Shedding light on the mercury mass discrepancy by weighing Hg52+ ions in a Penning trap

International Nuclear Information System (INIS)

Fritioff, T.; Bluhme, H.; Schuch, R.; Bergstroem, I.; Bjoerkhage, M.

2003-01-01

In their nuclear tables Audi and Wapstra have pointed out a serious mass discrepancy between their extrapolated values for the mercury isotopes and those from a direct measurement by the Manitoba group. The values deviate by as much as 85 ppb from each other with claimed uncertainties of about 16 and 7 ppb, respectively. In order to decide which values are correct the masses of the 198 Hg and 204 Hg isotopes have been measured in the Stockholm Penning trap mass spectrometer SMILETRAP using 52+ ions. This charge state corresponds to a filled Ni electron configuration for which the electron binding energy can be accurately calculated. The mass values obtained are 197.966 768 44(43) u for 198 Hg and 203.973 494 10(39) u for 204 Hg. These values agree with those measured by the Manitoba group, with a 3 times lower uncertainty. This measurement was made possible through the implementation of a cooling technique of the highly charged mercury ions during charge breeding in the electron beam ion source used for producing the Hg 52+ ions

Detailed Assessment of the Kinetics of Hg-Cell Association, Hg Methylation, and Methylmercury Degradation in Several Desulfovibrio Species

Science.gov (United States)

Graham, Andrew M.; Bullock, Allyson L.; Maizel, Andrew C.; Elias, Dwayne A.

2012-01-01

The kinetics of inorganic Hg [Hg(II)i] association, methylation, and methylmercury (MeHg) demethylation were examined for a group of Desulfovibrio species with and without MeHg production capability. We employed a detailed method for assessing MeHg production in cultures, including careful control of medium chemistry, cell density, and growth phase, plus mass balance of Hg(II)i and MeHg during the assays. We tested the hypothesis that differences in Hg(II)i sorption and/or uptake rates drive observed differences in methylation rates among Desulfovibrio species. Hg(II)i associated rapidly and with high affinity to both methylating and nonmethylating species. MeHg production by Hg-methylating strains was rapid, plateauing after ∼3 h. All MeHg produced was rapidly exported. We also tested the idea that all Desulfovibrio species are capable of Hg(II)i methylation but that rapid demethylation masks its production, but we found this was not the case. Therefore, the underlying reason why MeHg production capability is not universal in the Desulfovibrio is not differences in Hg affinity for cells nor differences in the ability of strains to degrade MeHg. However, Hg methylation rates varied substantially between Hg-methylating Desulfovibrio species even in these controlled experiments and after normalization to cell density. Thus, biological differences may drive cross-species differences in Hg methylation rates. As part of this study, we identified four new Hg methylators (Desulfovibrio aespoeensis, D. alkalitolerans, D. psychrotolerans, and D. sulfodismutans) and four nonmethylating species (Desulfovibrio alcoholivorans, D. tunisiensis, D. carbinoliphilus, and D. piger) in our ongoing effort to generate a library of strains for Hg methylation genomics. PMID:22885751

A mass balance mercury budget for a mine-dominated lake: Clear Lake, California

Science.gov (United States)

Suchanek, T.H.; Cooke, J.; Keller, K.; Jorgensen, S.; Richerson, P.J.; Eagles-Smith, Collin A.; Harner, E.J.; Adam, D.P.

2009-01-01

The Sulphur Bank Mercury Mine (SBMM), active intermittently from 1873–1957 and now a USEPA Superfund site, was previously estimated to have contributed at least 100 metric tons (105 kg) of mercury (Hg) into the Clear Lake aquatic ecosystem. We have confirmed this minimum estimate. To better quantify the contribution of the mine in relation to other sources of Hg loading into Clear Lake and provide data that might help reduce that loading, we analyzed Inputs and Outputs of Hg to Clear Lake and Storage of Hg in lakebed sediments using a mass balance approach. We evaluated Inputs from (1) wet and dry atmospheric deposition from both global/regional and local sources, (2) watershed tributaries, (3) groundwater inflows, (4) lakebed springs and (5) the mine. Outputs were quantified from (1) efflux (volatilization) of Hg from the lake surface to the atmosphere, (2) municipal and agricultural water diversions, (3) losses from out-flowing drainage of Cache Creek that feeds into the California Central Valley and (4) biotic Hg removal by humans and wildlife. Storage estimates include (1) sediment burial from historic and prehistoric periods (over the past 150–3,000 years) from sediment cores to ca. 2.5m depth dated using dichloro diphenyl dichloroethane (DDD), 210Pb and 14C and (2) recent Hg deposition in surficial sediments. Surficial sediments collected in October 2003 (11 years after mine site remediation) indicate no reduction (but a possible increase) in sediment Hg concentrations over that time and suggest that remediation has not significantly reduced overall Hg loading to the lake. Currently, the mine is believed to contribute ca. 322–331 kg of Hg annually to Clear Lake, which represents ca. 86–99% of the total Hg loading to the lake. We estimate that natural sedimentation would cover the existing contaminated sediments within ca. 150–300 years.

On the Mass Balance of Asphaltene Precipitation

DEFF Research Database (Denmark)

Andersen, Simon Ivar; Lira-Galeana, C.; Stenby, Erling Halfdan

2001-01-01

In the evaluation of experimental data as well as in calculation of phase equilibria the necessity of the application of mass balances is obvious. In the case of asphaltenes the colloidal nature of these compounds may highly affect the mass balance. In the present paper several experiments are pe......, and that the material in the second precipitation step was often of higher apparent molecular weight anti had an increased overall absorbance coefficient.......In the evaluation of experimental data as well as in calculation of phase equilibria the necessity of the application of mass balances is obvious. In the case of asphaltenes the colloidal nature of these compounds may highly affect the mass balance. In the present paper several experiments...... indicates that in temperature experiments as well as in solvent series experiments the precipitation of heavy asphaltenes affects the following precipitation of lighter asphaltenes. In both cases the mass balance using standard separation techniques cannot be closed, as less material is precipitated...

Mass balance gradients and climatic change

NARCIS (Netherlands)

Oerlemans, J.; Hoogendoorn, N.C.

1989-01-01

It is generally assumed that the mass-balance gradient on glaciers is more or less conserved under climatic change. In studies of the dynamic response of glaciers to climatic change, one of the following assumptions is normally made: (i) the mass-balance perturbation is independent of altitude

Excitation energy dependence of fragment-mass distributions from fission of 180,190Hg formed in fusion reactions of 36Ar + 144,154Sm

Directory of Open Access Journals (Sweden)

K. Nishio

2015-09-01

Full Text Available Mass distributions of fission fragments from the compound nuclei 180Hg and 190Hg formed in fusion reactions 36Ar + 144Sm and 36Ar + 154Sm, respectively, were measured at initial excitation energies of E⁎(Hg180=33–66 MeV and E⁎(Hg190=48–71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses A¯L/A¯H=79/101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β+/EC-delayed fission of 180Tl, from our earlier ISOLDE(CERN experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of A¯L/A¯H=83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.

Juneau Icefield Mass Balance Program 1946-2011

Science.gov (United States)

Pelto, M.; Kavanaugh, J.; McNeil, C.

2013-11-01

The annual surface mass balance records of the Lemon Creek Glacier and Taku Glacier observed by the Juneau Icefield Research Program are the longest continuous glacier annual mass balance data sets in North America. Annual surface mass balance (Ba) measured on Taku Glacier averaged +0.40 m a-1 from 1946-1985, and -0.08 m a-1 from 1986-2011. The recent annual mass balance decline has resulted in the cessation of the long-term thickening of the glacier. Mean Ba on Lemon Creek Glacier has declined from -0.30 m a-1 for the 1953-1985 period to -0.60 m a-1 during the 1986-2011 period. The cumulative change in annual surface mass balance is -26.6 m water equivalent, a 29 m of ice thinning over the 55 yr. Snow-pit measurements spanning the accumulation zone, and probing transects above the transient snow line (TSL) on Taku Glacier, indicate a consistent surface mass balance gradient from year to year. Observations of the rate of TSL rise on Lemon Creek Glacier and Taku Glacier indicate a comparatively consistent migration rate of 3.8 to 4.1 m d-1. The relationship between TSL on Lemon Creek Glacier and Taku Glacier to other Juneau Icefield glaciers (Norris, Mendenhall, Herbert, and Eagle) is strong, with correlations exceeding 0.82 in all cases. doi:10.5065/D6NZ85N3

Trends in ice sheet mass balance, 1992 to 2017

Science.gov (United States)

Shepherd, A.; Ivins, E. R.; Smith, B.; Velicogna, I.; Whitehouse, P. L.; Rignot, E. J.; van den Broeke, M. R.; Briggs, K.; Hogg, A.; Krinner, G.; Joughin, I. R.; Nowicki, S.; Payne, A. J.; Scambos, T.; Schlegel, N.; Moyano, G.; Konrad, H.

2017-12-01

The Ice Sheet Mass Balance Inter-Comparison Exercise (IMBIE) is a community effort, jointly supported by ESA and NASA, that aims to provide a consensus estimate of ice sheet mass balance from satellite gravimetry, altimetry and mass budget assessments, on an annual basis. The project has five experiment groups, one for each of the satellite techniques and two others to analyse surface mass balance (SMB) and glacial isostatic adjustment (GIA). The basic premise for the exercise is that individual ice sheet mass balance datasets are generated by project participants using common spatial and temporal domains to allow meaningful inter-comparison, and this controlled comparison in turn supports aggregation of the individual datasets over their full period. Participation is open to the full community, and the quality and consistency of submissions is regulated through a series of data standards and documentation requirements. The second phase of IMBIE commenced in 2015, with participant data submitted in 2016 and a combined estimate due for public release in 2017. Data from 48 participant groups were submitted to one of the three satellite mass balance technique groups or to the ancillary dataset groups. The individual mass balance estimates and ancillary datasets have been compared and combined within the respective groups. Following this, estimates of ice sheet mass balance derived from the individual techniques were then compared and combined. The result is single estimates of ice sheet mass balance for Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula. The participants, methodology and results of the exercise will be presented in this paper.

Quantifying mass balance processes on the Southern Patagonia Icefield

DEFF Research Database (Denmark)

Schaefer, M.; Machguth, Horst; Falvey, M.

2015-01-01

We present surface mass balance simulations of the Southern Patagonia Icefield (SPI) driven by downscaled reanalysis data. The simulations were evaluated and interpreted using geodetic mass balances, measured point balances and a complete velocity field of the icefield for spring 2004. The high m...

A reconciled estimate of ice-sheet mass balance

DEFF Research Database (Denmark)

Shepherd, Andrew; Ivins, Erik R; A, Geruo

2012-01-01

We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agre...

A portable, automated, inexpensive mass and balance calibration system

International Nuclear Information System (INIS)

Maxwell, S.L. III; Clark, J.P.

1987-01-01

Reliable mass measurements are essential for a nuclear production facility or process control laboratory. DOE Order 5630.2 requires that traceable standards be used to calibrate and monitor equipment used for nuclear material measurements. To ensure the reliability of mass measurements and to comply with DOE traceability requirements, a portable, automated mass and balance calibration system is used at the Savannah River Plant. Automation is achieved using an EPSON HX-20 notebook computer, which can be operated via RS232C interfacing to electronic balances or function with manual data entry if computer interfacing is not feasible. This economical, comprehensive, user-friendly system has three main functions in a mass measurement control program (MMCP): balance certification, calibration of mass standards, and daily measurement of traceable standards. The balance certification program tests for accuracy, precision, sensitivity, linearity, and cornerloading versus specific requirements. The mass calibration program allows rapid calibration of inexpensive mass standards traceable to certified Class S standards. This MMCP permits daily measurement of traceable standards to monitor the reliability of balances during routine use. The automated system verifies balance calibration, stores results for future use, and provides a printed control chart of the stored data. Another feature of the system permits three different weighing routines that accommodate their need for varying degrees of reliability in routine weighing operations

A portable, automated, inexpensive mass and balance calibration system

International Nuclear Information System (INIS)

Maxwell, S.L. III; Clark, J.P.

1987-01-01

Reliable mass measurements are essential for a nuclear production facility or process control laboratory. DOE Order 5630.2 requires that traceable standards be used to calibrate and monitor equipment used for nuclear material measurements. To ensure the reliability of mass measurements and to comply with DOE traceable requirements, a portable, automated mass and balance calibration system is used at the Savannah River Plant. Automation is achieved using an EPSON HX-20 notebook computer, which can be operated via RS232C interfacing to electronic balances or function with manual data entry if computer interfacing is not feasible. This economical, comprehensive, user-friendly system has three main functions in a mass measurement control program (MMCP): balance certification, calibration of mass standards, and daily measurement of traceable standards. The balance certification program tests for accuracy, precision, sensitivity, linearity, and cornerloading versus specific requirements. The mass calibration program allows rapid calibration of inexpensive mass standards traceable to certified Class S standards. This MMCP permits daily measurement of traceable standards to monitor the reliability of balances during routine use. The automated system verifies balance calibration, stores results for future use, and provides a printed control chart of the stored data. Another feature of the system permits three different weighing routines that accommodate our need for varying degrees of reliability in routine weighing operations. 1 ref

Anaerobic Digestion: Mass Balances and Products

DEFF Research Database (Denmark)

Møller, Jacob; Christensen, Thomas Højlund; Jansen, Jes la Cour

2011-01-01

While the basic processes involved in anaerobic digestion of waste are described in Chapter 9.4 and the main digestion technologies are presented in Chapter 9.5, this chapter focuses on mass balances, gas production and energy aspects, environmental emissions and unit process inventories. Underst......While the basic processes involved in anaerobic digestion of waste are described in Chapter 9.4 and the main digestion technologies are presented in Chapter 9.5, this chapter focuses on mass balances, gas production and energy aspects, environmental emissions and unit process inventories...

Decay of mass-separated 189mHg (8.7 min) and 189gHg (7.7 min) to 189Au

International Nuclear Information System (INIS)

Wood, J.L.; Zganjar, E.F.; Semmes, P.B.

1996-01-01

The decays of 189 Hg (8.7 min; J π =13/2 + ) and 189 Hg (7.7 min; J π =3/2 - ) have been studied with mass-separated sources from the UNISOR facility. Multiscaled spectra of γ-rays, X-rays, and conversion electrons, as well as γγt, γXt, eγt, and eXt coincidences were obtained. Decay schemes have been constructed incorporating >95% of the decay intensities assigned to the high-spin and low-spin decays. The γ-ray gated conversion-electron spectra permitted the determination of 119 conversion-electron subshell ratios. Portions of the level scheme bear a remarkable resemblance to the heavier and lighter odd-mass Au isotopes. An extensive band of states is observed built upon the h 9/2 intruder state at 325 keV. This band is markedly different from the corresponding bands in 187 Au and 185 Au, indicating a major change in the cores, i.e. between 188 Pt and 186,184 Pt. Evidence for oblate-hole-prolate-particle symmetry in 189 Au is discussed. Completeness of complex decay schemes far from stability is addressed. (orig.)

Calibration of a surface mass balance model for global-scale applications

NARCIS (Netherlands)

Giesen, R. H.; Oerlemans, J.

2012-01-01

Global applications of surface mass balance models have large uncertainties, as a result of poor climate input data and limited availability of mass balance measurements. This study addresses several possible consequences of these limitations for the modelled mass balance. This is done by applying a

Reconstruction of specific mass balance for glaciers in Western ...

Indian Academy of Sciences (India)

Vinay Kumar Gaddam

2017-06-12

Jun 12, 2017 ... temperatures and precipitation estimates of ERA 20CM ensemble climate reanalysis datasets to reconstruct the specific mass balance for a period of 110 years, between 1900 and 2010. Mass balance estimates suggest that the Shaune Garang, Gor-Garang and Gara glaciers have experienced both ...

Mass balance at partial run of quartzite carbothermal reduction

Directory of Open Access Journals (Sweden)

J. Węgrzyn

2016-04-01

Full Text Available Mass balance for the process of incomplete carbothermal reduction of SiO2 to SiC thermogravimetric studies was presented. Tests were performed for the molar ratio of C/SiO2 = 3 at a temperature of 1 500 °C under an argon flow in the range from 0,1 to 3,4 dm3/min. Mass balance includes the loss due to escape of SiO and the mass of reactants C and SiO2 due to stopping the reaction. The weight gain of Al2O3 crucible was found and also the formation of crust layer on the surface of the samples. The crucible weight gain and the weight of crust layer created were taken into account in mass balance.

Effect of mass asymmetry on the mass dependence of balance energy

International Nuclear Information System (INIS)

Goyal, Supriya

2011-01-01

We demonstrate the role of the mass asymmetry on the balance energy (E bal ) by studying asymmetric reactions throughout the periodic table and over entire colliding geometry. Our results, which are almost independent of the system size and as well as of the colliding geometries indicate a sizeable effect of the asymmetry of the reaction on the balance energy.

Mass-balance measurements in Alaska and suggestions for simplified observation programs

Science.gov (United States)

Trabant, D.C.; March, R.S.

1999-01-01

US Geological Survey glacier fieldwork in Alaska includes repetitious measurements, corrections for leaning or bending stakes, an ability to reliably measure seasonal snow as deep as 10 m, absolute identification of summer surfaces in the accumulation area, and annual evaluation of internal accumulation, internal ablation, and glacier-thickness changes. Prescribed field measurement and note-taking techniques help eliminate field errors and expedite the interpretative process. In the office, field notes are transferred to computerized spread-sheets for analysis, release on the World Wide Web, and archival storage. The spreadsheets have error traps to help eliminate note-taking and transcription errors. Rigorous error analysis ends when mass-balance measurements are extrapolated and integrated with area to determine glacier and basin mass balances. Unassessable errors in the glacier and basin mass-balance data reduce the value of the data set for correlations with climate change indices. The minimum glacier mass-balance program has at least three measurement sites on a glacier and the measurements must include the seasonal components of mass balance as well as the annual balance.

Remote Sensing of Cryosphere: Estimation of Mass Balance Change in Himalayan Glaciers

Science.gov (United States)

Ambinakudige, Shrinidhi; Joshi, Kabindra

2012-07-01

Glacial changes are an important indicator of climate change. Our understanding mass balance change in Himalayan glaciers is limited. This study estimates mass balance of some major glaciers in the Sagarmatha National Park (SNP) in Nepal using remote sensing applications. Remote sensing technique to measure mass balance of glaciers is an important methodological advance in the highly rugged Himalayan terrain. This study uses ASTER VNIR, 3N (nadir view) and 3B (backward view) bands to generate Digital Elevation Models (DEMs) for the SNP area for the years 2002, 2003, 2004 and 2005. Glacier boundaries were delineated using combination of boundaries available in the Global land ice measurement (GLIMS) database and various band ratios derived from ASTER images. Elevation differences, glacial area, and ice densities were used to estimate the change in mass balance. The results indicated that the rate of glacier mass balance change was not uniform across glaciers. While there was a decrease in mass balance of some glaciers, some showed increase. This paper discusses how each glacier in the SNP area varied in its annual mass balance measurement during the study period.

Antarctic Glacial Isostatic Adjustment and Ice Sheet Mass Balance using GRACE: A Report from the Ice-sheet Mass Balance Exercise (IMBIE)

Science.gov (United States)

Ivins, E. R.; Wahr, J. M.; Schrama, E. J.; Milne, G. A.; Barletta, V.; Horwath, M.; Whitehouse, P.

2012-12-01

In preparation for the Inter-govermental Panel on Climate Change: Assessment Report 5 (IPCC AR5), ESA and NASA have formed a committee of experts to perform a formal set of comparative experiments concerning space observations of ice sheet mass balance. This project began in August of 2011 and has now concluded with a report submitted for Science (Shepherd et al., 2012). The focus of the work conducted is to re-evaluate scientific reports on the mass balance of Greenland ice sheet (GIS) and Antarctic ice sheet (AIS). The most serious discrepancies have been reported for the AIS, amounting to as much as 0.9 mm/yr in discrepant sea level contribution. A direct method of determining the AIS is by space gravimetry. However, for this method to contribute to our understanding of sea level change, we require knowledge of present-day non-elastic vertical movements of bedrock in Antarctica. Quantifying the uncertainty and bias caused by lack of observational control on models of regional glacial isostatic adjustment (GIA), was a major focus for our experiments. This regional process is the most problematic error source for GRACE-determinations of ice mass balance in Antarctica. While GIA likely dominates some large vertical motions in Antarctica that are now observed with GPS (Thomas et al., 2011, GRL), interpretations still require models. The reported uncertainty for space gravimetric (GRACE) based sea level sourcing is roughly 0.20 to 0.35 mm/yr. The uncertainty is also part of the error budget for mass balances derived from altimetry measurements, though at a much lower level. Analysis of the GRACE time series using CSR RL04 (2003.0-2010.10) for AIS mass balance reveals a small trend of order +1 to -24 Gt/yr without a GIA correction. Three periods were selected over which to perform inter-comparisons (see Table). One class of GIA models, that relies primarily on far field sea level reconstructions (e.g. ICE-5G), provide a GIA correction that places AIS mass imbalance (�

Decay studies and mass measurements on isobarically pure neutron-rich Hg and Tl isotopes

CERN Multimedia

Schweikhard, L C; Savreux, R P; Hager, U D K; Beck, D; Blaum, K

2007-01-01

We propose to perform mass measurements followed by $\\beta$- and $\\gamma$-decay studies on isobarically pure beams of neutron-rich Hg and Tl isotopes, which are very poorly known due to a large contamination at ISOL-facilities with surface-ionised francium. The aim is to study the binding energies of mother Hg and Tl nuclides, as well as the energies, spins and parities of the excited and ground states in the daughter Tl and Pb isotopes. The proposed studies will address a new subsection of the nuclear chart, with Z 126, where only 9 nuclides have been observed so far. Our studies will provide valuable input for mass models and shell-model calculations: they will probe the proton hole-neutron interaction and will allow to refine the matrix elements for the two-body residual interaction. Furthermore, they also give prospects for discovering new isomeric states or even new isotopes, for which the half-lives are predicted in the minute- and second-range.\\\\ To reach the isobaric purity, the experiments will be p...

Quantifying the resolution level where the GRACE satellites can separate Greenland's glacial mass balance from surface mass balance

Science.gov (United States)

Bonin, J. A.; Chambers, D. P.

2015-09-01

Mass change over Greenland can be caused by either changes in the glacial dynamic mass balance (DMB) or the surface mass balance (SMB). The GRACE satellite gravity mission cannot directly separate the two physical causes because it measures the sum of the entire mass column with limited spatial resolution. We demonstrate one theoretical way to indirectly separate cumulative SMB from DMB with GRACE, using a least squares inversion technique with knowledge of the location of the glaciers. However, we find that the limited 60 × 60 spherical harmonic representation of current GRACE data does not provide sufficient resolution to adequately accomplish the task. We determine that at a maximum degree/order of 90 × 90 or above, a noise-free gravity measurement could theoretically separate the SMB from DMB signals. However, current GRACE satellite errors are too large at present to separate the signals. A noise reduction of a factor of 10 at a resolution of 90 × 90 would provide the accuracy needed for the interannual cumulative SMB and DMB to be accurately separated.

Myths and methodologies: Making sense of exercise mass and water balance.

Science.gov (United States)

Cheuvront, Samuel N; Montain, Scott J

2017-09-01

What is the topic of this review? There is a need to revisit the basic principles of exercise mass and water balance, the use of common equations and the practice of interpreting outcomes. What advances does it highlight? We propose use of the following equation as a way of simplifying exercise mass and water balance calculations in conditions where food is not consumed and waste is not excreted: ∆body mass - 0.20 g/kcal -1  = ∆body water. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass - 0.20 g kcal -1 )/starting body mass] × 100. Changes in body mass occur because of flux in liquids, solids and gases. This knowledge is crucial for understanding metabolism, health and human water needs. In exercise science, corrections to observed changes in body mass to estimate water balance are inconsistently applied and often misinterpreted, particularly after prolonged exercise. Although acute body mass losses in response to exercise can represent a close surrogate for body water losses, the discordance between mass and water balance equivalence becomes increasingly inaccurate as more and more energy is expended. The purpose of this paper is briefly to clarify the roles that respiratory water loss, gas exchange and metabolic water production play in the correction of body mass changes for fluid balance determinations during prolonged exercise. Computations do not include waters of association with glycogen because any movement of water among body water compartments contributes nothing to water or mass flux from the body. Estimates of sweat loss from changes in body mass should adjust for non-sweat losses when possible. We propose use of the following equation as a way of simplifying the study of exercise mass and water balance: ∆body mass - 0.20 g kcal -1  = ∆body water. This equation directly controls for the influence of energy expenditure on body mass

Spatial patterns of North Atlantic Oscillation influence on mass balance variability of European glaciers

Directory of Open Access Journals (Sweden)

B. Marzeion

2012-06-01

Full Text Available We present and validate a set of minimal models of glacier mass balance variability. The most skillful model is then applied to reconstruct 7735 individual time series of mass balance variability for all glaciers in the European Alps and Scandinavia. Subsequently, we investigate the influence of atmospheric variability associated with the North Atlantic Oscillation (NAO on the glaciers' mass balances.

We find a spatial coherence in the glaciers' sensitivity to NAO forcing which is caused by regionally similar mechanisms relating the NAO forcing to the mass balance: in southwestern Scandinavia, winter precipitation causes a correlation of mass balances with the NAO. In northern Scandinavia, temperature anomalies outside the core winter season cause an anti-correlation between NAO and mass balances. In the western Alps, both temperature and winter precipitation anomalies lead to a weak anti-correlation of mass balances with the NAO, while in the eastern Alps, the influences of winter precipitation and temperature anomalies tend to cancel each other, and only on the southern side a slight anti-correlation of mass balances with the NAO prevails.

Reconstructing mass balance of Garabashi Glacier (1800–2005 using dendrochronological data

Directory of Open Access Journals (Sweden)

E. A. Dolgova

2013-01-01

Full Text Available The exploration whether tree-ring data can be effectually applied for the mass balance reconstruction in Caucasus was the main goal of this research. Tree-ring width and maximum density chronologies of pine (Pinus sylvestris L. at seven high-elevation sites in Northern Caucasus were explored for this purpose. As well as in other places of the temperate zone tree- ring width has complex climate signal controlled both temperature and precipitation. Instrumental mass balance records of Garabashi Gglacier started at 1983s. It is well known that Caucasus glaciers intensively retreat in the last decades and according to instrumental data mass balance variations are mostly controlled by the ablation, i.e. summer temperature variations. Maximum density chronology has statistically significant correlation with mass balance due to summer temperature sensitivity and great input of ablation to total mass balance variations. To include in our reconstruction different climatically sensitive parameters, stepwise multiple regression model was used. The strongest relation (r = 0.88; r2 = 0.78; p < 0.05 between two ring-width and one maximum density chronologies was identified. Cross-validation test (r = 0.79; r2 = 0.62; p < 0.05 confirmed model adequacy and it allowed to reconstruct Garabashi Glacier mass balance for 1800–2005ss. Reconstructed and instrumental mass balance values coincide well except the most recent period in 2000s, when the reconstructed mass balance slightly underestimated the real values. However even in this period it remained negative as well as the instrumental records. The bias can be explained by the weak sensitivity of the chronologies to winter precipitation (i.e. accumulation. The tree-ring based mass balance reconstruction was compared with one based on meteorological data (since 1905s. Both reconstructions have good interannual agreement (r = 0.53; p < 0.05 particularly for the period between 1975 and 2005. According to the

Modelled and observed mass balance of Rikha Samba Glacier, Nepal, Central Himalaya

Science.gov (United States)

Gurung, T. R.; Kayastha, R. B.; Fujita, K.; Sinisalo, A. K.; Stumm, D.; Joshi, S.; Litt, M.

2016-12-01

Glacier mass balance variability has an implication for the regional water resources and it helps to understand the response of glacier to climate change in the Himalayan region. Several mass balance studies have been started in the Himalayan region since 1970s, but they are characterized by frequent temporal gaps and a poor spatial representatively. This study aims at bridging the temporal gaps in a long term mass balance series of the Rikha Samba glacier (5383 - 6475 m a.s.l.), a benchmark glacier located in the Hidden Valley, Mustang, Nepal. The ERA Interim reanalysis data for the period 2011-2015 is calibrated with the observed meteorological variables from an AWS installed near the glacier terminus. We apply an energy mass balance model, validated with the available in-situ measurements for the years 1998 and 2011-2015. The results show that the glacier is shrinking at a moderate negative mass balance rate for the period 1995 to 2015 and the high altitude location of Rikha Samba also prevents a bigger mass loss compared to other small Himalayan glaciers. Precipitation from July to January and the mean air temperature from June to October are the most influential climatic parameters of the annual mass balance variability of Rikha Samba glacier.

Overview of Ice-Sheet Mass Balance and Dynamics from ICESat Measurements

Science.gov (United States)

Zwally, H. Jay

2010-01-01

The primary purpose of the ICESat mission was to determine the present-day mass balance of the Greenland and Antarctic ice sheets, identify changes that may be occurring in the surface-mass flux and ice dynamics, and estimate their contributions to global sea-level rise. Although ICESat's three lasers were planned to make continuous measurements for 3 to 5 years, the mission was re-planned to operate in 33-day campaigns 2 to 3 times each year following failure of the first laser after 36 days. Seventeen campaigns were conducted with the last one in the Fall of 2009. Mass balance maps derived from measured ice-sheet elevation changes show that the mass loss from Greenland has increased significantly to about 170 Gt/yr for 2003 to 2007 from a state of near balance in the 1990's. Increased losses (189 Gt/yr) from melting and dynamic thinning are over seven times larger'than increased gains (25 gt/yr) from precipitation. Parts of the West Antarctic ice sheet and the Antarctic Peninsula are losing mass at an increasing rate, but other parts of West Antarctica and the East Antarctic ice sheet are gaining mass at an increasing rate. Increased losses of 35 Gt/yr in Pine Island, Thwaites-Smith, and Marie-Bryd.Coast are more than balanced by gains in base of Peninsula and ice stream C, D, & E systems. From the 1992-2002 to 2003-2007 period, the overall mass balance for Antarctica changed from a loss of about 60 Gt/yr to near balance or slightly positive.

Open complex-balanced mass action chemical reaction networks

NARCIS (Netherlands)

Rao, Shodhan; van der Schaft, Arjan; Jayawardhana, Bayu

We consider open chemical reaction networks, i.e. ones with inflows and outflows. We assume that all the inflows to the network are constant and all outflows obey the mass action kinetics rate law. We define a complex-balanced open reaction network as one that admits a complex-balanced steady state.

How many stakes are required to measure the mass balance of a glacier?

Science.gov (United States)

Fountain, A.G.; Vecchia, A.

1999-01-01

Glacier mass balance is estimated for South Cascade Glacier and Maclure Glacier using a one-dimensional regression of mass balance with altitude as an alternative to the traditional approach of contouring mass balance values. One attractive feature of regression is that it can be applied to sparse data sets where contouring is not possible and can provide an objective error of the resulting estimate. Regression methods yielded mass balance values equivalent to contouring methods. The effect of the number of mass balance measurements on the final value for the glacier showed that sample sizes as small as five stakes provided reasonable estimates, although the error estimates were greater than for larger sample sizes. Different spatial patterns of measurement locations showed no appreciable influence on the final value as long as different surface altitudes were intermittently sampled over the altitude range of the glacier. Two different regression equations were examined, a quadratic, and a piecewise linear spline, and comparison of results showed little sensitivity to the type of equation. These results point to the dominant effect of the gradient of mass balance with altitude of alpine glaciers compared to transverse variations. The number of mass balance measurements required to determine the glacier balance appears to be scale invariant for small glaciers and five to ten stakes are sufficient.

Isotopic Hg in an Allende carbon-rich residue

Science.gov (United States)

Reed, G. W., Jr.; Jovanovic, S.

1990-01-01

A carbon-rich residue from Allende subjected to stepwise heating yielded two isotopically resolvable types of Hg: one with an (Hg-196)/(Hg-202) concentration ratio the same as terrestrial (monitor) Hg; the other enriched in Hg-196 relative to Hg-202 by about 60 percent. Hg with the 202 isotope enriched relative to 196, as is found in bulk Allende, was not observed. Whether the result of mass fractionation or nucleosynthesis, the distinct types of Hg entered different carrier phases and were not thermally mobilized since the accretion of the Allende parent body.

Mass balance re-analysis of Findelengletscher, Switzerland; benefits of extensive snow accumulation measurements

Directory of Open Access Journals (Sweden)

Leo eSold

2016-02-01

Full Text Available A re-analysis is presented here of a 10-year mass balance series at Findelengletscher, a temperate mountain glacier in Switzerland. Calculating glacier-wide mass balance from the set of glaciological point balance observations using conventional approaches, such as the profile or contour method, resulted in significant deviations from the reference value given by the geodetic mass change over a five-year period. This is attributed to the sparsity of observations at high elevations and to the inability of the evaluation schemes to adequately estimate accumulation in unmeasured areas. However, measurements of winter mass balance were available for large parts of the study period from snow probings and density pits. Complementary surveys by helicopter-borne ground-penetrating radar (GPR were conducted in three consecutive years. The complete set of seasonal observations was assimilated using a distributed mass balance model. This model-based extrapolation revealed a substantial mass loss at Findelengletscher of -0.43m w.e. a^-1 between 2004 and 2014, while the loss was less pronounced for its former tributary, Adlergletscher (-0.30m w.e. a^-1. For both glaciers, the resulting time series were within the uncertainty bounds of the geodetic mass change. We show that the model benefited strongly from the ability to integrate seasonal observations. If no winter mass balance measurements were available and snow cover was represented by a linear precipitation gradient, the geodetic mass balance was not matched. If winter balance measurements by snow probings and snow density pits were taken into account, the model performance was substantially improved but still showed a significant bias relative to the geodetic mass change. Thus the excellent agreement of the model-based extrapolation with the geodetic mass change was owed to an adequate representation of winter accumulation distribution by means of extensive GPR measurements.

Estimates of Ice Sheet Mass Balance from Satellite Altimetry: Past and Future

Science.gov (United States)

Zwally, H. Jay; Zukor, Dorothy J. (Technical Monitor)

2001-01-01

A major uncertainty in predicting sea level rise is the sensitivity of ice sheet mass balance to climate change, as well as the uncertainty in present mass balance. Since the annual water exchange is about 8 mm of global sea level equivalent, the 20% uncertainty in current mass balance corresponds to 1.6 mm/yr in sea level change. Furthermore, estimates of the sensitivity of the mass balance to temperature change range from perhaps as much as - 10% to + 10% per K. A principal purpose of obtaining ice sheet elevation changes from satellite altimetry has been estimation of the current ice sheet mass balance. Limited information on ice sheet elevation change and their implications about mass balance have been reported by several investigators from radar altimetry (Seasat, Geosat, ERS-1&2). Analysis of ERS-1&2 data over Greenland for 7 years from 1992 to 1999 shows mixed patterns of ice elevation increases and decreases that are significant in terms of regional-scale mass balances. Observed seasonal and interannual variations in ice surface elevation are larger than previously expected because of seasonal and interannUal variations in precipitation, melting, and firn compaction. In the accumulation zone, the variations in firn compaction are modeled as a function of temperature leaving variations in precipitation and the mass balance trend. Significant interannual variations in elevation in some locations, in particular the difference in trends from 1992 to 1995 compared to 1995 to 1999, can be explained by changes in precipitation over Greenland. Over the 7 years, trends in elevation are mostly positive at higher elevations and negative at lower elevations. In addition, trends for the winter seasons (from a trend analysis through the average winter elevations) are more positive than the corresponding trends for the summer. At lower elevations, the 7-year trends in some locations are strongly negative for summer and near zero or slightly positive for winter. These

Natural Hg isotopic composition of different Hg compounds in mammal tissues as a proxy for in vivo breakdown of toxic methylmercury.

Science.gov (United States)

Perrot, Vincent; Masbou, Jeremy; Pastukhov, Mikhail V; Epov, Vladimir N; Point, David; Bérail, Sylvain; Becker, Paul R; Sonke, Jeroen E; Amouroux, David

2016-02-01

In the last decade, specific attention has been paid to total mercury (HgT) stable isotopic composition, especially in natural samples such as aquatic organisms, due to its potential to track the cycle of this toxic element in the environment. Here, we investigated Hg Compound Specific stable Isotopic Composition (CSIC) of natural inorganic Hg (iHg) and methylmercury (MMHg) in various tissues of aquatic mammals (Beluga whale from the Arctic marine environment and seals from the freshwater lake Baikal, Russia). In seals' organs the variation in mass dependent fractionation (MDF, δ(202)Hg) for total Hg was significantly correlated to the respective fraction of iHg and MMHg compounds, with MMHg being enriched by ∼ 3‰ in heavier isotopes relative to iHg. On the other hand, we observe insignificant variation in Hg mass independent isotope fractionation (MIF, Δ(199)Hg) among iHg and MMHg in all organs for the same mammal species and MMHg in prey items. MIF signatures suggest that both MMHg and iHg in aquatic mammals have the same origin (i.e., MMHg from food), and are representative of Hg photochemistry in the water column of the mammal ecosystem. MDF signatures of Hg compounds indicate that MMHg is demethylated in vivo before being stored in the muscle, and the iHg formed is stored in the liver, and to a lesser extent in the kidney, before excretion. Thus, Hg CSIC analysis in mammals can be a powerful tool for tracing the metabolic response to Hg exposure.

An Analysis of Mass Balance of Chilean Glaciers

Science.gov (United States)

Ambinakudige, S.; Tetteh, L.

2013-12-01

Glaciers in Chile range from very small glacierets found on the isolated volcanoes of northern Chile to the 13,000 sq.km Southern Patagonian Ice Field. Regular monitoring of these glaciers is very important as they are considered as sensitive indicators of climate change. Millions of people's lives are dependent on these glaciers for fresh water and irrigation purpose. In this study, mass balances of several Chilean glaciers were estimated using Aster satellite images between 2007 and 2012. Highly accurate DEMs were created with supplementary information from IceSat data. The result indicated a negative mass balance for many glaciers indicating the need for further monitoring of glaciers in the Andes.

Isotopic Hg in an Allende carbon-rich residue

International Nuclear Information System (INIS)

Reed, G.W. Jr.; Jovanovic, S.

1990-01-01

A carbon-rich residue from Allende subjected to stepwise heating yielded two isotopically resolvable types of Hg: one with an (Hg-196)/(Hg-202) concentration ratio the same as terrestrial (monitor) Hg; the other enriched in Hg-196 relative to Hg-202 by about 60 percent. Hg with the 202 isotope enriched relative to 196, as is found in bulk Allende, was not observed. Whether the result of mass fractionation or nucleosynthesis, the distinct types of Hg entered different carrier phases and were not thermally mobilized since the accretion of the Allende parent body. 9 refs

Mass Equivalent Pantographs for Synthesis of Balanced Focal Mechanisms

NARCIS (Netherlands)

van der Wijk, V.; Lenarcic, Jadran; Merlet, Jean-Pierre

2016-01-01

Force balance is an important property in the design of high-speed high precision machinery to reduce base vibrations and also for the design of inherently safe large movable structures. This paper presents the synthesis of inherently balanced overconstrained focal mechanisms with mass equivalent

A Reconciled Estimate of Ice-Sheet Mass Balance

Science.gov (United States)

Shepherd, Andrew; Ivins, Erik R.; Geruo, A.; Barletta, Valentia R.; Bentley, Mike J.; Bettadpur, Srinivas; Briggs, Kate H.; Bromwich, David H.; Forsberg, Rene; Galin, Natalia;

Remote Sensing Estimates of Glacier Mass Balance Changes in the Himalayas of Nepal

Science.gov (United States)

Ambinakudige, S.; Joshi, K.

2011-12-01

Mass balance changes of glaciers are important indicators of climate change. There are only 30 'reference' glaciers in the world that have continuous mass balance data with world glacier monitoring service since 1976. Especially, Himalayan glaciers are conspicuously absent from global mass balance records. This shows the urgent need for mass balance data for glaciers throughout the world. In this study, we estimated mass balance of some major glaciers in the Sagarmatha National Park (SNP) in Nepal using remote sensing applications. The SNP is one of the densest glaciated regions in the Himalayan range consisting approximately 296 glacial lakes. The region has experienced several glacial lake outburst floods (GLOFs) in recent years, causing extensive damage to local infrastructure and loss of human life. In general, mass balance is determined at seasonal or yearly intervals. Because of the rugged and difficult terrain of the Himalayan region, there are only a few field based measurements of mass balance available. Moreover, there are only few cases where the applications of remote sensing methods were used to calculate mass balance of the Himalayan glaciers due to the lack of accurate elevation data. Studies have shown that estimations of mass balance using remote sensing applications were within the range of field-based mass balance measurements from the same period. This study used ASTER VNIR, 3N (nadir view) and 3B (backward view) bands to generate Digital Elevation Models (DEMs) for the SNP area. 3N and 3B bands generate an along track stereo pair with a base-to-height (B/H) ratio of about 0.6. Accurate measurement of ground control points (GCPs), their numbers and distribution are important inputs in creating accurate DEMs. Because of the availability of topographic maps for this area, we were able to provide very accurate GCPs, in sufficient numbers and distribution. We created DEMs for the years 2002, 2003, 2004 and 2005 using ENVI DEM extraction tool. Bands

Mass balance of the Amitsulôq ice cap, West Greenland

DEFF Research Database (Denmark)

Ahlstrøm, Andreas P.; Bøggild, Carl Egede; Olesen, Ole B.

2007-01-01

We present detailed mass balance measurements from the Amitsulôq ice cap in West Greenland spanning from 1982 to 1990. The data includes summer and winter balances from 26 stake locations distributed over five transects covering the whole ice cap. The mass balance measurements are combined...... with a recent satellite-derived digital elevation model to calculate the specific balance, which is in turn compared to discharge data from the adjacent Tasersiaq basin. The correlation between specific summer balance and discharge is R2 = 0.93 indicating that the basin discharge is dominated by glacial...... meltwater, linking the hydropower potential of the basin closely to the fate of the adjoining Greenland ice-sheet margin....

Basin-scale partitioning of Greenland ice sheet mass balance components (2007-2011)

DEFF Research Database (Denmark)

Andersen, M.L.; Stenseng, Lars; Skourup, Henriette

2015-01-01

The current deficit in Greenland ice sheet mass balance is due to both a decrease in surface mass balance (SMB) input and an increase in ice discharge (D) output. While SMB processes are beginning to be well captured by observationally-constrained climate modeling, insight into D is relatively...... of the gate. Using a 1961-1990 reference climatology SMB field from the MAR regional climate model, we quantify ice sheet mass balance within eighteen basins. We find a 2007-2011 mean D of 515±57 Gtyr-1. We find a 2007-2011 mean total mass balance of -262±21 Gtyr-1, which is equal to a 0.73 mm yr-1 global sea...... limited. We use InSAR-derived velocities, in combination with ice thickness observations, to quantify the mass flux (F) across a flux perimeter around the ice sheet at ~1700 m elevation. To quantify D, we correct F for SMB, as well as changes in volume due to ice dynamics, in the area downstream...

Calibrating a surface mass-balance model for Austfonna ice cap, Svalbard

Science.gov (United States)

Schuler, Thomas Vikhamar; Loe, Even; Taurisano, Andrea; Eiken, Trond; Hagen, Jon Ove; Kohler, Jack

2007-10-01

Austfonna (8120 km2) is by far the largest ice mass in the Svalbard archipelago. There is considerable uncertainty about its current state of balance and its possible response to climate change. Over the 2004/05 period, we collected continuous meteorological data series from the ice cap, performed mass-balance measurements using a network of stakes distributed across the ice cap and mapped the distribution of snow accumulation using ground-penetrating radar along several profile lines. These data are used to drive and test a model of the surface mass balance. The spatial accumulation pattern was derived from the snow depth profiles using regression techniques, and ablation was calculated using a temperature-index approach. Model parameters were calibrated using the available field data. Parameter calibration was complicated by the fact that different parameter combinations yield equally acceptable matches to the stake data while the resulting calculated net mass balance differs considerably. Testing model results against multiple criteria is an efficient method to cope with non-uniqueness. In doing so, a range of different data and observations was compared to several different aspects of the model results. We find a systematic underestimation of net balance for parameter combinations that predict observed ice ablation, which suggests that refreezing processes play an important role. To represent these effects in the model, a simple PMAX approach was included in its formulation. Used as a diagnostic tool, the model suggests that the surface mass balance for the period 29 April 2004 to 23 April 2005 was negative (-318 mm w.e.).

Geodetic reanalysis of annual glaciological mass balances (2001-2011) of Hintereisferner, Austria

Science.gov (United States)

Klug, Christoph; Bollmann, Erik; Galos, Stephan Peter; Nicholson, Lindsey; Prinz, Rainer; Rieg, Lorenzo; Sailer, Rudolf; Stötter, Johann; Kaser, Georg

2018-03-01

This study presents a reanalysis of the glaciologically obtained annual glacier mass balances at Hintereisferner, Ötztal Alps, Austria, for the period 2001-2011. The reanalysis is accomplished through a comparison with geodetically derived mass changes, using annual high-resolution airborne laser scanning (ALS). The grid-based adjustments for the method-inherent differences are discussed along with associated uncertainties and discrepancies of the two methods of mass balance measurements. A statistical comparison of the two datasets shows no significant difference for seven annual, as well as the cumulative, mass changes over the 10-year record. Yet, the statistical view hides significant differences in the mass balance years 2002/03 (glaciological minus geodetic records = +0.92 m w.e.), 2005/06 (+0.60 m w.e.), and 2006/07 (-0.45 m w.e.). We conclude that exceptional meteorological conditions can render the usual glaciological observational network inadequate. Furthermore, we consider that ALS data reliably reproduce the annual mass balance and can be seen as validation or calibration tools for the glaciological method.

Ice-sheet mass balance and climate change.

Science.gov (United States)

Hanna, Edward; Navarro, Francisco J; Pattyn, Frank; Domingues, Catia M; Fettweis, Xavier; Ivins, Erik R; Nicholls, Robert J; Ritz, Catherine; Smith, Ben; Tulaczyk, Slawek; Whitehouse, Pippa L; Zwally, H Jay

2013-06-06

Since the 2007 Intergovernmental Panel on Climate Change Fourth Assessment Report, new observations of ice-sheet mass balance and improved computer simulations of ice-sheet response to continuing climate change have been published. Whereas Greenland is losing ice mass at an increasing pace, current Antarctic ice loss is likely to be less than some recently published estimates. It remains unclear whether East Antarctica has been gaining or losing ice mass over the past 20 years, and uncertainties in ice-mass change for West Antarctica and the Antarctic Peninsula remain large. We discuss the past six years of progress and examine the key problems that remain.

Comparative glacio-climatological analysis of mass balance variability along the geographical margin of Europe

Science.gov (United States)

Lehoczky, Annamária; Kern, Zoltán; Pongrácz, Rita

2014-05-01

Glacio-climatological studies recognise glacier mass balance changes as high-confident climate indicators. The climatic sensitivity of a glacier does not simply depend on regional climate variability but also influenced via large- and mesoscale atmospheric circulation patterns. This study focuses on recent changes in the mass balance using records from three border regions of Europe, and investigates the relationships between the seasonal mass balance components, regional climatic conditions, and distant atmospheric forcing. Since glaciers in different macro-climatological conditions (i.e., mid-latitudes or high-latitudes, dry-continental or maritime regions) may present strongly diverse mass balance characteristics, the three analysed regions were selected from different glacierised macroregions (using the database of the World Glacier Monitoring Service). These regions belong to the Caucasus Mountains (Central Europe macroregion), the Polar Ural (Northern Asia macroregion), and Svalbard (Arctic Islands macroregion). The analysis focuses on winter, summer, and annual mass balance series of eight glaciers. The climatic variables (atmospheric pressure, air temperature, precipitation) and indices of teleconnection patterns (e.g., North Atlantic Oscillation, Pacific Decadal Oscillation) are used from the gridded databases of the University of East Anglia, Climatic Research Unit and the National Oceanic and Atmospheric Administration, National Center for Environmental Prediction. However, the period and length of available mass balance data in the selected regions vary greatly (the first full record is in 1958, Polar Ural; the last is in 2010, Caucasus Mountains), a comparative analysis can be carried out for the period of 1968-1981. Since glaciers from different regions respond to large- and mesoscale climatic forcings differently, and because the mass balance of glaciers within a region often co-vary, our specific objectives are (i) to examine the variability and the

Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history.

