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Sample records for hg accumulation profile

  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. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Searching for Line Profile Variability in HgMn Stars

    CERN Document Server

    Turcotte, S; Knoglinger, P

    2002-01-01

    Spectra of four non-magnetic chemically peculiar late B type stars (HgMn) stars are analysed to detect periodic spectral line variations (LPVs). A procedure developed to study LPVs in Slowly Pulsating B stars has been adopted as pulsational properties of HgMn stars should be expected to be similar. In the preliminary results discussed here no conclusive evidence for periodic LPVs was uncovered. A more sensitive re-analysis of the data is under way.

  8. 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.

  9. 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.

  10. 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.

  11. 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 ...

  12. 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.

  13. 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.

  14. Quantitative damage depth profiles in arsenic implanted HgCdTe

    Energy Technology Data Exchange (ETDEWEB)

    Lobre, C., E-mail: clement.lobre@cea.fr [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Jalabert, D. [CEA-INAC/UJF-Grenoble 1 UMR-E, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Vickridge, I.; Briand, E.; Benzeggouta, D. [Institut des NanoSciences de Paris, UMR 7588 du CNRS, Universite de Pierre et Marie Curie, Paris (France); Mollard, L. [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Jouneau, P.H. [CEA-INAC/UJF-Grenoble 1 UMR-E, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Ballet, P. [CEA-Leti, MINATEC, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)

    2013-10-15

    Rutherford backscattering experiments under channeling conditions (RBS-c) have been carried out on Hg{sub 0.77}Cd{sub 0.23}Te (MCT) layers implanted with arsenic. Accurate damage profiles have been extracted through a simple formalism for implanted and annealed layers. Quantitative damage profiles are correlated with structural defects observed by bright-field scanning transmission electron microscopy (BF-STEM) and chemical composition measured by secondary ion mass spectrometry (SIMS). Evolution of damage for increasing ion implantation fluence has been investigated by these three complementary techniques. Evidence is found of irradiation induced annealing during implantation. A fast damage recovery has been observed for post-implantation thermal anneals. In the case of an implanted layer annealed during 1 h, the damage profile, associated with arsenic concentration measurements, indicates the presence of complexes involving arsenic.

  15. A Transformational Approach to Parametric Accumulated-Cost Static Profiling

    DEFF Research Database (Denmark)

    Haemmerlé, Rémy; López García, Pedro; Liqat, Umer

    2016-01-01

    Traditional static resource analyses estimate the total resource usage of a program, without executing it. In this paper we present a novel resource analysis whose aim is instead the static profiling of accumulated cost, i.e., to discover, for selected parts of the program, an estimate or bound...... of the resource usage accumulated in each of those parts. Traditional resource analyses are parametric in the sense that the results can be functions on input data sizes. Our static profiling is also parametric, i.e., our accumulated cost estimates are also parameterized by input data sizes. Our proposal is based...... on the concept of cost centers and a program transformation that allows the static inference of functions that return bounds on these accumulated costs depending on input data sizes, for each cost center of interest. Such information is much more useful to the software developer than the traditional resource...

  16. Two age-related accumulation profiles of toxic metals.

    Science.gov (United States)

    Yasuda, Hiroshi; Yoshida, Kazuya; Yasuda, Yuichi; Tsutsui, Toyoharu

    2012-07-01

    In order to investigate the body burden levels of toxic metals in Japanese, five toxic metal concentrations in scalp hair samples from 28,424 subjects from infant to elderly were determined with inductively coupled plasma mass spectrometry (ICP-MS). The geometric mean of hair mercury concentrations showed a high-significant age-correlated increase (r = 0.341, p female) in mercury accumulation. Arsenic also showed a similar accumulation profile with age dependency and gender difference in adult subjects. In contrast, cadmium, lead and aluminium exhibited another type of accumulation profile: the highest burden level was observed in infants aged 0-3 years old for every element in both sexes. In addition, cadmium was found to have a character accumulating in aged females, with significant age-dependency (r = 0.134, p male). These findings suggest that toxic metals are classified into two families on the basis of their accumulation profiles, and that the three elements of mercury, arsenic and cadmium which accumulate age-dependently in adults, may play a role in aging process and higher burden with them may lead to acceleration of aging.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. The use of helium ion RBS for profiling epitaxial layers of Cd sub x Hg sub 1-x Te

    Energy Technology Data Exchange (ETDEWEB)

    Avery, A.J.; Diskett, D.J.; Lane, D.W. (Royal Military Coll. of Science, Shrivenham, Swindon, Wiltshire (UK)); Giess, J.; Irvine, S.J.C. (Royal Signals and Radar Establishment, Malvern, Worcestershire (UK))

    1990-01-01

    This paper describes the application of helium ion RBS and channelling to the characterization of an epitaxial layer of Cd{sub x}Hg{sub 1-x}Te. The layer was grown by MOVPE on a substrate of GaAs as part of a programme for developing infrared detector materials. The use of RBS with the aid of computer techniques is discussed for obtaining compositional (x) profiles both within the layers and, in particular, in the near-surface region. Conventional- and grazing-geometry measurements have been used to establish layer quality and interfacial abruptness. Variations in composition close to the surface have been correlated with the conditions under which layer growth was terminated. Channelling measurements are presented for the assessment of the layer crystalline quality. (orig.).

  2. Mercury profiles in sediment from the marginal high of Arabian Sea: An indicator of increasing anthropogenic Hg input

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Vudamala, K.; Chennuri, K.; Armoury, K.; Linsy, P.; Ramteke, D.; Sebastian, T.; Jayachandran, S.; Naik, C.; Naik, R.; Nath, B.N.

    the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests...

  3. 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

    the town. Atmospheric Hg deposition was found low in variability within the whole study area. Mercury in the soil accumulated mainly in the 0~20 cm soil horizon, however, Hg accumulation could still be found at 60 cm in depth. The percentages of soil Hg in mobile and semi-mobile state to total Hg did not vary much in the whole soil profile. Obvious soil Hg accumulation observed in the studied area led to higher Hg concentrations in rice. The concentration in quite a number of sampling sites already exceeded the second grade criterion of the National Standard for Soil Environmental Quality ( 300 μg kg - 1 ) and the National Food Safety Standard (20 μg kg - 1 ), and would bring about hazard to the environment quality and human health. The fact that balance is maintained between the soil conditions and Hg accumulation in soil and that the low atmospheric Hg deposition indicate that the ongoing accumulation is not as significant. Measures such as remediation of the polluted soil or rotation of low-Hg-uptake crop species should be taken to reduce soil Hg or to inhibit Hg uptake by crops, and hence to achieve the target of environmental management.

  4. Nitrate Accumulation in Soil Profile of Dry Land Farming in Northwest China

    Institute of Scientific and Technical Information of China (English)

    FAN Jun; HAO Ming-De; SHAO Ming-An

    2003-01-01

    A long-term fertilizer experiment on dry land of the Loess Plateau, northwest China, has been conducted since 1984 to study the distribution and accumulation of NO3-N down to a depth of 400 cm in the profile of a coarse-textured dark loessial soil after continuous winter wheat cropping. Thirteen fertilizer treatments consisted of four levels of N and P applied alone or in combination. Annual N and P (P2O5) rates were 0,45, 90, 135 and 180 kg ha-1. After 15 successive cropping cycles, the soil samples were taken from each treatment for analysis of NO3-N concentration. The results showed that NO3-N distribution in the soil profile was quite different among the treatments. The application of fertilizer N alone resulted in higher NO3-N concentration in the soil profile than the combined application of N and P, showing that application of P could greatly reduce the NO3-N accumulation. With an annual application of 180 kg N ha-1 alone, a peak in NO3-N accumulation occurred at 140 cm soil depth, and the maximum NO3-N concentration in the soils was 67.92 mg kg-1. The amount of NO3-N accumulated in the soil profile decreased as the cumulative N uptake by the winter wheat increased. Application of a large amount of N resulted in lower N recoveries in winter wheat and greater NO3-N accumulation in soil profile. NO3-N did not enter underground water in the study region; therefore, there is no danger of underground water pollution. Amount of NO3-N accumulation can be predicted by an equation according to annual N and P rates based on the results of this experiment.

  5. Nitrogen accumulation profiles of selected grain and vegetable crops: A bibliography (1940-1992)

    Energy Technology Data Exchange (ETDEWEB)

    Meischen, S.J.; Byrd, K.R.

    1994-10-01

    A bibliography of nitrogen accumulation profile data for 25 vegetable and grain crops reported between 1940 and 1992 is presented. The selected crops are asparagus, broccoli, brussels sprouts, cabbage, carrots, cauliflower, celery, corn, cotton, cucumber, field bean, field pea, garlic, lettuce, onions, and peppers.

  6. 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.

  7. 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.

  8. Assessment of micro, macro, toxic elements (Cd, Hg, Pb) and fatty acids profile in consumed fish commercially available in Cananeia and Cubatao, Sao Paulo State; Avaliacao de micro e macroelementos, elementos toxicos (Cd, Hg e Pb) e acidos graxos, em peixes disponiveis comercialmente para consumo em Cananeia e Cubatao, Estado de Sao Paulo

    Energy Technology Data Exchange (ETDEWEB)

    Curcho, Michel Rodrigues da Silva Morales

    2009-07-01

    Aside from their nutritional importance, fish are considered one of the most important bio indicators in aquatic systems for the estimation of pollution levels by toxic metals. This is so, since fish can bio accumulate these elements and they occupy different trophic levels and present different sizes and age. The purpose of the present study was to contribute with important data for the knowledge of nutritional and toxic constituents in muscles of the most consumed fish species from two coastal regions, Cananeia and Cubatao. Cananeia fish species analyzed were: Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Centropomus undecimalis (Robalo peba) and Mugil platanus (Tainha). From Cubatao, Micropogonias furnieri (Corvina), Macrodon ancylodon (Pescada), Menticirrhus americanus (Perna de moca), Sardella braziliensis (Sardinha) and Mugil liza (Tainha). For this study, analytical methodologies were developed and validated, regarding precision and accuracy, by means of certified reference materials. Micronutrients (Ca, Fe, K, Na, Se and Zn) and some trace elements (As, Br, Co, Cr, Rb) in fish muscle were determined by means of neutron activation analysis (NAA). Cold Vapor Atomic Absorption Spectrometry (CV AAS) was used for total Hg determination and Electrothermal Atomic Absorption Spectrometry (ET AAS) for Cd and Pb determinations. Proximate composition determinations according to AOAC methodologies and fatty acids profiles by gas chromatography were done in these muscle fish samples. Regarding fatty acids profile from the {omega}-6 family, Tainha species pool presented the highest values (8.9%) and Pescada species pool the lowest ones (4.4%) for Cananeia species. Fatty acids from the {omega}-3 family, Sardinha pool species presented the highest values (31.8%) for all species analyzed. Regarding micronutrients content great concentration variations between individual of the same species and between different species were observed. Discriminate analysis

  9. Correlation between protein accumulation profiles and conventional toxicological findings using a model antiandrogenic compound, flutamide.

    Science.gov (United States)

    Friry-Santini, Claire; Rouquié, David; Kennel, Philippe; Tinwell, Helen; Benahmed, Mohamed; Bars, Rémi

    2007-05-01

    In conventional rodent toxicity studies the characterization of the adverse effects of a chemical relies primarily on gravimetric, and histopathological data. The aim of this study was to evaluate if the use of two-dimensional gel electrophoresis could generate protein accumulation profiles, which were in accordance with conventional toxicological findings by investigating a model antiandrogen, flutamide (FM), whose toxic effects, as measured using standard approaches, are well characterized. Male Sprague-Dawley rats were orally exposed to FM (0, 6, 30, and 150 mg/kg/day) for 28 days. The expected inhibition of androgen-dependent tissue stimulation, increased luteinizing hormone and testosterone plasma levels, and Leydig cell hyperplasia were observed. Changes in testicular protein accumulation profiles were evaluated in rats exposed to 150 mg/kg/day FM. Several proteins involved in steroidogenesis (e.g., StAR, ApoE, Hmgcs1, Idi1), cell cycle, and cancer (e.g., Ddx1, Hspd1) were modulated by FM, and these data provided molecular evidence for the hormonal and testicular histopathology changes recorded. Changes in proteins associated with spermatogenesis were also recorded, and these are discussed within the context of the testicular phenotype observed following FM treatment (i.e., normal spermatogenesis but Leydig cell hyperplasia). Overall, our data indicate that the combination of conventional toxicology measurements with omic observations has the potential to improve our global understanding of the toxicity of a compound.

  10. 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.

  11. Diversity in the carotenoid profiles and the expression of genes related to carotenoid accumulation among citrus genotypes

    OpenAIRE

    Ikoma, Yoshinori; Matsumoto, Hikaru; Kato, Masaya

    2016-01-01

    Carotenoids are not only important to the plants themselves but also are beneficial to human health. Since citrus fruit is a good source of carotenoids for the human diet, it is important to study carotenoid profiles and the accumulation mechanism in citrus fruit. Thus, in the present paper, we describe the diversity in the carotenoid profiles of fruit among citrus genotypes. In regard to carotenoids, such as β-cryptoxanthin, violaxanthin, lycopene, and β-citraurin, the relationship between t...

  12. 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.

  13. Accumulation Profile of Heavy Metals in Fish Samples from Nsawam, Along the Densu River, Ghana

    Directory of Open Access Journals (Sweden)

    A.K. Anim

    2011-01-01

    Full Text Available The present study was carried out to investigate the accumulation profile of heavy metals in five fish species namely; Heterotis niloticus, Channa obscura, Hepsetus odoe, Tilapia zilli and Clarias gariepinus. Concentrations of Fe, Mn, Cu, Zn, Ca, Cd, and Pb were measured in all the sam ples analysed. Ni, Co and Cr however, recorded 80, 60 and 20% incidence respectively in the fish samples. The highest mean concentration, 110.56±0.86 mg/kg was recorded for Cu in Hepsetus odoe. Ni, Co, and Cr measured relatively lower concentrations from as low as <0.01 mg/kg, <0.005 mg/kg and <0.001 mg/kg respectively been their respective detection limits. The least detectable concentration, 0.08±0.01 mg/kg was measured for Pb in Clarias gariepinus. Most of the heavy metals were within the recommended maximum guidelines. The concentration of Cu measured in all the samples however, exceeded the FAO maximum limit of 30 mg/kg. Similarly, the concentration of Mn measured in all the fish samples exceeded the WHO limit of 0.5 mg/L in drinking water. All the concentrations measured for Pb, were below the FAO limit of 0.5 mg/kg except 0.94±0.30 mg/kg, measured in Hepsetus odoe which exceeded the limit. The mean of the total concentration of each metal in all the samples indicate that the concentrations of the heavy metals in the samples are generally well below and or within the respective recommended guidelines. Thus fish species from the Densu river, harvested at Nsawam are safe for human consumption.

  14. Gene Expression Profiling of Development and Anthocyanin Accumulation in Kiwifruit (Actinidia chinensis Based on Transcriptome Sequencing.

    Directory of Open Access Journals (Sweden)

    Wenbin Li

    Full Text Available Red-fleshed kiwifruit (Actinidia chinensis Planch. 'Hongyang' is a promising commercial cultivar due to its nutritious value and unique flesh color, derived from vitamin C and anthocyanins. In this study, we obtained transcriptome data of 'Hongyang' from seven developmental stages using Illumina sequencing. We mapped 39-54 million reads to the recently sequenced kiwifruit genome and other databases to define gene structure, to analyze alternative splicing, and to quantify gene transcript abundance at different developmental stages. The transcript profiles throughout red kiwifruit development were constructed and analyzed, with a focus on the biosynthesis and metabolism of compounds such as phytohormones, sugars, starch and L-ascorbic acid, which are indispensable for the development and formation of quality fruit. Candidate genes for these pathways were identified through MapMan and phylogenetic analysis. The transcript levels of genes involved in sucrose and starch metabolism were consistent with the change in soluble sugar and starch content throughout kiwifruit development. The metabolism of L-ascorbic acid was very active, primarily through the L-galactose pathway. The genes responsible for the accumulation of anthocyanin in red kiwifruit were identified, and their expression levels were investigated during kiwifruit development. This survey of gene expression during kiwifruit development paves the way for further investigation of the development of this uniquely colored and nutritious fruit and reveals which factors are needed for high quality fruit formation. This transcriptome data and its analysis will be useful for improving kiwifruit genome annotation, for basic fruit molecular biology research, and for kiwifruit breeding and improvement.

  15. Profile Characteristics and Potential Environmental Effect of Accumulated Phosphorus in Soils ofVegetable Fields in Beijing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Profile characteristics of accumulated P in 10 representative soils of vegetable fields in suburban districts of Beijing were investigated. Bioavailability of the accumulated P and its potential effect on the environment were studied in a greenhouse pot experiment and a soil column experiment. The results showed that the concentration of Olsen-P in the 0~20 cm soil samples of the vegetable fields ranged from 22.1 to 358.0 mg kg-1, which was 2 to 10 times higher than that of the crop fields in the suburbs of Beijing. Most of the excessive phosphorus was accumulated in the topsoils. The longer the soils cultivated with vegetables, the higher the soil total P, Olsen-P and organic matter concentration. Accumulated P in the soils from vegetable fields had higher bioavailability. Application of phosphorus fertilizer could not increase the dry weights of cucumbers, Chinese cabbage, and rape seedlings continuously planted. The soil column study showed high P concentration (> 0.6 mg L-1) in the leachates from the columns of the vegetable field soils with high accumulated P, which has a potential effect on the groundwater and natural water quality.

  16. Diversity in the carotenoid profiles and the expression of genes related to carotenoid accumulation among citrus genotypes.

    Science.gov (United States)

    Ikoma, Yoshinori; Matsumoto, Hikaru; Kato, Masaya

    2016-01-01

    Carotenoids are not only important to the plants themselves but also are beneficial to human health. Since citrus fruit is a good source of carotenoids for the human diet, it is important to study carotenoid profiles and the accumulation mechanism in citrus fruit. Thus, in the present paper, we describe the diversity in the carotenoid profiles of fruit among citrus genotypes. In regard to carotenoids, such as β-cryptoxanthin, violaxanthin, lycopene, and β-citraurin, the relationship between the carotenoid profile and the expression of carotenoid-biosynthetic genes is discussed. Finally, recent results of quantitative trait locus (QTL) analyses of carotenoid contents and expression levels of carotenoid-biosynthetic genes in citrus fruit are shown.

  17. Firn density profile at Megadunes, East Antarctica, calls for an improved densification model for low accumulation sites.

    Science.gov (United States)

    Suwa, M.; Severinghaus, J. P.

    2004-12-01

    We report a density profile of the firn at Megadunes, East Antarctica (80o78'S; 124o50'E). The Megadunes site is characterized by a low mass accumulation rate (2.9 g/cm2/yr) and cold temperature (mean annual = -49.5oC). Validating existing firn densification models using a density profile of such a site is important because such models, either purely empirical or mechanistic, have been calibrated with few sites that are analogous to a glacial condition (ultralow accumulation and temperature). We make use of CO2 concentrations in the lock-in (or non-diffusive) zone to obtain the accumulation rate, assuming that the gas in the lock-in zone ages at the same rate as the surrounding ice [Battle et al., 1996], and assuming that the gas enclosure rate must equal the long-term mean accumulation rate. This estimate is preliminary and may change when results from beta analysis of cores become available. Our density profile shows that the widely used pure empirical model by Herron and Langway [1980] overestimates the close-off depth by 16 %, and the semi-mechanistic model by Pimienta and Barnola [Barnola et al., 1991] also overestimates the close-off depth by 26 %. Our study at the Megadunes site indicates that the δ 15N of N2 paradox for glacial ice from East Antarctica would have partly resulted from a poorly calibrated densification model for a `glacial-like' condition and a thick convective zone as we observed at the Megadunes site [Severinghaus et al., in prep].

  18. Spacial and temporal profiles of neutrophil accumulation in the reperfused ischemic myocardium

    Energy Technology Data Exchange (ETDEWEB)

    de Lorgeril, M.; Rousseau, G.; Basmadjian, A.; St-Jean, G.; Tran, D.C.; Latour, J.G. (Montreal Heart Institute, Quebec (Canada))

    1990-01-01

    To elucidate further the pathogenic role of neutrophils in evolving reperfused myocardial infarction, we investigated the dynamics of their accumulation and distribution in the ischemic myocardium. The left anterior descending coronary artery was occluded in dogs for 2 hours followed by reperfusion for 0, 3, 6, or 24 hours. 111In-labeled neutrophils were injected at the time of occlusion or after 16 hours of reperfusion. The area at risk was similar among groups. Infarct size expressed in percent of the area at risk was identical between groups reperfused for 6 (35.2 +/- 4.4%) or 24 (32.3 +/- 3.9%) hours but smaller (22.0 +/- 4.4%; p less than 0.05) after 3 hours of reperfusion. 111In-neutrophils accumulation quantified by scintigraphy correlated positively with infarct size (r = 0.64, p less than 0.005); accumulation rates (cells/h/cm2MI) were high during the first 3 (2288 +/- 754) and 6 hours (1953 +/- 463) but low (490 +/- 192) between 16 and 24 hours of reperfusion. Cells accumulating during reperfusion (12,566 +/- 2307 cells/g at 3 hours) were found within the borders of the necrotic area, and the cell counts (2420 +/- 724 cells/g, p less than 0.05) in the live tissue located within the area at risk after 3 hours of reperfusion were similar to those found in the subepicardium at the onset of reperfusion: (2240 +/- 571 cells/g). Only a few cells were detected in the normally perfused myocardium (67 +/- 33 cells/g). We conclude that reperfusion accumulation in the ischemic myocardium; the reaction takes place within 3-6 hours of reperfusion, a period of time where infarct size is growing by about 40%. These results support the concept that leukocytes may play a pathogenic role on infarct size in models with brief ischemia followed by reperfusion.

  19. Spacial and temporal profiles of neutrophil accumulation in the reperfused ischemic myocardium.

    Science.gov (United States)

    de Lorgeril, M; Rousseau, G; Basmadjian, A; St-Jean, G; Tran, D C; Latour, J G

    1990-01-01

    To elucidate further the pathogenic role of neutrophils in evolving reperfused myocardial infarction, we investigated the dynamics of their accumulation and distribution in the ischemic myocardium. The left anterior descending coronary artery was occluded in dogs for 2 hours followed by reperfusion for 0, 3, 6, or 24 hours. 111In-labeled neutrophils were injected at the time of occlusion or after 16 hours of reperfusion. The area at risk was similar among groups. Infarct size expressed in percent of the area at risk was identical between groups reperfused for 6 (35.2 +/- 4.4%) or 24 (32.3 +/- 3.9%) hours but smaller (22.0 +/- 4.4%; p less than 0.05) after 3 hours of reperfusion. 111In-neutrophils accumulation quantified by scintigraphy correlated positively with infarct size (r = 0.64, p less than 0.005); accumulation rates (cells/h/cm2MI) were high during the first 3 (2288 +/- 754) and 6 hours (1953 +/- 463) but low (490 +/- 192) between 16 and 24 hours of reperfusion. Cells accumulating during reperfusion (12,566 +/- 2307 cells/g at 3 hours) were found within the borders of the necrotic area, and the cell counts (2420 +/- 724 cells/g, p less than 0.05) in the live tissue located within the area at risk after 3 hours of reperfusion were similar to those found in the subepicardium at the onset of reperfusion: (2240 +/- 571 cells/g). Only a few cells were detected in the normally perfused myocardium (67 +/- 33 cells/g). We conclude that reperfusion accumulation in the ischemic myocardium; the reaction takes place within 3-6 hours of reperfusion, a period of time where infarct size is growing by about 40%. These results support the concept that leukocytes may play a pathogenic role on infarct size in models with brief ischemia followed by reperfusion.

  20. Fatigue accumulation and twitch potentiation during complex MVC-relative profiles.

    Science.gov (United States)

    Sonne, Michael W; Potvin, Jim R

    2015-08-01

    Fatigue accumulation can be significantly influenced by post-activation potentiation (PAP). This phenomenon leads to increased force generating capacity after a series of conditioning efforts. The purpose of our study was to examine how the order of force demands impacted muscle fatigue accumulation, and how fatigue was affected by potentiation. We had 33 participants complete one of four different force orders, consisting of 5 cycles of 12-s submaximal isometric "task plateaus". Every order consisted of 8 force plateaus of the different intensity, arranged in a different ways. A subset of 18 participants then received a stimulated muscle twitch, and all participants performed a brief MVC. Each task plateau was followed by a 12s long 10% MVC "reference plateau" also followed by twitch and MVC. Overall, the order of the force presentation only had an impact on fatigue levels and twitch potentiation during the first cycle. Maximum voluntary forces decreased, and twitch forces increased, at different rates between orders during the first cycle. At the end of each cycle, there was no difference between any of the orders in terms of twitch potentiation or decrease in MVC force. In a task that features identical force patterns, arranged in different orders, the order did not affect the final fatigue accumulation or potentiation level.

  1. Accumulation profiles of parabens and their metabolites in fish, black bear, and birds, including bald eagles and albatrosses.

    Science.gov (United States)

    Xue, Jingchuan; Kannan, Kurunthachalam

    2016-09-01

    Although several studies have reported the ubiquitous occurrence of parabens in human specimens and the environment, little is known about the accumulation of these estrogenic chemicals in fish and birds. In this study, accumulation profiles of six parabens and their metabolites were determined in 254 tissue (including liver, kidney, egg, and plasma) samples from 12 species of fish and seven species of birds collected from inland, coastal, and remote aquatic ecosystems. In addition, liver and kidney tissues from black bears were analyzed. Methyl paraben (MeP) was found in a majority of the tissues, with the highest concentration (796ng/g (wet weight [wet wt])) found in the liver of a bald eagle from Michigan. 4-Hydroxy benzoate (HB) was the major metabolite, found in 91% of the tissue samples analyzed at concentrations as high as 68,600ng/g, wet wt, which was found in the liver of a white-tailed sea eagle from the Baltic Sea coast. The accumulation pattern of MeP and 4-HB varied, depending on the species. The mean concentrations of MeP measured in fishes from Michigan, New York, and Florida waters were environment.

  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. HdhQ111 Mice Exhibit Tissue Specific Metabolite Profiles that Include Striatal Lipid Accumulation.

    Directory of Open Access Journals (Sweden)

    Jeffrey B Carroll

    Full Text Available The HTT CAG expansion mutation causes Huntington's Disease and is associated with a wide range of cellular consequences, including altered metabolism. The mutant allele is expressed widely, in all tissues, but the striatum and cortex are especially vulnerable to its effects. To more fully understand this tissue-specificity, early in the disease process, we asked whether the metabolic impact of the mutant CAG expanded allele in heterozygous B6.HdhQ111/+ mice would be common across tissues, or whether tissues would have tissue-specific responses and whether such changes may be affected by diet. Specifically, we cross-sectionally examined steady state metabolite concentrations from a range of tissues (plasma, brown adipose tissue, cerebellum, striatum, liver, white adipose tissue, using an established liquid chromatography-mass spectrometry pipeline, from cohorts of 8 month old mutant and wild-type littermate mice that were fed one of two different high-fat diets. The differential response to diet highlighted a proportion of metabolites in all tissues, ranging from 3% (7/219 in the striatum to 12% (25/212 in white adipose tissue. By contrast, the mutant CAG-expanded allele primarily affected brain metabolites, with 14% (30/219 of metabolites significantly altered, compared to wild-type, in striatum and 11% (25/224 in the cerebellum. In general, diet and the CAG-expanded allele both elicited metabolite changes that were predominantly tissue-specific and non-overlapping, with evidence for mutation-by-diet interaction in peripheral tissues most affected by diet. Machine-learning approaches highlighted the accumulation of diverse lipid species as the most genotype-predictive metabolite changes in the striatum. Validation experiments in cell culture demonstrated that lipid accumulation was also a defining feature of mutant HdhQ111 striatal progenitor cells. Thus, metabolite-level responses to the CAG expansion mutation in vivo were tissue specific and

  4. 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.

