WorldWideScience

Sample records for model mercury ion

  1. Modeling Mercury in Proteins

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jeremy C [ORNL; Parks, Jerry M [ORNL

    2016-01-01

    Mercury (Hg) is a naturally occurring element that is released into the biosphere both by natural processes and anthropogenic activities. Although its reduced, elemental form Hg(0) is relatively non-toxic, other forms such as Hg2+ and, in particular, its methylated form, methylmercury, are toxic, with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg2+ can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg2+ to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Clearly, then, understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed picture and circumvent issues associated with toxicity. Here we describe computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intra-protein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. We describe quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand binding propensities. We then provide a perspective on how we used chemical reasoning to discover how microorganisms methylate mercury. We also highlight our combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confers mercury resistance in many bacteria. Lastly, we place work on mercury in proteins in the context of what is needed for a comprehensive multi-scale model of environmental mercury cycling.

  2. Ecosystem conceptual model- Mercury

    Science.gov (United States)

    Alpers, Charles N.; Eagles-Smith, Collin A.; Foe, Chris; Klasing, Susan; Marvin-DiPasquale, Mark C.; Slotton, Darell G.; Windham-Myers, Lisamarie

    2008-01-01

    mercury conceptual model and its four submodels (1. Methylation, 2. Bioaccumulation, 3. Human Health Effects, and 4. Wildlife Heath Effects) can be used to understand the general relationships among drivers and outcomes associated with mercury cycling in the Delta. Several linkages between important drivers and outcomes have been identified as important but highly uncertain (i.e. poorly understood). For example, there may be significant wildlife health effect of mercury on mammals and reptiles in the Delta, but there is currently very little or no information about it. The characteristics of such linkages are important when prioritizing and funding restoration projects and associated monitoring in the Delta and its tributaries.

  3. Fluorescent sensing and determination of mercury (II) ions in water

    African Journals Online (AJOL)

    2011-11-28

    Nov 28, 2011 ... towards the mercury (II) ion among various alkali, alkaline earth, and transition metal ions. The mercury (II) .... the metal stock solution was added to 13 separate test tubes. The test ..... positive curvature in Stern-Volmer plots.

  4. Thermo-mechanical design aspects of mercury bombardment ion thrusters.

    Science.gov (United States)

    Schnelker, D. E.; Kami, S.

    1972-01-01

    The mechanical design criteria are presented as background considerations for solving problems associated with the thermomechanical design of mercury ion bombardment thrusters. Various analytical procedures are used to aid in the development of thruster subassemblies and components in the fields of heat transfer, vibration, and stress analysis. Examples of these techniques which provide computer solutions to predict and control stress levels encountered during launch and operation of thruster systems are discussed. Computer models of specific examples are presented.

  5. Functionalized diatom silica microparticles for removal of mercury ions

    Directory of Open Access Journals (Sweden)

    Yang Yu, Jonas Addai-Mensah and Dusan Losic

    2012-01-01

    Full Text Available Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS, 3-aminopropyl-trimethoxysilane (APTES and n-(2-aminoethyl-3-aminopropyl-trimethoxysilane (AEAPTMS, and their application for the adsorption of mercury ions (Hg(II is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (–SH or –NH2 were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g-1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto- or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.

  6. Centrifugally Stimulated Exospheric Ion Escape at Mercury

    Science.gov (United States)

    Delcourt, Dominique; Seki, K.; Terada, N.; Moore, Thomas E.

    2012-01-01

    We investigate the transport of ions in the low-altitude magnetosphere magnetosphere of Mercury. We show that, because of small spatial scales, the centrifugal effect due to curvature of the E B drift paths can lead to significant particle energization in the parallel direction. We demonstrate that because of this effect, ions with initial speed smaller than the escape speed such as those produced via thermal desorption can overcome gravity and escape into the magnetosphere. The escape route of this low-energy exosphere originating material is largely controlled by the magnetospheric convection rate. This escape route spreads over a narrower range of altitudes when the convection rate increases. Bulk transport of low-energy planetary material thus occurs within a limited region of space once moderate magnetospheric convection is established. These results suggest that, via release of material otherwise gravitationally trapped, the E B related centrifugal acceleration is an important mechanism for the net supply of plasma to the magnetosphere of Mercury.

  7. Search for Na+ Pickup Ion Generated Waves at Mercury

    Science.gov (United States)

    Boardsen, S. A.; Slavin, J. A.

    2007-05-01

    Telescopic observations by Potter et al. [2002] have discovered that Mercury's Sodium exosphere has a tail extending 10's of Mercury radii. Theory predicts that the shape of and the amount of Sodium [Smyth, 1986, 1995; Ip 1986, 1990] in this exospheric tail is highly dependent upon the true anomaly of Mercury. The exospheric Na that is not reabsorbed on Mercury's surface will be photo-ionized. Computations by Ip [1986] indicated that ionized exospheric Na could significantly mass load the plasma population in Mercury's magnetosphere. These freshly created ions will be rapidly energized by the convection electric field in Mercury's magnetosphere and sheath and should be highly unstable to the generation of plasma waves. These waves could play an important role in the thermalization and retention of the Na+. Because the gyro radii of Na+ can be comparable to the scale sizes in Mercury's geospace there is an open question whether Mercury's geospace can sustain such waves. After a brief review of what was observed in the Mariner 10 magnetometer data, we will present analytic calculations of the expected pickup ion distributions, the expected unstable waves, their frequencies, wavelengths and Doppler shifts, their variation with location in Mercury's geospace and Mercury's true anomaly for both high and low solar wind convection electric fields. We will assess if and when such waves can be generated and sustained.

  8. Ultrasensitive sliver nanorods array SERS sensor for mercury ions.

    Science.gov (United States)

    Song, Chunyuan; Yang, Boyue; Zhu, Yu; Yang, Yanjun; Wang, Lianhui

    2017-01-15

    With years of outrageous mercury emissions, there is an urgent need to develop convenient and sensitive methods for detecting mercury ions in response to increasingly serious mercury pollution in water. In the present work, a portable, ultrasensitive SERS sensor is proposed and utilized for detecting trace mercury ions in water. The SERS sensor is prepared on an excellent sliver nanorods array SERS substrate by immobilizing T-component oligonucleotide probes labeled with dye on the 3'-end and -SH on the 5'-end. The SERS sensor responses to the specific chemical bonding between thymine and mercury ions, which causes the previous flexible single strand of oligonucleotide probe changing into rigid and upright double chain structure. Such change in the structure drives the dyes far away from the excellent SERS substrate and results in a SERS signal attenuation of the dye. Therefore, by monitoring the decay of SERS signal of the dye, mercury ions in water can be detected qualitatively and quantitatively. The experimental results indicate that the proposed optimal SERS sensor owns a linear response with wide detecting range from 1pM to 1μM, and a detection limit of 0.16pM is obtained. In addition, the SERS sensor demonstrates good specificity for Hg(2+), which can accurately identify trace mercury ions from a mixture of ten kinds of other ions. The SERS sensor has been further executed to analyze the trace mercury ions in tap water and lake water respectively, and good recovery rates are obtained for sensing both kinds of water. With its high selectivity and good portability, the ultrasensitive SERS sensor is expected to be a promising candidate for discriminating mercury ions in the fields of environmental monitoring and food safety.

  9. A mercury transport and fate model (LM2-mercury) for mass budget assessment of mercury cycling in Lake Michigan

    Science.gov (United States)

    LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

  10. MODELING MERCURY FATE IN SEVEN GEORGIA WATERSHEDS

    Science.gov (United States)

    Field and modeling studies were conducted in support of total maximum daily loads (TMDLs)for mercury in six south Georgia rivers and the Savannah River. Mercury is introduced to these rivers primarily by atmospheric deposition, with minor point source loadings. To produce mercu...

  11. Micro Mercury Ion Clock (MMIC) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Demonstrate micro clock based on trapped Hg ions with more than 10x size reduction and power; Fractional frequency stability at parts per 1014 level, adequate for...

  12. Buffer Gas Experiments in Mercury (Hg+) Ion Clock

    Science.gov (United States)

    Chung, Sang K.; Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2004-01-01

    We describe the results of the frequency shifts measured from various buffer gases that might be used as a buffer gas to increase the loading efficiency and cooling of ions trapped in a small mercury ion clock. The small mass, volume and power requirement of space clock precludes the use of turbo pumps. Hence, a hermetically sealed vacuum system, incorporating a suitable getter material with a fixed amount of inert buffer gas may be a practical alternative to the groundbased system. The collision shifts of 40,507,347.996xx Hz clock transition for helium, neon and argon buffer gases were measured in the ambient earth magnetic field. In addition to the above non-getterable inert gases we also measured the frequency shifts due to getterable, molecular hydrogen and nitrogen gases which may be used as buffer gases when incorporated with a miniature ion pump. We also examined the frequency shift due to the low methane gas partial pressure in a fixed higher pressure neon buffer gas environment. Methane gas interacted with mercury ions in a peculiar way as to preserve the ion number but to relax the population difference in the two hyperfine clock states and thereby reducing the clock resonance signal. The same population relaxation was also observed for other molecular buffer gases (N H,) but at much reduced rate.

  13. Buffer Gas Experiments in Mercury (Hg+) Ion Clock

    Science.gov (United States)

    Chung, Sang K.; Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2004-01-01

    We describe the results of the frequency shifts measured from various buffer gases that might be used as a buffer gas to increase the loading efficiency and cooling of ions trapped in a small mercury ion clock. The small mass, volume and power requirement of space clock precludes the use of turbo pumps. Hence, a hermetically sealed vacuum system, incorporating a suitable getter material with a fixed amount of inert buffer gas may be a practical alternative to the groundbased system. The collision shifts of 40,507,347.996xx Hz clock transition for helium, neon and argon buffer gases were measured in the ambient earth magnetic field. In addition to the above non-getterable inert gases we also measured the frequency shifts due to getterable, molecular hydrogen and nitrogen gases which may be used as buffer gases when incorporated with a miniature ion pump. We also examined the frequency shift due to the low methane gas partial pressure in a fixed higher pressure neon buffer gas environment. Methane gas interacted with mercury ions in a peculiar way as to preserve the ion number but to relax the population difference in the two hyperfine clock states and thereby reducing the clock resonance signal. The same population relaxation was also observed for other molecular buffer gases (N H,) but at much reduced rate.

  14. Development of mercury (II) ion biosensors based on mercury-specific oligonucleotide probes.

    Science.gov (United States)

    Li, Lanying; Wen, Yanli; Xu, Li; Xu, Qin; Song, Shiping; Zuo, Xiaolei; Yan, Juan; Zhang, Weijia; Liu, Gang

    2016-01-15

    Mercury (II) ion (Hg(2+)) contamination can be accumulated along the food chain and cause serious threat to the public health. Plenty of research effort thus has been devoted to the development of fast, sensitive and selective biosensors for monitoring Hg(2+). Thymine was demonstrated to specifically combine with Hg(2+) and form a thymine-Hg(2+)-thymine (T-Hg(2+)-T) structure, with binding constant even higher than T-A Watson-Crick pair in DNA duplex. Recently, various novel Hg(2+) biosensors have been developed based on T-rich Mercury-Specific Oligonucleotide (MSO) probes, and exhibited advanced selectivity and excellent sensitivity for Hg(2+) detection. In this review, we explained recent development of MSO-based Hg(2+) biosensors mainly in 3 groups: fluorescent biosensors, colorimetric biosensors and electrochemical biosensors.

  15. Note: Production of a mercury beam with an electron cyclotron resonance ion source.

    Science.gov (United States)

    Vondrasek, R; Pardo, R; Scott, R

    2013-11-01

    An electron cyclotron resonance ion source has been utilized to produce mercury beams with intensities of 4.5 eμA of (202)Hg(29+) and 3.0 eμA of (202)Hg(31+) from natural abundance mercury metal. The production technique relies on the evaporation of liquid mercury into the source plasma vacuum region and utilizes elemental mercury instead of a volatile organic compound as the neutral feed material.

  16. Mercury

    Science.gov (United States)

    ... and treatments are needed. ELEMENTAL MERCURY Inhaled elemental mercury poisoning may be difficult to treat. The person may ... metals from the body INORGANIC MERCURY For inorganic mercury poisoning, treatment often begins with supportive care. The person ...

  17. Mercury

    CERN Document Server

    Balogh, André; Steiger, Rudolf

    2008-01-01

    Mercury, the planet closest to the Sun, is different in several respects from the other three terrestrial planets. In appearance, it resembles the heavily cratered surface of the Moon, but its density is high, it has a magnetic field and magnetosphere, but no atmosphere or ionosphere. This book reviews the progress made in Mercury studies since the flybys by Mariner 10 in 1974-75, based on the continued research using the Mariner 10 archive, on observations from Earth, and on increasingly realistic models of its interior evolution.

  18. CFD Modeling for Mercury Control Technology

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, J.I.

    2006-12-01

    Compliance with the Clean Air Mercury Rule will require implementation of dedicated mercury control solutions at a significant portion of the U.S. coal-fired utility fleet. Activated Carbon Injection (ACI) upstream of a particulate control device (ESP or baghouse) remains one of the most promising near-term mercury control technologies. The DOE/NETL field testing program has advanced the understanding of mercury control by ACI, but a persistent need remains to develop predictive models that may improve the understanding and practical implementation of this technology. This presentation describes the development of an advanced model of in-flight mercury capture based on Computational Fluid Dynamics (CFD). The model makes detailed predictions of the induct spatial distribution and residence time of sorbent, as well as predictions of mercury capture efficiency for particular sorbent flow rates and injection grid configurations. Hence, CFD enables cost efficient optimization of sorbent injection systems for mercury control to a degree that would otherwise be impractical both for new and existing plants. In this way, modeling tools may directly address the main cost component of operating an ACI system – the sorbent expense. A typical 300 MW system is expected to require between $1 and $2 million of sorbent per year, and so even modest reductions (say 10-20%) in necessary sorbent feed injection rates will quickly make any optimization effort very worthwhile. There are few existing models of mercury capture, and these typically make gross assumptions of plug gas flow, zero velocity slip between particle and gas phase, and uniform sorbent dispersion. All of these assumptions are overcome with the current model, which is based on first principles and includes mass transfer processes occurring at multiple scales, ranging from the large-scale transport in the duct to transport within the porous structure of a sorbent particle. In principle any single one of these processes

  19. 1-Pyrenecarboxaldehyde thiosemicarbazone:A novel fluorescent molecular sensor towards mercury(Ⅱ)ion

    Institute of Scientific and Technical Information of China (English)

    Xue Mei Wang; Hua Yan; Xin Lu Feng; Yong Chen

    2010-01-01

    A novel and simple fluorescent molecular sensor,1-pyrenecarboxaldehyde thiosemicarbazone(Hpytsc),was synthesized.Its higher sensitivity and selectivity to mercury(Ⅱ)ion were studied through absorption and emission channels.The UV-vis spectra show that the increasing mercury(Ⅱ)ion concentrations result in the decreasing absorption intensity.The fluorescence monomer emission of Hpytsc is enhanced upon binding mercury(Ⅱ)ion,which should be due to the 1:1 complex formation between Hpytsc and metal ion.

  20. Mercury

    Science.gov (United States)

    ... as chlorine, sulfur, or oxygen, to form inorganic mercury compounds or "salts," which are usually white powders or ... Mercury also combines with carbon to make organic mercury compounds. The most common one, methylmercury, is produced mainly ...

  1. Preparation of amine group-containing chelating fiber for thorough removal of mercury ions.

    Science.gov (United States)

    Ma, Nianfang; Yang, Ying; Chen, Shuixia; Zhang, Qikun

    2009-11-15

    An aminated chelating fiber (AF) with high adsorption capacity for mercury ions was prepared by grafting copolymerization of acrylonitrile onto polypropylene fiber, followed by aminating with chelating molecule diethylenetriamine. Effects of reaction conditions such as temperature, reaction time, bath ratio and dosage of catalyst on the grafting yield were studied. Chemical structure, tensile strength and thermal stability of AF were characterized. The adsorption performances for mercury were evaluated by batch adsorption experiments and kinetic experiments. The results show that AF is effective for the removal of mercury over a wide range of pH. The chelating fiber also shows much higher adsorption capacities for mercury, the equilibrium adsorption amount could be as high as 657.9 mg/g for mercury. The high adsorption capacity of Hg(2+) on AF is resulted from the strong chelating interaction between amine groups and mercury ions. Two amine groups coordinate with one mercury ion could be speculated from the adsorption capacity and amine group content on AF. The kinetic adsorption results indicate that the adsorption rates of AF for mercury are very rapid. Furthermore, the residual concentration was less than 1 microg/L with feed concentration of mercury below 1mg/L, which can meet the criterion of drinking water, which indicates that the chelating fiber prepared in this study could be applied to low-level Hg contaminated drinking water purification.

  2. On the Effect of IMF Turning on Ion Dynamics at Mercury

    Science.gov (United States)

    Delcourt, D. C.; Moore, T. E.; Fok, M.-C. H.

    2011-01-01

    We investigate the effect of a rotation of the Interplanetary Magnetic Field (IMF) on the transport of magnetospheric ion populations at Mercury. We focus on ions of planetary origin and investigate their large-scale circulation using three-dimensional single-particle simulations. We show that a nonzero Bx component of the IMF leads to a pronounced asymmetry in the overall circulation pattern . In particular, we demonstrate that the centrifugal acceleration due to curvature of the E x B drift paths is more pronounced in one hemisphere than the other, leading to filling of the magnetospheric lobes and plasma sheet with more or less energetic material depending upon the hemisphere of origin. Using a time-varying electric and magnetic field model, we investigate the response of ions to rapid (a few tens of seconds) re-orientation of the IMF. We show that, for ions with gyroperiods comparable to the field variation time scale, the inductive electric field should lead to significant nonadiabatic energization, up to several hundreds of eVs or a few keVs. It thus appears that IMP turning at Mercury should lead to localized loading of the magnetosphere with energetic material of planetary origin (e.g., Na+).

  3. Mercury

    Science.gov (United States)

    Mercury is an element that is found in air, water and soil. It has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If ... with other elements to form powders or crystals. Mercury is in many products. Metallic mercury is used ...

  4. ANALYSIS OF MERCURY IN VERMONT AND NEW HAMPSHIRE LAKES: EVALUATION OF THE REGIONAL MERCURY CYCLING MODEL

    Science.gov (United States)

    An evaluation of the Regional Mercury Cycling Model (R-MCM, a steady-state fate and transport model used to simulate mercury concentrations in lakes) is presented based on its application to a series of 91 lakes in Vermont and New Hampshire. Visual and statistical analyses are pr...

  5. Calcium in Mercury's Exosphere: Modeling MESSENGER Data

    Science.gov (United States)

    Burger, M. H.; Killen, R. M.; McClintock, W. E.; Merkel, A. W.; Vervack, R. J.; Sarantos, M.; Sprague, A. L.

    2011-12-01

    Mercury is surrounded by a surface-bounded exosphere known to contain hydrogen, sodium, potassium, calcium, and magnesium. Because the exosphere is collisionless, its composition represents a balance of active source and loss processes. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has made high-spatial-resolution observations of sodium, calcium, and magnesium near Mercury's surface and in the extended, anti-sunward direction. The most striking feature of these data is the substantial differences among species, which was detected during three close flybys of the planet and has been persistantly present during MESSENGER's orbital phase. Our modeling demonstrates that these differences are not because of post-ejection dynamics such as differences in photo-ionization rate and radiation pressure, but rather result from differences in the source mechanisms and regions on the surface from which each species is ejected. The observations of calcium have revealed a strong dawn/dusk asymmetry, with the abundance over the dawn hemisphere substantially greater than that on the dusk side. To understand this asymmetry, we use a Monte Carlo model of Mercury's exosphere that we developed to track the motions of exospheric neutrals under the influence of gravity and radiation pressure. In this model, Ca atoms can be ejected directly from the surface or produced by ejection of CaO followed by dissociation to produce Ca and O. Particles are removed from the system if they stick to the surface or escape from the model region of interest (within 15 Mercury radii). Photoionization reduces the final weighting given to each particle when simulating the Ca radiance. Data from the flybys are consistent with a high temperature (~1-2 x 104 K) source of atomic Ca concentrated over the dawn hemisphere. Such a high temperature resutls from dissociation of CaO in a near

  6. A thermodynamic investigation on the binding of mercury ion with myelin basic protein at different temperatures

    Institute of Scientific and Technical Information of China (English)

    G. Rezaei Behbehani; L. Barzegar; A.A. Saboury; S. Ghammami

    2011-01-01

    A thermodynamic study on the interaction of myelin basic protein with mercury ion was studied by using isothermal titration calorimetry, ITC, at 300.15, 310.15 and 320.15 K in Tris buffer solution at pH 7. The enthalpies of MBP + Hg2+ interaction are reported and analysed in terms of the extended solvation model. It was found that MBP has two identical and non-cooperative binding sites for Hg2+ ions. The intrinsic dissociation equilibrium constants are 99.904,112.968 and 126.724 |μmol/L, and the molar enthalpy of binding are -11.634, -10.768 and -10.117 kJ mol 1 at 300.15, 310.15 and 320.15 K, respectively.

  7. Selective detection of mercury (II) ion using nonlinear optical properties of gold nanoparticles.

    Science.gov (United States)

    Darbha, Gopala Krishna; Singh, Anant Kumar; Rai, Uma Shanker; Yu, Eugene; Yu, Hongtao; Chandra Ray, Paresh

    2008-06-25

    Contamination of the environment with heavy metal ions has been an important concern throughout the world for decades. Driven by the need to detect trace amounts of mercury in environmental samples, this article demonstrates for the first time that nonlinear optical (NLO) properties of MPA-HCys-PDCA-modified gold nanoparticles can be used for rapid, easy and reliable screening of Hg(II) ions in aqueous solution, with high sensitivity (5 ppb) and selectivity over competing analytes. The hyper Rayleigh scattering (HRS) intensity increases 10 times after the addition of 20 ppm Hg(2+) ions to modified gold nanoparticle solution. The mechanism for HRS intensity change has been discussed in detail using particle size-dependent NLO properties as well as a two-state model. Our results show that the HRS assay for monitoring Hg(II) ions using MPA-HCys-PDCA-modified gold nanoparticles has excellent selectivity over alkali, alkaline earth (Li(+), Na(+), K(+), Mg(2+), Ca(2+)), and transition heavy metal ions (Pb(2+), Pb(+), Mn(2+), Fe(2+), Cu(2+), Ni(2+), Zn(2+), Cd(2+)).

  8. An ion-imprinted polymer for the selective extraction of mercury(II ...

    African Journals Online (AJOL)

    2011-02-16

    Feb 16, 2011 ... A double-imprinted polymer exhibiting high sensitivity for mercury(II) in aqueous solution is ... In recent years the release of various harmful heavy metal ions ..... both of the competing ions have the same charge, have com-.

  9. Simultaneous bioremediation and biodetection of mercury ion through surface display of carboxylesterase E2 from Pseudomonas aeruginosa PA1.

    Science.gov (United States)

    Yin, Kun; Lv, Min; Wang, Qiaoning; Wu, Yixuan; Liao, Chunyang; Zhang, Weiwei; Chen, Lingxin

    2016-10-15

    Mercury is a toxic heavy metal and presents significant threats to organisms and natural ecosystems. Recently, the mercury remediation as well as its detection by environmental-friendly biotechnology has received increasing attention. In this study, carboxylesterase E2 from mercury-resistant strain Pseudomonas aeruginosa PA1 has been successfully displayed on the outer membrane of Escherichia coli Top10 bacteria to simultaneously adsorb and detect mercury ion (Hg(2+)). The transmission electron microscopy analysis shows that Hg(2+) can be absorbed by carboxylesterase E2 and accumulated on the outer membrane of surface-displayed E. coli bacteria. The adsorption of Hg(2+) followed a physicochemical, equilibrated and saturatable mechanism, which well fits the traditional Langmuir adsorption model. The surface-displayed system can be regenerated through regulating pH values. As its activity can be inhibited by Hg(2+), carboxylesterase E2 has been used to detect the concentration of Hg(2+) in water samples. The developed surface display system will be of great potential in the simultaneous bioremediation and biodetection of environmental mercury pollution. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. MESSENGER Observations of the Spatial Distribution of Planetary Ions Near Mercury

    Science.gov (United States)

    Zurbuchen, Thomas H.; Raines, Jim M.; Slavin, James A.; Gershman, Daniel J.; Gilbert, Jason A.; Gloeckler, George; Anderson, Brian J.; Baker, Daniel N.; Korth, Haje; Krimigis, Stamatios M.; Sarantos, Menelaos; Schriver, David; McNutt, Ralph L., Jr.; Solomon, Sean C.

    2011-01-01

    Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na(+)) and oxygen (O(+)), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury's ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He(+)) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na(+) pressure can be a substantial fraction of the proton pressure.

  11. Determination of Mercury (II Ion on Aryl Amide-Type Podand-Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Sevgi Güney

    2011-01-01

    Full Text Available A new voltammetric sensor based on an aryl amide type podand, 1,8-bis(o-amidophenoxy-3,6-dioxaoctane, (AAP modified glassy carbon electrode, was described for the determination of trace level of mercury (II ion by cyclic voltammetry (CV and differential pulse voltammetry (DPV. A well-defined anodic peak corresponding to the oxidation of mercury on proposed electrode was obtained at 0.2 V versus Ag/AgCl reference electrode. The effect of experimental parameters on differential voltammetric peak currents was investigated in acetate buffer solution of pH 7.0 containing 1 × 10−1 mol L−1 NaCl. Mercury (II ion was preconcentrated at the modified electrode by forming complex with AAP under proper conditions and then reduced on the surface of the electrode. Interferences of Cu2+, Pb2+, Fe3+, Cd2+, and Zn2+ ions were also studied at two different concentration ratios with respect to mercury (II ions. The modified electrode was applied to the determination of mercury (II ions in seawater sample.

  12. Everglqades Mercury: Biogeochemistry, Modeling, and Possible Mitigation

    Science.gov (United States)

    Orem, W. H.

    2015-12-01

    In the 1980s high levels of methylmercury (MeHg) were found in fish and other biota in the Florida Everglades, prompting fish consumption advisories. As part of Everglades restoration efforts Federal and State Agencies initiated a research program to study the underlying causes of the MeHg contamination. As part of this multi-agency effort, the U.S. Geological Survey developed the ACME (Aquatic Cycling of Mercury in the Everglades) project to examine the underlying biogeochemical factors controlling MeHg production and bioaccumulation in the ecosystem. Field studies by ACME and others identified the many factors impacting MeHg production in the Everglades. Thes factors include: high mercury deposition, large wetland area with organic-rich anaerobic soil, high sulfate loading in surface runoff, circumneutral pH, and high dissolved organic matter (DOM) content. Florida Department of Environmental Protection efforts that reduced local mercury emissions by 90%, produced only a small reduction in mercury deposition on the Everglades, suggesting that most Hg deposited on the ecosystem originates from distant sources, and beyond the reach of regulators. ACME studies demonstrated that high sulfate loading to the Everglades comes from discharge of canal water originating in the Everglades Agricultural Area (EAA). The use of sulfur in agriculture and soil oxidation in the EAA have been shown to be the principal sources of the sulfate loading. Sulfate entering the ecosystem drives microbial sulfate reduction and MeHg production, but inhibition of MeHg production by sulfide (a byproduct of microbial sulfate reduction) makes the biogeochemistry complex. Laboratory microcosm and field mesocosm experiments by ACME helped define the complexity of the sulfur/MeHg biogeochemistry, and demonstrated the key role of dissolved organic matter in MeHg production. A conceptual model was developed that relates MeHg production to sulfate loading, DOM, and soil composition. This conceptual

  13. Detection of Isotopes of Mercury Ions by Resonant Ejection in Paul Trap

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-Ming; SHE Lei; LI Jiao-Mei; GAO Ke-Lin

    2007-01-01

    A simple method to detect mercury ions confined in a Paul trap has been developed by resonant ejection. In this method, frequency of the additional ejection ac voltage is scanned instead of the amplitude of the rf drive voltage in conventional methods. It is possible not only to observe the spectra of the secular oscillation of the trapped ions directly, but also to eject the confined ions from the trap mass-selectively.

  14. Thermalization of Na+ Pickup Ions in Mercury's Magnetosheath and Magnetosphere via Hybrid Simulation

    Science.gov (United States)

    Boardsen, S. A.; Omidi, N.; Slavin, J. A.

    2007-12-01

    In previous studies it has been suggested that the incorporation of Na+ pickup ions into Mercury's magnetosphere could have a significant impact on various magnetospheric processes. Test particle simulations indicate that freshly created Na+ ions are rapidly energized and lost from the system. In order to incorporate these ions into the bulk magnetospheric plasma they must be thermalized. A recent study that used linear theory suggests that the wavelengths of electromagnetic ion cyclotron waves may be to large and may not grow to sufficient amplitudes to thermalize these ions and concluded that global thermalization of these ions is not possible. However, under certain solar wind and IMF conditions such thermalization might take place in limited regions of Mercury's magnetosphere, primarily in the sub-solar magnetosheath. Due the small scale size of Mercury's magnetosphere compared to the gyro-radii of these heavy ions and their associated wave modes, hybrid simulation with a kinetic treatment for the ions and a fluid treatment for the electrons may be the only way to study if thermalization of Na+ can occur. Preliminary results of a hybrid simulation that incorporates the Na+ pickup ions in its kinetic treatment will be presented.

  15. Thiol-functionalized MCM-48: an Effective Absorbent of Mercury Ions

    Institute of Scientific and Technical Information of China (English)

    Shu Guo WANG; Jin Lin LI

    2006-01-01

    Mercaptopropyl groups were grafted onto the pore walls of mesoporous molecular sieves MCM-48. The pore structures were characterized by powder X-ray diffraction and N2 adsorption analysis. Elemental analysis confirmed that the material with high organic moiety (2.2 mmol/g) had been obtained. 13C MAS NMR verified the tethered organic groups. The thiol-functionalized MCM-48 showed effective capture of mercury ions, and all of the organic ligands were accessible for the binding of mercury ions.

  16. Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

    Energy Technology Data Exchange (ETDEWEB)

    Al Razi, Khandakar Md Habib; Hiroshi, Moritomi; Shinji, Kambara [Environmental and Renewable Energy System (ERES), Graduate School of Engineering, Gifu University, Yanagido, Gifu City, 501-1193 (Japan)

    2012-07-01

    The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environmental concern. Identification of sources contributing to the high atmospheric mercury levels will be useful for formulating pollution control and mitigation strategies in the region. In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of 'Substances Requiring Priority Action' published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 ?g/m3. Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER) that estimates regional atmospheric concentration and distribution. The second is the Hybrid Single Particle Lagrangian Integrated trajectory Model (HYSPLIT) that estimates the atmospheric

  17. Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

    Directory of Open Access Journals (Sweden)

    Khandakar Md Habib Al Razi, Moritomi Hiroshi, Kambara Shinji

    2012-01-01

    Full Text Available The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environmental concern. Identification of sources contributing to the high atmospheric mercury levels will be useful for formulating pollution control and mitigation strategies in the region. In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of "Substances Requiring Priority Action" published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 μg/m3. Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER that estimates regional atmospheric concentration and distribution. The second is the Hybrid Single Particle Lagrangian Integrated trajectory Model (HYSPLIT that estimates the

  18. Complexation of mercury(II) ions with humic acids in tundra soils

    Science.gov (United States)

    Vasilevich, R. S.; Beznosikov, V. A.; Lodygin, E. D.; Kondratenok, B. M.

    2014-03-01

    The interaction mechanisms of mercury(II) ions with preparations of humic acids (HAs) isolated from organic horizons of surface-gleyed soils (Haplic Stagnosol (Gelic, Siltic)) of shrub tundra and hydromorphic peat gley soils (Histic Cryosol (Reductaquic, Siltic)) of moss-lichen tundra have been studied. The particular features of the interactions between the mercury(II) ions and the HAs are related to the molecular structure of the HAs, the mercury concentration range, and the environmental parameters. The fixation of mercury(II) ions into stable coordination compounds is most efficient in the pH range of 2.5-3.5. At the element concentrations below 0.50 μmol/dm3, the main complexing sites of HAs are their peripheral aminoacid functional groups. Pyrocatechol, salicylate, and phenolic groups from the nuclear moiety of molecules interact in the concentration range of 0.0005-0.50 mmol/dm3; the physical sorption of mercury hydroxo complexes by the surface of HAs is the main process occurring in the system.

  19. Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

    Directory of Open Access Journals (Sweden)

    J. Bieser

    2017-06-01

    Full Text Available Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

  20. Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

    Science.gov (United States)

    Bieser, Johannes; Slemr, Franz; Ambrose, Jesse; Brenninkmeijer, Carl; Brooks, Steve; Dastoor, Ashu; DeSimone, Francesco; Ebinghaus, Ralf; Gencarelli, Christian N.; Geyer, Beate; Gratz, Lynne E.; Hedgecock, Ian M.; Jaffe, Daniel; Kelley, Paul; Lin, Che-Jen; Jaegle, Lyatt; Matthias, Volker; Ryjkov, Andrei; Selin, Noelle E.; Song, Shaojie; Travnikov, Oleg; Weigelt, Andreas; Luke, Winston; Ren, Xinrong; Zahn, Andreas; Yang, Xin; Zhu, Yun; Pirrone, Nicola

    2017-06-01

    Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

  1. Development of a disposable mercury ion-selective optode based on trityl-picolinamide as ionophore

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman,; Dam, Henk H.; Reinhoudt, David N.; Verboom, Willem

    2007-01-01

    A disposable ion-selective optode for mercury based on trityl-picolinamide (T-Pico) as neutral ionophore was developed. The sensing layer consist of plasticised PVC incorporating T-Pico as a selective ionophore for Hg2+, ETH 5418 as a chromoionophore, and potassium tetrakis[3,5-bis(trifluoromethyl)p

  2. Development of a disposable mercury ion-selective optode based on tritylpicolinamide as ionophore

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Dam, H.H.; Reinhoudt, David; Verboom, Willem

    2007-01-01

    A disposable ion-selective optode for mercury based on trityl-picolinamide (T-Pico) as neutral ionophore was developed. The sensing layer consist of plasticised PVC incorporating T-Pico as a selective ionophore for Hg2+, ETH 5418 as a chromoionophore, and potassium

  3. Theoretical models of mercury dissolution from dental amalgams in neutral and acidic flows

    Science.gov (United States)

    Keanini, Russell G.; Ferracane, Jack L.; Okabe, Toru

    2001-06-01

    This article reports an experimental and theoretical investigation of mercury dissolution from dental amalgams immersed in neutral (noncorrosive) and acidic (corrosive) flows. Atomic absorption spectrophotometric measurements of Hg loss indicate that in neutral flow, surface oxide films formed in air prior to immersion persist and effectively suppress significant mercury release. In acidic (pH 1) flows, by contrast, oxide films are unstable and dissolve; depending on the amalgam’s material composition, particularly its copper content, two distinct mercury release mechanisms are initiated. In low copper amalgam, high initial mercury release rates are observed and appear to reflect preferential mercury dissolution from unstable Sn8Hg ( γ 2) grains within the amalgam matrix. In high copper amalgam, mercury release rates are initially low, but increase with time. Microscopic examination suggests that this feature reflects corrosion of copper from grains of Cu6Sn5 ( η') and consequent exposure of Ag2Hg3 ( γ 1) grains; the latter serve as internal mercury release sites and become more numerous as corrosion proceeds. Three theoretical models are proposed in order to explain observed dissolution characteristics. Model I, applicable to high and low copper amalgams in neutral flow, assumes that mercury dissolution is mediated by solid diffusion within the amalgam, and that a thin oxide film persists on the amalgam’s surface and lumps diffusive in-film transport into an effective convective boundary condition. Model II, applicable to low copper amalgam in acidic flow, assumes that the amalgam’s external oxide film dissolves on a short time scale relative to the experimental observation period; it neglects corrosive suppression of mercury transport. Model III, applicable to high copper amalgam in acidic flow, assumes that internal mercury release sites are created by corrosion of copper in η' grains and that corrosion proceeds via an oxidation-reduction reaction

  4. Adsorption of mercury ions by mercapto-functionalized amorphous silica

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Quintanilla, Damian; Hierro, Isabel del; Fajardo, Mariano; Sierra, Isabel [Universidad Rey Juan Carlos, Departamento de Tecnologia Quimica y Ambiental, E.S.C.E.T, Mostoles, Madrid (Spain); Carrillo-Hermosilla, Fernando [Universidad de Castilla-La Mancha, Departamento de Quimica Inorganica, Organica y Bioquimica, Facultad de Quimicas, Ciudad Real (Spain)

    2006-02-01

    Amorphous silicas have been functionalized by two different methods. In the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the silica surface to give the chlorinated silica Cl-Sil. In a second reaction, multifunctionalized N,S donor compounds were incorporated to obtain the functionalized silicas, which are denoted as L-Sil-Het (where L=mercaptothiazoline, mercaptopyridine or mercaptobenzothiazole). In the homogeneous route, the functionalization was achieved through a one-step reaction between the silica and an organic ligand containing the chelating functions; this gave the modified silicas denoted as L-Sil-Hom. The functionalized silicas were characterized by elemental analysis, IR spectroscopy and thermogravimetry. These materials were employed as adsorbents for mercury cations from aqueous and acetone solutions at room temperature. The results indicate that, in all cases, mercury adsorption was higher in the modified silicas prepared by the homogeneous method. (orig.)

  5. D-penicillamine-templated copper nanoparticles via ascorbic acid reduction as a mercury ion sensor.

    Science.gov (United States)

    Lin, Shu Min; Geng, Shuo; Li, Na; Li, Nian Bing; Luo, Hong Qun

    2016-05-01

    Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270nm). Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg(2+) in the 1.0-30μM concentration range and the detection limit (3σ/slope) is 32nM. The method was successfully applied to determine Hg(2+) in real water samples.

  6. Mercury

    CERN Document Server

    Mahoney, T J

    2014-01-01

    This gazetteer and atlas on Mercury lists, defines and illustrates every named (as opposed to merely catalogued) object and term as related to Mercury within a single reference work. It contains a glossary of terminology used, an index of all the headwords in the gazetteer, an atlas comprising maps and images with coordinate grids and labels identifying features listed in the gazetteer, and appendix material on the IAU nomenclature system and the transcription systems used for non-roman alphabets. This book is useful for the general reader, writers and editors dealing with astronomical themes, and those astronomers concerned with any aspect of astronomical nomenclature.

  7. One Step In-Situ Formed Magnetic Chitosan Nanoparticles as an Efficient Sorbent for Removal of Mercury Ions From Petrochemical Waste Water: Batch and Column Study

    Directory of Open Access Journals (Sweden)

    Rahbar

    2015-10-01

    Full Text Available Background In the recent years, mercury contamination has attracted great deal of attention due to its serious environmental threat. Objectives The main goal of this study was application of one-step synthesized magnetic (magnetite chitosan nanoparticles (MCNs in the removal of mercury ions from petrochemical waste water. Materials and Methods This study was performed in batch and column modes. Effects of various parameters such as pH, adsorbent dose, contact time, temperature and agitation speed for the removal of mercury ions by MCNs investigated in batch mode. Afterwards, optimum conditions were exploited in column mode. Different kinetic models were also studied. Results An effective Hg (II removal (99.8% was obtained at pH 6, with 50 mg of MCNs for an initial concentration of this ion in petrochemical waste water (5.63 mg L-1 and 10 minutes agitation of the solution. The adsorption kinetic data was well fitted to the pseudo-second-order model. Conclusions Experimental results showed that MCNs is an excellent sorbent for removal of mercury ions from petrochemical waste water. In addition, highly complex matrix of this waste does not affect the adsorption capability of MCNs.

  8. Mercury's spin-orbit model and its physical libration

    Science.gov (United States)

    Rambaux, N.

    2004-12-01

    The upcoming space missions, MESSENGER and BepiColombo with onboard instrumentation capable of measuring the rotational parameters stimulate the objective to reach an accurate theory of the rotational motion of Mercury. Our work deals with the physical and dynamical causes that induce librations of Mercury in order to evaluate accurately the rotational motion of this planet. In this aim, we have extended our BJV relativistic model of solar system integration including the spin-orbit coupled motion of the Moon to the spin-orbit coupling of terrestrial planets and particularly to Mercury (the BJV model was previously built by Bois, Journet and Vokrouhlicky in accordance with the requirements of the Lunar Laser Ranging observational accuracy). The model is at present called SONYR, acronym of Spin-Orbit N-BodY Relativistic model. Using the model, we can analyze the different families of rotational librations and identify their causes such as the planetary interactions or the impact of the parameters describing the dynamical figure of Mercury. In addition, the spin-orbit motion of Mercury is characterized by two proper frequencies (15.847 and 1066 years). Mercury presents also, between its angle of precession and the ascending node of the orbit, a second synchronism of 278898 years, which can be understood as a spin-orbit secular resonance. Besides, within the SONYR model, which integrates simultaneously the orbital and rotational motion of Mercury, we have been able to improve the Hermean's mean obliquity (1.665 arcminutes) and we identify the non-linear relationship between the dynamical figure and both the obliquity and the angle of libration in longitude. These determinations provide constraints on the internal structure of Mercury.

  9. Detection of mercury ions based on mercury-induced switching of enzyme-like activity of platinum/gold nanoparticles

    Science.gov (United States)

    Tseng, Chao-Wei; Chang, Hsiang-Yu; Chang, Jia-Yaw; Huang, Chih-Ching

    2012-10-01

    In this study, bimetallic platinum/gold nanoparticles (Pt/Au NPs) were found to exhibit peroxidase-like activity, and the deposition of mercury was found to switch the enzymatic activity to a catalase-like activity. Based on this phenomenon, we developed a new method for detecting mercury ions through their deposition on bimetallic Pt/Au NPs to switch the catalytic activity of Pt/Au NPs. Pt/Au NPs could be easily prepared through reduction of Au3+ and Pt4+ by sodium citrate in a one-pot synthesis. The peroxidase catalytic activity of the Pt/Au NPs was controlled by varying the ratios of Pt to Au. The Pt0.1/Au NPs (prepared with a [Au3+]/[Pt4+] molar ratio of 9.0/1.0) showed excellent oxidation catalysis for H2O2-mediated oxidation of Amplex® Red (AR) to resorufin. The oxidized product of AR, resorufin, fluoresces more strongly (excitation/emission wavelength maxima ca. 570/585 nm) than AR alone. The peroxidase catalytic activity of Pt0.1/Au NPs was switched to catalase-like activity in the presence of mercury ions in a 5.0 mM tris(hydroxymethyl)aminomethane (Tris)-borate solution (pH 7.0) through the deposition of Hg on the particle surfaces owing to the strong Hg-Au metallic bond. The catalytic activity of Hg-Pt0.1/Au NPs is superior (by at least 5-fold) to that of natural catalase (from bovine liver). Under optimal solution conditions [5.0 mM Tris-borate (pH 7.0), H2O2 (50 mM), and AR (10 μM)] and in the presence of the masking agents polyacrylic acid and tellurium nanowires, the Pt0.1/Au NPs allowed the selective detection of inorganic mercury (Hg2+) and methylmercury ions (MeHg+) at concentrations as low as several nanomolar. This simple, fast, and cost-effective system enabled selective determination of the spiked concentrations of Hg2+ and MeHg+ in tap, pond, and stream waters.In this study, bimetallic platinum/gold nanoparticles (Pt/Au NPs) were found to exhibit peroxidase-like activity, and the deposition of mercury was found to switch the enzymatic

  10. High extraction ability of 1,3-dialkynyl calixarene towards mercury(Ⅱ) ion

    Institute of Scientific and Technical Information of China (English)

    Lin Bo Gong; Shu Ling Gong; Qin Zheng; Xiong Li; Yuan Yin Chen

    2007-01-01

    The reaction of 1,3-dipropyn-2-yloxycalix[4]arene with mercury(Ⅱ) acetate could give mercury-containing alkynyl calixarene polymer. The extraction behavior of 1,3-dipropyn-2-yl-oxycalix[4]arene towards mercury(H) ion was examined. When the mole ratio of Hg2+/calixarene was 1∶1, the extractive percent can reach to 99.1%, and the extraction capacity was up to 431 mg/g. It could also decrease the Hg2+ concentration from 5 to 0.85 mg/L, which was only 17% of the national standard of effluent and satisfied the national standard of drinking water. The extraction process included chemical reaction.

  11. Integrating a DNA Strand Displacement Reaction with a Whispering Gallery Mode Sensor for Label-Free Mercury (II) Ion Detection.

    Science.gov (United States)

    Wu, Fengchi; Wu, Yuqiang; Niu, Zhongwei; Vollmer, Frank

    2016-07-29

    Mercury is an extremely toxic chemical pollutant of our environment. It has attracted the world's attention due to its high mobility and the ease with which it accumulates in organisms. Sensitive devices and methods specific for detecting mercury ions are, hence, in great need. Here, we have integrated a DNA strand displacement reaction with a whispering gallery mode (WGM) sensor for demonstrating the detection of Hg(2+) ions. Our approach relies on the displacement of a DNA hairpin structure, which forms after the binding of mercury ions to an aptamer DNA sequence. The strand displacement reaction of the DNA aptamer provides highly specific and quantitative means for determining the mercury ion concentration on a label-free WGM sensor platform. Our approach also shows the possibility for manipulating the kinetics of a strand displacement reaction with specific ionic species.

  12. Old tree with new shoots: silver nanoparticles for label-free and colorimetric mercury ions detection

    Science.gov (United States)

    Gao, Shuyan; Jia, Xiaoxia; Chen, Yanli

    2013-01-01

    Mercury in the environment from global mercury emissions as well as various forms of contamination poses severe threats to both human health and the environment. Long-term exposure to high levels of Hg-based toxins results in serious and irreversible damage of the central nervous system and other organs. Therefore, the development of effective sensing systems for mercury detection becomes an increasing demand. In this article, a yogurt-mediated silver nanostructure is reported to be unprecedentedly used in the naked-eye and label-free detection of mercury. The method relies on the redox reaction resulting from the electrode potential difference between Ag+/Ag (0.7996 V) and Hg2+/Hg2 2+ (0.920 V) that makes colorless Hg2+ ions which oxidize colored silver nanoparticle (AgNP) to colorless Ag+. The labor-intensive modification of AgNPs and expensive labeling are avoided, and the traditional AuNPs are substituted by AgNPs in this Hg2+ ions sensing platform, which makes it facile, low-cost, and particularly useful for home, clinic, or field applications as well as resource-limited conditions. This sensing system achieves a detection limit as low as 10 nM, lower than the toxicity level of Hg2+ ions in drinking water (30 nM) defined by World Health Organization, and exhibits excellent selectivity, largely free from the matrix effect of the real water samples. This visual label-free Hg2+ ions sensing motif shows great promise for sensing Hg2+ ions in terms of sensitivity, selectivity, cost, and maneuverability. It is also a good example for the organic combination of green chemistry and functional materials, which may trigger interest in furthering biosystems for environmental science applications.

  13. Neon as a Buffer Gas for a Mercury-Ion Clock

    Science.gov (United States)

    Prestage, John; Chung, Sang

    2008-01-01

    A developmental miniature mercury-ion clock has stability comparable to that of a hydrogen-maser clock. The ion-handling components are housed in a sealed vacuum tube, wherein a getter pump is used to maintain the partial vacuum, and the evacuated tube is backfilled with mercury vapor in a buffer gas. Neon was determined to be the best choice for the buffer gas: The pressure-induced frequency pulling by neon was found to be only about two-fifths of that of helium. Furthermore, because neon diffuses through solids much more slowly than does helium, the operational lifetime of a tube backfilled with neon could be considerably longer than that of a tube backfilled with helium.

  14. Phragmites karka as a Biosorbent for the Removal of Mercury Metal Ions from Aqueous Solution: Effect of Modification

    Directory of Open Access Journals (Sweden)

    Muhammad Hamid Raza

    2015-01-01

    Full Text Available Batch scale studies for the adsorption potential of novel biosorbent Phragmites karka (Trin, in its natural and treated forms, were performed for removal of mercury ions from aqueous solution. The study was carried out at different parameters to obtain optimum conditions of pH, biosorbent dose, agitation speed, time of contact, temperature, and initial metal ion concentration. To analyze the suitability of the process and maximum amount of metal uptake, Dubinin-Radushkevich (D-R model, Freundlich isotherm, and Langmuir isotherm were applied. The values of qmax for natural and treated biosorbents were found at 1.79 and 2.27 mg/g, respectively. The optimum values of contact time and agitation speed were found at 50 min and 150 rpm for natural biosorbent whereas 40 min and 100 rpm for treated biosorbent, respectively. The optimum biosorption capacities were observed at pH 4 and temperature 313 K for both natural P. karka and treated P. karka. RL values indicate that comparatively treated P. karka was more feasible for mercury adsorption compared to natural P. karka. Both pseudo-first-order and pseudo-second-order kinetic models were applied and it was found that data fit best to the pseudo-second-order kinetic model. Thermodynamic studies indicate that adsorption process was spontaneous, feasible, and endothermic.

  15. Binol based “turn on” fluorescent chemosensor for mercury ion

    Energy Technology Data Exchange (ETDEWEB)

    Velmurugan, Krishnaswamy; Nandhakumar, Raju, E-mail: nandhakumar@karunya.edu

    2015-06-15

    A simple dimeric binol-based fluorescent chemosensor S-1, capable of detecting Hg{sup 2+} in aqueous media is designed and synthesized. The Hg{sup 2+} recognition processes follow a photo induced electron transfer (PET) mechanism and are scarcely influenced by other coexisting metal ions. In addition, determination of mercury in waste water samples was also analysed. - Highlights: • Dimeric binol derived fluorescent chemosensor S-1. • Detection of Hg{sup 2+} in aqueous media with high selectivity. • A fluorescence “turn-on” process by a possible PET mechanism proposed. • Sensor is utilized to detect the Hg{sup 2+} ions in environmental water samples.

  16. Digital computer control of a 30-cm mercury ion thruster

    Science.gov (United States)

    Low, C. A., Jr.

    1975-01-01

    The major objective was to define the exact role of an onboard spacecraft computer in the control of ion thrusters. An initial computer control system with accurate high speed capability was designed, programmed, and tested with the computer as the sole control element for an operating ion thruster. The command functions and a code format for a spacecraft digital control system were established. A second computer control system was constructed to operate with these functions and format. A throttle program sequence was established and tested. A two thruster array was tested with these computer control systems and the results reported.

  17. Synthesis of a Novel Fluorescent Sensor Bearing Dansyl Fluorophores for the Highly Selective Detection of Mercury (II Ions

    Directory of Open Access Journals (Sweden)

    Kate Grudpan

    2010-03-01

    Full Text Available A new macromolecule possessing two dansyl moieties and based on 2-[4-(2-aminoethylthiobutylthio]ethanamine was prepared as a fluorescent sensor and its mercury sensing properties toward various transition metal, alkali, and alkali earth ions were investigated. The designed compound exhibited pronounced Hg2+-selective ON-OFF type fluorescence switching upon binding. The new compoundprovided highly selective sensing to Hg2+ in acetonitrile-water solvent mixtures with a detection limit of 2.49 x 10-7 M or 50 ppb. The molecular modeling results indicated that ions-recognition of the sensor originated from a self assembly process of the reagentand Hg2+ to form a helical wrapping structure with the favorable electrostatic interactions of Hg2+coordinated with sulfur, oxygen, nitrogen atoms and aromatic moieties.

  18. A simple model of the chaotic eccentricity of Mercury

    CERN Document Server

    Boué, Gwenaël; Farago, François

    2012-01-01

    Mercury's eccentricity is chaotic and can increase so much that collisions with Venus or the Sun become possible (Laskar, 1989, 1990, 1994, 2008, Batygin & Laughlin, 2008, Laskar & Gastineau, 2009). This chaotic behavior results from an intricate network of secular resonances, but in this paper, we show that a simple integrable model with only one degree of freedom is actually able to reproduce the large variations in Mercury's eccentricity, with the correct amplitude and timescale. We show that this behavior occurs in the vicinity of the separatrices of the resonance g1-g5 between the precession frequencies of Mercury and Jupiter. However, the main contribution does not come from the direct interaction between these two planets. It is due to the excitation of Venus' orbit at Jupiter's precession frequency g5. We use a multipolar model that is not expanded with respect to Mercury's eccentricity, but because of the proximity of Mercury and Venus, the Hamiltonian is expanded up to order 20 and more in t...

  19. Porcolation: An Invasion Percolation Model for Mercury Porosimetry

    Science.gov (United States)

    Bak, Bendegúz Dezső; Kalmár-Nagy, Tamás

    Mercury porosimetry is utilized primarily in the oil industry to determine the pore size distribution of rock samples. During the process, mercury is forced into the sample with gradually increasing pressure and the volume of the injected mercury is measured vs. the applied pressure (the saturation curve). In practice, the saturation curve is assumed to be directly related the cumulative pore size distribution. However, this distribution does not coincide with the real one because of the “nonaccessibility” of pores at a given pressure. This motivates our goal to determine a more accurate cumulative pore size distribution. To achieve this, we treat the propagation of mercury as a percolation process (dubbed “porcolation” after PORosimetry perCOLATION). Porcolation is an external pressure-driven access-limited invasion percolation model where resistance values are assigned to sites/vertices. As pressure increases, the invading mercury occupies sites with smaller resistance values along paths that are connected to the “boundaries” of the network. Simulations are carried out on regular lattices, as well as on random graphs with prescribed degree distributions (representing the pore network of rock samples). An assumed pore size distribution is considered as an input/parameter of the simulations resulting in an output saturation curve. We determine the input-output mapping (homeomorphism) and utilize its inverse to correct the discrepancies between the assumed and actual pore size distributions. The results show nice agreement between experimental saturation curves and those obtained from our homeomorphism method.

  20. Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model

    Directory of Open Access Journals (Sweden)

    E. Kallio

    Full Text Available Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model.

    In this paper we present a new quasi-neutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally, some of the first three-dimensional hybrid model runs made for Mercury are presented.

    The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions, and the study clearly demonstrates the large potential of the approach to address these more detailed issues by a quasi-neutral hybrid model in the future.

    Key words. Magnetospheric physics

  1. Model atmospheres for Mercury based on a lunar analogy

    Science.gov (United States)

    Hodges, R. R., Jr.

    1974-01-01

    Similarities in daytime spectral reflectivities and nighttime infrared emission from Mercury and the moon are shown to imply that the atmosphere of Mercury must be tenuous, like that of the moon. The theory of formation, transport, and loss in the lunar atmosphere is applied to Mercury. Models of the Hermian atmosphere at perihelion and aphelion are presented, based on the solar wind as the dominant source of gases. Only the noncondensable species - hydrogen, helium and neon - are considered. Of these, helium is the most abundant atmospheric gas, with maximum concentration of about 40,000,000 per cu cm at the nighttime surface. The maximum concentration of H2 is 6,000,000 per cu cm, and that of neon is 700,000 per cu cm.

  2. Enhanced and selective adsorption of mercury ions on chitosan beads grafted with polyacrylamide via surface-initiated atom transfer radical polymerization.

    Science.gov (United States)

    Li, Nan; Bai, Renbi; Liu, Changkun

    2005-12-06

    Enhanced and selective removal of mercury ions was achieved with chitosan beads grafted with polyacrylamide (chitosan-g-polyacrylamide) via surface-initiated atom transfer radical polymerization (ATRP). The chitosan-g-polyacrylamide beads were found to have significantly greater adsorption capacities and faster adsorption kinetics for mercury ions than the chitosan beads. At pH 4 and with initial mercury concentrations of 10-200 mg/L, the chitosan-g-polyacrylamide beads can achieve a maximum adsorption capacity of up to 322.6 mg/g (in comparison with 181.8 mg/g for the chitosan beads) and displayed a short adsorption equilibrium time of less than 60 min (compared to more than 15 h for the chitosan beads). Coadsorption experiments with both mercury and lead ions showed that the chitosan-g-polyacrylamide beads had excellent selectivity in the adsorption of mercury ions over lead ions at pH mercury adsorption was due to the many amide groups grafted onto the surfaces of the beads, and the selectivity in mercury adsorption can be attributed to the ability of mercury ions to form covalent bonds with the amide. It was found that adsorbed mercury ions on the chitosan-g-polyacrylamide beads can be effectively desorbed in a perchloric acid solution, and the regenerated beads can be reused almost without any loss of adsorption capacity.

  3. Mercury(II) ion-selective electrodes based on heterocyclic systems.

    Science.gov (United States)

    Mahajan, Rakesh Kumar; Sood, Pallavi; Pal Mahajan, Mohinder; Marwaha, Alka

    2007-09-01

    Mercury ion-selective electrodes (ISEs) were prepared with a polymeric membrane based on heterocyclic systems: 2-methylsulfanyl-4-(4-nitro-phenyl)-l-p-tolyl-1H-imidazole (I) and 2,4-diphenyl-l-p-tolyl-1H-imidazole (II) as the ionophores. Several ISEs were conditioned and tested for the selection of common ions. The electrodes based on these ionophores showed a good potentiometric response for Hg2+ ions over a wide concentration range of 5.0 x 10(5-) - 1.0 x 10(-1)M with near-Nernstian slopes. Stable potentiometric signals were obtained within a short time period of 20 s. The detection limits, the working pH range of the electrodes were 1.0 x 10(-5) M and 1.6-4.4 respectively. The electrodes showed better selectivity for Hg2+ ions over many of the alkali, alkaline-earth and heavy metal ions. Also sharp end points were obtained when these sensors were used as indicator electrodes for the potentiometric titration of Hg2+ ions with iodide ions.

  4. Sensitive determination method for mercury ion, methyl-, ethyl-, and phenyl-mercury in water and biological samples using high-performance liquid chromatography with chemiluminescence detection.

    Science.gov (United States)

    Kodamatani, Hitoshi; Matsuyama, Akito; Saito, Keiitsu; Kono, Yuriko; Kanzaki, Ryo; Tomiyasu, Takashi

    2012-01-01

    A sensitive determination method for mercury speciation analysis was developed. Four mercury species, mercury ion, methylmercury, ethylmercury, and phenylmercury, were complexed with emetine-dithiocarbamate (emetine-CS(2)), and then injected onto a HPLC instrument coupled with a tris(2,2'-bipyridine)ruthenium(III) chemiluminescence detection system. The emetine-CS(2) complexing agent was effectively used to measure the concentration in addition to serving as a separation and detection reagent. The calibration curves for these mercury complexes were linear in the range of 0.050 - 10 μg L(-1) (as Hg). The limit of detection for (emetine-CS(2))(2)Hg, emetine-CS(2)-methylmercury, emetine-CS(2)-ethylmercury, and emetine-CS(2)-phenylmercury were 30, 17, 21, and 22 ng L(-1), respectively. The sensitivity of this method enables the determination of mercury species in water samples at sub-ppb levels. Furthermore, the method was applied to biological samples in combination with acid leaching and liquid-liquid extraction using emetine-CS(2) as an extraction reagent. The determination results were in good agreement with the values of the certified reference materials.

  5. Ultrasensitive and rapid screening of mercury(II) ions by dual labeling colorimetric method in aqueous samples and applications in mercury-poisoned animal tissues

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yi; Wang, Xin; Xue, Feng [School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009 (China); Zheng, Lei [School of Medical Engineering, Hefei University of Technology, Hefei 230009 (China); Liu, Jian [School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009 (China); Yan, Feng [Applied Physics Department, Hong Kong Polytechnic University, Hong Kong (China); Xia, Fan, E-mail: xiafan@hust.edu.cn [School of Chemistry & Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Chen, Wei, E-mail: chenweishnu@163.com [School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009 (China)

    2015-04-08

    Highlights: • Rapid and ultrasensitive screening of mercury ions are achieved by using gold nanoparticles based colorimetric method. • Dual labeling strategy is adopted for sensing signal amplification. • The proposed method is successfully used for analysis of mercury-poisoned animal tissues. - Abstract: Rapid and ultrasensitive detection of trace heavy metal mercury(II) ions (Hg{sup 2+}) are of significant importance due to the induced serious risks for environment and human health. This presented article reports the gold nanoparticle-based dual labeling colorimetric method (Dual-COLO) for ultrasensitive and rapid detection of Hg{sup 2+} using the specific thymine–Hg{sup 2+}–thymine (T–Hg{sup 2+}–T) as recognition system and the dual labeling strategy for signal amplification. Both qualitative and quantitative detections of Hg{sup 2+} are achieved successfully in aqueous samples. More importantly, the achieved detection limit of 0.005 ng mL{sup −1} (0.025 nM) without any instruments is very competitive to other rapid detection methods even ICP-MS based methods. This Dual-COLO method is also applied directly for real water sample monitoring and, more importantly, applied in analysis of mercury poisoned animal tissues and body fluidic samples, indicating a potentially powerful and promising tool for environmental monitoring and food safety control.

  6. Indirect Determination of Mercury Ion by Inhibition of a Glucose Biosensor Based on ZnO Nanorods

    Directory of Open Access Journals (Sweden)

    Magnus Willander

    2012-11-01

    Full Text Available A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD on ZnO nanorods (ZnO-NRs has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS. The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10−6 mM to 0.5 × 10−4 mM, and from 0.5 × 10−4 mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10−3 mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users.

  7. Surface plasmon resonance sensing detection of mercury and lead ions based on conducting polymer composite.

    Directory of Open Access Journals (Sweden)

    Mahnaz M Abdi

    Full Text Available A new sensing area for a sensor based on surface plasmon resonance (SPR was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+ and Hg(2+ ions. The Pb(2+ ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+ compared to Hg(2+. The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.

  8. Testing Mercury Porosimetry with 3D Printed Porosity Models

    Science.gov (United States)

    Hasiuk, F.; Ewing, R. P.; Hu, Q.

    2014-12-01

    Mercury intrusion porosimetry is one of the most widely used techniques to study the porous nature of a geological and man-made materials. In the geosciences, it is commonly used to describe petroleum reservoir and seal rocks as well as to grade aggregates for the design of asphalt and portland cement concretes. It's wide utility stems from its ability to characterize a wide range of pore throat sizes (from nanometers to around a millimeter). The fundamental physical model underlying mercury intrusion porosimetry, the Washburn Equation, is based on the assumption that rock porosity can be described as a bundle of cylindrical tubes. 3D printing technology, also known as rapid prototyping, allows the construction of intricate and accurate models, exactly what is required to build models of rock porosity. We evaluate the applicability of the Washburn Equation by comparing properties (like porosity, pore and pore throat size distribution, and surface area) computed on digital porosity models (built from CT data, CAD designs, or periodic geometries) to properties measured via mercury intrusion porosimetry on 3D printed versions of the same digital porosity models.

  9. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-12-01

    Full Text Available Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by

  10. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-08-01

    Full Text Available Global models of atmospheric mercury generally assume that OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by the Hg + Br model. Model

  11. Preparation of chitosan-graft-polyacrylamide magnetic composite microspheres for enhanced selective removal of mercury ions from water.

    Science.gov (United States)

    Li, Kun; Wang, Yawen; Huang, Mu; Yan, Han; Yang, Hu; Xiao, Shoujun; Li, Aimin

    2015-10-01

    A novel magnetic composite microsphere based on polyacrylamide (PAM)-grafted chitosan and silica-coated Fe3O4 nanoparticles (CS-PAM-MCM) was successfully synthesized by a simple method. The molecular structure, surface morphology, and magnetic characteristics of the composite microsphere were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating-sample magnetometer (VSM), and scanning electron microscopy (SEM). The prepared CS-PAM-MCM was applied as an efficient adsorbent for the removal of copper(II), lead(II), and mercury(II) ions from aqueous solutions in respective single, binary, and ternary metal systems. Compared with chitosan magnetic composite microsphere (CS-MCM) without modification, CS-PAM-MCM showed improved adsorption capacity for each metal ion and highly selective adsorption for Hg from Pb and Cu. This improvement is attributed to the formation of stronger interactions between Hg and the amide groups of PAM branches for chelating effects. The adsorption isotherms of Hg/Cu and Hg/Pb binary metal systems onto CS-PAM-MCM are both well-described by extended and modified Langmuir models, indicating that the removal of the three aforementioned metal ions may follow a similar adsorption manner; that is, through a homogeneous monolayer chemisorption process. Furthermore, these magnetic adsorbents could be easily regenerated in EDTA aqueous solution and reused virtually without any adsorption capacity loss. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Evaluation of discrepancy between measured and modelled oxidized mercury species

    Directory of Open Access Journals (Sweden)

    G. Kos

    2013-05-01

    Full Text Available L. Zhang et al. (2012, in a recent report, compared model estimates with new observations of oxidized and particulate mercury species (Hg2+ and Hgp in the Great Lakes region and found that the sum of Hg2+ and Hgp varied between a factor of 2 to 10 between measurements and model. They suggested too high emission inputs as Hg2+ and too fast oxidative conversion of Hg0 to Hg2+ and Hgp as possible causes. This study quantitatively explores measurement uncertainties in detail. These include sampling efficiency, composition of sample, interfering species and calibration errors. Model (Global/Regional Atmospheric Heavy Metals Model – GRAHM sensitivity experiments are used to examine the consistency between various Hg measurements and speciation of Hg near emission sources to better understand the discrepancies between modelled and measured concentrations of Hg2+ and Hgp. We find that the ratio of Hg0, Hg2+ and Hgp in the emission inventories, measurements of surface air concentrations of oxidized Hg and measurements of wet deposition are currently inconsistent with each other in the vicinity of emission sources. Current speciation of Hg emissions suggests higher concentrations of Hg2+ in air and in precipitation near emission sources; however, measured air concentrations of Hg2+ and measured concentrations of Hg in precipitation are not found to be significantly elevated near emission sources compared to the remote regions. The averaged unbiased root mean square error (RMSE between simulated and observed concentrations of Hg2+ is found to be reduced by 42% and for Hgp reduced by 40% for 21 North American sites investigated, when a ratio for Hg0 : Hg2+ : Hgp in the emissions is changed from 50 : 40 : 10 (as specified in the original inventories to 90 : 8 : 2. Unbiased RMSE reductions near emissions sources in the eastern United States and Canada are found to be reduced by up to 58% for Hg2+. Significant improvement in the model simulated spatial

  13. Simple and rapid mercury ion selective electrode based on 1-undecanethiol assembled Au substrate and its recognition mechanism.