Science.gov (United States)

Kim, Jihun; Lim, Dhongil; Jung, Dohyun; Kang, Jeongwon; Jung, Hoisoo; Woo, Hanjun; Jeong, Kapsik; Xu, Zhaokai

2018-03-01

We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10 -5  g/m 2 /yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hg uptake in ureteral obstructions

International Nuclear Information System (INIS)

Desgrez, J.P.; Bourguignon, M.; Raynaud, C.; CEA, 91 - Orsay

1976-01-01

In the presence of a total obstruction the results obtained with the Hg uptake test, as indeed with other functional tests, inform on the value of the kidney function at the time but have no prognostic value where repair possibilities are concerned. Some preliminary results seem to show however that very soon after the obstacle is removed, by the 10th or 15th day perhaps, quantitative functional tests may once more be used to evaluate the functional prognosis. This would mean that by waiting about two weeks after the disappearance of a total obstruction the Hg uptake test may again be used in all confidence. In order to check this deduction, which is based on slender evidence but which nevertheless has important practical implications, the measurement of the Hg uptake rate during the days following removal of the obstacle appears essential. In long-standing partial obstructions the Hg uptake rate gives an accurate assessment of the functional balance and helps considerably in the choice of therapy [fr

Comparison of direct and geodetic mass balances on a multi-annual time scale

Directory of Open Access Journals (Sweden)

A. Fischer

2011-02-01

Full Text Available The geodetic mass balances of six Austrian glaciers over 19 periods between 1953 and 2006 are compared to the direct mass balances over the same periods. For two glaciers, Hintereisferner and Kesselwandferner, case studies showing possible reasons for discrepancies between the geodetic and the direct mass balance are presented. The mean annual geodetic mass balance for all periods is −0.5 m w.e. a⁻¹, the mean annual direct mass balance −0.4 m w.e. a⁻¹. The mean cumulative difference is −0.6 m w.e., the minimum −7.3 m w.e., and the maximum 5.6 m w.e. The accuracy of geodetic mass balance may depend on the accuracy of the DEMs, which ranges from 2 m w.e. for photogrammetric data to 0.02 m w.e. for airborne laser scanning (LiDAR data. Basal melt, seasonal snow cover, and density changes of the surface layer also contribute up to 0.7 m w.e. to the difference between the two methods over the investigated period of 10 yr. On Hintereisferner, the fraction of area covered by snow or firn has been changing within 1953–2006. The accumulation area is not identical with the firn area, and both are not coincident with areas of volume gain. Longer periods between the acquisition of the DEMs do not necessarily result in a higher accuracy of the geodetic mass balance. Trends in the difference between the direct and the geodetic data vary from glacier to glacier and can differ systematically for specific glaciers under specific types of climate forcing. Ultimately, geodetic and direct mass balance data are complementary, and great care must be taken when attempting to combine them.

Midlatitude Forcing Mechanisms for Glacier Mass Balance Investigated Using General Circulation Models

NARCIS (Netherlands)

Reichert, B.K.; Bengtsson, L.; Oerlemans, J.

2001-01-01

A process-oriented modeling approach is applied in order to simulate glacier mass balance for individual glaciers using statistically downscaled general circulation models (GCMs). Glacier-specific seasonal sensitivity characteristics based on a mass balance model of intermediate complexity are used

Surface Mass Balance Contributions to Acceleration of Antarctic Ice Mass Loss during 2003- 2013

Science.gov (United States)

Seo, K. W.; Wilson, C. R.; Scambos, T. A.; Kim, B. M.; Waliser, D. E.; Tian, B.; Kim, B.; Eom, J.

2015-12-01

Recent observations from satellite gravimetry (the GRACE mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE-derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by precipitation anomalies. However, on the Antarctic Peninsula and other parts of West Antarctica mass changes are not explained by precipitation and are likely associated with ice discharge rate increases. The total apparent GRACE acceleration over all of the AIS between 2003 and 2013 is -13.6±7.2 GTon/yr2. Of this total, we find that the surface mass balance component is -8.2±2.0 GTon/yr2. However, the GRACE estimate appears to contain errors arising from the atmospheric pressure fields used to remove air mass effects. The estimated acceleration error from this effect is about 9.8±5.8 GTon/yr2. Correcting for this yields an ice discharge acceleration of -15.1±6.5 GTon/yr2.

Comparison of Various Dynamic Balancing Principles Regarding Additional Mass and Additional Inertia

NARCIS (Netherlands)

van der Wijk, V.; Demeulenaere, Bram; Herder, Justus Laurens

2009-01-01

The major disadvantage of existing dynamic balancing principles is that a considerable amount of mass and inertia is added to the system. The objectives of this article are to summarize, to compare, and to evaluate existing complete balancing principles regarding the addition of mass and the

Electrothermal vaporization inductively coupled plasma-mass spectrometry for the determination of Cr, Cu, Cd, Hg and Pb in rice flour

International Nuclear Information System (INIS)

Li, P.-C.; Jiang, S.-J.

2003-01-01

Ultrasonic slurry sampling (USS)-electrothermal vaporization (ETV) dynamic reaction cell TM (DRC) inductively coupled plasma-mass spectrometry (ICP-MS) has been applied to determine Cr, Cu, Cd, Hg and Pb in rice samples. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. Ascorbic acid was used as a modifier to enhance the ion signals. The background ions at the chromium masses were reduced in intensity significantly by using 0.4 ml min -1 NH 3 as reaction cell gas in the dynamic reaction cell while a q value of 0.6 was used. Since the sensitivities of Cr, Cu, Cd, Hg and Pb in rice flour slurry and aqueous solution were quite different, standard addition and isotope dilution methods were used for the determination of Cr, Cu, Cd, Hg and Pb in these rice samples. This method has been applied to the determination of Cr, Cu, Cd, Hg and Pb in NIST SRM 1568a rice flour reference material and two rice samples purchased from the market. The analytical results for the reference material agreed with the certified values. The results for the rice samples for which no reference values were available were also found to be in good agreement between the isotope dilution and standard addition methods. The method's detection limits estimated from the standard addition plots were about 0.44, 1.7, 0.4, 0.53 and 0.69 ng g -1 for Cr, Cu, Cd, Hg and Pb, respectively, in the original rice flour

Surface mass balance contributions to acceleration of Antarctic ice mass loss during 2003-2013

OpenAIRE

Seo, Ki-Weon; Wilson, Clark R.; Scambos, Ted; Kim, Baek-Min; Waliser, Duane E.; Tian, Baijun; Kim, Byeong-Hoon; Eom, Jooyoung

2015-01-01

Abstract Recent observations from satellite gravimetry (the Gravity Recovery and Climate Experiment (GRACE) mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE?derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by ...

Land motion due to 20th century mass balance of the Greenland Ice Sheet

Science.gov (United States)

Kjeldsen, K. K.; Khan, S. A.

2017-12-01

Quantifying the contribution from ice sheets and glaciers to past sea level change is of great value for understanding sea level projections into the 21st century. However, quantifying and understanding past changes are equally important, in particular understanding the impact in the near-field where the signal is highest. We assess the impact of 20th century mass balance of the Greenland Ice Sheet on land motion using results from Kjeldsen et al, 2015. These results suggest that the ice sheet on average lost a minimum of 75 Gt/yr, but also show that the mass balance was highly spatial- and temporal variable, and moreover that on a centennial time scale changes were driven by a decreasing surface mass balance. Based on preliminary results we discuss land motion during the 20th century due to mass balance changes and the driving components surface mass balance and ice dynamics.

Comparative analysis for low-mass and low-inertia dynamic balancing of mechanisms

NARCIS (Netherlands)

van der Wijk, V.; Demeulenaere, B.; Gosselin, C.M.; Herder, Justus Laurens

2012-01-01

Dynamic balance is an important feature of high speed mechanisms and robotics that need to minimize vibrations of the base. The main disadvantage of dynamic balancing, however, is that it is accompanied with a considerable increase in mass and inertia. Aiming at low-mass and low-inertia dynamic

Understanding the Role of Wind in Reducing the Surface Mass Balance Estimates over East Antarctica

Science.gov (United States)

Das, I.; Scambos, T. A.; Koenig, L.; Creyts, T. T.; Bell, R. E.; van den Broeke, M. R.; Lenaerts, J.; Paden, J. D.

2014-12-01

Accurate quantification of surface snow-accumulation over Antarctica is important for mass balance estimates and climate studies based on ice core records. An improved estimate of surface mass balance must include the significant role near-surface wind plays in the sublimation and redistribution of snow across Antarctica. We have developed an empirical model based on airborne radar and lidar observations, and modeled surface mass balance and wind fields to produce a continent-wide prediction of wind-scour zones over Antarctica. These zones have zero to negative surface mass balance, are located over locally steep ice sheet areas (>0.002) and controlled by bedrock topography. The near-surface winds accelerate over these zones, eroding and sublimating the surface snow. This scouring results in numerous localized regions (≤ 200 km2) with reduced surface accumulation. Each year, tens of gigatons of snow on the Antarctic ice sheet are ablated by persistent near-surface katabatic winds over these wind-scour zones. Large uncertainties remain in the surface mass balance estimates over East Antarctica as climate models do not adequately represent the small-scale physical processes that lead to mass loss through sublimation or redistribution over the wind-scour zones. In this study, we integrate Operation IceBridge's snow radar over the Recovery Ice Stream with a series of ice core dielectric and depth-density profiles for improved surface mass balance estimates that reflect the mass loss over the wind-scour zones. Accurate surface mass balance estimates from snow radars require spatially variable depth-density profiles. Using an ensemble of firn cores, MODIS-derived surface snow grain size, modeled accumulation rates and surface temperatures from RACMO2, we assemble spatially variable depth-density profiles and use our mapping of snow density variations to estimate layer mass and net accumulation rates from snow radar layer data. Our study improves the quantification of

Mass balance of the Greenland ice sheet (2003-2008) from ICESat data

DEFF Research Database (Denmark)

Sørensen, Louise Sandberg; Simonsen, Sebastian Bjerregaard; Nielsen, Karina

2011-01-01

ICESat has provided surface elevation measurements of the ice sheets since the launch in January 2003, resulting in a unique dataset for monitoring the changes of the cryosphere. Here, we present a novel method for determining the mass balance of the Greenland ice sheet, derived from ICESat...... studies of the Greenland ice sheet mass balance, based on different remote-sensing techniques....... altimetry data. Three different methods for deriving elevation changes from the ICESat altimetry dataset are used. This multi-method approach provides a method to assess the complexity of deriving elevation changes from this dataset. The altimetry alone can not provide an estimate of the mass balance...

The mass balance of a Proton Exchange Membrane Fuel Cell (PEMFC)

International Nuclear Information System (INIS)

Miloud, S.; Kamaruzzaman Sopian; Wan Ramli Wan Daud

2006-01-01

A Proton Exchange Membrane Fuel Cell (PEMFC), operating at low temperature uses a simple chemical process to combine hydrogen and oxygen into water, producing electric current and heat during the electrochemical reaction. This work concern on the theoretical consideration of the mass balance has been evaluated to predict the mass flow rate of the both gases (hydrogen/oxygen), the water mass balance, and the heat transfer in order to design a single cell PEMFC stack with a better flow field distributor on the performance of Polymer Electrolyte membrane fuel cells

Effect of body mass index and fat mass on balance force platform measurements during a one-legged stance in older adults.

Science.gov (United States)

Pereira, Camila; Silva, Rubens A da; de Oliveira, Marcio R; Souza, Rejane D N; Borges, Renata J; Vieira, Edgar R

2018-05-01

The purpose of this study was to evaluate the impact of body mass index (BMI) and fat mass on balance force platform measurements in older adults. The sample consisted of 257 participants who were stratified into four groups by BMI: low weight, normal weight, pre-obesity and obesity. For fat mass variables, older individuals were classified into low and high-fat mass. All groups investigated performed three trials of one-legged stance balance on a force platform. Center of pressure (COP) domain parameters were computed from the mean across trials. Analysis of variance results revealed no significant interactions for groups and sexes for all COP parameters. Comparable balance results were found for BMI and fat groups for all COP parameters. A statistical effect (P < 0.05) was only reported for sex differences for COP parameters, regardless of BMI and fat mass variables. Overall, women presented better balance than men. In conclusion, BMI and fat mass do not seem to influence the balance of older adults during a one-leg stance task.

Determination of Interannual to Decadal Changes in Ice Sheet Mass Balance from Satellite Altimetry

Science.gov (United States)

Zwally, H. Jay; Busalacchi, Antonioa J. (Technical Monitor)

2001-01-01

A major uncertainty in predicting sea level rise is the sensitivity of ice sheet mass balance to climate change, as well as the uncertainty in present mass balance. Since the annual water exchange is about 8 mm of global sea level equivalent, the +/- 25% uncertainty in current mass balance corresponds to +/- 2 mm/yr in sea level change. Furthermore, estimates of the sensitivity of the mass balance to temperature change range from perhaps as much as - 10% to + 10% per K. Although the overall ice mass balance and seasonal and inter-annual variations can be derived from time-series of ice surface elevations from satellite altimetry, satellite radar altimeters have been limited in spatial coverage and elevation accuracy. Nevertheless, new data analysis shows mixed patterns of ice elevation increases and decreases that are significant in terms of regional-scale mass balances. In addition, observed seasonal and interannual variations in elevation demonstrate the potential for relating the variability in mass balance to changes in precipitation, temperature, and melting. From 2001, NASA's ICESat laser altimeter mission will provide significantly better elevation accuracy and spatial coverage to 86 deg latitude and to the margins of the ice sheets. During 3 to 5 years of ICESat-1 operation, an estimate of the overall ice sheet mass balance and sea level contribution will be obtained. The importance of continued ice monitoring after the first ICESat is illustrated by the variability in the area of Greenland surface melt observed over 17-years and its correlation with temperature. In addition, measurement of ice sheet changes, along with measurements of sea level change by a series of ocean altimeters, should enable direct detection of ice level and global sea level correlations.

Inter-comparison of ice sheet mass balance products from GRACE: ESA CCI Round Robin results

DEFF Research Database (Denmark)

Groth, A.; Horwath, M.; Horvath, A.

-term satellite-based data products are generated for selected ECVs. Since ice sheet mass balance is an ECV parameter of highest interest, both the AIS_cci and the GIS_cci project will provide mass balance products based on satellite gravimetry data: (a) time series of monthly mass changes for individual drainage...... basins, and (b) gridded mass changes covering the entire ice sheet.Gravimetry Mass Balance (GMB) products are derived from data acquired by the GRACE (Gravity Recovery and Climate Experiment) mission. Although GRACE data have the advantage of being directly sensitive to mass changes, their limited...... drainage basins the GMB time series are compared to independent mass balance products based on satellite altimetry and firn densification information from a regional climate model. This inter-comparison has aided the algorithm definition for the operational ECV production....

Greenland ice sheet mass balance: a review

DEFF Research Database (Denmark)

Khan, Shfaqat Abbas; Aschwanden, Andy; Bjørk, Anders A.

2015-01-01

Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance...

Performance of the Fuel Conditioning Facility electronic in-cell mass balances

International Nuclear Information System (INIS)

Orechwa, Y.; Bucher, R.G.

1996-01-01

An approach to error estimation and measurement control in the analysis of the balance measurements of mass standards on the in-cell electronic mass balances of the Fuel Conditioning Facility is presented. In light of measurement data from one year of operation, the algorithms proposed are evaluated. The need to take into account the effects of facility operations on the estimates of measurement uncertainty is demonstrated. In the case of a newly installed balance, where no historical data exists, an ad hoc procedure of adding a term which takes into account the operational variability is proposed. This procedure allows a sufficiently long operation so as to collect data for the estimate of the contribution of operational effects to the uncertainty estimate. An algorithm for systematically taking into account historical data is developed and demonstrated for two balances over two calibration periods. The algorithm, both asymptotically and in the two samples cases, has the necessary desirable properties for estimating the uncertainty in the measurements of the balances

A MASS BALANCE OF SURFACE WATER GENOTOXICITY IN PROVIDENCE RIVER (RHODE ISLAND USA)

Science.gov (United States)

White and Rasmussen (Mutation Res. 410:223-236) used a mass balance approach to demonstrate that over 85% of the total genotoxic loading to the St. Lawrence River at Montreal is non-industrial. To validate the mass balance approach and investigate the sources of genotoxins in sur...

Diagnosing the decline in climatic mass balance of glaciers in Svalbard over 1957-2014

Science.gov (United States)

Ims Østby, Torbjørn; Vikhamar Schuler, Thomas; Ove Hagen, Jon; Hock, Regine; Kohler, Jack; Reijmer, Carleen H.

2017-01-01

Estimating the long-term mass balance of the high-Arctic Svalbard archipelago is difficult due to the incomplete geodetic and direct glaciological measurements, both in space and time. To close these gaps, we use a coupled surface energy balance and snow pack model to analyse the mass changes of all Svalbard glaciers for the period 1957-2014. The model is forced by ERA-40 and ERA-Interim reanalysis data, downscaled to 1 km resolution. The model is validated using snow/firn temperature and density measurements, mass balance from stakes and ice cores, meteorological measurements, snow depths from radar profiles and remotely sensed surface albedo and skin temperatures. Overall model performance is good, but it varies regionally. Over the entire period the model yields a climatic mass balance of 8.2 cm w. e. yr-1, which corresponds to a mass input of 175 Gt. Climatic mass balance has a linear trend of -1.4 ± 0.4 cm w. e. yr-2 with a shift from a positive to a negative regime around 1980. Modelled mass balance exhibits large interannual variability, which is controlled by summer temperatures and further amplified by the albedo feedback. For the recent period 2004-2013 climatic mass balance was -21 cm w. e. yr-1, and accounting for frontal ablation estimated by Błaszczyk et al.(2009) yields a total Svalbard mass balance of -39 cm w. e. yr-1 for this 10-year period. In terms of eustatic sea level, this corresponds to a rise of 0.037 mm yr-1. Refreezing of water in snow and firn is substantial at 22 cm w. e. yr-1 or 26 % of total annual accumulation. However, as warming leads to reduced firn area over the period, refreezing decreases both absolutely and relative to the total accumulation. Negative mass balance and elevated equilibrium line altitudes (ELAs) resulted in massive reduction of the thick (> 2 m) firn extent and an increase in the superimposed ice, thin (ice extents. Atmospheric warming also leads to a marked change in the thermal regime, with cooling of the

Exploring uncertainty in glacier mass balance modelling with Monte Carlo simulation

NARCIS (Netherlands)

Machguth, H.; Purves, R.S.; Oerlemans, J.; Hoelzle, M.; Paul, F.

2008-01-01

By means of Monte Carlo simulations we calculated uncertainty in modelled cumulative mass balance over 400 days at one particular point on the tongue of Morteratsch Glacier, Switzerland, using a glacier energy balance model of intermediate complexity. Before uncertainty assessment, the model was

Assessment of Hg Pollution Released from a WWII Submarine Wreck (U-864) by Hg Isotopic Analysis of Sediments and Cancer pagurus Tissues.

Science.gov (United States)

Rua-Ibarz, Ana; Bolea-Fernandez, Eduardo; Maage, Amund; Frantzen, Sylvia; Valdersnes, Stig; Vanhaecke, Frank

2016-10-04

Hg pollution released from the U-864 submarine sunk during WWII and potential introduction of that Hg into the marine food chain have been studied by a combination of quantitative Hg and MeHg determination and Hg isotopic analysis via cold vapor generation multicollector inductively coupled plasma-mass spectrometry (CVG-MC-ICP-MS) in sediment and Cancer pagurus samples. The sediment pollution could be unequivocally linked with the metallic Hg present in the wreck. Crabs were collected at the wreck location and 4 nmi north and south, and their brown and claw meat were analyzed separately. For brown meat, the δ 202 Hg values of the individuals from the wreck location were shifted toward the isotopic signature of the sediment and, thus, the submarine Hg. Such differences were not found for claw meat. The isotope ratio results suggest direct ingestion of metallic Hg by C. pagurus but do not offer any proof for any other introduction of the submarine Hg into the marine food chain.

Autonomous Ice Mass Balance Buoys for Seasonal Sea Ice

Science.gov (United States)

Whitlock, J. D.; Planck, C.; Perovich, D. K.; Parno, J. T.; Elder, B. C.; Richter-Menge, J.; Polashenski, C. M.

2017-12-01

The ice mass-balance represents the integration of all surface and ocean heat fluxes and attributing the impact of these forcing fluxes on the ice cover can be accomplished by increasing temporal and spatial measurements. Mass balance information can be used to understand the ongoing changes in the Arctic sea ice cover and to improve predictions of future ice conditions. Thinner seasonal ice in the Arctic necessitates the deployment of Autonomous Ice Mass Balance buoys (IMB's) capable of long-term, in situ data collection in both ice and open ocean. Seasonal IMB's (SIMB's) are free floating IMB's that allow data collection in thick ice, thin ice, during times of transition, and even open water. The newest generation of SIMB aims to increase the number of reliable IMB's in the Arctic by leveraging inexpensive commercial-grade instrumentation when combined with specially developed monitoring hardware. Monitoring tasks are handled by a custom, expandable data logger that provides low-cost flexibility for integrating a large range of instrumentation. The SIMB features ultrasonic sensors for direct measurement of both snow depth and ice thickness and a digital temperature chain (DTC) for temperature measurements every 2cm through both snow and ice. Air temperature and pressure, along with GPS data complete the Arctic picture. Additionally, the new SIMB is more compact to maximize deployment opportunities from multiple types of platforms.

Representativeness of regional and global mass-balance measurement networks (Invited)

Science.gov (United States)

Cogley, J. G.; Moholdt, G.; Gardner, A. S.

2013-12-01

We showed in a recent publication that regional estimates of glacier mass budgets, obtained by interpolation from in-situ measurements, were markedly more negative than corresponding estimates by satellite gravimetry (GRACE) and satellite altimetry (ICESat) during 2003-2009. Examining the ICESat data in more detail, we found that in-situ records tend to be located in areas where glaciers are thinning more rapidly than as observed in their regional surroundings. Because neither GRACE nor ICESat can provide information for times before 2002-2003, and may not operate without interruption in the future, we explore possible explanations of and remedies for the identified bias in the in-situ network. Sparse spatial sampling, coupled with previously undetected spatial variability of mass balance at scales between the 10-km in-situ scale and the 350-km gravimetric scale, appears to be the leading explanation. Satisfactory remedies are not obvious. Selecting glaciers for in-situ measurement that are more representative will yield only incremental improvements. There appears to be no alternative to mass-balance modelling as a versatile tool for estimation of regional mass balance. However the meteorological data for forcing the surface components of glacier models have coarser resolution than is desirable and are themselves uncertain, especially in the remote regions where much of the glacier ice is found. Measurements of frontal (dynamic) mass changes are still difficult, and modelling of these changes remains underdeveloped in spite of recent advances. Thus research on a broad scale is called for in order to meet the challenge of producing more accurate hindcasts and projections of glacier mass budgets with fine spatial and temporal resolution.

Opportunities and Challenges in Enhancing Value of Annual Glacier Mass Balance Monitoring Examples from Western North America

Science.gov (United States)

Pelto, M. S.

2017-12-01

Alpine glacier mass balance is the most accurate indicator of glacier response to climate and with retreat of alpine glaciers is one of the clearest signals of global climate change. Completion of long term, representative and homogenous mass balance field measurement of mass balance, compiled by WGMS, is a key climate data record. To ensure a monitoring program remains vital and funded local collaboration and connecting the research to local societal impacts is crucial. Working with local partners in collecting and providing the right data is critical whether their interest is in hydropower, irrigation, municipal supply, hazard reduction and/or aquatic ecosystems. The expansion of remote sensing and modeling capability provides both a challenge to continued relevance and an opportunity for field mass balance programs to expand relevance. In modelling studies of both glacier mass balance and glacier runoff transient balance data has equivalent value with annual balance data, for both calibration runs and as an input variable. This increases the utility of mid-season field observations. Remote sensing provides repeat imagery that often identifies the AAR and transient snowline of a glacier. For runoff assessment understanding the specific percent of glacier surface area that is glacier ice, older firn, and retained snowpack from the previous winter at frequent intervals during the melt season is vital since each region has a different melt factor. A denser field observation network combined with this imagery can provide additional point balance values of ablation that complement the mass balance record. Periodic measurement of mass balance at a denser network using GPR, LIDAR, TLS or probing is required to better understand long term point balance locations and is important at end of the melt season not just beginning, and has value mid-season for modelling. Applications of each of utility of field mass balance observations will be illustrated.

Gulkana Glacier, Alaska-Mass balance, meteorology, and water measurements, 1997-2001

Science.gov (United States)

March, Rod S.; O'Neel, Shad

2011-01-01

The measured winter snow, maximum winter snow, net, and annual balances for 1997-2001 in the Gulkana Glacier basin are determined at specific points and over the entire glacier area using the meteorological, hydrological, and glaciological data. We provide descriptions of glacier geometry to aid in estimation of conventional and reference surface mass balances and descriptions of ice motion to aid in the understanding of the glacier's response to its changing geometry. These data provide annual estimates for area altitude distribution, equilibrium line altitude, and accumulation area ratio during the study interval. New determinations of historical area altitude distributions are given for 1900 and annually from 1966 to 2001. As original weather instrumentation is nearing the end of its deployment lifespan, we provide new estimates of overlap comparisons and precipitation catch efficiency. During 1997-2001, Gulkana Glacier showed a continued and accelerated negative mass balance trend, especially below the equilibrium line altitude where thinning was pronounced. Ice motion also slowed, which combined with the negative mass balance, resulted in glacier retreat under a warming climate. Average annual runoff augmentation by glacier shrinkage for 1997-2001 was 25 percent compared to the previous average of 13 percent, in accordance with the measured glacier volume reductions.

Antarctic and Greenland ice sheet mass balance products from satellite gravimetry

Science.gov (United States)

Horwath, Martin; Groh, Andreas; Horvath, Alexander; Forsberg, René; Meister, Rakia; Barletta, Valentina R.; Shepherd, Andrew

2017-04-01

Because of their important role in the Earth's climate system, ESA's Climate Change Initiative (CCI) has identified both the Antarctic Ice Sheet (AIS) and the Greenland Ice Sheet (GIS) as Essential Climate Variables (ECV). Since respondents of a user survey indicated that the ice sheet mass balance is one of the most important ECV data products needed to better understand climate change, the AIS_cci and the GIS_cci project provide Gravimetric Mass Balance (GMB) products based on satellite gravimetry data. The GMB products are derived from GRACE (Gravity Recovery and Climate Experiment) monthly solutions of release ITSG-Grace2016 produced at TU Graz. GMB basin products (i.e. time series of monthly mass changes for the entire ice sheets and selected drainage basins) and GMB gridded products (e.g. mass balance estimates with a formal resolution of about 50km, covering the entire ice sheets) are generated for the period from 2002 until present. The first GMB product was released in mid 2016. Here we present an extended and updated version of the ESA CCI GMB products, which are freely available through data portals hosted by the projects (https://data1.geo.tu-dresden.de/ais_gmb, http://products.esa-icesheets-cci.org/products/downloadlist/GMB). Since the initial product release, the applied processing strategies have been improved in order to further reduce GRACE errors and to enhance the separation of signals super-imposed to the ice mass changes. While a regional integration approach is used by the AIS_cci project, the GMB products of the GIS_cci project are derived using a point mass inversion. The differences between both approaches are investigated through the example of the GIS, where an alternative GMB product was generated using the regional integration approach implemented by the AIS_cci. Finally, we present the latest mass balance estimates for both ice sheets as well as their corresponding contributions to global sea level rise.

Development of pre-concentration procedure for the determination of Hg isotope ratios in seawater samples

International Nuclear Information System (INIS)

Štrok, Marko; Hintelmann, Holger; Dimock, Brian

2014-01-01

Highlights: • The method for the quantitative pre-concentration of Hg from seawater was developed. • First report of Hg isotope ratios in seawater is presented. • A unique mass independent 200 Hg isotope fractionation was observed. • This fractionation has unique potential to distinguish anthropogenic and natural Hg. - Abstract: Hg concentrations in seawater are usually too low to allow direct (without pre-concentration and removal of salt matrix) measurement of its isotope ratios with multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS). Therefore, a new method for the pre-concentration of Hg from large volumes of seawater was developed. The final method allows for relatively fast (about 2.5 L h −1 ) and quantitative pre-concentration of Hg from seawater samples with an average Hg recovery of 98 ± 6%. Using this newly developed method we determined Hg isotope ratios in seawater. Reference seawater samples were compared to samples potentially impacted by anthropogenic activity. The results show negative mass dependent fractionation relative to the NIST 3133 Hg standard with δ 202 Hg values in the range from −0.50‰ to −1.50‰. In addition, positive mass independent fractionation of 200 Hg was observed for samples from reference sites, while impacted sites did not show significant Δ 200 Hg values. Although the influence of the impacted sediments is limited to the seawater and particulate matter in very close proximity to the sediment, this observation may raise the possibility of using Δ 200 Hg to distinguish between samples from impacted and reference sites

Glacier Mass Changes of Lake-Terminating Grey and Tyndall Glaciers at the Southern Patagonia Icefield Derived From Geodetic Observations and Energy and Mass Balance Modeling

Directory of Open Access Journals (Sweden)

Stephanie S. Weidemann

2018-06-01

Full Text Available In this study we demonstrate how energy and mass fluxes vary in space and time for Grey and Tyndall glaciers at the Southern Patagonia Icefield (SPI. Despite the overall glacier retreat of most Patagonian glaciers, a recent increase in mass loss has been observed, but individual glaciers respond differently in terms of spatial and temporal changes. In this context, the detailed investigation of the effect of mass balance processes on recent glacier response to climate forcing still needs refinement. We therefore quantify surface energy-fluxes and climatic mass balance of the two neighboring glaciers, Grey and Tyndall. The COupled Snow and Ice energy and MAss balance model COSIMA is applied to assess recent surface energy and climatic mass balance variability with a high temporal and spatial resolution for a 16-year period between April 2000 and March 2016. The model is driven by downscaled 6-hourly atmospheric data derived from ERA-Interim reanalysis and MODIS/Terra Snow Cover and validated against ablation measurements made in single years. High resolution precipitation fields are determined by using an analytical orographic precipitation model. Frontal ablation is estimated as residual of climatic mass balance and geodetic mass balance derived from TanDEM-X/SRTM between 2000 and 2014. We simulate a positive glacier-wide mean annual climatic mass balance of +1.02 ± 0.52 m w.e. a−1 for Grey Glacier and of +0.68 ± 0.54 m w.e. a−1 for Tyndall Glacier between 2000 and 2014. Climatic mass balance results show a high year to year variability. Comparing climatic mass balance results with previous studies underlines the high uncertainty in climatic mass balance modeling with respect to accumulation on the SPI. Due to the lack of observations accumulation estimates differ from previous studies based on the methodological approaches. Mean annual ice loss by frontal ablation is estimated to be 2.07 ± 0.70 m w.e. a−1 for Grey Glacier and 3.26 ± 0

HgSe(Te)-HgHal2 systems

International Nuclear Information System (INIS)

Pan'ko, V.V.; Khudolij, V.A.; Voroshilov, Yu.V.

1989-01-01

Using the methods of differential thermal and X-ray phase analyses the character of chemical interaction in the systems HgTe(Se)-HgHal 2 , where Hal is Cl, Br, I, is investigated. Formation of compounds Hg 3 Se 2 Hal 2 , Hg 3 Te 2 Hal 2 , Hg 3 TeCl 4 and Hg 3 TeBr 4 in these systems is established. The phase diagrams of the studied systems are presented. The parameters of elementary cells of the compounds with the unknown structure, as well as their unknown physicochemical properties, are determined

Mass Balance Modelling of Saskatchewan Glacier, Canada Using Empirically Downscaled Reanalysis Data

Science.gov (United States)

Larouche, O.; Kinnard, C.; Demuth, M. N.

2017-12-01

Observations show that glaciers around the world are retreating. As sites with long-term mass balance observations are scarce, models are needed to reconstruct glacier mass balance and assess its sensitivity to climate. In regions with discontinuous and/or sparse meteorological data, high-resolution climate reanalysis data provide a convenient alternative to in situ weather observations, but can also suffer from strong bias due to the spatial and temporal scale mismatch. In this study we used data from the North American Regional Reanalysis (NARR) project with a 30 x 30 km spatial resolution and 3-hour temporal resolution to produce the meteorological forcings needed to drive a physically-based, distributed glacier mass balance model (DEBAM, Hock and Holmgren 2005) for the historical period 1979-2016. A two-year record from an automatic weather station (AWS) operated on Saskatchewan Glacier (2014-2016) was used to downscale air temperature, relative humidity, wind speed and incoming solar radiation from the nearest NARR gridpoint to the glacier AWS site. An homogenized historical precipitation record was produced using data from two nearby, low-elevation weather stations and used to downscale the NARR precipitation data. Three bias correction methods were applied (scaling, delta and empirical quantile mapping - EQM) and evaluated using split sample cross-validation. The EQM method gave better results for precipitation and for air temperature. Only a slight improvement in the relative humidity was obtained using the scaling method, while none of the methods improved the wind speed. The later correlates poorly with AWS observations, probably because the local glacier wind is decoupled from the larger scale NARR wind field. The downscaled data was used to drive the DEBAM model in order to reconstruct the mass balance of Saskatchewan Glacier over the past 30 years. The model was validated using recent snow thickness measurements and previously published geodetic mass

Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers

NARCIS (Netherlands)

Machguth, Horst; Thomsen, Henrik H.; Weidick, Anker; Ahlstrøm, Andreas P.; Abermann, Jakob; Andersen, Morten L.; Andersen, Signe B.; Bjørk, Anders A.; Box, Jason E.; Braithwaite, Roger J.; Bøggild, Carl E.; Citterio, Michele; Clement, Poul; Colgan, William; Fausto, Robert S.; Gleie, Karin; Gubler, Stefanie; Hasholt, Bent; Hynek, Bernhard; Knudsen, Niels T.; Larsen, Signe H.; Mernild, Sebastian H.; Oerlemans, Johannes; Oerter, Hans; Olesen, Ole B.; Smeets, C. J P Paul; Steffen, Konrad; Stober, Manfred; Sugiyama, Shin; Van As, Dirk; Van Den Broeke, Michiel R.; Van De Wal, Roderik S W

2016-01-01

Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in

Mass-Inertial Characteristics and Dimensionless Equations of Two-bearing Rotor Motion with Auto-balancer in Terms of Compensating Body Mass

Directory of Open Access Journals (Sweden)

A. N. Gorbenko

2015-01-01

Full Text Available Modern rotary machines use auto-balancing devices of passive type to provide automatic balancing of rotors and reduce vibration. Most available researches on the rotor auto-balancing dynamics and stability are based on the assumption that the compensating bodies of the autobalancer, as well as the rotor imbalance, are infinitesimal values. The literature review has shown that the problems concerning the automatic balancing of rotor with its three-dimensional motion are solved approximately and require an in-depth analysis taking into consideration the final mass of the compensating bodies.The paper analyses the effect of an auto-balancer mass on the mass-inertial properties of the three-dimensional rotor motion. It gives the autonomous equations of the system motion. The work shows that attaching the point masses of compensating auto-balancer bodies and imbalance to the rotor causes an increase, however non-identical, in all components of the total inertia tensor of the mechanical system. This leads to a qualitative change in mass-inertial characteristics of the system.The composite rotor becomes an inertia anisotropic body in which the inertia moments about the two transverse own axes are not equal to each other. The rotor anisotropy results in complicated dynamic behavior of the gyroscopic rotor. In this case, the additional critical rotor speeds and the zones of instability of motion may occur.It is shown that in the case of using multi-body auto-balancer the inertial parameters of the rotor system grow into the interval values, i.e. their values are not uniquely determined and may be equal to a variety values from a certain range. Thus, the degree of inertial anisotropy and other auto-balancing parameters are the interval values as well in this case.The system of dimensionless equations of rotary machine motion, which contains the minimum required number of dimensionless parameters, has been obtained. The specific ranges of the dimensionless

Reconstruction of specific mass balance for glaciers in Western ...

Indian Academy of Sciences (India)

Seasonal sensitivity characteristics (SSCs) were developed for Naradu, Shaune Garang, Gor Garang and Gara glaciers, Western Himalaya to quantify the changes in mean specific mass balance using monthly temperature and precipitation perturbations. The temperature sensitivities were observed high during summer ...

Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers

DEFF Research Database (Denmark)

Machguth, Horst; Thomsen, Henrik H.; Weidick, Anker

2016-01-01

Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in g...

The nuclear flow and the mass number dependence of the balance point

International Nuclear Information System (INIS)

Sebille, F.; de la Mota, V.; Remaud, B.; Schuck, P.

1990-01-01

The nuclear flow is studied theoretically with the Landau Vlasov equation in the E/A = 50 to 150 MeV energy domain using the finite range Gogny force. For comparison also other equations of states based on velocity independent mean fields are used. In this paper the mass number dependence of the balance point is investigated. A sensitivity of the flow on the equation of state as a function of mass and energies around and above the balance point can tentatively be advanced

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-28

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

Geochemical mass balance for sulfur- and nitrogen-bearing acid components: Eastern United States

International Nuclear Information System (INIS)

Bischoff, W.D.; Mackenzie, F.T.; Paterson, V.L.

1984-01-01

The impact on a geographical region of SO 2 and nitrogen oxides (NO /SUB x/ ) emissions to the atmosphere because of man's activities (e.g., burning of fossil fuels and smelting of sulfide ores) usually has not been considered in terms of a regional geochemical mass balance model. Mass balance models, however, have been employed extensively on a global scale. The models evaluate reservoir sizes, processes and fluxes associated with the transfer of a substance within a system of interest. The models may be steady- or transient-state, and include assessment of historical (geologic), present and future data and processes. In this chapter a geochemical mass balance model is applied to constituents of acid precipitation (H + , NO - 3 and SO 2- ) to evaluate the impact of acid precipitation on the eastern United States

An investigation of mercury sources in the Puyango-Tumbes River: Using stable Hg isotopes to characterize transboundary Hg pollution.

Science.gov (United States)

Schudel, Gary; Miserendino, Rebecca Adler; Veiga, Marcello M; Velasquez-López, P Colon; Lees, Peter S J; Winland-Gaetz, Sean; Davée Guimarães, Jean Remy; Bergquist, Bridget A

2018-07-01

Mercury (Hg) concentrations and stable isotopes along with other trace metals were examined in environmental samples from Ecuador and Peru's shared Puyango-Tumbes River in order to determine the extent to which artisanal- and small-scale gold mining (ASGM) in Portovelo-Zaruma, Ecuador contributes to Hg pollution in the downstream aquatic ecosystem. Prior studies investigated the relationship between ASGM activities and downstream Hg pollution relying primarily on Hg concentration data. In this study, Hg isotopes revealed an isotopically heavy Hg signature with negligible mass independent fractionation (MIF) in downstream sediments, which was consistent with the signature observed in the ASGM source endmember. This signature was traced as far as ∼120 km downstream of Portovelo-Zaruma, demonstrating that Hg stable isotopes can be used as a tool to fingerprint and trace sources of Hg over vast distances in freshwater environments. The success of Hg isotopes as a source tracer in fresh waters is largely due to the particle-reactive nature of Hg. Furthermore, the magnitude and extent of downstream Hg, lead, copper and zinc contamination coupled with the Hg isotopes suggest that it is unlikely that the smaller artisanal-scale activities, which do not use cyanidation, are responsible for the pollution. More likely it is the scale of ores processed and the cyanide leaching, which can release other metals and enhance Hg transport, used during small-scale gold mining that is responsible. Thus, although artisanal- and small-scale gold mining occur in tandem in Portovelo-Zaruma, a distinction should be made between these two activities. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hg stable isotope analysis by the double-spike method.

Science.gov (United States)

Mead, Chris; Johnson, Thomas M

2010-06-01

Recent publications suggest great potential for analysis of Hg stable isotope abundances to elucidate sources and/or chemical processes that control the environmental impact of mercury. We have developed a new MC-ICP-MS method for analysis of mercury isotope ratios using the double-spike approach, in which a solution containing enriched (196)Hg and (204)Hg is mixed with samples and provides a means to correct for instrumental mass bias and most isotopic fractionation that may occur during sample preparation and introduction into the instrument. Large amounts of isotopic fractionation induced by sample preparation and introduction into the instrument (e.g., by batch reactors) are corrected for. This may greatly enhance various Hg pre-concentration methods by correcting for minor fractionation that may occur during preparation and removing the need to demonstrate 100% recovery. Current precision, when ratios are normalized to the daily average, is 0.06 per thousand, 0.06 per thousand, 0.05 per thousand, and 0.05 per thousand (2sigma) for (202)Hg/(198)Hg, (201)Hg/(198)Hg, (200)Hg/(198)Hg, and (199)Hg/(198)Hg, respectively. This is slightly better than previously published methods. Additionally, this precision was attained despite the presence of large amounts of other Hg isotopes (e.g., 5.0% atom percent (198)Hg) in the spike solution; substantially better precision could be achieved if purer (196)Hg were used.

Morphometric Controls on Glacier Mass Balance of the Puruogangri Ice Field, Central Tibetan Plateau

Directory of Open Access Journals (Sweden)

Lin Liu

2016-11-01

Full Text Available Evaluating the impacts of climatic changes and morphometric features on glacier mass balance is crucial to providing insight into glacier changes and their effects on regional water resources and ecosystems. Here, we presented an evaluation of morphometric effects on the glacier mass balances of the Puruogangri ice field (PIF on the Tibetan Plateau. A clear spatial variability of glacier mass balances, ranging from −0.035 to +0.019 m·w.e.·year−1, was estimated by comparing the TanDEM-X DEM (2012 with the SRTM-X DEM (2000. In general, the observed glacier mass changes were consistent with our fieldwork investigations. Furthermore, by applying the method of linear regression analysis, we found that the mass changes of individual glaciers on the PIF were mainly dominated by the mean altitude (R = 0.84, p < 0.001, however, they were statistically independent of glacier size, aspect, and surface velocity. At a local scale (grid size of 10 × 10 pixels, apart from the factor of altitude, surface velocity was correlated with glacier mass change.

California's Snow Gun and its implications for mass balance predictions under greenhouse warming

Science.gov (United States)

Howat, I.; Snyder, M.; Tulaczyk, S.; Sloan, L.

2003-12-01

Precipitation has received limited treatment in glacier and snowpack mass balance models, largely due to the poor resolution and confidence of precipitation predictions relative to temperature predictions derived from atmospheric models. Most snow and glacier mass balance models rely on statistical or lapse rate-based downscaling of general or regional circulation models (GCM's and RCM's), essentially decoupling sub-grid scale, orographically-driven evolution of atmospheric heat and moisture. Such models invariably predict large losses in the snow and ice volume under greenhouse warming. However, positive trends in the mass balance of glaciers in some warming maritime climates, as well as at high elevations of the Greenland Ice Sheet, suggest that increased precipitation may play an important role in snow- and glacier-climate interactions. Here, we present a half century of April snowpack data from the Sierra Nevada and Cascade mountains of California, USA. This high-density network of snow-course data indicates that a gain in winter snow accumulation at higher elevations has compensated loss in snow volume at lower elevations by over 50% and has led to glacier expansion on Mt. Shasta. These trends are concurrent with a region-wide increase in winter temperatures up to 2° C. They result from the orographic lifting and saturation of warmer, more humid air leading to increased precipitation at higher elevations. Previous studies have invoked such a "Snow Gun" effect to explain contemporaneous records of Tertiary ocean warming and rapid glacial expansion. A climatological context of the California's "snow gun" effect is elucidated by correlation between the elevation distribution of April SWE observations and the phase of the Pacific Decadal Oscillation and the El Nino Southern Oscillation, both controlling the heat and moisture delivered to the U.S. Pacific coast. The existence of a significant "Snow Gun" effect presents two challenges to snow and glacier mass

A 3-axis force balanced accelerometer using a single proof-mass

Energy Technology Data Exchange (ETDEWEB)

Lemkin, M.A.; Boser, B.E.; Auslander, D. [Univ. of California, Berkeley, CA (United States); Smith, J. [Sandia National Lab., Albuquerque, NM (United States)

1997-04-01

This paper presents a new method for wideband force balancing a proof-mass in multiple axes simultaneously. Capacitive position sense and force feedback are accomplished using the same air-gap capacitors through time multiplexing. Proof of concept is experimentally demonstrated with a single-mass monolithic surface micromachined 3-axis accelerometer.

Development of pre-concentration procedure for the determination of Hg isotope ratios in seawater samples.

Science.gov (United States)

Štrok, Marko; Hintelmann, Holger; Dimock, Brian

2014-12-03

Hg concentrations in seawater are usually too low to allow direct (without pre-concentration and removal of salt matrix) measurement of its isotope ratios with multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS). Therefore, a new method for the pre-concentration of Hg from large volumes of seawater was developed. The final method allows for relatively fast (about 2.5Lh(-1)) and quantitative pre-concentration of Hg from seawater samples with an average Hg recovery of 98±6%. Using this newly developed method we determined Hg isotope ratios in seawater. Reference seawater samples were compared to samples potentially impacted by anthropogenic activity. The results show negative mass dependent fractionation relative to the NIST 3133 Hg standard with δ(202)Hg values in the range from -0.50‰ to -1.50‰. In addition, positive mass independent fractionation of (200)Hg was observed for samples from reference sites, while impacted sites did not show significant Δ(200)Hg values. Although the influence of the impacted sediments is limited to the seawater and particulate matter in very close proximity to the sediment, this observation may raise the possibility of using Δ(200)Hg to distinguish between samples from impacted and reference sites. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of iodine based impinger solutions for the efficient capture of Hg{sup 0} using direct injection nebulization-inductively coupled plasma mass spectrometry analysis

Energy Technology Data Exchange (ETDEWEB)

Hedrick, E.; Lee, T.G.; Biswas, P.; Zhuang, Y. [US Environmental Protection Agency, Cincinnati, OH (USA). National Exposure Research Laboratory

2001-09-15

Inductively coupled plasma mass spectrometry (ICP/MS) with direct injection nebulization (DIN) was used to evaluate novel impinger solution compositions capable of capturing elemental mercury (Hg{sup 0}) in EPA Method 5 type sampling. An iodine based impinger solution proved to be very efficient for Hg{sup 0} capture and was amenable to direct analysis by DIN-ICP/MS. Hg{sup 0} capture efficiency using aqueous iodine (I{sub 3}{sup -}) was comparable to Hg{sup 0} capture using acidified potassium permanganate impinger solutions which were analyzed by cold vapor atomic absorption spectrometry (CVAAS) with greater than 98% capture of Hg{sup 0} in the oxidizing impinger. Using DIN-ICP/MS, it was demonstrated for the first time that iodine can be generated just prior to impinger sampling for efficiently oxidizing Hg{sup 0} and retailing it in solution as HgI{sub 4}{sup 2-}. Due to the increased interest in Hg speciation from combustion sources and the potential for using DIN-ICP/MS for multiple metals analyses, an impinger sampling train for gaseous Hg speciation and multiple metals analyses using DIN-ICP/MS analyses is presented. The unique feature of such a sampling train is that each impinger solution in the series is amenable to direct analysis by DIN-ICP/MS. A bituminous coal was combusted in a bench scale coal system, and gaseous Hg species (oxidized and elemental) were determined using the proposed impinger train. The DIN-ICP/Ms instrumental detection limit was 0.003 ppb, and MDLs ranged from 0.007 to 0.116 {mu}g/L (ppb) in a variety of impinger solutions used for Hg capture. 33 refs., 5 figs., 7 tabs.

Composting: Mass Balances and Product Quality

DEFF Research Database (Denmark)

Boldrin, Alessio; Christensen, Thomas Højlund; Körner, I.

2011-01-01

While the basic processes involved in composting of waste are described in Chapter 9.1 and the main composting technologies are presented in Chapter 9.2, this chapter focuses on mass balances, environmental emissions, unit process inventories and the quality of the compost produced. Understanding...... these issues and being able to account for them is a prerequisite in compost engineering and for establishing and running a successful composting facility. Of specific importance is the final use of the compost product. Use in agriculture is described in Chapter 9.10 and the use of compost in soil amendment...

Use of mass and toxicity balances in risk-based corrective action decisions at contaminated sites

International Nuclear Information System (INIS)

Sevigny, J.H.; Lintott, D.; Wrubleski, R.M.; Drury, C.R.

1997-01-01

The contaminated groundwater at a sour gas plant facility was studied to identify the chemicals of environmental concern. Simple mass balance principles were used to determine the proportion of organic carbon, organic nitrogen and Microtox R toxicity that can be attributed to two process chemicals that have contaminated several sour gas plants in western Canada. The two process chemicals are sulfolane and diisopropanolamine (DIPA). The organic carbon balance was calculated by determining the molar contribution of sulfolane and DIPA relative to the mass of carboxylic acid-corrected dissolved organic carbon. Organic carbon balances ranged from 44 to 96 per cent. The organic nitrogen balance was calculated by determining the molar contribution of DIPA relative to the mass of ammonium ion-corrected dissolved Kjeldahl nitrogen. The nitrogen balances were highly variable between 8 to 48 per cent for samples with organic nitrogen concentrations between 10 and 32 mg/L. The Microtox R toxicity balance was calculated by determining the proportions of toxicity that could be accounted for by pure phase sulfolane and DIPA. The Microtox R toxicity balance for samples that showed significant toxicity ranged from 71 to 122 per cent

Use of mass and toxicity balances in risk-based corrective action decisions at contaminated sites

Energy Technology Data Exchange (ETDEWEB)

Sevigny, J.H. [Komex Consultants Ltd., Calgary, AB (Canada); Lintott, D. [HydroQual Consultants, Inc., Calgary, AB (Canada); Wrubleski, R.M.; Drury, C.R. [Shell Canada Ltd., Calgary, AB (Canada). Calgary Research Centre

1997-12-31

The contaminated groundwater at a sour gas plant facility was studied to identify the chemicals of environmental concern. Simple mass balance principles were used to determine the proportion of organic carbon, organic nitrogen and Microtox{sup R} toxicity that can be attributed to two process chemicals that have contaminated several sour gas plants in western Canada. The two process chemicals are sulfolane and diisopropanolamine (DIPA). The organic carbon balance was calculated by determining the molar contribution of sulfolane and DIPA relative to the mass of carboxylic acid-corrected dissolved organic carbon. Organic carbon balances ranged from 44 to 96 per cent. The organic nitrogen balance was calculated by determining the molar contribution of DIPA relative to the mass of ammonium ion-corrected dissolved Kjeldahl nitrogen. The nitrogen balances were highly variable between 8 to 48 per cent for samples with organic nitrogen concentrations between 10 and 32 mg/L. The Microtox{sup R} toxicity balance was calculated by determining the proportions of toxicity that could be accounted for by pure phase sulfolane and DIPA. The Microtox{sup R} toxicity balance for samples that showed significant toxicity ranged from 71 to 122 per cent.