  5. Inheritance profile of weathered chlordane and p,p'-DDTs accumulation by Cucurbita pepo hybrids.

    Science.gov (United States)

    Isleyen, Mehmet; Sevim, Pinar; Hawthorne, Joseph; Berger, William; White, Jason C

    2013-01-01

    Cucurbita pepo ssp pepo (zucchini) accumulates significant levels of persistent organic pollutants in its roots, followed by unexpectedly high contaminant translocation to the stems. Most other plant species, including the closely related C. pepo ssp ovifera (squash), do not have this ability. To investigate the mechanism of contaminant accumulation, two cultivars each of parental zucchini and squash, as well as previously created first filial (F1) hybrids and F1 backcrosses (BC) of those parental cultivars, were grown under field conditions in a soil contaminated with weathered chlordane (2.29 microg/g) and DDX residues (0.30 microg/g; sum of DDT, DDE, DDD). The parental zucchini had stem-to-soil bioconcentration factors (BCF, contaminant ratio of stem to soil) for chlordane and DDX of 6.23 and 3.10; these values were 2.2 and 3.7 times greater than the squash, respectively. Chlordane and DDX translocation factors, the ratio of contaminant content in the stems to that in the root, were 2.1 and 3.2 times greater for zucchini than for squash. The parental zucchini and squash also differed significantly in chlordane component ratios (relative amounts of trans-nonachlor [TN], cis-chlordane [CC], trans-chlordane [TC]) and enantiomer fractions for the chiral CC and TC. Hybridization of the parental squash and zucchini resulted in significant differences in contaminant uptake. For both the three separate component ratios (CR) and two sets of enantiomer fraction (EF) values, subspecies specific differences in the parental generation became statistically equivalent in the F1 hybrid zucchini and squash. When backcrossed (BC) with the original parental plants, the zucchini and squash F1 BC cultivars reverted to the statistically distinct CR and EF patterns. This pattern of trait segregation upon hybridization suggests either single gene or single locus control for persistent organic pollutant (POP) uptake ability by C. pepo ssp pepo.

  6. Study on the diagenetic calcareous accumulations in a soil profile from Floresti (Cluj County, Romania

    Directory of Open Access Journals (Sweden)

    Horea Bedelean

    2004-04-01

    Full Text Available The studied calcretes developed in two different levels (horizons in the soil profile from Floreşti (Cluj County. The deposits outcropping in the area are represented by Bartonian-Priabonian sedimentary rocks (Ciuleni Member, Viştea Limestone and the Quaternary horizon (terrace of Someşul Mic River, consisting of pebbles of different origin, which represent the parent rock of the soil. A detailed petrographical and mineralogical description of the calcretes is given below, based on macroscopic, microscopic and X-ray diffraction analysis. It led to the conclusion that the calcretes from the studied profile have a pedogenic origin. The calcretes consist of distinctive subhorizons within the host horizon of the soil. According to their microstructure, the studied calcretes belong to the alpha-type and may be considered as “nodular calcretes” or “glaebular calcretes”. The source of carbonate was variable: from the parent material of the soil including fragments of carbonate rocks, bioclasts, vegetal rests, eolian dust.

  7. Sunlight Modulates Fruit Metabolic Profile and Shapes the Spatial Pattern of Compound Accumulation within the Grape Cluster

    Science.gov (United States)

    Reshef, Noam; Walbaum, Natasha; Agam, Nurit; Fait, Aaron

    2017-01-01

    Vineyards are characterized by their large spatial variability of solar irradiance (SI) and temperature, known to effectively modulate grape metabolism. To explore the role of sunlight in shaping fruit composition and cluster uniformity, we studied the spatial pattern of incoming irradiance, fruit temperature and metabolic profile within individual grape clusters under three levels of sunlight exposure. The experiment was conducted in a vineyard of Cabernet Sauvignon cv. located in the Negev Highlands, Israel, where excess SI and midday temperatures are known to degrade grape quality. Filtering SI lowered the surface temperature of exposed fruits and increased the uniformity of irradiance and temperature in the cluster zone. SI affected the overall levels and patterns of accumulation of sugars, organic acids, amino acids and phenylpropanoids, across the grape cluster. Increased exposure to sunlight was associated with lower accumulation levels of malate, aspartate, and maleate but with higher levels of valine, leucine, and serine, in addition to the stress-related proline and GABA. Flavan-3-ols metabolites showed a negative response to SI, whereas flavonols were highly induced. The overall levels of anthocyanins decreased with increased sunlight exposure; however, a hierarchical cluster analysis revealed that the members of this family were grouped into three distinct accumulation patterns, with malvidin anthocyanins and cyanidin-glucoside showing contrasting trends. The flavonol-glucosides, quercetin and kaempferol, exhibited a logarithmic response to SI, leading to improved cluster uniformity under high-light conditions. Comparing the within-cluster variability of metabolite accumulation highlighted the stability of sugars, flavan-3-ols, and cinnamic acid metabolites to SI, in contrast to the plasticity of flavonols. A correlation-based network analysis revealed that extended exposure to SI modified metabolic coordination, increasing the number of negative

  8. Evaluation of physicochemical properties, skin permeation and accumulation profiles of salicylic acid amide prodrugs as sunscreen agent.

    Science.gov (United States)

    Yan, Yi-Dong; Sung, Jun Ho; Lee, Dong Won; Kim, Jung Sun; Jeon, Eun-Mi; Kim, Dae-Duk; Kim, Dong Wuk; Kim, Jong Oh; Piao, Ming Guan; Li, Dong Xun; Yong, Chul Soon; Choi, Han Gon

    2011-10-31

    Various amide prodrugs of salicylic acid were synthesised, and their physicochemical properties including lipophilicity, chemical stability and enzymatic hydrolysis were investigated. In vivo skin permeation and accumulation profiles were also evaluated using a combination of common permeation enhancing techniques such as the use of a supersaturated solution of permeants in an enhancer vehicle, a lipophilic receptor solution, removal of the stratum corneum and delipidisation of skin. Their capacity factor values were proportional to the degree of carbon-carbon saturation in the side chain. All these amides were highly stable in acetonitrile and glycerine. Amide prodrugs were converted to salicylic acid both in hairless mouse liver and skin homogenates. N-dodecyl salicylamide (C12SM) showed the lowest permeation of salicylic acid in skin compared to the other prodrugs, probably due to its low aqueous solubility. It had a high affinity for the stratum corneum and its accumulation was restricted to only the uppermost layer of skin. Thus, this amide prodrug could be a safer topical sunscreen agent with minimum potential for systemic absorption.

  9. Tissue-specific, development-dependent phenolic compounds accumulation profile and gene expression pattern in tea plant [Camellia sinensis].

    Directory of Open Access Journals (Sweden)

    Xiaolan Jiang

    Full Text Available Phenolic compounds in tea plant [Camellia sinensis (L.] play a crucial role in dominating tea flavor and possess a number of key pharmacological benefits on human health. The present research aimed to study the profile of tissue-specific, development-dependent accumulation pattern of phenolic compounds in tea plant. A total of 50 phenolic compounds were identified qualitatively using liquid chromatography in tandem mass spectrometry technology. Of which 29 phenolic compounds were quantified based on their fragmentation behaviors. Most of the phenolic compounds were higher in the younger leaves than that in the stem and root, whereas the total amount of proanthocyanidins were unexpectedly higher in the root. The expression patterns of 63 structural and regulator genes involved in the shikimic acid, phenylpropanoid, and flavonoid pathways were analyzed by quantitative real-time polymerase chain reaction and cluster analysis. Based on the similarity of their expression patterns, the genes were classified into two main groups: C1 and C2; and the genes in group C1 had high relative expression level in the root or low in the bud and leaves. The expression patterns of genes in C2-2-1 and C2-2-2-1 groups were probably responsible for the development-dependent accumulation of phenolic compounds in the leaves. Enzymatic analysis suggested that the accumulation of catechins was influenced simultaneously by catabolism and anabolism. Further research is recommended to know the expression patterns of various genes and the reason for the variation in contents of different compounds in different growth stages and also in different organs.

  10. Tissue-specific, development-dependent phenolic compounds accumulation profile and gene expression pattern in tea plant [Camellia sinensis].

    Science.gov (United States)

    Jiang, Xiaolan; Liu, Yajun; Li, Weiwei; Zhao, Lei; Meng, Fei; Wang, Yunsheng; Tan, Huarong; Yang, Hua; Wei, Chaoling; Wan, Xiaochun; Gao, Liping; Xia, Tao

    2013-01-01

    Phenolic compounds in tea plant [Camellia sinensis (L.)] play a crucial role in dominating tea flavor and possess a number of key pharmacological benefits on human health. The present research aimed to study the profile of tissue-specific, development-dependent accumulation pattern of phenolic compounds in tea plant. A total of 50 phenolic compounds were identified qualitatively using liquid chromatography in tandem mass spectrometry technology. Of which 29 phenolic compounds were quantified based on their fragmentation behaviors. Most of the phenolic compounds were higher in the younger leaves than that in the stem and root, whereas the total amount of proanthocyanidins were unexpectedly higher in the root. The expression patterns of 63 structural and regulator genes involved in the shikimic acid, phenylpropanoid, and flavonoid pathways were analyzed by quantitative real-time polymerase chain reaction and cluster analysis. Based on the similarity of their expression patterns, the genes were classified into two main groups: C1 and C2; and the genes in group C1 had high relative expression level in the root or low in the bud and leaves. The expression patterns of genes in C2-2-1 and C2-2-2-1 groups were probably responsible for the development-dependent accumulation of phenolic compounds in the leaves. Enzymatic analysis suggested that the accumulation of catechins was influenced simultaneously by catabolism and anabolism. Further research is recommended to know the expression patterns of various genes and the reason for the variation in contents of different compounds in different growth stages and also in different organs.

  11. Carotenoid profiling in tubers of different potato (Solanum sp) cultivars: accumulation of carotenoids mediated by xanthophyll esterification.

    Science.gov (United States)

    Fernandez-Orozco, Rebeca; Gallardo-Guerrero, Lourdes; Hornero-Méndez, Dámaso

    2013-12-01

    The carotenoid profile of sixty potato cultivars (commercial, bred, old and native cultivars) has been characterised in order to provide information to be used in selective breeding programs directed to improve the nutritional value of this important staple food. Cultivars were segregated into three groups according to the major pigment in the carotenoid profile: violaxanthin (37 cultivars; especially those with higher carotenoid content), lutein (16 cultivars), and neoxanthin (7 cultivars). Other minor carotenoids were antheraxanthin, β-cryptoxanthin and β-carotene, while zeaxanthin was absent in all sample. The total carotenoid content ranged from 50.0 to 1552.0 μg/100 g dry wt, with an average value of about 435.3 μg/100 g dry wt. Sipancachi, Poluya and Chaucha native cultivars showed the highest carotenoid content (1020.0, 1478.2 and 1551.2 μg/100 g dry wt, respectively). Xanthophyll esters were present in most cultivars, mainly as diesterified forms, being observed a direct correlation between the carotenoid content and the esterified fraction, suggesting that the esterification process facilitates the accumulation of these lipophilic compounds within the plastids. Therefore, the presence of xanthophyll esters should be a phenotypic character to be included in the breeding studies, and more efforts should be dedicated to the understanding of the biochemical process leading to this structural modification of carotenoids in plants.

  12. The Malus domestica sugar transporter gene family: identifications based on genome and expression profiling related to the accumulation of fruit sugars

    OpenAIRE

    2014-01-01

    In plants, sugar transporters are involved not only in long-distance transport, but also in sugar accumulations in sink cells. To identify members of sugar transporter gene families and to analyze their function in fruit sugar accumulation, we conducted a phylogenetic analysis of the Malus domestica genome. Expression profiling was performed with shoot tips, mature leaves, and developed fruit of ‘Gala’ apple. Genes for sugar alcohol (including 17 sorbitol transporters), sucrose, and monosacch...

  13. 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.

  14. Differences in grain ultrastructure, phytochemical and proteomic profiles between the two contrasting grain Cd-accumulation barley genotypes.

    Directory of Open Access Journals (Sweden)

    Hongyan Sun

    Full Text Available To reveal grain physio-chemical and proteomic differences between two barley genotypes, Zhenong8 and W6nk2 of high- and low-grain-Cd-accumulation, grain profiles of ultrastructure, amino acid and proteins were compared. Results showed that W6nk2 possesses significantly lower protein content, with hordein depicting the greatest genotypic difference, compared with Zhenong8, and lower amino acid contents with especially lower proportion of Glu, Tyr, Phe and Pro. Both scanning and transmission electron microscopy observation declared that the size of A-type starch molecule in W6nk2 was considerably larger than that of Zhenong8. Grains of Zhenong8 exhibited more protein-rich deposits around starch granules, with some A-type granules having surface pits. Seventeen proteins were identified in grains, using 2-DE coupled with mass spectrometry, with higher expression in Zhenong8 than that in W6nk2; including z-type serpin, serpin-Z7 and alpha-amylase/trypsin inhibitor CM, carbohydrate metabolism, protein synthesis and signal transduction related proteins. Twelve proteins were less expressed in Zhenong8 than that in W6nk2; including barley trypsin inhibitor chloroform/methanol-soluble protein (BTI-CMe2.1, BTI-CMe2.2, trypsin inhibitor, dehydroascorbate reductase (DHAR, pericentrin, dynein heavy chain and some antiviral related proteins. The data extend our understanding of mechanisms underlying Cd accumulation/tolerance and provides possible utilization of elite genetic resources in developing low-grain-Cd barley cultivars.

  15. Exploration of polar lipid accumulation profiles in Euglena gracilis using LipidBlast, an MS/MS spectral library constructed in silico.

    Science.gov (United States)

    Ogawa, Takumi; Furuhashi, Takeshi; Okazawa, Atsushi; Nakai, Rai; Nakazawa, Masami; Kind, Tobias; Fiehn, Oliver; Kanaya, Shigehiko; Arita, Masanori; Ohta, Daisaku

    2014-01-01

    A rapid protocol for polar lipid profiling was applied to Euglena gracilis lipid metabolism by LipidBlast, an MS/MS spectral similarity search tool. The similarity search results suggested anoxia-induced polar lipid metabolism in Euglena characterized by the accumulation of differential lipid classes, carbon chain lengths, and unsaturated bond numbers. The informatics-supported MS spectral search provides an alternative option for global lipid profiling studies.

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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).

  3. Impact assessment of mercury accumulation and biochemical and molecular response of Mentha arvensis: a potential hyperaccumulator plant.

    Science.gov (United States)

    Manikandan, R; Sahi, S V; Venkatachalam, P

    2015-01-01

    The present study was focused on examining the effect of Hg oxidative stress induced physiochemical and genetic changes in M. arvensis seedlings. The growth rate of Hg treated seedlings was decreased to 56.1% and 41.5% in roots and shoots, respectively, compared to the control. Accumulation of Hg level in both roots and shoots was increased with increasing the concentration of Hg. Superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities were found to be increased with increasing the Hg concentration up to 20 mg/L; however, it was decreased at 25 mg/L Hg concentration. The POX enzyme activity was positively correlated with Hg dose. The changes occurring in the random amplification of ploymorphic DNA (RAPD) profiles generated from Hg treated seedlings included variations in band intensity, disappearance of bands, and appearance of new bands compared with the control seedlings. It was concluded that DNA polymorphisms observed with RAPD profile could be used as molecular marker for the evaluation of heavy metal induced genotoxic effects in plant species. The present results strongly suggested that Mentha arvensis could be used as a potential phytoremediator plant in mercury polluted environment.

  4. Impact Assessment of Mercury Accumulation and Biochemical and Molecular Response of Mentha arvensis: A Potential Hyperaccumulator Plant

    Directory of Open Access Journals (Sweden)

    R. Manikandan

    2015-01-01

    Full Text Available The present study was focused on examining the effect of Hg oxidative stress induced physiochemical and genetic changes in M. arvensis seedlings. The growth rate of Hg treated seedlings was decreased to 56.1% and 41.5% in roots and shoots, respectively, compared to the control. Accumulation of Hg level in both roots and shoots was increased with increasing the concentration of Hg. Superoxide dismutase (SOD, catalase (CAT, and ascorbate peroxidase (APX activities were found to be increased with increasing the Hg concentration up to 20 mg/L; however, it was decreased at 25 mg/L Hg concentration. The POX enzyme activity was positively correlated with Hg dose. The changes occurring in the random amplification of ploymorphic DNA (RAPD profiles generated from Hg treated seedlings included variations in band intensity, disappearance of bands, and appearance of new bands compared with the control seedlings. It was concluded that DNA polymorphisms observed with RAPD profile could be used as molecular marker for the evaluation of heavy metal induced genotoxic effects in plant species. The present results strongly suggested that Mentha arvensis could be used as a potential phytoremediator plant in mercury polluted environment.

  5. 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.

  6. Genome-wide RNA polymerase II profiles and RNA accumulation reveal kinetics of transcription and associated epigenetic changes during diurnal cycles.

    Directory of Open Access Journals (Sweden)

    Gwendal Le Martelot

    Full Text Available Interactions of cell-autonomous circadian oscillators with diurnal cycles govern the temporal compartmentalization of cell physiology in mammals. To understand the transcriptional and epigenetic basis of diurnal rhythms in mouse liver genome-wide, we generated temporal DNA occupancy profiles by RNA polymerase II (Pol II as well as profiles of the histone modifications H3K4me3 and H3K36me3. We used these data to quantify the relationships of phases and amplitudes between different marks. We found that rhythmic Pol II recruitment at promoters rather than rhythmic transition from paused to productive elongation underlies diurnal gene transcription, a conclusion further supported by modeling. Moreover, Pol II occupancy preceded mRNA accumulation by 3 hours, consistent with mRNA half-lives. Both methylation marks showed that the epigenetic landscape is highly dynamic and globally remodeled during the 24-hour cycle. While promoters of transcribed genes had tri-methylated H3K4 even at their trough activity times, tri-methylation levels reached their peak, on average, 1 hour after Pol II. Meanwhile, rhythms in tri-methylation of H3K36 lagged transcription by 3 hours. Finally, modeling profiles of Pol II occupancy and mRNA accumulation identified three classes of genes: one showing rhythmicity both in transcriptional and mRNA accumulation, a second class with rhythmic transcription but flat mRNA levels, and a third with constant transcription but rhythmic mRNAs. The latter class emphasizes widespread temporally gated posttranscriptional regulation in the mouse liver.

  7. Expression Profiling Coupled with In-silico Mapping Identifies Candidate Genes for Reducing Aflatoxin Accumulation in Maize

    Science.gov (United States)

    Dhakal, Ramesh; Chai, Chenglin; Karan, Ratna; Windham, Gary L.; Williams, William P.; Subudhi, Prasanta K.

    2017-01-01

    Aflatoxin, produced by Aspergillus flavus, is hazardous to health of humans and livestock. The lack of information about large effect QTL for resistance to aflatoxin accumulation is a major obstacle to employ marker-assisted selection for maize improvement. The understanding of resistance mechanisms of the host plant and the associated genes is necessary for improving resistance to A. flavus infection. A suppression subtraction hybridization (SSH) cDNA library was made using the developing kernels of Mp715 (resistant inbred) and B73 (susceptible inbred) and 480 randomly selected cDNA clones were sequenced to identify differentially expressed genes (DEGs) in response to A. flavus infection and map these clones onto the corn genome by in-silico mapping. A total of 267 unigenes were identified and majority of genes were related to metabolism, stress response, and disease resistance. Based on the reverse northern hybridization experiment, 26 DEGs were selected for semi-quantitative RT-PCR analysis in seven inbreds with variable resistance to aflatoxin accumulation at two time points after A. flavus inoculation. Most of these genes were highly expressed in resistant inbreds. Quantitative RT-PCR analysis validated upregulation of PR-4, DEAD-box RNA helicase, and leucine rich repeat family protein in resistant inbreds. Fifty-six unigenes, which were placed on linkage map through in-silico mapping, overlapped the QTL regions for resistance to aflatoxin accumulation identified in a mapping population derived from the cross between B73 and Mp715. Since majority of these mapped genes were related to disease resistance, stress response, and metabolism, these should be ideal candidates to investigate host pathogen interaction and to reduce aflatoxin accumulation in maize. PMID:28428796

  8. 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.

  9. 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.

  10. 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.

  11. Comparative transcripts profiling reveals new insight into molecular processes regulating lycopene accumulation in a sweet orange (Citrus sinensis red-flesh mutant

    Directory of Open Access Journals (Sweden)

    Zhang Jianchen

    2009-11-01

    Full Text Available Abstract Background Interest in lycopene metabolism and regulation is growing rapidly because accumulative studies have suggested an important role for lycopene in human health promotion. However, little is known about the molecular processes regulating lycopene accumulation in fruits other than tomato so far. Results On a spontaneous sweet orange bud mutant with abnormal lycopene accumulation in fruits and its wild type, comparative transcripts profiling was performed using Massively Parallel Signature Sequencing (MPSS. A total of 6,877,027 and 6,275,309 reliable signatures were obtained for the wild type (WT and the mutant (MT, respectively. Interpretation of the MPSS signatures revealed that the total number of transcribed gene in MT is 18,106, larger than that in WT 17,670, suggesting that newly initiated transcription occurs in the MT. Further comparison of the transcripts abundance between MT and WT revealed that 3,738 genes show more than two fold expression difference, and 582 genes are up- or down-regulated at 0.05% significance level by more than three fold difference. Functional assignments of the differentially expressed genes indicated that 26 reliable metabolic pathways are altered in the mutant; the most noticeable ones are carotenoid biosynthesis, photosynthesis, and citrate cycle. These data suggest that enhanced photosynthesis and partial impairment of lycopene downstream flux are critical for the formation of lycopene accumulation trait in the mutant. Conclusion This study provided a global picture of the gene expression changes in a sweet orange red-flesh mutant as compared to the wild type. Interpretation of the differentially expressed genes revealed new insight into the molecular processes regulating lycopene accumulation in the sweet orange red-flesh mutant.

  12. 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.

  13. Expression profile of genes coding for carotenoid biosynthetic pathway during ripening and their association with accumulation of lycopene in tomato fruits.

    Science.gov (United States)

    Smita, Shuchi; Rajwanshi, Ravi; Lenka, Sangram Keshari; Katiyar, Amit; Chinnusamy, Viswanathan; Bansal, Kailash Chander

    2013-12-01

    Fruit ripening process is associated with change in carotenoid profile and accumulation of lycopene in tomato (Solanum lycopersicum L.). In this study, we quantified the beta-carotene and lycopene content at green, breaker and red-ripe stages of fruit ripening in eight tomato genotypes by using high-performance liquid chromatography. Among the genotypes, lycopene content was found highest in Pusa Rohini and lowest in VRT-32-1. To gain further insight into the regulation of lycopene biosynthesis and accumulation during fruit ripening, expression analysis of nine carotenoid pathway-related genes was carried out in the fruits of high lycopene genotype-Pusa Rohini. We found that expression of phytoene synthase and beta-carotene hydroxylase-1 was four and thirty-fold higher, respectively, at breaker stage as compared to red-ripe stage of fruit ripening. Changes in the expression level of these genes were associated with a 40% increase in lycopene content at red-ripe stage as compared with breaker stage. Thus, the results from our study suggest the role of specific carotenoid pathway-related genes in accumulation of high lycopene during the fruit ripening processes.

  14. Expression profile of genes coding for carotenoid biosynthetic pathway during ripening and their association with accumulation of lycopene in tomato fruits

    Indian Academy of Sciences (India)

    Shuchi Smita; Ravi Rajwanshi; Sangram Keshari Lenka; Amit Katiyar; Viswanathan Chinnusamy; Kailash Chander Bansal

    2013-12-01

    Fruit ripening process is associated with change in carotenoid profile and accumulation of lycopene in tomato (Solanum lycopersicum L.). In this study, we quantified the -carotene and lycopene content at green, breaker and red-ripe stages of fruit ripening in eight tomato genotypes by using high-performance liquid chromatography. Among the genotypes, lycopene content was found highest in Pusa Rohini and lowest in VRT-32-1. To gain further insight into the regulation of lycopene biosynthesis and accumulation during fruit ripening, expression analysis of nine carotenoid pathway-related genes was carried out in the fruits of high lycopene genotype—Pusa Rohini. We found that expression of phytoene synthase and -carotene hydroxylase-1 was four and thirty-fold higher, respectively, at breaker stage as compared to red-ripe stage of fruit ripening. Changes in the expression level of these genes were associated with a 40% increase in lycopene content at red-ripe stage as compared with breaker stage. Thus, the results from our study suggest the role of specific carotenoid pathway-related genes in accumulation of high lycopene during the fruit ripening processes.

  15. The Malus domestica sugar transporter gene family: identifications based on genome and expression profiling related to the accumulation of fruit sugars

    Directory of Open Access Journals (Sweden)

    Xiaoyu eWei

    2014-11-01

    Full Text Available In plants, sugar transporters are involved not only in long-distance transport, but also in sugar accumulations in sink cells. To identify members of sugar transporter gene families and to analyze their function in fruit sugar accumulation, we conducted a phylogenetic analysis of the Malus domestica genome. Expression profiling was performed with shoot tips, mature leaves, and developed fruit of ‘Gala’ apple. Genes for sugar alcohol (including 17 sorbitol transporters, sucrose, and monosaccharide transporters, plus SWEET genes, were selected as candidates in 31, 9, 50, and 27 loci, respectively, of the genome. The monosaccharide transporter family appears to include five subfamilies (30 MdHTs, 8 MdEDR6s, 5 MdTMTs, 3 MdvGTs, and 4 MdpGLTs. Phylogenetic analysis of the protein sequences indicated that orthologs exist among Malus, Vitis, and Arabidopsis. Investigations of transcripts revealed that 68 candidate transporters are expressed in apple, albeit to different extents. Here, we discuss their possible roles based on the relationship between their levels of expression and sugar concentrations. The high accumulation of fructose in apple fruit is possibly linked to the coordination and cooperation between MdTMT1/2 and MdEDR6. By contrast, these fruits show low MdSWEET4.1 expression and a high flux of fructose produced from sorbitol. Our study provides an exhaustive survey of sugar transporter genes and demonstrates that sugar transporter gene families in M. domestica are comparable to those in other species. Expression profiling of these transporters will likely contribute to improving our understanding of their physiological functions in fruit formation and the development of sweetness properties.

  16. The Malus domestica sugar transporter gene family: identifications based on genome and expression profiling related to the accumulation of fruit sugars.

    Science.gov (United States)

    Wei, Xiaoyu; Liu, Fengli; Chen, Cheng; Ma, Fengwang; Li, Mingjun

    2014-01-01

    In plants, sugar transporters are involved not only in long-distance transport, but also in sugar accumulations in sink cells. To identify members of sugar transporter gene families and to analyze their function in fruit sugar accumulation, we conducted a phylogenetic analysis of the Malus domestica genome. Expression profiling was performed with shoot tips, mature leaves, and developed fruit of "Gala" apple. Genes for sugar alcohol [including 17 sorbitol transporters (SOTs)], sucrose, and monosaccharide transporters, plus SWEET genes, were selected as candidates in 31, 9, 50, and 27 loci, respectively, of the genome. The monosaccharide transporter family appears to include five subfamilies (30 MdHTs, 8 MdEDR6s, 5 MdTMTs, 3 MdvGTs, and 4 MdpGLTs). Phylogenetic analysis of the protein sequences indicated that orthologs exist among Malus, Vitis, and Arabidopsis. Investigations of transcripts revealed that 68 candidate transporters are expressed in apple, albeit to different extents. Here, we discuss their possible roles based on the relationship between their levels of expression and sugar concentrations. The high accumulation of fructose in apple fruit is possibly linked to the coordination and cooperation between MdTMT1/2 and MdEDR6. By contrast, these fruits show low MdSWEET4.1 expression and a high flux of fructose produced from sorbitol. Our study provides an exhaustive survey of sugar transporter genes and demonstrates that sugar transporter gene families in M. domestica are comparable to those in other species. Expression profiling of these transporters will likely contribute to improving our understanding of their physiological functions in fruit formation and the development of sweetness properties.

  17. Whole genome HBV deletion profiles and the accumulation of preS deletion mutant during antiviral treatment

    Directory of Open Access Journals (Sweden)

    Zhang Dake

    2012-12-01

    Full Text Available Abstract Background Hepatitis B virus (HBV, because of its error-prone viral polymerase, has a high mutation rate leading to widespread substitutions, deletions, and insertions in the HBV genome. Deletions may significantly change viral biological features complicating the progression of liver diseases. However, the clinical conditions correlating to the accumulation of deleted mutants remain unclear. In this study, we explored HBV deletion patterns and their association with disease status and antiviral treatment by performing whole genome sequencing on samples from 51 hepatitis B patients and by monitoring changes in deletion variants during treatment. Clone sequencing was used to analyze preS regions in another cohort of 52 patients. Results Among the core, preS, and basic core promoter (BCP deletion hotspots, we identified preS to have the highest frequency and the most complex deletion pattern using whole genome sequencing. Further clone sequencing analysis on preS identified 70 deletions which were classified into 4 types, the most common being preS2. Also, in contrast to the core and BCP regions, most preS deletions were in-frame. Most deletions interrupted viral surface epitopes, and are possibly involved in evading immuno-surveillance. Among various clinical factors examined, logistic regression showed that antiviral medication affected the accumulation of deletion mutants (OR = 6.81, 95% CI = 1.296 ~ 35.817, P = 0.023. In chronic carriers of the virus, and individuals with chronic hepatitis, the deletion rate was significantly higher in the antiviral treatment group (Fisher exact test, P = 0.007. Particularly, preS2 deletions were associated with the usage of nucleos(tide analog therapy (Fisher exact test, P = 0.023. Dynamic increases in preS1 or preS2 deletions were also observed in quasispecies from samples taken from patients before and after three months of ADV therapy. In vitro experiments demonstrated that

  18. 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.

