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Sample records for surface water hg

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

    Directory of Open Access Journals (Sweden)

    Kotnik J.

    2013-04-01

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

  2. Assessment of Cu, Pb and Hg Contamination in Bottom Sediments Of Surface Water in XuZhou

    Institute of Scientific and Technical Information of China (English)

    王晓; 韩宝平; 朱雪强

    2004-01-01

    Pollution of heavy metals Cu,Pb and Hg is assessed using geo-accumulation index in this paper. The result shows that the bottom sediments of surface water in Xuzhou is polluted by these heavy metals to deferent degrees, of which the Jinma River is the most serious, and then the Kuihe River, the abandoned Yellow River, and the Jinghang Canal. The Yunlong Lake has also been polluted by Hg. The three kinds of heavy metals in the order of concentration is Hg>Cu>Pb. The pollution degree and the type of element is closely related with industrial structure in Xuzhou.

  3. A competitive immunoassay for ultrasensitive detection of Hg{sup 2+} in water, human serum and urine samples using immunochromatographic test based on surface-enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    She, Pei; Chu, Yanxin [The Key Lab of Health Chemistry & Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering & Materials Science, Soochow University, Renai Road 199, Suzhou 215123 (China); Liu, Chunwei; Guo, Xun [OptoTrace (Suzhou) Technologies, Inc., STE 316, Building 4, No. 218, Xinghu Street, bioBAY, Suzhou Industrial Park, Suzhou 215123 (China); Zhao, Kang [The Key Lab of Health Chemistry & Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering & Materials Science, Soochow University, Renai Road 199, Suzhou 215123 (China); Li, Jianguo, E-mail: lijgsd@suda.edu.cn [The Key Lab of Health Chemistry & Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering & Materials Science, Soochow University, Renai Road 199, Suzhou 215123 (China); Du, Haijing; Zhang, Xiang [The Key Lab of Health Chemistry & Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering & Materials Science, Soochow University, Renai Road 199, Suzhou 215123 (China); Wang, Hong [OptoTrace (Suzhou) Technologies, Inc., STE 316, Building 4, No. 218, Xinghu Street, bioBAY, Suzhou Industrial Park, Suzhou 215123 (China); Deng, Anping, E-mail: denganping@suda.edu.cn [The Key Lab of Health Chemistry & Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering & Materials Science, Soochow University, Renai Road 199, Suzhou 215123 (China)

    2016-02-04

    An immunochromatographic test (ICT) strip was developed for ultrasensitive competitive immunoassay of Hg{sup 2+}. This strategy was achieved by combining the easy-operation and rapidity of ICT with the high sensitivity of surface-enhanced Raman scattering (SERS). Monoclonal antibody (mAb) against Hg{sup 2+} and Raman active substance 4-mercaptobenzoic acid (MBA) dual labelled gold nanoparticles (GNPs) were prepared as an immunoprobe. The Raman scattering intensity of MBA on the test line of the ICT strip was measured for quantitative determination of Hg{sup 2+}. The ICT was able to directly detect Hg{sup 2+} without complexing due to the specific recognition of the mAb with Hg{sup 2+}. The IC{sub 50} and limit of detection (LOD) of the assay for Hg{sup 2+} detection were 0.12 ng mL{sup −1} and 0.45 pg mL{sup −1}, respectively. There was no cross-reactivity (CR) of the assay with other nineteen ions and the ICT strips could be kept for 5 weeks without loss of activity. The recoveries of the assay for water, human serum and urine samples spiked with Hg{sup 2+} were in range of 88.3–107.3% with the relative standard deviations (RSD) of 1.5–9.5% (n = 3). The proposed ICT was used for the detection of Hg{sup 2+} in urine samples collected from Occupational Disease Hospital and the results were confirmed by cold-vapor atomic fluorescence spectroscopy (CV-AFS). The assay exhibited high sensitivity, selectivity, stability, precision and accuracy, demonstrating a promising method for the detection of trace amount of Hg{sup 2+} in environmental water samples and biological serum and urine samples. - Highlights: • The proposed ICT was able to directly detect Hg{sup 2+} without formation of Hg{sup 2+}-ligand complex. • The proposed ICT exhibited high sensitivity, specificity, stability, precision and accuracy for Hg{sup 2+} detection. • The proposed ICT was applicable for the detection of trace amount of Hg{sup 2+} in water, human serum and urine samples.

  4. A competitive immunoassay for ultrasensitive detection of Hg(2+) in water, human serum and urine samples using immunochromatographic test based on surface-enhanced Raman scattering.

    Science.gov (United States)

    She, Pei; Chu, Yanxin; Liu, Chunwei; Guo, Xun; Zhao, Kang; Li, Jianguo; Du, Haijing; Zhang, Xiang; Wang, Hong; Deng, Anping

    2016-02-01

    An immunochromatographic test (ICT) strip was developed for ultrasensitive competitive immunoassay of Hg(2+). This strategy was achieved by combining the easy-operation and rapidity of ICT with the high sensitivity of surface-enhanced Raman scattering (SERS). Monoclonal antibody (mAb) against Hg(2+) and Raman active substance 4-mercaptobenzoic acid (MBA) dual labelled gold nanoparticles (GNPs) were prepared as an immunoprobe. The Raman scattering intensity of MBA on the test line of the ICT strip was measured for quantitative determination of Hg(2+). The ICT was able to directly detect Hg(2+) without complexing due to the specific recognition of the mAb with Hg(2+). The IC50 and limit of detection (LOD) of the assay for Hg(2+) detection were 0.12 ng mL(-1) and 0.45 pg mL(-1), respectively. There was no cross-reactivity (CR) of the assay with other nineteen ions and the ICT strips could be kept for 5 weeks without loss of activity. The recoveries of the assay for water, human serum and urine samples spiked with Hg(2+) were in range of 88.3-107.3% with the relative standard deviations (RSD) of 1.5-9.5% (n = 3). The proposed ICT was used for the detection of Hg(2+) in urine samples collected from Occupational Disease Hospital and the results were confirmed by cold-vapor atomic fluorescence spectroscopy (CV-AFS). The assay exhibited high sensitivity, selectivity, stability, precision and accuracy, demonstrating a promising method for the detection of trace amount of Hg(2+) in environmental water samples and biological serum and urine samples.

  5. Enhanced spectrophotometric detection of Hg in water samples by surface plasmon resonance of Au nanoparticles after preconcentration with vortex-assisted liquid-liquid microextraction

    Science.gov (United States)

    Martinis, Estefanía M.; Wuilloud, Rodolfo G.

    2016-10-01

    This article presents an efficient, simple, and cost-effective method for the determination of trace amounts of Hg by vortex-assisted liquid-liquid microextraction (VALLME) coupled to microvolume UV-Vis spectrophotometry. This method correlates changes in the intensity of localized surface plasmon resonance (LSPR) of tetraoctylammonium bromide (TOABr) coated Au nanoparticles (NPs) after interaction with Hg2+ ion. Spectroscopic measurements of the TOABr-coated Au NPs phase with particular absorption properties (strong and well-defined absorption bands) after analyte extraction by VALLME, provide an accurate and sensitive determination of Hg in water samples, comparable with measurements obtained by atomic absorption spectrometry (AAS). Different variables including sample volume, extraction time, and TOABr-coated Au NPs dispersion volume were carefully studied; final experimental conditions were 5 mL, 120 μL and 5 min respectively. The limit of detection (LOD) was 0.8 ng mL- 1. The calibration curve was linear at concentrations between the limit of quantification (LOQ) (4.9 ng mL- 1) and up to at least 120 ng mL- 1 of Hg. The relative standard deviation for six replicate determinations of 20 ng mL- 1 of Hg was 4.7%. This method exhibited an excellent analytical performance in terms of selectivity and sensitivity and it was finally applied for Hg determination in spiked tap and mineral water samples.

  6. Hg Vetical Transference in Soil—Water System

    Institute of Scientific and Technical Information of China (English)

    GUOYIJUN; MOUSUSEN; 等

    1998-01-01

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

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

    Science.gov (United States)

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

    2011-12-01

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

  8. Interaction of Hg Atom with Bare Si(111) Surface

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-Jun; LIU Ying

    2006-01-01

    To evaluate the interaction between Hg atom and bare Si(111) surface, three types of silicon cluster models of Si4H7, Si7H10 and Si16H20 together with their Hg complexes were studied by using hybrid (U)B3LYP density functional theory method. Optimized geometries and energies for Hg atom on different adsorption sites indicate that: 1) the binding energies at different adsorption sites are small (ranging from ~3 to 8 kJ/mol dependent on the adsorption sites), suggesting a weak interaction between Hg atom and silicon surface; 2) the most favorable adsorption site is the on top (T) site. By analyzing their natural bonding orbitals, the possible reason of this difference is suggested.

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

    Directory of Open Access Journals (Sweden)

    Diéguez M.C.

    2014-07-01

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

  10. Surface Water & Surface Drainage

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data set contains boundaries for all surface water and surface drainage for the state of New Mexico. It is in a vector digital data structure digitized from a...

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

    Science.gov (United States)

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

    2007-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-07-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-01-01

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

  14. Influence of water and water vapour on the characteristics of KI treated HgI 2 detectors

    Science.gov (United States)

    Ponpon, J. P.; Amann, M.; Sieskind, M.

    After being cleaned using a potassium iodide solution in water followed by a water rinse, the surface of mercuric iodide is covered by a chemical complex identified as being KHgI 3·H 2O. This compound can adsorb large quantities of water and its electrical properties are strongly sensitive to water and water vapour. The consequences on the manufacturing and storing conditions (especially the relative humidity), of mercuric iodide-based devices are therefore of great concern. They are illustrated by the study of the electrical and spectrometric properties of HgI 2 nuclear radiation detectors.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Heny Suseno

    2015-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-01-15

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

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

    Science.gov (United States)

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

    2014-01-01

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

  20. Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jian, E-mail: zhaojian0209@aliyun.com [Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China); State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); He, Man-Chao [State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China)

    2014-10-30

    Highlights: • We investigated the adsorption of Cd, Cu, Hg, and Ni(II) on kaolinite(0 0 1) surface. • The adsorption capabilities of the kaolinite for HM atoms were Ni > Cu > Cd > Hg(II). • The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms. • The adsorption energy decreases with the coverage for Ni(II) atoms. - Abstract: Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail.

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

    Science.gov (United States)

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

    2007-08-25

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

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

    Science.gov (United States)

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

    2016-01-01

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

  3. Immobilization of Hg(II) in water with polysulfide-rubber (PSR) polymer-coated activated carbon.

    Science.gov (United States)

    Kim, Eun-Ah; Seyfferth, Angelia L; Fendorf, Scott; Luthy, Richard G

    2011-01-01

    An effective mercury removal method using polymer-coated activated carbon was studied for possible use in water treatment. In order to increase the affinity of activated carbon for mercury, a sulfur-rich compound, polysulfide-rubber (PSR) polymer, was effectively coated onto the activated carbon. The polymer was synthesized by condensation polymerization between sodium tetrasulfide and 1,2-dichloroethane in water. PSR-mercury interactions and Hg-S bonding were elucidated from x-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy analyses. The sulfur loading levels were controlled by the polymer dose during the coating process and the total surface area of the activated carbon was maintained for the sulfur loading less than 2 wt%. Sorption kinetic studies showed that PSR-coated activated carbon facilitates fast reaction by providing a greater reactive surface area than PSR alone. High sulfur loading on activated carbon enhanced mercury adsorption contributing to a three orders of magnitude reduction in mercury concentration. μ-X-ray absorption near edge spectroscopic analyses of the mercury bound to activated carbon and to PSR on activated carbon suggests the chemical bond with mercury on the surface is a combination of Hg-Cl and Hg-S interaction. The pH effect on mercury removal and adsorption isotherm results indicate competition between protons and mercury for binding to sulfur at low pH.

  4. Hg(II) removal from water by chitosan and chitosan derivatives: a review.

    Science.gov (United States)

    Miretzky, P; Cirelli, A Fernandez

    2009-08-15

    Mercury (Hg) is one of the most toxic heavy metals commonly found in the global environment. Its toxicity is related to the capacity of its compounds to bioconcentrate in organisms and to biomagnify through food chain. A wide range of adsorbents has been used for removing Hg(II) from contaminated water. Chitosan is obtained by alkaline deacetylation of chitin. The adsorption capacity of chitosan depends on the origin of the polysaccharide, and on the experimental conditions in the preparation, that determine the degree of deacetylation. A great number of chitosan derivatives have been obtained by crosslinking with glutaraldehyde or epichlorohydrin among others or by grafting new functional groups on the chitosan backbone with the aim of adsorbing Hg(II). The new functional groups are incorporated to change the pH range for Hg(II) sorption and/or to change the sorption sites in order to increase sorption selectivity. The chemical modification affords a wide range of derivatives with modified properties for specific applications. Hg(II) adsorption on chitosan or chitosan derivatives is now assumed to occur through several single or mixed interactions: chelation or coordination on amino groups in a pendant fashion or in combination with vicinal hydroxyl groups, electrostatic attraction in acidic media or ion exchange with protonated amino groups. This review reports the recent developments in the Hg(II) removal in waste water treatment, using chitosan and its derivatives in order to provide useful information about the different technologies. When possibly the adsorption capacity of chitosan and chitosan derivatives under different experimental conditions is reported to help to compare the efficacy of the Hg(II) removal process. A comparison with the adsorption capacity of other low-cost adsorbents is also tabled.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2007-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

    It has been recently demonstrated, that a strained grown layer of of HgTe is a 3D topological insulator (TI) exhibiting a single family of Dirac cone states at its surface. Since the bulk has nearly no carriers left, the transport through these structures is strongly dominated by the surface states. Because of the prediction of creation of Majorana bound states we are looking at a superconductor-TI interface. This talk presents our results on highly transparent S-TI-S junctions where we observe unusual behaviour in the Josephson current. Preliminary results of this project are published.

  8. Surface-water surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Saldi, K.A.; Dirkes, R.L.; Blanton, M.L.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the Surface water on and near the Hanford Site is monitored to determine the potential effects of Hanford operations. Surface water at Hanford includes the Columbia River, riverbank springs, ponds located on the Hanford Site, and offsite water systems directly east and across the Columbia River from the Hanford Site, and offsite water systems directly east and across the Columbia River from the Hanford Site. Columbia River sediments are also included in this discussion. Tables 5.3.1 and 5.3.2 summarize the sampling locations, sample types, sampling frequencies, and sample analyses included in surface-water surveillance activities during 1994. Sample locations are also identified in Figure 5.3.1. This section describes the surveillance effort and summarizes the results for these aquatic environments. Detailed analytical results are reported by Bisping (1995).

  9. Blue-to-red colorimetric sensing strategy for Hg²⁺ and Ag⁺ via redox-regulated surface chemistry of gold nanoparticles.

    Science.gov (United States)

    Lou, Tingting; Chen, Zhaopeng; Wang, Yunqing; Chen, Lingxin

    2011-05-01

    Here we report a "blue-to-red" colorimetric method for determination of mercury ions (Hg²⁺) and silver ions (Ag⁺) based on stabilization of gold nanoparticles (AuNPs) by redox formed metal coating in the presence of ascorbic acid (AA). AuNPs were first stabilized by Tween 20 in phosphate buffer solution with high ionic strength. In a target ion-free system, the addition of N-acetyl-L-cysteine resulted in the aggregation of Tween 20 stabilized AuNPs for mercapto ligand self-assembled on the surface of AuNPs, which induced the AuNPs to be unstable. This would lead to a color change from red to blue. By contrast, in an aqueous solution with Hg²⁺ or Ag⁺, the ions could be reduced with the aid of AA to form Hg-Au alloy or Ag coating on the surface of AuNPs. This metal coating blocked mercapto ligand assembly and AuNPs kept monodispersed after addition of N-acetyl-L-cysteine, exhibiting a red color. Therefore, taking advantage of this mechanism, a "blue-to-red" colorimetric sensing strategy could be established for Hg²⁺ and Ag⁺ detection. Compare with the commonly reported aggregation-based method ('red-to-blue'), the color change from blue to red seems more eye-sensitive, especial in low concentration of target. Moreover, selective analysis of Hg²⁺ and Ag⁺ was simply achieved by the redox nature of target ions and the application of classic ion masking agents, avoiding the design and selection of ion chelating moieties and complicated gold surface modification procedure. This method could selectively detect Hg²⁺ and Ag⁺ as low as 5 nM and 10 nM in pure water with a linear range of 5 × 10⁻⁷ to 1 × 10⁻⁵ M for Hg²⁺ and 1 × 10⁻⁶ to 8 × 10⁻⁶ M for Ag⁺, respectively. It was successfully applied to determination of Hg²⁺ and Ag⁺ in tap water and drinking water.

  10. Surface Water in Hawaii

    Science.gov (United States)

    Oki, Delwyn S.

    2003-01-01

    Surface water in Hawaii is a valued resource as well as a potential threat to human lives and property. The surface-water resources of Hawaii are of significant economic, ecologic, cultural, and aesthetic importance. Streams supply more than 50 percent of the irrigation water in Hawaii, and although streams supply only a few percent of the drinking water statewide, surface water is the main source of drinking water in some places. Streams also are a source of hydroelectric power, provide important riparian and instream habitats for many unique native species, support traditional and customary Hawaiian gathering rights and the practice of taro cultivation, and possess valued aesthetic qualities. Streams affect the physical, chemical, and aesthetic quality of receiving waters, such as estuaries, bays, and nearshore waters, which are critical to the tourism-based economy of the islands. Streams in Hawaii pose a danger because of their flashy nature; a stream's stage, or water level, can rise several feet in less than an hour during periods of intense rainfall. Streams in Hawaii are flashy because rainfall is intense, drainage basins are small, basins and streams are steep, and channel storage is limited. Streamflow generated during periods of heavy rainfall has led to loss of property and human lives in Hawaii. Most Hawaiian streams originate in the mountainous interiors of the islands and terminate at the coast. Streams are significant sculptors of the Hawaiian landscape because of the erosive power of the water they convey. In geologically young areas, such as much of the southern part of the island of Hawaii, well-defined stream channels have not developed because the permeability of the surface rocks generally is so high that rainfall infiltrates before flowing for significant distances on the surface. In geologically older areas that have received significant rainfall, streams and mass wasting have carved out large valleys.

  11. Synthesis of Novel Amphiphilic Poly (ester-amine) Dendrimers and Their Recognition of Hg2+ at the Air/Water Interface

    Institute of Scientific and Technical Information of China (English)

    申亮; 李富友; 沙耀武; 潘峥峥; 洪啸吟; 黄春辉

    2003-01-01

    Two novel amphiphilic poly(ester-amine)dendrimers were synthesized and characterized by 1H NMR,13C NMR and IR spectra.Their properties of Langmuir film were investigated at the air/water interface.The relationship between the surface pressure and area isotherms of the dendrimers was found to be dependent on the nature of subphases,Interaction between HgCl2 and the dendrimers was observed,indicating that the amphiphilic dendrimers could act as a sensor for Hg2+.

  12. 46 CFR 53.05-2 - Relief valve requirements for hot water boilers (modifies HG-400.2).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Relief valve requirements for hot water boilers... requirements for hot water boilers (modifies HG-400.2). (a) The relief valve requirements for hot water boilers... (incorporated by reference; see 46 CFR 53.01-1) except as noted otherwise in this section. (b) Hot water...

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

    Science.gov (United States)

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

    2016-08-01

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

  14. A bright water-compatible sugar-rhodamine fluorescence sensor for selective detection of Hg2+ in natural water and living cells.

    Science.gov (United States)

    Huang, Wei; Zhou, Peng; Yan, Wenbo; He, Cheng; Xiong, Liqin; Li, Fuyou; Duan, Chunying

    2009-02-01

    By combination of a sugar group and a rhodamine group into one molecule, a bright and specific fluorescent sensor for Hg(2+) in natural water and living cells was achieved. RG1 features the high quantum efficiency for a Hg(2+)-bound sensor in natural water and sensitivity to environmentally relevant mercury in complex natural samples. The limit of detection of Hg(2+) of 1 ppb level suggests that RG1 is capable of distinguishing between the safe and toxic levels of inorganic mercury in drinking water. RG1 also establishes excellent Hg(2+)-ion specificity over alkali-, alkaline-earth metals and the first-row transition metals as well as Pb(2+) and Ag(+). Investigation on the fluorescence imaging of Hg(2+) in living cells demonstrates that RG1 might be used for monitoring Hg(2+) within biological samples.

  15. Development of emergency water quality standard for Cr6+and Hg2+in Liao River basin

    Institute of Scientific and Technical Information of China (English)

    Yan Zhenguang; Zheng Xin; Ye Jing; Wang Xiaonan; Wu Jiangyue; Liu Zhengtao; Meng Wei

    2014-01-01

    The acute toxicity data of Cr6+and Hg2+to the aquatic organisms in Liao River basin was collected and screened. Calculated results of criteria values using popular species sensitivity distribution (SSD) methods were evaluated through data analysis. The comprehensive methodology of emergency water quality standards (EWQSs) was established on the basis of the SSD method of Australia and New Zealand according to the evalu-ation results. The affected fractions of the aquatic organisms were set to be 5%,15%,30%and 50%,corre-sponding to the risk grades ofⅠ,Ⅱ,ⅢandⅣ,and four-grade EWQSs,respectively. The EWQSs for Cr6+and Hg2+in the Liao River were derived and the corresponding risk indicators were also proposed. The results showed that the four-grade EWQSs for Cr6+ were 2.85 μg/L ,21.0 μg/L ,161 μg/L and 797 μg/L,respec-tively,and the risk indicators were daphnia (grade Ⅱ),shrimp (grade Ⅲ),and the bighead fish or tadpole (gradeⅣ). The four-grade EWQSs for Hg2+were 0.59μg/L,2.32μg/L,6.25μg/L and 15.6μg/L,respective-ly,and the risk indicators were crucian carp or daphnia (grade Ⅱ),shrimp (grade Ⅲ),and worm or crab (gradeⅣ). The results provided valuable information for the risk analysis of sudden ambient water environmen-tal pollution accident.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-15

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

  17. A density functional theory study of the adsorption of Hg and HgCl2 on a CaO(001) surface

    Institute of Scientific and Technical Information of China (English)

    GUO Xin; ZHENG Chuguang; LU Nanxia

    2007-01-01

    The adsorption of mercury and mercury chloride on a CaO(001) surface was investigated by the density functional theory (DFT) by using Ca9O9 cluster embedded in an electrostatic field represented by 178 point charges at the crystal CaO lattice positions.For the mercury molecular axis normal to the surface,the mercury can only coordinate to the O2- anion and has a very weak binding energy of 19.649 kJ/mol.When the mercury chloride molecular axis is vertical to the surface,the Cl atom coordinates to the Ca2+ cation and has a binding energy of 23.699 kJ/mol.When the mercury chloride molecular axis is parallel to the surface,the Hg atom coordinates to the O2- anion and has a binding energy of 87.829 kJ/mol,which means that the parallel geometry is more stable than the vertical one.The present calculations show that CaO injection could substantially reduce gaseous mercury chloride,but have no apparent effect on the mercury,which is compatible with the available experimental results.This research will provide valuable information for optimizing and selecting a sorbent for the trace element in flue gas.

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

    Science.gov (United States)

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

    2012-04-01

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

  19. Water on graphene surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gordillo, M C [Departamento de Sistemas Fisicos, Quimicos y Naturales, Facultad de Ciencias Experimentales, Universidad Pablo de Olavide, Carretera de Utrera, km 1, E-41013 Sevilla (Spain); Marti, J, E-mail: cgorbar@upo.e, E-mail: jordi.marti@upc.ed [Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, B4-B5 Campus Nord, E-08034 Barcelona, Catalonia (Spain)

    2010-07-21

    In this paper, we summarize the main results obtained in our group about the behavior of water confined inside or close to different graphene surfaces by means of molecular dynamics simulations. These include the inside and outside of carbon nanotubes, and the confinement inside a slit pore or a single graphene sheet. We paid special attention to some thermodynamical (binding energies), structural (hydrogen-bond distributions) and dynamic (infrared spectra) properties, and their comparison to their bulk counterparts.

  20. Results of Hg speciation testing on tanks 30, 32, and 37 surface samples

    Energy Technology Data Exchange (ETDEWEB)

    Bannochie, C. J. [Savannah River Site (SRS), Aiken, SC (United States)

    2015-11-11

    The Savannah River National Laboratory (SRNL) was tasked with preparing and shipping samples for Hg speciation by Eurofins Frontier Global Sciences, Inc. in Seattle, WA on behalf of the Savannah River Remediation (SRR) Mercury Task Team.

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

    Science.gov (United States)

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

    2016-04-05

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

  2. A novel fluorescence "on-off-on" chemosensor for Hg(2+)via a water-assistant blocking heavy atom effect.

    Science.gov (United States)

    Wu, Chong; Zhao, Jiang-Lin; Jiang, Xue-Kai; Wang, Chuan-Zeng; Ni, Xin-Long; Zeng, Xi; Redshaw, Carl; Yamato, Takehiko

    2016-10-14

    Upper rim pyrene-functionalized hexahomotrioxacalix[3]arene L was synthesized via Click chemistry, and its fluorescence behaviors toward several common metal cations were investigated. L exhibited a significant fluorescence quenching response to Hg(2+) in CH3CN solution, which was unaffected by the coexistence of other competitive metal cations. Thus, L can be utilized as a highly selective and sensitive fluorescent chemosensor for Hg(2+) with a detection limit in the nM level. Interestingly, the quenched fluorescence emission can be successfully revived upon the addition of water. In this process, the heavy atom effect of Hg(2+) can be blocked by further coordination of a water molecule and resulted in the revival of the fluorescence emission of L/Hg(2+) complex. Particularly, other polar solvents such as CH3OH and CH3CH2OH also have the ability to revive the fluorescence emission of the L/Hg(2+) complex, but on a much smaller scale than observed for H2O. The heavy atom effect and blocking thereof were demonstrated within the same system by the use of a C3-symmetric homooxacalix[3]arene scaffold. The present studies provided further evidence for the blocking heavy atom effect.

  3. No detection of large-scale magnetic fields at the surfaces of Am and HgMn stars

    CERN Document Server

    Auriere, M; Lignieres, F; Hui-Bon-Hoa, A; Landstreet, J D; Iliev, I; Donati, J -F; Petit, P; Roudier, T; Theado, S

    2010-01-01

    We investigate the magnetic dichotomy between Ap/Bp and other A-type stars by carrying out a deep spectropolarimetric study of Am and HgMn stars. Using the NARVAL spectropolarimeter at the Telescope Bernard Lyot (Observatoire du Pic du Midi, France), we obtained high-resolution circular polarisation spectroscopy of 12 Am stars and 3 HgMn stars. Using Least Squares Deconvolution (LSD), no magnetic field is detected in any of the 15 observed stars. Uncertaintiies as low as 0.3 G (respectively 1 G) have been reached for surface-averaged longitudinal magnetic field measurements for Am (respectively HgMn) stars. Associated with the results obtained previously for Ap/Bp stars, our study confirms the existence of a magnetic dichotomy among A-type stars. Our data demonstrate that there is at least one order of magnitude difference in field strength between Zeeman detected stars (Ap/Bp stars) and non Zeeman detected stars (Am and HgMn stars). This result confirms that the spectroscopically-defined Ap/Bp stars are the ...

  4. Water Soluble Cationic Porphyrin Sensor for Detection of Hg2+, Pb2+, Cd2+, and Cu2+

    Directory of Open Access Journals (Sweden)

    Matibur Zamadar

    2016-01-01

    Full Text Available Here we report the sensing properties of the aqueous solution of meso-tetra(N-methyl-4-pyridylporphine tetrachloride (1 for simultaneous detection of toxic metal ions by using UV-vis spectroscopy. Cationic porphyrin 1 displayed different electronic absorptions in UV-vis region upon interacting with Hg2+, Pb2+, Cd2+, and Cu2+ ions in neutral water solution at room temperature. Quite interestingly, the porphyrin 1 showed that it can function as a single optical chemical sensor and/or metal ion receptor capable of detecting two or more toxic metal ions, particularly Hg2+, Pb2+, and Cd2+ ions coexisting in a water sample. Porphyrin 1 in an aqueous solution provides a unique UV-vis sensing system for the determination of Cd2+ in the presence of larger metal ions such as Hg2+, or Pb2+. Finally, the examination of the sensing properties of 1 demonstrated that it can operate as a Cu2+ ion selective sensor via metal displacement from the 1-Hg2+, 1-Pb2+, and 1-Cd2+.

  5. Sustaining dry surfaces under water

    DEFF Research Database (Denmark)

    Jones, Paul R.; Hao, Xiuqing; Cruz-Chu, Eduardo R.

    2015-01-01

    Rough surfaces immersed under water remain practically dry if the liquid-solid contact is on roughness peaks, while the roughness valleys are filled with gas. Mechanisms that prevent water from invading the valleys are well studied. However, to remain practically dry under water, additional...... mechanisms need consideration. This is because trapped gas (e.g. air) in the roughness valleys can dissolve into the water pool, leading to invasion. Additionally, water vapor can also occupy the roughness valleys of immersed surfaces. If water vapor condenses, that too leads to invasion. These effects have...... not been investigated, and are critically important to maintain surfaces dry under water.In this work, we identify the critical roughness scale, below which it is possible to sustain the vapor phase of water and/or trapped gases in roughness valleys – thus keeping the immersed surface dry. Theoretical...

  6. Sustaining dry surfaces under water

    Science.gov (United States)

    Jones, Paul R.; Hao, Xiuqing; Cruz-Chu, Eduardo R.; Rykaczewski, Konrad; Nandy, Krishanu; Schutzius, Thomas M.; Varanasi, Kripa K.; Megaridis, Constantine M.; Walther, Jens H.; Koumoutsakos, Petros; Espinosa, Horacio D.; Patankar, Neelesh A.

    2015-08-01

    Rough surfaces immersed under water remain practically dry if the liquid-solid contact is on roughness peaks, while the roughness valleys are filled with gas. Mechanisms that prevent water from invading the valleys are well studied. However, to remain practically dry under water, additional mechanisms need consideration. This is because trapped gas (e.g. air) in the roughness valleys can dissolve into the water pool, leading to invasion. Additionally, water vapor can also occupy the roughness valleys of immersed surfaces. If water vapor condenses, that too leads to invasion. These effects have not been investigated, and are critically important to maintain surfaces dry under water. In this work, we identify the critical roughness scale, below which it is possible to sustain the vapor phase of water and/or trapped gases in roughness valleys - thus keeping the immersed surface dry. Theoretical predictions are consistent with molecular dynamics simulations and experiments.

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

    CERN Document Server

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

    2010-01-01

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

  8. Isatin functionalized nanoporous SBA-15 as a selective fluorescent probe for the detection of Hg(II) in water.

    Science.gov (United States)

    Lashgari, Negar; Badiei, Alireza; Mohammadi Ziarani, Ghodsi; Faridbod, Farnoush

    2017-03-07

    A highly ordered mesoporous silica material functionalized with isatin (SBA-Pr-IS) was designed and synthesized. Characterization techniques including XRD, TGA, BET, SEM, and FT-IR were employed to characterize the pore structure, textural properties, microscopic morphology, and molecular composition of grafted organic moieties of SBA-Pr-IS. The successful attachment of the organic moiety (0.34 mmol g(-1)) without the SBA-15 structure collapsing after the modification steps was confirmed. Fluorescence characterization of SBA-Pr-IS was examined upon addition of a wide variety of cations in aqueous medium and it showed high sensitivity toward Hg(2+) ions. During testing in an ion competition experiment, it was observed that the fluorescence changes of the probe were remarkably specific for Hg(2+) ions. Furthermore, a good linearity between the fluorescence intensity of this material and the concentration of Hg(2+) ions was constructed with a suitable detection limit of 3.7 × 10(-6) M. Finally, the applicability of the proposed method was successfully evaluated for the determination of Hg(2+) ions in real samples. Therefore, SBA-Pr-IS can be used as an efficient fluorescence probe for Hg(2+) ions. Graphical Abstract A novel organic-inorganic hybrid material was designed and synthesized by functionalization of SBA-15 mesoporous silica material with isatin. The evaluation of the sensing ability of SBA-Pr-IS using fluorescence spectroscopy revealed that the SBA-Pr-IS was a selective fluorescent probe for Hg(2+) ion in water in the presence of a wide range of metal cations.