Mass Balance of Novaya Zemlya Archipelago from 2002 to Present

Science.gov (United States)

Ciraci, E.; Velicogna, I.; Fettweis, X.

2017-12-01

We employ satellite gravimetry from NASA's Gravity Recovery and Climate Experiment (GRACE) using a least-squares fit mascon approach to evaluate the mass balance of the glaciers of the Novaya Zemlya Archipelago (NZA) from 2002 to present. Our results reveal a mean mass loss 8±5 Gt/yr (gigatons per year), which makes NZA the largest contributor to sea level rise in the Russian Arctic (total Russian Arctic contributes 16±7Gt/yr). We then use Surface Mass Balance (SMB) estimates from the Modèle Atmosphérique Régional (MAR) and ice elevation change rates from NASA ICESat (2003-2009) and ESA CryoSat-2 (2010-present) altimetry data to gain insight about the physical processes driving the observed mass loss. We find that the inter-annual variability in SMB displays a significant correlation (0.6, p-val sea level rise. Elevation change from satellite altimetry reveals substantial thinning at low altitudes for both marine and land terminating glaciers. This result is consistent with the negative cumulative SMB values found at those sites. Yet, altimetry-derived thinning rates for the marine terminating glaciers are on average two times larger than those for land-terminating glaciers. We conclude that both SMB and ice dynamics play important roles in the regional ice mass loss.

Diagnosing the decline in climatic mass balance of glaciers in Svalbard over 1957–2014

NARCIS (Netherlands)

Østby, T.I.; Schuler, T.V.; Hagen, J.O.; Hock, Regine; Kohler, J.; Reijmer, C.H.

2017-01-01

Estimating the long-term mass balance of the high-Arctic Svalbard archipelago is difficult due to the incomplete geodetic and direct glaciological measurements, both in space and time. To close these gaps, we use a coupled surface energy balance and snow pack model to analyse the mass changes of all

Greenland ice sheet mass balance: a review.

Science.gov (United States)

Khan, Shfaqat A; Aschwanden, Andy; Bjørk, Anders A; Wahr, John; Kjeldsen, Kristian K; Kjær, Kurt H

2015-04-01

Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance and to ice discharge, which are forced by internal or external (atmospheric/oceanic/basal) fluctuations. Regardless of the measurement method, observations over the last two decades show an increase in ice loss rate, associated with speeding up of glaciers and enhanced melting. However, both ice discharge and melt-induced mass losses exhibit rapid short-term fluctuations that, when extrapolated into the future, could yield erroneous long-term trends. In this paper we review the GrIS mass loss over more than a century by combining satellite altimetry, airborne altimetry, interferometry, aerial photographs and gravimetry data sets together with modelling studies. We revisit the mass loss of different sectors and show that they manifest quite different sensitivities to atmospheric and oceanic forcing. In addition, we discuss recent progress in constructing coupled ice-ocean-atmosphere models required to project realistic future sea-level changes.

Comparison of Glaciological and Gravimetric Glacier Mass Balance Measurements of Taku and Lemon Creek Glaciers, Southeast Alaska

Science.gov (United States)

Vogler, K.; McNeil, C.; Bond, M.; Getraer, B.; Huxley-Reicher, B.; McNamara, G.; Reinhardt-Ertman, T.; Silverwood, J.; Kienholz, C.; Beedle, M. J.

2017-12-01

Glacier-wide annual mass balances (Ba) have been calculated for Taku (726 km2) and Lemon Creek glaciers (10.2 km2) since 1946 and 1953 respectively. These are the longest mass balance records in North America, and the only Ba time-series available for Southeast Alaska, making them particularly valuable for the global glacier mass balance monitoring network. We compared Ba time-series from Taku and Lemon Creek glaciers to Gravity Recovery and Climate Experiment (GRACE) mascon solutions (1352 and 1353) during the 2004-2015 period to assess how well these gravimetric solutions reflect individual glaciological records. Lemon Creek Glacier is a challenging candidate for this comparison because it is small compared to the 12,100 km2 GRACE mascon solutions. Taku Glacier is equally challenging because its mass balance is stable compared to the negative balances dominating its neighboring glaciers. Challenges notwithstanding, a high correlation between the glaciological and gravimetrically-derived Ba for Taku and Lemon Creek glaciers encourage future use of GRACE to measure glacier mass balance. Additionally, we employed high frequency ground penetrating radar (GPR) to measure the variability of accumulation around glaciological sites to assess uncertainty in our glaciological measurements, and the resulting impact to Ba. Finally, we synthesize this comparison of glaciological and gravimetric mass balance solutions with a discussion of potential sources of error in both methods and their combined utility for measuring regional glacier change during the 21st century.

Evidence for mass-independent and mass-dependent fractionation of the stable isotopes of mercury by natural processes in aquatic ecosystems

International Nuclear Information System (INIS)

Jackson, Togwell A.; Whittle, D. Michael; Evans, Marlene S.; Muir, Derek C.G.

2008-01-01

Isotopic and chemical analyses were performed on crustaceans, forage fish, top predator fish, and sediment cores from Lake Ontario and two boreal forest lakes to investigate fractionation of the stable isotopes of Hg in aquatic ecosystems. Multicollector inductively coupled mass spectrometry was used to determine Hg isotope abundances. The Hg isotope data for all three lakes showed mass-independent variation in the organisms but only mass-dependent variation in the sediments. The mass-independent isotope effect was characterised by (1) selective enrichment in isotopes of odd mass number ( 199 Hg and 201 Hg), (2) enrichment in 201 Hg relative to 199 Hg, (3) an inverse relationship between isotopes of odd and even mass number in fish, and (4) a positive correlation with methylHg (CH 3 Hg + ) concentration, and hence with trophic level (although lake whitefish were consistently anomalous, possibly owing to biochemical demethylation). Isotope signatures of species at the same trophic level varied with habitat and diet, differentiating between planktonic and benthic crustaceans and their predators, and between fish that frequent deep, cold water and fish of similar diet that prefer warmer, shallower water, because of corresponding differences in CH 3 Hg + and inorganic Hg content. Isotopic analysis of CH 3 Hg + and inorganic Hg extracted from lake trout proved that the mass-independent isotope effect was due to anomalously high abundances of 199 Hg and 201 Hg in CH 3 Hg + , as implied by the data for whole organisms, suggesting mass-independent fractionation during microbial methylation of Hg. The purely mass-dependent variation in the sediments is attributable to the fact that Hg in sediments is mostly inorganic. The mass-independent fractionation of Hg isotopes can be explained by effects of nuclear spin or nuclear field shift, or both, and penetration of the inner electron shells of Hg by valence electrons of Hg-binding ligands. The results of the research

Mass-Balance Constraints on Nutrient Cycling in Tropical Seagrass Beds

NARCIS (Netherlands)

Erftemeijer, P.L.A.; Middelburg, J.J.

1995-01-01

A relatively simple mass balance model is presented to study the cycling of nutrients (nitrogen and phosphorus) in tropical seagrass beds. The model is based on quantitative data on nutrient availability, seagrass primary production, community oxygen metabolism, seagrass tissue nutrient contents,

Solar radiation, cloudiness and longwave radiation over low-latitude glaciers: implications for mass-balance modelling

Science.gov (United States)

Mölg, Thomas; Cullen, Nicolas J.; Kaser, Georg

Broadband radiation schemes (parameterizations) are commonly used tools in glacier mass-balance modelling, but their performance at high altitude in the tropics has not been evaluated in detail. Here we take advantage of a high-quality 2 year record of global radiation (G) and incoming longwave radiation (L↓) measured on Kersten Glacier, Kilimanjaro, East Africa, at 5873 m a.s.l., to optimize parameterizations of G and L↓. We show that the two radiation terms can be related by an effective cloud-cover fraction neff, so G or L↓ can be modelled based on neff derived from measured L↓ or G, respectively. At neff = 1, G is reduced to 35% of clear-sky G, and L↓ increases by 45-65% (depending on altitude) relative to clear-sky L↓. Validation for a 1 year dataset of G and L↓ obtained at 4850 m on Glaciar Artesonraju, Peruvian Andes, yields a satisfactory performance of the radiation scheme. Whether this performance is acceptable for mass-balance studies of tropical glaciers is explored by applying the data from Glaciar Artesonraju to a physically based mass-balance model, which requires, among others, G and L↓ as forcing variables. Uncertainties in modelled mass balance introduced by the radiation parameterizations do not exceed those that can be caused by errors in the radiation measurements. Hence, this paper provides a tool for inclusion in spatially distributed mass-balance modelling of tropical glaciers and/or extension of radiation data when only G or L↓ is measured.

Glacier mass balance and its potential impacts in the Altai Mountains over the period 1990-2011

Science.gov (United States)

Zhang, Yong; Enomoto, Hiroyuki; Ohata, Tetsuo; Kitabata, Hideyuki; Kadota, Tsutomu; Hirabayashi, Yukiko

2017-10-01

The Altai Mountains contain 1281 glaciers covering an area of 1191 km2. These glaciers have undergone significant changes in glacial length and area over the past decade. However, mass changes of these glaciers and their impacts remain poorly understood. Here we present surface mass balances of all glaciers in the region for the period 1990-2011, using a glacier mass-balance model forced by the outputs of a regional climate model. Our results indicate that the mean specific mass balance for the whole region is about -0.69 m w.e. yr-1 over the entire period, and about 81.3% of these glaciers experience negative net mass balance. We detect an accelerated wastage of these glaciers in recent years, and marked differences in mass change and its sensitivity to climate change for different regions and size classes. In particular, higher mass loss and temperature sensitivity are observed for glaciers smaller than 0.5 km2. In addition to temperature rise, a decrease in precipitation in the western part of the region and an increase in precipitation in the eastern part likely contribute to significant sub-region differences in mass loss. With significant glacier wastage, the contribution of all glaciers to regional water resources and sea-level change becomes larger than before, but may not be a potential threat to human populations through impacts on water availability.

Can we close the long term mass balance equation for pollutants in highway ponds?

DEFF Research Database (Denmark)

Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

2007-01-01

The paper discusses the prospects of finding the long term mass balance on basis of short term simulations. A step in this process is to see to which degree the mass balance equation can be closed by measurements. Accordingly the total accumulation of heavy metals and PAH's in 8 Danish detention...... ponds only receiving runoff from highways have been measured. The result shows that the incoming mass of heavy metals from short term runoff events is accumulated. This is not observable in the same magnitude for the toxic organic compounds. The results also show that the accumulation rates...

Hg0 and HgCl2 Reference Gas Standards: ?NIST Traceability ...

Science.gov (United States)

EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the true concentrations of Hg0 and HgCl2 reference gases produced from high quality, NIST-traceable, commercial Hg0 and HgCl2 generators. This presentation will also discuss the availability of HCl and Hg0 compressed reference gas standards as a result of EPA's recently approved Alternative Methods 114 and 118. Gaseous elemental mercury (Hg0) and oxidized mercury (HgCl2) reference standards are integral to the use of mercury continuous emissions monitoring systems (Hg CEMS) for regulatory compliance emissions monitoring. However, a quantitative disparity of approximately 7-10% has been observed between commercial Hg0 and HgCl2 reference gases which currently limits the use of (HgCl2) reference gas standards. Resolving this disparity would enable the expanded use of (HgCl2) reference gas standards for regulatory compliance purposes.

A LEGO Watt balance: An apparatus to determine a mass based on the new SI

Science.gov (United States)

Chao, L. S.; Schlamminger, S.; Newell, D. B.; Pratt, J. R.; Seifert, F.; Zhang, X.; Sineriz, G.; Liu, M.; Haddad, D.

2015-11-01

A global effort to redefine our International System of Units (SI) is underway, and the change to the new system is expected to occur in 2018. Within the newly redefined SI, the present base units will still exist but be derived from fixed numerical values of seven reference constants. In particular, the unit of mass (the kilogram) will be realized through a fixed value of the Planck constant h. A so-called watt balance, for example, can then be used to realize the kilogram unit of mass within a few parts in 108. Such a balance has been designed and constructed at the National Institute of Standards and Technology. For educational outreach and to demonstrate the principle, we have constructed a LEGO tabletop watt balance capable of measuring a gram-level masses to 1% relative uncertainty. This article presents the design, construction, and performance of the LEGO watt balance and its ability to determine h.

Methylation of Hg downstream from the Bonanza Hg mine, Oregon

Science.gov (United States)

Gray, John E.; Hines, Mark E.; Krabbenhoft, David P.; Thoms, Bryn

2012-01-01

Speciation of Hg and conversion to methyl-Hg were evaluated in stream sediment, stream water, and aquatic snails collected downstream from the Bonanza Hg mine, Oregon. Total production from the Bonanza mine was >1360t of Hg, during mining from the late 1800s to 1960, ranking it as an intermediate sized Hg mine on an international scale. The primary objective of this study was to evaluate the distribution, transport, and methylation of Hg downstream from a Hg mine in a coastal temperate climatic zone. Data shown here for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from this area. Stream sediment collected from Foster Creek flowing downstream from the Bonanza mine contained elevated Hg concentrations that ranged from 590 to 71,000ng/g, all of which (except the most distal sample) exceeded the probable effect concentration (PEC) of 1060ng/g, the Hg concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in stream sediment collected from Foster Creek varied from 11 to 62ng/g and were highly elevated compared to regional baseline concentrations (0.11-0.82ng/g) established in this study. Methyl-Hg concentrations in stream sediment collected in this study showed a significant correlation with total organic C (TOC, R2=0.62), generally indicating increased methyl-Hg formation with increasing TOC in sediment. Isotopic-tracer methods indicated that several samples of Foster Creek sediment exhibited high rates of Hg-methylation. Concentrations of Hg in water collected downstream from the mine varied from 17 to 270ng/L and were also elevated compared to baselines, but all were below the 770ng/L Hg standard recommended by the USEPA to protect against chronic effects to aquatic wildlife. Concentrations of methyl-Hg in the water collected from Foster Creek ranged from 0.17 to 1.8ng/L, which were elevated compared to regional baseline sites upstream and downstream

Recovery of total Hg from geological matrices: a methodological intercomparison study (W6)

International Nuclear Information System (INIS)

Bloom, N.S.; Vondergeest, E.J.; Preus, E.M.; Horvat, M.; Prosenc, N.; Kingston, S.; Apte, S.; Pobbs, C.

2002-01-01

Full text: Aqua regia is commonly used for the extraction of Hg from soils prior to cold vapor spectrometry, but mass balance studies suggested it is not sufficiently robust to recover all Hg from more recalcitrant materials such as crystalline ores. As a result, an intercomparison exercise was undertaken between the following methods: (a) aqua regia digestion (EPA 7471) followed by SnCl 2 reduction, gold trapping and CVAFS detection, (b) Teflon bomb digestion at 110 o C with a 10:5:2 HNO 3 + HF + HCl mixture followed by SnCl 2 reduction, gold trapping and CVAFS, (c) 800 o C pyrolysis with gold trapping and CVAAS detection (EPA 7473), and (d) NAA followed by radiochemical separations using oxidative combustion and gold trapping. All methods gave quantitative recoveries from soil and sediment CRMs, but only the HF/HCI/HNO 3 digestion gave quantitative recoveries in all media. Pyrolysis resulted in approximately 88 ± 10 % recovery, while aqua regia digestion resulted in only about 61 ± 24 % recovery in bauxite ores and residues. RNAA generally gave the best agreement with the HF based digestion, although in a significant number of samples, particularly bauxite ores, recoveries were as low as 50 %. Based on these findings, we recommend that bomb digestions which include the use HF be applied to the analysis of Hg in geological solids, unless the matrix is documented to be fully extractable by a less rigorous procedure. We suggest a reference value for Hg in bauxite reference material (NIST-600) of 79.0 ± 2.0 ng/g, based on the pooled results of three laboratories. (author)

Quasiparticle excitations in superdeformed {sup 192}Hg

Energy Technology Data Exchange (ETDEWEB)

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

1995-08-01

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

Balance of dark and luminous mass in rotating galaxies.

Science.gov (United States)

McGaugh, Stacy S

2005-10-21

A fine balance between dark and baryonic mass is observed in spiral galaxies. As the contribution of the baryons to the total rotation velocity increases, the contribution of the dark matter decreases by a compensating amount. This poses a fine-tuning problem for galaxy formation models, and may point to new physics for dark matter particles or even a modification of gravity.

196Hg and 202Hg isotopic ratios in chondrites: revisited

International Nuclear Information System (INIS)

Jovanovic, S.; Reed, G.W. Jr.

1976-01-01

Additional evidence for an isotopically anomalous Hg fraction in unequilibrated meteorites has been obtained using neutron activation to produce 196 Hg and 202 Hg followed by stepwise heating to extract the Hg. In the latest experiments Allende matrix samples released the anomalous Hg but various high-temperature inclusions did not. Nucleogenetic processes are suggested as the probable cause of the anomaly. (Auth.)

Influence of Persistent Wind Scour on the Surface Mass Balance of Antarctica

Science.gov (United States)

Das, Indrani; Bell, Robin E.; Scambos, Ted A.; Wolovick, Michael; Creyts, Timothy T.; Studinger, Michael; Fearson, Nicholas; Nicolas, Julien P.; Lenaerts, Jan T. M.; vandenBroeke, Michiel R.

2013-01-01

Accurate quantification of surface snow accumulation over Antarctica is a key constraint for estimates of the Antarctic mass balance, as well as climatic interpretations of ice-core records. Over Antarctica, near-surface winds accelerate down relatively steep surface slopes, eroding and sublimating the snow. This wind scour results in numerous localized regions (Antarctica. The scour zones are persistent because they are controlled by bedrock topography. On the basis of our Dome A observations, we develop an empirical model to predict wind-scour zones across the Antarctic continent and find that these zones are predominantly located in East Antarctica. We estimate that approx. 2.7-6.6% of the surface area of Antarctica has persistent negative net accumulation due to wind scour, which suggests that, across the continent, the snow mass input is overestimated by 11-36.5 Gt /yr in present surface-mass-balance calculations.

A mass balance study of the phytoremediation of perchloroethylene-contaminated groundwater

International Nuclear Information System (INIS)

Andrew James, C.; Xin Gang; Doty, Sharon L.; Muiznieks, Indulis; Newman, Lee; Strand, Stuart E.

2009-01-01

A mass balance study was performed under controlled field conditions to investigate the phytoremediation of perchloroethylene (PCE) by hybrid poplar trees. Water containing 7-14 mg L -1 PCE was added to the test bed. Perchloroethylene, trichloroethylene, and cis-dichloroethylene were detected in the effluent at an average of 0.12 mg L -1 , 3.9 mg L -1 , and 1.9 mg L -1 , respectively. The total mass of chlorinated ethenes in the water was reduced by 99%. Over 95% of the recovered chlorine was as free chloride in the soil, indicating near-complete dehalogenation of the PCE. Transpiration, volatilization, and accumulation in the trees were all found to be minor loss mechanisms. In contrast, 98% of PCE applied to an unplanted soil chamber was recovered as PCE in the effluent water or volatilized into the air. These results suggest that phytoremediation can be an effective method for treating PCE-contaminated groundwater in field applications. - A chlorine balance performed on a planted test bed with PCE-contaminated water demonstrated VOC mass reduction of 99% and complete dechlorination.

A mass balance study of the phytoremediation of perchloroethylene-contaminated groundwater

Energy Technology Data Exchange (ETDEWEB)

Andrew James, C. [University of Washington, Department of Civil and Environmental Engineering, Seattle, WA (United States); Xin Gang [Hydranautics, 401 Jones Rd., Oceanside, CA 92058 (United States); Doty, Sharon L.; Muiznieks, Indulis [University of Washington, College of Forest Resources, Seattle, WA (United States); Newman, Lee [Brookhaven National Laboratory, Biology Department, Upton, NY (United States); Strand, Stuart E., E-mail: sstrand@u.washington.ed [University of Washington, Department of Civil and Environmental Engineering, Seattle, WA (United States)

2009-08-15

A mass balance study was performed under controlled field conditions to investigate the phytoremediation of perchloroethylene (PCE) by hybrid poplar trees. Water containing 7-14 mg L{sup -1} PCE was added to the test bed. Perchloroethylene, trichloroethylene, and cis-dichloroethylene were detected in the effluent at an average of 0.12 mg L{sup -1}, 3.9 mg L{sup -1}, and 1.9 mg L{sup -1}, respectively. The total mass of chlorinated ethenes in the water was reduced by 99%. Over 95% of the recovered chlorine was as free chloride in the soil, indicating near-complete dehalogenation of the PCE. Transpiration, volatilization, and accumulation in the trees were all found to be minor loss mechanisms. In contrast, 98% of PCE applied to an unplanted soil chamber was recovered as PCE in the effluent water or volatilized into the air. These results suggest that phytoremediation can be an effective method for treating PCE-contaminated groundwater in field applications. - A chlorine balance performed on a planted test bed with PCE-contaminated water demonstrated VOC mass reduction of 99% and complete dechlorination.

Adjustment of regional climate model output for modeling the climatic mass balance of all glaciers on Svalbard.

NARCIS (Netherlands)

Möller, M.; Obleitner, F.; Reijmer, C.H.; Pohjola, V.A.; Glowacki, P.; Kohler, J.

2016-01-01

Large-scale modeling of glacier mass balance relies often on the output from regional climate models (RCMs). However, the limited accuracy and spatial resolution of RCM output pose limitations on mass balance simulations at subregional or local scales. Moreover, RCM output is still rarely available

Water vapor mass balance method for determining air infiltration rates in houses

Science.gov (United States)

David R. DeWalle; Gordon M. Heisler

1980-01-01

A water vapor mass balance technique that includes the use of common humidity-control equipment can be used to determine average air infiltration rates in buildings. Only measurements of the humidity inside and outside the home, the mass of vapor exchanged by a humidifier/dehumidifier, and the volume of interior air space are needed. This method gives results that...

Accumulation of Mercury (Hg) and Methyl Mercury (Me Hg) Concentrations In Selected Marine Biota From Manjung Coastal Area

International Nuclear Information System (INIS)

Anisa Abdullah; Zaini Hamzah; Ahmad Saat; Ahmad Saat; Abd Khalik Wood; Masitah Alias

2015-01-01

Level of mercury (Hg) and methyl mercury (Me Hg) in marine ecosystem has been intensively studied as these toxic substances could be accumulated in the marine biota. This study is focusing on the Hg and Me Hg content in marine biota in Manjung coastal area. This area has high potential being affected by rapid socio-economic development of Manjung area such as heavy industrial activities (coal fired power plant, iron foundries, port development and factories), agricultural runoff, waste and toxic discharge, quarries, housing constructions. It may has a potential risk when released into the atmosphere and dispersed on the surface of water and continue deposited at the bottom of the water and sediment and being absorbed by marine biota. The concentrations of Hg and Me Hg in marine ecosystem can be adversely affect human health when it enters the food chain. In this study, five species of marine biota including Johnius dussumieri (Ikan Gelama), Pseudorhombus malayanus (Ikan Sebelah), Arius maculatus (Ikan Duri), Portunus pelagicus (Ketam Renjong) and Charybdis natator (Ketam Salib) were collected during rainy and dry seasons. Measurements were carried out using inductively coupled plasma mass spectrometry (ICP-MS) technique. The Hg concentrations for dry and rainy season are in the range 65.13-102.12 μg/ kg and 75.75-106.10 μg/ kg respectively, while for MeHg concentrations for dry and rainy seasons are in the range 4.35-6.26 μg/ kg and 5.42-6.46 μg/ kg, respectively. These results are below the limit set by Malaysia Food Act (1983). Generally, marine biota from the Manjung coastal area is safe to consume due to low value of ingestion dose rate and health risk index (HRI) for human health. (author)

Studying the Effects of Amazonian Land Cover Change on Glacier Mass Balance in the Tropical Andes

Science.gov (United States)

Mark, B. G.; Fernandez, A.; Gabrielli, P.; Montenegro, A.; Postigo, J.; Hellstrom, R. A.

2017-12-01

Recent research has highlighted several ongoing environmental changes occurring across Tropical South America, including Andean glacier retreat, drought, as well as changes in land-use and land-cover. As the regional climate of the area is mostly characterized by land-ocean interactions, the atmospheric convection in the Amazon, and the effect of the Andes on circulation patterns, it follows that changes in one of those regions may affect the other. Most scholars who have studied the causes of tropical glaciers' fluctuations have not analyzed the linkages with changes in the Amazon with the same attention paid to the influence of Pacific sea surface temperature. Here we study the response of glacier surface mass balance in the Cordillera Blanca, Peru (10°S), to a scenario where the Amazonian rainforest is replaced by savannas. We ran climatic simulations at 2-km spatial resolution utilizing the Weather Research and Forecasting (WRF) model considering two scenarios: (a) control (CRTL), with today's rainforest extent; and (b) land cover change (LCC), where all the rainforest was replaced by savanna. WRF output was in turn ingested into a glacier energy and mass balance (GEMB) model that we validate by reconstructing both the accumulated mass balance from available observations, and the altitudinal distribution of mass balance in the region. Seasonal comparison between CRTL and LCC scenarios indicates that forest replacement by savanna results in more positive glacier mass balance. This shift to more positive mass balance contrasts with a (WRF) modeled rise in the elevation of the freezing line (0°C) between 30 to 120 m for the LCC scenario. Our results are surprising because most previous studies have shown that reducing Amazon forest cover diminishes rainfall and increases temperature, suggesting that glaciers should lose mass. We hypothesize and discuss implications of possible land-atmospheric processes that might drive this tropical glacier response to

A thermodynamic stability of bulk and epitaxial CdHgTe, ZnHgTe and MnHgTe solid solutions

International Nuclear Information System (INIS)

Dejbuk, V.G.; Dremlyuzhenko, S.G.; Ostapov, S.Eh.

2005-01-01

A thermodynamics of Cd 1-x Hg x Te, Zn x Hg 1-x Te and Mg x Hg 1-x Te alloys has been investigated for a delta-lattice parameter model. The phase diagrams obtained show the stability of Cd 1-x Hg x Te, Zn x Hg 1-x Te in the whole range of compositions, alongside with a miscibility gap for Mn x Hg 1-x Te being of 0.35 x Hg 1-x Te/CdTe and Mn x Hg 1-x Te/Cd 0.96 Zn 0.04 Te epitaxial films result in lowering critical temperatures and narrowing the miscibility gap [ru

Nuclear radiation detected optical pumping of neutron deficient Hg isotopes

International Nuclear Information System (INIS)

Bonn, J.

1975-01-01

The extension of the Nuclear Radiation Detected Optical Pumping method to mass-separated samples of isotopes far off stability is presented for a series of light Hg isotopes produced at the ISOLDE facility at CERN. The isotope under investigation is transferred by an automatic transfer system into the optical pumping apparatus. Zeeman scanning of an isotopically pure Hg spectral lamp is used to reach energetic coincidence with the hyperfine structure components of the 6s 2 1 S 0 -6s6p 3 P 1 (lambda = 2537 A) resonance line of the investigated isotope and the Hg lamp. The orientation build up by optical pumping is monitored via the asymmetry or anisotropy of the nuclear radiation. Nuclear spins, magnetic moments, electric quadrupole moments and isotopic shift are obtained for 181 Hg- 191 Hg using the β-asymmetry as detector. The extension of the method using the γ-anisotropy is discussed and measurements on 193 Hg are presented. (orig./HK)

The pattern of anthropogenic signal emergence in Greenland Ice Sheet surface mass balance

NARCIS (Netherlands)

Fyke, J.G.; Vizcaino, M.; Lipscomb, W.H.

2014-01-01

Surface mass balance (SMB) trends influence observed Greenland Ice Sheet (GrIS) mass loss, but the component of these trends related to anthropogenic forcing is unclear. Here we study the simulated spatial pattern of emergence of an anthropogenically derived GrIS SMB signal between 1850 and 2100

The mass and energy balance of ice within the Eisriesenwelt cave, Austria

Directory of Open Access Journals (Sweden)

F. Obleitner

2011-03-01

Full Text Available Meteorological measurements were performed in a prominent ice cave (Eisriesenwelt, Austria during a full annual cycle. The data show the basic features of a dynamically ventilated cave system with a well distinguished winter and summer regime.

The calculated energy balance of the cave ice is largely determined by the input of long-wave radiation originating at the host rock surface. On average the turbulent fluxes withdraw energy from the surface. This is more pronounced during winter due to enhanced circulation and lower humidity. During summer the driving gradients reverse sign and the associated fluxes provide energy for melt.

About 4 cm of ice were lost at the measurement site during a reference year. This was due to some sublimation during winter, while the major loss resulted from melt during summer. Small amounts of accumulation occurred during spring due to refreezing of seepage water.

These results are largely based on employing a numerical mass and energy balance model. Sensitivity studies prove reliability of the calculated energy balance regarding diverse measurement uncertainties and show that the annual mass balance of the ice strongly depends on cave air temperature during summer and the availability of seepage water in spring.

Virtual Reality-Based Center of Mass-Assisted Personalized Balance Training System

Directory of Open Access Journals (Sweden)

Deepesh Kumar

2018-01-01

Full Text Available Poststroke hemiplegic patients often show altered weight distribution with balance disorders, increasing their risk of fall. Conventional balance training, though powerful, suffers from scarcity of trained therapists, frequent visits to clinics to get therapy, one-on-one therapy sessions, and monotony of repetitive exercise tasks. Thus, technology-assisted balance rehabilitation can be an alternative solution. Here, we chose virtual reality as a technology-based platform to develop motivating balance tasks. This platform was augmented with off-the-shelf available sensors such as Nintendo Wii balance board and Kinect to estimate one’s center of mass (CoM. The virtual reality-based CoM-assisted balance tasks (Virtual CoMBaT was designed to be adaptive to one’s individualized weight-shifting capability quantified through CoM displacement. Participants were asked to interact with Virtual CoMBaT that offered tasks of varying challenge levels while adhering to ankle strategy for weight shifting. To facilitate the patients to use ankle strategy during weight-shifting, we designed a heel lift detection module. A usability study was carried out with 12 hemiplegic patients. Results indicate the potential of our system to contribute to improving one’s overall performance in balance-related tasks belonging to different difficulty levels.

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

Science.gov (United States)

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

2017-09-15

Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl 2 ) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl 2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl 2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl 2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl 2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl 2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden. Copyright © 2017 Elsevier Inc. All rights reserved.

Antarctic Ice-Sheet Mass Balance from Satellite Altimetry 1992 to 2001

Science.gov (United States)

Zwally, H. Jay; Brenner, Anita C.; Cornejo, Helen; Giovinetto, Mario; Saba, Jack L.; Yi, Donghui

2003-01-01

A major uncertainty in understanding the causes of the current rate of sea level rise is the potential contributions from mass imbalances of the Greenland and Antarctic ice sheets. Estimates of the current mass balance of the Antarctic ice sheet are derived from surface- elevation changes obtained from 9 years of ERS - 1 & 2 radar altimeter data. Elevation time-series are created from altimeter crossovers among 90-day data periods on a 50 km grid to 81.5 S. The time series are fit with a multivariate linear/sinusoidal function to give the average rate of elevation change (dH/dt). On the major Rome-Filchner, Ross, and Amery ice shelves, the W d t are small or near zero. In contrast, the ice shelves of the Antarctic Peninsula and along the West Antarctic coast appear to be thinning significantly, with a 23 +/- 3 cm per year surface elevation decrease on the Larsen ice shelf and a 65 +/- 4 cm per year decrease on the Dotson ice shelf. On the grounded ice, significant elevation decreases are obtained over most of the drainage basins of the Pine Island and Thwaites glaciers in West Antarctica and inland of Law Dome in East Antarctica. Significant elevation increases are observed within about 200 km of the coast around much of the rest of the ice sheet. Farther inland, the changes are a mixed pattern of increases and decreases with increases of a few centimeters per year at the highest elevations of the East Antarctic plateau. The derived elevation changes are combined with estimates of the bedrock uplift from several models to provide maps of ice thickness change. The ice thickness changes enable estimates of the ice mass balances for the major drainage basins, the overall mass balance, and the current contribution of the ice sheet to global sea level change.

Mass Balance of the West Antarctic Ice-Sheet from ICESat Measurements

Science.gov (United States)

Zwally, H. Jay; Li, Jun; Robins, John; Saba, Jack L.; Yi, Donghui

2011-01-01

Mass balance estimates for 2003-2008 are derived from ICESat laser altimetry and compared with estimates for 1992-2002 derived from ERS radar altimetry. The net mass balance of 3 drainage systems (Pine Island, Thwaites/Smith, and the coast of Marie Bryd) for 2003-2008 is a loss of 100 Gt/yr, which increased from a loss of 70 Gt/yr for the earlier period. The DS including the Bindschadler and MacAyeal ice streams draining into the Ross Ice Shelf has a mass gain of 11 Gt/yr for 2003-2008, compared to an earlier loss of 70 Gt/yr. The DS including the Whillans and Kamb ice streams has a mass gain of 12 Gt/yr, including a significant thickening on the upper part of the Kamb DS, compared to a earlier gain of 6 Gt/yr (includes interpolation for a large portion of the DS). The other two DS discharging into the Ronne Ice Shelf and the northern Ellsworth Coast have a mass gain of 39 Gt/yr, compared to a gain of 4 Gt/yr for the earlier period. Overall, the increased losses of 30 Gt/yr in the Pine Island, Thwaites/Smith, and the coast of Marie Bryd DSs are exceeded by increased gains of 59 Gt/yr in the other 4 DS. Overall, the mass loss from the West Antarctic ice sheet has decreased to 38 Gt/yr from the earlier loss of 67 Gt/yr, reducing the contribution to sea level rise to 0.11 mm/yr from 0.19 mm/yr

Elevation change and remote-sensing mass-balance methods on the Greenland ice sheet

DEFF Research Database (Denmark)

Ahlstrøm, Andreas P.; Reeh, Niels; Christensen, Erik Lintz

The mass balance of the Greenland Ice Sheet is virtually impossible to obtain with traditional ground-based methods alone due to its vast size. It is thus desirable to develop mass-balance methods depending on remote sensing instead and this field has experienced a dramatic development within...... of measured surface elevation change over a 50x50~km part of the western Greenland Ice-Sheet margin near Kangerlussuaq. In this region, the mean observed elevation change has been -0.5~m from 2000 to 2003. However, the change is unevenly distributed with the northern and central part generally in balance...... the last decade. Large amounts of data have been collected from satellite and airborne platforms, yielding surface elevation changes and surface velocity fields. Here we present data from the Greenland Ice-Sheet margin acquired with a new small-scale airborne system, designed for regional high...

Use of L-cysteine for minimization of inorganic Hg loss during thermal neutron irradiation

International Nuclear Information System (INIS)

Anderson, D.L.

2009-01-01

Thermal neutron irradiation experiments performed with cellulose-based L-cysteine-treated and untreated Hg standards showed Hg losses of 59-81% for untreated standards but only about a 0.2% loss for treated standards. These results and others for multielement standards showed that Hg loss is highly dependent on total mass and placement of materials in the irradiation vessel and that distribution of volatilized Hg was fairly uniform throughout the sample-containing region of the vessel. Polyethylene trapped volatile Hg much more efficiently than cellulose and a multielement standard containing inorganic Se selectively trapped Hg lost from a co-irradiated multielement standard containing Hg. (author)

Evaluation of a mass-balance approach to determine consumptive water use in northeastern Illinois

Science.gov (United States)

Mills, Patrick C.; Duncker, James J.; Over, Thomas M.; Marian Domanski,; ,; Engel, Frank

2014-01-01

A principal component of evaluating and managing water use is consumptive use. This is the portion of water withdrawn for a particular use, such as residential, which is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. The amount of consumptive use may be estimated by a water (mass)-balance approach; however, because of the difficulty of obtaining necessary data, its application typically is restricted to the facility scale. The general governing mass-balance equation is: Consumptive use = Water supplied - Return flows.

Evaluating Greenland glacial isostatic adjustment corrections using GRACE, altimetry and surface mass balance data

International Nuclear Information System (INIS)

Sutterley, Tyler C; Velicogna, Isabella; Csatho, Beata; Rezvan-Behbahani, Soroush; Babonis, Greg; Van den Broeke, Michiel

2014-01-01

Glacial isostatic adjustment (GIA) represents a source of uncertainty for ice sheet mass balance estimates from the Gravity Recovery and Climate Experiment (GRACE) time-variable gravity measurements. We evaluate Greenland GIA corrections from Simpson et al (2009 Quat. Sci. Rev. 28 1631–57), A et al (2013 Geophys. J. Int. 192 557–72) and Wu et al (2010 Nature Geosci. 3 642–6) by comparing the spatial patterns of GRACE-derived ice mass trends calculated using the three corrections with volume changes from ICESat (Ice, Cloud, and land Elevation Satellite) and OIB (Operation IceBridge) altimetry missions, and surface mass balance products from the Regional Atmospheric Climate Model (RACMO). During the period September 2003–August 2011, GRACE ice mass changes obtained using the Simpson et al (2009 Quat. Sci. Rev. 28 1631–57) and A et al (2013 Geophys. J. Int. 192 557–72) GIA corrections yield similar spatial patterns and amplitudes, and are consistent with altimetry observations and surface mass balance data. The two GRACE estimates agree within 2% on average over the entire ice sheet, and better than 15% in four subdivisions of Greenland. The third GRACE estimate corrected using the (Wu et al 2010 Nature Geosci. 3 642–6)) GIA shows similar spatial patterns, but produces an average ice mass loss for the entire ice sheet that is 64 − 67 Gt yr −1 smaller. In the Northeast the recovered ice mass change is 46–49 Gt yr −1 (245–270%) more positive than that deduced from the other two corrections. By comparing the spatial and temporal variability of the GRACE estimates with trends of volume changes from altimetry and surface mass balance from RACMO, we show that the Wu et al (2010 Nature Geosci. 3 642–6) correction leads to a large mass increase in the Northeast that is inconsistent with independent observations. (paper)

Energy and Mass Balance At Gran Campo Nevado, Patagonia, Chile

Science.gov (United States)

Schneider, C.; Kilian, R.; Casassa, G.

The Gran Campo Nevado (GCN) Ice Cap on Peninsula Muñoz Gamero, Chile, is lo- cated in the southernmost part of the Patagonian Andes at 53S. It comprises an ice cap and numerous outlet glaciers which mostly end in proglacial lakes at sea level. The total ice covered area sums up to approximately 250 km2. GCN forms the only major ice body between the Southern Patagonian Icefield and the Street of Magallan. Its almost unique location in the zone of the all-year westerlies makes it a region of key interest in terms of glacier and climate change studies of the westwind zone of the Southern Hemisphere. Mean annual temperature of approximately +5C at sea level and high precipitation of about 8.000 mm per year lead to an extreme turn-over of ice mass from the accumulation area of the GCN Ice Cap to the ablation areas of the outlet glaciers. Since October 1999 an automated weather station (AWS) is run continuously in the area at Bahia Bahamondes for monitoring climate parameters. From February to April 2000 an additional AWS was operated on Glaciar Lengua a small outlet glacier of GCN to the north-west. Ablation has been measured at stakes during the same pe- riod. The aim of this study, was to obtain point energy and mass balance on Glaciar Lengua. The work was conducted as part of the international and interdisciplinary working group SGran Campo NevadoT and supported by the German Research Foun- & cedil;dation (DFG). Energy balance was calculated using the bulk approach formulas and calibrated to the measured ablation. It turns out, that sensible heat transfer is the major contribution to the energy balance. Since high cloud cover rates prevail, air tempera- ture is the key factor for the energy balance of the glacier. Despite high rain fall rates, energy input from rain fall is of only minor importance to the overall energy balance. From the energy balance computed, it was possible to derive summer-time degree-day factors for Glaciar Lengua. With data from the nearby

199Hg Moessbauer measurements on mercury, alloys and Hg-fluorides

International Nuclear Information System (INIS)

Wurtinger, W.; Kankeleit, E.

1979-01-01

The Moessbauer effect on the 158 keV 5/2 - -1/2 - transition in 199 Hg, of the order of 10 ppm, has been studied using the current integration technique. The isomer shift between the Hg(I)- and Hg(II)-fluorides as well as the quadrupole splitting in Hg 2 Pt and Hg 2 F 2 are interpreted in terms of relativistic Hartree-Fock-Slater and Molecular Orbital calculations. The following nuclear parameters could be derived: Δ[r 2 ] = (3.2+-1.1) 10 -3 fm 2 and Q(5/2 - ) = (-0.8+-0.4)b. Evidence for an oblate triaxially deformed 199 Hg nucleus is derived from particle plus rotor calculations. (orig.)

Search for entrance-channel dependence in the population of superdeformed bands in {sup 191}Hg

Energy Technology Data Exchange (ETDEWEB)

Soramel, F.; Khoo, T.L.; Janssens, R.V.F. [and others

1995-08-01

The population intensity of some SD bands in the mass 150 region were observed to depend on the mass symmetry of the entrance channel in the fusion reaction. The authors raised the possibility that the population of SD bands had a memory of the entrance channel. To check this interesting possibility, we made measurements of the population intensities of superdeformed (SD) bands in the {sup 160}Gd({sup 36}S,5n){sup 191}Hg and {sup 130}Te({sup 64}Ni,3n){sup 191}Hg reactions. To ensure that any observed effect was not due to a simple angular momentum difference in the entrance channels, we also measured the average entry points and spin distributions of normal and SD states in {sup 191}Hg in the two reactions. The entry points and spin distributions for {sup 191}Hg are the same and, indeed, so are the SD intensities in the two reactions. Hence, no entrance-channel effect is observed in the population of the SD band in {sup 191}Hg, in contrast with data for SD bands in the mass 150 regions. We suggest that the effect observed previously in the mass 150 region is due to an angular momentum effect. A letter reporting our results was submitted for publication.

The Mass Balance of Glacier No. 1 at the Headwaters of the Urumqi River in Relation to Northern Hemisphere Teleconnection Patterns

Directory of Open Access Journals (Sweden)

Feifei Yuan

2016-03-01

Full Text Available Most small glaciers in the world have significantly decreased their volume during the last century, which has caused water shortage problems. Glacier No. 1, at the headwaters of the Urumqi River, Tianshan, China, has been monitored since 1959 and similarly has experienced significant mass and volume losses over the last few decades. Thus, we examined the trend and potential abrupt changes of the mass balance of Glacier No. 1. Principal component analysis and singular value decomposition were used to find significant relations between the mass balance of Glacier No. 1 and Northern Hemisphere teleconnection patterns using climate indices. It was found that the mass balance of Glacier No. 1 had a significantly decreasing trend corresponding to −14.5 mm/year from 1959 to 2010. A change point was detected in 1997 with 99% confidence level. Two time periods with different mass balances were identified as 1959–1996 and 1997–2010. The mass balance for the first period was −136.4 mm/year and up to −663.9 mm/year for the second period. The mass balance of Glacier No. 1 is positively related to the Scandinavian Pattern (SCA, and negatively related to the East Atlantic Pattern (EA. These relationships are useful in better understanding the interaction between glacier mass balance and climate variability.

Determination of Cd, Cr, Hg and Pb in plastics from waste electrical and electronic equipment by inductively coupled plasma mass spectrometry with collision-reaction interface technology.

Science.gov (United States)

Santos, Mirian C; Nóbrega, Joaquim A; Cadore, Solange

2011-06-15

A procedure based on the use of a quadrupole inductively coupled plasma-mass spectrometer equipped with a collision-reaction interface (CRI) for control of spectral overlap interferences was developed for simultaneous determination of Cd, Cr, Hg, and Pb in plastics from waste electrical and electronic equipment (WEEE). The injection of H(2) and He (80 and 60 mL min(-1), respectively) into the sampled plasma, colliding and reacting with potentially interfering polyatomic ions, allows interference-free determination of chromium via its isotopes (52)Cr and (53)Cr that are freed from overlap due to the occurrence of (40)Ar(12)C(+), (40)Ar(12)C(1)H(+), (36)S(16)O(+) or (1)H(36)S(16)O(+). Cadmium, Hg and Pb were directly determined via their isotopes (110)Cd, (111)Cd, (112)Cd, (199)Hg, (200)Hg, (201)Hg, (202)Hg, (206)Pb, (207)Pb, and (208)Pb, without using CRI. The CRI can be quickly activated or deactivated before each analyte measurement. Limits of detection for (52)Cr were 0.04 or 0.14 μg L(-1) with He or H(2) injected in CRI. Cadmium and Pb have LODs between 0.02 and 0.08 μg L(-1) and Hg had 0.93-0.98 μg L(-1), without using CRI. Analyte concentrations for samples varied from 16 to 43, 1 to 11, 4 to 12, and 5 to 13 mg kg(-1) for Cr, Cd, Hg and Pb, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Monitoring glacier albedo as a proxy to derive summer and annual surface mass balances from optical remote-sensing data

Science.gov (United States)

Davaze, Lucas; Rabatel, Antoine; Arnaud, Yves; Sirguey, Pascal; Six, Delphine; Letreguilly, Anne; Dumont, Marie

2018-01-01

Less than 0.25 % of the 250 000 glaciers inventoried in the Randolph Glacier Inventory (RGI V.5) are currently monitored with in situ measurements of surface mass balance. Increasing this archive is very challenging, especially using time-consuming methods based on in situ measurements, and complementary methods are required to quantify the surface mass balance of unmonitored glaciers. The current study relies on the so-called albedo method, based on the analysis of albedo maps retrieved from optical satellite imagery acquired since 2000 by the MODIS sensor, on board the TERRA satellite. Recent studies revealed substantial relationships between summer minimum glacier-wide surface albedo and annual surface mass balance, because this minimum surface albedo is directly related to the accumulation-area ratio and the equilibrium-line altitude. On the basis of 30 glaciers located in the French Alps where annual surface mass balance data are available, our study conducted on the period 2000-2015 confirms the robustness and reliability of the relationship between the summer minimum surface albedo and the annual surface mass balance. For the ablation season, the integrated summer surface albedo is significantly correlated with the summer surface mass balance of the six glaciers seasonally monitored. These results are promising to monitor both annual and summer glacier-wide surface mass balances of individual glaciers at a regional scale using optical satellite images. A sensitivity study on the computed cloud masks revealed a high confidence in the retrieved albedo maps, restricting the number of omission errors. Albedo retrieval artifacts have been detected for topographically incised glaciers, highlighting limitations in the shadow correction algorithm, although inter-annual comparisons are not affected by systematic errors.

Applying an orographic precipitation model to improve mass balance modeling of the Juneau Icefield, AK

Science.gov (United States)

Roth, A. C.; Hock, R.; Schuler, T.; Bieniek, P.; Aschwanden, A.

2017-12-01

Mass loss from glaciers in Southeast Alaska is expected to alter downstream ecological systems as runoff patterns change. To investigate these potential changes under future climate scenarios, distributed glacier mass balance modeling is required. However, the spatial resolution gap between global or regional climate models and the requirements for glacier mass balance modeling studies must be addressed first. We have used a linear theory of orographic precipitation model to downscale precipitation from both the Weather Research and Forecasting (WRF) model and ERA-Interim to the Juneau Icefield region over the period 1979-2013. This implementation of the LT model is a unique parameterization that relies on the specification of snow fall speed and rain fall speed as tuning parameters to calculate the cloud time delay, τ. We assessed the LT model results by considering winter precipitation so the effect of melt was minimized. The downscaled precipitation pattern produced by the LT model captures the orographic precipitation pattern absent from the coarse resolution WRF and ERA-Interim precipitation fields. Observational data constraints limited our ability to determine a unique parameter combination and calibrate the LT model to glaciological observations. We established a reference run of parameter values based on literature and performed a sensitivity analysis of the LT model parameters, horizontal resolution, and climate input data on the average winter precipitation. The results of the reference run showed reasonable agreement with the available glaciological measurements. The precipitation pattern produced by the LT model was consistent regardless of parameter combination, horizontal resolution, and climate input data, but the precipitation amount varied strongly with these factors. Due to the consistency of the winter precipitation pattern and the uncertainty in precipitation amount, we suggest a precipitation index map approach to be used in combination with

Comparison of surface mass balance of ice sheets simulated by positive-degree-day method and energy balance approach

Directory of Open Access Journals (Sweden)

E. Bauer

2017-07-01

Full Text Available Glacial cycles of the late Quaternary are controlled by the asymmetrically varying mass balance of continental ice sheets in the Northern Hemisphere. Surface mass balance is governed by processes of ablation and accumulation. Here two ablation schemes, the positive-degree-day (PDD method and the surface energy balance (SEB approach, are compared in transient simulations of the last glacial cycle with the Earth system model of intermediate complexity CLIMBER-2. The standard version of the CLIMBER-2 model incorporates the SEB approach and simulates ice volume variations in reasonable agreement with paleoclimate reconstructions during the entire last glacial cycle. Using results from the standard CLIMBER-2 model version, we simulated ablation with the PDD method in offline mode by applying different combinations of three empirical parameters of the PDD scheme. We found that none of the parameter combinations allow us to simulate a surface mass balance of the American and European ice sheets that is similar to that obtained with the standard SEB method. The use of constant values for the empirical PDD parameters led either to too much ablation during the first phase of the last glacial cycle or too little ablation during the final phase. We then substituted the standard SEB scheme in CLIMBER-2 with the PDD scheme and performed a suite of fully interactive (online simulations of the last glacial cycle with different combinations of PDD parameters. The results of these simulations confirmed the results of the offline simulations: no combination of PDD parameters realistically simulates the evolution of the ice sheets during the entire glacial cycle. The use of constant parameter values in the online simulations leads either to a buildup of too much ice volume at the end of glacial cycle or too little ice volume at the beginning. Even when the model correctly simulates global ice volume at the last glacial maximum (21 ka, it is unable to simulate

Mass, energy and material balances of SRF production process. Part 2: SRF produced from construction and demolition waste.