    Science.gov (United States)

    Li, Xian-Qing; Liang, Hai-Qing; Cao, Zhong; Xiao, Qing; Xiao, Zhong-Liang; Song, Liu-Bin; Chen, Dan; Wang, Fu-Liang

    2017-03-01

    A simple and rapid mercury ion selective electrode based on 1-undecanethiol (1-UDT) assembled Au substrate (Au/1-UDT) has been well constructed. 1-UDT was for the purpose of generating self-assembled monolayer on gold surface to recognize Hg(2+) in aqueous solution, which had a working concentration range of 1.0×10(-8)-1.0×10(-4)molL(-1), with a Nernst response slope of 28.83±0.4mV/-pC, a detection limit of 4.5×10(-9)molL(-1), and a good selectivity over the other tested cations. Also, the Au/1-UDT possessed good reproducibility, stability, and short response time. The recovery obtained for the determination of mercury ion in practical tremella samples was in the range of 99.8-103.4%. Combined electrochemical analysis and X-ray photoelectron spectroscopy (XPS) with quantum chemical computation, the probable recognition mechanism of the electrode for selective recognition of Hg(2+) has been investigated. The covalent bond formed between mercury and sulfur is stronger than the one between gold and sulfur and thus prevents the adsorption of 1-UDT molecules on the gold surface. The quantum chemical computation with density functional theory further demonstrates that the strong interaction between the mercury atom and the sulfur atom on the gold surface leads to the gold sulfur bond ruptured and the gold mercury metallophilic interaction.

  14. A spirobifluorene-based two-photon fluorescence probe for mercury ions and its applications in living cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Haibo, E-mail: xiaohb@shnu.edu.cn; Zhang, Yanzhen; Zhang, Wu; Li, Shaozhi; Tan, Jingjing; Han, Zhongying

    2017-05-01

    A novel spirobifluorene derivative SPF-TMS, which containing dithioacetal groups and triphenylamine units, was synthesized. The probing behaviors toward various metal ions were investigated via UV/Vis absorption spectra as well as one-photon fluorescence changes. The results indicated that SPF-TMS exhibits high sensitivity and selectivity for mercury ions. The detection limit was at least 8.6 × 10{sup −8}M, which is excellent comparing with other optical sensors for Hg{sup 2+}. When measured by two-photon excited fluorescence technique in THF at 800 nm, the two-photon cross-section of SPF-TMS is 272 GM. Especially, upon reaction with mercury species, SPF-TMS yielded another two-photon dye SPF-DA. Both SPF-TMS and SPF-DA emit strong two-photon induced fluorescence and can be applied in cell imaging by two-photon microscopy. - Highlights: • We report a spirobifluorene-based molecule as two-photon fluorescent probe with large two-photon cross-section. • The molecule has exclusive selectivity and sensitivity for mercury species. • The molecule has large two-photon emission changes before and after addition of Hg{sup 2+}. • Both the probe and the mercury ion-promoted reaction product can be applied in cell imaging by two-photon microscopy.

  15. Mercury's Dynamic Magnetic Tail

    Science.gov (United States)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

  16. Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: Behaviours and mechanisms

    Science.gov (United States)

    Bao, Shuangyou; Li, Kai; Ning, Ping; Peng, Jinhui; Jin, Xu; Tang, Lihong

    2017-01-01

    A novel hybrid material was fabricated using mercaptoamine-functionalised silica-coated magnetic nanoparticles (MAF-SCMNPs) and was effective in the extraction and recovery of mercury and lead ions from wastewater. The properties of this new magnetic material were explored using various characterisation and analysis methods. Adsorbent amounts, pH levels and initial concentrations were optimised to improve removal efficiency. Additionally, kinetics, thermodynamics and adsorption isotherms were investigated to determine the mechanism by which the fabricated MAF-SCMNPs adsorb heavy metal ions. The results revealed that MAF-SCMNPs were acid-resistant. Sorption likely occurred by chelation through the amine group and ion exchange between heavy metal ions and thiol functional groups on the nanoadsorbent surface. The equilibrium was attained within 120 min, and the adsorption kinetics showed pseudo-second-order (R2 > 0.99). The mercury and lead adsorption isotherms were in agreement with the Freundlich model, displaying maximum adsorption capacities of 355 and 292 mg/g, respectively. The maximum adsorptions took place at pH 5-6 and 6-7 for Hg(II) and Pb(II), respectively. The maximum adsorptions were observed at 10 mg and 12 mg adsorbent quantities for Hg(II) and Pb(II), respectively. The adsorption process was endothermic and spontaneous within the temperature range of 298-318 K. This work demonstrates a unique magnetic nano-adsorbent for the removal of Hg(II) and Pb(II) from wastewater.

  17. Removal of mercury(II) ions in aqueous solution using the peel biomass of Pachira aquatica Aubl: kinetics and adsorption equilibrium studies.

    Science.gov (United States)

    Santana, Andrea J; dos Santos, Walter N L; Silva, Laiana O B; das Virgens, Cesário F

    2016-05-01

    Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g(-1) at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent.

  18. Modeling study of natural emissions, source apportionment, and emission control of atmospheric mercury

    Science.gov (United States)

    Shetty, Suraj K.

    Mercury (Hg) is a toxic pollutant and is important to understand its cycling in the environment. In this dissertation, a number of modeling investigations were conducted to better understand the emission from natural surfaces, the source-receptor relationship of the emissions, and emission reduction of atmospheric mercury. The first part of this work estimates mercury emissions from vegetation, soil and water surfaces using a number of natural emission processors and detailed (LAI) Leaf Area Index data from GIS (Geographic Information System) satellite products. East Asian domain was chosen as it contributes nearly 50% of the global anthropogenic mercury emissions into the atmosphere. The estimated annual natural mercury emissions (gaseous elemental mercury) in the domain are 834 Mg yr-1 with 462 Mg yr-1 contributing from China. Compared to anthropogenic sources, natural sources show greater seasonal variability (highest in simmer). The emissions are significant, sometimes dominant, contributors to total mercury emission in the regions. The estimates provide possible explanation for the gaps between the anthropogenic emission estimates based on activity data and the emission inferred from field observations in the regions. To understand the contribution of domestic emissions to mercury deposition in the United States, the second part of the work applies the mercury model of Community Multi-scale Air Quality Modeling system (CMAQ-Hg v4.6) to apportion the various emission sources attributing to the mercury wet and dry deposition in the 6 United States receptor regions. Contributions to mercury deposition from electric generating units (EGU), iron and steel industry (IRST), industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC) in domain was estimated. The model results for 2005 compared reasonably well to field observations made by MDN (Mercury Deposition Network

  19. Digital Elevation Model Mosaic of Mercury

    Science.gov (United States)

    Cook, A. C.; Watters, T. R.; Robinson, M. S.

    2001-01-01

    At CEPS (Center for Earth and Planetary Studies) work has been underway since 2000 to semi-automatically stereo match all Mariner 10 stereo pairs. The resulting matched image coordinates are converted into longitude, latitude, and height points and then combined to form a map projected Digital Elevation Model (DEM) mosaic of the planet's surface. Stereo images from Mariner 10 cover one quarter of the planet's surface, mostly in the southern hemisphere. Additional information is contained in the original extended abstract.

  20. Influence of anions on methylpyridinium ion adsorption on the mercury electrode in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gerovich, V.M.; Damaskin, B.B.; Ermolin, V.B.

    1987-02-01

    The adsorption behavior of aromatic and heterocyclic cations is known to be determined by image forces on one hand and by pi-electron interaction on the other. The first factor is effective at the negatively charged surface of the mercury electrode whereas the second factor is effective at the positively charged surface where the forces of pi-electron interaction are in opposition to the electrostatic repulsion forces of the cations. The authors of this paper study the adsorption of methylpyridinium as the aromatic cation in combination with persulfate, chlorine, bromine, and iodine as the anions. The potential range studied was limited on the anodic side by a potential of -0.1 eV, since the values of interfacial tension were poorly reproducible at more positive potentials, and on the cathodic side by a potential of -1.1 eV, since methylpyridinium is reduced at more negative potentials. It is found that the halide ions, owing to the possible formation of charge transfer complexes, have an even stronger effect on the adsorption behavior of organic cations than that observed previously for tetraalkylammonium ions.

  1. Calix[4]pyrrole derivative: recognition of fluoride and mercury ions and extracting properties of the receptor-based new material.

    Science.gov (United States)

    de Namor, Angela F Danil; Khalife, Rasha

    2008-12-11

    A calix[4]pyrrole derivative, namely, meso-tetramethyl tetrakis (4-phenoxy methyl ketone) calix[4]pyrrole, 1, was synthesized and structurally (1H NMR) and thermodynamically characterized. The complexing properties of this receptor with a wide variety of anions and cations in dipolar aprotic media (acetonitrile, propylene carbonate, and dimethyl sulfoxide) were investigated through 1H NMR and conductance studies. The former technique was used to assess whether or not complexation occurs and if so to identify the active sites of interaction of 1 with ions. The composition of the complexes was established by conductance measurements. It was found that in dipolar aprotic solvents, 1 interacts only with two polluting ions (fluoride and mercury). The complexation thermodynamics of 1 and these ions in these solvents is reported. The medium effect on the binding process involving the fluoride ion is discussed taking into account the solvation properties of reactants and the product. Complexes of moderate stability are found. Given that this is an important factor to consider for the recycling of the loaded material in extraction processes, 1 was treated with formaldehyde in basic medium leading to the production of a calix[4]pyrrole based material able to extract fluoride and mercury (II) ions from water. Thus the optimum conditions for the extraction of these ions from aqueous solutions were established. The material is easily recyclable using an organic acid. Final conclusions are given.

  2. Femtomole level photoelectrochemical aptasensing for mercury ions using quercetin-copper(II) complex as the DNA intercalator.

    Science.gov (United States)

    Li, Hongbo; Xue, Yan; Wang, Wei

    2014-04-15

    An ultrasensitive and selective photoelectrochemical (PEC) aptasensor for mercury ions was first fabricated based on perylene-3, 4, 9, 10-tetracarboxylic acid/graphene oxide (PTCA/GO) heterojunction using quercetin-copper(II) complex intercalated into the poly(dT)-poly(dA) duplexes. Both the PTCA/GO heterojunction and the quercetin-copper(II) complex are in favor of the sensitivity for the fabricated PEC aptasensor due to band alignment and strong reduction capability, respectively. And they efficiently promote the separation of photoexcited carriers and enhance the photocurrent. The formation of thymine-Hg(2+)-thymine coordination chemistry resulted in the dehybridization of poly(dT)-poly(dA) duplexes and then the intercalator quercetin-copper(II) complex broke away from the surface of the PEC aptasensor. As the concentration of mercury ions increased, the photocurrent gradually decreased. The electrode response for mercury ions detection was in the linear range from 0.01 pmol L(-1) to 1.00 pmol L(-1) with the detection limit of 3.33 fmol L(-1). The label-free PEC aptasensor has excellent performances with ultrasensitivity and good selectivity besides the advantage of economic and facile fabrication. The strategy of quercetin-copper(II) complex as a novel DNA intercalator paves a new way to improve the performances for PEC sensors. © 2013 Published by Elsevier B.V.

  3. Modeling the Lithium Ion Battery

    Science.gov (United States)

    Summerfield, John

    2013-01-01

    The lithium ion battery will be a reliable electrical resource for many years to come. A simple model of the lithium ions motion due to changes in concentration and voltage is presented. The battery chosen has LiCoO[subscript 2] as the cathode, LiPF[subscript 6] as the electrolyte, and LiC[subscript 6] as the anode. The concentration gradient and…

  4. Modeling the Lithium Ion Battery

    Science.gov (United States)

    Summerfield, John

    2013-01-01

    The lithium ion battery will be a reliable electrical resource for many years to come. A simple model of the lithium ions motion due to changes in concentration and voltage is presented. The battery chosen has LiCoO[subscript 2] as the cathode, LiPF[subscript 6] as the electrolyte, and LiC[subscript 6] as the anode. The concentration gradient and…

  5. CHARACTERIZATION AND MODELING OF THE FORMS OF MERCURY FROM COAL-FIRED POWER PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Dennis L. Laudal

    2001-08-01

    The 1990 Clean Air Act Amendments (CAAAs) required the U.S. Environmental Protection Agency (EPA) to determine whether the presence of mercury in the stack emissions from fossil fuel-fired electric utility power plants poses an unacceptable public health risk. EPA's conclusions and recommendations were presented in the Mercury Study Report to Congress (1) and the Utility Air Toxics Report to Congress (1). The first report addressed both the human health and environmental effects of anthropogenic mercury emissions, while the second addressed the risk to public health posed by the emission of mercury and other hazardous air pollutants from steam-electric generating units. Given the current state of the art, these reports did not state that mercury controls on coal-fired electric power stations would be required. However, they did indicate that EPA views mercury as a potential threat to human health. In fact, in December 2000, the EPA issued an intent to regulate for mercury from coal-fired boilers. However, it is clear that additional research needs to be done in order to develop economical and effective mercury control strategies. To accomplish this objective, it is necessary to understand mercury behavior in coal-fired power plants. The markedly different chemical and physical properties of the different mercury forms generated during coal combustion appear to impact the effectiveness of various mercury control strategies. The original Characterization and Modeling of the Forms of Mercury from Coal-Fired Power Plants project had two tasks. The first was to collect enough data such that mercury speciation could be predicted based on relatively simple inputs such as coal analyses and plant configuration. The second was to field-validate the Ontario Hydro mercury speciation method (at the time, it had only been validated at the pilot-scale level). However, after sampling at two power plants (the Ontario Hydro method was validated at one of them), the EPA issued

  6. Alkaline hydrothermal conversion of fly ash precipitates into zeolites 3: The removal of mercury and lead ions from wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Vernon Somerset; Leslie Petrik; Emmanuel Iwuoha [University of the Western Cape, Bellville (South Africa). Sensor Research Laboratory, Department of Chemistry

    2008-04-15

    In this paper, the utilisation of zeolites synthesised from fly ash (FA) and related co-disposal filtrates as low-cost adsorbent material were investigated. When raw FA and co-disposal filtrates were subjected to alkaline hydrothermal zeolite synthesis, the zeolites faujasite, sodalite and zeolite A were formed. The synthesised zeolites were explored to establish its ability to remove lead and mercury ions from aqueous solution in batch experiments, to which various dosages of the synthesised zeolites were added. The test results indicated that when increasing synthesised zeolite dosages of 5-20 g/L were added to the acid mine drainage (AMD) wastewater, the concentrations of lead and mercury in the wastewater were reduced accordingly. The lead concentrations were reduced from 3.23 to 0.38 and 0.17 {mu}g/kg, respectively, at an average pH of 4.5, after the addition of raw FA zeolite and co-disposal filtrate zeolite to the AMD wastewater. On the other hand, the mercury concentration was reduced from 0.47 to 0.17 {mu}g/kg at pH=4.5 when increasing amounts of co-disposal filtrate zeolite were added to the wastewater. The experimental results had shown that the zeolites synthesised from the co-disposal filtrates were effective in reducing the lead and mercury concentrations in the AMD wastewater by 95% and 30%, respectively.

  7. Alkaline hydrothermal conversion of fly ash precipitates into zeolites 3: the removal of mercury and lead ions from wastewater.

    Science.gov (United States)

    Somerset, Vernon; Petrik, Leslie; Iwuoha, Emmanuel

    2008-04-01

    In this paper, the utilisation of zeolites synthesised from fly ash (FA) and related co-disposal filtrates as low-cost adsorbent material were investigated. When raw FA and co-disposal filtrates were subjected to alkaline hydrothermal zeolite synthesis, the zeolites faujasite, sodalite and zeolite A were formed. The synthesised zeolites were explored to establish its ability to remove lead and mercury ions from aqueous solution in batch experiments, to which various dosages of the synthesised zeolites were added. The test results indicated that when increasing synthesised zeolite dosages of 5-20 g/L were added to the acid mine drainage (AMD) wastewater, the concentrations of lead and mercury in the wastewater were reduced accordingly. The lead concentrations were reduced from 3.23 to 0.38 and 0.17 microg/kg, respectively, at an average pH of 4.5, after the addition of raw FA zeolite and co-disposal filtrate zeolite to the AMD wastewater. On the other hand, the mercury concentration was reduced from 0.47 to 0.17 microg/kg at pH=4.5 when increasing amounts of co-disposal filtrate zeolite were added to the wastewater. The experimental results had shown that the zeolites synthesised from the co-disposal filtrates were effective in reducing the lead and mercury concentrations in the AMD wastewater by 95% and 30%, respectively.

  8. Green synthesis of silver nanoparticles using Carica Papaya fruit extract under sunlight irradiation and their colorimetric detection of mercury ions

    Science.gov (United States)

    Firdaus, M.; Andriana, S.; Elvinawati; Alwi, W.; Swistoro, E.; Ruyani, A.; Sundaryono, A.

    2017-04-01

    We have successfully synthesized silver nanoparticles (AgNPs) by using aqueous extract of papaya (Carica papaya) fruit as bioreductant under sunlight irradiation without additional capping agent. Characterizations were done using UV-Visible spectrophotometry and Fourier Transform Infrared Spectroscopy (FTIR). The synthesized AgNPs have yellowish-brown color with surface plasmon resonance peak at 410 nm. Good selectivity of the AgNPs towards hazardous heavy metal of mercury ions in aqueous solution has been developed as a green environmental sensor. The presence of Hg(II) ions in the mixture changed the yellowish-brown color of AgNPs to colorless due to oxidation of Ag(O) in AgNPs to Ag(I) ions. Effect of samples matrix such as alkali metal, alkaline earth metal and transition metal ions were evaluated.

  9. ECHMERIT: A new on-line global mercury-chemistry model

    Science.gov (United States)

    Jung, G.; Hedgecock, I. M.; Pirrone, N.

    2009-04-01

    Mercury is a volatile metal, that is of concern because when deposited and transformed to methylmercury accumulates within the food-web. Due to the long lifetime of elemental mercury, which is the dominant fraction of mercury species in the atmosphere, mercury is prone to long-range transport and therefore distributed over the globe, transported and hence deposited even in regions far from anthropogenic emission sources. Mercury is released to the atmosphere from a variety of natural and anthropogenic sources, in elementary and oxidised forms, and as particulate mercury. It is then transported, but also transformed chemically in the gaseous phase, as well as in aqueous phase within cloud and rain droplets. Mercury (particularly its oxidised forms) is removed from the atmosphere though wet and dry deposition processes, a large fraction of deposited mercury is, after chemical or biological reduction, re-emitted to the atmosphere as elementary mercury. To investigate mercury chemistry and transport processes on the global scale, the new, global model ECHMERIT has been developed. ECHMERIT simulates meteorology, transport, deposition, photolysis and chemistry on-line. The general circulation model on which ECHMERIT is based is ECHAM5. Sophisticated chemical modules have been implemented, including gas phase chemistry based on the CBM-Z chemistry mechanism, as well as aqueous phase chemistry, both of which have been adapted to include Hg chemistry and Hg species gas-droplet mass transfer. ECHMERIT uses the fast-J photolysis routine. State-of-the-art procedures simulating wet and dry deposition and emissions were adapted and included in the model as well. An overview of the model structure, development, validation and sensitivity studies is presented.

  10. Impact of mercury emissions from historic gold and silver mining: Global modeling

    Science.gov (United States)

    Strode, Sarah; Jaeglé, Lyatt; Selin, Noelle E.

    We compare a global model of mercury to sediment core records to constrain mercury emissions from the 19th century North American gold and silver mining. We use information on gold and silver production, the ratio of mercury lost to precious metal produced, and the fraction of mercury lost to the atmosphere to calculate an a priory mining inventory for the 1870s, when the historical gold rush was at its highest. The resulting global mining emissions are 1630 Mg yr -1, consistent with previously published studies. Using this a priori estimate, we find that our 1880 simulation over-predicts the mercury deposition enhancements archived in lake sediment records. Reducing the mining emissions to 820 Mg yr -1 improves agreement with observations, and leads to a 30% enhancement in global deposition in 1880 compared to the pre-industrial period. For North America, where 83% of the mining emissions are located, deposition increases by 60%. While our lower emissions of atmospheric mercury leads to a smaller impact of the North American gold rush on global mercury deposition than previously estimated, it also implies that a larger fraction of the mercury used in extracting precious metals could have been directly lost to local soils and watersheds.

  11. Highly sensitive electrochemical sensor for mercury(II) ions by using a mercury-specific oligonucleotide probe and gold nanoparticle-based amplification.

    Science.gov (United States)

    Zhu, Zhiqiang; Su, Yuanyuan; Li, Jiang; Li, Di; Zhang, Jiong; Song, Shiping; Zhao, Yun; Li, Genxi; Fan, Chunhai

    2009-09-15

    We report a highly sensitive electrochemical sensor for the detection of Hg(2+) ions in aqueous solution by using a thymine (T)-rich, mercury-specific oligonucleotide (MSO) probe and gold nanoparticles (Au NPs)-based signal amplification. The MSO probe contains seven thymine bases at both ends and a "mute" spacer in the middle, which, in the presence of Hg(2+), forms a hairpin structure via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. The thiolated MSO probe is immobilized on Au electrodes to capture free Hg(2+) in aqueous media, and the MSO-bound Hg(2+) can be electrochemically reduced to Hg(+), which provides a readout signal for quantitative detection of Hg(2+). This direct immobilization strategy leads to a detection limit of 1 microM. In order to improve the sensitivity, MSO probe-modified Au NPs are employed to amplify the electrochemical signals. Au NPs are comodified with the MSO probe and a linking probe that is complementary to a capture DNA probe immobilized on gold electrodes. We demonstrated that this Au NPs-based sensing strategy brings about an amplification factor of more than 3 orders of magnitude, leading to a limit of detection of 0.5 nM (100 ppt), which satisfactorily meets the sensitivity requirement of U.S. Environmental Protection Agency (EPA). This Au NPs-based Hg(2+) sensor also exhibits excellent selectivity over a spectrum of interference metal ions. Considering the high sensitivity and selectivity of this sensor, as well as the cost-effective and portable features of electrochemical techniques, we expect this Au NPs amplified electrochemical sensor will be a promising candidate for field detection of environmentally toxic mercury.

  12. Adsoption Model of Mercury in the Water-Sediment Systems in Riam Kanan Dam, South Kalimantan

    Directory of Open Access Journals (Sweden)

    Utami Irawati

    2014-06-01

    Full Text Available The Riam Kanan  Dam reservoir is one of living source for the people of South Kalimantan and has a strategic value for their prosperity. Traditional and illegal mining activities nearby the area of this dam may cause heavy metals pollution, such as mercury (Hg in the water and sediment. This research was conducted to predict  the adsorption model of mercury (Hg in water and sediment system in Riam Kanan reservoir  Banjar regency.  The modeling was carried out by analyzing the content of mercury (Hg in the water  and sediments. The result was then plotted into Freundlich and Langmuir models. The determination coefficient for each of the models were 0.947 and 0.388 respectively. It can be concluded that the transport of mercury (Hg from water bodies  onto the sediment complies with Freundlich model.

  13. Vaporization wave model for ion-ion central collisions

    Energy Technology Data Exchange (ETDEWEB)

    Baldo, M.; Giansiracusa, G.; Piccitto, G. (Catania Univ. (Italy). Ist. di Fisica; Istituto Nazionale di Fisica Nucleare, Catania (Italy))

    1983-09-24

    We propose a simple model for central or nearly central ion-ion collisions at intermediate energies. It is based on the ''vaporization wave model'' developed by Bennett for macroscopic objects. The model offers a simple explanation of the observed deuteron/proton abundancy ratio as a function of the beam energy.

  14. Vaporization wave model for ion-ion central collisions

    Energy Technology Data Exchange (ETDEWEB)

    Baldo, M.; Giansiracusa, G.; Piccitto, G. (Catania Univ. (Italy). Ist. di Fisica)

    1983-09-24

    A simple model for central or nearly central ion-ion collisions at intermediate energies is proposed. It is based on the ''vaporization wave model'' developed by Bennet for macroscopic objects. The model offers a simple explanation of the observed deuteron/proton abundancy ratio as a function of the beam energy.

  15. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

    2009-06-15

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  16. Sensitive detection of mercury (II) ion using water-soluble captopril-stabilized fluorescent gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jiu-Ju; Huang, Hong; Chen, Wei-Jie; Chen, Jian-Rong; Lin, Hong-Jun; Wang, Ai-Jun, E-mail: ajwang@zjnu.cn

    2013-07-01

    In our work, a simple, facile, and green method was developed for the synthesis of water-soluble and well-dispersed fluorescent gold nanoparticles (Au NPs) within 5 min, using captopril as a capping agent. The as-prepared Au NPs showed strong emission at 414 nm, with a quantum yield of 5.5%. The fluorescence of the Au NPs can be strongly quenched by mercury (II) ion (Hg{sup 2+}) due to the stronger interactions between thiolates (RS{sup −}) and Hg{sup 2+}. It was applied to the detection of Hg{sup 2+} in water samples in the linear ranges of 0.033–0.133 μM and 0.167–2.500 μM, with a detection limit of 0.017 μM. Therefore, the as-prepared Au NPs can meet the requirement for monitoring Hg{sup 2+} in environmental samples. - Graphical abstract: In this work, we developed a simple, fast and facile method for the preparation of water-soluble and fluorescent gold nanoparticles (Au NPs). The trace existence of Hg{sup 2+} could strongly quench the fluorescence of the Au NPs. The Au NPs were used to detect highly toxic Hg{sup 2+} in water samples with high sensitivity and selectivity. Highlights: ► Water-soluble fluorescent Au NPs stabilized by captopril ► The synthesis procedure was simple, fast and facile. ► The fluorescence of the Au NPs can be strongly quenched by Hg{sup 2+}. ► The Au NPs were used to the assay of Hg{sup 2+} in water samples with high sensitivity and selectivity.

  17. How relevant is the deposition of mercury onto snowpacks? – Part 2: A modeling study

    Directory of Open Access Journals (Sweden)

    D. Durnford

    2012-10-01

    Full Text Available An unknown fraction of mercury that is deposited onto snowpacks is revolatilized to the atmosphere. Determining the revolatilized fraction is important since mercury that enters the snowpack meltwater may be converted to highly toxic bioaccumulating methylmercury. In this study, we present a new dynamic physically-based snowpack/meltwater model for mercury that is suitable for large-scale atmospheric models for mercury. It represents the primary physical and chemical processes that determine the fate of mercury deposited onto snowpacks. The snowpack/meltwater model was implemented in Environment Canada's atmospheric mercury model GRAHM. For the first time, observed snowpack-related mercury concentrations are used to evaluate and constrain an atmospheric mercury model. We find that simulated concentrations of mercury in both snowpacks and the atmosphere's surface layer agree closely with observations. The simulated concentration of mercury in both in the top 30 cm and the top 150 cm of the snowpack, averaged over 2005–2009, is predominantly below 6 ng L−1 over land south of 66.5° N but exceeds 18 ng L−1 over sea ice in extensive areas of the Arctic Ocean and Hudson Bay. The average simulated concentration of mercury in snowpack meltwater runoff tends to be higher on the Russian/European side (>20 ng L−1 of the Arctic Ocean than on the Canadian side (<10 ng L−1. The correlation coefficient between observed and simulated monthly mean atmospheric surface-level gaseous elemental mercury (GEM concentrations increased significantly with the inclusion of the new snowpack/meltwater model at two of the three stations (midlatitude, subarctic studied and remained constant at the third (arctic. Oceanic emissions are postulated to produce the observed summertime maximum in concentrations of surface-level atmospheric GEM at Alert in the Canadian Arctic and to generate the summertime volatility observed in

  18. Model analyses of atmospheric mercury: present air quality and effects of transpacific transport on the United States

    Directory of Open Access Journals (Sweden)

    H. Lei

    2013-04-01

    Full Text Available Atmospheric mercury is a toxic air and water pollutant that is of significant concern because of its effects on human health and ecosystems. A mechanistic representation of the atmospheric mercury cycle is developed for the state-of-the-art global climate-chemistry model, CAM-Chem (Community Atmospheric Model with Chemistry. The model simulates the emission, transport, transformation and deposition of atmospheric mercury (Hg in three forms: elemental mercury (Hg(0, reactive mercury (Hg(II, and particulate mercury (PHg. Emissions of mercury include those from human, land, ocean, biomass burning and volcano related sources. Land emissions are calculated based on surface solar radiation flux and skin temperature. A simplified air–sea mercury exchange scheme is used to calculate emissions from the oceans. The chemistry mechanism includes the oxidation of Hg(0 in gaseous phase by ozone with temperature dependence, OH, H2O2 and chlorine. Aqueous chemistry includes both oxidation and reduction of Hg(0. Transport and deposition of mercury species are calculated through adapting the original formulations in CAM-Chem. The CAM-Chem model with mercury is driven by present meteorology to simulate the present mercury air quality during the 1999–2001 periods. The resulting surface concentrations of total gaseous mercury (TGM are then compared with the observations from worldwide sites. Simulated wet depositions of mercury over the continental United States are compared to the observations from 26 Mercury Deposition Network stations to test the wet deposition simulations. The evaluations of gaseous concentrations and wet deposition confirm a strong capability for the CAM-Chem mercury mechanism to simulate the atmospheric mercury cycle. The results also indicate that mercury pollution in East Asia and Southern Africa is very significant with TGM concentrations above 3.0 ng m−3. The comparison to wet deposition indicates that wet deposition patterns of

  19. Mercury emission and dispersion models from soils contaminated by cinnabar mining and metallurgy.

    Science.gov (United States)

    Llanos, Willians; Kocman, David; Higueras, Pablo; Horvat, Milena

    2011-12-01

    The laboratory flux measurement system (LFMS) and dispersion models were used to investigate the kinetics of mercury emission flux (MEF) from contaminated soils. Representative soil samples with respect to total Hg concentration (26-9770 μg g(-1)) surrounding a decommissioned mercury-mining area (Las Cuevas Mine), and a former mercury smelter (Cerco Metalúrgico de Almadenejos), in the Almadén mercury mining district (South Central Spain), were collected. Altogether, 14 samples were analyzed to determine the variation in mercury emission flux (MEF) versus distance from the sources, regulating two major environmental parameters comprising soil temperature and solar radiation. In addition, the fraction of the water-soluble mercury in these samples was determined in order to assess how MEF from soil is related to the mercury in the aqueous soil phase. Measured MEFs ranged from less than 140 to over 10,000 ng m(-2) h(-1), with the highest emissions from contaminated soils adjacent to point sources. A significant decrease of MEF was then observed with increasing distance from these sites. Strong positive effects of both temperature and solar radiation on MEF was observed. Moreover, MEF was found to occur more easily in soils with higher proportions of soluble mercury compared to soils where cinnabar prevails. Based on the calculated Hg emission rates and with the support of geographical information system (GIS) tools and ISC AERMOD software, dispersion models for atmospheric mercury were implemented. In this way, the gaseous mercury plume generated by the soil-originated emissions at different seasons was modeled. Modeling efforts revealed that much higher emissions and larger mercury plumes are generated in dry and warm periods (summer), while the plume is smaller and associated with lower concentrations of atmospheric mercury during colder periods with higher wind activity (fall). Based on the calculated emissions and the model implementation, yearly emissions from

  20. Application of polypyrrole multi-walled carbon nanotube composite layer for detection of mercury, lead and iron ions using surface plasmon resonance technique.

    Science.gov (United States)

    Sadrolhosseini, Amir Reza; Noor, A S M; Bahrami, Afarin; Lim, H N; Talib, Zainal Abidin; Mahdi, Mohd Adzir

    2014-01-01

    Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°.

  1. How relevant is the deposition of mercury onto snowpacks? – Part 2: A modeling study

    Directory of Open Access Journals (Sweden)

    D. Durnford

    2012-01-01

    Full Text Available An unknown fraction of mercury that is deposited onto snowpacks is revolatilized to the atmosphere. Determining the revolatilized fraction is important since mercury that enters the snowpack meltwater may be converted to highly toxic bioaccumulating methylmercury. In this study, we present a new dynamic physically-based snowpack/meltwater model for mercury that is suitable for large-scale atmospheric models for mercury. It represents the primary physical and chemical processes that determine the fate of mercury deposited onto snowpacks. The snowpack/meltwater model was implemented in Environment Canada's atmospheric mercury model GRAHM. For the first time, observed snowpack-related mercury concentrations are used to evaluate and constrain an atmospheric mercury model. We find that simulated concentrations of mercury in both snowpacks and the atmosphere's surface layer agree closely with observations. The simulated concentration of mercury in both in the top 30 cm and the top 150 cm of the snowpack, averaged over 2005–2009, is predominantly below 6 ng l−1 over land south of 66.5° N but exceeds 18 ng l−1 over sea ice in extensive areas of the Arctic Ocean and Hudson Bay. The average simulated concentration of mercury in snowpack meltwater runoff tends to be higher on the Russian/European side (>20 ng l−1 of the Arctic Ocean than on the Canadian side (<10 ng l−1. The correlation coefficient between observed and simulated monthly mean atmospheric surface-level GEM concentrations increased significantly with the inclusion of the new snowpack/meltwater model at two of the three stations (midlatitude, subarctic studied and remained constant at the third (arctic. Oceanic emissions are postulated to produce the observed summertime maximum in concentrations of surface-level atmospheric GEM at Alert in the Canadian Arctic and to generate the summertime volatility observed in these concentrations at

  2. Model analyses of atmospheric mercury: present air quality and effects of transpacific transport on the United States

    Science.gov (United States)

    Lei, H.; Liang, X.-Z.; Wuebbles, D. J.; Tao, Z.

    2013-11-01

    Atmospheric mercury is a toxic air and water pollutant that is of significant concern because of its effects on human health and ecosystems. A mechanistic representation of the atmospheric mercury cycle is developed for the state-of-the-art global climate-chemistry model, CAM-Chem (Community Atmospheric Model with Chemistry). The model simulates the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three forms: elemental mercury (Hg(0)), reactive mercury (Hg(II)), and particulate mercury (PHg). Emissions of mercury include those from human, land, ocean, biomass burning and volcano related sources. Land emissions are calculated based on surface solar radiation flux and skin temperature. A simplified air-sea mercury exchange scheme is used to calculate emissions from the oceans. The chemistry mechanism includes the oxidation of Hg(0) in gaseous phase by ozone with temperature dependence, OH, H2O2 and chlorine. Aqueous chemistry includes both oxidation and reduction of Hg(0). Transport and deposition of mercury species are calculated through adapting the original formulations in CAM-Chem. The CAM-Chem model with mercury is driven by present meteorology to simulate the present mercury air quality during the 1999-2001 period. The resulting surface concentrations of total gaseous mercury (TGM) are then compared with the observations from worldwide sites. Simulated wet depositions of mercury over the continental United States are compared to the observations from 26 Mercury Deposition Network stations to test the wet deposition simulations. The evaluations of gaseous concentrations and wet deposition confirm a strong capability for the CAM-Chem mercury mechanism to simulate the atmospheric mercury cycle. The general reproduction of global TGM concentrations and the overestimation on South Africa indicate that model simulations of TGM are seriously affected by emissions. The comparison to wet deposition indicates that wet deposition patterns

  3. Sensitivity model study of regional mercury dispersion in the atmosphere

    Science.gov (United States)

    Gencarelli, Christian N.; Bieser, Johannes; Carbone, Francesco; De Simone, Francesco; Hedgecock, Ian M.; Matthias, Volker; Travnikov, Oleg; Yang, Xin; Pirrone, Nicola

    2017-01-01

    Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, transport and chemical interactions of atmospheric Hg have been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high-resolution three-dimensional chemical transport models (CTMs), varying the anthropogenic emission datasets, atmospheric Br input fields, Hg oxidation schemes and modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg0(g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution are crucial to the simulated concentration and deposition fields, as is also the choice of Hg0(g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black seas, the English Channel, the Skagerrak Strait and the northern German coast. Considerable influence was found also evident over the Mediterranean, the North Sea and Baltic Sea and some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more HgII(g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O3 / OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg and to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat

  4. The Plasma Environment at Mercury

    Science.gov (United States)

    Raines, James M.; Gershman, Daniel J.; Zurbuchen, Thomas H.; Gloeckler, George; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Krimigis, Stamatios M.; Killen, Rosemary M.; Sarantos, Menalos; hide

    2011-01-01

    Mercury is the least explored terrestrial planet, and the one subjected to the highest flux of solar radiation in the heliosphere. Its highly dynamic, miniature magnetosphere contains ions from the exosphere and solar wind, and at times may allow solar wind ions to directly impact the planet's surface. Together these features create a plasma environment that shares many features with, but is nonetheless very different from, that of Earth. The first in situ measurements of plasma ions in the Mercury space environment were made only recently, by the Fast Imaging Plasma Spectrometer (FIPS) during the MESSENGER spacecraft's three flybys of the planet in 2008-2009 as the probe was en route to insertion into orbit about Mercury earlier this year. Here. we present analysis of flyby and early orbital mission data with novel techniques that address the particular challenges inherent in these measurements. First. spacecraft structures and sensor orientation limit the FIPS field of view and allow only partial sampling of velocity distribution functions. We use a software model of FIPS sampling in velocity space to explore these effects and recover bulk parameters under certain assumptions. Second, the low densities found in the Mercury magnetosphere result in a relatively low signal-to-noise ratio for many ions. To address this issue, we apply a kernel density spread function to guide removal of background counts according to a background-signature probability map. We then assign individual counts to particular ion species with a time-of-flight forward model, taking into account energy losses in the carbon foil and other physical behavior of ions within the instrument. Using these methods, we have derived bulk plasma properties and heavy ion composition and evaluated them in the context of the Mercury magnetosphere.

  5. Mercury Dispersion Modeling And Purge Ventilation Stack Height Determination For Tank 40H

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Giboyeaux, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-05-19

    The SRNL Atmospheric Technologies Group performed an analysis for mercury emissions from H-Tank Farm - Tank 40 ventilation system exhaust in order to assess whether the Short Term Exposure Limit (STEL), or Threshold Limit Value (TLV) levels for mercury will be exceeded during bulk sludge slurry mixing and sludge removal operations. The American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) was used as the main dispersion modelling tool for this analysis. The results indicated that a 45-foot stack is sufficient to raise the plume centerline from the Tank 40 release to prevent mercury exposure problems for any of the stack discharge scenarios provided. However, a 42-foot stack at Tank 40 is sufficient to prevent mercury exposure concerns in all emission scenarios except the 50 mg/m3 release. At a 42-foot stack height, values exceeding the exposure standards are only measured on receptors located above 34 feet.

  6. Investigation of effects of varying model inputs on mercury deposition estimates in the Southwest US

    Directory of Open Access Journals (Sweden)

    T. Myers

    2012-04-01

    Full Text Available The Community Multiscale Air Quality (CMAQ model version 4.7.1 was used to simulate mercury wet and dry deposition for a domain covering the contiguous United States (US. The simulations used MM5-derived meteorological input fields and the US Environmental Protection Agency (EPA Clear Air Mercury Rule (CAMR emissions inventory. Using sensitivity simulations with different boundary conditions and tracer simulations, this investigation focuses on the contributions of boundary concentrations to deposited mercury in the Southwest (SW US. Concentrations of oxidized mercury species along the boundaries of the domain, in particular the upper layers of the domain, can make significant contributions to the simulated wet and dry deposition of mercury in the SW US. In order to better understand the contributions of boundary conditions to deposition, inert tracer simulations were conducted to quantify the relative amount of an atmospheric constituent transported across the boundaries of the domain at various altitudes and to quantify the amount that reaches and potentially deposits to the land surface in the SW US. Simulations using alternate sets of boundary concentrations, including estimates from global models (Goddard Earth Observing System-Chem (GEOS-Chem and the Global/Regional Atmospheric Heavy Metals (GRAHM model, and alternate meteorological input fields (for different years are analyzed in this paper. CMAQ dry deposition in the SW US is sensitive to differences in the atmospheric dynamics and atmospheric mercury chemistry parameterizations between the global models used for boundary conditions.

  7. Investigation of effects of varying model inputs on mercury deposition estimates in the Southwest US

    Directory of Open Access Journals (Sweden)

    T. Myers

    2013-01-01

    Full Text Available The Community Multiscale Air Quality (CMAQ model version 4.7.1 was used to simulate mercury wet and dry deposition for a domain covering the continental United States (US. The simulations used MM5-derived meteorological input fields and the US Environmental Protection Agency (EPA Clear Air Mercury Rule (CAMR emissions inventory. Using sensitivity simulations with different boundary conditions and tracer simulations, this investigation focuses on the contributions of boundary concentrations to deposited mercury in the Southwest (SW US. Concentrations of oxidized mercury species along the boundaries of the domain, in particular the upper layers of the domain, can make significant contributions to the simulated wet and dry deposition of mercury in the SW US. In order to better understand the contributions of boundary conditions to deposition, inert tracer simulations were conducted to quantify the relative amount of an atmospheric constituent transported across the boundaries of the domain at various altitudes and to quantify the amount that reaches and potentially deposits to the land surface in the SW US. Simulations using alternate sets of boundary concentrations, including estimates from global models (Goddard Earth Observing System-Chem (GEOS-Chem and the Global/Regional Atmospheric Heavy Metals (GRAHM model, and alternate meteorological input fields (for different years are analyzed in this paper. CMAQ dry deposition in the SW US is sensitive to differences in the atmospheric dynamics and atmospheric mercury chemistry parameterizations between the global models used for boundary conditions.

  8. Enhanced adsorption of mercury ions on thiol derivatized single wall carbon nanotubes.

    Science.gov (United States)

    Bandaru, Narasimha Murthy; Reta, Nekane; Dalal, Habibullah; Ellis, Amanda V; Shapter, Joseph; Voelcker, Nicolas H

    2013-10-15

    Thiol-derivatized single walled carbon nanotube (SWCNT-SH) powders were synthesized by reacting acid-cut SWCNTs with cysteamine hydrochloride using carbodiimide coupling. Infrared (IR) spectroscopy, Raman spectroscopy and thermogravimetric analysis confirmed the successful functionalization of the SWCNTs. SWCNT-SH powders exhibited a threefold higher adsorption capacity for Hg(II) ions compared to pristine SWCNTs, and a fourfold higher adsorption capacity compared to activated carbon. The influence of adsorption time, pH, initial metal concentration and adsorbent dose on Hg(II) ion removal was investigated. The maximum adsorption capacity of the SWCNT-SH powders was estimated by using equilibrium isotherms, such as Freundlich and Langmuir, and the maximum adsorption capacity of the SWCNT-SH powder was found to be 131 mg/g. A first-order rate model was employed to describe the kinetic adsorption process of Hg(II) ions onto the SWCNT-SH powders. Desorption studies revealed that Hg(II) ions could be easily removed from the SWCNT-SH powders by altering the pH. Further, the adsorption efficiency of recovered SWCNT-SH powders was retained up to 91%, even after 5 adsorption/desorption cycles.

  9. Modeling the global atmospheric transport and deposition of mercury to the Great Lakes

    Directory of Open Access Journals (Sweden)

    Mark D. Cohen

    2016-07-01

    Full Text Available Abstract Mercury contamination in the Great Lakes continues to have important public health and wildlife ecotoxicology impacts, and atmospheric deposition is a significant ongoing loading pathway. The objective of this study was to estimate the amount and source-attribution for atmospheric mercury deposition to each lake, information needed to prioritize amelioration efforts. A new global, Eulerian version of the HYSPLIT-Hg model was used to simulate the 2005 global atmospheric transport and deposition of mercury to the Great Lakes. In addition to the base case, 10 alternative model configurations were used to examine sensitivity to uncertainties in atmospheric mercury chemistry and surface exchange. A novel atmospheric lifetime analysis was used to characterize fate and transport processes within the model. Model-estimated wet deposition and atmospheric concentrations of gaseous elemental mercury (Hg(0 were generally within ∼10% of measurements in the Great Lakes region. The model overestimated non-Hg(0 concentrations by a factor of 2–3, similar to other modeling studies. Potential reasons for this disagreement include model inaccuracies, differences in atmospheric Hg fractions being compared, and the measurements being biased low. Lake Erie, downwind of significant local/regional emissions sources, was estimated by the model to be the most impacted by direct anthropogenic emissions (58% of the base case total deposition, while Lake Superior, with the fewest upwind local/regional sources, was the least impacted (27%. The U.S. was the largest national contributor, followed by China, contributing 25% and 6%, respectively, on average, for the Great Lakes. The contribution of U.S. direct anthropogenic emissions to total mercury deposition varied between 46% for the base case (with a range of 24–51% over all model configurations for Lake Erie and 11% (range 6–13% for Lake Superior. These results illustrate the importance of atmospheric

  10. Application of artificial neural network to simultaneous potentiometric determination of silver(I), mercury(II) and copper(II) ions by an unmodified carbon paste electrode.

    Science.gov (United States)

    Shamsipur, Mojtaba; Tashkhourian, Javad; Hemmateenejad, Bahram; Sharghi, Hashem

    2004-10-20

    The response characteristics and selectivity coefficients of an unmodified carbon paste electrode (CPEs) towards Ag(+), Cu(2+) and Hg(2+) were evaluated. The electrode was used as an indicator electrode for the simultaneous determination of the three metal ions in their mixtures via potentiometric titration with a standard thiocyanate solution. A three-layered feed-forward artificial neural network (ANN) trained by back-propagation learning algorithm was used to model the complex non-linear relationship between the concentration of silver, copper and mercury in their different mixtures and the potential of solution at different volumes of the added titrant. The network architecture and parameters were optimized to give low prediction errors. The optimized networks were able to precisely predict the concentrations of the three cations in synthetic mixtures.

  11. Adsorption property of melamine to mercury ion%三聚氰胺对汞离子的吸附性能

    Institute of Scientific and Technical Information of China (English)

    周艳梅; 王亚萍; 朱金花; 刘清泉

    2011-01-01

    The melamine molecule contained three free amino groups and three aromatic nitrogen atoms, so it had great adsorption potential to heavy metal ions. In order to investigate the adsorption property of this adsorbent to mercury ion, the adsorption capacity and adsorption rate of melamine to mercury ion were measured under different conditions including adsorption time, adsorption temperature, pH of solution and concentration of mercury ion. The results showed that melamine had good adsorption property to mercury ions, At 30 ℃ and pH 5. 0, when 50 mg of melamine was used to absorb mercury ion in 25 mL of 5430 mg/L mercury chloride solution for 6 h, the measured adsorption capacity was 606 mg/g and the adsorption rate was 38. 9 %. The adsorption isotherm belonged to Freundlich mode. This adsorbent had good comprehensive adsorption property and price advantage, so it had wide application prospect in separation and enrichment of mercury ion and the treatment of wastewater containing mercury.%三聚氰胺中含有三个自由氨基和三个芳香氮原子,对重金属离子具有很大的吸附潜力.为考察该吸附荆对汞离子的吸附性能,实验分别在不同吸附时间、吸附温度、溶液pH值、汞离子浓度条件下测定三聚氰胺对汞离子的吸附容量和吸附率,结果表明三聚氰胺对汞离子具有良好的吸附性能.在30℃温度下,pH 5.0,50 mg三聚氰胺在25 mL 5 430 mg/L氯化汞溶液中对汞离子吸附6 h,测得吸附容量为606 mg/g,吸附率达38.9%,其吸附等温线属于Freundlich型.由于该吸附剂的良好综合吸附性能和廉价优势,使得它在汞离子的分离、富集及含汞废液处理领域具有广阔的应用前景.

  12. Hematological Changes Induced by Mercury Ions and Ionizing Radiation in Experimental Animals

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin-Kyu; Lee, Yun-Jong; Choi, Dae-Seong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Kim, Ji-Hyang [Biotechnology Research Institute, Seoul (Korea, Republic of); Cebulska-Wasilewska, Antonina [The Henryk Niewodniczanski Institute of Nuclear Physics, Krakow (Poland)

    2006-07-01

    Toxic metals such as lead, chromium, cadmium, mercury and arsenic are widely found in our environment. Humans are exposed to these metals from numerous sources, including contaminated air, water, soil and food. Mercury, one of the most diffused and hazardous organ specific environmental contaminants, exists in a wide variety of physical and chemical states, each of which has unique characteristics for a target organ specificity. Although reports indicate that mercury induces deleterious damage, little is known about its effects on living organisms. Ionizing radiation, an extensively used therapeutic modality in oncology, not only eradicates neoplastic cells but also generates inevitable side effects for normal tissues. Such biological effects are made through the production of reactive oxygen species which include a superoxide anion, a hydroxyl radical and a hydrogen peroxide. These reactive species may contribute to the radiation-induced cytotoxicity (e.g., chromosome aberrations, protein oxidation, and muscle injury) and to the metabolic and morphologic changes (e.g., increased muscle proteolysis and changes in the central nervous system) in animals and humans. In the present study, radioimmunoassay of the cortisol in the serum and the analysis of the hematological components and enzymes related to a tissue injury were carried out to evaluate the effects of mercury chloride in comparison with those of ionizing radiation.

  13. Simultaneous determination of arsenic and mercury species in rice by ion-pairing reversed phase chromatography with inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Fang, Yong; Pan, Yushi; Li, Peng; Xue, Mei; Pei, Fei; Yang, Wenjian; Ma, Ning; Hu, Qiuhui

    2016-12-15

    An analytical method using reversed phase chromatography-inductively coupled plasma mass spectrometry for arsenic and mercury speciation analysis was described. The effect of ion-pairing reagent on simultaneous separation of four arsenic (arsenite, arsenate, monomethlyarsonate and dimethylarsinate) and three mercury species (inorganic mercury (Hg(II)), methylmecury and ethylmercury) was investigated. Parameters including concentrations and pH of the mobile phase were optimized. The separation and re-equilibration time was attained within 20min. Meanwhile, a sequential extraction method for arsenic and mercury in rice was tested. Subsequently, 1% HNO3 microwave-assisted extraction was chosen. Calibration curves based on peak area measurements were linear with correlation coefficient greater than 0.9958 for each species in the range studied. The detection limits of the species were in the range of 0.84-2.41μg/L for arsenic and 0.01-0.04μg/L for mercury, respectively. The proposed method was then successfully applied for the simultaneous determination of arsenic and mercury species in rice flour standard material and two kinds of rice from local markets.

  14. 改性蛭石对汞离子吸附性能的影响%Effect of Modified Vermiculite on Mercury Ion Adsorption

    Institute of Scientific and Technical Information of China (English)

    张莹; 李洪玲; 肖芙蓉; 陈宏伟; 吕新明; 但建明

    2011-01-01

    The single factor test method and the orthogonal experimental method were applied to study the the adsorption of mercury ion with the modified vermiculite. Influence factors included the modification method of vermiculite, the expansion tem|/era-ture of vermiculitcthe fineness of vermiculite, the concentration of CTMAB, the adsorption time, the adsorption temperature, pH value and the concentration of mercury ion. The results showed that the optimization adsorption conditions of mercury ion were as follows:1000 ℃ expansion,3% CTMAB concentration, 100 mesh fineness, pH5,0. 1 g amount of vermiculite and 30 min adsorption at room temperature. The adsorption rate of mercury ion was about 93%. Consequently,the modified vermiculite was very useful in treating industrial wastewater containing mercury ion.%分别利用单因素实验和正交设计实验研究了改性蛭石对汞离子吸附的影响,影响因素包括:蛭石的改性方法、蛭石膨胀温度、蛭石细度、改性剂浓度、吸附时间、吸附温度、pH值、汞离子浓度等.实验结果表明:蛭石经1000℃膨胀,3%的CTMAB改性,细度为100目,溶液pH值为5,蛭石用量为0.1g,室温下吸附30 min,汞离子的吸附率最高达到93%左右.说明储量丰富、价格低廉的改性蛭石是处理含汞工业废水的有效途径之一.

  15. Modelling of the X-ray fluorescence from Mercury's surface and sodium exosphere

    Science.gov (United States)

    Cooper, Rose

    2016-10-01

    We model the fluorescent X-ray signal expected from the Mercury surface. Due to the high solar flux at Mercury, it represents a highly suitable target. Observations of this fluorescence will be performed by the Mercury Imaging X-ray Spectrometer (MIXS) on the upcoming BepiColumbo mission. Accurate modelling is required to plan observation strategies and eventually to quantify the surface composition. In addition, we also investigate the possibility of detecting fluorescence from the exosphere. We are using code modified from that used for the SMART-1 D-CIXS instrument to the Moon. Modifications include detector parameters, solar proximity, likely surface elemental components, and emission from the optically thin exosphere. Modelling of fluorescence from both the surface and exosphere are conducted, with particular emphasis on the sodium component.

  16. Colorimetric Signal Amplification Assay for Mercury Ions Based on the Catalysis of Gold Amalgam.

    Science.gov (United States)

    Chen, Zhengbo; Zhang, Chenmeng; Gao, Qinggang; Wang, Guo; Tan, Lulu; Liao, Qing

    2015-11-03

    Mercury is a major threat to the environment and to human health. It is highly desirable to develop a user-friendly kit for on-site mercury detection. Such a method must be able to detect mercury below the threshold levels (10 nM) for drinking water defined by the U.S. Environmental Protection Agency. Herein, we for the first time reported catalytically active gold amalgam-based reaction between 4-nitrophenol and NaBH4 with colorimetric sensing function. We take advantage of the correlation between the catalytic properties and the surface area of gold amalgam, which is proportional to the amount of the gold nanoparticle (AuNP)-bound Hg(2+). As the concentration of Hg(2+) increases until the saturation of Hg onto the AuNPs, the catalytic performance of the gold amalgam is much stronger due to the formation of gold amalgam and the increase of the nanoparticle surface area, leading to the decrease of the reduction time of 4-nitrophenol for the color change. This sensing system exhibits excellent selectivity and ultrahigh sensitivity up to the 1.45 nM detection limit. The practical use of this system for Hg(2+) determination in tap water samples is also demonstrated successfully.

  17. Fully variational average atom model with ion-ion correlations.

    Science.gov (United States)

    Starrett, C E; Saumon, D

    2012-02-01

    An average atom model for dense ionized fluids that includes ion correlations is presented. The model assumes spherical symmetry and is based on density functional theory, the integral equations for uniform fluids, and a variational principle applied to the grand potential. Starting from density functional theory for a mixture of classical ions and quantum mechanical electrons, an approximate grand potential is developed, with an external field being created by a central nucleus fixed at the origin. Minimization of this grand potential with respect to electron and ion densities is carried out, resulting in equations for effective interaction potentials. A third condition resulting from minimizing the grand potential with respect to the average ion charge determines the noninteracting electron chemical potential. This system is coupled to a system of point ions and electrons with an ion fixed at the origin, and a closed set of equations is obtained. Solution of these equations results in a self-consistent electronic and ionic structure for the plasma as well as the average ionization, which is continuous as a function of temperature and density. Other average atom models are recovered by application of simplifying assumptions.

  18. Sub-mm Scale Fiber Guided Deep/Vacuum Ultra-Violet Optical Source for Trapped Mercury Ion Clocks

    Science.gov (United States)

    Yi, Lin; Burt, Eric A.; Huang, Shouhua; Tjoelker, Robert L.

    2013-01-01

    We demonstrate the functionality of a mercury capillary lamp with a diameter in the sub-mm range and deep ultraviolet (DUV)/ vacuum ultraviolet (VUV) radiation delivery via an optical fiber integrated with the capillary. DUV spectrum control is observed by varying the fabrication parameters such as buffer gas type and pressure, capillary diameter, electrical resonator design, and temperature. We also show spectroscopic data of the 199Hg+ hyper-fine transition at 40.5GHz when applying the above fiber optical design. We present efforts toward micro-plasma generation in hollow-core photonic crystal fiber with related optical design and theoretical estimations. This new approach towards a more practical DUV optical interface could benefit trapped ion clock developments for future ultra-stable frequency reference and time-keeping applications.

  19. Sub-mm Scale Fiber Guided Deep/Vacuum Ultra-Violet Optical Source for Trapped Mercury Ion Clocks

    Science.gov (United States)

    Yi, Lin; Burt, Eric A.; Huang, Shouhua; Tjoelker, Robert L.

    2013-01-01

    We demonstrate the functionality of a mercury capillary lamp with a diameter in the sub-mm range and deep ultraviolet (DUV)/ vacuum ultraviolet (VUV) radiation delivery via an optical fiber integrated with the capillary. DUV spectrum control is observed by varying the fabrication parameters such as buffer gas type and pressure, capillary diameter, electrical resonator design, and temperature. We also show spectroscopic data of the 199Hg+ hyper-fine transition at 40.5GHz when applying the above fiber optical design. We present efforts toward micro-plasma generation in hollow-core photonic crystal fiber with related optical design and theoretical estimations. This new approach towards a more practical DUV optical interface could benefit trapped ion clock developments for future ultra-stable frequency reference and time-keeping applications.

  20. Modeling mercury biomagnification (South River, Virginia, USA) to inform river management decision making.

    Science.gov (United States)

    Tom, Kyle R; Newman, Michael C; Schmerfeld, John

    2010-04-01

    Mercury trophic transfer in the South River (VA, USA) was modeled to guide river remediation decision making. Sixteen different biota types were collected at six sites within 23 river miles. Mercury biomagnification was modeled using a general biomagnification model based on delta(15)N and distance from the historic mercury release. Methylmercury trophic transfer was clearer than that for total Hg and, therefore, was used to build the predictive model (r(2) (prediction) = 0.76). The methylmercury biomagnification factors were similar among sites, but model intercept did increase with distance down river. Minimum Akaike's Information Criterion Estimation (MAICE) justified the incorporation of distance in the model. A model with a very similar biomagnification factor to the South River (95% confidence intervals [CI] = 0.38-0.52) was produced for a second contaminated Virginia river, the North Fork Holston River (95% CI = 0.41-0.55). Percent of total Hg that was methylmercury increased monotonically with trophic position. Trophic models based on delta(15)N were adequate for predicting changes in mercury concentrations in edible fish under different remediation scenarios.

  1. Ames stereo pipeline-derived digital terrain models of Mercury from MESSENGER stereo imaging

    Science.gov (United States)

    Fassett, Caleb I.

    2016-12-01

    In this study, 96 digital terrain models (DTMs) of Mercury were created using the Ames Stereo Pipeline, using 1456 pairs of stereo images from the Mercury Dual Imaging System instrument on MESSENGER. Although these DTMs cover only 1% of the surface of Mercury, they enable three-dimensional characterization of landforms at horizontal resolutions of 50-250 m/pixel and vertical accuracy of tens of meters. This is valuable in regions where the more precise measurements from the Mercury Laser Altimeter (MLA) are sparse. MLA measurements nonetheless provide an important geodetic framework for the derived stereo products. These DTMs, which are publicly released in conjunction with this paper, reveal topography of features at relatively small scales, including craters, graben, hollows, pits, scarps, and wrinkle ridges. Measurements from these data indicate that: (1) hollows have a median depth of 32 m, in basic agreement with earlier shadow measurement, (2) some of the deep pits (up to 4 km deep) that are interpreted to form via volcanic processes on Mercury have surrounding rims or rises, but others do not, and (3) some pits have two or more distinct, low-lying interior minima that could represent multiple vents.

  2. The attenuation of concentrations model: a new method for assessing mercury mobility in sediments

    Directory of Open Access Journals (Sweden)

    Julio C. Wasserman

    2004-02-01

    Full Text Available In this work we propose a new approach for the determination of the mobility of mercury in sediments based on spatial distribution of concentrations. We chose the Tainheiros Cove, located in the Todos os Santos Bay, Brazil, as the study area, for it has a history of mercury contamination due to a chloro-alkali plant that was active during 12 years. Twenty-six surface sediment samples were collected from the area and mercury concentrations were measured by cold vapour atomic absorption spectrophotometry. A contour map was constructed from the results, indicating that mercury accumulated in a "hot spot" where concentrations reach more than 1 µg g-1. The model is able to estimate mobility of mercury in the sediments based on the distances between iso-concentration contours that determines an attenuation of concentrations factor. Values of attenuation ranged between 0.0729 (East of the hot spot, indicating higher mobility to 0.7727 (North of the hot spot, indicating lower mobility.

  3. Development of an empirical nonlinear model for mercury bioaccumulation in the South and South Fork Shenandoah rivers of Virginia.

    Science.gov (United States)

    Brent, Robert N; Kain, Donald G

    2011-11-01

    Mercury is a globally distributed pollutant that biomagnifies in aquatic food webs. In the United States, 3781 water bodies fail to meet criteria for safe fish consumption due to mercury bioaccumulation. In the risk assessment and management of these impairments (through the total maximum daily load program), an important step is evaluating the relationship between aqueous mercury and mercury in fish tissue. Often, this relationship is simplified to a bioaccumulation factor (BAF): the ratio of fish tissue mercury to aqueous mercury. This article evaluates the relationship between aqueous mercury and fish tissue mercury across a contamination gradient in the South and South Fork Shenandoah rivers of Virginia. The relationship was found to be nonlinear, with BAFs decreasing as the level of contamination increased. This means that protective water column mercury concentration targets established from site-specific BAFs will be overestimated in contaminated areas and will not be sufficiently protective. To avoid this over-prediction in the South and South Fork Shenandoah rivers, an empirical nonlinear Michaelis-Menten model was used to establish a protective water-quality target. Among other models and variables, the Michaelis-Menten model, relating total mercury in the water column to methylmercury in fish tissue, achieved the best empirical fit (r(2) = 0.9562). The resulting water-quality targets using this model were 3.8 and 3.2 ng/l for the South and South Fork Shenandoah rivers, respectively. These values are 2.1-2.5 times lower than the water-quality target developed using a site-specific BAF. These findings demonstrate the need to consider nonlinear BAF relationships in mercury-contaminated areas.

  4. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal models of Mercury. Ph.D. Thesis

    Science.gov (United States)

    Leake, M. A.

    1982-01-01

    Recent and more complex thermal models of Mercury and the terrestrial planets are discussed or noted. These models isolate a particular aspect of the planet's thermal history in an attempt to understand that parameter. Among these topics are thermal conductivity, convection, radiogenic sources of heat, other heat sources, and the problem of the molten core and regenerative dynamo.

  5. The intercrater plains of Mercury and the Moon: Their nature, origin and role in terrestrial planet evolution. Thermal models of Mercury. Ph.D. Thesis

    Science.gov (United States)

    Leake, M. A.

    1982-01-01

    Recent and more complex thermal models of Mercury and the terrestrial planets are discussed or noted. These models isolate a particular aspect of the planet's thermal history in an attempt to understand that parameter. Among these topics are thermal conductivity, convection, radiogenic sources of heat, other heat sources, and the problem of the molten core and regenerative dynamo.

  6. Compensated Multi-Pole Mercury Trapped Ion Frequency Standard and Stability Evaluation of Systematic Effects

    Science.gov (United States)

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

    2009-04-01

    We have developed a compensated multi-pole Linear Ion Trap Standard (LITS) that eliminates nearly all frequency sensitivity to residual ion number variations. When operated with 199Hg+, this trapped ion clock has recently demonstrated extremely good stability over a 9-month period. The short-term stability has been measured at 5 × 10-14/τ1/2 and an upper limit on long-term fractional frequency deviations of REFID="9789812838223_0037FN001">

  7. Trend analysis from 1970 to 2008 and model evaluation of EDGARv4 global gridded anthropogenic mercury emissions

    Energy Technology Data Exchange (ETDEWEB)

    Muntean, Marilena, E-mail: marilena.muntean@jrc.ec.europa.eu [European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra (Italy); Janssens-Maenhout, Greet [European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra (Italy); Song, Shaojie; Selin, Noelle E. [Massachusetts Institute of Technology, Cambridge, MA (United States); Olivier, Jos G.J. [PBL Netherlands Environment Assessment Agency, Bilthoven (Netherlands); Guizzardi, Diego [European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra (Italy); Maas, Rob [RIVM National Institute for Public Health and Environment, Bilthoven (Netherlands); Dentener, Frank [European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra (Italy)

    2014-10-01

    The Emission Database for Global Atmospheric Research (EDGAR) provides a time-series of man-made emissions of greenhouse gases and short-lived atmospheric pollutants from 1970 to 2008. Mercury is included in EDGARv4.tox1, thereby enriching the spectrum of multi-pollutant sources in the database. With an average annual growth rate of 1.3% since 1970, EDGARv4 estimates that the global mercury emissions reached 1287 tonnes in 2008. Specifically, gaseous elemental mercury (GEM) (Hg{sup 0}) accounted for 72% of the global total emissions, while gaseous oxidised mercury (GOM) (Hg{sup 2+}) and particle bound mercury (PBM) (Hg-P) accounted for only 22% and 6%, respectively. The less reactive form, i.e., Hg{sup 0}, has a long atmospheric residence time and can be transported long distances from the emission sources. The artisanal and small-scale gold production, accounted for approximately half of the global Hg{sup 0} emissions in 2008 followed by combustion (29%), cement production (12%) and other metal industry (10%). Given the local-scale impacts of mercury, special attention was given to the spatial distribution showing the emission hot-spots on gridded 0.1° × 0.1° resolution maps using detailed proxy data. The comprehensive ex-post analysis of the mitigation of mercury emissions by end-of-pipe abatement measures in the power generation sector and technology changes in the chlor-alkali industry over four decades indicates reductions of 46% and 93%, respectively. Combined, the improved technologies and mitigation measures in these sectors accounted for 401.7 tonnes of avoided mercury emissions in 2008. A comparison shows that EDGARv4 anthropogenic emissions are nearly equivalent to the lower estimates of the United Nations Environment Programme (UNEP)'s mercury emissions inventory for 2005 for most sectors. An evaluation of the EDGARv4 global mercury emission inventory, including mercury speciation, was performed using the GEOS-Chem global 3-D mercury model. The

  8. Recovery of mercury from mercury compounds via electrolytic methods

    Science.gov (United States)

    Grossman, M.W.; George, W.A.