  19. Graphene oxide induces plasma membrane damage, reactive oxygen species accumulation and fatty acid profiles change in Pichia pastoris.

    Science.gov (United States)

    Zhang, Meng; Yu, Qilin; Liang, Chen; Liu, Zhe; Zhang, Biao; Li, Mingchun

    2016-10-01

    During the past couple of years, graphene nanomaterials were extremely popular among the scientists due to the promising properties in many aspects. Before the materials being well applied, we should first focus on their biosafety and toxicity. In this study, we investigated the toxicity of synthesized graphene oxide (GO) against the model industrial organism Pichia pastoris. We found that the synthesized GO showed dose-dependent toxicity to P. pastoris, through cell membrane damage and intracellular reactive oxygen species (ROS) accumulation. In response to these cell stresses, cells had normal unsaturated fatty acid (UFA) levels but increased contents of polyunsaturated fatty acid (PUFA) with up-regulation of UFA synthesis-related genes on the transcriptional level, which made it overcome the stress under GO attack. Two UFA defective strains (spt23Δ and fad12Δ) were used to demonstrate the results above. Hence, this study suggested a close connection between PUFAs and cell survival against GO.

  20. Improved stratigraphic dating at a low accumulation Alpine ice core through laser ablation trace element profiling at sub-mm depth resolution

    Science.gov (United States)

    Bohleber, Pascal; Spaulding, Nicole; Mayewski, Paul; Sneed, Sharon; Handley, Mike; Erhardt, Tobias; Wagenbach, Dietmar

    2015-04-01

    The small scale Colle Gnifetti glacier saddle (4450 m asl, Monte Rosa region) is the only ice core drilling site in the European Alps with a net accumulation low enough to offer multi-millennia climate records. However, a robust interpretation of such long term records (i.e. mineral dust, stable water isotopes) at the Colle Gnifetti (CG) multi core array is strongly challenged by depositional noise associated with a highly irregular annual layer stratigraphy. In combination with a relatively large vertical strain rate and rapid layer thinning, annual layer counting gets increasingly ambiguous as of approximately 100 years. In addition, this prevents clear attribution of likely volcanic horizons to historical eruption dates. To improve stratigraphic dating under such intricate conditions, we deployed laser ablation (LA) ICP-MS at sub-mm sample resolution. We present here the first LA impurity profiles from a new Colle Gnifetti ice core drilled 73 m to bedrock in 2013 at a site where the net snow accumulation is around 20 cm w.e. per year. We contrast the LA signal variability (including Ca, Fe, Na) to continuous flow analyses (CFA) records at cm-resolution (Ca, Na, melt water conductivity, micro- particle) recorded over the whole core length. Of special concern are the lower 28 m to bedrock, which have been continuously profiled in LA Ca, thus offering the direct comparison of Ca-signals between CFA and LA. By this means, we first validate at upper depths LA based annual layer identification through agreement with CFA based counting efforts before demonstrating the LA based counting still works at depths where CFA derived annual layers become spurious since embedded in strong, multi-year cycles. Finally, LA ice core profiling of our CG core has potential for not only dating improvement but also reveals benefits in resolving highly thinned basal ice sections including accounting for micro-structural features such as grain boundaries.

  1. 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.

  2. Oxygen accumulation on metal surfaces investigated by XPS, AES and LEIS, an issue for sputter depth profiling under UHV conditions

    Science.gov (United States)

    Steinberger, R.; Celedón, C. E.; Bruckner, B.; Roth, D.; Duchoslav, J.; Arndt, M.; Kürnsteiner, P.; Steck, T.; Faderl, J.; Riener, C. K.; Angeli, G.; Bauer, P.; Stifter, D.

    2017-07-01

    Depth profiling using surface sensitive analysis methods in combination with sputter ion etching is a common procedure for thorough material investigations, where clean surfaces free of any contamination are essential. Hence, surface analytic studies are mostly performed under ultra-high vacuum (UHV) conditions, but the cleanness of such UHV environments is usually overrated. Consequently, the current study highlights the in principle known impact of the residual gas on metal surfaces (Fe, Mg, Al, Cr and Zn) for various surface analytics methods, like X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and low-energy ion scattering (LEIS). The investigations with modern, state-of-the-art equipment showed different behaviors for the metal surfaces in UHV during acquisition: (i) no impact for Zn, even after long time, (ii) solely adsorption of oxygen for Fe, slight and slow changes for Cr and (iii) adsorption accompanied by oxide formation for Al and Mg. The efficiency of different counter measures was tested and the acquired knowledge was finally used for ZnMgAl coated steel to obtain accurate depth profiles, which exhibited before serious artifacts when data acquisition was performed in an inconsiderate way.

  3. Evaluation of Penicillium expansum for growth, patulin accumulation, nonvolatile compounds and volatile profile in kiwi juices of different cultivars.

    Science.gov (United States)

    Wang, Yuan; Shan, Tingting; Yuan, Yahong; Zhang, Zhiwei; Guo, Chunfeng; Yue, Tianli

    2017-08-01

    Patulin (PAT) contamination and changes of nonvolatile and volatile compounds caused by Penicillium expansum in fresh juices of 8 kiwi cultivars were investigated. Growth and PAT production of P. expansum were greater at 25°C than at 4°C. P. expansum grew in kiwi juices under pH ranging from 2.75 to 3.27 and produced 45.10-268.88μg/mL of PAT at 25°C. Decreases occurred in malic acid and soluble protein; while consumption and production simultaneously happened for reducing sugar, total soluble solid, titratable acid, citric acid, ascorbic acid and total phenolics. A large number of volatile organic compounds (VOCs) were produced during infection and each cultivar presented a distinct profile. Most of the alcohols, acids, ketones and phenols increased while aldehydes decreased. VOCs that were specific to infected kiwi juices are potential biomarkers for GC-MS analysis of kiwifruit infected by P. expansum.

  4. 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

  5. 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)

  6. 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.

  7. 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...

  8. 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.

  9. MicroRNA profiling analysis throughout tomato fruit development and ripening reveals potential regulatory role of RIN on microRNAs accumulation.

    Science.gov (United States)

    Gao, Chao; Ju, Zheng; Cao, Dongyan; Zhai, Baiqiang; Qin, Guozheng; Zhu, Hongliang; Fu, Daqi; Luo, Yunbo; Zhu, Benzhong

    2015-04-01

    The development and ripening of tomato fruit are complex processes involving many gene regulatory pathways at the transcriptional and post-transcriptional level. Ripening inhibitor (RIN) is a vital transcription factor, which targets numerous ripening-related genes at the transcriptional level during tomato fruit ripening. MicroRNAs (miRNAs) are a class of short noncoding RNAs that play important roles in post-transcriptional gene regulation. To elucidate the potential regulatory relationship between rin and miRNAs during fruit development and ripening, we identified known miRNAs and profiled their expression in wild-type tomato and rin mutant using a deep sequencing approach combined with quantitative RT-PCR. A total of 33 known miRNA families were identified, of which 14 miRNA families were differently accumulated. Subsequent promoter analysis showed that possible RIN-binding motifs (CArG-box) tended to occur frequently in the promoter regions of partial differently expressed miRNAs. In addition, ethylene may participate in the regulation of miRNAs accumulation during tomato fruit ripening. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay confirmed the direct binding of RIN to the promoter of MIR172a. Collectively, these results showed a close correlation between miRNA expression and RIN as well as ethylene, which further elucidated the regulatory roles of miRNAs during fruit development and ripening and enriched the regulatory network of RIN in tomato fruit.

  10. Prion Strain Differences in Accumulation of PrPSc on Neurons and Glia Are Associated with Similar Expression Profiles of Neuroinflammatory Genes: Comparison of Three Prion Strains.

    Directory of Open Access Journals (Sweden)

    James A Carroll

    2016-04-01

    Full Text Available Misfolding and aggregation of host proteins are important features of the pathogenesis of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, frontotemporal dementia and prion diseases. In all these diseases, the misfolded protein increases in amount by a mechanism involving seeded polymerization. In prion diseases, host prion protein is misfolded to form a pathogenic protease-resistant form, PrPSc, which accumulates in neurons, astroglia and microglia in the CNS. Here using dual-staining immunohistochemistry, we compared the cell specificity of PrPSc accumulation at early preclinical times post-infection using three mouse scrapie strains that differ in brain regional pathology. PrPSc from each strain had a different pattern of cell specificity. Strain 22L was mainly associated with astroglia, whereas strain ME7 was mainly associated with neurons and neuropil. In thalamus and cortex, strain RML was similar to 22L, but in substantia nigra, RML was similar to ME7. Expression of 90 genes involved in neuroinflammation was studied quantitatively using mRNA from thalamus at preclinical times. Surprisingly, despite the cellular differences in PrPSc accumulation, the pattern of upregulated genes was similar for all three strains, and the small differences observed correlated with variations in the early disease tempo. Gene upregulation correlated with activation of both astroglia and microglia detected in early disease prior to vacuolar pathology or clinical signs. Interestingly, the profile of upregulated genes in scrapie differed markedly from that seen in two acute viral CNS diseases (LaCrosse virus and BE polytropic Friend retrovirus that had reactive gliosis at levels similar to our prion-infected mice.

  11. Dynamics of pedogenic carbonate accumulation in soils under different land use as an impulse to simulation study of water flows in their profiles

    Science.gov (United States)

    Khokhlova, Olga; Arkhangelskaya, Tatiana

    2016-04-01

    Little is known about changes in pedogenic carbonate accumulation under different land use in forest-steppe ecosystems. This work was conducted to investigate the dynamics of pedogenic carbonate accumulation in cultivated Gray-Forest soils (Luvisols). These soils together with the Chernozems belong to typical soils for the forest-steppe area of the Central Russian Upland. The studied soils were formed on calcareous loess-like loam parent material in well-drained position with groundwater level at 8-10 m depth. Soils were sampled at four sites: a broadleaf forest and an adjacent 50-year continuously cropped field under corn monoculture (first plot), bare fallow (second plot) and crop rotation which includes clean fallow every fourth year (third plot) at the Experimental Station of the Voronezh Institute of Corn in the Voronezh oblast of Russia. All plowed soils are now classified as arable Chernozems (Mollisols). The carbonate status of four soils was studied using hierarchical morphological observation (macro-, meso-, micro- and sub-micro levels) and radiocarbon dating of carbonate pedofeatures. Then, the simulation of soil hydrology for two plots, under corn monoculture and bare fallow, was performed for the vegetation period. Significant differences in the down-profile carbonates distribution were apparent between pairs of soil pits: under monoculture of corn and forest on the one hand, and under bare fallow and crop rotation on the other. In pits under bare fallow and crop rotation, the depth of carbonate occurrence was about 60-80 cm higher than in the profiles under forest and corn. In addition significant differences were observed in micro- and submicrostructure of carbonate pedofeatures in these two pairs of soils. 14C-date of carbonate soft masses (cutans) from 80-90 cm in the soil under bare fallow was 10650±170 yr BP whereas practically the same date, 11100±100 yr BP, was obtained in the soil under corn from 140-160 cm. Presumably, this difference in

  12. 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.

  13. Combined transcriptome and metabolite profiling reveals that IiPLR1 plays an important role in lariciresinol accumulation in Isatis indigotica.

    Science.gov (United States)

    Xiao, Ying; Ji, Qian; Gao, Shouhong; Tan, Hexin; Chen, Ruibing; Li, Qing; Chen, Junfeng; Yang, Yingbo; Zhang, Lei; Wang, Zhengtao; Chen, Wansheng; Hu, Zhibi

    2015-10-01

    A lignan, lariciresinol, is an important efficacious compound for the antiviral effect of Isatis indigotica, a widely used herb for the treatment of colds, fever, and influenza. Although some rate-limiting steps of the lariciresinol biosynthetic pathway are well known, the specific roles of gene family members in I. indigotica in regulating lariciresinol production are poorly understood. In the present study, a correlation analysis between the RNA sequencing (RNA-Seq) expression profile and lignan content by using I. indigotica hairy roots treated with methyl jamonate (0.5 μM) at different time points as a source implicated that I. indigotica pinoresinol/lariciresinol reductase 1 (IiPLR1), but not IiPLR2 or IiPLR3, contributed greatly to lariciresinol accumulation. Gene silencing by RNA interference (RNAi) demonstrated that IiPLR1 indeed influenced lariciresinol biosynthesis, whereas suppression of IiPLR2 or IiPLR3 did not change lariciresinol abundance significantly. IiPLR1 was thus further characterized; IiPLR1 was constitutively expressed in roots, stems, leaves, and flowers of I. indigotica, with the highest expression in roots, and it responds to different stress treatments to various degrees. Recombinant IiPLR1 reduces both (±)-pinoresinol and (±)-lariciresinol efficiently, with comparative K cat/K m values. Furthermore, overexpression of IiPLR1 significantly enhanced lariciresinol accumulation in I. indigotica hairy roots, and the best line (ovx-2) produced 353.9 μg g(-1) lariciresinol, which was ~6.3-fold more than the wild type. This study sheds light on how to increase desired metabolites effectively by more accurate or appropriate genetic engineering strategies, and also provides an effective approach for the large-scale commercial production of pharmaceutically valuable lariciresinol by using hairy root culture systems as bioreactors.

  14. Transcriptome Profiling Identifies Candidate Genes Associated with the Accumulation of Distinct Sulfur γ-Glutamyl Dipeptides in Phaseolus vulgaris and Vigna mungo Seeds.

    Science.gov (United States)

    Liao, Dengqun; Cram, Dustin; Sharpe, Andrew G; Marsolais, Frédéric

    2013-01-01

    Common bean (Phaseolus vulgaris) and black gram (Vigna mungo) accumulate γ-Glutamyl-S-methylcysteine and γ-Glutamyl-methionine in seed, respectively. Transcripts were profiled by 454 pyrosequencing data at a similar developmental stage coinciding with the beginning of the accumulation of these metabolites. Expressed sequence tags were assembled into Unigenes, which were assigned to specific genes in the early release chromosomal assembly of the P. vulgaris genome. Genes involved in multiple sulfur metabolic processes were expressed in both species. Expression of Sultr3 members was predominant in P. vulgaris, whereas expression of Sultr5 members predominated in V. mungo. Expression of the cytosolic SERAT1;1 and -1;2 was approximately fourfold higher in P. vulgaris while expression of the plastidic SERAT2;1 was twofold higher in V. mungo. Among BSAS family members, BSAS4;1, encoding a cytosolic cysteine desulfhydrase, and BSAS1;1, encoding a cytosolic O-acetylserine sulphydrylase were most highly expressed in both species. This was followed by BSAS3;1 encoding a plastidic β-cyanoalanine synthase which was more highly expressed by 10-fold in P. vulgaris. The data identify BSAS3;1 as a candidate enzyme for the biosynthesis of S-methylcysteine through the use of methanethiol as substrate instead of cyanide. Expression of GLC1 would provide a complete sequence leading to the biosynthesis of γ-Glutamyl-S-methylcysteine in plastids. The detection of S-methylhomoglutathione in P. vulgaris suggested that homoglutathione synthetase may accept, to some extent, γ-Glutamyl-S-methylcysteine as substrate, which might lead to the formation of S-methylated phytochelatins. In conclusion, 454 sequencing was effective at revealing differences in the expression of sulfur metabolic genes, providing information on candidate genes for the biosynthesis of distinct sulfur amino acid γ-Glutamyl dipeptides between P. vulgaris and V. mungo.

  15. Transcriptome profiling identifies candidate genes associated with the accumulation of distinct γ-glutamyl sulphur dipeptides in Phaseolus vulgaris and Vigna mungo seeds

    Directory of Open Access Journals (Sweden)

    Dengqun eLiao

    2013-03-01

    Full Text Available Common bean (Phaseolus vulgaris and black gram (Vigna mungo accumulate γ-glutamyl-S-methylcysteine and γ-glutamyl-methionine in seed, respectively. Transcripts were profiled by 454 pyrosequencing at a similar developmental stage coinciding with the beginning of the accumulation of these metabolites. Expressed sequence tags were assembled into Unigenes, which were assigned to specific genes in the early release chromosomal assembly of the P. vulgaris genome. Genes involved in multiple sulphur metabolic processes were expressed in both species. Expression of Sultr3 members was predominant in P. vulgaris, whereas expression of Sultr5 members predominated in V. mungo. Expression of the cytosolic SERAT1;1 and -1;2 was approximately four-fold higher in P. vulgaris while expression of the plastidic SERAT2;1 was two-fold higher in V. mungo. Among BSAS family members, BSAS4;1, encoding a cytosolic cysteine desulphydrase, and BSAS1;1, encoding a cytosolic O-acetylserine sulphydrylase were most highly expressed in both species. This was followed by BSAS3;1 encoding a plastidic β-cyanoalanine synthase which was more highly expressed by 10-fold in P. vulgaris. The data identify BSAS3;1 as a candidate enzyme for the biosynthesis of S-methyl-cysteine through the use of methanethiol as substrate instead of cyanide. Expression of GLC1 would provide a complete sequence leading to the biosynthesis of γ-glutamyl-S-methylcysteine in plastids. The detection of S-methylhomoglutathione in P. vulgaris suggested that homoglutathione synthetase may accept, to some extent, γ-glutamyl-S-methylcysteine as substrate, which might lead to the formation of S-methylated phytochelatins. In conclusion, 454 sequencing was effective at revealing differences in the expression of sulphur metabolic genes, providing information on candidate genes for the biosynthesis of distinct sulphur amino acid γ-glutamyl dipeptides between P. vulgaris and V. mungo.

  16. 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.

  17. 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.

  18. Single-kernel ionomic profiles are highly heritable indicators of genetic and environmental influences on elemental accumulation in maize grain (Zea mays.

    Directory of Open Access Journals (Sweden)

    Ivan R Baxter

    Full Text Available The ionome, or elemental profile, of a maize kernel can be viewed in at least two distinct ways. First, the collection of elements within the kernel are food and feed for people and animals. Second, the ionome of the kernel represents a developmental end point that can summarize the life history of a plant, combining genetic programs and environmental interactions. We assert that single-kernel-based phenotyping of the ionome is an effective method of analysis, as it represents a reasonable compromise between precision, efficiency, and power. Here, we evaluate potential pitfalls of this sampling strategy using several field-grown maize sample sets. We demonstrate that there is enough genetically determined diversity in accumulation of many of the elements assayed to overcome potential artifacts. Further, we demonstrate that environmental signals are detectable through their influence on the kernel ionome. We conclude that using single kernels as the sampling unit is a valid approach for understanding genetic and environmental effects on the maize kernel ionome.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Distribution and accumulation of mercury and copper in mangrove sediments in Shenzhen, the world's most rapid urbanized city.

    Science.gov (United States)

    Li, Ruili; Xu, Hualin; Chai, Minwei; Qiu, Guo Yu

    2016-02-01

    To investigate the influence of mangrove forest on heavy metal accumulation and storage in intertidal sediments, core sediments from natural mangrove, restored mangrove, and adjacent mud flat spanning the intertidal zone along the south coastline of the most heavily urbanized Deep bay, Guangdong province, China were analyzed. The average concentrations of mercury (Hg) in surface sediments of natural mangrove and restored mangrove were 172 and 151 ng g(-1), whereas those of copper (Cu) were 75 and 50 μg g(-1), respectively. Compared to those from other typical mangrove wetlands of the world, the metal levels in Shenzhen were at median to high levels, which is consistent with the fact that Shenzhen is in high exploitation and its mangrove suffer intensive impact from human activities. Hg and Cu concentration profiles indicated a higher metal accumulation in surface layers of sediments, in agreement with enrichment of organic matter contents. Maximum concentration, enrichment factors, and excess (background-deducted) concentration inventories of metals (Hg and Cu) were substantially different between environments, decreasing from natural mangrove sediments to restored mangrove sediments to mud flat. Furthermore, metal inputs to Futian mangrove decreased in the order natural mangrove > restored mangrove > mud flat, indicating that mangrove facilitated the accumulation and storage of Hg and Cu in sediment layers.

  6. Expression profiles of genes related to carbohydrate metabolism provide new insights into carbohydrate accumulation in seeds and seedlings of Ricinus communis in response to temperature

    NARCIS (Netherlands)

    Ribeiro de Jesus, P.R.; Ligterink, W.; Hilhorst, H.W.M.

    2015-01-01

    Ricinus communis possesses a specific metabolic signature to adjust growth and developmental processes in response to temperature: carbohydrates are accumulated at low temperatures, whereas amino acids are accumulated at elevated temperatures. Our objective was to assess tissue-specific changes in

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Ocean currents measured by Shipboard Acoustic Doppler Current Profilers (SADCP) from global oceans accumulated at Joint Archive for SADCP from 2004 to 2013 (NODC Accession 0123302)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Absolute U- and V-component ocean current vectors from Shipboard Acoustic Doppler Current Profilers (SADCP), as both a high-frequency sampling (nominally 5 minutes...

  14. 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

  15. Proteomics Profiling Reveals Carbohydrate Metabolic Enzymes and 14-3-3 Proteins Play Important Roles for Starch Accumulation during Cassava Root Tuberization.

    Science.gov (United States)

    Wang, Xuchu; Chang, Lili; Tong, Zheng; Wang, Dongyang; Yin, Qi; Wang, Dan; Jin, Xiang; Yang, Qian; Wang, Liming; Sun, Yong; Huang, Qixing; Guo, Anping; Peng, Ming

    2016-01-01

    Cassava is one of the most important root crops as a reliable source of food and carbohydrates. Carbohydrate metabolism and starch accumulation in cassava storage root is a cascade process that includes large amounts of proteins and cofactors. Here, comparative proteomics were conducted in cassava root at nine developmental stages. A total of 154 identified proteins were found to be differentially expressed during starch accumulation and root tuberization. Many enzymes involved in starch and sucrose metabolism were significantly up-regulated, and functional classification of the differentially expressed proteins demonstrated that the majority were binding-related enzymes. Many proteins were took part in carbohydrate metabolism to produce energy. Among them, three 14-3-3 isoforms were induced to be clearly phosphorylated during storage root enlargement. Overexpression of a cassava 14-3-3 gene in Arabidopsis thaliana confirmed that the older leaves of these transgenic plants contained higher sugar and starch contents than the wild-type leaves. The 14-3-3 proteins and their binding enzymes may play important roles in carbohydrate metabolism and starch accumulation during cassava root tuberization. These results not only deepened our understanding of the tuberous root proteome, but also uncovered new insights into carbohydrate metabolism and starch accumulation during cassava root enlargement.

  16. Effect of green and red light in lipid accumulation and transcriptional profile of genes implicated in lipid biosynthesis in Chlamydomonas reinhardtii.

    Science.gov (United States)

    Gaytán-Luna, Daniel Eugenio; Ochoa-Alfaro, Ana Erika; Rocha-Uribe, Alejandro; Pérez-Martínez, Ana Silvia; Alpuche-Solís, Ángel Gabriel; Soria-Guerra, Ruth Elena

    2016-11-01

    Microalgae have the potential to accumulate triacylglycerols under different light spectra. In this work, Chlamydomonas reinhardtii was grown under white (400-700 nm), red (650 nm), and green (550 nm) lights. According to our results, red light (650 nm) has a positive effect in the microalgae growth and chlorophyll concentration. About the lipid content, the control culture (white light-illuminated) reached a 4.4% of dry cell weight (dcw), whereas the culture grown at 550 nm showed an increase of 1.35-fold in the lipids accumulation (5.96% dcw). Interestingly, the most significant accumulation was found in the culture grown at 650 nm (14.78% dcw) which means 3.36-fold higher with respect to the white light-illuminated culture. The most abundant fatty acids found in lipid extracts obtained from the cultures under different light wavelength were palmitic (C16: 0), oleic (C18: 1n9), stearidonic (C18: 4), and linoleic (C18: 2), which are useful in the biodiesel production. Changes in gene expression in response to different wavelength illuminations were assessed; however, an in-depth analysis of a larger number of genes involved in lipid biosynthesis is necessary to fully explain the highest accumulation of lipids in the culture grown under red light. This approach will be useful to find a sustainable source of lipids for biodiesel production. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1404-1411, 2016.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. The integration of GC-MS and LC-MS to assay the metabolomics profiling in Panax ginseng and Panax quinquefolius reveals a tissue- and species-specific connectivity of primary metabolites and ginsenosides accumulation.

    Science.gov (United States)

    Liu, Jia; Liu, Yang; Wang, Yu; Abozeid, Ann; Zu, Yuan-Gang; Tang, Zhong-Hua

    2017-02-20

    The traditional medicine Ginseng mainly including Panax ginseng and Panax quinquefolius is the most widely consumed herbal product in the world. Despite the extensive investigation of biosynthetic pathway of the active compounds ginsenosides, our current understanding of the metabolic interlink between ginsenosides synthesis and primary metabolism at the whole-plant level. In this study, the tissue-specific profiling of primary and the secondary metabolites in two different species of ginseng were investigated by gas chromatography- and liquid chromatography coupled to mass spectrometry. A complex continuous coordination of primary- and secondary-metabolic network was modulated by tissues and species factors during growth. The results showed that altogether 149 primary compounds and 10 ginsenosides were identified from main roots, lateral roots, stems, petioles and leaves in P. ginseng and P. quinquefolius. The partial least squares-discriminate analysis (PLS-DA) revealed obvious compounds distinction among tissue-specific districts relative to species. To survey the dedication of carbon and nitrogen metabolism in different tissues to the accumulation of ginsenosides, we inspected the tissue-specific metabolic changes. Our study testified that the ginsenosides content was dependent on main roots and lateral roots energy metabolism, whereas independent of leaves and petiole photosynthesis during ginsenosides accumulation. When tow species were compared, the results indicated that high rates of C assimilation to C accumulation are closely associated with ginsenosides accumulation in P. ginseng main roots and P. quinquefolius lateral roots, respectively. Taken together, our results suggest that tissue-specific metabolites profiling dynamically changed in process of ginsenosides biosynthesis, which may offer a new train of thoughts to the mechanisms of the ginsenosides biosynthesis at the metabolite level. Copyright © 2016 The Author(s). Published by Elsevier B.V. All

  2. In situ compositional control of advanced HgCdTe-based IR detectors

    Science.gov (United States)

    Almeida, L. A.; Dinan, J. H.

    1999-05-01

    The application of a feedback control system for maintaining a desired compositional profile during Hg 1- xCd xTe epitaxy is reported. A spectroscopic ellipsometer monitored the optical properties of Hg 1- xCd xTe films during deposition by molecular beam epitaxy. A library of optical constants was established from in situ measurements of multiple layers of varying composition. The compositions were subsequently determined ex situ using Fourier transform infrared spectroscopy. This work represents an extension of the compositional range of this control system to measure the x-values of Hg 1- xCd xTe sensitive to long-, mid-, and short-wavelength infrared (LWIR, MWIR, and SWIR) radiation (0.16CdTe effusion cell. The application of this control system is demonstrated by measuring the compositional profile of a three layer Hg 1- xCd xTe structure suitable for use as an MWIR/SWIR detector.

  3. Isolation, structural elucidation, MS profiling, and evaluation of triglyceride accumulation inhibitory effects of benzophenone C-glucosides from leaves of Mangifera indica L.

    Science.gov (United States)

    Zhang, Yi; Han, Lifeng; Ge, Dandan; Liu, Xuefeng; Liu, Erwei; Wu, Chunhua; Gao, Xiumei; Wang, Tao

    2013-02-27

    Seventy percent ethanol-water extract from the leaves of Mangifera indica L. (Anacardiaceae) was found to show an inhibitory effect on triglyceride (TG) accumulation in 3T3-L1 cells. From the active fraction, six new benzophenone C-glucosides, foliamangiferosides A(3) (1), A(4) (2), C(4) (3), C(5) (4), C(6) (5), and C(7) (6) together with 11 known benzophenone C-glucosides (7-17) were obtained. In this paper, isolation, structure elucidation (1-6), and MS fragment cleavage pathways of all 17 isolates were studied. 1-6 showed inhibitory effects on TG and free fatty acid accumulation in 3T3-L1 cells at 10 μM.