Science.gov (United States)

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2014-11-01

In this work, the fraction of construction and demolition waste (C&D waste) complicated and economically not feasible to sort out for recycling purposes is used to produce solid recovered fuel (SRF) through mechanical treatment (MT). The paper presents the mass, energy and material balances of this SRF production process. All the process streams (input and output) produced in MT waste sorting plant to produce SRF from C&D waste are sampled and treated according to CEN standard methods for SRF. Proximate and ultimate analysis of these streams is performed and their composition is determined. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. By mass balance means the overall mass flow of input waste material stream in the various output streams and material balances mean the mass flow of components of input waste material stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. The results from mass balance of SRF production process showed that of the total input C&D waste material to MT waste sorting plant, 44% was recovered in the form of SRF, 5% as ferrous metal, 1% as non-ferrous metal, and 28% was sorted out as fine fraction, 18% as reject material and 4% as heavy fraction. The energy balance of this SRF production process showed that of the total input energy content of C&D waste material to MT waste sorting plant, 74% was recovered in the form of SRF, 16% belonged to the reject material and rest 10% belonged to the streams of fine fraction and heavy fraction. From the material balances of this process, mass fractions of plastic (soft), paper and cardboard, wood and plastic (hard) recovered in the SRF stream were 84%, 82%, 72% and 68% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC) and rubber material was found in the reject material

Mass, energy and material balances of SRF production process. Part 1: SRF produced from commercial and industrial waste.

Science.gov (United States)

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2014-08-01

This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442 and EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non

Future climate warming increases Greenland ice sheet surface mass balance variability

NARCIS (Netherlands)

Fyke, J.G.; Vizcaino, M.; Lipscomb, W.; Price, S.

2014-01-01

The integrated surface mass balance (SMB) of the Greenland ice sheet (GrIS) has large interannual variability. Long-term future changes to this variability will affect GrIS dynamics, freshwater fluxes, regional oceanography, and detection of changes in ice volume trends. Here we analyze a simulated

21st century changes in the surface mass balance of the Greenland ice sheet simulated with the global model CESM

Science.gov (United States)

Vizcaíno, M.; Lipscomb, W. H.; Van den Broeke, M.

2012-04-01

We present here the first projections of 21st century surface mass balance change of the Greenland ice sheet simulated with the Community Earth System Model (CESM). CESM is a fully-coupled, global climate model developed at many research centers and universities, primarily in the U.S. The model calculates the surface mass balance in the land component (the Community Land Model, CLM), at the same resolution as the atmosphere (1 degree), with an energy-balance scheme. The snow physics included in CLM for non-glaciated surfaces (SNiCAR model, Flanner and Zender, 2005) are used over the ice sheet. The surface mass balance is calculated for 10 elevation classes, and then downscaled to the grid of the ice sheet model (5 km in this case) via vertical linear interpolation between elevation classes combined with horizontal bilinear interpolation. The ice sheet topography is fixed at present-day values for the simulations presented here. The use of elevation classes reduces computational costs while giving results that reproduce well the mass balance gradients at the steep margins of the ice sheet. The simulated present-day surface mass balance agrees well with results from regional models. We focus on the regional model RACMO (Ettema et al. 2009) to compare the results on 20th-century surface mass balance evolution and two-dimensional patterns. The surface mass balance of the ice sheet under RCP8.5. forcing becomes negative in the last decades of the 21st century. The equilibrium line becomes ~500 m higher on average. Accumulation changes are positive in the accumulation zone. We examine changes in refreezing, accumulation, albedo, surface fluxes, and the timing of the melt season.

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

Science.gov (United States)

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

2014-08-05

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

Past and future sea-level change from the surface mass balance of glaciers

Directory of Open Access Journals (Sweden)

B. Marzeion

2012-11-01

Full Text Available We present estimates of sea-level change caused by the global surface mass balance of glaciers, based on the reconstruction and projection of the surface mass balance of all the individual glaciers of the world, excluding the ice sheets in Greenland and Antarctica. The model is validated using a leave-one-glacier-out cross-validation scheme against 3997 observed surface mass balances of 255 glaciers, and against 756 geodetically observed, temporally integrated volume and surface area changes of 341 glaciers. When forced with observed monthly precipitation and temperature data, the glaciers of the world are reconstructed to have lost mass corresponding to 114 ± 5 mm sea-level equivalent (SLE between 1902 and 2009. Using projected temperature and precipitation anomalies from 15 coupled general circulation models from the Coupled Model Intercomparison Project phase 5 (CMIP5 ensemble, they are projected to lose an additional 148 ± 35 mm SLE (scenario RCP26, 166 ± 42 mm SLE (scenario RCP45, 175 ± 40 mm SLE (scenario RCP60, or 217 ± 47 mm SLE (scenario RCP85 during the 21st century. Based on the extended RCP scenarios, glaciers are projected to approach a new equilibrium towards the end of the 23rd century, after having lost either 248 ± 66 mm SLE (scenario RCP26, 313 ± 50 mm SLE (scenario RCP45, or 424 ± 46 mm SLE (scenario RCP85. Up until approximately 2100, ensemble uncertainty within each scenario is the biggest source of uncertainty for the future glacier mass loss; after that, the difference between the scenarios takes over as the biggest source of uncertainty. Ice mass loss rates are projected to peak 2040 ∼ 2050 (RCP26, 2050 ∼ 2060 (RCP45, 2070 ∼ 2090 (RCP60, or 2070 ∼ 2100 (RCP85.

Studies of the 198Hg(d,d') and 198Hg(d,p) reactions

Science.gov (United States)

Diaz Varela, Alejandra; Garrett, P. E.; Rand, E. T.; Ball, G. C.; Bilstein, V.; Laffoley, A. T.; Maclean, A. D.; Svensson, C. E.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

2017-09-01

Limits on the electric dipole moment (EDM) continue to decrease for 199Hg, the most stringent upper limit for a nuclear EDM to date. The experimental limit on the observed atomic EDM for 199Hg is converted to a limit on the nuclear EDM via a calculation of the Schiff moment, requiring knowledge of the nuclear structure of 199Hg. The E 3 and E 1 strength distributions to the ground state of 199Hg, and E 2 transitions amongst excited states, would be ideal information to further constrain 199Hg Schiff moment theoretical models. The high level density of 199Hg makes those determinations challenging, however the similar information can be obtained from exploring surrounding even-even Hg isotopes. As part of a campaign to study the Hg isotopes near 199Hg, two experiments, 198Hg(d,d') 198Hg and 198Hg(d,p)199Hg reaction were performed using the Q3D spectrograph at the Maier-Leibnitz Laboratory (MLL) at Garching, Germany. A 22 MeV deuterium beam was used to impinge a 198Hg32S target. The (d,d') reaction allows us to probe the desired E 2 and E 3 matrix elements, while the (d,p) reaction provides information on the neutron single-particle states of 199Hg.

Design of a peptidic turn with high affinity for HgII

DEFF Research Database (Denmark)

Pires, Sara; Habjanic, Jelena; Sezer, Murat

2012-01-01

A four amino acid peptide containing the ß-turn template dPro-Pro in the middle and two cysteines (Cys) in the terminal positions (CdPPC) has been synthesized and its mercury(II) coordination properties studied using different spectroscopic methods. The UV-vis, CD, (199m)Hg PAC, and Raman...... spectroscopic studies indicate the binding of Hg(II) to the two Cys, forming the dithiolatemercury(II) complex Hg(CdPPC). Electrospray ionization mass spectrometry corroborates the 1:1 complex formation. A log K = 40.0 was determined for the formation constant of the Hg(CdPPC) complex using competition...... potentiometric studies. Replacement of the dPro-Pro motif by a Pro-Pro unit generated a peptide (CPPC) capable of forming a similar species [Hg(CPPC)] but showing a lower affinity for Hg(II) (at least 3-3.5 orders of magnitude lower). The introduction of the dPro-Pro motif is crucial to induce the folding...

Spent Nuclear Fuel (SNF) Project Multi Canister Overpack (MCO) Process Flow Diagram Mass Balance Calculations

International Nuclear Information System (INIS)

KLEM, M.J.

2000-01-01

The purpose of this calculation document is to develop the bases for the material balances of the Multi-Canister Overpack (MCO) Level 1 Process Flow Diagram (PFD). The attached mass balances support revision two of the PFD for the MCO and provide future reference

Identifying Key Proteins in Hg Methylation Pathways of Desulfovibrio by Global Proteomics, Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Summers, Anne O. [Univ. of Georgia, Athens, GA (United States). Dept. of Microbiology; Miller, Susan M. [Univ. of California, San Francisco, CA (United States). Dept. of Pharmaceutical Chemistry; Wall, Judy [Univ. of Missouri, Columbia, MO (United States). Dept. of Biochemistry; Lipton, Mary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-06-18

Elemental mercury, Hg(0) is a contaminant at many DOE sites, especially at Oak Ridge National Laboratory (ORNL) where the spread of spilled Hg and its effects on microbial populations have been monitored for decades. To explore the microbial interactions with Hg, we have devised a global proteomic approach capable of directly detecting Hg-adducts of proteins. This technique developed in the facultative anaerobe, Escherichia coli, allows us to identify the proteins most vulnerable to acute exposure to organomercurials phenyl- and ethyl-mercury (as surrogates for the highly neurotoxic methyl-Hg) (Polacco, et al, 2011). We have found >300 such proteins in all metabolic functional groups and cellular compartments; most are highly conserved and can serve as markers for acute Hg exposure (Zink, et al. 2016, in preparation). We have also discovered that acute Hg exposure severely disrupts thiol, iron and redox homeostases, and electrolyte balance (LaVoie, et al., 2015) Thus, we proposed to bring these techniques to bear on the central problem of identifying the cellular proteins involved in bacterial uptake and methylation of mercury and its release from the cell.

46 CFR 53.12-1 - General (modifies HG-600 through HG-640).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false General (modifies HG-600 through HG-640). 53.12-1... HEATING BOILERS Instruments, Fittings, and Controls (Article 6) § 53.12-1 General (modifies HG-600 through HG-640). (a) The instruments, fittings and controls for heating boilers shall be as indicated in HG...

Development of the ECLSS Sizing Analysis Tool and ARS Mass Balance Model Using Microsoft Excel

Science.gov (United States)

McGlothlin, E. P.; Yeh, H. Y.; Lin, C. H.

1999-01-01

The development of a Microsoft Excel-compatible Environmental Control and Life Support System (ECLSS) sizing analysis "tool" for conceptual design of Mars human exploration missions makes it possible for a user to choose a certain technology in the corresponding subsystem. This tool estimates the mass, volume, and power requirements of every technology in a subsystem and the system as a whole. Furthermore, to verify that a design sized by the ECLSS Sizing Tool meets the mission requirements and integrates properly, mass balance models that solve for component throughputs of such ECLSS systems as the Water Recovery System (WRS) and Air Revitalization System (ARS) must be developed. The ARS Mass Balance Model will be discussed in this paper.

Simulation and reconstruction of parameters of streamflow and glacier mass balance in the Northern Caucasus

Directory of Open Access Journals (Sweden)

V. G. Konovalov

2014-01-01

Full Text Available The work was aimed at numerical modeling of spatial-temporal variability of the river Terek seasonal (April to September streamflow characteristics and long-term fluctuations of components of annual glacier mass balances in this basin and on the adjacent territories. Mass balance of glaciers Djankuat and Garabashi was calculated. Simulation was performed by means of stochastic modeling and discrete data presenting fields of main meteorological parameters (precipitation, air temperature and humidity having effect on the streamflow. Realization of this approach is complicated by the fact that spatial representativeness of hydrological and meteorological sites are not corresponding one to another. Data on the runoff is clearly related to the total drainage area closed by a gauging station. And for this data we study a relationship with meteorological parameters which are measured at a non-regular observational network whose spatial representativeness is unknown. These stations are generally located beyond the area under investigation (Fig. 2. Similar problem exists when we analyze a relationship between components of the mass balance of individual glaciers (Djankuat and Garabashi and the above climate characteristics measured at some stations located on the whole Caucasus territory. The same takes place when long-term indices of width and density of tree annual rings obtained in upper reaches of the river Kuban’ are used for analysis of variations of the runoff and the glacier mass balance in the river Terek basin located at a distance of 100-150 km from the Kuban’ dendrologic sites.To solve the problem we used a wide number of factors which directly (various information about the climate or indirectly (indices of the climate dryness, wood ring characteristics characterize conditions of formation of annual and seasonal river runoff and components of glacier mass balance in the North Caucasus. Use of all obtained information made possible the

Glacier albedo decrease in the European Alps: potential causes and links with mass balances

Science.gov (United States)

Di Mauro, Biagio; Julitta, Tommaso; Colombo, Roberto

2016-04-01

Both mountain glaciers and polar ice sheets are losing mass all over the Earth. They are highly sensitive to climate variation, and the widespread reduction of glaciers has been ascribed to the atmospheric temperature increase. Beside this driver, also ice albedo plays a fundamental role in defining mass balance of glaciers. In fact, dark ice absorbs more energy causing faster glacier melting, and this can drive to more negative balances. Previous studies showed that the albedo of Himalayan glaciers and the Greenland Ice Sheet is decreasing with important rates. In this contribution, we tested the hypothesis that also glaciers in the European Alps are getting darker. We analyzed 16-year time series of MODIS (MODerate resolution Imaging Spectrometer) snow albedo from Terra (MOD13A1, 2000-2015) and Aqua (MYD13A1, 2002-2015) satellites. These data feature a spatial resolution of 500m and a daily temporal resolution. We evaluated the existence of a negative linear and nonlinear trend of the summer albedo values both at pixel and at glacier level. We also calculated the correlation between MODIS summer albedo and glacier mass balances (from the World Glaciological Monitoring Service, WGMS database), for all the glaciers with available mass balance during the considered period. In order to estimate the percentage of the summer albedo that can be explained by atmospheric temperature, we correlated MODIS albedo and monthly air temperature extracted from the ERA-Interim reanalysis dataset. Results show that decreasing trends exist with a strong spatial variability in the whole Alpine chain. In large glaciers, such as the Aletch (Swiss Alps), the trend varies significantly also within the glacier, showing that the trend is higher in the area across the accumulation and ablation zone. Over the 17 glaciers with mass balance available in the WGMS data set, 11 gave significant relationship with the MODIS summer albedo. Moreover, the comparison between ERA-Interim temperature

Mass balance of the Greenland ice sheet - a study of ICESat data, surface density and firn compaction modelling

DEFF Research Database (Denmark)

Sørensen, L. S.; Simonsen, Sebastian Bjerregaard; Nielsen, K.

2010-01-01

ICESat has provided surface elevation measurements of the ice sheets since the launch in January 2003, resulting in a unique data set for monitoring the changes of the cryosphere. Here we present a novel method for determining the mass balance of the Greenland ice sheet derived from ICESat...... in estimating the mass balance of the Greenland ice sheet. We find firn dynamics and surface densities to be important factors in deriving the mass loss from remote sensing altimetry. The volume change derived from ICESat data is corrected for firn compaction, vertical bedrock movement and an intercampaign...... boundary conditions. We find an annual mass loss of the Greenland ice sheet of 210 ± 21 Gt yr-1 in the period from October 2003 to March 2008. This result is in good agreement with other studies of the Greenland ice sheet mass balance, based on different remote sensing techniques....

Quadrupole moments of the 12+ isomers in 188Hg and 190Hg

International Nuclear Information System (INIS)

Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.

1984-01-01

The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)

Tracing aquatic bioavailable Hg in three different regions of China using fish Hg isotopes.

Science.gov (United States)

Liu, Cheng-Bin; Hua, Xiu-Bing; Liu, Hong-Wei; Yu, Ben; Mao, Yu-Xiang; Wang, Ding-Yong; Yin, Yong-Guang; Hu, Li-Gang; Shi, Jian-Bo; Jiang, Gui-Bin

2018-04-15

To trace the most concerned bioavailable mercury (Hg) in aquatic environment, fish samples were collected from three typical regions in China, including 3 rivers and 1 lake in the Tibetan Plateau (TP, a high altitude background region with strong solar radiation), the Three Gorges Reservoir (TGR, the largest artificial freshwater reservoir in China), and the Chinese Bohai Sea (CBS, a heavily human-impacted semi-enclosed sea). The Hg isotopic compositions in fish muscles were analyzed. The results showed that anthropogenic emissions were the main sources of Hg in fish from TGR and CBS because of the observed negative δ 202 Hg and positive Δ 199 Hg in these two regions (TGR, δ 202 Hg: - 0.72 to - 0.29‰, Δ 199 Hg: 0.15 - 0.52‰; CBS, δ 202 Hg: - 2.09 to - 0.86‰, Δ 199 Hg: 0.07 - 0.52‰). The relatively higher δ 202 Hg and Δ 199 Hg (δ 202 Hg: - 0.37 - 0.08‰, Δ 199 Hg: 0.50 - 1.89‰) in fish from TP suggested the insignificant disturbance from local anthropogenic activities. The larger slopes of Δ 199 Hg/Δ 201 Hg in fish from TGR (1.29 ± 0.14, 1SD) and TP (1.25 ± 0.06, 1SD) indicated methylmercury (MeHg) was produced and photo-reduced in the water column before incorporation into the fish. In contrast, the photoreduction of Hg 2+ was the main process in CBS (slope of Δ 199 Hg/Δ 201 Hg: 1.06 ± 0.06, 1SD). According to the fingerprint data of Hg isotopes, the most important source for aquatic bioavailable Hg in TP should be the long-range transported Hg, contrasting to the anthropogenic originated MeHg from surface sediments and runoffs in TGR and inorganic Hg from continental inputs in CBS. Therefore, the isotopic signatures of Hg in fish can provide novel clues in tracing sources and behaviors of bioavailable Hg in aquatic systems, which are critical for further understanding the biogeochemical cycling of Hg. Copyright © 2017 Elsevier Inc. All rights reserved.

Elevation Change, Mass Balance, Dynamics, and Surging of Langjökull, Iceland from 1997 to 2007

OpenAIRE

Pope, Allen; Willis, Ian Craig; Pálsson, Finnur; Arnold, Neil Stuart; Rees, William Gareth; Björnsson, Helgi; Grey, Lauren

2016-01-01

Glaciers and ice caps around the world are changing quickly, with surge-type behaviour superimposed upon climatic forcing. Here, we study Iceland’s second largest ice cap, Langjökull, which has both surge- and non-surge-type outlets. By differencing elevation change with surface mass balance, we estimate the contribution of ice dynamics to elevation change. We use DEMs, in situ stake measurements, regional reanalyses, and a mass balance model to calculate the vertical ice velocity. Thus,...

Large-scale subduction of continental crust implied by India-Asia mass-balance calculation

Science.gov (United States)

Ingalls, Miquela; Rowley, David B.; Currie, Brian; Colman, Albert S.

2016-11-01

Continental crust is buoyant compared with its oceanic counterpart and resists subduction into the mantle. When two continents collide, the mass balance for the continental crust is therefore assumed to be maintained. Here we use estimates of pre-collisional crustal thickness and convergence history derived from plate kinematic models to calculate the crustal mass balance in the India-Asia collisional system. Using the current best estimates for the timing of the diachronous onset of collision between India and Eurasia, we find that about 50% of the pre-collisional continental crustal mass cannot be accounted for in the crustal reservoir preserved at Earth's surface today--represented by the mass preserved in the thickened crust that makes up the Himalaya, Tibet and much of adjacent Asia, as well as southeast Asian tectonic escape and exported eroded sediments. This implies large-scale subduction of continental crust during the collision, with a mass equivalent to about 15% of the total oceanic crustal subduction flux since 56 million years ago. We suggest that similar contamination of the mantle by direct input of radiogenic continental crustal materials during past continent-continent collisions is reflected in some ocean crust and ocean island basalt geochemistry. The subduction of continental crust may therefore contribute significantly to the evolution of mantle geochemistry.

Glacier mass balance in high-arctic areas with anomalous gravity

Science.gov (United States)

Sharov, A.; Rieser, D.; Nikolskiy, D.

2012-04-01

All known glaciological models describing the evolution of Arctic land- and sea-ice masses in changing climate treat the Earth's gravity as horizontally constant, but it isn't. In the High Arctic, the strength of the gravitational field varies considerably across even short distances under the influence of a density gradient, and the magnitude of free air gravity anomalies attains 100 mGal and more. On long-term base, instantaneous deviations of gravity can have a noticeable effect on the regime and mass budget of glaciological objects. At best, the gravity-induced component of ice mass variations can be determined on topographically smooth, open and steady surfaces, like those of arctic planes, regular ice caps and landfast sea ice. The present research is devoted to studying gravity-driven impacts on glacier mass balance in the outer periphery of four Eurasian shelf seas with a very cold, dry climate and rather episodic character of winter precipitation. As main study objects we had chosen a dozen Russia's northernmost insular ice caps, tens to hundreds of square kilometres in extent, situated in a close vicinity of strong gravity anomalies and surrounded with extensive fields of fast and/or drift ice for most of the year. The supposition about gravitational forcing on glacioclimatic settings in the study region is based on the results of quantitative comparison and joint interpretation of existing glacier change maps and available data on the Arctic gravity field and solid precipitation. The overall mapping of medium-term (from decadal to half-centennial) changes in glacier volumes and quantification of mass balance characteristics in the study region was performed by comparing reference elevation models of study glaciers derived from Russian topographic maps 1:200,000 (CI = 20 or 40 m) representing the glacier state as in the 1950s-1980s with modern elevation data obtained from satellite radar interferometry and lidar altimetry. Free-air gravity anomalies were

Mass and element balance in food waste composting facilities.

Science.gov (United States)

Zhang, Huijun; Matsuto, Toshihiko

2010-01-01

The mass and element balance in municipal solid waste composting facilities that handle food waste was studied. Material samples from the facilities were analyzed for moisture, ash, carbon, nitrogen, and the oxygen consumption of compost and bulking material was determined. Three different processes were used in the food waste composting facilities: standard in-vessel composting, drying, and stand-alone composting machine. Satisfactory results were obtained for the input/output ash balance despite several assumptions made concerning the quantities involved. The carbon/nitrogen ratio and oxygen consumption values for compost derived only from food waste were estimated by excluding the contribution of the bulking material remaining in the compost product. These estimates seemed to be suitable indices for the biological stability of compost because there was a good correlation between them, and because the values seemed logical given the operating conditions at the facilities. 2010 Elsevier Ltd. All rights reserved.

Mass balance and long-term fate of PCDD/Fs in a lagoon sediment and paddy soil, Niigata, Japan

Energy Technology Data Exchange (ETDEWEB)

Sakai, Mizuki [National Institute for Agro-Environmental Science, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan)], E-mail: mizukis@affrc.go.jp; Seike, Nobuyasu [National Institute for Agro-Environmental Science, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan)], E-mail: seike@niaes.affrc.go.jp; Kobayashi, Jun [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)], E-mail: kobayashi.jun@nies.go.jp; Kajihara, Hideo [National Institute of Advanced Industrial Science and Technology, 16-1 Tsukuba, Ibaraki 305-8569 (Japan)], E-mail: kajihara.hideo@aist.go.jp; Takahashi, Yukio [Academic Assembly Institute of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata City 950-2181 (Japan)], E-mail: yukitak@eng.niigata-u.ac.jp

2008-12-15

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in a sediment core and in samples of surface sediment and paddy soil collected from the Toyano lagoon and Kameda basin in Niigata, Japan, were analyzed to elucidate the temporal trends of their concentrations in the lagoon sediment and the relationship between the sediment and the paddy soil. The mass balance of these pollutants was also estimated to determine their long-term fate in surface waters. An analysis by chemical mass balance identified the agrochemicals pentachlorophenol and 2,4,6-trichlorophenyl 4-nitrophenyl ether as the major sources of PCDD/Fs. On the basis of the findings regarding the mass balance in the Kameda basin over the last 40 years, we estimate that more than half the input of PCDD/Fs to the Kameda basin has disappeared. We suggest that the PCDD/Fs that flowed out from the paddy fields have been transferred to the lower basin. - The long-term mass balance of PCDD/Fs in sediments from paddy soil is elucidated.

Photochemical reactions between mercury (Hg) and dissolved organic matter decrease Hg bioavailability and methylation.

Science.gov (United States)

Luo, Hong-Wei; Yin, Xiangping; Jubb, Aaron M; Chen, Hongmei; Lu, Xia; Zhang, Weihua; Lin, Hui; Yu, Han-Qing; Liang, Liyuan; Sheng, Guo-Ping; Gu, Baohua

2017-01-01

Atmospheric deposition of mercury (Hg) to surface water is one of the dominant sources of Hg in aquatic environments and ultimately drives methylmercury (MeHg) toxin accumulation in fish. It is known that freshly deposited Hg is more readily methylated by microorganisms than aged or preexisting Hg; however the underlying mechanism of this process is unclear. We report that Hg bioavailability is decreased by photochemical reactions between Hg and dissolved organic matter (DOM) in water. Photo-irradiation of Hg-DOM complexes results in loss of Sn(II)-reducible (i.e. reactive) Hg and up to an 80% decrease in MeHg production by the methylating bacterium Geobacter sulfurreducens PCA. Loss of reactive Hg proceeded at a faster rate with a decrease in the Hg to DOM ratio and is attributed to the possible formation of mercury sulfide (HgS). These results suggest a new pathway of abiotic photochemical formation of HgS in surface water and provide a mechanism whereby freshly deposited Hg is readily methylated but, over time, progressively becomes less available for microbial uptake and methylation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Equilibrium mercury isotope fractionation between dissolved Hg(II) species and thiol-bound Hg

NARCIS (Netherlands)

Wiederhold, Jan G.; Cramer, Christopher J.; Daniel, Kelly; Infante, Ivan; Bourdon, Bernard; Kretzschmar, Ruben

2010-01-01

Stable Hg isotope ratios provide a new tool to trace environmental Hg cycling. Thiols (-SH) are the dominant Hg-binding groups in natural organic matter. Here, we report experimental and computational results on equilibrium Hg isotope fractionation between dissolved Hg(II) species and thiol-bound

Hybrid inventory, gravimetry and altimetry (HIGA) mass balance product for Greenland and the Canadian Arctic

DEFF Research Database (Denmark)

Colgan, W.; Abdalati, W.; Citterio, M.

2015-01-01

We present a novel inversion algorithm that generates a mass balance field that is simultaneously consistent with independent observations of glacier inventory derived from optical imagery, cryosphere-attributed mass trends derived from satellite gravimetry, and ice surface elevation trends derived...

Spent Nuclear Fuel (SNF) Project Canister Storage Building (CSB) Process Flow Diagram Mass Balance Calculations

International Nuclear Information System (INIS)

KLEM, M.J.

2000-01-01

The purpose of these calculations is to develop the material balances for documentation of the Canister Storage Building (CSB) Process Flow Diagram (PFD) and future reference. The attached mass balances were prepared to support revision two of the PFD for the CSB. The calculations refer to diagram H-2-825869

46 CFR 53.10-3 - Inspection and tests (modifies HG-500 through HG-540).

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Inspection and tests (modifies HG-500 through HG-540... tests (modifies HG-500 through HG-540). (a) The inspections required by HG-500 through HG-540 must be performed by the “Authorized Inspector” as defined in HG-515 of section IV of the ASME Boiler and Pressure...

Hg Storage and Mobility in Tundra Soils of Northern Alaska

Science.gov (United States)

Olson, C.; Obrist, D.

2017-12-01

Atmospheric mercury (Hg) can be transported over long distances to remote regions such as the Arctic where it can then deposit and temporarily be stored in soils. This research aims to improve the understanding of terrestrial Hg storage and mobility in the arctic tundra, a large receptor area for atmospheric deposition and a major source of Hg to the Arctic Ocean. We aim to characterize spatial Hg pool sizes across various tundra sites and to quantify the mobility of Hg from thawing tundra soils using laboratory mobility experiments. Active layer and permafrost soil samples were collected in the summer of 2014 and 2015 at the Toolik Field Station in northern Alaska (68° 38' N) and along a 200 km transect extending from Toolik to the Arctic Ocean. Soil samples were analyzed for total Hg concentration, bulk density, and major and trace elements. Hg pool sizes were estimated by scaling up Hg soil concentrations using soil bulk density measurements. Mobility of Hg in tundra soils was quantified by shaking soil samples with ultrapure Milli-Q® water as an extracting solution for 24 and 72 hours. Additionally, meltwater samples were collected for analysis when present. The extracted supernatant was analyzed for total Hg, dissolved organic carbon, cations and anions, redox, and ph. Mobility of Hg from soil was calculated using Hg concentrations determined in solid soil samples and in supernatant of soil solution samples. Results of this study show Hg levels in tundra mineral soils that are 2-5 times higher than those observed at temperate sites closer to pollution sources. Most of the soil Hg was located in mineral horizons where Hg mass accounted for 72% of the total soil pool. Soil Hg pool sizes across the tundra sites were highly variable (166 - 1,365 g ha-1; avg. 419 g ha-1) due to the heterogeneity in soil type, bulk density, depth to frozen layer, and soil Hg concentration. Preliminary results from the laboratory experiment show higher mobility of Hg in mineral

Mass Balance. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

Science.gov (United States)

Carnegie, John W.

This module describes the process used to determine solids mass and location throughout a waste water treatment plant, explains how these values are used to determine the solids mass balance around single treatment units and the entire system, and presents calculations of solids in pounds and sludge units. The instructor's manual contains a…

SEMIC: an efficient surface energy and mass balance model applied to the Greenland ice sheet

Directory of Open Access Journals (Sweden)

M. Krapp

2017-07-01

Full Text Available We present SEMIC, a Surface Energy and Mass balance model of Intermediate Complexity for snow- and ice-covered surfaces such as the Greenland ice sheet. SEMIC is fast enough for glacial cycle applications, making it a suitable replacement for simpler methods such as the positive degree day (PDD method often used in ice sheet modelling. Our model explicitly calculates the main processes involved in the surface energy and mass balance, while maintaining a simple interface and requiring minimal data input to drive it. In this novel approach, we parameterise diurnal temperature variations in order to more realistically capture the daily thaw–freeze cycles that characterise the ice sheet mass balance. We show how to derive optimal model parameters for SEMIC specifically to reproduce surface characteristics and day-to-day variations similar to the regional climate model MAR (Modèle Atmosphérique Régional, version 2 and its incorporated multilayer snowpack model SISVAT (Soil Ice Snow Vegetation Atmosphere Transfer. A validation test shows that SEMIC simulates future changes in surface temperature and surface mass balance in good agreement with the more sophisticated multilayer snowpack model SISVAT included in MAR. With this paper, we present a physically based surface model to the ice sheet modelling community that is general enough to be used with in situ observations, climate model, or reanalysis data, and that is at the same time computationally fast enough for long-term integrations, such as glacial cycles or future climate change scenarios.

Origin of howardites, diogenites and eucrites - A mass balance constraint

Science.gov (United States)

Warren, P. H.

1985-01-01

Two petrogenetic models for the noncumulate-basaltic parts of howardite meteorites are discussed. A mass balance constraint is developed which indicates that more than half of the basaltic components in howardites formed as residual liquids from fractional crystallization of melts that had earlier produced diogentelike pyroxene cumulate components. Other model constriants involving scandium trends, clustering near olivine-pyroxene-plagioclase peritectic, and MgO/(MgO + FeO) ratios are discussed.

Mercury dynamics and mass balance in a subtropical forest, southwestern China

Directory of Open Access Journals (Sweden)

M. Ma

2016-04-01

Full Text Available The mid-subtropical forest area in southwest China was affected by anthropogenic mercury (Hg emissions over the past 3 decades. We quantified mercury dynamics on the forest field and measured fluxes and pools of Hg in litterfall, throughfall, stream water and forest soil in an evergreen broadleaved forest field in southwestern China. Total Hg (THg input by the throughfall and litterfall was assessed at 32.2 and 42.9 µg m−2 yr−1, respectively, which was remarkably higher than those observed from other forest fields in the background of North America and Europe. Hg fluxes across the soil–air interface (18.6 mg m−2 yr−1 and runoff and/or stream flow (7.2 µg m−2 yr−1 were regarded as the dominant ways for THg export from the forest field. The forest field hosts an enormous amount of atmospheric Hg, and its reserves is estimated to be 25 341 µg m2. The ratio of output to input Hg fluxes (0.34 is higher compared with other study sites. The higher output / input ratio may represent an important ecological risk for the downstream aquatic ecosystems, even if the forest field could be an effective sink of Hg.

The mid-cretaceous water bearer: Isotope mass balance quantification of the Albian hydrologic cycle

Science.gov (United States)

Ufnar, David F.; Gonzalez, Luis A.; Ludvigson, Greg A.; Brenner, Richard L.; Witzke, B.J.

2002-01-01

A latitudinal gradient in meteoric ??18O compositions compiled from paleosol sphaerosiderites throughout the Cretaceous Western Interior Basin (KWIB) (34-75??N paleolatitude) exhibits a steeper, more depleted trend than modern (predicted) values (3.0??? [34??N latitude] to 9.7??? [75??N] lighter). Furthermore, the sphaerosiderite meteoric ??18O latitudinal gradient is significantly steeper and more depleted (5.8??? [34??N] to 13.8??? [75??N] lighter) than a predicted gradient for the warm mid-Cretaceous using modern empirical temperature-??18O precipitation relationships. We have suggested that the steeper and more depleted (relative to the modern theoretical gradient) meteoric sphaerosiderite ??18O latitudinal gradient resulted from increased air mass rainout effects in coastal areas of the KWIB during the mid-Cretaceous. The sphaerosiderite isotopic data have been used to constrain a mass balance model of the hydrologic cycle in the northern hemisphere and to quantify precipitation rates of the equable 'greenhouse' Albian Stage in the KWIB. The mass balance model tracks the evolving isotopic composition of an air mass and its precipitation, and is driven by latitudinal temperature gradients. Our simulations indicate that significant increases in Albian precipitation (34-52%) and evaporation fluxes (76-96%) are required to reproduce the difference between modern and Albian meteoric siderite ??18O latitudinal gradients. Calculations of precipitation rates from model outputs suggest mid-high latitude precipitation rates greatly exceeded modern rates (156-220% greater in mid latitudes [2600-3300 mm/yr], 99% greater at high latitudes [550 mm/yr]). The calculated precipitation rates are significantly different from the precipitation rates predicted by some recent general circulation models (GCMs) for the warm Cretaceous, particularly in the mid to high latitudes. Our mass balance model by no means replaces GCMs. However, it is a simple and effective means of obtaining

First observation of excited structures in neutron-deficient 179Hg : evidence for multiple shape coexistence

International Nuclear Information System (INIS)

Kondev, F.G.; Carpenter, M.P.; Janssens, R.V.F.; Lister, C.J.; Abu Saleem, K.; Ahmad, I.; Amro, H.; Caggiano, J.; Davids, C.N.; Heinz, A.; Herskind, B.; Khoo, T.L.; Lauristen, T.; Ma, W.C.; Ressler, J.J.; Reviol, W.; Riedinger, L.L.; Sarantites, D.G.; Seweryniak, D.; Siem, S.; Sonzongni, A.A.; Varmette, P.G.; Wiedenhoever, I.

2002-01-01

Excited structures in the neutron-deficient nucleus 179 Hg have been established for the first time using the Gammasphere spectrometer in conjunction with the fragment mass analyzer. Competing states originating from three different minima associated with nearly spherical, oblate, and prolate deformations were found. This result can be contrasted with the situation in heavier odd-mass Hg isotopes where only two minima (oblate and prolate) have been seen. The implications of these three shapes at low spin and excitation energy are discussed in the general context of shape coexistence in this mass region.

The role of crystallization-driven exsolution on the sulfur mass balance in volcanic arc magmas

Science.gov (United States)

Su, Yanqing; Huber, Christian; Bachmann, Olivier; Zajacz, Zoltán; Wright, Heather M.; Vazquez, Jorge A.

2016-01-01

The release of large amounts of sulfur to the stratosphere during explosive eruptions affects the radiative balance in the atmosphere and consequentially impacts climate for up to several years after the event. Quantitative estimations of the processes that control the mass balance of sulfur between melt, crystals, and vapor bubbles is needed to better understand the potential sulfur yield of individual eruption events and the conditions that favor large sulfur outputs to the atmosphere. The processes that control sulfur partitioning in magmas are (1) exsolution of volatiles (dominantly H2O) during decompression (first boiling) and during isobaric crystallization (second boiling), (2) the crystallization and breakdown of sulfide or sulfate phases in the magma, and (3) the transport of sulfur-rich vapor (gas influx) from deeper unerupted regions of the magma reservoir. Vapor exsolution and the formation/breakdown of sulfur-rich phases can all be considered as closed-system processes where mass balance arguments are generally easier to constrain, whereas the contribution of sulfur by vapor transport (open system process) is more difficult to quantify. The ubiquitous “excess sulfur” problem, which refers to the much higher sulfur mass released during eruptions than what can be accounted for by amount of sulfur originally dissolved in erupted melt, as estimated from melt inclusion sulfur concentrations (the “petrologic estimate”), reflects the challenges in closing the sulfur mass balance between crystals, melt, and vapor before and during a volcanic eruption. In this work, we try to quantify the relative importance of closed- and open-system processes for silicic arc volcanoes using kinetic models of sulfur partitioning during exsolution. Our calculations show that crystallization-induced exsolution (second boiling) can generate a significant fraction of the excess sulfur observed in crystal-rich arc magmas. This result does not negate the important role of

Analysis of moment structures for assessing relationships among perceived chewing ability, dentition status, muscle strength, and balance in community-dwelling older adults.

Science.gov (United States)

Moriya, Shingo; Notani, Kenji; Murata, Ayumi; Inoue, Nobuo; Miura, Hiroko

2014-12-01

The aim of this study was to assess relationships among perceived chewing ability, dentition status, muscle strength and balance in community-dwelling older adults using analysis of moment structures (Amos). Physical performance parameters such as muscle strength and balance can predict the future onset of disabilities in activities of daily living among older adults. In this context, elucidation of the relationships among oral conditions and physical performance parameters is necessary. Data on occlusal contact patterns of natural teeth (OPNT), self-assessed masticatory ability (mastication), body mass index (BMI), handgrip strength (HG) and one-leg standing time with eyes open (OLST) were collected from 501 independently living adults aged 65-74 years. The relationships among these parameters were analysed using Spearman's rank correlation coefficients and Amos. Subjects of both genders showed significant correlations among OPNT, mastication, HG and OLST, evaluated using Spearman's rank correlation coefficients. For each Amos model, the goodness-of-fit statistic indicated a good level of fit. In both men and women, OPNT was significantly related to mastication, and mastication was related to HG but not to OLST. OPNT was related to neither HG nor OLST in women and was related to OLST but not HG in men. The findings observed in this study present a possible importance of dental status and perceived chewing ability for the onset of disability by influencing physical performance in community-dwelling older adults. © 2012 The Gerodontology Society and John Wiley & Sons A/S.

Mass balance model parameter transferability on a tropical glacier

Science.gov (United States)

Gurgiser, Wolfgang; Mölg, Thomas; Nicholson, Lindsey; Kaser, Georg

2013-04-01

The mass balance and melt water production of glaciers is of particular interest in the Peruvian Andes where glacier melt water has markedly increased water supply during the pronounced dry seasons in recent decades. However, the melt water contribution from glaciers is projected to decrease with appreciable negative impacts on the local society within the coming decades. Understanding mass balance processes on tropical glaciers is a prerequisite for modeling present and future glacier runoff. As a first step towards this aim we applied a process-based surface mass balance model in order to calculate observed ablation at two stakes in the ablation zone of Shallap Glacier (4800 m a.s.l., 9°S) in the Cordillera Blanca, Peru. Under the tropical climate, the snow line migrates very frequently across most of the ablation zone all year round causing large temporal and spatial variations of glacier surface conditions and related ablation. Consequently, pronounced differences between the two chosen stakes and the two years were observed. Hourly records of temperature, humidity, wind speed, short wave incoming radiation, and precipitation are available from an automatic weather station (AWS) on the moraine near the glacier for the hydrological years 2006/07 and 2007/08 while stake readings are available at intervals of between 14 to 64 days. To optimize model parameters, we used 1000 model simulations in which the most sensitive model parameters were varied randomly within their physically meaningful ranges. The modeled surface height change was evaluated against the two stake locations in the lower ablation zone (SH11, 4760m) and in the upper ablation zone (SH22, 4816m), respectively. The optimal parameter set for each point achieved good model skill but if we transfer the best parameter combination from one stake site to the other stake site model errors increases significantly. The same happens if we optimize the model parameters for each year individually and transfer

Shape coexistence in $^{180}$Hg studied through the $\\beta$ decay of $^{180}$Tl

CERN Document Server

Elseviers, J; Diriken, J; Patronis, N; Koster, U; Franchoo, S; Vermote, S; Bree, N; Veselsky, M; Huyse, M; Cocolios, T E; Seliverstov, M; Barzakh, A; Van Duppen, P; Venhart, M; Van den Bergh, P; Page, R D; Marsh, B A; Wagemans, C; Heredia, J A; Ivanov, O; Comas, V F; Van De Walle, J; Antalic, S; Fedosseyev, V N; Fedorov, D; Andreyev, A N

2011-01-01

The beta(+)/EC decay of (180)Tl and excited states in the daughter nucleus (180)Hg have been investigated at the CERN On-Line Isotope Mass Separator (ISOLDE) facility. Many new low-lying energy levels were observed in (180)Hg, of which the most significant are the 0(2)(+) at 419.6 keV and the 2(2)(+) at 601.3 keV. The former is the bandhead of an excited band in (180)Hg assumed originally to be of prolate nature. From the beta feeding to the different states in (180)Hg, the ground-state spin of (180)Tl was deduced to be (4(-),5(-)).

A nitrogen mass balance for California

Science.gov (United States)

Liptzin, D.; Dahlgren, R. A.

2010-12-01

Human activities have greatly altered the global nitrogen cycle and these changes are apparent in water quality, air quality, ecosystem and human health. However, the relative magnitude of the sources of new reactive nitrogen and the fate of this nitrogen is not well established. Further, the biogeochemical aspects of the nitrogen cycle are often studied in isolation from the economic and social implications of all the transformations of nitrogen. The California Nitrogen Assessment is an interdisciplinary project whose aim is evaluating the current state of nitrogen science, practice, and policy in the state of California. Because of the close proximity of large population centers, highly productive and diverse agricultural lands and significant acreage of undeveloped land, California is a particularly interesting place for this analysis. One component of this assessment is developing a mass balance of nitrogen as well as identifying gaps in knowledge and quantifying uncertainty. The main inputs of new reactive nitrogen to the state are 1) synthetic nitrogen fertilizer, 2) biological nitrogen fixation, and 3) atmospheric nitrogen deposition. Permanent losses of nitrogen include 1) gaseous losses (N2, N2O, NHx, NOy), 2) riverine discharge, 3) wastewater discharge to the ocean, and 4) net groundwater recharge. A final term is the balance of food, feed, and fiber to support the human and animal populations. The largest input of new reactive nitrogen to California is nitrogen fertilizer, but both nitrogen fixation and atmospheric deposition contribute significantly. Non-fertilizer uses, such as the production of nylon and polyurethane, constitutes about 5% of the synthetic N synthesized production. The total nitrogen fixation in California is roughly equivalent on the 400,000 ha of alfalfa and the approximately 40 million ha of natural lands. In addition, even with highly productive agricultural lands, the large population of livestock, in particular dairy cows

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

Science.gov (United States)

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

2014-01-01

Stream sediment, stream water, and fish were collected from a broad region to evaluate downstream transport and dispersion of mercury (Hg) from inactive mines in the Monte Amiata Hg District (MAMD), Tuscany, Italy. Stream sediment samples ranged in Hg concentration from 20 to 1,900 ng/g, and only 5 of the 17 collected samples exceeded the probable effect concentration for Hg of 1,060 ng/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in Tiber River sediment varied from 0.12 to 0.52 ng/g, and although there is no established guideline for sediment methyl-Hg, these concentrations exceeded methyl-Hg in a regional baseline site (water varied from 1.2 to 320 ng/L, all of which were below the 1,000 ng/L Italian drinking water Hg guideline and the 770 ng/L U.S. Environmental Protection Agency (USEPA) guideline recommended to protect against chronic effects to aquatic wildlife. Methyl-Hg concentrations in stream water varied from water samples contained concentrations of As (drinking water guidelines to protect human health (10 μg/L for As and 20 μg/L for Sb) and for protection against chronic effects to aquatic wildlife (150 μg/L for As and 5.6 μg/L for Sb). Concentrations of Hg in freshwater fish muscle ranged from 0.052–0.56 μg/g (wet weight), mean of 0.17 μg/g, but only 17 % (9 of 54) exceeded the 0.30 μg/g (wet weight) USEPA fish muscle guideline recommended to protect human health. Concentrations of Hg in freshwater fish in this region generally decreased with increasing distance from the MAMD, where fish with the highest Hg concentrations were collected more proximal to the MAMD, whereas all fish collected most distal from Hg mines contained Hg below the 0.30 μg/g fish muscle guideline. Data in this study indicate some conversion of inorganic Hg to methyl-Hg and uptake of Hg in fish on the Paglia River, but less methylation of Hg and Hg uptake by freshwater fish in the larger Tiber River.

Binding of Hg by bacterial extracellular polysaccharide: a possible role in Hg tolerance.

Science.gov (United States)

Cruz, Kimberly; Guézennec, Jean; Barkay, Tamar

2017-07-01

Bacteria employ adaptive mechanisms of mercury (Hg) tolerance to survive in environments containing elevated Hg concentrations. The potential of extracellular polysaccharides (EPS) production by bacteria as a mechanism of Hg tolerance has not been previously investigated. The objectives of this study were to determine if bacterial EPS sorb Hg, and if so does sorption provide protection against Hg toxicity. Purified EPS with different chemical compositions produced by bacterial isolates from microbial mats in French Polynesian atolls and deep-sea hydrothermal vents were assessed for Hg sorption. The data showed that EPS sorbed up to 82% of Hg from solution, that this sorption was dependent on EPS composition, and that sorption was a saturable mechanism. Hg uptake capacities ranged from 0.005 to 0.454 mmol Hg/g for the different EPS. To determine if EPS production could alter bacterial Hg tolerance, Escherichia coli K-12 strains and their EPS defective mutants were tested by the disc inhibition assay. Mercury inhibited growth in a dose-dependent manner with wild-type strains having smaller (~1 mm), but statistically significant, zones of inhibition than various mutants and this difference was related to a 2-fold decline in the amount of EPS produced by the mutants relative to cell biomass. These experiments identified colanic acid and hexosamine as Hg-binding moieties in EPS. Together these data indicate that binding of Hg to EPS affords a low level of resistance to the producing bacteria.

193Hg collective oblate band with Ex>5.7 MeV

International Nuclear Information System (INIS)

Roy, N.; Henry, E.A.; Becker, J.A.