  9. Artificial Ground Water Recharge with Surface Water

    Science.gov (United States)

    Heviánková, Silvie; Marschalko, Marian; Chromíková, Jitka; Kyncl, Miroslav; Korabík, Michal

    2016-10-01

    With regard to the adverse manifestations of the recent climatic conditions, Europe as well as the world have been facing the problem of dry periods that reduce the possibility of drawing drinking water from the underground sources. The paper aims to describe artificial ground water recharge (infiltration) that may be used to restock underground sources with surface water from natural streams. Among many conditions, it aims to specify the boundary and operational conditions of the individual aspects of the artificial ground water recharge technology. The principle of artificial infiltration lies in the design of a technical system, by means of which it is possible to conduct surplus water from one place (in this case a natural stream) into another place (an infiltration basin in this case). This way, the water begins to infiltrate into the underground resources of drinking water, while the mixed water composition corresponds to the water parameters required for drinking water.

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

    Institute of Scientific and Technical Information of China (English)

    毕东苏; 钱春龙

    2007-01-01

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

  11. A core-shell structured nanocomposite material for detection, adsorption and removal of Hg(II) ions in water.

    Science.gov (United States)

    Li, Le; Tang, Shuangyang; Ding, Dexin; Hu, Nan; Yang, Shengyuan; He, Shuya; Wang, Yongdong; Tan, Yan; Sun, Jing

    2012-11-01

    In this paper, a core-shell structured nanocomposite material was prepared for the detection, adsorption and removal of Hg(ll) ions in aqueous solution. The core was made from Fe3O4 nanoparticles with superparamagnetic behavior and the outer shell was made from amorphous silica modified with pyrene-based sensing-probes. The material could detect and adsorb Hg(II) ions in aqueous solution due to its surface being modified with pyrene-based sensing-probes, and could easily be removed from the solution by magnetic force because of its core being made from magnetic Fe3O4 nanoparticles. This multifunctional core-shell structure was confirmed and characterized by TEM, IR spectra, TGA, XRD and N2 adsorption/desorption isotherms. Experiments were conducted on its functions of detection, adsorption and removal of Hg(II) ions in aqueous solution. The experimental results showed that this composite material had high sensitivity and unique selectivity to Hg(II), and that it could easily be removed from the solution.

  12. A first-principles study of Hg adsorption on Pd(1 1 1) and Pd/γ-Al2O3(1 1 0) surfaces

    Science.gov (United States)

    Geng, Lu; Han, Lina; Cen, Wanglai; Wang, Jiancheng; Chang, Liping; Kong, Dejin; Feng, Gang

    2014-12-01

    Spin-polarized density functional theory calculations were carried out to investigate the adsorption of Hgn (n = 1-3) on the perfect, step and vacancy-defective Pd(1 1 1) surfaces as well as the Pd/γ-Al2O3(1 1 0) surface. It is found that Hg atoms prefer to adsorb on the hollow sites on Pd(1 1 1) surfaces. The adsorption of Hg on the step and vacancy-defective Pd(1 1 1) surfaces is stronger than on the perfect Pd(1 1 1) surface, which indicates that the existence of vacancy and step defects can enhance the mercury adsorption activity of Pd adsorbents. As indicated by the calculated adsorption energies, the mercury adsorption on γ-Al2O3 is weak. The γ-Al2O3 supported single Pd atom shows as good Hg adsorption activity as the perfect Pd(1 1 1) surface at low Hg coverage, while more coordination unsaturated active Pd atoms is needed to achieve high Hg adsorption capacity. In addition, it was also found that the Hg adsorption on Pd/γ-Al2O3 weakens the binding of Pd to the γ-Al2O3 surface.

  13. Influence of cations on the blue to purple transition of bacteriorhodopsin. Comparison of Ca2+ and Hg2+ binding and their effect on the surface potential.

    Science.gov (United States)

    Duñach, M; Seigneuret, M; Rigaud, J L; Padrós, E

    1988-11-25

    We have investigated the effect of Ca2+ and Hg2+ binding on various properties of the blue membrane prepared by deionization of the Halobacterium halobium purple membrane. Binding of radioactive 45Ca2+ and 203Hg2+ was monitored by a filtration technique. Five high and medium affinity sites for Ca2+ and seven low affinity sites for Hg2+ were found per bacteriorhodopsin. Competitive binding was observed only for three Ca2+ and three Hg2+. Visible absorption studies indicated that Ca2+ binding could restore the purple color of bacteriorhodopsin while Hg2+ was inefficient. Hg2- could partially reverse to blue the Ca2+-regenerated purple membrane in parallel with the displacement of three Ca2+. Effects of cation binding on the surface potential of the membrane were measured by Electron Spin Resonance spectroscopy using a cationic spin-labeled amphiphile. Cations such as La3+, Ca2+, Mg2+, or Na+ strongly increased (i.e. rendered less negative) the surface potential. An univocal correlation was found between the cation-induced variation of surface potential and the extent of regeneration of the purple color. Hg2+ induced a smaller increase in surface potential than that corresponding to the effective divalent cations. This lower effect appears to be due to binding to sites not related to those of other cations.

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

    Science.gov (United States)

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

    2015-05-01

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

  15. Thiol-functionalised mesoporous silica-coated magnetite nanoparticles for high efficiency removal and recovery of Hg from water.

    Science.gov (United States)

    Hakami, Othman; Zhang, Yue; Banks, Charles J

    2012-08-01

    The preparation and testing of thiol-functionalised silica-coated magnetite nanoparticles (TF-SCMNPs) is described. The characteristics of these particles are assessed at different stages in the production process using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and a magnetometer. The particles were found to be almost spherical with a uniform mesoporous structure with a pore size of ∼2.1nm. The particles were strongly responsive to an external magnetic field making separation from solution possible in less than 1min. The adsorption characteristics of the particles were quantified in a series of isotherm experiments using Hg(II) solution concentrations between 40 and 1000μg l(-1) at adsorbent concentrations of 4 and 8mg l(-1). The adsorption capacity was higher than for other commonly used adsorbents with 90% of Hg(II) removed during the first 5min and equilibrium in less than 15min. Both the Langmuir and Freundlich isotherm models were applied to the isotherm data and the maximum adsorption capacity was achieved when the ratio of adsorbent to adsorbate was low. Both temperature and pH had an effect on adsorption but when the TF-SCMNPs were used for removal of Hg(II) from tap water and bottled water, which contained other ions, there appeared to be no interference. Hg(II) could be successfully desorbed using thiourea in a 3M HCl solution; this did not result in the destruction of the nanoparticles and they could subsequently be reused without loss of their activity in repetitive adsorption tests.

  16. Total Phosphorus in Surface Water

    Data.gov (United States)

    U.S. Environmental Protection Agency — Excess phosphorus in surface water can result in eutrophication. TOTALP is reported in kilograms/hectare/year. More information about these resources, including the...

  17. Total Nitrogen in Surface Water

    Data.gov (United States)

    U.S. Environmental Protection Agency — Excess nitrogen in surface water can result in eutrophication. TOTALN is reported in kilograms/hectare/year. More information about these resources, including the...

  18. Free Surface Water Tunnel (FSWT)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The Free Surface Water Tunnel consists of the intake plenum, the test section and the exit plenum. The intake plenum starts with a perforated pipe that...

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

    Science.gov (United States)

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

    2016-04-01

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

  20. Surface quality studies of high T$_{c}$ superconductors of the Hg , Tl and Hg$_{x}$Tl$_{1-x}$-families RBS and resonant C and O backscattering studies

    CERN Document Server

    Vantomme, A; Correia, J G; Bryntse, I; Johansson, L G; Loureiro, S M; Le Floc'h, S; Toulemonde, T; Bordet, P; Bougerol-Chaillout, C

    2002-01-01

    The composition, crystallinity, uniformity, purity, and thermal stability of cuprate superconductors have been studied by Rutherford backscattering and channeling spectrometry, and 3.045 MeV He$^{+}$ oxygen non-Rutherford resonant scattering. Further experiments have been performed with 1.75 MeV H$^{+}$carbon non-Rutherford resonant scattering. Three sets of samples were studied : HgBa$_{2}$CuO$_{(4+\\delta)}$ (Hg1201), Hg$_{x}$T1$_{1-x}$Ba$_{2}$Ca$_{2}$Cu$_{3}$O$_{(2n+\\delta)}$ (Hg,T1-1223) and T1$_{1.85}$Ba$_{2}$CuO$_{6}$/LaA10$_{3}$ (T1-2201), either in bulk or as an epitaxial thin film. It was observed that the superconductors exhibit a metal deficiency near the surface, which is largely compensated by excess oxygen. Moreover, the samples are significantly contaminated with carbon within the probing region of the H$^+$ beam. The thermal stability and surface degradation were studied in both oxidizing ambient and vacuum. As a general trend, the heavy metal deficiency — and consequently the compensating o...

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

    Energy Technology Data Exchange (ETDEWEB)

    He, Kai; Wang, Xi; Zhang, Peng; Chen, Yi-Yu [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhou, Song-Min; Xie, Xiao-Hui; Lin, Chun, E-mail: chun-lin@mail.sitp.ac.cn; Ye, Zhen-Hua; Wang, Jian-Xin; Zhang, Qin-Yao, E-mail: qinyao@mail.sitp.ac.cn [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Yang [Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-05-28

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

  2. Diminished Mercury Emission From Water Surfaces by Duckweed (Lemna minor)

    Science.gov (United States)

    Wollenberg, J. L.; Peters, S. C.

    2007-12-01

    Aquatic plants of the family Lemnaceae (generally referred to as duckweeds) are a widely distributed type of floating vegetation in freshwater systems. Under suitable conditions, duckweeds form a dense vegetative mat on the water surface, which reduces light penetration into the water column and decreases the amount of exposed water surface. These two factors would be expected to reduce mercury emission by limiting a) direct photoreduction of Hg(II), b) indirect reduction via coupled DOC photooxidation-Hg(II) reduction, and c) gas diffusion across the water-air interface. Conversely, previous studies have demonstrated transpiration of Hg(0) by plants, so it is therefore possible that the floating vegetative mat would enhance emission via transpiration of mercury vapor. The purpose of this experiment was to determine whether duckweed limits mercury flux to the atmosphere by shading and the formation of a physical barrier to diffusion, or whether it enhances emission from aquatic systems via transpiration of Hg(0). Deionized water was amended with mercury to achieve a final concentration of approximately 35 ng/L and allowed to equilibrate prior to the experiment. Experiments were conducted in rectangular polystyrene flux chambers with measured UV-B transmittance greater than 60% (spectral cutoff approximately 290 nm). Light was able to penetrate the flux chamber from the sides as well as the top throughout the experiment, limiting the effect of shading by duckweed on the water surface. Flux chambers contained 8L of water with varying percent duckweed cover, and perforated plastic sheeting was used as an abiotic control. Exposures were conducted outside on days with little to no cloud cover. Real time mercury flux was measured using atomic absorption (Mercury Instruments UT-3000). Total solar and ultraviolet radiation, as well as a suite of meteorological parameters, were also measured. Results indicate that duckweed diminishes mercury emission from the water surface

  3. Modifying Fe3O4 microspheres with rhodamine hydrazide for selective detection and removal of Hg2+ ion in water.

    Science.gov (United States)

    Wang, Zhuqing; Wu, Dayu; Wu, Genhua; Yang, Ningning; Wu, Aiguo

    2013-01-15

    Rhodamine hydrazide modifying Fe(3)O(4) microspheres (Fe(3)O(4)-R6G) was developed for selective detection and removal of mercury ion from water. With a saturation magnetization of 74.2 emu/g, the Fe(3)O(4)-R6G could be simply recollected from water with magnetic separation within a few minutes. The selectivity and adsorption ability of Fe(3)O(4)-R6G for metal cations were studied by fluorophotometry and atomic absorption spectrometry, respectively. The results showed that Fe(3)O(4)-R6G exhibited excellent selectivity for sensing mercury ion over other metal ions in aqueous solution, and also adsorbed 91% of mercury ion. The maximum adsorption capacity of the Fe(3)O(4)-R6G for Hg(2+) ion was 37.4 μmol g(-1). The Fe(3)O(4)-R6G was successfully applied to the determination of Hg(2+) in environmental samples, and could be used repeatedly by treatment with tetrabutylammonium hydroxide. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Groundwater–Surface Water Exchange

    DEFF Research Database (Denmark)

    Karan, Sachin

    The exchange of groundwater-surface water has been invetigated in the western part of Denmark. Holtum AA provides the framework for all the performed investigations. Several methods are used, primarily eld based measurements ombined with numerical models to achieve insight to the governing...... processes of interaction between groundwater and surface water. By using heat as a tracer it has been possible to use temperature directly as calibrationtargets in a groundwater and heat transport model. Thus, it is possible to use heat investigate the change in groundwater discharge in dynamic conditions...... by using simple temperature devices along a stream to delineate the areas of interest in regard to GW{SW exchange. Thus, at several locations in a stream a temperature data logger was placed in the water column and right at the streambed-water interface. By looking at the correlation of streambed...

  5. Groundwater–Surface Water Exchange

    DEFF Research Database (Denmark)

    Karan, Sachin

    The exchange of groundwater-surface water has been invetigated in the western part of Denmark. Holtum AA provides the framework for all the performed investigations. Several methods are used, primarily eld based measurements ombined with numerical models to achieve insight to the governing...... processes of interaction between groundwater and surface water. By using heat as a tracer it has been possible to use temperature directly as calibrationtargets in a groundwater and heat transport model. Thus, it is possible to use heat investigate the change in groundwater discharge in dynamic conditions...... by using simple temperature devices along a stream to delineate the areas of interest in regard to GW{SW exchange. Thus, at several locations in a stream a temperature data logger was placed in the water column and right at the streambed-water interface. By looking at the correlation of streambed...

  6. Determination of arsenic speciation in sulfidic waters by Ion Chromatography Hydride-Generation Atomic Fluorescence Spectrometry (IC-HG-AFS).

    Science.gov (United States)

    Keller, Nicole S; Stefánsson, Andri; Sigfússon, Bergur

    2014-10-01

    A method for the analysis of arsenic species in aqueous sulfide samples is presented. The method uses an ion chromatography system connected with a Hydride-Generation Atomic Fluorescence Spectrometer (IC-HG-AFS). With this method inorganic As(III) and As(V) species in water samples can be analyzed, including arsenite (HnAs(III)O3(n-3)), thioarsenite (HnAs(III)S3(n-3)), arsenate (HnAs(V)O4(n-3)), monothioarsenate (HnAs(V)SO3(n-3)), dithioarsenate (HnAs(V)S2O2(n-3)), trithioarsenate (HnAs(V)S3O(n-3)) and tetrathioarsenate (HnAs(V)S4(n-3)). The peak identification and retention times were determined based on standard analysis of the various arsenic compounds. The analytical detection limit was ~1-3 µg L(-1) (LOD), depending on the quality of the baseline. This low detection limit makes this method also applicable to discriminate between waters meeting the drinking water standard of max. 10 µg L(-1) As, and waters that do not meet this standard. The new method was successfully applied for on-site determination of arsenic species in natural sulfidic waters, in which seven species were unambiguously identified.

  7. Mobile surface water filtration system

    Directory of Open Access Journals (Sweden)

    Aashish Vatsyayan

    2012-09-01

    Full Text Available To design a mobile system for surface water filtrationMethodology: the filtration of surface impurities begins with their retraction to concentrated thickness using non ionising surfactants, then isolation using surface tension property and sedimentation of impurities in process chamber using electrocoagulation. Result:following studies done to determine the rate of spreading of crude oil on water a method for retraction of spread crude oil to concentrated volumes is developed involving addition of non -ionising surfactants in contrast to use of dispersants. Electrocoagulation process involves multiple processes taking place to lead to depositionof impurities such as oil, grease, metals. Studies of experiments conducted reveals parameters necessary for design of electrocoagulation process chamber though a holistic approach towards system designing is still required. Propeller theory is used in determining the required design of propeller and the desired thrust, the overall structure will finally contribute in deciding the choice of propeller.

  8. Novel thymine-functionalized MIL-101 prepared by post-synthesis and enhanced removal of Hg{sup 2+} from water

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xubiao, E-mail: luoxubiao@126.com [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Shen, Tingting; Ding, Lin; Zhong, Weiping; Luo, Jianfeng [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian, E-mail: sllou@hnu.edu.cn [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2016-04-05

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

  9. ARSENIC SPECIATION ANALYSIS IN GROUND WATER BY IC-HG-AFS

    Science.gov (United States)

    The determination of low levels of arsenic draws concern more than ever today, because of the possible legislative changes in the drinking water limit. The toxicity of arsenic depends upon its chemical form. Arsenite is the most toxic form, 25 to 50 times more toxic than arsena...

  10. Biofilms as bioindicators of mercury exposure in surface waters

    Science.gov (United States)

    Le Faucheur, S.; Dranguet, P.; Freiburghaus, A.; Slaveykova, V. I.; Carmen, M.

    2016-12-01

    Biofilms are communities of microorganisms living in shallow waters, which possess several interesting characteristics to be a good bioindicator, i.e. ubiquitous, easy to collect, integrator of the quality of their ambient environment and sensitive to pollutants. Our work investigated whether biofilm could be used as a bioindicator of Hg contamination in natural waters and explore the links between ambient Hg concentrations, its bioaccumulation and biofilm composition. To that end, field- and lab-based experiments were performed with biofilm grown on artificial substrata in either Hg-impacted waters and in microcosms spiked with Hg. The field experiments were performed in contrasted environments: the Olt River (Romania) impacted by chloro-alkali releases and the lagoon of Venice (Italy) affected by urban, industrial and agricultural activities. The field studies were complemented with microcosm experiments using Geneva Lake water enriched with Hg (13 pM to 1.4 nM). Bioaccumulated inorganic HgII and methylmercury (CH3Hg) in biofilms were measured w/o cysteine washing step to assess the total and intracellular Hg content. Biofilm composition was examined from gene to community levels using several techniques, notably qPCR, epifluorescent microscopy and pyrosequencing. In parallel the physico-chemical parameters of the ambient waters (pH, anion/cation and dissolved organic matter concentrations) were well characterized and dissolved Hg concentrations measured. Commercially available DGTs for Hg were additionally used in the lagoon of Venice. The main findings of the study can be summarized as follows: (i) accumulation of Hg in biofilms well correlates with ambient Hg concentration in a specific environment, but (ii) that bioaccumulation highly depends of biofilm composition, with bacterial-dominated biofilms having higher uptake rate constants than algal-dominated biofilms, and (iii) Hg exposure at environmental low concentrations (pM levels) strongly impacts algal

  11. [Influence of inorganic ions and humic acid on the removal of Pb(II) and Hg(II) in water by zero-valent iron].

    Science.gov (United States)

    Shi, Qiu-Ling; Zhou, Xin; Zhang, Jin-Zhong; Qiu, Xin-Kai

    2014-08-01

    The effects of Ca2+, Cl- and humic acid (HA) on the removal rates of Pb(II) and Hg(II) in water by zero-valent (ZVI) and the kinetic characteristics were studied, and the removal mechanism of Pb(II) and Hg(II) by ZVI were preliminarily investigated using X-ray diffraction (XRD). The results indicated that the removal mechanism of Pb(II) might mainly be attributed to the adsorption and co-precipitation of ZVI, while that of Hg(II) might mainly be attributed to the oxidation-reduction of ZVI. With the increase of Ca2+ concentration, the removal rates of Hg(II) and Pb(II) showed the trends of gradual increase and slight decrease, respectively. The Hg(II) removal increased with increasing Cl- concentration, whereas no obvious increase in Pb(II) removal was observed. The removal rates of Hg(II) and Pb(II) showed the trends of slow increase and slow decrease with increasing HA concentration, respectively. When Ca2+, Cl- and HA coexisted, the removal rates of Hg(II) and Pb(II) reached 99.71% and 97.95%, respectively. The removal processes of Pb(II) and Hg(II) could be described by pseudo first-order reaction kinetic equations when Ca2+, Cl- and HA existed alone and in combination. The removal rate constant of Pb(II) was the maxinum (0.024 0 min(-1)) when 5 mg x L(-1) HA existed alone, whereas that of Hg(II) was the maximum (0.0169 min(-1)) when 0.80 mmol x L(-1) Ca2+ existed alone.

  12. Localized surface plasmon resonance light-scattering detection of Hg(II) with 3-aminopropyltriethoxysilane-assisted synthesis of highly stabilized Ag nanoclusters.

    Science.gov (United States)

    Zhu, Jingjing; Mao, Qinli; Gao, Lang; He, Yu; Song, Gongwu

    2013-03-21

    We employed 3-aminopropyltriethoxysilane to assist the synthesis of Ag NCs using polyethyleneimine as the template for detecting Hg(2+) by localized surface plasmon resonance light-scattering technology. The developed selective and sensitive method presaged more opportunities for application in environmental systems.

  13. Speciation of mercury in surface and deep-sea waters in the Mediterranean Sea

    Science.gov (United States)

    Horvat, Milena; Kotnik, Jože; Logar, Martina; Fajon, Vesna; Zvonarić, Tomislav; Pirrone, Nicola

    A summary of data recently obtained for mercury analysis and speciation (reactive Hg, total Hg and monomethylmercury (MMHg)) in filtered and non-filtered seawater samples, dissolved gaseous mercury (DGM) and dimethylmercury (DMHg) in open and coastal waters of the Mediterranean Sea is presented. The majority of the results were obtained during an oceanographic cruise aboard the research vessel Urania from 14 July to 9 August, 2000, as part of the MED-OCEANOR Project funded by the National Research Council of Italy. The results are compared with those obtained in contaminated coastal environments of the Adriatic (The Gulf of Trieste and Kaštela Bay) and non-contaminated coastal waters of the eastern Adriatic coast obtained in 1998. Total mercury concentrations in surface ocean waters are relatively low with an average of 0.81 pM (0.49-1.91 pM). Reactive Hg represents a substantial part with an average of 57% of total Hg (15-97%). Most mercury in open ocean waters was present in the dissolved form (32-95%, av. 70%), which is mainly due to the low abundance of particulate matter, a phenomenon well known for the Mediterranean open ocean waters. On average the percentage of Hg as MMHg was about 20%, of which about 66% was present in the dissolved form. The percentage of DGM in the surface ocean waters represents about 9% of total Hg (2.5-24.5%) and may originate from photochemical, biologically mediated mechanisms or diffusion from deeper layer either due to biological and/or to tectonic activity which is typical of the Mediterranean region. The presence of DMHg was confirmed only in waters below 20 m (up to 12 fM), while in surface waters DMHg was below the limit of detection (<0.1 fM). Surface concentrations of Hg in the eastern and western parts are comparable, except for DGM which shows significantly higher concentrations in the eastern part (mean value: 0.22 pM) as compared to the western Mediterranean (mean value: 0.09 pM). The distribution of Hg species with

  14. Assessment of mercury erosion by surface water in Wanshan mercury mining area.

    Science.gov (United States)

    Dai, ZhiHui; Feng, Xinbin; Zhang, Chao; Shang, Lihai; Qiu, Guangle

    2013-08-01

    Soil erosion is a main cause of land degradation, and in its accelerated form is also one of the most serious ecological environmental problems. Moreover, there are few studies on migration of mercury (Hg) induced by soil erosion in seriously Hg-polluted districts. This paper selected Wanshan Hg mining area, SW China as the study area. Revised universal soil loss equation (RUSLE) and Geographic information system (GIS) methods were applied to calculate soil and Hg erosion and to classify soil erosion intensity. Our results show that the soil erosion rate can reach up to 600,884tkm(-2)yr(-1). Surfaces associated with very slight and extremely severe erosion include 76.6% of the entire land in Wanshan. Furthermore, the cumulative erosion rates in the area impacted by extremely severe erosion make up 90.5% of the total. On an annual basis, Hg surface erosion load was predicted to be 505kgyr(-1) and the corresponding mean migration flux of Hg was estimated to be 3.02kgkm(-2)yr(-1). The erosion loads of Hg resulting from farmland and meadow soil were 175 and 319kgyr(-1) respectively, which were enhanced compared to other landscape types due to the fact that they are generally located in the steep zones associated with significant reclamation. Contributing to establish a mass balance of Hg in Wanshan Hg mining area, this study supplies a dependable scientific basis for controlling soil and water erosion in the local ecosystems. Land use change is the most effective way for reducing Hg erosion load in Wanshan mining area. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Determination of Hg(II) in waters by on-line preconcentration using Cyanex 923 as a sorbent — Cold vapor atomic absorption spectrometry

    Science.gov (United States)

    Duan, Taicheng; Song, Xuejie; Xu, Jingwei; Guo, Pengran; Chen, Hangting; Li, Hongfei

    2006-09-01

    Using a solid phase extraction mini-column home-made from a neutral extractant Cyanex 923, inorganic Hg could be on-line preconcentrated and simultaneously separated from methyl mercury. The preconcentrated Hg (II) was then eluted with 10% HNO 3 and subsequently reduced by NaBH 4 to form Hg vapor before determination by cold vapor atomic absorption spectrometry (CVAAS). Optimal conditions for and interferences on the Hg preconcentration and measurement were at 1% HCl, for a 25 mL sample uptake volume and a 10 mL min - 1 sample loading rate. The detection limit was 0.2 ng L - 1 and much lower than that of conventional method (around 15.8 ng L - 1 ). The relative standard deviation (RSD) is 1.8% for measurements of 40 ng L - 1 of Hg and the linear working curve is from 20 to 2000 ng L - 1 (with a correlation coefficient of 0.9996). The method was applied in determination of inorganic Hg in city lake and deep well water (from Changchun, Jilin, China), and recovery test results for both samples were satisfactory.

  16. Determination of Hg(II) in waters by on-line preconcentration using Cyanex 923 as a sorbent - Cold vapor atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Duan Taicheng [State Key Laboratory of Electroanalytical Chemistry, National Research Center of Electroanalytical and Spectroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Song Xuejie [State Key Laboratory of Electroanalytical Chemistry, National Research Center of Electroanalytical and Spectroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Xu Jingwei [State Key Laboratory of Electroanalytical Chemistry, National Research Center of Electroanalytical and Spectroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Guo Pengran [State Key Laboratory of Electroanalytical Chemistry, National Research Center of Electroanalytical and Spectroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Chen Hangting [State Key Laboratory of Electroanalytical Chemistry, National Research Center of Electroanalytical and Spectroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)]. E-mail: htchen@ciac.jl.cn; Li Hongfei [Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2006-09-15

    Using a solid phase extraction mini-column home-made from a neutral extractant Cyanex 923, inorganic Hg could be on-line preconcentrated and simultaneously separated from methyl mercury. The preconcentrated Hg (II) was then eluted with 10% HNO{sub 3} and subsequently reduced by NaBH{sub 4} to form Hg vapor before determination by cold vapor atomic absorption spectrometry (CVAAS). Optimal conditions for and interferences on the Hg preconcentration and measurement were at 1% HCl, for a 25 mL sample uptake volume and a 10 mL min{sup -1} sample loading rate. The detection limit was 0.2 ng L{sup -1} and much lower than that of conventional method (around 15.8 ng L{sup -1}). The relative standard deviation (RSD) is 1.8% for measurements of 40 ng L{sup -1} of Hg and the linear working curve is from 20 to 2000 ng L{sup -1} (with a correlation coefficient of 0.9996). The method was applied in determination of inorganic Hg in city lake and deep well water (from Changchun, Jilin, China), and recovery test results for both samples were satisfactory.

  17. Formation of Dirac point and the topological surface states inside the strained gap for mixed 3D Hg1-xCdx Te

    Science.gov (United States)

    Marchewka, Michał

    2016-10-01

    In this paper the results of the numerical calculation obtained for the three-dimensional (3D) strained Hg1-xCdx Te layers for the x-Cd composition from 0.1 to 0.155 and a different mismatch of the lattice constant are presented. For the investigated region of the Cd composition (x value) the negative energy gap (Eg =Γ8 -Γ6) in the Hg1-xCdx Te is smaller than in the case of pure HgTe which, as it turns out, has a significant influence on the topological surface states (TSS) and the position of the Dirac point. The numerical calculation based on the finite difference method applied for the 8×8 kp model with the in-plane tensile strain for (001) growth oriented structure shows that the Dirac cone inside the induced insulating band gap for non zero of the Cd composition and a bigger strain caused by the bigger lattice mismatch (than for the 3D HgTe TI) can be obtained. It was also shown how different x-Cd compounds move the Dirac cone from the valence band into the band gap. The presented results show that 75 nm wide 3D Hg1-xCdx Te structures with x ≈ 0.155 and 1.6% lattice mismatch make the system a true topological insulator with the dispersion of the topological surface states similar to those ones obtained for the strained CdTe/HgTe QW.

  18. A first-principles study of Hg adsorption on Pd(1 1 1) and Pd/γ-Al{sub 2}O{sub 3}(1 1 0) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Lu [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Han, Lina, E-mail: hanlina@tyut.edu.cn [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024 (China); Cen, Wanglai [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Wang, Jiancheng; Chang, Liping [Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024 (China); Kong, Dejin [Shanghai Research Institute of Petrochemical Technology SINOPEC, Shanghai 201208 (China); Feng, Gang, E-mail: fengg.sshy@sinopec.com [Shanghai Research Institute of Petrochemical Technology SINOPEC, Shanghai 201208 (China)

    2014-12-01

    Graphical abstract: - Highlights: • The defects of Pd(1 1 1) surface can enhance the adsorption of Hg. • The adsorption energies of the stepwise adsorbed Hg atoms decreases as the Hg coverage increases. • Pd is the main active composition for improving Hg adsorption property of Pd/γ-Al{sub 2}O{sub 3} sorbents. • The Hg adsorption on Pd/γ-Al{sub 2}O{sub 3} weakens the binding of Pd to the γ-Al{sub 2}O{sub 3} surface. - Abstract: Spin-polarized density functional theory calculations were carried out to investigate the adsorption of Hg{sub n} (n = 1–3) on the perfect, step and vacancy-defective Pd(1 1 1) surfaces as well as the Pd/γ-Al{sub 2}O{sub 3}(1 1 0) surface. It is found that Hg atoms prefer to adsorb on the hollow sites on Pd(1 1 1) surfaces. The adsorption of Hg on the step and vacancy-defective Pd(1 1 1) surfaces is stronger than on the perfect Pd(1 1 1) surface, which indicates that the existence of vacancy and step defects can enhance the mercury adsorption activity of Pd adsorbents. As indicated by the calculated adsorption energies, the mercury adsorption on γ-Al{sub 2}O{sub 3} is weak. The γ-Al{sub 2}O{sub 3} supported single Pd atom shows as good Hg adsorption activity as the perfect Pd(1 1 1) surface at low Hg coverage, while more coordination unsaturated active Pd atoms is needed to achieve high Hg adsorption capacity. In addition, it was also found that the Hg adsorption on Pd/γ-Al{sub 2}O{sub 3} weakens the binding of Pd to the γ-Al{sub 2}O{sub 3} surface.

  19. Water molecules orientation in surface layer

    Science.gov (United States)

    Klingo, V. V.

    2000-08-01

    The water molecules orientation has been investigated theoretically in the water surface layer. The surface molecule orientation is determined by the direction of a molecule dipole moment in relation to outward normal to the water surface. Entropy expressions of the superficial molecules in statistical meaning and from thermodynamical approach to a liquid surface tension have been found. The molecules share directed opposite to the outward normal that is hydrogen protons inside is equal 51.6%. 48.4% water molecules are directed along to surface outward normal that is by oxygen inside. A potential jump at the water surface layer amounts about 0.2 volts.