  4. NMR-based metabolic profiling in healthy individuals overfed different types of fat : links to changes in liver fat accumulation and lean tissue mass.

    OpenAIRE

    Elmsjö, Albert; Rosqvist, Fredrik; Engskog, Mikael K.R.; Haglöf, Jakob; Kullberg, Joel; Iggman, David; Johansson, Lars; Ahlström, Håkan; Arvidsson, Torbjörn; Risérus, Ulf; Pettersson, Curt

    2015-01-01

    BACKGROUND: Overeating different dietary fatty acids influence the amount of liver fat stored during weight gain, however, the mechanisms responsible are unclear. We aimed to identify non-lipid metabolites that may differentiate between saturated (SFA) and polyunsaturated fatty acid (PUFA) overfeeding using a non-targeted metabolomic approach. We also investigated the possible relationships between plasma metabolites and body fat accumulation. METHODS: In a randomized study (LIPOGAIN study), ...

  5. 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.

  6. 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.)

  7. 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.

  8. Expression profiles of genes related to carbohydrate metabolism provide new insights into carbohydrate accumulation in seeds and seedlings of Ricinus communis in response to temperature.

    Science.gov (United States)

    Ribeiro, Paulo R; Ligterink, Wilco; Hilhorst, Henk W M

    2015-10-01

    Ricinus communis possesses a specific metabolic signature to adjust growth and developmental processes in response to temperature: carbohydrates are accumulated at low temperatures, whereas amino acids are accumulated at elevated temperatures. Our objective was to assess tissue-specific changes in transcript levels of genes related with carbohydrate biosynthesis and catabolism in response to temperature. For that, we measured transcript levels of genes encoding enzymes involved in starch biosynthesis, starch catabolism, and gluconeogenesis in R. communis leaves, roots, and seeds grown at 20 °C and 35 °C. Transcript levels of genes involved in starch catabolism were higher in leaves grown at 20 °C than at 35 °C, but up-regulation of genes involved in starch biosynthesis seems to compensate for this and, therefore, are the likely explanation for higher levels of starch in leaves grown at 20 °C. Higher levels of soluble carbohydrates in leaves grown at 20 °C may be caused by a coordinated increase in transcript level of genes associated with starch catabolism and gluconeogenesis pathways. In roots, transcript levels of genes associated with starch catabolism and gluconeogenesis seem to be enhanced at elevated temperatures. Higher levels of starch in seeds germinated at low temperatures is associated with higher transcript levels of genes involved in starch biosynthesis. Similarly, higher transcript levels of RcPEPCK and RcFBPase are most likely causal for fructose and glucose accumulation in seeds germinated at 20 °C. This study provides important insights in the understanding of the plasticity of R. communis in response to temperature that may apply to other species as well. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  9. 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.

  10. 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...

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. Effects of dietary palmitoleic acid on plasma lipoprotein profile and aortic cholesterol accumulation are similar to those of other unsaturated fatty acids in the F1B golden Syrian hamster.

    Science.gov (United States)

    Matthan, Nirupa R; Dillard, Alice; Lecker, Jaime L; Ip, Blanche; Lichtenstein, Alice H

    2009-02-01

    The lower susceptibility of palmitoleic acid (16:1) to oxidation compared to PUFA may confer functional advantages with respect to finding acceptable alternatives to partially hydrogenated fats, but limited data are available on its effect on cardiovascular risk factors. This study investigated the effect of diets (10% fat, 0.1% cholesterol, wt:wt) enriched with macadamia [monounsaturated fatty acid (MUFA)16:1], palm (SFA,16:0), canola (MUFA,18:1), or safflower (PUFA,18:2) oils on lipoprotein profiles and aortic cholesterol accumulation in F1B Golden Syrian hamsters (n = 16/group). After 12 wk, 8 hamsters in each group were killed (phase 1). The remaining hamsters fed palm oil were changed to a diet containing coconut oil, while hamsters in the other diet groups continued on their original diets for an additional 6 wk (phase 2). With minor exceptions, the time course and dietary SFA source did not alter the study outcomes. Macadamia oil-fed hamsters had lower non-HDL cholesterol and triglyceride concentrations compared with the palm and coconut oil-fed hamsters and higher HDL-cholesterol compared with the coconut, canola, and safflower oil-fed hamsters. The aortic cholesterol concentration was not affected by dietary fat type. The hepatic cholesterol concentration was higher in the unsaturated compared with the saturated oil-fed hamsters. RBC membrane and aortic cholesteryl ester, triglyceride, and phospholipid fatty acid profiles reflected that of the dietary oil. These data suggest that an oil relatively high in palmitoleic acid does not adversely affect plasma lipoprotein profiles or aortic cholesterol accumulation and was similar to other unsaturated fatty acid-rich oils.

  17. The Partition Intervalometer: A Programmable Underwater Timer for Marking Accumulated Sediment Profiles Collected in Anderson Sediment Traps: Development, Operation, Testing Procedures, and Field Results

    Science.gov (United States)

    Rendigs, Richard R.; Anderson, Roger Y.; Xu, Jingping; Davis, Raymond E.; Bergeron, Emile M.

    2009-01-01

    This manual illustrates the development of a programmable instrument designed to deploy a series of wafer-shaped discs (partitions) into the collection tube of a sediment trap in various aquatic environments. These hydrodynamically shaped discs are deployed at discrete time intervals from the Intervalometer and provide markers that delineate time intervals within the sediments that accumulate in the collection tube. The timer and mechanical system are lodged in an air-filled, water-tight pressure housing that is vertically hung within the confines of a cone-shaped sediment trap. The instrumentation has been operationally pressure tested to an equivalent water depth of approximately 1 km. Flaws discovered during extensive laboratory and pressure testing resulted in the implementation of several mechanical modifications (such as a redesign of the rotor and the discs) that improved the operation of the rotor assembly as well as the release of discs through the end cap. These results also identified a preferred azimuth placement of the rotor disc relative to the drop hole of the end cap. In the initial field trial, five sediment traps and coupled Intervalometers were attached to moored arrays and deployed at two sites off the coast of Southern California for approximately 8 months. Each of the instruments released 18 discs at the programmed 10 day intervals, except one unit, which experienced a malfunction after approximately 4 months. Most of the discs oriented in a near-horizontal position upon the surface of the sediment in the collection tubes. Sampling of the sediments for geochemical analyses was improved by these clearly defined markers, which indicated the changes in the flux and nature of sediments accumulated during the deployment period of each sediment trap.

  18. [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.

  19. 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.

  20. 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...

  1. 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.

  2. 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.

  3. 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.

  4. Genome-wide identification and expression profile analysis of citrus sucrose synthase genes: investigation of possible roles in the regulation of sugar accumulation.

    Science.gov (United States)

    Islam, Mohammad Zahidul; Hu, Xiao-Mei; Jin, Long-Fei; Liu, Yong-Zhong; Peng, Shu-Ang

    2014-01-01

    Sucrose synthase (Sus) (EC 2.4.1.13) is a key enzyme for the sugar accumulation that is critical to form fruit quality. In this study, extensive data-mining and PCR amplification confirmed that there are at least six Sus genes (CitSus1-6) in the citrus genome. Gene structure and phylogeny analysis showed an evolutionary consistency with other plant species. The six Sus genes contain 12-15 exons and 11-14 introns and were evenly distributed into the three plant Sus groups (CitSus1 and CitSus2 in the Sus I group, CitSus3 and CitSus6 in the Sus II group, and CitSus4 and CitSus5 in the Sus III group). Transcripts of these six CitSus genes were subsequently examined. For tissues and organs, CitSus1 and 2 were predominantly expressed in fruit juice sacs (JS) whereas CitSus3 and 4 were predominantly expressed in early leaves (immature leaves), and CitSus5 and 6 were predominantly expressed in fruit JS and in mature leaves. During fruit development, CitSus5 transcript increased significantly and CitSus6 transcript decreased significantly in fruit JS. In the fruit segment membrane (SM), the transcript levels of CitSus2 and 5 were markedly higher and the abundant levels of CitSus3 and 6 gradually decreased. Moreover, transcript levels of CitSus1-4 examined were higher and the CitSus5 transcript level was lower in the fruit SM than in fruit JS, while CitSus6 had a similar transcript level in fruit JS and SM. In addition, transcripts of CitSus1-6 responded differently to dehydration in mature leaves or to mild drought stress in fruit JS and SM. Finally, the possible roles of Sus genes in the regulation of sugar accumulation are discussed; however, further study is required.

  5. Genome-wide identification and expression profile analysis of citrus sucrose synthase genes: investigation of possible roles in the regulation of sugar accumulation.

    Directory of Open Access Journals (Sweden)

    Mohammad Zahidul Islam

    Full Text Available Sucrose synthase (Sus (EC 2.4.1.13 is a key enzyme for the sugar accumulation that is critical to form fruit quality. In this study, extensive data-mining and PCR amplification confirmed that there are at least six Sus genes (CitSus1-6 in the citrus genome. Gene structure and phylogeny analysis showed an evolutionary consistency with other plant species. The six Sus genes contain 12-15 exons and 11-14 introns and were evenly distributed into the three plant Sus groups (CitSus1 and CitSus2 in the Sus I group, CitSus3 and CitSus6 in the Sus II group, and CitSus4 and CitSus5 in the Sus III group. Transcripts of these six CitSus genes were subsequently examined. For tissues and organs, CitSus1 and 2 were predominantly expressed in fruit juice sacs (JS whereas CitSus3 and 4 were predominantly expressed in early leaves (immature leaves, and CitSus5 and 6 were predominantly expressed in fruit JS and in mature leaves. During fruit development, CitSus5 transcript increased significantly and CitSus6 transcript decreased significantly in fruit JS. In the fruit segment membrane (SM, the transcript levels of CitSus2 and 5 were markedly higher and the abundant levels of CitSus3 and 6 gradually decreased. Moreover, transcript levels of CitSus1-4 examined were higher and the CitSus5 transcript level was lower in the fruit SM than in fruit JS, while CitSus6 had a similar transcript level in fruit JS and SM. In addition, transcripts of CitSus1-6 responded differently to dehydration in mature leaves or to mild drought stress in fruit JS and SM. Finally, the possible roles of Sus genes in the regulation of sugar accumulation are discussed; however, further study is required.

  6. 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.

  7. 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.

  8. Transportation and transformation of mercury in a calcine profile in the Wanshan Mercury Mine, SW China.

    Science.gov (United States)

    Yin, Runsheng; Gu, Chunhao; Feng, Xinbin; Zheng, Lirong; Hu, Ningning

    2016-12-01

    Calcination of Hg ores has resulted in serious contamination of mercury (Hg) in the environment. To understand the mobilization of Hg in the calcine pile, the speciation of Hg in a profile of a large calcine pile in the Wanshan Mercury Mine, SW China was investigated using the X-ray absorption spectroscopy (XANES), to understand the mobilization of Hg in the calcine pile. Higher concentrations of Hg were observed at the 30-50 cm depth of the profile, corresponding to a cemented layer. This layer is observed in the entire pile, and was formed due to cementation of calcines. Hg species in calcines include cinnabar (α-HgS), metacinnabar (β-HgS), elemental Hg(0), and minor mercuric chloride (HgCl2), but these Hg species show dramatic changes in the profile. Variations in Hg speciation suggest that extensive mobilization of Hg can occur during weathering processes. We show that the cemented layer can prevent the leaching of Hg and the emission of Hg(0) from the pile. High MeHg concentrations were found near the cemented layer, indicating Hg methylation occurs. This study provides important insights into the environmental risk of Hg in mining areas.

  9. 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...

  10. 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.

  11. 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.

  12. Massive accumulation of highly polluted sedimentary deposits by river damming

    Energy Technology Data Exchange (ETDEWEB)

    Palanques, Albert, E-mail: albertp@icm.csic.es [Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003 (Spain); Grimalt, Joan [Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona, 18, Barcelona 08034 (Spain); Belzunces, Marc; Estrada, Ferran; Puig, Pere; Guillén, Jorge [Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003 (Spain)

    2014-11-01

    Uncontrolled dumping of anthropogenic waste in rivers regulated by dams has created contaminated deposits in reservoirs that have remained unidentified for decades. The Flix Reservoir is located in the Ebro River, the second largest river flowing into the NW Mediterranean, has been affected by residue dumping from a chlor-alkali electrochemical plant for decades. High-resolution seismic profiles, bathymetric data, surficial sediment samples and sediment cores were obtained in the Flix Reservoir to study the characteristics of the deposit accumulated by this dumping. These data were used to reconstruct the waste deposit history. Since the construction of the Flix Dam in 1948, more than 3.6 × 10{sup 5} t of industrial waste has accumulated in the reservoir generating a delta-like deposit formed by three sediment lobes of fine-grained material highly contaminated by Hg, Cd, Zn and Cr (max: 640, 26, 420 and 750 mg kg{sup −1}, respectively). This contamination was associated with the Hg that was used for the cathode in the electrochemical plant from 1949 and with the production of phosphorite derivatives from 1973. After the construction of two large dams only a few kilometres upstream during the 1960s, the solids discharged from the industrial complex became the main sediment source to the Flix Reservoir. The deposit has remained in the reservoir forming a delta that obstructs about 50% of the river water section. Its stability only depended on the flow retention by the Flix Dam. At present, this contaminated waste deposit is being removed from the water reservoir as it is a cause of concern for the environment and for human health downriver. - Highlights: • A delta-like anthropogenic deposit prograded into the reservoir behind the Flix dam. • More than 3.6 × 10{sup 5} t of anthropogenic waste was accumulated in less than 4 decades. • A waste deposit with extreme levels of Hg and Cd was trapped in the Flix Reservoir. • The main pollution was related to

  13. Simultaneous determination of 13 carotenoids by a simple C18 column-based ultra-high-pressure liquid chromatography method for carotenoid profiling in the astaxanthin-accumulating Haematococcus pluvialis.

    Science.gov (United States)

    Jin, Hui; Lao, Yong Min; Zhou, Jin; Zhang, Huai Jin; Cai, Zhong Hua

    2017-03-10

    A simple ultra-high-pressure liquid chromatography (UHPLC) method for rapidly and simultaneously identifying thirteen carotenoids in Haematococcus pluvialis was developed in this study. The method is capable of effectively separating two astaxanthin isomers, two ζ-carotene isomers, and three phytoene isomers on two simple C18 columns within 9 and 12min only by using methanol and acetonitrile, respectively. To our best knowledge, this is the rapidest method for these carotenoid isomers, currently. Using this method, carotenoid profiling in the astaxanthin-accumulating H. pluvialis under environmental stresses was successfully carried out. Results indicated that carotenoid biosynthesis was differentially perturbed by environmental stresses, indicating that this simple and rapid method is suitable to not only bacterial but also algal samples, with potential applications for a wide range of samples from plant to animal. Finally, possible reasons for the elution order of carotenoids were studied.

  14. 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.

  15. 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.

  16. 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.

  17. Gene profiling of postnatal Mfrprd6 mutant eyes reveals differential accumulation of Prss56, visual cycle and phototransduction mRNAs.

    Science.gov (United States)

    Soundararajan, Ramani; Won, Jungyeon; Stearns, Timothy M; Charette, Jeremy R; Hicks, Wanda L; Collin, Gayle B; Naggert, Jürgen K; Krebs, Mark P; Nishina, Patsy M

    2014-01-01

    Mutations in the membrane frizzled-related protein (MFRP/Mfrp) gene, specifically expressed in the retinal pigment epithelium (RPE) and ciliary body, cause nanophthalmia or posterior microphthalmia with retinitis pigmentosa in humans, and photoreceptor degeneration in mice. To better understand MFRP function, microarray analysis was performed on eyes of homozygous Mfrprd6 and C57BL/6J mice at postnatal days (P) 0 and P14, prior to photoreceptor loss. Data analysis revealed no changes at P0 but significant differences in RPE and retina-specific transcripts at P14, suggesting a postnatal influence of the Mfrprd6 allele. A subset of these transcripts was validated by quantitative real-time PCR (qRT-PCR). In Mfrprd6 eyes, a significant 1.5- to 2.0-fold decrease was observed among transcripts of genes linked to retinal degeneration, including those involved in visual cycle (Rpe65, Lrat, Rgr), phototransduction (Pde6a, Guca1b, Rgs9), and photoreceptor disc morphogenesis (Rpgrip1 and Fscn2). Levels of RPE65 were significantly decreased by 2.0-fold. Transcripts of Prss56, a gene associated with angle-closure glaucoma, posterior microphthalmia and myopia, were increased in Mfrprd6 eyes by 17-fold. Validation by qRT-PCR indicated a 3.5-, 14- and 70-fold accumulation of Prss56 transcripts relative to controls at P7, P14 and P21, respectively. This trend was not observed in other RPE or photoreceptor mutant mouse models with similar disease progression, suggesting that Prss56 upregulation is a specific attribute of the disruption of Mfrp. Prss56 and Glul in situ hybridization directly identified Müller glia in the inner nuclear layer as the cell type expressing Prss56. In summary, the Mfrprd6 allele causes significant postnatal changes in transcript and protein levels in the retina and RPE. The link between Mfrp deficiency and Prss56 up-regulation, together with the genetic association of human MFRP or PRSS56 variants and ocular size, raises the possibility that these genes

  18. Gene profiling of postnatal Mfrprd6 mutant eyes reveals differential accumulation of Prss56, visual cycle and phototransduction mRNAs.

    Directory of Open Access Journals (Sweden)

    Ramani Soundararajan

    Full Text Available Mutations in the membrane frizzled-related protein (MFRP/Mfrp gene, specifically expressed in the retinal pigment epithelium (RPE and ciliary body, cause nanophthalmia or posterior microphthalmia with retinitis pigmentosa in humans, and photoreceptor degeneration in mice. To better understand MFRP function, microarray analysis was performed on eyes of homozygous Mfrprd6 and C57BL/6J mice at postnatal days (P 0 and P14, prior to photoreceptor loss. Data analysis revealed no changes at P0 but significant differences in RPE and retina-specific transcripts at P14, suggesting a postnatal influence of the Mfrprd6 allele. A subset of these transcripts was validated by quantitative real-time PCR (qRT-PCR. In Mfrprd6 eyes, a significant 1.5- to 2.0-fold decrease was observed among transcripts of genes linked to retinal degeneration, including those involved in visual cycle (Rpe65, Lrat, Rgr, phototransduction (Pde6a, Guca1b, Rgs9, and photoreceptor disc morphogenesis (Rpgrip1 and Fscn2. Levels of RPE65 were significantly decreased by 2.0-fold. Transcripts of Prss56, a gene associated with angle-closure glaucoma, posterior microphthalmia and myopia, were increased in Mfrprd6 eyes by 17-fold. Validation by qRT-PCR indicated a 3.5-, 14- and 70-fold accumulation of Prss56 transcripts relative to controls at P7, P14 and P21, respectively. This trend was not observed in other RPE or photoreceptor mutant mouse models with similar disease progression, suggesting that Prss56 upregulation is a specific attribute of the disruption of Mfrp. Prss56 and Glul in situ hybridization directly identified Müller glia in the inner nuclear layer as the cell type expressing Prss56. In summary, the Mfrprd6 allele causes significant postnatal changes in transcript and protein levels in the retina and RPE. The link between Mfrp deficiency and Prss56 up-regulation, together with the genetic association of human MFRP or PRSS56 variants and ocular size, raises the possibility that

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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...

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

    Science.gov (United States)

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

    2016-05-01

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

  5. 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.

  6. A water-soluble and retrievable ruthenium-based probe for colorimetric recognition of Hg(II) and Cys

    Science.gov (United States)

    Cui, Yali; Hao, Yuanqiang; Zhang, Yintang; Liu, Baoxia; Zhu, Xu; Qu, Peng; Li, Deliang; Xu, Maotian

    2016-08-01

    A new ruthenium-based complex 1 [(bis(4,4‧-dimethylphosphonic-2,2‧-bipyridine) dithiocyanato ruthenium (II))] was developed as a colorimetric probe for the detection of Hg(II) and Cys (Cysteine). The obtained compound 1 can give interconversional color changes upon the alternating addition of Hg(II) and Cys in 100% aqueous solution. The specific coordination between NCS groups with Hg(II) can lead to the formation of 1-Hg2 + complex, which can induce a remarkable spectral changes of probe 1. Afterwards the formed 1-Hg2 + complex can act as effective colorimetric sensor for Cys. Owing to the stronger binding affinity of sulfhydryl group to Hg2 +, Cys can extract Hg2 + from 1-Hg2 + complex resulting in the release of 1 and the revival of absorption profile of the probe 1. By introducing the hydrophilic phosphonic acid groups, the proposed probe exhibited excellent water solubility. The limits of detection (LODs) of the assay for Hg2 + and Cys are calculated to be 15 nM and 200 nM, respectively.

  7. 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

  8. 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.

  9. 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...

  10. 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

  11. 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.

  12. 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...

  13. 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.

  14. 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...

  15. 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.

  16. 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

  17. 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

  18. 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

  19. Production, separation and speciation of no-carrier-added Hg radionuclides using greener methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, S.; Nayak, D. [Chemical Sciences Div., Saba Inst. of Nuclear Physics, Kolkata (India)

    2010-07-01

    Species dependent studies of no-carrier-added (nca) mercury were carried out using radioanalytical technique coupled with two greener analytical methodologies. The adsorption of nca {sup 195mg}Hg and {sup 197m}Hg radionuclides on chitosan biopolymer and cloud point extraction (CPE) was studied to develop environmentally sustainable speciation methodologies at ultra trace level. Species information was obtained by comparing the adsorption profile of nca radiomercury on chitosan biopolymer with the software code CHEAQS PRO. Results obtained from the adsorption study were validated by CPE technique using non ionic surfactant and mixed micelle. Both the experiments established that nca Hg existed as Hg(II). The experimental results support the presence of HgCl{sub 2} species over the pH range 2-4, whereas Hg(OH){sub 2} is the main species over the pH range 6-8. Chitosan biopolymer and mixed micelle [Triton-X-114 and cetyltrimethylammonium bromide (CTAB)] constitute an efficient reagent for the preconcentration of ultra trace level mercury. (orig.)

  20. 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.

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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).

  8. 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.

  9. 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.

  10. 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)

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Ice slurry accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, K.G.; Kauffeld, M.

    1998-06-01

    More and more refrigeration systems are designed with secondary loops, thus reducing the refrigerant charge of the primary refrigeration plant. In order not to increase energy consumption by introducing a secondary refrigerant, alternatives to the well established single phase coolants (brines) and different concepts of the cooling plant have to be evaluated. Combining the use of ice-slurry - mixture of water, a freezing point depressing agent (antifreeze) and ice particles - as melting secondary refrigerant and the use of a cool storage makes it possible to build plants with secondary loops without increasing the energy consumption and investment. At the same time the operating costs can be kept at a lower level. The accumulation of ice-slurry is compared with other and more traditional storage systems. The method is evaluated and the potential in different applications is estimated. Aspects of practically use of ice-slurry has been examined in the laboratory at the Danish Technological Institute (DTI). This paper will include the final conclusions from this work concerning tank construction, agitator system, inlet, outlet and control. The work at DTI indicates that in some applications systems with ice-slurry and accumulation tanks have a great future. These applications are described by a varying load profile and a process temperature suiting the temperature of ice-slurry (-3 - -8/deg. C). (au)

  4. 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.

  5. 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.

  6. Directional Solidification and Characterization of Hg(0.89) Mn(0.11)Te

    Science.gov (United States)

    Price, M. W.; Scripa, R. N.; Lehoczky. S. L.; Szofran, F. R.; Su, C.-H.

    1998-01-01

    Two boules of Hg(0.89)Mn(0.11)Te(MMT) were solidified using the vertical Bridgman-Stockbarger method. Translation rates of 0.09 and 0. 18 microns/s were used. The influence of growth rate on axial compositional homogeneity in the MMT boules was evaluated experimentally by conducting precision density measurements on radial slices taken from each boule. In addition, Plane Front Solidification theory and segregation coefficient (k) data for the Hg(1-x)Mn(x)Te system were used to fit theoretical composition profiles to the measured MMT axial composition profiles. The strong correlation between the measured and calculated MMT axial composition profiles indicates diffusion dominated axial solute redistribution in the boules under the applied growth conditions. The analysis of the MMT axial composition profiles by Plane Front Solidification theory allowed the calculation of the effective diffusion coefficient (D(eff) = 3.5 x l0(exp -5) sq cm/s). The k-values for the Hg(1-x)Mn(x)Te system and the D(sub eff) - value were then used to verify that both boules were solidified under conditions which did not exceed the Constitutional Supercooling Criteria under ideal conditions. Finally, a preliminary examination of the radial compositional variation in each MMT was made using Fourier Transform Infra-Red Spectroscopy (FTIR). The radial homogeneity in the MMT boules was found to be comparable for both translation rates.

  7. 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).

  8. 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).

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

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

    Science.gov (United States)

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

    2006-12-01

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

  3. 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.

  4. 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...

  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. 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. 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.

  8. 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.

  9. 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

  10. 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.

  11. 黄绵土长期定位试验中硝态氮剖面分布特征%Effect of Long-term Located Fertilization on NO3--N Accumulation in the Profile of Loessial Soil

    Institute of Scientific and Technical Information of China (English)

    杨孔雀; 郝明德; 臧逸飞; 孙占育; 高亚利

    2011-01-01

    对1982年建立的长期肥料定位试验的土壤剖面硝态氮含量变化进行分析.结果表明,经25 a种植冬小麦施用不同肥料后,土壤0~400 cm土层硝态氮含量差异显著,施N、NP、NPK在200cm出现累积峰,各处理在300 cm以下硝态氮含量显著减少(低于1.0 mg/kg).对于CK、和单施P处理的100 cm以下土壤因长期没有N肥的补给,作物的长期吸收利用,而趋于耗竭(低于1.0 mg/kg);单施N和NP配施处理0~400cm土壤剖面中的氮残留量高达1 323.3kg/hm2,是不施肥的23.3倍,NPK配施也达655.9kg/hm2,是不施肥的11.1倍;M处理的残留量维持在1 018.6~1 753.1 kg/hm2左右,与化肥处理相比残留量显著增加,M处理比CK处理、NM处理比N处理、NPM处理比NP处理和NPKM处理比NPK处理分别增加了93.1%、21.1%、32.5%和83.3%.单施N的硝态氮年残留率最大,相当于施肥量的48.6%;NP配施残留率33.6%,NPK为21.3%.M、NM、NPM和NPKM处理的硝态氮残留率分别为2.6%、33.2%、25.2%和22.8%.平衡施肥能显著减少硝态氮含量,相同施氮水平下,配施磷肥、钾肥、有机肥的硝态氮残留率显著减少.%A 25 years fertilization experiment was carried out with wheat-grown Loessial soil in North China, and the profile of nitric nitrogen content in soil was analyzed. The results showed that there is significant differences on NO3--N contents in the 0-400 cm soil layer, after 25 years cultivation of the winter wheat. It showed an peak accumulation at 200 cm soil layer, and reduced significantly under 300 cm soil layer, ( less than 1.0 mg/kg) in N, NP and NPK treatment. When organic fertilizer supplied only, the accumulation of NO3--N increased in the surface of soil and tended to exhaust under the 120 cm soil layer. The NO3--N content in N and NP treatment was more than 1323.3kg/hm2 ,about 23.3 times of that in CK treatment, and 655.9 kg/hm2 and about 11.1 times in NPK treatment.The NO3 -N in manure treatment was about 1 028.6 to 1 753

  12. 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.

  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. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

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

    Science.gov (United States)

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

    2017-09-01

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

  2. 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

  3. 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">

  4. 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

  5. [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.

  6. 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.

  7. 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).

  8. Comparison of gaseous oxidized Hg measured by KCl-coated denuders, and nylon and cation exchange membranes.

    Science.gov (United States)

    Huang, Jiaoyan; Miller, Matthieu B; Weiss-Penzias, Peter; Gustin, Mae Sexauer

    2013-07-02

    The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.

  9. Solids Accumulation Scouting Studies

    Energy Technology Data Exchange (ETDEWEB)

    Duignan, M. R.; Steeper, T. J.; Steimke, J. L.