    1989-11-07

    A process for electrolytically recovering mercury from mercury compounds is provided. In one embodiment, Hg is recovered from Hg[sub 2]Cl[sub 2] employing as the electrolyte solution a mixture of HCl and H[sub 2]O. In another embodiment, Hg is electrolytically recovered from HgO wherein the electrolyte solution is comprised of glacial acetic acid and H[sub 2]O. Also provided is an apparatus for producing isotopically enriched mercury compounds in a reactor and then transporting the dissolved compounds into an electrolytic cell where mercury ions are electrolytically reduced and elemental mercury recovered from the mercury compounds. 3 figs.

  9. Catalytic hydrogen evolution in cathodic stripping voltammetry on a mercury electrode in the presence of cobalt(II) ion and phenylthiourea or thiourea.

    Science.gov (United States)

    Spătaru, N; Bănica, F G

    2001-11-01

    The system Co(II)-phenylthiourea (PTU)-borax buffer was investigated by cathodic stripping voltammetry (CSV) at a hanging mercury drop electrode. The results of the voltammetric measurements showed that the presence of both PTU and Co(II) gives rise to a new irreversible peak at about -1.5 V. Based upon our previous results obtained in the study of other sulfur compounds and the sulfide ion itself, the peak was ascribed to the catalytic hydrogen evolution superimposed on the reduction of the coordinated Co(II) ion. The catalyst itself is a Co(II) complex with the sulfide ion produced by the decomposition of the analyte during the deposition step. The influence of PTU and cobalt concentration, accumulation conditions and stripping parameters was investigated and complementary data on thiourea are included. The results showed that the measurement of the catalytic hydrogen evolution peak current can be used as a basis for a simple, accurate and rapid method for the determination of PTU within the concentration range 10-100 nM. The catalytic method is relatively free of interferences and could be a suitable alternative for cases in which the stripping peak due to mercury ion reduction in the accumulated mercury compound is disturbed by some interference.

  10. ECHMERIT V1.0 – a new global fully coupled mercury-chemistry and transport model

    Directory of Open Access Journals (Sweden)

    N. Pirrone

    2009-05-01

    Full Text Available Mercury is a global pollutant due to its long lifetime in the atmosphere. Its hemispheric transport patterns and eventual deposition are therefore of major concern. For the purpose of global atmospheric mercury chemistry and transport modelling the ECHMERIT model was developed. ECHMERIT, based on the global circulation model ECHAM5 differs from most global mercury models in that the emissions, chemistry (including general tropospheric chemistry and mercury chemistry, transport and deposition are coupled on-line to the GCM. The chemistry mechanism includes an online calculation of photolysis rate constants using the Fast-J photolysis mechanism, the CBM-Z tropospheric gas-phase mechanism and aqueous-phase chemistry based on the MECCA mechanism. Additionally, a mercury chemistry mechanism that incorporates gas and aqueous phase mercury chemistry is included. A detailed description of the model, including the wet and dry deposition modules, and the implemented emissions is given in this technical report. First model testing and evaluation show a satisfactory model performance for surface ozone and mercury concentrations (with a mean bias of 1.46 ppb for ozone and a mean bias of 13.55 ppq for TGM when compared with EMEP station data. Requirements regarding measurement data and emission inventories which could considerably improve model skill are discussed.

  11. ECHMERIT V1.0 – a new global fully coupled mercury-chemistry and transport model

    Directory of Open Access Journals (Sweden)

    G. Jung

    2009-11-01

    Full Text Available Mercury is a global pollutant due to its long lifetime in the atmosphere. Its hemispheric transport patterns and eventual deposition are therefore of major concern. For the purpose of global atmospheric mercury chemistry and transport modelling the ECHMERIT model was developed. ECHMERIT, based on the global circulation model ECHAM5 differs from most global mercury models in that the emissions, chemistry (including general tropospheric chemistry and mercury chemistry, transport and deposition are coupled on-line to the GCM. The chemistry mechanism includes an online calculation of photolysis rate constants using the Fast-J photolysis mechanism, the CBM-Z tropospheric gas-phase mechanism and aqueous-phase chemistry based on the MECCA mechanism. Additionally, a mercury chemistry mechanism that incorporates gas and aqueous phase mercury chemistry is included. A detailed description of the model, including the wet and dry deposition modules, and the implemented emissions is given in this technical report. First model testing and evaluation show a satisfactory model performance for surface ozone and mercury mixing ratios (with a mean bias of 1.46 nmol/mol for ozone and a mean bias of 13.55 fmol/mol for TGM when compared with EMEP station data. Requirements regarding measurement data and emission inventories which could considerably improve model skill are discussed.

  12. A novel voltammetric sensor for sensitive detection of mercury(II) ions using glassy carbon electrode modified with graphene-based ion imprinted polymer

    Energy Technology Data Exchange (ETDEWEB)

    Ghanei-Motlagh, Masoud, E-mail: m.ghaneimotlagh@yahoo.com [Young Researchers and Elite Club, Kerman Branch, Islamic Azad University, Kerman (Iran, Islamic Republic of); Taher, Mohammad Ali; Heydari, Abolfazl [Department of Chemistry, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ghanei-Motlagh, Reza [Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Gupta, Vinod K. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Department of Applied Chemistry, University of Johannesburg, Johannesburg (South Africa)

    2016-06-01

    In this paper, a novel strategy was proposed to prepare ion-imprinted polymer (IIP) on the surface of reduced graphene oxide (RGO). Polymerization was performed using methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, 2,2′–((9E,10E)–1,4–dihydroxyanthracene–9,10–diylidene) bis(hydrazine–1–carbothioamide) (DDBHCT) as the chelating agent and ammonium persulfate (APS) as initiator, via surface imprinted technique. The RGO–IIP was characterized by means of Fourier transform infrared spectroscopy (FT–IR), field emission scanning electron microscopy (FE–SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The electrochemical procedure was based on the accumulation of Hg(II) ions at the surface of a modified glassy carbon electrode (GCE) with RGO–IIP. The prepared RGO–IIP sensor has higher voltammetric response compared to the non-imprinted polymer (NIP), traditional IIP and RGO. The RGO–IIP modified electrode exhibited a linear relationship toward Hg(II) concentrations ranging from 0.07 to 80 μg L{sup −1}. The limit of detection (LOD) was found to be 0.02 μg L{sup −1} (S/N = 3), below the guideline value from the World Health Organization (WHO). The applicability of the proposed electrochemical sensor to determination of mercury(II) ions in different water samples was reported. - Highlights: • The novel Hg(II)-imprinted polymer was synthesized and characterized. • The resulting RGO–IIP was applied for electrochemical monitoring of Hg(II) ions. • The proposed sensor was successfully applied for determination of Hg(II) in real water samples.

  13. Nanoporous gold based optical sensor for sub-ppt detection of mercury ions.

    Science.gov (United States)

    Zhang, Ling; Chang, Haixin; Hirata, Akihiko; Wu, Hongkai; Xue, Qi-Kun; Chen, Mingwei

    2013-05-28

    Precisely probing heavy metal ions in water is important for molecular biology, environmental protection, and healthy monitoring. Although many methods have been reported in the past decade, developing a quantitative approach capable of detecting sub-ppt level heavy metal ions with high selectivity is still challenging. Here we report an extremely sensitive and highly selective nanoporous gold/aptamer based surface enhanced resonance Raman scattering (SERRS) sensor. The optical sensor has an unprecedented detection sensitivity of 1 pM (0.2 ppt) for Hg(2+) ions, the most sensitive Hg(2+) optical sensor known so far. The sensor also exhibits excellent selectivity. Dilute Hg(2+) ions can be identified in an aqueous solution containing 12 metal ions as well as in river water and underground water. Moreover, the SERRS sensor can be reused without an obvious loss of the sensitivity and selectivity even after 10 cycles.

  14. Metal Ion Modeling Using Classical Mechanics.

    Science.gov (United States)

    Li, Pengfei; Merz, Kenneth M

    2017-02-08

    Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems.

  15. Metal Ion Modeling Using Classical Mechanics

    Science.gov (United States)

    2017-01-01

    Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems. PMID:28045509

  16. Simulation of atmospheric mercury depletion events (AMDEs) during polar springtime using the MECCA box model

    Science.gov (United States)

    Xie, Z.-Q.; Sander, R.; Pöschl, U.; Slemr, F.

    2008-12-01

    Atmospheric mercury depletion events (AMDEs) during polar springtime are closely correlated with bromine-catalyzed tropospheric ozone depletion events (ODEs). To study gas- and aqueous-phase reaction kinetics and speciation of mercury during AMDEs, we have included mercury chemistry into the box model MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere), which enables dynamic simulation of bromine activation and ODEs. We found that the reaction of Hg with Br atoms dominates the loss of gaseous elemental mercury (GEM). To explain the experimentally observed synchronous depletion of GEM and O3, the reaction rate of Hg+BrO has to be much lower than that of Hg+Br. The synchronicity is best reproduced with rate coefficients at the lower limit of the literature values for both reactions, i.e. kHg+Br≍3×10-13 and kHg+BrO≤1×10-15 cm3 molecule-1 s-1, respectively. Throughout the simulated AMDEs, \\chem{BrHgOBr} was the most abundant reactive mercury species, both in the gas phase and in the aqueous phase. The aqueous-phase concentrations of BrHgOBr, HgBr2, and HgCl2 were several orders of magnitude larger than that of Hg(SO3)22-. Considering chlorine chemistry outside depletion events (i.e. without bromine activation), the concentration of total divalent mercury in sea-salt aerosol particles (mostly HgCl42-) was much higher than in dilute aqueous droplets (mostly Hg(SO3)22-), and did not exhibit a diurnal cycle (no correlation with HO2 radicals).

  17. Modular model for Mercury's magnetospheric magnetic field confined within the average observed magnetopause.

    Science.gov (United States)

    Korth, Haje; Tsyganenko, Nikolai A; Johnson, Catherine L; Philpott, Lydia C; Anderson, Brian J; Al Asad, Manar M; Solomon, Sean C; McNutt, Ralph L

    2015-06-01

    Accurate knowledge of Mercury's magnetospheric magnetic field is required to understand the sources of the planet's internal field. We present the first model of Mercury's magnetospheric magnetic field confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The field of internal origin is approximated by a dipole of magnitude 190 nT RM(3), where RM is Mercury's radius, offset northward by 479 km along the spin axis. External field sources include currents flowing on the magnetopause boundary and in the cross-tail current sheet. The cross-tail current is described by a disk-shaped current near the planet and a sheet current at larger (≳ 5 RM ) antisunward distances. The tail currents are constrained by minimizing the root-mean-square (RMS) residual between the model and the magnetic field observed within the magnetosphere. The magnetopause current contributions are derived by shielding the field of each module external to the magnetopause by minimizing the RMS normal component of the magnetic field at the magnetopause. The new model yields improvements over the previously developed paraboloid model in regions that are close to the magnetopause and the nightside magnetic equatorial plane. Magnetic field residuals remain that are distributed systematically over large areas and vary monotonically with magnetic activity. Further advances in empirical descriptions of Mercury's magnetospheric external field will need to account for the dependence of the tail and magnetopause currents on magnetic activity and additional sources within the magnetosphere associated with Birkeland currents and plasma distributions near the dayside magnetopause.

  18. Behavior of mercury, lead, cesium, and uranyl ions on four SRS soils

    Energy Technology Data Exchange (ETDEWEB)

    Bibler, J.P.; Marson, D.B.

    1992-03-20

    Samples of four Savannah River Site (SRS) soils were tested for sorption behavior with Hg[sup 2+], Pb[sup 2+], UO[sub 2][sup 2+], and Cs[sup +] ions. The purpose of the study was to determine the selectivity of the different soils for these ions alone and in the presence of the competing cations, H[sup +] and Ca[sup 2+]. Distribution constants, Kd's, for the test ions in various solutions have been determined for the four soils. In general, sorption by all of the soils appeared to be more complex than a simple ion exchange or adsorption process. In particular, the presence of organic matter in soil increased the capacity of the soil due to its chelating ability. Similar soils did not react similarly toward each metal cation.

  19. Behavior of mercury, lead, cesium, and uranyl ions on four SRS soils

    Energy Technology Data Exchange (ETDEWEB)

    Bibler, J.P.; Marson, D.B.

    1992-03-20

    Samples of four Savannah River Site (SRS) soils were tested for sorption behavior with Hg{sup 2+}, Pb{sup 2+}, UO{sub 2}{sup 2+}, and Cs{sup +} ions. The purpose of the study was to determine the selectivity of the different soils for these ions alone and in the presence of the competing cations, H{sup +} and Ca{sup 2+}. Distribution constants, Kd`s, for the test ions in various solutions have been determined for the four soils. In general, sorption by all of the soils appeared to be more complex than a simple ion exchange or adsorption process. In particular, the presence of organic matter in soil increased the capacity of the soil due to its chelating ability. Similar soils did not react similarly toward each metal cation.

  20. A Concentration-Controllable Microfluidic Droplet Mixer for Mercury Ion Detection

    Directory of Open Access Journals (Sweden)

    Qian-Fang Meng

    2015-07-01

    Full Text Available A microfluidic droplet mixer is developed for rapid detection of Hg(II ions. Reagent concentration and droplets can be precisely controlled by adjusting the flow rates of different fluid phases. By selecting suitable flow rates of the oil phase, probe phase and sample phase, probe droplets and sample droplets can be matched and merged in pairs and subsequently well-mixed in the poly (dimethylsiloxane (PDMS channels. The fluorescence enhancement probe (Rhodamine B mixed with gold nanoparticles encapsulated in droplets can react with Hg(II ions. The Hg(II ion concentration in the sample droplets is adjusted from about 0 to 1000 nM through fluid regulation to simulate possible various contaminative water samples. The intensity of the emission fluorescence is sensitive to Hg(II ions (increases as the Hg(II ion concentration increases. Through the analysis of the acquired fluorescence images, the concentration of Hg(II ions can be precisely detected. With the advantages of less time, cost consumption and easier manipulations, this device would have a great potential in micro-scale sample assays and real-time chemical reaction studies.

  1. Facile and One Pot Synthesis of Gold Nanoparticles Using Tetraphenylborate and Polyvinylpyrrolidone for Selective Colorimetric Detection of Mercury Ions in Aqueous Medium

    Directory of Open Access Journals (Sweden)

    Sidhureddy Boopathi

    2012-01-01

    Full Text Available In this work, we reported for the first time, a facile and one step synthesis of gold nanoparticles from HAuCl4, employing tetraphenylborate as the reducing agent. The synthesis is not only facile but also yields “dumb-bell-shaped”particles. This shape appears to arise from a possible emulsion of the products of oxidation/decomposition of tetraphenylborate by HAuCl4, surrounding the particle. The size and shape of the AuNPs were characterized by Transmission electron microscopy (TEM and UV-visible Spectroscopy. Interestingly, the addition of polyvinylpyrrolidone (PVP during the synthesis was found to enhance the stability of the nanoparticle dispersion. The particles synthesized under these conditions assume “spherical” shape with the appearance of only transverse surface plasmon resonance band. The highlight of the observations is that the gold nanoparticles synthesized using tetraphenylborate as reducing agent and PVP as stabilizer are highly stable in alkaline medium, in contrast to the synthesis wherein borohydride is used as reducing agent. The AuNPs synthesized using tetraphenylborate and PVP show their mercury sensing behavior only in the alkaline medium. The color of the nanoparticle dispersion undergoes distinct color change from pink to blue with the addition of mercury ions. They also show dramatic selectivity to mercury ions in presence of other interfering ions, Pb2+, Zn2+ and Ca2+.

  2. Radiative Transfer Modeling of MESSENGER VIR Spectra of Mercury: Detection and Mapping of Submicroscopic Carbon

    Science.gov (United States)

    Trang, D.; Lucey, P. G.; Izenberg, N.

    2015-12-01

    The composition of Mercury is elusive because the planet is optically dark and exhibits a relatively featureless red visible and near-infrared spectrum. Studies have invoked opaque minerals and space weathering to explain these characteristics. In this study we used radiative transfer modeling of MESSENGER VIRS data to show that carbon is required to explain the detailed shape of the spectrum of Mercury from 0.3-1.5 µm. In this model, we assume the regolith comprises a high albedo host mineral, which contains nanophase and microphase iron and carbon. We varied the abundance of nanophase and microphase iron and carbon to fit the observed spectra. We found that the nanophase and microphase iron alone inadequately fits the visible portion of the observed spectra. By adding carbon, we find that nanophase and microphase iron and nanophase amorphous carbon fit the VIRS spectra consistently. We produced a global nanophase amorphous carbon map as well as nanophase and microphase iron maps. From the carbon map (see figure), we find that nanophase amorphous carbon is sensitive to geologic features associated with space weathering, such as fresh crater rays. Thus, amorphous carbon is a new indicator for regolith maturity. We also observe that the global average submicroscopic carbon content is 1.4±0.3 wt.% C, which is consistent with MESSENGER Gamma-Ray Spectrometer measurements. Using this abundance, we can constrain the source of water and carbon on Mercury. Assuming the water ice in the poles is derived from wet impactors, both asteroids and comets, and knowing C/H ratios of those sources, the surface nanophase carbon layer can be no thicker than 10 m if all carbon is derived from an exogenous source. It is almost certain the space weathered regolith on Mercury is thicker than 10 m, so the majority of carbon on Mercury must be endogenous. Figure: Nanophase amorphous carbon map. In this map, fresh craters and their rays are distinguishable by the lower proportion of

  3. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Buitrago, Paula A. [Univ. of Utah, Salt Lake City, UT (United States); Morrill, Mike [Univ. of Utah, Salt Lake City, UT (United States); Lighty, JoAnn S. [Univ. of Utah, Salt Lake City, UT (United States); Silcox, Geoffrey D. [Univ. of Utah, Salt Lake City, UT (United States)

    2009-06-01

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  4. A Model of Mercury's Magnetospheric Magnetic Field with Dependence on Magnetic Activity

    Science.gov (United States)

    Korth, H.; Tsyganenko, N. A.; Johnson, C. L.; Philpott, L. C.; Anderson, B. J.; Solomon, S. C.; McNutt, R. L., Jr.

    2015-12-01

    Accurate knowledge of Mercury's magnetospheric magnetic field is required to characterize the planet's internal field and the structure of the magnetosphere. We present the first model of Mercury's magnetospheric magnetic field that includes a dependence on magnetic activity. The model consists of individual modules for magnetic fields of internal origin, approximated by a dipole of magnitude 190 nT RM3, where RM is Mercury's radius, offset northward by 479 km along the spin axis, and of external origin resulting from currents flowing on the magnetopause boundary and in the cross-tail current sheet. The magnetic field is confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft and dependent on magnetic activity. The cross-tail current is prescribed having a disk shape near the planet and extending into a sheet at larger distances. The magnitude of the tail current, which also depends on magnetic activity, is fit to minimize the root-mean-square residual between the model magnetic field and the field within the magnetosphere observed by MESSENGER. The model was fit separately for magnetic field observations within distinct levels of magnetic activity. Linear fits of model parameters versus magnetic activity allows continuous scaling of the model to magnetic activity. The magnetic field contribution from each module is shielded individually by a scalar potential function, which was fit to minimize the root-mean-square normal magnetic field component at the magnetopause. The resulting model reproduces the dependence of the magnetospheric size and tail current intensity on magnetic activity, and allows more accurate characterization of the internal field.

  5. Simultaneous removal of acid green 25 and mercury ions from aqueous solutions using glutamine modified chitosan magnetic composite microspheres.

    Science.gov (United States)

    Tao, Xue; Li, Kun; Yan, Han; Yang, Hu; Li, Aimin

    2016-02-01

    In this current work, the magnetic composite microsphere containing glutamine modified chitosan and silica coated Fe3O4 nanoparticles (CS-Gln-MCM) has been successfully prepared and extensively characterized, which is a kind of biodegradable materials. CS-Gln-MCM shows enhanced removal efficiency for both acid green 25 (AG25), an amphoteric dye, and mercury ions (Hg(2+)) from water in the respective while measured pH range compared with chitosan magnetic composite microsphere (CS-MCM) without modification. It is due to the fact that the grafted amino acid provides a variety of additional adsorption active sites and diverse adsorption mechanisms are involved. In AG25 and Hg(2+) aqueous mixture, the modified adsorbents bear preferential adsorption for AG25 over Hg(2+) in strong acidic solutions ascribed to multiple interactions between AG25 and CS-Gln-MCM, such as hydrogen bonding and electrostatic interactions. While, in weak acidic conditions, an efficient simultaneous removal is observed for different adsorption effects involved in aforementioned two pollutants. Besides, CS-Gln-MCM illuminates not only short equilibrium time for adsorption of each pollutant less than 20.0 min but also rapid magnetic separation from water and efficient regeneration after saturated adsorption. Therefore, CS-Gln-MCM bears great application potentials in water treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Using Existing Arctic Atmospheric Mercury Measurements to Refine Global and Regional Scale Atmospheric Transport Models

    Science.gov (United States)

    Moore, C. W.; Dastoor, A.; Steffen, A.; Nghiem, S. V.; Agnan, Y.; Obrist, D.

    2015-12-01

    Northern hemisphere background atmospheric concentrations of gaseous elemental mercury (GEM) have been declining by up to 25% over the last ten years at some lower latitude sites. However, this decline has ranged from no decline to 9% over 10 years at Arctic long-term measurement sites. Measurements also show a highly dynamic nature of mercury (Hg) species in Arctic air and snow from early spring to the end of summer when biogeochemical transformations peak. Currently, models are unable to reproduce this variability accurately. Estimates of Hg accumulation in the Arctic and Arctic Ocean by models require a full mechanistic understanding of the multi-phase redox chemistry of Hg in air and snow as well as the role of meteorology in the physicochemical processes of Hg. We will show how findings from ground-based atmospheric Hg measurements like those made in spring 2012 during the Bromine, Ozone and Mercury Experiment (BROMEX) near Barrow, Alaska can be used to reduce the discrepancy between measurements and model output in the Canadian GEM-MACH-Hg model. The model is able to reproduce and to explain some of the variability in Arctic Hg measurements but discrepancies still remain. One improvement involves incorporation of new physical mechanisms such as the one we were able to identify during BROMEX. This mechanism, by which atmospheric mercury depletion events are abruptly ended via sea ice leads opening and inducing shallow convective mixing that replenishes GEM (and ozone) in the near surface atmospheric layer, causing an immediate recovery from the depletion event, is currently lacking in models. Future implementation of this physical mechanism will have to incorporate current remote sensing sea ice products but also rely on the development of products that can identify sea ice leads quantitatively. In this way, we can advance the knowledge of the dynamic nature of GEM in the Arctic and the impact of climate change along with new regulations on the overall

  7. Fluorogenic mercury ion sensor based on pyrene-amino mercapto thiadiazole unit.

    Science.gov (United States)

    Rani, B Kirthika; John, S Abraham

    2017-09-15

    A highly selective and sensitive determination of Hg(2+) in water samples with bioimaging applications in living cells using a fluorogenic pyrene-amino mercapto thiadiazole (PYAMT) probe is described. The probe PYAMT exhibited three absorption peaks at 333, 348 and 394nm and emission maxima at 378, 388 and 397nm (λex=348nm). It showed significant fluorescent quenching (96%) with I/I0=0.051 upon the addition of 2.5μM Hg(2+) ion in CH3CN(ACN):H2O (1:1, v/v; pH 7.2), whereas its fluorescence remained unaltered in the presence of other metal ions. The quenching phenomenon is attributed to the heavy atom effect of Hg(2+) ion followed by electron transfer. The fluorescence intensity decreased linearly against a wide range from 100nM to 2.5μM Hg(2+) (R(2)=0.9937) with a limit of detection as low as 0.35nM (S/N=3). The binding stoichiometry ratio of PYAMT-Hg(2+) is proved to be 1:1 by fluorescence and DFT measurements. The sensor possesses high association constant with Hg(2+) ion in the order of 9.08×10(5)M(-1) and it is also capable of reversibly detecting cysteine with OFF-ON mechanism. Finally, the proposed method is successfully applied to selectively detect Hg(2+) ion in real water samples and bioimaging studies in live cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Mercury's thermo-chemical evolution from numerical models constrained by Messenger observations

    Science.gov (United States)

    Tosi, N.; Breuer, D.; Plesa, A. C.; Wagner, F.; Laneuville, M.

    2012-04-01

    The Messenger spacecraft, in orbit around Mercury for almost one year, has been delivering a great deal of new information that is changing dramatically our understanding of the solar system's innermost planet. Tracking data of the Radio Science experiment yielded improved estimates of the first coefficients of the gravity field that permit to determine the normalized polar moment of inertia of the planet (C/MR2) and the ratio of the moment of inertia of the mantle to that of the whole planet (Cm/C). These two parameters provide a strong constraint on the internal mass distribution and, in particular, on the core mass fraction. With C/MR2 = 0.353 and Cm/C = 0.452 [1], interior structure models predict a core radius as large as 2000 km [2], leaving room for a silicate mantle shell with a thickness of only ~ 400 km, a value significantly smaller than that of 600 km usually assumed in parametrized [3] as well as in numerical models of Mercury's mantle dynamics and evolution [4]. Furthermore, the Gamma-Ray Spectrometer measured the surface abundance of radioactive elements, revealing, besides uranium and thorium, the presence of potassium. The latter, being moderately volatile, rules out traditional formation scenarios from highly refractory materials, favoring instead a composition not much dissimilar from a chondritic model. Considering a 400 km thick mantle, we carry out a large series of 2D and 3D numerical simulations of the thermo-chemical evolution of Mercury's mantle. We model in a self-consistent way the formation of crust through partial melting using Lagrangian tracers to account for the partitioning of radioactive heat sources between mantle and crust and variations of thermal conductivity. Assuming the relative surface abundance of radiogenic elements observed by Messenger to be representative of the bulk mantle composition, we attempt at constraining the degree to which uranium, thorium and potassium are concentrated in the silicate mantle through a broad

  9. Unified Science Information Model for SoilSCAPE using the Mercury Metadata Search System

    Science.gov (United States)

    Devarakonda, Ranjeet; Lu, Kefa; Palanisamy, Giri; Cook, Robert; Santhana Vannan, Suresh; Moghaddam, Mahta Clewley, Dan; Silva, Agnelo; Akbar, Ruzbeh

    2013-12-01

    methods including OAI-PMH [3]. The Mercury search interface then allows users to perform simple, fielded, spatial and temporal searches across a central harmonized index of metadata. Mercury supports various metadata standards including FGDC, ISO-19115, DIF, Dublin-Core, Darwin-Core, and EML. This poster describes in detail how Mercury implements the Unified Science Information Model for Soil moisture data. References: [1]Devarakonda R., et al. Mercury: reusable metadata management, data discovery and access system. Earth Science Informatics (2010), 3(1): 87-94. [2]Devarakonda R., et al. Daymet: Single Pixel Data Extraction Tool. http://daymet.ornl.gov/singlepixel.html (2012). Last Accesses 10-01-2013 [3]Devarakonda R., et al. Data sharing and retrieval using OAI-PMH. Earth Science Informatics (2011), 4(1): 1-5.

  10. Modelling mercury accumulation in minerogenic peat combining FTIR-ATR spectroscopy and partial least squares (PLS)

    Science.gov (United States)

    Pérez-Rodríguez, Marta; Horák-Terra, Ingrid; Rodríguez-Lado, Luis; Martínez Cortizas, Antonio

    2016-11-01

    Despite its potential, infrared spectroscopy combined with multivariate statistics has been seldom used to model peat properties with environmental value, such us the concentration of potentially toxic metals. In this research, we applied attenuated total reflectance (ATR) Fourier-Transform Infrared (FTIR) spectroscopy to evaluate the ability of the technique to predict mercury concentrations in late-Pleistocene/Holocene peat from a minerogenic peatland from Minas Gerais (Brazil). Mercury concentrations were analysed using a Milestone DMA-80 analyzer and attenuated total reflectance FTIR-ATR was performed using a Gladi-ATR (Pike Technologies) in the mid IR spectrum (4000-400 cm- 1). Concentrations were modelled using principal components (PCR) and partial least squares regression (PLS). The performance of the models varied between moderate and very good (R2 0.67-0.90), with low RMSD values (0.35-1.06). A PLS model based on three latent vectors (LV1 to LV3) provided the best (R2 0.90, RMSD 0.35) results. LV1 reflected total organic matter content versus mineral matter (mainly quartz from local fluxes), LV2 was related to dust deposition from regional sources, and LV3 reflected peat organic matter decomposition. Compared to a previous investigation based on geochemical data, the spectroscopy-based PLS model performed better, but it has to be complemented with additional data (as δ13 C ratios) to reliably reproduce the changes of the factors controlling mercury accumulation over time. This, time- and cost-effective, methodology may help to develop multi-core approaches to study the within and between mire (of a similar type and area) variability in mercury accumulation, and probably also other peat properties.

  11. Mercury Speciation in Coal-Fired Power Plant Flue Gas-Experimental Studies and Model Development

    Energy Technology Data Exchange (ETDEWEB)

    Radisav Vidic; Joseph Flora; Eric Borguet

    2008-12-31

    The overall goal of the project was to obtain a fundamental understanding of the catalytic reactions that are promoted by solid surfaces present in coal combustion systems and develop a mathematical model that described key phenomena responsible for the fate of mercury in coal-combustion systems. This objective was achieved by carefully combining laboratory studies under realistic process conditions using simulated flue gas with mathematical modeling efforts. Laboratory-scale studies were performed to understand the fundamental aspects of chemical reactions between flue gas constituents and solid surfaces present in the fly ash and their impact on mercury speciation. Process models were developed to account for heterogeneous reactions because of the presence of fly ash as well as the deliberate addition of particles to promote Hg oxidation and adsorption. Quantum modeling was used to obtain estimates of the kinetics of heterogeneous reactions. Based on the initial findings of this study, additional work was performed to ascertain the potential of using inexpensive inorganic sorbents to control mercury emissions from coal-fired power plants without adverse impact on the salability fly ash, which is one of the major drawbacks of current control technologies based on activated carbon.

  12. Mathematical Modelling of the Electrode Process of Azithromycin Using Cyclic Voltammetry at Hanging Mercury Drop Electrode

    Directory of Open Access Journals (Sweden)

    Maha F. Tutunji

    2002-11-01

    Full Text Available A theoretical treatment is presented to predict the kinetic behaviour of azithromycin at the surface of hanging mercury drop electrode using cyclic voltammetry. A model is developed to incorporate the occurrence of adsorption of the oxidized and reduced species of azithromycin at the surface of mercury drop electrode. An analytical solution was obtained using MATHEMATICA (V-3, Wolfram Research, Inc. to predict the cyclic voltammetric profiles by calculating the currents resulting after applying variable potentials ranging –1.9 to –1.3 V versus Ag/AgCl. Simulation runs at different initial concentrations of azithromycin and different scan rates showed good agreement with experimental findings. However, this model should be modified to describe a multilayer adsorption with irreversible electrochemical reaction.

  13. Numerical modelling of ion transport in flames

    KAUST Repository

    Han, Jie

    2015-10-20

    This paper presents a modelling framework to compute the diffusivity and mobility of ions in flames. The (n, 6, 4) interaction potential is adopted to model collisions between neutral and charged species. All required parameters in the potential are related to the polarizability of the species pair via semi-empirical formulas, which are derived using the most recently published data or best estimates. The resulting framework permits computation of the transport coefficients of any ion found in a hydrocarbon flame. The accuracy of the proposed method is evaluated by comparing its predictions with experimental data on the mobility of selected ions in single-component neutral gases. Based on this analysis, the value of a model constant available in the literature is modified in order to improve the model\\'s predictions. The newly determined ion transport coefficients are used as part of a previously developed numerical approach to compute the distribution of charged species in a freely propagating premixed lean CH4/O2 flame. Since a significant scatter of polarizability data exists in the literature, the effects of changes in polarizability on ion transport properties and the spatial distribution of ions in flames are explored. Our analysis shows that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect that the modelling framework proposed here will benefit future efforts in modelling the effect of external voltages on flames. Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/13647830.2015.1090018. © 2015 Taylor & Francis.

  14. Modelling transport and transformation of mercury fractions in heavily contaminated mountain streams by coupling a GIS-based hydrological model with a mercury chemistry model.

    Science.gov (United States)

    Lin, Yan; Larssen, Thorjørn; Vogt, Rolf D; Feng, Xinbin; Zhang, Hua

    2011-10-01

    Many heavily polluted areas are located in remote regions that lack routine hydrologic monitoring. A modelling method that can produce scenarios of water chemistry trends for regions that lack hydrological data is therefore needed. The Wanshan mining area, in Guizhou province in south-western China, is such a region, as it is heavily polluted with mercury (Hg). In order to model Hg transport in a stream draining the Wanshan mining area, a Geographic Information System (GIS) hydrologic model (HEC-HMS) was coupled with a simulation model for Hg fractions in water (WASP Hg). Hydrological variations in the stream flow can thereby be simulated based on readily available precipitation data. The WASP 7 MERC Hg model was used for simulating variations in total Hg, dissolved Hg and methyl-Hg concentrations. The results of HEC-HMS modelling of flow show clear seasonal variation. Winter (Oct-Dec) constitutes the dry season with low flow, while the summer season (Jun-Aug) is rainy with high flow. 48% of total annual precipitation happens in the three summer months. The stream flows at the high flow events were several times higher than normal flow. The modelled total suspended solids and Hg concentrations were tested against monitoring data from two sampling campaigns conducted in September 2007 and August 2008. The model produced reasonable simulations for TSS, THg, DHg and MeHg, with relative errors generally around 10% for the modelled parameters. High flow events are the main contributors for release of both suspended particles and Hg. The three high flow events account for about 50% of annual discharge of THg. The annual total discharge of Hg was 8.8 kg Hg high up in the stream and 2.6 kg where the stream meets a large river 20 km downstream of the pollution source. Hence, about 70% of Hg is retained in the stream through sedimentation.

  15. Fast Quantum Rabi Model with Trapped Ions

    Science.gov (United States)

    Moya-Cessa, Héctor M.

    2016-12-01

    We show how to produce a fast quantum Rabi model with trapped ions. Its importance resides not only in the acceleration of the phenomena that may be achieved with these systems, from quantum gates to the generation of nonclassical states of the vibrational motion of the ion, but also in reducing unwanted effects such as the decay of coherences that may appear in such systems.

  16. A Comparison of Mathematical Models of Fish Mercury Concentration as a Function of Atmospheric Mercury Deposition Rate and Watershed Characteristics

    Science.gov (United States)

    Smith, R. A.; Moore, R. B.; Shanley, J. B.; Miller, E. K.; Kamman, N. C.; Nacci, D.

    2009-12-01

    Mercury (Hg) concentrations in fish and aquatic wildlife are complex functions of atmospheric Hg deposition rate, terrestrial and aquatic watershed characteristics that influence Hg methylation and export, and food chain characteristics determining Hg bioaccumulation. Because of the complexity and incomplete understanding of these processes, regional-scale models of fish tissue Hg concentration are necessarily empirical in nature, typically constructed through regression analysis of fish tissue Hg concentration data from many sampling locations on a set of potential explanatory variables. Unless the data sets are unusually long and show clear time trends, the empirical basis for model building must be based solely on spatial correlation. Predictive regional scale models are highly useful for improving understanding of the relevant biogeochemical processes, as well as for practical fish and wildlife management and human health protection. Mechanistically, the logical arrangement of explanatory variables is to multiply each of the individual Hg source terms (e.g. dry, wet, and gaseous deposition rates, and residual watershed Hg) for a given fish sampling location by source-specific terms pertaining to methylation, watershed transport, and biological uptake for that location (e.g. SO4 availability, hill slope, lake size). This mathematical form has the desirable property that predicted tissue concentration will approach zero as all individual source terms approach zero. One complication with this form, however, is that it is inconsistent with the standard linear multiple regression equation in which all terms (including those for sources and physical conditions) are additive. An important practical disadvantage of a model in which the Hg source terms are additive (rather than multiplicative) with their modifying factors is that predicted concentration is not zero when all sources are zero, making it unreliable for predicting the effects of large future reductions in

  17. MERGANSER: an empirical model to predict fish and loon mercury in New England lakes

    Science.gov (United States)

    Shanley, James B.; Moore, Richard; Smith, Richard A.; Miller, Eric K.; Simcox, Alison; Kamman, Neil; Nacci, Diane; Robinson, Keith; Johnston, John M.; Hughes, Melissa M.; Johnston, Craig; Evers, David; Williams, Kate; Graham, John; King, Susannah

    2012-01-01

    MERGANSER (MERcury Geo-spatial AssessmeNtS for the New England Region) is an empirical least-squares multiple regression model using mercury (Hg) deposition and readily obtainable lake and watershed features to predict fish (fillet) and common loon (blood) Hg in New England lakes. We modeled lakes larger than 8 ha (4404 lakes), using 3470 fish (12 species) and 253 loon Hg concentrations from 420 lakes. MERGANSER predictor variables included Hg deposition, watershed alkalinity, percent wetlands, percent forest canopy, percent agriculture, drainage area, population density, mean annual air temperature, and watershed slope. The model returns fish or loon Hg for user-entered species and fish length. MERGANSER explained 63% of the variance in fish and loon Hg concentrations. MERGANSER predicted that 32-cm smallmouth bass had a median Hg concentration of 0.53 μg g-1 (root-mean-square error 0.27 μg g-1) and exceeded EPA's recommended fish Hg criterion of 0.3 μg g-1 in 90% of New England lakes. Common loon had a median Hg concentration of 1.07 μg g-1 and was in the moderate or higher risk category of >1 μg g-1 Hg in 58% of New England lakes. MERGANSER can be applied to target fish advisories to specific unmonitored lakes, and for scenario evaluation, such as the effect of changes in Hg deposition, land use, or warmer climate on fish and loon mercury.

  18. Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model.

    Science.gov (United States)

    Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B; Hao, Jiming

    2014-07-01

    China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35-50% of THg concentration and 50-70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China.

  19. Modelling of mercury isotope separation in CP stellar atmospheres: results and problems

    CERN Document Server

    Sapar, A; Sapar, L; Poolamäe, R; 10.1016/j.newar.2009.08.010

    2009-01-01

    Formation of anomalous isotope abundances in the atmospheres of chemically peculiar (CP) stars can be explained by light-induced drift (LID). This effect is additional to the radiative acceleration and appears due to systematic asymmetry of radiative flux in partly overlapping isotopic spectral line profiles. LID causes levitation of an isotope with a red-shifted spectral line and sinking of an isotope with a blue-shifted line, generating thus diffusive separation of isotopes. We have studied diffusion of mercury as a typical well-studied isotope-rich heavy metal. Our model computations show that in mercury-rich quiescent atmospheres of CP stars LID causes levitation of the heavier mercury isotopes and sinking of the lighter ones. Precise quantitative modelling of the process of isotope separation demands very high-resolution computations and the high-precision input data, including data on hyperfine and isotopic splitting of spectral lines, adequate line profiles and impact cross-sections. Presence of microt...

  20. Simulation of atmospheric mercury depletion events (AMDEs during polar springtime using the MECCA box model

    Directory of Open Access Journals (Sweden)

    Z.-Q. Xie

    2008-12-01

    Full Text Available Atmospheric mercury depletion events (AMDEs during polar springtime are closely correlated with bromine-catalyzed tropospheric ozone depletion events (ODEs. To study gas- and aqueous-phase reaction kinetics and speciation of mercury during AMDEs, we have included mercury chemistry into the box model MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere, which enables dynamic simulation of bromine activation and ODEs.

    We found that the reaction of Hg with Br atoms dominates the loss of gaseous elemental mercury (GEM. To explain the experimentally observed synchronous depletion of GEM and O3, the reaction rate of Hg+BrO has to be much lower than that of Hg+Br. The synchronicity is best reproduced with rate coefficients at the lower limit of the literature values for both reactions, i.e. kHg+Br≈3×10−13 and kHg+BrO≤1×10−15 cm3 molecule−1 s−1, respectively.

    Throughout the simulated AMDEs, chem{BrHgOBr} was the most abundant reactive mercury species, both in the gas phase and in the aqueous phase. The aqueous-phase concentrations of BrHgOBr, HgBr2, and HgCl2 were several orders of magnitude larger than that of Hg(SO322−.

    Considering chlorine chemistry outside depletion events (i.e. without bromine activation, the concentration of total divalent mercury in sea-salt aerosol particles (mostly HgCl42− was much higher than in dilute aqueous droplets (mostly Hg(SO322−, and did not exhibit a diurnal cycle (no correlation with HO2 radicals.

  1. Simulation of atmospheric mercury depletion events (AMDEs during polar springtime using the MECCA box model

    Directory of Open Access Journals (Sweden)

    Z.-Q. Xie

    2008-07-01

    Full Text Available Atmospheric mercury depletion events (AMDEs during polar springtime are closely correlated with bromine-catalyzed tropospheric ozone depletion events (ODEs. To study gas- and aqueous-phase reaction kinetics and speciation of mercury during AMDEs, we have included mercury chemistry into the box model MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere, which enables dynamic simulation of bromine activation and ODEs.

    We found that the reaction of Hg with Br atoms dominates the loss of gaseous elemental mercury (GEM. To explain the experimentally observed synchronous destruction of Hg and O3, the reaction rate of Hg+BrO has to be much lower than that of Hg+Br. The synchronicity is best reproduced with rate coefficients at the lower limit of the literature values for both reactions, i.e. kHg+Br≈3×10-13 and kHg+BrO≤1×10-15cm3 mol-1 s-1, respectively.

    Throughout the simulated AMDEs, BrHgOBr was the most abundant reactive mercury species, both in the gas phase and in the aqueous phase. The aqueous phase concentrations of BrHgOBr, HgBr2, and HgCl2 were several orders of magnitude larger than that of Hg(SO32-2.

    Considering chlorine chemistry outside depletion events (i.e. without bromine activation, the concentration of total divalent mercury in sea-salt aerosol particles (mostly HgCl2 was much higher than in dilute aqueous droplets (mostly Hg(SO32-2, and did not exhibit a diurnal cycle (no correlation with HO2 radicals.

  2. Oxidation of Mercury in Products of Coal Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Peter Walsh; Giang Tong; Neeles Bhopatkar; Thomas Gale; George Blankenship; Conrad Ingram; Selasi Blavo Tesfamariam Mehreteab; Victor Banjoko; Yohannes Ghirmazion; Heng Ban; April Sibley

    2009-09-14

    scale, burning bituminous coals (Gale, 2006) and blends of bituminous coals with Powder River Basin coal (Gale, 2005). The removal of mercury by fly ash and unburned carbon in the flue gas from combustion of the bituminous coals and blends was reproduced with satisfactory accuracy by the model. The enhancement of mercury capture in the presence of calcium (Gale, 2005) explained a synergistic effect of blending on mercury removal across the baghouse. The extent of mercury oxidation, on the other hand, was not so well described by the simulation, because of oversensitivity of the oxidation process in the model to the concentration of unburned carbon. Combined catalysts and sorbents for oxidation and removal of mercury from flue gas at low temperature were based on surfactant-templated silicas containing a transition metal and an organic functional group. The presence of both metal ions and organic groups within the pore structure of the materials is expected to impart to them the ability to simultaneously oxidize elemental mercury and adsorb the resulting oxidized mercury. Twelve mesoporous organosilicate catalysts/sorbents were synthesized, with and without metals (manganese, titanium, vanadium) and organic functional groups (aminopropyl, chloropropyl, mercaptopropyl). Measurement of mercury oxidation and adsorption by the candidate materials remains for future work.

  3. Measurements of atmospheric mercury concentrations in Northwestern and Central Europe - comparison of experimental data and model results

    Energy Technology Data Exchange (ETDEWEB)

    Ebinghaus, R. [GKSS-Forschungszentrum Geesthacht GmbH (Germany); Kock, H.H. [GKSS-Forschungszentrum Geesthacht GmbH (Germany); Jennings, S.G. [University Coll., Galway (Ireland); McCartin, P. [University Coll., Galway (Ireland); Orren, M.J. [University Coll., Galway (Ireland)

    1995-12-31

    Field experiments were carried out at various sites in Europe to compare ambient air and precipitation concentrations of atmospheric mercury with model data. In addition, ozone and aerosol black carbon concentrations in air were measured simultaneously as input data for validation of the EMEP-based European long-range transport model. Data sets for mercury in air and precipitation, ozone and aerosol black carbon show that the selcted sites range from background conditions for Northwestern Europe to regionally influenced air masses from heavily industrialized Central Europe. Measured 12 h average mercury concentrations in air range from 2.1 ng m{sup -3} for Mace Head, Ireland to 8.2 ng m{sup -3} for the Halle/Leipzig/Bitterfeld area in former German Democratic Republic. Precipitation concentrations of total mercury from 17 to 460 ng l{sup -1} were measured from 1991 to 1993 for the same sites. Experimental data and model results for total geaseous mercury and mercury in precipitation are in good agreement. (orig.)

  4. Mercury cycling in aquatic ecosystems and trophic state-related variables--implications from structural equation modeling.

    Science.gov (United States)

    Pollman, Curtis D

    2014-11-15

    Structural equation modeling (SEM) provides a framework that can more properly handle complex variable interactions inherent in mercury cycling and its bioaccumulation compared to more traditional regression-based methods. SEM was applied to regional data sets for three different types of aquatic ecosystems within Florida, USA--lakes, streams, and the Everglades--to evaluate the underlying nature (i.e., indirect and direct) of the relationships between fish mercury concentrations and trophic state related variables such as nutrients, dissolved organic carbon (DOC), sulfate, and alkalinity. The modeling results indicated some differences in key variable relationships--for example, the effect of nutrients on fish mercury in lakes and streams was uniformly negative through direct and indirect pathways consistent with biodilution or eutrophication-associated effects on food web structure. Somewhat surprisingly, however, was that total phosphorus did not serve as a meaningful variable in the Everglades model, apparently because its effects were masked or secondary to the effects of DOC. What is perhaps a more important result were two key similarities across the three systems. First, the modeling clearly indicates that the dominant influence on fish tissue mercury concentrations in all three systems is related to variations in the methylmercury signal. Second, the modeling demonstrated that the effect of DOC on fish mercury concentrations was exerted through multiple and antagonistic pathways, including facilitated transport of total mercury and methylmercury, enhanced rates of methylation, and limitations imposed on bioavailability. Indeed, while the individual DOC pathways in the models were all highly significant (generally pmodel was greatly reduced or insignificant. These results can help explain contradictory results obtained previously by other researchers in other systems, and illustrate the importance of SEM as a modeling tool when studying systems with complex

  5. Target-induced formation of gold amalgamation on DNA-based sensing platform for electrochemical monitoring of mercury ion coupling with cycling signal amplification strategy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jinfeng; Tang, Juan; Zhou, Jun; Zhang, Lan; Chen, Guonan; Tang, Dianping, E-mail: dianping.tang@fzu.edu.cn

    2014-01-31

    Graphical abstract: -- Highlights: •We report a new electrochemical sensing protocol for the detection of mercury ion. •Gold amalgamation on DNA-based sensing platform was used as nanocatalyst. •The signal was amplified by cycling signal amplification strategy. -- Abstract: Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg{sup 2+}), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg{sup 2+} by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T{sub (25)} oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg{sup 2+} ion was intercalated into the DNA polyion complex membrane based on T–Hg{sup 2+}–T coordination chemistry. The chelated Hg{sup 2+} ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH{sub 4} and Ru(NH{sub 3}){sub 6}{sup 3+} for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg{sup 2+} level in the sample, and has a detection limit of 0.02 nM with a dynamic range of up to 1000 nM Hg{sup 2+}. The strategy afforded exquisite selectivity for Hg{sup 2+} against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg{sup 2+} in spiked tap-water samples, and the recovery was 87.9–113.8%.

  6. A FRET-based fluorescent probe for mercury ions in water and living cells

    Science.gov (United States)

    Zhang, Bo; Ma, Pinyi; Gao, Dejiang; Wang, Xinghua; Sun, Ying; Song, Daqian; Li, Xuwen

    2016-08-01

    On the basis of fluorescence resonance energy transfer (FRET), a new rhodamine derivative (DRh) was synthesized as a ratiometric fluorescent probe for detecting Hg2 + in water and living cells samples. The recognition properties of the probe DRh with metal ions had been investigated in H2O/CH3CN (9:1, v/v; Tris-HCl 50 mmol L- 1; pH = 7.0) solution by the UV-Vis spectrophotometry and the fluorescence spectrophotometry. The results showed that the probe DRh exhibited the selective recognition of Hg2 +. Upon the addition of Hg2 +, the spirolactam ring of probe DRh was opened. The 1:1 stoichiometric structure between DRh and Hg2 + were supported by Job's plot, MS and DFT theoretical calculations. The linearly fluorescence intensity ratio (I582/I538) is proportional to the concentration of Hg2 + in the range 0-30 μmol L- 1. The limit of detection (LOD) of Hg2 + is 0.008 μmol L- 1 (base on S/N = 3). The present probe was applied to the determination of Hg2 + in neutral water samples and gave recoveries ranging from 104.5 to 107.9%. Furthermore, the fluorescent probe also can be applied as a bioimaging reagent for Hg2 + detection in HeLa cells.

  7. Ohmic model for electrodeposition of metallic ions

    Energy Technology Data Exchange (ETDEWEB)

    Gliozzi, A.S. [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy); Alexe-Ionescu, A.L. [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy); Department of Physics, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest (Romania); Barbero, G., E-mail: giovanni.barbero@polito.it [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 29, 10129 Torino (Italy)

    2015-10-23

    An ohmic model to describe the electrodeposition of metallic ions on the electrodes is proposed. We assume that the ionic distribution is homogeneous across the electrolytic cell, and that the ionic current is due to the bulk electric field. The nucleation in the electrodeposition is supposed to be well described by a kinetic equation at the electrode, taking into account the neutralization of metallic ions on the electrodes. Two cases are considered. In the first case the characteristic time describing the neutralization of the ions is supposed to be negligible with respect to the flight time of the ions across the cell. In this framework the bulk electric field coincides with the external electric field, and our analysis gives analytical formulae for the surface density of deposited ions and for the electric current in the external circuit. The case where the two characteristic times are comparable, and the effective electric field in the bulk depends on the surface deposition, is considered too. In this case the ordinary differential equations describing the ionic distribution and the adsorption phenomenon have to be solved numerically. The agreement between the presented model and the experimental results published by several groups is reasonably good.

  8. SPEEDUP{trademark} ion exchange column model

    Energy Technology Data Exchange (ETDEWEB)

    Hang, T.

    2000-03-06

    A transient model to describe the process of loading a solute onto the granular fixed bed in an ion exchange (IX) column has been developed using the SpeedUp{trademark} software package. SpeedUp offers the advantage of smooth integration into other existing SpeedUp flowsheet models. The mathematical algorithm of a porous particle diffusion model was adopted to account for convection, axial dispersion, film mass transfer, and pore diffusion. The method of orthogonal collocation on finite elements was employed to solve the governing transport equations. The model allows the use of a non-linear Langmuir isotherm based on an effective binary ionic exchange process. The SpeedUp column model was tested by comparing to the analytical solutions of three transport problems from the ion exchange literature. In addition, a sample calculation of a train of three crystalline silicotitanate (CST) IX columns in series was made using both the SpeedUp model and Purdue University's VERSE-LC code. All test cases showed excellent agreement between the SpeedUp model results and the test data. The model can be readily used for SuperLig{trademark} ion exchange resins, once the experimental data are complete.

  9. Mercury emissions from coal combustion: modeling and comparison of Hg capture in a fabric filter versus an electrostatic precipitator.

    Science.gov (United States)

    Scala, Fabrizio; Clack, Herek L

    2008-04-01

    Mercury emissions from coal combustion must be reduced, in response to new air quality regulations in the U.S. Although the most mature control technology is adsorption across a dust cake of powdered sorbent in a fabric filter (FF), most particulate control in the U.S. associated with coal combustion takes the form of electrostatic precipitation (ESP). Using recently developed models of mercury adsorption within an ESP and within a growing sorbent bed in a FF, parallel analyses of elemental mercury (Hg(0)) uptake have been conducted. The results show little difference between an ESP and a FF in absolute mercury removal for a low-capacity sorbent, with a high-capacity sorbent achieving better performance in the FF. Comparisons of fractional mercury uptake per-unit-pressure-drop provide a means for incorporating and comparing the impact of the much greater pressure drop of a FF as compared to an ESP. On a per-unit-pressure-drop basis, mercury uptake within an ESP exhibited better performance, particularly for the low-capacity sorbent and high mass loadings of both sorbents.

  10. MESSENGER: Exploring Mercury's Magnetosphere

    Science.gov (United States)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  11. Modeling the ion channel structure of cecropin.

    OpenAIRE

    Durell, S R; Raghunathan, G.; Guy, H R

    1992-01-01

    Atomic-scale computer models were developed for how cecropin peptides may assemble in membranes to form two types of ion channels. The models are based on experimental data and physiochemical principles. Initially, cecropin peptides, in a helix-bend-helix motif, were arranged as antiparallel dimers to position conserved residues of adjacent monomers in contact. The dimers were postulated to bind to the membrane with the NH2-terminal helices sunken into the head-group layer and the COOH-termin...

  12. A modified QWASI model for fate and transport modeling of mercury between the water-ice-sediment in Lake Ulansuhai.

    Science.gov (United States)

    Liu, Yu; Li, Changyou; Anderson, Bruce; Zhang, Sheng; Shi, Xiaohong; Zhao, Shengnan

    2017-06-01

    Mercury contamination from industrial and agricultural drainage into lakes and rivers is a growing concern in Northern China. Lake Ulansuhai, located in Hetao irrigation district in Inner Mongolia, is the only sink for the all industrial and agricultural drainage and sole outlet for this district to the Yellow River, which is one of the main source of drinking water for the numerous cities and towns downstream. Because Ulansuahi is ice-covered during winter, the QWASI model was modified by adding an ice equation to get a more accurate understanding of the fate and transport of mercury within the lake. Both laboratory and field tests were carried out during the ice growth period. The aquivalence and mass balance approaches were used to develop the modified QWASI + ice model. The margins of error between the modelled and the measured average concentrations of Hg in ice, water, and sediment were 30%, 26.2%, and 19.8% respectively. These results suggest that the new QWASI + ice model could be used to more accurately represent the fate and transport of mercury in the seasonally ice-covered lakes, during the ice growth period.

  13. Modeling of ion conductivity in Nafion membranes

    Institute of Scientific and Technical Information of China (English)

    YANG Zhen; PENG Xiaofeng; WANG Buxuan; LEE Duujong; DUAN Yuanyuan

    2007-01-01

    A theoretical investigation was conducted to describe the ion transport behavior in a Nafion Membrane of proton exchange membrane fuel cells (PEMFC).By analyzing the surface energy configuration of the ionic clusters in a Nafion membrane,an equivalent field intensity,Ee,was introduced to facilitate the analysis of surface resistance against ion conduction in the central region of clusters.An expression was derived for ionic conductivity incorporating the influence of surface resistance.A face-centered cubic (FCC)lattice model for a spatial cluster distribution was used to modify the effect of water content on ionic conductivity in the polymeric matrix,i.e.,the regions between clusters.Compared with the available empirical correlations,the new expression showed much better agreement with the available experimental results,which indicates the rationality to consider the structural influence on ion conduction in water-swollen Nation membranes.

  14. A reactive transport model for mercury fate in soil--application to different anthropogenic pollution sources.

    Science.gov (United States)

    Leterme, Bertrand; Blanc, Philippe; Jacques, Diederik

    2014-11-01

    Soil systems are a common receptor of anthropogenic mercury (Hg) contamination. Soils play an important role in the containment or dispersion of pollution to surface water, groundwater or the atmosphere. A one-dimensional model for simulating Hg fate and transport for variably saturated and transient flow conditions is presented. The model is developed using the HP1 code, which couples HYDRUS-1D for the water flow and solute transport to PHREEQC for geochemical reactions. The main processes included are Hg aqueous speciation and complexation, sorption to soil organic matter, dissolution of cinnabar and liquid Hg, and Hg reduction and volatilization. Processes such as atmospheric wet and dry deposition, vegetation litter fall and uptake are neglected because they are less relevant in the case of high Hg concentrations resulting from anthropogenic activities. A test case is presented, assuming a hypothetical sandy soil profile and a simulation time frame of 50 years of daily atmospheric inputs. Mercury fate and transport are simulated for three different sources of Hg (cinnabar, residual liquid mercury or aqueous mercuric chloride), as well as for combinations of these sources. Results are presented and discussed with focus on Hg volatilization to the atmosphere, Hg leaching at the bottom of the soil profile and the remaining Hg in or below the initially contaminated soil layer. In the test case, Hg volatilization was negligible because the reduction of Hg(2+) to Hg(0) was inhibited by the low concentration of dissolved Hg. Hg leaching was mainly caused by complexation of Hg(2+) with thiol groups of dissolved organic matter, because in the geochemical model used, this reaction only had a higher equilibrium constant than the sorption reactions. Immobilization of Hg in the initially polluted horizon was enhanced by Hg(2+) sorption onto humic and fulvic acids (which are more abundant than thiols). Potential benefits of the model for risk management and remediation of

  15. Poly(ester sulphonic acid) coated mercury thin film electrodes: characterization and application in batch injection analysis stripping voltammetry of heavy metal ions.

    Science.gov (United States)

    Brett, C M; Fungaro, D A

    2000-01-10

    Mercury-thin film electrodes coated with a thin film of poly(ester sulphonic acid) (PESA) have been investigated for application in the analysis of trace heavy metals by square wave anodic stripping voltammetry using the batch injection analysis (BIA) technique. Different polymer dispersion concentrations in water/acetone mixed solvent are investigated and are characterised by electrochemical impedance measurements on glassy carbon and on mercury film electrodes. The influence of electrolyte anion, acetate or nitrate, on polymer film properties is demonstrated, acetate buffer being shown to be preferable for stripping voltammetry applications. Although stripping currents are between 30 and 70% less at the coated than at bare mercury thin film electrodes, the influence of model surfactants on stripping response is shown to be very small. The effect of the composition of the modifier film dispersion on calibration plots is shown; however, detection limits of around 5 nM are found for all modified electrodes tested. This coated electrode is an alternative to Nafion-coated mercury thin film electrodes for the analysis of trace metals in complex matrices, particularly useful when there is a high concentration of non-ionic detergents.

  16. Oxidation of elemental mercury in the atmosphere; Constraints imposed by global scale modelling

    Energy Technology Data Exchange (ETDEWEB)

    Bergan, Torbjoern; Rodhe, Henning [Stockholm Univ. (Sweden). Dept. of Meteorology

    2000-05-01

    Based on the global mercury model published by Bergan et al. (1999), we present here further results from simulations where the central theme has been to evaluate the role of ozone and the hydroxyl radical as possible gas phase oxidants for the oxidation of elemental mercury in the atmosphere. The magnitude of natural and man-made mercury emissions are taken from recent literature estimates and the flux from land areas is assumed to vary by season. We consider only two mercury reservoirs, elemental mercury, Hg{sup 0}, and the more soluble divalent form, Hgll. Wet and dry deposition of Hgll is explicitly treated. Applying monthly mean fields of ozone for the oxidation of gas phase Hg{sup 0} and using the reaction rate by Hall (1995) yields a global transformation of Hg{sup 0} to Hgll which is too slow to keep the simulated concentration of Hg{sup 0} near observed values. This shows that there are additional important removal processes for Hg{sup 0} or that the reaction rate proposed by Hall (1995) is too slow. A simulation in which the oxidation rate was artificially increased, so that the global turn-over time of Hg{sup 0} was one year and the simulated average concentration of Hg{sup 0} was realistic, produced latitudinal and seasonal variations in Hg{sup 0} that did not support the hypothesis that gas phase reaction with O{sub 3} is the major oxidation process for Hg{sup 0}. Recent studies indicate that OH may be an important gas phase oxidant for Hg{sup 0}. Using OH as the oxidant and applying the preliminary oxidation rate by Sommar et al. (1999) gave an unrealistically large removal of Hg{sup 0} from the atmosphere. From calculations using a slower reaction rate, corresponding to a turn-over time of Hg{sup 0} of one year, we calculated concentrations of both Hg{sup 0} in surface air and Hgll in precipitation which correspond, both in magnitude and temporal variation, to seasonal observations in Europe and North America. This result supports the suggestion that

  17. Hopping models for ion conduction in noncrystals

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Schrøder, Thomas

    2007-01-01

    Ion conduction in noncrystals (glasses, polymers, etc) has a number of properties in common. In fact, from a purely phenomenological point of view, these properties are even more widely observed: ion conduction behaves much like electronic conduction in disordered materials (e.g., amorphous...... semiconductors). These universalities are subject of much current interest, for instance interpreted in the context of simple hopping models. In the present paper we first discuss the temperature dependence of the dc conductivity in hopping models and the importance of the percolation phenomenon. Next......, the experimental (quasi)universality of the ac conductivity is discussed. It is shown that hopping models are able to reproduce the experimental finding that the response obeys time-temperature superposition, while at the same time a broad range of activation energies is involved in the conduction process. Again...

  18. The transport behaviour of elemental mercury DNAPL in saturated porous media: Analysis of field observations and two-phase flow modelling

    Science.gov (United States)

    Sweijen, Thomas; Hartog, Niels; Marsman, Annemieke; Keijzer, Thomas J. S.

    2014-06-01

    Mercury is a contaminant of global concern. The use of elemental mercury in various (former) industrial processes, such as chlorine production at chlor-alkali plants, is known to have resulted in soil and groundwater contaminations worldwide. However, the subsurface transport behaviour of elemental mercury as an immiscible dense non-aqueous phase liquid (DNAPL) in porous media has received minimal attention to date. Even though, such insight would aid in the remediation effort of mercury contaminated sites. Therefore, in this study a detailed field characterization of elemental mercury DNAPL distribution with depth was performed together with two-phase flow modelling, using STOMP. This is to evaluate the dynamics of mercury DNAPL migration and the controls on its distribution in saturated porous media. Using a CPT-probe mounted with a digital camera, in-situ mercury DNAPL depth distribution was obtained at a former chlor-alkali-plant, down to 9 m below ground surface. Images revealing the presence of silvery mercury DNAPL droplets were used to quantify its distribution, characteristics and saturation, using an image analysis method. These field-observations with depth were compared with results from a one-dimensional two-phase flow model simulation for the same transect. Considering the limitations of this approach, simulations reasonably reflected the variability and range of the mercury DNAPL distribution. To further explore the impact of mercury's physical properties in comparison with more common DNAPLs, the migration of mercury and PCE DNAPL in several typical hydrological scenarios was simulated. Comparison of the simulations suggest that mercury's higher density is the overall controlling factor in controlling its penetration in saturated porous media, despite its higher resistance to flow due to its higher viscosity. Based on these results the hazard of spilled mercury DNAPL to cause deep contamination of groundwater systems seems larger than for any other

  19. Electrostatic ion thrusters - towards predictive modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kalentev, O.; Matyash, K.; Duras, J.; Lueskow, K.F.; Schneider, R. [Ernst-Moritz-Arndt Universitaet Greifswald, D-17489 (Germany); Koch, N. [Technische Hochschule Nuernberg Georg Simon Ohm, Kesslerplatz 12, D-90489 Nuernberg (Germany); Schirra, M. [Thales Electronic Systems GmbH, Soeflinger Strasse 100, D-89077 Ulm (Germany)

    2014-02-15

    The development of electrostatic ion thrusters so far has mainly been based on empirical and qualitative know-how, and on evolutionary iteration steps. This resulted in considerable effort regarding prototype design, construction and testing and therefore in significant development and qualification costs and high time demands. For future developments it is anticipated to implement simulation tools which allow for quantitative prediction of ion thruster performance, long-term behavior and space craft interaction prior to hardware design and construction. Based on integrated numerical models combining self-consistent kinetic plasma models with plasma-wall interaction modules a new quality in the description of electrostatic thrusters can be reached. These open the perspective for predictive modeling in this field. This paper reviews the application of a set of predictive numerical modeling tools on an ion thruster model of the HEMP-T (High Efficiency Multi-stage Plasma Thruster) type patented by Thales Electron Devices GmbH. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Effects of 1,2,4-Trichlorobenzene and Mercury Ion Stress on Ca2+ Fluxion and Protein Phosphorylation in Rice

    Directory of Open Access Journals (Sweden)

    Cai-lin GE

    2007-12-01

    Full Text Available The effects of 5 mg/L 1,2,4-trichlorobenzene (TCB and 0.1 mmol/L mercury ion (Hg2+ stresses on Ca2+ fluxion and protein phosphorylation in rice seedlings were investigated by isotope exchange kinetics and in vitro phosphorylation assay. The Ca2+ absorption in rice leaves and Ca2+ transportation from roots to leaves were promoted significantly in response to Hg2+ and TCB treatments for 4-48 h. The Ca2+ absorption peaks presented in the leaves when the rice seedlings were exposed to Hg2+ for 8-12 h or to TCB for 12-24 h. Several Ca2+ absorption peaks presented in the roots during rice seedlings being exposed to Hg2+ and TCB, and the first Ca2+ absorption peak was at 8 h after being exposed to Hg2+ and TCB. The result of isotope exchange kinetic analysis confirmed that short-term (8 h Hg2+ and TCB stresses caused Ca2+ channels or pumps located on plasmalemma to open transiently. The phosphorylation assay showed that short-term TCB stress enhanced protein phosphorylation in rice roots (TCB treatment for 4-8 h and leaves (TCB treatment for 4-24 h, and short-term (4-8 h Hg2+ stress also enhanced protein phosphorylation in rice leaves. The enhancement of protein phosphorylation in both roots and leaves corresponded with the first Ca2+ absorption peak, which confirmed that the enhancement of protein phosphorylation caused by TCB or Hg2+ stress might be partly triggered by the increases of cytosolic calcium. TCB treatment over 12 h inhibited protein phosphorylation in rice roots, which might be partly due to that TCB stress suppressed the protein kinase activity. Whereas, Hg2+ treatment inhibited protein phosphorylation in rice roots, and Hg2+ treatment over 12 h inhibited protein phosphorylation in rice leaves. This might be attributed to that not only the protein kinase activity, but also the expressions of phosphorylation proteins were restrained by Hg2+ stress.