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

    Science.gov (United States)

    Drott, A.; Skyllberg, U.

    2007-12-01

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

  1. Electrochemical detection of Hg(II in water using self-assembled single walled carbon nanotube-poly(m-amino benzene sulfonic acid on gold electrode

    Directory of Open Access Journals (Sweden)

    Gauta Gold Matlou

    2016-09-01

    Full Text Available This work reports on the detection of mercury using single walled carbon nanotube-poly (m-amino benzene sulfonic acid (SWCNT-PABS modified gold electrode by self-assembled monolayers (SAMs technique. A thiol containing moiety (dimethyl amino ethane thiol (DMAET was used to facilitate the assembly of the SWCNT-PABS molecules onto the Au electrode surface. The successfully assembled monolayers were characterised using atomic force microscopy (AFM. Cyclic voltammetric and electrochemical impedance spectroscopic studies of the modified electrode (Au-DMAET-(SWCNT-PABS showed improved electron transfer over the bare Au electrode and the Au-DMAET in [Fe (CN6]3−/4− solution. The Au-DMAET-(SWCNT-PABS was used for the detection of Hg in water by square wave anodic stripping voltammetry (SWASV analysis at the following optimized conditions: deposition potential of −0.1 V, deposition time of 30 s, 0.1 M HCl electrolyte and pH 3. The sensor showed a good sensitivity and a limit of detection of 0.06 μM with a linear concentration range of 20 ppb to 250 ppb under the optimum conditions. The analytical applicability of the proposed method with the sensor electrode was tested with real water sample and the method was validated with inductively coupled plasma – optical emission spectroscopy.

  2. Removal of inorganic mercury and methylmercury from surface waters following coagulation of dissolved organic matter with metal-based salts

    Science.gov (United States)

    Henneberry, Y.K.; Kraus, T.E.C.; Fleck, J.A.; Krabbenhoft, D.P.; Bachand, P.M.; Horwath, W.R.

    2011-01-01

    The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however these studies used high concentrations of Hg and did not reflect naturally occurring concentrations of Hg. In this study, water collected from an agricultural drain in the Sacramento-San Joaquin Delta was filtered to isolate the dissolved organic matter (DOM) fraction. The DOM was then treated with a range of coagulant doses to determine the efficacy of removing all forms of Hg from solution. Three industrial-grade coagulants were tested: ferric chloride, ferric sulfate, and polyaluminum chloride. Coagulation removed up to 85% of DOM from solution. In the absence of DOM, all three coagulants released IHg into solution, however in the presence of DOM the coagulants removed up to 97% of IHg and 80% of MeHg. Results suggest that the removal of Hg is mediated by DOM-coagulant interactions. There was a preferential association of IHg with the more aromatic, higher molecular weight fraction of DOM but no such relationship was found for MeHg. This study offers new fundamental insights regarding large-scale removal of Hg at environmentally relevant regarding large-scale removal of Hg at environmentally relevant concentrations.

  3. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment

  4. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment concentrati

  5. Rocky Mountain Arsenal surface water management plan : water year 2003

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Surface Water Management Plan (SWMP) for Water Year 2003 (WY 2003) (October I, 2002 to September 30, 2003) is an assessment of the nonpotable water demands at...

  6. Rocky Mountain Arsenal surface water management plan : water year 2005

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Surface Water Management Plan for Water Year (WY) 2005 (October 1, 2004 to September 30, 2005) is an assessment of the nonpotable water demands at the Rocky...

  7. Rocky Mountain Arsenal surface water management plan : water year 2006

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Surface Water Management Plan for Water Year (WY) 2006 (October 1, 2005 to September 30, 2006) is an assessment of the nonpotable water demands at the Rocky...

  8. DFT study of Hg adsorption on M-substituted Pd(1 1 1) and PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces

    Science.gov (United States)

    Wang, Jiancheng; Yu, Huafeng; Geng, Lu; Liu, Jianwen; Han, Lina; Chang, Liping; Feng, Gang; Ling, Lixia

    2015-11-01

    The adsorption of Hgn (n = 1-3) on the Au-, Ag-, Cu-substituted Pd(1 1 1) surfaces as well as the PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces has been investigated using spin-polarized density functional theory calculations. It is found that M-substituted Pd(1 1 1) surfaces show as good Hg adsorption capacity as the perfect Pd(1 1 1) at low Hg coverage, while the Hg adsorption capacity is only slightly weakened at high Hg coverage. On the basis of stepwise adsorption energies analysis, it is concluded that M-substituted Pd(1 1 1) surfaces can contribute to the binding of Hg atom on the surfaces at high Hg coverage. The electronic properties of the second metal atoms are the main factor contributes to the Hg adsorption capacity. Gas phase Pd2 shows better Hg adsorption capacity than Pd2/γ-Al2O3, while PdM/γ-Al2O3 can adsorb Hg more efficiently than bare PdM clusters. It suggests that the γ-Al2O3 support can enhance the activity of PdM for Hg adsorption and reduces the activity of Pd2. It is also found that Pd is the main active composition responsible for the interaction of mercury with the surface for PdM/γ-Al2O3 sorbent. Taking Hg adsorption capacity and economic costs into account, Cu addition is a comparatively good candidate for Hg capture.

  9. Surface water discharges from onshore stripper wells.

    Energy Technology Data Exchange (ETDEWEB)

    Veil, J. A.

    1998-01-16

    Under current US Environmental Protection Agency (EPA) rules, small onshore oil producers are allowed to discharge produced water to surface waters with approval from state agencies; but small onshore gas producers, however, are prohibited from discharging produced water to surface waters. The purpose of this report is to identify those states that allow surface water discharges from small onshore oil operations and to summarize the types of permitting controls they use. It is intended that the findings of this report will serve as a rationale to encourage the EPA to revise its rules and to remove the prohibition on surface water discharges from small gas operations.

  10. Water surface capturing by image processing

    Science.gov (United States)

    An alternative means of measuring the water surface interface during laboratory experiments is processing a series of sequentially captured images. Image processing can provide a continuous, non-intrusive record of the water surface profile whose accuracy is not dependent on water depth. More trad...

  11. Distribution and production of reactive mercury and dissolved gaseous mercury in surface waters and water/air mercury flux in reservoirs on Wujiang River, Southwest China

    Science.gov (United States)

    Fu, Xuewu; Feng, Xinbin; Guo, Yanna; Meng, Bo; Yin, Runsheng; Yao, Heng

    2013-05-01

    Transformation and distribution of mercury (Hg) species play an important role in the biogeochemical cycling of mercury in aquatic systems. Measurements of water/air exchange fluxes of Hg, reactive mercury (RHg), and dissolved gaseous mercury (DGM) concentrations were conducted at 14 sites in five reservoirs on the Wujiang River, Guizhou, Southwest China. Clear spatial and temporal variations in Hg fluxes, RHg, and DGM concentrations were observed in the study area. Hg fluxes and RHg concentrations exhibited a consistent diurnal variation in the study area, with maximum fluxes and concentrations during daytime. A typical diurnal trend of DGM with elevated concentration at night was observed in a eutrophic reservoir with elevated bacteria abundance, suggesting a bacteria-induced production of DGM in this reservoir. For other reservoirs, a combination of sunlight-stimulated production and loss via photo-induced oxidation and evaporation regulated the diurnal trends of DGM. Seasonal variations with elevated Hg fluxes and RHg concentrations in warm season were noticeable in the study area, which highlighted the combined effect of interrelationships between Hg species in water and environmental parameters. Hg fluxes exhibited much more significant correlations with RHg and THg concentrations and air temperature compared to DGM concentrations and solar radiation. The measured fluxes were significantly higher than those simulated using the water/air thin film Hg0 gradient model. Aside from the potential limitations of dynamic flux chamber method, this may also suggest the thin film gas exchange model is not capable of predicting water/air Hg flux under low wind speed conditions. Additionally, it is speculated that DGM concentrations might vary significantly in surface waters with depth, and measurements of DGM at a depth of 2-4 cm below the water surface probably underestimated the DGM concentration that should be taken into account in simulations of water/air flux using

  12. Flow Alteration and Chemical Reduction: Air Stripping to Lessen Subsurface Discharges of Mercury to Surface Water

    Science.gov (United States)

    Brooks, S. C.; Bogle, M.; Liang, L.; Miller, C. L.; Peterson, M.; Southworth, G. R.; Spalding, B. P.

    2009-12-01

    Mercury concentrations in groundwater, surface water, and biota near an industrial facility in Oak Ridge, Tennessee remain high some 50 years after the original major releases from the facility to the environment. Since the mid-1980s, various remedial and abatement actions have been implemented at the facility, including re-routing water flows, armoring contaminated stream banks, relining or cleanout of facility storm drains, and activated charcoal treatment of groundwater and sump discharges. These actions were taken to reduce inorganic mercury inputs from the facility to the stream; a strategy that assumes limiting the inorganic mercury precursor will reduce Hg methylation and its subsequent bioaccumulation. To date, such actions have reduced mercury loading from the site by approximately 90% from levels typical of the mid 1980's, but waterborne mercury at the facility boundary remains roughly 100 times the typical local background concentration and methylmercury accumulation in aquatic biota exceed standards for safe consumption by humans and wildlife. In 2008 and 2009, a series of investigations was initiated to explore innovative approaches to further control mercury concentrations in stream water. Efforts in this study focused on decreasing waterborne inorganic mercury inputs from two sources. The first, a highly localized source, is the discharge point of the enclosed stormdrain network whereas the second is a more diffuse short reach of stream where metallic Hg in streambed sediments generates a continued input of dissolved Hg to the overlying water. Moving a clean water flow management discharge point to a position downstream of the contaminated reach reduced mercury loading from the streambed source by 75% - 100%, likely by minimizing resuspension of Hg-rich fine particulates and changing characteristic hyporheic flow path length and residence time. Mercury in the stormdrain discharge exists as highly reactive dissolved Hg(II) due to residual chlorine in

  13. Safe Drinking Water Information System (SDWIS) Surface Water Intakes

    Data.gov (United States)

    U.S. Environmental Protection Agency — This is a point feature dataset showing the locations of surface water intakes. These intake locations are part of the safe drinking water information system...

  14. Comment on and reinterpretation of Gabriel et Al. (2014) 'fish mercury and surface water sulfate relationships in the everglades protection area'.

    Science.gov (United States)

    Julian, Paul; Gu, Binhe; Redfield, Garth

    2015-01-01

    Mercury (Hg) methylation and bioaccumulation is a major environmental issue in the Everglades Protection Area (EvPA). Therefore, it is critical to improve our predictive understanding of Hg dynamics. This commentary critically reviews a recently published manuscript concerning the possible relationship between Hg in fish tissue and surface water sulfate within EvPA marshes. The commentary addresses fundamental issues with the authors' data analysis, results and interpretation as well as highlights inconsistencies with published literature and the lack of support for their suggested ecosystem management actions. A number of chemical, biological, and physical factors influence Hg methylation and bioaccumulation, and water sulfate is sometimes viewed as a keystone factor, Gabriel et al. (2014) conclude that Hg bioaccumulation is favored at elevated sulfate concentrations, and suggest mitigation strategies to reduce sulfate inputs to the EvPA. A careful review of their data and conclusions reveals major flaws and in fact, a more straightforward and defensible interpretation of their data would be that no predictable relationship exists between fish tissue Hg and surface water sulfate concentrations in south Florida. Given the complexity of Hg cycling and the influence of trophic and habitat characteristics on aquatic consumer Hg accumulation, expecting one parameter to predict Hg accumulation dynamics within fish species within a dynamic marsh environment is unrealistic. Furthermore, proposing any management guidance from this relationship with little to no quantitative statistical analysis is inappropriate and misleading.

  15. Comment on and Reinterpretation of Gabriel et al. (2014) `Fish Mercury and Surface Water Sulfate Relationships in the Everglades Protection Area'

    Science.gov (United States)

    Julian, Paul; Gu, Binhe; Redfield, Garth

    2015-01-01

    Mercury (Hg) methylation and bioaccumulation is a major environmental issue in the Everglades Protection Area (EvPA). Therefore, it is critical to improve our predictive understanding of Hg dynamics. This commentary critically reviews a recently published manuscript concerning the possible relationship between Hg in fish tissue and surface water sulfate within EvPA marshes. The commentary addresses fundamental issues with the authors' data analysis, results and interpretation as well as highlights inconsistencies with published literature and the lack of support for their suggested ecosystem management actions. A number of chemical, biological, and physical factors influence Hg methylation and bioaccumulation, and water sulfate is sometimes viewed as a keystone factor, Gabriel et al. (2014) conclude that Hg bioaccumulation is favored at elevated sulfate concentrations, and suggest mitigation strategies to reduce sulfate inputs to the EvPA. A careful review of their data and conclusions reveals major flaws and in fact, a more straightforward and defensible interpretation of their data would be that no predictable relationship exists between fish tissue Hg and surface water sulfate concentrations in south Florida. Given the complexity of Hg cycling and the influence of trophic and habitat characteristics on aquatic consumer Hg accumulation, expecting one parameter to predict Hg accumulation dynamics within fish species within a dynamic marsh environment is unrealistic. Furthermore, proposing any management guidance from this relationship with little to no quantitative statistical analysis is inappropriate and misleading.

  16. Anti-Aliased Rendering of Water Surface

    Institute of Scientific and Technical Information of China (English)

    Xue-Ying Qin; Eihachiro Nakamae; Wei Hua; Yasuo Nagai; Qun-Sheng Peng

    2004-01-01

    Water surface is one of the most important components of landscape scenes. When rendering spacious far from the viewpoint. This is because water surface consists of stochastic water waves which are usually modeled by periodic bump mapping. The incident rays on the water surface are actually scattered by the bumped waves,pattern, we estimate this solid angle of reflected rays and trace these rays. An image-based accelerating method is adopted so that the contribution of each reflected ray can be quickly obtained without elaborate intersection calculation. We also demonstrate anti-aliased shadows of sunlight and skylight on the water surface. Both the rendered images and animations show excellent effects on the water surface of a reservoir.

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

    Science.gov (United States)

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

    2015-02-03

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

  18. SURFACE WATER QUALITY IN THE RIVER PRUT

    Directory of Open Access Journals (Sweden)

    MIHAELA DUMITRAN

    2011-03-01

    Full Text Available Water is an increasingly important and why it is important to surfacewater quality, which is given by the analysis of physical - chemical, biological andobserving the investigation of water, biota, environments investigation. Analysis ofthe Prut river in terms of biological and physical elements - chemical. Evaluationof ecological and chemical status of water was done according to order of approvalof the standard classification nr.161/2006 surface water to determine the ecologicalstatus of water bodies

  19. Manufacturing and characterisation of water repellent surfaces

    DEFF Research Database (Denmark)

    De Grave, Arnaud; Botija, Pablo; Hansen, Hans Nørgaard

    2006-01-01

    design criteria for such surfaces. The problem of adapting this behaviour to artificially roughened surfaces is addressed by providing design criteria for superhydrophobic, water-repellent and self-cleaning surfaces according to the concrete performance desired for them. Different kind of manufacturing...

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

    Science.gov (United States)

    Schiel, Detlef; Rienitz, Olaf

    2011-01-01

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

  1. Surface Water Quality Monitoring Sites

    Data.gov (United States)

    Minnesota Department of Natural Resources — The MN Department of Agriculture (MDA) is charged with periodically collecting and analyzing water samples from selected locations throughout the state to determine...

  2. Comparison of Two Mercury Contaminated Surface Water Bodies

    Science.gov (United States)

    Brooks, S. C.; Southworth, G. R.; Turner, R. R.; Jensen, R.

    2008-12-01

    Due to the methyl mercury (MeHg) burden in fish tissues, the Virginia Department of Health and the Tennessee Department of Environment and Conservation have posted fish advisories for the South River, VA and the East Fork Poplar Creek, TN (EFPC), respectively. This presentation will compare and contrast the hydrogeochemical characteristics of these two industrially contaminated water bodies. Both streams share broad similarities in terms of their general chemistry and underlying geology. Nevertheless, patterns of waterborne mercury (Hg) and, importantly, MeHg concentration are different. For example, in the South River both Hg and MeHg concentrations increase with increasing distance downstream from the industrial site of mercury origin whereas in EFPC Hg decreases while MeHg increases with increasing distance downstream. Although both sites are the focus of concerted research efforts to identify effective remediation, the underlying mechanisms that drive the patterns within each system and therefore account for the differences between them are poorly understood. We intend for this presentation to provide a context within which attendees can frame their discussion of the challenges inherent to studying the biogeochemical cycling of Hg in general and at contaminated sites in particular where effective remedies can be elusive.

  3. Survey of trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) in retail samples of flavoured and bottled waters.

    Science.gov (United States)

    Barroso, M F; Ramos, S; Oliva-Teles, M T; Delerue-Matos, C; Sales, M G F; Oliveira, M B P P

    2009-01-01

    Concentrations of eleven trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) were measured in 39 (natural and flavoured) water samples. Determinations were performed using graphite furnace electrothermetry for almost all elements (Al, As, Cd, Cr, Co, Mn, Ni, Pb, and Si). For Se determination hydride generation was used, and cold vapour generation for Hg. These techniques were coupled to atomic absorption spectrophotometry. The trace element content of still or sparkling natural waters changed from brand to brand. Significant differences between natural still and natural sparkling waters (p differences between flavoured and natural waters. The concentration of each element was compared with the presence of flavours, preservatives, acidifying agents, fruit juice and/or sweeteners, according to the labelled composition. It was shown that flavoured waters generally increase the trace element content. The addition of preservatives and acidifying regulators had a significant influence on Mn, Co, As and Si contents (p difference in Mn, Co, Se and Si content.

  4. Surface Water Treatment Workshop Manual.

    Science.gov (United States)

    Ontario Ministry of the Environment, Toronto.

    This manual was developed for use at workshops designed to increase the knowledge of experienced water treatment plant operators. Each of the fourteen lessons in this document has clearly stated behavioral objectives to tell the trainee what he should know or do after completing that topic. Areas covered in this manual include: basic water…

  5. Evidence for water structuring forces between surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, Christopher B [ORNL; Rau, Dr. Donald [National Institutes of Health

    2011-01-01

    Structured water on apposing surfaces can generate significant energies due to reorganization and displacement as the surfaces encounter each other. Force measurements on a multitude of biological structures using the osmotic stress technique have elucidated commonalities that point toward an underlying hydration force. In this review, the forces of two contrasting systems are considered in detail: highly charged DNA and nonpolar, uncharged hydroxypropyl cellulose. Conditions for both net repulsion and attraction, along with the measured exclusion of chemically different solutes from these macromolecular surfaces, are explored and demonstrate features consistent with a hydration force origin. Specifically, the observed interaction forces can be reduced to the effects of perturbing structured surface water.

  6. Total Phosphorus in Surface Water (Future)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Excess phosphorus in surface water can result in eutrophication. TOTALPFuture is reported in kilograms/hectare/year. More information about these resources,...

  7. Surface processing using water cluster ion beams

    Science.gov (United States)

    Takaoka, Gikan H.; Ryuto, Hiromichi; Takeuchi, Mitsuaki; Ichihashi, Gaku

    2013-07-01

    Vaporized water clusters were produced by an adiabatic expansion phenomenon, and various substrates such as Si(1 0 0), SiO2, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polycarbonate (PC) were irradiated by water cluster ion beams. The sputtered depth increased with increasing acceleration voltage, and the sputtering rate was much larger than that obtained using Ar monomer ion irradiation. The sputtering yield for PMMA was approximately 200 molecules per ion, at an acceleration voltage of 9 kV. X-ray photoelectron spectroscopy (XPS) measurements showed that high-rate sputtering for the PMMA surface can be ascribed to the surface erosion by the water cluster ion irradiation. Furthermore, the micropatterning was demonstrated on the PMMA substrate. Thus, the surface irradiation by water cluster ion beams exhibited a chemical reaction based on OH radicals, as well as excited hydrogen atoms, which resulted in a high sputtering rate and low irradiation damage of the substrate surfaces.

  8. Surface processing using water cluster ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Takaoka, Gikan H., E-mail: gtakaoka@kuee.kyoto-u.ac.jp [Photonics and Electronics Science and Engineering Center, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Ryuto, Hiromichi; Takeuchi, Mitsuaki; Ichihashi, Gaku [Photonics and Electronics Science and Engineering Center, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2013-07-15

    Vaporized water clusters were produced by an adiabatic expansion phenomenon, and various substrates such as Si(1 0 0), SiO{sub 2}, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polycarbonate (PC) were irradiated by water cluster ion beams. The sputtered depth increased with increasing acceleration voltage, and the sputtering rate was much larger than that obtained using Ar monomer ion irradiation. The sputtering yield for PMMA was approximately 200 molecules per ion, at an acceleration voltage of 9 kV. X-ray photoelectron spectroscopy (XPS) measurements showed that high-rate sputtering for the PMMA surface can be ascribed to the surface erosion by the water cluster ion irradiation. Furthermore, the micropatterning was demonstrated on the PMMA substrate. Thus, the surface irradiation by water cluster ion beams exhibited a chemical reaction based on OH radicals, as well as excited hydrogen atoms, which resulted in a high sputtering rate and low irradiation damage of the substrate surfaces.

  9. Exit Creek Water Surface Survey, June 2013

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset consists of survey data from a longitudinal profile of water surface surveyed June 23-24, 2013 at Exit Creek, a stream draining Exit Glacier in Kenai...

  10. US Forest Service Surface Drinking Water Importance

    Data.gov (United States)

    US Forest Service, Department of Agriculture — A map service on the www depicting watershed indexes to help identify areas of interest for protecting surface drinking water quality. The dataset depicted in this...

  11. Total Nitrogen in Surface Water (Future)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Excess nitrogen in surface water can result in eutrophication. TOTALNFuture is reported in kilograms/hectare/year. More information about these resources, including...

  12. Surface Waters Information Management System (SWIMS)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Surface Waters Information Management System (SWIMS) has been designed to meet multi-agency hydrologic database needs for Kansas. The SWIMS project was supported...

  13. The Dynamic Surface Tension of Water.

    Science.gov (United States)

    Hauner, Ines M; Deblais, Antoine; Beattie, James K; Kellay, Hamid; Bonn, Daniel

    2017-03-23

    The surface tension of water is an important parameter for many biological or industrial processes, and roughly a factor of 3 higher than that of nonpolar liquids such as oils, which is usually attributed to hydrogen bonding and dipolar interactions. Here we show by studying the formation of water drops that the surface tension of a freshly created water surface is even higher (∼90 mN m(-1)) than under equilibrium conditions (∼72 mN m(-1)) with a relaxation process occurring on a long time scale (∼1 ms). Dynamic adsorption effects of protons or hydroxides may be at the origin of this dynamic surface tension. However, changing the pH does not significantly change the dynamic surface tension. It also seems unlikely that hydrogen bonding or dipole orientation effects play any role at the relatively long time scale probed in the experiments.

  14. Water desorption from nanostructured graphite surfaces.

    Science.gov (United States)

    Clemens, Anna; Hellberg, Lars; Grönbeck, Henrik; Chakarov, Dinko

    2013-12-21

    Water interaction with nanostructured graphite surfaces is strongly dependent on the surface morphology. In this work, temperature programmed desorption (TPD) in combination with quadrupole mass spectrometry (QMS) has been used to study water ice desorption from a nanostructured graphite surface. This model surface was fabricated by hole-mask colloidal lithography (HCL) along with oxygen plasma etching and consists of a rough carbon surface covered by well defined structures of highly oriented pyrolytic graphite (HOPG). The results are compared with those from pristine HOPG and a rough (oxygen plasma etched) carbon surface without graphite nanostructures. The samples were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TPD experiments were conducted for H2O coverages obtained after exposures between 0.2 and 55 langmuir (L) and reveal a complex desorption behaviour. The spectra from the nanostructured surface show additional, coverage dependent desorption peaks. They are assigned to water bound in two-dimensional (2D) and three-dimensional (3D) hydrogen-bonded networks, defect-bound water, and to water intercalated into the graphite structures. The intercalation is more pronounced for the nanostructured graphite surface in comparison to HOPG surfaces because of a higher concentration of intersheet openings. From the TPD spectra, the desorption energies for water bound in 2D and 3D (multilayer) networks were determined to be 0.32 ± 0.06 and 0.41 ± 0.03 eV per molecule, respectively. An upper limit for the desorption energy for defect-bound water was estimated to be 1 eV per molecule.

  15. Polyfluorinated chemicals in European surface waters, ground- and drinking waters

    NARCIS (Netherlands)

    Eschauzier, C.; de Voogt, P.; Brauch, H.-J.; Lange, F.T.; Knepper, T.P.; Lange, F.T.

    2012-01-01

    Polyfluorinated chemicals (PFCs), especially short chain fluorinated alkyl sulfonates and carboxylates, are ubiquitously found in the environment. This chapter aims at giving an overview of PFC concentrations found in European surface, ground- and drinking waters and their behavior during convention

  16. Polyfluorinated chemicals in European surface waters, ground- and drinking waters

    NARCIS (Netherlands)

    Eschauzier, C.; de Voogt, P.; Brauch, H.-J.; Lange, F.T.; Knepper, T.P.; Lange, F.T.

    2012-01-01

    Polyfluorinated chemicals (PFCs), especially short chain fluorinated alkyl sulfonates and carboxylates, are ubiquitously found in the environment. This chapter aims at giving an overview of PFC concentrations found in European surface, ground- and drinking waters and their behavior during

  17. Stable water layers on solid surfaces.

    Science.gov (United States)

    Hong, Ying-Jhan; Tai, Lin-Ai; Chen, Hung-Jen; Chang, Pin; Yang, Chung-Shi; Yew, Tri-Rung

    2016-02-17

    Liquid layers adhered to solid surfaces and that are in equilibrium with the vapor phase are common in printing, coating, and washing processes as well as in alveoli in lungs and in stomata in leaves. For such a liquid layer in equilibrium with the vapor it faces, it has been generally believed that, aside from liquid lumps, only a very thin layer of the liquid, i.e., with a thickness of only a few nanometers, is held onto the surface of the solid, and that this adhesion is due to van der Waals forces. A similar layer of water can remain on the surface of a wall of a microchannel after evaporation of bulk water creates a void in the channel, but the thickness of such a water layer has not yet been well characterized. Herein we showed such a water layer adhered to a microchannel wall to be 100 to 170 nm thick and stable against surface tension. The water layer thickness was measured using electron energy loss spectroscopy (EELS), and the water layer structure was characterized by using a quantitative nanoparticle counting technique. This thickness was found for channel gap heights ranging from 1 to 5 μm. Once formed, the water layers in the microchannel, when sealed, were stable for at least one week without any special care. Our results indicate that the water layer forms naturally and is closely associated only with the surface to which it adheres. Our study of naturally formed, stable water layers may shed light on topics from gas exchange in alveoli in biology to the post-wet-process control in the semiconductor industry. We anticipate our report to be a starting point for more detailed research and understanding of the microfluidics, mechanisms and applications of gas-liquid-solid systems.

  18. Hg-Mask Coronagraph

    Science.gov (United States)

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

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

  19. Design Strategies for CeO2-MoO3 Catalysts for DeNOx and Hg(0) Oxidation in the Presence of HCl: The Significance of the Surface Acid-Base Properties.

    Science.gov (United States)

    Chang, Huazhen; Wu, Qingru; Zhang, Tao; Li, Mingguan; Sun, Xiaoxu; Li, Junhua; Duan, Lei; Hao, Jiming

    2015-10-20

    A series of CeMoOx catalysts with different surface Ce/Mo ratios was synthesized by a coprecipitation method via changing precipitation pH value. The surface basicity on selective catalytic reduction (SCR) catalysts (CeMoOx and VMo/Ti) was characterized and correlated to the durability and activity of catalyst for simultaneous elimination of NOx and Hg(0). The pH value in the preparation process affected the surface concentrations of Ce and Mo, the Brunauer-Emmett-Teller (BET) specific surface area, and the acid-base properties over the CeMoOx catalysts. The O 1s X-ray photoelectron spectroscopy (XPS) spectra and CO2-temperature programmed desorption (TPD) suggested that the surface basicity increased as the pH value increased. The existence of strong basic sites contributed to the deactivation effect of HCl over the VMo/Ti and CeMoOx catalysts prepared at pH = 12. For the CeMoOx catalysts prepared at pH = 9 and 6, the appearance of surface molybdena species replaced the surface -OH, and the existence of appropriate medium-strength basic sites contributed to their resistance to HCl poisoning in the SCR reaction. Moreover, these sites facilitated the adsorption and activation of HCl and enhanced Hg(0) oxidation. On the other hand, the inhibitory effect of NH3 on Hg(0) oxidation was correlated with the competitive adsorption of NH3 and Hg(0) on acidic surface sites. Therefore, acidic surface sites may play an important role in Hg(0) adsorption. The characterization and balance of basicity and acidity of an SCR catalyst is believed to be helpful in preventing deactivation by acid gas in the SCR reaction and simultaneous Hg(0) oxidation.

  20. Radiolysis of water with aluminum oxide surfaces

    Science.gov (United States)

    Reiff, Sarah C.; LaVerne, Jay A.

    2017-02-01

    Aluminum oxide, Al2O3, nanoparticles with water were irradiated with γ-rays and 5 MeV He ions followed by the determination of the production of molecular hydrogen, H2, and characterization of changes in the particle surface. Surface analysis techniques included: diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), nitrogen absorption with the Brunauer - Emmett - Teller (BET) methodology for surface area determination, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Production of H2 by γ-ray radiolysis was determined for samples with adsorbed water and for Al2O3 - water slurries. For Al2O3 samples with adsorbed water, the radiation chemical yield of H2 was measured as 80±20 molecules/100 eV (1 molecule/100 eV=1.04×10-7 mol/J). The yield of H2 was observed to decrease as the amount of water present in the Al2O3 - water slurries increased. Surface studies indicated that the α-phase Al2O3 samples changed phase following irradiation by He ions, and that the oxyhydroxide layer, present on the pristine sample, is removed by γ-ray and He ion irradiation.

  1. Water vapor interactions with polycrystalline titanium surfaces

    Science.gov (United States)

    Azoulay, A.; Shamir, N.; Volterra, V.; Mintz, M. H.

    1999-02-01

    The initial interactions of water vapor with polycrystalline titanium surfaces were studied at room temperature. Measurements of water vapor surface accumulation were performed in a combined surface analysis system incorporating direct recoils spectrometry (DRS), Auger electron spectroscopy and X-ray photoelectron spectroscopy. The kinetics of accommodation of the water dissociation fragments (H, O and OH) displayed a complex behavior depending not only on the exposure dose but also on the exposure pressure. For a given exposure dose the efficiency of chemisorption increased with increasing exposure pressure. DRS measurements indicated the occurrence of clustered hydroxyl moieties with tilted O-H bonds formed even at very low surface coverage. A model which assumes two parallel routes of chemisorption, by direct collisions (Langmuir type) and by a precursor state is proposed to account for the observed behavior. The oxidation efficiency of water seemed to be much lower than that of oxygen. No Ti 4+ states were detected even at high water exposure values. It is likely that hydroxyl species play an important role in the reduced oxidation efficiency of water.