    2012-09-26

    The objective of Solids Accumulation activities was to perform scaled testing to understand the behavior of remaining solids in a Double Shell Tank (DST), specifically AW-105, at Hanford during multiple fill, mix, and transfer operations. It is important to know if fissionable materials can concentrate when waste is transferred from staging tanks prior to feeding waste treatment plants. Specifically, there is a concern that large, dense particles containing plutonium could accumulate in poorly mixed regions of a blend tank heel for tanks that employ mixing jet pumps. At the request of the DOE Hanford Tank Operations Contractor, Washington River Protection Solutions, the Engineering Development Laboratory of the Savannah River National Laboratory performed a scouting study in a 1/22-scale model of a waste staging tank to investigate this concern and to develop measurement techniques that could be applied in a more extensive study at a larger scale. Simulated waste tank solids: Gibbsite, Zirconia, Sand, and Stainless Steel, with stainless steel particles representing the heavier particles, e.g., plutonium, and supernatant were charged to the test tank and rotating liquid jets were used to mix most of the solids while the simulant was pumped out. Subsequently, the volume and shape of the mounds of residual solids and the spatial concentration profiles for the surrogate for heavier particles were measured. Several techniques were developed and equipment designed to accomplish the measurements needed and they included: 1. Magnetic particle separator to remove simulant stainless steel solids. A device was designed and built to capture these solids, which represent the heavier solids during a waste transfer from a staging tank. 2. Photographic equipment to determine the volume of the solids mounds. The mounds were photographed as they were exposed at different tank waste levels to develop a composite of topographical areas. 3. Laser rangefinders to determine the volume of

  10. Quantitative imaging of D-2-hydroxyglutarate (D2HG in selected histological tissue areas by a novel bioluminescence technique

    Directory of Open Access Journals (Sweden)

    Nadine Fabienne Voelxen

    2016-03-01

    Full Text Available AbstractPatients with malignant gliomas have a poor prognosis with average survival of less than one year. Whereas in other tumor entities the characteristics of tumor metabolism are successfully used for therapeutic approaches, such developments are very rare in brain tumors, notably in gliomas. One metabolic feature characteristic of gliomas, in particular diffuse astrocytomas and oligodendroglial tumors, is the variable content of D-2-hydroxyglutarate (D2HG, a metabolite, which was discovered first in this tumor entity. D2HG is generated in large amounts due to various gain-of–function mutations in the isocitrate dehydrogenases IDH-1 and IDH-2. Meanwhile, D2HG has been detected in several other tumor entities including intrahepatic bile-duct cancer, chondrosarcoma, acute myeloid leukemia, and angioimmunoblastic T-cell lymphoma. D2HG is barely detectable in healthy tissue (< 0.1 mM, but its concentration increases up to 35 mM in malignant tumor tissues. Consequently, the oncometabolite D2HG has gained increasing interest in the field of tumor metabolism. To facilitate its quantitative measurement without loss of spatial resolution at a microscopical level, we have developed a novel bioluminescence assay for determining D2HG in sections of snap-frozen tissue. The assay was verified independently by photometric tests and liquid chromatography / mass spectrometry (LC/MS. The novel technique allows the microscopically resolved determination of D2HG in a concentration range of 0 – 10 µmol/g tissue (wet weight. In combination with the already established bioluminescence imaging techniques for ATP, glucose, pyruvate, and lactate, the novel D2HG assay enables a comparative characterization of the metabolic profile of individual tumors in a further dimension.

  11. 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.

  12. Recent accumulation rate at Dome A, Antarctica

    Institute of Scientific and Technical Information of China (English)

    HOU ShuGui; LI YuanSheng; XIAO CunDe; REN JiaWen

    2007-01-01

    Based on the horizon of β activity and the density profiles, recent accumulation rate at Dome A, Antarctica is calculated to be 0.023 m water equivalent per year. This value is comparative to the accumulation rates deduced from the other inland sites of Antarctica. Clear-sky precipitation (or diamond dust) dominates the total precipitation at Dome A region. We speculate Dome A as a potential site to discover the oldest ice in Antarctica due to its tremendous ice thickness (>3000 m), extremely low accumulation rate, and low ice velocity.

  13. 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.

  14. 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 ...

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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).

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. 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

    Full Text Available Accumulation of mercury (Hg by arrow cane (Gynerium sagittatum (Aubl Beauv. in vitro RESUMEN  En este estudio se evaluó, in vitro, la capacidad de acumulación de mercurio (Hg que pueda poseer la caña flecha (Gynerium sagittatum (Aubl Beauv. como una alternativa viable de ser implementada para la rehabilitación de suelos contaminados. Este estudio fue realizado en el laboratorio de Biotecnología Vegetal de la Universidad de Sucre (9º18’ N, 75º23’ O. Se usó un diseño experimental de bloques al azar, un análisis de varianza para comparación de medias, una prueba de Tukey (p≤0,05 para la establecer las diferencias significativas entre los tratamientos, pruebas de normalidad (Kolmogorov-Smirnov y test de homogeneidad de varianza de Bartlett. Los análisis de mercurio se realizaron en un espectrofotómetro de absorción atómica Thermo Electron S4, provisto de una celda con ventanas de cuarzo, por el método de espectroscopia de absorción atómica con vapor frío. Los resultados muestran que la parte de la planta que presenta mayor acumulación es la raíz con 55,98 µg g-1 HgT, seguida de los tallos-hojas con 14,84 µg g-1 HgT, valores relacionados con el grado de concentración del metal en el medio de cultivo. Además, la acumulación de mercurio en raíces y tallos aumentó con el tiempo. En conclusión, in vitro esta planta acumula Hg debido a las altas concentraciones en sus tejidos sin afectar la viabilidad de las plantas.Palabras clave: fitorremediación, remoción, metales pesados.ABSTRACTIn this in vitro study was evaluated the potential for accumulation of mercury (Hg that can hold the cane arrow (Gynerium sagittatum (Aubl Beauv. as a viable alternative to be implemented for the rehabilitation of contaminated soils. This study was conducted at the Plant Biotechnology Laboratory, University of Sucre (9º 18' N, 75° 23' W. An experimental design was randomized block, an analysis of variance to compare means, Tukey test

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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).

  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. 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.

  5. 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 increased from 200 to 400°C. Upon pretreatment with HCl and O2 at 350°C, the catalyst demonstrated higher catalytic activity for Hg(0) oxidation. Notably, the effect of pretreatment with HCl alone was not obvious. For the catalyst treated with HCl and O2, better performance was observed with lower reaction temperatures. The results showed that both HCl and Hg(0) were first adsorbed onto the catalyst and then reacted with O2 following its adsorption, which indicates that the oxidation of Hg(0) over the commercial catalyst followed the Langmuir-Hinshelwood mechanism. Several characterization techniques, including Hg(0) temperature-programmed desorption (Hg-TPD) and X-ray photoelectron spectroscopy (XPS), were employed in this work. Hg-TPD profiles showed that weakly adsorbed mercury species were converted to strongly bound species in the presence of HCl and O2. XPS patterns indicated that new chemisorbed oxygen species were formed by the adsorption of HCl, which consequently facilitated the oxidation of mercury.

  6. 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).

  7. 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.

  8. 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

  9. Dry etched SiO2 Mask for HgCdTe Etching Process

    Science.gov (United States)

    Chen, Y. Y.; Ye, Z. H.; Sun, C. H.; Deng, L. G.; Zhang, S.; Xing, W.; Hu, X. N.; Ding, R. J.; He, L.

    2016-09-01

    A highly anisotropic etching process with low etch-induced damage is indispensable for advanced HgCdTe (MCT) infrared focal plane array (IRFPA) detectors. The inductively coupled plasma (ICP) enhanced reactive ion etching technique has been widely adopted in manufacturing HgCdTe IRFPA devices. An accurately patterned mask with sharp edges is decisive to accomplish pattern duplication. It has been reported by our group that the SiO2 mask functions well in etching HgCdTe with high selectivity. However, the wet process in defining the SiO2 mask is limited by ambiguous edges and nonuniform patterns. In this report, we patterned SiO2 with a mature ICP etching technique, prior to which a thin ZnS film was deposited by thermal evaporation. The SiO2 film etching can be terminated at the auto-stopping point of the ZnS layer thanks to the high selectivity of SiO2/ZnS in SF6 based etchant. Consequently, MCT etching was directly performed without any other treatment. This mask showed acceptable profile due to the maturity of the SiO2 etching process. The well-defined SiO2 pattern and the etched smooth surfaces were investigated with scanning electron microscopy and atomic force microscope. This new mask process could transfer the patterns exactly with very small etch-bias. A cavity with aspect-ratio (AR) of 1.2 and root mean square roughness of 1.77 nm was achieved first, slightly higher AR of 1.67 was also get with better mask profile. This masking process ensures good uniformity and surely benefits the delineation of shrinking pixels with its high resolution.

  10. Growth and characterization of Hg(1-x)Cd(x)Se alloys

    Science.gov (United States)

    Andrews, R. N.; Szofran, F. R.; Lehoczky, S. L.

    1988-01-01

    A detailed evaluation of the influence of growth conditions on the radial and axial compositional variations in directionally solidified Hg(1-x)Cd(x)Se alloys was performed. The measured axial compositional profiles were fitted to theoretical profiles to determine the effective solute (CdSe) diffusion coefficient (D) for the Hg(1-x)Cd(x)Se system. The value for D was estimated to be 3.0 + or - 0.5 x 10 to the -5th sq cm/s and did not appear to be significantly affected by the rate of crystal growth. The axial crystal uniformity was shown to be highly growth-rate dependent, with the faster growth rates producing crystals of more uniform composition in the axial direction. The magnitude of the radial variations was also shown to be highly growth-rate dependent, with the slower growth rates producing crystals of greater radial uniformity. This translation rate dependence of the radial uniformity is discussed in terms of lateral solute diffusion and convective interfacial fluid flows.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. Spectroscopic variability and magnetic fields of HgMn stars

    CERN Document Server

    Hubrig, S; Ilyin, I; Korhonen, H; Savanov, I S; Dall, T; Schoeller, M; Cowley, C R; Briquet, M; Arlt, R

    2011-01-01

    The discovery of exotic abundances, chemical inhomogeneities, and weak magnetic fields on the surface of late B-type primaries in spectroscopic binaries has important implications not only for our understanding of the formation mechanisms of stars with Hg and Mn peculiarities themselves, but also for the general understanding of B-type star formation in binary systems. The origin of the abundance anomalies observed in late B-type stars with HgMn peculiarity is still poorly understood. The connection between HgMn peculiarity and membership in binary and multiple systems is supported by our observations during the last decade. The important result achieved in our studies of a large sample of HgMn stars is the finding that most HgMn stars exhibit spectral variability of various chemical elements, proving that the presence of an inhomogeneous distribution on the surface of these stars is a rather common characteristic and not a rare phenomenon. Further, in the studied systems, we found that all components are che...

  16. Are there tangled magnetic fields on HgMn stars?

    CERN Document Server

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

    2013-01-01

    Several recent spectrophotometric studies failed to detect significant global magnetic fields in late-B HgMn chemically peculiar stars, but some investigations have suggested the presence of strong unstructured or tangled fields in these objects. We used detailed spectrum synthesis analysis to search for evidence of tangled magnetic fields in high-quality observed spectra of 8 slowly rotating HgMn stars and one normal late-B star. We also evaluated recent sporadic detections of weak longitudinal magnetic fields in HgMn stars based on the moment technique. Our analysis of the Zeeman broadening of magnetically sensitive spectral lines reveals no evidence of tangled magnetic fields in any of the studied HgMn or normal stars. We infer upper limits of 200-700 G for the mean magnetic field modulus -- much smaller than the field strengths implied by studies based on differential magnetic line intensification and quadratic field diagnostics. The new HARPSpol longitudinal field measurements for the extreme HgMn star H...

  17. Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753

    CERN Document Server

    Briquet, M; Gonzalez, J F; Hubrig, S; Hackman, T

    2010-01-01

    Aims. We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, HD 11753, HD 53244, and HD 221507, to search for slowly pulsating B-like pulsations and surface inhomogeneous distribution of various chemical elements. Methods. Classical frequency analysis methods were used to detect line profile variability and to determine the variation period. Doppler imaging reconstruction was performed to obtain abundance maps of chemical elements on the stellar surface. Results. For HD 11753, which is the star with the most pronounced variability, distinct spectral line profile changes were detected for Ti, Sr, Y, Zr, and Hg, whereas for HD 53244 and HD 221507 the most variable line profiles belong to the elements Hg and Y, respectively. We derived rotation periods for all three stars from the variations of radial velocities and equivalent widths of spectral lines belonging to inhomogeneously distributed elements: P_rot (HD 11753)=9.54 d, P_rot (HD 53244)=6.16 d, and P_rot (HD 221507)=...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Crystal structure of Hg2SO4 – a redetermination

    Directory of Open Access Journals (Sweden)

    Matthias Weil

    2014-09-01

    Full Text Available The crystal structure of mercury(I sulfate (or mercurous sulfate, Hg2SO4, was re-determined based on modern CCD data. In comparison with the previous determination from Weissenberg film data [Dorm (1969. Acta Chem. Scand. 23, 1607–1615], all atoms were refined with anisotropic displacement parameters, leading to higher precision in terms of bond lengths and angles [e.g. Hg—Hg = 2.5031 (7 compared to 2.500 (3Å]. The structure consists of alternating rows along [001] of Hg22+ dumbbells (generated by inversion symmetry and SO42− tetrahedra (symmetry 2. The dumbbells are linked via short O—Hg—Hg—O bonds to the sulfate tetrahedra into chains extending parallel to [20-1]. More remote O—Hg—Hg—O bonds connect these chains into a three-dimensional framework.

  3. Characterization studies of purified HgI{sub 2} precursors

    Energy Technology Data Exchange (ETDEWEB)

    Schieber, M. E-mail: Schieber@vms.huji.ac.il; Zuck, A.; Sanguinetti, S.; Montalti, M.; Braiman, M.; Melekhov, L.; Nissenbaum, J.; Grilli, E.; Guzzi, M.; Turchetta, R.; Dulinski, W.; Husson, D.; Riester, J.L

    1999-06-01

    The ability of HgI{sub 2} powders, used as precursors in mercuric iodide crystal growth, to produce high-quality detectors may be predicted by non-destructive methods like photoluminescence. In fact, it is possible to correlate the presence and the intensity ratio of specific bands in the photoluminescence spectrum of a HgI{sub 2} crystal to its impurity content and stoichiometry. These quantities determine the detector grade that may be achieved using that starting material. Nine different HgI{sub 2} precursors, obtained by different purification methods, have been characterized. The lowest impurity content is achieved via poly-ethylene treatment, which gives also a powder of relatively good stoichiometric quality.

  4. [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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Forecasting temperate alpine glacier survival from accumulation zone observations

    Directory of Open Access Journals (Sweden)

    M. S. Pelto

    2010-01-01

    Full Text Available Temperate alpine glacier survival is dependent on the consistent presence of an accumulation zone. Frequent low accumulation area ratio values, below 30%, indicate the lack of a consistent accumulation zone, which leads to substantial thinning of the glacier in the accumulation zone. This thinning is often evident from substantial marginal recession, emergence of new rock outcrops and surface elevation decline in the accumulation zone. In the North Cascades 9 of the 12 examined glaciers exhibit characteristics of substantial accumulation zone thinning; marginal recession or emergent bedrock areas in the accumulation zone. The longitudinal profile thinning factor, f, which is a measure of the ratio of thinning in the accumulation zone to that at the terminus, is above 0.6 for all glaciers exhibiting accumulation zone thinning characteristics. The ratio of accumulation zone thinning to cumulative mass balance is above 0.5 for glacier experiencing substantial accumulation zone thinning. Without a consistent accumulation zone these glaciers are forecast not to survive the current climate or future additional warming. The results vary considerably with adjacent glaciers having a different survival forecast. This emphasizes the danger of extrapolating survival from one glacier to the next.

  15. 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

  16. 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...

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Depth Profiling (ICP-MS Study of Toxic Metal Buildup in Concrete Matrices: Potential Environmental Impact

    Directory of Open Access Journals (Sweden)

    Ghada Bassioni

    2010-10-01

    Full Text Available This paper explores the potential of concrete material to accumulate toxic trace elements using ablative laser technology (ICP-MS. Concrete existing in offshore structures submerged in seawater acts as a sink for hazardous metals, which could be gradually released into the ocean creating pollution and anoxic conditions for marine life. Ablative laser technology is a valuable tool for depth profiling concrete to evaluate the distribution of toxic metals and locate internal areas where such metals accumulate. Upon rapid degradation of concrete these “hotspots” could be suddenly released, thus posing a distinct threat to aquatic life. Our work simulated offshore drilling conditions by immersing concrete blocks in seawater and investigating accumulated toxic trace metals (As, Be, Cd, Hg, Os, Pb in cored samples by laser ablation. The experimental results showed distinct inhomogeneity in metal distribution. The data suggest that conditions within the concrete structure are favorable for random metal accumulation at certain points. The exact mechanism for this behavior is not clear at this stage and has considerable scope for extended research including modeling and remedial studies.

  5. 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

  6. 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.).

  7. Sediment geochemistry and accumulation rates on the northeastern shelf of the Gulf of Cádiz (SW Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    Roberta Guerra

    2010-11-01

    Full Text Available Geochemistry, total organic carbon and total nitrogen of three sediment cores collected in the Gulf of Cádiz and the Guadalquivir prodelta areas in Spain were investigated. The C/N ratio, mostly around 10, seems to indicate a predominantly marine origin for the sedimentary organic matter. Major and minor elements (Si, Ti, Al, Fe, Mg, Ca, K, Na, P, S and trace elements (Mn, Sc, V, Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Ba, Ce, Pb, Hg showed significant differences in bulk chemical composition between the two areas. Despite the effects of bioturbation, vertical changes in downcore profiles of heavy metals occur only in the cores of the Cádiz area, although the concentrations keep to low levels. The relatively high concentrations of Zr and Y, elements commonly associated with the heavy minerals fraction, at the top of cores from the Cádiz area are attributed to an enrichment of heavy minerals related to selective transport that concentrates this fraction. 137Cs and 210Pb activities in one of the two sediment cores collected in the Gulf of Cádiz were also measured. The distribution of excess 210Pb was used to determine the modern (last 100 yr mass accumulation rate and the depth of sediment mixing on the continental shelf of the gulf. Estimated sediment accumulation rate was 0.1 g cm-2 yr-1. The uppermost 4 cm had uniform excess 210Pb activity profiles above a region of steadily decreasing 210Pb activity, and this phenomenon was attributed to sediment mixing (bioturbation. 137Cs activity was lower than 3 Bq kg-1 and the profile does not show evidence of fallout peaks.

  8. 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.

  9. 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

  10. 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.

  11. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  13. 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.

  14. Growth and characterization of Hg(1-x)Zn(x)Se

    Science.gov (United States)

    Andrews, R. N.

    1986-01-01

    Hg sub 1-xZn sub xSe alloys of composition x=0.10 were grown in a Bridgman-Stockbarger growth furnace at translation rates of 0.3 and 0.1 micron sec. The axial and radial composition profiles were determined using precision density measurements and IR transmission-edge-mapping, respectively. A more radially homogeneous alloy was produced at the slower growth rate, while the faster growth rate produced more axially homogeneous alloys. A determination of the electrical properties of the Hg sub 1-xZn sub xSe samples in the temperature range 300K-20K was also made. Typical carrier concentrations were on the order of magnitude of 10 to the 18th power cu/cm, and remained fairly constant as a function of temperature. A study was also made of the temperature dependence of the resistivity and Hall mobility. The effect of annealing in a selenium vapor on both the IR transmission and the electrical properties was determined. Annealing was effective in reducing the number of native donor defects and at the resulting lower carrier concentrations, charge carrier concentration was shown to be a function of temperature. Annealing caused the mobility to increase, primarily at the lower temperature, and the room temperature resistivity to increase. Annealing was also observed to greatly enhance the % IR transmittance of the samples. This was due primarily to the effect of annealing on decreasing the charge carrier concentration.

  15. 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.

  16. 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.

  17. Mercury contamination in human hair and fish from Cambodia: levels, specific accumulation and risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Agusa, Tetsuro [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Kunito, Takashi [Department of Environmental Sciences, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Iwata, Hisato [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Monirith, In [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Tana, Touch Seang [Social and Cultural Observation Unit (OBSES) of the Cabinet of the Council of Ministers, Phnom Penh (Cambodia); Subramanian, Annamalai [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Tanabe, Shinsuke [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan)]. E-mail: shinsuke@agr.ehime-u.ac.jp

    2005-03-01

    Mercury (Hg) concentrations in human hair and fish samples from Phnom Penh, Kien Svay, Tomnup Rolork and Batrong, Cambodia, collected in November 1999 and December 2000 were determined to understand the status of contamination, and age- and sex-dependent accumulation in humans and to assess the intake of mercury via fish consumption. Mercury concentrations in human hair ranged from 0.54 to 190 {mu}g/g dry wt. About 3% of the samples contained Hg levels exceeding the no observed adverse effects level (NOAEL) of WHO (50 {mu}g/g) and the levels in some hair samples of women also exceeded the NOAEL (10 {mu}g/g) associated with fetus neurotoxicity. A weak but significant positive correlation was observed between age and Hg levels in hair of residents. Mercury concentrations in muscle of marine and freshwater fish from Cambodia ranged from <0.01 to 0.96 {mu}g/g wet wt. Mercury intake rates were estimated on the basis of the Hg content in fish and daily fish consumption. Three samples of marine fish including sharp-tooth snapper and obtuse barracuda, and one sample of sharp-tooth snapper exceeded the guidelines by US EPA and by Joint FAO/WHO Expert Committee on Food Additives (JECFA), respectively, which indicates that some fish specimens examined (9% and 3% for US EPA and JECFA guidelines, respectively) were hazardous for consumption at the ingestion rate of Cambodian people (32.6 g/day). It is suggested that fish is probably the main source of Hg for Cambodian people. However, extremely high Hg concentrations were observed in some individuals and could not be explained by Hg intake from fish consumption, indicating some other contamination sources of Hg in Cambodia. - A source other than fish may be responsible for high Hg in some Cambodians.

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

    Science.gov (United States)

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

    2011-12-01

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

  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. 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.

  1. 640 X 480 Pace HgCdTe FPA

    Science.gov (United States)

    Kozlowski, Lester J.; Bailey, Robert B.; Cabelli, Scott A.; Cooper, Donald E.; McComas, Gail D.; Vural, Kadri; Tennant, William E.

    1992-12-01

    A hybrid HgCdTe 640 X 480 infrared (IR) focal plane array (FPA) that meets the sensitivity, resolution, and field-of-view requirements of high-performance medium wavelength infrared (MWIR) imaging systems has been developed. The key technology making this large, high sensitivity device producible is the epitaxial growth of HgCdTe on a CdTe-buffered, sapphire substrate (referred to as PACE, for Producible Alternative to CdTe for Epitaxy; PACE-I refers to sapphire). The device offers TV resolution with excellent sensitivity at temperatures below 120 K. Mean NE(Delta) T as low as 13 mK has been achieved at operating temperatures nonuniformity compensation.

  2. Electrical Conductivity of HgTe at High Temperatures

    Science.gov (United States)

    Li, C.; Lehoczky, S. L.; Su, C.-H.; Scripa, R. N.

    2004-01-01

    The electrical conductivity of HgTe was measured using a rotating magnetic field method from 300 K to the melting point (943 K). A microscopic theory for electrical conduction was used to calculate the expected temperature dependence of the HgTe conductivity. A comparison between the measured and calculated conductivities was used to obtain the estimates of the temperature dependence of Gamma(sub 6)-Gamma(sub 8) energy gap from 300 K to 943 K. The estimated temperature coefficient for the energy gap was comparable to the previous results at lower temperatures (less than or equal to 300 K). A rapid increase in the conductivity just above 300 K and a subsequent decrease at 500 K is attributed to band crossover effects. This paper describes the experimental approach and some of the theoretical calculation details.

  3. Electronic structure of rectangular HgTe quantum dots

    Science.gov (United States)

    Li, Jian; Zhang, Dong; Zhu, Jia-Ji

    2017-09-01

    We theoretically investigate the single- and few-electron ground-states properties of HgTe topological insulator quantum dots with rectangular hard-wall confining potential using configuration interaction method. For the case of single electron, the edge states is robust against the deformation from a square quantum dot to a rectangular ones, in contrast to the bulk states, the energy gap of the QDs increased due to the coupling of the opposite edge states; for the case of few electrons, the electrons first fill the edge states in the bulk band gap and the addition energy exhibit universal even-odd oscillation due to the shape-independent two-fold degeneracy of the edge states. The size of this edge shell can be controlled by tuning the dot size, shape or the bulk band gap via lateral or vertical electric gating respectively of the HgTe quantum dot.

  4. 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

  5. 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.

  6. Hvordan understøttes hg-elevers kompetenceudvikling

    DEFF Research Database (Denmark)

    Svejgaard, Karin Løvenskjold; Hansen, Jens Ager; Karmark, Ole

    Publikationen handler om, hvordan hg-elever arbejder og dermed lærer og udvikler kvalifikationer og kompetencer i de undervisnings- og arbejdsformer, de indgår i. Indholdet er baseret på observationer af elever i klasseundervisning, gruppearbejde eller individuel arbejde i forlængelse af...... klasseundervisning og af elever i projektarbejde. Observationerne er gennemført på tre jyske handelsskoler....

  7. Temperature dependence of Hg{sub 0.68}Cd{sub 0.32}Te infrared photoconductor performance

    Energy Technology Data Exchange (ETDEWEB)

    Siliquini, J.F.; Musca, C.A.; Nener, B.D.; Faraone, L. [Univ. of Western Australia, Nedlands, Western Australia (Australia). Dept. of Electrical and Electronic Engineering

    1995-08-01

    An experimental and theoretical study has been carried out of the temperature dependent noise and responsivity performance of n-type x = 0.32 Hg{sub 1{minus}x}Cd{sub x}Te photoconductors. The fundamental noise sources that ultimately limit the specific detectivity, D*{sub {lambda}}, at the three main temperatures of interest are identified and correlated with the experimental material parameters of the device. A device model is presented for the responsivity and noise voltage which takes into account surface effects such as surface recombination and accumulation layer shunting. For a given set of device and material parameters this model is well able to account for the observed experimental values of responsivity and noise voltage over the full temperature range from 80--300 K. Using a theoretical model, it is shown that under ideal conditions it is possible to achieve background limited performance at temperatures up to 210 K. Experimental results are presented for responsivity, noise voltage, semiconductor surface charge density and D*{sub {lambda}} for a frontside-illuminated Hg{sub 1{minus}x} Cd{sub x} Te photoconductive detector, as a function of temperature in the range 80--300 K. The devices were fabricated on Liquid Phase Epitaxially (LPE) grown n-type Hg{sub 0.68}Cd{sub 0.32}Te, and were passivated with anodic oxide/ZnS on the front side.

  8. X-ray study of the anomalous thermal hystereses of the modulation wavevectors in Cs2HgCl4

    Science.gov (United States)

    Bagautdinov, Bagautdin; Shaw, Zachery; Orlov, Andrii; Aliev, Marat A.

    2016-05-01

    A rich sequence of structural modulations in Cs2HgCl4 as a function of temperature was studied by means of X-ray diffraction. Accurate satellite-position measurements on the cooling and heating paths of the crystal revealed abnormal thermal hystereses for incommensurate phases and coexistences of neighboring commensurate phases. A well-defined X-ray picture of the a-axis modulated phases in the range of 221-184 K were observed on the heating path, while the c-axis modulated phases existing below 184 K were definitely detected on the cooling path. The proper conditions for a precise phase diagram of Cs2HgCl4 can be correlated with relatively defect-free transformations of a-axis modulations at heating and of c-axis modulations at cooling. The peculiarity of Cs2HgCl4 to switch modulation direction among the a- and c-axes at 184 K allows us deliberately accumulate and thus control a majority of mobile defects on the mutually perpendicular (100) or (001) planes by possessing crystal within temperature domain of a- or c-axes modulations, respectively.