  1. Effects of 1,2,4-Trichlorobenzene and Mercury Ion Stress on Ca2+ Fluxion and Protein Phosphorylation in Rice

    Institute of Scientific and Technical Information of China (English)

    GE Cai-lin; WANG Ze-gang; WAN Ding-zhen; DING Yan; WANG Yu-long; SHANG Qi; LUO Shi-shi; MA Fei

    2007-01-01

    The effects of 5 mg/L 1,2,4-trichlorobenzene (TCB) and 0.1 mmol/L mercury ion (Hg2+) stresses on Ca2+ fluxion and protein phosphorylation in rice seedlings were investigated by isotope exchange kinetics and in vitro phosphorylation assay. The Ca2+ absorption in rice leaves and Ca2+ transportation from roots to leaves were promoted significantly in response to Hg2+ and TCB treatments for 4-48 h. The Ca2+ absorption peaks presented in the leaves when the rice seedlings were exposed to Hg2+ for 8-12 h or to TCB for 12-24 h. Several Ca2+ absorption peaks presented in the roots during rice seedlings being exposed to Hg2+ and TCB, and the first Ca2+ absorption peak was at 8 h after being exposed to Hg2+ and TCB.The result of isotope exchange kinetic analysis confirmed that short-term (8 h) Hg2+ and TCB stresses caused Ca2+ channels or pumps located on plasmalemma to open transiently. The phosphorylation assay showed that short-term TCB stress enhanced protein phosphorylation in rice roots (TCB treatment for 4-8 h) and leaves (TCB treatment for 4-24 h), and short-term (4-8 h) Hg2+ stress also enhanced protein phosphorylation in rice leaves. The enhancement of protein phosphorylation in both roots and leaves corresponded with the first Ca2+ absorption peak, which confirmed that the enhancement of protein phosphorylation caused by TCB or Hg2+ stress might be partly triggered by the increases of cytosolic calcium. TCB treatment over 12 h inhibited protein phosphorylation in rice roots, which might be partly due to that TCB stress suppressed the protein kinase activity. Whereas, Hg2+ treatment inhibited protein phosphorylation in rice roots, and Hg2+treatment over 12 h inhibited protein phosphorylation in rice leaves. This might be attributed to that not only the protein kinase activity, but also the expressions of phosphorylation proteins were restrained by Hg2+ stress.

  2. Space Environment of Mercury at the Time of the First MESSENGER Flyby: Solar Wind and Interplanetary Magnetic Field Modeling of Upstream Conditions

    Science.gov (United States)

    2009-10-01

    passed over the planet (and MESSENGER) several days prior to the flyby of Mercury with the highest-speed (600 km/s) stream features having been expected...when MESSENGER is in orbit around Mercury , the spacecraft will be within the magnetosphere and magnetotail of the planet for extended portions of...TITLE AND SUBTITLE Space environment of Mercury at the time of the first 3HESSENGER flyby: Solar wind and interplanetary magnetic field •Modeling

  3. The role of chitosan as nanofiller of graphite oxide for the removal of toxic mercury ions.

    Science.gov (United States)

    Kyzas, George Z; Travlou, Nikolina A; Deliyanni, Eleni A

    2014-01-01

    The present study focuses on the role of chitosan (CS) as nanofiller of graphite oxide (GO) in order to prepare composite materials with improved Hg(II) adsorption properties. The removal of Hg(II) from aqueous solutions was studied using adsorbents as graphite oxide (GO), graphite oxide nanofilled with chitosan (GO/CS) and magnetic chitosan (GO/mCS). Many possible interactions between materials and Hg(II) were observed after adsorption and explained via characterization with various techniques (SEM/EDAX, FTIR, XRD, DTG). The adsorption evaluation was done studying various parameters as the effect of pH (both in adsorption and desorption), contact time (pseudo-second order fitting), temperature (isotherms at 25, 45, 65 °C), in line with a brief thermodynamic analysis (ΔG(0), ΔH(0), ΔS(0)). The maximum adsorption capacity (fitting with Langmuir model) of GO at 25 °C was Qmax=187 mg/g, while after the CS nanofilling (formation of the composite GO/CS), Qmax was increased to 381 mg/g with a further enhancement for GO/mCS (Qmax=397 mg/g). Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Dynamical Properties of Potassium Ion Channels with a Hierarchical Model

    Institute of Scientific and Technical Information of China (English)

    ZHAN Yong; AN Hai-Long; YU Hui; ZHANG Su-Hua; HAN Ying-Rong

    2006-01-01

    @@ It is well known that potassium ion channels have higher permeability than K ions, and the permeable rate of a single K ion channel is about 108 ions per second. We develop a hierarchical model of potassium ion channel permeation involving ab initio quantum calculations and Brownian dynamics simulations, which can consistently explain a range of channel dynamics. The results show that the average velocity of K ions, the mean permeable time of K ions and the permeable rate of single channel are about 0.92nm/ns, 4.35ns and 2.30×108 ions/s,respectively.

  5. Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids

    Directory of Open Access Journals (Sweden)

    Jesse O. Bash

    2013-12-01

    Full Text Available In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+. However, most atmospheric chemistry models use a parameterization of the aqueous-phase reduction of Hg2+ that has been shown to be unlikely under normal ambient conditions or use a non mechanistic value derived to optimize wet deposition results. Recent laboratory experiments have shown that Hg2+ can be photochemically reduced to elemental mercury (Hg in the aqueous-phase by dissolved organic matter and a mechanism and the rate for Hg2+ photochemical reduction by dicarboxylic acids (DCA has been proposed. For the first time in a regional scale model, the DCA mechanism has been applied. The HO2-Hg2+ reduction mechanism, the proposed DCA reduction mechanism, and no aqueous-phase reduction (NAR of Hg2+ are evaluated against weekly wet deposition totals, concentrations and precipitation observations from the Mercury Deposition Network (MDN using the Community Multiscale Air Quality (CMAQ model version 4.7.1. Regional scale simulations of mercury wet deposition using a DCA reduction mechanism evaluated well against observations, and reduced the bias in model evaluation by at least 13% over the other schemes evaluated, although summertime deposition estimates were still biased by −31.4% against observations. The use of the DCA reduction mechanism physically links Hg2+ reduction to plausible atmospheric processes relevant under typical ambient conditions.

  6. Mercury speciation modeling using site specific chemical and redox data from the TNXOD OU

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, D.I.

    2000-03-22

    The objective of this study was to evaluate mercury speciation under reducing conditions expected in sediments at the TNX Outfall Delta Operable Unit. These changes in speciation would then be used to infer whether mercury toxicity and mobility would be expected to be significantly altered under reducing conditions. The results from this work suggest that mercury would likely become more strongly retained by the solid phase under reducing conditions than under oxidizing conditions at the TNX Outfall Delta Site. Considering that experimental results indicate that mercury is extremely tightly bound to the solid phase under oxidizing conditions, little mercury mobility would therefore be expected under reducing conditions.

  7. Developing Depositional Models for Mercury Contaminated Floodplain Deposits Using Geomorphic Mapping and GIS in South River, Virginia

    Science.gov (United States)

    Barbieri, A.; Pizzuto, J.; O'Neal, M. A.; Rhoades, E.

    2007-12-01

    Mercury was introduced into the South River from the 1930s to the 1950s from an industrial plant in Waynesboro, Virginia. Mercury contamination in fish tissue continues to exceed acceptable levels. The contaminated sediments in the river's floodplains are probably the present source of mercury to the South River ecosystem. Locating and determining the extent and depositional history of these deposits are important for understanding the mercury cycle in the river as well as for remediation plans. The South River is a sinuous, single thread alluvial river with frequent bedrock exposures along its bed and banks. Overbank deposits are discontinuous and thin. Rates of lateral migration by the South River are extremely low, averaging 0.02 m/yr, and the river has been influenced by mill dams along a 19 km study reach. This 19 km section of the 37 km river reach was selected for the study because of its high concentration of Hg. Six different categories of floodplain deposits dating from 1937-2005 have been identified throughout the river using studies of historical aerial photographs in a GIS framework, field mapping, dendro- and radionuclide dating, grain size and Hg analysis. Not surprisingly, traditional depositional models of meandering rivers do not apply. Floodplain depositional units include mill dam deposits, point bar/bench deposits, concave bank bench deposits, islands, cattle deposits, and tributary confluences deposits. The most important deposits for sequestering historic mercury are those that also store the most silt and clay. These include mill dam deposits, point bar/bench deposits, concave bank deposits, and tributary confluence deposits. Many of these deposits represent reservoirs of mercury-contaminated sediments that could supply significant amounts of mercury into the river presently and in the future.

  8. Modeling and Optimizing RF Multipole Ion Traps

    Science.gov (United States)

    Fanghaenel, Sven; Asvany, Oskar; Schlemmer, Stephan

    2016-06-01

    Radio frequency (rf) ion traps are very well suited for spectroscopy experiments thanks to the long time storage of the species of interest in a well defined volume. The electrical potential of the ion trap is determined by the geometry of its electrodes and the applied voltages. In order to understand the behavior of trapped ions in realistic multipole traps it is necessary to characterize these trapping potentials. Commercial programs like SIMION or COMSOL, employing the finite difference and/or finite element method, are often used to model the electrical fields of the trap in order to design traps for various purposes, e.g. introducing light from a laser into the trap volume. For a controlled trapping of ions, e.g. for low temperature trapping, the time dependent electrical fields need to be known to high accuracy especially at the minimum of the effective (mechanical) potential. The commercial programs are not optimized for these applications and suffer from a number of limitations. Therefore, in our approach the boundary element method (BEM) has been employed in home-built programs to generate numerical solutions of real trap geometries, e.g. from CAD drawings. In addition the resulting fields are described by appropriate multipole expansions. As a consequence, the quality of a trap can be characterized by a small set of multipole parameters which are used to optimize the trap design. In this presentation a few example calculations will be discussed. In particular the accuracy of the method and the benefits of describing the trapping potentials via multipole expansions will be illustrated. As one important application heating effects of cold ions arising from non-ideal multipole fields can now be understood as a consequence of imperfect field configurations.

  9. Development of a mercury speciation, fate, and biotic uptake (BIOTRANSPEC) model: Application to Lahontan Reservoir (Nevada, USA)

    Science.gov (United States)

    Gandhi, N.; Bhavsar, S.P.; Diamond, M.L.; Kuwabara, J.S.; Marvin-DiPasquale, M.; Krabbenhoft, D.P.

    2007-01-01

    A mathematically linked mercury transport, speciation, kinetic, and simple biotic uptake (BIOTRANSPEC) model has been developed. An extension of the metal transport and speciation (TRANSPEC) model, BIOTRANSPEC estimates the fate and biotic uptake of inorganic (Hg(II)), elemental (Hg(0)) and organic (MeHg) forms of mercury and their species in the dissolved, colloidal (e.g., dissolved organic matter [DOM]), and particulate phases of surface aquatic systems. A pseudo-steady state version of the model was used to describe mercury dynamics in Lahontan Reservoir (near Carson City, NV, USA), where internal loading of the historically deposited mercury is remobilized, thereby maintaining elevated water concentrations. The Carson River is the main source of total mercury (THg), of which more than 90% is tightly bound in a gold-silver-mercury amalgam, to the system through loadings in the spring, with negligible input from the atmospheric deposition. The speciation results suggest that aqueous species are dominated by Hg-DOM, Hg(OH)2, and HgClOH. Sediment-to-water diffusion of MeHg and Hg-DOM accounts for approximately 10% of total loadings to the water column. The water column acts as a net sink for MeHg by reducing its levels through two competitive processes: Uptake by fish, and net MeHg demethylation. Although reservoir sediments produce significant amounts of MeHg (4 g/d), its transport from sediment to water is limited (1.6 g/d), possibly because of its adsorption on metal oxides of iron and manganese at the sediment-water interface. Fish accumulate approximately 45% of the total MeHg mass in the water column, and 9% of total MeHg uptake by fish leaves the system because of fishing. Results from this new model reiterate the previous conclusion that more than 90% of THg input is retained in sediment, which perpetuates elevated water concentrations. ?? 2007 SETAC.

  10. Track structure modelling for ion radiotherapy

    CERN Document Server

    Korcyl, Marta

    2014-01-01

    In its broadest terms, doctoral dissertation entitled "Track structure modelling for ion radiotherapy" is part of the supporting research background in the development of the ambitious proton radiotherapy project currently under way at the Institute of Nuclear Physics PAN in Krak\\'ow. Another broad motivation was the desire to become directly involved in research on a topical and challenging subject of possibly developing a therapy planning system for carbon beam radiotherapy, based in its radiobiological part on the Track Structure model developed by prof. Robert Katz over 50 years ago. Thus, the general aim of this work was, firstly, to recapitulate the Track Structure model and to propose an updated and complete formulation of this model by incorporating advances made by several authors who had contributed to its development in the past. Secondly, the updated and amended (if necessary) formulation of the model was presented in a form applicable for use in computer codes which would constitute the "radiobio...

  11. Air-snowpack exchange of bromine, ozone and mercury in the springtime Arctic simulated by the 1-D model PHANTAS - Part 2: Mercury and its speciation

    Science.gov (United States)

    Toyota, K.; Dastoor, A. P.; Ryzhkov, A.

    2014-04-01

    Atmospheric mercury depletion events (AMDEs) refer to a recurring depletion of mercury occurring in the springtime Arctic (and Antarctic) boundary layer, in general, concurrently with ozone depletion events (ODEs). To close some of the knowledge gaps in the physical and chemical mechanisms of AMDEs and ODEs, we have developed a one-dimensional model that simulates multiphase chemistry and transport of trace constituents throughout porous snowpack and in the overlying atmospheric boundary layer (ABL). This paper constitutes Part 2 of the study, describing the mercury component of the model and its application to the simulation of AMDEs. Building on model components reported in Part 1 ("In-snow bromine activation and its impact on ozone"), we have developed a chemical mechanism for the redox reactions of mercury in the gas and aqueous phases with temperature dependent reaction rates and equilibrium constants accounted for wherever possible. Thus the model allows us to study the chemical and physical processes taking place during ODEs and AMDEs within a single framework where two-way interactions between the snowpack and the atmosphere are simulated in a detailed, process-oriented manner. Model runs are conducted for meteorological and chemical conditions that represent the springtime Arctic ABL characterized by the presence of "haze" (sulfate aerosols) and the saline snowpack on sea ice. The oxidation of gaseous elemental mercury (GEM) is initiated via reaction with Br-atom to form HgBr, followed by competitions between its thermal decomposition and further reactions to give thermally stable Hg(II) products. To shed light on uncertain kinetics and mechanisms of this multi-step oxidation process, we have tested different combinations of their rate constants based on published laboratory and quantum mechanical studies. For some combinations of the rate constants, the model simulates roughly linear relationships between the gaseous mercury and ozone concentrations as

  12. Air-snowpack exchange of bromine, ozone and mercury in the springtime Arctic simulated by the 1-D model PHANTAS – Part 2: Mercury and its speciation

    Directory of Open Access Journals (Sweden)

    K. Toyota

    2013-08-01

    Full Text Available Atmospheric mercury depletion events (AMDEs refer to a recurring depletion of mercury in the springtime Arctic (and Antarctic boundary layer, occurring, in general, concurrently with ozone depletion events (ODEs. To close some of the knowledge gaps in the physical and chemical mechanisms of AMDEs and ODEs, we have developed a one-dimensional model that simulates multiphase chemistry and transport of trace constituents throughout porous snowpack and in the overlying atmospheric boundary layer (ABL. Building on the model reported in a companion paper (Part 1: In-snow bromine activation and its impact on ozone, we have expanded the chemical mechanism to include the reactions of mercury in the gas- and aqueous-phases with temperature dependence of rate and equilibrium constants accounted for wherever possible. Thus the model allows us to study the chemical and physical processes taking place during ODEs and AMDEs within a single framework where two-way interactions between the snowpack and the atmosphere are simulated in a detailed, process-oriented manner. Model runs are conducted for meteorological and chemical conditions representing the springtime Arctic ABL loaded with "haze" sulfate aerosols and the underlying saline snowpack laid on sea ice. Using recent updates for the Hg + Br ⇄ HgBr reaction kinetics, we show that the rate and magnitude of photochemical loss of gaseous elemental mercury (GEM during AMDEs exhibit a strong dependence on the choice of reaction(s of HgBr subsequent to its formation. At 253 K, the temperature that is presumably low enough for bromine radical chemistry to cause prominent AMDEs as indicated from field observations, the parallel occurrence of AMDEs and ODEs is simulated if the reaction HgBr + BrO is assumed to produce a thermally stable intermediate, Hg(OBrBr, at the same rate constant as the reaction HgBr + Br. On the contrary, the simulated depletion of atmospheric mercury is notably diminished by

  13. GNAQPMS-Hg v1.0, a global nested atmospheric mercury transport model: model description, evaluation and application to trans-boundary transport of Chinese anthropogenic emissions

    Directory of Open Access Journals (Sweden)

    H. S. Chen

    2014-10-01

    Full Text Available Atmospheric mercury (Hg is a toxic pollutant and can be transported over the whole globe due to its long lifetime in the atmosphere. For the purpose of assessing Hg hemispheric transport and better characterizing regional Hg pollution, a global nested atmospheric Hg transport model (GNAQPMS-Hg has been developed. In GNAQPMS-Hg, the gas and aqueous phase Hg chemistry representing the transformation among three forms of Hg: elemental mercury (Hg(0, divalent mercury (Hg(II, and primary particulate mercury (Hg(P are calculated. A detailed description of the model, including mercury emissions, gas and aqueous phase chemistry, and dry and wet deposition is given in this study. Worldwide observations including extensive data in China have been collected for model evaluation. Comparison results show that the model reasonably simulates the global mercury budget and the spatial–temporal variation of surface mercury concentrations and deposition. Overall, model predictions of annual total gaseous mercury (TGM and wet deposition agree with observations within a factor of two, and within a factor of five for oxidized mercury and dry deposition. The model performs significantly better in North America and Europe than in East Asia. This can probably be attributed to the large uncertainties in emission inventories, coarse model resolution and to the inconsistency between the simulation and observation periods in East Asia. Compared to the global simulation, the nested simulation shows improved skill at capturing the high spatial variability of Hg concentrations and deposition over East Asia. In particular, the root mean square error (RMSE of simulated Hg wet deposition over East Asia is reduced by 24% in the nested simulation. Model sensitivity studies indicate that Chinese primary anthropogenic emissions account for 30 and 62% of surface mercury concentrations and deposition over China, respectively. Along the rim of the western Pacific, the contributions

  14. High-yield synthesis of strong photoluminescent N-doped carbon nanodots derived from hydrosoluble chitosan for mercury ion sensing via smartphone APP.

    Science.gov (United States)

    Wang, Lei; Li, Baoqiang; Xu, Feng; Shi, Xinyao; Feng, Demeng; Wei, Daqing; Li, Ying; Feng, Yujie; Wang, Yaming; Jia, Dechang; Zhou, Yu

    2016-05-15

    Photoluminescent carbon nanodots (CNDs) have offered considerable potential to be used in biomedical and environmental fields including live cell imaging and heavy metal ion detection due to their superior quantum emission efficiencies, ability to be functionalized using a variety of chemistries and apparent absence of toxicity. However, to date, synthetic yield of CNDs derived from biomass via hydrothermal carbonization is quite low. We report here the synthesis of nitrogen-doped carbon nanodots (N-doped CNDs) derived from hydrosoluble chitosan via hydrothermal carbonization. The synthetic yield could reach 38.4% which is 2.2-320 times increase compared with that from other biomass reported so far. These N-doped CNDs exhibited a high quantum yield (31.8%) as a consequence of nitrogen incorporation coincident with multiple types of functional groups (C=O, O-H, COOH, and NH2). We further demonstrate applications of N-doped CNDs as probes for live cell multicolor imaging and heavy metal ion detection. The N-doped CNDs offered potential as mercury ion sensors with detection limit of 80nM. A smartphone application (APP) based on N-doped CNDs was developed for the first time providing a portable and low cost detection platform for detection of Hg(2+) and alert of heavy metal ions contamination. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Modelling the Dynamic Interaction Power System Lamp - Application to High Pressure Mercury Gas Discharge Lamps

    Directory of Open Access Journals (Sweden)

    ZIANE, M.

    2007-11-01

    Full Text Available The aim of this paper is to study the dynamic behaviour of a plant constituted by an electrical power system and a gas discharge lamp, this latter, increasingly used in street lighting, remains a nonlinear load element. Various approaches are used to represent it, one is the approximation of the discharge represented by a hot "channel", which verifies the assumption of local thermodynamic equilibrium [LTE] or the polynomial form of the conductance variation. A calculation procedure, based on "channel" approximation of the high pressure mercury (HPM gas-discharge lamp, is developed to determine the physical and electric magnitudes, which characterize the dynamic behavior of the couple "lamp-electrical power system". The evolution of the lamp properties when principal parameters of the discharge (pressure of mercury, voltage supply, frequency are varying were studied and analyzed. We show the concordance between simulation, calculations and measurements for electric, energetic or irradiative characteristics. The model reproduces well the evolution of properties of the supply when principal parameters of the discharge vary.

  16. Mercury and Your Health

    Science.gov (United States)

    ... the Risk of Exposure to Mercury Learn About Mercury What is Mercury What is Metallic mercury? Toxicological Profile ToxFAQs Mercury Resources CDC’s National Biomonitoring Program Factsheet on Mercury ...

  17. Characterizing mercury concentrations and fluxes in a Coastal Plain watershed: Insights from dynamic modeling and data

    Science.gov (United States)

    Golden, H.E.; Knightes, C.D.; Conrads, P.A.; Davis, G.M.; Feaster, T.D.; Journey, C.A.; Benedict, S.T.; Brigham, M.E.; Bradley, P.M.

    2012-01-01

    Mercury (Hg) is one of the leading water quality concerns in surface waters of the United States. Although watershed-scale Hg cycling research has increased in the past two decades, advances in modeling watershed Hg processes in diverse physiographic regions, spatial scales, and land cover types are needed. The goal of this study was to assess Hg cycling in a Coastal Plain system using concentrations and fluxes estimated by multiple watershed-scale models with distinct mathematical frameworks reflecting different system dynamics. We simulated total mercury (HgT, the sum of filtered and particulate forms) concentrations and fluxes from a Coastal Plain watershed (McTier Creek) using three watershed Hg models and an empirical load model. Model output was compared with observed in-stream HgT. We found that shallow subsurface flow is a potentially important transport mechanism of particulate HgT during periods when connectivity between the uplands and surface waters is maximized. Other processes (e.g., stream bank erosion, sediment re-suspension) may increase particulate HgT in the water column. Simulations and data suggest that variable source area (VSA) flow and lack of rainfall interactions with surface soil horizons result in increased dissolved HgT concentrations unrelated to DOC mobilization following precipitation events. Although flushing of DOC-HgT complexes from surface soils can also occur during this period, DOC-complexed HgT becomes more important during base flow conditions. TOPLOAD simulations highlight saturated subsurface flow as a primary driver of daily HgT loadings, but shallow subsurface flow is important for HgT loads during high-flow events. Results suggest limited seasonal trends in HgT dynamics.

  18. Mercury's geochronology revised by applying Model Production Functions to Mariner 10 data: geological implications

    CERN Document Server

    Massironi, M; Marchi, S; Martellato, M; Mottola, M; Wagner, R J

    2009-01-01

    Model Production Function chronology uses dynamic models of the Main Belt Asteroids (MBAs) and Near Earth Objects (NEOs) to derive the impactor flux to a target body. This is converted into the crater size-frequency-distribution for a specific planetary surface, and calibrated using the radiometric ages of different regions of the Moon's surface. This new approach has been applied to the crater counts on Mariner 10 images of the highlands and of several large impact basins on Mercury. MPF estimates for the plains show younger ages than those of previous chronologies. Assuming a variable uppermost layering of the Hermean crust, the age of the Caloris interior plains may be as young as 3.59 Ga, in agreement with MESSENGER results that imply that long-term volcanism overcame contractional tectonics. The MPF chronology also suggests a variable projectile flux through time, coherent with the MBAs for ancient periods and then gradually comparable also to the NEOs.

  19. Computing maximum-likelihood estimates for parameters of the National Descriptive Model of Mercury in Fish

    Science.gov (United States)

    Donato, David I.

    2012-01-01

    This report presents the mathematical expressions and the computational techniques required to compute maximum-likelihood estimates for the parameters of the National Descriptive Model of Mercury in Fish (NDMMF), a statistical model used to predict the concentration of methylmercury in fish tissue. The expressions and techniques reported here were prepared to support the development of custom software capable of computing NDMMF parameter estimates more quickly and using less computer memory than is currently possible with available general-purpose statistical software. Computation of maximum-likelihood estimates for the NDMMF by numerical solution of a system of simultaneous equations through repeated Newton-Raphson iterations is described. This report explains the derivation of the mathematical expressions required for computational parameter estimation in sufficient detail to facilitate future derivations for any revised versions of the NDMMF that may be developed.

  20. Quantum-Mechanical QSPR Models for Polymerization Volume Change of Epoxides and Methacrylates Based on Mercury Dilatometry Results

    OpenAIRE

    Miller, Matthew D.; Holder, Andrew J.; Kilway, Kathleen V.; Giese, Gregory J.; Finley, Jason E.; Travis, DeAnna M.; Iwai, Benjamin T.; Eick, J. David

    2006-01-01

    Polymerization volume change (PVC) was measured systematically using mercury dilatometry for 41 epoxide and methacrylate monomers with quartz filler. Quantitative structure property relationship (QSPR) models were developed based on this previously unreported data to gain insight in the data collection method for future models. Successful models included only data from those samples which polymerized to hardness. The most significant descriptors in these models related to monomer reactivity. ...

  1. Computational modeling of Li-ion batteries

    Science.gov (United States)

    Grazioli, D.; Magri, M.; Salvadori, A.

    2016-08-01

    This review focuses on energy storage materials modeling, with particular emphasis on Li-ion batteries. Theoretical and computational analyses not only provide a better understanding of the intimate behavior of actual batteries under operational and extreme conditions, but they may tailor new materials and shape new architectures in a complementary way to experimental approaches. Modeling can therefore play a very valuable role in the design and lifetime prediction of energy storage materials and devices. Batteries are inherently multi-scale, in space and time. The macro-structural characteristic lengths (the thickness of a single cell, for instance) are order of magnitudes larger than the particles that form the microstructure of the porous electrodes, which in turn are scale-separated from interface layers at which atomistic intercalations occur. Multi-physics modeling concepts, methodologies, and simulations at different scales, as well as scale transition strategies proposed in the recent literature are here revised. Finally, computational challenges toward the next generation of Li-ion batteries are discussed.

  2. Computational modeling of Li-ion batteries

    Science.gov (United States)

    Grazioli, D.; Magri, M.; Salvadori, A.

    2016-12-01

    This review focuses on energy storage materials modeling, with particular emphasis on Li-ion batteries. Theoretical and computational analyses not only provide a better understanding of the intimate behavior of actual batteries under operational and extreme conditions, but they may tailor new materials and shape new architectures in a complementary way to experimental approaches. Modeling can therefore play a very valuable role in the design and lifetime prediction of energy storage materials and devices. Batteries are inherently multi-scale, in space and time. The macro-structural characteristic lengths (the thickness of a single cell, for instance) are order of magnitudes larger than the particles that form the microstructure of the porous electrodes, which in turn are scale-separated from interface layers at which atomistic intercalations occur. Multi-physics modeling concepts, methodologies, and simulations at different scales, as well as scale transition strategies proposed in the recent literature are here revised. Finally, computational challenges toward the next generation of Li-ion batteries are discussed.

  3. Simultaneous Automatic Electrochemical Detection of Zinc, Cadmium, Copper and Lead Ions in Environmental Samples Using a Thin-Film Mercury Electrode and an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Jiri Kudr

    2014-12-01

    Full Text Available In this study a device for automatic electrochemical analysis was designed. A three electrodes detection system was attached to a positioning device, which enabled us to move the electrode system from one well to another of a microtitre plate. Disposable carbon tip electrodes were used for Cd(II, Cu(II and Pb(II ion quantification, while Zn(II did not give signal in this electrode configuration. In order to detect all mentioned heavy metals simultaneously, thin-film mercury electrodes (TFME were fabricated by electrodeposition of mercury on the surface of carbon tips. In comparison with bare electrodes the TMFEs had lower detection limits and better sensitivity. In addition to pure aqueous heavy metal solutions, the assay was also performed on mineralized rock samples, artificial blood plasma samples and samples of chicken embryo organs treated with cadmium. An artificial neural network was created to evaluate the concentrations of the mentioned heavy metals correctly in mixture samples and an excellent fit was observed (R2 = 0.9933.

  4. Atmospheric mercury simulation using the CMAQ model: formulation description and analysis of wet deposition results

    Science.gov (United States)

    Bullock, O. Russell; Brehme, Katherine A.

    The community multiscale air quality (CMAQ) modeling system has been adapted to simulate the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three distinct forms: elemental Hg gas, reactive gaseous Hg, and particulate Hg. Emissions of Hg are currently defined from information published in the Environmental Protection Agency's Mercury Study Report to Congress. The atmospheric transport of these three forms of Hg is simulated in the same manner as for all other substances simulated by the CMAQ model to date. Transformations of Hg are simulated with four new chemical reactions within the standard CMAQ gaseous chemistry framework and a highly modified cloud chemistry mechanism which includes a compound-specific speciation for oxidized forms of Hg, seven new aqueous-phase Hg reactions, six aqueous Hg chemical equilibria, and a two-way mechanism for the sorption of dissolved oxidized Hg to elemental carbon particles. The CMAQ Hg model simulates the partitioning of reactive gaseous Hg between air and cloud water based on the Henry's constant for mercuric chloride. Henry's equilibrium is assumed for elemental Hg also. Particulate Hg is assumed to be incorporated into the aqueous medium during cloud nucleation. Wet and dry deposition is simulated for each of the three forms of Hg. Wet deposition rate is calculated based on precipitation information from the CMAQ meteorological processor and the physicochemical Hg speciation in the cloud chemistry mechanism. Dry deposition rate is calculated based on dry deposition velocity and air concentration information for each of the three forms of Hg. The horizontal modeling domain covers the central and eastern United States and adjacent southern Canada. An analysis of simulated Hg wet deposition versus weekly observations is performed. The results are described for two evaluation periods: 4 April-2 May 1995, and 20 June-18 July 1995.

  5. [Mercury poisoning].

    Science.gov (United States)

    Bensefa-Colas, L; Andujar, P; Descatha, A

    2011-07-01

    Mercury is a widespread heavy metal with potential severe impacts on human health. Exposure conditions to mercury and profile of toxicity among humans depend on the chemical forms of the mercury: elemental or metallic mercury, inorganic or organic mercury compounds. This article aims to reviewing and synthesizing the main knowledge of the mercury toxicity and its organic compounds that clinicians should know. Acute inhalation of metallic or inorganic mercury vapours mainly induces pulmonary diseases, whereas chronic inhalation rather induces neurological or renal disorders (encephalopathy and interstitial or glomerular nephritis). Methylmercury poisonings from intoxicated food occurred among some populations resulting in neurological disorders and developmental troubles for children exposed in utero. Treatment using chelating agents is recommended in case of symptomatic acute mercury intoxication; sometimes it improves the clinical effects of chronic mercury poisoning. Although it is currently rare to encounter situations of severe intoxication, efforts remain necessary to decrease the mercury concentration in the environment and to reduce risk on human health due to low level exposure (dental amalgam, fish contamination by organic mercury compounds…). In case of occupational exposure to mercury and its compounds, some disorders could be compensated in France. Clinicians should work with toxicologists for the diagnosis and treatment of mercury intoxication.

  6. Basic Information about Mercury

    Science.gov (United States)

    ... other organic compounds, elemental (metallic) mercury, and inorganic mercury compounds. Methylmercury and other organic mercury compounds are formed when mercury combines with carbon. Microscopic ...

  7. Mercury: A Synthesis from MESSENGER's Extended Mission

    Science.gov (United States)

    Solomon, S. C.; Nittler, L. R.; McNutt, R. L.

    2012-12-01

    Launched in 2004, MESSENGER flew by Mercury three times in 2008-2009 en route to becoming the first spacecraft to orbit the solar system's innermost planet in March 2011. Orbital observations over the subsequent 21 months have provided the first global view of this nearby but heretofore little studied world. MESSENGER's chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction, low in Fe and high in Mg, differs from those of the other inner planets. Moreover, surface materials are richer in the moderately volatile constituents S and K than predicted by most current models for inner planet formation. Global image mosaics and targeted high-resolution images reveal that Mercury experienced globally extensive volcanism, with large expanses of plains emplaced as flood lavas and widespread examples of pyroclastic deposits likely emplaced during explosive eruptions of volatile-bearing magmas. Bright deposits within impact craters host fresh-appearing, rimless depressions or hollows, often with high-reflectance interiors and halos and likely formed through processes involving the geologically recent loss of volatiles. The large-scale deformational history of Mercury, although dominated by near-global contractional deformation as first seen by Mariner 10, is more complex than first appreciated, with numerous examples of extensional deformation that accompanied impact crater and basin modification. Mercury's magnetic field is dominantly dipolar, but the field is axially symmetric and equatorially asymmetric, a geometry that poses challenges to dynamo models for field generation. The interaction between the solar wind and Mercury's magnetosphere, among the most dynamic in the solar system, serves both to replenish the exosphere and space weather the planet's surface. Plasma ions of planetary origin are seen throughout the sampled volume of Mercury's magnetosphere, with maxima in heavy-ion fluxes in the planet's magnetic

  8. Modeling ion sensing in molecular electronics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Caroline J.; Smeu, Manuel, E-mail: manuel.smeu@northwestern.edu; Ratner, Mark A., E-mail: ratner@northwestern.edu [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (United States)

    2014-02-07

    We examine the ability of molecules to sense ions by measuring the change in molecular conductance in the presence of such charged species. The detection of protons (H{sup +}), alkali metal cations (M{sup +}), calcium ions (Ca{sup 2+}), and hydronium ions (H{sub 3}O{sup +}) is considered. Density functional theory (DFT) is used within the Keldysh non-equilibrium Green's function framework (NEGF) to model electron transport properties of quinolinedithiol (QDT, C{sub 9}H{sub 7}NS{sub 2}), bridging Al electrodes. The geometry of the transport region is relaxed with DFT. The transport properties of the device are modeled with NEGF-DFT to determine if this device can distinguish among the M{sup +} + QDT species containing monovalent cations, where M{sup +} = H{sup +}, Li{sup +}, Na{sup +}, or K{sup +}. Because of the asymmetry of QDT in between the two electrodes, both positive and negative biases are considered. The electron transmission function and conductance properties are simulated for electrode biases in the range from −0.5 V to 0.5 V at increments of 0.1 V. Scattering state analysis is used to determine the molecular orbitals that are the main contributors to the peaks in the transmission function near the Fermi level of the electrodes, and current-voltage relationships are obtained. The results show that QDT can be used as a proton detector by measuring transport through it and can conceivably act as a pH sensor in solutions. In addition, QDT may be able to distinguish among different monovalent species. This work suggests an approach to design modern molecular electronic conductance sensors with high sensitivity and specificity using well-established quantum chemistry.

  9. Planet Mercury

    Science.gov (United States)

    1974-01-01

    Mariner 10's first image of Mercury acquired on March 24, 1974. During its flight, Mariner 10's trajectory brought it behind the lighted hemisphere of Mercury, where this image was taken, in order to acquire important measurements with other instruments.This picture was acquired from a distance of 3,340,000 miles (5,380,000 km) from the surface of Mercury. The diameter of Mercury (3,031 miles; 4,878 km) is about 1/3 that of Earth.Images of Mercury were acquired in two steps, an inbound leg (images acquired before passing into Mercury's shadow) and an outbound leg (after exiting from Mercury's shadow). More than 2300 useful images of Mercury were taken, both moderate resolution (3-20 km/pixel) color and high resolution (better than 1 km/pixel) black and white coverage.

  10. Estimation of gaseous mercury emissions in Germany. Inverse modelling of source strengths at the contaminated industrial site BSL Werk Schkopau

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, O.; Ebinghaus, R.; Kock, H.H.; Richter-Politz, I.; Geilhufe, C.

    1998-12-31

    Anthropogenic emission sources of gaseous mercury at the contaminated industrial site BSL Werk Schkopau have been determined by measurements and numerical modelling applying a local dispersion model. The investigations are based on measurements from several field campaigns in the period of time between December 1993 and June 1994. The estimation of the source strengths was performed by inverse modelling using measurements as constraints for the dispersion model. Model experiments confirmed the applicability of the inverse modelling procedure for the source strength estimation at BSL Werk Schkopau. At the factory premises investigated, the source strengths of four source areas, among them three closed chlor-alkali productions, one partly removed acetaldehyde factory and additionaly one still producing chlor-alkali factory have been identified with an approximate total gaseous mercury emission of lower than 2.5 kg/day. (orig.)

  11. A highly selective and simple fluorescent sensor for mercury (II) ion detection based on cysteamine-capped CdTe quantum dots synthesized by the reflux method.

    Science.gov (United States)

    Ding, Xiaojie; Qu, Lingbo; Yang, Ran; Zhou, Yuchen; Li, Jianjun

    2015-06-01

    Cysteamine (CA)-capped CdTe quantum dots (QDs) (CA-CdTe QDs) were prepared by the reflux method and utilized as an efficient nano-sized fluorescent sensor to detect mercury (II) ions (Hg(2+) ). Under optimum conditions, the fluorescence quenching effect of CA-CdTe QDs was linear at Hg(2+) concentrations in the range of 6.0-450 nmol/L. The detection limit was calculated to be 4.0 nmol/L according to the 3σ IUPAC criteria. The influence of 10-fold Pb(2+) , Cu(2+) and Ag(+) on the determination of Hg(2+) was CdTe QDs probe, which was prepared using a one-pot synthetic method. This CA-CdTe QDs sensor system represents a new feasibility to improve the detection performance of a QDs sensor by changing the synthesis method.

  12. Measurement-based modelling of bromine-induced oxidation of mercury above the Dead Sea

    Science.gov (United States)

    Tas, E.; Obrist, D.; Peleg, M.; Matveev, V.; Faïn, X.; Asaf, D.; Luria, M.

    2012-03-01

    Atmospheric mercury depletion events (AMDEs) outside the polar region - driven by high levels of gaseous Br and BrO (i.e., BrOx) - were observed recently in the warm Dead Sea boundary layer. The efficient oxidation of gaseous elemental mercury (GEM) under temperate conditions by BrOx was unexpected considering that the thermal back dissociation reaction of HgBr is about 2.5 orders of magnitude higher under Dead Sea temperatures compared to polar temperatures, and hence was expected to significantly slow down GEM oxidation under warm temperatures. The goal of this modelling study was to improve understanding of the interaction of reactive bromine and mercury during Dead Sea AMDEs using numerical simulations based on a comprehensive measurement campaign in summer 2009. Our analysis is focused on daytime AMDE when chemical processes dominate concentration changes. Best agreements between simulations and observations were achieved using rate constants for kHg+Br and kHg+BrO of 2.7 × 10-13 cm3 molecule-1 s-1 and 1.5 × 10-13 cm3 molecule-1 s-1, respectively. Our model also predicted that a rate constant kHg+BrO of 5.0 × 10-14 cm3 molecule-1 s-1 may be considered as a minimum, which is higher than most reported values. These rate constants suggest that BrO could be a more efficient oxidant than Br in the troposphere as long as [Br]/[BrO] ratios are smaller than ~0.2 to 0.5. Under Dead Sea conditions, these kinetics demonstrate a high efficiency and central role of BrOx for AMDEs, with relative contributions to GEM depletion of more than ~90%. Unexpectedly, BrO was found to be the dominant oxidant with relative contributions above 80%. The strong contribution of BrO could explain why the efficiency of GEM oxidation at the Dead Sea does not critically depend on Br and, therefore, is comparable to that in cold polar regions. In order to confirm the suggested kinetics, additional studies, particularly for temperature-dependence of rate constants, are required.

  13. Measurement-based modelling of bromine-induced oxidation of mercury above the Dead Sea

    Directory of Open Access Journals (Sweden)

    E. Tas

    2012-03-01

    Full Text Available Atmospheric mercury depletion events (AMDEs outside the polar region – driven by high levels of gaseous Br and BrO (i.e., BrOx – were observed recently in the warm Dead Sea boundary layer. The efficient oxidation of gaseous elemental mercury (GEM under temperate conditions by BrOx was unexpected considering that the thermal back dissociation reaction of HgBr is about 2.5 orders of magnitude higher under Dead Sea temperatures compared to polar temperatures, and hence was expected to significantly slow down GEM oxidation under warm temperatures. The goal of this modelling study was to improve understanding of the interaction of reactive bromine and mercury during Dead Sea AMDEs using numerical simulations based on a comprehensive measurement campaign in summer 2009.

    Our analysis is focused on daytime AMDE when chemical processes dominate concentration changes. Best agreements between simulations and observations were achieved using rate constants for kHg+Br and kHg+BrO of 2.7 × 10−13 cm3 molecule−1 s−1 and 1.5 × 10−13 cm3 molecule−1 s−1, respectively. Our model also predicted that a rate constant kHg+BrO of 5.0 × 10−14 cm3 molecule−1 s−1 may be considered as a minimum, which is higher than most reported values. These rate constants suggest that BrO could be a more efficient oxidant than Br in the troposphere as long as [Br]/[BrO] ratios are smaller than ~0.2 to 0.5. Under Dead Sea conditions, these kinetics demonstrate a high efficiency and central role of BrOx for AMDEs, with relative contributions to GEM depletion of more than ~90%. Unexpectedly, BrO was found to be the dominant oxidant with relative contributions above 80%. The strong contribution of BrO could explain why the efficiency of GEM

  14. Mercury(6)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    31. Since Mariner Ten's flight, astronomers have been trying to find out more about Mercury. Telescopes, including the orbiting Hubble Space Telescope,cannot help much. They would be damaged by the bright light of the sun if they turned to look at Mercury. So, astronomers are studying Mercury from observatories on Earth. They are recording information about the planet's radiation.

  15. Na+ Cl- ion pair association in water-DMSO mixtures: Effect of ion pair model potentials

    Indian Academy of Sciences (India)

    ATANU SARKAR; ANUPAM CHATTERJEE; S C TIWARI; B L TEMBE

    2016-06-01

    Potentials of Mean Force (PMF) for the Na+ Cl- ion pair in water–dimethyl sulfoxide (DMSO)mixtures for three DMSO mole fractions have been computed using constrained Molecular Dynamics (MD)simulations and confirmed by dynamical trajectories and residence times of the ion pair at various inter-ionicseparations. The three ion-ion direct potentials used are 12-6-1, exp-6-1 and exp-8-6-1. The physical picturethat emerges is that there is a strong contact ion pair (CIP) and strong to moderate solvent separated ion pair(SSIP) in these solutions. Analysis of local ion clusters shows that ions are dominantly solvated by watermolecules. The 12-6-1 potential model predicts running coordination numbers closest to experimental data.

  16. Mercury Atomic Frequency Standards for Space Based Navigation and Timekeeping

    Science.gov (United States)

    Tjoelker, R. L.; Burt, E. A.; Chung, S.; Hamell, R. L.; Prestage, J. D.; Tucker, B.; Cash, P.; Lutwak, R.

    2012-01-01

    A low power Mercury Atomic Frequency Standard (MAFS) has been developed and demonstrated on the path towards future space clock applications. A self contained mercury ion breadboard clock: emulating flight clock interfaces, steering a USO local oscillator, and consuming approx 40 Watts has been operating at JPL for more than a year. This complete, modular ion clock instrument demonstrates that key GNSS size, weight, and power (SWaP) requirements can be achieved while still maintaining short and long term performance demonstrated in previous ground ion clocks. The MAFS breadboard serves as a flexible platform for optimizing further space clock development and guides engineering model design trades towards fabrication of an ion clock for space flight.

  17. Mercury Atomic Frequency Standards for Space Based Navigation and Timekeeping

    Science.gov (United States)

    Tjoelker, R. L.; Burt, E. A.; Chung, S.; Hamell, R. L.; Prestage, J. D.; Tucker, B.; Cash, P.; Lutwak, R.

    2012-01-01

    A low power Mercury Atomic Frequency Standard (MAFS) has been developed and demonstrated on the path towards future space clock applications. A self contained mercury ion breadboard clock: emulating flight clock interfaces, steering a USO local oscillator, and consuming approx 40 Watts has been operating at JPL for more than a year. This complete, modular ion clock instrument demonstrates that key GNSS size, weight, and power (SWaP) requirements can be achieved while still maintaining short and long term performance demonstrated in previous ground ion clocks. The MAFS breadboard serves as a flexible platform for optimizing further space clock development and guides engineering model design trades towards fabrication of an ion clock for space flight.

  18. Observations and Model Analysis of Enhanced Oxidized Mercury in the Free Troposphere during NOMADSS

    Science.gov (United States)

    Gratz, L.; Shah, V.; Ambrose, J. L., II; Jaffe, D. A.; Jaegle, L.; Selin, N. E.; Song, S.; Festa, J.; Stutz, J.

    2014-12-01

    Mercury (Hg) is a hazardous neurotoxic pollutant with complex atmospheric speciation and chemistry. It exists in the atmosphere primarily as gaseous elemental Hg (GEM), with a lifetime on the order of months, while oxidized Hg is more water soluble and deposits readily. Thus, Hg is considered both a local and a global pollutant. There are significant limitations in our understanding of global Hg cycling, including the sources and chemical mechanisms producing enhanced oxidized Hg in the free troposphere. Ground-based and airborne studies have associated free tropospheric oxidized Hg with GEM oxidation and atmospheric subsidence. Chemical transport models suggest that free tropospheric GEM oxidation is largely attributable to bromine (Br) atoms. During the 2013 Nitrogen Oxidants Mercury and Aerosol Distributions Sources and Sinks (NOMADSS) campaign, we sought to quantify the distribution and chemical transformation of Hg species in the free troposphere over the southeastern US. Enhanced oxidized Hg over North Texas was associated with long-range transport and subsidence from the sub-tropical Pacific free troposphere, where GEOS-Chem predicts air enriched in oxidized Hg. Bromine oxide (BrO) concentrations were also elevated over North Texas, perhaps supporting halogen oxidation as a source of free tropospheric oxidized Hg. Over the Atlantic Ocean, oxidized Hg up to 680 pg m-3 was associated with GEM oxidation and subsidence within the Atlantic high pressure system. The standard GEOS-Chem model underestimates free tropospheric oxidized Hg in these locations by a factor of three to ten, possibly due to underestimation of Br concentrations and/or uncertainty in the Hg+Br rate constant. We investigate GEOS-Chem's improved ability to reproduce the observed concentrations by tripling free tropospheric Br in the tropics and implementing a faster Hg+Br oxidation mechanism. Results have important implications for our understanding of global-scale atmospheric Hg chemistry and

  19. Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons

    Science.gov (United States)

    Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

    2005-01-01

    The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

  20. Spatially-explicit model of mercury accumulation in the forest floor of the United States

    Science.gov (United States)

    Perry, C. H.; Zimmerman, P.

    2009-12-01

    Atmospherically-deposited Hg has a strong affinity for soil organic matter. The Forest Service, US Department of Agriculture, Forest Inventory and Analysis (FIA) program collects soil samples from forested areas across the United States as part of its sampling program, and annual soils inventories are underway or completed in 46 of the 50 states (Alaska, Hawaii, New Mexico, and Oklahoma have yet to be sampled). Our objective is to describe the spatial distribution of forest floor Hg for a transect running across the United States, from Arizona in the southwest to Maine in the northeast. The collection of forest floor samples was accomplished as part of the standard FIA Phase 3 Soil Quality Indicator program. Field protocols include the measurement of the thickness of the forest floor and the collection of the entire forest floor found within a 30-cm diameter sampling frame. We removed approximately 0.1 g of the sample for plots in our region of interest, and these were sent to two different laboratories for Hg analysis by cold-vapor atomic absorption. The two laboratories calibrated their instruments against common Hg standards. We found good agreement between samples analyzed at both laboratories. Observations of mercury concentrations were joined with the Forest Inventory and Analysis Database and other geospatial databases to assign basic location information and associated inventory data. Ecoprovince and forest-type group are significant predictors of Hg storage; conifer species tend to store more mercury than hardwood species. Additionally, models created using spatially-explicit techniques yield distinct patterns of Hg storage that vary across forest-type groups.

  1. Models for Cometary Comae Containing Negative Ions

    Science.gov (United States)

    Cordiner, M. A.; Charnley, S. B.

    2012-01-01

    The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of IP/Halley. The anions O(-), OH(-), C(-), CH(-) and CN(-) have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu [I]. Organic molecular anions such as C4H(-) and C6H(-) are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been fully explored. We present details of our new models for the chemistry of cometary comae that include atomic and molecular anions. We calculate the impact of these anions on the charge balance and examine their importance for cometary coma chemistry.

  2. The Planet Mercury Surface Spectroscopy and Analysis from the Kuiper Airborne Observatory and Analysis and Modeling to Determine Surface Composition

    Science.gov (United States)

    Sprague, Ann

    1997-01-01

    We had two successful flights to observe Mercury from the Kuiper Airborne Observatory (KAO) using High-efficiency Infrared Faint-Object Grating Spectrograph (HIFOGS). Flights were May 8, 1995 (eastern elongation) and July 6, 1995 (western elongation) For the observations one half of the primary mirror was covered to prevent sunlight from entering the telescope. All equipment and the airplane and its crew performed well. These flights were historical firsts for the KAO and for spectroscopy of Mercury in that it was the first time any spectroscopic observations of Mercury from above the Earth's atmosphere had been made. It was the first time the KAO had been used to @bserve an object less than 30 degrees from the Sun. Upon completion of the basic data reduction it became obvious that extensive modeling and analysis would be required to understand the data. It took three years of a graduate student's time and part time the PI to do the thermal modeling and the spectroscopic analysis. This resulted in a lengthy publication. A copy of this publication is attached and has all the data obtained in both KAO flights and the results clearly presented. Notable results are: (1) The observations found an as yet unexplained 5 micron emission enhancement that we think may be a real characteristic of Mercury's surface but could have an instrumental cause; (2) Ground-based measurements or an emission maximum at 7.7 microns were corroborated. The chemical composition of Mercury's surface must be feldspathic in order to explain spectra features found in the data obtained during the KAO flights.

  3. The Planet Mercury Surface Spectroscopy and Analysis from the Kuiper Airborne Observatory and Analysis and Modeling to Determine Surface Composition

    Science.gov (United States)

    Sprague, Ann

    1997-01-01

    We had two successful flights to observe Mercury from the Kuiper Airborne Observatory (KAO) using High-efficiency Infrared Faint-Object Grating Spectrograph (HIFOGS). Flights were May 8, 1995 (eastern elongation) and July 6, 1995 (western elongation) For the observations one half of the primary mirror was covered to prevent sunlight from entering the telescope. All equipment and the airplane and its crew performed well. These flights were historical firsts for the KAO and for spectroscopy of Mercury in that it was the first time any spectroscopic observations of Mercury from above the Earth's atmosphere had been made. It was the first time the KAO had been used to @bserve an object less than 30 degrees from the Sun. Upon completion of the basic data reduction it became obvious that extensive modeling and analysis would be required to understand the data. It took three years of a graduate student's time and part time the PI to do the thermal modeling and the spectroscopic analysis. This resulted in a lengthy publication. A copy of this publication is attached and has all the data obtained in both KAO flights and the results clearly presented. Notable results are: (1) The observations found an as yet unexplained 5 micron emission enhancement that we think may be a real characteristic of Mercury's surface but could have an instrumental cause; (2) Ground-based measurements or an emission maximum at 7.7 microns were corroborated. The chemical composition of Mercury's surface must be feldspathic in order to explain spectra features found in the data obtained during the KAO flights.

  4. Climate change and watershed mercury export: a multiple projection and model analysis.

    Science.gov (United States)

    Golden, Heather E; Knightes, Christopher D; Conrads, Paul A; Feaster, Toby D; Davis, Gary M; Benedict, Stephen T; Bradley, Paul M

    2013-09-01

    Future shifts in climatic conditions may impact watershed mercury (Hg) dynamics and transport. An ensemble of watershed models was applied in the present study to simulate and evaluate the responses of hydrological and total Hg (THg) fluxes from the landscape to the watershed outlet and in-stream THg concentrations to contrasting climate change projections for a watershed in the southeastern coastal plain of the United States. Simulations were conducted under stationary atmospheric deposition and land cover conditions to explicitly evaluate the effect of projected precipitation and temperature on watershed Hg export (i.e., the flux of Hg at the watershed outlet). Based on downscaled inputs from 2 global circulation models that capture extremes of projected wet (Community Climate System Model, Ver 3 [CCSM3]) and dry (ECHAM4/HOPE-G [ECHO]) conditions for this region, watershed model simulation results suggest a decrease of approximately 19% in ensemble-averaged mean annual watershed THg fluxes using the ECHO climate-change model and an increase of approximately 5% in THg fluxes with the CCSM3 model. Ensemble-averaged mean annual ECHO in-stream THg concentrations increased 20%, while those of CCSM3 decreased by 9% between the baseline and projected simulation periods. Watershed model simulation results using both climate change models suggest that monthly watershed THg fluxes increase during the summer, when projected flow is higher than baseline conditions. The present study's multiple watershed model approach underscores the uncertainty associated with climate change response projections and their use in climate change management decisions. Thus, single-model predictions can be misleading, particularly in developmental stages of watershed Hg modeling. Copyright © 2013 SETAC.

  5. A global hybrid model for Mercury's interaction with the solar wind: Case study of the dipole representation

    Science.gov (United States)

    Richer, E.; Modolo, R.; Chanteur, G. M.; Hess, S.; Leblanc, F.

    2012-10-01

    The interaction of the solar wind (SW) with the magnetic field of Mercury is investigated by means of a three dimensional parallelized multispecies hybrid model. A comparison between two mathematical representations of Mercury's intrinsic magnetic field is studied. The first model is an Offset Dipole (OD) having the offset and dipolar moment reported by Anderson et al. (2011). The second model is a combination of a Dipole and a Quadrupole (DQ), the total field is fitted to the offset dipolar field, for northern latitudes greater than 50°. Simulations reproduce the features which characterize Mercury's interaction with the SW, encompassing the Bow Shock (BS), the magnetosheath, the magnetotail, the “cusps” region and the neutral current sheet. Global hybrid simulations of the Hermean magnetosphere run for the OD and DQ models demonstrate that the southern parts of the magnetospheres produced by the OD and DQ models differ greatly in topology and volume meanwhile their northern parts-are quite similar. In particular the DQ model exhibits a dome of closed field lines around the south pole in contrast to the OD. Without further information on the intrinsic magnetic field of the planet in the southern region which should be provided by BepiColombo after year 2020, we can only speculate on the influence of the different magnetic topologies on the magnetospheric dynamics.

  6. Global observations and modeling of atmosphere-surface exchange of elemental mercury: a critical review

    Science.gov (United States)

    Zhu, Wei; Lin, Che-Jen; Wang, Xun; Sommar, Jonas; Fu, Xuewu; Feng, Xinbin

    2016-04-01

    Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg0) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg0. Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O3, radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling. We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg0 flux observations in East

  7. Mercury in Arctic snow: Quantifying the kinetics of photochemical oxidation and reduction

    Energy Technology Data Exchange (ETDEWEB)

    Mann, E.A. [Department of Environmental Science, Acadia University, Wolfville, NS (Canada); Environmental Science Programme, Memorial University of Newfoundland, St. John' s, NL (Canada); Mallory, M.L. [Department of Biology, Acadia University, Wolfville, NS (Canada); Ziegler, S.E. [Environmental Science Programme, Memorial University of Newfoundland, St. John' s, NL (Canada); Tordon, R. [Environment Canada, Dartmouth, NS (Canada); O' Driscoll, N.J., E-mail: nelson.odriscoll@acadiau.ca [Department of Environmental Science, Acadia University, Wolfville, NS (Canada)

    2015-03-15

    Controlled experiments were performed with frozen and melted Arctic snow to quantify relationships between mercury photoreaction kinetics, ultra violet (UV) radiation intensity, and snow ion concentrations. Frozen (− 10 °C) and melted (4 °C) snow samples from three Arctic sites were exposed to UV (280–400 nm) radiation (1.26–5.78 W · m{sup −2}), and a parabolic relationship was found between reduction rate constants in frozen and melted snow with increasing UV intensity. Total photoreduced mercury in frozen and melted snow increased linearly with greater UV intensity. Snow with the highest concentrations of chloride and iron had larger photoreduction and photooxidation rate constants, while also having the lowest Hg(0) production. Our results indicate that the amount of mercury photoreduction (loss from snow) is the highest at high UV radiation intensities, while the fastest rates of mercury photoreduction occurred at both low and high intensities. This suggests that, assuming all else is equal, earlier Arctic snow melt periods (when UV intensities are less intense) may result in less mercury loss to the atmosphere by photoreduction and flux, since less Hg(0) is photoproduced at lower UV intensities, thereby resulting in potentially greater mercury transport to aquatic systems with snowmelt. - Highlights: • Mercury photochemical kinetics were studied in frozen and melted Arctic snow. • UV-induced photoreduction and photooxidation rate constants were quantified. • Chloride ion, iron, and DOC influence mercury photoreactions in snow. • Frozen and melted snow have different mercury photoreduction characteristics. • Kinetic information provided can be used to model mercury fate in the Arctic.

  8. Preliminary Assessment of Mercury Atmosphere-Surface Exchange Parameterizations for Incorporation into Chemical Transport Models

    Science.gov (United States)

    Khan, T.; Agnan, Y.; Obrist, D.; Selin, N. E.; Urban, N. R.; Wu, S.; Perlinger, J. A.

    2015-12-01

    Inadequate representation of process-based mechanisms of exchange behavior of elemental mercury (Hg0) and decoupled treatment of deposition and emission are two major limitations of parameterizations of atmosphere-surface exchange flux commonly incorporated into chemical transport models (CTMs). Of nineteen CTMs for Hg0 exchange we reviewed (ten global, nine regional), eight global and seven regional models have decoupled treatment of Hg0 deposition and emission, two global models include no parameterization to account for emission, and the remaining two regional models include coupled deposition and emission parameterizations (i.e., net atmosphere-surface exchange). The performance of atmosphere-surface exchange parameterizations in CTMs depends on parameterization uncertainty (in terms of both accuracy and precision) and feasibility of implementation. We provide a comparison of the performance of three available parameterizations of net atmosphere-surface exchange. To evaluate parameterization accuracy, we compare predicted exchange fluxes to field measurements conducted over a variety of surfaces compiled in a recently developed global database of terrestrial Hg0 surface-atmosphere exchange flux measurements. To assess precision, we estimate the sensitivity of predicted fluxes to the imprecision in parameter input values, and compare this sensitivity to that derived from analysis of the global Hg0 flux database. Feasibility of implementation is evaluated according to the availability of input parameters, computational requirements, and the adequacy of uncertainty representation. Based on this assessment, we provide suggestions for improved treatment of Hg0 net exchange processes in CTMs.

  9. An ion species model for positive ion sources - part I description of the model

    CERN Document Server

    Surrey, E

    2014-01-01

    A one dimensional model of the magnetic multipole volume plasma source has been developed for use in intense ion/neutral atom beam injectors. The model uses plasma transport coefficients for particle and energy flow to create a detailed description of the plasma parameters along an axis parallel to that of the extracted beam. Primarily constructed for applications to neutral beam injection systems on fusion devices, the model concentrates on the hydrogenic isotopes but can be extended to any gas by substitution of the relevant masses, cross sections and rate coefficients. The model considers the flow of fast ionizing electrons that create the ratios of the three hydrogenic isotope ion species, H+, H2 +, H3 + (and similarly for deuterium and tritium) as they flow towards the beam extraction electrode, together with the production of negative hydrogenic ions through volume processes. The use of detailed energy balance in the discharge allows the determination of the fraction of the gas density that is in an ato...

  10. Investigation of mercury-free potentiometric stripping analysis and the influence of mercury in the analysis of trace-elements lead and zinc

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Andersen, Laust

    1997-01-01

    Application of Potentiometric Stripping Analysis (PSA), without any mercury, to determination of trace-elements lead and zinc, results in linear responses between stripping-peak areas and concentrations within the range 0-2000 ng/g. The best response, as determined by the size of stripping areas...... in an electrolyte containing 0.1 M HCl and 2 mg/g Zn2+ and electrolysis at -1400 mV(SCE). It is suggested that the concentration range of linear response occur where the electrode is not fully covered by metal clusters during the electrolysis step. The influence of mercury is investigated and a model is proposed...... which explains the co-deposition of mercury and test metals in the electrolysis step in terms of a charge-distribution parameter. The model explains that the decrease of stripping peak area, as a function of concentration, is entirely due to mercury ions being simultaneously reduced together...

  11. Behaviour of ion velocity distributions for a simple collision model

    Science.gov (United States)

    St-Maurice, J.-P.; Schunk, R. W.

    1974-01-01

    Calculation of the ion velocity distributions for a weakly ionized plasma subjected to crossed electric and magnetic fields. An exact solution to Boltzmann's equation has been obtained by replacing the Boltzmann collision integral with a simple relaxation model. At altitudes above about 150 km, where the ion collision frequency is much less than the ion cyclotron frequency, the ion distribution takes the shape of a torus in velocity space for electric fields greater than 40 mV/m. This shape persists for one to two hours after application of the electric field. At altitudes where the ion collision and cyclotron frequencies are approximately equal (about 120 km), the ion velocity distribution is shaped like a bean for large electric field strengths. This bean-shaped distribution persists throughout the lifetime of ionospheric electric fields. These highly non-Maxwellian ion velocity distributions may have an appreciable affect on the interpretation of ion temperature measurements.

  12. Cooling effect of different buffer gas of trapped mercury ions in a linear ion trap%线型离子阱中不同缓冲气体对汞离子的冷却效果研究

    Institute of Scientific and Technical Information of China (English)

    杨玉娜; 柳浩; 何跃宏; 陈义和; 佘磊; 李交美

    2012-01-01

    Buffer gas cooling is the most effective and practical method to cool ions in ion trap.The kind and quantity of buffer gas are the key technologies in mercury ion microwave frequency standard experiments.Buffer gas made of helium,neon or argon was studied to cool trapped mercury ions (199Hg+)in a linear ion trap by introducing a resistance term in Mathieu's equation.It's found that the decay time of motion of 199Hg+ in argon gas is the shortest,and the frequency shift of the clock transition (40.5 GHz)is minimum when the pressure of helium is 10-5 Torr or the pressure of neon gas is 2.4 x 10-5 Torr.Neon is the most suitable buffer gas among helium,neon and argon,considering the decay time-constant of motion of 199Hg+ in buffer gases and 199Hg+ clock transition shift's sensitivity to the change of the pressure of buffer gas.%缓冲气体冷却是将离子阱中的离子云冷却的最有效和实用的方法,缓冲气体的种类和数量是汞离子微波频标实验的关键技术.通过在马修方程中引入阻力项的方法,研究了线型离子阱中氦气、氖气、氩气对囚禁的汞离子的冷却效果,结果表明在氩气中汞离子运动的衰减时间最短.研究了为使钟跃迁(40.5 GHz)的频率移动最小,所需氦气的压强为10-5 Torr,氖气的压强为2.4×10-5 Torr.考虑到缓冲气体对汞离子的冷却效率和对气体压强的敏感性,氖气要比氦气、氩气更适合作缓冲气体.

  13. Mercury's Sodium Exosphere: Observations during the MESSENGER Orbital Phase

    Science.gov (United States)

    Killen, Rosemary M.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; Burger, Matthew H.; Merkel, Aimee W.; Sarantos, Menelaos; Sprague, Ann L.; McClintock, William E.; Benna, Mehdi; Solomon, Sean C.