1993-01-01

Rotational bands in the neutron-deficient Pb nuclei 192,194,196-201 Pb have been reported recently. Band members are connected by L = 1 transitions, with crossover L = 2 transitions observed at the higher γ-ray energies. Regular and irregular patterns of γ-ray energies are observed. Conversion coefficients determined from intensity balance suggest the L = 1 transitions are M1. The bands have generally been interpreted as collective oblate, involving deformation aligned high-j proton configurations such as π(s 1/2 -2 h 9/2 i 13/2 ), and rotation aligned i 13/2 -n neutrons. Evidence for a similar band in 193 Hg has been obtained. 193 Hg was populated in the reaction 176 Yb( 22 Ne,5n) at E i ( 22 Ne) = 110 MeV. Reaction γ rays were detected with the Ge detector array HERA. A new 'collective' structure was observed with E x >5.7 MeV. States of the structure extend from I≥47/2 to I +10, and they decay with competing dipole and quadrupole transitions. The ratio B(M1)/B(E2), ∼ 2μ 2 /(e b) 2 , is approximately 10x lower in 193 Hg than in the Pb bands. The lowest member is produced with ∼20% of the 193 Hg cross section. Evidence for a similar band in 196 Hg will be presented at this meeting

Twenty-one years of mass balance observations along the K-transect, West Greenland

Directory of Open Access Journals (Sweden)

R. S. W. van de Wal

2012-08-01

Full Text Available A 21-yr record is presented of surface mass balance measurements along the K-transect. The series covers the period 1990–2011. Data are available at eight sites along a transect over an altitude range of 380–1850 m at approximately 67° N in West Greenland. The surface mass balance gradient is on average 3.8 × 10⁻³ m w.e. m⁻¹, and the mean equilibrium line altitude is 1553 m a.s.l. Only the lower three sites within 10 km of the margin up to an elevation of 700 m experience a significant increasing trend in the ablation over the entire period. Data are available at: doi:10.1594/PANGAEA.779181.

Mass balance evolution of Martial Este Glacier, Tierra del Fuego (Argentina for the period 1960–2099

Directory of Open Access Journals (Sweden)

M. Buttstädt

2009-12-01

Full Text Available The Martial Este Glacier in southern Tierra del Fuego was studied in order to estimate the surface mass balance from 1960 until 2099. For this reason a degree-day model was calibrated. Air temperature and precipitation data obtained from 3 weather stations as well as glaciological measurements were applied. The model was driven using a vertical air temperature gradient of 0.69 K/100 m, a degree-day factor for snow of 4.7 mm w.e. K⁻¹ day⁻¹, a degree-day factor for ice of 9.4 mm w.e. K⁻¹ day⁻¹ and a precipitation gradient of 22%/100 m. For the purpose of surface mass balance reconstruction for the time period 1960 until 2006 a winter vertical air temperature gradient of 0.57 K/100 m and a summer vertical air temperature gradient of 0.71 K/100 m were added as well as a digital terrain model. The key finding is an almost continuous negative mass balance of −772 mm w.e. a⁻¹ throughout this period. While the calculation of the mass balance for the period 1960–2006 is based on instrumental records, the mass balance for the years 2007 until 2099 was estimated based on the IPCC SRES A2-scenario. To accomplish this estimation, the dataset of the global climate model HadCM3 was statistically downscaled to fit local conditions at Martial Este Glacier. Subsequently, the downscaled air temperature and precipitation were applied to a volume-area scaling glacier change model. Findings reveal an enduring deglaciation resulting in a surface area reduction of nearly 93% until 2099. This implicates that the Martial Este Glacier might be melted off at the beginning of the 22nd century.

Modelling the contribution of supraglacial ice cliffs to the mass-balance of glaciers in the Langtang catchment, Nepalese Himalaya

Science.gov (United States)

Buri, P.; Steiner, J. F.; Miles, E.; Ragettli, S.; Pellicciotti, F.

2017-12-01

Supraglacial cliffs are typical surface features of debris-covered glaciers worldwide, affecting surface evolution, and mass balance by providing a direct ice-atmosphere interface where melt rates can be very high. As a result, ice cliffs act as windows of energy transfer from the atmosphere to the ice, and enhance melt and mass losses of otherwise insulated ice. However, their contribution to glacier mass balance has never been quantified at the glacier scale, and all inference has been obtained from upscaling results of point-scale models or observations at select individual cliffs. Here we use a 3D, physically-based backwasting model to estimate the volume losses associated with the melting and backwasting of supraglacial ice cliffs for the entire debris-covered glacier area of the Langtang catchment. We estimate mass losses for the 2014 melt season and compare them to recent values of glacier mass balance determined from geodetic and numerical modelling approached. Cliff outlines and topography are derived from high-resolution stereo SPOT6-imagery from April 2014. Meteorological data to force the model are provided by automatic weather stations on- and off-glacier within the valley. The model simulates ice cliff backwasting by considering the cliff-atmosphere energy-balance, reburial by debris and the effects of adjacent ponds. In the melt season of 2014, cliffs' distribution and patterns of mass losses vary considerably from glacier to glacier, and we relate rates of volume loss to both glaciers' and cliffs' characteristics. Only cliffs with a northerly aspect account for substantial losses. Uncertainty in our estimates is due to the quality of the stereo DEM, uncertainties in the cliff delineation and the fact that we use a conservative approach to cliff delineation and discard very small cliffs and those for which uncertainty in topography is high. Despite these uncertainties, our work presents the first estimate of the importance of supraglacial ice

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

Science.gov (United States)

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

2007-12-01

We present here the first study of the isotopic composition of Hg in rocks, ore deposits, and active hydrothermal systems from the California Coast Ranges, one of Earth's largest Hg-depositing systems. The Franciscan Complex and Great Valley Sequence, which form the bedrock in the California Coast Ranges, are intruded and overlain by Tertiary volcanic rocks including the Clear Lake Volcanic Sequence. These rocks contain two types of Hg deposits, hot-spring deposits that form at shallow depths (<300 m) and silica-carbonate deposits that extend to greater depths (200 to 1000 m), as well as active springs and geothermal systems that release Hg to the present surface. The Franciscan Complex and Great Valley Sequence contain clastic sedimentary rocks with higher concentrations of Hg than volcanic rocks of the Clear Lake Volcanic Field. Mean Hg isotope compositions for all three rock units are similar, although the range of values in Franciscan Complex rocks is greater than in either Great Valley or Clear Lake rocks. Hot spring and silica-carbonate Hg deposits have similar average isotopic compositions that are indistinguishable from averages for the three rock units, although δ202Hg values for the Hg deposits have a greater variance than the country rocks. Precipitates from dilute spring and saline thermal waters in the area have similarly large variance and a mean δ202Hg value that is significantly lower than the ore deposits and rocks. These observations indicate there is little or no isotopic fractionation during release of Hg from its source rocks into hydrothermal solutions. Isotopic fractionation does appear to take place during transport and concentration of Hg in deposits, especially in their uppermost parts. Boiling of hydrothermal fluids is likely the most important process causing of the observed Hg isotope fractionation. This should result in the release of Hg with low δ202Hg values into the atmosphere from the top of these hydrothermal systems and a

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

Directory of Open Access Journals (Sweden)

Joseph J. Nocera

1998-12-01

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

Occurrence of pharmaceuticals in a municipal wastewater treatment plant: mass balance and removal processes.

Science.gov (United States)

Gao, Pin; Ding, Yunjie; Li, Hui; Xagoraraki, Irene

2012-06-01

Occurrence and removal efficiencies of fifteen pharmaceuticals were investigated in a conventional municipal wastewater treatment plant in Michigan. Concentrations of these pharmaceuticals were determined in both wastewater and sludge phases by a high-performance liquid chromatograph coupled to a tandem mass spectrometer. Detailed mass balance analysis was conducted during the whole treatment process to evaluate the contributing processes for pharmaceutical removal. Among the pharmaceuticals studied, demeclocycline, sulfamerazine, erythromycin and tylosin were not detected in the wastewater treatment plant influent. Other target pharmaceuticals detected in wastewater were also found in the corresponding sludge phase. The removal efficiencies of chlortetracycline, tetracycline, sulfamerazine, acetaminophen and caffeine were >99%, while doxycycline, oxytetracycline, sulfadiazine and lincomycin exhibited relatively lower removal efficiencies (e.g., <50%). For sulfamethoxazole, the removal efficiency was approximately 90%. Carbamazepine manifested a net increase of mass, i.e. 41% more than the input from the influent. Based on the mass balance analysis, biotransformation is believed to be the predominant process responsible for the removal of pharmaceuticals (22% to 99%), whereas contribution of sorption to sludge was relatively insignificant (7%) for the investigated pharmaceuticals. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Neutron Scattering Study of Lattice Dynamics of HgTe and HgSe

DEFF Research Database (Denmark)

Kepa, H.; Giebultowicz, T.; Buras, B.

1982-01-01

The dispersion relations for the acoustic and optic phonons in HgTe and for the acoustic phonons in HgSe were determined by neutron inelastic scattering in three high symmetry directions. The effect of the free-carrier screening of the long-range electric field of LO phonons in HgTe was observed....... The formalism of the rigid ion model is used for numerical calculations of the phonon dispersion relations and the phonon densities of states in HgTe and HgSe....

Progress toward Consensus Estimates of Regional Glacier Mass Balances for IPCC AR5

Science.gov (United States)

Arendt, A. A.; Gardner, A. S.; Cogley, J. G.

2011-12-01

Glaciers are potentially large contributors to rising sea level. Since the last IPCC report in 2007 (AR4), there has been a widespread increase in the use of geodetic observations from satellite and airborne platforms to complement field observations of glacier mass balance, as well as significant improvements in the global glacier inventory. Here we summarize our ongoing efforts to integrate data from multiple sources to arrive at a consensus estimate for each region, and to quantify uncertainties in those estimates. We will use examples from Alaska to illustrate methods for combining Gravity Recovery and Climate Experiment (GRACE), elevation differencing and field observations into a single time series with related uncertainty estimates. We will pay particular attention to reconciling discrepancies between GRACE estimates from multiple processing centers. We will also investigate the extent to which improvements in the glacier inventory affect the accuracy of our regional mass balances.

Electron beam induced Hg desorption and the electronic structure of the Hg depleted surface of Hg1/sub -//sub x/Cd/sub x/Te

International Nuclear Information System (INIS)

Shih, C.K.; Friedman, D.J.; Bertness, K.A.; Lindau, I.; Spicer, W.E.; Wilson, J.A.

1986-01-01

Auger electron spectroscopy (AES), x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED), and angle-resolved ultraviolet photoemission spectroscopy (ARPES) were used to study the electron beam induced Hg desorption from a cleaved (110)Hg/sub 1-//sub x/Cd/sub x/Te surface and the electronic structure of the Hg depleted surface. Solid state recrystallized Hg/sub 1-//sub x/Cd/sub x/Te single crystals were used. It was found that the electron beam heating dominated the electron beam induced Hg desorption on Hg/sub 1-//sub x/Cd/sub x/Te. At the electron beam energy used, the electron beam heating extended several thousand angstroms deep. However, the Hg depletion saturated after a few monolayers were depleted of Hg atoms. At the initial stage of Hg loss (only 3%), the surface band bends upward (more p type). The ARPES spectrum showed the loss of some E vs k dispersion after 22% Hg atoms were removed from the surface region, and no dispersion was observed after 43% Hg atoms were removed. These results have important implications on the electronic structure of the surfaces and interfaces of which the stoichiometry is altered

Superconductivity of Hg3NbF6 and Hg3TaF6

International Nuclear Information System (INIS)

Datars, W.R.; Morgan, K.R.; Gillespie, R.J.

1983-01-01

Low-temperature ac susceptibility measurements show that two new metallic compounds, Hg 3 TaF 6 and Hg 3 NbF 6 , are superconductors with a critical temperature of 7.0 K. Critical fields are 20% higher in Hg 3 TaF 6 but the temperature dependence of the critical field of the compounds is very similar down to 1.35 K. The critical field extrapolated to T = 0 K is 0.17 T for Hg 3 TaF 6 and 0.13 T for Hg 3 NbF 6

Comparison of a Mass Balance and an Ecosystem Model Approach when Evaluating the Carbon Cycling in a Lake Ecosystem

International Nuclear Information System (INIS)

Andersson, Eva; Sobek, Sebastian

2006-01-01

Carbon budgets are frequently used in order to understand the pathways of organic matter in ecosystems, and they also have an important function in the risk assessment of harmful substances. We compared two approaches, mass balance calculations and an ecosystem budget, to describe carbon processing in a shallow, oligotrophic hardwater lake. Both approaches come to the same main conclusion, namely that the lake is a net auto trophic ecosystem, in spite of its high dissolved organic carbon and low total phosphorus concentrations. However, there were several differences between the carbon budgets, e.g. in the rate of sedimentation and the air-water flux of CO 2 . The largest uncertainty in the mass balance is the contribution of emergent macrophytes to the carbon cycling of the lake, while the ecosystem budget is very sensitive towards the choice of conversion factors and literature values. While the mass balance calculations produced more robust results, the ecosystem budget gave valuable insights into the pathways of organic matter transfer in the ecosystem. We recommend that when using an ecosystem budget for the risk assessment of harmful substances, mass balance calculations should be performed in parallel in order to increase the robustness of the conclusions

Mass balance-based regression modeling of PAHs accumulation in urban soils, role of urban development

International Nuclear Information System (INIS)

Peng, Chi; Wang, Meie; Chen, Weiping; Chang, Andrew C.

2015-01-01

We investigated the polycyclic aromatic hydrocarbons (PAHs) contents in 68 soils samples collected at housing developments that represent different length of development periods across Beijing. Based on the data, we derived a mass balanced mathematical model to simulate the dynamics of PAH accumulations in urban soils as affected by the urban developments. The key parameters were estimated by fitting the modified mass balance model to the data of PAH concentrations vs. building age of the sampling green area. The total PAH concentrations would increase from the baseline of 267 ng g −1 to 3631 ng g −1 during the period of 1978–2048. It showed that the dynamic changes in the rates of accumulations of light and heavy PAH species were related to the shifting of sources of fuels, combustion efficiencies, and amounts of energy consumed during the course of development. - Highlights: • Introduced a mass balance model for soil PAHs accumulation with urbanization. • Reconstructed the historical data of PAH accumulation in soil of Beijing, China. • The soil PAH concentrations would be doubled in the following 40 years. • The composition of PAH emissions were shifting to light PAH species. - Introduced a regression modeling approach to predict the changes of PAH concentrations in urban soil

40 CFR 60.4112 - Changing Hg designated representative and alternate Hg designated representative; changes in...

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Changing Hg designated representative and alternate Hg designated representative; changes in owners and operators. 60.4112 Section 60.4112... Generating Units Hg Designated Representative for Hg Budget Sources § 60.4112 Changing Hg designated...

Pathways of CH3Hg and Hg ingestion in benthic organisms: an enriched isotope approach.

Science.gov (United States)

Taylor, Vivien F; Bugge, Deenie; Jackson, Brian P; Chen, Celia Y

2014-05-06

Mercury is a widespread contaminant in marine food webs, and identifying uptake pathways of mercury species, CH3Hg(+) and Hg(2+), into low trophic level organisms is important to understanding its entry into marine food webs. Enriched stable isotope tracers were used to study benthic vs. pelagic pathways of CH3Hg(+) and Hg(2+) uptake via food to the infaunal estuarine amphipod, Leptocheirus plumulosus. Algal cells differentially labeled with isotopically enriched CH3Hg(+) or Hg(2+) were added simultaneously to the sediment and water column of microcosms, and Hg species were monitored in amphipods and in sediment and water compartments. Methylation of Hg(2+) occurred during the course of the experiment, enhancing the uptake of Hg(2+) spikes. Trophic transfer of Hg from algae added to the water column was determined to be the major uptake route for amphipods, suggesting inputs of contaminated organic matter from the pelagic zone are important to mercury bioaccumulation even in organisms living in sediments.

Elastic, dynamical, and electronic properties of LiHg and Li3Hg: First-principles study

Science.gov (United States)

Wang, Yan; Hao, Chun-Mei; Huang, Hong-Mei; Li, Yan-Ling

2018-04-01

The elastic, dynamical, and electronic properties of cubic LiHg and Li3Hg were investigated based on first-principles methods. The elastic constants and phonon spectral calculations confirmed the mechanical and dynamical stability of the materials at ambient conditions. The obtained elastic moduli of LiHg are slightly larger than those of Li3Hg. Both LiHg and Li3Hg are ductile materials with strong shear anisotropy as metals with mixed ionic, covalent, and metallic interactions. The calculated Debye temperatures are 223.5 K and 230.6 K for LiHg and Li3Hg, respectively. The calculated phonon frequency of the T2 g mode in Li3Hg is 326.8 cm-1. The p states from the Hg and Li atoms dominate the electronic structure near the Fermi level. These findings may inspire further experimental and theoretical study on the potential technical and engineering applications of similar alkali metal-based intermetallic compounds.

High-resolution DEMs for High-mountain Asia: A systematic, region-wide assessment of geodetic glacier mass balance and dynamics

Science.gov (United States)

Shean, D. E.; Arendt, A. A.; Osmanoglu, B.; Montesano, P.

2017-12-01

High Mountain Asia (HMA) constitutes the largest glacierized region outside of the Earth's polar regions. Although available observations are limited, long-term records indicate sustained regional glacier mass loss since 1850, with increased loss in recent decades. Recent satellite data (e.g., GRACE, ICESat-1) show spatially variable glacier mass balance, with significant mass loss in the Himalaya and Hindu Kush and slight mass gain in the Karakoram. We generated 4000 high-resolution digital elevation models (DEMs) from sub-meter commercial stereo imagery (DigitalGlobe WorldView/GeoEye) acquired over glaciers in High-mountain Asia from 2002-present (mostly 2013-present). We produced a regional 8-m DEM mosaic for 2015 and estimated 15-year geodetic mass balance for 40000 glaciers larger than 0.1 km2. We are combining with other regional DEM sources to systematically document the spatiotemporal evolution of glacier mass balance for the entire HMA region. We also generated monthly to interannual DEM and velocity time series for high-priority sites distributed across the region, with >15-20 DEMs available for some locations from 2010-present. These records document glacier dynamics, seasonal snow accumulation/redistribution, and processes that affect glacier mass balance (e.g., ice-cliff retreat, debris cover evolution). These efforts will provide basin-scale assessments of snow/ice melt runoff contributions for model cal/val and downstream water resources applications. We will continue processing all archived and newly available commercial stereo imagery for HMA, and will release all DEMs through the HiMAT DAAC.

Mass, energy and material balances of SRF production process. Part 3: solid recovered fuel produced from municipal solid waste.

Science.gov (United States)

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2015-02-01

This is the third and final part of the three-part article written to describe the mass, energy and material balances of the solid recovered fuel production process produced from various types of waste streams through mechanical treatment. This article focused the production of solid recovered fuel from municipal solid waste. The stream of municipal solid waste used here as an input waste material to produce solid recovered fuel is energy waste collected from households of municipality. This article presents the mass, energy and material balances of the solid recovered fuel production process. These balances are based on the proximate as well as the ultimate analysis and the composition determination of various streams of material produced in a solid recovered fuel production plant. All the process streams are sampled and treated according to CEN standard methods for solid recovered fuel. The results of the mass balance of the solid recovered fuel production process showed that 72% of the input waste material was recovered in the form of solid recovered fuel; 2.6% as ferrous metal, 0.4% as non-ferrous metal, 11% was sorted as rejects material, 12% as fine faction and 2% as heavy fraction. The energy balance of the solid recovered fuel production process showed that 86% of the total input energy content of input waste material was recovered in the form of solid recovered fuel. The remaining percentage (14%) of the input energy was split into the streams of reject material, fine fraction and heavy fraction. The material balances of this process showed that mass fraction of paper and cardboard, plastic (soft) and wood recovered in the solid recovered fuel stream was 88%, 85% and 90%, respectively, of their input mass. A high mass fraction of rubber material, plastic (PVC-plastic) and inert (stone/rock and glass particles) was found in the reject material stream. © The Author(s) 2014.

Multi-year analysis of distributed glacier mass balance modelling and equilibrium line altitude on King George Island, Antarctic Peninsula

Science.gov (United States)

Falk, Ulrike; López, Damián A.; Silva-Busso, Adrián

2018-04-01

The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP). This region was subject to strong warming trends in the atmospheric surface layer. Surface air temperature increased about 3 K in 50 years, concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. The positive trend in surface air temperature has currently come to a halt. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0 K (100 m)-1) and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns. The increased mesocyclonic activity during the wintertime over the past decades in the study area results in intensified advection of warm, moist air with high temperatures and rain and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. Its impact on winter accumulation results in the observed negative mass balance estimates. Six years of continuous glaciological measurements on mass balance stake transects as well as 5 years of climatological data time series are presented and a spatially distributed glacier energy balance melt model adapted and run based on these multi-year data sets. The glaciological surface mass balance model is generally in good agreement with observations, except for atmospheric conditions promoting snow drift by high wind speeds, turbulence-driven snow deposition and snow layer erosion by rain. No drift in the difference between simulated mass balance and mass balance measurements can be seen over the course of the 5-year model run period. The winter accumulation does not suffice to compensate for the high variability in summer ablation. The results are analysed to assess changes in meltwater input to the coastal waters, specific glacier mass balance and the equilibrium line altitude (ELA). The Fourcade Glacier catchment drains

Demonstration of isotope-mass balance approach for water budget analyses of El-burulus Lake, Nile Delta, Egypt

International Nuclear Information System (INIS)

Sadek, M.A.

2006-01-01

The major elements of El-Burulus lake water system are rainfall, agricultural drainage discharge, groundwater, human activities, evaporation and water interaction between the lake and the Mediterranean sea. The principal input sources are agricultural drainage (8 drains at the southern borders of the lake), sea water as well as some contribution of precipitation, groundwater and human activities. Water is lost from the lake through evaporation and surface outflow. The present study has been conducted using isotopic / mass balance approach to investigate the water balance of El-Burulus lake and to emphasize the relative contribution of different input / output components which affect the environmental and hydrological terms of the system. An isotopic evaporation pan experiment was performed to estimate the parameters of relevance to water balance (isotopic composition of free air moisture and evaporating flux) and to simulate the isotopic enrichment of evaporation under atmospheric and hydraulic control. The isotopic mass balance approach employed herein facilitated the estimation of groundwater inflow to the lake, evaporated fraction of total lake inflow (E/I) and its fraction to outflow (E/O), ratio of surface inflow to surface outflow (I/O) as well as residence time of lake water. The isotopic mass balance approach has been validated by comparing the values of estimated parameters with the previous hydrological investigations; a quite good match has been indicated, the relevance of this approach is related to its integrative scale and the more simply implementation

A 30-year record of surface mass balance (1966-95) and motion and surface altitude (1975-95) at Wolverine Glacier, Alaska

Science.gov (United States)

Mayo, Lawrence R.; Trabant, Dennis C.; March, Rod S.

2004-01-01

Scientific measurements at Wolverine Glacier, on the Kenai Peninsula in south-central Alaska, began in April 1966. At three long-term sites in the research basin, the measurements included snow depth, snow density, heights of the glacier surface and stratigraphic summer surfaces on stakes, and identification of the surface materials. Calculations of the mass balance of the surface strata-snow, new firn, superimposed ice, and old firn and ice mass at each site were based on these measurements. Calculations of fixed-date annual mass balances for each hydrologic year (October 1 to September 30), as well as net balances and the dates of minimum net balance measured between time-transgressive summer surfaces on the glacier, were made on the basis of the strata balances augmented by air temperature and precipitation recorded in the basin. From 1966 through 1995, the average annual balance at site A (590 meters altitude) was -4.06 meters water equivalent; at site B (1,070 meters altitude), was -0.90 meters water equivalent; and at site C (1,290 meters altitude), was +1.45 meters water equivalent. Geodetic determination of displacements of the mass balance stake, and glacier surface altitudes was added to the data set in 1975 to detect the glacier motion responses to variable climate and mass balance conditions. The average surface speed from 1975 to 1996 was 50.0 meters per year at site A, 83.7 meters per year at site B, and 37.2 meters per year at site C. The average surface altitudes were 594 meters at site A, 1,069 meters at site B, and 1,293 meters at site C; the glacier surface altitudes rose and fell over a range of 19.4 meters at site A, 14.1 meters at site B, and 13.2 meters at site C.

On the mean square displacements (MSD) of Hg and Te in HgTe

International Nuclear Information System (INIS)

Madhavan, Y.; Ramachandran, K.

1989-01-01

The mean square displacements (MSD) of Hg and Te in the perfect system of HgTe are worked out in the modified rigid ion model of Plumelle and Vandevyver. Also the MSD of Hg and Te neighbours around anion and cation vacancies in HgTe are worked out giving an active role for the vacancy following the theory of Maradudin et al. The results are compared with experimental values. (author)

Comparing Mass Balance and Adjoint-Based 4D-VAR Methods for Inverse Modeling of Nitrogen Dioxide Columns for Nitrogen Oxide Emissions

Science.gov (United States)

Cooper, M.; Martin, R.; Henze, D. K.

2016-12-01

Nitrogen oxide (NOx ≡ NO + NO2) emission inventories can be improved through top-down constraints provided by inverse modeling of observed nitrogen dioxide (NO2) columns. Here we compare two methods of inverse modeling for emissions of NOx from synthetic NO2 columns generated from known emissions using the GEOS-Chem chemical transport model and its adjoint. We treat the adjoint-based 4D-VAR approach for estimating top-down emissions as a benchmark against which to evaluate variations on the mass balance method. We find that the standard mass balance algorithm can be improved by using an iterative process and using finite difference to calculate the local sensitivity of a change in NO2 columns to a change in emissions, resulting in a factor of two reduction in inversion error. In a simplified case study to recover local emission perturbations, horizontal smearing effects due to NOx transport were better resolved by the adjoint-based approach than by mass balance. For more complex emission changes that reflect real world scenarios, the iterative finite difference mass balance and adjoint methods produce similar top-down inventories when inverting hourly synthetic observations, both reducing the a priori error by factors of 3-4. Inversions of data sets that simulate satellite observations from low Earth and geostationary orbits also indicate that both the mass balance and adjoint inversions produce similar results, reducing a priori error by a factor of 3. As the iterative finite difference mass balance method provides similar accuracy as the adjoint-based 4D-VAR method, it offers the ability to efficiently estimate top-down emissions using models that do not have an adjoint.

Determination of spin, magnetic moment and isotopic shift of neutron rich 205Hg by optical pumping

International Nuclear Information System (INIS)

Rodriguez, J.; Bonn, J.; Huber, G.; Kluge, H.J.; Otten, E.W.; European Organisation for Nuclear Research, Geneva

1975-01-01

Neutron rich 205 Hg(Tsub(1/2) = 5.2 min) was produced and on-line mass separated at the ISOLDE facility at CERN. The polarization achieved by optical pumping via the atomic line (6s 21 S 0 - 6s6p 3 P 1 , lambda = 2,537 A) was monitored by the β decay asymmetry. Hyperfine structure and isotopic shift of the 205 Hg absorption line was determined by Zeeman scanning. In addition a magnetic resoncance was performed on the polarized 205 Hg nuclei in the atomic ground state. The results are: I( 205 Hg) = 1/2 (confirmed); μ(I, 205 Hg) = 0.5915(1)μ(N) (uncorrected for diamagnetism); isotopic shift deltaν(204/205) = ν( 205 Hg) - ν( 204 Hg) = -1.8(1)GHz. μ(I) and IS are discussed briefly in the frame of current literature. (orig.) [de

Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species

International Nuclear Information System (INIS)

Greger, Maria; Wang Yaodong; Neuschuetz, Clara

2005-01-01

In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 μg L -1 Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected. - Mercury translocation to shoots was low

Estimating the ice thickness of mountain glaciers with an inverse approach using surface topography and mass-balance

International Nuclear Information System (INIS)

Michel, Laurent; Picasso, Marco; Farinotti, Daniel; Bauder, Andreas; Funk, Martin; Blatter, Heinz

2013-01-01

We present a numerical method to estimate the ice thickness distribution within a two-dimensional, non-sliding mountain glacier, given a transient surface geometry and a mass-balance distribution, which are relatively easy to obtain for a large number of glaciers. The inverse approach is based on the shallow ice approximation (SIA) of ice flow and requires neither filtering of the surface topography with a lower slope limit nor approximation of constant basal shear stress. We first address this problem for a steady-state surface geometry. Next, we use an apparent surface mass-balance description that makes the transient evolution quasi-stationary. Then, we employ a more elaborated fixed-point method in which the bedrock solution is iteratively obtained by adding the difference between the computed and known surface geometries at the end of the considered time interval. In a sensitivity study, we show that the procedure is much more susceptible to small perturbations in surface geometry than mass-balance. Finally, we present preliminary results for bed elevations in three space dimensions. (paper)

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

International Nuclear Information System (INIS)

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

2013-01-01

Highlights: ► Hg and Pb concentration and isotopic compositions traced anthropogenic sources. ► Concentrations and metal loadings of Hg and Pb increased during the smelting period. ► Hg isotopic compositions changed during smelting compared to the pre-smelting period. ► Data indicate mass independent fractionation of Hg isotopes. - Abstract: Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ 202 Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ 202 Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206 Pb/ 207 Pb and 208 Pb/ 207 Pb isotopic compositions during these periods. Data for Δ 199 Hg and Δ 201 Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ 199 Hg and Δ 201 Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger

Using an SLR inversion to measure the mass balance of Greenland before and during GRACE

Science.gov (United States)

Bonin, Jennifer

2016-04-01

The GRACE mission has done an admirable job of measuring large-scale mass changes over Greenland since its launch in 2002. However before that time, measurements of large-scale ice mass balance were few and far between, leading to a lack of baseline knowledge. High-quality Satellite Laser Ranging (SLR) data existed a decade earlier, but normally has too low a spatial resolution to be used for this purpose. I demonstrate that a least squares inversion technique can reconstitute the SLR data and use it to measure ice loss over Greenland. To do so, I first simulate the problem by degrading today's GRACE data to a level comparable with SLR, then demonstrating that the inversion can re-localize Greenland's contribution to the low-resolution signal, giving an accurate time series of mass change over all of Greenland which compares well with the full-resolution GRACE estimates. I then utilize that method on the actual SLR data, resulting in an independent 1994-2014 time series of mass change over Greenland. I find favorable agreement between the pure-SLR inverted results and the 2012 Ice-sheet Mass Balance Inter-comparison Exercise (IMBIE) results, which are largely based on the "input-output" modeling method before GRACE's launch.

Model description of trophodynamic behavior of methylmercury in a marine aquatic system

International Nuclear Information System (INIS)

Tong Yindong; Zhang Wei; Hu Xindi; Ou Langbo; Hu Dan; Yang Tianjun; Wei Wen; Wang Xuejun

2012-01-01

A marine food web in Bohai Bay, China, was selected to study methylmercury (MeHg) bioaccumulation, and an aquivalence-based mass balance model was established to explore the possibility of predicting the MeHg concentrations and quantifying MeHg bioaccumulation in the food web. Results showed that both total mercury (THg) and MeHg were biomagnified in the food web. The calculated MeHg concentrations in the selected species agreed well with the measured values, which shows the model could be a useful tool in MeHg concentration prediction in food web. Model outputs also showed that metabolism and growth dilution could be the dominant mechanisms for the reduction of MeHg levels in aquatic organisms. With the increase of trophic level, the contribution of food as a MeHg source for organism is increasing, and MeHg from prey was the dominant source. - Highlights: ► We model the bioaccumulation of methylmercury in a marine aquatic food web. ► Aquivalence-based mass balance model could quantify MeHg trophic transfer. ► Metabolism and growth dilution are dominant mechanisms of MeHg reduction in organisms. ► With increase of trophic levels, contribution of food as MeHg source is increasing. - Aquivalence-based mass balance model was established to study methylmercury bioaccumulation in a marine food web.

Hyperemesis Gravidarum (HG)

Science.gov (United States)

... Treatments Risks Complications Impact Take a Poll If HG continued past mid-pregnancy , did you experience complications ... Understanding Hyperemesis | Overview About Hyperemesis Gravidarum Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting ...

Photoionization study of HgAr

International Nuclear Information System (INIS)

Linn, S.H.; Brom, J.M. Jr.; Tzeng, W.; Ng, C.Y.

1985-01-01

Photoionization efficiency data for HgAr + have been obtained in the region of 680--1240 A. The ionization energy of HgAr was determined to be 10.217 +- 0.012 eV. This value allows the calculation of the dissociation energy of HgAr + to be 0.228 +- 0.017 eV. The relative probabilities for the formation of HgAr + via the reactions Ar* x Hg or Hg* x Ar→ HgAr + +e - with Ar* and Hg* prepared in high Rydberg states in the energy range of 10.22--15.79 eV were estimated. Although the radii for the 3d and 5s Rydberg ortitals of Ar have similar values, the probabilities for the formation of HgAr + from Hg x Ar* with Ar* in the 5s[3/2] 0 1 and 5s'[1/2] 0 1 Rydberg states are substantially greater than those when the Ar* excited atoms are in the 3d[1/2] 0 1 , 3s[3/2] 0 1 , and 3d'[3/2] 0 1 Rydberg levels. The ratio for the cross sections for the formation of HgAr + from Hg x Ar* with Ar* formed in the 3d[1/2] 0 1 and 4d[1/2] 0 1 states, as well as that with Ar* prepared in the 5d[1/2] 0 1 and 6d[1/2] 0 1 states, were found to be consistent with the predictions of the previous impact parameter calculations

Mass balance of Mars' residual south polar cap from CTX images and other data

Science.gov (United States)

Thomas, P. C.; Calvin, W.; Cantor, B.; Haberle, R.; James, P. B.; Lee, S. W.

2016-04-01

Erosion of pits in the residual south polar cap (RSPC) of Mars concurrent with deposition and fluctuating cap boundaries raises questions about the mass balance and long term stability of the cap. Determining a mass balance by measurement of a net gain or loss of atmospheric CO2 by direct pressure measurements (Haberle, R.M. et al. [2014]. Secular climate change on Mars: An update using one Mars year of MSL pressure data. American Geophysical Union (Fall). Abstract 3947), although perhaps the most direct method, has so far given ambiguous results. Estimating volume changes from imaging data faces challenges, and has previously been attempted only in isolated areas of the cap. In this study we use 6 m/pixel Context Imager (CTX) data from Mars year 31 to map all the morphologic units of the RSPC, expand the measurement record of pit erosion rates, and use high resolution images to place limits on vertical changes in the surface of the residual cap. We find the mass balance in Mars years 9-31 to be -6 to +4 km3/♂y, or roughly -0.039% to +0.026% of the mean atmospheric CO2 mass/♂y. The indeterminate sign results chiefly from uncertainty in the amounts of deposition or erosion on the upper surfaces of deposits (as opposed to scarp retreat). Erosion and net deposition in this period appear to be controlled by summertime planetary scale dust events, the largest occurring in MY 9, another, smaller one in MY 28. The rates of erosion and the deposition observed since MY 9 appear to be consistent with the types of deposits and erosional behavior found in most of the residual cap. However, small areas (100 ♂y) of depositional and/or erosional conditions different from those occurring in the period since MY 9, although these environmental differences could be subtle.

A Range Correction for Icesat and Its Potential Impact on Ice-sheet Mass Balance Studies

Science.gov (United States)

Borsa, A. A.; Moholdt, G.; Fricker, H. A.; Brunt, Kelly M.

2014-01-01

We report on a previously undocumented range error in NASA's Ice, Cloud and land Elevation Satellite (ICESat) that degrades elevation precision and introduces a small but significant elevation trend over the ICESat mission period. This range error (the Gaussian-Centroid or 'G-C'offset) varies on a shot-to-shot basis and exhibits increasing scatter when laser transmit energies fall below 20 mJ. Although the G-C offset is uncorrelated over periods less than1 day, it evolves over the life of each of ICESat's three lasers in a series of ramps and jumps that give rise to spurious elevation trends of -0.92 to -1.90 cm yr(exp -1), depending on the time period considered. Using ICESat data over the Ross and Filchner-Ronne ice shelves we show that (1) the G-C offset introduces significant biases in ice-shelf mass balance estimates, and (2) the mass balance bias can vary between regions because of different temporal samplings of ICESat.We can reproduce the effect of the G-C offset over these two ice shelves by fitting trends to sample-weighted mean G-C offsets for each campaign, suggesting that it may not be necessary to fully repeat earlier ICESat studies to determine the impact of the G-C offset on ice-sheet mass balance estimates.

Rates and time scales of clay-mineral formation by weathering in saprolitic regoliths of the southern Appalachians from geochemical mass balance

Science.gov (United States)

Jason R. Price; Michael A. Velbel; Lina C. Patino

2005-01-01

Rates of clay formation in three watersheds located at the Coweeta Hydrologic Laboratory, western North Carolina, have been determined from solute flux-based mass balance methods. A system of mass balance equations with enough equations and unknowns to allow calculation of secondary mineral formation rates as well as the more commonly determined primary-...

Role of deformed shell effects on the mass asymmetry in nuclear fission of mercury isotopes

International Nuclear Information System (INIS)

Panebianco, Stefano; Sida, Jean-Luc; Goutte, Heloise; Lemaitre, Jean-Francois; Dubray, Noel; Hilaire, Stephane

2012-01-01

Until now, the mass asymmetry in the nuclear fission process has been understood in terms of the strong influence of the nuclear structure of the nascent fragments. Recently, a surprising asymmetric fission has been discovered in the light mercury region and has been interpreted as the result of the influence of the nuclear structure of the parent nucleus, totally discarding the influence of the fragments' structure. To assess the role of the fragment shell effects in the mass asymmetry in this particular region, a scission-point model, based on a full energy balance between the two nascent fragments, has been developed using one of the best theoretical descriptions of microscopic nuclear structure. As for actinides, this approach shows that the asymmetric splitting of the Hg-180 nucleus and the symmetric one of Hg-198 can be understood on the basis of only the microscopic nuclear structure of the fragments at scission. (authors)

Geodetic Mass Balance of the Northern Patagonian Icefield from 2000 to 2012 Using Two Independent Methods

Directory of Open Access Journals (Sweden)

Inés Dussaillant

2018-02-01

Full Text Available We compare two independent estimates of the rate of elevation change and geodetic mass balance of the Northern Patagonian Icefield (NPI between 2000 (3,856 km2 and 2012 (3,740 km2 from space-borne data. The first is obtained by differencing the Shuttle Radar Topography Mission (SRTM digital elevation model (DEM from February 2000 and a Satellite pour l'Observation de la Terre 5 (SPOT5 DEM from March 2012. The second is deduced by fitting pixel-based linear elevation trends over 118 DEMs calculated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER stereo images acquired between 2000 and 2012. Both methods lead to similar and strongly negative icefield-wide mass balance rates of −1.02 ± 0.21 and −1.06 ± 0.14 m w.e. yr−1 respectively, which is in agreement with earlier studies. Contrasting glacier responses are observed, with individual glacier mass balance rates ranging from −0.15 to −2.30 m w.e. yr−1 (standard deviation = 0.49 m w.e. yr−1; N = 38. For individual glaciers, the two methods agree within error bars, except for small glaciers poorly sampled in the SPOT5 DEM due to clouds. Importantly, our study confirms the lack of penetration of the C-band SRTM radar signal into the NPI snow and firn except for a region above 2,900 m a.s.l. covering <1% of the total area. Ignoring penetration would bias the mass balance by only 0.005 m w.e. yr−1. A strong advantage of the ASTER method is that it relies only on freely available data and can thus be extended to other glacierized areas.

Multi-year analysis of distributed glacier mass balance modelling and equilibrium line altitude on King George Island, Antarctic Peninsula

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U. Falk

2018-04-01

Full Text Available The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP. This region was subject to strong warming trends in the atmospheric surface layer. Surface air temperature increased about 3 K in 50 years, concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. The positive trend in surface air temperature has currently come to a halt. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0 K (100 m−1 and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns. The increased mesocyclonic activity during the wintertime over the past decades in the study area results in intensified advection of warm, moist air with high temperatures and rain and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. Its impact on winter accumulation results in the observed negative mass balance estimates. Six years of continuous glaciological measurements on mass balance stake transects as well as 5 years of climatological data time series are presented and a spatially distributed glacier energy balance melt model adapted and run based on these multi-year data sets. The glaciological surface mass balance model is generally in good agreement with observations, except for atmospheric conditions promoting snow drift by high wind speeds, turbulence-driven snow deposition and snow layer erosion by rain. No drift in the difference between simulated mass balance and mass balance measurements can be seen over the course of the 5-year model run period. The winter accumulation does not suffice to compensate for the high variability in summer ablation. The results are analysed to assess changes in meltwater input to the coastal waters, specific glacier mass balance and the equilibrium line altitude (ELA. The

Changes in ice dynamics and mass balance of the Antarctic ice sheet.

Science.gov (United States)

Rignot, Eric

2006-07-15

The concept that the Antarctic ice sheet changes with eternal slowness has been challenged by recent observations from satellites. Pronounced regional warming in the Antarctic Peninsula triggered ice shelf collapse, which led to a 10-fold increase in glacier flow and rapid ice sheet retreat. This chain of events illustrated the vulnerability of ice shelves to climate warming and their buffering role on the mass balance of Antarctica. In West Antarctica, the Pine Island Bay sector is draining far more ice into the ocean than is stored upstream from snow accumulation. This sector could raise sea level by 1m and trigger widespread retreat of ice in West Antarctica. Pine Island Glacier accelerated 38% since 1975, and most of the speed up took place over the last decade. Its neighbour Thwaites Glacier is widening up and may double its width when its weakened eastern ice shelf breaks up. Widespread acceleration in this sector may be caused by glacier ungrounding from ice shelf melting by an ocean that has recently warmed by 0.3 degrees C. In contrast, glaciers buffered from oceanic change by large ice shelves have only small contributions to sea level. In East Antarctica, many glaciers are close to a state of mass balance, but sectors grounded well below sea level, such as Cook Ice Shelf, Ninnis/Mertz, Frost and Totten glaciers, are thinning and losing mass. Hence, East Antarctica is not immune to changes.

Using Terrain Analysis and Remote Sensing to Improve Snow Mass Balance and Runoff Prediction

Science.gov (United States)

Venteris, E. R.; Coleman, A. M.; Wigmosta, M. S.

2010-12-01

Approximately 70-80% of the water in the international Columbia River basin is sourced from snowmelt. The demand for this water has competing needs, as it is used for agricultural irrigation, municipal, hydro and nuclear power generation, and environmental in-stream flow requirements. Accurate forecasting of water supply is essential for planning current needs and prediction of future demands due to growth and climate change. A significant limitation on current forecasting is spatial and temporal uncertainty in snowpack characteristics, particularly snow water equivalent. Currently, point measurements of snow mass balance are provided by the NRCS SNOTEL network. Each site consists of a snow mass sensor and meteorology station that monitors snow water equivalent, snow depth, precipitation, and temperature. There are currently 152 sites in the mountains of Oregon and Washington. An important step in improving forecasts is determining how representative each SNOTEL site is of the total mass balance of the watershed through a full accounting of the spatiotemporal variability in snowpack processes. This variation is driven by the interaction between meteorological processes, land cover, and landform. Statistical and geostatistical spatial models relate the state of the snowpack (characterized through SNOTEL, snow course measurements, and multispectral remote sensing) to terrain attributes derived from digital elevation models (elevation, aspect, slope, compound topographic index, topographic shading, etc.) and land cover. Time steps representing the progression of the snow season for several meteorologically distinct water years are investigated to identify and quantify dominant physical processes. The spatially distributed snow balance data can be used directly as model inputs to improve short- and long-range hydrologic forecasts.

Chronologically matched toenail-Hg to hair-Hg ratio: temporal analysis within the Japanese community (U.S.

Directory of Open Access Journals (Sweden)

Hinners Thomas

2012-10-01

Full Text Available Abstract Background Toenail-Hg levels are being used as a marker of methylmercury (MeHg exposure in efforts to associate exposure with effects such as cardiovascular disease. There is a need to correlate this marker with more established biomarkers that presently underlie existing dose–response relationships in order to compare these relationships across studies. Methods As part of the Arsenic Mercury Intake Biometric Study, toenail clippings were collected at three time points over a period of one year amongst females from within the population of Japanese living near Puget Sound in Washington State (US. Variability in temporal intra-individual toenail-Hg levels was examined and chronologically matched hair and toenail samples were compared to more accurately define the toxicokinetic variability of Hg levels observed between the two compartments. Results Mean toenail-Hg values (n=43 for the 1st, 2nd and 3rd visits were 0.60, 0.60 and 0.56 ng/mg. Correlations were as follows: r=0.92 between 1st and 2nd clinic visits, r=0.75 between 1st and 3rd visits and r=0.87 between 2nd and 3rd visits. With few exceptions, toenail-Hg values from any visit were within 50-150% of the individual’s mean toenail-Hg level. Nearly all participants had less than a two-fold change in toenail-Hg levels across the study period. A regression model of the relationship between toenail-Hg and hair-Hg (n = 41 levels representing the same time period of exposure, gave a slope (Hg ng/mg of 2.79 for hair relative to toenail (r=0.954. Conclusions A chronologically matched hair-Hg to toenail-Hg ratio has been identified within a population that consumes fish regularly and in quantity. Intra-individual variation in toenail-Hg levels was less than two-fold and may represent dietary-based fluctuations in body burden for individuals consuming various fish species with different contaminant levels. The chronologically matched ratio will be useful for relating MeHg exposure and

Mass Balance Model, A study of contamination effects in AMS 14C sample analysis

NARCIS (Netherlands)

Prokopiou, Markella

2010-01-01

In this training thesis a background correction analysis, also known as mass balance model, was implemented to study the contamination effects in AMS 14C sample processing. A variety of backgrounds and standards with sizes ranging from 50 μg C to 1500 μg

Geodetic mass balance measurements on debris and clean-ice tropical glaciers in Ecuador

Science.gov (United States)

La Frenierre, J.; Decker, C. R.; Jordan, E.; Wigmore, O.; Hodge, B. E.; Niederriter, C.; Michels, A.

2017-12-01

Glaciers are recognized as highly sensitive indicators of climate change in high altitude, low latitude environments. In the tropical Andes, various analyses of glacier surface area change have helped illuminate the manifestation of climate change in this region, however, information about actual glacier mass balance behavior is much more limited given the relatively small glaciers, difficult access, poor weather, and/or limited local resources common here. Several new technologies, including aerial and terrestrial LIDAR and structure-from-motion photogrammetry using small unmanned aerial vehicles (UAVs), make mass balance measurements using geodetic approaches increasingly feasible in remote mountain locations, which can both further our understanding of changing climatic conditions, and improve our ability to evaluate the downstream hydrologic impacts of ice loss. At Volcán Chimborazo, Ecuador, these new technologies, combined with a unique, 5-meter resolution digital elevation model derived from 1997 aerial imagery, make possible an analysis of the magnitude and spatial patterns of mass balance behavior over the past two decades. Here, we evaluate ice loss between 1997 and 2017 at the tongues of two adjacent glaciers, one debris-covered and detached from its accumulation area (Reschreiter Glacier), and one debris-free and intact (Hans Meyer Glacier). Additionally, we incorporate data from 2012 and 2013 terrestrial LIDAR surveys to evaluate the behavior of the Reschreiter at a finer temporal resolution. We find that on the Hans Meyer, the mean surface deflation rate since 1997 at the present-day tongue has been nearly 3 m yr-1, while on the lower-elevation Reschreiter, the mean deflation rate has been approximately 1 m yr-1. However, the processes by which debris-covered ice becomes exposed results in highly heterogeneous patterns of ice loss, with some areas experiencing surface deflation rates approaching 15 m yr-1 when energy absorption is unimpeded.

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

CERN Document Server

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

1999-01-01

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

Mass Balance Reconstruction and Volumetric change of Stok Glaicer , Ladak Region, Western Himalyas,India (1969-2015)

Science.gov (United States)

Mohd, S.; AL, R.

2017-12-01

Understanding mass balance and volumetric change of glaciers are extremely important in areas where the majority of the population depends on cryospheric sources for the livelihood. Ladakh is one of the coldest and the aridest region of India. The majority of the population live in mountain pockets where the only source of water is snow and glacier melt for agriculture and domestic use. Stok village catchment (52 km2) has seven very small glaciers with an area ranging between 0.2-1.05 km2 at an elevation above 5300m a.s.l (GSI 2009). These glaciers contribute to a stream feeding Stok village of 274 ( 1469 individuals) households and a portion of Chuchot village before joining the Indus River. Ironically very limited studies have been carried out so far in this region, making it even more urgent to monitor the health of the glaciers in this region. With the changing climate, booming of the tourism industry and scarcity of water resources during the spring season, there is a shift in the livelihood of the region towards other option leading to a negative impact on the environment and over exploitation of natural resources. In this study we present analysis of measured annual mass balances for the period 2015-2017 and reconstruction of annual mass balances since 1969 to 2015 of Stok glacier located on the north eastern slope of Zanskar range in Ladakh region of western Himalayas. Direct glaciological methods were used to obtain annual mass balance for 2015-2017 and for reconstruction of annual mass balances, Classical Temperature Index model were used with the help of meteorological data from Indian Meteorological Department. The data gaps were filled with the help of several modelled datasets viz. HAR (High Asia Reanalysis), REMO, and Climate Research Unit (CRU) TS2.1 dataset. We also present catchment wide change in volume of the glaciers since 1969 to 2015. Declassified satellite images and Landsat images were used to obtain the change in volume of the glacier with

Mass balance for lead in the California South Coast Air Basin: An update

International Nuclear Information System (INIS)

Lankey, R.L.; Davidson, C.I.; McMichael, F.C.