  9. Trace element accumulation in lotic dragonfly nymphs: Genus matters

    Science.gov (United States)

    Fletcher, Dean E.; Lindell, Angela H.; Stillings, Garrett K.; Blas, Susan A.; McArthur, J. Vaun

    2017-01-01

    Constituents of coal combustion waste (CCW) expose aquatic organisms to complex mixtures of potentially toxic metals and metalloids. Multi-element trace element analyses were used to distinguish patterns of accumulation among 8 genera of dragonfly nymphs collected from two sites on a CCW contaminated coastal plain stream. Dragonfly nymphs are exceptional for comparing trace element accumulation in syntopic macroinvertebrates that are all predators within the same order (Odonata) and suborder (Anisoptera), but differ vastly in habitat use and body form. Sixteen trace element (Be, V, Cr, Ni, Cu, Zn, As, Se, Sr, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) were analyzed and trophic position and basal carbon sources assessed with stable isotope analyses (C and N). Trophic positions varied within relatively narrow ranges. Size did not appear to influence trophic position. Trophic position rarely influenced trace element accumulation within genera and did not consistently correlate with accumulation among genera. Patterns between δ13C and trace element accumulation were generally driven by differences between sites. An increase in trace element accumulation was associated with a divergence of carbon sources between sites in two genera. Higher trace element concentrations tended to accumulate in nymphs from the upstream site, closer to contaminant sources. Influences of factors such as body form and habitat use appeared more influential on trace element accumulation than phylogeny for several elements (Ni, Ba, Sr, V, Be, Cd, and Cr) as higher concentrations accumulated in sprawler and the climber-sprawler genera, irrespective of family. In contrast, As and Se accumulated variably higher in burrowers, but accumulation in sprawlers differed between sites. Greater variation between genera than within genera suggests genus as an acceptable unit of comparison in dragonfly nymphs. Overall, taxonomic differences in trace element accumulation can be substantial, often exceeding variation

  10. Trace element accumulation in lotic dragonfly nymphs: Genus matters.

    Science.gov (United States)

    Fletcher, Dean E; Lindell, Angela H; Stillings, Garrett K; Blas, Susan A; McArthur, J Vaun

    2017-01-01

    Constituents of coal combustion waste (CCW) expose aquatic organisms to complex mixtures of potentially toxic metals and metalloids. Multi-element trace element analyses were used to distinguish patterns of accumulation among 8 genera of dragonfly nymphs collected from two sites on a CCW contaminated coastal plain stream. Dragonfly nymphs are exceptional for comparing trace element accumulation in syntopic macroinvertebrates that are all predators within the same order (Odonata) and suborder (Anisoptera), but differ vastly in habitat use and body form. Sixteen trace element (Be, V, Cr, Ni, Cu, Zn, As, Se, Sr, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) were analyzed and trophic position and basal carbon sources assessed with stable isotope analyses (C and N). Trophic positions varied within relatively narrow ranges. Size did not appear to influence trophic position. Trophic position rarely influenced trace element accumulation within genera and did not consistently correlate with accumulation among genera. Patterns between δ13C and trace element accumulation were generally driven by differences between sites. An increase in trace element accumulation was associated with a divergence of carbon sources between sites in two genera. Higher trace element concentrations tended to accumulate in nymphs from the upstream site, closer to contaminant sources. Influences of factors such as body form and habitat use appeared more influential on trace element accumulation than phylogeny for several elements (Ni, Ba, Sr, V, Be, Cd, and Cr) as higher concentrations accumulated in sprawler and the climber-sprawler genera, irrespective of family. In contrast, As and Se accumulated variably higher in burrowers, but accumulation in sprawlers differed between sites. Greater variation between genera than within genera suggests genus as an acceptable unit of comparison in dragonfly nymphs. Overall, taxonomic differences in trace element accumulation can be substantial, often exceeding variation

  11. 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.

  12. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-15

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

  14. Characterization of HgCdTe and HgCdSe Materials for Third Generation Infrared Detectors

    Science.gov (United States)

    2011-12-01

    etched HgCdTe photodiode .................................. 13 1.6 (a) Hybrid IR FPA, (b) cross section of structure, (c) indium bumps on Si...to areas of approximately 30 cm2. At this size, the wafers used for growth are unable to accommodate more than two 1024 × 1024 FPAs.3 For more...clear advantages over the other substrates because of its low cost, large wafer size, and a thermal-expansion coefficient that perfectly matches

  15. Biomonitoring of Cd, Cr, Hg and Pb in the Baluarte River basin associated to a mining area (NW Mexico).

    Science.gov (United States)

    Ruelas-Inzunza, J; Green-Ruiz, C; Zavala-Nevárez, M; Soto-Jiménez, M

    2011-08-15

    With the purpose of knowing seasonal variations of Cd, Cr, Hg and Pb in a river basin with past and present mining activities, elemental concentrations were measured in six fish species and four crustacean species in Baluarte River, from some of the mining sites to the mouth of the river in the Pacific Ocean between May 2005 and March 2006. In fish, highest levels of Cd (0.06 μg g ⁻¹ dry weight) and Cr (0.01 μg g⁻¹) were detected during the dry season in Gobiesox fluviatilis and Agonostomus monticola, respectively; the highest levels of Hg (0.56 μg g⁻¹) were detected during the dry season in Guavina guavina and Mugil curema. In relation to Pb, the highest level (1.65 μg g⁻¹) was detected in A. monticola during the dry season. In crustaceans, highest levels of Cd (0.05 μg g⁻¹) occurred in Macrobrachium occidentale during both seasons; highest concentration of Cr (0.09 μg g⁻¹) was also detected in M. occidentale during the dry season. With respect to Hg, highest level (0.20 μg g⁻¹) was detected during the rainy season in Macrobrachium americanum; for Pb, the highest concentration (2.4 μg g⁻¹) corresponded to Macrobrachium digueti collected in the dry season. Considering average concentrations of trace metals in surficial sediments from all sites, Cd (pseason. Biota sediment accumulation factors above unity were detected mostly in the case of Hg in fish during both seasons. On the basis of the metal levels in fish and crustacean and the provisional tolerable weekly intake of studied elements, people can eat up to 13.99, 0.79 and 2.34 kg of fish in relation to Cd, Hg and Pb, respectively; regarding crustaceans, maximum amounts were 11.33, 2.49 and 2.68 kg of prawns relative to levels of Cd, Hg and Pb, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Metabolic footprint analysis uncovers strain specific overflow metabolism and D-isoleucine production of Staphylococcus aureus COL and HG001.

    Science.gov (United States)

    Dörries, Kirsten; Lalk, Michael

    2013-01-01

    During infection processes, Staphylococcus aureus is able to survive within the host and to invade tissues and cells. For studying the interaction between the pathogenic bacterium and the host cell, the bacterial growth behaviour and its metabolic adaptation to the host cell environment provides first basic information. In the present study, we therefore cultivated S. aureus COL and HG001 in the eukaryotic cell culture medium RPMI 1640 and analyzed the extracellular metabolic uptake and secretion patterns of both commonly used laboratory strains. Extracellular accumulation of D-isoleucine was detected starting during exponential growth of COL and HG001 in RPMI medium. This non-canonical D-amino acid is known to play a regulatory role in adaptation processes. Moreover, individual uptake of glucose, accumulation of acetate, further overflow metabolites, and intermediates of the branched-chain amino acid metabolism constitute unique metabolic footprints. Altogether these time-resolved footprint analyses give first metabolic insights into staphylococcal growth behaviour in a culture medium used for infection related studies.

  17. Natural variation in expression of genes associated with carotenoid biosynthesis and accumulation in cassava (Manihot esculenta Crantz) storage root

    Science.gov (United States)

    Several groups have reported on massive accumulation of total carotenoids in cassava storage root (CSR). Naturally occurring color variation associated with carotenoid accumulation was observed in cassava (Manihot esculenta Crantz) storage root of landraces from Amazon. Here carotenoid profiles from...

  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. Dielectric properties of nanophase Ag2HgI4 and Ag2HgI4–Al2O3 nanocomposites

    Indian Academy of Sciences (India)

    S Sankara Narayanan Potty; M Abdul Khadar

    2000-10-01

    The dielectric properties of nanophase Ag2HgI4 and Ag2HgI4–Al2O3 nanocomposites at different frequencies have been studied over a temperature range covering the stability range of phase of Ag2HgI4 and beyond the to phase transition temperature. ', tan and a.c. of nanophase Ag2HgI4 and Ag2HgI4–Al2O3 nanocomposites were found to be larger than the reported values for polycrystalline pellets of Ag2HgI4 . The dielectric properties of the nanocomposites were found to be a function of the wt.% of nano alumina. The observed changes are attributed to the grain boundary properties of nanophase materials and to the microsize space charge effects.

  20. Association of a Specific Algal Group with Methylmercury Accumulation in Periphyton of a Tropical High-Altitude Andean Lake.

    Science.gov (United States)

    Lanza, William G; Achá, Darío; Point, David; Masbou, Jeremy; Alanoca, Lucia; Amouroux, David; Lazzaro, Xavier

    2017-01-01

    Periphyton relevance for methylmercury (MeHg) production and accumulation are now well known in aquatic ecosystems. Sulfate-reducing bacteria and other microbial groups were identified as the main MeHg producers, but the effect of periphyton algae on the accumulation and transfer of MeHg to the food web remains little studied. Here we investigated the role of specific groups of algae on MeHg accumulation in the periphyton of Schoenoplectus californicus ssp. (Totora) and Myriophyllum sp. in Uru Uru, a tropical high-altitude Bolivian lake with substantial fishing and mining activities accruing around it. MeHg concentrations were most strongly related to the cell abundance of the Chlorophyte genus Oedogonium (r (2) = 0.783, p = 0.0126) and to no other specific genus despite the presence of other 34 genera identified. MeHg was also related to total chlorophyll-a (total algae) (r (2) = 0.675, p = 0.0459), but relations were more significant with chlorophyte cell numbers, chlorophyll-b (chlorophytes), and chlorophyll-c (diatoms and dinoflagellates) (r (2) = 0.72, p = 0.028, r (2) = 0.744, p = 0.0214, and r (2) = 0.766, p = 0.0161 respectively). However, Oedogonium explains most variability of chlorophytes and chlorophyll-c (r (2) = 0.856, p = < 0.001 and r (2) = 0.619, p = 0.002, respectively), suggesting it is the most influential group for MeHg accumulation and periphyton algae composition at this particular location and given time.

  1. On-line method of determining utilization factor in Hg-196 photochemical separation process

    Science.gov (United States)

    Grossman, Mark W.; Moskowitz, Philip E.

    1992-01-01

    The present invention is directed to a method for determining the utilization factor [U] in a photochemical mercury enrichment process (.sup.196 Hg) by measuring relative .sup.196 Hg densities using absorption spectroscopy.

  2. Stability and diffusion 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

    The radioactive isotope $^{197m}$Hg was implanted at 60 keV with low fluences (10$^{13}$ ions/cm$^{2}$ ) into YBa$_{2}$Cu$_{3}$O$_{6+x}$ (YBCO) superconducting thin films at ISOLDE/CERN. We report on the Hg dynamics and stability inside the YBCO lattice as a function of annealing temperature up to 890 K in vacuum or O$_{2}$ atmosphere. The perturbed angular correlation (PAC) technique was used for probing the Hg behavior at the atomic scale, while by monitoring the sample's activity in situ the Hg outdiffusion was studied. We found that Hg ions occupy unique lattice sites and that Hg should be bound to two apical oxygens. Hg diffusion occurs only for annealing temperatures above 653 K, in vacuum. The Hg migration energy was estimated to be EM = 1.58 $\\pm$ 0.15 eV.

  3. The Antiproton Accumulator (AA)

    CERN Multimedia

    1980-01-01

    Section 06 - 08*) of the AA where the dispersion (and hence the horizontal beam size) is large. One can distinguish (left to right): A vacuum-tank, two bending magnets (BST06 and BST07 in blue) with a quadrupole (QDN07, in red) in between, another vacuum-tank, a wide quadrupole (QFW08) and a further tank . The tanks are covered with heating tape for bake-out. The tank left of BST06 contained the stack core pickup for stochastic cooling (see 7906193, 7906190, 8005051), the two other tanks served mainly as vacuum chambers in the region where the beam was large. Peter Zettwoch works on BST06. *) see: H. Koziol, Antiproton Accumulator Parameter List, PS/AA/Note 84-2 (1984)

  4. 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.

  5. 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.

  6. 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.

  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. 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)

  9. Phase effects in HgTe quantum structures

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, M.; Buhmann, H.; Becker, C.R.; Molenkamp, L.W. [Wuerzburg Univ. (Germany). Physikalisches Inst.

    2007-07-01

    HgTe quantum well structures with high electron mobilities have been used to fabricate quantum interference devices. Aharonov-Bohm oscillations have been studied in the low and high magnetic field regime. In the latter case a decrease of the effective ring radius is observed. Additionally, as a consequence of the strong Rashba spin-orbit coupling within this material, it was possible to observe conductance oscillations which are due to the so-called Aharonov-Casher effect. These quantum interference effects are effectively controlled by the applied magnetic and electric field. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Micromagnetic Sensors and Dirac Fermions in HgTe Heterostructures

    OpenAIRE

    Büttner, Bastian

    2012-01-01

    Within the scope of this thesis two main topics have been investigated: the examination of micromagnetic sensors and transport of massive and massless Dirac fermions in HgTe quantum wells. For the investigation of localized, inhomogeneous magnetic fields, the fabrication and characterization of two different non-invasive and ultra sensitive sensors has been established at the chair ”Experimentelle Physik” of the University of Würzburg. The first sensor is based on the young technique named micr...

  11. COMPARISON OF CHARACTERIZATION TECHNIQUES IN P-ON-N HgCdTe LWIR PHOTODIODES TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper standard techniques for characterization of HgCdTe liquid phase epitaxial layers (LPE) were presented. The performance of long wavelength p-on-n HgCdTe photodiodes fabricated by arsenic diffusion was described. The correlation between LPE HgCdTe material parameters and properties of the infrared photodiodes was demonstrated.

  12. Hg tolerance and biouptake of an isolated pigmentation yeast Rhodotorula mucilaginosa

    Science.gov (United States)

    Liu, Bing; Wang, Chaogang; Liu, Danxia; He, Ning; Deng, Xu

    2017-01-01

    A pigmented yeast R1 with strong tolerance to Hg2+ was isolated. Phylogenetic identification based on the analysis of 26S rDNA and ITS revealed R1 is a Rhodotorula mucilaginosa species. R1 was able to grow in the presence of 80 mg/L Hg2+, but the lag phase was much prolonged compared to its growth in the absence of Hg2+. The maximum Hg2+ binding capacity of R1 was 69.9 mg/g, and dead cells could bind 15% more Hg2+ than living cells. Presence of organic substances drastically reduced bioavailability of Hg2+ and subsequently decreased Hg2+ removal ratio from aqueous solution, but this adverse effect could be remarkably alleviated by the simultaneous process of cell propagation and Hg2+ biouptake with actively growing R1. Furthermore, among the functional groups involved in Hg2+ binding, carboxyl group contributed the most, followed by amino & hydroxyl group and phosphate group. XPS analysis disclosed the mercury species bound on yeast cells was HgCl2 rather than HgO or Hg0. PMID:28253367

  13. The $^{191,193}$Hg and $^{191,193}$Au positon decays

    CERN Document Server

    Vieu, C; Berg, V; Bourgeois, C

    1976-01-01

    The positron spectra emitted by /sup 191/Hg, /sup 193/Hg and their decay products were analyzed with a Gerholm-Lindskog beta spectrometer automatically operated. From the analysis of the Fermi-Kuri diagrams, the total decay energies of /sup 191,193/Hg and /sup 191,193/Au were deduced.

  14. Phosphorus accumulation and spatial distribution in agricultural soils in Denmark

    DEFF Research Database (Denmark)

    Rubæk, Gitte Holton; Kristensen, Kristian; Olesen, S E;

    2013-01-01

    Over the past century, phosphorus (P) has accumulated in Danish agricultural soils. We examined the soil P content and the degree of P saturation in acid oxalate (DPS) in 337 agricultural soil profiles and 32 soil profiles from deciduous forests sampled at 0–0.25, 0.25–0.50, 0.50–0.75 and 0.75–1....... discusses the potential importance of leaching, deep tillage, erosion and bioturbation for the observed accumulation of P in the subsoil....

  15. Transcriptome profiling and physiological studies reveal a major role for aromatic amino acids in mercury stress tolerance in rice seedlings.

    Directory of Open Access Journals (Sweden)

    Yun-An Chen

    Full Text Available Mercury (Hg is a serious environmental pollution threat to the planet. The accumulation of Hg in plants disrupts many cellular-level functions and inhibits growth and development, but the mechanism is not fully understood. To gain more insight into the cellular response to Hg, we performed a large-scale analysis of the rice transcriptome during Hg stress. Genes induced with short-term exposure represented functional categories of cell-wall formation, chemical detoxification, secondary metabolism, signal transduction and abiotic stress response. Moreover, Hg stress upregulated several genes involved in aromatic amino acids (Phe and Trp and increased the level of free Phe and Trp content. Exogenous application of Phe and Trp to rice roots enhanced tolerance to Hg and effectively reduced Hg-induced production of reactive oxygen species. Hg induced calcium accumulation and activated mitogen-activated protein kinase. Further characterization of the Hg-responsive genes we identified may be helpful for better understanding the mechanisms of Hg in plants.

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

    Science.gov (United States)

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

    2000-01-01

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

  17. 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.

  18. 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.

  19. Simulation of Small-Pitch HgCdTe Photodetectors

    Science.gov (United States)

    Vallone, Marco; Goano, Michele; Bertazzi, Francesco; Ghione, Giovanni; Schirmacher, Wilhelm; Hanna, Stefan; Figgemeier, Heinrich

    2017-09-01

    Recent studies indicate as an important technological step the development of infrared HgCdTe-based focal plane arrays (FPAs) with sub-wavelength pixel pitch, with the advantage of smaller volume, lower weight, and potentially lower cost. In order to assess the limits of pixel pitch scaling, we present combined three-dimensional optical and electrical simulations of long-wavelength infrared HgCdTe FPAs, with 3 μm, 5 μm, and 10 μm pitch. Numerical simulations predict significant cavity effects, brought by the array periodicity. The optical and electrical contributions to spectral inter-pixel crosstalk are investigated as functions of pixel pitch, by illuminating the FPAs with Gaussian beams focused on the central pixel. Despite the FPAs being planar with 100% pixel duty cycle, our calculations suggest that the total crosstalk with nearest-neighbor pixels could be kept acceptably small also with pixels only 3 μ m wide and a diffraction-limited optical system.

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

    Science.gov (United States)

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

    2011-09-01

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

  1. The Antiproton Accumulator (AA)

    CERN Multimedia

    1980-01-01

    A section of the AA where the dispersion (and hence the horizontal beam size) is large. One can distinguish (left to right): A large vacuum-tank, a quadrupole (QDN09*), a bending magnet (BST08), another vacuum-tank, a wide quadrupole (QFW08) and (in the background) a further bending magnet (BST08). The tanks are covered with heating tape for bake-out. The tank left of QDN09 contained the kickers for stochastic pre-cooling (see 790621, 8002234, 8002637X), the other one served mainly as vacuum chamber in the region where the beam was large. Peter Zettwoch works on QFW08. * see: H. Koziol, Antiproton Accumulator Parameter List, PS/AA/Note 84-2 (1984) See under 7911303, 7911597X, 8004261 and 8202324. For photos of the AA in different phases of completion (between 1979 and 1982) see: 7911303, 7911597X, 8004261, 8004608X, 8005563X, 8005565X, 8006716X, 8006722X, 8010939X, 8010941X, 8202324, 8202658X, 8203628X .

  2. 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.

  3. Incorporation of radiometric tracers in peat and implications for estimating accumulation rates

    Energy Technology Data Exchange (ETDEWEB)

    Hansson, Sophia V., E-mail: sophia.hansson@emg.umu.se [Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå (Sweden); Kaste, James M. [Geology Department, The College of William and Mary, Williamsburg, VA 23187 (United States); Olid, Carolina; Bindler, Richard [Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå (Sweden)

    2014-09-15

    Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides {sup 210}Pb, {sup 137}Cs, {sup 241}Am, and {sup 7}Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of {sup 7}Be down to 18–20 cm for some cores, and the broad vertical distribution of {sup 241}Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age–depth model leads to unrealistic peat mass accumulation rates (400–600 g m{sup −2} yr{sup −1}), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of {sup 210}Pb through the uppermost peat layers, recent peat accumulation rates (200–300 g m{sup −2} yr{sup −1}) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using {sup 7}Be, and if this information is incorporated into age–depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years. - Highlights: • {sup 210}Pb, {sup 137}Cs, {sup 241}Am and {sup 7}Be, and tot-Pb and tot Hg were measured in 5 peat cores. • Two age–depth models were applied resulting in different accumulation rates

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

    Science.gov (United States)

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

    2013-01-01

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

  5. Minority carrier lifetimes in different doped LWIR HgCdTe grown by LPE

    Science.gov (United States)

    Qiu, GuangYin; Wei, YanFeng; Sun, QuanZhi; Yang, JianRong

    2012-10-01

    The carrier lifetimes of different types of p-type doped HgCdTe(x~0.23) long wavelength infrared (LWIR) epilayers were measured which were Hg-vacancy, Au and arsenic doped ones prepared by Te-rich Liquid-phase epitaxy (LPE). By comparing the lifetimes of Hg-vacancy and extrinsic doped HgCdTe, we focus on three primary mechanisms limiting the lifetimes in these different p-type HgCdTe samples: radiative recombination, Auger recombination and Schokley-Read- Hall (SRH) Recombination. The recombination mechanism in p-type HgCdTe is the SRH recombination at low temperatures and Auger and radiative recombination at high temperature. It is found that the lifetime of As-doped and Au-doped HgCdTe is far longer than that of Hg-vacancy-doped sample which is caused by the deep energy level of the Hg-vacancy acceptor that is considered as a recombination center in HgCdTe. Also we found lifetime in those p-type doped HgCdTe LWIR epilayers is limited by SRH by comparing the experimental lifetimes with the calculated data. Impurity doping was found to have a main effect on minority carrier lifetime.

  6. Biosorption of Hg(II) onto goethite with extracellular polymeric substances.

    Science.gov (United States)

    Song, Wenjuan; Pan, Xiangliang; Mu, Shuyong; Zhang, Daoyong; Yang, Xue; Lee, Duu-Jong

    2014-05-01

    This study characterized the interactions of goethite, EPS from cyanobacterium Chroococcus sp. and Hg(II) using excitation emission matrix (EEM) spectra and adsorption isotherms. Three protein-like fluorescence peaks were noted to quench in the presence of Hg(II). The estimated conditional stability constant (logKa) and the binding constant (logKb) of the studied EPS-Hg(II) systems ranged 3.84-4.24 and 6.99-7.69, respectively. The proteins in EPS formed stable complex with Hg(II). The presence of proteins of Chroococcus sp. enhanced the adsorption capacity of Hg(II) on goethite; therefore, the goethite-EPS soil is a larger Hg(II) sink than goethite alone soil. Biosorption significantly affects the mobility of Hg(II) in goethite soils.

  7. 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.

  8. 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

  9. Terahertz photoconductivity in GaAs/AlGaAs and HgTe/HgCdTe quantum Hall devices

    Energy Technology Data Exchange (ETDEWEB)

    Stellmach, C.; Bonk, R.; Hirsch, A.; Nachtwei, G. [Institut fuer Angewandte Physik, TU Braunschweig, Mendelssohnstr. 2, 38106 Braunschweig (Germany); Vasilyev, Y.B. [Institut fuer Angewandte Physik, TU Braunschweig, Mendelssohnstr. 2, 38106 Braunschweig (Germany); A.F. Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, 194021 St. Petersburg (Russian Federation); Hein, G. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Becker, C.R. [Physikalisches Institut der Universitaet Wuerzburg, 97074 Wuerzburg (Germany)

    2006-08-15

    We present measurements of the THz photoconductivity on different quantum Hall systems. GaAs/AlGaAs and HgTe/HgCdTe (MCT) heterostructures with Hall-bar and Corbino geometry are investigated. A recipe for the preparation of metallic Corbino contacts on MCT is shown. The system is excited by the radiation of a p -Ge laser (tunable from 1.7 to 2.5 THz) and the photoresponse (PR) is measured versus the magnetic field B. We observe enhanced PR around integer filling factors (bolometric PR) and cyclotron resonance (CR) effects. Because of the lower effective mass in MCT, the CR in this system appears at a relatively low magnetic field ({approx}2 T). This is appropriate for possible applications. Finally we present time resolved measurements of the PR on the GaAs system. We find relaxation times from about 10 to over 200 ns, which depend on the geometry, the applied source-drain voltage and the on mobility of the sample. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Integrated optical fiber lattice accumulators

    OpenAIRE

    Atherton, Adam F

    1997-01-01

    Approved for public release; distribution is unlimited. Sigma-delta modulators track a signal by accumulating the error between an input signal and a feedback signal. The accumulated energy is amplitude analyzed by a comparator. The comparator output signal is fed back and subtracted from the input signal. This thesis is primarily concerned with designing accumulators for inclusion in an optical sigma-delta modulator. Fiber lattice structures with optical amplifiers are used to perform the...

  11. 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.

  12. Species-specific isotope tracers to study the accumulation and biotransformation of mixtures of inorganic and methyl mercury by the microalga Chlamydomonas reinhardtii.

    Science.gov (United States)

    Bravo, Andrea Garcia; Le Faucheur, Séverine; Monperrus, Mathilde; Amouroux, David; Slaveykova, Vera I

    2014-09-01

    The present study demonstrates that species-specific isotope tracing is an useful tool to precisely measure Hg accumulation and transformations capabilities of living organisms at concentrations naturally encountered in the environment. To that end, a phytoplanktonic green alga Chlamydomonas reinhardtii Dangeard (Chlamydomonadales, Chlorophyceae) was exposed to mixtures of (199)-isotopically enriched inorganic mercury ((199)IHg) and of (201)-isotopically enriched monomethylmercury ((201)CH3Hg) at a concentration range between less than 1 pM to 4 nM. Additionally, one exposure concentration of both mercury species was also studied separately to evaluate possible interactive effects. No difference in the intracellular contents was observed for algae exposed to (199)IHg and (201)CH3Hg alone or in their mixture, suggesting similar accumulation capacity for both species at the studied concentrations. Demethylation of (201)CH3Hg was observed at the highest exposure concentrations, whereas no methylation was detected.

  13. Distribution and air-sea exchange of mercury (Hg) in polluted marine environments

    Science.gov (United States)

    Bagnato, E.; Sprovieri, M.; Bitetto, M.; Bonsignore, M.; Calabrese, S.; Di Stefano, V.; Oliveri, E.; Parello, F.; Mazzola, S.

    2012-04-01

    Mercury (Hg) is emitted in the atmosphere by anthropogenic and natural sources, these last accounting for one third of the total emissions. Since the pre-industrial age, the atmospheric deposition of mercury have increased notably, while ocean emissions have doubled owing to the re-emission of anthropogenic mercury. Exchange between the atmosphere and ocean plays an important role in cycling and transport of mercury. We present the preliminary results from a study on the distribution and evasion flux of mercury at the atmosphere/sea interface in the Augusta basin (SE Sicily, southern Italy), a semi-enclosed marine area affected by a high degree of contamination (heavy metals and PHA) due to the oil refineries placed inside its commercial harbor. It seems that the intense industrial activity of the past have lead to an high Hg pollution in the bottom sediments of the basin, whose concentrations are far from the background mercury value found in most of the Sicily Strait sediments. The release of mercury into the harbor seawater and its dispersion by diffusion from sediments to the surface, make the Augusta basin a potential supplier of mercury both to the Mediterranean Sea and the atmosphere. Based on these considerations, mercury concentration and flux at the air-sea interface of the Bay have been estimated using a real-time atomic adsorption spectrometer (LUMEX - RA915+) and an home-made accumulation chamber, respectively. Estimated Total Atmospheric Mercury (TGM) concentrations during the cruise on the bay were in the range of 1-3 ng · m-3, with a mean value of about 1.4 ng · m-3. These data well fit with the background Hgatm concentration values detected on the land (1-2 ng · m-3, this work), and, more in general, with the background atmospheric TGM levels found in the North Hemisphere (1.5-1.7 ng · m-3)a. Besides, our measurements are in the range of those reported for other important polluted marine areas. The mercury evasion flux at the air-sea interface

  14. Multidrug efflux transporters limit accumulation of inorganic, but not organic, mercury in sea urchin embryos.

    Science.gov (United States)

    Bosnjak, Ivana; Uhlinger, Kevin R; Heim, Wesley; Smital, Tvrtko; Franekić-Colić, Jasna; Coale, Kenneth; Epel, David; Hamdoun, Amro

    2009-11-01

    Mercuric compounds are persistent global pollutants that accumulate in marine organisms and in humans who consume them. While the chemical cycles and speciation of mercury in the oceans are relatively well described, the cellular mechanisms that govern which forms of mercury accumulate in cells and why they persist are less understood. In this study we examined the role of multidrug efflux transport in the differential accumulation of inorganic (HgCl(2)) and organic (CH(3)HgCl) mercury in sea urchin (Strongylocentrotus purpuratus) embryos. We found that inhibition of MRP/ABCC-type transporters increases intracellular accumulation of inorganic mercury but had no effect on accumulation of organic mercury. Similarly, pharmacological inhibition of metal conjugating enzymes by ligands GST/GSH significantly increases this antimitotic potency of inorganic mercury, but had no effect on the potency of organic mercury. Our results point to MRP-mediated elimination of inorganic mercury conjugates as a cellular basis for differences in the accumulation and potency of the two major forms of mercury found in marine environments.