    2012-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered into orbit about Mercury on March 18,2011. We now have approximately five Mercury years of data from orbit. Prior to the MESSENGER mission, Mercury's surface-bounded exosphere was known to contain H, He, Na. K, and Ca. The Ultraviolet and Visible Spectrometer (UVVS) began routine orbital observations of both the dayside and nightside exosphere on March 29. 2011, measuring altitude profiles for all previously detected neutral species except for He and K. We focus here on what we have learned about the sodium exosphere: its spatial, seasonal, and sporadic variation. Observations to date permit delineation of the relative roles of photon-stimulated desorption (PSD) and impact vaporization (IV) from seasonal and spatial effects, as well as of the roles of ions both as sputtering agents and in their possible role to enhance the efficiency of PSD. Correlations of Mercury's neutral sodium exosphere with measurements from MESSENGER's Magnetometer (MAG) and Energetic Particle and Plasma Spectrometer (EPPS) provide insight into the roles of ions and electrons. Models incorporating MAG observations provide a basis for identifying the location and area of the surface exposed to solar wind plasma, and EPPS observations reveal episodic populations of energetic electrons in the magnetosphere and the presence of planetary He(+), 0(+), and Na(+),

  14. Characterisation and modelling of mercury speciation in urban air affected by gold mining - assessment of bioavailability

    Directory of Open Access Journals (Sweden)

    Cukrowska E. M.

    2013-04-01

    Full Text Available The growing global concern over the release of mercury to the environment has prompted specific inventories that quantify mercury emissions from various sources. Investigations of atmospheric mercury have been mostly done on gaseous species. Although, to assess human expose to mercury, especially in urban areas, the inhalable dust should be included in a study. The Witwatersrand Basin in South Africa is one of the most important gold mining regions in the world. Mercury (Hg, which occurs in gold-bearing ores, was also used for gold recoveries in previous centuries (19th and early 20th century and presently in illegal artisanal mining. The consequences of these mining activities were the release of Hg to the environment, mainly due to AMD from tailings dumps which are presently reprocessed. The city of Johannesburg is a multimillion population exposed strongly to industrial pollution. The aim of this study was to determine the magnitude of mercury pollution in this urban area and assess its bioavailability. The gaseous samples were collected by trapping mercury on various gold traps. Dust samples were collected from a ground and on inhalation levels (1–2 m above a ground. They were later separated into different fractions by micro sieving. Bioavailability of mercury in inhalable dust (25 μm was tested by leaching collected samples with artificial lung fluid (ALF, pH 4.5, Gray’s solution (pH 7.4 and water. The leaching conditions were selected to mimic lungs environment (incubator at 30°C, time 24 hrs, rotation of samples 150 rpm. Total concentrations of mercury in dust fractions were also determined after microwave digestion. The results showed extremely high concentration levels of mercury in air and dust in industrial areas. Especially high levels were found around presently reprocessed old gold tailings dumps, up to 900 000 μgl–1. The levels dropped significantly in CBD area but still showing elevated concentrations up to 10 μgl−1

  15. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash.

    Science.gov (United States)

    Liu, Minmin; Hou, Li-An; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-15

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and (29)Si and (27)Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  16. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    Science.gov (United States)

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  17. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Minmin [School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Hou, Li-an, E-mail: 11liuminmin@tongji.edu.cn [School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Xi, Beidou; Zhao, Ying; Xia, Xunfeng [China Research Academy of Environmental Science, Beijing 200012 (China)

    2013-05-15

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and {sup 29}Si and {sup 27}Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin–Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  18. Development with MESSENGER Data of a Model of Mercury's Magnetospheric Magnetic Field Confined within the Average Observed Magnetopause

    Science.gov (United States)

    Korth, H.; Tsyganenko, N. A.; Johnson, C. L.; Philpott, L. C.; Anderson, B. J.; Al Asad, M.; Solomon, S. C.; McNutt, R. L., Jr.

    2014-12-01

    Accurate knowledge of Mercury's magnetospheric magnetic field is required to understand the sources of the planet's internal field. We present the first model of Mercury's magnetospheric magnetic field that is confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The model consists of individual modules for magnetic fields of internal origin, approximated by a dipole of magnitude 190 nT RM3, where RM is Mercury's radius, offset northward by 479 km along the spin axis, and of external origin resulting from currents flowing on the magnetopause boundary and in the cross-tail current sheet. The cross-tail current is prescribed having a disk shape near the planet and extending into a Harris sheet at larger distances. The magnitude of the tail current is fit to minimize the root mean square residual between the magnetic field within the magnetosphere observed by MESSENGER and the model field. The magnetic field contribution from each module is shielded individually by a scalar potential function consisting of Cartesian harmonic expansions with linear and non-linear coefficients, which are fit to minimize the root-mean-square normal magnetic field component at the magnetopause. The resulting model resembles the observed magnetic field better than the previously developed paraboloid model in regions that are close to the magnetopause, i.e., at northern high latitudes and on the dayside. It will allow more accurate characterization of crustal magnetization, which may be observed during low-altitude orbits in the final months of the MESSENGER mission.

  19. Magnetohydrodynamics with Embedded Particle-in-Cell Simulation of Mercury's Magnetosphere

    Science.gov (United States)

    Chen, Y.; Toth, G.; Jia, X.; Gombosi, T. I.; Markidis, S.

    2015-12-01

    Mercury's magnetosphere is much more dynamic than other planetary magnetospheres because of Mercury's weak intrinsic magnetic field and its proximity to the Sun. Magnetic reconnection and Kelvin-Helmholtz phenomena occur in Mercury's magnetopause and magnetotail at higher frequencies than in other planetary magnetosphere. For instance, chains of flux transfer events (FTEs) on the magnetopause, have been frequentlyobserved by the the MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft (Slavin et al., 2012). Because ion Larmor radius is comparable to typical spatial scales in Mercury's magnetosphere, finite Larmor radius effects need to be accounted for. In addition, it is important to take in account non-ideal dissipation mechanisms to accurately describe magnetic reconnection. A kinetic approach allows us to model these phenomena accurately. However, kinetic global simulations, even for small-size magnetospheres like Mercury's, are currently unfeasible because of the high computational cost. In this work, we carry out global simulations of Mercury's magnetosphere with the recently developed MHD-EPIC model, which is a two-way coupling of the extended magnetohydrodynamic (XMHD) code BATS-R-US with the implicit Particle-in-Cell (PIC) model iPIC3D. The PIC model can cover the regions where kinetic effects are most important, such as reconnection sites. The BATS-R-US code, on the other hand, can efficiently handle the rest of the computational domain where the MHD or Hall MHD description is sufficient. We will present our preliminary results and comparison with MESSENGER observations.

  20. Colorimetric detection of mercury species based on functionalized gold nanoparticles.

    Science.gov (United States)

    Chen, Ling; Li, Jinhua; Chen, Lingxin

    2014-09-24

    The speciation analysis of heavy metal pollutants is very important because different species induce different toxicological effects. Nanomaterial-assisted optical sensors have achieved rapid developments, displaying wide applications to heavy metal ions but few to metal speciation analysis. In this work, a novel colorimetric nanosensor strategy for mercury speciation was proposed for the first time, based on the analyte-induced aggregation of gold nanoparticles (Au NPs) with the assistance of a thiol-containing ligand of diethyldithiocarbamate (DDTC). Upon the addition of mercury species, because Hg-DDTC was more stable than Cu-DDTC, a place-displacement between Hg species and Cu(2+) would occur, and thereby the functionalized Au NPs would aggregate, resulting in a color change. Moreover, by virtue of the masking effect of ethylenediaminetetraacetic acid (EDTA), the nanosensor could readily discriminate organic mercury and inorganic mercury (Hg(2+)), and it is thus anticipated to shed some light on the colorimetric sensing of organic mercury. So, a direct, simple colorimetric assay for selective determination of Hg species was obtained, presenting high detectability, such as up to 10 nM for Hg(2+) and 15 nM for methylmercury. Meanwhile, the strategy offered excellent selectivity toward mercury species against other metal ions. The simple, rapid, and sensitive label-free colorimetric sensor for the determination of Hg species provided an attractive alternative to conventional methods, which usually involve sophisticated instruments, complicated processes, and long periods of time. More importantly, by using mercury as a model, an excellent nanomaterial-based optical sensing platform can be developed for speciation analysis of trace heavy metals, which can lead to nanomaterials stability change through smart functionalization and reasonable interactions.

  1. Adsorption of toxic mercury(II) by an extracellular biopolymer poly(gamma-glutamic acid).

    Science.gov (United States)

    Inbaraj, B Stephen; Wang, J S; Lu, J F; Siao, F Y; Chen, B H

    2009-01-01

    Adsorption of mercury(II) by an extracellular biopolymer, poly(gamma-glutamic acid) (gamma-PGA), was studied as a function of pH, temperature, agitation time, ionic strength, light and heavy metal ions. An appreciable adsorption occurred at pH>3 and reached a maximum at pH 6. Isotherms were well predicted by Redlich-Peterson model with a dominating Freundlich behavior, implying the heterogeneous nature of mercury(II) adsorption. The adsorption followed an exothermic and spontaneous process with increased orderliness at solid/solution interface. The adsorption was rapid with 90% being attained within 5 min for a 80 mg/L mercury(II) solution, and the kinetic data were precisely described by pseudo second order model. Ionic strength due to added sodium salts reduced the mercury(II) binding with the coordinating ligands following the order: Cl(-) >SO(4)(2-) >NO(3)(-). Both light and heavy metal ions decreased mercury(II) binding by gamma-PGA, with calcium(II) ions showing a more pronounced effect than monovalent sodium and potassium ions, while the interfering heavy metal ions followed the order: Cu(2+) > Cd(2+) > Zn(2+). Distilled water adjusted to pH 2 using hydrochloric acid recovered 98.8% of mercury(II), and gamma-PGA reuse for five cycles of operation showed a loss of only 6.5%. IR spectra of gamma-PGA and Hg(II)-gamma-PGA revealed binding of mercury(II) with carboxylate and amide groups on gamma-PGA.

  2. Micelles entrapped Cresyl Violet can selectively detect copper and mercury ions in solution: A fluorescence Correlation Spectroscopy investigation

    Science.gov (United States)

    Das, Nirmal Kumar; Ghosh, Subhadip; Jaiswal, Sunidhi; Tewary, Anu; Mukherjee, Saptarshi

    2017-08-01

    The dynamic interaction of Cresyl Violet (CV) in different micellar systems has been demonstrated in single molecular level by FCS studies. The SDS micelle entrapped CV efficiently detected Cu2+ ions in solution with a limit of detection (LOD) of 70 nM, which is further substantiated with the gradual enhancement of the translational motion. The CV entrapped in the DTAB micelles could selectively detect Hg2+ ions in solution with a LOD of 35 nM. The micelle encapsulated CV was effective in detecting these metal ions in real water samples from different sources.

  3. Mercury(1)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    1.Mercury is the planet closest to the sun.It is thefastest moving planet.And it is the second smallestplanet in our solar system. 2.Mercury is very difficult to see.Its orbit isbetween us and the sun.So,we have to look toward thebright light of the sun to see it.The sunlight usuallyhides Mercury.When we can see it,it appears as a fuzzyball.

  4. Adsorption of mercury on lignin: combined surface complexation modeling and X-ray absorption spectroscopy studies.

    Science.gov (United States)

    Lv, Jitao; Luo, Lei; Zhang, Jing; Christie, Peter; Zhang, Shuzhen

    2012-03-01

    Adsorption of mercury (Hg) on lignin was studied at a range of pH values using a combination of batch adsorption experiments, a surface complexation model (SCM) and synchrotron X-ray absorption spectroscopy (XAS). Surface complexation modeling indicates that three types of acid sites on lignin surfaces, namely aliphatic carboxylic-, aromatic carboxylic- and phenolic-type surface groups, contributed to Hg(II) adsorption. The bond distance and coordination number of Hg(II) adsorption samples at pH 3.0, 4.0 and 5.5 were obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy analysis. The results of SCM and XAS combined reveal that the predominant adsorption species of Hg(II) on lignin changes from HgCl(2)(0) to monodentate complex -C-O-HgCl and then bidentate complex -C-O-Hg-O-C- with increasing pH value from 2.0 to 6.0. The good agreement between SCM and XAS results provides new insight into understanding the mechanisms of Hg(II) adsorption on lignin.

  5. EMMMA: A web-based system for environmental mercury mapping, modeling, and analysis

    Science.gov (United States)

    Hearn,, Paul P.; Wente, Stephen P.; Donato, David I.; Aguinaldo, John J.

    2006-01-01

    Mercury in our environment - in our air, water, soil, and especially our food - poses significant hazards to human health, particularly for developing fetuses and young children. Because of the importance of this issue and the length of time it has been studied, large and complex data sets of mercury concentrations in various media and associated ancillary data have been generated by many Federal, State, Tribal, and local agencies. To facilitate efficient and effective use of these

  6. A new isoindoline-based highly selective "turn-on" fluorescent chemodosimeter for detection of mercury ion.

    Science.gov (United States)

    Zali-Boeini, Hassan; Zareh Jonaghani, Mohammad; Fadaei, Negar; Rudbari, Hadi Amiri

    2017-05-05

    A new isoindoline-based highly efficient turn-on fluorescent chemodosimeter S with a thioamide functionality as a binding site for selective detection of Hg(2+) ion has been developed. The chemodosimeter S showed an extreme selectivity for detection of Hg(2+) ion among various two and three-valent metal ions in acetonitrile/water (70/30, v/v). It was found that, in the presence of Hg(2+) ion the non-fluorescent chemodosimeter S was efficiently and rapidly desulfurized to the corresponding highly fluorescent amide 1. A good linear relationship was shown between the fluorescence intensity and the concentration of Hg(2+) within the range of 0-1μM, with a detection limit of 2.03×10(-8)M.

  7. Nutrient supply and mercury dynamics in marine ecosystems: a conceptual model.

    Science.gov (United States)

    Driscoll, Charles T; Chen, Celia Y; Hammerschmidt, Chad R; Mason, Robert P; Gilmour, Cynthia C; Sunderland, Elsie M; Greenfield, Ben K; Buckman, Kate L; Lamborg, Carl H

    2012-11-01

    There is increasing interest and concern over the impacts of mercury (Hg) inputs to marine ecosystems. One of the challenges in assessing these effects is that the cycling and trophic transfer of Hg are strongly linked to other contaminants and disturbances. In addition to Hg, a major problem facing coastal waters is the impacts of elevated nutrient, particularly nitrogen (N), inputs. Increases in nutrient loading alter coastal ecosystems in ways that should change the transport, transformations and fate of Hg, including increases in fixation of organic carbon and deposition to sediments, decreases in the redox status of sediments and changes in fish habitat. In this paper we present a conceptual model which suggests that increases in loading of reactive N to marine ecosystems might alter Hg dynamics, decreasing bioavailabilty and trophic transfer. This conceptual model is most applicable to coastal waters, but may also be relevant to the pelagic ocean. We present information from case studies that both support and challenge this conceptual model, including marine observations across a nutrient gradient; results of a nutrient-trophic transfer Hg model for pelagic and coastal ecosystems; observations of Hg species, and nutrients from coastal sediments in the northeastern U.S.; and an analysis of fish Hg concentrations in estuaries under different nutrient loadings. These case studies suggest that changes in nutrient loading can impact Hg dynamics in coastal and open ocean ecosystems. Unfortunately none of the case studies is comprehensive; each only addresses a portion of the conceptual model and has limitations. Nevertheless, our conceptual model has important management implications. Many estuaries near developed areas are impaired due to elevated nutrient inputs. Widespread efforts are underway to control N loading and restore coastal ecosystem function. An unintended consequence of nutrient control measures could be to exacerbate problems associated with Hg

  8. A double-layer based model of ion confinement in electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Mascali, D., E-mail: davidmascali@lns.infn.it; Neri, L.; Celona, L.; Castro, G.; Gammino, S.; Ciavola, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Torrisi, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile, Via Graziella, I-89100 Reggio Calabria (Italy); Sorbello, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica, Viale Andrea Doria 6, 95125 Catania (Italy)

    2014-02-15

    The paper proposes a new model of ion confinement in ECRIS, which can be easily generalized to any magnetic configuration characterized by closed magnetic surfaces. Traditionally, ion confinement in B-min configurations is ascribed to a negative potential dip due to superhot electrons, adiabatically confined by the magneto-static field. However, kinetic simulations including RF heating affected by cavity modes structures indicate that high energy electrons populate just a thin slab overlapping the ECR layer, while their density drops down of more than one order of magnitude outside. Ions, instead, diffuse across the electron layer due to their high collisionality. This is the proper physical condition to establish a double-layer (DL) configuration which self-consistently originates a potential barrier; this “barrier” confines the ions inside the plasma core surrounded by the ECR surface. The paper will describe a simplified ion confinement model based on plasma density non-homogeneity and DL formation.

  9. Mobilization of mercury from lean tissues during simulated migratory fasting in a model songbird.

    Science.gov (United States)

    Seewagen, Chad L; Cristol, Daniel A; Gerson, Alexander R

    2016-05-12

    The pollutant methylmercury accumulates within lean tissues of birds and other animals. Migrating birds catabolize substantial amounts of lean tissue during flight which may mobilize methylmercury and increase circulating levels of this neurotoxin. As a model for a migrating songbird, we fasted zebra finches (Taeniopygia guttata) that had been dosed with 0.0, 0.1, and 0.6 parts per million (ppm) dietary methylmercury and measured changes in blood total mercury concentrations (THg) in relation to reductions in lean mass. Birds lost 6-16% of their lean mass during the fast, and THg increased an average of 12% and 11% in the 0.1 and 0.6 ppm treatments, respectively. Trace amounts of THg in the 0.0 ppm control group also increased as a result of fasting, but remained extremely low. THg increased 0.4 ppm for each gram of lean mass catabolized in the higher dose birds. Our findings indicate that methylmercury is mobilized from lean tissues during protein catabolism and results in acute increases in circulating concentrations. This is a previously undocumented potential threat to wild migratory birds, which may experience greater surges in circulating methylmercury than demonstrated here as a result of their greater reductions in lean mass.

  10. Computing ordinary least-squares parameter estimates for the National Descriptive Model of Mercury in Fish

    Science.gov (United States)

    Donato, David I.

    2013-01-01

    A specialized technique is used to compute weighted ordinary least-squares (OLS) estimates of the parameters of the National Descriptive Model of Mercury in Fish (NDMMF) in less time using less computer memory than general methods. The characteristics of the NDMMF allow the two products X'X and X'y in the normal equations to be filled out in a second or two of computer time during a single pass through the N data observations. As a result, the matrix X does not have to be stored in computer memory and the computationally expensive matrix multiplications generally required to produce X'X and X'y do not have to be carried out. The normal equations may then be solved to determine the best-fit parameters in the OLS sense. The computational solution based on this specialized technique requires O(8p2+16p) bytes of computer memory for p parameters on a machine with 8-byte double-precision numbers. This publication includes a reference implementation of this technique and a Gaussian-elimination solver in preliminary custom software.

  11. Mercury(5)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    26. Mercury appears to have a center of iron thattakes up seventy-five percent 0f the planet. There isonly a thin outer covering of rock around the core. Someastronomers think most of Mercury's rock was explodedoff when the planet was hit by a huge object early in itshistory.

  12. Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC).

    Science.gov (United States)

    Kim, Eun-Ah; Masue-Slowey, Yoko; Fendorf, Scott; Luthy, Richard G

    2012-02-01

    The depth profile of mercuric ion after the reaction with polysulfide-rubber-coated activated carbon (PSR-AC) was investigated using micro-X-ray fluorescence (μ-XRF) imaging techniques and mathematical modeling. The μ-XRF results revealed that mercury was concentrated at 0-100 μm from the exterior of the particle after 3 months of treatment with PSR-AC in 10 ppm HgCl(2) aqueous solution. The μ-X-ray absorption near edge spectroscopic (μ-XANES) analyses indicated HgS as a major mercury species, and suggested that the intra-particle mercury transport involved a chemical reaction with PSR polymer. An intra-particle mass transfer model was developed based on either a Langmuir sorption isotherm with liquid phase diffusion (Langmuir model) or a kinetic sorption with surface diffusion (kinetic sorption model). The Langmuir model predicted the general trend of mercury diffusion, although at a slower rate than observed from the μ-XRF map. A kinetic sorption model suggested faster mercury transport, which overestimated the movement of mercuric ions through an exchange reaction between the fast and slow reaction sites. Both μ-XRF and mathematical modeling results suggest mercury removal occurs not only at the outer surface of the PSR-AC particle but also at some interior regions due to a large PSR surface area within an AC particle.

  13. Modeling and mapping of atmospheric mercury deposition in adirondack park, new york.

    Directory of Open Access Journals (Sweden)

    Xue Yu

    Full Text Available The Adirondacks of New York State, USA is a region that is sensitive to atmospheric mercury (Hg deposition. In this study, we estimated atmospheric Hg deposition to the Adirondacks using a new scheme that combined numerical modeling and limited experimental data. The majority of the land cover in the Adirondacks is forested with 47% of the total area deciduous, 20% coniferous and 10% mixed. We used litterfall plus throughfall deposition as the total atmospheric Hg deposition to coniferous and deciduous forests during the leaf-on period, and wet Hg deposition plus modeled atmospheric dry Hg deposition as the total Hg deposition to the deciduous forest during the leaf-off period and for the non-forested areas year-around. To estimate atmospheric dry Hg deposition we used the Big Leaf model. The average atmospheric Hg deposition to the Adirondacks was estimated as 17.4 [Formula: see text]g m[Formula: see text] yr[Formula: see text] with a range of -3.7-46.0 [Formula: see text]g m[Formula: see text] yr[Formula: see text]. Atmospheric Hg dry deposition (370 kg yr[Formula: see text] was found to be more important than wet deposition (210 kg yr[Formula: see text] to the entire Adirondacks (2.4 million ha. The spatial pattern showed a large variation in atmospheric Hg deposition with scattered areas in the eastern Adirondacks having total Hg deposition greater than 30 μg m(-2 yr(-1, while the southwestern and the northern areas received Hg deposition ranging from 25-30 μg m(-2 yr(-1.

  14. Influence of Arsenic (III, Cadmium (II, Chromium (VI, Mercury (II, and Lead (II Ions on Human Triple Negative Breast Cancer (HCC1806 Cell Cytotoxicity and Cell Viability

    Directory of Open Access Journals (Sweden)

    Tsdale F. Mehari

    2017-01-01

    Full Text Available The hazardous consequences of heavy metal ions (HMIs on human health necessitate the immediate need to probe fundamentally the interactions and cytotoxic effects of HMIs on humans. This study investigated the influence of five toxic HMIs (arsenic (As (III, cadmium (Cd (II, chromium (Cr (VI, mercury (Hg (II, and lead (Pb (II on human TNBC (HCC 1806 cell viability using optical microscopy, trypan blue dye-exclusion assays, and flow cytometry. The TNBC cells were exposed to varying concentrations of HMIs for 24 and 48 hours. We evaluated the influence of the concentrations and duration of HMIs exposure on TNBC cell viability. Light microscopy, cell viability assays, revealed that after 48-hour treatment of TNBC cells with 1 x 10-5 M of As (III, Cd (II, Hg (II, Cr (IV, and Pb (II resulted in cell viabilities of 23%, 34%, 35%, 56%, 91% respectively, suggesting that As (III has the greatest cytotoxicity (77% cell death while Pb (II showed the least (9% cell death. Furthermore, flow cytometry revealed that while Pb (II, As (III and Cr (IV had significant increases in cell death, Hg (II caused a G1 arrest. Together, this study revealed that HMIs cause a differential cytotoxic effect on TNBC cells and suggest that they may have very different genotoxic targets and implications in their mutagenic potential.

  15. Electrochemical behavior of phytochelatins and related peptides at the hanging mercury drop electrode in the presence of cobalt(II) ions.

    Science.gov (United States)

    Dorcák, Vlastimil; Sestáková, Ivana

    2006-01-01

    Direct current voltammetry and differential pulse voltammetry have been used to investigate the electrochemical behaviour of two phytochelatins: heptapeptide (gamma-Glu-Cys)3-Gly and pentapeptide (gamma-Glu-Cys)2-Gly, tripeptide glutathione gamma-Glu-Cys-Gly and its fragments: dipeptides Cys-Gly and gamma-Glu-Cys at the hanging mercury drop electrode in the presence of cobalt(II) ions. Most interesting results were obtained with direct current voltammetry in the potential region of -0.80 V up to -1.80 V. Differential pulse voltammetry of the same solutions of Co(II) with peptides gives more complicated voltammograms with overlapping peaks, probably in connection with the influence of adsorption at slow scan rates necessarily used in this method. However, in using Brdicka catalytic currents for analytical purposes, differential pulse voltammograms seem to be more helpful. Presented investigations have shown that particularly the prewave of cobalt(II) allows distinguishing among phytochelatins, glutathione, and its fragments.

  16. Trifunctional molecular beacon-mediated quadratic amplification for highly sensitive and rapid detection of mercury(II) ion with tunable dynamic range.

    Science.gov (United States)

    Zhao, Yue; Liu, Huaqing; Chen, Feng; Bai, Min; Zhao, Junwu; Zhao, Yongxi

    2016-12-15

    Analyses of target with low abundance or concentration varying over many orders of magnitude are severe challenges faced by numerous assay methods due to their modest sensitivity and limited dynamic range. Here, we introduce a homogeneous and rapid quadratic polynomial amplification strategy through rational design of a trifunctional molecular beacon, which serves as not only a reporter molecule but also a bridge to couple two stage amplification modules without adding any reaction components or process other than basic linear amplification. As a test bed for our studies, we took mercury(II) ion as an example and obtained a high sensitivity with detection limit down to 200 pM within 30min. In order to create a tunable dynamic range, homotropic allostery is employed to modulate the target specific binding. When the number of metal binding site varies from 1 to 3, signal response is programmed accordingly with useful dynamic range spanning 50, 25 and 10 folds, respectively. Furthermore, the applicability of the proposed method in river water and biological samples are successfully verified with good recovery and reproducibility, indicating considerable potential for its practicality in complex real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  18. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  19. Feeding mice with diets containing mercury-contaminated fish flesh from French Guiana: a model for the mercurial intoxication of the Wayana Amerindians

    Directory of Open Access Journals (Sweden)

    Rossignol Rodrigue

    2008-10-01

    Full Text Available Abstract Background In 2005, 84% of Wayana Amerindians living in the upper marshes of the Maroni River in French Guiana presented a hair mercury concentration exceeding the limit set up by the World Health Organization (10 μg/g. To determine whether this mercurial contamination was harmful, mice have been fed diets prepared by incorporation of mercury-polluted fish from French Guiana. Methods Four diets containing 0, 0.1, 1, and 7.5% fish flesh, representing 0, 5, 62, and 520 ng methylmercury per g, respectively, were given to four groups of mice for a month. The lowest fish regimen led to a mercurial contamination pressure of 1 ng mercury per day per g of body weight, which is precisely that affecting the Wayana Amerindians. Results The expression of several genes was modified with mercury intoxication in liver, kidneys, and hippocampus, even at the lowest tested fish regimen. A net genetic response could be observed for mercury concentrations accumulated within tissues as weak as 0.15 ppm in the liver, 1.4 ppm in the kidneys, and 0.4 ppm in the hippocampus. This last value is in the range of the mercury concentrations found in the brains of chronically exposed patients in the Minamata region or in brains from heavy fish consumers. Mitochondrial respiratory rates showed a 35–40% decrease in respiration for the three contaminated mice groups. In the muscles of mice fed the lightest fish-containing diet, cytochrome c oxidase activity was decreased to 45% of that of the control muscles. When mice behavior was assessed in a cross maze, those fed the lowest and mid-level fish-containing diets developed higher anxiety state behaviors compared to mice fed with control diet. Conclusion We conclude that a vegetarian diet containing as little as 0.1% of mercury-contaminated fish is able to trigger in mice, after only one month of exposure, disorders presenting all the hallmarks of mercurial contamination.

  20. Sensitive pseudobienzyme electrocatalytic DNA biosensor for mercury(II) ion by using the autonomously assembled hemin/G-quadruplex DNAzyme nanowires for signal amplification

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yali [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); College of resources and environments, Southwest University, Chongqing 400715 (China); Gao, Min [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Liu, Guangpeng [College of resources and environments, Southwest University, Chongqing 400715 (China); Chai, Yaqin [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Wei, Shiqing, E-mail: sqwei@swu.edu.cn [College of resources and environments, Southwest University, Chongqing 400715 (China); Yuan, Ruo, E-mail: yuanruo@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2014-02-06

    Graphical abstract: -- Highlights: •An ultrasensitive detection system for Hg{sup 2+} detection was presented. •The autonomously assembled hemin/G-quadruplex DNAzyme nanowires were employed. •The DNAzyme simultaneously served as an NADH oxidase and HRP-mimicking DNAzyme. •The DNAzyme nanowires served as carrier for loading substantial redox probe Thi. -- Abstract: Herein, a novel sensitive pseudobienzyme electrocatalytic DNA biosensor was proposed for mercury ion (Hg{sup 2+}) detection by using autonomously assembled hemin/G-quadruplex DNAzyme nanowires for signal amplification. Thiol functionalized capture DNA was firstly immobilized on a nano-Au modified glass carbon electrode (GCE). In presence of Hg{sup 2+}, the specific coordination between Hg{sup 2+} and T could result in the assembly of primer DNA on the electrode, which successfully triggered the HCR to form the hemin/G-quadruplex DNAzyme nanowires with substantial redox probe thionine (Thi). In the electrolyte of PBS containing NADH, the hemin/G-quadruplex nanowires firstly acted as an NADH oxidase to assist the concomitant formation of H{sub 2}O{sub 2} in the presence of dissolved O{sub 2}. Then, with the redox probe Thi as electron mediator, the hemin/G-quadruplex nanowires acted as an HRP-mimicking DNAzyme that quickly bioelectrocatalyzed the reduction of produced H{sub 2}O{sub 2}, which finally led to a dramatically amplified electrochemical signal. This method has demonstrated a high sensitivity of Hg{sup 2+} detection with the dynamic concentration range spanning from 1.0 ng L{sup −1} to 10 mg L{sup −1} Hg{sup 2+} and a detection limit of 0.5 ng L{sup −1} (2.5 pM) at the 3S{sub blank} level, and it also demonstrated excellent selectivity against other interferential metal ions.

  1. Water flow experiments and analyses on the cross-flow type mercury target model with the flow guide plates

    CERN Document Server

    Haga, K; Kaminaga, M; Hino, R

    2001-01-01

    A mercury target is used in the spallation neutron source driven by a high-intensity proton accelerator. In this study, the effectiveness of the cross-flow type mercury target structure was evaluated experimentally and analytically. Prior to the experiment, the mercury flow field and the temperature distribution in the target container were analyzed assuming a proton beam energy and power of 1.5 GeV and 5 MW, respectively, and the feasibility of the cross-flow type target was evaluated. Then the average water flow velocity field in the target mock-up model, which was fabricated from Plexiglass for a water experiment, was measured at room temperature using the PIV technique. Water flow analyses were conducted and the analytical results were compared with the experimental results. The experimental results showed that the cross-flow could be realized in most of the proton beam path area and the analytical result of the water flow velocity field showed good correspondence to the experimental results in the case w...

  2. Lithium ion transport in a model of amorphous polyethylene oxide.

    Energy Technology Data Exchange (ETDEWEB)

    Boinske, P. T.; Curtiss, L.; Halley, J. W.; Lin, B.; Sutjianto, A.; Chemical Engineering; Univ. of Minnesota

    1996-01-01

    We have made a molecular dynamics study of transport of a single lithium ion in a previously reported model of amorphous polyethylene oxide. New ab initio calculations of the interaction of the lithium ion with 1,2-dimethoxyethane and with dimethyl ether are reported which are used to determine force fields for the simulation. We report preliminary calculations of solvation energies and hopping barriers and a calculation of the ionic conductivity which is independent of any assumptions about the mechanism of ion transport. We also report some details of a study of transport of the trapped lithium ion on intermediate time and length scales.

  3. Unified Ion-chemical Model for the Middle Atmosphere

    Science.gov (United States)

    Kamsali, Nagaraja; Kamsali, Nagaraja; Datta, Jayati; Prasad, Bsn

    The importance of ion-chemical model studies in our understanding of middle atmospheric regions needs no special emphasis. Present day knowledge of middle atmosphere (0-100 km) has come from two distinct experimental developments: first, in situ measurements of ion composition by balloons and sounding rockets and second, laboratory investigations on ionchemical reactions of importance at these heights, determination of reaction rate coefficients and their temperature dependence. Model studies act as an interface between these, to generate theoretical estimates of ion composition and their derivatives (e.g. electrical conductivity) by using as input the laboratory data on reaction rate coefficients and the data on neutral species density, ionization flux, temperature etc. Free electrons exist only in the mesosphere. Positive molecular ions dominate the upper mesospheric heights and heavy positive and negative cluster ions appearing at the lower mesospheric heights continue to dominate in strato and troposphere. The equilibrium density of electrons and ionic species is governed by: a) ionization of the atmospheric constituents producing electron-positive ion pair b)gas-phase ion-chemical reactions that convert the electrons and primary positive ions into heavy cluster ions of both polarity c)heterogeneous ion-chemical reactions for producing aerosol ions and d) loss mechanisms for small ions and aerosol ions through recombination of oppositely charged species. Physical entities that control the ion production and loss processes are not the same and vary vastly both in nature and magnitude in the middle atmosphere X-rays, Lymann-alpha and precipitating electrons are the dominant ionizing agents at the mesospheric heights. Cosmic ray ionization that is not so significant in the mesosphere is the sole ionizing agent at stratosphere and troposphere. At the ground level and up to a few tens of meters above the earth's surface, natural radioactivity induced ionization is

  4. Numerical model of electron cyclotron resonance ion source

    Directory of Open Access Journals (Sweden)

    V. Mironov

    2015-12-01

    Full Text Available Important features of the electron cyclotron resonance ion source (ECRIS operation are accurately reproduced with a numerical code. The code uses the particle-in-cell technique to model the dynamics of ions in ECRIS plasma. It is shown that a gas dynamical ion confinement mechanism is sufficient to provide the ion production rates in ECRIS close to the experimentally observed values. Extracted ion currents are calculated and compared to the experiment for a few sources. Changes in the simulated extracted ion currents are obtained with varying the gas flow into the source chamber and the microwave power. Empirical scaling laws for ECRIS design are studied and the underlying physical effects are discussed.

  5. Mercury sources, distribution, and bioavailability in the North Pacific Ocean: Insights from data and models

    Science.gov (United States)

    Sunderland, E.M.; Krabbenhoft, D.P.; Moreau, J.W.; Strode, S.A.; Landing, W.M.

    2009-01-01

    Fish harvested from the Pacific Ocean are a major contributor to human methylmercury (MeHg) exposure. Limited oceanic mercury (Hg) data, particularly MeHg, has confounded our understanding of linkages between sources, methylation sites, and concentrations in marine food webs. Here we present methylated (MeHg and dimethylmercury (Me2Hg)) and total Hg concentrations from 16 hydrographie stations in the eastern North Pacific Ocean. We use these data in combination with information from previous cruises and coupled atmospheric-oceanic modeling results to better understand controls on Hg concentrations, distribution, and bioavailability. Total Hg concentrations (average 1.14 ?? 0.38 pM) are elevated relative to previous cruises. Modeling results agree with observed increases and suggest that at present atmospheric Hg deposition rates, basin-wide Hg concentrations will double relative to circa 1995 by 2050. Methylated Hg accounts for up to 29% of the total Hg in subsurface waters (average 260 ??114 fM). We observed lower ambient methylated Hg concentrations in the euphotic zone and older, deeper water masses, which likely result from decay of MeHg and Me2Hg when net production is not occurring. We found a significant, positive linear relationship between methylated Hg concentrations and rates of organic carbon remineralization (r2 = 0.66, p < 0.001). These results provide evidence for the importance of particulate organic carbon (POC) transport and remineralization on the production and distribution of methylated Hg species in marine waters. Specifically, settling POC provides a source of inorganic Hg(II) to microbially active subsurface waters and can also provide a substrate for microbial activity facilitating water column methylation. Copyright 2009 by the American Geophysical Union.

  6. Modeling of Crystalline Silicotitanate Ion Exchange Columns

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.D.

    1999-03-09

    Non-elutable ion exchange is being considered as a potential replacement for the In-Tank Precipitation process for removing cesium from Savannah River Site (SRS) radioactive waste. Crystalline silicotitanate (CST) particles are the reference ion exchange medium for the process. A major factor in the construction cost of this process is the size of the ion exchange column required to meet product specifications for decontaminated waste. To validate SRS column sizing calculations, SRS subcontracted two reknowned experts in this field to perform similar calculations: Professor R. G. Anthony, Department of Chemical Engineering, Texas A&038;M University, and Professor S. W. Wang, Department of Chemical Engineering, Purdue University. The appendices of this document contain reports from the two subcontractors. Definition of the design problem came through several meetings and conference calls between the participants and SRS personnel over the past few months. This document summarizes the problem definition and results from the two reports.

  7. To Mercury dynamics

    Science.gov (United States)

    Barkin, Yu. V.; Ferrandiz, J. M.

    obtain new and accurate data about dynamics and structure of this planet (Anselmi et al., 2001). There are also some evaluations of moments of inertia Mercury and its core: C/(mR^2)=0.35, C_m /C=0.5± 0.07, (Peal, 1996). Here C and C_m are the moments of inertia of the full Mercury and of its core, m and R is a mass and a mean radius of Mercury. Based on two methods, we consider the rotation of Mercury in the gravitational field of the Sun. First method of perturbation has been effectively applied to the construction of a rotational theory of the Earth for its models as two or three layer celestial body moving in gravitational fields of the Moon, Sun and planets in wide set of papers ranging in 1999-2001 years of Ferrandiz J.M. and Getino J.(2001). Some generalization of this Hamiltonian formalism on the case of cavity (core) with arbitrary dynamical and geometrical oblateness has been obtained in a paper (Barkin, Ferrandiz, 2001). Another method is an analytical method of construction of the resonant rotational motion of synchronous satellites and Mercury, considered as non-spherical rigid bodies. This method has been applied earlier to construction of an analytical theory of rotation of the Moon considered as rigid non-spherical body (Barkin, 1989). Here we modified these methods to apply them to the study of the resonant rotation of a two-layer Mercury. By this we use very effective for the application of perturbation methods and dynamical geometrical illustration of canonical equations in Andoyer and Poincare variables. Main resonant properties of Mercury motion were been described first as generalized Cassini's laws (Colombo, 1966). But Colombo and some anothers scientists (Peal, 1969; Beletskii, 1972; Ward, 1975 and oth.) considered Mercury as rigid non-spherical body sometimes taking into account tidal deformation. Here we have been obtained and formulated these laws and their generalization for a two-layer model of Mercury. On the next step we have evaluated

  8. A Simulation Model for the Toroidal Ion Temperature Gradient Instability with Fully Kinetic Ions

    Science.gov (United States)

    Sturdevant, Benjamin; Parker, Scott; Chen, Yang

    2016-10-01

    A simulation model for the toroidal ITG mode in which the ions follow the primitive Lorentz force equations of motion is presented. Such a model can provide an important validation tool or replacement for gyrokinetic ion models in applications where higher order terms may be important. A number of multiple-scale simulation techniques are employed in this work, based on the previous success in slab geometry with an implicit orbit averaged and sub-cycled δf model. For the toroidal geometry model, we have derived a particle integration scheme based on variational principles, which is demonstrated to produce stable and accurate ion trajectories on long time scales. Orbit averaging and sub-cycling will be implemented with the variational integration scheme. The inclusion of equilibrium gradients in the fully kinetic δf formulation is achieved through the use of a guiding center coordinate transformation of the weight equation. Simulation results for the fully kinetic ion model will be presented for the cyclone base case and comparisons will be made with gyrokinetic ion models.

  9. Effects of environmental levels of cadmium, lead and mercury on human renal function evaluated by structural equation modeling.

    Science.gov (United States)

    Trzeciakowski, Jerome P; Gardiner, Lesley; Parrish, Alan R

    2014-07-03

    A relationship between exposure to heavy metals, including lead and cadmium, and renal dysfunction has long been suggested. However, modeling of the potential additive, or synergistic, impact of metals on renal dysfunction has proven to be challenging. In these studies, we used structural equation modeling (SEM), to investigate the relationship between heavy metal burden (serum and urine levels of lead, cadmium and mercury) and renal function using data from the NHANES database. We were able to generate a model with goodness of fit indices consistent with a well-fitting model. This model demonstrated that lead and cadmium had a negative relationship with renal function, while mercury did not contribute to renal dysfunction. Interestingly, a linear relationship between lead and loss of renal function was observed, while the maximal impact of cadmium occurred at or above serum cadmium levels of 0.8 μg/L. The interaction of lead and cadmium in loss of renal function was also observed in the model. These data highlight the use of SEM to model interaction between environmental contaminants and pathophysiology, which has important implications in mechanistic and regulatory toxicology.

  10. Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics

    Science.gov (United States)

    Poh, Gang Kai

    Mercury has proven to be a unique natural laboratory for space plasma processes. Mercury's magnetosphere is formed by the interaction between its intrinsic planetary magnetic field and the supersonic solar wind. The structure of Mercury's magnetosphere is very similar to Earth's; yet the results from the MESSENGER mission to Mercury have shown that the spatial and temporal scales of magnetospheric processes are very different at Mercury. In this thesis, we analyze in situ observations from the MESSENGER spacecraft to characterize and understand the dynamic physical plasma processes occurring in Mercury's magnetosphere. We identified and analyzed 345 plasma filaments in Mercury's northern magnetospheric cusp to determine their physical properties. Cusp plasma filaments are magnetic structures that are identified on the basis of their characteristic 2-3 seconds long decrease in magnetic field intensity. Our analysis indicates that these cusp filaments are cylindrical flux tubes filled with plasma, which causes a diamagnetic decrease in the magnetic field inside the flux tube. MESSENGER observations of flux transfer events (FTEs) and cusp filament suggests that cusp filaments properties are the low-altitude extension of FTEs formed at Mercury's dayside magnetopause. We examined 319 central plasma sheet crossings observed by MESSENGER. Using a Harris model, we determined the physical properties of Mercury's cross-tail current sheet. Analysis of BZ in the current sheet indicated that MESSENGER usually crossed the current sheet sunward of the Near Mercury Neutral Line. Magnetohydrodynamics-based analysis using the MESSENGER magnetic field and plasma measurements suggests that heavy planetary ions and/or ion temperature anisotropy may be important in maintaining radial stress balance within Mercury's central plasma sheet. We report the observation of significant dawn-dusk variation in Mercury's cross-tail current sheet with thicker, lower plasma beta dawn side current

  11. Adsorption of chromium(III), mercury(II) and lead(II) ions onto 4-aminoantipyrine immobilized bentonite.

    Science.gov (United States)

    Wang, Qihui; Chang, Xijun; Li, Dandan; Hu, Zheng; Li, Ruijun; He, Qun

    2011-02-28

    In this work, the immobilization of 4-aminoantipyrine onto bentonite was carried out and it was then used to investigate the adsorption behavior of Cr(III), Hg(II) and Pb(II) ions from aqueous solutions. The separation and preconcentration conditions of analytes were investigated, including effects of pH, the shaking time, the sample flow rate and volume, the elution condition and the interfering ions. Under optimum pH value (pH 4.0), the maximum static adsorption capacity of the sorbent was found to be 38.8, 52.9 and 55.5 mg g(-1) for Cr(III), Hg(II) and Pb(II), respectively. 2.0 mL of 2% thiourea in 1.0 M HCl solution effectively eluted the adsorbed metal ions. The detection limit (3σ) of this method defined by IUPAC was found to be 0.12, 0.09 and 0.23 ng mL(-1) for Cr(III), Hg(II) and Pb(II), respectively. The relative standard deviation (RSD) was lower 3.0% (n=8). The developed method has been validated by analyzing certified reference materials and successfully applied to the determination of trace Cr(III), Hg(II) and Pb(II) in water samples with satisfactory results.

  12. Estimation of mercury speciation in soil standard reference materials with different extraction methods by ion chromatography coupled with ICP-MS.

    Science.gov (United States)

    Park, Misun; Yoon, Hyeon; Yoon, Cheolho; Yu, Jae-Young

    2011-01-01

    Analytical methods for the speciation of mercury, based on microwave extraction and sonication extraction, have been tested to determine the inorganic mercury and methyl mercury contents in two standard soil reference materials: SRM 2710 Montana Soil and BCR 580 estuarine sediment. Prior to applying the speciation extraction methods, the mineral compositions were analyzed via XRD analysis, with SRM 2710 shown to be composed mostly of aluminum silicate minerals, while carbonate minerals were the major constituent in BCR 580. Two extraction methods, microwave and sonication, were tested for the analysis and recovery efficiency of total mercury. The accuracy and efficiency of each extraction method was also compared. In the analysis of total mercury, the microwave extraction method, with using methanol and HCl as extractants, was better for SRM2710, while the application of the sonication extraction method was more efficient for the calcite-based BCR 580. The results showed good separation and recovery efficiencies, with values reaching 100% of those estimated. The sonication method was selected for the speciation of mercury, especially in BCR 580. An extraction solution comprising of a 1:1 mixture of methanol and HCl was used for the sonication extraction of BCR 580, with the resulting extractants analyzed by IC-HG-ICP-MS for methyl mercury and inorganic mercury. As a simple, rapid, sensitive, and accurate method, sonication extraction was found to be satisfactory.

  13. Hydraulic Models for the Accumulation of Mercury-Contaminated Fine-Grained Sediment in Forested and Non-Forested Near-Bank Regions of the South River, Virginia, 1930-2007

    Science.gov (United States)

    Pizzuto, J. E.; Skalak, K.

    2010-12-01

    Mercury was released into the South River from a textile manufacturing facility in Waynesboro, Virginia, beginning in 1930. Because mercury strongly adsorbs to fine particles, it is a useful tracer for fine-grained sediment transport processes. Mercury concentrations were measured on sediment samples from 29 cores taken from near-bank environments up to 14 km downstream from the textile plant. Mercury concentrations average around 20 ppm, with a maximum of 839 ppm and a minimum of mercury in each core ranged from 0.0008 to 0.2 kg/m^2. These data were used to calibrate simple hydraulic models of mercury accumulation at each coring site since 1930. Previous studies document the concentration of mercury on suspended sediment through time, allowing our models to estimate the history of mercury accumulation and to infer rates of sedimentation. Rating curves for each coring site were computed based on Total Station surveys of channel morphology and flow records interpolated between 3 U.S. Geological Survey gauging stations. Hydraulic roughness parameters were obtained from a HEC-RAS model calibrated to measured stage-discharge relationships. The calibrated mercury accumulation model explains 69% of the variability in the observed mercury inventories. At forested sites, each inundation event deposited an average of 0.00065 kg of mercury, while deposition at non-forested sites (mostly in pasture), averaged 0.00009 kg of mercury per event, lower by a factor of 7. At 6 sites where lateral migration increased accommodation space, mercury deposition was increased by an order of magnitude. If particle-associated mercury accumulation is assumed to result only from reduced basal shear stresses, critical shear stresses for deposition are unreasonably low, which suggests that a significant amount of the observed inventory of mercury-contaminated sediment accumulates on plant stems and leaves, rather than only being deposited on the ground. 58% of the total mercury inventory

  14. 3-D Modeling of Bromine Chemistry and Its Impacts on Ozone and Mercury in the Arctic Boundary Layer

    Science.gov (United States)

    Toyota, K.; Ryzhkov, A.; Dastoor, A.; Stroud, C.; Chen, J.; Zhang, J.; Lupu, A.; Savic-Jovcic, V.; Zheng, Q.; Moran, M. D.; McLinden, C. A.

    2016-12-01

    Gas-phase bromine radical chemistry is the main driver for the frequent and concurrent depletion of ozone and mercury (Hg) from surface air in polar regions during the spring. Sea ice and its overlying snow cover are broadly understood as the key elements in the production of reactive bromine in polar spring. However, a full characterization remains on how physicochemical states of snow and ice influence the release of bromine into the atmosphere. Uncertainties in the kinetics and reaction mechanisms of Hg redox chemistry add further complexity to an accurate assessment of the behavior of Hg during its depletion from air. Three-dimensional (3-D) models have been developed to simulate the impact of bromine chemistry on Hg oxidation at both global and arctic-basin regional scales. However, thus far, such models have relied upon simplified and indirect representations of the release of gaseous bromine from snow/ice, its photochemical transformation to radical species and eventual deposition from the polar atmosphere. Within Environment and Climate Change Canada's operational air-quality model, GEM-MACH, we have developed a process-oriented representation for the coupled bromine-ozone-mercury chemistry and the exchange of bromine, ozone and mercury species between air and snow/ice surface. The model is run at 15-km horizontal resolution in a limited-area domain of the Arctic and is capable of capturing the evolution of high BrO columns associated with synoptic weather disturbances during polar sunrise as can be seen from satellite. The concurrent depletion of ozone and Hg is simulated by consistent model formulations, where the release of reactive bromine from the frozen surfaces is facilitated by the presence of ozone in air. We will show and discuss the impact of using our process-oriented representation of bromine and Hg chemistry on the spatial and temporal patterns of deposition of oxidized Hg during depletion events and as seasonal averages.

  15. ELECTROSTATIC ION THRUSTERS - TOWARDS PREDICTIVE MODELING

    Directory of Open Access Journals (Sweden)

    Julia Duras

    2015-02-01

    Full Text Available For satellite missions, thrusters have to be qualified in large vacuum vessels to simulate space environment. One caveat of these experiments is the possible  modification of the beam properties due to the interaction of the energetic ions with the  vessel walls. Impinging ions can produce sputtered impurities or secondary  electrons from the wall. These can stream back into the acceleration channel of the  thruster and produce co-deposited layers. Over the long operation time of thousands  of hours, such layers can modify the optimized geometry and induce changes of the ion beam properties, e.g. broadening of the angular distribution and thrust reduction. To study such effects, a Monte Carlo code for the simulation of the interaction of ion thruster beams with vessel  walls was developed. Strategies to overcome sputter limitations by additional baffles are  studied with the help of this Monte-Carlo erosion code.

  16. Modified Dietary Fiber from Cassava Pulp and Assessment of Mercury Bioaccessibility and Intestinal Uptake Using an In Vitro Digestion/Caco-2 Model System.

    Science.gov (United States)

    Kachenpukdee, Natta; Santerre, Charles R; Ferruzzi, Mario G; Oonsivilai, Ratchadaporn

    2016-07-01

    The ability of modified dietary fiber (MDF) generated from cassava pulp to modulate the bioaccessibility and intestinal absorption of heavy metals may be helpful to mitigate health risk associated with select foods including select fish high in methyl mercury. Using a coupled in vitro digestion/Caco-2 human intestinal cell model, the reduction of fish mercury bioaccessibility and intestinal uptake by MDF was investiaged. MDF was prepared from cassava pulp, a byproduct of tapioca production. The highest yield (79.68%) of MDF was obtained by enzymatic digestion with 0.1% α-amylase (w/v), 0.1% amyloglucosidase (v/v) and 1% neutrase (v/v). MDF and fish tissue were subjected to in vitro digestion and results suggest that MDF may reduce mercury bioaccessibility from fish to 34% to 85% compared to control in a dose-dependent manner. Additionally, accumulation of mercury from digesta containing fish and MDF was only modestly impacted by the presence of MDF. In conclusion, MDF prepared from cassava pulp may be useful as an ingredient to reduce mercury bioavailability from food such as fish specifically by inhibiting mercury transfer to the bioaccessibile fraction during digestion. © 2016 Institute of Food Technologists®

  17. Use of adsorption process to remove organic mercury thimerosal from industrial process wastewater.

    Science.gov (United States)

    Velicu, Magdalena; Fu, Hongxiang; Suri, Rominder P S; Woods, Kevin

    2007-09-30

    Carbon adsorption process is tested for removal of high concentration of organic mercury (thimerosal) from industrial process wastewater, in batch and continuously flow through column systems. The organic mercury concentration in the process wastewater is about 1123 mg/L due to the thimerosal compound. Four commercially available adsorbents are tested for mercury removal and they are: Calgon F-400 granular activated carbon (GAC), CB II GAC, Mersorb GAC and an ion-exchange resin Amberlite GT73. The adsorption capacity of each adsorbent is described by the Freundlich isotherm model at pH 3.0, 9.5 and 11.0 in batch isotherm experiments. Acidic pH was favorable for thimerosal adsorption onto the GACs. Columns-in-series experiments are conducted with 30-180 min empty bed contact times (EBCTs). Mercury breakthrough of 30 mg/L occurred after about 47 h (96 Bed Volume Fed (BVF)) of operation, and 97 h (197 BVF) with 120 min EBCT and 180 min EBCT, respectively. Most of the mercury removal is attributed to the 1st adsorbent column. Increase in contact time by additional adsorbent columns did not lower the effluent mercury concentration below 30 mg/L. However, at a lower influent wastewater pH 3, the mercury effluent concentration decreased to less than 7 mg/L for up to 90 h of column operation (183 BVF).

  18. Photochemical reactions of divalent mercury with thioglycolic acid: formation of mercuric sulfide particles.

    Science.gov (United States)

    Si, Lin; Ariya, Parisa A

    2015-01-01

    Mercury (Hg) is a key toxic global pollutant. Studies in aquatic environment have suggested that thiols could be important for mercury speciation. Thioglycolic acid has been detected in various natural water systems and used as a model compound to study the complicated interaction between mercury and polyfunctional dissolved organic matter (DOM). We herein presented the first evidence for mercury particle formation during kinetic and product studies on the photochemistry of divalent mercury (Hg(2+)) with thioglycolic acid at near environmental conditions. Mercuric sulfide (HgS) particles formed upon photolysis were identified by high-resolution transmission electron microscopy coupled with energy dispersive spectrometry and select area electron diffraction. Kinetic data were obtained using UV-visible spectrophotometry and cold vapour atomic fluorescent spectrometry. The apparent first-order reaction rate constant under our experimental conditions was calculated to be (2.3±0.4)×10(-5) s(-1) at T=296±2 K and pH 4.0. It was found that (89±3)% of the reactants undergo photoreduction to generate elemental mercury (Hg(0)). The effects of ionic strengths, pH and potassium ion were also investigated. The formation of HgS particles pointed to the possible involvement of heterogeneous processes. Our kinetic results indicated the importance of weak binding sites on DOM to Hg in photoreduction of Hg(2+) to Hg(0). The potential implications of our data on environmental mercury transformation were discussed.

  19. A study on the adsorption mechanism of mercury on Aspergillus versicolor biomass.

    Science.gov (United States)

    Das, Sujoy K; Das, Akhil R; Guha, Arun K

    2007-12-15

    The adsorption behavior of mercury on Aspergillus versicolor biomass (AVB) has been investigated in aqueous solution to understand the physicochemical process involved and to explore the potentiality of AVB in pollution control management. This biomass has been successfully used for reducing the mercury concentration level in the effluent of chloralkali and battery industries to a permissible limit. The results establish that 75.6 mg of mercury is adsorbed per gram of biomass. The adsorption process is found to be a function of pH of the solution, with the optimum range being pH 5.0-6.0. The process obeys the Langmuir-Freundlich isotherm model. Scanning electron microscopic analysis demonstrates a conspicuous surface morphology change of the mercury-adsorbed biomass. A nearly uniform distribution of metal ions on the mycelial surface excepting a few aggregation points is revealed by X-ray elemental mapping profiles. The results of zeta potential measurement, Fourier transform infrared (FTIR) spectroscopy, and blocking of the functional groups by chemical modification reflect the binding of mercury on the biomass occurs through electrostatic and complexation reactions. The accumulation of mercury on the cell wall associated with negligible diffusion and or transportation into cytoplasm finds support from the results of adsorption kinetics and transmission electron micrographs. Mercury adsorption on biomass also leads to elongation of cells and cytoplasmic aggregation of spheroplast/protoplasts, indicating that the cell wall acts as a permeation barrier against this toxic metal.

  20. A new, catchment-scale model for simulating methyl and total mercury in soils and surface waters

    Science.gov (United States)

    Futter, M. N.; Poste, A. E.; Whitehead, P. G.; Dillon, P. J.

    2012-04-01

    Mercury (Hg) is a potent and persistent neurotoxin. It is subject to long-range atmospheric transport, accumulates in catchment soils, and can pose health risks to humans and animals both at the point of use as well as in remote locations. Elevated concentrations of methyl mercury (MeHg) in fish are related to atmospheric Hg deposition and have resulted in fish consumption advisories in many parts of North America and Fennoscandia. After more than 150 years of elevated Hg deposition in Europe and North America, there remains a large inventory of Hg in the terrestrial catchments of lakes, which continues to be exported to receiving waters despite decreasing atmospheric inputs. While a substantial Hg pool exists in boreal catchment soils, fluxes of Hg from catchments via stream runoff tend to be much lower than atmospheric Hg inputs. Terrestrial catchments receiving similar atmospheric Hg inputs can have markedly different patterns of Hg output in stream water. Considering the importance of catchment processes in determining Hg flux to lakes and subsequent MeHg concentrations in fish, there is a need to characterize Hg cycling and transport in boreal and temperate forest-covered catchments. We present a new, catchment-scale, process-based dynamic model for simulating Hg in soils and surface waters. The Integrated Catchments Model for Mercury (INCA-Hg) simulates transport of gaseous, dissolved and solid Hg and transformations between elemental (Hg0), ionic (Hg(II)) and MeHg in natural and semi-natural landscapes. The mathematical description represents the model as a series of linked, first-order differential equations describing chemical and hydrological processes in catchment soils and waters which control surface water Hg dynamics and subsequent fluxes to lakes and other receiving waters. The model simulates daily time series between one and one hundred years long and can be applied to catchments ranging in size from Canada where we were able to reproduce observed

  1. Modeling radial flow ion exchange performance for condensate polisher conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shallcross, D. [University of Melbourne, Melbourne, VIC (Australia). Department of Chemical Engineering; Renouf, P.

    2001-11-01

    A theoretical model is developed which simulates ion exchange performance within an annular resin bed. Flow within the mixed ion exchange bed is diverging, with the solution flowing outwards away from the bed's axis. The model is used to simulate performance of a mixed annular bed operating under condensate polisher conditions. The simulation predictions are used to develop design envelope curves for practical radial flow beds and to estimate potential cost savings flowing from less expensive polisher vessels. (orig.)

  2. 离子交换法回收PVC含汞废盐酸的试验研究%Experimental research on ion-exchange method to recover mercury-containing waste acid from production of PVC

    Institute of Scientific and Technical Information of China (English)

    张桂香

    2012-01-01

    研究了采用离子交换法处理含汞废盐酸中汞的工艺技术,实现了含汞废盐酸的回收利用,并从树脂类型、树脂再生、再生液处理3个方面进行了全过程工艺条件考察。%The technologies of removing mercury from mercury-containing waste hydrochloric acid by ion-exchange method were studied. The whole process conditions were investigated in three aspects, i.e. resin type, resin regeneration and regenerated liquid treatment.

  3. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2004-12-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems.

  4. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2004-12-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems.

  5. DNA derived fluorescent bio-dots for sensitive detection of mercury and silver ions in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ting [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Xuefeng, E-mail: zhuxf@ms.xjb.ac.cn [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Zhou, Shenghai [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Yang, Guang [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049 (China); Gan, Wei [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Yuan, Qunhui, E-mail: yuanqh@ms.xjb.ac.cn [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China)

    2015-08-30

    Highlights: • First application of a DNA derived fluorescent bio-dot for metal sensing. • Bio-dot was conveniently obtained via a mild thermal hydro-thermal synthesis. • Bio-dot was directly used for fluorescent sensing without further modification. • Bio-dot showed good fluorescent sensing property for Hg(II) and Ag(I). • Formation of T–Hg–T and C–Ag–C structures played key roles in sensing. - Abstract: Inspired by the high affinity between heavy metal ions and bio-molecules as well as the low toxicity of carbon-based quantum dots, we demonstrated the first application of a DNA derived carbonaceous quantum dots, namely bio-dots, in metal ion sensing. The present DNA-derived bio-dots contain graphitic carbon layers with 0.242 nm lattice fringes, exhibit excellent fluorescence property and can be obtained via a facile hydrothermal preparation procedure. Hg(II) and Ag(I) are prone to be captured by the bio-dots due to the existence of residual thymine (T) and cytosine (C) groups, resulting in a quenched fluorescence while other heavy metal ions would cause negligible changes on the fluorescent signals of the bio-dots. The bio-dots could be used as highly selective toxic-free biosensors, with two detecting linear ranges of 0–0.5 μM and 0.5–6 μM for Hg(II) and one linear range of 0–10 μM for Ag(I). The detection limits (at a signal-to-noise ratio of 3) were estimated to be 48 nM for Hg(II) and 0.31 μM for Ag(I), respectively. The detection of Hg(II) and Ag(I) could also be realized in the real water sample analyses, with satisfying recoveries ranging from 87% to 100%.

  6. Particulate-phase mercury emissions from biomass burning and impact on resulting deposition: a modelling assessment

    Science.gov (United States)

    Mercury (Hg) emissions from biomass burning (BB) are an important source of atmospheric Hg and a major factor driving the interannual variation of Hg concentrations in the troposphere. The greatest fraction of Hg from BB is released in the form of elemental Hg (Hg0(g)). However, ...

  7. Synthesis of C-glycosyl triazolyl quinoline-based fluorescent sensors for the detection of mercury ions.

    Science.gov (United States)

    Wang, Linfang; Jin, Jianzhong; Zhao, Linwei; Shen, Hongyun; Shen, Chao; Zhang, Pengfei

    2016-10-01

    A series of novel C-glycosyl triazolyl quinoline-based fluorescent sensors have been synthesized via click chemistry. It was found that novel sensors exhibited good selectivity for Hg(2+) over many other metal ions. The glucose framework was introduced to increase the water-solubility of the fluorescent sensors and broaden its application for the detection of Hg(II) in the water-solubility biological systems. The mechanism of the chemodosimetric behavior of the sensors has been attributed to a binding mode of triazolyl quinoline with Hg(2+) which has been characterized by a number of spectroscopic techniques.

  8. Synthesis of Activated Carbon Mesoporous from Coffee Waste and Its Application in Adsorption Zinc and Mercury Ions from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Liliana Giraldo

    2012-01-01

    Full Text Available We obtain activated carbons with high portion of meso pores using coffee residues as precursor for the application of adsorption of large adsorbates. Because of its natural properties, the coffee residue exhibited a large pore size. In this work, the coffee residue were impregnated with ZnCl2 and KOH, and then carbonized under the nitrogen conditions and activated with CO2 respectively. Obtained activated carbons are used in the adsorption of ions Hg(II and Zn(II. These adsorbents are efficacious to remove these ions from aqueous solution, with monocomponent equilibrium adsorption capacities ranging from from 0.002 to 0.380 mmol∙g-1 for Hg on ACK3 and from 0.002 to 0.330 mmol∙g-1 for ACZ3. For Zn(II on ACK2 from 0.002 to 0.300 mmol∙g-1, and from 0.001 to 0.274 mmol∙g-1 for ACZ2.

  9. Fate and transport of mercury in soil systems : a numerical model in HP1 and sensitivity analysis

    Science.gov (United States)

    Leterme, Bertrand; Jacques, Diederik

    2013-04-01

    Mercury (Hg) poses threats for human health and the environment, notably due to its persistence and its ability to bioaccumulate in ecosystems. Anthropogenic activities are major contributors of mercury release to soils. Main sources of contamination include manufacturing (chlor-alkali plants, manometer spill), mine tailings from mercury, gold and silver mining industries, wood preservation. The objective of this study was to develop a reactive transport model for simulating mercury fate and transport in the unsaturated zone, and to gain insight in the fate and transport of Hg following anthropogenic soil contamination. The present work is done in the framework of the IMaHg project, which aims at providing recommendations to improve management of sites contaminated by mercury within the SNOWMAN funding framework. A model of mercury fate and transport in soil systems was developed using the reactive transport code HP1 (Jacques and Šimůnek, 2010). The geochemical database THERMODDEM (Blanc et al., 2012) is used, augmented with some speciation data from (Skyllberg, 2012). The main processes accounted for in the model are : Hg aqueous speciation (including complexation with dissolved organic matter (DOM) - humic and fulvic acids, and thiol groups), Hg sorption to solid organic matter (SOM), dissolution of solid phase Hg (e.g. cinnabar HgS(s)), dissolution of Hg non-aqueous liquid phase (NAPL), sunlight-driven Hg(II) reduction to Hg(0), Hg(0) diffusion in the gas phase and volatilization, DOM sorption to soil minerals. Colloid facilitated transport is implicitly accounted for by solute transport of Hg-DOM complexes. Because we focused on soil systems having a high Hg contamination, some processes showing relatively smaller Hg fluxes could be neglected such as vegetation uptake and atmospheric wet and dry deposition. NAPL migration and entrapment is not modelled, as pollution is assumed to be historical and only residual NAPL to be present. Mercury methylation and

  10. Studying non-linearity of Mercury magnetosphere and solar wind interaction features using the combined hybrid model

    Science.gov (United States)

    Parunakian, David; Dyadechkin, Sergey; Alexeev, Igor; Belenkaya, Elena; Khodachenko, Maxim; Kallio, Esa; Alho, Markku

    2017-04-01

    The main focus of this work is to investigate non-linearity of Mercury's magnetospheric features. We use the paraboloid magnetospheric model (PMM) to calculate the initial magnetospheric field which we then use in hybrid simulations. We show that the initial total magnetospheric field can be considered a linear combination of the planetary dipole field, magnetospheric current system fields, and a penetrating portion of the interplanetary magnetic field (IMF). We use two sets of modelling runs with IMF values of identical magnitudes and anti-parallel directions. We then compute semi-sums and semi-differences of final magnetic field maps generated by hybrid plasma simulations, and use semi-sums to cancel out IMF contributions and semi-differences to cancel out PMM contributions. The remnant fields outside and inside the magnetosphere (for semi-sum and semi-difference fields, accordingly) are used to improve our ability to determine the position of the bow shock and magnetopause, as well as calculate the IMF penetration coefficient that results into best matches of this model to observational MESSENGER data. We compare Mercury's magnetosheath magnetic field predicted by our model with MESSENGER data in the appropriate orbit sections.