1998-01-01

A mass balance for lead for the year 1989 in the South Coast Air Basin has inputs to the atmosphere of 600 ± 190 kg/day and outputs of 580 ± 160 kg/day, showing rough agreement. Stationary sources are responsible for only about 5% of the total lead emissions. The bulk of the lead is emitted from vehicles using leaded gasoline (37%) and unleaded gasoline (15%), as well as from resuspension of previously deposited lead on roads (43%). Over half of the total emitted lead deposits on roads and nearby soil, while about one-third is carried out of the basin by wind. A small amount, less than 10%, is deposited on surfaces throughout the basin. These percentages are approximately the same as those in a mass balance for the same region calculated for 1972, when lead emissions from leaded gasoline were about a factor of 70 greater than leaded gas emissions in 1989. When the lead emissions re used as inputs o a simple continuously stirred flow reactor model for the basin, reasonable, agreement is obtained between calculated and measured concentrations

Balance model of masses for mercury and cyanide in the Surata River

International Nuclear Information System (INIS)

Amaya S, Cesar Jovane

2004-01-01

The pattern of masses balance consists of a comparison through the time of pollutants quantity (mercury and cyanide) poured in the mining region of Vetas and California, with the values of these same pollutants detected in the Bosconia plant of the metropolitan aqueduct of Bucaramanga. The mercury and the cyanide are used in the mining region for the gold benefit and they already arrive as residuals to the air sources and to the water that arrives to Surata River, one of the sources of supply of drinkable water of the aqueduct. In the gold benefit in the region, two different groups work:; the mining companies and the barrileros. The barrileros is particular people that work mainly the amalgamation of the mineral in barrels, and they discard their residuals to the environment, the same as the mining companies. The mining companies of California pour their residuals in the gulch La Baja, above of the monitoring point LB-01 (Round Hill) of the CDMB; as long as the mining companies of Vetas, pour them above of the monitoring point RV-05 (Borrero) also of the CDMB, to the River Vetas. Few data exist on the used of mercury and cyanide quantities through the time for the mining companies and the barrileros. In the monitored points of the CDMB, RV-02 and LB-01 (Round Hill), it is had temporary registrations of so much of concentrations of mercury and total cyanide in the water, as well as of flows. In the plant Bosconia registers concentrations of mercury and cyanide in the water of the Surata River every two hours daily, as long as the data of flows are measured in the point MA-01 (Majadas) By means of the flow multiplication and concentration they can register the masses of mercury and cyanide that happen at one time determined by the sampling points. A very simple balance of masses is obtained measuring in the different sampling points the masses of mercury and cyanide poured in the mining region. In the ideal case all the data required should exist in with a high

Evidence of Hg-chain formation in HgxTiS2: a 199mHg-TDPAC study

International Nuclear Information System (INIS)

Troeger, W.; Butz, T.; Ouvrard, G.

1993-01-01

We determined the 199m Hg nuclear quadrupole interaction in the ''misfit'' or ''superstoichiometric'' compound Hg x TiS 2 by time differential perturbed angular correlation. A unique Hg-site with ν Q = 511(1) MHz and η = 0.410(4) was observed, irrespective of the Hg-uptake (2/3 ≤ x ≤ 4/3). We propose a model of Hg-Hg zig-zag chains which accounts for these observations as well as for the X-ray diffraction data. (orig.)

Radar Interferometry Studies of the Mass Balance of Polar Ice Sheets

Science.gov (United States)

Rignot, Eric (Editor)

1999-01-01

The objectives of this work are to determine the current state of mass balance of the Greenland and Antarctic Ice Sheets. Our approach combines different techniques, which include satellite synthetic-aperture radar interferometry (InSAR), radar and laser altimetry, radar ice sounding, and finite-element modeling. In Greenland, we found that 3.5 times more ice flows out of the northern part of the Greenland Ice Sheet than previously accounted for. The discrepancy between current and past estimates is explained by extensive basal melting of the glacier floating sections in the proximity of the grounding line where the glacier detaches from its bed and becomes afloat in the ocean. The inferred basal melt rates are very large, which means that the glaciers are very sensitive to changes in ocean conditions. Currently, it appears that the northern Greenland glaciers discharge more ice than is being accumulated in the deep interior, and hence are thinning. Studies of temporal changes in grounding line position using InSAR confirm the state of retreat of northern glaciers and suggest that thinning is concentrated at the lower elevations. Ongoing work along the coast of East Greenland reveals an even larger mass deficit for eastern Greenland glaciers, with thinning affecting the deep interior of the ice sheet. In Antarctica, we found that glaciers flowing into a large ice shelf system, such as the Ronne Ice Shelf in the Weddell Sea, exhibit an ice discharge in remarkable agreement with mass accumulation in the interior, and the glacier grounding line positions do not migrate with time. Glaciers flowing rapidly into the Amudsen Sea, unrestrained by a major ice shelf, are in contrast discharging more ice than required to maintain a state of mass balance and are thinning quite rapidly near the coast. The grounding line of Pine Island glacier (see diagram) retreated 5 km in 4 years, which corresponds to a glacier thinning rate of 3.5 m/yr. Mass imbalance is even more negative

A Theoretical Study of the Oxidation of Hg0 to HgBr2 in the Troposphere

DEFF Research Database (Denmark)

Goodsite, M. E.; Plane, J. M C; Skov, H.

2004-01-01

The oxidation of elemental mercury (Hg0) to the divalent gaseous mercury dibromide (HgBr2) has been proposed to account for the removal of Hg0 during depletion events in the springtime Arctic. The mechanism of this process is explored in this paper by theoretical calculations of the relevant rate...... coefficients. Rice-Ramsberger-Kassel-Marcus (RRKM) theory, together with ab initio quantum calculations where required, are used to estimate the following: recombination rate coefficients of Hg with Br, I, and O; the thermal dissociation rate coefficient of HgBr; and the recombination rate coefficients of Hg......Br with Br, I, OH, and O2. A mechanism based on the initial recombination of Hg with Br, followed by the addition of a second radical (Br, I, or OH) in competition with thermal dissociation of HgBr, is able to account for the observed rate of Hg 0 removal, both in Arctic depletion events and at lower...

Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions

Energy Technology Data Exchange (ETDEWEB)

Chen, Wei-Ni [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Jiang, Shiuh-Jen, E-mail: sjjiang@faculty.nsysu.edu.tw [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Chen, Yen-Ling [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Sahayam, A.C. [National Centre for Compositional Characterisation of Materials (CCCM), Hyderabad (India)

2015-02-20

Highlights: • Determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions in a single run. • Accurate analysis using isotope dilution and standard addition methods. • Vapor generation ICP-MS yielded superior detection limits compared to ETV-ICP-MS. • No sample dissolution increased sample through put. • Analysis of GBW09305 Cosmetic (Cream) reference material for accuracy. - Abstract: A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v L-cysteine, 0.5 μg mL{sup −1} Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng g{sup −1} for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample.

Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions

International Nuclear Information System (INIS)

Chen, Wei-Ni; Jiang, Shiuh-Jen; Chen, Yen-Ling; Sahayam, A.C.

2015-01-01

Highlights: • Determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions in a single run. • Accurate analysis using isotope dilution and standard addition methods. • Vapor generation ICP-MS yielded superior detection limits compared to ETV-ICP-MS. • No sample dissolution increased sample through put. • Analysis of GBW09305 Cosmetic (Cream) reference material for accuracy. - Abstract: A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v L-cysteine, 0.5 μg mL −1 Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng g −1 for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample

Mass, Energy, Entropy and Exergy Rate Balance in a Ranque-Hilsh Vortex Tube

Science.gov (United States)

Carrascal Lecumberri, Edorta; Sala Lizarraga, José María

2013-01-01

The objective of this paper is to present a laboratory program designed for the Thermodynamics course offered in the Department of Thermal Engineering at the University of the Basque Country. With reference to one of the examples given in the textbook by Moran, Shapiro, Boettner and Bailey (2012), the balances of mass, energy, entropy and exergy…

Effect of thermal mass on life cycle primary energy balances of a concrete- and a wood-frame building

International Nuclear Information System (INIS)

Dodoo, Ambrose; Gustavsson, Leif; Sathre, Roger

2012-01-01

Highlights: ► The effect of thermal mass on life cycle primary energy balance of concrete and wood building is analyzed. ► A concrete building has slightly lower space heating demand than a wood alternative. ► Still, a wood building has a lower life cycle primary energy use than a concrete alternative. ► The influence of thermal mass on space heating energy use for buildings in Nordic climate is small. -- Abstract: In this study we analyze the effect of thermal mass on space heating energy use and life cycle primary energy balances of a concrete- and a wood-frame building. The analysis includes primary energy use during the production, operation, and end-of-life phases. Based on hour-by-hour dynamic modeling of heat flows in building mass configurations we calculate the energy saving benefits of thermal mass during the operation phase of the buildings. Our results indicate that the energy savings due to thermal mass is small and varies with the climatic location and energy efficiency levels of the buildings. A concrete-frame building has slightly lower space heating demand than a wood-frame alternative, due to the higher thermal mass of concrete-based materials. Still, a wood-frame building has a lower life cycle primary energy balance than a concrete-frame alternative. This is due primarily to the lower production primary energy use and greater bioenergy recovery benefits of the wood-frame buildings. These advantages outweigh the energy saving benefits of thermal mass. We conclude that the influence of thermal mass on space heating energy use for buildings located in Nordic climate is small and that wood-frame buildings with cogeneration based district heating would be an effective means of reducing primary energy use in the built environment.

Mass Balance Evolution of Black Rapids Glacier, Alaska, 1980–2100, and Its Implications for Surge Recurrence

Directory of Open Access Journals (Sweden)

Christian Kienholz

2017-07-01

Full Text Available Surge-type Black Rapids Glacier, Alaska, has undergone strong retreat since it last surged in 1936–1937. To assess its evolution during the late Twentieth and Twenty-first centuries and determine potential implications for surge likelihood, we run a simplified glacier model over the periods 1980–2015 (hindcasting and 2015–2100 (forecasting. The model is forced by daily temperature and precipitation fields, with downscaled reanalysis data used for the hindcasting. A constant climate scenario and an RCP 8.5 scenario based on the GFDL-CM3 climate model are employed for the forecasting. Debris evolution is accounted for by a debris layer time series derived from satellite imagery (hindcasting and a parametrized debris evolution model (forecasting. A retreat model accounts for the evolution of the glacier geometry. Model calibration, validation and parametrization rely on an extensive set of in situ and remotely sensed observations. To explore uncertainties in our projections, we run the glacier model in a Monte Carlo fashion, varying key model parameters and input data within plausible ranges. Our results for the hindcasting period indicate a negative mass balance trend, caused by atmospheric warming in the summer, precipitation decrease in the winter and surface elevation lowering (climate-elevation feedback, which exceed the moderating effects from increasing debris cover and glacier retreat. Without the 2002 rockslide deposits on Black Rapids' lower reaches, the mass balances would be more negative, by ~20% between the 2003 and 2015 mass-balance years. Despite its retreat, Black Rapids Glacier is substantially out of balance with the current climate. By 2100, ~8% of Black Rapids' 1980 area are projected to vanish under the constant climate scenario and ~73% under the RCP 8.5 scenario. For both scenarios, the remaining glacier portions are out of balance, suggesting continued retreat after 2100. Due to mass starvation, a surge in the Twenty

Distinct toxicological characteristics and mechanisms of Hg2+ and MeHg in Tetrahymena under low concentration exposure.

Science.gov (United States)

Liu, Cheng-Bin; Qu, Guang-Bo; Cao, Meng-Xi; Liang, Yong; Hu, Li-Gang; Shi, Jian-Bo; Cai, Yong; Jiang, Gui-Bin

2017-12-01

Inorganic divalent mercury complexes (Hg 2+ ) and monomethylmercury complexes (MeHg) are the main mercury species in aquatic systems and their toxicity to aquatic organisms is of great concern. Tetrahymena is a type of unicellular eukaryotic protozoa located at the bottom of food chain that plays a fundamental role in the biomagnification of mercury. In this work, the dynamic accumulation properties, toxicological characteristics and mechanisms of Hg 2+ and MeHg in five Tetrahymena species were evaluated in detail. The results showed that both Hg 2+ and MeHg were ingested and exhibited inhibitory effects on the proliferation or survival of Tetrahymena species. However, the ingestion rate of MeHg was significantly higher than that of Hg 2+ . The mechanisms responsible for the toxicity of MeHg and Hg 2+ were different, although both chemicals altered mitochondrial membrane potential (MMP). MeHg disrupted the integrity of membranes while Hg 2+ had detrimental effects on Tetrahymena as a result of the increased generation of reactive oxygen species (ROS). In addition, the five Tetrahymena species showed different capacities in accumulating Hg 2+ and MeHg, with T. corlissi exhibiting the highest accumulations. The study also found significant growth-promoting effect on T. corlissi under low concentration exposure (0.003 and 0.01μg Hg/mL (15 and 50nM)), suggesting different effect and mechanism that should be more closely examined when assessing the bioaccumulation and toxicity of mercury in aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification of the one-quadrupole phonon 21,ms+ state of 204Hg

Directory of Open Access Journals (Sweden)

R. Stegmann

2017-07-01

Full Text Available One-phonon states of vibrational nuclei with mixed proton–neutron symmetry have been observed throughout the nuclear chart besides the mass A≈200 region. Very recently, it has been proposed that the 22+ state of 212Po is of isovector nature. This nucleus has two valence protons and two valence neutrons outside the doubly-magic 208Pb nucleus. The stable isotope 204Hg, featuring two valence-proton and valence-neutron holes, with respect to 208Pb, is the particle-hole mirror of 212Po. In order to compare the properties of low-lying isovector excitations in these particle-hole mirror nuclei, we have studied 204Hg by using the projectile Coulomb-excitation technique. The measured absolute B(M1;22+→21+ strength of 0.20(2μN2 indicates that the 22+ level of 204Hg is at least the main fragment of the 21,ms+ state. For the first time in this mass region, both lowest-lying, one-quadrupole phonon excitations are established together with the complete set of their decay strengths. This allows for a microscopic description of their structures, achieved in the framework of the Quasi-particle Phonon Model.

Hg and Pt-metals in meteorite carbon-rich residues - Suggestions for possible host phase for Hg

Science.gov (United States)

Jovanovic, S.; Reed, G. W., Jr.

1980-01-01

Carbon-rich and oxide residual phases have been isolated from Allende and Murchison by acid demineralization for the determination of their Hg, Pt-metal, Cr, Sc, Co, and Fe contents. Experimental procedures used eliminated the possibility of exogenous and endogenous contaminant trace elements from coprecipitating with the residues. Large enrichments of Hg and Pt-metals were found in Allende but not in Murchison residues. Hg-release profiles from stepwise heating experiments suggest a sulfide as the host for Hg. Diffusion calculations for Hg based on these experiments indicate an activation energy of 7-8 kcal/mol, the same as that for Hg in troilite from an iron meteorite. This is further support for a sulfide host phase for Hg. Equilibration of Hg with this phase at approximately 900 K is indicated. Reasons for the presence of Pt-metals in noncosmic relative abundances are explored.

Surface Energy and Mass Balance Model for Greenland Ice Sheet and Future Projections

Science.gov (United States)

Liu, Xiaojian

The Greenland Ice Sheet contains nearly 3 million cubic kilometers of glacial ice. If the entire ice sheet completely melted, sea level would raise by nearly 7 meters. There is thus considerable interest in monitoring the mass balance of the Greenland Ice Sheet. Each year, the ice sheet gains ice from snowfall and loses ice through iceberg calving and surface melting. In this thesis, we develop, validate and apply a physics based numerical model to estimate current and future surface mass balance of the Greenland Ice Sheet. The numerical model consists of a coupled surface energy balance and englacial model that is simple enough that it can be used for long time scale model runs, but unlike previous empirical parameterizations, has a physical basis. The surface energy balance model predicts ice sheet surface temperature and melt production. The englacial model predicts the evolution of temperature and meltwater within the ice sheet. These two models can be combined with estimates of precipitation (snowfall) to estimate the mass balance over the Greenland Ice Sheet. We first compare model performance with in-situ observations to demonstrate that the model works well. We next evaluate how predictions are degraded when we statistically downscale global climate data. We find that a simple, nearest neighbor interpolation scheme with a lapse rate correction is able to adequately reproduce melt patterns on the Greenland Ice Sheet. These results are comparable to those obtained using empirical Positive Degree Day (PDD) methods. Having validated the model, we next drove the ice sheet model using the suite of atmospheric model runs available through the CMIP5 atmospheric model inter-comparison, which in turn built upon the RCP 8.5 (business as usual) scenarios. From this exercise we predict how much surface melt production will increase in the coming century. This results in 4-10 cm sea level equivalent, depending on the CMIP5 models. Finally, we try to bound melt water

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

Energy Technology Data Exchange (ETDEWEB)

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

2006-10-27

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

Mass-balance modelling results of groundwater data collected at Olkiluoto over the period 2004-2007

International Nuclear Information System (INIS)

Partamies, S.; Pitkaenen, P.

2014-02-01

Olkiluoto has been selected as a repository site for final disposal of spent nuclear waste produced in Finland. An understanding of the hydrogeochemical groundwater conditions and their evolution is essential in evaluating the long-term safety of the repository. The performance of technical barriers and the migration of potentially released radionuclides depend on the chemical conditions. A prerequisite for understanding these factors is the ability to specify the water-rock interactions, which control chemical conditions in the groundwater. The objective of this study is to present mass-balance studies of the samples collected over the period 2004 - 2007. A total of 178 groundwater samples have been collected over this period (84 groundwater observation tubes, 88 from deep multipackered boreholes and 6 from the ONKALO) which provided a comprehensive dataset on dissolved chemical species and isotopes. The PHREEQC program was used in the mass-balance calculations in order to develop geochemical interpretations of water-rock interactions, isotope-chemical evolution and the mixing of palaeowater types. A model of the hydrogeochemical evolution in different parts of the crystalline bedrock at Olkiluoto has been created and the significance of chemical reactions and groundwater mixing along different flow paths calculated. The changes in hydrogeochemical interpretations and chemical and isotopic calculations indicate that pH seems to be dominantly controlled by thermodynamic equilibrium with calcite in fractures and there are indications that this process may also occur in the overburden layer. Oxic redox conditions, prevailing in recharging groundwater, change abruptly to sulphidic conditions close to the surface, generally in the overburden. The results from the mass-balance calculations correspond and support the earlier conceptions of groundwater mixing, the origin of salinity and the hydrogeochemical evolution. The fractions of glacial meltwater indicated in these

Mass-balance modelling results of groundwater data collected at Olkiluoto over the period 2004-2007

Energy Technology Data Exchange (ETDEWEB)

Partamies, S. [VTT Technical Research Centre of Finland, Espoo (Finland); Pitkaenen, P.

2014-02-15

Olkiluoto has been selected as a repository site for final disposal of spent nuclear waste produced in Finland. An understanding of the hydrogeochemical groundwater conditions and their evolution is essential in evaluating the long-term safety of the repository. The performance of technical barriers and the migration of potentially released radionuclides depend on the chemical conditions. A prerequisite for understanding these factors is the ability to specify the water-rock interactions, which control chemical conditions in the groundwater. The objective of this study is to present mass-balance studies of the samples collected over the period 2004 - 2007. A total of 178 groundwater samples have been collected over this period (84 groundwater observation tubes, 88 from deep multipackered boreholes and 6 from the ONKALO) which provided a comprehensive dataset on dissolved chemical species and isotopes. The PHREEQC program was used in the mass-balance calculations in order to develop geochemical interpretations of water-rock interactions, isotope-chemical evolution and the mixing of palaeowater types. A model of the hydrogeochemical evolution in different parts of the crystalline bedrock at Olkiluoto has been created and the significance of chemical reactions and groundwater mixing along different flow paths calculated. The changes in hydrogeochemical interpretations and chemical and isotopic calculations indicate that pH seems to be dominantly controlled by thermodynamic equilibrium with calcite in fractures and there are indications that this process may also occur in the overburden layer. Oxic redox conditions, prevailing in recharging groundwater, change abruptly to sulphidic conditions close to the surface, generally in the overburden. The results from the mass-balance calculations correspond and support the earlier conceptions of groundwater mixing, the origin of salinity and the hydrogeochemical evolution. The fractions of glacial meltwater indicated in these

Uncertainty of solute flux estimation in ungauged small streams: potential implications for input-output nutrient mass balances at stream reach scale

Directory of Open Access Journals (Sweden)

A. Butturini

2005-01-01

Full Text Available Input-output mass balances within stream reaches provide in situ estimates of stream nutrient retention/release under a wide spectrum of hydrological conditions. Providing good estimates of the mass balances for nutrients depends on precise hydrological monitoring and good chemical characterisation of stream water at the input and output ends of the stream reach. There is a need to optimise the hydrological monitoring and the frequencies of water sampling to yield precise annual mass balances, so as to avoid undue cost - high resolution monitoring and subsequent chemical analysis can be labour intensive and costly. In this paper, simulation exercises were performed using a data set created to represent the instantaneous discharge and solute dynamics at the input and output ends of a model stream reach during a one year period. At the output end, stream discharge and water chemistry were monitored continuously, while the input end was assumed to be ungauged; water sampling frequency was changed arbitrarily. Instantaneous discharge at the ungauged sampling point was estimated with an empirical power model linking the discharge to the catchment area (Hooper, 1986. The model thus substitutes for the additional gauge station. Simulations showed that 10 days was the longest chemical sampling interval which could provide reach annual mass balances of acceptable precision. Presently, the relationship between discharge and catchment area is usually assumed to be linear but simulations indicate that small departures from the linearity of this relationship could cause dramatic changes in the mass balance estimations.

Determination of equilibrium phase composition in the Hg-HgTe-CdTe system by ''dew point'' method

International Nuclear Information System (INIS)

Vanyukov, A.V.; Krotov, I.I.; Ermakov, A.I.

1978-01-01

Using the ''dew point'' method a study has been made of the equilibrium composition of the solid and liquid phases in the Hg-HgTe-CdTe system at 404, 435 and 454 deg C. It has been pointed out that crystallization of cadmium-rich solid solutions of Cdsub(x)Hgsub(1-x) Te takes place from a liquid phase with a much higher concentration of Hg. The activity of Hg in the liquid phase increases along the liquidus isotherm in the direction from section Hg-HgTe to section HgCdTe in accordance with the increase of its concentration. An increase in activity of Hg in the solid phase of Cdsub(x)Hgsub(1-x)Te has been noted with the reduction of its concentration

Regional Modeling of Dust Mass Balance and Radiative Forcing over East Asia using WRF-Chem

Energy Technology Data Exchange (ETDEWEB)

Chen, Siyu; Zhao, Chun; Qian, Yun; Leung, Lai-Yung R.; Huang, J.; Huang, Zhongwei; Bi, Jianrong; Zhang, Wu; Shi, Jinsen; Yang, Lei; Li, Deshuai; Li, Jinxin

2014-12-01

The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and radiative forcing. A variety of measurements from in-stu and satellite observations have been used to evaluate simulation results. Generally, WRF-Chem reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions of East Asia. We investigate the dust lifecycle and the factors that control the seasonal and spatial variations of dust mass balance and radiative forcing over the seven sub-regions of East Asia, i.e. source regions, the Tibetan Plateau, Northern China, Southern China, the ocean outflow region, and Korea-Japan regions. Results show that, over the source regions, transport and dry deposition are the two dominant sinks. Transport contributes to ~30% of the dust sink over the source regions. Dust results in a surface cooling of up to -14 and -10 W m-2, atmospheric warming of up to 20 and 15 W m-2, and TOA cooling of -5 and -8 W m-2 over the two major dust source regions of East Asia, respectively. Over the Tibetan Plateau, transport is the dominant source with a peak in summer. Over identified outflow regions, maximum dust mass loading in spring is contributed by the transport. Dry and wet depositions are the comparably dominant sinks, but wet deposition is larger than dry deposition over the Korea-Japan region, particularly in spring (70% versus 30%). The WRF-Chem simulations can generally capture the measured features of dust aerosols and its radaitve properties and dust mass balance over East Asia, which provides confidence for use in further investigation of dust impact on climate over East Asia.

R-2HG Exhibits Anti-tumor Activity by Targeting FTO/m6A/MYC/CEBPA Signaling.

Science.gov (United States)

Su, Rui; Dong, Lei; Li, Chenying; Nachtergaele, Sigrid; Wunderlich, Mark; Qing, Ying; Deng, Xiaolan; Wang, Yungui; Weng, Xiaocheng; Hu, Chao; Yu, Mengxia; Skibbe, Jennifer; Dai, Qing; Zou, Dongling; Wu, Tong; Yu, Kangkang; Weng, Hengyou; Huang, Huilin; Ferchen, Kyle; Qin, Xi; Zhang, Bin; Qi, Jun; Sasaki, Atsuo T; Plas, David R; Bradner, James E; Wei, Minjie; Marcucci, Guido; Jiang, Xi; Mulloy, James C; Jin, Jie; He, Chuan; Chen, Jianjun

2018-01-11

R-2-hydroxyglutarate (R-2HG), produced at high levels by mutant isocitrate dehydrogenase 1/2 (IDH1/2) enzymes, was reported as an oncometabolite. We show here that R-2HG also exerts a broad anti-leukemic activity in vitro and in vivo by inhibiting leukemia cell proliferation/viability and by promoting cell-cycle arrest and apoptosis. Mechanistically, R-2HG inhibits fat mass and obesity-associated protein (FTO) activity, thereby increasing global N 6 -methyladenosine (m 6 A) RNA modification in R-2HG-sensitive leukemia cells, which in turn decreases the stability of MYC/CEBPA transcripts, leading to the suppression of relevant pathways. Ectopically expressed mutant IDH1 and S-2HG recapitulate the effects of R-2HG. High levels of FTO sensitize leukemic cells to R-2HG, whereas hyperactivation of MYC signaling confers resistance that can be reversed by the inhibition of MYC signaling. R-2HG also displays anti-tumor activity in glioma. Collectively, while R-2HG accumulated in IDH1/2 mutant cancers contributes to cancer initiation, our work demonstrates anti-tumor effects of 2HG in inhibiting proliferation/survival of FTO-high cancer cells via targeting FTO/m 6 A/MYC/CEBPA signaling. Copyright © 2017 Elsevier Inc. All rights reserved.

Variation of the mean square amplitude with concentration in Hg1-xCdxTe

International Nuclear Information System (INIS)

Sadaiyandi, K.; Ramachandran, K.

1989-01-01

The mean square displacements (MSD) of Hg and Te in the mixed system Hg 1-x Cd x Te have been calculated for various concentrations of Cd atoms (x = 0.20, 0.40, 0.60, 0.80, 1.00) at 4, 77, and 300 K by means of the virtual crystal approximation. An unusual trend in MSD is found for x below 0.2: the higher mass has higher value of MS amplitude

Transdermal administration of radiolabelled [14C]rotigotine by a patch formulation: A mass balance trial

NARCIS (Netherlands)

Cawello, W.; Wolff, H.M.; Meuling, W.J.A.; Horstmann, R.; Braun, M.

2007-01-01

Background and objective: The dopamine agonist rotigotine has been formulated in a silicone-based transdermal system for once-daily administration. The objective of the present study was to characterise the mass balance of rotigotine in humans after administration of a single transdermal patch

The changing impact of snow conditions and refreezing on the mass balance of an idealized Svalbard glacier

Directory of Open Access Journals (Sweden)

Ward Van Pelt

2016-11-01

Full Text Available Glacier surface melt and runoff depend strongly on seasonal and perennial snow (firn conditions. Not only does the presence of snow and firn directly affect melt rates by reflecting solar radiation, it may also act as a buffer against mass loss by storing melt water in refrozen or liquid form. In Svalbard, ongoing and projected amplified climate change with respect to the global mean change has severe implications for the state of snow and firn and its impact on glacier mass loss. Model experiments with a coupled surface energy balance - firn model were done to investigate the surface mass balance and the changing role of snow and firn conditions for an idealized Svalbard glacier. A climate forcing for the past, present and future (1984-2104 is constructed, based on observational data from Svalbard Airport and a seasonally dependent projection scenario. Results illustrate ongoing and future firn degradation in response to an elevational retreat of the equilibrium line altitude (ELA of 31 m decade−1. The temperate firn zone is found to retreat and expand, while cold ice in the ablation zone warms considerably. In response to pronounced winter warming and an associated increase in winter rainfall, the current prevalence of refreezing during the melt season gradually shifts to the winter season in a future climate. Sensitivity tests reveal that in a present and future climate the density and thermodynamic structure of Svalbard glaciers are heavily influenced by refreezing. Refreezing acts as a net buffer against mass loss. However, the net mass balance change after refreezing is substantially smaller than the amount of refreezing itself, which can be ascribed to melt-enhancing effects after refreezing, which partly offset the primary mass-retaining effect of refreezing.

Balance Mass Flux and Velocity Across the Equilibrium Line in Ice Drainage Systems of Greenland

Science.gov (United States)

Zwally, H. Jay; Giovinetto, Mario B.; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Estimates of balance mass flux and the depth-averaged ice velocity through the cross-section aligned with the equilibrium line are produced for each of six drainage systems in Greenland. (The equilibrium line, which lies at approximately 1200 m elevation on the ice sheet, is the boundary between the area of net snow accumulation at higher elevations and the areas of net melting at lower elevations around the ice sheet.) Ice drainage divides and six major drainage systems are delineated using surface topography from ERS (European Remote Sensing) radar altimeter data. The net accumulation rate in the accumulation zone bounded by the equilibrium line is 399 Gt/yr and net ablation rate in the remaining area is 231 Gt/yr. (1 GigaTon of ice is 1090 kM(exp 3). The mean balance mass flux and depth-averaged ice velocity at the cross-section aligned with the modeled equilibrium line are 0.1011 Gt kM(exp -2)/yr and 0.111 km/yr, respectively, with little variation in these values from system to system. The ratio of the ice mass above the equilibrium line to the rate of mass output implies an effective exchange time of approximately 6000 years for total mass exchange. The range of exchange times, from a low of 3 ka in the SE drainage system to 14 ka in the NE, suggests a rank as to which regions of the ice sheet may respond more rapidly to climate fluctuations.

Mercury stable isotope fractionation in a tropical ecosystem including human hair: New insights for an isotope balance

Science.gov (United States)

Laffont, Laure; Sonke, Jeroen; Maurice, Laurence; Behra, Philippe

2010-05-01

Mercury contamination is an environmental problem in the Amazon basin still relevant today as impacts on human health are poorly studied. In Bolivia, indigenous people have elevated methylmercury concentrations (between 2719 and 23701 ng.g-1) in their hair. This highly toxic molecule is formed after methylation of inorganic Hg released by chemical and physical weathering and from human activities. The aim of our study is to propose a first isotope balance in a Bolivian Amazon ecosystem, through variations in Hg isotopic compositions. The discovery of mass-independent fracionation (MIF) of odd-isotopes in our organic samples (fish and human hair) opened a new way of research in tracing the sources and the processes involved in the cycle of Hg. Four types of samples are studied: liquid Hg0 from gold mining, sediment samples, fish coming from the Beni River basin (from the main channel and an associated floodplain lake) and hair from gold miners and fish-eating native populations. Hg isotopic compositions were analyzed on a Thermo-Finnigan Neptune MC-ICP-MS at the LMTG after sample digestion by HCl/HNO3 or by H2O2/HNO3 for fish samples, at 120°C. The δ202Hg values (relative to NIST 3133) are signicantly different with respect to the external precision on UM-Almaden#2 of 0.18 ‰ (2σ, n = 42): -0.34 ± 0.02 ‰ for liquid mercury, between -1.33 and -0.81 ‰ for bottom and floodplain sediments (n=18), between -0.87 and 2.22 ‰ for miners hair (n=26), +1.29 ± 0.41 ‰ for native hair (n=13) and between -0.91 and -0.21 ‰ for fish samples (n=53). A large mass-independent isotope fractionation (MIF) was observed for odd isotope ratios in all hair samples and fish samples whereas weak anomalies were measured for sediment samples: - ∆199Hg anomaly: -0.12 to -0.04 ‰ for sediment, -0.22 to +0.63 ‰ for fish samples and +0.13 to +1.63 ‰ for hair - ∆201Hg anomaly: -0.12 to -0.02 ‰ for sediment, -0.21 to +0.43 ‰ for fish samples and +0.06 to +1.25 ‰ for hair

Analysis of High Resolution Satellite imagery to acsees Glacier Mass Balance and Lake Hazards in Sikkim Himalayas

Science.gov (United States)

Bhushan, S.; Shean, D. E.; Haritashya, U. K.; Arendt, A. A.; Syed, T. H.; Setiawan, L.

2017-12-01

Glacial lake outburst floods can impact downstream communities due to the sudden outflux of huge quantities of stored water. In this study, we develop a hazard assessment of the moraine dammed glacial lakes in Sikkim Himalayas by analyzing the morphometry of proglacial features, and the surface velocity and mass balance of glaciers. We generated high-resolution digital elevation models (DEMs) using the open-source NASA Ames Stereo Pipeline (ASP) and use other open-source tools to calculate surface velocity and patterns of glacier downwasting over time. Geodetic glacier mass balance is obtained for three periods using high-resolution WorldView/GeoEye stereo DEMs (8 m posting, 2014-2016), Cartosat-1 stereo DEMs (10 m, 2006-2008) and SRTM (30 m, 2000). Initial results reveal a region-wide mass balance of -0.31±0.13 m w.eq.a-1 for the 2007-2015 period, with some debris covered glaciers showing a very low mass loss rate. Additionally, 12 annual glacier velocity fields spanning from 1991 to 2017.derived from Landsat imagery are used to explore the relationship between glacier dynamics and changes in proglacial lakes. Multi-temporal glacial lake mapping is conducted using Landsat and Cartosat imagery. Avalanche and rockfall modeling are combined with morphometric analysis of the proglacial lake area to assess the likelihood of glacial lake dam failure. The above parameters are integrated into a decision tree approach enabling categorization of moraine-dammed lakes according to their potential for outburst events.

Application of the stable-isotope system to the study of sources and fate of Hg in the environment: A review

International Nuclear Information System (INIS)

Yin Runsheng; Feng Xinbin; Shi Wenfang

2010-01-01

With the improvement of analytical methods and the development of multiple-collector inductively coupled plasma-mass spectrometry (MC-ICP/MS), research on non-traditional stable isotope (Cu, Zn, Fe, Se, Mo, Cr, Hg) in geochemistry has made tremendous progress in the past decade. Recent studies have demonstrated that both organic and inorganic reactions may cause Hg isotope fractionation, and variations of Hg isotopic composition in the environment have been successfully employed to explain Hg pollution history, Hg sources and tracking Hg pathways in nature. Furthermore, Hg isotopic fractionation studies can be a powerful tool in the calibration of global Hg cycling models. Stable isotope geochemistry of Hg is therefore becoming a new frontier subject in earth sciences. Based on summarizing previous research, this paper outlines the main advances in the study of Hg stable isotopes with particular emphasis placed on a brief explanation of Hg isotope analytical techniques, possible Hg isotope fractionation mechanisms observed in both natural and experimental processes, Hg isotope composition variations in different environmental matrices, and the application prospects of the Hg stable isotopes in environmental geosciences.

The mercury chromates Hg6Cr2O9 and Hg6Cr2O10-Preparation and crystal structures, and thermal behaviour of Hg6Cr2O9

International Nuclear Information System (INIS)

Weil, Matthias; Stoeger, Berthold

2006-01-01

The basic mercury(I) chromate(VI), Hg 6 Cr 2 O 9 (=2Hg 2 CrO 4 .Hg 2 O), has been obtained under hydrothermal conditions (200deg. C, 5 days) in the form of orange needles as a by-product from reacting elemental mercury and K 2 Cr 2 O 7 . Hydrothermal treatment of microcrystalline Hg 6 Cr 2 O 9 in demineralised water at 200deg. C for 3 days led to crystal growth of red crystals of the basic mercury(I, II) chromate(VI), Hg 6 Cr 2 O 10 (=2Hg 2 CrO 4 .2HgO). The crystal structures were solved and refined from single crystal X-ray data sets. Hg 6 Cr 2 O 9 : space group P2 1 2 1 2 1 , Z=4, a=7.3573(12), b=8.0336(13), c=20.281(3)A, 3492 structure factors, 109 parameters, R[F 2 >2σ(F 2 )]=0.0371, wR(F 2 all)=0.0517; Hg 6 Cr 2 O 10 : space group Pca2 1 , Z=4, a=11.4745(15), b=9.4359(12), c=10.3517(14)A, 3249 structure factors, 114 parameters, R[F 2 >2σ(F 2 )]=0.0398, wR(F 2 all)=0.0625. Both crystal structures are made up of an intricate mercury-oxygen network, subdivided into single building blocks [O-Hg-Hg-O] for the mercurous compound, and [O-Hg-Hg-O] and [O-Hg-O] for the mixed-valent compound. Hg 6 Cr 2 O 9 contains three different Hg 2 2+ dumbbells, whereas Hg 6 Cr 2 O 10 contains two different Hg 2 2+ dumbbells and two Hg 2+ cations. The Hg I -Hg I distances are characteristic and range between 2.5031(15) and 2.5286(9)A. All Hg 2 2+ groups exhibit an unsymmetrical oxygen environment. The oxygen coordination of the Hg 2+ cations is nearly linear with two tightly bonded O atoms at distances around 2.07A. For both structures, the chromate(VI) anions reside in the vacancies of the Hg-O network and deviate only slightly from the ideal tetrahedral geometry with average Cr-O distances of ca. 1.66A. Upon heating at temperatures above 385deg. C, Hg 6 Cr 2 O 9 decomposes in a four-step mechanism with Cr 2 O 3 as the end-product at temperatures above 620 deg. C

Crystal structure of the Hg4SiS6 and Hg4SiSe6 compounds

International Nuclear Information System (INIS)

Gulay, L.D.; Olekseyuk, I.D.; Parasyuk, O.V.

2002-01-01

The crystal structures of Hg 4 SiS 6 and Hg 4 SiSe 6 compounds were investigated using X-ray powder diffraction. These compounds crystallize in the monoclinic Cc space group with the lattice parameters a=1.23020(5), b=0.71031(4), c=1.22791(4) nm, β=109.721(3) deg. for Hg 4 SiS 6 and a=1.28110(4), b=0.74034(4), c=1.27471(1) nm, β=109.605(3) deg. for Hg 4 SiSe 6 . Atomic parameters were refined in the isotropic approximation (R I =0.0571 and R I =0.0555 for the Hg 4 SiS 6 and Hg 4 SiSe 6 , respectively)

Evaporation and NARS Nitric Acid Mass Balance Summary: 2000--2005

International Nuclear Information System (INIS)

Kreutzberg, B.D.; Ames, R.L.; Hansel, K.M.

2005-01-01

A compilation of the historical nitric acid processing data for the evaporation and nitric acid recycle system (NARS) in TA-55 has provided general acid mass balance trends, as well as the location of missing information in both the evaporation system and NARS data logs. The data were accumulated during the calendar years 2000 to 2005. After making a number of processing assumptions, the empirical system information was used to create an interactive spreadsheet that predicts, with moderate accuracy, some of the various stream variables for the combined evaporation and acid recycle processes. Empirical data and interactive calculations were compared to an Aspen Plus(trademark) simulation of the process

Recycled Uranium Mass Balance Project Y-12 National Security Complex Site Report

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-12-01

This report has been prepared to summarize the findings of the Y-12 National Security Complex (Y-12 Complex) Mass Balance Project and to support preparation of associated U. S. Department of Energy (DOE) site reports. The project was conducted in support of DOE efforts to assess the potential for health and environmental issues resulting from the presence of transuranic (TRU) elements and fission products in recycled uranium (RU) processed by DOE and its predecessor agencies. The United States government used uranium in fission reactors to produce plutonium and tritium for nuclear weapons production. Because uranium was considered scarce relative to demand when these operations began almost 50 years ago, the spent fuel from U.S. fission reactors was processed to recover uranium for recycling. The estimated mass balance for highly enriched RU, which is of most concern for worker exposure and is the primary focus of this project, is summarized in a table. A discrepancy in the mass balance between receipts and shipments (plus inventory and waste) reflects an inability to precisely distinguish between RU and non-RU shipments and receipts involving the Y-12 Complex and Savannah River. Shipments of fresh fuel (non-RU) and sweetener (also non-RU) were made from the Y-12 Complex to Savannah River along with RU shipments. The only way to distinguish between these RU and non-RU streams using available records is by enrichment level. Shipments of {le}90% enrichment were assumed to be RU. Shipments of >90% enrichment were assumed to be non-RU fresh fuel or sweetener. This methodology using enrichment level to distinguish between RU and non-RU results in good estimates of RU flows that are reasonably consistent with Savannah River estimates. Although this is the best available means of distinguishing RU streams, this method does leave a difference of approximately 17.3 MTU between receipts and shipments. Slightly depleted RU streams received by the Y-12 Complex from ORGDP and

The evaluation of body mass index, balance and agility features of amateur soccer players according to their positions

Directory of Open Access Journals (Sweden)

Kamil Erdem

2015-12-01

Full Text Available Aim: The purpose of this study was to compare of body mass index (BMI, balance and agility features of soccer players at different positions and to investigate the relation between these features. Material and Methods: Research was carried out on 44 amateur soccer player whom played in different positions in various teams that compete in amateur league of İstanbul. In the research, it was tested vki, balance, agility with ball and agility without ball on soccer players. The average of variables was taken and Kruskal Wallis nonparametric variance analysis was used to determine the difference between groups. Pearson correlation was used to determine correlations between variables. Results: As a result of measuments, when compare between positions, it was found that there was a statistical difference on body mass measurement (p0,01. As a result of correlations, it was found statistically significant relation between body mass and agility with ball between BMI and agility with ball and between body mass and BMI variables (p<0,01. Conclusion: As a result of assesstments it has been revealed that there was a correlation between BMI and dribbling skills on soccer players however there wasn’t found any differences between other parameters as balance and agility because of the trainings that carried out regardless of the positions in soccer. As a conclusion, optimal training programmes that will be held on according to positions of players, additional balance trainings and the identified shortcomings may contribute to the development of soccer players performance and skill with appliying ideal diet programme to maintain the appropriate body weight for players heights.

Radiocarbon Mass Balance for a Magnox Nuclear Power Station

International Nuclear Information System (INIS)

Metcalfe, M.P.; Mills, R.W.

2016-01-01

Nuclear power generation in the United Kingdom is based principally on graphite-moderated gas-cooled reactors. The mass of irradiated graphite associated with these reactors, including material from associated experimental, prototype and production reactors, exceeds 96,000 tonnes. One of the principal long-lived radionuclides produced during graphite irradiation is radiocarbon (C-14), which has a half-life of 5730 ± 40 years. Decommissioning and graphite waste management strategies must take account of this radionuclide. In order to identify appropriate options for addressing the potential hazard of C-14, it is important that the production processes are understood and the distributions and concentrations of C-14 are characterised. In fact, C-14 precursors and their activation processes are well-known. However, there is ongoing debate over the relative importance of different C-14 precursors, which will determine the location of C-14 within graphite components and hence its mobility/response to treatment. A generally held misconception concerning C-14 in irradiated graphite is that generic statements can be made about its precursors and their location. C-14 location and activities will depend upon the composition of the original manufactured graphite (raw materials, impurities), the chemical environment of the graphite during service and the irradiation history of the graphite. So, while there may be some similarities across, for example, carbon dioxide cooled graphite moderated designs (Magnox, AGR, UNGG), any informed assessment of a core’s C-14 inventory would require more-precise characterisation. The analysis presented here focuses on a UK Magnox reactor core, Reactor 1 at Wylfa Nuclear Power Station. The objective of the analysis is to present a full C-14 mass balance over a selected period of operation for which there are accurate C-14 discharge records. The analysis presented here provides the first assessment of the principal C-14 activation pathways

Mercury nonstoichiometry of the Hg1-xBa2CuO4+δ superconductor and the P(Hg)-P(O2)-T phase diagram of the Hg-Ba-Cu-O system

International Nuclear Information System (INIS)

Alyoshin, V.A.; Mikhailova, D.A.; Rudnyi, E.B.; Antipov, E.V.

2002-01-01

The P(Hg)-P(O 2 )-T phase diagram of the Hg-Ba-Cu-O system for the Ba:Cu=2:1 ratio was experimentally studied and followed by means of the thermodynamic modeling. It was shown that the Hg 1-x Ba 2 CuO 4+δ (Hg-1201) superconductor possesses a significant range of Hg-nonstoichiometry and exists in a certain P(Hg), P(O 2 ) and T range. Mercury nonstoichiometry of Hg-1201 was investigated in the 923≤T≤1095 K; 2.0≤P(Hg)≤8.4 atm; 0.09≤P(O 2 )≤0.86 atm ranges. It was found that the mercury content varies in the range of 0.80-0.94 under these conditions. The Gibbs energy of the Hg-1201 phase was estimated as a function of temperature and mercury concentration. The obtained results allow optimizing the synthesis conditions of Hg-1201 with a given Hg-content including preparation of the Hg-stoichiometric phase

Investigating ice cliff evolution and contribution to glacier mass-balance using a physically-based dynamic model

Science.gov (United States)

Buri, Pascal; Miles, Evan; Ragettli, Silvan; Brun, Fanny; Steiner, Jakob; Pellicciotti, Francesca

2016-04-01

Supraglacial cliffs are a surface feature typical of debris-covered glaciers, affecting surface evolution, glacier downwasting and mass balance by providing a direct ice-atmosphere interface. As a result, melt rates can be very high and ice cliffs may account for a significant portion of the total glacier mass loss. However, their contribution to glacier mass balance has rarely been quantified through physically-based models. Most cliff energy balance models are point scale models which calculate energy fluxes at individual cliff locations. Results from the only grid based model to date accurately reflect energy fluxes and cliff melt, but modelled backwasting patterns are in some cases unrealistic, as the distribution of melt rates would lead to progressive shallowing and disappearance of cliffs. Based on a unique multitemporal dataset of cliff topography and backwasting obtained from high-resolution terrestrial and aerial Structure-from-Motion analysis on Lirung Glacier in Nepal, it is apparent that cliffs exhibit a range of behaviours but most do not rapidly disappear. The patterns of evolution cannot be explained satisfactorily by atmospheric melt alone, and are moderated by the presence of supraglacial ponds at the base of cliffs and by cliff reburial with debris. Here, we document the distinct patterns of evolution including disappearance, growth and stability. We then use these observations to improve the grid-based energy balance model, implementing periodic updates of the cliff geometry resulting from modelled melt perpendicular to the ice surface. Based on a slope threshold, pixels can be reburied by debris or become debris-free. The effect of ponds are taken into account through enhanced melt rates in horizontal direction on pixels selected based on an algorithm considering distance to the water surface, slope and lake level. We use the dynamic model to first study the evolution of selected cliffs for which accurate, high resolution DEMs are available

Characterization of methane oxidation in a simulated landfill cover system by comparing molecular and stable isotope mass balances.

Science.gov (United States)

Schulte, Marcel; Jochmann, Maik A; Gehrke, Tobias; Thom, Andrea; Ricken, Tim; Denecke, Martin; Schmidt, Torsten C

2017-11-01

Biological methane oxidation may be regarded as a method of aftercare treatment for landfills to reduce climate relevant methane emissions. It is of social and economic interest to estimate the behavior of bacterial methane oxidation in aged landfill covers due to an adequate long-term treatment of the gas emissions. Different approaches assessing methane oxidation in laboratory column studies have been investigated by other authors recently. However, this work represents the first study in which three independent approaches, ((i) mass balance, (ii) stable isotope analysis, and (iii) stoichiometric balance of product (CO 2 ) and reactant (CH 4 ) by CO 2 /CH 4 -ratio) have been compared for the estimation of the biodegradation by a robust statistical validation on a rectangular, wide soil column. Additionally, an evaluation by thermal imaging as a potential technique for the localization of the active zone of bacterial methane oxidation has been addressed in connection with stable isotope analysis and CO 2 /CH 4 -ratios. Although landfills can be considered as open systems the results for stable isotope analysis based on a closed system correlated better with the mass balance than calculations based on an open system. CO 2 /CH 4 -ratios were also in good agreement with mass balance. In general, highest values for biodegradation were determined from mass balance, followed by CO 2 /CH 4 -ratio, and stable isotope analysis. The investigated topsoil proved to be very suitable as a potential cover layer by removing up to 99% of methane for CH 4 loads of 35-65gm -2 d -1 that are typical in the aftercare phase of landfills. Finally, data from stable isotope analysis and the CO 2 /CH 4 -ratios were used to trace microbial activity within the reactor system. It was shown that methane consumption and temperature increase, as a cause of high microbial activity, correlated very well. Copyright © 2017 Elsevier Ltd. All rights reserved.

