorganic mercury(II) model compounds revealed that in plants grown live and aerobically, 5 {+-} 3% of the mercury was in the form of methylmercury, in a form similar to methylmercury cysteine. This percentage increased to 16 {+-} 4% in live plants grown anaerobically and to 22 {+-} 6% in shredded anaerobic plants. We conclude that shredding of the hyacinth plants and, in fact, subjection of plants to anaerobic conditions (e.g., as in normal decay, or in crowded growth conditions) increases mercury methylation. Mechanical removal of the entire plant is significantly more

  3. Risk assessments of PAHs and Hg exposure via settled house dust and street dust, linking with their correlations in human hair.

    Science.gov (United States)

    Wang, Wei; Wu, Fuyong; Zheng, Jinshu; Wong, Ming Hung

    2013-12-15

    Domestic energy, chemicals bioaccessibility and particle size were found as three critical factors for risk assessment of PAHs exposure via settled house dust (SHD) and street dust. ∑PAHs and Hg contained in SHD were significantly (p10(-4)) via SHD exposure. The highest accumulation trend of PAHs and Hg were found in PAHs led to a significant decrease on related cancer risks and decreased in the order of 1.9, 1.1, 0.6 and 0.4 μg g(-1) with the increase of particle sizes (PAHs (0.05-0.9 μg g(-1)) and Hg (0.04-1.6 μg g(-1)). Different PAHs profiles were found between PAHs in SHD and those of hair, indicating that exogenous exposure to PAHs adsorbed on dust was not the major source of hair PAHs.

  4. Fluorescent probes for "off-on" highly sensitive detection of Hg²⁺ and L-cysteine based on nitrogen-doped carbon dots.

    Science.gov (United States)

    Zhang, Yi; Cui, Peipei; Zhang, Feng; Feng, Xiaoting; Wang, Yaling; Yang, Yongzhen; Liu, Xuguang

    2016-05-15

    Fluorescent nitrogen-doped carbon dots (NCDs) were synthesized by a facile, and low-cost one-step hydrothermal strategy using citric acid as carbon source and ammonia solution as nitrogen source for the first time. The obtained NCDs show stable blue fluorescence with a high quantum yield of 35.4%, along with the fluorescence lifetime of ca. 6.75 ns. Most importantly, Hg(2+) can completely quench the fluorescence of NCDs as a result of the formation of a non-fluorescent stable NCDs-Hg(2+) complex. Static fluorescence quenching towards Hg(2+) is proved by the Stern-Volmer equation, ultraviolet-visible absorption spectra, temperature dependent quenching and fluorescence lifetime measurements. Subsequently, the fluorescence of the NCDs-Hg(2+) system is completely recovered with the addition L-cysteine (L-Cys) owing to the dissociation of NCDs-Hg(2+) complex to form a more stable Hg(2+)-L-Cys complex by Hg(2+)-S bonding. Therefore, such NCDs can be used as an effective fluorescent "turn-off" probe for rapid, rather highly selective and sensitive detection of Hg(2+), with a limit of detection (LOD) as low as 1.48 nM and a linear detection range of 0-10 μM. Interestingly, NCDs-Hg(2+) system can be conveniently employed as a fluorescent "turn-on" sensor for highly selective and sensitive detection of L-Cys with a low LOD of 0.79 nM and a wide linear detection range of 0-50 μM. Further, the sensitivity of NCDs to Hg(2+) is preserved in tap water with a LOD of 1.65 nM and a linear detection range of 0-10 μM.

  5. DISTRIBUIÇÃO E FRACIONAMENTO DO Hg EM SEDIMENTOS DO RIO PARAÍBA DO SUL – RJ, BRASIL

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    Beatriz Ferreira Araujo

    2015-01-01

    Full Text Available Mercury distribution and fractionation were determined in sediments from the Paraíba do Sul River – RJ, Brazil. Total mercury concentration ranged from 1 to 158 ng g-1. Hg associated with the weakly bound fraction was dominant in the estuarine areas (main - 60% and secondary - 55%; followed by fluvial end member (48% and mangrove (18%. These results reinforce the mercury availability to fluvial and estuarine areas and emphasize the key role played by mangroves as an efficient biogeochemical barrier. In conclusion, the continuous reduction of the mangrove ecosystem around the world can exacerbate the damage resulting from the mercury accumulation.

  6. 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

    Hg urine concentration was detected in group I and group II (involved and not involved in gold recovery) at average levels of 15.82 and 9.95 microg/g creatinine, respectively. The average Hg values for both groups were below the established levels indicating no risk from Hg intake. Average Hg hair level in all schoolchildren (0.93 microg/g) was not significantly higher than reference group. There were two variables (gender and personal hygiene) which affected the concentration of Hg in urine of schoolchildren (P < 0.05). The result (HQ) also suggested that schoolchildren were not at risk (< 1). Schoolchildren involved in gold mining activities showed some indirect exposure to Hg from the adults working in mining area.

  7. 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.

  8. 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.

  9. 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+).

  10. Antiproton Accumulator (AA)

    CERN Multimedia

    Photographic Service

    1980-01-01

    The AA in its final stage of construction, before it disappeared from view under concrete shielding. Antiprotons were first injected, stochastically cooled and accumulated in July 1980. From 1981 on, the AA provided antiprotons for collisions with protons, first in the ISR, then in the SPS Collider. From 1983 on, it also sent antiprotons, via the PS, to the Low-Energy Antiproton Ring (LEAR). The AA was dismantled in 1997 and shipped to Japan.