  11. Sorption equilibrium of mercury onto ground-up tree fern

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Y.-S. [Department of Chemical Engineering, I-Shou University, No. 1, Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung County 840, Taiwan (China)], E-mail: ysho@isu.edu.tw; Wang, C.-C. [Department of Chemical Engineering, I-Shou University, No. 1, Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung County 840, Taiwan (China)

    2008-08-15

    The sorption behavior of mercury at different temperatures onto ground-up tree fern was investigated. The experimental results were fitted to two two-parameter isotherms, the Freundlich and Langmuir isotherms, as well as to two three-parameter isotherms, the Redlich-Peterson and Sips isotherms to obtain the characteristic parameters of each model. A comparison of best-fitting was performed using the coefficient of determination and Chi-square test. Both the Langmuir and Redlich-Peterson isotherms were found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the saturated monolayer sorption capacity of mercury ions onto ground-up tree fern was 26.5 mg/g at 298 K. It was noted that an increase in temperature resulted in a higher mercury ion loading per unit weight of the tree fern. In addition, various thermodynamic parameters, such as {delta}G{sup o}, {delta}H{sup o}, and {delta}S{sup o}, were calculated and compared with the sorption of mercury by other sorbents.

  12. Got Mercury?

    Science.gov (United States)

    Meyers, Valerie; James, John T.; McCoy, Torin; Garcia, Hector

    2010-01-01

    Many lamps used in various spacecraft contain elemental mercury, which is efficiently absorbed through the lungs as a vapor. The liquid metal vaporizes slowly at room temperature, but may be completely vaporized when lamps are operating. Because current spacecraft environmental control systems are unable to remove mercury vapors, we considered short-term and long-term exposures. Using an existing study, we estimated mercury vapor releases from lamps that are not in operation during missions lasting less than or equal to 30 days; whereas we conservatively assumed complete vaporization from lamps that are operating or being used during missions lasing more than 30 days. Based on mercury toxicity, the Johnson Space Center's Toxicology Group recommends stringent safety controls and verifications for any hardware containing elemental mercury that could yield airborne mercury vapor concentrations greater than 0.1 mg/m3 in the total spacecraft atmosphere for exposures lasting less than or equal to 30 days, or concentrations greater than 0.01 mg/m3 for exposures lasting more than 30 days.

  13. One-pot electrochemical synthesis of functionalized fluorescent carbon dots and their selective sensing for mercury ion.

    Science.gov (United States)

    Hou, Yuxin; Lu, Qiujun; Deng, Jianhui; Li, Haitao; Zhang, Youyu

    2015-03-25

    We propose a simple, economical, and one-pot method to synthesize water-soluble functionalized fluorescent carbon dots (C-Dots) through electrochemical carbonization of sodium citrate and urea. The as-prepared C-Dots have good photostability and exhibit a high quantum yield of 11.9%. The sizes of the C-Dots are mainly distributed in the range of 1.0-3.5 nm with an average size of 2.4 nm. It has been further used as a novel label-free sensing probe for selective detection of Hg(2+) ions with detection limit as low as 3.3 nM. The detection linear range is 0.01-10 μM. The as-prepared C-Dots are also successfully applied for the determination of Hg(2+) in real water samples.

  14. Poisson-Fermi Model of Single Ion Activities

    CERN Document Server

    Liu, Jinn-Liang

    2015-01-01

    A Poisson-Fermi model is proposed for calculating activity coefficients of single ions in strong electrolyte solutions based on the experimental Born radii and hydration shells of ions in aqueous solutions. The steric effect of water molecules and interstitial voids in the first and second hydration shells play an important role in our model. The screening and polarization effects of water are also included in the model that can thus describe spatial variations of dielectric permittivity, water density, void volume, and ionic concentration. The activity coefficients obtained by the Poisson-Fermi model with only one adjustable parameter are shown to agree with experimental data, which vary nonmonotonically with salt concentrations.

  15. Electron impact ionization of tungsten ions in a statistical model

    Science.gov (United States)

    Demura, A. V.; Kadomtsev, M. B.; Lisitsa, V. S.; Shurygin, V. A.

    2015-01-01

    The statistical model for calculations of the electron impact ionization cross sections of multielectron ions is developed for the first time. The model is based on the idea of collective excitations of atomic electrons with the local plasma frequency, while the Thomas-Fermi model is used for atomic electrons density distribution. The electron impact ionization cross sections and related ionization rates of tungsten ions from W+ up to W63+ are calculated and then compared with the vast collection of modern experimental and modeling results. The reasonable correspondence between experimental and theoretical data demonstrates the universal nature of statistical approach to the description of atomic processes in multielectron systems.

  16. Particulate-phase mercury emissions from biomass burning and impact on resulting deposition: a modelling assessment

    Science.gov (United States)

    De Simone, Francesco; Artaxo, Paulo; Bencardino, Mariantonia; Cinnirella, Sergio; Carbone, Francesco; D'Amore, Francesco; Dommergue, Aurélien; Feng, Xin Bin; Gencarelli, Christian N.; Hedgecock, Ian M.; Landis, Matthew S.; Sprovieri, Francesca; Suzuki, Noriuki; Wängberg, Ingvar; Pirrone, Nicola

    2017-02-01

    Mercury (Hg) emissions from biomass burning (BB) are an important source of atmospheric Hg and a major factor driving the interannual variation of Hg concentrations in the troposphere. The greatest fraction of Hg from BB is released in the form of elemental Hg (Hg0(g)). However, little is known about the fraction of Hg bound to particulate matter (HgP) released from BB, and the factors controlling this fraction are also uncertain. In light of the aims of the Minamata Convention to reduce intentional Hg use and emissions from anthropogenic activities, the relative importance of Hg emissions from BB will have an increasing impact on Hg deposition fluxes. Hg speciation is one of the most important factors determining the redistribution of Hg in the atmosphere and the geographical distribution of Hg deposition. Using the latest version of the Global Fire Emissions Database (GFEDv4.1s) and the global Hg chemistry transport model, ECHMERIT, the impact of Hg speciation in BB emissions, and the factors which influence speciation, on Hg deposition have been investigated for the year 2013. The role of other uncertainties related to physical and chemical atmospheric processes involving Hg and the influence of model parametrisations were also investigated, since their interactions with Hg speciation are complex. The comparison with atmospheric HgP concentrations observed at two remote sites, Amsterdam Island (AMD) and Manaus (MAN), in the Amazon showed a significant improvement when considering a fraction of HgP from BB. The set of sensitivity runs also showed how the quantity and geographical distribution of HgP emitted from BB has a limited impact on a global scale, although the inclusion of increasing fractions HgP does limit Hg0(g) availability to the global atmospheric pool. This reduces the fraction of Hg from BB which deposits to the world's oceans from 71 to 62 %. The impact locally is, however, significant on northern boreal and tropical forests, where fires are

  17. Generalized Manning Condensation Model Captures the RNA Ion Atmosphere

    Science.gov (United States)

    Hayes, Ryan L.; Noel, Jeffrey K.; Mandic, Ana; Whitford, Paul C.; Sanbonmatsu, Karissa Y.; Mohanty, Udayan; Onuchic, José N.

    2016-01-01

    RNA is highly sensitive to the ionic environment, and typically requires Mg2+ to form compact structures. There is a need for models capable of describing the ion atmosphere surrounding RNA with quantitative accuracy. We present a model of RNA electrostatics and apply it within coarse-grained molecular dynamics simulation. The model treats Mg2+ ions explicitly to account for ion-ion correlations neglected by mean field theories. Since mean-field theories capture KCl well, it is treated implicitly by a generalized Manning counterion condensation model. The model extends Manning condensation to deal with arbitrary RNA conformations, non-limiting KCl concentrations, and the ion inaccessible volume of RNA. The model is tested against experimental measurements of the excess Mg2+ associated with the RNA, Γ2+, because Γ2+ is directly related to the Mg2+-RNA interaction free energy. The excellent agreement with experiment demonstrates the model captures the ionic dependence of the RNA free energy landscape. PMID:26197147

  18. MODELING THE IMPACT OF ELEVATED MERCURY IN DEFENSE WASTE PROCESSING FACILITY MELTER FEED ON THE MELTER OFF-GAS SYSTEM-PRELIMINARY REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zamecnik, J.; Choi, A.

    2010-08-18

    The Defense Waste Processing Facility (DWPF) is currently evaluating an alternative Chemical Process Cell (CPC) flowsheet to increase throughput. It includes removal of the steam-stripping step, which would significantly reduce the CPC processing time and lessen the sampling needs. However, its downside would be to send 100% of the mercury that comes in with the sludge straight to the melter. For example, the new mercury content in the Sludge Batch 5 (SB5) melter feed is projected to be 25 times higher than that in the SB4 with nominal steam stripping of mercury. This task was initiated to study the impact of the worst-case scenario of zero-mercury-removal in the CPC on the DWPF melter offgas system. It is stressed that this study is intended to be scoping in nature, so the results presented in this report are preliminary. In order to study the impact of elevated mercury levels in the feed, it is necessary to be able to predict how mercury would speciate in the melter exhaust under varying melter operating conditions. A homogeneous gas-phase oxidation model of mercury by chloride was developed to do just that. The model contains two critical parameters pertaining to the partitioning of chloride among HCl, Cl, Cl{sub 2}, and chloride salts in the melter vapor space. The values for these parameters were determined at two different melter vapor space temperatures by matching the calculated molar ratio of HgCl (or Hg{sub 2}Cl{sub 2}) to HgCl{sub 2} with those measured during the Experimental-Scale Ceramic Melter (ESCM) tests run at the Pacific Northwest National Laboratory (PNNL). The calibrated model was then applied to the SB5 simulant used in the earlier flowsheet study with an assumed mercury stripping efficiency of zero; the molar ratio of Cl-to-Hg in the resulting melter feed was only 0.4, compared to 12 for the ESCM feeds. The results of the model run at the indicated melter vapor space temperature of 650 C (TI4085D) showed that due to excessive shortage of

  19. MODELING THE IMPACT OF ELEVATED MERCURY IN DEFENSE WASTE PROCESSING FACILITY MELTER FEED ON THE MELTER OFF-GAS SYSTEM - PRELIMINARY REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zamecnik, J.; Choi, A.

    2009-03-25

    The Defense Waste Processing Facility (DWPF) is currently evaluating an alternative Chemical Process Cell (CPC) flowsheet to increase throughput. It includes removal of the steam-stripping step, which would significantly reduce the CPC processing time and lessen the sampling needs. However, its downside would be to send 100% of the mercury that come in with the sludge straight to the melter. For example, the new mercury content in the Sludge Batch 5 (SB5) melter feed is projected to be 25 times higher than that in the SB4 with nominal steam stripping of mercury. This task was initiated to study the impact of the worst-case scenario of zero-mercury-removal in the CPC on the DWPF melter off-gas system. It is stressed that this study is intended to be scoping in nature, so the results presented in this report are preliminary. In order to study the impact of elevated mercury levels in the feed, it is necessary to be able to predict how mercury would speciate in the melter exhaust under varying melter operating conditions. A homogeneous gas-phase oxidation model of mercury by chloride was developed to do just that. The model contains two critical parameters pertaining to the partitioning of chloride among HCl, Cl, Cl{sub 2}, and chloride salts in the melter vapor space. The values for these parameters were determined at two different melter vapor space temperatures by matching the calculated molar ratio of HgCl (or Hg{sub 2}Cl{sub 2}) to HgCl{sub 2} with those measured during the Experimental-Scale Ceramic Melter (ESCM) tests run at the Pacific Northwest National Laboratory (PNNL). The calibrated model was then applied to the SB5 simulant used in the earlier flowsheet study with an assumed mercury stripping efficiency of zero; the molar ratio of Cl-to-Hg in the resulting melter feed was only 0.4, compared to 12 for the ESCM feeds. The results of the model run at the indicated melter vapor space temperature of 650 C (TI4085D) showed that due to excessive shortage of

  20. Mercury in the pelagic food web of Lake Champlain.

    Science.gov (United States)

    Miller, Eric K; Chen, Celia; Kamman, Neil; Shanley, James; Chalmers, Ann; Jackson, Brian; Taylor, Vivien; Smeltzer, Eric; Stangel, Pete; Shambaugh, Angela

    2012-04-01

    Lake Champlain continues to experience mercury contamination resulting in public advisories to limit human consumption of top trophic level fish such as walleye. Prior research suggested that mercury levels in biota could be modified by differences in ecosystem productivity as well as mercury loadings. We investigated relationships between mercury in different trophic levels in Lake Champlain. We measured inorganic and methyl mercury in water, seston, and two size fractions of zooplankton from 13 sites representing a range of nutrient loading conditions and productivity. Biomass varied significantly across lake segments in all measured ecosystem compartments in response to significant differences in nutrient levels. Local environmental factors such as alkalinity influenced the partitioning of mercury between water and seston. Mercury incorporation into biota was influenced by the biomass and mercury content of different ecosystem strata. Pelagic fish tissue mercury was a function of fish length and the size of the mercury pool associated with large zooplankton. We used these observations to parameterize a model of mercury transfers in the Lake Champlain food web that accounts for ecosystem productivity effects. Simulations using the mercury trophic transfer model suggest that reductions of 25-75% in summertime dissolved eplimnetic total mercury will likely allow fish tissue mercury concentrations to drop to the target level of 0.3 μg g(-1) in a 40-cm fish in all lake segments. Changes in nutrient loading and ecosystem productivity in eutrophic segments may delay any response to reduced dissolved mercury and may result in increases in fish tissue mercury.

  1. Removal of Mercury from chlor-alkali Industry Wastewater using Acetobacter xylinum Cellulose

    Directory of Open Access Journals (Sweden)

    A. Rezaee

    2005-01-01

    Full Text Available In this study, the removal of mercury ions by cellulose of Acetobacter xylinum was investigated in the synthetic and chlor-alkali wastewater. Biofilms of Acetobacter xylinum were grown in laboratory column bioreactors. The biofilms were continuously treated with sterile synthetic model wastewater or nonsterile, neutralized chloralkali wastewater.The extent of adsorption was studied as function of pH, adsorbent dose and contact time. Efficiency of mercury ion removal from chlor-alkali industry wastewater by aluminum sulfate and ferric chloride was also determined. Under acidic condition the adsorption of mercury by cellulose was quite low and increasing processing time more than 10min has no remarkably effect on the adsorption rate. Adsorption capacity of cellulose under dynamic condition for chlor-alkali wastewater was 65mg/µg which was less than the value (80mg/µg that obtained from batch adsorption experiments for synthetic wastewater.

  2. Trapped ions in optical lattices for probing oscillator chain models

    CERN Document Server

    Pruttivarasin, Thaned; Talukdar, Ishan; Kreuter, Axel; Haeffner, Hartmut

    2011-01-01

    We show that a chain of trapped ions embedded in microtraps generated by an optical lattice can be used to study oscillator models related to dry friction and energy transport. Numerical calculations with realistic experimental parameters demonstrate that both static and dynamic properties of the ion chain change significantly as the optical lattice power is varied. Finally, we lay out an experimental scheme to use the spin degree of freedom to probe the phase space structure and quantum critical behavior of the ion chain.

  3. Mercury migration into ground water, a literature study

    Energy Technology Data Exchange (ETDEWEB)

    Carlton, W.H.; Carden, J.L.; Kury, R.; Eichholz, G.G.

    1994-11-01

    This report presents a broad review of the technical literature dealing with mercury migration in the soil. The approach followed was to identify relevant articles by searching bibliographic data bases, obtaining the promising articles and searching these articles for any additional relevant citations. Eight catagories were used to organize the literature, with a review and summary of each paper. Catagories used were the following: chemical states of mercury under environmental conditions; diffusion of mercury vapor through soil; solubility and stability of mercury in environmental waters; transport of mercury on colloids; models for mercury migration through the environment; analytical techniques; retention of mercury by soil components; formation of organomecurials.

  4. Etch rate modeling for ion-irradiated nitrocellulose

    Energy Technology Data Exchange (ETDEWEB)

    Merhari, L.; Belorgeot, C.; Moliton, J.P. (Laboratoire d' electronique des Polymeres sous Faisceaux Ioniques, 123, Avenue Albert Thomas, 87060 Limoges Cedex (France))

    1990-12-24

    The self-developing mechanism of nitrocellulose when used as an ion beam resist is described by a model predicting the evolution of the etch rate versus irradiation time. Fundamentals of the model based on ion energy deposition dependent ablative development along with related mathematical derivations are given and briefly discussed. Comparison between theoretical results and experimental data available for protons at 20 keV and Ne{sup +}, Ar{sup +}, Kr{sup +} ions at 150 keV is made and shows a good agreement. This result clearly does not conflict with our assumption that the nitrocellulose etch rate is dependent on the total ion deposited energy no matter how the energy is deposited.

  5. Applications progress of desulfurization reaction in chemosensors for mercury ion%脱硫化反应在汞离子传感器中的应用进展

    Institute of Scientific and Technical Information of China (English)

    程晓红; 王松

    2015-01-01

    Because of the thiophiolic property of mercury ions,desulfurization reactions have been widely used in the design of reactive sensors for mercury ions and provide us methods of investigating mercury ions with superior selectivity. This review mainly focused on the applications of desulfurization reactions in the design of chemosensers for mercury ions,including the Hg2+-promoted desulfurization reactions of thiocarbonyl compounds,derivatives of thiourea,squaraine-based compounds,thiosemicarbazide compounds,as well as the Hg2+-promoted deprotection of dithioacetals. Several obstacles in this field include harsh reaction conditions for some chemical reactions in the design of sensors of mercury ions,slow reaction rate of some chemical reactions at room temperature;low sensitivity of some sensor systems. Therefore, optimization of the sensing conditions is needed in order to provide more opportunities in the development of reactive sensors for mercury ions.%汞离子具有独特的嗜硫性,因此脱硫化反应被广泛地应用于汞离子传感器的设计之中,并表现出超高的选择性。本文在前期研究工作的基础上,结合相关文献报道,综述了脱硫化反应在汞离子化学传感器中的应用,包括汞离子与硫代羰基化合物发生脱硫反应、汞诱导硫脲衍生物脱硫化氢生成胍类化合物的反应、汞诱导的方酸化合物脱硫醇反应、汞促进氨基硫脲转化为二唑反应以及缩硫醛化合物的脱保护反应。分析文献表明,该领域的研究目前仍存在一些尚未解决的问题:有些化学反应的反应条件较苛刻;有些化学反应在室温下反应速率较慢;一些传感体系对汞离子检测的灵敏度较低。因此,需要更好地利用化学反应,探索并优化传感条件,为反应型汞离子传感器的发展提供更多契机。

  6. Alternative modeling methods for plasma-based Rf ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Veitzer, Seth A., E-mail: veitzer@txcorp.com; Kundrapu, Madhusudhan, E-mail: madhusnk@txcorp.com; Stoltz, Peter H., E-mail: phstoltz@txcorp.com; Beckwith, Kristian R. C., E-mail: beckwith@txcorp.com [Tech-X Corporation, Boulder, Colorado 80303 (United States)

    2016-02-15

    Rf-driven ion sources for accelerators and many industrial applications benefit from detailed numerical modeling and simulation of plasma characteristics. For instance, modeling of the Spallation Neutron Source (SNS) internal antenna H{sup −} source has indicated that a large plasma velocity is induced near bends in the antenna where structural failures are often observed. This could lead to improved designs and ion source performance based on simulation and modeling. However, there are significant separations of time and spatial scales inherent to Rf-driven plasma ion sources, which makes it difficult to model ion sources with explicit, kinetic Particle-In-Cell (PIC) simulation codes. In particular, if both electron and ion motions are to be explicitly modeled, then the simulation time step must be very small, and total simulation times must be large enough to capture the evolution of the plasma ions, as well as extending over many Rf periods. Additional physics processes such as plasma chemistry and surface effects such as secondary electron emission increase the computational requirements in such a way that even fully parallel explicit PIC models cannot be used. One alternative method is to develop fluid-based codes coupled with electromagnetics in order to model ion sources. Time-domain fluid models can simulate plasma evolution, plasma chemistry, and surface physics models with reasonable computational resources by not explicitly resolving electron motions, which thereby leads to an increase in the time step. This is achieved by solving fluid motions coupled with electromagnetics using reduced-physics models, such as single-temperature magnetohydrodynamics (MHD), extended, gas dynamic, and Hall MHD, and two-fluid MHD models. We show recent results on modeling the internal antenna H{sup −} ion source for the SNS at Oak Ridge National Laboratory using the fluid plasma modeling code USim. We compare demonstrate plasma temperature equilibration in two

  7. Alternative modeling methods for plasma-based Rf ion sources

    Science.gov (United States)

    Veitzer, Seth A.; Kundrapu, Madhusudhan; Stoltz, Peter H.; Beckwith, Kristian R. C.

    2016-02-01

    Rf-driven ion sources for accelerators and many industrial applications benefit from detailed numerical modeling and simulation of plasma characteristics. For instance, modeling of the Spallation Neutron Source (SNS) internal antenna H- source has indicated that a large plasma velocity is induced near bends in the antenna where structural failures are often observed. This could lead to improved designs and ion source performance based on simulation and modeling. However, there are significant separations of time and spatial scales inherent to Rf-driven plasma ion sources, which makes it difficult to model ion sources with explicit, kinetic Particle-In-Cell (PIC) simulation codes. In particular, if both electron and ion motions are to be explicitly modeled, then the simulation time step must be very small, and total simulation times must be large enough to capture the evolution of the plasma ions, as well as extending over many Rf periods. Additional physics processes such as plasma chemistry and surface effects such as secondary electron emission increase the computational requirements in such a way that even fully parallel explicit PIC models cannot be used. One alternative method is to develop fluid-based codes coupled with electromagnetics in order to model ion sources. Time-domain fluid models can simulate plasma evolution, plasma chemistry, and surface physics models with reasonable computational resources by not explicitly resolving electron motions, which thereby leads to an increase in the time step. This is achieved by solving fluid motions coupled with electromagnetics using reduced-physics models, such as single-temperature magnetohydrodynamics (MHD), extended, gas dynamic, and Hall MHD, and two-fluid MHD models. We show recent results on modeling the internal antenna H- ion source for the SNS at Oak Ridge National Laboratory using the fluid plasma modeling code USim. We compare demonstrate plasma temperature equilibration in two-temperature MHD models

  8. Ion spectroscopy for improvement of the physical beam model for therapy planning in ion beam therapy

    Energy Technology Data Exchange (ETDEWEB)

    Arico, Giulia

    2016-11-23

    Helium and carbon ions enable a more conformal dose distribution, narrower penumbra and higher relative biological effectiveness than photon and proton radiotherapy. However, they may undergo nuclear fragmentation in the patient tissues and the arising secondary fragments affect the delivered biological dose distributions. Currently there is a lack of data regarding ion nuclear fragmentation. One reason is the large size (up to some meters) of the experimental setups required for the investigations. In this thesis a new method is presented, which makes use of versatile pixelated semiconductor detectors (Timepix). This method is based on tracking of single particles and pattern recognition of their signals in the detectors. Measurements were performed at the HIT facility. The mixed radiation field arising from 430 MeV/u carbon ion beams and 221 MeV/u helium ion beams in water and in PMMA targets was investigated. The amounts of primary (carbon or helium) ions detected behind targets with the same water equivalent thickness (WET) were found to be in agreement within the statistical uncertainties. However, more fragments (differences up to 20% in case of H) and narrower lateral particle distributions were measured behind the PMMA than the water targets. The spectra of ions behind tissue surrogates and corresponding water targets with the same WET were analysed. The results obtained with adipose and inner bone surrogates and with the equivalent water phantoms were found to be consistent within the uncertainties. Significant differences in the results were observed in the case of lung and cortical bone surrogates when compared to the water phantoms. The experimental results were compared to FLUKA Monte Carlo simulations. This comparison could contribute to enhance the ion interaction models currently implemented for {sup 12}C and {sup 4}He ion beams.

  9. Stable isotopes and mercury in a model estuarine fish: Multibasin comparisons with water quality, community structure, and available prey base

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Douglas H., E-mail: Doug.Adams@MyFWC.com; Paperno, Richard

    2012-01-01

    Stable-isotope ratios ({delta}{sup 13}C and {delta}{sup 15}N) and mercury in a model predator, and associated prey community assessments were used to make inferences regarding food web relationships and how these relationships are influenced by habitat variability and anthropogenic factors. Although interconnected, the three major basins of the Indian River Lagoon system on the Atlantic coast of Florida comprise noticeably different available habitat types with spatially distinct faunal communities and available prey for spotted seatrout, Cynoscion nebulosus, a model predatory fish species. Water quality, degree of urbanization, human population density, and levels of nitrogen enrichment clearly differ between these representative estuarine basins. The differences can influence feeding ecology and therefore result in different mercury concentrations and different stable-isotope signatures of spotted seatrout between basins. Mercury concentrations in spotted seatrout were greatest in Mosquito Lagoon (ML) and least in the Indian River Lagoon proper (IRL), although concentrations were low for all basins. Spotted seatrout from IRL were carbon-depleted and nitrogen-enriched compared with those from the other basins; this suggests either that the fish's primary source of carbon in IRL is an algae- or phytoplankton-based food web or that the pathway through the food web is shorter there. The {delta}{sup 15}N values of IRL spotted seatrout were greater than those in the Banana River Lagoon or ML, suggesting slightly different trophic positioning of fish in these basins. The greater {delta}{sup 15}N values in IRL spotted seatrout may also reflect the greater human population density and resultant anthropogenic inputs (e.g., observed higher total nitrogen levels) in IRL compared with the other more pristine basins examined. Understanding species' responses to broad-scale habitat heterogeneity in estuaries and knowing basin-specific differences in stable isotopes

  10. A sensitive and selective sensing platform based on CdTe QDs in the presence of l-cysteine for detection of silver, mercury and copper ions in water and various drinks.

    Science.gov (United States)

    Gong, Tingting; Liu, Junfeng; Liu, Xinxin; Liu, Jie; Xiang, Jinkun; Wu, Yiwei

    2016-12-15

    Water soluble CdTe quantum dots (QDs) have been prepared simply by one-pot method using potassium tellurite as stable tellurium source and thioglycolic acid (TGA) as stabilizer. The fluorescence of CdTe QDs can be improved 1.3-fold in the presence of l-cysteine (Cys), however, highly efficiently quenched in the presence of silver or mercury or copper ions. A sensitive and selective sensing platform for analysis of silver, mercury and copper ions has been simply established based on CdTe QDs in the presence of l-cysteine. Under the optimum conditions, excellent linear relationships exist between the quenching degree of the sensing platform and the concentrations of Ag(+), Hg(2+) and Cu(2+) ranging from 0.5 to 40ngmL(-1). By using masking agents of sodium diethyldithiocarbamate (DDTC) for Ag(+) and Cu(2+), NH4OH for Ag(+) and Hg(2+) and 1-(2-Pyridylazo)-2-naphthol (PAN) for Hg(2+) and Cu(2+), Hg(2+), Cu(2+) and Ag(+) can be exclusively detected in coexistence with other two ions, and the detection limits (3σ) were 0.65, 0.063 and 0.088ngmL(-1) for Ag(+), Hg(2+) and Cu(2+), respectively. This effective sensing platform has been used to detection of Ag(+), Hg(2+) and Cu(2+) in water and various drinks with satisfactory results.

  11. Ethylene Decomposition Initiated by Ultraviolet Radiation from Low Pressure Mercury Lamps: Kinetics Model Prediction and Experimental Verification.

    Science.gov (United States)

    Jozwiak, Zbigniew Boguslaw

    1995-01-01

    Ethylene is an important auto-catalytic plant growth hormone. Removal of ethylene from the atmosphere surrounding ethylene-sensitive horticultural products may be very beneficial, allowing an extended period of storage and preventing or delaying the induction of disorders. Various ethylene removal techniques have been studied and put into practice. One technique is based on using low pressure mercury ultraviolet lamps as a source of photochemical energy to initiate chemical reactions that destroy ethylene. Although previous research showed that ethylene disappeared in experiments with mercury ultraviolet lamps, the reactions were not described and the actual cause of ethylene disappearance remained unknown. Proposed causes for this disappearance were the direct action of ultraviolet rays on ethylene, reaction of ethylene with ozone (which is formed when air or gas containing molecular oxygen is exposed to radiation emitted by this type of lamp), or reactions with atomic oxygen leading to formation of ozone. The objective of the present study was to determine the set of physical and chemical actions leading to the disappearance of ethylene from artificial storage atmosphere under conditions of ultraviolet irradiation. The goal was achieved by developing a static chemical model based on the physical properties of a commercially available ultraviolet lamp, the photochemistry of gases, and the kinetics of chemical reactions. The model was used to perform computer simulations predicting time dependent concentrations of chemical species included in the model. Development of the model was accompanied by the design of a reaction chamber used for experimental verification. The model provided a good prediction of the general behavior of the species involved in the chemistry under consideration; however the model predicted lower than measured rate of ethylene disappearance. Some reasons for the model -experiment disagreement are radiation intensity averaging, the experimental

  12. Investigation of the lithium ion mobility in cyclic model compounds and their ion conduction properties

    Energy Technology Data Exchange (ETDEWEB)

    Thielen, Joerg

    2011-07-27

    In view of both, energy density and energy drain, rechargeable lithium ion batteries outperform other present accumulator systems. However, despite great efforts over the last decades, the ideal electrolyte in terms of key characteristics such as capacity, cycle life, and most important reliable safety, has not yet been identified. Steps ahead in lithium ion battery technology require a fundamental understanding of lithium ion transport, salt association, and ion solvation within the electrolyte. Indeed, well defined model compounds allow for systematic studies of molecular ion transport. Thus, in the present work, based on the concept of immobilizing ion solvents, three main series with a cyclotriphosphazene (CTP), hexaphenylbenzene (HBP), and tetramethylcyclotetrasiloxane (TMS) scaffold were prepared. Lithium ion solvents, among others ethylene carbonate (EC), which has proven to fulfill together with propylene carbonate safety and market concerns in commercial lithium ion batteries, were attached to the different cores via alkyl spacers of variable length. All model compounds were fully characterized, pure and thermally stable up to at least 235 C, covering the requested broad range of glass transition temperatures from -78.1 C up to +6.2 C. While the CTP models tend to rearrange at elevated temperatures over time, which questions the general stability of alkoxide related (poly)phosphazenes, both, the HPB and CTP based models show no evidence of core stacking. In particular the CTP derivatives represent good solvents for various lithium salts, exhibiting no significant differences in the ionic conductivity {sigma}{sub dc} and thus indicating comparable salt dissociation and rather independent motion of cations and ions. In general, temperature-dependent bulk ionic conductivities investigated via impedance spectroscopy follow a William-Landel-Ferry (WLF) type behavior. Modifications of the alkyl spacer length were shown to influence ionic conductivities only in

  13. Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD-2

    Energy Technology Data Exchange (ETDEWEB)

    Tuzen, Mustafa, E-mail: m.tuzen@gmail.com [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Uluozlu, Ozgur Dogan [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Karaman, Isa [Gaziosmanpasa University, Faculty of Science and Arts, Biology Department, 60250 Tokat (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey)

    2009-09-30

    A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1 mol L{sup -1} HCl for methyl mercury and 2 mol L{sup -1} HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical conditions including pH, amounts of biosorbent, sample volumes, etc., were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries were also investigated. The capacity of biosorbent for mercury(II) and methyl mercury was 4.8 and 3.4 mg g{sup -1}. The detection limit (3 sigma) of the reagent blank for mercury(II) and methyl mercury was 2.1 and 1.5 ng L{sup -1}. Preconcentration factor was calculated as 25. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of standard reference material (NRCC-DORM 2 Dogfish Muscle). The procedure was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and environmental samples.

  14. Mercury(II) and methyl mercury speciation on Streptococcus pyogenes loaded Dowex Optipore SD-2.

    Science.gov (United States)

    Tuzen, Mustafa; Uluozlu, Ozgur Dogan; Karaman, Isa; Soylak, Mustafa

    2009-09-30

    A solid phase extraction procedure based on speciation of mercury(II) and methyl mercury on Streptococcus pyogenes immobilized on Dowex Optipore SD-2 has been established. Selective and sequential elution with 0.1 mol L(-1) HCl for methyl mercury and 2 mol L(-1) HCl for mercury(II) were performed at pH 8. The determination of mercury levels was performed by cold vapour atomic absorption spectrometry (CVAAS). Optimal analytical conditions including pH, amounts of biosorbent, sample volumes, etc., were investigated. The influences of the some alkaline and earth alkaline ions and some transition metals on the recoveries were also investigated. The capacity of biosorbent for mercury(II) and methyl mercury was 4.8 and 3.4 mg g(-1). The detection limit (3 sigma) of the reagent blank for mercury(II) and methyl mercury was 2.1 and 1.5 ng L(-1). Preconcentration factor was calculated as 25. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of standard reference material (NRCC-DORM 2 Dogfish Muscle). The procedure was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and environmental samples.

  15. Assessing Mercury and Methylmercury Bioavailability in Sediment Pore Water Using Mercury-Specific Hydrogels

    Science.gov (United States)

    2015-06-01

    including a closer look at the effects of mercury speciation and complexation, as well as continued work employing DGTs as mercury porewater...developing a deeper understanding of the relationship between DGT and tissue data, including a closer look at the effects of mercury speciation and...mercury-contaminated soils with activated carbon: a laboratory, field, and modeling study. Rem J 21(1):115-135. Brooks Rand Labs. 2013

  16. Two-dimensional FeS nanoflakes: synthesis and application to electrochemical sensor for mercury(II) ions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ligang; Zhao, Yizhe; Tian, Yang, E-mail: tianyang@cnu.edu.cn [Capital Normal University, Department of Chemistry (China)

    2015-10-15

    We report a facile solvothermal method to prepare troilite FeS two-dimensional nanoflakes. The morphology and size were observed by transmission electron microscopy (TEM), the intrinsic crystallography of the obtained FeS nanoflakes was characterized by powder X-ray diffraction and high-resolution TEM, and the composition was analyzed by X-ray photoelectron spectroscopy. Furthermore, the prepared FeS nanoflakes were successfully modified on an electrode to fabricate a sensor for Hg{sup 2+} detection. The electrochemical detection mechanism was expected that Hg{sup 2+} ions interact with FeS to form stable HgS in the nanoflakes, which provided a sensitive approach for electrochemical detection of Hg{sup 2+} selectively. The detection limit for Hg{sup 2+} was 4 nM in a PBS solution. The prepared sensor based on the FeS nanoflakes shows the better performance than that with bulk-FeS materials for the Hg{sup 2+} detection. The proposed FeS nanoflakes also exhibit good applicability for monitoring Hg{sup 2+} in real water specimens.

  17. One-pot electrochemical synthesis of functionalized fluorescent carbon dots and their selective sensing for mercury ion

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yuxin; Lu, Qiujun; Deng, Jianhui; Li, Haitao; Zhang, Youyu, E-mail: zhangyy@hunnu.edu.cn

    2015-03-25

    Highlights: • One-pot electrochemical synthesis of functionalized carbon dots (C-Dots). • The C-Dots can serve as a fluorescent probe for sensitive detection of Hg{sup 2+}. • The detection limit for Hg{sup 2+} is 3.3 nM. • The sensor is successfully applied to Hg{sup 2+} determination in real samples. - Abstract: We propose a simple, economical, and one-pot method to synthesize water-soluble functionalized fluorescent carbon dots (C-Dots) through electrochemical carbonization of sodium citrate and urea. The as-prepared C-Dots have good photostability and exhibit a high quantum yield of 11.9%. The sizes of the C-Dots are mainly distributed in the range of 1.0–3.5 nm with an average size of 2.4 nm. It has been further used as a novel label-free sensing probe for selective detection of Hg{sup 2+} ions with detection limit as low as 3.3 nM. The detection linear range is 0.01–10 μM. The as-prepared C-Dots are also successfully applied for the determination of Hg{sup 2+} in real water samples.

  18. The role of pressure drop and flow redistribution on modeling mercury control using sorbent injection in baghouse filters.

    Science.gov (United States)

    Flora, Joseph R V; Hargis, Richard A; O'Dowd, William J; Karash, Andrew; Pennline, Henry W; Vidic, Radisav D

    2006-03-01

    A mathematical model based on simple cake filtration theory was coupled to a previously developed two-stage mathematical model for mercury (Hg) removal using powdered activated carbon injection upstream of a baghouse filter. Values of the average permeability of the filter cake and the filter resistance extracted from the model were 4.4 x 10(-13) m2 and 2.5 x 10(-4) m(-1), respectively. The flow is redistributed during partial cleaning of the filter, with flows higher across the newly cleaned filter section. The calculated average Hg removal efficiency from the baghouse is lower because of the high mass flux of Hg exiting the filter in the newly cleaned section. The model shows that calculated average Hg removal is affected by permeability, filter resistance, fraction of the baghouse cleaned, and cleaning interval.

  19. A New Poisson-Nernst-Planck Model with Ion-Water Interactions for Charge Transport in Ion Channels.

    Science.gov (United States)

    Chen, Duan

    2016-08-01

    In this work, we propose a new Poisson-Nernst-Planck (PNP) model with ion-water interactions for biological charge transport in ion channels. Due to narrow geometries of these membrane proteins, ion-water interaction is critical for both dielectric property of water molecules in channel pore and transport dynamics of mobile ions. We model the ion-water interaction energy based on realistic experimental observations in an efficient mean-field approach. Variation of a total energy functional of the biological system yields a new PNP-type continuum model. Numerical simulations show that the proposed model with ion-water interaction energy has the new features that quantitatively describe dielectric properties of water molecules in narrow pores and are possible to model the selectivity of some ion channels.

  20. Ferroelectric active models of ion channels in biomembranes.

    Science.gov (United States)

    Bystrov, V S; Lakhno, V D; Molchanov, M

    1994-06-21

    Ferroactive models of ion channels in the theory of biological membranes are presented. The main equations are derived and their possible solutions are shown. The estimates of some experimentally measured parameters are given. Possible physical consequences of the suggested models are listed and the possibility of their experimental finding is discussed. The functioning of the biomembrane's ion channel is qualitatively described on the basis of the suggested ferroactive models. The main directions and prospects for development of the ferroactive approach to the theory of biological membranes and their structures are indicated.

  1. Computational stochastic model of ions implantation

    Energy Technology Data Exchange (ETDEWEB)

    Zmievskaya, Galina I., E-mail: zmi@gmail.ru; Bondareva, Anna L., E-mail: bal310775@yandex.ru [M.V. Keldysh Institute of Applied Mathematics RAS, 4,Miusskaya sq., 125047 Moscow (Russian Federation); Levchenko, Tatiana V., E-mail: tatlevchenko@mail.ru [VNII Geosystem Russian Federal Center, Varshavskoye roadway, 8, Moscow (Russian Federation); Maino, Giuseppe, E-mail: giuseppe.maino@enea.it [Scuola di Lettere e BeniCulturali, University di Bologna, sede di Ravenna, via Mariani 5, 48100 Ravenna (Italy)

    2015-03-10

    Implantation flux ions into crystal leads to phase transition /PT/ 1-st kind. Damaging lattice is associated with processes clustering vacancies and gaseous bubbles as well their brownian motion. System of stochastic differential equations /SDEs/ Ito for evolution stochastic dynamical variables corresponds to the superposition Wiener processes. The kinetic equations in partial derivatives /KE/, Kolmogorov-Feller and Einstein-Smolukhovskii, were formulated for nucleation into lattice of weakly soluble gases. According theory, coefficients of stochastic and kinetic equations uniquely related. Radiation stimulated phase transition are characterized by kinetic distribution functions /DFs/ of implanted clusters versus their sizes and depth of gas penetration into lattice. Macroscopic parameters of kinetics such as the porosity and stress calculated in thin layers metal/dielectric due to Xe{sup ++} irradiation are attracted as example. Predictions of porosity, important for validation accumulation stresses in surfaces, can be applied at restoring of objects the cultural heritage.

  2. Chemical Form Matters: Differential Accumulation of Mercury Following Inorganic and Organic Mercury Exposures in Zebrafish Larvae

    Energy Technology Data Exchange (ETDEWEB)

    Korbas, Malgorzata; MacDonald, Tracy C.; Pickering, Ingrid J.; George, Graham N.; Krone, Patrick H. (Saskatchewan)

    2013-04-08

    Mercury, one of the most toxic elements, exists in various chemical forms each with different toxicities and health implications. Some methylated mercury forms, one of which exists in fish and other seafood products, pose a potential threat, especially during embryonic and early postnatal development. Despite global concerns, little is known about the mechanisms underlying transport and toxicity of different mercury species. To investigate the impact of different mercury chemical forms on vertebrate development, we have successfully combined the zebrafish, a well-established developmental biology model system, with synchrotron-based X-ray fluorescence imaging. Our work revealed substantial differences in tissue-specific accumulation patterns of mercury in zebrafish larvae exposed to four different mercury formulations in water. Methylmercury species not only resulted in overall higher mercury burdens but also targeted different cells and tissues than their inorganic counterparts, thus revealing a significant role of speciation in cellular and molecular targeting and mercury sequestration. For methylmercury species, the highest mercury concentrations were in the eye lens epithelial cells, independent of the formulation ligand (chloride versus L-cysteine). For inorganic mercury species, in absence of L-cysteine, the olfactory epithelium and kidney accumulated the greatest amounts of mercury. However, with L-cysteine present in the treatment solution, mercuric bis-L-cysteineate species dominated the treatment, significantly decreasing uptake. Our results clearly demonstrate that the common differentiation between organic and inorganic mercury is not sufficient to determine the toxicity of various mercury species.

  3. Chemical form matters: differential accumulation of mercury following inorganic and organic mercury exposures in zebrafish larvae.

    Science.gov (United States)

    Korbas, Malgorzata; Macdonald, Tracy C; Pickering, Ingrid J; George, Graham N; Krone, Patrick H

    2012-02-17

    Mercury, one of the most toxic elements, exists in various chemical forms each with different toxicities and health implications. Some methylated mercury forms, one of which exists in fish and other seafood products, pose a potential threat, especially during embryonic and early postnatal development. Despite global concerns, little is known about the mechanisms underlying transport and toxicity of different mercury species. To investigate the impact of different mercury chemical forms on vertebrate development, we have successfully combined the zebrafish, a well-established developmental biology model system, with synchrotron-based X-ray fluorescence imaging. Our work revealed substantial differences in tissue-specific accumulation patterns of mercury in zebrafish larvae exposed to four different mercury formulations in water. Methylmercury species not only resulted in overall higher mercury burdens but also targeted different cells and tissues than their inorganic counterparts, thus revealing a significant role of speciation in cellular and molecular targeting and mercury sequestration. For methylmercury species, the highest mercury concentrations were in the eye lens epithelial cells, independent of the formulation ligand (chloride versusl-cysteine). For inorganic mercury species, in absence of l-cysteine, the olfactory epithelium and kidney accumulated the greatest amounts of mercury. However, with l-cysteine present in the treatment solution, mercuric bis-l-cysteineate species dominated the treatment, significantly decreasing uptake. Our results clearly demonstrate that the common differentiation between organic and inorganic mercury is not sufficient to determine the toxicity of various mercury species.

  4. Modeling the observed tropospheric BrO background: Importance of multiphase chemistry and implications for ozone, OH, and mercury

    Science.gov (United States)

    Schmidt, J. A.; Jacob, D. J.; Horowitz, H. M.; Hu, L.; Sherwen, T.; Evans, M. J.; Liang, Q.; Suleiman, R. M.; Oram, D. E.; Le Breton, M.; Percival, C. J.; Wang, S.; Dix, B.; Volkamer, R.

    2016-10-01

    Aircraft and satellite observations indicate the presence of ppt (ppt ≡ pmol/mol) levels of BrO in the free troposphere with important implications for the tropospheric budgets of ozone, OH, and mercury. We can reproduce these observations with the GEOS-Chem global tropospheric chemistry model by including a broader consideration of multiphase halogen (Br-Cl) chemistry than has been done in the past. Important reactions for regenerating BrO from its nonradical reservoirs include HOBr + Br-/Cl- in both aerosols and clouds, and oxidation of Br- by ClNO3 and ozone. Most tropospheric BrO in the model is in the free troposphere, consistent with observations and originates mainly from the photolysis and oxidation of ocean-emitted CHBr3. Stratospheric input is also important in the upper troposphere. Including production of gas phase inorganic bromine from debromination of acidified sea salt aerosol increases free tropospheric Bry by about 30%. We find HOBr to be the dominant gas-phase reservoir of inorganic bromine. Halogen (Br-Cl) radical chemistry as implemented here in GEOS-Chem drives 14% and 11% decreases in the global burdens of tropospheric ozone and OH, respectively, a 16% increase in the atmospheric lifetime of methane, and an atmospheric lifetime of 6 months for elemental mercury. The dominant mechanism for the Br-Cl driven tropospheric ozone decrease is oxidation of NOx by formation and hydrolysis of BrNO3 and ClNO3.

  5. Bistable dynamics underlying excitability of ion homeostasis in neuron models.

    Directory of Open Access Journals (Sweden)

    Niklas Hübel

    2014-05-01

    Full Text Available When neurons fire action potentials, dissipation of free energy is usually not directly considered, because the change in free energy is often negligible compared to the immense reservoir stored in neural transmembrane ion gradients and the long-term energy requirements are met through chemical energy, i.e., metabolism. However, these gradients can temporarily nearly vanish in neurological diseases, such as migraine and stroke, and in traumatic brain injury from concussions to severe injuries. We study biophysical neuron models based on the Hodgkin-Huxley (HH formalism extended to include time-dependent ion concentrations inside and outside the cell and metabolic energy-driven pumps. We reveal the basic mechanism of a state of free energy-starvation (FES with bifurcation analyses showing that ion dynamics is for a large range of pump rates bistable without contact to an ion bath. This is interpreted as a threshold reduction of a new fundamental mechanism of ionic excitability that causes a long-lasting but transient FES as observed in pathological states. We can in particular conclude that a coupling of extracellular ion concentrations to a large glial-vascular bath can take a role as an inhibitory mechanism crucial in ion homeostasis, while the Na⁺/K⁺ pumps alone are insufficient to recover from FES. Our results provide the missing link between the HH formalism and activator-inhibitor models that have been successfully used for modeling migraine phenotypes, and therefore will allow us to validate the hypothesis that migraine symptoms are explained by disturbed function in ion channel subunits, Na⁺/K⁺ pumps, and other proteins that regulate ion homeostasis.

  6. Stydy on the Model of Ion Exchange Kinetics

    Institute of Scientific and Technical Information of China (English)

    ChenFengrong; JiangZhixin

    1994-01-01

    In this paper, a macrokinetics model equation describing the characteristics of the solid-liquid mass transfer has been proposed.The qualitative analysis and experimental verification have been done for this mode equation.The model equation can explain the ion exchange process considerably well.

  7. Estimating Mercury-Binding Ligand Concentrations in Freshwater Wetland Porewaters Using the “Tin-Reducible-Mercury” Titration Method

    Science.gov (United States)

    Creswell, J. E.; Babiarz, C.; Shafer, M. M.; Armstrong, D. E.

    2009-12-01

    Wetland environments are recognized as active regions of mercury methylation and may represent the primary source of methylmercury to many aquatic systems. Thus understanding the methylation process in these systems is vital to efforts at prediction of methylmercury accumulation at higher trophic levels. Strong mercury-binding ligands in porewaters can limit methylation in wetlands because large ligands and charged Hg-complexes are not bioavailable to methylating bacteria. Following the method developed by Lamborg and colleagues (2003), we used tin(II) chloride, a weak reductant, to reduce and measure labile Hg in porewater samples (i.e. the fraction not bound to strong ligands). We further titrated samples with Hg(II) to determine the Hg concentration at which the naturally occurring ligands were saturated - thus providing a measure of mercury-binding ligand concentrations. To our knowledge, this is the first extensive use of this technique on porewater samples. In an effort to differentiate between inorganic- and organic-complexed Hg, we modeled the inorganic speciation of Hg using MINEQL+, an aqueous speciation modeling program. Measurements of total mercury, methylmercury, sulfide, sulfate, chloride, carbonate, pH, dissolved organic carbon, phosphate, bromide, and major ions in sample porewaters were used as inputs to the model. Using the inorganic speciation calculated by the model, and the ligand concentrations measured in our laboratory experiment, we calculated conditional stability constants for mercury-ligand binding in this system. Although modeling predicts that mercury speciation will be dominated by sulfide at the concentrations present in this system, mercury methylation rate measurements show a stronger correlation with dissolved organic carbon concentrations than with sulfide. This correlation suggests that dissolved organic carbon plays an important role in mercury speciation, even in the presence of sulfide. Porewaters were extracted from

  8. MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS

    Energy Technology Data Exchange (ETDEWEB)

    Nash, C.; Hang, T.; Aleman, S.

    2011-01-03

    Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.

  9. Radial dose distribution around an energetic heavy ion and an ion track structure model

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, Katsutoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ohno, Shin-ichi; Namba, Hideki; Taguchi, Mitsumasa; Watanabe, Ritsuko

    1997-03-01

    Ionization currents produced in a small wall-less ionization chamber located at varying distance from the 200 MeV Ni{sup 12+} ion`path traversing Ar gas were measured and utilized to construct a track structure model. Using the LET value of 200 MeV Ni{sup 12+} and G(Fe{sup 3+}) in Fricke solutions (= 15.4) for fast electrons, we estimate G(Fe{sup 3+}) for this ion to be 5.0. (author)

  10. Tests of the improved Weiland ion temperature gradient transport model

    Energy Technology Data Exchange (ETDEWEB)

    Kinsey, J.E.; Bateman, G.; Kritz, A.H. [Lehigh Univ., Bethlehem, PA (United States)] [and others

    1996-12-31

    The Weiland theoretically derived transport model for ion temperature gradient and trapped electron modes has been improved to include the effects of parallel ion motion, finite beta, and collisionality. The model also includes the effects of impurities, fast ions, unequal ion and electron temperatures, and finite Larmor radius. This new model has been implemented in our time-dependent transport code and is used in conjunction with pressure-driven modes and neoclassical theory to predict the radial particle and thermal transport in tokamak plasmas. Simulations of TFTR, DIII-D, and JET L-mode plasmas have been conducted to test how the new effects change the predicted density and temperature profiles. Comparisons are made with results obtained using the previous version of the model which was successful in reproducing experimental data from a wide variety of tokamak plasmas. Specifically, the older model has been benchmarked against over 50 discharges from at least 7 different tokamaks including L-mode scans in current, heating power, density, and dimensionless scans in normalized gyro-radius, collisionality, and beta. We have also investigated the non-diffusive elements included in the Weiland model, particularly the particle pinch in order to characterize its behavior. This is partly motivated by recent simulations of ITER. In those simulations, the older Weiland model predicted a particle pinch and ignition was more easily obtained.

  11. Fate of mercury in the Arctic (FOMA)

    DEFF Research Database (Denmark)

    Skov, H.; Christensen, J.; Asmund, G.

    This report is the final reporting of the project FONA, funded by the Danish Environmental Protection Agency with means from the MIKA/DANCEA funds for Environmental Support to the Arctic Region. The aim of the project is to study the intercompartment mercury transport chain in the arctic area. From...... atmospheric deposition of mercury on sea surfaces to uptake in marine organisms, bio-accumulation, and finally mercury levels in mammals. The studies in the project are focused on the behaviour of mercury during the spring period where special phenomena lead to an enhanced deposition of mercury in the Arctic...... environment, at a time where the marine ecosystem is particularly active. The studies also include a comprehensive time trend study of mercury in top carnivore species. Each of these studies contributes towards establishing the knowledge necessary to develop a general model for transport and uptake of mercury...

  12. Fate of mercury in the Arctic (FOMA)

    DEFF Research Database (Denmark)

    Skov, H.; Christensen, J.; Asmund, G.

    This report is the final reporting of the project FONA, funded by the Danish Environmental Protection Agency with means from the MIKA/DANCEA funds for Environmental Support to the Arctic Region. The aim of the project is to study the intercompartment mercury transport chain in the arctic area. From...... atmospheric deposition of mercury on sea surfaces to uptake in marine organisms, bio-accumulation, and finally mercury levels in mammals. The studies in the project are focused on the behaviour of mercury during the spring period where special phenomena lead to an enhanced deposition of mercury in the Arctic...... environment, at a time where the marine ecosystem is particularly active. The studies also include a comprehensive time trend study of mercury in top carnivore species. Each of these studies contributes towards establishing the knowledge necessary to develop a general model for transport and uptake of mercury...

  13. Statistical 3D damage accumulation model for ion implant simulators

    CERN Document Server

    Hernandez-Mangas, J M; Enriquez, L E; Bailon, L; Barbolla, J; Jaraiz, M

    2003-01-01

    A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided.

  14. Statistical 3D damage accumulation model for ion implant simulators

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Mangas, J.M. E-mail: jesman@ele.uva.es; Lazaro, J.; Enriquez, L.; Bailon, L.; Barbolla, J.; Jaraiz, M

    2003-04-01

    A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided.

  15. An ion species model for positive ion sources - part II analysis of hydrogen isotope effects

    CERN Document Server

    Surrey, E

    2014-01-01

    A one dimensional model of the magnetic multipole volume plasma source has been developed for application to intense ion/neutral atom beam injectors. The model uses plasma transport coefficients for particle and energy flow to create a detailed description of the plasma parameters along an axis parallel to that of the extracted beam. In this paper the isotopic modelling of positive hydrogenic ions is considered and compared with experimental data from the neutral beam injectors of the Joint European Torus. The use of the code to gain insights into the processes contributing to the ratios of the ionic species is demonstrated and the conclusion is drawn that 75% of the atomic ion species arises from ionization of dissociated molecules and 25% from dissociation of the molecular ions. However whilst the former process is independent of the filter field, the latter is sensitive to the change in distribution of fast and thermal electrons produced by the magnetic filter field and an optimum combination of field stre...

  16. Ion-acoustic shocks with reflected ions: modeling and PIC simulations

    CERN Document Server

    Liseykina, T; Vshivkov, V; Malkov, M

    2015-01-01

    Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms whereby they accelerate particles remains incomplete. We present here the results of numerical modeling of an ion-acoustic collisionless shock based on one-dimensional (1D) kinetic approximation both for electrons and ions with a real mass ratio. Special emphasis is made on the shock-reflected ions as the main driver of shock dissipation. The reflection efficiency, velocity distribution of reflected particles and the shock electrostatic structure are studied in terms of the shock parameters. Applications to particle acceleration in geophysical and astrophysical shocks are discussed.

  17. The role of iron compounds and hydrogen peroxideon the oxidation of metallic mercury

    OpenAIRE

    "愛甲, 博美"

    1980-01-01

    The uptake of metallic mercury with ferric and ferrous ions was studied. The results were; (1) Mercury uptake of free ferric ion increased with hydrogen peroxide, the maximum uptake was 1.0 mM. However, ferric ion was not taken up without hydrogen peroxide. (2) In the presence of ferric and ferrous ions with hydrogen peroxide, mercury uptake was maximum when the mole ratio (Fe(3+)/Fe(2+)) was 0.1.

  18. Rank-based model selection for multiple ions quantum tomography

    Science.gov (United States)

    Guţă, Mădălin; Kypraios, Theodore; Dryden, Ian

    2012-10-01

    The statistical analysis of measurement data has become a key component of many quantum engineering experiments. As standard full state tomography becomes unfeasible for large dimensional quantum systems, one needs to exploit prior information and the ‘sparsity’ properties of the experimental state in order to reduce the dimensionality of the estimation problem. In this paper we propose model selection as a general principle for finding the simplest, or most parsimonious explanation of the data, by fitting different models and choosing the estimator with the best trade-off between likelihood fit and model complexity. We apply two well established model selection methods—the Akaike information criterion (AIC) and the Bayesian information criterion (BIC)—two models consisting of states of fixed rank and datasets such as are currently produced in multiple ions experiments. We test the performance of AIC and BIC on randomly chosen low rank states of four ions, and study the dependence of the selected rank with the number of measurement repetitions for one ion states. We then apply the methods to real data from a four ions experiment aimed at creating a Smolin state of rank 4. By applying the two methods together with the Pearson χ2 test we conclude that the data can be suitably described with a model whose rank is between 7 and 9. Additionally we find that the mean square error of the maximum likelihood estimator for pure states is close to that of the optimal over all possible measurements.

  19. Worldwide trend of atmospheric mercury since 1995

    Directory of Open Access Journals (Sweden)

    F. Slemr

    2011-01-01

    Full Text Available Concern about the adverse effects of mercury on human health and ecosystems has led to tightening emission controls since the mid 1980s. But the resulting mercury emissions reductions in many parts of the world are believed to be offset or even surpassed by the increasing emissions in rapidly industrializing countries. Consequently, concentrations of atmospheric mercury are expected to remain roughly constant. Here we show that the worldwide atmospheric mercury concentration have decreased by about 20 to 38% since 1996 as indicated by long term monitoring at stations in the Southern and Northern Hemispheres combined with intermittent measurements of latitudinal distribution over the Atlantic Ocean. The total reduction of the atmospheric mercury burden of this magnitude within 14 yrs is unprecedented among most of atmospheric trace gases and is at odds with the current mercury emission inventories with nearly constant emissions over the period. It suggests a major shift in the biogeochemical cycle of mercury including oceans and soil reservoirs. Decreasing reemissions from the legacy of historical mercury emissions are the most likely explanation for this decline since the hypothesis of an accelerated oxidation rate of elemental mercury in the atmosphere is not supported by the observed trends of other trace gases. Consequently, models of the atmospheric mercury cycle have to include soil and ocean mercury pools and their dynamics to be able to make projections of future trends.

  20. A kinetic study of mercury(II transport through a membrane assisted by new transport reagent

    Directory of Open Access Journals (Sweden)

    Görgülü Ahmet

    2011-07-01

    Full Text Available Abstract Background A new organodithiophosphorus derivative, namely O-(1,3-Bispiperidino-2-propyl-4-methoxy phenyldithiophosphonate, was synthesized and then the kinetic behavior of the transport process as a function of concentration, temperature, stirring rate and solvents was investigated. Results The compound 1 was characterized by elemental analysis, IR, 1H and 31P NMR spectroscopies. The transport of mercury(II ion by a zwitterionic dithiophosphonate 1 in the liquid membrane was studied and the kinetic behavior of the transport process as a function of concentration, temperature, stirring rate and solvents was investigated. The compound 1 is expected to serve as a model liquid membrane transport with mercury(II ions. Conclusion A kinetic study of mercury(II transport through a membrane assisted by O-(1,3-Bispiperidino-2-propyl-4-methoxy phenyldithiophosphonate was performed. It can be concluded that the compound 1 can be provided a general and straightforward route to remove toxic metals ions such as mercury(II ion from water or other solution.

  1. Coarse grained model for calculating the ion mobility of hydrocarbons

    Science.gov (United States)

    Kuroboshi, Y.; Takemura, K.

    2016-12-01

    Hydrocarbons are widely used as insulating compounds. However, their fundamental characteristics in conduction phenomena are not completely understood. A great deal of effort is required to determine reasonable ionic behavior from experiments because of their complicated procedures and tight controls of the temperature and the purity of the liquids. In order to understand the conduction phenomena, we have theoretically calculated the ion mobilities of hydrocarbons and investigated their characteristics using the coarse grained model in molecular dynamics simulations. We assumed a molecule of hydrocarbons to be a bead and simulated its dependence on the viscosity, electric field, and temperature. Furthermore, we verified the suitability of the conformation, scale size, and long-range interactions for the ion mobility. The results of the simulations show that the ion mobility values agree reasonably well with the values from Walden's rule and depend on the viscosity but not on the electric field. The ion mobility and self-diffusion coefficient exponentially increase with increasing temperature, while the activation energy decreases with increasing molecular size. These values and characteristics of the ion mobility are in reasonable agreement with experimental results. In the future, we can understand not only the ion mobilies of hydrocarbons in conduction, but also we can predict general phenomena in electrochemistry with molecular dynamics simulations.

  2. Highly sensitive and specific determination of mercury(II) ion in water, food and cosmetic samples with an ELISA based on a novel monoclonal antibody

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuzhen; Li, Yuan [Sichuan University, College of Chemistry, Chengdu (China); Yang, Hong [Soochow University, College of Pharmacy, Suzhou (China); Pschenitza, Michael; Niessner, Reinhard; Knopp, Dietmar [Technical University Munich, Chair for Analytical Chemistry, Institute of Hydrochemistry and Chemical Balneology, Munich (Germany); Deng, Anping [Sichuan University, College of Chemistry, Chengdu (China); Soochow University, College of Chemistry, Chemical Engineering and Materials Science, Suzhou (China)

    2012-07-15

    Mercury is one of the most toxic heavy metals present in the environment. In this study, a highly sensitive and specific monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of Hg{sup 2+} was developed. A new bifunctional ligand, 6-mercaptonicotinic acid (MNA), which contains a pyridine ring bearing a carboxylic group and a mercapto group, was selected for the preparation of immunogen. After immunization of mice and performing the hybridoma technique, the obtained mAb was characterized for its binding affinity and selectivity for Hg{sup 2+}. Based on this novel mAb, an ELISA was established. At optimal experimental conditions, the standard curve of the ELISA for Hg{sup 2+} was constructed in concentration range of 0.1-100 ng mL{sup -1}. The values of IC{sub 50} and LOD of the assay were found to be 1.12 and 0.08 ng mL{sup -1}. The cross-reactivity was lower than 2 % with MNA, CH{sub 3}Hg, and CH{sub 3}Hg-MNA and was 11.5 % and 4.4 % for Hg{sup +} and Au{sup 3+}, respectively. No cross-reactivity was found with other metal ions such as Cu{sup 2+}, Sn{sup 2+}, Ni{sup 2+}, Mn{sup 2+}, Pb{sup 2+}, Zn{sup 2+}, Cd{sup 2+}, Fe{sup 2+}, Co{sup 2+}, Mg{sup 2+}, Ca{sup 2+}, and anions such as Cl{sup -}, NO{sub 3} {sup -}, NO{sub 2} {sup -}, HCO{sub 3} {sup -}, F{sup -}, and SO{sub 4} {sup 2-}, indicating that the assay displays not only high sensitivity but also high selectivity. Different kinds of samples including water, milk, green vegetable, kelp, facial cleanser, and night cream were spiked with Hg{sup 2+} and the extracts were analyzed by ELISA. Acceptable recovery rates of 80.0-113.0 % and coefficients of variation of 1.9-18.6 % were obtained. A linear relationship between ELISA and cold-vapor atomic fluorescence spectroscopy (CV-AFS) as indicated by a correlation coefficient of 0.97 for liquid samples (water samples) and 0.98 for other samples was obtained. The proposed mAb-based ELISA provides a

  3. RESISTANCE LEVEL OF Pseudomonas stutzeri AGAINST MERCURY AND ITS ABILITY IN PRODUCTION OF MERCURY REDUCTASE ENZYME

    Directory of Open Access Journals (Sweden)

    Purkan Purkan

    2016-11-01

    Full Text Available Mercury reductase is an enzyme that is able to reduce Hg2+ to Hg0 non toxic. This enzyme is usually produced by mercury resistant bacteria. The research wanted to determine the resistance of indigenous Pseudomonas stutzeri isolate toward mercury and to explore the mercury reductase activity which is produced by the bacteria. The results of resistance assay of the Pseudomonas stutzeri toward mercury ion showed that the isolate could survive in media containing HgCl2 up to a concentration of 80 µM. The bacteria could produce mercury reductase optimally at the 24th of fermentation time. The enzyme showed optimum activity at pH 7 and temperature of 45 oC

  4. Lithium-ion batteries modeling involving fractional differentiation

    Science.gov (United States)

    Sabatier, Jocelyn; Merveillaut, Mathieu; Francisco, Junior Mbala; Guillemard, Franck; Porcelatto, Denis

    2014-09-01

    With hybrid and electric vehicles development, automobile battery monitoring systems (BMS) have to meet the new requirements. These systems have to give information on state of health, state of charge, available power. To get this information, BMS often implement battery models. Accuracy of the information manipulated by the BMS thus depends on the model accuracy. This paper is within this framework and addresses lithium-ion battery modeling. The proposed fractional model is based on simplifications of an electrochemical model and on resolution of some partial differential equations used in its description. Such an approach permits to get a simple model in which electrochemical variables and parameters still appear.

  5. Fluorescent sensor for mercury

    Science.gov (United States)

    Wang, Zidong [Urbana, IL; Lee, Jung Heon [Evanston, IL; Lu, Yi [Champaign, IL

    2011-11-22

    The present invention provides a sensor for detecting mercury, comprising: a first polynucleotide, comprising a first region, and a second region, a second polynucleotide, a third polynucleotide, a fluorophore, and a quencher, wherein the third polynucleotide is optionally linked to the second region; the fluorophore is linked to the first polynucleotide and the quencher is linked to the second polynucleotide, or the fluorophore is linked to the second polynucleotide and the quencher is linked to the first polynucleotide; the first region and the second region hybridize to the second polynucleotide; and the second region binds to the third polynucleotide in the presence of Hg.sup.2+ ions.