  15. Hg, Bi, Cu and Zn distribution in human teeth treated by dental amalgam measured by synchrotron microprobe

    Science.gov (United States)

    Carvalho, M. L.; Marques, J. P.; Brito, J.; Casaca, C.; Cunha, A. S.

    2002-11-01

    Human teeth restored with dental amalgam were analysed by a synchrotron microprobe to evaluate the diffusion of its major constituents, Cu, Zn and Hg, throughout the tooth structures. We measured the elemental distribution inside the tooth from the root to the enamel, specially the region around the amalgam, after its total removal. Hg is present only in restored teeth and concentration profiles show strongly increased levels of this element close to the amalgam region, reaching 500 μg g -1 in one or two cases, decreasing strongly to the inner part of the tooth. Pb concentration profiles do not seem to be affected by metallic amalgam. Very high concentrations of Bi were found in one of the restored teeth, reaching more than 2000 μg g -1, decreasing sharply to the outer regions. The distribution of Mn, Fe, Cu and Zn was also determined in order to evaluate elemental influences by amalgam components. No significant changes in elemental concentrations were detected for Mn and Fe between healthy and restored teeth. However, the levels of Zn and Cu are increased in restored teeth. An X-ray fluorescence set-up with microprobe capabilities, 100 μm of spatial resolution and an energy of 18 keV, installed at LURE synchrotron (France) was used.

  16. Hg, Bi, Cu and Zn distribution in human teeth treated by dental amalgam measured by synchrotron microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, M.L. E-mail: luisa@cii.fc.ul.pt; Marques, J.P.; Brito, J.; Casaca, C.; Cunha, A.S

    2002-11-01

    Human teeth restored with dental amalgam were analysed by a synchrotron microprobe to evaluate the diffusion of its major constituents, Cu, Zn and Hg, throughout the tooth structures. We measured the elemental distribution inside the tooth from the root to the enamel, specially the region around the amalgam, after its total removal. Hg is present only in restored teeth and concentration profiles show strongly increased levels of this element close to the amalgam region, reaching 500 {mu}g g{sup -1} in one or two cases, decreasing strongly to the inner part of the tooth. Pb concentration profiles do not seem to be affected by metallic amalgam. Very high concentrations of Bi were found in one of the restored teeth, reaching more than 2000 {mu}g g{sup -1}, decreasing sharply to the outer regions. The distribution of Mn, Fe, Cu and Zn was also determined in order to evaluate elemental influences by amalgam components. No significant changes in elemental concentrations were detected for Mn and Fe between healthy and restored teeth. However, the levels of Zn and Cu are increased in restored teeth. An X-ray fluorescence set-up with microprobe capabilities, 100 {mu}m of spatial resolution and an energy of 18 keV, installed at LURE synchrotron (France) was used.

  17. Mercury accumulation and attenuation at a rapidly forming delta with a point source of mining waste

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Bryce E., E-mail: bjohnson@ce.berkeley.edu [Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Esser, Bradley K. [Chemical Sciences Division, 7000 East Avenue, Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Whyte, Dyan C.; Ganguli, Priya M.; Austin, Carrie M. [California Regional Water Quality Control Board, 1515 Clay St., Suite 1400, Oakland, CA 94612 (United States); Hunt, James R. [Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2009-09-01

    The Walker Creek intertidal delta of Tomales Bay, California is impacted by a former mercury mine within the watershed. Eleven short sediment cores (10 cm length) collected from the delta found monomethylmercury (MMHg) concentrations ranging from 0.3 to 11.4 ng/g (dry wt.), with lower concentrations occurring at the vegetated marsh and upstream channel locations. Algal mats common to the delta's sediment surface had MMHg concentrations ranging from 7.5 to 31.5 ng/g, and the top 1 cm of sediment directly under the mats had two times greater MMHg concentrations compared to adjacent locations without algal covering. Spatial trends in resident biota reflect enhanced MMHg uptake at the delta compared to other bay locations. Eighteen sediment cores, 1 to 2 m deep, collected from the 1.2 km{sup 2} delta provide an estimate of a total mercury (Hg) inventory of 2500 {+-} 500 kg. Sediment Hg concentrations ranged from pre-mining background conditions of approximately 0.1 {mu}g/g to a post-mining maximum of 5 {mu}g/g. Sediment accumulation rates were determined from three sediment cores using measured differences of {sup 137}Cs activity. We estimate a pre-mining Hg accumulation of less than 20 kg/yr, and a period of maximum Hg accumulation in the 1970s and 1980s with loading rates greater than 50 kg/yr, corresponding to the failure of a tailings dam at the mine site. At the time of sampling (2003) over 40 kg/yr of Hg was still accumulating at the delta, indicating limited recovery. We attribute observed spatial evolution of elevated Hg levels to ongoing inputs and sediment re-working, and estimate the inventory of the anthropogenic fraction of total Hg to be at least 1500 {+-} 300 kg. We suggest ongoing sediment inputs and methylation at the deltaic surface support enhanced mercury levels for resident biota and transfer to higher trophic levels throughout the Bay.

  18. Accumulation of some metals in muscles of five fish species from lower Nitra river.

    Science.gov (United States)

    Andreji, Jaroslav; Stránai, Ivan; Massányi, Peter; Valent, Miroslav

    2006-01-01

    This paper reports the results of accumulated selected metals concentrations (Fe, Mn, Zn, Cu, Ni, Co, Cr, Pb, Cd, Hg and meHg) in the muscle of five common Slovak fish species (Chub-Leuciscus cephalus, Common carp-Cyprinus carpio, Prussian carp-Carassius gibelio, Roach-Rutilus rutilus, and Wels catfish-Silurus glanis). Furthermore, correlations among the selected metals and order of metal accumulation in the fish muscle were determined. The concentrations of metals (mg/kg wet weight basis) ranged as follows: Fe 3.70-21.10; Mn 0.27-1.50; Zn 3.72-42.82; Cu 0.26-1.82; Ni 0.02-0.29; Co 0.06-0.28; Cr 0.09-0.28; Pb 0.08-34.59; Cd 0.06-2.76, Hg 0.34-3.64 and meHg 0.08-1.20. The level of lead and mercury exceeded the maximum allowed concentration in Slovakia by the Codex Alimentarius for safe human consumption (0.2 and 0.5 mg/kg, respectively) in the majority of samples (94.6 and 82.1%, respectively). Content of Cd (0.88 +/- 0.76 mg/kg wet weight) in the fish muscle exceeded maximum allowed levels (0.05 mg/kg) in all samples. An average, the order of metal concentrations in the fish muscle was: Fe > Zn > Pb > Cd > Hg > Cu > Mn > meHg > Ni > Cr > Co.

  19. Lifetimes of an excited superdeformed band in {sup 192}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Blumenthal, D.; Carpenter, M.P. [and others

    1995-08-01

    An excited superdeformed band was identified in {sup 192}Hg and the lifetimes of its levels measured with the Doppler-shift attenuation method from data taken with the Eurogam spectrometer. The band is proposed to be based on the two-quasineutron (v[642]3/2 [512]5/2) configuration, which after a band crossing, becomes the (v[642]3/2 [752]5/2) configuration. The transition quadrupole moment Q{sub t} of the excited band is the same as that of the yrast SD band, within experimental errors. This suggests that the deformation of the SD minimum is robust with respect to quasiparticle excitation, despite the occupation of the deformation-driving v[752]5/2 level (from the j{sub 15/2} shell) after the band crossing.

  20. [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.

  1. Archaic introjects and the cosmology of H.G. Wells.

    Science.gov (United States)

    Parkin, A

    1982-01-01

    The roles of the archaic loving and hating introjects are traced in the early scientific romances and the life work of H.G. Wells. The preambivalent polarization of the early loving introjects of an archaic ego ideal (giving rise to utopian fantasies and, later, to promulgations of a new world state) and the early hostile introjects of an archaic superego (giving rise to fears of death and, later, to fears of cosmic dissolution) is represented in eschatological preoccupations with death, the Last Judgment, heaven and hell. These religious preoccupations are derivatives of wishes for maternal union and bliss on the one hand, and of castration anxiety and fears of personal annihilation on the other. Further transformations of the archaic introjects are traced through an indentification with the role of redeemer, and later, through his scientific studies, to an espousal of T.H. Huxley's teachings of organic evolution and to the development of cosmological themes in his work.

  2. Accumulation of trace metals by aquatic macrophytes and their possible use in phytoremediation techniques

    Directory of Open Access Journals (Sweden)

    Michaela Hillermannová

    2008-01-01

    Full Text Available The aim of the performed research was to obtain knowledge on the ability of aquatic plants naturally growing at a site to absorb trace metals contained in bottom sediments and surface water. Furthermore, we compared differences in the accumulation of trace metals by the individual groups of aquatic plants (submerged and emergent and assessed a possible use of the individual plant species in phytoremediation techniques. Representative samples of water, sediments and aquatic macrophytes were taken from three anthropogenically loaded streams in six monitoring cycles in several collection profiles differing in the distance from a source of contamination. The samples were analysed for the total content of selected trace metals (As, Cd, Pb, Al, Hg, Zn, Fe, Mn, Cr, Ni and Cu. For comparison, one profile at an unloaded site was sampled as well. The obtained results were subjected to multivariate statistical analysis of data. Increased contents of Fe, Al, Mn, Cr and Zn were detected in sediments and plant biomass at loaded sites, namely 2–3× higher than at the comparing site. The contents of metals in surface water samples were altogether below the detection limit of the analytical method. When evaluating the individual plant species, we can state that the lowest contents of metals were detected in shore species (reed canary grass Phalaroides arundinacea, wood club-rush Scirpus silvaticus and red dock Rumex aquaticus; plant species growing in the very water current (water star-wort Callitriche sp. and flote-grass Glyceria fluitans exhibited mean contents of metals. In species forming mats (Fontinalis antipyretica and Cladophora sp., these contents were several times higher as compared to the previous species. The results of the performed research show that one of important factors, which influence the accumulation of trace metals in plants, is their ecological group (emergent – submerged affiliation and the species classification within this group

  3. Erosion, sediment transportation and accumulation in rivers

    Institute of Scientific and Technical Information of China (English)

    N.I.ALEKSEEVSKIY; K.M.BERKOVICH; R.S.CHALOV

    2008-01-01

    The present paper analyses the interrelation between erosion,sediment transportation and accumulation proposed by N.I.Makkaveyev (1908-1983) and its further development in modem studies of river channel processes in Russia.Spatio-temporal linkages between erosion and accumulation are defined considering channel processes at different scales - river longitudinal profile,channel morphological patterns,alluvial bedforms (bars,dunes) and individual sediment particles.Relations between river geomorphic activity,flow transportation capacity and sediment budgets are established (sediment input and output;channel bed erosion and sediment entrainment into flow -termination of sediment transport and its deposition).Channel planforms,floodplain segments separated by the latter and alluvial channel bedforms are shown to be geomorphic expressions of sediment transport process at different spatial and temporal scales.This paper is dedicated to the 100th anniversary of N.I.Makkaveyev,Professor of the Moscow State University,author of the book "River channel and erosion in its basin" (1955).That book is regarded in Russia as the pioneering work which initiated the complex hydrological and geographical studies of channel processes and laid a basis for the theory of unified fluvial erosion-accumulation process.

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

    Science.gov (United States)

    Filippelli, G. M.

    2016-12-01

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

  5. Beryllium-7 and lead-210 chronometry of modern soil processes: The Linked Radionuclide aCcumulation model, LRC

    Science.gov (United States)

    Landis, Joshua D.; Renshaw, Carl E.; Kaste, James M.

    2016-05-01

    Soil systems are known to be repositories for atmospheric carbon and metal contaminants, but the complex processes that regulate the introduction, migration and fate of atmospheric elements in soils are poorly understood. This gap in knowledge is attributable, in part, to the lack of an established chronometer that is required for quantifying rates of relevant processes. Here we develop and test a framework for adapting atmospheric lead-210 chronometry (210Pb; half-life 22 years) to soil systems. We propose a new empirical model, the Linked Radionuclide aCcumulation model (LRC, aka "lark"), that incorporates measurements of beryllium-7 (7Be; half-life 54 days) to account for 210Pb penetration of the soil surface during initial deposition, a process which is endemic to soils but omitted from conventional 210Pb models (e.g., the Constant Rate of Supply, CRS model) and their application to sedimentary systems. We validate the LRC model using the 1963-1964 peak in bomb-fallout americium-241 (241Am; half-life of 432 years) as an independent, corroborating time marker. In three different soils we locate a sharp 241Am weapons horizon at disparate depths ranging from 2.5 to 6 cm, but with concordant ages averaging 1967 ± 4 via the LRC model. Similarly, at one site contaminated with mercury (HgT) we find that the LRC model is consistent with the recorded history of Hg emission. The close agreement of Pb, Am and Hg behavior demonstrated here suggests that organo-metallic colloid formation and migration incorporates many trace metals in universal soil processes and that these processes may be described quantitatively using atmospheric 210Pb chronometry. The 210Pb models evaluated here show that migration rates of soil colloids on the order of 1 mm yr-1 are typical, but also that these rates vary systematically with depth and are attributable to horizon-specific processes of leaf-litter decay, eluviation and illuviation. We thus interpret 210Pb models to quantify (i) exposure

  6. Heavy metal accumulation and toxicity in smoothhound (Mustelus mustelus) shark from Langebaan Lagoon, South Africa.

    Science.gov (United States)

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

    2016-01-01

    Together with several health benefits, fish meat could introduce toxins to consumers in the form of heavy metal contaminants. High levels of mercury (Hg), especially, are frequently detected in certain predatory fish species. Mustelus mustelus fillets were analysed for 16 metals and three individual Hg species (inorganic Hg, ehtylmercury, methylmercury) with inductively coupled plasma mass spectrometry (ICP-MS) and HPLC-ICP-MS respectively. Eleven of the 30 sharks had total Hg levels above the maximum allowable limit with toxic methylmercury found as the dominant mercury species with a strong correlation (r = 0.97; p mercury concentrations. Limited correlations between metals and shark size parameters were observed; therefore metal accumulation in M. mustelus is mostly independent of size/age. Average values for arsenic (28.31 ± 18.79 mg/kg) exceed regulatory maximum limits and Hg (0.96 ± 0.69 mg/kg) is close to the maximum limit with all other metals well below maximum limits.

  7. 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

    2015-01-01

    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 199Hg 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. PMID:26644634

  8. Lipid Profile

    Science.gov (United States)

    ... AACC products and services. Advertising & Sponsorship: Policy | Opportunities Lipid Profile Share this page: Was this page helpful? Also ... as: Lipid Panel; Coronary Risk Panel Formal name: Lipid Profile Related tests: Cholesterol ; HDL Cholesterol ; LDL Cholesterol ; Triglycerides ; ...

  9. Exposure to Low Dose of Cinnabar (a Naturally Occurring Mercuric Sulfide (HgS Caused Neurotoxicological Effects in Offspring Mice

    Directory of Open Access Journals (Sweden)

    Chun-Fa Huang

    2012-01-01

    Full Text Available Cinnabar, a naturally occurring mercuric sulfide (HgS, has long been used in Chinese mineral medicine for more than 2000 years. Although mercury is well-known for its toxicity, whether cinnabar induces neurotoxicity, especially in infants and children, is unknown. The purpose of this study was to explore the neurotoxic effects of low-dose of cinnabar (10 mg/kg/day on developing mice. The results revealed neurobehavioral defects in F1-C-Cin group, which were associated with Hg accumulation, increased NOx levels in whole blood, and Na+/K+-ATPase activities in brain tissues. F1- and F2-Cin-V groups were found to increase brain Hg contents and prominent neurobehavioral defects compared with F1-C-V group, suggesting that the fetal brain was more susceptible to irreversible effects for cinnabar-induced damage. Moreover, F1- and F2-Cin-Cin groups had severely neurobehavioral dysfunctions, closely correlated with the further alteration of NOx levels and Na+/K+-ATPase activities than F1- and F2-C-Cin groups. Effects in F2-Cin-Cin group were more significant than those in F1-Cin-Cin group. In conclusion, this study demonstrates that exposure to low-dose of cinnabar during the perinatal and developmental stages results in irreversible and severe injuries of the neurotoxicity in offspring, and NOx and Na+/K+-ATPase activities may exist potential and useful biomarkers for neurotoxicity-induced by low-doses of mercuric compounds.

  10. HgTe/CdHgTe double quantum well with a spectrum of bilayer graphene and peculiarities of its magnetotransport

    Science.gov (United States)

    Yakunin, M. V.; Krishtopenko, S. S.; Podgornykh, S. M.; Popov, M. R.; Neverov, V. N.; Mikhailov, N. N.; Dvoretsky, S. A.

    2016-09-01

    The quantum Hall effect (QHE) in a HgTe/CdHgTe double quantum well (DQW) with a tunneling-transparent barrier and the energy spectrum resembling the band structure of bilayer graphene has been investigated. An experimental manifestation of a tunnel gap between the states of light carriers seen as a magnetoresistance (MR) peak in the in-plane magnetic field has been discovered. An unusual structure of the QHE has been observed in a sample with hole conductivity: there is a pronounced peak on a plateau with the number i = 2 and the slopes of this anomalous peak correspond to two peaks of the longitudinal MR. On the other hand, a stable 2-1 plateau-plateau transition has been observed in much higher fields with the position of this transition corresponding to a considerably higher hole density than follows from the pattern of the QHE in weak fields. The anomalous peak is interpreted as a reentrant QHE between the 2-1-2 states. The position of the anomalous peak is immune to IR illumination and the tilting angle of the magnetic field, although these factors strongly affect its amplitude. According to comparison with the calculated structure of magnetic levels, the anomalous peak is attributed to crossing of electron-like and hole-like levels in the valence band. The difference between the hole densities found in weak field and from the 2-1 transition in strong fields is attributed to the effects of redistribution of holes between the localized states in sideband maxima of the valence subband and the ones delocalized in the overlapping levels of light holes.

  11. Data Profiling

    OpenAIRE

    Hladíková, Radka

    2010-01-01

    Title: Data Profiling Author: Radka Hladíková Department: Department of Software Engineering Supervisor: Ing. Vladimír Kyjonka Supervisor's e-mail address: Abstract: This thesis puts mind on problems with data quality and data profiling. This Work analyses and summarizes problems of data quality, data defects, process of data quality, data quality assessment and data profiling. The main topic is data profiling as a process of researching data available in existing...

  12. 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.

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

    Science.gov (United States)

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

    2015-01-01

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

  14. Micromagnetic sensors and Dirac fermions in HgTe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Bastian

    2012-08-06

    Within the scope of this thesis two main topics have been investigated: the examination of micromagnetic sensors and transport of massive and massless Dirac fermions in HgTe quantum wells. For the investigation of localized, inhomogeneous magnetic fields, the fabrication and characterization of two different non-invasive and ultra sensitive sensors has been established at the chair ''Experimentelle Physik'' of the University of Wuerzburg. The first sensor is based on the young technique named micro-Hall magnetometry. The necessary semiconductor devices (Hall cross structures) were fabricated by high-resolution electron beam lithography based on two different two dimensional electron gases (2DEGs), namely InAs/(Al,Ga)Sb- and HgTe/(Hg,Cd)Te-heterostructures. The characteristics have been examined in two different ways. Measurements in homogeneous magnetic fields served for characterization of the sensors, whereas the investigation of artificially produced sub-{mu}m magnets substantiates the suitability of the devices for the study of novel nanoscale magnetic materials (e.g. nanowires). Systematic experiments with various magnets are in accordance with the theory of single-domain particles and anisotropic behavior due to shapes with high aspect ratio. The highest sensitivity for strongly localized fields was obtained at T=4.2 K for a (200.200) nm{sup 2} Hall cross - made from shallow, high mobility HgTe 2DEG. Although the field resolution was merely {delta}B{approx}100 {mu}T, the nanoscale sensor size yields an outstanding flux resolution of {delta}{Phi}=2.10{sup -3} {Phi}{sub 0}, where {Phi}{sub 0}=h/2e is the flux quantum. Translating this result in terms of magnetic moment, the sensitivity allows for the detection of magnetization changes of a particle centered on top of the sensor as low as {delta}M{approx}10{sup 2} {mu}{sub B}, with the magnetic moment of a single electron {mu}{sub B}, the Bohr magneton. The further examination of a permalloy

  15. Micromagnetic sensors and Dirac fermions in HgTe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Bastian

    2012-08-06

    Within the scope of this thesis two main topics have been investigated: the examination of micromagnetic sensors and transport of massive and massless Dirac fermions in HgTe quantum wells. For the investigation of localized, inhomogeneous magnetic fields, the fabrication and characterization of two different non-invasive and ultra sensitive sensors has been established at the chair ''Experimentelle Physik'' of the University of Wuerzburg. The first sensor is based on the young technique named micro-Hall magnetometry. The necessary semiconductor devices (Hall cross structures) were fabricated by high-resolution electron beam lithography based on two different two dimensional electron gases (2DEGs), namely InAs/(Al,Ga)Sb- and HgTe/(Hg,Cd)Te-heterostructures. The characteristics have been examined in two different ways. Measurements in homogeneous magnetic fields served for characterization of the sensors, whereas the investigation of artificially produced sub-{mu}m magnets substantiates the suitability of the devices for the study of novel nanoscale magnetic materials (e.g. nanowires). Systematic experiments with various magnets are in accordance with the theory of single-domain particles and anisotropic behavior due to shapes with high aspect ratio. The highest sensitivity for strongly localized fields was obtained at T=4.2 K for a (200.200) nm{sup 2} Hall cross - made from shallow, high mobility HgTe 2DEG. Although the field resolution was merely {delta}B{approx}100 {mu}T, the nanoscale sensor size yields an outstanding flux resolution of {delta}{Phi}=2.10{sup -3} {Phi}{sub 0}, where {Phi}{sub 0}=h/2e is the flux quantum. Translating this result in terms of magnetic moment, the sensitivity allows for the detection of magnetization changes of a particle centered on top of the sensor as low as {delta}M{approx}10{sup 2} {mu}{sub B}, with the magnetic moment of a single electron {mu}{sub B}, the Bohr magneton. The further examination of a permalloy

  16. Incorporation of radiometric tracers in peat and implications for estimating accumulation rates.

    Science.gov (United States)

    Hansson, Sophia V; Kaste, James M; Olid, Carolina; Bindler, Richard

    2014-09-15

    Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides (210)Pb, (137)Cs, (241)Am, and (7)Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of (7)Be down to 18-20 cm for some cores, and the broad vertical distribution of (241)Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age-depth model leads to unrealistic peat mass accumulation rates (400-600 g m(-2) yr(-1)), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of (210)Pb through the uppermost peat layers, recent peat accumulation rates (200-300 g m(-2) yr(-1)) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using (7)Be, and if this information is incorporated into age-depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years.

  17. 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.

  18. Cd, Pb and Hg Biomonitoring in Fish of the Mediterranean Region and Risk Estimations on Fish Consumption

    Directory of Open Access Journals (Sweden)

    Elisavet A. Renieri

    2014-08-01

    Full Text Available Cadmium (Cd, lead (Pb and mercury (Hg are toxic metals with increasing interest due to their tendency to bioaccumulate in fish tissue which may pose a threat to human health via fish consumption. This review of the recent literature on Cd, Pb, Hg levels summarizes data of fish biomonitoring studies in the Mediterranean Sea in order to determine potential risks due to dietary intake of metals. The analytical methods applied are described, with Atomic Absorption Spectroscopy and Inductively Coupled Plasma Mass Spectroscopy being the most popular. Most of the literature reviewed is focused on the Eastern Mediterranean. Results from the studies indicate that metals mostly accumulate in liver, followed by muscle. Although there are few studies reporting metal levels in fish exceeding the maximum residue levels (MRLs, the bulk of the studies cite levels below the MRLs. The hazard index (HI of fish consumption, namely the ratio of estimated weekly intake to provisional tolerable weekly intake (EWI/PTWI was estimated for adult consumers and no risk emerged. The EWI/PTWI ratios of lead and mercury for Italy (0.14 and 0.22 respectively represent the highest HI levels estimated. In view of maximizing the benefits while minimizing the risks of fish consumption, a more detailed fish-specific database on intakes for consumers is required and extended bimonitoring in as many regions as possible.

  19. 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.

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

    Science.gov (United States)

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

    2015-11-01

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

  1. 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.

  2. Topically applied ceramide accumulates in skin glyphs

    Science.gov (United States)

    Zhang, Qihong; Flach, Carol R; Mendelsohn, Richard; Mao, Guangru; Pappas, Apostolos; Mack, M Catherine; Walters, Russel M; Southall, Michael D

    2015-01-01

    Ceramides (CERs), structural components of the stratum corneum (SC), impart essential barrier properties to this thin outer layer of the epidermis. Variations in CER species within this layer have been linked to several skin diseases. A recent proliferation of CER-containing topical skin-care products warrants the elucidation of CER penetration profiles in both healthy and diseased skin. In the current study, the spatial distributions of CER concentration profiles, following topical application of two species of CER, were tracked using infrared imaging. Suspensions of single-chain perdeuterated sphingosine and phytosphingosine CER in oleic acid were applied, in separate experiments, to the surface of healthy intact ex vivo human skin using Franz diffusion cells. Following either a 24- or 48-hour incubation period at 34°C, infrared images were acquired from microtomed skin sections. Both CER species accumulated in glyph regions of the skin and penetrated into the SC, to a limited extent, only in these regions. The concentration profiles observed herein were independent of the CER species and incubation time utilized in the study. As a result, a very heterogeneous, sparse, spatial distribution of CERs in the SC was revealed. In contrast, oleic acid was found to be fairly homogeneously distributed throughout the SC and viable epidermis, albeit at lower concentrations in the latter. A more uniform, lateral distribution of CERs in the SC would likely be important for barrier efficacy or enhancement. PMID:26170709

  3. Some health physics aspects of working with 203Hg in university research.

    Science.gov (United States)

    Belanger, M; Westin, A; Barfuss, D W

    2001-02-01

    The radioisotope 203Hg is used in university toxicology research experiments. When our commercial vendor ceased the production of the high specific activity 203Hg we required, an alternative source was sought. Other commercial sources were investigated without success leaving the synthesis of this radioisotope to us. This paper outlines the method we used to synthesize 203Hg and provides a summary of our results to date and a discussion of our experiences.

  4. Viscosity Relaxation in Molten HgZnTe

    Science.gov (United States)

    Baird, James K.

    2002-01-01

    Because of its narrow electronic band-gap, HgZnTe solid solutions have been proposed as effective detectors for infrared radiation. To produce the best single crystals of these materials for this application, knowledge of the phase diagram that governs the freezing of the liquid is essential. Besides the phase diagram, however, some information concerning the thermophysical properties of the melt, such as viscosity, density, specific heat, and enthalpy of mixing, can also be useful. Of these thermophysical properties, the viscosity is perhaps of the most interest scientifically. Measurements using the oscillating cup method have shown that the isothermal melt requires tens of hours of equilibration time before a steady value of the viscosity can be achieved. Over this equilibration time, which depends upon temperature, the viscosity can increase by as much as a factor of two before reaching a steady state. We suggest that this relaxation phenomenon may be due to a slight polymerization of Te atoms in the melt. To account for the time dependence of the viscosity in the HgZnTe melt, we propose that the liquid acts as a solvent that favors the formation of Te atom chains. We suggest that as the melt is cooled from a high temperature to the temperature for measurement of the viscosity, a free radical polymerization of Te atoms begins. To estimate this average molecular weight, we use a simple free radical polymerization mechanism, including a depolymerization step, to calculate the time dependence to the concentration of each Te polymer molecular weight fraction. From these molecular weight fractions, we compute the weight average molecular weight of the distribution. Using the semi-empirical relation between average molecular weight and viscosity, we obtain a formula for the time dependence of the viscosity of the melt. Upon examining this formula, we find that the viscosity achieves a steady value when a balance is achieved between the rate of formation of the chains

  5. 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.