  11. 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.

  12. [Effect of temperature on kinetic of soil urease inhibited by Hg].

    Science.gov (United States)

    Yang, Chun-Lu; Sun, Tie-Heng; He, Wen-Xiang; Song, Xue-Ying

    2007-02-01

    Urease kinetics inhibited by Hg in two meadow burozem, fertilized by different ways and two phaeozem soils with different organic matter content was investigated at different temperatures. The results showed that the urease activity and kinetic parameter V(max) and V(max)/K(m) were higher in soils with high organic matter content than that in soils with low organic matter among the same soil type. It indicated that organic matter had great adsorption capacity to urease. Soil urease V(max) and V(max)/K(m) in phaeozem were generally higher than that in meadow organic matter had great adsorption capacity to urease. Soil urease V(max) and V(max)/K(m) in phaeozem were generally higher than that in meadow burozem, but urease activity and K(m) were not comparable among different soil types. K(m) depended on not only the organic matter content of soils, but also fertilization ways. As incubating temperature increased, urease activity, V(max) and V(max)/K(m) value enhanced under the optical catalysis temperature. Hg behaved as uncompetitive inhibitor to soil urease in this experiment. The negative effect that Hg inhibited urease activity, K(m), V(max) and V(max)/K(m) increased with temperature increasing, indicated that the protective capacity of soil on urease decreased with the temperature increasing.

  13. 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.

  14. Hg(II) adsorption using amidoximated porous acrylonitrile/itaconic copolymers prepared by suspended emulsion polymerization.

    Science.gov (United States)

    Ji, Chunnuan; Qu, Rongjun; Chen, Hou; Liu, Xiguang; Sun, Changmei; Ma, Caixia

    2016-01-01

    Initially, porous acrylonitrile/itaconic acid copolymers (AN/IA) were prepared by suspended emulsion polymerization. Successively, the cyano groups in AN/IA copolymers were converted to amidoxime (AO) groups by the reaction with hydroxylamine hydrochloride. The structures of the AN/IA and amidoximated AN/IA (AO AN/IA) were characterized by infrared spectroscopy, scanning electron microscopy, and porous structural analysis. The adsorption properties of AO AN/IA for Hg(II) were investigated. The results show that AO AN/IA has mesopores and macropores, and surface area of 11.71 m(2) g(-1). It was found that AO AN/IA has higher affinity for Hg(II), with the maximum adsorption capacity of 84.25 mg g(-1). The AO AN/IA also can effectively remove Hg(II) from different binary metal ion mixture systems. Furthermore, the adsorption kinetics and thermodynamics were studied in detail. The adsorption equilibrium can quickly be achieved in 4 h determined by an adsorption kinetics study. The adsorption process is found to belong to the second-order model, and can be described by the Freundlich model.

  15. Recent progress in the doping of MBE HgCdTe

    Science.gov (United States)

    Sivananthan, Sivalingam; Wijewarnasuriya, P. S.; Faurie, Jean-Pierre

    1995-09-01

    We present a review of the recent progress in the doping of HgCdTe grown by molecular beam epitaxy. A detailed analysis of the unintentional/intrinsic, n-type, and p-type doping is presented. Our results show that CdZnTe substrates should be carefully screened to reduce the out-diffusion of impurities from the substrate. N-type HgCdTe layers exhibit excellent Hall characteristics down to indium levels of 2 X 10(superscript 15) cm(superscript -3). Electron mobilities in the range of (2 - 3) X 10(superscript 5) cm(superscript 2)/vs at 23 K were obtained. Measured lifetime data fits very well with the intrinsic band-to-band recombination. However, below 2 X 10(superscript 15) cm(superscript -3) doping levels, minority carrier lifetime is limited by Schockley-Reed recombination. We have implemented planar doping with arsenic as p-type dopant during MBE growth. Our results clearly indicate that arsenic incorporates as an acceptor dopant during the growth of MBE HgCdTe.

  16. No magnetic field in the spotted HgMn star mu Leporis

    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

    2011-01-01

    Chemically peculiar stars of the mercury-manganese (HgMn) type represent a new class of spotted late-B stars, in which evolving surface chemical inhomogeneities are apparently unrelated to the presence of strong magnetic fields but are produced by some hitherto unknown astrophysical mechanism. The goal of this study is to perform a detailed line profile variability analysis and carry out a sensitive magnetic field search for one of the brightest HgMn stars - mu Lep. We acquired a set of very high-quality intensity and polarization spectra of mu Lep with the HARPSpol polarimeter. These data were analyzed with the multiline technique of least-squares deconvolution in order to extract information on the magnetic field and line profile variability. Our spectra show very weak but definite variability in the lines of Sc, all Fe-peak elements represented in the spectrum of mu Lep, as well as Y, Sr, and Hg. Variability might also be present in the lines of Si and Mg. Anomalous profile shapes of Ti II and Y II lines s...

  17. Mechanism of Hg(0) oxidation in the presence of HCl over a commercial V2O5-WO3/TiO2 SCR catalyst.

    Science.gov (United States)

    Liu, Ruihui; Xu, Wenqing; Tong, Li; Zhu, Tingyu

    2015-10-01

    Experiments were conducted in a fixed-bed reactor containing a commercial V2O5/WO3/TiO2 catalyst to investigate mercury oxidation in the presence of HCl and O2. Mercury oxidation was improved significantly in the presence of HCl and O2, and the Hg(0) oxidation efficiencies decreased slowly as the temperature incre