  6. Fundamentals of Mercury Oxidation in Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    JoAnn Lighty; Geoffrey Silcox; Constance Senior; Joseph Helble; Balaji Krishnakumar

    2008-07-31

    The objective of this project was to understand the importance of and the contribution of gas-phase and solid-phase coal constituents in the mercury oxidation reactions. The project involved both experimental and modeling efforts. The team was comprised of the University of Utah, Reaction Engineering International, and the University of Connecticut. The objective was to determine the experimental parameters of importance in the homogeneous and heterogeneous oxidation reactions; validate models; and, improve existing models. Parameters studied include HCl, NO{sub x}, and SO{sub 2} concentrations, ash constituents, and temperature. The results suggested that homogeneous mercury oxidation is below 10% which is not consistent with previous data of others and work which was completed early in this research program. Previous data showed oxidation above 10% and up to 100%. However, the previous data are suspect due to apparent oxidation occurring within the sampling system where hypochlorite ion forms in the KCl impinger, which in turn oxidized mercury. Initial tests with entrained iron oxide particles injected into a flame reactor suggest that iron present on fly ash particle surfaces can promote heterogeneous oxidation of mercury in the presence of HCl under entrained flow conditions. Using the data generated above, with homogeneous reactions accounting for less than 10% of the oxidation, comparisons were made to pilot- and full-scale data. The results suggest that heterogeneous reactions, as with the case of iron oxide, and adsorption on solid carbon must be taking place in the full-scale system. Modeling of mercury oxidation using parameters from the literature was conducted to further study the contribution of homogeneous pathways to Hg oxidation in coal combustion systems. Calculations from the literature used rate parameters developed in different studies, in some cases using transition state theory with a range of approaches and basis sets, and in other cases

  7. Mercury CEM Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John Schabron; Joseph Rovani; Mark Sanderson

    2008-02-29

    Mercury continuous emissions monitoring systems (CEMS) are being implemented in over 800 coal-fired power plant stacks. The power industry desires to conduct at least a full year of monitoring before the formal monitoring and reporting requirement begins on January 1, 2009. It is important for the industry to have available reliable, turnkey equipment from CEM vendors. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor generators. The generators are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 requires that calibration be performed with NIST-traceable standards (Federal Register 2007). Traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued an interim traceability protocol for elemental mercury generators (EPA 2007). The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The document is divided into two separate sections. The first deals with the qualification of generators by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the generator models that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma/mass spectrometry performed by NIST in Gaithersburg, MD. The

  8. Atmospheric mercury footprints of nations.

    Science.gov (United States)

    Liang, Sai; Wang, Yafei; Cinnirella, Sergio; Pirrone, Nicola

    2015-03-17

    The Minamata Convention was established to protect humans and the natural environment from the adverse effects of mercury emissions. A cogent assessment of mercury emissions is required to help implement the Minamata Convention. Here, we use an environmentally extended multi-regional input-output model to calculate atmospheric mercury footprints of nations based on upstream production (meaning direct emissions from the production activities of a nation), downstream production (meaning both direct and indirect emissions caused by the production activities of a nation), and consumption (meaning both direct and indirect emissions caused by final consumption of goods and services in a nation). Results show that nations function differently within global supply chains. Developed nations usually have larger consumption-based emissions than up- and downstream production-based emissions. India, South Korea, and Taiwan have larger downstream production-based emissions than their upstream production- and consumption-based emissions. Developed nations (e.g., United States, Japan, and Germany) are in part responsible for mercury emissions of developing nations (e.g., China, India, and Indonesia). Our findings indicate that global mercury abatement should focus on multiple stages of global supply chains. We propose three initiatives for global mercury abatement, comprising the establishment of mercury control technologies of upstream producers, productivity improvement of downstream producers, and behavior optimization of final consumers.

  9. Numerical modeling of the SNS H- ion source

    Science.gov (United States)

    Veitzer, Seth A.; Beckwith, Kristian R. C.; Kundrapu, Madhusudhan; Stoltz, Peter H.

    2015-04-01

    Ion source rf antennas that produce H- ions can fail when plasma heating causes ablation of the insulating coating due to small structural defects such as cracks. Reducing antenna failures that reduce the operating capabilities of the Spallation Neutron Source (SNS) accelerator is one of the top priorities of the SNS H- Source Program at ORNL. Numerical modeling of ion sources can provide techniques for optimizing design in order to reduce antenna failures. There are a number of difficulties in developing accurate models of rf inductive plasmas. First, a large range of spatial and temporal scales must be resolved in order to accurately capture the physics of plasma motion, including the Debye length, rf frequencies on the order of tens of MHz, simulation time scales of many hundreds of rf periods, large device sizes on tens of cm, and ion motions that are thousands of times slower than electrons. This results in large simulation domains with many computational cells for solving plasma and electromagnetic equations, short time steps, and long-duration simulations. In order to reduce the computational requirements, one can develop implicit models for both fields and particle motions (e.g. divergence-preserving ADI methods), various electrostatic models, or magnetohydrodynamic models. We have performed simulations using all three of these methods and have found that fluid models have the greatest potential for giving accurate solutions while still being fast enough to perform long timescale simulations in a reasonable amount of time. We have implemented a number of fluid models with electromagnetics using the simulation tool USim and applied them to modeling the SNS H- ion source. We found that a reduced, single-fluid MHD model with an imposed magnetic field due to the rf antenna current and the confining multi-cusp field generated increased bulk plasma velocities of > 200 m/s in the region of the antenna where ablation is often observed in the SNS source. We report

  10. Molecular modeling of mechanosensory ion channel structural and functional features.

    Science.gov (United States)

    Gessmann, Renate; Kourtis, Nikos; Petratos, Kyriacos; Tavernarakis, Nektarios

    2010-09-16

    The DEG/ENaC (Degenerin/Epithelial Sodium Channel) protein family comprises related ion channel subunits from all metazoans, including humans. Members of this protein family play roles in several important biological processes such as transduction of mechanical stimuli, sodium re-absorption and blood pressure regulation. Several blocks of amino acid sequence are conserved in DEG/ENaC proteins, but structure/function relations in this channel class are poorly understood. Given the considerable experimental limitations associated with the crystallization of integral membrane proteins, knowledge-based modeling is often the only route towards obtaining reliable structural information. To gain insight into the structural characteristics of DEG/ENaC ion channels, we derived three-dimensional models of MEC-4 and UNC-8, based on the available crystal structures of ASIC1 (Acid Sensing Ion Channel 1). MEC-4 and UNC-8 are two DEG/ENaC family members involved in mechanosensation and proprioception respectively, in the nematode Caenorhabditis elegans. We used these models to examine the structural effects of specific mutations that alter channel function in vivo. The trimeric MEC-4 model provides insight into the mechanism by which gain-of-function mutations cause structural alterations that result in increased channel permeability, which trigger cell degeneration. Our analysis provides an introductory framework to further investigate the multimeric organization of the DEG/ENaC ion channel complex.

  11. Molecular modeling of mechanosensory ion channel structural and functional features.

    Directory of Open Access Journals (Sweden)

    Renate Gessmann

    Full Text Available The DEG/ENaC (Degenerin/Epithelial Sodium Channel protein family comprises related ion channel subunits from all metazoans, including humans. Members of this protein family play roles in several important biological processes such as transduction of mechanical stimuli, sodium re-absorption and blood pressure regulation. Several blocks of amino acid sequence are conserved in DEG/ENaC proteins, but structure/function relations in this channel class are poorly understood. Given the considerable experimental limitations associated with the crystallization of integral membrane proteins, knowledge-based modeling is often the only route towards obtaining reliable structural information. To gain insight into the structural characteristics of DEG/ENaC ion channels, we derived three-dimensional models of MEC-4 and UNC-8, based on the available crystal structures of ASIC1 (Acid Sensing Ion Channel 1. MEC-4 and UNC-8 are two DEG/ENaC family members involved in mechanosensation and proprioception respectively, in the nematode Caenorhabditis elegans. We used these models to examine the structural effects of specific mutations that alter channel function in vivo. The trimeric MEC-4 model provides insight into the mechanism by which gain-of-function mutations cause structural alterations that result in increased channel permeability, which trigger cell degeneration. Our analysis provides an introductory framework to further investigate the multimeric organization of the DEG/ENaC ion channel complex.

  12. Predictive Models of Li-ion Battery Lifetime (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Smith, K.; Wood, E.; Santhanagopalan, S.; Kim, G.; Shi, Y.; Pesaran, A.

    2014-09-01

    Predictive models of Li-ion battery reliability must consider a multiplicity of electrochemical, thermal and mechanical degradation modes experienced by batteries in application environments. Complicating matters, Li-ion batteries can experience several path dependent degradation trajectories dependent on storage and cycling history of the application environment. Rates of degradation are controlled by factors such as temperature history, electrochemical operating window, and charge/discharge rate. Lacking accurate models and tests, lifetime uncertainty must be absorbed by overdesign and warranty costs. Degradation models are needed that predict lifetime more accurately and with less test data. Models should also provide engineering feedback for next generation battery designs. This presentation reviews both multi-dimensional physical models and simpler, lumped surrogate models of battery electrochemical and mechanical degradation. Models are compared with cell- and pack-level aging data from commercial Li-ion chemistries. The analysis elucidates the relative importance of electrochemical and mechanical stress-induced degradation mechanisms in real-world operating environments. Opportunities for extending the lifetime of commercial battery systems are explored.

  13. Determination of stability constants of 5-(2-hydroxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione with copper(II) and mercury(II) ions

    OpenAIRE

    Bahram,Morteza; Pesyan, Nader Noroozi

    2011-01-01

    In this work, a hard model chemometric method was used to determine the stability constants of copper(II) and mercury(II) complexes with the newly synthesized ligand 5-(2-hydroxybenzylidene)- 2-thioxodihydropyrimidine-4,6(1H,5H)-dione in acetonitrile by UV-Vis spectrophotometry. The ligand forms stable complexes with both metal cations. The protonation constants of the ligand were also measured in an ethanol-water (1:1) mixture.

  14. An integrated systems model for heavy ion drivers

    Energy Technology Data Exchange (ETDEWEB)

    Bangerter, R O; Faltens, A; Meier, W R

    1998-09-02

    A source-to-target computer model for an induction linac driver for heavy ion fusion has been developed and used to define a reference case driver that meets the requirements of one current target design. Key features of the model are discussed, and the design parameters of the reference case design are described. Examples of the systems analyses leading to the point design are given, and directions for future work are noted.

  15. Quantum Model for the Selectivity Filter in K$^{+}$ Ion Channel

    CERN Document Server

    Cifuentes, A A

    2013-01-01

    In this work, we present a quantum transport model for the selectivity filter in the KcsA potassium ion channel. This model is fully consistent with the fact that two conduction pathways are involved in the translocation of ions thorough the filter, and we show that the presence of a second path may actually bring advantages for the filter as a result of quantum interference. To highlight interferences and resonances in the model, we consider the selectivity filter to be driven by a controlled time-dependent external field which changes the free energy scenario and consequently the conduction of the ions. In particular, we demonstrate that the two-pathway conduction mechanism is more advantageous for the filter when dephasing in the transient configurations is lower than in the main configurations. As a matter of fact, K$^+$ ions in the main configurations are highly coordinated by oxygen atoms of the filter backbone and this increases noise. Moreover, we also show that, for a wide range of driving frequencie...

  16. Markov modeling of ion channels: implications for understanding disease.

    Science.gov (United States)

    Lampert, Angelika; Korngreen, Alon

    2014-01-01

    Ion channels are the bridge between the biochemical and electrical domains of our life. These membrane crossing proteins use the electric energy stored in transmembrane ion gradients, which are produced by biochemical activity to generate ionic currents. Each ion channel can be imagined as a small power plant similar to a hydroelectric power station, in which potential energy is converted into electric current. This current drives basically all physiological mechanisms of our body. It is clear that a functional blueprint of these amazing cellular power plants is essential for understanding the principle of all aspects of physiology, particularly neurophysiology. The golden path toward this blueprint starts with the biophysical investigation of ion channel activity and continues through detailed numerical modeling of these channels that will eventually lead to a full system-level description of cellular and organ physiology. Here, we discuss the first two stages of this process focusing on voltage-gated channels, particularly the voltage-gated sodium channel which is neurologically and pathologically important. We first detail the correlations between the known structure of the channel and its activity and describe some pathologies. We then provide a hands-on description of Markov modeling for voltage-gated channels. These two sections of the chapter highlight the dichotomy between the vast amounts of electrophysiological data available on voltage-gated channels and the relatively meager number of physiologically relevant models for these channels.

  17. The transition from complex crater to peak-ring basin on Mercury: New observations from MESSENGER flyby data and constraints on basin formation models

    Science.gov (United States)

    Baker, David M. H.; Head, James W.; Schon, Samuel C.; Ernst, Carolyn M.; Prockter, Louise M.; Murchie, Scott L.; Denevi, Brett W.; Solomon, Sean C.; Strom, Robert G.

    2011-12-01

    The study of peak-ring basins and other impact crater morphologies transitional between complex craters and multi-ring basins is important to our understanding of the mechanisms for basin formation on the terrestrial planets. Mercury has the largest population, and the largest population per area, of peak-ring basins and protobasins in the inner solar system and thus provides important data for examining questions surrounding peak-ring basin formation. New flyby images from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have more than doubled the area of Mercury viewed at close range, providing nearly complete global coverage of the planet's surface when combined with flyby data from Mariner 10. We use this new near-global dataset to compile a catalog of peak-ring basins and protobasins on Mercury, including measurements of the diameters of the basin rim crest, interior ring, and central peak (if present). Our catalog increases the population of peak-ring basins by ˜150% and protobasins by ˜100% over previous catalogs, including 44 newly identified peak-ring basins (total=74) and 17 newly identified protobasins (total=32). A newly defined transitional basin type, the ringed peak-cluster basin (total=9), is also described. The new basin catalog confirms that Mercury has the largest population of peak-ring basins of the terrestrial planets and also places the onset rim-crest diameter for peak-ring basins at 126-26+33km, which is intermediate between the onset diameter for peak-ring basins on the Moon and those for the other terrestrial planets. The ratios of ring diameter to rim-crest diameter further emphasize that protobasins and peak-ring basins are parts of a continuum of basin morphologies relating to their processes of formation, in contrast to previous views that these forms are distinct. Comparisons of the predictions of peak-ring basin-formation models with the characteristics of the basin catalog for Mercury

  18. Measurement-based modeling of bromine-induced oxidation of mercury above the Dead Sea

    Directory of Open Access Journals (Sweden)

    E. Tas

    2011-08-01

    Full Text Available Atmospheric mercury depletion events (AMDEs outside the polar regions – driven by high levels of reactive bromine species (RBS – were observed recently in the warm Dead Sea boundary layer. Efficient oxidation of gaseous elemental mercury (GEM under temperate conditions by RBS was unexpected considering that the thermal back dissociation reaction of HgBr, a proposed key mechanism, is more than 2.5 orders of magnitude higher under Dead Sea temperatures compared with polar temperatures. The goal of this study was to improve understanding of RBS-mercury interactions using numerical simulations based on a comprehensive measurement campaign performed at the Dead Sea during summer 2009.

    Results demonstrate a high efficiency and central role of BrOx (i.e., Br + BrO for AMDEs at the Dead Sea, with relative contributions for GEM depletion of more than ~90 %. BrO was found to be the dominant oxidant with relative contribution above 80 %. Best agreement between simulations and observations was achieved by applying rate constants for kHg+Br and kHg+BrO of 2.7×10−13 cm3 molecule−1 s−1 and 1.5 × 10−13 cm3 molecule−1 s−1, respectively – indicating that kHg+BrO is higher than most reported values and that BrO is a more efficient oxidant than Br in the ozone-rich atmosphere (i.e., for [BrO]/[Br] >2. This further explains why the efficiency of GEM oxidation by reactive bromine species at the Dead Sea doesn't critically depend on Br and, therefore, is comparable to the efficiency in polar regions even under much higher temperatures. These findings also support the hypothesis identified in a previous study, that Br-induced GEM depletion can be important above oceans in the mid-latitudes and tropics. In the presence of anthropogenic NO2, RBS activity can lead to enhanced NO3

  19. Measurement-based modeling of bromine-induced oxidation of mercury above the Dead Sea

    Science.gov (United States)

    Tas, E.; Obrist, D.; Peleg, M.; Matveev, V.; Faïn, X.; Asaf, D.; Luria, M.

    2011-08-01

    Atmospheric mercury depletion events (AMDEs) outside the polar regions - driven by high levels of reactive bromine species (RBS) - were observed recently in the warm Dead Sea boundary layer. Efficient oxidation of gaseous elemental mercury (GEM) under temperate conditions by RBS was unexpected considering that the thermal back dissociation reaction of HgBr, a proposed key mechanism, is more than 2.5 orders of magnitude higher under Dead Sea temperatures compared with polar temperatures. The goal of this study was to improve understanding of RBS-mercury interactions using numerical simulations based on a comprehensive measurement campaign performed at the Dead Sea during summer 2009. Results demonstrate a high efficiency and central role of BrOx (i.e., Br + BrO) for AMDEs at the Dead Sea, with relative contributions for GEM depletion of more than ~90 %. BrO was found to be the dominant oxidant with relative contribution above 80 %. Best agreement between simulations and observations was achieved by applying rate constants for kHg+Br and kHg+BrO of 2.7×10-13 cm3 molecule-1 s-1 and 1.5 × 10-13 cm3 molecule-1 s-1, respectively - indicating that kHg+BrO is higher than most reported values and that BrO is a more efficient oxidant than Br in the ozone-rich atmosphere (i.e., for [BrO]/[Br] >2). This further explains why the efficiency of GEM oxidation by reactive bromine species at the Dead Sea doesn't critically depend on Br and, therefore, is comparable to the efficiency in polar regions even under much higher temperatures. These findings also support the hypothesis identified in a previous study, that Br-induced GEM depletion can be important above oceans in the mid-latitudes and tropics. In the presence of anthropogenic NO2, RBS activity can lead to enhanced NO3 formation, which then causes significant nighttime GEM depletion.

  20. 模拟烟气中炭质颗粒的汞吸附模型%Modeling mercury adsorption on carbon particles in simulated flue gas

    Institute of Scientific and Technical Information of China (English)

    王立刚; 陈昌和; Kruse H.Kolker

    2006-01-01

    根据残炭和活性炭的穿透吸附试验数据,提出了残炭吸附等温线的数学模型.通过所取微元内气相汞和固相汞的总量平衡关系建立相关微分方程组,并运用Matlab软件结合Runge-Kutta过程推导出适用模型.穿透试验结果表明:在与电厂烟气汞浓度相近的低汞浓度条件下(<0.3 mg/m3),残炭的吸附等温线符合Freundich理论的Ⅱ型等温线,而活性炭的数据则明显具有Langmuir关系,即属于Ⅲ型等温线.运用Matlab软件将实验数据对修正模型进行拟合计算,经过统计分析,出口汞浓度数据方差不超过0.81,表明在允许的误差范围内,测试数据和模拟结果令人满意.该模型对汞吸附脱除效率预测和炭质吸附剂的汞吸附富集机理研究有重要意义.%A model was developed to describe the adsorption characteristic of mercury in flue gas based on one residual carbon sample and one activated carbon sample. The differential equations were established with mass balance of mercury in the gas phase and in the solid phase. Then the model was solved using a Matlab program with a Runge-Kutta process. The mercury adsorption isotherms of these two adsorbents were obtained by breakthrough column experiments. The results show that at low gas phase mercury concentrations ( <0.3 mg/m3), the adsorption equilibrium of residual carbon is in accord with the case of a type Ⅱ isotherm of the Freundich theory. Whereas the data of activated carbon falls into the Langmuir relationship, it is the case of a type Ⅲ isotherm. The experimental data were fitted to the Freundlich model by Matlab software. The variances of mercury concentration are smaller than 0. 81 which implies the agreement between measurements and simulation is quite agreeable considering the wide scatter of the measurements. This model is useful for forecasting mercury removal efficiency and is helpful to the mechanism analysis of mercury adsorption on carbon-based adsorbent.

  1. PIC modeling of negative ion sources for fusion

    Science.gov (United States)

    Taccogna, F.; Minelli, P.

    2017-01-01

    This work represents the first attempt to model the full-size ITER negative ion source prototype including expansion, extraction and part of the acceleration regions keeping the resolution fine enough to resolve every single aperture of the extraction grid. The model consists of a 2.5-dimensional Particle-in-Cell/Monte Carlo Collision representation of the plane perpendicular to the filter field lines. Both the magnetic filter and electron deflection fields have been included. A negative ion current density of {j}{H-}=500 {{A}} {{{m}}}-2 produced by neutral conversion from the plasma grid is used as fixed parameter, while negative ions produced by electron dissociative attachment of vibrationally excited molecules and by ionic conversion on plasma grid are self-consistently simulated. Results show the non-ambipolar character of the transport in the expansion region driven by electron magnetic drifts in the plane perpendicular to the filter field. It induces a top-bottom asymmetry detected up to the extraction grid which in turn leads to a tilted positive ion flow hitting the plasma grid and a tilted negative ion flow emitted from the plasma grid. As a consequence, the plasma structure is not uniform around the single aperture: the meniscus assumes a form of asymmetric lobe and a deeper potential well is detected from one side of the aperture relative to the other side. Therefore, the surface-produced contribution to the negative ion extraction is not equally distributed between both the sides around the aperture but it come mainly from the lower side of the grid giving an asymmetrical current distribution in the single beamlet.

  2. Ghezeljeh nanoclay as a new natural adsorbent for the removal of copper and mercury ions:Equilibrium, kinetics and thermodynamics studies

    Institute of Scientific and Technical Information of China (English)

    Majid Soleimani⁎; Zahra Hassanzadeh Siahpoosh

    2015-01-01

    Heavy metal determination was carried out by applying the solid phase extraction (SPE) method in batch mode followed by atomic absorption spectroscopy (AAS) and inductively coupled plasma atomic emission spectrosco-py (ICP-AES) from aqueous solutions using Ghezeljeh montmoril onite nanoclay as a new natural adsorbent. The Ghezeljeh clay is characterized by using Fourier Transform Infrared (FT-IR) Spectroscopy, Scanning Electron Mi-croscopy–Energy Dispersive Spectrometry (SEM–EDS) and X-ray Diffractometry (XRD) and X-ray Fluorescence (XRF). The results of XRD and FT-IR of nanoclay confirm that montmoril onite is the dominant mineral phase. Based on SEM images of Ghezeljeh clay, it can be seen that the distance between the plates is Nano. The effects of varying parameters such as initial concentration of metal ions, pH and type of buffer solutions, amount of ad-sorbent, contact time, and temperature on the adsorption process were examined. The effect of various interfer-ing ions was studied. The adsorption data correlated with Freundlich, Langmuir, Dubinin–Radushkevich (D–R), and Temkin isotherms. The Langmuir and Freundlich isotherms showed the best fit to the equilibrium data for Hg(I ), but the equilibrium nature of Cu(II) adsorption has been described by the Langmuir isotherm. The kinetic data were described with pseudo-first-order, pseudo-second-order and double-exponential models. The adsorp-tion process follows a pseudo-second-order reaction scheme. Calculation ofΔG0,ΔH0 andΔS0 showed that the nature of Hg(II) ion sorption onto the Ghezeljeh nanoclay was endothermic and was favored at higher temper-ature, and the nature of Cu(II) ion sorption was exothermic and was favored at lower temperature.

  3. Potential sources and processes affecting speciated atmospheric mercury at Kejimkujik National Park, Canada: comparison of receptor models and data treatment methods

    Science.gov (United States)

    Xu, Xiaohong; Liao, Yanyin; Cheng, Irene; Zhang, Leiming

    2017-01-01

    Source apportionment analysis was conducted with positive matrix factorization (PMF) and principal component analysis (PCA) methods using concentrations of speciated mercury (Hg), i.e., gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM), and other air pollutants collected at Kejimkujik National Park, Nova Scotia, Canada, in 2009 and 2010. The results were largely consistent between the 2 years for both methods. The same four source factors were identified in each year using PMF method. In both years, factor photochemistry and re-emission had the largest contributions to atmospheric Hg, while the contributions of combustion emission and industrial sulfur varied slightly between the 2 years. Four components were extracted with air pollutants only in each year using PCA method. Consistencies between the results of PMF and PCA include (1) most or all PMF factors overlapped with PCA components, (2) both methods suggest strong impact of photochemistry but little association between ambient Hg and sea salt, and (3) shifting of PMF source profiles and source contributions from one year to another was echoed in PCA. Inclusion of meteorological parameters led to identification of an additional component, Hg wet deposition in PCA, while it did not affect the identification of other components. The PMF model performance was comparable in 2009 and 2010. Among the three Hg forms, the agreements between model-reproduced and observed annual mean concentrations were excellent for GEM, very good for PBM, and acceptable for GOM. However, on a daily basis, the agreement was very good for GEM but poor for GOM and PBM. Sensitivity tests suggest that increasing sample size by imputation is not effective in improving model performance, while reducing the fraction of concentrations below method detection limit, by either scaling GOM and PBM to higher concentrations or combining them to reactive mercury, is effective. Most of the data

  4. Aqueous mercury adsorption by activated carbons.

    Science.gov (United States)

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies.

  5. Small Mercury Relativity Orbiter

    Science.gov (United States)

    Bender, Peter L.; Vincent, Mark A.

    1989-01-01

    The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

  6. MESSENGER observations of the composition of Mercury's ionized exosphere and plasma environment.

    Science.gov (United States)

    Zurbuchen, Thomas H; Raines, Jim M; Gloeckler, George; Krimigis, Stamatios M; Slavin, James A; Koehn, Patrick L; Killen, Rosemary M; Sprague, Ann L; McNutt, Ralph L; Solomon, Sean C

    2008-07-04

    The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na+, O+, and K+ abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S+ and H2S+, with (S+ + H2S+)/(Na+ + Mg+) = 0.67 +/- 0.06, and from water-group ions around m/q = 18, at an abundance of 0.20 +/- 0.03 relative to Na+ plus Mg+. The fluxes of Na+, O+, and heavier ions are largest near the planet, but these Mercury-derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere.

  7. Performance Evaluation of the Prototype Model NEXT Ion Thruster

    Science.gov (United States)

    Herman, Daniel A.; Soulas, George C.; Patterson, Michael J.

    2008-01-01

    The performance testing results of the first prototype model NEXT ion engine, PM1, are presented. The NEXT program has developed the next generation ion propulsion system to enhance and enable Discovery, New Frontiers, and Flagship-type NASA missions. The PM1 thruster exhibits operational behavior consistent with its predecessors, the engineering model thrusters, with substantial mass savings, enhanced thermal margins, and design improvements for environmental testing compliance. The dry mass of PM1 is 12.7 kg. Modifications made in the thruster design have resulted in improved performance and operating margins, as anticipated. PM1 beginning-of-life performance satisfies all of the electric propulsion thruster mission-derived technical requirements. It demonstrates a wide range of throttleability by processing input power levels from 0.5 to 6.9 kW. At 6.9 kW, the PM1 thruster demonstrates specific impulse of 4190 s, 237 mN of thrust, and a thrust efficiency of 0.71. The flat beam profile, flatness parameters vary from 0.66 at low-power to 0.88 at full-power, and advanced ion optics reduce localized accelerator grid erosion and increases margins for electron backstreaming, impingement-limited voltage, and screen grid ion transparency. The thruster throughput capability is predicted to exceed 750 kg of xenon, an equivalent of 36,500 hr of continuous operation at the full-power operating condition.

  8. An integrative model of ion regulation in yeast.

    Science.gov (United States)

    Ke, Ruian; Ingram, Piers J; Haynes, Ken

    2013-01-01

    Yeast cells are able to tolerate and adapt to a variety of environmental stresses. An essential aspect of stress adaptation is the regulation of monovalent ion concentrations. Ion regulation determines many fundamental physiological parameters, such as cell volume, membrane potential, and intracellular pH. It is achieved through the concerted activities of multiple cellular components, including ion transporters and signaling molecules, on both short and long time scales. Although each component has been studied in detail previously, it remains unclear how the physiological parameters are maintained and regulated by the concerted action of all components under a diverse range of stress conditions. In this study, we have constructed an integrated mathematical model of ion regulation in Saccharomyces cerevisiae to understand this coordinated adaptation process. Using this model, we first predict that the interaction between phosphorylated Hog1p and Tok1p at the plasma membrane inhibits Tok1p activity and consequently reduces Na(+) influx under NaCl stress. We further characterize the impacts of NaCl, sorbitol, KCl and alkaline pH stresses on the cellular physiology and the differences between the cellular responses to these stresses. We predict that the calcineurin pathway is essential for maintaining a non-toxic level of intracellular Na(+) in the long-term adaptation to NaCl stress, but that its activation is not required for maintaining a low level of Na(+) under other stresses investigated. We provide evidence that, in addition to extrusion of toxic ions, Ena1p plays an important role, in some cases alongside Nha1p, in re-establishing membrane potential after stress perturbation. To conclude, this model serves as a powerful tool for both understanding the complex system-level properties of the highly coordinated adaptation process and generating further hypotheses for experimental investigation.

  9. An integrative model of ion regulation in yeast.

    Directory of Open Access Journals (Sweden)

    Ruian Ke

    Full Text Available Yeast cells are able to tolerate and adapt to a variety of environmental stresses. An essential aspect of stress adaptation is the regulation of monovalent ion concentrations. Ion regulation determines many fundamental physiological parameters, such as cell volume, membrane potential, and intracellular pH. It is achieved through the concerted activities of multiple cellular components, including ion transporters and signaling molecules, on both short and long time scales. Although each component has been studied in detail previously, it remains unclear how the physiological parameters are maintained and regulated by the concerted action of all components under a diverse range of stress conditions. In this study, we have constructed an integrated mathematical model of ion regulation in Saccharomyces cerevisiae to understand this coordinated adaptation process. Using this model, we first predict that the interaction between phosphorylated Hog1p and Tok1p at the plasma membrane inhibits Tok1p activity and consequently reduces Na(+ influx under NaCl stress. We further characterize the impacts of NaCl, sorbitol, KCl and alkaline pH stresses on the cellular physiology and the differences between the cellular responses to these stresses. We predict that the calcineurin pathway is essential for maintaining a non-toxic level of intracellular Na(+ in the long-term adaptation to NaCl stress, but that its activation is not required for maintaining a low level of Na(+ under other stresses investigated. We provide evidence that, in addition to extrusion of toxic ions, Ena1p plays an important role, in some cases alongside Nha1p, in re-establishing membrane potential after stress perturbation. To conclude, this model serves as a powerful tool for both understanding the complex system-level properties of the highly coordinated adaptation process and generating further hypotheses for experimental investigation.

  10. 基于二氟化硼-二吡咯甲烷(BODIPY)染料类汞离子荧光探针的研究进展%Progress of fluorescent probes for mercury ions based on bipyrrometheneboron difluoride (BODIPY) dyes

    Institute of Scientific and Technical Information of China (English)

    徐海云; 胡春华; 刘瑛

    2012-01-01

    As one of the most toxic chemicals, mercury ion can give rise to severe harm to human and environment. Hence its chemical sensing methods are widely studied. Fluorescent probe has been one of the most important sensing methods for mercury ion,due to its excellent advantages such as high sensitivity, convenient and fast detection. BODIPY-based fluorescent probes for mercury ion reported in recent years are summarized. The design and synthesis of probe molecules as well as their sensing mechanisms are described , the development is also prospected in the field of BODIPY-based fluorescent probes for mercury ions.%Hg2+是一种极具生理毒性的化学物质,对人类和环境危害极大,其检测方法在化学传感器领域得到广泛研究.荧光探针法因具有检测灵敏度高、快速便捷等优点而成为Hg2+检测的重要手段之一.综述了近年来BODIPY类染料汞离子的研究进展,着重总结了Hg2+荧光探针的设计合成、性能及其检测机制;展望了该类荧光探针的研究方向.

  11. Removal of mercury (II) from aqueous solution using papain immobilized on alginate bead: optimization of immobilization condition and modeling of removal study.

    Science.gov (United States)

    Bhattacharyya, Aparupa; Dutta, Susmita; De, Parameswar; Ray, Parthasarathi; Basu, Srabanti

    2010-12-01

    Papain having the characteristics of metal binding ability is immobilized on alginate bead. Design Expert Software (Version 7.1.6) uses Response Surface Methodology (RSM) for statistical designing of operating condition for immobilization of papain on alginate bead considering concentration of papain, concentration of sodium alginate, concentration of calcium chloride and pH as numeric factors and Specific Enzymatic Activity (SEA) of immobilized papain sample as response. Immobilization using 25.96 g/L papain, 20 g/L sodium alginate and 20 g/L calcium chloride at pH 7 gives the desired product as indicated by ANOVA (Analysis of Variance). Three parameters viz., initial concentration of mercury (II), amount of AIP and pH are varied in a systematic manner. Maximum 98.88% removal of mercury (II) has been achieved within 8 min when simulated aqueous solution of mercury (II) with initial concentration of 10mg/L has been contacted with 5 g of AIP at pH 9 and at 35 degrees C in a batch contactor. A mathematical model has been developed and the value of equilibrium constant for binding of mercury (II) with AIP has been found to be 126797.3.

  12. Modeling for mean ion activity coefficient of strong electrolyte system with new boundary conditions and ion-size parameters

    Institute of Scientific and Technical Information of China (English)

    Miyi Li; Tao Fang

    2015-01-01

    A rigorous approach is proposed to model the mean ion activity coefficient for strong electrolyte systems using the Poisson–Boltzmann equation. An effective screening radius similar to the Debye decay length is introduced to define the local composition and new boundary conditions for the central ion. The crystallographic ion size is also considered in the activity coefficient expressions derived and non-electrostatic contributions are neglected. The model is presented for aqueous strong electrolytes and compared with the classical Debye–Hückel (DH) limiting law for dilute solutions. The radial distribution function is compared with the DH and Monte Carlo studies. The mean ion activity coefficients are calculated for 1:1 aqueous solutions containing strong electrolytes composed of alkali halides. The individual ion activity coefficients and mean ion activity coefficients in mixed sol-vents are predicted with the new equations.

  13. Modelling interaction cross sections for intermediate and low energy ions

    Energy Technology Data Exchange (ETDEWEB)

    Toburen, L.H.; Shinpaugh, J.L.; Justiniano, E.L.B

    2002-07-01

    When charged particles slow in tissue they undergo electron capture and loss processes than can have profound effects on subsequent interaction cross sections. Although a large amount of data exists for the interaction of bare charged particles with atoms and molecules, few experiments have been reported for these 'dressed' particles. Projectile electrons contribute to an impact-parameter-dependent screening of the projectile charge that precludes straightforward scaling of energy loss cross sections from those of bare charged particles. The objective of this work is to develop an analytical model for the energy-loss-dependent effects of screening on differential ionisation cross sections that can be used in track structure calculations for high LET ions. As a first step a model of differential ionisation cross sections for bare ions has been combined with a simple screening model to explore cross sections for intermediate and low energy dressed ions in collisions with atomic and molecular gas targets. The model is described briefly and preliminary results compared to measured electron energy spectra. (author)

  14. Modelling interaction cross sections for intermediate and low energy ions.

    Science.gov (United States)

    Toburen, L H; Shinpaugh, J L; Justiniano, E L B

    2002-01-01

    When charged particles slow in tissue they undergo electron capture and loss processes that can have profound effects on subsequent interaction cross sections. Although a large amount of data exists for the interaction of bare charged particles with atoms and molecules, few experiments have been reported for these 'dressed' particles. Projectile electrons contribute to an impact-parameter-dependent screening of the projectile charge that precludes straightforward scaling of energy loss cross sections from those of bare charged particles. The objective of this work is to develop an analytical model for the energy-loss-dependent effects of screening on differential ionisation cross sections that can be used in track structure calculations for high LET ions. As a first step a model of differential ionisation cross sections for bare ions has been combined with a simple screening model to explore cross sections for intermediate and low energy dressed ions in collisions with atomic and molecular gas targets. The model is described briefly and preliminary results compared to measured ejected electron energy spectra.

  15. Toward a Unified Understanding of Mercury and Methylated Mercury from the World's Oceans

    Science.gov (United States)

    McNutt, M. K.; Krabbenhoft, D. P.; Landing, W. M.; Sunderland, E. M.

    2012-12-01

    -profile concentration maxima, however, the depth of the maxima are more varied than the total mercury profiles (150 - 700m). Also, our observed distribution of methylated mercury highly correlated with organic carbon remineralization rates (OCRR) in the North Pacific and Indian Oceans. Interestingly, we find the highest methylated mercury concentrations in the Southern Ocean, suggesting the possibility of unique mechanisms for methylmercury production, preservation, and degradation in polar ecosystems such as cold water temperatures, extended periods of sea ice cover, and annual atmospheric mercury depletion events. We are using these data to better link oceanic production of bioaccumulative mercury to models for atmospheric and oceanic transport and bioaccumulation. This will ultimately lead to a better understanding of mercury levels in consumable fish and shell fish.

  16. Two models with rescattering for high energy heavy ion collisions

    Science.gov (United States)

    Bøggild, H.; Hansen, Ole; Humanic, T. J.

    2006-12-01

    The effects of hadronic rescattering in high energy relativistic Au+Au collisions are studied using two very different models to describe the early stages of the collision. One model is based on a hadronic thermal picture and the other on a superposition of parton-parton collisions. Operationally, the output hadrons from each of these models are used as input to a hadronic rescattering calculation. The results of the rescattering calculations from each model are then compared with rapidity and transverse momentum distributions from the BNL Relativistic Heavy Ion Collider BRAHMS experiment. In spite of the different points of view of the two models of the initial stage, after rescattering, the observed differences between the models are mostly “washed out” and both models give observables that agree roughly with each other and with experimental data.

  17. Mercuric ion attenuates nuclear factor-kappaB activation and DNA binding in normal rat kidney epithelial cells: implications for mercury-induced nephrotoxicity.

    Science.gov (United States)

    Dieguez-Acuña, F J; Ellis, M E; Kushleika, J; Woods, J S

    2001-06-15

    Mercuric ion (Hg(2+)), one of the strongest thiol-binding agents known, mediates the toxicity associated with elemental, inorganic, and organic mercurial compounds. Studies of cellular events associated with Hg(2+) toxicity have focused largely on disruption of cell membranes and impairment of mitochondrial functions. In contrast, few studies have sought to define the specific molecular mechanisms through which Hg(2+) might affect toxicity via alteration of thiol-dependent signal transduction pathways that regulate cell proliferation and survival. Of particular interest in this regard is the effect of Hg(2+) on nuclear factor-kappaB (NF-kappaB), a pleiotropic transcriptional factor that is known to require reduced cysteine moieties at critical steps of activation and DNA binding. Here, we evaluated the effects of Hg(2+) on the expression of NF-kappaB in normal rat kidney epithelial (NRK52E) cells, a principal target of Hg(2+) toxicity. The lipopolysaccharide (LPS)-inducible form of NF-kappaB was readily detected in kidney cells and has been characterized as the p50p65 heterodimer. NF-kappaB-DNA binding was prevented in a dose-related manner by Hg(2+) (0-55 microM) in vitro when added to DNA binding reactions containing the nonthiol reducing agent Tris(2-carboxyethyl)phosphine hydrochloride (TCEP). Similarly, Hg(2+) at the same concentrations prevented DNA binding of a human recombinant wild-type p50p50 homodimer in binding reactions, and this effect was attenuated using a mutant form of the p50 protein containing a cys(62)-->ser(62) mutation. The inhibition of p50-DNA binding by Hg(2+) was reversible in a dose-related manner in vitro by competitive thiols DTT, GSH, and l-cysteine in binding reactions. In contrast, competitive thiols added to nuclear binding reactions were unable to reverse attenuation of LPS-mediated NF-kappaB-DNA binding affinity when cells were pretreated in vivo with Hg(2+) at concentrations as low as 2 microM prior to LPS administration

  18. Heavy ion tracks in polycarbonate. Comparison with a heavy ion irradiated model compound (diphenyl carbonate)

    Science.gov (United States)

    Ferain, E.; Legras, R.

    1993-09-01

    The chemical modifications induced by energetic heavy ion irradiation of polycarbonate (PC) film are determined by GPC, HPLC, ESR, TGA, IR and UV spectrophotometry. The main results of the irradiation are creation of radicals, chain scission, cross-linking and appearance of new chemical groups in the main polymer chain. As far as the creation of new groups is concerned, they are determined by means of a model compound of PC: the diphenyl carbonate (DPC). The following compounds are identified after energetic heavy ion irradiation of DPC: salicylic acid, phenol, 4,4'-biphenol, 2,4'-biphenol, 2,2'-biphenol, 4-phenoxyphenol, 2-phenoxyphenol, phenyl ether, phenyl benzoate, phenyl salicylate, 2-phenylphenol and 2-phenoxyphenyl benzoate. A similarity between the heavy ion irradiation and a heat treatment has also been established with DPC. On the basis of these results, we try to give an explanation of the preferential attack along the tracks of the irradiated film. Also, an explanation of the well-known beneficial effect of an UV exposition of the irradiated film on the selectivity of this preferential chemical attack is suggested.

  19. Predictive Models of Li-ion Battery Lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Kandler; Wood, Eric; Santhanagopalan, Shriram; Kim, Gi-heon; Shi, Ying; Pesaran, Ahmad

    2015-06-15

    It remains an open question how best to predict real-world battery lifetime based on accelerated calendar and cycle aging data from the laboratory. Multiple degradation mechanisms due to (electro)chemical, thermal, and mechanical coupled phenomena influence Li-ion battery lifetime, each with different dependence on time, cycling and thermal environment. The standardization of life predictive models would benefit the industry by reducing test time and streamlining development of system controls.

  20. Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models

    Science.gov (United States)

    Angot, Hélène; Dastoor, Ashu; De Simone, Francesco; Gårdfeldt, Katarina; Gencarelli, Christian N.; Hedgecock, Ian M.; Langer, Sarka; Magand, Olivier; Mastromonaco, Michelle N.; Nordstrøm, Claus; Pfaffhuber, Katrine A.; Pirrone, Nicola; Ryjkov, Andrei; Selin, Noelle E.; Skov, Henrik; Song, Shaojie; Sprovieri, Francesca; Steffen, Alexandra; Toyota, Kenjiro; Travnikov, Oleg; Yang, Xin; Dommergue, Aurélien

    2016-08-01

    Mercury (Hg) is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions to deposition of Hg onto environmental surfaces, large uncertainties arise from our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission). Atmospheric Hg reactivity is exacerbated in high latitudes and there is still much to be learned from polar regions in terms of atmospheric processes. This paper provides a synthesis of the atmospheric Hg monitoring data available in recent years (2011-2015) in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. The cycle of atmospheric Hg in the Arctic and in Antarctica presents both similarities and differences. Coastal sites in the two regions are both influenced by springtime atmospheric Hg depletion events and by summertime snowpack re-emission and oceanic evasion of Hg. The cycle of atmospheric Hg differs between the two regions primarily because of their different geography. While Arctic sites are significantly influenced by northern hemispheric Hg emissions especially in winter, coastal Antarctic sites are significantly influenced by the reactivity observed on the East Antarctic ice sheet due to katabatic winds. Based on the comparison of multi-model simulations with observations, this paper discusses whether the processes that affect atmospheric Hg seasonality and interannual variability are appropriately represented in the models and identifies research gaps in our understanding of the atmospheric Hg cycling in high latitudes.

  1. Monte Carlo modeling of ion beam induced secondary electrons

    Energy Technology Data Exchange (ETDEWEB)

    Huh, U., E-mail: uhuh@vols.utk.edu [Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996-0840 (United States); Cho, W. [Electrical and Computer Engineering, University of Tennessee, Knoxville, TN 37996-2100 (United States); Joy, D.C. [Biochemistry & Cellular & Molecular Biology, University of Tennessee, Knoxville, TN 37996-0840 (United States); Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2016-09-15

    Ion induced secondary electrons (iSE) can produce high-resolution images ranging from a few eV to 100 keV over a wide range of materials. The interpretation of such images requires knowledge of the secondary electron yields (iSE δ) for each of the elements and materials present and as a function of the incident beam energy. Experimental data for helium ions are currently limited to 40 elements and six compounds while other ions are not well represented. To overcome this limitation, we propose a simple procedure based on the comprehensive work of Berger et al. Here we show that between the energy range of 10–100 keV the Berger et al. data for elements and compounds can be accurately represented by a single universal curve. The agreement between the limited experimental data that is available and the predictive model is good, and has been found to provide reliable yield data for a wide range of elements and compounds. - Highlights: • The Universal ASTAR Yield Curve was derived from data recently published by NIST. • IONiSE incorporated with the Curve will predict iSE yield for elements and compounds. • This approach can also handle other ion beams by changing basic scattering profile.

  2. Immobilization of mercury by carboxymethyl cellulose stabilized iron sulfide nanoparticles: reaction mechanisms and effects of stabilizer and water chemistry.

    Science.gov (United States)

    Gong, Yanyan; Liu, Yuanyuan; Xiong, Zhong; Zhao, Dongye

    2014-04-01

    Iron sulfide (FeS) nanoparticles were prepared with sodium carboxymethyl cellulose (CMC) as a stabilizer, and tested for enhanced removal of aqueous mercury (Hg(2+)). CMC at ≥0.03 wt % fully stabilized 0.5 g/L of FeS (i.e., CMC-to-FeS molar ratio ≥0.0006). FTIR spectra suggested that CMC molecules were attached to the nanoparticles through bidentate bridging and hydrogen bonding. Increasing the CMC-to-FeS molar ratio from 0 to 0.0006 enhanced mercury sorption capacity by 20%; yet, increasing the ratio from 0.0010 to 0.0025 diminished the sorption by 14%. FTIR and XRD analyses suggested that precipitation (formation of cinnabar and metacinnabar), ion exchange (formation of Hg0.89Fe0.11S), and surface complexation were important mechanisms for mercury removal. A pseudo-second-order kinetic model was able to interpret the sorption kinetics, whereas a dual-mode isotherm model was proposed to simulate the isotherms, which considers precipitation and adsorption. High mercury uptake was observed over the pH range of 6.5-10.5, whereas significant capacity loss was observed at pH 106 mg/L) and organic matter (5 mg/L as TOC) modestly inhibited mercury uptake. The immobilized mercury remained stable when preserved for 2.5 years at pH above neutral.

  3. Multi-ion conduction bands in a simple model of calcium ion channels

    CERN Document Server

    Kaufman, I; Tindjong, R; McClintock, P V E; Eisenberg, R S

    2012-01-01

    We report self-consistent Brownian dynamics simulations of a simple electrostatic model of the selectivity filters (SF) of calcium ion channels. They reveal regular structure in the conductance and selectivity as functions of the fixed negative charge Qf at the SF. This structure comprises distinct regions of high conductance (conduction bands) M0, M1, M2 separated by regions of zero-conductance (stop-bands). Two of these conduction bands, M1 and M2, demonstrate high calcium selectivity and prominent anomalous mole fraction effects and can be identified with the L-type and RyR calcium channels.

  4. Mercury contamination extraction

    Science.gov (United States)

    Fuhrmann, Mark; Heiser, John; Kalb, Paul

    2009-09-15

    Mercury is removed from contaminated waste by firstly applying a sulfur reagent to the waste. Mercury in the waste is then permitted to migrate to the reagent and is stabilized in a mercury sulfide compound. The stable compound may then be removed from the waste which itself remains in situ following mercury removal therefrom.

  5. Fluvial transport of mercury, organic carbon, suspended sediment, and selected major ions in contrasting stream basins in South Carolina and New York, October 2004 to September 2009

    Science.gov (United States)

    Journey, Celeste; Burns, Douglas A.; Riva-Murray, Karen; Brigham, Mark E.; Button, Daniel T.; Feaster, Toby D.; Petkewich, Matthew D.; Bradley, Paul M.

    2012-01-01

    A spatially extensive assessment of the environmental controls on mercury transport and bioaccumulation in stream ecosystems in New York and South Carolina was conducted as part of the U.S. Geological Survey National Water-Quality Assessment Program and included the determination of fluvial transport of mercury and associated constituents during water years 2005–2009. (A water year extends from October of one calendar year to September of the next calendar year.) In the Coastal Plain region of South Carolina, the study area included the Edisto River and its headwater tributary, McTier Creek. In the Adirondack region of New York, the study area included the upper Hudson River and its headwater tributary, Fishing Brook. Median concentrations of filtered total mercury rangedfrom 1.55 nanograms per liter (ng/L) at the Hudson River site to 2.77 ng/L at the Edisto River site. The Edisto River site had the greatest median filtered methylmercury concentration, at 0.32 ng/L, and the Hudson River site had the least median filtered methylmercury concentration, at 0.07 ng/L.

  6. Migration and entrapment of mercury in porous media

    Science.gov (United States)

    Devasena, M.; Nambi, Indumathi M.

    2010-09-01

    Elemental mercury is an immiscible liquid with high density and high interfacial tension with water. Its movement in the saturated subsurface region is therefore considered as a case of two phase flow involving mercury and water and is expected to be governed by gravity, viscous, hydrodynamic and capillary forces. This paper investigates the migration and capillary entrapment of mercury in the subsurface based on controlled laboratory capillary pressure-saturation experiments. In the first place, entrapment of mercury was observed in homogeneous porous media. Residual mercury saturation and van Genuchten's parameters for mercury entrapment were generated. These data will provide vital inputs for mercury migration and entrapment models. Secondly, the dependency of residual saturation on fluid properties was brought out in this work by comparing the experimental results of mercury-water system and DNAPL-water systems. Capillary forces were large enough in mercury-water systems to counteract the high gravity forces and caused the entrapment of mercury. Large density differences between mercury and water lead to a high Bond number and thus a low residual mercury saturation was obtained which corroborates with existing DNAPL theories. However, the inverse relationship between residual saturation and capillary number established for NAPL-water systems cannot be compared with mercury-water systems. Moreover, the critical capillary numbers and Bond numbers to mobilize DNAPLs may not be applicable to mercury since mercury has a low capillary number and high Bond number. This work has enabled the understanding of the process of migration and entrapment of mercury and provided useful inputs for two phase flow models specific to mercury-water systems. It has also highlighted the influence of fluid properties on entrapment and mobilization particularly for highly dense, viscous fluid which also possesses high interfacial tension with water.

  7. Mercury and health care

    Directory of Open Access Journals (Sweden)

    Rustagi Neeti

    2010-01-01

    Full Text Available Mercury is toxic heavy metal. It has many characteristic features. Health care organizations have used mercury in many forms since time immemorial. The main uses of mercury are in dental amalgam, sphygmomanometers, and thermometers. The mercury once released into the environment can remain for a longer period. Both acute and chronic poisoning can be caused by it. Half of the mercury found in the atmosphere is human generated and health care contributes the substantial part to it. The world has awakened to the harmful effects of mercury. The World Health Organization and United Nations Environmental Programme (UNEP have issued guidelines for the countries′ health care sector to become mercury free. UNEP has formed mercury partnerships between governments and other stakeholders as one approach to reducing risks to human health and the environment from the release of mercury and its compounds to the environment. Many hospitals are mercury free now.

  8. Mercury and health care

    Science.gov (United States)

    Rustagi, Neeti; Singh, Ritesh

    2010-01-01

    Mercury is toxic heavy metal. It has many characteristic features. Health care organizations have used mercury in many forms since time immemorial. The main uses of mercury are in dental amalgam, sphygmomanometers, and thermometers. The mercury once released into the environment can remain for a longer period. Both acute and chronic poisoning can be caused by it. Half of the mercury found in the atmosphere is human generated and health care contributes the substantial part to it. The world has awakened to the harmful effects of mercury. The World Health Organization and United Nations Environmental Programme (UNEP) have issued guidelines for the countries’ health care sector to become mercury free. UNEP has formed mercury partnerships between governments and other stakeholders as one approach to reducing risks to human health and the environment from the release of mercury and its compounds to the environment. Many hospitals are mercury free now. PMID:21120080

  9. Mercury and health care.

    Science.gov (United States)

    Rustagi, Neeti; Singh, Ritesh

    2010-08-01

    Mercury is toxic heavy metal. It has many characteristic features. Health care organizations have used mercury in many forms since time immemorial. The main uses of mercury are in dental amalgam, sphygmomanometers, and thermometers. The mercury once released into the environment can remain for a longer period. Both acute and chronic poisoning can be caused by it. Half of the mercury found in the atmosphere is human generated and health care contributes the substantial part to it. The world has awakened to the harmful effects of mercury. The World Health Organization and United Nations Environmental Programme (UNEP) have issued guidelines for the countries' health care sector to become mercury free. UNEP has formed mercury partnerships between governments and other stakeholders as one approach to reducing risks to human health and the environment from the release of mercury and its compounds to the environment. Many hospitals are mercury free now.

  10. Competitive Adsorption of Cadmium(II and Mercury(II Ions from Aqueous Solutions by Activated Carbon from Xanthoceras sorbifolia Bunge Hull

    Directory of Open Access Journals (Sweden)

    Xiaotao Zhang

    2016-01-01

    Full Text Available This paper presents low-cost and recyclable activated carbon (XLAC derived from Xanthoceras sorbifolia Bunge hull for high-efficiency adsorption of Cd(II and Hg(II ions in industrial wastewater. XLAC was prepared through H3PO4 activation and was characterized using N2 adsorption-desorption, scanning electron microscopy (SEM, energy-dispersive spectroscopy (EDX, and Fourier transform infrared (FTIR spectroscopy. In single-metal-system adsorption experiments, the maximum adsorption capacities for Cd(II and Hg(II obtained under different experimental conditions were 388.7 and 235.6 mg·g−1, respectively. All adsorption equilibrium data fit perfectly with the Langmuir isotherm model. In a binary metal system, competitive studies demonstrated that the presence of Cd(II significantly decreased the adsorption of Hg(II, but the adsorption of Cd(II showed a little change in the presence of Hg(II. In addition, XLAC can be regenerated with a 0.01 mol·L−1 HNO3 solution and reused at least four times. The FTIR spectra revealed that a chemical interaction occurs between functional groups containing lone electron pairs in XLAC and metal ions. Overall, these results suggest that XLAC may be suitable as an adsorbent for heavy metal removal from wastewater streams.

  11. Assessment of the basis of mercury tolerance in Dunaliella tertiolecta

    Energy Technology Data Exchange (ETDEWEB)

    Davies, A.G.

    1976-01-01

    The specific growth rate of Dunaliella tertiolecta was unaffected by mercury II concentrations of at least 2.03 ..mu..g at/l. At 10 ..mu..g at/l, it was eventually reduced by 84 percent but growth continued, giving a final level of cell material only 13 percent below that in a mercury-free control. At this concentration, however, growth was largely uncoupled from division and giant cells were produced, probably due to the effect of mercury upon the production of methionine which is known to be implicated in the process of cell division. The basis of the mercury tolerance was investigated in terms of (1) mercury detoxication in the culture medium by complex or compound formation between the metal and metabolites produced by the cells, (2) the concentration of sulfhydryl groups both within the cells as possible sequestration sites and in the cell membrane where any molecular disruption and permeability changes produced by the metal first occur, (3) the absence of cellular potassium leakage and (4) the resistance of the cell membrane to the uptake of mercury II ions. Where possible, the results were compared with those from determinations of the same properties of the mercury-sensitive species Isochrysis galbana. The experiments indicated that the mercury tolerance of D. tertiolecta is partly related to the slower rate of mercury accumulation by this species, but is largely due to the detoxication of the mercury within the cell possibly by the precipitation of a highly insoluble mercury compound.

  12. Geochemistry of Mercury Mineralization,Catian,West Hunan

    Institute of Scientific and Technical Information of China (English)

    何江; 马东升; 等

    1995-01-01

    The Tongfeng mercury zone is an important producer of mercury in China.The underlying Lower Cambrian black rock series is strongly depleted in mercury and is thought to be the major source bed for mercury mineralization .The Catian deposit ,as the representative of the zone, was formed at low temperature,which is characterized by a meteoric chlorine-rich and sulfur-poor ore-forming solution of high salinity.A geochemical genetic model of buried hydrothermal explosion is proposed.

  13. Novel Parametric Circuit Modeling for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Ximing Cheng

    2016-07-01

    Full Text Available Because of their simplicity and dynamic response, current pulse series are often used to extract parameters for equivalent electrical circuit modeling of Li-ion batteries. These models are then applied for performance simulation, state estimation, and thermal analysis in electric vehicles. However, these methods have two problems: The assumption of linear dependence of the matrix columns and negative parameters estimated from discrete-time equations and least-squares methods. In this paper, continuous-time equations are exploited to construct a linearly independent data matrix and parameterize the circuit model by the combination of non-negative least squares and genetic algorithm, which constrains the model parameters to be positive. Trigonometric functions are then developed to fit the parameter curves. The developed model parameterization methodology was applied and assessed by a standard driving cycle.

  14. Characterization of mercury-resistant clinical Aeromonas species

    Directory of Open Access Journals (Sweden)

    Abigail Pérez-Valdespino

    2013-12-01

    Full Text Available Mercury-resistant Aeromonas strains isolated from diarrhea were studied. Resistance occurs via mercuric ion reduction but merA and merR genes were only detected in some strains using PCR and dot hybridization. Results indicate a high variability in mer operons in Aeromonas. To our knowledge, this is the first report of mercury-resistant clinical Aeromonas strains.

  15. New methods for preparing mercury-based ferrofluids

    DEFF Research Database (Denmark)

    Linderoth, Søren; Rasmussen, L.H.; Mørup, Steen

    1991-01-01

    Metallic ferrofluids based on magnetic particles in mercury have been produced by two new methods. Alloy particles of Fe-B, Fe-Co-B, Fe-Ni-B, and Co-B were prepared by reduction of the transition metal ions in aqueous solutions by NaBH4 and subsequently suspended in mercury. In one preparation...

  16. Characterization of mercury-resistant clinical Aeromonas species.

    Science.gov (United States)

    Pérez-Valdespino, Abigail; Celestino-Mancera, Martin; Villegas-Rodríguez, Viridiana Lorena; Curiel-Quesada, Everardo

    2013-12-01

    Mercury-resistant Aeromonas strains isolated from diarrhea were studied. Resistance occurs via mercuric ion reduction but merA and merR genes were only detected in some strains using PCR and dot hybridization. Results indicate a high variability in mer operons in Aeromonas. To our knowledge, this is the first report of mercury-resistant clinical Aeromonas strains.

  17. Interferences in Photodetachment of a Negative Molecular Ion Model

    Institute of Scientific and Technical Information of China (English)

    A. Afaq; DU Meng-Li

    2008-01-01

    By employing a two-center model, the total and differential cross sections in the photodetachment of "a negative molecular ion" are studied theoretically and obtained for the case of light polarization parallel to the molecular axis. We find that in contrast to the smooth behavior of the total cross section for perpendicular polarized light, the cross section for parallel polarized light shows an interesting oscillatory structure. The oscillations in the total cross section may provide a method to determine the distance between the two centers. We explain the oscillation in the total cross section as an interference effect using closed-orbit theory. We also calculated the detached-electron flux distributions on a screen placed at a large distance from the negative molecular ion. The distributions display multiple-ring-like interference patterns. Such interference patterns are similar to those in the photodetachment microscopy experiments.

  18. Thermal Environmental Testing of NSTAR Engineering Model Ion Thrusters

    Science.gov (United States)

    Rawlin, Vincent K.; Patterson, Michael J.; Becker, Raymond A.

    1999-01-01

    NASA's New Millenium program will fly a xenon ion propulsion system on the Deep Space 1 Mission. Tests were conducted under NASA's Solar Electric Propulsion Technology Applications Readiness (NSTAR) Program with 3 different engineering model ion thrusters to determine thruster thermal characteristics over the NSTAR operating range in a variety of thermal environments. A liquid nitrogen-cooled shroud was used to cold-soak the thruster to -120 C. Initial tests were performed prior to a mature spacecraft design. Those results and the final, severe, requirements mandated by the spacecraft led to several changes to the basic thermal design. These changes were incorporated into a final design and tested over a wide range of environmental conditions.

  19. Model of wet chemical etching of swift heavy ions tracks

    Science.gov (United States)

    Gorbunov, S. A.; Malakhov, A. I.; Rymzhanov, R. A.; Volkov, A. E.

    2017-10-01

    A model of wet chemical etching of tracks of swift heavy ions (SHI) decelerated in solids in the electronic stopping regime is presented. This model takes into account both possible etching modes: etching controlled by diffusion of etchant molecules to the etching front, and etching controlled by the rate of a reaction of an etchant with a material. Olivine ((Mg0.88Fe0.12)2SiO4) crystals were chosen as a system for modeling. Two mechanisms of chemical activation of olivine around the SHI trajectory are considered. The first mechanism is activation stimulated by structural transformations in a nanometric track core, while the second one results from neutralization of metallic atoms by generated electrons spreading over micrometric distances. Monte-Carlo simulations (TREKIS code) form the basis for the description of excitations of the electronic subsystem and the lattice of olivine in an SHI track at times up to 100 fs after the projectile passage. Molecular dynamics supplies the initial conditions for modeling of lattice relaxation for longer times. These simulations enable us to estimate the effects of the chemical activation of olivine governed by both mechanisms. The developed model was applied to describe chemical activation and the etching kinetics of tracks of Au 2.1 GeV ions in olivine. The estimated lengthwise etching rate (38 µm · h‑1) is in reasonable agreement with that detected in the experiments (24 µm · h‑1).

  20. Analysis of sorption and bioavailability of different species of mercury on model soil components using XAS techniques and sensor bacteria.

    Science.gov (United States)

    Bernaus, Anna; Gaona, Xavier; Ivask, Angela; Kahru, Anne; Valiente, Manuel

    2005-08-01

    The present work studies the adsorption behaviour of mercury species on different soil components (montmorillonite, kaolinite and humic acid) spiked with CH3HgCl and CH3HgOH at different pH values, by using XAS techniques and bacterial mercury sensors in order to evaluate the availability of methyl mercury on soil components. The study details and discusses different aspects of the adsorption process, including sample preparation (with analysis of adsorbed methyl mercury by ICP-OES), the various adsorption conditions, and the characterization of spiked samples by XAS techniques performed at two synchrotron facilities (ESRF in Grenoble, France and HASYLAB in Hamburg, Germany), as well as bioavailability studies using mercury-specific sensor bacteria. Results show that XAS is a valuable qualitative technique that can be used to identify the bonding character of the Hg in mercury environment. The amount of methyl in mercury adsorbed to montmorillonite was pH-dependent while for all soil components studied, the bond character was not affected by pH. On the other hand, clays exhibited more ionic bonding character than humic acids did with methyl mercury. This interaction has a higher covalent character and so it is more stable for CH3HgOH than for CH3HgCl, due to the higher reactivity of the hydroxyl group arising from the possible formation of hydrogen bonds. The bioavailability of methyl mercury adsorbed to montmorillonite, kaolinite and humic acids was measured using recombinant luminescent sensor bacterium Escherichia coli MC1061 (pmerBR(BS)luc). In case of contact exposure (suspension assays), the results showed that the bioavailability was higher than it was for exposure to particle-free extracts prepared from these suspensions. The highest bioavailability of methyl mercury was found in suspensions of montmorillonite (about 50% of the total amount), while the bioavailabilities of kaolinite and humic acids were five times lower (about 10%). The behaviour of methyl

  1. Mercury Quick Facts: Health Effects of Mercury Exposure

    Science.gov (United States)

    Mercury Quick Facts Health Effects of Mercury Exposure What is Elemental Mercury? Elemental (metallic) mercury is the shiny, silver-gray metal found in thermometers, barometers, and thermostats and other ...

  2. Study of efficacy in a mercury-free flat discharge fluorescent lamp using a zero-dimensional positive column model

    Science.gov (United States)

    Shiga, T.; Pitchford, L. C.; Boeuf, J.-P.; Mikoshiba, S.

    2003-03-01

    A zero-dimensional model of the positive column in Ar/Ne/Xe gas mixtures has been developed to help understand the measured dependence of the efficacy on operating conditions in a mercury-free flat fluorescent lamp in a dielectric barrier geometry. The experimental conditions are such that the radiation from the discharge is homogeneous over most of the discharge voltage. The model uses as input the discharge current waveform from the experiments, and it yields the time variations of the mean electron energy and the species densities. From these quantities we calculate the number of vacuum ultraviolet (VUV) photons emitted by the xenon resonance atoms and excimers during one current pulse and the efficiency for generation of VUV radiation in the positive column, which are compared with the measured luminance and efficacy for various voltages, pulse intervals, and lamp sizes. Over the range of conditions studied, we find that most electrical energy dissipated in xenon excitation is converted to VUV radiation; i.e. the losses of xenon excitation in stepwise and associative ionization processes are small. When the mean electron energy is low, energy dissipation in elastic momentum transfer collisions leads to a decrease in the efficiency. On the other hand, ionization and excitation of argon degrade the efficiency when the mean electron energy is high. To a lesser extent, stepwise excitation of the xenon metastables also decreases the efficiency for high current densities.