Instruments for radiation measurement in life sciences (4). 7. Application of accelerator mass spectrometry for drug development. Human mass balance studies at discovery stage

International Nuclear Information System (INIS)

Miyaoka, Teiji

2005-01-01

Following the recent trend of Position Paper issued from European Agency for the Evaluation of Medicinal Products on the non-clinical safety studies to support clinical trials with a single micro dose, human mass balance studies at discovery stages were made with special interest in using AMS (accelerator mass spectrometry) with a small amount of hot (radioisotope-labeled) drug. This method was found to be effective for the purpose of screening in the clinical study for pharmaceutical development. To show an example of the test, 5, 50, 500μg/body of C14-ARA (α1A adrenoreceptor antagonist, 50 nCi or 1.85 kBq/body/dose) were given (cross over) to several persons to be inspected and C14-quantity in the blood plasma or urine was determined with AMS until after 168 hours or so. The results of the present experiment demonstrate that human mass balance study at discovery stages is possible with ultra high sensitive measuring systems such as AMS and PET (positron emission tomography). (S. Ohno)

Determination of Cd, Hg, Pb and Tl in coal and coal fly ash slurries using electrothermal vaporization inductively coupled plasma mass spectrometry and isotopic dilution

Energy Technology Data Exchange (ETDEWEB)

Maia, S.M.; Pozebon, D.; Curtius, A.J. [Univ. Federal de Santa Catarina, Florianopolis, SC (Brazil)

2003-07-01

A method has been investigated for the determination of Cd, Hg, Pb and Tl in coal and in coal fly ash, using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry and isotope dilution. The slurry, 25 mg ml{sup -1}, was prepared by mixing the powdered sample (less than or equal to 36 - 45 mm) with acid solutions (nitric acid for coal and nitric and hydrofluoric acids for coal fly ash) and submitting the mixture to an ultrasonic agitation, letting it stand afterwards in a water bath at 60{sup o}C for 2 h. An ultrasonic probe was used to homogenize the slurry in the autosampler cup just before its introduction into the graphite tube. The best conditions were determined regarding analyte sensitivity, furnace temperature program, amount of modifier, acid concentration, gas flow rate and particle size. For Hg, the pyrolysis stage was omitted and a low vaporization temperature was used (450 - 1000{sup o}C); the residual matrix was eliminated in the first step of the following cycle. The modifiers used were: Pd for Cd and Tl; Au, Ir or Pd for Hg; Ir or Pd for Pb. The accuracy of the method was checked by analyzing six certified coal reference materials (SARM 20, SARM 19, BCR No. 40, BCR No. 180, BCR No. 181 and NIST 1630a) and one certified coal fly ash (NIST 1633b). With one exception (Hg in BCR No. 180), the found concentrations were typically within 95% confidence interval of the certified values, or close enough to the recommended values, as long as the samples were ground to a small enough particle size. The limits of detection were typically around 0.08 {mu}g g{sup -1}, 0.03 {mu}g g{sup -1}, 1 {mu}g g{sup -1} and 0.02 {mu}g g{sup -1} for Cd, Hg, Pb and Tl, respectively. The precision was also adequate with relative standard deviations of usually < 5%.

The relevance of clinical balance assessment tools to differentiate balance deficits

OpenAIRE

Mancini, Martina; Horak, Fay B

2010-01-01

Control of balance is complex and involves maintaining postures, facilitating movement, and recovering equilibrium. Balance control consists of controlling the body center of mass over its limits of stability. Clinical balance assessment can help assess fall risk and/or determine the underlying reasons for balance disorders. Most functional balance assessment scales assess fall risk and the need for balance rehabilitation but do not differentiate types of balance deficits. A system approach t...

Monthly solutions of ice sheet mass balance at basin scale – and their associated uncertainties

DEFF Research Database (Denmark)

Sørensen, Louise Sandberg; Barletta, Valentina Roberta; Forsberg, René

2012-01-01

There are still discrepancies in published ice sheet mass balance results, even between ones based on the same data sets. It can be difficult to conclude from where the discrepancies arise, and it is therefore important to cross calibrate methods, data and models in order to determine...

Greenland ice sheet surface mass balance: evaluating simulations and making projections with regional climate models

NARCIS (Netherlands)

Rae, J.G.L.; Aðalgeirsdóttir, G.; Edwards, T.L.; Fettweis, X.; Gregory, J.M.; Hewitt, H.T.; Lowe, J.A.; Lucas-Picher, P.; Mottram, R.H.; Payne, A.J.; Ridley, J.K.; Shannon, S.R.; van de Berg, W.J.; van de Wal, R.S.W.; van den Broeke, M.R.

2012-01-01

Four high-resolution regional climate models (RCMs) have been set up for the area of Greenland, with the aim of providing future projections of Greenland ice sheet surface mass balance (SMB), and its contribution to sea level rise, with greater accuracy than is possible from coarser-resolution

Sulfurization of Dissolved Organic Matter Increases Hg-Sulfide-Dissolved Organic Matter Bioavailability to a Hg-Methylating Bacterium.

Science.gov (United States)

Graham, Andrew M; Cameron-Burr, Keaton T; Hajic, Hayley A; Lee, Connie; Msekela, Deborah; Gilmour, Cynthia C

2017-08-15

Reactions of dissolved organic matter (DOM) with aqueous sulfide (termed sulfurization) in anoxic environments can substantially increase DOM's reduced sulfur functional group content. Sulfurization may affect DOM-trace metal interactions, including complexation and metal-containing particle precipitation, aggregation, and dissolution. Using a diverse suite of DOM samples, we found that susceptibility to additional sulfur incorporation via reaction with aqueous sulfide increased with increasing DOM aromatic-, carbonyl-, and carboxyl-C content. The role of DOM sulfurization in enhancing Hg bioavailability for microbial methylation was evaluated under conditions typical of Hg methylation environments (μM sulfide concentrations and low Hg-to-DOM molar ratios). Under the conditions of predicted metacinnabar supersaturation, microbial Hg methylation increased with increasing DOM sulfurization, likely reflecting either effective inhibition of metacinnabar growth and aggregation or the formation of Hg(II)-DOM thiol complexes with high bioavailability. Remarkably, Hg methylation efficiencies with the most sulfurized DOM samples were similar (>85% of total Hg methylated) to that observed in the presence of l-cysteine, a ligand facilitating rapid Hg(II) biouptake and methylation. This suggests that complexes of Hg(II) with DOM thiols have similar bioavailability to Hg(II) complexes with low-molecular-weight thiols. Overall, our results are a demonstration of the importance of DOM sulfurization to trace metal and metalloid (especially mercury) fate in the environment. DOM sulfurization likely represents another link between anthropogenic sulfate enrichment and MeHg production in the environment.

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

OpenAIRE

C. Feng; Z. Pedrero; P. Li; B. Du; X. Feng; M. Monperrus; E. Tessier; S. Berail; D. Amouroux

2016-01-01

Abstract Human consumption of rice constitutes a potential toxicological risk in mercury (Hg) polluted areas such as Hg mining regions in China. It is recognized to be an important source of Hg for the local human diet considering the efficient bioaccumulation of methylmercury (MeHg) in rice seed. To assess Hg sources and uptake pathways to the rice plants, Hg speciation and isotopic composition were investigated in rice seeds and their corresponding paddy soils from different locations withi...

Satellite-derived submarine melt rates and mass balance (2011-2015) for Greenland's largest remaining ice tongues

Science.gov (United States)

Wilson, Nat; Straneo, Fiammetta; Heimbach, Patrick

2017-12-01

Ice-shelf-like floating extensions at the termini of Greenland glaciers are undergoing rapid changes with potential implications for the stability of upstream glaciers and the ice sheet as a whole. While submarine melting is recognized as a major contributor to mass loss, the spatial distribution of submarine melting and its contribution to the total mass balance of these floating extensions is incompletely known and understood. Here, we use high-resolution WorldView satellite imagery collected between 2011 and 2015 to infer the magnitude and spatial variability of melt rates under Greenland's largest remaining ice tongues - Nioghalvfjerdsbræ (79 North Glacier, 79N), Ryder Glacier (RG), and Petermann Glacier (PG). Submarine melt rates under the ice tongues vary considerably, exceeding 50 m a-1 near the grounding zone and decaying rapidly downstream. Channels, likely originating from upstream subglacial channels, give rise to large melt variations across the ice tongues. We compare the total melt rates to the influx of ice to the ice tongue to assess their contribution to the current mass balance. At Petermann Glacier and Ryder Glacier, we find that the combined submarine and aerial melt approximately balances the ice flux from the grounded ice sheet. At Nioghalvfjerdsbræ the total melt flux (14.2 ± 0.96 km3 a-1 w.e., water equivalent) exceeds the inflow of ice (10.2 ± 0.59 km3 a-1 w.e.), indicating present thinning of the ice tongue.

Collective structures in 185Hg

International Nuclear Information System (INIS)

Bourgeois, C.; Hildingsson, L.; Perrin, N.; Sergolle, H.; Hannachi, F.; Bastin, G.; Porquet, M.G.; Thibaud, J.P.; Beck, F.A.; Merdinger, J.C.

1988-01-01

Excited states of 185 Hg have been investigated via the 161 Dy ( 28 Si, 4n) reaction at 145 MeV. In-beam gamma-ray spectroscopy studies have been performed with the ''Chateau de Cristal'' 4π-multidetector array. Level scheme of 185 Hg has been established. Shape coexistence, still present in 185 Hg like in the neighbouring Hg isotopes, manifests itself through a weakly populated decoupled band built on the 13/2+ isomer and three strongly-coupled bands built on the prolate 1/2-[521], 7/2-[514], and 9/2+[624] Nilsson states

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

Science.gov (United States)

Drott, A.; Skyllberg, U.

2007-12-01

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

Mass balance of Greenland and the Canadian Ice Caps from combined altimetry and GRACE inversion

DEFF Research Database (Denmark)

Forsberg, René; Simonsen, Sebastian Bjerregaard; Sørensen, Louise Sandberg

The combination of GRACE and altimetry data may yield a high resolution mass balance time series of the Greenlandice sheet, highlighting the varying individual mass loss behaviour of major glaciers. By including the Canadian arctic ice caps in the estimation, a more reliable estimate of the mass...... loss of both Greenlandand the Canadian ice caps may be obtained, minimizing the leakage errors otherwise unavoidable by GRACE. Actually, the absolute value of the Greenlandice sheet mass loss is highly dependent on methods and how the effects of Arctic Canadian ice caps are separated in the GRACE...... loss of the ice caps and ice sheet basins for the period 2003-15. This period shows a marked increase of ice sheet melt, especially in NW and NE Greenland, but also show large variability, with the melt anomaly year of 2012 showing a record mass loss, followed by 2013 with essentially no Greenland mass...

Higher surface mass balance of the Greenland ice sheet revealed by high - resolution climate modeling

NARCIS (Netherlands)

Ettema, Janneke; van den Broeke, Michiel R.; van Meijgaard, Erik; van de Berg, Willem Jan; Bamber, Jonathan L.; Box, Jason E.; Bales, Roger C.

2009-01-01

High‐resolution (∼11 km) regional climate modeling shows total annual precipitation on the Greenland ice sheet for 1958–2007 to be up to 24% and surface mass balance up to 63% higher than previously thought. The largest differences occur in coastal southeast Greenland, where the much higher

Balancing low mass and low inertia addition

NARCIS (Netherlands)

van der Wijk, V.

2009-01-01

To increase the accuracy as well the production speed of industrial machines, dynamic balance is becoming a key issue. Instead of applying complicated control strategies to reduce machine vibrations, and damping systems to suppress vibrations, in dynamic balancing the mechanism parts are considered

Method of Calibrating a Force Balance

Science.gov (United States)

Parker, Peter A. (Inventor); Rhew, Ray D. (Inventor); Johnson, Thomas H. (Inventor); Landman, Drew (Inventor)

2015-01-01

A calibration system and method utilizes acceleration of a mass to generate a force on the mass. An expected value of the force is calculated based on the magnitude and acceleration of the mass. A fixture is utilized to mount the mass to a force balance, and the force balance is calibrated to provide a reading consistent with the expected force determined for a given acceleration. The acceleration can be varied to provide different expected forces, and the force balance can be calibrated for different applied forces. The acceleration may result from linear acceleration of the mass or rotational movement of the mass.

Estimation of air-water gas exchange coefficient in a shallow lagoon based on 222Rn mass balance.

Science.gov (United States)

Cockenpot, S; Claude, C; Radakovitch, O

2015-05-01

The radon-222 mass balance is now commonly used to quantify water fluxes due to Submarine Groundwater Discharge (SGD) in coastal areas. One of the main loss terms of this mass balance, the radon evasion to the atmosphere, is based on empirical equations. This term is generally estimated using one among the many empirical equations describing the gas transfer velocity as a function of wind speed that have been proposed in the literature. These equations were, however, mainly obtained from areas of deep water and may be less appropriate for shallow areas. Here, we calculate the radon mass balance for a windy shallow coastal lagoon (mean depth of 6m and surface area of 1.55*10(8) m(2)) and use these data to estimate the radon loss to the atmosphere and the corresponding gas transfer velocity. We present new equations, adapted to our shallow water body, to express the gas transfer velocity as a function of wind speed at 10 m height (wind range from 2 to 12.5 m/s). When compared with those from the literature, these equations fit particularly well with the one of Kremer et al. (2003). Finally, we emphasize that some gas transfer exchange may always occur, even for conditions without wind. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Safety valve requirements for steam boilers (modifies HG-400 and HG-401). 53.05-1 Section 53.05-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... requirements for steam boilers (modifies HG-400 and HG-401). (a) The pressure relief valve requirements and the...

Hg0 and HgCl2 Reference Gas Standards: NIST Traceability and Comparability (And EPA ALT Methods for Hg and HCl )

Science.gov (United States)

EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the tru...

Improving Surface Mass Balance Over Ice Sheets and Snow Depth on Sea Ice

Science.gov (United States)

Koenig, Lora Suzanne; Box, Jason; Kurtz, Nathan

2013-01-01

Surface mass balance (SMB) over ice sheets and snow on sea ice (SOSI) are important components of the cryosphere. Large knowledge gaps remain in scientists' abilities to monitor SMB and SOSI, including insufficient measurements and difficulties with satellite retrievals. On ice sheets, snow accumulation is the sole mass gain to SMB, and meltwater runoff can be the dominant single loss factor in extremely warm years such as 2012. SOSI affects the growth and melt cycle of the Earth's polar sea ice cover. The summer of 2012 saw the largest satellite-recorded melt area over the Greenland ice sheet and the smallest satellite-recorded Arctic sea ice extent, making this meeting both timely and relevant.

Use of new threshold detector 199Hg(n,n')/sup 199m/Hg for neutron spectrum unfolding

International Nuclear Information System (INIS)

Sakurai, K.

1982-01-01

The nuclear data for the 199 Hg(n,n')/sup 199m/Hg reaction are reviewed and the data are used for neutron spectrum unfolding. The neutron spectrum of the YAYOI glory-hole is unfolded by SAND II with 10 nuclear reactions including the 199 Hg(n,n')/sup 199m/Hg reaction. The ratio of the measured reaction rate to the calculated reaction rate is about 1:1.1 for the guess spectrum. The 199 Hg(n,n')/sup 199m/Hg, 115 In(n,n')/sup 115m/In, 103 Rh(n,n')/sup 103m/Rh reactions should be useful threshold detectors for the neutron dosimetry with low level fast neutron flux

A Preliminary Model for Spacecraft Propulsion Performance Analysis Based on Nuclear Gain and Subsystem Mass-Power Balances

Science.gov (United States)

Chakrabarti, Suman; Schmidt, George R.; Thio, Y. C.; Hurst, Chantelle M.

1999-01-01

A preliminary model for spacecraft propulsion performance analysis based on nuclear gain and subsystem mass-power balances are presented in viewgraph form. For very fast missions with straight-line trajectories, it has been shown that mission trip time is proportional to the cube root of alpha. Analysis of spacecraft power systems via a power balance and examination of gain vs. mass-power ratio has shown: 1) A minimum gain is needed to have enough power for thruster and driver operation; and 2) Increases in gain result in decreases in overall mass-power ratio, which in turn leads to greater achievable accelerations. However, subsystem mass-power ratios and efficiencies are crucial: less efficient values for these can partially offset the effect of nuclear gain. Therefore, it is of interest to monitor the progress of gain-limited subsystem technologies and it is also possible that power-limited systems with sufficiently low alpha may be competitive for such ambitious missions. Topics include Space flight requirements; Spacecraft energy gain; Control theory for performance; Mission assumptions; Round trips: Time and distance; Trip times; Vehicle acceleration; and Minimizing trip times.

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

DEFF Research Database (Denmark)

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

2007-01-01

The use of de novo designed peptides is a powerful strategy to elucidate HgII-protein interactions and to gain insight into the chemistry of HgII in biological systems. Cysteine derivatives of the designed -helical peptides of the TRI family [Ac-G-(LaKbAcLdEeEfKg)4-G-NH2] bind HgII at high p...... to characterize the distinct species that are generated under different pH conditions and peptide TRI L9C/HgII ratios. These studies prove for the first time the formation of [Hg{(TRI L9C)2-(TRI L9C H)}], a dithiolate-HgII complex in the hydrophobic interior of the three-stranded coiled coil (TRI L9C)3. 199Hg NMR...

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

International Nuclear Information System (INIS)

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

2008-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-06-15

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

Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a gas exchange and carbon burial balance

International Nuclear Information System (INIS)

Yang Hong; Xing Yangping; Xie Ping; Ni Leyi; Rong Kewen

2008-01-01

Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon exchange across the water-air interface have demonstrated that lakes are supersaturated with CO 2 and CH 4 causing a net release of CO 2 and CH 4 to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon exchange across the water-air interface. Using two methods, overall mass balance and gas exchange and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the gas exchange and carbon burial balance, gaseous carbon (CO 2 and CH 4 ) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon exchange. - Due to high primary production, substantive allochthonous carbon inputs and intensive anthropogenic acitivity, subtropical, eutrophic Lake Donghu is a great carbon sink

Gradient measurements of gaseous elemental mercury (Hg0) in the marine boundary layer of the northwest Sea of Japan (East Sea).

Science.gov (United States)

Kalinchuk, Viktor; Lopatnikov, Evgeny; Astakhov, Anatoly

2018-06-01

Gaseous elemental mercury (Hg 0 ) is a prolific and persistent contaminant in the atmosphere. Atmospheric concentrations of Hg 0 were determined from 17 September to 7 October 2015 in the northwest Sea of Japan aboard the Russian research vessel Professor Gagarinsky. Simultaneous measurements of Hg 0 concentrations were performed 2 m and 20 m above the sea surface using automatic Hg 0 analysers RA-915M and RA-915+, respectively. Concentrations ranged from 0.3 to 25.9 ng/m 3 (n = 5207) and from 0.3 to 27.8 ng/m 3 (n = 4415), with medians of 1.7 and 1.6 ng/m 3 , respectively. Elevated Hg 0 was observed during three episodes from 19 to 22 September, likely caused by one or more of the following factors: 1) atmospheric transport of Hg 0 from the west and south-west (from N. Korea, China, and the Yellow Sea region); 2) Hg 0 emission from the sea due to pollution by water from the Tumannaya River; or 3) underwater geological activities. Increased Hg 0 concentration was observed during periods when air masses flowed from the south, and low concentrations were observed when air masses came from the north. A daytime increase of Hg 0 concentrations at a height of 2 m occurred simultaneously with decreasing Hg 0 at a height of 20 m. These diurnal variations suggest that two contrasting processes occur during the daytime in the marine boundary layer (MBL): Hg 0 emission from the sea surface and Hg 0 oxidation in the MBL by active halogens formed by photolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

MASS BALANCE: A KEY TO ADVANCING MONITORED AND ENHANCED ATTENUATION FOR CHLORINATED SOLVENTS

Energy Technology Data Exchange (ETDEWEB)

Looney, B; Karen Vangelas, K; Karen-M Adams, K; Francis H. Chappelle; Tom O. Early; Claire H. Sink

2006-06-30

Monitored natural attenuation (MNA) and enhanced attenuation (EA) are two environmental management strategies that rely on a variety of attenuation processes to degrade or immobilize contaminants and are implemented at appropriate sites by demonstrating that contaminant plumes have low risk and are stable or shrinking. The concept of a mass balance between the loading and attenuation of contaminants in a groundwater system is a powerful framework for conceptualizing and documenting the relative stability of a contaminant plume. As a result, this concept has significant potential to support appropriate implementation of monitored natural attenuation (MNA) and enhanced attenuation (EA). For mass balance to be useful in engineering practice, however, it is necessary to quantify it in practical ways that facilitate overall site remediation and which are consistent with existing regulatory guidance. Two divergent philosophies exist for quantifying plume stability--empirical and deterministic. The first relies on historical contaminant concentration data and bulk geochemical information from a monitoring well network and documents plume stability using trend analysis and statistical tools. This empirical approach, when feasible, provides powerful and compelling documentation of plume behavior and mass balance. It provides an interpretation on a relevant scale under field conditions. It integrates the operative attenuation processes measured by observing their actual impact on the plume. The power of the empirical approach was recognized early in the development of MNA guidance and protocols and it is currently the basis of the three lines of evidence used in MNA studies. The empirical approach has some weaknesses, however. It requires a relatively long period of undisturbed historical data. Thus it cannot be effectively applied to sites where active remediation was initiated quickly and is currently operating. It cannot be used as a tool to determine how much source

HgTe based topological insulators

International Nuclear Information System (INIS)

Bruene, Christoph

2014-01-01

This PhD thesis summarizes the discovery of topological insulators and highlights the developments on their experimental observations. The work focuses on HgTe. The thesis is structured as follows: - The first chapter of this thesis will give a brief overview on discoveries in the field of topological insulators. It focuses on works relevant to experimental results presented in the following chapters. This includes a short outline of the early predictions and a summary of important results concerning 2-dimensional topological insulators while the final section discusses observations concerning 3-dimensional topological insulators. - The discovery of the quantum spin Hall effect in HgTe marked the first experimental observation of a topological insulator. Chapter 2 focuses on HgTe quantum wells and the quantum spin Hall effect. The growth of high quality HgTe quantum wells was one of the major goals for this work. In a final set of experiments the spin polarization of the edge channels was investigated. Here, we could make use of the advantage that HgTe quantum well structures exhibit a large Rashba spin orbit splitting. - HgTe as a 3-dimensional topological insulator is presented in chapter 3. - Chapters 4-6 serve as in depth overviews of selected works: Chapter 4 presents a detailed overview on the all electrical detection of the spin Hall effect in HgTe quantum wells. The detection of the spin polarization of the quantum spin Hall effect is shown in chapter 5 and chapter 6 gives a detailed overview on the quantum Hall effect originating from the topological surface state in strained bulk HgTe.

Hydrothermal liquefaction of high- and low-lipid algae: Mass and energy balances.

Science.gov (United States)

Cheng, Feng; Cui, Zheng; Mallick, Kwonit; Nirmalakhandan, Nagamany; Brewer, Catherine E

2018-06-01

Hydrothermal liquefaction (HTL) of high-lipid microalgae Nannochloropsis salina (N. salina) and low-lipid microalgae Galdieria sulphuraria (G. sulphuraria) were run under subcritical conditions (310-350 °C and 10-17 MPa) in a 1.8 L batch autoclave system. HTL mass and energy balances for both species were compared under different operating conditions to predict the optimum reaction conditions for new algae strains based on their feedstock composition. Bio-crude oils and chars were characterized by bomb calorimetry, elemental analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), and thermogravimetric analysis (TGA). Under the optimized conditions, 59 wt% and 31 wt% bio-crude oil yields were obtained from HTL of N. salina and G. sulphuraria, while 85% and 59% of the feedstock energy were partitioned into N. salina-derived and G. sulphuraria-derived bio-crude oils, respectively. More favorable energy balances were related to shorter reaction times and higher algal solid contents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Efficacy of an extravascular lung water-driven negative fluid balance protocol.

Science.gov (United States)

Díaz-Rubia, L; Ramos-Sáez, S; Vázquez-Guillamet, R; Guerrero-López, F; Pino-Sánchez, F; García-Delgado, M; Gómez-Jiménez, F J; Fernández-Mondéjar, E

2015-01-01

To analyze the efficacy of negative fluid balance in hypoxemic patients with an elevated extravascular lung water index (EVLWI). A retrospective observational study was made. Intensive Care Unit of Virgen de las Nieves Hospital (Spain). Forty-four patients participated in the study. We analyzed our database of hypoxemic patients covering a period of 11 consecutive months. We included all hemodynamically stable and hypoxemic patients with EVLWI>9ml/kg. The protocol dictates a negative fluid balance between 500 and 1500ml/day. We analyzed the impact of this negative fluid balance strategy upon pulmonary, hemodynamic, and renal function. Demographic data, severity scores, clinical, hemodynamic, pulmonary, metabolic and renal function data. Thirty-three patients achieved negative fluid balance (NFB group) and 11 had a positive fluid balance (PFB group). In the former group, PaO2/FiO2 improved from 145 (IQR 106, 200) to 210mmHg (IQR 164, 248) (pPFB group, EVLWI also decreased from 11 (10, 14) to 10ml/kg (8, 14) at the end of the protocol (p=0.004). For these patients there were no changes in oxygenation, with a PaO2/FiO2 of 216mmHg (IQR 137, 260) at the beginning versus 205mmHg (IQR 99,257) at the end of the study (p=0.08). Three out of four hypoxic patients with elevated EVLWI tolerated the NFB protocol. In these subjects, the improvement of various analyzed physiological parameters was greater and faster than in those unable to complete the protocol. Patients who did not tolerate the protocol were usually in more severe condition, though a larger sample would be needed to detect specific characteristics of this group. Copyright © 2014 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Observation of superdeformation in 191Hg

International Nuclear Information System (INIS)

Moore, E.F.; Janssens, R.V.F.; Chasman, R.R.

1989-01-01

The first observation of superdeformation in the A ≅ 190 mass region is reported. A rotational band of 12 transitions with an average energy spacing of 37 keV, an average moment of inertia of 110 ℎ 2 MeV -1 , and an average quadrupole moment of 18 ± 3 eb has been observed in 191 Hg. These results are in excellent agreement with a calculation that predicts an ellipsoidal axis ratio of 1.65:1 for the superdeformed shape in this nucleus. Evidence for another discrete superdeformed band and superdeformed structures in the quasi-continuum was also found in the data. 19 refs., 6 figs

Quantification of seasonal to annual mass balances from glacier surface albedo derived from optical satellite images, application on 30 glaciers in the French Alps for the period 2000-2015.

Science.gov (United States)

Davaze, Lucas; Rabatel, Antoine; Arnaud, Yves; Sirguey, Pascal; Six, Delphine; Letreguilly, Anne; Dumont, Marie

2017-04-01

Increasing the number of glaciers monitored for surface mass balance is very challenging, especially using laborious methods based on in situ data. Complementary methods are therefore required to quantify the surface mass balance of unmonitored glaciers. The current study relies on the so-called albedo method, based on the analysis of albedo maps retrieved from optical satellite imagery acquired since 2000 by the MODIS sensor, onboard of TERRA satellite. Recent studies performed on single glaciers in the French Alps, the Himalayas or the Southern Alps of New Zealand revealed substantial relationships between summer minimum glacier-wide surface albedo and annual mass balance, because this minimum surface albedo is directly related to accumulation-area ratio and the equilibrium-line altitude. On the basis of 30 glaciers located in the French Alps where annual surface mass balance are available, our study conducted on the period 2000-2015 confirms the robustness and reliability of the relationship between the summer minimum surface albedo and the annual surface mass balance. At the seasonal scale, the integrated summer surface albedo is significantly correlated with the summer mass balance of the six glaciers seasonally surveyed. For the winter season, four of the six glaciers showed a significant correlation when linking the winter surface mass balance and the integrated winter surface albedo, using glacier-dependent thresholds to filter the albedo signal. Sensitivity study on the computed cloud detection algorithm revealed high confidence in retrieved albedo maps. These results are promising to monitor both annual and seasonal glacier-wide surface mass balances of individual glaciers at a regional scale using optical satellite images.

Changing pattern of ice flow and mass balance for glaciers discharging into the Larsen A and B embayments, Antarctic Peninsula, 2011 to 2016

Science.gov (United States)

Rott, Helmut; Abdel Jaber, Wael; Wuite, Jan; Scheiblauer, Stefan; Floricioiu, Dana; Melchior van Wessem, Jan; Nagler, Thomas; Miranda, Nuno; van den Broeke, Michiel R.

2018-04-01

We analysed volume change and mass balance of outlet glaciers on the northern Antarctic Peninsula over the periods 2011 to 2013 and 2013 to 2016, using high-resolution topographic data from the bistatic interferometric radar satellite mission TanDEM-X. Complementary to the geodetic method that applies DEM differencing, we computed the net mass balance of the main outlet glaciers using the mass budget method, accounting for the difference between the surface mass balance (SMB) and the discharge of ice into an ocean or ice shelf. The SMB values are based on output of the regional climate model RACMO version 2.3p2. To study glacier flow and retrieve ice discharge we generated time series of ice velocity from data from different satellite radar sensors, with radar images of the satellites TerraSAR-X and TanDEM-X as the main source. The study area comprises tributaries to the Larsen A, Larsen Inlet and Prince Gustav Channel embayments (region A), the glaciers calving into the Larsen B embayment (region B) and the glaciers draining into the remnant part of the Larsen B ice shelf in Scar Inlet (region C). The glaciers of region A, where the buttressing ice shelf disintegrated in 1995, and of region B (ice shelf break-up in 2002) show continuing losses in ice mass, with significant reduction of losses after 2013. The mass balance numbers for the grounded glacier area of region A are -3.98 ± 0.33 Gt a-1 from 2011 to 2013 and -2.38 ± 0.18 Gt a-1 from 2013 to 2016. The corresponding numbers for region B are -5.75 ± 0.45 and -2.32 ± 0.25 Gt a-1. The mass balance in region C during the two periods was slightly negative, at -0.54 ± 0.38 Gt a-1 and -0.58 ± 0.25 Gt a-1. The main share in the overall mass losses of the region was contributed by two glaciers: Drygalski Glacier contributing 61 % to the mass deficit of region A, and Hektoria and Green glaciers accounting for 67 % to the mass deficit of region B. Hektoria and Green glaciers accelerated significantly in 2010

Sudden change of quadrupole moment between the first 5/2- states of 197Hg and 199Hg

International Nuclear Information System (INIS)

Herzog, P.; Krien, K.; Freitag, M.; Reuschenbach, M.; Walitzki, H.

1980-01-01

Low-temperature time differential perturbed angular correlation experiments with the 164 KeV-134 keV cascade of sup(197m)Hg in a zinc matrix give evidence that the hitherto accepted value of the quadrupole moment of the first 5/2 - state of 197 Hg is erroneous. A new value is derived from a time differential perturbed angular correlation experiment with the 374 keV-158 keV cascade of sup(199m)Hg implanted into a Be single crystal and comparison with an analogous experiment for sup(197m)Hg. Taking Q(5/2 - , 199 Hg) = +0.95(7) b we derive Q(5/2 - , 197 Hg) = 0.081(6) b. This change of quadrupole moment is discussed in the framework of the shell model. (orig.)

Hourly mass and snow energy balance measurements from Mammoth Mountain, CA USA, 2011-2017

Science.gov (United States)

Bair, Edward H.; Davis, Robert E.; Dozier, Jeff

2018-03-01

The mass and energy balance of the snowpack govern its evolution. Direct measurement of these fluxes is essential for modeling the snowpack, yet there are few sites where all the relevant measurements are taken. Mammoth Mountain, CA USA, is home to the Cold Regions Research and Engineering Laboratory and University of California - Santa Barbara Energy Site (CUES), one of five energy balance monitoring sites in the western US. There is a ski patrol study site on Mammoth Mountain, called the Sesame Street Snow Study Plot, with automated snow and meteorological instruments where new snow is hand-weighed to measure its water content. There is also a site at Mammoth Pass with automated precipitation instruments. For this dataset, we present a clean and continuous hourly record of selected measurements from the three sites covering the 2011-2017 water years. Then, we model the snow mass balance at CUES and compare model runs to snow pillow measurements. The 2011-2017 period was marked by exceptional variability in precipitation, even for an area that has high year-to-year variability. The driest year on record, and one of the wettest years, occurred during this time period, making it ideal for studying climatic extremes. This dataset complements a previously published dataset from CUES containing a smaller subset of daily measurements. In addition to the hand-weighed SWE, novel measurements include hourly broadband snow albedo corrected for terrain and other measurement biases. This dataset is available with a digital object identifier: https://doi.org/10.21424/R4159Q.

A Smartphone Inertial Balance

Science.gov (United States)

Barrera-Garrido, Azael

2017-01-01

In order to measure the mass of an object in the absence of gravity, one useful tool for many decades has been the inertial balance. One of the simplest forms of inertial balance is made by two mass holders or pans joined together with two stiff metal plates, which act as springs.

Phase equilibria and thermodynamic functions for Ag–Hg and Cu–Hg binary systems

International Nuclear Information System (INIS)

Liu, Yajun; Wang, Guan; Wang, Jiang; Chen, Yang; Long, Zhaohui

2012-01-01

Highlights: ► The thermodynamic properties of Ag–Hg and Cu–Hg are explored in order to facilitate dental materials design. ► A self-consistent set of thermodynamic parameters is obtained. ► The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag–Hg and Cu–Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

Phase equilibria and thermodynamic functions for Ag-Hg and Cu-Hg binary systems

Energy Technology Data Exchange (ETDEWEB)

Liu, Yajun, E-mail: yajunliu@gatech.edu [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Guan [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Jiang [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Chen, Yang [Mining, Metallurgy and Materials Research Department, General Research Institute for Nonferrous Metals, Beijing 100088 (China); Long, Zhaohui [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China)

2012-11-10

Highlights: Black-Right-Pointing-Pointer The thermodynamic properties of Ag-Hg and Cu-Hg are explored in order to facilitate dental materials design. Black-Right-Pointing-Pointer A self-consistent set of thermodynamic parameters is obtained. Black-Right-Pointing-Pointer The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag-Hg and Cu-Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

A study of capillary discharge lamps in Ar-Hg and Xe-Hg mixtures

International Nuclear Information System (INIS)

Denisova, N; Gavare, Z; Revalde, G; Skudra, Ja; Veilande, R

2011-01-01

Low-pressure capillary discharge lamps in Ar-Hg and Xe-Hg mixtures are studied. The discharge size is 0.5 mm (500 μm) in radius. According to the literature, such types of plasma sources are classified as microplasmas. The studies include spectrally resolved optical measurements, tomographic reconstructions and numerical simulations using the collisional-radiative model for an Ar-Hg plasma. We discuss the problems of theoretical modelling and experimental diagnostics of microplasma sources. It is shown that the conventional collisional-radiative model, based on the assumption that transportation of atoms in the highly excited states can be neglected, has limitations in modelling a capillary discharge in an Ar-Hg mixture. It is found that diffusion of highly excited mercury atoms to the wall influences the emission properties of the capillary discharge. We have concluded that applications of the emission tomography method to microplasmas require a special analysis in each particular case.

A synthesis of the Green Bay (Lake Michigan) mass balance project: Implications for environmental science

Energy Technology Data Exchange (ETDEWEB)

Richardson, W.; Endicott, D.; Kreis, R. [Environmental Protection Agency, Grosse Ile, MI (United States). Large Lakes Research Station

1995-12-31

The questions confronting environmental managers responsible for the Great Lakes are complex and regulatory action (or inaction) have major social, environmental and economical consequences. It has become evident that rational approaches must be found to address the issues, more clearly identify and quantitate problems, locate and quantitate sources of important chemicals, and arrive at optimal remedial programs. A scientifically based management framework has been implemented and prototyped within the Great Lakes community of mangers and scientists referred to as the Mass Balance Approach. The US Environmental Protection Agency, led by the Great Lakes National Program Office (GLNPO) in cooperation with Office of Research and Development (ORD) and other state and academic organizations, has completed an intensive study of Green Bay (Lake Michigan) to test the feasibility of using the mass balance approach for managing toxic substances in the Great Lakes. This presentation will provide an overview of the project and the results. Conclusions and recommendations will be reviewed and implications for future policy based, scientific studies will be explored.

Electric field gradients in Hg compounds

DEFF Research Database (Denmark)

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

2012-01-01

&H functional performs best at both 4-component and ZORA levels. We furthermore observe that changes in the largest component of the diagonalised EFG tensor, Vzz, of linear HgCl2 show a slightly stronger dependence than the r-3 scaling upon bond length r(Hg-Cl) alterations. The 4-component/BH&H Vzz value of -9.......26 a.u. for a bent HgCl2 (¿ Cl-Hg-Cl = 120¿) is close to -9.60 a.u. obtained for the linear HgCl2 structure. Thus a point charge model for EFG calculations completely fails in this case. By means of a projection analysis of molecular orbital (MO) contributions to Vzz in terms of the atomic constituents...

Mercury (Hg) speciation in coral reef systems of remote Oceania: Implications for the artisanal fisheries of Tutuila, Samoa Islands.

Science.gov (United States)

Morrison, R John; Peshut, Peter J; West, Ronald J; Lasorsa, Brenda K

2015-07-15

We investigated Hg in muscle tissue of fish species from three trophic levels on fringing reefs of Tutuila (14°S, 171°W), plus water, sediment and turf alga. Accumulation of total Hg in the herbivore Acanthurus lineatus (Acanthuridae, lined surgeonfish, (n=40)) was negligible at 1.05 (±0.04) ng g(-1) wet-weight, (∼65% occurring as methyl Hg). The mid-level carnivore Parupeneus spp. (Mullidae, goatfishes (n=10)) had total Hg 29.8 (±4.5) ng g(-1) wet-weight (∼99% as methyl Hg). Neither A. lineatus or Parupeneus spp. showed a propensity to accumulate Hg based on body size. Both groups were assigned a status of "un-restricted" for monthly consumption limits for non-carcinogenic health endpoints for methyl Hg. The top-level carnivore Sphyraena qenie (Sphyraenidae, blackfin barracuda, n=3) had muscle tissue residues of 105, 650 and 741 ng g(-1) wet-weight (100% methyl Hg, with increasing concentration with body mass, suggesting that S. qenie >15 kg would have a recommendation of "no consumption". Copyright © 2015 Elsevier Ltd. All rights reserved.

40 CFR 60.4142 - Hg allowance allocations.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Hg allowance allocations. 60.4142... Coal-Fired Electric Steam Generating Units Hg Allowance Allocations § 60.4142 Hg allowance allocations. (a)(1) The baseline heat input (in MMBtu) used with respect to Hg allowance allocations under...

Transfer of arsenic from poultry feed to poultry litter: A mass balance study.

Science.gov (United States)

Gupta, Sanjay K; Le, X Chris; Kachanosky, Gary; Zuidhof, Martin J; Siddique, Tariq

2018-07-15

Roxarsone (rox), an arsenic (As) containing organic compound, is a common feed additive used in poultry production. To determine if As present in rox is excreted into the poultry litter without any retention in chicken meat for safe human consumption, the transference of As from the feed to poultry excreta was assessed using two commercial chicken strains fed with and without dietary rox. The results revealed that both the strains had similar behaviour in growth (chicken weight; 2.17-2.25kg), feed consumption (282-300kgpen -1 initially containing 102 chicken) and poultry litter production (73-81kgpen -1 ) during the growth phase of 35days. Our mass balance calculations showed that chickens ingested 2669-2730mg As with the feed and excreted out 2362-2896mg As in poultry litter during the growth period of 28days when As containing feed was used, yielding As recovery between 86 and 108%. Though our complementary studies show that residual arsenic species in rox-fed chicken meat may have relevance to human exposure, insignificant retention of total As in the chicken meat substantiates our mass balance results. The results are important in evaluating the fate of feed additive used in poultry production and its potential environmental implications if As containing poultry litter is applied to soil for crop production. Copyright © 2018 Elsevier B.V. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-08-17

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

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

Science.gov (United States)

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

2014-01-01

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

Sugarcane bagasse pretreatment using three imidazolium-based ionic liquids; mass balances and enzyme kinetics

Directory of Open Access Journals (Sweden)

Karatzos Sergios

2012-08-01

Full Text Available Abstract Background Effective pretreatment is key to achieving high enzymatic saccharification efficiency in processing lignocellulosic biomass to fermentable sugars, biofuels and value-added products. Ionic liquids (ILs, still relatively new class of solvents, are attractive for biomass pretreatment because some demonstrate the rare ability to dissolve all components of lignocellulosic biomass including highly ordered (crystalline cellulose. In the present study, three ILs, 1-butyl-3-methylimidazolium chloride ([C4mim]Cl, 1-ethyl-3-methylimidazolium chloride ([C2mim]Cl, 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc are used to dissolve/pretreat and fractionate sugarcane bagasse. In these IL-based pretreatments the biomass is completely or partially dissolved in ILs at temperatures greater than 130°C and then precipitated by the addition of an antisolvent to the IL biomass mixture. For the first time mass balances of IL-based pretreatments are reported. Such mass balances, along with kinetics data, can be used in process modelling and design. Results Lignin removals of 10% mass of lignin in bagasse with [C4mim]Cl, 50% mass with [C2mim]Cl and 60% mass with [C2mim]OAc, are achieved by limiting the amount of water added as antisolvent to 0.5 water:IL mass ratio thus minimising lignin precipitation. Enzyme saccharification (24 h, 15FPU yields (% cellulose mass in starting bagasse from the recovered solids rank as: [C2mim]OAc(83% > >[C2mim]Cl(53% = [C4mim]Cl(53%. Composition of [C2mim]OAc-treated solids such as low lignin, low acetyl group content and preservation of arabinosyl groups are characteristic of aqueous alkali pretreatments while those of chloride IL-treated solids resemble aqueous acid pretreatments. All ILs are fully recovered after use (100% mass as determined by ion chromatography. Conclusions In all three ILs regulated addition of water as an antisolvent effected a polysaccharide enriched precipitate since some of the lignin

Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors

Science.gov (United States)

Andres, Britta; Engström, Ann-Christine; Blomquist, Nicklas; Forsberg, Sven; Dahlström, Christina; Olin, Håkan

2016-01-01

Symmetric electric double-layer capacitors (EDLCs) have equal masses of the same active material in both electrodes. However, having equal electrode masses may prevent the EDLC to have the largest possible specific capacitance if the sizes of the hydrated anions and cations in the electrolyte differ because the electrodes and the electrolyte may not be completely utilized. Here we demonstrate how this issue can be resolved by mass balancing. If the electrode masses are adjusted according to the size of the ions, one can easily increase an EDLC’s specific capacitance. To that end, we performed galvanostatic cycling to measure the capacitances of symmetric EDLCs with different electrode mass ratios using four aqueous electrolytes— Na2SO4, H2SO4, NaOH, and KOH (all with a concentration of 1 M)—and compared these to the theoretical optimal electrode mass ratio that we calculated using the sizes of the hydrated ions. Both the theoretical and experimental values revealed lower-than-1 optimal electrode ratios for all electrolytes except KOH. The largest increase in capacitance was obtained for EDLCs with NaOH as electrolyte. Specifically, we demonstrate an increase of the specific capacitance by 8.6% by adjusting the electrode mass ratio from 1 to 0.86. Our findings demonstrate that electrode mass balancing is a simple and inexpensive method to increase the capacitance of EDLCs. Furthermore, our results imply that one can reduce the amount of unused material in EDLCs and thus decrease their weight, volume and cost. PMID:27658253

Active tuned mass damper in vehicles. Integrated mass and energy balance; Mechatronische Schwingungstilger in Fahrzeugen. Ganzheitliche Massen- und Energiebilanz

Energy Technology Data Exchange (ETDEWEB)

Granzow, Sebastian

2012-04-02

The number of mechatronic automotive applications is growing rapidly and becoming more and more important. On the other hand, the automotive industry is faced with the ambitious challenge to significantly reduce CO{sub 2}-emissions. The vehicle mass is as a part of the driving resistance is a starting point. New innovative approaches are required for lightweight constructions. Taking the two aspects together, this leads inevitably to the question: Is it possible to support automotive lightweight construction by using mechatronic systems? The Mechatronic vibration absorber is a combination of a mechanical oscillating system with an electronically controllable force component. This allows a broadband and situation-dependent influence of vehicle vibration behavior. Mechatronic vibration absorbers are suitable to compensate a loss of riding comfort due to a reduction of the body mass. Essential for this is a multidisciplinary simulation environment. The mechatronic vibration absorber, including appropriate control systems, the nonlinear chassis and the elastic body characteristics, inclusive of mutual interactions are mapped in the simulation environment Matlab. In addition to the representation of the oscillating vehicle the determination of the total energy requirements is necessary. To achieve a CO{sub 2}-reduction target, the overall energy balance of lightweight and the electrical vibration absorber energy, which is offered by the vehicle, is required. The question of the real vibration absorber energy needs to be discussed in the context of the individual driving behavior. Ultimately, the overall energy balance is inherently dependent of the individual driving behavior.

Oxidative stress in MeHg-induced neurotoxicity

Energy Technology Data Exchange (ETDEWEB)

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

2011-11-15

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-12-15

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

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

Science.gov (United States)

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

2016-06-01

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

Balanced conditions or slight mass gain of glaciers in the Lahaul and Spiti region (northern India, Himalaya during the nineties preceded recent mass loss

Directory of Open Access Journals (Sweden)

C. Vincent

2013-04-01

Full Text Available The volume change of the Chhota Shigri Glacier (India, 32° 20 N, 77° 30' E between 1988 and 2010 has been determined using in situ geodetic measurements. This glacier has experienced only a slight mass loss between 1988 and 2010 (−3.8 ± 2.0 m w.e. (water equivalent corresponding to −0.17 ± 0.09 m w.e. yr−1. Using satellite digital elevation models (DEM differencing and field measurements, we measure a negative mass balance (MB between 1999 and 2010 (−4.8 ± 1.8 m w.e. corresponding to −0.44 ± 0.16 m w.e. yr−1. Thus, we deduce a slightly positive or near-zero MB between 1988 and 1999 (+1.0 ± 2.7 m w.e. corresponding to +0.09 ± 0.24 m w.e. yr−1. Furthermore, satellite DEM differencing reveals that the MB of the Chhota Shigri Glacier (−0.39 ± 0.15 m w.e. yr−1 has been only slightly less negative than the MB of a 2110 km2 glaciarized area in the Lahaul and Spiti region (−0.44 ± 0.09 m w.e. yr−1 during 1999−2011. Hence, we conclude that the ice wastage is probably moderate in this region over the last 22 yr, with near equilibrium conditions during the nineties, and an ice mass loss after. The turning point from balanced to negative mass budget is not known but lies probably in the late nineties and at the latest in 1999. This positive or near-zero MB for Chhota Shigri Glacier (and probably for the surrounding glaciers of the Lahaul and Spiti region during at least part of the 1990s contrasts with a recent compilation of MB data in the Himalayan range that indicated ice wastage since 1975. However, in agreement with this compilation, we confirm more negative balances since the beginning of the 21st century.

Mass Balance Applied to Brazilian Conventional Broiler Houses during One Production Cycle

Directory of Open Access Journals (Sweden)

A Migliavacca

Full Text Available ABSTRACT Brazil plays an important role in global poultry production as it is the world's largest chicken exporter and the third largest broiler producer. Despite the development achieved by the Brazilian broiler industry as a result of the integrated production system, many obstacles still need to be overcome, in particular, housing environment. In this regard, detailed knowledge of the inputs, outputs, and primary waste generated by broiler production cycles is essential to establish a baseline for energy balance research studies and to develop environmental solutions. This article proposes a mass balance of conventional broiler houses of southern Brazil sheds in order to predict their outputs, but that may also be applicable to other regions with similar climate. Control volumes considered the heating, cooling, and rearing processes. All generated products and wastes were estimated considering litter production and the total production per cycle. Despite the variety of the microclimates, the results were very close to those reported in experiments, indicating that this model is adequate for this kind of estimation.

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

DEFF Research Database (Denmark)

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

2012-01-01

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

Mass balance and hydrological contribution of glaciers in northern and central Chile

Science.gov (United States)

MacDonell, Shelley; Vivero, Sebastian; McPhee, James; Ayala, Alvaro; Pellicciotti, Francesca; Campos, Cristian; Caro, Dennys; Ponce, Rodrigo

2016-04-01

Water is a critical resource in the northern and central regions of Chile, as the area supports more than 40% of the country's population, and the regional economy depends on agricultural production and mining, which are two industries that rely heavily on a consistent water supply. Due to relatively low rates of rainfall, meltwater from snow and ice bodies in the highland areas provides a key component of the annual water supply in these areas. Consequently, accurate estimates of the rates of ablation of the cryosphere (i.e. snow and ice) are crucial for predicting current supply rates, and future projections. Whilst snow is generally a larger contributor of freshwater, during periods of drought, glaciers provide a significant source. This study aims to determine the contribution of glaciers to two catchments in northern and central Chile during a 2.5 year period, which largely consisted of extreme dry periods, but also included the recent El Niño event. This study combined field and modelling studies to understand glacier and rock glacier contributions in the Tapado (30°S), Yeso (33°S) catchments. In the field we undertook glaciological mass balance monitoring of three glaciers, monitored albedo and snow line changes using automatic cameras for three glaciers, measured discharge continuously at several points, installed six automatic weather stations and used thermistors to monitor thermal regime changes of two rock glaciers. The combination of these datasets where used to drive energy balance and hydrological models to estimate the contribution of ice bodies to streamflow in the two studied catchments. Over the course of the study all glaciers maintained a negative mass balance, however glaciers in central Chile lost more mass, which is due to the higher melt rates experienced due to lower elevations and higher temperatures. Areas free of debris generally contributed more to streamflow than sediment covered regions, and snow generally contributed more over

Lake Michigan Mass Balance Study Post Audit: Integrated, Multi-media PCB Modeling and Forecasting for Lake Trout

Science.gov (United States)

The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

Structure cristalline du composé Hg3-xSbx(S+Se2+xI2-x (x ≃ 0.1

Directory of Open Access Journals (Sweden)

Mohammed Kars

2016-03-01

Full Text Available Single crystals of the mercury chalcohalide Hg3-xSbx(S+Se2+xI2-x (x ≃ 0.1 (mercury antimony sulfide selenide iodide, were grown by a chemical transport reaction. The structure contains three independent A (Hg/Sb atoms; each atom is strongly covalently bonded with two X (Se/S atoms to form approximately linear X–A–X units. The X–A–X units link to form A4X4 rings, which are combined into infinite crankshaft-type bands running along the [100] direction. Four equatorial E (I/X = Se,S atoms at relatively long distances complete the distorted octahedral coordination of A (Hg/Sb. The crystal under investigation was twinned by non-merohedry with a refined twin domain fraction of 0.814 (6:0.186 (6. The structure is isotypic with Hg3Se2I2 [Beck & Hedderich (2000. J. Solid State Chem. 151, 73–76], but the current determination reveals a coupled substitution, with partial replacement of Hg+2 by Sb+3, balanced by the equivalent substitution of I−1 by S−2 and Se−2. Bond-valence calculations are consistent with this relative substitution model.