  2. A Water Rich Mars Surface Mission Scenario

    Science.gov (United States)

    Hoffman, Stephen; Andrews, Alida; Joosten, Kent; Watts, Kevin

    2017-01-01

    The surface of Mars once had abundant water flowing on its surface, but now there is a general perception that this surface is completely dry. Several lines of research have shown that there are sources of potentially large quantities of water at many locations on the surface, including regions considered as candidates for future human missions. Traditionally, system designs for these human missions are constrained to tightly recycle water and oxygen, and current resource utilization strategies involve ascent vehicle oxidizer production only. But the assumption of relatively abundant extant water may change this. Several scenarios were constructed to evaluate water requirements for human Mars expeditions to assess the impact to system design if locally produced water is available. Specifically, we have assessed water resources needed for 1) ascent vehicle oxidizer and fuel production, 2) open-loop water and oxygen life support requirements along with more robust usage scenarios, and 3) crew radiation protection augmentation. In this assessment, production techniques and the associated chemistry to transform Martian water and atmosphere into these useful commodities are identified, but production mass and power requirements are left to future analyses. The figure below illustrates the type of water need assessment performed and that will be discussed. There have been several sources of feedstock material discussed in recent literature that could be used to produce these quantities of water. This paper will focus on Mars surface features that resemble glacier-like forms on Earth. Several lines of evidence indicate that some of these features are in fact buried ice, likely remnants from an earlier ice age on Mars. This paper examines techniques and hardware systems used in the polar regions of Earth to access this buried ice and withdraw water from it. These techniques and systems will be described to illustrate options available. A technique known as a Rodriguez Well

  3. Electrolysis of water on (oxidized) metal surfaces

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2005-01-01

    directly from the electronic structure calculations. We consider electrodes of Pt(111) and Au(111) in detail and then discuss trends for a series of different metals. We show that the difficult step in the water splitting process is the formation of superoxy-type (OOH) species on the surface...... by the splitting of a water molecule on top an adsorbed oxygen atom. One conclusion is that this is only possible on metal surfaces that are (partly) oxidized. We show that the binding energies of the different intermediates are linearly correlated for a number of metals. In a simple analysis, where the linear...... relations are assumed to be obeyed exactly, this leads to a universal relationship between the catalytic rate and the oxygen binding energy. Finally, we conclude that for systems obeying these relations, there is a limit to how good a water splitting catalyst an oxidized metal surface can become. (c) 2005...

  4. SURFACE WATER POLLUTION WITH HEAVY METALS IN THE LOWER CATCHMENT OF JIU RIVER BASIN, ACCORDING TO THE WATER FRAMEWORK DIRECTIVE (2000/60/EC

    Directory of Open Access Journals (Sweden)

    ADINA SANDA ŞERBAN

    2011-03-01

    Full Text Available Surface water pollution with heavy metals in the lower catchment of Jiu river basin, according to the Water Framework Directive (2000/60/EC. The Water Framework Directive establishes a single transparent, effective and coherent water policy by defining a strategy to combat pollution by requiring specific action programs.Chemical pollution of surface water presents a threat to the aquatic environment with acute and chronic toxicity to aquatic organisms, accumulation in the ecosystem and losses of habitats and biodiversity, as well as a threat to human health (art.1 from Directive 2008/105/EC regarding the environmental quality standards for water policy.The purpose of this study is to evaluate the chemical status for surface water bodies in the lower catchment of Jiu river basin. The assessment was made taking into account the water impact of four heavy metals: cadmium (Cd, nickel (Ni, mercury (Hg and lead (Pb.

  5. Surface Modification of Water Purification Membranes.

    Science.gov (United States)

    Miller, Daniel J; Dreyer, Daniel R; Bielawski, Christopher W; Paul, Donald R; Freeman, Benny D

    2017-04-18

    Polymeric membranes are an energy-efficient means of purifying water, but they suffer from fouling during filtration. Modification of the membrane surface is one route to mitigating membrane fouling, as it helps to maintain high levels of water productivity. Here, a series of common techniques for modification of the membrane surface are reviewed, including surface coating, grafting, and various treatment techniques such as chemical treatment, UV irradiation, and plasma treatment. Historical background on membrane development and surface modification is also provided. Finally, polydopamine, an emerging material that can be easily deposited onto a wide variety of substrates, is discussed within the context of membrane modification. A brief summary of the chemistry of polydopamine, particularly as it may pertain to membrane development, is also described. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Surface Water Protection by Productive Buffers

    DEFF Research Database (Denmark)

    Christen, Benjamin

    Vegetated riparian buffer zones are a widely recommended best management practice in agriculture for protecting surface and coastal waters from diffuse nutrient pollution. On the background of the EU funded research project NitroEurope (NEU; www.NitroEurope.eu), this study concentrates...... on the mitigation of nitrogen pollution in surface and groundwater, using riparian buffer zones for biomass production. The objectives are to map suitable areas for buffer implementation across the six NEU study landscapes, model tentative N-loss mitigation, calculate biomass production potential and economic...... designed for local conditions could be a way of protecting water quality attractive to many stakeholders....

  7. Hg 1- xCd xTe (0 ≦ x ≦ 1): a correlation between stoichiometry, surface preparation and electroreflectance measurements

    Science.gov (United States)

    Lemasson, Philippe; Van Huong, Chau Nguyen

    1990-11-01

    Mercury cadmium telluride (HCT) alloys are studied in the whole composition range by electrochemistry and electroreflectance (ER). For Hg 1- xCd xTe with 0 ≦ x ≦ 0.5 and x = 1, fairly well-defined ER structures are easily obtained using a simple pro The alloy surface is mechanically polished (0.5 μm), chemically etched in 1% bromine in methanol solution and then prepared electrochemically by cyclic voltammetry. On the other hand, ER measurements for x = 0.7 are possible only if the HCT sample is, in addition, treated specifically by means of a large amplitude AC perturbation (1 V rms, 15 Hz) for 1 to 5 min while the mean current is kept approximately zero. The electrochemical processes involved in the alloy surface preparation are analyzed in terms of a decomposition which leads to soluble species. In the whole composition range, ER spectra can be fairly well interpreted using classical methods. Energy values obtained, in particular for the E1 band-band transition, correspond exactly to what is expected on the basis of the composition of the bulk material. Therefore, electrochemistry and electroreflectance appear to be complementary techniques for the preparation and characterization of HCT alloy surfaces.

  8. Surface-Water Conditions in Georgia, Water Year 2005

    Science.gov (United States)

    Painter, Jaime A.; Landers, Mark N.

    2007-01-01

    INTRODUCTION The U.S. Geological Survey (USGS) Georgia Water Science Center-in cooperation with Federal, State, and local agencies-collected surface-water streamflow, water-quality, and ecological data during the 2005 Water Year (October 1, 2004-September 30, 2005). These data were compiled into layers of an interactive ArcReaderTM published map document (pmf). ArcReaderTM is a product of Environmental Systems Research Institute, Inc (ESRI?). Datasets represented on the interactive map are * continuous daily mean streamflow * continuous daily mean water levels * continuous daily total precipitation * continuous daily water quality (water temperature, specific conductance dissolved oxygen, pH, and turbidity) * noncontinuous peak streamflow * miscellaneous streamflow measurements * lake or reservoir elevation * periodic surface-water quality * periodic ecological data * historical continuous daily mean streamflow discontinued prior to the 2005 water year The map interface provides the ability to identify a station in spatial reference to the political boundaries of the State of Georgia and other features-such as major streams, major roads, and other collection stations. Each station is hyperlinked to a station summary showing seasonal and annual stream characteristics for the current year and for the period of record. For continuous discharge stations, the station summary includes a one page graphical summary page containing five graphs, a station map, and a photograph of the station. The graphs provide a quick overview of the current and period-of-record hydrologic conditions of the station by providing a daily mean discharge graph for the water year, monthly statistics graph for the water year and period of record, an annual mean streamflow graph for the period of record, an annual minimum 7-day average streamflow graph for the period of record, and an annual peak streamflow graph for the period of record. Additionally, data can be accessed through the layer's link

  9. Ultra Water Repellent Polypropylene Surfaces with Tunable Water Adhesion.

    Science.gov (United States)

    Zhu, Tang; Cai, Chao; Guo, Jing; Wang, Rong; Zhao, Ning; Xu, Jian

    2017-03-22

    Polypropylene (PP), including isotactic PP (i-PP) and atactic PP (a-PP) with distinct tacticity, is one of the most widely used general plastics. Herein, ultra water repellent PP coatings with tunable adhesion to water were prepared via a simple casting method. The pure i-PP coating shows a hierarchical morphology with micro/nanobinary structures, exhibiting a water contact angle (CA) larger than 150° and a sliding angle less than 5° (for 5 μL water droplet). In contrast, the pure a-PP coating has a less rough morphology with a water contact angle of about 130°, and the water droplets stick on the coating at any tilted angles. For the composite i-PP/a-PP coatings, however, ultra water repellency with CA > 150° but water adhesion tailorable from slippery to sticky can be realized, depending on the contents of a-PP and i-PP. The different wetting behaviors are due to the various microstructures of the composite coatings resulting from the distinct crystallization ability of a-PP and i-PP. Furthermore, the existence of a-PP in the composite coatings enhances the mechanical properties compared to the i-PP coating. The proposed method is feasible to modify various substrates and potential applications in no-loss liquid transportation, slippery surfaces, and patterned superhydrophobic surfaces are demonstrated.

  10. Global modelling of Cryptosporidium in surface water

    Science.gov (United States)

    Vermeulen, Lucie; Hofstra, Nynke

    2016-04-01

    Introduction Waterborne pathogens that cause diarrhoea, such as Cryptosporidium, pose a health risk all over the world. In many regions quantitative information on pathogens in surface water is unavailable. Our main objective is to model Cryptosporidium concentrations in surface waters worldwide. We present the GloWPa-Crypto model and use the model in a scenario analysis. A first exploration of global Cryptosporidium emissions to surface waters has been published by Hofstra et al. (2013). Further work has focused on modelling emissions of Cryptosporidium and Rotavirus to surface waters from human sources (Vermeulen et al 2015, Kiulia et al 2015). A global waterborne pathogen model can provide valuable insights by (1) providing quantitative information on pathogen levels in data-sparse regions, (2) identifying pathogen hotspots, (3) enabling future projections under global change scenarios and (4) supporting decision making. Material and Methods GloWPa-Crypto runs on a monthly time step and represents conditions for approximately the year 2010. The spatial resolution is a 0.5 x 0.5 degree latitude x longitude grid for the world. We use livestock maps (http://livestock.geo-wiki.org/) combined with literature estimates to calculate spatially explicit livestock Cryptosporidium emissions. For human Cryptosporidium emissions, we use UN population estimates, the WHO/UNICEF JMP sanitation country data and literature estimates of wastewater treatment. We combine our emissions model with a river routing model and data from the VIC hydrological model (http://vic.readthedocs.org/en/master/) to calculate concentrations in surface water. Cryptosporidium survival during transport depends on UV radiation and water temperature. We explore pathogen emissions and concentrations in 2050 with the new Shared Socio-economic Pathways (SSPs) 1 and 3. These scenarios describe plausible future trends in demographics, economic development and the degree of global integration. Results and

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

    Science.gov (United States)

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

    2014-01-01

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

  12. Lithium content in potable water, surface water, ground water, and mineral water on the territory of Republic of Macedonia

    OpenAIRE

    Vesna Kostik; Biljana Bauer; Zoran Kavrakovski

    2014-01-01

    The aim of this study was to determine lithium concentration in potable water, surface water, ground, and mineral water on the territory of the Republic of Macedonia. Water samples were collected from water bodies such as multiple public water supply systems located in 13 cities, wells boreholes located in 12 areas, lakes and rivers located in three different areas. Determination of lithium concentration in potable water, surface water was performed by the technique of inductively coupl...

  13. Thermodynamic properties of water solvating biomolecular surfaces

    Science.gov (United States)

    Heyden, Matthias

    Changes in the potential energy and entropy of water molecules hydrating biomolecular interfaces play a significant role for biomolecular solubility and association. Free energy perturbation and thermodynamic integration methods allow calculations of free energy differences between two states from simulations. However, these methods are computationally demanding and do not provide insights into individual thermodynamic contributions, i.e. changes in the solvent energy or entropy. Here, we employ methods to spatially resolve distributions of hydration water thermodynamic properties in the vicinity of biomolecular surfaces. This allows direct insights into thermodynamic signatures of the hydration of hydrophobic and hydrophilic solvent accessible sites of proteins and small molecules and comparisons to ideal model surfaces. We correlate dynamic properties of hydration water molecules, i.e. translational and rotational mobility, to their thermodynamics. The latter can be used as a guide to extract thermodynamic information from experimental measurements of site-resolved water dynamics. Further, we study energy-entropy compensations of water at different hydration sites of biomolecular surfaces. This work is supported by the Cluster of Excellence RESOLV (EXC 1069) funded by the Deutsche Forschungsgemeinschaft.

  14. Impinging Water Droplets on Inclined Glass Surfaces.

    Energy Technology Data Exchange (ETDEWEB)

    Armijo, Kenneth Miguel; Lance, Blake; Ho, Clifford K.

    2017-09-01

    Multiphase computational models and tests of falling water droplets on inclined glass surfaces were developed to investigate the physics of impingement and potential of these droplets to self-clean glass surfaces for photovoltaic modules and heliostats. A multiphase volume-of-fluid model was developed in ANSYS Fluent to simulate the impinging droplets. The simulations considered different droplet sizes (1 mm and 3 mm), tilt angles (0deg, 10deg, and 45deg), droplet velocities (1 m/s and 3 m/s), and wetting characteristics (wetting=47deg contact angle and non-wetting = 93deg contact angle). Results showed that the spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) decreased with increasing inclination angle due to the reduced normal force on the surface. The hydrophilic surface yielded greater spread factors than the hydrophobic surface in all cases. With regard to impact forces, the greater surface tilt angles yielded lower normal forces, but higher shear forces. Experiments showed that the experimentally observed spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) was significantly larger than the simulated spread factor. Observed spread factors were on the order of 5 - 6 for droplet velocities of %7E3 m/s, whereas the simulated spread factors were on the order of 2. Droplets were observed to be mobile following impact only for the cases with 45deg tilt angle, which matched the simulations. An interesting phenomenon that was observed was that shortly after being released from the nozzle, the water droplet oscillated (like a trampoline) due to the "snapback" caused by the surface tension of the water droplet being released from the nozzle. This oscillation impacted the velocity immediately after the release. Future work should evaluate the impact of parameters such as tilt angle and surface wettability on the impact of particle/soiling uptake and removal to investigate ways that

  15. Chemical surface inhomogeneities in late B-type stars with Hg and Mn peculiarity I Spot evolution in HD 11753 on short and long time scales

    CERN Document Server

    Korhonen, H; Briquet, M; Soriano, M Flores; Hubrig, S; Savanov, I; Hackman, T; Ilyin, I V; Eulaers, E; Pessemier, W

    2013-01-01

    Aims: Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. Methods: High-resolution and high signal-to-noise ratio spectra were obtained using the CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII, SrII, TiII, and CrII were calculated using the Doppler imaging technique. The results were also compared to equivalent width measurements. The evolution of chemical spots both on short and long time scales were investigated. Results: We determine the binary orbit of HD 11753 and fine-tune the rotation period of the primary. The earlier discovered fast evolution of the chemical spots is confirmed by an analysis using both the chemical spot maps and equivalent width measurements. In addition, a long-term decrease in the overall YII and SrII abundances is discovered. A detailed analysis of the chemical spot configurations reveals som...

  16. Water at surfaces with tunable surface chemistries and the chiral imprint of water around DNA

    Science.gov (United States)

    Petersen, Poul

    Aqueous interfaces are ubiquitous in atmospheric chemistry and biological systems but are notoriously hard to probe experimentally. Surface-specific vibrational spectroscopy offers an avenue to directly probe the vibrational modes of the water OH stretching band but this method is challenging to implement to buried surfaces. Here we present results from sum-frequency generation (SFG) spectroscopy probing the buried interface between a functionalized surface and aqueous solutions. Studying such buried surfaces offers the advantage of being able to systematically tune the surface chemistry using self-assembled monolayers, i.e. the hydrophobic and hydrophilic character, and examine the effect on the interfacial water. In addition to water at these controlled surfaces, we have initiated studying water at biological surfaces. This includes the solvation structure around DNA. X-ray experiments at cryogenic temperatures have found crystallographic water in the minor grove of DNA giving rise to the notion of a spine of hydration surrounding DNA. Such structured water should exhibit a chiral structure adapted from DNA. We investigate if such a chiral water structure exist around DNA at room temperature using chiral SFG. This work was supported by the National Science Foundation under a NSF CAREER Grant (CHE-1151079).

  17. A Water Rich Mars Surface Mission Scenario

    Science.gov (United States)

    Hoffman, Stephen J.; Andrews, Alida; Joosten, B. Kent; Watts, Kevin

    2017-01-01

    In an on-going effort to make human Mars missions more affordable and sustainable, NASA continues to investigate the innovative leveraging of technological advances in conjunction with the use of accessible Martian resources directly applicable to these missions. One of the resources with the broadest utility for human missions is water. Many past studies of human Mars missions assumed a complete lack of water derivable from local sources. However, recent advances in our understanding of the Martian environment provides growing evidence that Mars may be more "water rich" than previously suspected. This is based on data indicating that substantial quantities of water are mixed with surface regolith, bound in minerals located at or near the surface, and buried in large glacier-like forms. This paper describes an assessment of what could be done in a "water rich" human Mars mission scenario. A description of what is meant by "water rich" in this context is provided, including a quantification of the water that would be used by crews in this scenario. The different types of potential feedstock that could be used to generate these quantities of water are described, drawing on the most recently available assessments of data being returned from Mars. This paper specifically focuses on sources that appear to be buried quantities of water ice. (An assessment of other potential feedstock materials is documented in another paper.) Technologies and processes currently used in terrestrial Polar Regions are reviewed. One process with a long history of use on Earth and with potential application on Mars - the Rodriguez Well - is described and results of an analysis simulating the performance of such a well on Mars are presented. These results indicate that a Rodriguez Well capable of producing the quantities of water identified for a "water rich" human mission are within the capabilities assumed to be available on the Martian surface, as envisioned in other comparable Evolvable

  18. Streamers sliding on a water surface

    Science.gov (United States)

    Akishev, Yuri Semenov; Karalnik, Vladimir; Medvedev, Mikhail; Petryakov, Alexander; Trushkin, Nikolay; Shafikov, Airat

    2017-06-01

    The features of an electrical interaction between surface streamers (thin current filaments) sliding on a liquid and liquid itself are still unknown in many details. This paper presents the experimental results on properties of the surface streamers sliding on water with different conductivity (distilled and tap water). The streamers were initiated with a sharpened thin metallic needle placed above the liquid and stressed with a periodical or pulsed high voltage. Two electrode systems were used and tested. The first of them provides in advance the existence of the longitudinal electric field above the water. The second one imitates the electrode geometry of a pin-to-plane dielectric barrier discharge in which the barrier is a thick layer of liquid. The electrical and optical characteristics of streamers were complemented with data on the spectroscopic measurements. It was revealed that surface streamers on water have no spatial memory. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

  19. Uncertainty in surface water flood risk modelling

    Science.gov (United States)

    Butler, J. B.; Martin, D. N.; Roberts, E.; Domuah, R.

    2009-04-01

    Two thirds of the flooding that occurred in the UK during summer 2007 was as a result of surface water (otherwise known as ‘pluvial') rather than river or coastal flooding. In response, the Environment Agency and Interim Pitt Reviews have highlighted the need for surface water risk mapping and warning tools to identify, and prepare for, flooding induced by heavy rainfall events. This need is compounded by the likely increase in rainfall intensities due to climate change. The Association of British Insurers has called for the Environment Agency to commission nationwide flood risk maps showing the relative risk of flooding from all sources. At the wider European scale, the recently-published EC Directive on the assessment and management of flood risks will require Member States to evaluate, map and model flood risk from a variety of sources. As such, there is now a clear and immediate requirement for the development of techniques for assessing and managing surface water flood risk across large areas. This paper describes an approach for integrating rainfall, drainage network and high-resolution topographic data using Flowroute™, a high-resolution flood mapping and modelling platform, to produce deterministic surface water flood risk maps. Information is provided from UK case studies to enable assessment and validation of modelled results using historical flood information and insurance claims data. Flowroute was co-developed with flood scientists at Cambridge University specifically to simulate river dynamics and floodplain inundation in complex, congested urban areas in a highly computationally efficient manner. It utilises high-resolution topographic information to route flows around individual buildings so as to enable the prediction of flood depths, extents, durations and velocities. As such, the model forms an ideal platform for the development of surface water flood risk modelling and mapping capabilities. The 2-dimensional component of Flowroute employs

  20. Influence of infrared radiation on the electrical characteristics of the surface-barrier nanostructures based on MBE HgCdTe

    Science.gov (United States)

    Pociask-Bialy, Malgorzata; Izhnin, Ihor; Voitsekhovskii, Alexander; Nesmelov, Sergey; Dzyadukh, Stanislav

    2016-12-01

    Impact of illumination on the admittance of the MIS structures based on MBE Hg1-xCdxTe with graded-gap layers and single quantum wells was investigated. It is shown that for HgCdTe-based nanostructures the illumination greatly affects the capacitance and conductance dependencies. The capacitance-voltage characteristics exhibit a low-frequency behavior, which is associated with a decrease in the differential resistance of the space charge region. Especially informative illumination exposure is in the study of deep traps in n-HgCdTe (x=0.21-0.23) without graded-gap layer. Illumination leads to the low-frequency behavior of capacitance-voltage characteristics of MIS structures based on p-HgCdTe with HgTe single quantum well in the active region, and maximums in the voltage dependences do not appear.

  1. Source Water Assessment for the Las Vegas Valley Surface Waters

    Science.gov (United States)

    Albuquerque, S. P.; Piechota, T. C.

    2003-12-01

    The 1996 amendment to the Safe Drinking Water Act of 1974 created the Source Water Assessment Program (SWAP) with an objective to evaluate potential sources of contamination to drinking water intakes. The development of a Source Water Assessment Plan for Las Vegas Valley surface water runoff into Lake Mead is important since it will guide future work on source water protection of the main source of water. The first step was the identification of the watershed boundary and source water protection area. Two protection zones were delineated. Zone A extends 500 ft around water bodies, and Zone B extends 3000 ft from the boundaries of Zone A. These Zones extend upstream to the limits of dry weather flows in the storm channels within the Las Vegas Valley. After the protection areas were identified, the potential sources of contamination in the protection area were inventoried. Field work was conducted to identify possible sources of contamination. A GIS coverage obtained from local data sources was used to identify the septic tank locations. Finally, the National Pollutant Discharge Elimination System (NPDES) Permits were obtained from the State of Nevada, and included in the inventory. After the inventory was completed, a level of risk was assigned to each potential contaminating activity (PCA). The contaminants of concern were grouped into five categories: volatile organic compounds (VOCs), synthetic organic compounds (SOCs), inorganic compounds (IOCs), microbiological, and radionuclides. The vulnerability of the water intake to each of the PCAs was assigned based on these five categories, and also on three other factors: the physical barrier effectiveness, the risk potential, and the time of travel. The vulnerability analysis shows that the PCAs with the highest vulnerability rating include septic systems, golf courses/parks, storm channels, gas stations, auto repair shops, construction, and the wastewater treatment plant discharges. Based on the current water quality

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

    Science.gov (United States)

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

    2016-06-01

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

  3. How Water Advances on Superhydrophobic Surfaces

    Science.gov (United States)

    Schellenberger, Frank; Encinas, Noemí; Vollmer, Doris; Butt, Hans-Jürgen

    2016-03-01

    Superliquid repellency can be achieved by nano- and microstructuring surfaces in such a way that protrusions entrap air underneath the liquid. It is still not known how the three-phase contact line advances on such structured surfaces. In contrast to a smooth surface, where the contact line can advance continuously, on a superliquid-repellent surface, the contact line has to overcome an air gap between protrusions. Here, we apply laser scanning confocal microscopy to get the first microscopic videos of water drops advancing on a superhydrophobic array of micropillars. In contrast to common belief, the liquid surface gradually bends down until it touches the top face of the next micropillars. The apparent advancing contact angle is 180°. On the receding side, pinning to the top faces of the micropillars determines the apparent receding contact angle. Based on these observations, we propose that the apparent receding contact angle should be used for characterizing superliquid-repellent surfaces rather than the apparent advancing contact angle and hysteresis.

  4. One-step competitive lateral flow biosensor running on an independent quantification system for smart phones based in-situ detection of trace Hg(II) in tap water.

    Science.gov (United States)

    Cheng, Nan; Xu, Yuancong; Huang, Kunlun; Chen, Yuting; Yang, Zhansen; Luo, Yunbo; Xu, Wentao

    2017-01-01

    In this study, a one-step lateral flow biosensor (LFB) has been developed, optimized and validated for quantitative detection of Hg(II) in water. In the measurement principle, just one T-rich ssDNA probe (TSP) for the specific binding process was successfully employed in the competitive LFB based methods. The concept of an independent quantification system was realized using a cresol red dot as an external standard, which effectively eliminates false negative results. Under optimized conditions, the limit of detection for Hg(II) was 4nM; high selectivity towards Hg(II) and extraordinary device-to-device repeatability of the LFB were achieved. Furthermore, Hg(II) from tap water samples was analyzed, and the results were confirmed by ICP-MS. The interference from other components in the real samples could be neglected during the analysis. The approach provides a simple, sensitive, and practical tool for the detection of trace Hg(II) in tap water, showing great promise for in-situ applications.

  5. Convergent surface water distributions in U.S. cities

    Science.gov (United States)

    M.K. Steele; J.B. Heffernan; N. Bettez; J. Cavender-Bares; P.M. Groffman; J.M. Grove; S. Hall; S.E. Hobbie; K. Larson; J.L. Morse; C. Neill; K.C. Nelson; J. O' Neil-Dunne; L. Ogden; D.E. Pataki; C. Polsky; R. Roy Chowdhury

    2014-01-01

    Earth's surface is rapidly urbanizing, resulting in dramatic changes in the abundance, distribution and character of surface water features in urban landscapes. However, the scope and consequences of surface water redistribution at broad spatial scales are not well understood. We hypothesized that urbanization would lead to convergent surface water abundance and...

  6. Heavy metal contamination, sources, and pollution assessment of surface water in the Tianshan Mountains of China.

    Science.gov (United States)

    Zhaoyong, Zhang; Abuduwaili, Jilili; Fengqing, Jiang

    2015-02-01

    In order to gain insight into heavy metal contamination occurring in the surface water of the Tianshan Mountains in northwest China, we collected surface water samples from there, tested heavy metals Pb, Ni, Cd, Co, Hg, As, Cu, Mn, Zn, and Cr, and then we analyzed the data using typical analysis, multivariate statistical, and pollution index methods. Results showed that (1) the order of the average values of the ten kinds of heavy metals in all the water samples was as follows: Zn > Mn > Cu > Co > Ni > Pb > Cr > As > Hg > Cd. The maximum variation coefficients of Zn and Pb were 138.96 and 145.86 %, respectively, indicating that these heavy metal concentrations varied largely between different sampling locations. (2) Research showed the average concentrations of Pb, Cd, As, Cu, Zn, and Cr were all within the national surface water standard of class IV and those of As, Cu, Mn, and Cr were all within the range of the Drinking Water Guidelines from the WHO, indicating the surface water of the Tianshan Mountains is clean. (3) Multivariate statistical analysis showed that Cu, Cd, Mn, Hg, Zn, and Pb have close correlations, and they mainly came from artificial sources; while Ni, As, Co, Cu, and Cr mainly came from natural sources. The results of correlation analysis, principal component analysis, and cluster analysis are consistent. (4) Pollution evaluation showed the values of comprehensive pollution index (WQI) of ten kinds of heavy metals in three sections were all lower than 2, suggesting the low levels of pollution, while the over-limit ratios of Pb and Zn in water samples of the middle Urumqi-Akesu section, As in the western Zhaosu-Tekesi section, and Pb, Hg, and Zn in the eastern Balikun-Yiwu section were all above 10 %. This research shows that recent economic development of the Tianshan Mountains has negatively influenced the heavy metal concentrations in the surface water, although the concentrations of the ten kinds of tested

  7. Effect of traditional gold mining to surface water quality in Murung Raya District, Central Kalimantan Province

    Directory of Open Access Journals (Sweden)

    W.Wilopo

    2013-10-01

    Full Text Available There are many locations for traditional gold mining in Indonesia. One of these is in Murung Raya District, Central Kalimantan Province. Mining activities involving the application of traditional gold processing technology have a high potential to pollute the environment, especially surface water. Therefore, this study aims to determine the impact of gold mining and processing on surface water quality around the mine site. Based on the results of field surveys and laboratory analysis, our data shows that the concentration of mercury (Hg and Cyanide (CN has reached 0.3 mg/L and 1.9 mg/L, respectively, in surface water. These values exceed the drinking water quality standards of Indonesia and WHO. Many people who live in the mining area use surface water for daily purposes including drinking, cooking, bathing and washing. This scenario is very dangerous because the effect of surface water contamination on human health cannot be immediately recognized or diagnosed. In our opinion the dissemination of knowledge regarding the treatment of gold mining wastewater is urgently required so that the quality of wastewater can be improved before it is discharged into the environment.

  8. Effect of traditional gold mining to surface water quality in Murung Raya District, Central Kalimantan Province

    Directory of Open Access Journals (Sweden)

    W.Wilopo

    2013-10-01

    Full Text Available There are many locations for traditional gold mining in Indonesia. One of these is in Murung Raya District, Central Kalimantan Province. Mining activities involving the application of traditional gold processing technology have a high potential to pollute the environment, especially surface water. Therefore, this study aims to determine the impact of gold mining and processing on surface water quality around the mine site. Based on the results of field surveys and laboratory analysis, our data shows that the concentration of mercury (Hg and Cyanide (CN has reached 0.3 mg/L and 1.9 mg/L, respectively, in surface water. These values exceed the drinking water quality standards of Indonesia and WHO. Many people who live in the mining area use surface water for daily purposes including drinking, cooking, bathing and washing. This scenario is very dangerous because the effect of surface water contamination on human health cannot be immediately recognized or diagnosed. In our opinion the dissemination of knowledge regarding the treatment of gold mining wastewater is urgently required so that the quality of wastewater can be improved before it is discharged into the environment

  9. Bacteriophages as surface and ground water tracers

    Directory of Open Access Journals (Sweden)

    P. Rossi

    1998-01-01

    Full Text Available Bacteriophages are increasingly used as tracers for quantitative analysis in both hydrology and hydrogeology. The biological particles are neither toxic nor pathogenic for other living organisms as they penetrate only a specific bacterial host. They have many advantages over classical fluorescent tracers and offer the additional possibility of multi-point injection for tracer tests. Several years of research make them suitable for quantitative transport analysis and flow boundary delineation in both surface and ground waters, including karst, fractured and porous media aquifers. This article presents the effective application of bacteriophages based on their use in differing Swiss hydrological environments and compares their behaviour to conventional coloured dye or salt-type tracers. In surface water and karst aquifers, bacteriophages travel at about the same speed as the typically referenced fluorescent tracers (uranine, sulphurhodamine G extra. In aquifers of interstitial porosity, however, they appear to migrate more rapidly than fluorescent tracers, albeit with a significant reduction in their numbers within the porous media. This faster travel time implies that a modified rationale is needed for defining some ground water protection area boundaries. Further developments of other bacteriophages and their documentation as tracer methods should result in an accurate and efficient tracer tool that will be a proven alternative to conventional fluorescent dyes.

  10. Bacteriophages as surface and ground water tracers

    Science.gov (United States)

    Rossi, P.; Dörfliger, N.; Kennedy, K.; Müller, I.; Aragno, M.

    Bacteriophages are increasingly used as tracers for quantitative analysis in both hydrology and hydrogeology. The biological particles are neither toxic nor pathogenic for other living organisms as they penetrate only a specific bacterial host. They have many advantages over classical fluorescent tracers and offer the additional possibility of multi-point injection for tracer tests. Several years of research make them suitable for quantitative transport analysis and flow boundary delineation in both surface and ground waters, including karst, fractured and porous media aquifers. This article presents the effective application of bacteriophages based on their use in differing Swiss hydrological environments and compares their behaviour to conventional coloured dye or salt-type tracers. In surface water and karst aquifers, bacteriophages travel at about the same speed as the typically referenced fluorescent tracers (uranine, sulphurhodamine G extra). In aquifers of interstitial porosity, however, they appear to migrate more rapidly than fluorescent tracers, albeit with a significant reduction in their numbers within the porous media. This faster travel time implies that a modified rationale is needed for defining some ground water protection area boundaries. Further developments of other bacteriophages and their documentation as tracer methods should result in an accurate and efficient tracer tool that will be a proven alternative to conventional fluorescent dyes.