  6. Accumulation Pattern of Heavy Metals in Chromolaena odorata (L. King & Robins. Grown in Nutrient Solution and Soil

    Directory of Open Access Journals (Sweden)

    Swapna K.S.

    2014-05-01

    Full Text Available Accumulation pattern of Al, Cd, Fe, Hg, Cr, Cu, Pb, Ni and Zn in Chromolaena odorata plants grown in Hoagland nutrient solution and soil contaminated with known quantities of the above said metals was investigated. Significant variations in the quantity of accumulation as well as distribution among plant parts like root, stem and leaf were shown between the metals. Accumulation of Pb was maximum in the root followed by Fe and Al. Maximum quantity of each metal was accumulated in the root as compared to stem and leaf. Drastic differences in the accumulation pattern of metals between the nutrient solution and soil culture was observed. Comparatively small quantity of metal was accumulated in the plants of soil despite several fold quantity of each metal was given. The results are discussed in terms of BCF, TF, metal specificity as well as detoxification mechanisms.

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

    Science.gov (United States)

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

    2017-06-01

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

  8. 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.

  9. Design of a peptidic turn with high affinity for HgII

    DEFF Research Database (Denmark)

    Pires, Sara; Habjanic, Jelena; Sezer, Murat

    2012-01-01

    A four amino acid peptide containing the ß-turn template dPro-Pro in the middle and two cysteines (Cys) in the terminal positions (CdPPC) has been synthesized and its mercury(II) coordination properties studied using different spectroscopic methods. The UV-vis, CD, (199m)Hg PAC, and Raman...... spectroscopic studies indicate the binding of Hg(II) to the two Cys, forming the dithiolatemercury(II) complex Hg(CdPPC). Electrospray ionization mass spectrometry corroborates the 1:1 complex formation. A log K = 40.0 was determined for the formation constant of the Hg(CdPPC) complex using competition...

  10. Rezension zu: Emily Teeter (Hg.), Before the pyramids. The origins of Egyptian civilization

    OpenAIRE

    Köpp-Junk, Heidi

    2013-01-01

    Rezension zu: Emily Teeter (Hg.), Before the Pyramids. The Origins of Egyptian Civilization. The Oriental Institute of the University of Chicago, Oriental Institute Museum Publications 33 (Chicago 2011)

  11. 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.

  12. Local chemical composition of HgBaCaCuO high-temperature superconductors

    Science.gov (United States)

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

    1994-07-01

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

  13. HgCdTe detector technology at Kunming Institute of Physics

    Science.gov (United States)

    Su, Junhong; Zeng, Gehong

    1996-09-01

    HgCdTe detector and thermal image system laboratories at Kunming Institute of Physics have been carrying the research and development of HgCdTe detectors and thermal imaging systems for a wide range applications for over 20 years. During this period, significant progress has been made in many areas such as HgCdTe material, detector, miniature dewar and cooler to meet the requirements of civil and military operations. This paper describes these activities and present status of HgCdTe technology at Kunming Institute of Physics, and some of the problems we faced and how they were solved.

  14. Combined in-beam electron and gamma-ray spectroscopy of (184,186)Hg

    CERN Document Server

    Scheck, M; Rahkila, P; Butler, P A; Larsen, A C; Sandzelius, M; Scholey, C; Carrol, R J; Papadakis, P; Jakobsson, U; Grahn, T; Joss, D T; Watkins, H V; Juutinen, S; Bree, N; Cox, D; Huyse, M; Uusitalo, J; Leino, M; Ruotsalainen, P; Nieminen, P; Srebrny, J; Van Duppen, P; Herzan, A; Greenlees, P T; Julin, R; Herzberg, R D; Hauschild, K; Pakarinen, J; Page, R D; Peura, P; Gaffney, L P; Kowalczyk, M; Rinta-Antila, S; Saren, J; Lopez-Martens, A; Sorri, J; Ketelhut, S

    2011-01-01

    By exploiting the SAGE spectrometer a simultaneous measurement of conversion electrons and gamma rays emitted in the de-excitation of excited levels in the neutron-deficient nuclei (184,186)Hg was performed. The light Hg isotopes under investigation were produced using the 4n channels of the fusion-evaporation reactions of (40)Ar and (148,150)Sm. The measured K- and L-conversion electron ratios confirmed the stretched E2 nature of several transitions of the yrast bands in (184,186)Hg. Additional information on the E0 component of the 2(2)(+) -> 2(1)(+) transition in (186)Hg was obtained.

  15. Karolinske psychodynamic profile (KAPP)

    DEFF Research Database (Denmark)

    Mathiesen, Birgit Bork; Søgaard, Ulf

    2006-01-01

    psykologiske testmetoder, assesment, Karolinska psychodynamic profile (KAPP), psykodynamisk profil......psykologiske testmetoder, assesment, Karolinska psychodynamic profile (KAPP), psykodynamisk profil...

  16. Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements in $^{184,186}$Hg and two-state mixing calculations

    CERN Document Server

    Gaffney, L P; Page, R.D.; Grahn, T.; Scheck, M.; Butler, P.A.; Bertone, P.F.; Bree, N.; Carroll, R.J.; Carpenter, M.P.; Chiara, C.J.; Dewald, A.; Filmer, F.; Fransen, C.; Huyse, M.; Janssens, R.V.F.; Joss, D.T.; Julin, R.; Kondev, F.G.; Nieminen, P.; Pakarinen, J.; Rigby, S.V.; Rother, W.; Van Duppen, P.; Watkins, H.V.; Wrzosek-Lipska, K.; Zhu, S.

    2014-01-01

    The neutron-deficient mercury isotopes, $^{184,186}$Hg, were studied with the Recoil Distance Doppler Shift (RDDS) method using the Gammasphere array and the K\\"oln Plunger device. The Differential Decay Curve Method (DDCM) was employed to determine the lifetimes of the yrast states in $^{184,186}$Hg. An improvement on previously measured values of yrast states up to $8^{+}$ is presented as well as first values for the $9_{3}$ state in $^{184}$Hg and $10^{+}$ state in $^{186}$Hg. $B(E2)$ values are calculated and compared to a two-state mixing model which utilizes the variable moment of inertia (VMI) model, allowing for extraction of spin-dependent mixing strengths and amplitudes.

  17. Can graphene make better HgCdTe infrared detectors?

    Directory of Open Access Journals (Sweden)

    Shi Yanli

    2011-01-01

    Full Text Available Abstract We develop a simple and low-cost technique based on chemical vapor deposition from which large-size graphene films with 5-10 graphene layers can be produced reliably and the graphene films can be transferred easily onto HgCdTe (MCT thin wafers at room temperature. The proposed technique does not cause any thermal and mechanical damages to the MCT wafers. It is found that the averaged light transmittance of the graphene film on MCT thin wafer is about 80% in the mid-infrared bandwidth at room temperature and 77 K. Moreover, we find that the electrical conductance of the graphene film on the MCT substrate is about 25 times larger than that of the MCT substrate at room temperature and 77 K. These experimental findings suggest that, from a physics point of view, graphene can be utilized as transparent electrodes as a replacement for metal electrodes while producing better and cheaper MCT infrared detectors.

  18. ROIC for HgCdTe e-APD FPA

    Science.gov (United States)

    Chen, Guoqiang; Zhang, Junling; Wang, Pan; Zhou, Jie; Gao, Lei; Ding, Ruijun

    2013-08-01

    Ultra-low light imaging and passive/active dual mode imaging require very low noise optical receivers to achieve detection of fast and weak optical signal. HgCdTe electrons initiated avalanche photodiodes (e-APDs) in linear multiplication mode is the detector of choice thanks to its high quantum efficiency, high gain at low bias, high bandwidth and low noise factor. In my work, a passive/active dual mode readout integrated circuit (ROIC) of e-APD focal plane array (FPA) is designed. Unit cell circuit architecture of ROIC includes a capacitance feedback transimpedance amplifier (CTIA) as preamplifier of ROIC, a high voltage protection module, a comparator, a Sample-Hold circuit module, and output driver stage. There is a protection module in every unit cell circuit which can avoid ROIC to be damaged from avalanche breakdown of some diodes of detector. Conventional 5V CMOS process is applied to implement the high voltage protection with the small area rather than Laterally Diffused Metal Oxide Semiconductor (LDMOS) in high voltage BCD process in the limited 100um×100um pitch area. In CTIA module, three integration capacitances are included in the CTIA module, two of them are switchable to provide different well capacity and noise. Constraints such as pixel area, stability and power lead us design toward a simple one-stage cascade operational transconductance amplifier (OTA) as pre-amplifier. High voltage protection module can protect ROIC to be damaged because of breakdown of some avalanche diodes.

  19. Comparison of carotenoid accumulation and biosynthetic gene expression between Valencia and Rohde Red Valencia sweet oranges

    Science.gov (United States)

    Carotenoid accumulation and biosynthetic gene expression levels during fruit maturation were compared between ordinary Valencia (VAL) and its more deeply colored mutant Rohde Red Valencia orange (RRV). The two cultivars exhibited different carotenoid profiles and regulatory mechanisms in flavedo and...

  20. Manganese As a Metal Accumulator

    Science.gov (United States)

    Manganese deposits in water distribution systems accumulate metals, radionuclides and oxyanions by a combination of surface complexation, adsorption and solid substitution, as well as a combination of oxidation followed by manganese reduction and sorption of the oxidized constitu...

  1. Manganese As a Metal Accumulator

    Science.gov (United States)

    Manganese deposits in water distribution systems accumulate metals, radionuclides and oxyanions by a combination of surface complexation, adsorption and solid substitution, as well as a combination of oxidation followed by manganese reduction and sorption of the oxidized constitu...

  2. Investigation of magnetoabsorption at different temperatures in HgTe/CdHgTe quantum-well heterostructures in pulsed magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Platonov, V. V.; Kudasov, Yu. B.; Makarov, I. V.; Maslov, D. A.; Surdin, O. M. [Sarov Physical–Technical Institute—National Research Nuclear University MEPhI (Russian Federation); Zholudev, M. S.; Ikonnikov, A. V.; Gavrilenko, V. I. [Russian Academy of Sciences, Institute of Physics of Microstructures (Russian Federation); Mikhailov, N. N.; Dvoretsky, S. A. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2015-12-15

    The magnetoabsorption in magnetic fields as high as 40 T is investigated at T > 77 K in HgTe/CdHgTe quantum-well heterostructures (d{sub QW} ≈ 8 nm). The spectra reveal two lines associated both with intraband transition from the lower Landau level in the conduction band and with interband transition. It is shown that the band structure in these systems changes from inverted to normal with increasing temperature.

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

    OpenAIRE

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

    2014-01-01

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

  4. 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

  5. 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...

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

    Science.gov (United States)

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

    2015-02-03

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

  7. A DFT based analysis of adsorption of Hg(2+) ion on chitosan monomer and its citralidene and salicylidene derivatives: Prior to the removal of Hg toxicity.

    Science.gov (United States)

    Hassan, Basila; Rajan, Vijisha K; Mujeeb, V M Abdul; K, Muraleedharan

    2017-03-07

    A Density functional theory based study of adsorption of the toxic metal Hg (II) ion by chitosan monomer and two of its derivatives; citralidene and salicylidene chitosan, has been performed. The effect of structural features on the stability of studied complexes has been analyzed by using Gaussian03 software package. All the possible conformations of these adsorbents were studied using the global minimum geometries. All the adsorbing sites were studied by placing the metal ion on the centroid of the atoms and the stable conformer of the adsorbent-metal ion complex was identified. Interaction between Hg (II) and the adsorbents is found to be electrostatic. Metal ion binding with nitrogen atom is stronger than that with oxygen atoms in all the cases as the charge density of nitrogen is enhanced on Schiff base formation. The advantage of derivatives over chitosan monomer is their stability in acidic media. ΔE value of the complexes are in the order SC-Hg (II)>chitosan-Hg (II)>CC-Hg (II) which indicates that the stability of complexes increases with increase in energy gap. The study reveals that aromatic Schiff base derivatives of chitosan is better for Hg(II) intake than aliphatic derivatives.

  8. 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

  9. Enhanced circular photogalvanic effect in HgTe quantum wells in the heavily inverted regime

    Science.gov (United States)

    Li, Jun; Yang, Wen; Liu, Jiang-Tao; Huang, Wei; Li, Cheng; Chen, Song-Yan

    2017-01-01

    HgTe-based quantum wells (QWs) possess very strong spin-orbit interaction (SOI) and have become an ideal platform for the study of fundamental SOI-dependent phenomena and the topological insulator phase. Circular photogalvanic effect (CPGE) in HgTe QWs is of great interest because it provides an effective optical access to probe the spin-related information of HgTe systems. However, the complex band structure and large spin splitting of HgTe QWs makes it inadequate to analyze the experimental results of CPGE in HgTe QWs [B. Wittmann et al., Semicond. Sci. Technol. 25, 095005 (2010), 10.1088/0268-1242/25/9/095005] with reduced band models. Here, based on the realistic eight-band k .p Hamiltonian and combined with the density-matrix formalism, we present a detailed theoretical investigation of CPGE in (001)-oriented Hg0.3Cd0.7Te /HgTe /Hg0.3Cd0.7Te QWs. We find the CPGE currents in HgTe QWs in the heavily inverted regime are significantly enhanced due to the strong distortion of band dispersion at a certain range of the energy spectrum. This enhancement effect could offer an experimental certificate that the HgTe QW is in the heavily inverted phase (usually accompanied with the emergence of two-dimensional topological edge states), and could also be utilized in engineering the high efficiency ellipticity detector of infrared and terahertz radiation [S. N. Danilov et al., J. Appl. Phys. 105, 013106 (2009), 10.1063/1.3056393]. Additionally, within the same theoretical framework, we also investigate the interplay effect of structure inversion asymmetry and bulk inversion asymmetry and the pure spin currents driven by linearly polarized light in HgTe QWs.

  10. 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.

  11. HG-AFS Determination of Selenium in Moringa Oleifera%HG-AFS测定辣木中的Se

    Institute of Scientific and Technical Information of China (English)

    黄国清; 肖仔君

    2007-01-01

    采用湿法消解,HG-AFS法(氢化物发生原子荧光光谱法)对辣木中微量Se含量进行了分析测定,系统地考察了消化方式、仪器工作条件、酸介质、掩蔽剂等因素对测定的影响,确定了最佳测定条件,结果表明:方法的最低检出限为0.42 ng·mL-1,线性范围0~120 ng·mL-1,相对标准偏差(RSI))为3·53%(n=11),回收率为95.2%~104.6%,表明该方法有较高灵敏度,并且简便、快速、准确.

  12. Mercury accumulation in Mediterranean Fish and Cephalopods Species of Sicilian coasts: correlation between pollution and the presence of Anisakis parasites.

    Science.gov (United States)

    Graci, Stefania; Collura, Rosaria; Cammilleri, Gaetano; Buscemi, Maria Drussilla; Giangrosso, Giuseppe; Principato, Deborah; Gervasi, Teresa; Cicero, Nicola; Ferrantelli, Vincenzo

    2017-05-01

    The aim of this study was to investigate mercury accumulation in some species, caught in Mediterranean Sea, in the period between May and December 2015, and to compare it to the presence of Anisakis parasites. The samples were examined by direct mercury analyzer (DMA-80) for their Hg levels. The metal concentration was compared to the presence or the absence of Anisakis parasites. Significant differences in Hg concentration in analysed samples were observed. The low-infested fishes contained 1-6 larvae of parasites whereas the high-infested one had 7-83 larvae.

  13. Spins of superdeformed band in {sup 192}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Khoo, T.L.; Henry, R.G. [and others

    1995-08-01

    Determination of the spins of SD states is the most important challenge in the study of superdeformation. Knowledge of the spin will provide crucial information on SD bands, in particular on the fascinating phenomenon of bands with identical energies and moments of inertia. Angular distribution coefficients of the {gamma}rays decaying out of the {sup 192}Hg SD band were determined using Eurogam data. These coefficients, as well as the spectral shape and multiplicity of the spectrum, are compared with the results of calculations, thereby providing a check on these calculations. From the measured decay multiplicity and the calculated average spin removed per photon (0.3 h), we deduce the average spin {bar I}{sub decay} removed by the {gamma} rays connecting SD and normal states. The spin I{sub SD} of the SD band from which the decay occurs is given by I{sub SD} = {bar I} decay + {bar I} ND, where {bar I} ND is the average spin removed by the normal yrast states. The state from which the major decay out of the SD band occurs is found to have spin 9.5 {plus_minus} 0.8 h. Since angular momentum is (quantized), this leads to a spin assignment of 9 or 10 h. The latter value is favored since the yrast band in the SD well must have only even spin values. This constitutes the first deduction of spin from data in the mass 150 and 190 regions. The spin of 10 h agrees with the spin which is inferred from a model, using the observed moment of inertia (Im){sup (2)}{omega}.

  14. Nuclear Structure Studies from Hg and Au Alpha Decay Chains

    Science.gov (United States)

    Goon, J. Tm.; Bingham, C. R.; Hartley, D. J.; Zhang, Jing-Ye; Riedinger, L. L.; Danchev, M.; Kondev, F. G.; Carpenter, M. P.; Janssens, R. V. F.; Abu Saleem, K. H.; Ahmad, I.; Davids, C. N.; Heinz, A.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Poli, G. L.; Seweryniak, D.; Wiedenhover, I.; Ma, W. C.; Amro, H.; Reviol, W.; Cizewski, J. A.; Smith, M.

    2003-04-01

    Neutron deficient nuclei near the Z = 82 shell gap have been a source of great interest. This region is known to exhibit the phenomena of shape-coexistence and triaxiality. Alpha decay study of these nuclei coupled with gamma-rayspectroscopy data can give a better understanding of their nuclear structure properties. The decay chains of ^173-177Au and ^175-179Hg were studied following the bombardment of ^92,94,96Mo targets with ^84Sr beam from the ATLAS accelerator at the Argonne National Laboratory. The experiment utilized the Gammasphere array in conjunction with the Fragment Mass Analyzer (FMA) for mass identification and a Double-sided Silicon Strip Detector (DSSD) that was used to detect the recoiling implants and the alpha particles associated with each nuclide. An array of four Ge detectors and a low-energy photon spectrometer (LEPS) was used at the focal plane of the FMA to detect γ rays in coincidence with the α particles. This information was used to elucidate the α-decay fine structures. Inverse radioactive decay tagging was also useful in assigning certain fine structure α peaks to a particular nuclide. New α decay lines were observed and their energies, and half-lives were measured. These include fine structure lines in the α decays of ^174,176Au and ^173Pt. The decay schemes resulting from the fine structure observations will be presented. The α decay reduced widths are used to suggest spin and parity assignments. The structure of these states will be discussed in the framework of the Nilsson model and alpha decay selection rules. * This work is supported by the Department of Energy through contract numbers DE-FG02-96ER40983 (UT), W-31-109-ENG-38 (ANL), DE-FG02-95ER40939 (MSU), DE-FG05-88ER40406 (WU), and by the National Science Foundation (RU

  15. Ultrasonic gas accumulation detection and evaluation in nuclear cooling pipes

    Science.gov (United States)

    Yu, Lingyu; Lin, Bin; Shin, Yong-June; Wang, Jingjiang; Tian, Zhenhua

    2012-04-01

    This paper presents a novel ultrasonic guided wave based inspection methodology for detecting and evaluating gas accumulation in nuclear cooling pipe system. The sensing is in-situ by means of low-profile permanently installed piezoelectric wafer sensors to excite interrogating guided waves and to receive the propagating waves in the pipe structure. Detection and evaluation is established through advanced cross time-frequency analysis to extract the phase change in the sensed signal when the gas is accumulating. A correlation between the phase change and the gas amount has been established to provide regulatory prediction capability based on measured sensory data.

  16. ION EFFECTS IN THE APS PARTICLE ACCUMULATOR RING

    Energy Technology Data Exchange (ETDEWEB)

    Calvey, J.; Harkay, K.; Yao, CY.

    2017-06-25

    Trapped ions in the APS Particle Accumulator Ring (PAR) lead to a positive coherent tune shift in both planes, which increases along the PAR cycle as more ions accumulate. This effect has been studied using an ion simulation code developed at SLAC. After modifying the code to include a realistic vacuum profile, multiple ionization, and the effect of shaking the beam to measure the tune, the simulation agrees well with our measurements. This code has also been used to evaluate the possibility of ion instabilities at the high bunch charge needed for the APS-Upgrade.

  17. Chemical spots in the absence of magnetic field in the binary HgMn star 66 Eridani

    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

    According to our current understanding, a subclass of the upper main sequence chemically peculiar stars, called mercury-manganese (HgMn), is non-magnetic. Nevertheless, chemical inhomogeneities were recently discovered on their surfaces. At the same time, no global magnetic fields stronger than 1-100 G are detected by modern studies. The goals of our study are to search for magnetic field in the HgMn binary system 66 Eri and to investigate chemical spots on the stellar surfaces of both components. Our analysis is based on high quality spectropolarimetric time-series observations obtained during 10 consecutive nights with the HARPSpol instrument at the ESO 3.6-m telescope. To increase the sensitivity of the magnetic field search we employed a least-squares deconvolution (LSD). We used spectral disentangling to measure radial velocities and study line profile variability. Chemical spot geometry was reconstructed using multi-line Doppler imaging. We report a non-detection of magnetic field in 66 Eri, with error ...

  18. Multi-step analysis of Hg2+ ion inhibition of jack bean urease.

    Science.gov (United States)

    Krajewska, Barbara; Zaborska, Wiesława; Chudy, Michał

    2004-06-01

    We performed a multi-step analysis of the inhibition of jack bean urease by Hg(2+) ions that included residual activity measurements after incubation of the enzyme with the metal ion, reactivation of Hg(2+)-inhibited urease, protection of urease with thiol reagents prior to incubation with Hg(2+), progress curve analysis, and spectroscopic assay of thiol groups in urease-Hg(2+) complexes with a cysteine selective agent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Hg(2+) ions were found to form stable complexes with urease that could rapidly be reversed only by the treatment with dithiotreitol, and not by dilution or dialysis. The residual activity data interpreted in terms of the Hill equation revealed the multisite Hg(2+) inhibition of urease, and along with the DTNB thiol-assay they demonstrated the involvement in the reaction with Hg(2+) of six cysteine residues per enzyme subunit, including the active-site flap cysteine. The molar ratios of the inhibitor and enzyme imply that the inhibition consists of the formation of RSHgX complexes, X being a water molecule or an anion. The time-dependent Hg(2+) inhibitory action on urease determined in the system without enzyme preincubation was best described by slow-binding mechanism with the steady-state inhibition constant K(i) = 1.9 nM (+/-10%).

  19. Progress in MOCVD growth of HgCdTe epilayers for HOT infrared detectors

    Science.gov (United States)

    Kebłowski, A.; Gawron, W.; Martyniuk, P.; Stepień, D.; Kolwas, K.; Piotrowski, J.; Madejczyk, P.; Kopytko, M.; Piotrowski, A.; Rogalski, A.

    2016-05-01

    In this paper we present progress in MOCVD growth of (100) HgCdTe epilayers achieved recently at the Institute of Applied Physics, Military University of Technology and Vigo System S.A. It is shown that MOCVD technology is an excellent tool in fabrication of different HgCdTe detector structures with a wide range of composition, donor/acceptor doping and without post grown annealing. Particular progress has been achieved in the growth of (100) HgCdTe epilayers for long wavelength infrared photoconductors operated in HOT conditions. The (100) HgCdTe photoconductor optimized for 13-μm attain detectivity equal to 6.5x109 Jones and therefore outperform its (111) counterpart. The paper also presents technological progress in fabrication of MOCVD-grown (111) HgCdTe barrier detectors. The barrier device performance is comparable with state-of-the-art of HgCdTe photodiodes. The detectivity of HgCdTe detectors is close to the value marked HgCdTe photodiodes. Dark current densities are close to the values given by "Rule 07".

  20. ANTIMONY HALIDES AND HgX2 (X = Cl, Br AMINE ADDUCTS: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    NDONGO GUEYE

    2013-12-01

    Full Text Available Eight new SbF3, SbCl5 and HgX2 (X = Cl, Br amine adducts have been synthesized and their infrared study carried out. Discrete structures have been suggested on the basis of elemental analysis and infrared data, the coordination number of antimony varying from five to nine, while the environment around Hg is tetrahedral.

  1. Synthesis and characterization of HgI2 nanoparticles for films nucleation

    Science.gov (United States)

    Barthaburu, María Pérez; Galain, Isabel; Mombrú, Maia; Aguiar, Ivana; Olivera, Alvaro; Pereira, Heinkel Bentos; Fornaro, Laura

    2017-01-01

    With the aim of controlling the first steps in HgI2 film growth onto amorphous substrates, we employed HgI2 nanoparticles for nucleation. Hg(NO3)2 and NaI were used for obtaining HgI2 in water with and without citric or oxalic acid as capping agents. These samples were then subjected to a hydrothermal treatment at a constant temperature of 120 ºC during 2 h. All samples were washed, centrifuged and dried. This method presents a facile route for obtaining HgI2 nanoparticles and is easily scalable. HgI2 tetragonal phase was confirmed by powder X-ray diffraction. Nanoparticles were characterized in their size and morphology by transmission electron microscopy and the capping agent presence was studied by infrared spectroscopy. HgI2 nanoparticles synthesized in octadecene, previously reported, as well as nanoparticles obtained in the present work, were used for nucleation onto amorphous substrates. They were deposited onto floating silica glass by spin coating and the morphology of the layer was studied by atomic force microscopy. The results we obtained are the first involving HgI2 nucleation by spin coating, and are very promising for improving the film growth orientation and therefore the current applications of this material, as well as for opening new ones.

  2. Nested reactor chamber and operation for Hg-196 isotope separation process

    Science.gov (United States)

    Grossman, M.W.

    1991-10-08

    The present invention is directed to an apparatus for use in [sup 196]Hg separation and its method of operation. Specifically, the present invention is directed to a nested reactor chamber useful for [sup 196]Hg isotope separation reactions avoiding the photon starved condition commonly encountered in coaxial reactor systems. 6 figures.

  3. A measurement of the neutron to {sup 199}Hg magnetic moment ratio

    Energy Technology Data Exchange (ETDEWEB)

    Afach, S. [ETH Zürich, Institute for Particle Physics, CH-8093 Zürich (Switzerland); Paul Scherrer Institute (PSI), CH-5232 Villigen-PSI (Switzerland); Hans Berger Department of Neurology, Jena University Hospital, D-07747 Jena (Germany); Baker, C.A. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Ban, G. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Bison, G. [Paul Scherrer Institute (PSI), CH-5232 Villigen-PSI (Switzerland); Bodek, K. [Marian Smoluchowski Institute of Physics, Jagiellonian University, 30-059 Cracow (Poland); Burghoff, M. [Physikalisch Technische Bundesanstalt, Berlin (Germany); Chowdhuri, Z.; Daum, M. [Paul Scherrer Institute (PSI), CH-5232 Villigen-PSI (Switzerland); Fertl, M.; Franke, B. [ETH Zürich, Institute for Particle Physics, CH-8093 Zürich (Switzerland); Paul Scherrer Institute (PSI), CH-5232 Villigen-PSI (Switzerland); Geltenbort, P. [Institut Laue–Langevin, Grenoble (France); Green, K.; Grinten, M.G.D. van der [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Department of Physics and Astronomy, University of Sussex, Falmer, Brighton BN1 9QH (United Kingdom); Grujic, Z. [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Harris, P.G. [Department of Physics and Astronomy, University of Sussex, Falmer, Brighton BN1 9QH (United Kingdom); Heil, W. [Institut für Physik, Johannes-Gutenberg-Universität, D-55128 Mainz (Germany); Hélaine, V. [Paul Scherrer Institute (PSI), CH-5232 Villigen-PSI (Switzerland); LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Henneck, R. [Paul Scherrer Institute (PSI), CH-5232 Villigen-PSI (Switzerland); and others

    2014-12-12

    The neutron gyromagnetic ratio has been measured relative to that of the {sup 199}Hg atom with an uncertainty of 0.8 ppm. We employed an apparatus where ultracold neutrons and mercury atoms are stored in the same volume and report the result γ{sub n}/γ{sub Hg}=3.8424574(30)

  4. Frequency Ratio of ${}^{199}$Hg and ${}^{87}$Sr Optical Lattice Clocks beyond the SI Limit<