Converting Hg-1212 to Tl-2212 via Tl-Hg cation exchange in combination with Tl cation intercalation

International Nuclear Information System (INIS)

Zhao Hua; Wu, Judy Z

2007-01-01

In a cation exchange process developed recently for epitaxy of HgBa 2 CaCu 2 O 6 (Hg-1212) thin films, TlBa 2 CaCu 2 O 7 (Tl-1212) or Tl 2 Ba 2 CaCu 2 O 9 (Tl-2212) precursor films were employed as the precursor matrices and Hg-1212 was obtained by replacing Tl cations on the precursor lattice with Hg cations. The reversibility of the cation exchange dictates directly the underlying mechanism. Following our recent success in demonstrating a complete reversibility within '1212' structure, we show the conversion from Hg-1212 to Tl-2212 can be achieved via two steps: conversion from Hg-1212 to Tl-1212 followed by Tl intercalation to form double Tl-O plans in each unit cell. The demonstrated reversibility of the cation exchange process has confirmed the process is a thermal perturbation of weakly bonded cations on the lattice and the direction of the process is determined by the population ratio between the replacing cations and that to be replaced

Synthesis of Dynamically Balanced Mechanisms by Using Counter-Rotary Countermass Balanced Double Pendula

NARCIS (Netherlands)

van der Wijk, V.; Herder, Justus Laurens

2009-01-01

Complete dynamic balancing principles still cannot avoid a substantial increase in mass and inertia. In addition, the conditions for dynamic balance and inertia equations can be complicated to derive. This article shows how a double pendulum, which is fully dynamically balanced using counter-rotary

Balances instruments, manufacturers, history

CERN Document Server

Robens, Erich; Kiefer, Susanne

2014-01-01

The book deals mainly with direct mass determination by means of a conventional balances. It covers the history of the balance from the beginnings in Egypt earlier than 3000 BC to recent developments. All balance types are described with emphasis on scientific balances. Methods of indirect mass determination, which are applied to very light objects like molecules and the basic particles of matter and celestial bodies, are included.  As additional guidance, today’s manufacturers are listed and the profile of important companies is reviewed. Several hundred photographs, reproductions and drawings show instruments and their uses. This book includes commercial weighing instruments for merchandise and raw materials in workshops as well as symbolic weighing in the ancient Egyptian’s ceremony of ‘Weighing of the Heart’, the Greek fate balance, the Roman  Justitia, Juno Moneta and Middle Ages scenes of the Last Judgement with Jesus or St. Michael and of modern balances. The photographs are selected from the...

A thermodynamic model of the Hg(0.8)Cd(0.2)Te-iodine transport system. I - Te-saturated source material. II - Source material composition within the homogeneity range

Science.gov (United States)

Chandra, D.; Wiedemeier, H.

1987-01-01

A thermochemical analysis of the Hg(0.8)Cd(0.2)Te-iodine vapor transport system is presented, and theoretical calculations of diffusion-controlled mass transport rates are made. The predicted mass fluxes are compared with experimental data obtained from transport experiments under vertical, stabilizing conditions reported earlier and with results of additional transport experiments conducted during the present study. Experimental mass transport rate studies of the transport system for fixed amount of excess Hg as a function of transport agent pressure are presented. The mass fluxes are determined for the vertical, stabilizing orientation of the density gradient relative to the gravitational vector. In order to compare experimental mass transport rates with computed values, the thermochemical analysis is extended to take the formation of Hg vacancies in the above compound into account along with their effect on the partial pressure of the system.

Ab initio study of structural, electronic and optical properties of MnHg(SCN)4 and FeHg(SCN)4

International Nuclear Information System (INIS)

He, K.H.; Zheng, G.; Chen, G.; Lue, T.; Wan, M.; Ji, G.F.

2007-01-01

The structural, electronic and optical properties of MnHg(SCN) 4 and FeHg(SCN) 4 were studied by means of quantum-mechanical calculations based on the density-functional theory and pseudopotential method. The lattice constants can be compared with the experimental values when the effects of temperature are considered. The peaks of partial density of states of S, C, N and Hg of FeHg(SCN) 4 have a tendency of shifting to the higher energy levels relative to those of MnHg(SCN) 4 . The distributions of the 3d electronic states in the transition metal atoms show quite large difference and decide different optical properties. We found that absorptional peaks of FeHg(SCN) 4 lag behind those of MnHg(SCN) 4 and the peak in the infrared range has a higher absorptional intensity, which are in accord with the experimental results. By analyzing the distributions and transitions of the 3d electronic states, we explained the different absorption phenomena

Compton profiles and electronic structure of HgBr{sub 2} and HgI{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Ahmed, G.; Dashora, Alpa [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur, 313001 Rajasthan (India); Sharma, M. [Physics Division, State Forensic Science Laboratory, Jaipur, 302016 Rajasthan (India); Ahuja, B.L. [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur, 313001 Rajasthan (India)], E-mail: blahuja@yahoo.com

2010-02-15

In this paper, we present the first-ever experimental Compton line shapes of HgBr{sub 2} and HgI{sub 2} using {sup 137}Cs Compton spectrometer. To compare our experimental momentum densities, we have computed the Compton profiles using Hartree-Fock and density functional theory within linear combination of atomic orbitals. We have also computed the energy bands and density of states using the linear combination of atomic orbitals and full potential linearized augmented plane wave method. On the basis of equal-valence-electron-density profiles, it is seen that HgI{sub 2} is more covalent than HgBr{sub 2} which is in agreement with the valence charge densities. The experimental isotropic profiles are found to be relatively in better agreement with the Hartree-Fock data. We have also discussed the photoluminescence and detection properties of both the halides.

Hg(+) Frequency Standards

Science.gov (United States)

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

2000-01-01

In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

Elevation change of the Greenland Ice Sheet due to surface mass balance and firn processes, 1960-2014

NARCIS (Netherlands)

Kuipers Munneke, P.; Ligtenberg, S. R M; Noël, B. P Y; Howat, I. M.; Box, J. E.; Mosley-Thompson, E.; McConnell, J. R.; Steffen, K.; Harper, J. T.; Das, S. B.; Van Den Broeke, M. R.

2015-01-01

Observed changes in the surface elevation of the Greenland Ice Sheet are caused by ice dynamics, basal elevation change, basal melt, surface mass balance (SMB) variability, and by compaction of the overlying firn. The last two contributions are quantified here using a firn model that includes

Aquatic Exposure Predictions of Insecticide Field Concentrations Using a Multimedia Mass-Balance Model.

Science.gov (United States)

Knäbel, Anja; Scheringer, Martin; Stehle, Sebastian; Schulz, Ralf

2016-04-05

Highly complex process-driven mechanistic fate and transport models and multimedia mass balance models can be used for the exposure prediction of pesticides in different environmental compartments. Generally, both types of models differ in spatial and temporal resolution. Process-driven mechanistic fate models are very complex, and calculations are time-intensive. This type of model is currently used within the European regulatory pesticide registration (FOCUS). Multimedia mass-balance models require fewer input parameters to calculate concentration ranges and the partitioning between different environmental media. In this study, we used the fugacity-based small-region model (SRM) to calculate predicted environmental concentrations (PEC) for 466 cases of insecticide field concentrations measured in European surface waters. We were able to show that the PECs of the multimedia model are more protective in comparison to FOCUS. In addition, our results show that the multimedia model results have a higher predictive power to simulate varying field concentrations at a higher level of field relevance. The adaptation of the model scenario to actual field conditions suggests that the performance of the SRM increases when worst-case conditions are replaced by real field data. Therefore, this study shows that a less complex modeling approach than that used in the regulatory risk assessment exhibits a higher level of protectiveness and predictiveness and that there is a need to develop and evaluate new ecologically relevant scenarios in the context of pesticide exposure modeling.

Estimating Regional Mass Balance of Himalayan Glaciers Using Hexagon Imagery: An Automated Approach

Science.gov (United States)

Maurer, J. M.; Rupper, S.

2013-12-01

Currently there is much uncertainty regarding the present and future state of Himalayan glaciers, which supply meltwater for river systems vital to more than 1.4 billion people living throughout Asia. Previous assessments of regional glacier mass balance in the Himalayas using various remote sensing and field-based methods give inconsistent results, and most assessments are over relatively short (e.g., single decade) timescales. This study aims to quantify multi-decadal changes in volume and extent of Himalayan glaciers through efficient use of the large database of declassified 1970-80s era Hexagon stereo imagery. Automation of the DEM extraction process provides an effective workflow for many images to be processed and glacier elevation changes quantified with minimal user input. The tedious procedure of manual ground control point selection necessary for block-bundle adjustment (as ephemeral data is not available for the declassified images) is automated using the Maximally Stable Extremal Regions algorithm, which matches image elements between raw Hexagon images and georeferenced Landsat 15 meter panchromatic images. Additional automated Hexagon DEM processing, co-registration, and bias correction allow for direct comparison with modern ASTER and SRTM elevation data, thus quantifying glacier elevation and area changes over several decades across largely inaccessible mountainous regions. As consistent methodology is used for all glaciers, results will likely reveal significant spatial and temporal patterns in regional ice mass balance. Ultimately, these findings could have important implications for future water resource management in light of environmental change.

Hg transfer from contaminated soils to plants and animals

NARCIS (Netherlands)

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

2012-01-01

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

Purity Assessment of Organic Reference Materials with a Mass Balance Method: A Case Study of Endosulfan-II

International Nuclear Information System (INIS)

Kim, Seunghyun; Lee, Joonhee; Ahn, Seonghee; Song, Youngsin; Kim, Dongkyun; Kim, Byungjoo

2013-01-01

A mass balance method established in this laboratory was applied to determine the purity of an endosulfan-II pure substance. Gas chromatography-flame ionization detector (GC-FID) was used to measure organic impurities. Total of 10 structurally related organic impurities were detected by GC-FID in the material. Water content was determined to be 0.187% by Karl-Fischer (K-F) coulometry with an oven-drying method. Nonvolatile residual impurities was not detected by Thermal gravimetric analysis (TGA) within the detection limit of 0.04% (0.7 μg in absolute amount). Residual solvents within the substance were determined to be 0.007% in the Endosulfan-II pure substance by running GC-FID after dissolving it with two solvents. The purity of the endosulfan-II was finally assigned to be (99.17 ± 0.14)%. Details of the mass balance method including interpretation and evaluating uncertainties of results from each individual methods and the finally assayed purity were also described

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

Energy Technology Data Exchange (ETDEWEB)

Dutton, Jessica, E-mail: dutton.jess@gmail.com; Fisher, Nicholas S., E-mail: nfisher@notes.cc.sunysb.edu

2011-08-15

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

Changes in the Mass Balance of the Greenland Ice Sheet in a Warming Climate During 2003-2009

Science.gov (United States)

Zwally, H. Jay; Luthcke, Scott

2010-01-01

Mass changes of the Greenland ice sheet (GIS) derived from ICESat and GRACE data both show that the net mass loss from GIS during 2003-2009 is about 175 Gt/year, which contributes 0.5mm/yr global sea-level rise. The rate of mass loss has increased significantly since the 1990's when the GIS was close to mass balance. Even though the GIS was close to mass balance during the 1990's, it was already showing characteristics of responding to8 warmer climate, specifically thinning at the margins and thickening inland at higher elevations. During 2003-2009, increased ice thinning due to increases in melting and acceleration of outlet glaciers began to strongly exceed the inland thickening from increases in accumulation. Over the entire GIS, the mass loss between the two periods, from increased melting and ice dynamics, increased by about 190 Gt/year while the mass gain, from increased precipitation and accumulation, increased by only about 15Gt/year. These ice changes occurred during a time when the temperature on GIS changed at rate of about 2K/decade. The distribution of elevation and mass changes derived from ICESat have high spatial resolution showing details over outlet glaciers, by drainage systems, and by elevation. However, information on the seasonal cycle of changes from ICESat data is limited, because the ICESat lasers were only operated during two to three campaigns per year of about 35 days duration each. In contrast, the temporal resolution of GRACE data, provided by the continuous data collection, is much better showing details of the seasonal cycle and the inter-annual variability. The differing sensitivity of the ICESat altimetry and the GRACE gravity methods to motion of the underlying bedrock from glacial isostatic adjustment (GIA) is used to evaluate the GIA corrections provided by models. The two data types are also combined to make estimates of the partitioning of the mass gains and losses among accumulation, melting, and ice discharge from outlet

Life cycle inventory and mass-balance of municipal food waste management systems: Decision support methods beyond the waste hierarchy.

Science.gov (United States)

Edwards, Joel; Othman, Maazuza; Crossin, Enda; Burn, Stewart

2017-11-01

When assessing the environmental and human health impact of a municipal food waste (FW) management system waste managers typically rely on the principles of the waste hierarchy; using metrics such as the mass or rate of waste that is 'prepared for recycling,' 'recovered for energy,' or 'sent to landfill.' These metrics measure the collection and sorting efficiency of a waste system but are incapable of determining the efficiency of a system to turn waste into a valuable resource. In this study a life cycle approach was employed using a system boundary that includes the entire waste service provision from collection to safe end-use or disposal. A life cycle inventory of seven waste management systems was calculated, including the first service wide inventory of FW management through kitchen in-sink disposal (food waste disposer). Results describe the mass, energy and water balance of each system along with key emissions profile. It was demonstrated that the energy balance can differ significantly from its' energy generation, exemplified by mechanical biological treatment, which was the best system for generating energy from waste but only 5 th best for net-energy generation. Furthermore, the energy balance of kitchen in-sink disposal was shown to be reduced because 31% of volatile solids were lost in pre-treatment. The study also confirmed that higher FW landfill diversion rates were critical for reducing many harmful emissions to air and water. Although, mass-balance analysis showed that the alternative end-use of the FW material may still contain high impact pollutants. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Sensitivity of a Chemical Mass Balance model for PM2.5 to source profiles for differing styles of cooking

Science.gov (United States)

Abdullahi, K. L.; Delgado-Saborit, J. M.; Harrison, Roy M.

2018-04-01

Use of a Chemical Mass Balance model is one of the two most commonly used approaches to estimating atmospheric concentrations of cooking aerosol. Such models require the input of chemical profiles for each of the main sources contributing to particulate matter mass and there is appreciable evidence from the literature that not only the mass emission but also the chemical composition of particulate matter varies according to the food being prepared and the style of cooking. In this study, aerosol has been sampled in the laboratory from four different styles of cooking, i.e. Indian, Chinese, Western and African cooking. The chemical profiles of molecular markers have been quantified and are used individually within a Chemical Mass Balance model applied to air samples collected in a multi-ethnic area of Birmingham, UK. The model results give a source contribution estimate for cooking aerosol which is consistent with other comparable UK studies, but also shows a very low sensitivity of the model to the cooking aerosol profile utilised. A survey of local restaurants suggested a wide range of cooking styles taking place which may explain why no one profile gives an appreciably better fit in the CMB model.

Oblate shapes of 200,202,204Hg

International Nuclear Information System (INIS)

Bockisch, A.; Bharuth-Ram, K.; Kleinfeld, A.M.; Lieb, K.P.

1979-01-01

Measurements of the reorientation effect for the first excited 2 + states in 200 , 202 , 204 Hg were performed by exploiting the dependence of the γ-ray yield on Q 2 + for different projectiles. For 200 Hg, a positive quadrupole moment of Q 2 = 0.96 +- 0.11 eb (for negative interference) or Q 2 = 1.11 +- 0.11 eb (for positive interference) was determined indicating an oblate shape. Small positive Q 2 values were also found for 202 Hg and 204 Hg. Nine B(E2) values for excitation of the 2 + , 2 + ' and 4 + states in 196-204 Hg were measured. (orig.) [de

Respiratory mass spectrometer

Energy Technology Data Exchange (ETDEWEB)

Mostert, J.W. (Pretoria Univ. (South Africa). Dept. of Anesthesiology)

1983-06-01

The high degree of technical perfection of the respiratory mass spectrometer has rendered the instrument feasible for routine monitoring of anesthetized patients. It is proposed that the difference between inspired and expired oxygen tension in mm Hg be equated with whole body oxygen consumption in ml/min/M/sup 2/ body-surface area at STPD, by the expedient of multiplying tension-differences by a factor of 2. Years of experience have confirmed the value of promptly recognizing sudden drops in this l/E tension difference below 50 mm Hg indicative of metabolic injury from hypovolemia or respiratory depression. Rises in l/E tension-differences were associated with shivering as well as voluntary muscle activity. Tension differences of less than 25 mm Hg (equated with a whole-body O/sub 2/ consumption of less than 50 ml O/sub 2//min/M/sup 2/) occurred in a patient in the sitting position for posterior fossa exploration without acidosis, hypoxia or hypotension for several hours prior to irreversible cardiac arrest. The value of clinical monitoring by mass spectrometry is especially impressive in open-heart surgery.

A ratiometric electrochemical biosensor for sensitive detection of Hg2+ based on thymine-Hg2+-thymine structure.

Science.gov (United States)

Xiong, Erhu; Wu, Liang; Zhou, Jiawan; Yu, Peng; Zhang, Xiaohua; Chen, Jinhua

2015-01-01

In this paper, a simple, selective and reusable electrochemical biosensor for the sensitive detection of mercury ions (Hg(2+)) has been developed based on thymine (T)-rich stem-loop (hairpin) DNA probe and a dual-signaling electrochemical ratiometric strategy. The assay strategy includes both "signal-on" and "signal-off" elements. The thiolated methylene blue (MB)-modified T-rich hairpin DNA capture probe (MB-P) firstly self-assembled on the gold electrode surface via Au-S bond. In the presence of Hg(2+), the ferrocene (Fc)-labeled T-rich DNA probe (Fc-P) hybridized with MB-P via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. As a result, the hairpin MB-P was opened, the MB tags were away from the gold electrode surface and the Fc tags closed to the gold electrode surface. These conformation changes led to the decrease of the oxidation peak current of MB (IMB), accompanied with the increase of that of Fc (IFc). The logarithmic value of IFc/IMB is linear with the logarithm of Hg(2+) concentration in the range from 0.5 nM to 5000 nM, and the detection limit of 0.08 nM is much lower than 10nM (the US Environmental Protection Agency (EPA) limit of Hg(2+) in drinking water). What is more, the developed DNA-based electrochemical biosensor could be regenerated by adding cysteine and Mg(2+). This strategy provides a simple and rapid approach for the detection of Hg(2+), and has promising application in the detection of Hg(2+) in real environmental samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Interactions of Hg(ii) with oligonucleotides having thymine-thymine mispairs. Optimization of an impedimetric Hg(ii) sensor.

Science.gov (United States)

Kamal, Ajar; She, Zhe; Sharma, Renu; Kraatz, Heinz-Bernhard

2017-05-21

The present work describes the effect of the number of thymine-thymine mispairs in single strand DNA probes on Hg(ii) interactions and further to develop a highly sensitive DNA based impedimetric sensor for Hg(ii) detection. To achieve this goal, the influence of the number of T-T mispairs on the signal response prompted by DNA-Hg(ii) binding interactions was examined on three designed DNA probes: 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCACACGTTCCTTACGC-3', 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCACATTTTCCTTTTGC-3', 5'-OH-(CH 2 ) 6 -S-S-(CH 2 ) 6 -AGTCCATTTTTTCCTTTTTT-3' having 2T-T, 4T-T and 6T-T mispairs with identical length, respectively. This study revealed that the number of T-T mispairs plays a critical role in maximizing the signal intensity of DNA-Hg(ii) binding interactions. Based on these results, DNA comprising maximum number of T-T mispairs was further utilized for construction of the Hg(ii) sensor, which exhibited a linear correlation between the change in charge transfer resistance (ΔR CT ) and the concentration of Hg(ii) over the range of 1.0 × 10 -5 M to 1.0 × 10 -10 M with a lower detection limit of 3.2 × 10 -11 M. The selectivity was tested against 12 different metal ions including Hg(ii). The ΔR CT response from Hg(ii) is 3 times higher than the nearest competitor Pb(ii) and approximately 10 times than other ions. The potential application of such a robust and label-free DNA sensor was demonstrated by analyzing environmental samples collected from Lake Ontario.

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

Science.gov (United States)

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

2012-04-01

measured during the first cruise ranges from about 110 to 1500 ng · m-2day-1. This range is 1-2 order of magnitude higher than most of marine environments (Pacific Ocean, Mediterranean Sea, Artic Ocean) and some important polluted marine areas, such as the Tokyo Bay (19-259 ng · m-2day-1)b and the Yellow Sea (156-722 ng · m-2day-1)c. Further estimates on Hg atmospheric deposition flux (wet and dry) and biomonitoring are required for finally assessing a mass balance of Hg in Augusta basin. aLindberg et al., 2007. A Journal of the Human Environment, 3, 19-33. bNarukawa et al., 2006. Journal of Oceanography, 62, 249-257. cCi et al., 2011. Atmosphere Chemistry and Physics, 11, 2881-2892.

A semi-automated approach to derive elevation time-series and calculate glacier mass balance from historical aerial imagery

Science.gov (United States)

Whorton, E.; Headman, A.; Shean, D. E.; McCann, E.

2017-12-01

Understanding the implications of glacier recession on water resources in the western U.S. requires quantifying glacier mass change across large regions over several decades. Very few glaciers in North America have long-term continuous field measurements of glacier mass balance. However, systematic aerial photography campaigns began in 1957 on many glaciers in the western U.S. and Alaska. These historical, vertical aerial stereo-photographs documenting glacier evolution have recently become publically available. Digital elevation models (DEM) of the transient glacier surface preserved in each imagery timestamp can be derived, then differenced to calculate glacier volume and mass change to improve regional geodetic solutions of glacier mass balance. In order to batch process these data, we use Python-based algorithms and Agisoft Photoscan structure from motion (SfM) photogrammetry software to semi-automate DEM creation, and orthorectify and co-register historical aerial imagery in a high-performance computing environment. Scanned photographs are rotated to reduce scaling issues, cropped to the same size to remove fiducials, and batch histogram equalization is applied to improve image quality and aid pixel-matching algorithms using the Python library OpenCV. Processed photographs are then passed to Photoscan through the Photoscan Python library to create DEMs and orthoimagery. To extend the period of record, the elevation products are co-registered to each other, airborne LiDAR data, and DEMs derived from sub-meter commercial satellite imagery. With the exception of the placement of ground control points, the process is entirely automated with Python. Current research is focused on: one, applying these algorithms to create geodetic mass balance time series for the 90 photographed glaciers in Washington State and two, evaluating the minimal amount of positional information required in Photoscan to prevent distortion effects that cannot be addressed during co

NETPATH-WIN: an interactive user version of the mass-balance model, NETPATH

Science.gov (United States)

El-Kadi, A. I.; Plummer, Niel; Aggarwal, P.

2011-01-01

NETPATH-WIN is an interactive user version of NETPATH, an inverse geochemical modeling code used to find mass-balance reaction models that are consistent with the observed chemical and isotopic composition of waters from aquatic systems. NETPATH-WIN was constructed to migrate NETPATH applications into the Microsoft WINDOWS® environment. The new version facilitates model utilization by eliminating difficulties in data preparation and results analysis of the DOS version of NETPATH, while preserving all of the capabilities of the original version. Through example applications, the note describes some of the features of NETPATH-WIN as applied to adjustment of radiocarbon data for geochemical reactions in groundwater systems.

Mathematical modeling of water mass balance for proton exchange membrane fuel cell

International Nuclear Information System (INIS)

Wan Ramli Wan Daud; Kamaruzzaman Sopian; Jaafar Sahari; Nik Suhaimi Mat Hassan

2006-01-01

Gas and water management are key to achieving good performance from a proton exchange membrane fuel cell (PEMFC) stack. Water plays a critical role in PEMFC. The proton conductivity is increase with the water content. In order to achieve enough hydration, water is normally introduced into the cell externally by a variety of methods such as liquid injection, steam introduction, and humidification of reactants by passing them through humidifiers before entering the cell. In this paper, mathematical modeling of water mass balance for PEMFC at anode and cathode side are proposed by using external humidification and assume that steady state, constant pressure, constant temperature and gases distribution are uniform

40 CFR 60.4111 - Alternate Hg designated representative.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Alternate Hg designated representative... Times for Coal-Fired Electric Steam Generating Units Hg Designated Representative for Hg Budget Sources § 60.4111 Alternate Hg designated representative. (a) A certificate of representation under § 60.4113...

Alfacalcidol improves muscle power, muscle function and balance in elderly patients with reduced bone mass.

Science.gov (United States)

Schacht, E; Ringe, Johann D

2012-01-01

We investigated the effect of daily therapy with 1 mcg alfacalcidol (Doss(®)-TEVA/AWD-pharma) on muscle power, muscle function, balance performance and fear of falls in an open, multi-centered, uncontrolled, prospective study on a cohort of patients with reduced bone mass. Among the 2,097 participants, 87.1% were post-menopausal women and 12.9% were men. Mean age was 74.8 years and mean body mass index (BMI) 26.3 kg/m². A total of 75.3% of the study population had osteoporosis, 81% a diagnosis of "increased risk of falls" and 70.1% had a creatinine clearance (CrCl) of power tests at onset and after 3 and 6 months: the timed up and go test (TUG) and the chair rising test (CRT). At baseline and after 6 months, participants performed the tandem gait test (TGT) and filled out a questionnaire evaluating fear of falling. Successful performance in the muscle tests is associated with a significantly lower risk of falls and non-vertebral fractures in elderly patients (successful test performance: TUG ≤ 10 s (sec), CRT ≤ 10 s, TGT ≥ 8 steps). A significant improvement in the performance of the two muscle tests was proved already after 3 months of treatment with alfacalcidol and further increased by the end of the therapeutic intervention. There were significant increases in the number of participants able to successfully perform the tests: 24.6% at baseline and 46.3% at the end of trial for the TUG (P balance test (TGT) increased from 36.0% at onset to 58.6% at the end of the trial (P power, muscle function and balance and reduces fear of falls. The significant improvement in the three muscle and balance tests and fear of falls may have a preventative effect on falls and fractures. We suggest that the quantitative risk tests used in this study could be reliable surrogate parameters for the risk of falls and fractures in elderly patients.

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

Science.gov (United States)

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

2000-01-01

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

Modeling and experimental validation of water mass balance in a PEM fuel cell stack

DEFF Research Database (Denmark)

Liso, Vincenzo; Araya, Samuel Simon; Olesen, Anders Christian

2016-01-01

Polymer electrolyte membrane (PEM) fuel cells require good hydration in order to deliver high performance and ensure long life operation. Water is essential for proton conductivity in the membrane which increases by nearly six orders of magnitude from dry to fully hydrated. Adequate water...... management in PEM fuel cell is crucial in order to avoid an imbalance between water production and water removal from the fuel cell. In the present study, a novel mathematical zero-dimensional model has been formulated for the water mass balance and hydration of a polymer electrolyte membrane. This model...... is validated against experimental data. In the results it is shown that the fuel cell water balance calculated by this model shows better fit with experimental data-points compared with model where only steady state operation were considered. We conclude that this discrepancy is due a different rate of water...

Treating a 20 mm Hg gradient alleviates myocardial hypertrophy in experimental aortic coarctation.

Science.gov (United States)

Wendell, David C; Friehs, Ingeborg; Samyn, Margaret M; Harmann, Leanne M; LaDisa, John F

2017-10-01

Children with coarctation of the aorta (CoA) can have a hyperdynamic and remodeled left ventricle (LV) from increased afterload. Literature from an experimental model suggests the putative 20 mm Hg blood pressure gradient (BPG) treatment guideline frequently implemented in CoA studies may permit irreversible vascular changes. LV remodeling from pressure overload has been studied, but data are limited following correction and using a clinically representative BPG. Rabbits underwent CoA at 10 weeks to induce a 20 mm Hg BPG using permanent or dissolvable suture thereby replicating untreated and corrected CoA, respectively. Cardiac function was evaluated at 32 weeks by magnetic resonance imaging using a spoiled cine GRE sequence (TR/TE/FA 8/2.9/20), 14 × 14-cm FOV, and 3-mm slice thickness. Images (20 frames/cycle) were acquired in 6-8 short axis views from the apex to the mitral valve annulus. LV volume, ejection fraction (EF), and mass were quantified. LV mass was elevated for CoA (5.2 ± 0.55 g) versus control (3.6 ± 0.16 g) and corrected (4.0 ± 0.44 g) rabbits, resulting in increased LV mass/volume ratio for CoA rabbits. A trend toward increased EF and stroke volume was observed but did not reach significance. Elevated EF by volumetric analysis in CoA rabbits was supported by concomitant increases in total aortic flow by phase-contrast magnetic resonance imaging. The indices quantified trended toward a persistent hyperdynamic LV despite correction, but differences were not statistically significant versus control rabbits. These findings suggest the current putative 20 mm Hg BPG for treatment may be reasonable from the LV's perspective. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009

Science.gov (United States)

Zwally, H. Jay; Giovinetto, Mario B.

2011-01-01

Published mass balance estimates for the Antarctic Ice Sheet (AIS) lie between approximately +50 to -250 Gt/year for 1992 to 2009, which span a range equivalent to 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar-altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (+28 and -31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (-40 to -246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. Although recent reports of large and accelerating rates of mass loss from GRACE=based studies cite agreement with IOM results, our evaluation does not support that conclusion. We find that the extrapolation used in the published IOM estimates for the 15 % of the periphery for which discharge velocities are not observed gives twice the rate of discharge per unit of associated ice-sheet area than the 85% faster-moving parts. Our calculations show that the published extrapolation overestimates the ice discharge by 282 Gt/yr compared to our assumption that the slower moving areas have 70% as much discharge per area as the faster moving parts. Also, published data on the time-series of discharge velocities and accumulation/precipitation do not support mass output increases or input decreases with time, respectively. Our modified IOM estimate, using the 70% discharge assumption and substituting input from a field-data compilation for input from an atmospheric model over 6% of area, gives a loss of only 13 Gt/year (versus 136 Gt/year) for the period around 2000. Two ERS-based estimates, our modified IOM, and a GRACE-based estimate for observations within 1992 to 2005 lie in a narrowed range of +27 to - 40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992-2001 is - 47 Gt

Application of a contaminant mass balance method at an old landfill to assess the impact on water resources

DEFF Research Database (Denmark)

Thomsen, Nanna Isbak; Milosevic, Nemanja; Bjerg, Poul Løgstrup

2012-01-01

linking soil and groundwater contamination to surface water pollution are required. This paper presents a method which provides an estimate of the contaminant mass discharge, using a combination of a historical investigation and contaminant mass balance approach. The method works at the screening level...... and could be part of a risk assessment. The study site was Risby Landfill, an old unlined landfill located in a clay till setting on central Zealand, Denmark. The contaminant mass discharge was determined for three common leachate indicators: chloride, dissolved organic carbon and ammonium. For instance......, the mass discharge of chloride from the landfill was 9.4ton/year and the mass discharge of chloride to the deep limestone aquifer was 1.4ton/year. This resulted in elevated concentrations of leachate indicators (chloride, dissolved organic carbon and ammonium) in the groundwater. The mass discharge...

Intracellular Hg(0) Oxidation in Desulfovibrio desulfuricans ND132.

Science.gov (United States)

Wang, Yuwei; Schaefer, Jeffra K; Mishra, Bhoopesh; Yee, Nathan

2016-10-03

The disposal of elemental mercury (Hg(0)) wastes in mining and manufacturing areas has caused serious soil and groundwater contamination issues. Under anoxic conditions, certain anaerobic bacteria can oxidize dissolved elemental mercury and convert the oxidized Hg to neurotoxic methylmercury. In this study, we conducted experiments with the Hg-methylating bacterium Desulfovibrio desulfuricans ND132 to elucidate the role of cellular thiols in anaerobic Hg(0) oxidation. The concentrations of cell-surface and intracellular thiols were measured, and specific fractions of D. desulfuricans ND132 were examined for Hg(0) oxidation activity and analyzed with extended X-ray absorption fine structure (EXAFS) spectroscopy. The experimental data indicate that intracellular thiol concentrations are approximately six times higher than those of the cell wall. Cells reacted with a thiol-blocking reagent were severely impaired in Hg(0) oxidation activity. Spheroplasts lacking cell walls rapidly oxidized Hg(0) to Hg(II), while cell wall fragments exhibited low reactivity toward Hg(0). EXAFS analysis of spheroplast samples revealed that multiple different forms of Hg-thiols are produced by the Hg(0) oxidation reaction and that the local coordination environment of the oxidized Hg changes with reaction time. The results of this study indicate that Hg(0) oxidation in D. desulfuricans ND132 is an intracellular process that occurs by reaction with thiol-containing molecules.

Greenland Surface Mass Balance as Simulated by the Community Earth System Model. Part II: Twenty-First-Century Changes

NARCIS (Netherlands)

Vizcaino, M.; Lipscomb, W.H.; Sacks, W.J.; van den Broeke, M.R.

2014-01-01

This study presents the first twenty-first-century projections of surface mass balance (SMB) changes for the Greenland Ice Sheet (GIS) with the Community Earth System Model (CESM), which includes a new ice sheet component. For glaciated surfaces, CESM includes a sophisticated calculation of energy

Luminescent turn-on detection of Hg(II) via the quenching of an iridium(III) complex by Hg(II)-mediated silver nanoparticles.

Science.gov (United States)

Liu, Jinshui; Vellaisamy, Kasipandi; Yang, Guanjun; Leung, Chung-Hang; Ma, Dik-Lung

2017-06-15

A novel luminescent turn-on detection method for Hg(II) was developed. The method was based on the silver nanoparticle (AgNP)-mediated quenching of Ir(III) complex 1. The addition of Hg(II) ions causes the luminescence of complex 1 to be recovered due to the oxidation of AgNPs by Hg(II) ions to form Ag(I) and Ag/Hg amalgam. The luminescence intensity of 1 increased in accord with an increased Hg(II) concentration ranging from 0 nM to 180 nM, with the detection limit of 5 nM. This approach offers an innovative method for the quantification of Hg(II).

40 CFR 60.4160 - Submission of Hg allowance transfers.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Submission of Hg allowance transfers... Times for Coal-Fired Electric Steam Generating Units Hg Allowance Transfers § 60.4160 Submission of Hg allowance transfers. An Hg authorized account representative seeking recordation of a Hg allowance transfer...

Mercury mass measurement in fluorescent lamps via neutron activation analysis

International Nuclear Information System (INIS)

Viererbl, L.; Vinš, M.; Lahodová, Z.; Fuksa, A.; Kučera, J.; Koleška, M.; Voljanskij, A.

2015-01-01

Mercury is an essential component of fluorescent lamps. Not all fluorescent lamps are recycled, resulting in contamination of the environment with toxic mercury, making measurement of the mercury mass used in fluorescent lamps important. Mercury mass measurement of lamps via instrumental neutron activation analysis (NAA) was tested under various conditions in the LVR-15 research reactor. Fluorescent lamps were irradiated in different positions in vertical irradiation channels and a horizontal channel in neutron fields with total fluence rates from 3×10 8 cm −2 s −1 to 10 14 cm −2 s −1 . The 202 Hg(n,γ) 203 Hg nuclear reaction was used for mercury mass evaluation. Activities of 203 Hg and others induced radionuclides were measured via gamma spectrometry with an HPGe detector at various times after irradiation. Standards containing an Hg 2 Cl 2 compound were used to determine mercury mass. Problems arise from the presence of elements with a large effective cross section in luminescent material (europium, antimony and gadolinium) and glass (boron). The paper describes optimization of the NAA procedure in the LVR-15 research reactor with particular attention to influence of neutron self-absorption in fluorescent lamps. - Highlights: • Mercury is an essential component of fluorescent lamps. • Fluorescent lamps were irradiated in neutron fields in research reactor. • 203 Hg induced radionuclide activity was measured using gamma spectrometry. • Mercury mass in fluorescent lamps can be measured by neutron activation analysis.

Offspring Hg exposure relates to parental feeding strategies in a generalist bird with strong individual foraging specialization.

Science.gov (United States)

Santos, Cátia S A; Blondel, Léa; Sotillo, Alejandro; Müller, Wendt; Stienen, Eric W M; Boeckx, Pascal; Soares, Amadeu M V M; Monteiro, Marta S; Loureiro, Susana; de Neve, Liesbeth; Lens, Luc

2017-12-01

Generalist species can potentially exploit a wide variety of resources, but at the individual level they often show a certain degree of foraging specialization. Specific foraging strategies, however, may increase exposure to environmental contaminants that can alter the cost-benefit balance of consuming particular food items. The Lesser Black-backed Gull (Larus fuscus) is known to opportunistically feed on a wide range of marine and terrestrial prey that differ in contaminant load, such as mercury (Hg) that strongly biomagnifies through the aquatic food web. The hypothesis tested in this study were: i) a predominant use of marine prey by females during egg-formation and by both parents during chick rearing increases the exposure to Hg during embryonic development and chick growth, and ii) this affects parental investment in clutch volume, chick growth and body condition. Total Hg burden and isotopic signatures of carbon (δ 13 C) and nitrogen (δ 15 N) were determined for eggs, down feathers, and primary feathers of L. fuscus chicks collected at a coastal colony in Belgium. As expected, eggs and feathers of chicks from parents with a stable isotope signature that suggested a predominantly marine diet had higher levels of Hg. The use of marine resources by females during the egg-formation period positively correlated to maternal investment in egg size, though entailing the cost of increased Hg-concentrations which in turn negatively affected clutch volume. Furthermore, it is shown that the use of chick down feathers is a suitable matrix to non-lethally estimate Hg concentrations in eggs. Contrary to our expectations, no relationship between Hg exposure and chick growth or chick body condition was found, which may be due the low concentrations found. We conclude that currently Hg contamination does not constitute a risk for development and condition of L. fuscus offspring at the levels currently observed at the Belgian coast. Copyright © 2017 Elsevier B.V. All

A benzothiazole-based fluorescent probe for distinguishing and bioimaging of Hg{sup 2+} and Cu{sup 2+}

Energy Technology Data Exchange (ETDEWEB)

Gu, Biao; Huang, Liyan; Su, Wei; Duan, Xiaoli; Li, Haitao, E-mail: haitao-li@hunnu.edu.cn; Yao, Shouzhuo

2017-02-15

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

Supplementing an energy adequate, higher protein diet with protein does not enhance fat-free mass restoration after short-term severe negative energy balance.

Science.gov (United States)

Berryman, C E; Sepowitz, J J; McClung, H L; Lieberman, H R; Farina, E K; McClung, J P; Ferrando, A A; Pasiakos, S M

2017-06-01

Negative energy balance during military operations can be severe and result in significant reductions in fat-free mass (FFM). Consuming supplemental high-quality protein following such military operations may accelerate restoration of FFM. Body composition (dual-energy X-ray absorptiometry) and whole body protein turnover (single-pool [ 15 N]alanine method) were determined before (PRE) and after 7 days (POST) of severe negative energy balance during military training in 63 male US Marines (means ± SD, 25 ± 3 yr, 84 ± 9 kg). After POST measures were collected, volunteers were randomized to receive higher protein (HIGH: 1,103 kcal/day, 133 g protein/day), moderate protein (MOD: 974 kcal/day, 84 g protein/day), or carbohydrate-based low protein control (CON: 1,042 kcal/day, 7 g protein/day) supplements, in addition to a self-selected, ad libitum diet, for the 27-day intervention (REFED). Measurements were repeated POST-REFED. POST total body mass (TBM; -5.8 ± 1.0 kg, -7.0%), FFM (-3.1 ± 1.6 kg, -4.7%), and net protein balance (-1.7 ± 1.1 g protein·kg -1 ·day -1 ) were lower and proteolysis (1.1 ± 1.9 g protein·kg -1 ·day -1 ) was higher compared with PRE ( P energy (4,498 ± 725 kcal/day). All volunteers, independent of group assignment, achieved positive net protein balance (0.4 ± 1.0 g protein·kg -1 ·day -1 ) and gained TBM (5.9 ± 1.7 kg, 7.8%) and FFM (3.6 ± 1.8 kg, 5.7%) POST-REFED compared with POST ( P energy-adequate, higher protein diets with additional protein may not be necessary to restore FFM after short-term severe negative energy balance. NEW & NOTEWORTHY This article demonstrates 1 ) the majority of physiological decrements incurred during military training (e.g., total and fat-free mass loss), with the exception of net protein balance, resolve and return to pretraining values after 27 days and 2 ) protein supplementation, in addition to an ad libitum, higher protein (~2.0 g·kg -1 ·day -1 ), energy adequate diet, is not necessary to

Logs and completion data for water and mass balance wells in Mortandad and Ten Site Canyons

International Nuclear Information System (INIS)

McLin, S.G.; Koch, R.J.

1997-10-01

Twenty-four monitoring wells were drilled and completed in December 1994 as part of a water and mass balance study for the shallow perched aquifer in the Mortandad Canyon alluvium and in the lower part of Ten-Site Canyon. The wells penetrated the alluvium containing the aquifer and were completed into the top of the weathered tuff. Twelve of these wells encountered the Tshirege Member (Cooing Unit 1 g) of the Bandelier Tuff below the canyon alluvium, while ten wells made contact with the Cerro Toledo interval, which lies between the Tshirege and Otowi Members of the Bandelier Tuff. The remaining two wells were completed into the alluvium above the weathered tuff contact. These wells provide access for continuous water level measurement and water sampling. Data from these new wells will be used to determine changes in alluvial aquifer water storage, water quality sampling, and estimation of seepage into the unsaturated Bandelier Tuff below the alluvium. This report documents drilling activities and well completion logs for the water and mass balance study. These wells also provide critical new data for fourteen north-south vertical cross-sections constructed for the canyon alluvium

Immobilization of aqueous Hg(II) by mackinawite (FeS)

International Nuclear Information System (INIS)

Liu Jianrong; Valsaraj, Kalliat T.; Devai, Istvan; DeLaune, R.D.

2008-01-01

As one of the major constituents of acid volatile sulfide (AVS) in anoxic sediments, mackinawite (FeS) is known for its ability to scavenge trace metals. The interaction between aqueous Hg(II) (added as HgCl 2 ) and synthetic FeS was studied via batch sorption experiments conducted under anaerobic conditions. Due to the release of H + during formation of hydrolyzed Hg(II) species which is more reactive than Hg 2+ in surface adsorption, the equilibrium pH decreased with the increase in Hg(II)/FeS molar ratio. Counteracting the loss of FeS solids at lower pH, the maximum capacity for FeS to remove aqueous Hg(II) was approximately 0.75 mol Hg(II) (mol FeS) -1 . The comparison of X-ray power diffraction (XRPD) patterns of synthetic FeS sorbent before and after sorption showed that the major products formed from the interaction between FeS and the aqueous Hg(II) were metacinnabar, cinnabar, and mercury iron sulfides. With the addition of FeS at 0.4 g L -1 to a 1 mM Hg(II) solution with an initial pH of 5.6, Fe 2+ release was approximately 0.77 mol Fe 2+ per mol Hg(II) removed, suggesting that 77% of Hg(II) was removed via precipitation reaction under these conditions, with 23% of Hg(II) removed by adsorption. Aeration does not cause significant release of Hg(II) into the water phase

Injury of Hg2+ and DBS on Lemna minor%Hg2+、DBS对浮萍的伤害研究

Institute of Scientific and Technical Information of China (English)

马剑敏; 王琳; 杜晋立; 吴晶敏

2001-01-01

The injury degree of Lemna minor by the stress of Hg2+ and DBSare reported.The concentrations of chlorophyll and dissolved protein decrease with the increase of Hg2+ and DBS concentrations or as treatment time is continued,dead percentage increase with the increase of Hg2+ and DBS concentrations or as treatment time is continued.When the concentrations of HgCl2 is 6mg/L or DBS is 12mg/L,about 70% of Lemna minor can live for 10 days at least.%研究了在Hg2+、DBS胁迫下，浮萍(LemnaminorL.)植株的枯死率、叶绿素含量和可溶性蛋白质含量的变化。植株的枯死率随Hg2+、DBS浓度升高和处理时间的延长而增加；叶绿素和蛋白质含量随Hg2+和DBS浓度升高和处理时间的延长而逐渐下降。在HgCl2、DBS浓度分别为6mg/L、12mg/L时，约70%的浮萍10d内仍存活。

Fourier transform nuclear magnetic resonance studies of 199Hg

International Nuclear Information System (INIS)

Krueger, H.; Lutz, O.; Nolle, A.; Schwenk, A.

1975-01-01

199 Hg Fourier Transform NMR studies of various solutions of diverse mercury salts in H 2 O and D 2 O or in the appropriate protonated and deuterated acids are reported for both Hg 2 ++ and Hg ++ . In the different solutions investigated the 199 Hg line positions depend on the concentration of the solution, on the solvents and their isotopic composition and on the temperature of the sample. A ratio of the Larmor frequency of 199 Hg and of 2 H in a Hg(NO 3 ) 2 solution in dilute DNO 3 is given. Using this ratio and the measured chemical shifts, a ratio of the Larmor frequencies of 199 Hg for infinite dilution relative to 2 H in pure D 2 O is given. From this a g 1 -factor for 199 Hg is derived and compared with the g 1 -factor of an optical pumping experiment. The resulting shielding constant is sigma (hydrated 199 Hg ++ versus 199 Hg atom) = -24.32(5) x 10 -4 . This yields an atomic reference scale for all measured NMR line shifts of mercury. (orig.) [de

OXALATE MASS BALANCE DURING CHEMICAL CLEANING IN TANK 6F

Energy Technology Data Exchange (ETDEWEB)

Poirier, M.; Fink, S.

2011-07-22

The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.

Comparison of mass balance, energy consumption and cost of composting facilities for different types of organic waste

International Nuclear Information System (INIS)

Zhang Huijun; Matsuto, Toshihiko

2011-01-01

Mass balance, energy consumption and cost are basic pieces of information necessary for selecting a waste management technology. In this study, composting facilities that treat different types of organic waste were studied by questionnaire survey and via a chemical analysis of material collected at the facilities. The mass balance was calculated on a dry weight basis because the moisture content of organic waste was very high. Even though the ratio of bulking material to total input varied in the range 0-65% on a dry basis, the carbon and ash content, carbon/nitrogen ratio, heavy metal content and inorganic nutrients in the compost were clearly influenced by the different characteristics of the input waste. The use of bulking material was not correlated with ash or elemental content in the compost. The operating costs were categorised into two groups. There was some economy of scale for wages and maintenance cost, but the costs for electricity and fuel were proportional to the amount of waste. Differences in operating costs can be explained by differences in the process characteristics.

Design and synthesis of BODIPY-clickate based Hg(2+) sensors: the effect of triazole binding mode with Hg(2+) on signal transduction.

Science.gov (United States)

Vedamalai, Mani; Kedaria, Dhaval; Vasita, Rajesh; Mori, Shigeki; Gupta, Iti

2016-02-14

BODIPY-clickates, F1 and F2, for the detection of Hg(2+) have been designed, synthesized and characterized. Both F1 and F2 showed hyperchromic shifts in the UV-visible spectra in response to increasing Hg(2+) concentrations. Hg(2+) ion binding caused perturbation of the emission quenching process and chelation induced enhanced bathochromic emission of F1 and F2 to 620 nm and 660 nm, respectively. Job's plot clearly indicated that the binding ratio of F1 and F2 with Hg(2+) was 1 : 1. The NMR titration of BODIPY-clickates with Hg(2+) confirmed that aromatic amines and triazoles were involved in the binding event. Furthermore, HRMS data of F1-Hg(2+) and F2-Hg(2+) supported the formation of mercury complexes of BODIPY-clickates. The dissociation constant for the interaction between fluorescent probes F1 and F2 with Hg(2+) was found to be 24.4 ± 5.1 μM and 22.0 ± 3.9 μM, respectively. The Hg(2+) ion induced fluorescence enhancement was almost stable in a pH range of 5 to 8. Having less toxicity to live cells, both the probes were successfully used to map the Hg(2+) ions in live A549 cells.