  11. Water droplet evaporation from sticky superhydrophobic surfaces

    Science.gov (United States)

    Lee, Moonchan; Kim, Wuseok; Lee, Sanghee; Baek, Seunghyeon; Yong, Kijung; Jeon, Sangmin

    2017-07-01

    The evaporation dynamics of water from sticky superhydrophobic surfaces was investigated using a quartz crystal microresonator and an optical microscope. Anodic aluminum oxide (AAO) layers with different pore sizes were directly fabricated onto quartz crystal substrates and hydrophobized via chemical modification. The resulting AAO layers exhibited hydrophobic or superhydrophobic characteristics with strong adhesion to water due to the presence of sealed air pockets inside the nanopores. After placing a water droplet on the AAO membranes, variations in the resonance frequency and Q-factor were measured throughout the evaporation process, which were related to changes in mass and viscous damping, respectively. It was found that droplet evaporation from a sticky superhydrophobic surface followed a constant contact radius (CCR) mode in the early stage of evaporation and a combination of CCR and constant contact angle modes without a Cassie-Wenzel transition in the final stage. Furthermore, AAO membranes with larger pore sizes exhibited longer evaporation times, which were attributed to evaporative cooling at the droplet interface.

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  13. Nitrate reducing activity pervades surface waters during upwelling.

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, S.O.; Halarnekar, R.; Malik, A.; Vijayan, V.; Varik, S.; RituKumari; Jineesh V.K.; Gauns, M.U.; Nair, S.; LokaBharathi, P.A.

    Nitrate reducing activity (NRA) is known to be mediated by microaerophilic to anaerobic bacteria and generally occurs in the sub-surface waters. However, we hypothesize that NRA could become prominent in the surface waters during upwelling. Hence...

  14. Wettability and water uptake of holm oak leaf surfaces

    OpenAIRE

    2014-01-01

    Plant trichomes play important protective functions and may have a major influence on leaf surface wettability. With the aim of gaining insight into trichome structure, composition and function in relation to water-plant surface interactions, we analyzed the adaxial and abaxial leaf surface of Quercus ilex L. (holm oak) as model. By measuring the leaf water potential 24 h after the deposition of water drops on to abaxial and adaxial surfaces, evidence for water penetration through the upper l...

  15. Groundwater–surface water interactions in wetlands for integrated water resources management (preface)

    NARCIS (Netherlands)

    Schot, P.P.; Winter, T.C.

    2006-01-01

    Groundwater–surface water interactions constitute an important link between wetlands and the surrounding catchment. Wetlands may develop in topographic lows where groundwater exfiltrates. This water has its functions for ecological processes within the wetland, while surface water outflow from

  16. General survey and conclusions with regard to the connection of water quantity and water quality studies of surface waters

    NARCIS (Netherlands)

    Rijtema, P.E.

    1979-01-01

    Publikatie die bestaat uit twee delen: 1. General survey of the relation between water quantity and water quality; 2. Conclusions with regard to the connection of water quantity and water quality studies of surface waters

  17. An Alternative to Precious Metals: Hg(ClO4)2·3H2O as a Cheap and Water-Tolerant Catalyst for the Cycloisomerization of Allenols.

    Science.gov (United States)

    Alcaide, Benito; Almendros, Pedro; Luna, Amparo; Soriano, Elena

    2015-07-17

    Hg(ClO4)2·3H2O, a cheap, water-tolerant, and stable salt, catalyzes the cycloisomerization reaction or α-allenols to 2,5-dihydrofurans in an efficient and selective manner. The reaction is general and can be applied to differently functionalized substrates, including alkyl-substituted, aryl-substituted, enantiopure, and tertiary allenols. In addition, density functional theory (DFT) calculations were performed to obtain insight into various aspects of the controlled reactivity of α-allenols under mercury catalysis. They suggest a dual activation of the allenol by the Hg complex that drives the reaction to the chemoselective formation of 2,5-dihydrofurans.

  18. Impact of Water Withdrawals from Groundwater and Surface Water on Continental Water Storage Variations

    Science.gov (United States)

    Doell, Petra; Hoffmann-Dobrev, Heike; Portmann, Felix T.; Siebert, Stefan; Eicker, Annette; Rodell, Matthew; Strassberg, Gil

    2011-01-01

    Humans have strongly impacted the global water cycle, not only water flows but also water storage. We have performed a first global-scale analysis of the impact of water withdrawals on water storage variations, using the global water resources and use model WaterGAP. This required estimation of fractions of total water withdrawals from groundwater, considering five water use sectors. According to our assessment, the source of 35% of the water withdrawn worldwide (4300 cubic km/yr during 1998-2002) is groundwater. Groundwater contributes 42%, 36% and 27% of water used for irrigation, households and manufacturing, respectively, while we assume that only surface water is used for livestock and for cooling of thermal power plants. Consumptive water use was 1400 cubic km/yr during 1998-2002. It is the sum of the net abstraction of 250 cubic km/yr of groundwater (taking into account evapotranspiration and return flows of withdrawn surface water and groundwater) and the net abstraction of 1150 km3/yr of surface water. Computed net abstractions indicate, for the first time at the global scale, where and when human water withdrawals decrease or increase groundwater or surface water storage. In regions with extensive surface water irrigation, such as Southern China, net abstractions from groundwater are negative, i.e. groundwater is recharged by irrigation. The opposite is true for areas dominated by groundwater irrigation, such as in the High Plains aquifer of the central USA, where net abstraction of surface water is negative because return flow of withdrawn groundwater recharges the surface water compartments. In intensively irrigated areas, the amplitude of seasonal total water storage variations is generally increased due to human water use; however, in some areas, it is decreased. For the High Plains aquifer and the whole Mississippi basin, modeled groundwater and total water storage variations were compared with estimates of groundwater storage variations based on

  19. Recovery from acidification in European surface waters

    Directory of Open Access Journals (Sweden)

    C. D. Evans

    2001-01-01

    Full Text Available Water quality data for 56 long-term monitoring sites in eight European countries are used to assess freshwater responses to reductions in acid deposition at a large spatial scale. In a consistent analysis of trends from 1980 onwards, the majority of surface waters (38 of 56 showed significant (p ≤0.05 decreasing trends in pollution-derived sulphate. Only two sites showed a significant increase. Nitrate, on the other hand, had a much weaker and more varied pattern, with no significant trend at 35 of 56 sites, decreases at some sites in Scandinavia and Central Europe, and increases at some sites in Italy and the UK. The general reduction in surface water acid anion concentrations has led to increases in acid neutralising capacity (significant at 27 of 56 sites but has also been offset in part by decreases in base cations, particularly calcium (significant at 26 of 56 sites, indicating that much of the improvement in runoff quality to date has been the result of decreasing ionic strength. Increases in acid neutralising capacity have been accompanied by increases in pH and decreases in aluminium, although fewer trends were significant (pH 19 of 56, aluminium 13 of 53. Increases in pH appear to have been limited in some areas by rising concentrations of organic acids. Within a general trend towards recovery, some inter-regional variation is evident, with recovery strongest in the Czech Republic and Slovakia, moderate in Scandinavia and the United Kingdom, and apparently weakest in Germany. Keywords: acidification, recovery, European trends, sulphate, nitrate, acid neutralising capacity

  20. Structured free-water clusters near lubricating surfaces are essential in water-based lubrication.

    Science.gov (United States)

    Hou, Jiapeng; Veeregowda, Deepak H; de Vries, Joop; Van der Mei, Henny C; Busscher, Henk J

    2016-10-01

    Water-based lubrication provides cheap and environmentally friendly lubrication and, although hydrophilic surfaces are preferred in water-based lubrication, often lubricating surfaces do not retain water molecules during shear. We show here that hydrophilic (42° water contact angle) quartz surfaces facilitate water-based lubrication to the same extent as more hydrophobic Si crystal surfaces (61°), while lubrication by hydrophilic Ge crystal surfaces (44°) is best. Thus surface hydrophilicity is not sufficient for water-based lubrication. Surface-thermodynamic analyses demonstrated that all surfaces, regardless of their water-based lubrication, were predominantly electron donating, implying water binding with their hydrogen groups. X-ray photoelectron spectroscopy showed that Ge crystal surfaces providing optimal lubrication consisted of a mixture of -O and =O functionalities, while Si crystal and quartz surfaces solely possessed -O functionalities. Comparison of infrared absorption bands of the crystals in water indicated fewer bound-water layers on hydrophilic Ge than on hydrophobic Si crystal surfaces, while absorption bands for free water on the Ge crystal surface indicated a much more pronounced presence of structured, free-water clusters near the Ge crystal than near Si crystal surfaces. Accordingly, we conclude that the presence of structured, free-water clusters is essential for water-based lubrication. The prevalence of structured water clusters can be regulated by adjusting the ratio between surface electron-donating and electron-accepting groups and between -O and =O functionalities.

  1. Potentially hazardous substances in surface waters. II. Cholinesterase inhibitors in Dutch surface waters

    NARCIS (Netherlands)

    Greve, P.A.; Freudenthal, J.; Wit, S.L.

    1972-01-01

    Several analytical methods were employed to determine the concentrations of cholinesterase inhibitors in several Dutch surface waters. An Auto-Analyzer method was used for screening purposes; thin-layer chromatography and gas-liquid chromatography-mass spectrometry were used for identification and q

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

    Data.gov (United States)

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

  3. Mother-embryo isotope (δ15N, δ13C) fractionation and mercury (Hg) transfer in aplacental deep-water sharks

    OpenAIRE

    Le Bourg, Baptiste; Kiszka, Jeremy; Bustamante, Paco

    2014-01-01

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

  4. Chemical thermodynamics of Hg1201 and Hg1223 phases

    Science.gov (United States)

    Tsuchiya, Tetsuo; Fueki, Kazuo; Koyama, Tadashi

    1998-03-01

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

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

    DEFF Research Database (Denmark)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2000-12-01

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

  7. Grooved organogel surfaces towards anisotropic sliding of water droplets.

    Science.gov (United States)

    Zhang, Pengchao; Liu, Hongliang; Meng, Jingxin; Yang, Gao; Liu, Xueli; Wang, Shutao; Jiang, Lei

    2014-05-21

    Periodic micro-grooved organogel surfaces can easily realize the anisotropic sliding of water droplets attributing to the formed slippery water/oil/solid interface. Different from the existing anisotropic surfaces, this novel surface provides a versatile candidate for the anisotropic sliding of water droplets and might present a promising way for the easy manipulation of liquid droplets for water collection, liquid-directional transportation, and microfluidics.

  8. Petroleum pollutant degradation by surface water microorganisms.

    Science.gov (United States)

    Antić, Malisa P; Jovancićević, Branimir S; Ilić, Mila; Vrvić, Miroslav M; Schwarzbauer, Jan

    2006-09-01

    It is well known that the composition of petroleum or some of its processing products changes in the environment mostly under the influence of microorganisms. A series of experiments was conducted in order to define the optimum conditions for an efficient biodegradation of petroleum pollutant, or bioremediation of different segments of the environment. The aim of these investigations was to show to what extent the hydrocarbons of a petroleum pollutant are degraded by microbial cultures which were isolated as dominant microorganisms from a surface water of a wastewater canal of an oil refinery and a nitrogen plant. Biodegradation experiments were conducted on one paraffinic, and one naphthenic type of petroleum during a three month period under aerobic conditions, varying the following parameters: Inorganic (Kp) or an organic medium (Bh) with or without exposition to light. Microorganisms were analyzed in a surface water sample from a canal (Pancevo, Serbia), into which wastewater from an oil refinery and a nitrogen plant is released. The consortia of microorganisms were isolated from the water sample (most abundant species: Phormidium foveolarum--filamentous Cyanobacteria, blue-green algae and Achanthes minutissima, diatoms, algae). The simulation experiments of biodegradation were conducted with the biomass suspension and crude oils Sirakovo (Sir, paraffinic type) and Velebit (Ve, naphthenic type). After a three month period, organic substance was extracted by means of chloroform. In the extracts, the content of saturated hydrocarbons, aromatic hydrocarbons, alcohols and fatty acids was determined (the group composition). n-Alkanes and isoprenoid aliphatic alkanes, pristane and phytane, in the aliphatic fractions, were analyzed using gas chromatography (GC). Total isoprenoid aliphatic alkanes and polycyclic alkanes of sterane and triterpane types were analyzed by GC-MS. Paraffinic type petroleums have a significant loss of saturated hydrocarbons. For naphthenic

  9. Atmospheric Water Harvesting: Role of Surface Wettability and Edge Effect

    KAUST Repository

    Jin, Yong

    2017-06-23

    Atmospheric water is emerging as an important potable water source. The present work experimentally and theoretically investigates water condensation and collection on flat surfaces with contrasting contact angles and contact angle hysteresis (CAH) to elucidate their roles on water mass collection efficiency. The experimental results indicate that a hydrophilic surface promotes nucleation and individual droplets growth, and a surface with a low CAH tends to let a smaller droplet to slide down, but the overall water mass collection efficiency is independent of both surface contact angle and CAH. The experimental results agree well with our theoretical calculations. During water condensation, a balance has to be struck between single droplet growth and droplet density on a surface so as to maintain a constant water droplet surface coverage ratio, which renders the role of both surface wettability and hysteresis insignificant to the ultimate water mass collection. Moreover, water droplets on the edges of a surface grow much faster than those on the non-edge areas and thus dominate the contribution to the water mass collection by the entire surface, directly pointing out the very important role of edge effect on water condensation and collection.

  10. Adsorbed water on iron surface by molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, F.W.; Campos, T.M.B.; Cividanes, L.S., E-mail: flaviano@ita.br; Simonetti, E.A.N.; Thim, G.P.

    2016-01-30

    Graphical abstract: - Highlights: • We developed a new force field to describe the Fe–H{sub 2}O interaction. • We developed a new force field to describe the flexible water model at low temperature. • We analyze the orientation of water along the iron surface. • We calculate the vibrational spectra of water near the iron surface. • We found a complex relationship between water orientation and the atomic vibrational spectra at different sites of adsorption along the iron surface. - Abstract: The adsorption of H{sub 2}O molecules on metal surfaces is important to understand the early process of water corrosion. This process can be described by computational simulation using molecular dynamics and Monte Carlo. However, this simulation demands an efficient description of the surface interactions between the water molecule and the metallic surface. In this study, an effective force field to describe the iron-water surface interactions was developed and it was used in a molecular dynamics simulation. The results showed a very good agreement between the simulated vibrational-DOS spectrum and the experimental vibrational spectrum of the iron–water interface. The water density profile revealed the presence of a water double layer in the metal interface. Furthermore, the horizontal mapping combined with the angular distribution of the molecular plane allowed the analysis of the water structure above the surface, which in turn agrees with the model of the double layer on metal surfaces.

  11. 40 CFR 258.27 - Surface water requirements.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Surface water requirements. 258.27... FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.27 Surface water requirements. MSWLF... wetlands, that violates any requirements of the Clean Water Act, including, but not limited to,...

  12. Floating Vegetated Mats For Improving Surface Water Quality

    Science.gov (United States)

    Contamination of surface and ground waters is an environmental concern. Pollution from both point and nonpoint sources can render water unsuitable for use. Surface waters of concern include streams, rivers, ponds, lakes, canals, and wastewater lagoons. Lagooned wastewater from confined animal feedi...

  13. Validation of the methodology for determining As, Sb, Hg, and Se in the water supply in Tudela, Navarra, spain, by atomic absorption; Validacion de la metodologia para la determinacion de As, Sb, Hg, y Se en aguas de abastecimiento a Tudela (Navarra) por absorcion atomica

    Energy Technology Data Exchange (ETDEWEB)

    Gale, M. A.; Cebrian, N.; Ormad, P.; Ovelleiro, J. L.

    2002-07-01

    In compliance with the current regulations on water quality, an analytical methodology has been put in place in the laboratory of the waste water treatment plant in Tudela, Navarre (Spain) to monitor As, Sb, Hg, and Se in the water going into the public water supply. The technique used to monitor these elements is atomic absorption spectrometry, As, Sb, Se are determined by the generation of hydrides and Hg by the generation of cold vapour. In addition, in order to ensure the authenticity of the results, the methodology employed has been validated by a study of the following technical characteristics: linearity, work interval, sensitivity, precision and accuracy. Extremely satisfactory results were obtained in all cases. A linear range between 0 and 1000 mg/l for all four elements and extremely low detection and quantification limits (less than 1 mg/l) were found. In the study of the method's accuracy, the C. V. s were below the legally established minima and the method was found to be very accurate. (Author) 18 refs.

  14. Lithium content in potable water, surface water, ground water, and mineral water on the territory of Republic of Macedonia

    Directory of Open Access Journals (Sweden)

    Vesna Kostik

    2014-07-01

    Full Text Available The aim of this study was to determine lithium concentration in potable water, surface water, ground, and mineral water on the territory of the Republic of Macedonia. Water samples were collected from water bodies such as multiple public water supply systems located in 13 cities, wells boreholes located in 12 areas, lakes and rivers located in three different areas. Determination of lithium concentration in potable water, surface water was performed by the technique of inductively coupled plasma-mass spectrometry, while in ground water samples from wells boreholes and mineral waters with the technique of ion chromatography. The research shows that lithium concentration in potable water ranging from 0.1 to 5.2 μg/L; in surface water from 0.5 to 15.0 μg/L; ground water from wells boreholes from 16.0 to 49.1 μg/L and mineral water from 125.2 to 484.9 μg/L. Obtained values are in accordance with the relevant international values for the lithium content in water.

  15. SURFACE RECOMBINATION VELOCITY OF THE HgCdTe SURFACE PASSIVATED WITH SPUTTERING CdTe FILM%CdTe钝化的HgCdTe非平衡载流子表面复合速度的实验研究

    Institute of Scientific and Technical Information of China (English)

    周咏东; 赵军; 龚海梅; 李言谨; 方家熊

    2000-01-01

    利用Ar+束溅射沉积技术在HgCdTe表面实现了低温CdTe介质薄膜的低温生长.在同一HgCdTe晶片表面分别用CdTe介质膜、HgCdTe自身阳极氧化膜进行表面钝化.利用光电导衰退测量技术测量了两种不同表面钝化的薄HgCdTe晶片的非平衡载流子(少数载流子)寿命,并通过光电导衰减信号波形的拟合,得到两种不同表面钝化的HgCdTe表面复合速度.实验结果表明,获得的CdTe/HgCdTe界面质量已超过了成熟的自身阳极氧化膜/HgCdTe界面质量水平.

  16. The impact of municipal landfill on surface and ground water quality in Bulawayo, Zimbabwe

    Directory of Open Access Journals (Sweden)

    R. Nyengera

    2012-11-01

    Full Text Available Leachate from Richmond municipal landfill, underlain by the Matsheumhlope unconfined aquifer in Bulawayo city and its consequent water resource quality impacts are evaluated. Leachate samples from collection ponds and water samples from a stream, and up and down-gradient boreholes fromthe landfill were tested for nine pollutants. The leachate pollutants found in both surface and ground water included metals (Fe, Pb and Hg and organic compounds that are hazardous to both human and the environmental health. Borehole water quality compliance with the relevant national and international regulations is reported. From borehole water samples, only chloride and nitrate with concentrations of 56.9 mg/ℓ and 2.26 mg/ℓ, respectively, were within the World Health Organisation (WHO recommended limits for drinking water of 250 mg/ℓ and 10 mg/ℓ, respectively. Lead and mercury concentrations of 0.22 mg/ℓ and 0.04 mg/ℓ were 10 times higher than WHO guidelines of 0.01 and 0.001 mg/ℓ, respectively. Both landfill and informal settlement activities near the landfill impact negatively to water resources quality in the area. City council should minimize waste by recycling, pre-treat collected leachate and drill monitoring wells around the landfill to check possible leachate leaks to water resources and take remedial actions, such assubmerged leachate combustion and evaporation.

  17. How to repel hot water from a superhydrophobic surface?

    KAUST Repository

    Yu, Zhejun

    2014-01-01

    Superhydrophobic surfaces, with water contact angles greater than 150° and slide angles less than 10°, have attracted a great deal of attention due to their self-cleaning ability and excellent water-repellency. It is commonly accepted that a superhydrophobic surface loses its superhydrophobicity in contact with water hotter than 50 °C. Such a phenomenon was recently demonstrated by Liu et al. [J. Mater. Chem., 2009, 19, 5602], using both natural lotus leaf and artificial leaf-like surfaces. However, our work has shown that superhydrophobic surfaces maintained their superhydrophobicity, even in water at 80 °C, provided that the leaf temperature is greater than that of the water droplet. In this paper, we report on the wettability of water droplets on superhydrophobic thin films, as a function of both their temperatures. The results have shown that both the water contact and slide angles on the surfaces will remain unchanged when the temperature of the water droplet is greater than that of the surface. The water contact angle, or the slide angle, will decrease or increase, however, with droplet temperatures increasingly greater than that of the surfaces. We propose that, in such cases, the loss of superhydrophobicity of the surfaces is caused by evaporation of the hot water molecules and their condensation on the cooler surface. © 2014 the Partner Organisations.

  18. Exchange flux of total gaseous mercury between air and natural water surfaces in summer season

    Institute of Scientific and Technical Information of China (English)

    FENG; Xinbin; (冯新斌); Jonas; Sommar; Katarina; Gordfeldt; Oliver; Lindqvist

    2002-01-01

    The exchanges of mercury between surface and air are of significance in the biogeochemical cycling of Hg in the environment, but there are still few reliable data on air/surface exchange in aquatic systems. Field measurement campaigns over seawater surface at Kristineberg Marine Research Station (KMRS) and over Hovg?rds?n River surface at Knobesholm in southwestern Sweden were conducted to measure mercury flux using a dynamic flux chamber technique coupled with automatic mercury vapor-phase analyzers. Both sites show net emissions during summer time. Mercury fluxes measured over both river and seawater surfaces exhibit a consistently diurnal pattern with maximum fluxes during the daytime period and minimum fluxes during the nighttime period. At freshwater site, mercury flux is strongly correlated with the intensity of net solar radiation, and negatively correlated with relative humidity. A typical exponential relationship between mercury flux and water temperature was observed at freshwater measurement site. At seawater site, a strong correlation between mercury flux and intensity of solar radiation was obtained. The driving force of mercury emission from water surface to air is the super-saturation of dissolved gaseous mercury in aqueous phase.

  19. Structure and reactivity of water at biomaterial surfaces.

    Science.gov (United States)

    Vogler, E A

    1998-02-01

    Molecular self association in liquids is a physical process that can dominate cohesion (interfacial tension) and miscibility. In water, self association is a powerful organizational force leading to a three-dimensional hydrogen-bonded network (water structure). Localized perturbations in the chemical potential of water as by, for example, contact with a solid surface, induces compensating changes in water structure that can be sensed tens of nanometers from the point of origin using the surface force apparatus (SFA) and ancillary techniques. These instruments reveal attractive or repulsive forces between opposing surfaces immersed in water, over and above that anticipated by continuum theory (DLVO), that are attributed to a variable density (partial molar volume) of a more-or-less ordered water structure, depending on the water wettability (surface energy) of the water-contacting surfaces. Water structure at surfaces is thus found to be a manifestation of hydrophobicity and, while mechanistic/theoretical interpretation of experimental results remain the subject of some debate in the literature, convergence of experimental observations permit, for the first time, quantitative definition of the relative terms 'hydrophobic' and 'hydrophilic'. In particular, long-range attractive forces are detected only between surfaces exhibiting a water contact angle theta > 65 degrees (herein defined as hydrophobic surfaces with pure water adhesion tension tau O = gamma O cos theta 30 dyn/cm). These findings suggest at least two distinct kinds of water structure and reactivity: a relatively less-dense water region against hydrophobic surfaces with an open hydrogen-bonded network and a relatively more-dense water region against hydrophilic surfaces with a collapsed hydrogen-bonded network. Importantly, membrane and SFA studies reveal a discrimination between biologically-important ions that preferentially solubilizes divalent ions in more-dense water regions relative to less

  20. Distribution of {sup 129}I in terrestrial surface water environments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xuegao [State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098 (China); College of Hydrology and Water Resources, Hohai University, Nanjing (China); Gong, Meng [College of Hydrology and Water Resources, Hohai University, Nanjing (China); Yi, Peng, E-mail: pengyi1915@163.com [State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098 (China); College of Hydrology and Water Resources, Hohai University, Nanjing (China); Aldahan, Ala [Department of Earth Sciences, Uppsala University, Uppsala (Sweden); Department of Geology, United Arab Emirates University, Al Ain (United Arab Emirates); Yu, Zhongbo [State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098 (China); College of Hydrology and Water Resources, Hohai University, Nanjing (China); Possnert, Göran [Tandem Laboratory, Uppsala University, Uppsala (Sweden); Chen, Li [State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098 (China); College of Hydrology and Water Resources, Hohai University, Nanjing (China)

    2015-10-15

    The global distribution of the radioactive isotope iodine-129 in surface waters (lakes and rivers) is presented here and compared with the atmospheric deposition and distribution in surface marine waters. The results indicate relatively high concentrations in surface water systems in close vicinity of the anthropogenic release sources as well as in parts of Western Europe, North America and Central Asia. {sup 129}I level is generally higher in the terrestrial surface water of the Northern hemisphere compared to the southern hemisphere. The highest values of {sup 129}I appear around 50°N and 40°S in the northern and southern hemisphere, separately. Direct gaseous and marine atmospheric emissions are the most likely avenues for the transport of {sup 129}I from the sources to the terrestrial surface waters. To apply iodine-129 as process tracer in terrestrial surface water environment, more data are needed on {sup 129}I distribution patterns both locally and globally.

  1. Water content distribution in the surface layer of Maoping slope

    Institute of Scientific and Technical Information of China (English)

    LIU Yuewu; CHEN Huixin; LIU Qingquan; GONG Xin; ZHANG Dawei; LI Lianxiang

    2005-01-01

    The water content distribution in the surface layer of Maoping slope has been studied by testing the water content at 31 control sites. The water content profiles at these sites have also been determined. The water content distributions at different segments have been obtained by using the Kriging method of geostatistics. By comparing the water content distributions with the landform of the slope, it was shown that the water content is closely dependent on the landform of the slope. The water content distribution in the surface layer provided a fundamental basis for landslide predication and treatment.

  2. Section 11: Surface Water Pathway - Likelihood of Release

    Science.gov (United States)

    Surface water releases can include the threat to targets from overland flow of hazardous substances and from flooding or the threat from the release of hazardous substances to ground water and the subsequent discharge of contaminated ground w

  3. 氢化物发生ICP-AES法同时测定纯净水中的砷和汞%Simultaneous Determination of Arsenic and Mercury in Purified Water by HG-ICP-AES

    Institute of Scientific and Technical Information of China (English)

    黄志; 刘英萍; 张宏

    2001-01-01

    本文建立了氢化物发生ICP-AES法同时测定纯净水中砷和汞的方法。检出限分别为As 1.7μg/L、Hg 0.1μg/L,方法精密度(RSD)为As 3.46%、Hg 2.85%,回收率为As 92%—110%、Hg 90%—113%。%A HG-ICP-AES method for simultaneous determination of arsenic and mercury in purified water is proposed.The detection limit of arsenic and mercury is 1.7μg/L and 0.1μg/L respectively.The RSD for arsenic is 3.46% and for mercury is 2.85%.The recovery for arsenic is in the range of 92%—110% and for mercury is in the range of 90%—113%.

  4. Biofilm development on metal surfaces in tropical marine waters

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, F.P.; Bhosle, N.B.

    environments. However, little is known about biofilm bacteria developed on metal surfaces, especially immersed in tropical marine waters. Similarly, not much is known about the nature of organic matter deposited on the surfaces over the period of immersion...

  5. The glass-liquid transition of water on hydrophobic surfaces.

    Science.gov (United States)

    Souda, Ryutaro

    2008-09-28

    Interactions of thin water films with surfaces of graphite and vitrified room-temperature ionic liquid [1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)])] were investigated using time-of-flight secondary ion mass spectrometry as a function of temperature and annealing time to elucidate the glass-liquid transition of water at the molecular level. Surface diffusion of water occurs at temperatures higher than 120 K, thereby forming three-dimensional clusters (a two-dimensional layer) on the [bmim][PF(6)] (graphite) surface. The hydrophobic effect of the surface decreases with increasing coverage of water; the bulklike properties evolve up to 40 ML, as evidenced by the occurrence of film dewetting at around the conventional glass transition temperature (140 K). Results also showed that aging is necessary for the water monolayer (a 40 ML water film) to dewet the graphite ([bmim][PF(6)]) surface. The occurrence of aging is explainable by the successive evolution of two distinct liquids during the glass-liquid transition: low density liquid is followed by supercooled liquid water. The water monolayer on graphite is characterized by the preferred orientation of unpaired OH groups toward the surface; this structure is arrested during the aging time despite the occurrence of surface diffusion. However, the water monolayer formed on the [bmim][PF(6)] surface agglomerates immediately after the commencement of surface diffusion. The structure of low density liquid tends to be arrested by the attractive interaction with the neighbors.

  6. Conjunctive Surface Water and Groundwater Management under Climate Change

    Directory of Open Access Journals (Sweden)

    Xiaodong eZhang

    2015-09-01

    Full Text Available Climate change can result in significant impacts on regional and global surface water and groundwater resources. Using groundwater as a complimentary source of water has provided an effective means to satisfy the ever-increasing water demands and deal with surface water shortages problems due to robust capability of groundwater in responding to climate change. Conjunctive use of surface water and groundwater is crucial for integrated water resources management. It is helpful to reduce vulnerabilities of water supply systems and mitigate the water supply stress in responding to climate change. Some critical challenges and perspectives are discussed to help decision/policy makers develop more effective management and adaptation strategies for conjunctive water resources use in facing climate change under complex uncertainties.

  7. Spreading of Cholera through Surface Water

    Science.gov (United States)

    Bertuzzo, E.; Casagrandi, R.; Gatto, M.; Rodriguez-Iturbe, I.; Rinaldo, A.

    2009-12-01

    Cholera epidemics are still a major public health concern to date in many areas of the world. In order to understand and forecast cholera outbreaks, one of the most important factors is the role played by the environmental matrix in which the disease spreads. We study how river networks, acting as environmental corridors for pathogens, affect the spreading of cholera epidemics. The environmental matrix in which the disease spreads is constituted by different human communities and their hydrologic interconnections. Each community is characterized by its spatial position, population size, water resources availability and hygiene conditions. By implementing a spatially explicit cholera model we seek the effects on epidemic dynamics of: i) the topology and metrics of the pathogens pathways that connect different communities; ii) the spatial distribution of the population size; and iii) the spatial distributions and quality of surface water resources and public health conditions, and how they vary with population size. The model has been applied to study the space-time evolution of a well documented cholera epidemic occurred in the KwaZulu-Natal province of South Africa. The epidemic lasted for two years and involved about 140,000 confirmed cholera cases. The model does well in reproducing the distribution of the cholera cases during the two outbreaks as well as their spatial spreading. We further extend the model by deriving the speed of propagation of traveling fronts in the case of uniformly distributed systems for different topologies: one and two dimensional lattices and river networks. The derivation of the spreading celerity proves instrumental in establishing the overall conditions for the relevance of spatially explicit models. The conditions are sought by comparison between spreading and disease timescales. Consider a cholera epidemic that starts from a point and spreads throughout a finite size system, it is possible to identify two different timescales: i

  8. Region 9 Surface Water Intakes (SDWIS)

    Data.gov (United States)

    U.S. Environmental Protection Agency — EPAâ??s Safe Drinking Water Information System (SDWIS) databases store information about drinking water. The federal version (SDWIS/FED) stores the information EPA...