  3. Study of efficacy in a mercury-free flat discharge fluorescent lamp using a zero-dimensional positive column model

    CERN Document Server

    Shiga, T; Boeuf, J P; Mikoshiba, S

    2003-01-01

    A zero-dimensional model of the positive column in Ar/Ne/Xe gas mixtures has been developed to help understand the measured dependence of the efficacy on operating conditions in a mercury-free flat fluorescent lamp in a dielectric barrier geometry. The experimental conditions are such that the radiation from the discharge is homogeneous over most of the discharge voltage. The model uses as input the discharge current waveform from the experiments, and it yields the time variations of the mean electron energy and the species densities. From these quantities we calculate the number of vacuum ultraviolet (VUV) photons emitted by the xenon resonance atoms and excimers during one current pulse and the efficiency for generation of VUV radiation in the positive column, which are compared with the measured luminance and efficacy for various voltages, pulse intervals, and lamp sizes. Over the range of conditions studied, we find that most electrical energy dissipated in xenon excitation is converted to VUV radiation; ...

  4. Study of efficacy in a mercury-free flat discharge fluorescent lamp using a zero-dimensional positive column model

    Energy Technology Data Exchange (ETDEWEB)

    Shiga, T [Centre de Physique des Plasmas et Applications de Toulouse, Universite Paul Sabatier, 118 Route de Narbonne, Toulouse 31062 (France); Pitchford, L C [Centre de Physique des Plasmas et Applications de Toulouse, Universite Paul Sabatier, 118 Route de Narbonne, Toulouse 31062 (France); Boeuf, J-P [Centre de Physique des Plasmas et Applications de Toulouse, Universite Paul Sabatier, 118 Route de Narbonne, Toulouse 31062 (France); Mikoshiba, S [The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585 (Japan)

    2003-03-07

    A zero-dimensional model of the positive column in Ar/Ne/Xe gas mixtures has been developed to help understand the measured dependence of the efficacy on operating conditions in a mercury-free flat fluorescent lamp in a dielectric barrier geometry. The experimental conditions are such that the radiation from the discharge is homogeneous over most of the discharge voltage. The model uses as input the discharge current waveform from the experiments, and it yields the time variations of the mean electron energy and the species densities. From these quantities we calculate the number of vacuum ultraviolet (VUV) photons emitted by the xenon resonance atoms and excimers during one current pulse and the efficiency for generation of VUV radiation in the positive column, which are compared with the measured luminance and efficacy for various voltages, pulse intervals, and lamp sizes. Over the range of conditions studied, we find that most electrical energy dissipated in xenon excitation is converted to VUV radiation; i.e. the losses of xenon excitation in stepwise and associative ionization processes are small. When the mean electron energy is low, energy dissipation in elastic momentum transfer collisions leads to a decrease in the efficiency. On the other hand, ionization and excitation of argon degrade the efficiency when the mean electron energy is high. To a lesser extent, stepwise excitation of the xenon metastables also decreases the efficiency for high current densities.

  5. The Influence of Climate Change on Atmospheric Deposition of Mercury in the Arctic—A Model Sensitivity Study

    Directory of Open Access Journals (Sweden)

    Kaj M. Hansen

    2015-09-01

    Full Text Available Mercury (Hg is a global pollutant with adverse health effects on humans and wildlife. It is of special concern in the Arctic due to accumulation in the food web and exposure of the Arctic population through a rich marine diet. Climate change may alter the exposure of the Arctic population to Hg. We have investigated the effect of climate change on the atmospheric Hg transport to and deposition within the Arctic by making a sensitivity study of how the atmospheric chemistry-transport model Danish Eulerian Hemispheric Model (DEHM reacts to climate change forcing. The total deposition of Hg to the Arctic is 18% lower in the 2090s compared to the 1990s under the applied Special Report on Emissions Scenarios (SRES-A1B climate scenario. Asia is the major anthropogenic source area (25% of the deposition to the Arctic followed by Europe (6% and North America (5%, with the rest arising from the background concentration, and this is independent of the climate. DEHM predicts between a 6% increase (Status Quo scenario and a 37% decrease (zero anthropogenic emissions scenario in Hg deposition to the Arctic depending on the applied emission scenario, while the combined effect of future climate and emission changes results in up to 47% lower Hg deposition.

  6. The Influence of Climate Change on Atmospheric Deposition of Mercury in the Arctic—A Model Sensitivity Study.

    Science.gov (United States)

    Hansen, Kaj M; Christensen, Jesper H; Brandt, Jørgen

    2015-09-10

    Mercury (Hg) is a global pollutant with adverse health effects on humans and wildlife. It is of special concern in the Arctic due to accumulation in the food web and exposure of the Arctic population through a rich marine diet. Climate change may alter the exposure of the Arctic population to Hg. We have investigated the effect of climate change on the atmospheric Hg transport to and deposition within the Arctic by making a sensitivity study of how the atmospheric chemistry-transport model Danish Eulerian Hemispheric Model (DEHM) reacts to climate change forcing. The total deposition of Hg to the Arctic is 18% lower in the 2090s compared to the 1990s under the applied Special Report on Emissions Scenarios (SRES-A1B) climate scenario. Asia is the major anthropogenic source area (25% of the deposition to the Arctic) followed by Europe (6%) and North America (5%), with the rest arising from the background concentration, and this is independent of the climate. DEHM predicts between a 6% increase (Status Quo scenario) and a 37% decrease (zero anthropogenic emissions scenario) in Hg deposition to the Arctic depending on the applied emission scenario, while the combined effect of future climate and emission changes results in up to 47% lower Hg deposition.

  7. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  8. Phytoremediation of Ionic and Methyl Mercury Pollution

    Energy Technology Data Exchange (ETDEWEB)

    Meagher, Richard B.

    2005-06-01

    Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to

  9. Molecular dynamics simulations of water within models of ion channels.

    Science.gov (United States)

    Breed, J; Sankararamakrishnan, R; Kerr, I D; Sansom, M S

    1996-04-01

    The transbilayer pores formed by ion channel proteins contain extended columns of water molecules. The dynamic properties of such waters have been suggested to differ from those of water in its bulk state. Molecular dynamics simulations of ion channel models solvated within and at the mouths of their pores are used to investigate the dynamics and structure of intra-pore water. Three classes of channel model are investigated: a) parallel bundles of hydrophobic (Ala20) alpha-helices; b) eight-stranded hydrophobic (Ala10) antiparallel beta-barrels; and c) parallel bundles of amphipathic alpha-helices (namely, delta-toxin, alamethicin, and nicotinic acetylcholine receptor M2 helix). The self-diffusion coefficients of water molecules within the pores are reduced significantly relative to bulk water in all of the models. Water rotational reorientation rates are also reduced within the pores, particularly in those pores formed by alpha-helix bundles. In the narrowest pore (that of the Ala20 pentameric helix bundle) self-diffusion coefficients and reorientation rates of intra-pore waters are reduced by approximately an order of magnitude relative to bulk solvent. In Ala20 helix bundles the water dipoles orient antiparallel to the helix dipoles. Such dipole/dipole interaction between water and pore may explain how water-filled ion channels may be formed by hydrophobic helices. In the bundles of amphipathic helices the orientation of water dipoles is modulated by the presence of charged side chains. No preferential orientation of water dipoles relative to the pore axis is observed in the hydrophobic beta-barrel models.

  10. A Simple Model of Wings in Heavy-Ion Collisions

    CERN Document Server

    Parikh, Aditya

    2015-01-01

    We create a simple model of heavy ion collisions independent of any generators as a way of investigating a possible source of the wings seen in data. As a first test, we reproduce a standard correlations plot to verify the integrity of the model. We then proceed to test whether an η dependent v2 could be a source of the wings and take projections along multiple Δφ intervals and compare with data. Other variations of the model are tested by having dN/dφ and v2 depend on η as well as including pions and protons into the model to make it more realistic. Comparisons with data seem to indicate that an η dependent v2 is not the main source of the wings.

  11. Comprehensive modeling of ion-implant amorphization in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mok, K.R.C. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain) and Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576 (Singapore)]. E-mail: g0202446@nus.edu.sg; Jaraiz, M. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Martin-Bragado, I. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Synopsys, Karl-Hammerschmidt Strasse 34, D-85609 Aschheim/Dornach (Germany); Rubio, J.E. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Castrillo, P. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Pinacho, R. [Departamento de E. y Electronica, Universidad de Valladolid, ETSIT Campus Miguel Delibes, 47011 Valladolid (Spain); Srinivasan, M.P. [Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576 (Singapore); Benistant, F. [Chartered Semiconductor Manufacturing. 60 Woodlands Industrial Park D, Street 2, Singapore 738406 (Singapore)

    2005-12-05

    A physically based model has been developed to simulate the ion-implant induced damage accumulation up to amorphization in silicon. Based on damage structures known as amorphous pockets (AP), which are three-dimensional, irregularly shaped agglomerates of interstitials (I) and vacancies (V) surrounded by crystalline silicon, the model is able to reproduce a wide range of experimental observations of damage accumulation and amorphization with interdependent implantation parameters. Instead of recrystallizing the I's and V's instantaneously, the recrystallization rate of an AP containing nI and mV is a function of its effective size, defined as min(n, m), irrespective of its internal spatial configuration. The parameters used in the model were calibrated using the experimental silicon amorphous-crystalline transition temperature as a function of dose rate for C, Si, and Ge. The model is able to show the superlinear damage build-up with dose, the extent of amorphous layer and the superadditivity effect of polyatomic ions.

  12. Modelling the ion-exchange equilibrium in nanoporous materials

    Directory of Open Access Journals (Sweden)

    M. Lukšič

    2012-06-01

    Full Text Available Distribution of a two component electrolyte mixture between the model adsorbent and a bulk aqueous electrolyte solution was studied using the replica Ornstein-Zernike theory and the grand canonical Monte Carlo method. The electrolyte components were modelled to mimic the HCl/NaCl and HCl/CaCl2 mixtures, respectively. The matrix, invaded by the primitive model electrolyte mixture, was formed from monovalent negatively charged spherical obstacles. The solution was treated as a continuous dielectric with the properties of pure water. Comparison of the pair distribution functions (obtained by the two methods between the various ionic species indicated a good agreement between the replica Ornstein-Zernike results and machine calculations. Among thermodynamic properties, the mean activity coefficient of the invaded electrolyte components was calculated. Simple model for the ion-exchange resin was proposed. The selectivity calculations yielded qualitative agreement with the following experimental observations: (i selectivity increases with the increasing capacity of the adsorbent (matrix concentration, (ii the adsorbent is more selective for the ion having higher charge density if its fraction in mixture is smaller.

  13. Independent-particle models for light negative atomic ions

    Science.gov (United States)

    Ganas, P. S.; Talman, J. D.; Green, A. E. S.

    1980-01-01

    For the purposes of astrophysical, aeronomical, and laboratory application, a precise independent-particle model for electrons in negative atomic ions of the second and third period is discussed. The optimum-potential model (OPM) of Talman et al. (1979) is first used to generate numerical potentials for eight of these ions. Results for total energies and electron affinities are found to be very close to Hartree-Fock solutions. However, the OPM and HF electron affinities both depart significantly from experimental affinities. For this reason, two analytic potentials are developed whose inner energy levels are very close to the OPM and HF levels but whose last electron eigenvalues are adjusted precisely with the magnitudes of experimental affinities. These models are: (1) a four-parameter analytic characterization of the OPM potential and (2) a two-parameter potential model of the Green, Sellin, Zachor type. The system O(-) or e-O, which is important in upper atmospheric physics is examined in some detail.

  14. Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC)

    OpenAIRE

    2011-01-01

    The depth profile of mercuric ion after the reaction with polysulfide-rubber-coated activated carbon (PSR-AC) was investigated using micro-x-ray fluorescence (μ-XRF) imaging techniques and mathematical modeling. The μ-XRF results revealed that mercury was concentrated at 0~100 μm from the exterior of the particle after three months of treatment with PSR-AC in 10 ppm HgCl2 aqueous solution. The μ-X-ray absorption near edge spectroscopic (μ-XANES) analyses indicated HgS as a major mercury speci...

  15. Methyl mercury, but not inorganic mercury, associated with higher blood pressure during pregnancy.

    Science.gov (United States)

    Wells, Ellen M; Herbstman, Julie B; Lin, Yu Hong; Hibbeln, Joseph R; Halden, Rolf U; Witter, Frank R; Goldman, Lynn R

    2017-04-01

    Prior studies addressing associations between mercury and blood pressure have produced inconsistent findings; some of this may result from measuring total instead of speciated mercury. This cross-sectional study of 263 pregnant women assessed total mercury, speciated mercury, selenium, and n-3 polyunsaturated fatty acids in umbilical cord blood and blood pressure during labor and delivery. Models with a) total mercury or b) methyl and inorganic mercury were evaluated. Regression models adjusted for maternal age, race/ethnicity, prepregnancy body mass index, neighborhood income, parity, smoking, n-3 fatty acids and selenium. Geometric mean total, methyl, and inorganic mercury concentrations were 1.40µg/L (95% confidence interval: 1.29, 1.52); 0.95µg/L (0.84, 1.07); and 0.13µg/L (0.10, 0.17), respectively. Elevated systolic BP, diastolic BP, and pulse pressure were found, respectively, in 11.4%, 6.8%, and 19.8% of mothers. In adjusted multivariable models, a one-tertile increase of methyl mercury was associated with 2.83mmHg (0.17, 5.50) higher systolic blood pressure and 2.99mmHg (0.91, 5.08) higher pulse pressure. In the same models, an increase of one tertile of inorganic mercury was associated with -1.18mmHg (-3.72, 1.35) lower systolic blood pressure and -2.51mmHg (-4.49, -0.53) lower pulse pressure. No associations were observed with diastolic pressure. There was a non-significant trend of higher total mercury with higher systolic blood pressure. We observed a significant association of higher methyl mercury with higher systolic and pulse pressure, yet higher inorganic mercury was significantly associated with lower pulse pressure. These results should be confirmed with larger, longitudinal studies.

  16. Ion size effect on colloidal forces within the primitive model

    Directory of Open Access Journals (Sweden)

    J.Wu

    2005-01-01

    Full Text Available The effect of ion size on the mean force between a pair of isolated charged particles in an electrolyte solution is investigated using Monte Carlo simulations within the framework of the primitive model where both colloidal particles and small ions are represented by charged hard spheres and the solvent is treated as a dielectric continuum. It is found that the short-ranged attraction between like-charged macroions diminishes as the diameter of the intermediating divalent counterions and coions increases and the maximum attractive force is approximately a linear function of the counterion diameter. This size effect contradicts the prediction of the Asakura-Oosawa theory suggesting that an increase in the excluded volume of small ions would lead to a stronger depletion between colloidal particles. Interestingly, the simulation results indicate that both the hard-sphere collision and the electrostatic contributions to the mean force are insensitive to the size disparity of colloidal particles with the same average diameter.

  17. Modeling ion interpenetration, stagnation, and thermalization in colliding plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jones, M.E.; Winske, D.; Goldman, S.R.; Kopp, R.A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Rogatchev, V.G.; Belkov, S.A.; Gasparyan, P.D.; Dolgoleva, G.V.; Zhidkov, N.V.; Ivanov, N.V.; Kochubej, Y.K.; Nasyrov, G.F.; Pavlovskii, V.A.; Smirnov, V.V.; Romanov, Y.A. [All Russian Scientific Research Institute of Experimental Physics, Sarov (Arzamas 16), Nizhniy Novgorod Region, 607200 (Russia)

    1996-03-01

    Ion interpenetration, stagnation, and energization processes are studied in colliding laser-produced plasma configurations relevant to Trident [R. G. Watt, Rev. Sci. Instrum. {bold 64}, 1770 (1993)] experiments using four different numerical methods: one-dimensional Monte Carlo and Lagrangian multifluid codes, and one- and two-dimensional hybrid (particle ions, fluid electrons) and single-fluid Lagrangian codes. Results from the four methodologies are compared for plasmas generated with gold and deuterated polyethylene (CD{sub 2}) targets. Overall, the various codes give similar results concerning the initial expansion of the plasmas and their collisional interaction, the degree of stagnation, stagnation time, and amount of ion thermalization for gold targets, while multispecies techniques indicate a much softer stagnation for CD{sub 2} plasmas than the single-fluid model. Variations in the results of the calculations due to somewhat different initializations and parameters, as well as to different physics in the codes, are discussed. {copyright} {ital 1996 American Institute of Physics.}

  18. Messenger Observations of Mercury's Bow Shock and Magnetopause

    Science.gov (United States)

    Slavin J. A.; Acuna, M. H.; Anderson, B. J.; Benna, M.; Gloeckler, G.; Krimigis, S. M.; Raines, M.; Schriver, D.; Travnicek, P.; Zurbuchen, T. H.

    2008-01-01

    The MESSENGER spacecraft made the first of three flybys of Mercury on January 14.2008 (1). New observations of solar wind interaction with Mercury were made with MESSENGER'S Magnetometer (MAG) (2.3) and Energetic Particle and Plasma Spectrometer (EPPS) - composed of the Energetic Particle Spectrometer (EPS) and Fast Imaging Plasma Spectrometer (FIPS) (3,4). These MESSENGER observations show that Mercury's magnetosphere has a large-scale structure that is distinctly Earth-like, but it is immersed in a comet-like cloud of planetary ions [5]. Fig. 1 provides a schematic view of the coupled solar wind - magnetosphere - neutral atmosphere - solid planet system at Mercury.

  19. Mercury (Environmental Health Student Portal)

    Science.gov (United States)

    ... to dispose of (get rid of) mercury and mercury compounds properly, or they can wind up contaminating (polluting) soil, water, and air. Show more What products might have mercury in them? People have used mercury throughout history — ...

  20. Mercury's cross-tail current sheet: Structure, X-line location and stress balance

    Science.gov (United States)

    Poh, Gangkai; Slavin, James A.; Jia, Xianzhe; Raines, Jim M.; Imber, Suzanne M.; Sun, Wei-Jie; Gershman, Daniel J.; DiBraccio, Gina A.; Genestreti, Kevin J.; Smith, Andy W.

    2017-01-01

    The structure, X-line location, and magnetohydrodynamic (MHD) stress balance of Mercury's magnetotail were examined between -2.6 MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) measurements from 319 central plasma sheet (CPS) crossings. The mean plasma β in the CPS calculated from MESSENGER data is 6. The CPS magnetic field was southward (i.e., tailward of X-line) 2-18% of the time. Extrapolation of downtail variations in BZ indicates an average X-line location at -3 RM. Modeling of magnetic field measurements produced a cross-tail current sheet (CS) thickness, current density, and inner CS edge location of 0.39 RM, 92 nA/m2 and -1.22 RM, respectively. Application of MHD stress balance suggests that heavy planetary ions may be important in maintaining stress balance within Mercury's CPS. Qualitative similarities between Mercury's and Earth's magnetotail are remarkable given the differences in upstream conditions, internal plasma composition, finite gyro-radius scaling, and Mercury's lack of ionosphere.

  1. A new specific polymeric material for mercury speciation: Application to environmental and food samples.

    Science.gov (United States)

    Zarco-Fernández, S; Mancheño, M J; Muñoz-Olivas, R; Cámara, C

    2015-10-15

    A new polymeric material (Patent: P201400535) highly specific for mercury is presented. Its great capability to pre-concentrate and selectively elute inorganic mercury and methylmercury are the main figures of merit. The polymer can be reused several times. To our knowledge, this is the only polymer proposed in the literature for direct inorganic mercury and methylmercury speciation without need of chromatography or quantification by difference. The polymer formation is based on the reaction of a vinyl derivative of 8-hydroxiquinoline as monomer, and 2-(Methacryloylamino) ethyl 2-Methyl Acrylate (NOBE) as co-monomer. Random radical polymerization by the precipitation method was carried out using Azobisisobutyronitrile (AIBN) as initiator. The polymer was characterized by SEM and FTIR. Adsorption binding isotherms were evaluated using Langmuir and Freundlich models, showing high adsorption capacity for both inorganic and organic mercury species. The polymer was employed to sequentially determine inorganic mercury and methylmercury, using a solid phase extraction (SPE) scheme. Cross reactivity of several ions, as well as matrix effects from a high saline matrix like seawater was irrelevant as the retained fractions mostly eluted during the washing step. The procedure was first validated by analyzing a certified reference material (BCR 464) and finally applied to commercial fish samples. The speciation proposed procedure is cheap, fast, and easy to use and minimizes reagents waste.

  2. Modeling the ion abundances in Saturn's inner magnetosphere

    Science.gov (United States)

    Fleshman, B. L.; Bagenal, F.; Delamere, P. A.

    2011-12-01

    Water ejected from Enceladus's plumes provides much of the material that fills both the dense H2O torus centered on Enceladus's orbit, as well as Saturn's neutral clouds which extend at least four times farther from Saturn. Photo- and impact ionization transforms a few percent of these neutrals into the ions co-rotating with Saturn's magnetosphere, and charge exchange is responsible for a substantial redistribution among the hydrogen and water-group ions, though it does not alter the overall plasma density. In this paper, we explore ion abundances at Saturn with a chemistry model developed to include all of these processes. Building on our earlier attempts, we now include a source of neutrals from a neutral cloud model, so as to advance our description to include radial and latitudinal variations. At the same time, we now prescribe a radially-varying plasma diffusion coefficient to study the magnetosphere's inability to contain centrifigually-unstable plasma. We also are interested in the effect of hot electrons (102-103 eV) beamed along field lines into the equatorial region chiefly of interest. Our parameter study of radial diffusion and hot-electron flux is anchored to available Cassini CAPS water-group and proton abundances. Preliminary results suggest an injection of ~10 MW by hot electrons, and reveal promising radial trends in the water-group abundances that agree well with Sittler et al. (2008). We can also simulate an Enceladus torus dominated H3O+ -- a result not obtainable prior to coupling the chemistry and neutral cloud models.

  3. Energetic Particles Dynamics in Mercury's Magnetosphere

    Science.gov (United States)

    Walsh, Brian M.; Ryou, A.S.; Sibeck, D. G.; Alexeev, I. I.

    2013-01-01

    We investigate the drift paths of energetic particles in Mercury's magnetosphere by tracing their motion through a model magnetic field. Test particle simulations solving the full Lorentz force show a quasi-trapped energetic particle population that gradient and curvature drift around the planet via "Shabansky" orbits, passing though high latitudes in the compressed dayside by equatorial latitudes on the nightside. Due to their large gyroradii, energetic H+ and Na+ ions will typically collide with the planet or the magnetopause and will not be able to complete a full drift orbit. These simulations provide direct comparison for recent spacecraft measurements from MESSENGER. Mercury's offset dipole results in an asymmetric loss cone and therefore an asymmetry in particle precipitation with more particles precipitating in the southern hemisphere. Since the planet lacks an atmosphere, precipitating particles will collide directly with the surface of the planet. The incident charged particles can kick up neutrals from the surface and have implications for the formation of the exosphere and weathering of the surface

  4. Modeling magnetosensitive ion channels in viscoelastic environment of living cells

    CERN Document Server

    Goychuk, Igor

    2015-01-01

    We propose and study a model of hypothetical magnetosensitive ionic channels which are long thought to be a possible candidate to explain the influence of weak magnetic fields on living organisms ranging from magnetotactic bacteria to fishes, birds, rats, bats and other mammals including humans. The core of the model is provided by a short chain of magnetosomes serving as a sensor which is coupled by elastic linkers to the gating elements of ion channels forming a small cluster in the cell membrane. The magnetic sensor is fixed by one end on cytoskeleton elements attached to the membrane and is exposed to viscoelastic cytosol. Its free end can reorient stochastically and subdiffusively in viscoelastic cytosol responding to external magnetic field changes and open the gates of coupled ion channels. The sensor dynamics is generally bistable due to bistability of the gates which can be in two states with probabilities which depend on the sensor orientation. For realistic parameters, it is shown that this model c...

  5. Model for hypernucleus production in heavy ion collisions

    CERN Document Server

    Pop, V Topor

    2010-01-01

    We estimate the production cross sections of hypernuclei in projectile like fragment (PLF) in heavy ion collisions. The discussed scenario for the formation cross section of hypernucleus is: (a) Lambda particles are produced in the participant region but have a considerable rapidity spread and (b) Lambda with rapidity close to that of the PLF and total momentum (in the rest system of PLF) up to Fermi motion can then be trapped and produce hypernuclei. The process (a) is considered here within Heavy Ion Jet Interacting Generator HIJING-BBbar model and the process (b) in the canonical thermodynamic model (CTM). We estimate the production cross-sections for light hypernuclei for C + C at 3.7 GeV total nucleon-nucleon center of mass energy and for Ne+Ne and Ar+Ar collisions at 5.0 GeV. By taking into account explicitly the impact parameter dependence of the colliding systems, it is found that the cross section is different from that predicted by the coalescence model and large discrepancy is obtained for 6_He and...

  6. Electrochemical model based charge optimization for lithium-ion batteries

    Science.gov (United States)

    Pramanik, Sourav; Anwar, Sohel

    2016-05-01

    In this paper, we propose the design of a novel optimal strategy for charging the lithium-ion battery based on electrochemical battery model that is aimed at improved performance. A performance index that aims at minimizing the charging effort along with a minimum deviation from the rated maximum thresholds for cell temperature and charging current has been defined. The method proposed in this paper aims at achieving a faster charging rate while maintaining safe limits for various battery parameters. Safe operation of the battery is achieved by including the battery bulk temperature as a control component in the performance index which is of critical importance for electric vehicles. Another important aspect of the performance objective proposed here is the efficiency of the algorithm that would allow higher charging rates without compromising the internal electrochemical kinetics of the battery which would prevent abusive conditions, thereby improving the long term durability. A more realistic model, based on battery electro-chemistry has been used for the design of the optimal algorithm as opposed to the conventional equivalent circuit models. To solve the optimization problem, Pontryagins principle has been used which is very effective for constrained optimization problems with both state and input constraints. Simulation results show that the proposed optimal charging algorithm is capable of shortening the charging time of a lithium ion cell while maintaining the temperature constraint when compared with the standard constant current charging. The designed method also maintains the internal states within limits that can avoid abusive operating conditions.

  7. Modeling Fast Ion Transport in TAE Avalanches in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, E D; Bell, R E; Darrow, D; Gorelenkov, N N; Kramer, G; Kubota, S; Levinton, F M; Liu, D; Medley, S S; Podesta, M; Tritz, K

    2009-08-17

    Experiments on the National Spherical Torus Experiment [M. Ono, et al., Nucl. Fusion 40 (2000) 557 ] have found strong bursts of Toroidal Alfven Eigenmode (TAE) activity correlated with abrupt drops in the neutron rate. A fairly complete data set offers the opportunity to benchmark the NOVA [C. Z. Cheng, Phys. Reports 211, 1-51 (1992)] and ORBIT [R. B. White and M. S. Chance, Phys. Fluids 27, 2455 (1984)] codes in the low aspect ratio tokamak (ST) geometry. The internal structure of TAE were modeled with NOVA and good agreement is found with measurements made with an array of five fixed-frequency reflectometers. The fast-ion transport resulting from these bursts of multiple TAE were then modeled with the ORBIT code. The simulations are reasonably consistent with the observed drop in neutron rate. While these results represent our best attempts to find agreement, we believe that further refinements in both the simulation of the TAE structure and in the modeling of the fast ion transport are needed. Benchmarking stability codes against present experiments is an important step in developing the predictive capability needed to plan future experiments.

  8. Mercury- and silver-rich ferromanganese oxides, southern California Borderland: Deposit model and environmental implications

    Science.gov (United States)

    Hein, J.R.; Koschinsky, A.; McIntyre, B.R.

    2005-01-01

    Mercury- and silver-enriched ferromanganese oxide crusts were recovered at water depths of 1,750 tol,300 m from La Victoria knoll, located about 72 km off the coast of northern Baja California. No other ferromanganese precipitate found so far in the modern ocean basins is similarly enriched in Hg and Ag. The precipitates consist of submetallic gray, brecciated, Mn oxide layers overlain by brown earthy, laminated Fe-Mn oxide crusts. Both oxide types are rich in Hg (to 10 ppm) and Ag (to 5.5 ppm). The Mn-rich layers are composed of ??MnO2, with lesser amounts of 10A?? and 7A?? manganates, whereas the Mn phase in the Fe-Mn crusts is solely ??MnO2. The Fe phase in both layers is X-ray amorphous. Established criteria for distinguishing hydrothermal versus hydrogenetic crusts indicate that the Mn-rich layers are predominantly of low-temperature hydrothermal origin, whereas the Fe-Mn crusts are hydrogenetic, although there is some overlap in the source of chemical components in both types. La Victoria knoll is uplifted continental basement rock with basalt, andesite, and schist cropping out at the surface; the knoll may have an intrusive core. The Hg and Ag were derived from leaching by hydrothermal fluids of organic matter-rich sediments in basins adjacent to La Victoria knoll and, to a lesser extent, from continental basement rocks underlying the knoll and adjacent basins. Both rock types are notably enriched in Ag and Hg. Faults were the main fluid transport pathway, and hydrothermal circulation was driven by high heat flow associated with thinned crust. Other elements derived from the hydrothermal fluids include Tl, Cd, Cr, and Li. The main host for Hg and Ag is FeOOH, although MnO2 likely hosts some of the Ag. Minor sulfide and barite also may contain small amounts of these metals. Possible analogs in the geologic record for this deposit type are found in the Basin and Range province of the western United States and Mexico. The discovery highlights the fact that

  9. Mercury speciation in terrestrial biota from coastal and inland food webs in California: A provisional model

    Science.gov (United States)

    Weiss-Penzias, P. S.; Wilmers, C.; Houghtaling, P.; Torregrosa, A.; Bank, M. S.

    2016-12-01

    Previous research has suggested that coastal ocean emissions of volatile methylated inorganic mercury (Hg) compounds are the source of elevated concentrations of toxic monomethylmercury (MMHg) in summertime marine fog on the coast of California relative to MMHg concentrations found in rain. Here we evaluate a priori predictions that speciated Hg (total Hg and MMHg) concentrations would be higher in the terrestrial biota from the coastal versus inland environments in California, which may reflect an additional Hg burden from fog deposition. Total Hg concentrations were determined in the following biota from the coastal Santa Cruz Mountains (SCM) and the inland Sierra Nevada foothills (SNF): puma (Puma concolor) whisker and fur, deer (Odocoileus hemionus) fur, and specimens from eight plant species that are consumed by deer. In addition, MMHg concentrations were determined in the eight plant species. Average total Hg concentrations were significantly higher in the SCM puma whisker (1.04 ug/g, N = 77) compared with SNF puma whisker (0.15 ug/g, N = 12). Average total Hg concentrations were also significantly higher in SCM deer fur (0.035 ug/g, N = 35) compared with SNF deer fur (0.010 ug/g, N = 4). Average total Hg concentrations were not significantly higher in all plant species from SCM (0.029 ug/g) compared with SNF (0.021 ug/g). Similarly average MMHg concentrations were not significantly higher in all plant species from SCM (0.95 ng/g, N = 15) compared with SNF (0.66 ng/g, N = 12). However, the difference in average MMHg concentration among oak leaves between SCM (1.39 ng/g, N = 8) and SNF (0.62 ng/g, N = 5) was significant (p < 0.10). Within the SCM, the spatial distribution of MMHg concentrations in oak leaves was significantly correlated (r2 = 0.70) with fog and low cloud cover (FLCC) frequency as determined by ten years of summertime GOES satellite images. Work is ongoing to measure the Hg isotope ratios in biota from the coastal and inland areas to evaluate

  10. Successes and challenges of measuring and modeling atmospheric mercury at the part per quadrillion level: a critical review

    Directory of Open Access Journals (Sweden)

    M. Sexauer Gustin

    2015-02-01

    Full Text Available Measurements of atmospheric mercury (Hg are being increasingly incorporated into monitoring networks worldwide. These data are expected to support and inform regulatory decision making aimed at protecting human and wildlife health. Here we critically review current efforts to measure Hg concentrations in the atmosphere and interpret these data with Hg models. There are three operationally defined forms of atmospheric Hg: Gaseous Elemental (GEM, Gaseous Oxidized (GOM, and Particulate Bound (PBM. While there is relative confidence in GEM measurements, GOM and PBM are less well understood. Field and laboratory investigations suggest the methods to measure GOM and PBM are impacted by analytical interferences that vary with environmental setting (e.g., ozone, relative humidity and GOM concentrations can be biased low by a factor of 1.6–12 times depending on the chemical compound. Importantly, efforts to understand the fundamental limitations of atmospheric Hg measurement methods have provided clear evidence that the composition of GOM (e.g., HgBr2, HgCl2, HgBrOH varies across space and time. This has significant implications for refining existing measurement methods and developing new ones, model/measurement comparisons, model development, and assessing trends. In addition, unclear features of previously published data may now be re-examined and possibly explained, which we present as a case study. Lastly, we outline recommendations for needed research directions as the Hg field moves forward. Priorities include GOM and PBM calibration systems, identification of GOM compounds in ambient air, and identification of redox mechanisms and associated rate coefficients. Determination of a quantitative correction factor for biased GOM and PBM data is also needed to facilitate model-measurement comparisons.

  11. Application of a rule-based model to estimate mercury exchange for three background biomes in the continental United States.

    Science.gov (United States)

    Hartman, Jelena S; Weisberg, Peter J; Pillai, Rekha; Ericksen, Jody A; Kuiken, Todd; Lindberg, Steve E; Zhang, Hong; Rytuba, James J; Gustin, Mae S

    2009-07-01

    Ecosystems that have low mercury (Hg) concentrations (i.e., not enriched or impacted by geologic or anthropogenic processes) cover most of the terrestrial surface area of the earth yet their role as a net source or sink for atmospheric Hg is uncertain. Here we use empirical data to develop a rule-based model implemented within a geographic information system framework to estimate the spatial and temporal patterns of Hg flux for semiarid deserts, grasslands, and deciduous forests representing 45% of the continental United States. This exercise provides an indication of whether these ecosystems are a net source or sink for atmospheric Hg as well as a basis for recommendation of data to collect in future field sampling campaigns. Results indicated that soil alone was a small net source of atmospheric Hg and that emitted Hg could be accounted for based on Hg input by wet deposition. When foliar assimilation and wet deposition are added to the area estimate of soil Hg flux these biomes are a sink for atmospheric Hg.

  12. Bioavailability study of arsenic and mercury in traditional Chinese medicines (TCM) using an animal model after a single dose exposure.

    Science.gov (United States)

    Tinggi, Ujang; Sadler, Ross; Ng, Jack; Noller, Barry; Seawright, Alan

    2016-04-01

    Traditional Chinese medicines (TCM) are increasingly being used as alternative medicines in many countries, and this has caused concern because of adverse health effects from toxic metal bioavailability such as mercury (Hg) and arsenic (As). The aim of this study was to investigate the bioavailability of As and Hg from TCM after a single exposure dose using an animal model of female Sprague-Dawley rats. The rats were divided into 6 groups which included four groups treated with sodium arsenite (NaAsO2), arsenic sulfide (As2S3), mercuric chloride (HgCl2), mercuric sulfide (HgS), and two groups treated with TCM containing high Hg or As (Liu Shen Wan: As 7.7-9.1% and Hg 1.4-5.0%; Niuhang Jie du Pian: As 6.2-7.9% and Hg bioavailability of As and Hg from TCM as indicated by low relative bioavailability of As (0.60-1.10%) and Hg (<0.001%). Histopathological examination of rat kidney and liver tissues did not show toxic effects from TCM. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  13. Model-based condition monitoring for lithium-ion batteries

    Science.gov (United States)

    Kim, Taesic; Wang, Yebin; Fang, Huazhen; Sahinoglu, Zafer; Wada, Toshihiro; Hara, Satoshi; Qiao, Wei

    2015-11-01

    Condition monitoring for batteries involves tracking changes in physical parameters and operational states such as state of health (SOH) and state of charge (SOC), and is fundamentally important for building high-performance and safety-critical battery systems. A model-based condition monitoring strategy is developed in this paper for Lithium-ion batteries on the basis of an electrical circuit model incorporating hysteresis effect. It systematically integrates 1) a fast upper-triangular and diagonal recursive least squares algorithm for parameter identification of the battery model, 2) a smooth variable structure filter for the SOC estimation, and 3) a recursive total least squares algorithm for estimating the maximum capacity, which indicates the SOH. The proposed solution enjoys advantages including high accuracy, low computational cost, and simple implementation, and therefore is suitable for deployment and use in real-time embedded battery management systems (BMSs). Simulations and experiments validate effectiveness of the proposed strategy.

  14. RF Plasma modeling of the Linac4 H− ion source

    CERN Document Server

    Mattei, S; Hatayama, A; Lettry, J; Kawamura, Y; Yasumoto, M; Schmitzer, C

    2013-01-01

    This study focuses on the modelling of the ICP RF-plasma in the Linac4 H− ion source currently being constructed at CERN. A self-consistent model of the plasma dynamics with the RF electromagnetic field has been developed by a PIC-MCC method. In this paper, the model is applied to the analysis of a low density plasma discharge initiation, with particular interest on the effect of the external magnetic field on the plasma properties, such as wall loss, electron density and electron energy. The use of a multi-cusp magnetic field effectively limits the wall losses, particularly in the radial direction. Preliminary results however indicate that a reduced heating efficiency results in such a configuration. The effect is possibly due to trapping of electrons in the multi-cusp magnetic field, preventing their continuous acceleration in the azimuthal direction.

  15. Kinetic modelling for zinc (II) ions biosorption onto Luffa cylindrica

    Energy Technology Data Exchange (ETDEWEB)

    Oboh, I., E-mail: innocentoboh@uniuyo.edu.ng [Department of Chemical and Petroleum Engineering, University of Uyo, Uyo (Nigeria); Aluyor, E.; Audu, T. [Department of Chemical Engineering, University of Uyo, BeninCity, BeninCity (Nigeria)

    2015-03-30

    The biosorption of Zinc (II) ions onto a biomaterial - Luffa cylindrica has been studied. This biomaterial was characterized by elemental analysis, surface area, pore size distribution, scanning electron microscopy, and the biomaterial before and after sorption, was characterized by Fourier Transform Infra Red (FTIR) spectrometer. The kinetic nonlinear models fitted were Pseudo-first order, Pseudo-second order and Intra-particle diffusion. A comparison of non-linear regression method in selecting the kinetic model was made. Four error functions, namely coefficient of determination (R{sup 2}), hybrid fractional error function (HYBRID), average relative error (ARE), and sum of the errors squared (ERRSQ), were used to predict the parameters of the kinetic models. The strength of this study is that a biomaterial with wide distribution particularly in the tropical world and which occurs as waste material could be put into effective utilization as a biosorbent to address a crucial environmental problem.

  16. Developments of the ISOLDE RILIS for radioactive ion beam production and the results of their application in the study of exotic mercury isotopes

    CERN Document Server

    Day Goodacre, Thomas; Marsh, Bruce

    This work centres around development and applications of the Resonance Ionization Laser Ion Source (RILIS) of the ISOLDE radioactive ion beam facility based at CERN. The RILIS applies step-wise resonance photo-ionization, to achieve an unparalleled degree of element selectivity, without compromising on ion source efficiency. Because of this, it has become the most commonly used ion source at ISOLDE, operating for up to 75% of ISOLDE experiments. In addition to its normal application as an ion source, the RILIS can be exploited as a spectroscopic tool for the study of nuclear ground state and isomer properties, by resolving the influence of nuclear parameters on the atomic energy levels of the ionization scheme. There are two avenues of development by which to widen the applicability of the RILIS: laser ionization scheme development, enabling new or more efficient laser ionized ion beams and the development of new laser-atom interaction regions. New ionization schemes for chromium, tellurium, germanium, mercu...

  17. A Device Model for Polymer Light-Emitting Diodes with Mobile Ions

    NARCIS (Netherlands)

    Jong, M.J.M. de; Blom, P.W.M.

    1996-01-01

    A model is presented for the device operation of a polymer light-emitting diode (PLED) with mobile ions. It is calculated that the low efficiency of a PLED with a high injection barrier increases as the ions migrate.

  18. Method development estimating ambient mercury concentration from monitored mercury wet deposition

    Directory of Open Access Journals (Sweden)

    S. M. Chen

    2013-05-01

    Full Text Available Speciated atmospheric mercury data have recently been monitored at multiple locations in North America; but the spatial coverage is far less than the long-established mercury wet deposition network. The present study describes a first attempt linking ambient concentration with wet deposition using Beta distribution fitting of a ratio estimate. The mean, median, mode, standard deviation, and skewness of the fitted Beta distribution parameters were generated using data collected in 2009 at 11 monitoring stations. Comparing the normalized histogram and the fitted density function, the empirical and fitted Beta distribution of the ratio shows a close fit. The estimated ambient mercury concentration was further partitioned into reactive gaseous mercury and particulate bound mercury using linear regression model developed by Amos et al. (2012. The method presented here can be used to roughly estimate mercury ambient concentration at locations and/or times where such measurement is not available but where wet deposition is monitored.

  19. Worldwide trend of atmospheric mercury since 1995

    Directory of Open Access Journals (Sweden)

    F. Slemr

    2011-05-01

    Full Text Available Concern about the adverse effects of mercury on human health and ecosystems has led to tightening emission controls since the mid 1980s. But the resulting mercury emissions reductions in many parts of the world are believed to be offset or even surpassed by the increasing emissions in rapidly industrializing countries. Consequently, concentrations of atmospheric mercury are expected to remain roughly constant. Here we show that the worldwide atmospheric mercury concentrations have decreased by about 20 to 38 % since 1996 as indicated by long-term monitoring at stations in the Southern and Northern Hemispheres combined with intermittent measurements of latitudinal distribution over the Atlantic Ocean. The total reduction of the atmospheric mercury burden of this magnitude within 14 years is unusually large among most atmospheric trace gases and is at odds with the current mercury emission inventories with nearly constant anthropogenic emissions over this period. This suggests a major shift in the biogeochemical cycle of mercury including oceans and soil reservoirs. Decreasing reemissions from the legacy of historical mercury emissions are the most likely explanation for this decline since the hypothesis of an accelerated oxidation rate of elemental mercury in the atmosphere is not supported by the observed trends of other trace gases. Acidification of oceans, climate change, excess nutrient input and pollution may also contribute by their impact on the biogeochemistry of ocean and soils. Consequently, models of the atmospheric mercury cycle have to include soil and ocean mercury pools and their dynamics to be able to make projections of future trends.

  20. Thermal stability and modeling of lithium ion batteries

    Science.gov (United States)

    Botte, Gerardine Gabriela

    2000-10-01

    First-principles mathematical models were developed to examine the effect of the lithium-lithium ion interactions inside the anode particles on the performance of a lithium foil cell. Two different models were developed: the chemical potential model (CPM) that includes the lithium-lithium ion interactions inside the anode particles and the diffusion model (DIM) that does not include the interactions. Significant differences in the thermal and electrochemical performance of the cell were observed between the two approaches. The temperature of the cell predicted by the DFM is higher than the one predicted by the CPM at a given capacity. The discharge time of the cell predicted by the DFM is shorter than the one predicted by the CPM. The results indicate that the cell needs to be modeled using the CPM approach especially at high discharge rates. An evaluation of the numerical techniques, control volume formulation (CVF) and finite difference method (FDM), used for the models was performed. It is shown that the truncation error is the same for both methods when the boundary conditions are of the Dirichlet type, the system of equations are linear and represented in Cartesian coordinates. A new technique to analyze the accuracy of the methods is presented. The only disadvantage of the FDM is that it failed to conserve mass for a small number of nodes when both boundary conditions include a derivative term whereas the CVF did conserve mass for these cases. However, for a large number of nodes the FDM provides mass conservation. It is important to note that the CVF has only (DeltaX) order of accuracy for a Neumann type boundary condition whereas the FDM has (DeltaX) 2 order. The second topic of this dissertation presents a study of the thermal stability of LiPF6 EC:EMC electrolyte for lithium ion batteries. A differential scanning calorimeter (DSC) was used to perform the study of the electrolyte. For first time, the effect of different variables on its thermal stability

  1. Surface analysis of Li-ion battery model anodes

    Energy Technology Data Exchange (ETDEWEB)

    Seemayer, Andreas; Bach, Philipp; Renner, Frank Uwe [Max Planck Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Duesseldorf (Germany)

    2011-07-01

    Lithium ion batteries are the most promising power source for future electromobility applications. Research on the battery systems aims to achieve higher rate capability, cycle life, or better safety. To achieve necessary further improvements a better understanding of the basic processes is needed. Following a surface science approach we focus on the investigation of simple model systems (like single crystals or thin film electrodes) of relevant anode materials. We report investigations of the electrochemical insertion of lithium in Au, Ag, Al, Mg and Si model surfaces, i.e. alloying and dealloying of lithium alloys. As electrolyte we use the ionic liquid 1-Butyl-1-methylpyrrolidinium bis(trifluoromethanesolfonyl)imide (PYR14TFSI) with 0.3M LiTFSI. The electrochemical characterisation is performed by cyclic voltammetry (CV). The surface and film characterisation regarding its geometrical structure is investigated by means of scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM). The chemical composition is characterised ex-situ by photoelectron spectroscopy (PES) and secondary ion mass spectrometry (SIMS).

  2. Identification of potential regional sources of atmospheric total gaseous mercury in Windsor, Ontario, Canada using hybrid receptor modeling

    Directory of Open Access Journals (Sweden)

    U. S. Akhtar

    2009-11-01

    Full Text Available Windsor (Ontario – the automotive capital of Canada does not have any significant mercury (Hg sources. However, Windsor experiences trans-boundary air pollution as it is located immediately downwind of industrialized regions of the United States of America. A study was conducted in 2007 aimed to identify the potential regional sources of total gaseous mercury (TGM and investigate the effects of regional sources and other factors on seasonal variability of TGM concentrations in Windsor.

    TGM concentration was measured at the University of Windsor campus using a Tekran® 2537A Hg vapour analyzer. An annual mean of 2.02±1.63 ng/m3 was observed in 2007. The average TGM concentration was high in the summer (2.48 ng/m3 and winter (2.17 ng/m3, compared to spring (1.88 ng/m3 and fall (1.76 ng/m3. Hybrid receptor modeling potential source contribution function (PSCF was used by incorporating 72-h backward trajectories and measurements of TGM in Windsor. The results of PSCF were analyzed in conjunction with the Hg emissions inventory of North America (by state/province to identify regions affecting Windsor. In addition to annual modeling, seasonal PSCF modeling was also conducted. The potential source region was identified between 24–61° N and 51–143° W. Annual PSCF modeling identified major sources southwest of Windsor, stretching from Ohio to Texas. The emissions inventory also supported the findings, as Hg emissions were high in those regions. Results of seasonal PSCF modeling were analyzed to find the combined effects of regional sources, meteorological conditions, and surface reemissions, on intra-annual variability of Hg concentrations. It was found that the summer and winter highs of atmospheric Hg can be attributed to areas where large numbers of coal fired power plants are located in the USA. Weak atmospheric dispersion due to low winds and high reemission from surfaces due

  3. Global Trends in Mercury Management

    Science.gov (United States)

    Choi, Kyunghee

    2012-01-01

    The United Nations Environmental Program Governing Council has regulated mercury as a global pollutant since 2001 and has been preparing the mercury convention, which will have a strongly binding force through Global Mercury Assessment, Global Mercury Partnership Activities, and establishment of the Open-Ended Working Group on Mercury. The European Union maintains an inclusive strategy on risks and contamination of mercury, and has executed the Mercury Export Ban Act since December in 2010. The US Environmental Protection Agency established the Mercury Action Plan (1998) and the Mercury Roadmap (2006) and has proposed systematic mercury management methods to reduce the health risks posed by mercury exposure. Japan, which experienced Minamata disease, aims vigorously at perfection in mercury management in several ways. In Korea, the Ministry of Environment established the Comprehensive Plan and Countermeasures for Mercury Management to prepare for the mercury convention and to reduce risks of mercury to protect public health. PMID:23230466

  4. DNA-based Colorimetric Assay for Fast Detection of Mercury Ions in Urine%基于DNA的比色分析法快速测定尿液中的Hg2+

    Institute of Scientific and Technical Information of China (English)

    赵秋伶; 刘玲玲; 杨丽娜; 张振宇

    2014-01-01

    以琼脂糖珠作为固定 DNA 的载体,建立了可视化的快速检测尿液中 Hg2+的方法。 DNA 对 Hg2+特异性识别后,其构象发生变化,启动相邻序列DNA酶的类过氧化物酶催化活性,进而催化氧化双氧水介导的ABTS(2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸))体系,溶液显绿色。考察了各种物质用量对检测体系的影响。在最优实验条件下,体系在420 nm 处的吸光度与 Hg2+浓度呈良好线性关系,线性范围为5~200 nmol/L,检出限为2 nmol/L。应用于真实尿样中 Hg2+检测,加标回收率为95.1%~99.8%,相对标准偏差(n=5)为1.5%~3.1%。本方法对 Hg2+具有良好的选择性,且检测不受其它金属离子干扰。另外,以琼脂糖珠为固相载体,能实现高效快速分离,有效排除尿液中其它物质对显色的影响,提高了检测的准确度和灵敏度。%A novel colorimetric assay for the rapid detection of mercury ions in urine was established with agarose beads as carrier to capture DNA. Specific recognition of DNA towards mercury ions leads to conformational change and DNAzyme formation caused by DNA conformational change revealed peroxidase-like activities, catalyzing the H2 O2-mediated oxidation of 2, 2-azinobis ( 3-ethylbenzothiozoline )-6-sulfonic acid ( ABTS) to produce green color. The effects of the amount of various substances on detection system were investigated. Under optimal conditions, the absorbances at 420 nm of the system showed a good linear relationship with the concentration of mercury ions ranged from 5 to 200 nmol/L, the detection limit was 2 nmol/L. When tested Hg2+in real urine, the spiked recoveries were from 95. 1% to 99. 8% and the relative standard deviations ( n=5 ) were between 1 . 5% and 3 . 1%. This method had good selectivity for the detection of Hg2+avoiding interference from other metal ions. Furthermore, the fast and efficient separation was achieved with agarose beads as a solid phase carrier to effectively exclude the

  5. A Simple and Highly Sensitive Thymine Sensor for Mercury Ion Detection Based on Surface Enhanced Raman Spectroscopy and the Mechanism Study

    National Research Council Canada - National Science Library

    Hao Yang; Sui-Bo Ye; Yu Fu; Weihong Zhang; Fangyan Xie; Li Gong; Ping-Ping Fang; Jian Chen; Yexiang Tong

    2017-01-01

    ...+ ions over 7 types of alkali, heavy metal and transition-metal ions. Moreover, the LOD of the sensor can even achieve 1 ppb in practical application in the nature system, which is half the maximum allowable level (10 nM, 2 ppb...

  6. Modeling ion exchange in clinoptilolite using the EQ3/6 geochemical modeling code

    Energy Technology Data Exchange (ETDEWEB)

    Viani, B.E.; Bruton, C.J.

    1992-06-01

    Assessing the suitability of Yucca Mtn., NV as a potential repository for high-level nuclear waste requires the means to simulate ion-exchange behavior of zeolites. Vanselow and Gapon convention cation-exchange models have been added to geochemical modeling codes EQ3NR/EQ6, allowing exchange to be modeled for up to three exchangers or a single exchanger with three independent sites. Solid-solution models that are numerically equivalent to the ion-exchange models were derived and also implemented in the code. The Gapon model is inconsistent with experimental adsorption isotherms of trace components in clinoptilolite. A one-site Vanselow model can describe adsorption of Cs or Sr on clinoptilolite, but a two-site Vanselow exchange model is necessary to describe K contents of natural clinoptilolites.

  7. Modeling ion exchange in clinoptilolite using the EQ3/6 geochemical modeling code

    Energy Technology Data Exchange (ETDEWEB)

    Viani, B.E.; Bruton, C.J. [Lawrence Livermore National Lab., CA (United States)

    1992-12-31

    Potential disposal of high-level nuclear waste at Yucca Mtn., Nevada requires the means to simulate ion-exchange behavior of clays and zeolites. Vanselow and Gapon convention cation-exchange models have been added to geochemical modeling codes EQ3NR/EQ6, allowing exchange to be modeled for up to three exchangers or a single exchanger with three independent sites. Solid-solution models that are numerically equivalent to the ion-exchange models were derived and also implemented in the code. The Gapon model is inconsistent with experimental adsorption isotherms of trace components in clinoptilolite. A one-site Vanselow model can describe adsorption of Cs and Sr on clinoptilolite, but a two-site Vanselow exchange model is necessary to describe K contents of natural clinoptilolites. 15 refs., 5 figs., 1 tab.

  8. Heavy Ions Collision evolution modeling with ECHO-QGP

    CERN Document Server

    Rolando, Valentina; Beraudo, Andrea; Del Zanna, Luca; Becattini, Francesco; Chandra, Vinod; De Pace, Arturo; Nardi, Marzia

    2014-01-01

    We present a numerical code modeling the evolution of the medium formed in relativistic heavy ion collisions, ECHO-QGP. The code solves relativistic hydrodynamics in $(3+1)-$D, with dissipative terms included within the framework of Israel-Stewart theory; it can work both in Minkowskian and in Bjorken coordinates. Initial conditions are provided through an implementation of the Glauber model (both Optical and Monte Carlo), while freezeout and particle generation are based on the Cooper-Frye prescription. The code is validated against several test problems and shows remarkable stability and accuracy with the combination of a conservative (shock-capturing) approach and the high-order methods employed. In particular it beautifully agrees with the semi-analytic solution known as Gubser flow, both in the ideal and in the viscous Israel-Stewart case, up to very large times and without any ad hoc tuning of the algorithm.

  9. Modeling Crabbing Dynamics in an Electron-Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Castilla, Alejandro [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Univ. de Guanajuato (DCI-UG), Leon (Mexico); Morozov, Vasiliy S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Satogata, Todd J. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Delayen, Jean R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)

    2015-09-01

    A local crabbing scheme requires π/2 (mod π) horizontal betatron phase advances from an interaction point (IP) to the crab cavities on each side of it. However, realistic phase advances generated by sets of quadrupoles, or Final Focusing Blocks (FFB), between the crab cavities located in the expanded beam regions and the IP differ slightly from π/2. To understand the effect of crabbing on the beam dynamics in this case, a simple model of the optics of the Medium Energy Electron-Ion Collider (MEIC) including local crabbing was developed using linear matrices and then studied numerically over multiple turns (1000 passes) of both electron and proton bunches. The same model was applied to both local and global crabbing schemes to determine the linear-order dynamical effects of the synchro-betatron coupling induced by crabbing.

  10. Use of criteria pollutants, active and passive mercury sampling, and receptor modeling to understand the chemical forms of gaseous oxidized mercury in Florida

    Directory of Open Access Journals (Sweden)

    J. Huang

    2015-04-01

    Full Text Available The highest mercury (Hg wet deposition in the United States (US occurs along the Gulf of Mexico, and in the southern and central Mississippi River Valley. Gaseous oxidized Hg (GOM is thought to be a major contributor due to its high water solubility and reactivity. Therefore, it is critical to understand the concentrations, potential for wet and dry deposition, and GOM compounds present in the air. Concentrations and dry deposition fluxes of GOM were measured at Outlying Landing Field (OLF, Florida, using a Tekran® 2537/1130/1135, and active and passive samplers using cation-exchange and nylon membranes. Relationships with Tekran® derived data must be interpreted with caution, since GOM concentrations can be biased low depending on the chemical compounds in air, and interferences with water vapor and ozone. Only gaseous elemental Hg and GOM are discussed here since the PBM measurement uncertainties are higher. Criteria air pollutants were concurrently measured and Tekran® data were assessed along with these using Principal Component Analysis to identify associations among air pollutants. Based on the diel pattern, high GOM concentrations at this site were associated with fossil fuel combustion and gas phase oxidation during the day, and gas phase oxidation and transport in the free troposphere. The ratio of GEM/CO at OLF (0.008 ng m−3 ppbv−1 was much higher than the numbers reported for the Western United States and central New York for domestic emissions or biomass burning (0.001 ng m−3 ppbv−1, which we suggest is indicative of a marine boundary layer source. Results from nylon membranes with thermal desorption analyses suggest five potential GOM compounds exist in this area, including HgBr2, HgO, Hg(NO32, HgSO4, and an unknown compound. This indicates that the site is influenced by different gaseous phase reactions and sources. A~high GOM event related to high CO but average SO2 suggests the air parcels moved from the free

  11. Effect of water quality on mercury toxicity to Photobacterium phosphoreum: Model development and its application in natural waters.

    Science.gov (United States)

    Wang, Xinghao; Qu, Ruijuan; Wei, Zhongbo; Yang, Xi; Wang, Zunyao

    2014-06-01

    Mercury (Hg) compounds are widely distributed toxic environmental and industrial pollutants and they may bring danger to growth and development of aquatic organisms. The distribution of Hg species in the 3 percent NaCl solution was calculated using the chemical equilibrium model Visual MINTEQ, which demonstrated that Hg was mainly complexed by chlorides in the pH range 5.0-9.0 and the proportions of HgCl4(2-), HgCl3(-) and HgCl2(aq) reached to 95 percent of total Hg. Then the effects of cations (Ca(2+), Mg(2+), K(+) and H(+)), anions (HCO3(-), NO3(-), SO4(2-) and HPO4(2-)) and complexing agents (ethylene diamine tetraacetic acid (EDTA) and dissolved organic matter (DOM)) on Hg toxicity to Photobacterium phosphoreum were evaluated in standardized 15min acute toxicity tests. The significant increase of 6.3-fold in EC50 data with increasing pH was observed over the tested pH range of 5.0-8.0, which suggested the possible competition between hydroxyl and the negatively charged chloro-complex. By contrast, it was found that major cations (Ca(2+), Mg(2+) and K(+)) have little effect on Hg toxicity to P. phosphoreum. An interesting finding was that the addition of HPO4(2-) significantly increased Hg toxicity, which may imply that the addition of phosphate increased the soluble Hg-chloro complex species. Additions of complexing agents (EDTA and DOM) into the exposure water increased Hg bioavailability via complexation of Hg. Finally, a model which incorporated the effect of pH, HPO4(2-), HCO3(-), SO4(2-) and DOM on Hg toxicity was developed to predict acute Hg toxicity for P. phosphoreum, which may be a useful tool in setting realistic water quality criteria for different types of water.

  12. How Tiny Collisions Shape Mercury

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    If space rocks are unpleasant to encounter, space dust isnt much better. Mercurys cratered surface tells of billions of years of meteoroid impacts but its thin atmosphere is what reveals its collisional history with smaller impactors. Now new research is providing a better understanding of what were seeing.Micrometeoroids Ho!The inner solar system is bombarded by micrometeoroids, tiny particles of dust (on the scale of a tenth of a millimeter) emitted by asteroids and comets as they make their closest approach to the Sun. This dust doesnt penetrateEarths layers of atmosphere, but the innermost planet of our solar system, Mercury, doesnt have this convenient cushioning.Just as Mercury is affected by the impacts of large meteoroids, its also shaped by the many smaller-scale impacts it experiences. These tiny collisions are thought to vaporize atoms and molecules from the planets surface, which quickly dissociate. This process adds metals to Mercurys exosphere, the planets extremely tenuous atmosphere.Modeling PopulationsDistribution of the directions from which meteoroids originate before impacting Mercurys surface, as averaged over its entire orbit. Local time of 12 hr corresponds to the Sun-facing side. A significant asymmetry is seen between the dawn (6 hrs) and dusk (18 hrs) rates. [Pokorn et al. 2017]The metal distribution in the exosphere provides a way for us to measure the effect of micrometeoroid impacts on Mercury but this only works if we have accurate models of the process. A team of scientists led by Petr Pokorn (The Catholic University of America and NASA Goddard SFC) has now worked to improve our picture of micrometeoroid impact vaporization on Mercury.Pokorn and collaborators argue that two meteoroid populations Jupiter-family comets (short-period) and Halley-type comets (long-period) contribute the dust for the majority of micrometeoroid impacts on Mercury. The authors model the dynamics and evolution of these two populations, reproducing the

  13. Mechanisms of mercury bioremediation.

    Science.gov (United States)

    Essa, A M M; Macaskie, L E; Brown, N L

    2002-08-01

    Mercury is one of the most toxic heavy metals, and has significant industrial and agricultural uses. These uses have led to severe localized mercury pollution. Mercury volatilization after its reduction to the metallic form by mercury-resistant bacteria has been reported as a mechanism for mercury bioremediation [Brunke, Deckwer, Frischmuth, Horn, Lunsdorf, Rhode, Rohricht, Timmis and Weppen (1993) FEMS Microbiol. Rev. 11, 145-152; von Canstein, Timmis, Deckwer and Wagner-Dobler (1999) Appl. Environ. Microbiol. 65, 5279-5284]. The reduction/volatilization system requires to be studied further, in order to eliminate the escape of the metallic mercury into the environment. Recently we have demonstrated three different mechanisms for mercury detoxification in one organism, Klebsiella pneumoniae M426, which may increase the capture efficiency of mercury.

  14. Mercury Continuous Emmission Monitor Calibration

    Energy Technology Data Exchange (ETDEWEB)

    John Schabron; Eric Kalberer; Ryan Boysen; William Schuster; Joseph Rovani

    2009-03-12

    Mercury continuous emissions monitoring systems (CEMs) are being implemented in over 800 coal-fired power plant stacks throughput the U.S. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor calibrators/generators. These devices are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 and vacated by a Federal appeals court in early 2008 required that calibration be performed with NIST-traceable standards. Despite the vacature, mercury emissions regulations in the future will require NIST traceable calibration standards, and EPA does not want to interrupt the effort towards developing NIST traceability protocols. The traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued a conceptual interim traceability protocol for elemental mercury calibrators. The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The EPA traceability protocol document is divided into two separate sections. The first deals with the qualification of calibrator models by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the calibrators that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma

  15. Low-cost Adsorbents for the Removal of Mercury (11 from Aqueous Solution-A Comparative Study

    Directory of Open Access Journals (Sweden)

    Ajay Kumar Meena

    2004-10-01

    Full Text Available The establishments of the Ministry of Defence, specifically ordnance factories and public sector undertakings (like Bharat Electronics Ltd, carry out operations like electroplating, metal1surface finishing, solid-state wafer processing, and initiatory manufacturing (lead azide, mercury fulminate, which generate waste water contaminated with hazardous heavy metals. Mercuryand its compounds are known to be highly toxic, both for the living organisms and theenvironment. To protect public health, a regulatory discharge standard of mercury, as low as 0.01 mgll, has been imposed and is expected to be even stricter in the future. A promising method for effective mercury discharge control is to employ suitable adsorbents for the removal of mercury from the contaminated aqueous stream.This paper describes the effectiveness of low cost and locally available, untreated and chemically-treated adsorbents for the removal of mercury from the aqueous solution. Their effectiveness has been compared with that of chemically-treated granular activated carbon. Treated sawdust and untreated weathered coal were found to be the most suitable low-cost adsorbents in addition to treated granular activated carbon for the removal of mercury from aqueous solution. Under the optimised conditions, ie, adsorbent dose 10 gll, pH 6, contact time 48 h, and initial concentration of mercury 3 mgll, the removal of mercury was found to be 99.8 per cent, 99.8 per cent, and 99.7per cent, using treated granular activated carbon, treated sawhust, and untreated weathered coal, respectively.The adsorption parameters were determined using both Langmuir and Freundlich isotherm models. Surface complexation and ion exchange were the major removal mechanisms involved.The adsorption isotherm studies clearly indicated that the Langmuir model is in good agreement, with the experimental data on the adsorptive behaviour of mercury on treated granular activated carbon, whereas, the experimental data

  16. Lithium-ion battery models: a comparative study and a model-based powerline communication

    Science.gov (United States)

    Saidani, Fida; Hutter, Franz X.; Scurtu, Rares-George; Braunwarth, Wolfgang; Burghartz, Joachim N.

    2017-09-01

    In this work, various Lithium-ion (Li-ion) battery models are evaluated according to their accuracy, complexity and physical interpretability. An initial classification into physical, empirical and abstract models is introduced. Also known as white, black and grey boxes, respectively, the nature and characteristics of these model types are compared. Since the Li-ion battery cell is a thermo-electro-chemical system, the models are either in the thermal or in the electrochemical state-space. Physical models attempt to capture key features of the physical process inside the cell. Empirical models describe the system with empirical parameters offering poor analytical, whereas abstract models provide an alternative representation. In addition, a model selection guideline is proposed based on applications and design requirements. A complex model with a detailed analytical insight is of use for battery designers but impractical for real-time applications and in situ diagnosis. In automotive applications, an abstract model reproducing the battery behavior in an equivalent but more practical form, mainly as an equivalent circuit diagram, is recommended for the purpose of battery management. As a general rule, a trade-off should be reached between the high fidelity and the computational feasibility. Especially if the model is embedded in a real-time monitoring unit such as a microprocessor or a FPGA, the calculation time and memory requirements rise dramatically with a higher number of parameters. Moreover, examples of equivalent circuit models of Lithium-ion batteries are covered. Equivalent circuit topologies are introduced and compared according to the previously introduced criteria. An experimental sequence to model a 20 Ah cell is presented and the results are used for the purposes of powerline communication.

  17. Lithium-ion battery models: a comparative study and a model-based powerline communication

    Directory of Open Access Journals (Sweden)

    F. Saidani

    2017-09-01

    Full Text Available In this work, various Lithium-ion (Li-ion battery models are evaluated according to their accuracy, complexity and physical interpretability. An initial classification into physical, empirical and abstract models is introduced. Also known as white, black and grey boxes, respectively, the nature and characteristics of these model types are compared. Since the Li-ion battery cell is a thermo-electro-chemical system, the