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

    Science.gov (United States)

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

    2014-01-01

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

  10. COMMUNITY PARTICIPATION IN SURFACE WATER HARVESTING ...

    African Journals Online (AJOL)

    USER

    2014-11-25

    Nov 25, 2014 ... There is seasonal water scarcity in Marigat Division and the water demand has been ... with improved storage and rainwater harvesting methods. Such water can be ..... in the planning process and decision making and this ... The organizations support the community ... systems for domestic uses in urban.

  11. An ontology design pattern for surface water features

    Science.gov (United States)

    Sinha, Gaurav; Mark, David; Kolas, Dave; Varanka, Dalia; Romero, Boleslo E.; Feng, Chen-Chieh; Usery, E. Lynn; Liebermann, Joshua; Sorokine, Alexandre

    2014-01-01

    Surface water is a primary concept of human experience but concepts are captured in cultures and languages in many different ways. Still, many commonalities exist due to the physical basis of many of the properties and categories. An abstract ontology of surface water features based only on those physical properties of landscape features has the best potential for serving as a foundational domain ontology for other more context-dependent ontologies. The Surface Water ontology design pattern was developed both for domain knowledge distillation and to serve as a conceptual building-block for more complex or specialized surface water ontologies. A fundamental distinction is made in this ontology between landscape features that act as containers (e.g., stream channels, basins) and the bodies of water (e.g., rivers, lakes) that occupy those containers. Concave (container) landforms semantics are specified in a Dry module and the semantics of contained bodies of water in a Wet module. The pattern is implemented in OWL, but Description Logic axioms and a detailed explanation is provided in this paper. The OWL ontology will be an important contribution to Semantic Web vocabulary for annotating surface water feature datasets. Also provided is a discussion of why there is a need to complement the pattern with other ontologies, especially the previously developed Surface Network pattern. Finally, the practical value of the pattern in semantic querying of surface water datasets is illustrated through an annotated geospatial dataset and sample queries using the classes of the Surface Water pattern.

  12. Adsorption mechanism of water molecule on goethite (010) surface

    Science.gov (United States)

    Xiu, Fangyuan; Zhou, Long; Xia, Shuwei; Yu, Liangmin

    2016-12-01

    Goethite widely exists among ocean sediments; it plays an important role in fixing heavy metals and adsorbing organic contaminants. So the understanding of the adsorbing process of water molecule on its surface will be very helpful to further reveal such environmental friendly processes. The configuration, electronic properties and interaction energy of water molecules adsorbed on pnma goethite (010) surface were investigated in detail by using density functional theory on 6-31G (d,p) basis set and projector- augment wave (PAW) method. The mechanism of the interaction between goethite surface and H2O was proposed. Despite the differences in total energy, there are four possible types of water molecule adsorption configurations on goethite (010) surface (Aa, Ab, Ba, Bb), forming coordination bond with surface Fe atom. Results of theoretical modeling indicate that the dissociation process of adsorbed water is an endothermic reaction with high activation energy. The dissociation of adsorbed water molecule is a proton transportation process between water's O atoms and surface. PDOS results indicate that the bonding between H2O and (010) surface is due to the overlapping of water's 2p orbitals and Fe's 3d orbitals. These results clarify the mechanism on how adsorbed water is dissociated on the surface of goethite and potentially provide useful information of the surface chemistry of goethite.

  13. Infiltration of pesticides in surface water into nearby drinking water supply wells

    DEFF Research Database (Denmark)

    Malaguerra, Flavio; Albrechtsen, Hans-Jørgen; Binning, Philip John

    Drinking water wells are often placed near streams because streams often overly permeable sediments and the water table is near the surface in valleys, and so pumping costs are reduced. The lowering of the water table by pumping wells can reverse the natural flow from the groundwater to the stream......, inducing infiltration of surface water to groundwater and consequently to the drinking water well. Many attenuation processes can take place in the riparian zone, mainly due to mixing, biodegradation and sorption. However, if the water travel time from the surface water to the pumping well is too short......, or if the compounds are poorly degradable, contaminants can reach the drinking water well at high concentrations, jeopardizing drinking water quality. Here we developed a reactive transport model to evaluate the risk of contamination of drinking water wells by surface water pollution. The model was validated using...

  14. Simulation of water cluster assembly on a graphite surface.

    Science.gov (United States)

    Lin, C S; Zhang, R Q; Lee, S T; Elstner, M; Frauenheim, Th; Wan, L J

    2005-07-28

    The assembly of small water clusters (H2O)n, n = 1-6, on a graphite surface is studied using a density functional tight-binding method complemented with an empirical van der Waals force correction, with confirmation using second-order Møller-Plesset perturbation theory. It is shown that the optimized geometry of the water hexamer may change its original structure to an isoenergy one when interacting with a graphite surface in some specific orientation, while the smaller water cluster will maintain its cyclic or linear configurations (for the water dimer). The binding energy of water clusters interacting with graphite is dependent on the number of water molecules that form hydrogen bonds, but is independent of the water cluster size. These physically adsorbed water clusters show little change in their IR peak position and leave an almost perfect graphite surface.

  15. Lithography process for patterning HgI2 photonic devices

    Science.gov (United States)

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

    2004-11-23

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

  16. Effects of HgCl2 stress on the upper leaf necroses and water use efficiency of oriental hybrid lilies%HgCl2胁迫对东方百合叶烧指数和水分利用效率的影响

    Institute of Scientific and Technical Information of China (English)

    杨爽; 袁晓娜; 王中轩; 祝璞; 贾桂霞

    2016-01-01

    东方百合部分品种在冬季栽培中极易发生叶烧,成为影响百合切花和盆花质量的主要因素之一。叶烧的发生与水分代谢有关,为探寻百合叶烧的发生是否和水通道蛋白相关,本文采用3种不同浓度的水通道蛋白抑制剂HgCl2(50、100和200μmol/L),对叶烧敏感程度不同的2个东方百合品种进行灌根处理,结果表明:随着HgCl2浓度增加,‘Sorbonne '的叶烧指数分别比对照增加了13.56%、36.06%和42.19%;‘Siberia '分别比对照增加了7.20%、12.15%和18.00%。‘Sorbonne'和‘Siberia'的株高、茎粗、叶面积、茎生根长度、茎生根厚度和根系活力、净光合速率和蒸腾速率都受到了不同程度的抑制。其中,HgCl2处理对根系活力的抑制作用最大,3种不同浓度的HgCl2处理后‘Sorbonne'的根系活力分别比对照降低了41.9%、54.7%和67.5%;‘Siberia'的根系活力分别比对照降低了4.8%、33.5%和38.2%。从水分利用效率情况来看,随着HgCl2浓度增加,‘Sorbonne'的水分利用效率分别比对照降低了14.00%、19.23%和46.06%;‘Siberia '的水分利用效率分别比对照降低了8.62%、17.60%和28.71%。由此可知,不同浓度HgCl2胁迫处理抑制了‘Sorbonne'和‘Siberia'的水分运输,显著增加了植物叶烧指数,初步推测百合叶烧发生的程度与植物水通道蛋白的表达有一定的相关性。%Some of the oriental hybrid lily cultivars are prone to upper leaf necrosis ( ULN) , which has become a major threat to the quality of cut and pot lilies. The ULN of oriental lily is believed to relate with water metabolism. In order to explore the relationship between ULN of lilies and the aquaporin, we used three different concentrations of aquaporin inhibitor HgCl2 ( 50, 100 and 200 μmol/L ) to irrigate two lily cultivars which are different in sensitivity to ULN. The result showed that with the increasing concentrations of HgCl2 , the ULN indexes of the cultivar

  17. Surface Curvature-Induced Directional Movement of Water Droplets

    CERN Document Server

    Lv, Cunjing; Yin, Yajun; Zheng, Quanshui

    2010-01-01

    Here we report a surface curvature-induced directional movement phenomenon, based on molecular dynamics simulations, that a nanoscale water droplet at the outer surface of a graphene cone always spontaneously moves toward the larger end of the cone, and at the inner surface toward the smaller end. The analysis on the van der Waals interaction potential between a single water molecule and a curved graphene surface reveals that the curvature with its gradient does generate the driving force resulting in the above directional motion. Furthermore, we found that the direction of the above movement is independent of the wettability, namely is regardless of either hydrophobic or hydrophilic of the surface. However, the latter surface is in general leading to higher motion speed than the former. The above results provide a basis for a better understanding of many reported observations, and helping design of curved surfaces with desired directional surface water transportation.

  18. Sampling procedure for lake or stream surface water chemistry

    Science.gov (United States)

    Robert Musselman

    2012-01-01

    Surface waters collected in the field for chemical analyses are easily contaminated. This research note presents a step-by-step detailed description of how to avoid sample contamination when field collecting, processing, and transporting surface water samples for laboratory analysis.

  19. Models of Fate and Transport of Pollutants in Surface Waters

    Science.gov (United States)

    Okome, Gloria Eloho

    2013-01-01

    There is the need to answer very crucial questions of "what happens to pollutants in surface waters?" This question must be answered to determine the factors controlling fate and transport of chemicals and their evolutionary state in surface waters. Monitoring and experimental methods are used in establishing the environmental states.…

  20. Models of Fate and Transport of Pollutants in Surface Waters

    Science.gov (United States)

    Okome, Gloria Eloho

    2013-01-01

    There is the need to answer very crucial questions of "what happens to pollutants in surface waters?" This question must be answered to determine the factors controlling fate and transport of chemicals and their evolutionary state in surface waters. Monitoring and experimental methods are used in establishing the environmental states.…

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-07

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

  2. Shallow Water Propagation and Surface Reverberation Modeling

    Science.gov (United States)

    2014-07-29

    term goals were to 1. exploit measurements of breaking wave noise and photographic images of whitecaps to infer bubble cloud populations at the sea ...surface reverberation in wind-driven seas , an additional objective has been to study the role of sub-surface bubbles on the attenuation and scattering of...acoustic signals, including determining methods for quantifying bubble populations with video footage of the sea surface and developing models of

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

    Science.gov (United States)

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

    2001-12-01

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

  4. Sources of mercury in surface waters of the upper Madeira erosive basins, Bolivia

    Science.gov (United States)

    Maurice-Bourgoin, L.; Alanoca, L.; Fraizy, P.; Vauchel, P.

    2003-05-01

    The human activities impact on the mercury (Hg) distribution in the Amazon waters is still discussed but very few information regarding the Hg sources from the highly turbid Andean headwaters have been published. The annualload of suspended sediments eroded from the Bolivian Andes, averages 300 10^6 tons in the Beni river, of which till 97% is exported during the rainy season. At the edge of the Bolivian Andean piedmont, the total Hg concentration vary from 8 ng l^{-1} during the dry season, to 1600 ng l^{-1} during the high water period [1]. During this stage, it appears that the maximum concentrations of Hg associated with the fine particles and the highest Hg specific fluxes are observed in the rivers exploited for their alluvial gold during the last century. The black-shales series associated to the gold deposits are characterised by high natural Hg contents, which can be released in the hydrographic system by both chemical and physical weathering. But if we compare two clear water rivers characterised by the same suspended sediment concentrations, the maximum specific Hg flux varies between 126 kg km^{-2} j^{-1} in the pristine river, to 590 kg km^{-2} j^{-1} in the river characterised by recent human activities.

  5. Water-Mediated Interactions between Hydrophilic and Hydrophobic Surfaces.

    Science.gov (United States)

    Kanduč, Matej; Schlaich, Alexander; Schneck, Emanuel; Netz, Roland R

    2016-09-01

    All surfaces in water experience at short separations hydration repulsion or hydrophobic attraction, depending on the surface polarity. These interactions dominate the more long-ranged electrostatic and van der Waals interactions and are ubiquitous in biological and colloidal systems. Despite their importance in all scenarios where the surface separation is in the nanometer range, the origin of these hydration interactions is still unclear. Using atomistic solvent-explicit molecular dynamics simulations, we analyze the interaction free energies of charge-neutral model surfaces with different elastic and water-binding properties. The surface polarity is shown to be the most important parameter that not only determines the hydration properties and thereby the water contact angle of a single surface but also the surface-surface interaction and whether two surfaces attract or repel. Elastic properties of the surfaces are less important. On the basis of surface contact angles and surface-surface binding affinities, we construct a universal interaction diagram featuring three different interaction regimes-hydration repulsion, cavitation-induced attraction-and for intermediate surface polarities-dry adhesion. On the basis of scaling arguments and perturbation theory, we establish simple combination rules that predict the interaction behavior for combinations of dissimilar surfaces.

  6. Surface water quality assessment by environmetric methods.

    Science.gov (United States)

    Boyacioglu, Hülya; Boyacioglu, Hayal

    2007-08-01

    This environmetric study deals with the interpretation of river water monitoring data from the basin of the Buyuk Menderes River and its tributaries in Turkey. Eleven variables were measured to estimate water quality at 17 sampling sites. Factor analysis was applied to explain the correlations between the observations in terms of underlying factors. Results revealed that, water quality was strongly affected from agricultural uses. Cluster analysis was used to classify stations with similar properties and results distinguished three groups of stations. Water quality at downstream of the river was quite different from the other part. It is recommended to involve the environmetric data treatment as a substantial procedure in assessment of water quality data.

  7. 40 CFR 257.3-3 - Surface water.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Surface water. 257.3-3 Section 257.3-3... and Practices § 257.3-3 Surface water. (a) For purposes of section 4004(a) of the Act, a facility... Water Act, as amended. (b) For purposes of section 4004(a) of the Act, a facility shall not cause...

  8. Preliminary monitoring of faecal indicator organisms of surface water ...

    African Journals Online (AJOL)

    Preliminary monitoring of faecal indicator organisms of surface water: A case study ... in Mvudi River used as a source of domestic water for people who live around it. ... of Water Affairs and Forestry of South Africa (DWAF) and the World Health ...

  9. First-principles study on magnetism and half-metallicity in bulk and various (001) surfaces of Heusler alloy Zr2VSn with Hg2CuTi-type structure

    Science.gov (United States)

    Deng, Zun-Yi; Zhang, Jian-Min

    2016-07-01

    Structural, electronic and magnetic properties in the bulk and five different (001) surfaces (ZrV-, ZrSn-, VV-, ZrZr- and SnSn-terminations) of Zr2 VSn Heusler alloy with Hg2 CuTi -type structure are studied by using first-principles calculations based on density-functional theory. The bulk Zr2 VSn Heusler alloy is ferrimagnetic half-metallicity with equilibrium lattice constant 6.815 Å and total magnetic moment -1.000 μB / f.u . , following the Slater-Pauling rule μt =Zt - 18 . The atoms on different surface layers exhibit different displacements, electronic and magnetic properties. All five (001) surfaces lose the half-metallicity and are not usable in spintronics devices.

  10. Layers of Porous Superhydrophobic Surfaces for Robust Water Repellency

    Science.gov (United States)

    Ahmadi, Farzad; Boreyko, Jonathan; Nature-Inspired Fluids; Interfaces Team

    2015-11-01

    In nature, birds exhibit multiple layers of superhydrophobic feathers that repel water. Inspired by bird feathers, we utilize porous superhydrophobic surfaces and compare the wetting and dewetting characteristics of a single surface to stacks of multiple surfaces. The superhydrophobic surfaces were submerged in water in a closed chamber. Pressurized gas was regulated to measure the critical pressure for the water to fully penetrate through the surfaces. In addition to using duck feathers, two-tier porous superhydrophobic surfaces were fabricated to serve as synthetic mimics with a controlled surface structure. The energy barrier for the wetting transition was modeled as a function of the number of layers and their orientations with respect to each other. Moreover, after partial impalement into a subset of the superhydrophobic layers, it was observed that a full dewetting transition was possible, which suggests that natural organisms can exploit their multiple layers to prevent irreversible wetting.

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

    Science.gov (United States)

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

    2017-05-01

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

  12. Surface properties of a single perfluoroalkyl group on water surfaces studied by surface potential measurements.

    Science.gov (United States)

    Shimoaka, Takafumi; Tanaka, Yuki; Shioya, Nobutaka; Morita, Kohei; Sonoyama, Masashi; Amii, Hideki; Takagi, Toshiyuki; Kanamori, Toshiyuki; Hasegawa, Takeshi

    2016-12-01

    A discriminative study of a single perfluoroalkyl (Rf) group from a bulk material is recently recognized to be necessary toward the total understanding of Rf compounds based on a primary chemical structure. The single molecule and the bulk matter have an interrelationship via an intrinsic two-dimensional (2D) aggregation property of an Rf group, which is theorized by the stratified dipole-arrays (SDA) theory. Since an Rf group has dipole moments along many C-F bonds, a single Rf group would possess a hydrophilic-like character on the surface. To reveal the hydration character of a single Rf group, in the present study, surface potential (ΔV) measurements are performed for Langmuir monolayers of Rf-containing compounds. From a comparative study with a monolayer of a normal hydrocarbon compound, the hydration/dehydration dynamics of a lying Rf group on water has first been monitored by ΔV measurements, through which a single Rf group has been revealed to have a unique "dipole-interactive" character, which enables the Rf group interacted with the water 'surface.' In addition, the SDA theory proves to be useful to predict the 2D aggregation property across the phase transition temperature of 19°C by use of the ΔV measurements.

  13. OCCURRENCE OF ENTERIC VIRUSES IN SURFACE WATERS

    Science.gov (United States)

    Human enteric viruses cause a number of diseases when individuals are exposed to contaminated drinking & recreational waters. Vaccination against poliovirus has virtually eliminated poliomyelitis from the planet. Other members of enterovirus group cause numerous diseases. Hepatit...

  14. Interim Enhanced Surface Water Treatment Rule Documents

    Science.gov (United States)

    The IESWTR balances the need for treatment with potential increases in disinfection by -products. The materials found on this page are intended to assist public water systems and state in the implementation of the IESWTR.

  15. SurfaceWater Source Protection Areas (SPAs)

    Data.gov (United States)

    Vermont Center for Geographic Information — Source Protection Area (SPA) boundaries have been located on RF 24000 & RF 25000 scale USGS topographic maps by Water Supply Division (DEC) and VT Dept of Health...

  16. SURFACE WATER QUALITY IN ADDIS ABABA, ETHIOPIA

    African Journals Online (AJOL)

    environmental pollution derived from domestic and industrial activities. Due to the inadequacy of controlled waste management strategies and waste treatment plants ... Oxygen Demand (COD), Biological Oxygen Demand (BOD) and Dissolved ... appropriate waste water purifying plants. ..... University of Turku, Finland. 2.

  17. Bioinspired aquatic microrobot capable of walking on water surface like a water strider.

    Science.gov (United States)

    Zhang, Xinbin; Zhao, Jie; Zhu, Qing; Chen, Ning; Zhang, Mingwen; Pan, Qinmin

    2011-07-01

    Walking on the water surface is a dream of humans, but it is exactly the way of life for some aquatic insects. In this study, a bionic aquatic microrobot capable of walking on the water surface like a water strider was reported. The novel water strider-like robot consisted of ten superhydrophobic supporting legs, two miniature dc motors, and two actuating legs. The microrobot could not only stand effortlessly but also walk and turn freely on the water surface, exhibiting an interesting motion characteristic. A numerical model describing the interface between the partially submerged leg and the air-water surface was established to fully understand the mechanism for the large supporting force of the leg. It was revealed that the radius and water contact angle of the legs significantly affect the supporting force. Because of its high speed, agility, low cost, and easy fabrication, this microrobot might have a potential application in water quality surveillance, water pollution monitoring, and so on.

  18. Unique water-water coordination tailored by a metal surface

    DEFF Research Database (Denmark)

    Schiros, T.; Andersson, Klas Jerker; MacNaughton, J.;

    2013-01-01

    At low coverage of water on Cu(110), substrate-mediated electrostatics lead to zigzagging chains along [001] as observed with STM [T. Yamada, S. Tamamori, H. Okuyama, and T. Aruga, “Anisotropic water chain growth on Cu(110) observed with scanning tunneling microscopy” Phys. Rev. Lett. 96, 036105...... (2006)]. Using x-ray absorption spectroscopy we find an anomalous low-energy resonance at ~533.1 eV which, based on density functional theory spectrum simulations, we assign to an unexpected configuration of water units whose uncoordinated O-H bonds directly face those of their neighbors...

  19. Measurements of water surface snow lines in classical protoplanetary disks

    CERN Document Server

    Blevins, Sandra M; Banzatti, Andrea; Zhang, Ke; Najita, Joan R; Carr, John S; Salyk, Colette; Blake, Geoffrey A

    2015-01-01

    We present deep Herschel-PACS spectroscopy of far-infrared water lines from a sample of four protoplanetary disks around solar-mass stars, selected to have strong water emission at mid-infrared wavelengths. By combining the new Herschel spectra with archival Spitzer-IRS spectroscopy, we retrieve a parameterized radial surface water vapor distribution from 0.1-100 AU using two-dimensional dust and line radiative transfer modeling. The surface water distribution is modeled with a step model comprising of a constant inner and outer relative water abundance and a critical radius at which the surface water abundance is allowed to change. We find that the four disks have critical radii of $\\sim 3-11$ AU, at which the surface water abundance decreases by at least 5 orders of magnitude. The measured values for the critical radius are consistently smaller than the location of the surface snow line, as predicted by the observed spectral energy distribution. This suggests that the sharp drop-off of the surface water abu...

  20. Survival of Phytophthora infestans in Surface Water.

    Science.gov (United States)

    Porter, Lyndon D; Johnson, Dennis A

    2004-04-01

    ABSTRACT Coverless petri dishes with water suspensions of sporangia and zoospores of Phytophthora infestans were embedded in sandy soil in eastern Washington in July and October 2001 and July 2002 to quantify longevity of spores in water under natural conditions. Effects of solar radiation intensity, presence of soil in petri dishes (15 g per dish), and a 2-h chill period on survival of isolates of clonal lineages US-8 and US-11 were investigated. Spores in water suspensions survived 0 to 16 days under nonshaded conditions and 2 to 20 days under shaded conditions. Mean spore survival significantly increased from 1.7 to 5.8 days when soil was added to the water. Maximum survival time of spores in water without soil exposed to direct sunlight was 2 to 3 days in July and 6 to 8 days in October. Mean duration of survival did not differ significantly between chilled and nonchilled sporangia, but significantly fewer chilled spores survived for extended periods than that of nonchilled spores. Spores of US-11 and US-8 isolates did not differ in mean duration of survival, but significantly greater numbers of sporangia of US-8 survived than did sporangia of US-11 in one of three trials.

  1. Georgia's Surface-Water Resources and Streamflow Monitoring Network, 2008

    Science.gov (United States)

    ,

    2008-01-01

    Surface water provides 5 billion gallons per day, or 78 percent, of the total freshwater used (including thermoelectric) in Georgia (Fanning, 2003). Climate, geology, and landforms control the natural distribution of Georgia's water resources. Georgia is a 'headwaters' State, with most of the rivers beginning in northern Georgia and increasing in size downstream (see map at right for major watersheds). Surface water is the primary source of water in the northern one-half of the State, including the Atlanta metropolitan area, where limited ground-water resources are difficult to obtain. In Georgia, periodic droughts exacerbate competition for surface-water supplies. Many areas of Georgia also face a threat of flooding because of spring frontal thunderstorms and the potential for hurricanes from both the Atlantic Ocean and Gulf of Mexico. As the population of Georgia increases, these flood risks will increase with development in flood-risk zones, particularly in the coastal region.

  2. Surface complexation at calcium mineral-water interfaces

    OpenAIRE

    Wu, Liuming

    1994-01-01

    Surface reactions occurring at solid-water interfaces in calcium mineral-ligands systems have been studied. Both hydrous apatite and fluorite surfaces show clear amphoteric properties. An ion exchange process between lattice ions of F- on fluorite and OH- ions in bulk solution is discovered. The surface adsorption of Alizarin Red S and sodium oleate are determined. Surface chemical reaction models are established based on acidbase potentiometric titrations, solubility, adsorption and zeta-pot...

  3. A molecular dynamics study on surface properties of supercooled water

    Institute of Scientific and Technical Information of China (English)

    L(U) Yongjun; WEI Bingbo

    2006-01-01

    Molecular dynamics simulations were performed to study the surface properties of water in a temperature range from 228 to 293 K by using the extended simple point charge (SPC/E) and four-site TIP4P potentials. The calculated surface tension increases with the decrease of temperature, and moreover the slopes of the surface tension-temperature curves show a weak rise below 273 K, whereas no obvious anomalies appear near 228 K, which accords with the previous experiments. Compared with the measured values, the SPC/E potential shows a good agreement, and the TIP4P potential scription of the surface structure of supercooled water for the SPC/E. When simulating the orientational distributions of water molecules near the surface, the SPC/E potential produces higher ordering and larger surface potentials than the TIP4P potential.

  4. Tractor beam on the water surface

    CERN Document Server

    Punzmann, Horst; Xia, Hua; Falkovich, Gregory; Shats, Michael

    2014-01-01

    Can one send a wave to bring an object from a distance? The general idea is inspired by the recent success in moving micro particles using light and the development of a tractor beam concept. For fluid surfaces, however, the only known paradigm is the Stokes drift model, where linear planar waves push particles in the direction of the wave propagation. Here we show how to fetch a macroscopic floater from a large distance by sending a surface wave towards it. We develop a new method of remote manipulation of floaters by forming inward and outward surface jets, stationary vortices, and other complex surface flows using nonlinear waves generated by a vertically oscillating plunger. The flows can be engineered by changing the geometry and the power of a wave maker, and the flow dissipation. The new method is robust and works both for long gravity and for short capillary waves. We use a novel method of visualising 3D particle trajectories on the surface. This letter introduces a new conceptual framework for unders...

  5. HgZnTe-based detectors for LWIR NASA applications

    Science.gov (United States)

    Patten, Elizabeth A.; Kalisher, Murray H.

    1990-01-01

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

  6. Experimental Observation of Dark Solitons on Water Surface

    Science.gov (United States)

    2016-06-13

    vertical walls are made of transparent sections of glass supported by the metal frame. The water level of the free surface is measured with seven resistive...Experimental observation of dark solitons on water surface A. Chabchoub1,∗, O. Kimmoun2, H. Branger3, N. Hoffmann1, D. Proment4, M. Onorato4,5, and N...observation of dark solitons on the water surface. It takes the form of an amplitude drop of the carrier wave which does not change shape in propagation

  7. Drainage-water travel times as a key factor for surface water contamination

    OpenAIRE

    Groenendijk, P.; Eertwegh, van den, A.J.M.

    2004-01-01

    The importance of the unsaturated zone as an inextricable part of the hydrologic cycle has long been recognized. The root zone and the unsaturated sub-surface domain are chemically and biologically the most active zones. The interrelationships between soil, subsoil and surface waters make it unrealistic to treat the saturated and unsaturated zones and the discharge to surface waters separately. Point models describe vertical water flow in the saturated zone and possibly lateral flow by defini...

  8. Quality of surface water in Missouri, water year 2012

    Science.gov (United States)

    Barr, Miya N.

    2014-01-01

    The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designed and operates a series of monitoring stations on streams and springs throughout Missouri known as the Ambient Water-Quality Monitoring Network. During the 2012 water year (October 1, 2011, through September 30, 2012), data were collected at 81 stations—73 Ambient Water-Quality Monitoring Network stations, 6 alternate Ambient Water-Quality Monitoring Network stations, and 2 U.S. Geological Survey National Stream Quality Accounting Network stations. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, fecal coliform bacteria, Escherichia coli bacteria, dissolved nitrate plus nitrite as nitrogen, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 78 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak discharges, monthly mean discharges, and 7-day low flow is presented.

  9. Quality of surface water in Missouri, water year 2013

    Science.gov (United States)

    Barr, Miya N.; Schneider, Rachel E.

    2014-01-01

    The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designed and operates a series of monitoring stations on streams and springs throughout Missouri known as the Ambient Water-Quality Monitoring Network. During the 2013 water year (October 1, 2012, through September 30, 2013), data were collected at 79 stations—73 Ambient Water-Quality Monitoring Network stations, 4 alternate Ambient Water-Quality Monitoring Network stations, and 2 U.S. Geological Survey National Stream Quality Accounting Network stations. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, Escherichia coli bacteria, fecal coliform bacteria, dissolved nitrate plus nitrite as nitrogen, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 76 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak discharges, monthly mean discharges, and 7-day low flow is presented.

  10. ASSESSMENT OF SURFACE WATER QUALITY IN AN ARSENIC CONTAMINATED VILLAGE

    Directory of Open Access Journals (Sweden)

    Kumud C. Saikia

    2012-01-01

    Full Text Available Arsenic contamination of ground water has occurred in various parts of the world, becoming a menace in the Ganga-Meghna-Brahmaputra basin (West Bengal and Assam in India and Bangladesh. Recently arsenic has been detected in Cachar and Karimganj districts of barak valley, Assam, bordering Bangladesh. In this area coli form contamination comprises the major constraint towards utilization of its otherwise ample surface water resources. The local water management exploited ground water sources using a centralized piped water delivery scheme without taking into account the geologically arsenic-prone nature of the sediments and aquifers in this area. Thus surface water was the suggestive alternative for drinking water in this area. The present study investigated surface water quality and availability in a village of Karimganj district, Assam, India contaminated with arsenic for identifying the potential problems of surface water quality maintenance so that with effective management safe drinking water could be provided. The study revealed that the area was rich in freshwater ecosystems which had all physico-chemical variables such as water temperature, pH, DO, total alkalinity, free CO2, heavy metals like lead, chromium and cadmium within WHO standards. In contrast, coli form bacteria count was found far beyond permissible limit in all the sources. Around 60% people of the village preferred ground water for drinking and only 6% were aware of arsenic related problems. The problem of bacterial contamination could be controlled by implementing some ameliorative measures so that people can safely use surface water. Inhabitants of the two districts should be given proper education regarding arsenic contamination and associated health risk. Effluents should be treated to acceptable levels and standards before discharging them into natural streams.

  11. Electron bombardment of water adsorbed on Zr(0001) surfaces

    CERN Document Server

    Ankrah, S; Ramsier, R D

    2003-01-01

    A study of the effects of electron bombardment on water adsorbed on Zr(0001) is reported. Zirconium surfaces are dosed with isotopic water mixtures at 160 K followed by electron bombardment (485 eV). The system is then probed by low energy electron diffraction, temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). No evidence is found that would indicate preferential mixing of hydrogen from the bulk with isotopic water dissociation products during TPD. However, electron bombardment results in the sharpening of a hydrogen/deuterium desorption peak near 320 K and the production of water near 730 K at low water exposures. In addition, although water does not oxidize Zr(0001) thermally, electron bombardment of adsorbed water induces a shift of about 2 eV in the Zr AES features indicating that the surface is partially oxidized by electron bombardment.

  12. Magnetic fields of HgMn stars

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  13. Quality of surface water in Missouri, water year 2014

    Science.gov (United States)

    Barr, Miya N.

    2015-12-18

    The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designed and operates a series of monitoring stations on streams and springs throughout Missouri known as the Ambient Water-Quality Monitoring Network. During the 2014 water year (October 1, 2013, through September 30, 2014), data were collected at 74 stations—72 Ambient Water-Quality Monitoring Network stations and 2 U.S. Geological Survey National Stream Quality Assessment Network stations. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, Escherichia coli bacteria, fecal coliform bacteria, dissolved nitrate plus nitrite as nitrogen, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 71 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak discharges, monthly mean discharges, and 7-day low flow is presented.

  14. Quality of surface water in Missouri, water year 2010

    Science.gov (United States)

    Barr, Miya N.

    2011-01-01

    The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designs and operates a series of monitoring stations on streams throughout Missouri known as the Ambient Water-Quality Monitoring Network. During the 2010 water year (October 1, 2009 through September 30, 2010), data were collected at 75 stations-72 Ambient Water-Quality Monitoring Network stations, 2 U.S. Geological Survey National Stream Quality Accounting Network stations, and 1 spring sampled in cooperation with the U.S. Forest Service. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, fecal coliform bacteria, Escherichia coli bacteria, dissolved nitrate plus nitrite, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 72 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak discharges, monthly mean discharges, and 7-day low flow is presented.

  15. Quality of surface water in Missouri, water year 2009

    Science.gov (United States)

    Barr, Miya N.

    2010-01-01

    The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designs and operates a series of monitoring stations on streams throughout Missouri known as the Ambient Water-Quality Monitoring Network. During the 2009 water year (October 1, 2008, through September 30, 2009), data were collected at 75 stations-69 Ambient Water-Quality Monitoring Network stations, 2 U.S. Geological Survey National Stream Quality Accounting Network stations, 1 spring sampled in cooperation with the U.S. Forest Service, and 3 stations sampled in cooperation with the Elk River Watershed Improvement Association. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, fecal coliform bacteria, Escherichia coli bacteria, dissolved nitrate plus nitrite, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 72 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak discharges, monthly mean discharges, and seven-day low flow is presented.

  16. Quality of surface water in Missouri, water year 2011

    Science.gov (United States)

    Barr, Miya N.

    2012-01-01

    The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designed and operates a series of monitoring stations on streams throughout Missouri known as the Ambient Water-Quality Monitoring Network. During the 2011 water year (October 1, 2010, through September 30, 2011), data were collected at 75 stations—72 Ambient Water-Quality Monitoring Network stations, 2 U.S. Geological Survey National Stream Quality Accounting Network stations, and 1 spring sampled in cooperation with the U.S. Forest Service. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, fecal coliform bacteria, Escherichia coli bacteria, dissolved nitrate plus nitrite, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 72 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak discharges, monthly mean discharges, and 7-day low flow is presented.

  17. Quality of surface water in Missouri, water year 2015

    Science.gov (United States)

    Barr, Miya N.; Heimann, David C.

    2016-11-14

    The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, designed and operates a series of monitoring stations on streams and springs throughout Missouri known as the Ambient Water-Quality Monitoring Network. During water year 2015 (October 1, 2014, through September 30, 2015), data were collected at 74 stations—72 Ambient Water-Quality Monitoring Network stations and 2 U.S. Geological Survey National Stream Quality Assessment Network stations. Dissolved oxygen, specific conductance, water temperature, suspended solids, suspended sediment, Escherichia coli bacteria, fecal coliform bacteria, dissolved nitrate plus nitrite as nitrogen, total phosphorus, dissolved and total recoverable lead and zinc, and select pesticide compound summaries are presented for 71 of these stations. The stations primarily have been classified into groups corresponding to the physiography of the State, primary land use, or unique station types. In addition, a summary of hydrologic conditions in the State including peak streamflows, monthly mean streamflows, and 7-day low flows is presented.

  18. Role of water in polymer surface modification using organosilanes

    Science.gov (United States)

    Thallapalle, Pradeep Kumar; Zhang Newby, Bi-Min

    2002-03-01

    In general, polymers exhibit excellent bulk properties but may not possess specific surface properties for successful applications in biomaterials and nanotechnology. Surface modification of polymers with the self-assembled monolayers (SAMs) of organosilanes - ‘Silanization’ - is an attractive approach to alter surface properties without altering the polymer’s desired bulk properties. However, a pretreatment such as exposure to UV/O or plasma is normally required to generate active surface groups prior to silanization. These pretreatments cause undesirable surface changes such as severe surface roughening and excessive surface damage. Recent studies in silanization suggest that the presence of water or OH groups on the surface is essential to form SAMs. In this study we investigated the importance of surface water layer and OH groups in the formation of SAMs for a variety of polymers. The pre and post-modified polymers were examined using fourier transform infrared spectrometry, scanning probe microscopy and contact angle measurements. The results show that organosilanes can be grafted to a polymer surface as long as a water layer can be physisorbed to the surface or the polymer itself contains OH groups. However the monolayers formed are less organized compared to those formed on silicon wafers due to the amorphous nature of the polymers.

  19. SWFSC FED Mid Water Trawl Juvenile Rockfish Survey, Surface Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC FED Mid Water Trawl Juvenile Rockfish Survey: Station Information and Surface Data. Surveys have been conducted along the central California coast in May/June...

  20. Treatability of South African surface waters by enhanced coagulation

    African Journals Online (AJOL)

    2013-06-05

    Jun 5, 2013 ... The majority of South African inland surface water sources are compromised due to a ... minimising residual coagulant, minimising sludge production .... included as being indicative of the worst effects of indirect reuse.

  1. Second Inflection Point of the Surface Tension of Water

    Science.gov (United States)

    Kalova, Jana; Mares, Radim

    2012-06-01

    The theme of a second inflection point of the temperature dependence of the surface tension of water remains a subject of controversy. Using data above 273 K, it is difficult to get a proof of existence of the second inflection point, because of experimental uncertainties. Data for the surface tension of supercooled water and results of a molecular dynamics study were included into the exploration of existence of an inflection point. A new term was included into the IAPWS equation to describe the surface tension in the supercooled water region. The new equation describes the surface tension values of ordinary water between 228 K and 647 K and leads to the inflection point value at a temperature of about 1.5 °C.

  2. Shallow Water Propagation and Surface Reverberation Modeling

    Science.gov (United States)

    2012-09-30

    compare the results with experiment. This work will be used to help interpret field data of bistatic scattering from sea ice cover and calibrate...approximate analytical and numerical acoustic models used to compute bistatic scattering. The clouds of bubbles entrained at the sea surface by breaking...ABSTRACT SAR 18. NUMBER OF PAGES 7 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified

  3. Tracer injection techniques in flowing surface water

    Science.gov (United States)

    Wörman, A.

    2009-04-01

    Residence time distributions for flowing water and reactive matter are commonly used integrated properties of the transport process for determining technical issues of water resource management and in eco-hydrological science. Two general issues for tracer techniques are that the concentration-vs-time relation following a tracer injection (the breakthrough curve) gives unique transport information in different parts of the curve and separation of hydromechanical and reactive mechanisms often require simultaneous tracer injections. This presentation discusses evaluation methods for simultaneous tracer injections based on examples of tracer experiments in small rivers, streams and wetlands. Tritiated water is used as a practically inert substance to reflect the actual hydrodynamics, but other involved tracers are Cr(III)-51, P-32 and N-15. Hydromechanical, in-stream dispersion is reflected as a symmetrical spreading of the spatial concentration distribution. This requires that the transport distance over water depth is larger than about five times the flow Peclet number. Transversal retention of both inert and reactive solutes is reflected in terms of the tail of the breakthrough curve. Especially, reactive solutes can have a substantial magnification of the tailing behaviour depending on reaction rates or partitioning coefficients. To accurately discriminate between the effects of reactions and hydromechanical mixing its is relevant to use simultaneous injections of inert and reactive tracers with a sequential or integrated evaluation procedure. As an example, the slope of the P-32 tailing is consistently smaller than that of a simultaneous tritium injection in Ekeby wetland, Eskilstuna. The same applies to N-15 injected in the same experiment, but nitrogen is affected also by a systematic loss due to denitrification. Uptake in stream-bed sediments can be caused by a pumping effect arising when a variable pressure field is created on the stream bottom due to bed

  4. Cooperativity in Surface Bonding and Hydrogen Bonding of Water and Hydroxyl at Metal Surfaces

    DEFF Research Database (Denmark)

    Schiros, T.; Ogasawara, H.; Naslund, L. A.;

    2010-01-01

    of the mixed phase at metal surfaces. The surface bonding can be considered to be similar to accepting a hydrogen bond, and we can thereby apply general cooperativity rules developed for hydrogen-bonded systems. This provides a simple understanding of why water molecules become more strongly bonded...... to the surface upon hydrogen bonding to OH and why the OH surface bonding is instead weakened through hydrogen bonding to water. We extend the application of this simple model to other observed cooperativity effects for pure water adsorption systems and H3O+ on metal surfaces.......We examine the balance of surface bonding and hydrogen bonding in the mixed OH + H2O overlayer on Pt(111), Cu(111), and Cu(110) via density functional theory calculations. We find that there is a cooperativity effect between surface bonding and hydrogen bonding that underlies the stability...

  5. Super water repellent surface 'strictly' mimicking the surface structure of lotus leaf

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Tae Gon; Kim, Ho Young [Seoul National University, Seoul (Korea, Republic of); Yi, Jin Woo; Lee, Kwang Ryeol; Moon, Myoung Woon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2009-07-01

    To achieve the hierarchy of roughness as observed in lotus leaves, most artificial water-repellent surfaces have nano-asperities on top of micropillars. However, observation of real lotus leaves through SEM reveals that nonoscale roughness covers the entire surface including the base as well as bumps. Thus we fabricate surfaces having the same hierarchical roughness structure as the lotus leaf by forming nanopillars on both micropillars and base. We compare the measures of water-repellency (static contact angle, contact angle hysteresis, and transition pressure between the Cassie and Wenzel states) of the lotus-like surface with those of surfaces having single micro- and nano- roughness. The results show that nanoscale roughness covering entire surface area leads to superior water-repellency to other surface roughness structures. We also give a theoretical consideration of this observation.

  6. Simulation method for determining biodegradation in surface waters

    Energy Technology Data Exchange (ETDEWEB)

    Schoeberl, P.; Guhl, W. [Henkel KGaA, Duesseldorf (Germany). Hauptabteilung Oekologie; Scholz, N. [OXENO GmbH, Marl (Germany); Taeger, K. [BASF AG, Ludwigshafen am Rhein (Germany)

    1998-07-01

    OECD guidelines and EU directives on the biological testing of chemicals contain no methods able to simulate biodegradation in surface waters. The surface water simulation method presented in this paper is suitable for closing this gap. The species in the autochthonous biocoenosis used in the method form part of the food web in natural surface waters. The microbial degradation activity measured by the half-life is comparable with that in surface waters. The degrees of degradation measured in this surface water simulation method can be applied to natural surface waters. (orig.) [Deutsch] Die OECD- und EU-Richtlinien zur biologischen Pruefung von Chemikalien enthalten kein Verfahren, mit dem der biologische Abbau in Fliessgewaessern simuliert werden kann. Das in dieser Arbeit vorgestellte Fliessgewaesser-Simulationsmodell ist geeignet, diese Luecke zu schliessen. Die Arten der autochthonen Biocoenose des Modells sind Glieder im Nahrungsnetz natuerlicher Fliessgewaesser. Die an der Halbwertszeit gemessene mikrobielle Abbauaktivitaet ist mit derjenigen in Fliessgewaessern vergleichbar. Die im Fliessgewaesser-Simulationsmodell gemessenen Abbaugrade sind auf natuerliche Fliessgewaesser uebertragbar. (orig.)

  7. Chlorine stress mediates microbial surface attachment in drinking water systems.

    Science.gov (United States)

    Liu, Li; Le, Yang; Jin, Juliang; Zhou, Yuliang; Chen, Guowei

    2015-03-01

    Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems.

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

    Institute of Scientific and Technical Information of China (English)

    WUHONGTAO; YUGUIFEN; 等

    2001-01-01

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

  9. Water-clay surface interaction: A neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Sobolev, O., E-mail: sobolev38@gmail.com [LGIT, University of Grenoble and CNRS, BP 53-38041 Grenoble (France); Favre Buivin, F. [HES-SO Fribourg, Bd de Perolles 80-CP 32, CH-1705 Fribourg (Switzerland); Kemner, E.; Russina, M. [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Glienicker Strasse 100, D-14109 Berlin (Germany); Beuneu, B. [Laboratoire Leon Brillouin, C.E. Saclay, 91191 Gif sur Yvette (France); Cuello, G.J. [Institut Laue Langevin and Ikerbasque, 6, rue Jules Horowitz, BP 156, 38042 Grenoble, Cedex 9 (France); Charlet, L. [LGIT, University of Grenoble and CNRS, BP 53-38041 Grenoble (France)

    2010-08-23

    Graphical abstract: Interaction between water molecules and internal clay surfaces was studied by means of neutron diffraction and quasielastic neutron scattering. A hydrophobic cation, TMA{sup +} was used to reduce hydration of interlayer cations. - Abstract: The aim of this study was to investigate interaction between water molecules and internal clay surfaces by means of neutron diffraction and quasielastic neutron scattering. A hydrophobic cation, TMA{sup +} (NC{sub 4}H{sub 12}), was used to saturate the interlayer space of nontronite NAu-1 in order to reduce hydration of interlayer cations that could hinder the effects related to the clay-water interactions. The water content was low in order to reduce hydrogen bonding between water molecules. It was found that water molecules form strong hydrogen bonds with surface oxygen atoms of nontronite. The diffusion activation energy value E{sub a} = 29 {+-} 3 kJ/mol was obtained for water molecules hydrating the clay surface. These results confirm the assumption that surfaces of smectite clays with tetrahedral substitutions are hydrophilic.

  10. Dropwise condensation rate of water breath figures on polymer surfaces having similar surface free energies

    Science.gov (United States)

    Ucar, Ikrime O.; Erbil, H. Yildirim

    2012-10-01

    This study investigates the effect of surface roughness, wettability, water contact angle hysteresis (CAH) and wetting hysteresis (WH) of polymeric substrates to the water drop condensation rate. We used five polyolefin coatings whose surface free energies were in a close range of 30-37 mJ/m2 but having different surface roughness and CAH. The formation of water breath figures was monitored at a temperature just below the dew point. The initial number of the condensed droplets per unit area (N0) and droplet surface coverage were determined during the early stage of drop condensation where the droplet coalescence was negligible. It was found that the mean drop diameter of condensed droplets on these polymer surfaces grow according to a power law with exponent 1/3 of time, similar to the previous reports given in the literature. It was determined that surface roughness and corresponding CAH and WH properties of polymers have important effects on the number of nucleation sites and growth rate of the condensed water droplets. N0 values and the surface coverage increased with the increase in surface roughness, CAH and WH of the polymer surfaces. The total condensed water drop volume also increased with the increase in surface roughness in accordance with the increase of the number of nucleated droplets.

  11. Macro-invertebrate decline in surface water polluted with imidacloprid

    NARCIS (Netherlands)

    van Dijk, T.; van Staalduinen, M.A.; van der Sluijs, J.P.

    2013-01-01

    Imidacloprid is one of the most widely used insecticides in the world. Its concentration in surface water exceeds the water quality norms in many parts of the Netherlands. Several studies have demonstrated harmful effects of this neonicotinoid to a wide range of non-target species. Therefore we expe

  12. Magnetic fields of HgMn stars

    CERN Document Server

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

    2012-01-01

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

  13. HgCdTe barrier infrared detectors

    Science.gov (United States)

    Kopytko, M.; Rogalski, A.

    2016-05-01

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

  14. Practical aspects of tritium measurement in ground and surface waters

    Energy Technology Data Exchange (ETDEWEB)

    Nitzsche, O. [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Angewandte Physik; Hebert, D. [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Angewandte Physik

    1997-03-01

    Tritium measurements are a powerful tool in hydrological and hydrogeological investigations for detecting mean residence times of several water reservoirs. Due to the low tritium activities in precipitation, ground and surface waters a low level measurement is necessary. Therefore often the liquid scintillation counting after an electrolytic enrichment of water is used. In this paper some practical aspects and problems of measurement are discussed and the problem of contamination in low level laboratories is shown. (orig.)

  15. Assessment of heavy metal river Ingulets surface water pollution

    OpenAIRE

    Trokhymenko, Ganna G.; Tsyhanyuk, Nina V.

    2017-01-01

    The low efficiency of implemented targeted programs to reduce the anthropogenic impact on hydroecosystem and overcoming its negative consequences demand a search for the optimal evidence reasonable decisions to improve the quality of Ingul river water basin for different economic sectors of water resources and the required number and suitable quality. Methodical bases of such research must be based on a detailed and comprehensive study of the hydrochemical regime and surface water quality. Th...

  16. Effects of Dimethyl Sulfoxide on Surface Water near Phospholipid Bilayers.

    Science.gov (United States)

    Lee, Yuno; Pincus, Philip A; Hyeon, Changbong

    2016-12-06

    Despite much effort to probe the properties of dimethyl sulfoxide (DMSO) solution, the effects of DMSO on water, especially near plasma membrane surfaces, still remain elusive. By performing molecular dynamics simulations at varying DMSO concentrations (XDMSO), we study how DMSO affects structural and dynamical properties of water in the vicinity of phospholipid bilayers. As proposed by a number of experiments, our simulations confirm that DMSO induces dehydration from bilayer surfaces and disrupts the H-bond structure of water. However, DMSO-enhanced water diffusivity at solvent-bilayer interfaces, an intriguing discovery reported by a spin-label measurement, is not confirmed in our simulations. To resolve this discrepancy, we examine the location of the spin label (Tempo) relative to the solvent-bilayer interface. In accord with the evidence in the literature, our simulations, which explicitly model Tempo-phosphatidylcholine, find that the Tempo moiety is equilibrated at ∼8-10 Å below the bilayer surface. Furthermore, the DMSO-enhanced surface-water diffusion is confirmed only when water diffusion is analyzed around the Tempo moiety that is immersed below the bilayer surface, which implies that the experimentally detected signal of water using Tempo stems from the interior of bilayers, not from the interface. Our analysis finds that the increase of water diffusion below the bilayer surface is coupled to the increase of area per lipid with an increasing XDMSO(≲10mol%). Underscoring the hydrophobic nature of the Tempo moiety, our study calls for careful re-evaluation of the use of Tempo in measurements on lipid bilayer surfaces. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  17. An Ontology Design Pattern for Surface Water Features

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Gaurav [Ohio University; Mark, David [University at Buffalo (SUNY); Kolas, Dave [Raytheon BBN Technologies; Varanka, Dalia [U.S. Geological Survey, Rolla, MO; Romero, Boleslo E [University of California, Santa Barbara; Feng, Chen-Chieh [National University of Singapore; Usery, Lynn [U.S. Geological Survey, Rolla, MO; Liebermann, Joshua [Tumbling Walls, LLC; Sorokine, Alexandre [ORNL

    2014-01-01

    Surface water is a primary concept of human experience but concepts are captured in cultures and languages in many different ways. Still, many commonalities can be found due to the physical basis of many of the properties and categories. An abstract ontology of surface water features based only on those physical properties of landscape features has the best potential for serving as a foundational domain ontology. It can then be used to systematically incor-porate concepts that are specific to a culture, language, or scientific domain. The Surface Water ontology design pattern was developed both for domain knowledge distillation and to serve as a conceptual building-block for more complex surface water ontologies. A fundamental distinction is made in this on-tology between landscape features that act as containers (e.g., stream channels, basins) and the bodies of water (e.g., rivers, lakes) that occupy those containers. Concave (container) landforms semantics are specified in a Dry module and the semantics of contained bodies of water in a Wet module. The pattern is imple-mented in OWL, but Description Logic axioms and a detailed explanation is provided. The OWL ontology will be an important contribution to Semantic Web vocabulary for annotating surface water feature datasets. A discussion about why there is a need to complement the pattern with other ontologies, es-pecially the previously developed Surface Network pattern is also provided. Fi-nally, the practical value of the pattern in semantic querying of surface water datasets is illustrated through a few queries and annotated geospatial datasets.

  18. Rapid surface-water volume estimations in beaver ponds

    Science.gov (United States)

    Karran, Daniel J.; Westbrook, Cherie J.; Wheaton, Joseph M.; Johnston, Carol A.; Bedard-Haughn, Angela

    2017-02-01

    Beaver ponds are surface-water features that are transient through space and time. Such qualities complicate the inclusion of beaver ponds in local and regional water balances, and in hydrological models, as reliable estimates of surface-water storage are difficult to acquire without time- and labour-intensive topographic surveys. A simpler approach to overcome this challenge is needed, given the abundance of the beaver ponds in North America, Eurasia, and southern South America. We investigated whether simple morphometric characteristics derived from readily available aerial imagery or quickly measured field attributes of beaver ponds can be used to approximate surface-water storage among the range of environmental settings in which beaver ponds are found. Studied were a total of 40 beaver ponds from four different sites in North and South America. The simplified volume-area-depth (V-A-h) approach, originally developed for prairie potholes, was tested. With only two measurements of pond depth and corresponding surface area, this method estimated surface-water storage in beaver ponds within 5 % on average. Beaver pond morphometry was characterized by a median basin coefficient of 0.91, and dam length and pond surface area were strongly correlated with beaver pond storage capacity, regardless of geographic setting. These attributes provide a means for coarsely estimating surface-water storage capacity in beaver ponds. Overall, this research demonstrates that reliable estimates of surface-water storage in beaver ponds only requires simple measurements derived from aerial imagery and/or brief visits to the field. Future research efforts should be directed at incorporating these simple methods into both broader beaver-related tools and catchment-scale hydrological models.

  19. Integrated Water Flow Model (IWFM), A Tool For Numerically Simulating Linked Groundwater, Surface Water And Land-Surface Hydrologic Processes

    Science.gov (United States)

    Dogrul, E. C.; Brush, C. F.; Kadir, T. N.

    2006-12-01

    The Integrated Water Flow Model (IWFM) is a comprehensive input-driven application for simulating groundwater flow, surface water flow and land-surface hydrologic processes, and interactions between these processes, developed by the California Department of Water Resources (DWR). IWFM couples a 3-D finite element groundwater flow process and 1-D land surface, lake, stream flow and vertical unsaturated-zone flow processes which are solved simultaneously at each time step. The groundwater flow system is simulated as a multilayer aquifer system with a mixture of confined and unconfined aquifers separated by semiconfining layers. The groundwater flow process can simulate changing aquifer conditions (confined to unconfined and vice versa), subsidence, tile drains, injection wells and pumping wells. The land surface process calculates elemental water budgets for agricultural, urban, riparian and native vegetation classes. Crop water demands are dynamically calculated using distributed soil properties, land use and crop data, and precipitation and evapotranspiration rates. The crop mix can also be automatically modified as a function of pumping lift using logit functions. Surface water diversions and groundwater pumping can each be specified, or can be automatically adjusted at run time to balance water supply with water demand. The land-surface process also routes runoff to streams and deep percolation to the unsaturated zone. Surface water networks are specified as a series of stream nodes (coincident with groundwater nodes) with specified bed elevation, conductance and stage-flow relationships. Stream nodes are linked to form stream reaches. Stream inflows at the model boundary, surface water diversion locations, and one or more surface water deliveries per location are specified. IWFM routes stream flows through the network, calculating groundwater-surface water interactions, accumulating inflows from runoff, and allocating available stream flows to meet specified or

  20. Nonzero Ideal Gas Contribution to the Surface Tension of Water.

    Science.gov (United States)

    Sega, Marcello; Fábián, Balázs; Jedlovszky, Pál

    2017-06-15

    Surface tension, the tendency of fluid interfaces to behave elastically and minimize their surface, is routinely calculated as the difference between the lateral and normal components of the pressure or, invoking isotropy in momentum space, of the virial tensor. Here we show that the anisotropy of the kinetic energy tensor close to a liquid-vapor interface can be responsible for a large part of its surface tension (about 15% for water, independent from temperature).

  1. Metropolitan Spokane Region Water Resources Study. Appendix A. Surface Water

    Science.gov (United States)

    1976-01-01

    the river as surface supply. This second area lies mostly north of the Spokane River extending up the val- ley known as Rathdrum Prairie and includes...4 10. 2-29 I .~ -A- IvA -4 -4 IS I rp4r 1-4 - 4NCs 4~ 10. 2- 3o * r~tar gg~wr 4 . fAPPENDIX I en00 -4 - r., 0 CM- WMC q ~~0 0r0 4. .44 . VFog 4102A3

  2. Water transport mechanism through open capillaries analyzed by direct surface modifications on biological surfaces

    Science.gov (United States)

    Ishii, Daisuke; Horiguchi, Hiroko; Hirai, Yuji; Yabu, Hiroshi; Matsuo, Yasutaka; Ijiro, Kuniharu; Tsujii, Kaoru; Shimozawa, Tateo; Hariyama, Takahiko; Shimomura, Masatsugu

    2013-10-01

    Some small animals only use water transport mechanisms passively driven by surface energies. However, little is known about passive water transport mechanisms because it is difficult to measure the wettability of microstructures in small areas and determine the chemistry of biological surfaces. Herein, we developed to directly analyse the structural effects of wettability of chemically modified biological surfaces by using a nanoliter volume water droplet and a hi-speed video system. The wharf roach Ligia exotica transports water only by using open capillaries in its legs containing hair- and paddle-like microstructures. The structural effects of legs chemically modified with a self-assembled monolayer were analysed, so that the wharf roach has a smart water transport system passively driven by differences of wettability between the microstructures. We anticipate that this passive water transport mechanism may inspire novel biomimetic fluid manipulations with or without a gravitational field.

  3. Stormwater Priority Pollutants Versus Surface Water Quality Criteria

    DEFF Research Database (Denmark)

    Eriksson, Eva; Ledin, Anna; Baun, Anders

    2011-01-01

    Stormwater in urban areas comprises of a substantial part of the urban water cycle, dominating the flow in many small urban streams, and the pollution levels are sizeable. No stormwater quality criteria were found here and no European or national emission limit values exist. Stormwater pollutants...... however are present in levels exceeding most of the regulated surface water quality criteria and environmental quality standards. Therefore catchment characterisation is needed to chose suitable treatment prior to discharge into receiving surface waters, as the mixing may be insufficient in small streams....

  4. Surface Water Resources Response to Climate Changes in Jilin Province

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The response of surface water resources on climate changes was studied.[Method] By dint of monthly average temperature and precipitation in 45 meteorological stations in Jilin Province from 1960 to 2000,monthly runoff in 56 hydrological stations in Songhuajiang and Liaohe region,the surface runoff change and the response of surface water resources to climate change in 41 years were expounded.[Result] The runoff of Songliao region was limited during 1960s and 1970s.It began to increase slowly in ...

  5. The Proposed Surface Water and Ocean Topography (SWOT) Mission

    Science.gov (United States)

    Fu, Lee-Lueng; Alsdorf, Douglas; Rodriguez, Ernesto; Morrow, Rosemary; Mognard, Nelly; Vaze, Parag; Lafon, Thierry

    2012-01-01

    A new space mission concept called Surface Water and Ocean Topography (SWOT) is being developed jointly by a collaborative effort of the international oceanographic and hydrological communities for making high-resolution measurement of the water elevation of both the ocean and land surface water to answer the questions about the oceanic submesoscale processes and the storage and discharge of land surface water. The key instrument payload would be a Ka-band radar interferometer capable of making high-resolution wide-swath altimetry measurement. This paper describes the proposed science objectives and requirements as well as the measurement approach of SWOT, which is baselined to be launched in 2019. SWOT would demonstrate this new approach to advancing both oceanography and land hydrology and set a standard for future altimetry missions.

  6. The influence of lithology on surface water sources | Science ...

    Science.gov (United States)

    Understanding the temporal and spatial variability of surface water sources within a basin is vital to our ability to manage the impacts of climate variability and land cover change. Water stable isotopes can be used as a tool to determine geographic and seasonal sources of water at the basin scale. Previous studies in the Coastal Range of Oregon reported that the variation in the isotopic signatures of surface water does not conform to the commonly observed “rainout effect”, which exhibits a trend of increasing isotopic depletion with rising elevation. The primary purpose of this research is to investigate the mechanisms governing seasonal and spatial variations in the isotopic signature of surface waters within the Marys River Basin, located in the leeward side of the Oregon Coastal Range. Surface water and precipitation samples were collected every 2-3 weeks for isotopic analysis of δ18O and δ2H for one year. Results indicate a significant difference in isotopic signature between watersheds underlain by basalt and sandstone. The degree of separation was the most distinct during the summer when low flows reflect deeper groundwater sources, whereas isotopic signatures during the rainy season (fall and winter) showed a greater degree of similarity between the two lithologies. This indicates that baseflow within streams drained by sandstone versus basalt is being supplied from two distinctly separate water sources. In addition, Marys River flow at the outle

  7. Surface water waves due to an oscillatory wavemaker in the presence of surface tension

    Directory of Open Access Journals (Sweden)

    B. N. Mandal

    1992-01-01

    Full Text Available The initial value problem of generation of surface water waves by a harmonically oscillating plane vertical wavemaker in an infinite incompressible fluid under the action of gravity and surface tension is investigated. In the asymptotic evaluation of the free surface depression for large time and distance, the contribution to the integral by stationary phase method gives rise to transient component of the free surface depression while the contribution from the poles give rise to steady state component. It is observed that the presence of surface tension sometimes changes the qualitative nature of the transient component of free surface depression.

  8. Surface tension isotherms of the dioxane-acetone-water and glycerol-ethanol-water ternary systems

    Science.gov (United States)

    Dzhambulatov, R. S.; Dadashev, R. Kh.; Elimkhanov, D. Z.; Dadashev, I. N.

    2016-10-01

    The results of the experimental and theoretical studies of the concentration dependence of surface tension of aqueous solutions of the 1,4-dioxane-acetone-water and glycerol-ethanol-water ternary systems were given. The studies were performed by the hanging-drop method on a DSA100 tensiometer. The maximum error of surface tension was 1%. The theoretical models for calculating the surface tension of the ternary systems of organic solutions were analyzed.

  9. Supplementary report on surface-water and ground-water surveys, Nueces River Basin, Texas

    Science.gov (United States)

    Broadhurst, W.L.; Ellsworth, C.E.

    1950-01-01

    A report on the ground-water and surface-water surveys of the Nueces River Basin was included in a report by the Bureau of Reclamation, entitled "Comprehensive plan for water-resources development of the Nueces River Basin project planning report number 5-14.04-3, February 1946".

  10. 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.

  11. Using IR Imaging of Water Surfaces for Estimating Piston Velocities

    Science.gov (United States)

    Gålfalk, M.; Bastviken, D.; Arneborg, L.

    2013-12-01

    The transport of gasses dissolved in surface waters across the water-atmosphere interface is controlled by the piston velocity (k). This coefficient has large implications for, e.g., greenhouse gas fluxes but is challenging to quantify in situ. At present, empirical k-wind speed relationships from a small number of studies and systems are often extrapolated without knowledge of model performance. It is therefore of interest to search for new methods for estimating k, and to compare the pros and cons of existing and new methods. Wind speeds in such models are often measured at a height of 10 meters. In smaller bodies of water such as lakes, wind speeds can vary dramatically across the surface through varying degrees of wind shadow from e.g. trees at the shoreline. More local measurements of the water surface, through wave heights or surface motion mapping, could give improved k-estimates over a surface, also taking into account wind fetch. At thermal infrared (IR) wavelengths water has very low reflectivity (depending on viewing angle) than can go below 1%, meaning that more than 99% is heat radiation giving a direct measurement of surface temperature variations. Using an IR camera at about 100 frames/s one could map surface temperature structures at a fraction of a mm depth even with waves present. In this presentation I will focus on IR imaging as a possible tool for estimating piston velocities. Results will be presented from IR field measurements, relating the motions of surface temperature structures to k calculated from other simultaneous measurements (flux chamber and ADV-Based Dissipation Rate), but also attempting to calculate k directly from the IR surface divergence. A relation between wave height and k will also be presented.

  12. Foulant characteristics comparison in recycling cooling water system makeup by municipal reclaimed water and surface water in power plant.

    Science.gov (United States)

    Ping, Xu; Jing, Wang; Yajun, Zhang; Jie, Wang; Shuai, Si

    2015-01-01

    Due to water shortage, municipal reclaimed water rather than surface water was replenished into recycling cooling water system in power plants in some cities in China. In order to understand the effects of the measure on carbon steel corrosion, characteristics of two kinds of foulant produced in different systems were studied in the paper. Differences between municipal reclaimed water and surface water were analyzed firstly. Then, the weight and the morphology of two kinds of foulant were compared. Moreover, other characteristics including the total number of bacteria, sulfate reducing bacteria, iron bacteria, extracellular polymeric substance (EPS), protein (PN), and polysaccharide (PS) in foulant were analyzed. Based on results, it could be concluded that microbial and corrosive risk would be increased when the system replenished by municipal reclaimed water instead of surface water.

  13. Molecular Dynamics Simulations of Water Nanodroplets on Silica Surfaces

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.

    2009-01-01

    and DNA microarrays technologies.4,5,6,7,8 Although extensive experimental, theoretical and computational work has been devoted to study the nature of the interaction between silica and water,2,9-16 at the molecular level a complete understanding of silica-water systems has not been reached. Contact angle...... computations of water droplets on silica surfaces offers a useful fundamental and quantitative measurement in order to study chemical and physical properties of water-silica systems.3,16,17,18 For hydrophobic systems the static and dynamic properties of the fluid-solid interface are influenced by the presence...

  14. A Mechanism for Near-Surface Water Ice on Mars

    Science.gov (United States)

    Travis, B. J.; Feldman, W. C.; Maurice, S.

    2009-12-01

    Recent findings (e.g., Byrne et al, 2009) indicate that water ice lies very close to the surface at mid-latitudes on Mars. Re-interpretation of neutron and gamma-ray data is consistent with water ice buried less than a meter or two below the surface. Hydrothermal convection of brines provides a mechanism for delivering water to the near-surface. Previous numerical and experimental studies with pure water have indicated that hydrothermal circulation of pore water should be possible, given reasonable estimates of geothermal heat flux and regolith permeability. For pure water convection, the upper limit of the liquid zone would lie at some depth, but in the case of salt solutions, the boundary between liquid and frozen pore water could reach virtually to the surface. The principal drivers for hydrothermal circulation are regolith permeability, geothermal heat flux, surface temperature and salt composition. Both the Clifford and the Hanna-Phillips models of Martian regolith permeability predict sufficiently high permeabilities to sustain hydrothermal convection. Salts in solution will concentrate in upwelling plumes as the cold surface is approached. As water ice is excluded upon freezing, the remaining solution becomes a more concentrated brine, reaching its eutectic concentration before freezing. Numerical simulations considering several salts (NaCl, CaCl2, MgSO4), and a range of heat fluxes (20 - 100 mW/m2) covering the range of estimated present day heat flux (20 to 40 mW/m2) to moderately elevated conditions (60 to 100 mW/m2) such as might exist in the vicinity of volcanoes and craters, all indicate the same qualitative behavior. A completely liquid, convective regime occurs at depth, overlain by a partially frozen "mushy" layer (but still convecting despite the increased viscosity), overlain by a thin frozen layer at the surface. The thicknesses of these layers depend on the heat flux, surface temperature and the salt. As heat flux increases, the mushy region

  15. Lawrence Livermore National Laboratory Surface Water Protection: A Watershed Approach

    Energy Technology Data Exchange (ETDEWEB)

    Coty, J

    2009-03-16

    This surface water protection plan (plan) provides an overview of the management efforts implemented at Lawrence Livermore National Laboratory (LLNL) that support a watershed approach to protect surface water. This plan fulfills a requirement in the Department of Energy (DOE) Order 450.1A to demonstrate a watershed approach for surface water protection that protects the environment and public health. This plan describes the use of a watershed approach within which the Laboratory's current surface water management and protections efforts have been structured and coordinated. With more than 800 million acres of land in the U.S. under federal management and stewardship, a unified approach across agencies provides enhanced resource protection and cost-effectiveness. The DOE adopted, along with other federal agencies, the Unified Federal Policy for a Watershed Approach to Federal Land and Resource Management (UFP) with a goal to protect water quality and aquatic ecosystems on federal lands. This policy intends to prevent and/or reduce water pollution from federal activities while fostering a cost-effective watershed approach to federal land and resource management. The UFP also intends to enhance the implementation of existing laws (e.g., the Clean Water Act [CWA] and National Environmental Policy Act [NEPA]) and regulations. In addition, this provides an opportunity for the federal government to serve as a model for water quality stewardship using a watershed approach for federal land and resource activities that potentially impact surface water and its uses. As a federal land manager, the Laboratory is responsible for a small but important part of those 800 million acres of land. Diverse land uses are required to support the Laboratory's mission and provide an appropriate work environment for its staff. The Laboratory comprises two sites: its main site in Livermore, California, and the Experimental Test Site (Site 300), near Tracy, California. The main site

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

    Science.gov (United States)

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

    2007-11-01

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

  17. Impact of Water Recovery from Wastes on the Lunar Surface Mission Water Balance

    Science.gov (United States)

    Fisher, John W.; Hogan, John Andrew; Wignarajah, Kanapathipi; Pace, Gregory S.

    2010-01-01

    Future extended lunar surface missions will require extensive recovery of resources to reduce mission costs and enable self-sufficiency. Water is of particular importance due to its potential use for human consumption and hygiene, general cleaning, clothes washing, radiation shielding, cooling for extravehicular activity suits, and oxygen and hydrogen production. Various water sources are inherently present or are generated in lunar surface missions, and subject to recovery. They include: initial water stores, water contained in food, human and other solid wastes, wastewaters and associated brines, ISRU water, and scavenging from residual propellant in landers. This paper presents the results of an analysis of the contribution of water recovery from life support wastes on the overall water balance for lunar surface missions. Water in human wastes, metabolic activity and survival needs are well characterized and dependable figures are available. A detailed life support waste model was developed that summarizes the composition of life support wastes and their water content. Waste processing technologies were reviewed for their potential to recover that water. The recoverable water in waste is a significant contribution to the overall water balance. The value of this contribution is discussed in the context of the other major sources and loses of water. Combined with other analyses these results provide guidance for research and technology development and down-selection.

  18. The significant surface-water connectivity of "geographically isolated wetlands"

    Science.gov (United States)

    Calhoun, Aram J. K.; Mushet, David M.; Alexander, Laurie C.; DeKeyser, Edward S.; Fowler, Laurie; Lane, Charles R.; Lang, Megan W.; Rains, Mark C.; Richter, Stephen; Walls, Susan

    2017-01-01

    We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of grouping wetlands based on the singular condition of being surrounded by uplands. The most recent research on wetlands considered to be “geographically isolated” shows the difficulties in grouping an ecological resource that does not reliably indicate lack of surface water connectivity in order to meet legal, regulatory, or scientific needs. Additionally, the practice of identifying “geographically isolated wetlands” based on distance from a stream can result in gross overestimates of the number of wetlands lacking ecologically important surface-water connections. Our findings do not support use of the overly simplistic label of “geographically isolated wetlands”. Wetlands surrounded by uplands vary in function and surface-water connections based on wetland landscape setting, context, climate, and geographic region and should be evaluated as such. We found that the “geographically isolated” grouping does not reflect our understanding of the hydrologic variability of these wetlands and hence does not benefit conservation of the Nation’s diverse wetland resources. Therefore, we strongly discourage use of categorizations that provide overly simplistic views of surface-water connectivity of wetlands fully embedded in upland landscapes.

  19. Properties of water surface discharge at different pulse repetition rates

    Energy Technology Data Exchange (ETDEWEB)

    Ruma,; Yoshihara, K. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Hosseini, S. H. R., E-mail: hosseini@kumamoto-u.ac.jp; Sakugawa, T.; Akiyama, H. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555 (Japan); Akiyama, M. [Department of Electrical and Electronic Engineering, Kagoshima University, Kagoshima 890-0065 (Japan); Lukeš, P. [Institute of Plasma Physics, AS CR, Prague, Prague 18200 (Czech Republic)

    2014-09-28

    The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H₂O₂) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H₂O₂ and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.

  20. Operational Surface Water Detection and Monitoring Using Radarsat 2

    Directory of Open Access Journals (Sweden)

    Sandra Bolanos

    2016-03-01

    Full Text Available Traditional on-site methods for mapping and monitoring surface water extent are prohibitively expensive at a national scale within Canada. Despite successful cost-sharing programs between the provinces and the federal government, an extensive number of water features within the country remain unmonitored. Particularly difficult to monitor are the potholes in the Canadian Prairie region, most of which are ephemeral in nature and represent a discontinuous flow that influences water pathways, runoff response, flooding and local weather. Radarsat-2 and the Radarsat Constellation Mission (RCM offer unique capabilities to map the extent of water bodies at a national scale, including unmonitored sites, and leverage the current infrastructure of the Meteorological Service of Canada to monitor water information in remote regions. An analysis of the technical requirements of the Radarsat-2 beam mode, polarization and resolution is presented. A threshold-based procedure to map locations of non-vegetated water bodies after the ice break-up is used and complemented with a texture-based indicator to capture the most homogeneous water areas and automatically delineate their extents. Some strategies to cope with the radiometric artifacts of noise inherent to Synthetic Aperture Radar (SAR images are also discussed. Our results show that Radarsat-2 Fine mode can capture 88% of the total water area in a fully automated way. This will greatly improve current operational procedures for surface water monitoring information and impact a number of applications including weather forecasting, hydrological modeling, and drought/flood predictions.

  1. Studying surface water balance in Kurdistan province using GIS

    Directory of Open Access Journals (Sweden)

    Nader Fallah

    2016-06-01

    Full Text Available The study of water exchange in a region or area, which emphasizes the principle of conservation of matter in the water cycle, is called balance. Investigating their balance is the basis for managing the rivers’ water management, the results of which refer to the change rate in surface water supply and can efficiently be used in decision making and optimal use of water resources. The present study was carried out in order to investigate the surface water balance in Kurdistan province using GIS. In so doing, digital topographic maps, soil map of the area, and meteorological data retrieved from the regional stations were used to prepare layers of precipitation, evaporation and infiltration of rainwater into the soil. Discharge-arearegion comparative method was employed to measure the amount of runoff and base flow for each sub-basin in raster form saved per unit area which was subsequently overlapped based on balance equation, and the balance of the region was displayed in a graphical mode. The results indicated that more surface water is wasted in the southeast and central area of the province.

  2. Spatial development of the wind-driven water surface flow

    Science.gov (United States)

    Chemin, Rémi; Caulliez, Guillemette

    2015-04-01

    The water velocity field induced by wind and waves beneath an air-water interface is investigated experimentally versus fetch in the large Marseille-Luminy wind wave tank. Measurements of the vertical velocity profiles inside the subsurface shear layer were performed by a three-component Nortek acoustic Doppler velocimeter. The surface drift current was also derived from visualizations of small floating drifters recorded by a video camera looking vertically from above the water surface. Surface wave height and slopes were determined simultaneously by means of capacitance gauges and a single-point laser slope system located in the immediate vicinity of the profiler. Observations were made at steady low to moderate wind speeds and various fetches ranging between 1 and 15 meters. This study first corroborates that the thin subsurface water boundary layer forced by wind at the leading edge of the water sheet is laminar. The surface drift current velocity indeed increases gradually with fetch, following a 1/3 power law characteristic of an accelerated flat-plate laminar boundary layer. The laminar-turbulent transition manifests itself by a sudden decrease in the water surface flow velocity and a rapid deepening of the boundary layer due to the development of large-scale longitudinal vortices. Further downstream, when characteristic capillary-gravity wind waves develop at the surface, the water flow velocity increases again rapidly within a sublayer of typically 4 mm depth. This phenomenon is explained by the occurrence of an intense momentum flux from waves to the mean flow due to the dissipation of parasitic capillaries generated ahead of the dominant wave crests. This phenomenon also sustains significant small-scale turbulent motions within the whole boundary layer. However, when gravity-capillary waves of length longer than 10 cm then grow at the water surface, the mean flow velocity field decreases drastically over the whole boundary layer thickness. At the same

  3. Influence of building resolution on surface water inundation outputs

    Science.gov (United States)

    Green, Daniel; Yu, Dapeng; Pattison, Ian

    2016-04-01

    Surface water (pluvial) flooding occurs when intense precipitation events overwhelm the drainage capacity of an area and excess water is unable to infiltrate into the ground or drain via natural or artificial drainage channels. In the UK, over 3 million properties are at risk from surface water flooding alone, accounting for approximately one third of all UK flood risk. This risk is predicted to increase due to future climatic changes resulting in an increasing magnitude and frequency of intense precipitation events. Numerical modelling is a well-established method of investigating surface water flood risk, allowing the researcher to gain an understanding of the depth, extent and severity of actual or hypothetical flood scenarios. Although numerical models allow the simulation of surface water inundation in a particular region, the model parameters (e.g. roughness, hydraulic conductivity) and resolution of topographic data have been shown to exert a profound influence on the inundation outputs which often leads to an over- or under-estimation of flood depths and extent without the use of external validation data to calibrate model outputs. Although previous research has demonstrated that model outputs are highly sensitive to Digital Elevation Model (DEM) mesh resolution, with flood inundation over large and complex topographies often requiring mesh resolutions coarser than the structural features (e.g. buildings) present within the study catchment, the specific influence of building resolution on surface flowpaths and connectivity during a surface water flood event has not been investigated. In this study, a LiDAR-derived DEM and OS MasterMap buildings layer of the Loughborough University campus, UK, were rasterized into separate 1m, 5m and 10m resolution layers. These layers were combined to create a series of Digital Surface Models (DSM) with varying, mismatching building and DEM resolutions (e.g. 1m DEM resolution, 10m building resolution, etc.) to understand

  4. Infiltration of pesticides in surface water into nearby drinking water supply wells

    Science.gov (United States)

    Malaguerra, F.; Albrechtsen, H.; Binning, P. J.

    2010-12-01

    Drinking water wells are often placed near streams because streams often overly permeable sediments and the water table is near the surface in valleys, and so pumping costs are reduced. The lowering of the water table by pumping wells can reverse the natural flow from the groundwater to the stream, inducing infiltration of surface water to groundwater and consequently to the drinking water well. Many attenuation processes can take place in the riparian zone, mainly due to mixing, biodegradation and sorption. However, if the water travel time from the surface water to the pumping well is too short, or if the compounds are poorly degradable, contaminants can reach the drinking water well at high concentrations, jeopardizing drinking water quality. Here we developed a reactive transport model to evaluate the risk of contamination of drinking water wells by surface water pollution. The model was validated using data of a tracer experiment in a riparian zone. Three compounds were considered: an older pesticide MCPP (Mecoprop) which is mobile and persistent, glyphosate (Roundup), a new biodegradable and strongly sorbed pesticide, and its degradation product AMPA. Global sensitivity analysis using the method of Morris was employed to identify the dominant model parameters. Results showed that the presence of an aquitard and its characteristics (degree of fracturing and thickness), pollutant properties and well depth are the crucial factors affecting the risk of drinking water well contamination from surface water. Global sensitivity analysis results were compared with rank correlation statistics between pesticide concentrations and geological parameters derived from a comprehensive database of Danish drinking water wells. Aquitard thickness and well depth are the most critical parameters in both the model and observed data.

  5. Sources of mercury to San Francisco Bay surface sediment as revealed by mercury stable isotopes

    Science.gov (United States)

    Gehrke, Gretchen E.; Blum, Joel D.; Marvin-DePasquale, Mark

    2011-01-01

    Mercury (Hg) concentrations and isotopic compositions were examined in shallow-water surface sediment (0–2 cm) from San Francisco (SF) Bay to determine the extent to which historic Hg mining contributes to current Hg contamination in SF Bay, and to assess the use of Hg isotopes to trace sources of contamination in estuaries. Inter-tidal and wetland sediment had total Hg (HgT) concentrations ranging from 161 to 1529 ng/g with no simple gradients of spatial variation. In contrast, inter-tidal and wetland sediment displayed a geographic gradient of δ202Hg values, ranging from -0.30% in the southern-most part of SF Bay (draining the New Almaden Hg District) to -0.99% in the northern-most part of SF Bay near the Sacramento–San Joaquin River Delta. Similar to SF Bay inter-tidal sediment, surface sediment from the Alviso Slough channel draining into South SF Bay had a δ202Hg value of -0.29%, while surface sediment from the Cosumnes River and Sacramento–San Joaquin River Delta draining into north SF Bay had lower average δ202Hg values of -0.90% and -0.75%, respectively. This isotopic trend suggests that Hg-contaminated sediment from the New Almaden Hg District mixes with Hg-contaminated sediment from a low δ202Hg source north of SF Bay. Tailings and thermally decomposed ore (calcine) from the New Idria Hg mine in the California Coast Range had average δ202Hg values of -0.37 and +0.03%, respectively, showing that Hg calcination fractionates Hg isotopes resulting in Hg contamination from Hg(II) mine waste products with higher δ202Hg values than metallic Hg(0) produced from Hg mines. Thus, there is evidence for at least two distinct isotopic signals for Hg contamination in SF Bay: Hg associated with calcine waste materials at Hg mines in the Coast Range, such as New Almaden and New Idria; and Hg(0) produced from these mines and used in placer gold mines and/or in other industrial processes in the Sierra Nevada region and SF Bay area.

  6. Sources of mercury to San Francisco Bay surface sediment as revealed by mercury stable isotopes

    Science.gov (United States)

    Gehrke, Gretchen E.; Blum, Joel D.; Marvin-DiPasquale, Mark

    2011-02-01

    Mercury (Hg) concentrations and isotopic compositions were examined in shallow-water surface sediment (0-2 cm) from San Francisco (SF) Bay to determine the extent to which historic Hg mining contributes to current Hg contamination in SF Bay, and to assess the use of Hg isotopes to trace sources of contamination in estuaries. Inter-tidal and wetland sediment had total Hg (Hg T) concentrations ranging from 161 to 1529 ng/g with no simple gradients of spatial variation. In contrast, inter-tidal and wetland sediment displayed a geographic gradient of δ 202Hg values, ranging from -0.30‰ in the southern-most part of SF Bay (draining the New Almaden Hg District) to -0.99‰ in the northern-most part of SF Bay near the Sacramento-San Joaquin River Delta. Similar to SF Bay inter-tidal sediment, surface sediment from the Alviso Slough channel draining into South SF Bay had a δ 202Hg value of -0.29‰, while surface sediment from the Cosumnes River and Sacramento-San Joaquin River Delta draining into north SF Bay had lower average δ 202Hg values of -0.90‰ and -0.75‰, respectively. This isotopic trend suggests that Hg-contaminated sediment from the New Almaden Hg District mixes with Hg-contaminated sediment from a low δ 202Hg source north of SF Bay. Tailings and thermally decomposed ore (calcine) from the New Idria Hg mine in the California Coast Range had average δ 202Hg values of -0.37 and +0.03‰, respectively, showing that Hg calcination fractionates Hg isotopes resulting in Hg contamination from Hg(II) mine waste products with higher δ 202Hg values than metallic Hg(0) produced from Hg mines. Thus, there is evidence for at least two distinct isotopic signals for Hg contamination in SF Bay: Hg associated with calcine waste materials at Hg mines in the Coast Range, such as New Almaden and New Idria; and Hg(0) produced from these mines and used in placer gold mines and/or in other industrial processes in the Sierra Nevada region and SF Bay area.

  7. Return of naturally sourced Pb to Atlantic surface waters

    Science.gov (United States)

    Bridgestock, Luke; van de Flierdt, Tina; Rehkämper, Mark; Paul, Maxence; Middag, Rob; Milne, Angela; Lohan, Maeve C.; Baker, Alex R.; Chance, Rosie; Khondoker, Roulin; Strekopytov, Stanislav; Humphreys-Williams, Emma; Achterberg, Eric P.; Rijkenberg, Micha J. A.; Gerringa, Loes J. A.; de Baar, Hein J. W.

    2016-09-01

    Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the nearly complete global cessation of leaded petrol use. Significant proportions of up to 30-50% of natural Pb, derived from mineral dust, are observed in Atlantic surface waters, reflecting the success of the global effort to reduce anthropogenic Pb emissions. The observation of mineral dust derived Pb in surface waters is governed by the elevated atmospheric mineral dust concentration of the North African dust plume and the dominance of dry deposition for the atmospheric aerosol flux to surface waters. Given these specific regional conditions, emissions from anthropogenic activities will remain the dominant global marine Pb source, even in the absence of leaded petrol combustion.

  8. Macroelements in the surface microlayer of water of urban ponds

    Directory of Open Access Journals (Sweden)

    Antonowicz Józef Piotr

    2016-03-01

    Full Text Available Analyses were conducted concerning the accumulation of four metals representing the group of macroelements, i.e. sodium, potassium, calcium and magnesium in two ponds located in the city of Słupsk. Water samples for chemical analyses were collected from the surface microlayer using a Garrett net. At the same time subsurface water samples were collected. Concentrations of metals were determined using a mass spectrometer. Generally, amounts of sodium, potassium, calcium and magnesium were similar in surface microlayer and subsurface water. Only in the case of potassium and calcium was low enrichment observed in the surface microlayer in one pond, while the greatest extent for magnesium enrichment was observed in the spring period.

  9. Occurrence of illicit drugs in surface waters in China.

    Science.gov (United States)

    Li, Kaiyang; Du, Peng; Xu, Zeqiong; Gao, Tingting; Li, Xiqing

    2016-06-01

    Illicit drugs have been recognized as a group of emerging contaminants. In this work, occurrence of common illicit drugs and their metabolites in Chinese surface waters was examined by collecting samples from 49 lakes and 4 major rivers across the country. Among the drugs examined, methamphetamine and ketamine were detected with highest frequencies and concentration levels, consistent with the fact that these are primary drugs of abuse in China. Detection frequencies and concentrations of other drugs were much lower than in European lakes and rivers reported in the literature. In most Chinese surface waters methamphetamine and ketamine were detected at concentrations of several ng L(-1) or less, but in some southern lakes and rivers, these two drugs were detected at much higher concentrations (up to several tens ng L(-1)). Greater occurrence of methamphetamine and ketamine in southern surface waters was attributed to greater abuse and more clandestine production of the two drugs in southern China.

  10. Wavefront modulation of water surface wave by a metasurface

    Institute of Scientific and Technical Information of China (English)

    孙海涛; 程营; 王敬时; 刘晓峻

    2015-01-01

    We design a planar metasurface to modulate the wavefront of a water surface wave (WSW) on a deep sub-wavelength scale. The metasurface is composed of an array of coiling-up-space units with specially designed parameters, and can take on the work of steering the wavefront when it is pierced into water. Like their acoustic counterparts, the modulation of WSW is ascribed to the gradient phase shift of the coiling-up-space units, which can be perfectly tuned by changing the coiling plate length and channel number inside the units. According to the generalized Snell’s law, negative refraction and‘driven’ surface mode of WSW are also demonstrated at certain incidences. Specially, the transmitted WSW could be efficiently guided out by linking a symmetrically-corrugated channel in‘driven’ surface mode. This work may have potential applications in water wave energy extraction and coastal protection.

  11. Salty glycerol versus salty water surface organization: bromide and iodide surface propensities.

    Science.gov (United States)

    Huang, Zishuai; Hua, Wei; Verreault, Dominique; Allen, Heather C

    2013-07-25

    Salty NaBr and NaI glycerol solution interfaces are examined in the OH stretching region using broadband vibrational sum frequency generation (VSFG) spectroscopy. Raman and infrared (IR) spectroscopy are used to further understand the VSFG spectroscopic signature. The VSFG spectra of salty glycerol solutions reveal that bromide and iodide anions perturb the interfacial glycerol organization in a manner similar as that found in aqueous halide salt solutions, thus confirming the presence of bromide and iodide anions at the glycerol surface. Surface tension measurements are consistent with the surface propensity suggested by the VSFG data and also show that the surface excess increases with increasing salt concentration, similar to that of water. In addition, iodide is shown to have more surface prevalence than bromide, as has also been determined from aqueous solutions. These results suggest that glycerol behaves similarly to water with respect to surface activity and solvation of halide anions at its air/liquid interface.

  12. Biogeochemical factors affecting the distribution, speciation, and transport of Hg species in the Deûle and Lys Rivers (Northern France).

    Science.gov (United States)

    Daye, Mirna; Kadlecova, Milada; Ouddane, Baghdad

    2015-02-01

    The Deûle River is a highly polluted River by heavy metals caused by the historical discharges of ore minerals from the former ore smelter "Metaleurop." The potential mercury (Hg) pollution in the Deûle River implicates the importance of Hg distribution study in the river. As well as to configure the different biogeochemical factors that control the distribution and the potential transport of Hg to distant places. Four different sites were studied as follows: D-A (Deûle River, a site located upstream the river), D-B (Deûle River, a site located near a Zn, Pb, Cu, and Ni smelter that closed in 2003), L-C (Lys River, a site located upstream the confluence of the Deûle River with Lys River), and L-D (downstream the rivers confluence). Different Hg analyses were performed including total mercury in sediment (HgTS), methylmercury (MeHg) in sediment, total mercury in pore water (HgTPW), total mercury in surface water (HgTD), and total suspended particulate Hg in water (HgTP). HgTS decreases downstream from the Deûle River sites with a mean value of 11 ± 0.34 mg/kg to Lys River site (L-D) with a mean value of 0.53 ± 0.02 mg/kg at the confluence. The unaffected side of the Lys River, localized before the confluence (L-C), is characterized by low HgTS of an average value of 0.042 ± 0.003 mg/kg and high % MeHg reaching 4.2 %. Whereas, the highly contaminated Deûle sites are designated by low % MeHg with an average value of 0.053 %. Low pristine environments like that found in L-C site with more favorable biogeochemical conditions of lower concentrations of HgTS, sulfides, and Corg host more active biotic methylation than that of the highly polluted Deûle sites with high concentrations of HgTS and sulfides concentrations. Methylation in D-B (the closet site to Metaleurop smelter) is an old and recent methylation activity that has contributed to MeHg accumulation in the sediments as opposed to the exclusive recent events of methylation in Lys sites. MeHg

  13. Synthesis of amino functionalized magnetic graphenes composite material and its application to remove Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) from contaminated water.

    Science.gov (United States)

    Guo, Xiaoyao; Du, Bin; Wei, Qin; Yang, Jian; Hu, Lihua; Yan, Liangguo; Xu, Weiying

    2014-08-15

    In the present study, a kind of graphenes magnetic material (Fe3O4-GS) was prepared by compositing graphene sheet with ferroferric oxide, and shown to be effective for removing Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) ions from aqueous solution. The synthesized sorbent was characterized by SEM, TEM, FTIR, XRD, XPS and BET, respectively. The pHZPC value of the sorbent was estimated to be 3.5 by alkaline-titration methods. Fe3O4-GS can be simply recovered from water with magnetic separation at low magnetic field within one minute. The sorption capacities of the metals were 17.29, 27.95, 23.03, 27.83 and 22.07 mg g(-1) for Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II), respectively. Kinetic data showed good correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data of all the heavy metal ions. It was found that the metals sorption was accomplished mainly via chelation or ion exchange. The results of thermodynamic studies illustrate that the adsorption process was endothermic and spontaneous in nature.

  14. Engineering of a highly efficient Xe₂*-excilamp (xenon excimer lamp, λmax=172 nm, η=40%) and qualitative comparison to a low-pressure mercury lamp (LP-Hg, λ=185/254 nm) for water purification.

    Science.gov (United States)

    Al-Gharabli, Samer; Engeßer, Patrick; Gera, Diana; Klein, Sandra; Oppenländer, Thomas

    2016-02-01

    Excilamps are mercury-free gas-discharge sources of non-coherent VUV or UV radiation with high radiant power and a long lifetime. The most efficient excilamp that is currently available on the market is a VUV xenon excilamp system (Xe2(*)-excimer lamp, λ(max) = 172 nm) with a stated radiant efficiency η of 40% at an electrical input power P(el) of 20 W, 50 W or 100 W. In this paper, the use of this highly efficient Xe2(*)-excilamp (P(el) = 20 W) for water treatment is demonstrated using a recirculating laboratory photoreactor system with negative radiation geometry. The efficiency in the 172 nm initiated bleaching of aqueous solutions of Rhodamine B is compared to that initiated by a common low-pressure mercury (LP-Hg) lamp (185 nm, TNN 15/32). The dependence of the pseudo zero order rate constant k´ of decolorization of RhB on the flow rate and on the initial concentration of RhB was investigated. Both lamps exhibited dependences of k´ on the initial concentration of RhB, which represents a typical saturation kinetical behavior. The saturation kinetics was very prominent in the case of the Xe2(*)-excilamp. Also, the Xe2(*)-excilamp treatment exhibited a significant influence on the flow rate of the RhB aqueous solution, which was not the case during the LP-Hg lamp initiated bleaching of RhB. The results of this paper demonstrate that Xe2(*)-excilamps can be used for VUV-initiated water purification. However, to reach the maximum efficacy of the Xe2(*)-excilamp for photo-initiated water purification further engineering optimization of the photoreactor concept is necessary.

  15. Spring and surface water quality of the Cyprus ophiolites

    Directory of Open Access Journals (Sweden)

    C. Neal

    2002-01-01

    Full Text Available A survey of surface, spring and borehole waters associated with the ophiolite rocks of Cyprus shows five broad water types (1 Mg-HCO3, (2 Na-SO4-Cl-HCO3, (3 Na-Ca-Cl-SO4-OH-CO3, (4 Na-Cl-SO4 and (5 Ca-SO4. The waters represent a progression in chemical reactivity from surface waters that evolve within a groundwater setting due to hydrolysis of the basic/ultrabasic rock as modified by CO2-weathering. An increase in salinity is also observed which is due to mixing with a saline end-member (modified sea-water and dissolution of gypsum/anhydrite. In some cases, the waters have pH values greater than 11. Such high values are associated with low temperature serpentinisation reactions. The system is a net sink for CO2. This feature is related not only to the hydrolysis of the primary minerals in the rock, but also to CaCO3 or Ca-Mg-CO3 solubility controls. Under hyperalkaline conditions, virtually all the carbon dioxide is lost from the water due to the sufficiently high calcium levels and carbonate buffering is then insignificant. Calcium sulphate solubility controls may also be operative when calcium and sulphate concentrations are particularly high. Keywords: Cyprus, Troodos, ophiolite, serpentinisation, spring, stream, water quality, bromide, iodine, boron, trace elements, hyperalkaline.

  16. Zirconium fluoride glass - Surface crystals formed by reaction with water

    Science.gov (United States)

    Doremus, R. H.; Bansal, N. P.; Bradner, T.; Murphy, D.

    1984-01-01

    The hydrated surfaces of a zirconium barium fluoride glass, which has potential for application in optical fibers and other optical elements, were observed by scanning electron microscopy. Crystalline zirconium fluoride was identified by analysis of X-ray diffraction patterns of the surface crystals and found to be the main constituent of the surface material. It was also found that hydrated zirconium fluorides form only in highly acidic fluoride solutions. It is possible that the zirconium fluoride crystals form directly on the glass surface as a result of its depletion of other ions. The solubility of zirconium fluoride is suggested to be probably much lower than that of barium fluoride (0.16 g/100 cu cm at 18 C). Dissolution was determined to be the predominant process in the initial stages of the reaction of the glass with water. Penetration of water into the glass has little effect.

  17. Eutrophication management in surface waters using lanthanum modified bentonite

    DEFF Research Database (Denmark)

    Copetti, Diego; Finsterle, Karin; Marziali, Laura

    2016-01-01

    This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The availa......This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales...

  18. Evaluation of ATP measurements to detect microbial ingress by wastewater and surface water in drinking water

    DEFF Research Database (Denmark)

    Vang, Óluva Karin; Corfitzen, Charlotte B.; Smith, Christian

    2014-01-01

    in this respect. Compared to traditional microbiological methods, the ATP assay could detect wastewater and surface water in drinking water to a higher degree than total direct counts (TDCs), while both heterotrophic plate counts (HPC 22 °C and HPC 37 °C) and Colilert-18 (Escherichia coli and coliforms) were more......Fast and reliable methods are required for monitoring of microbial drinking water quality in order to protect public health. Adenosine triphosphate (ATP) was investigated as a potential real-time parameter for detecting microbial ingress in drinking water contaminated with wastewater or surface...

  19. Some Aspects of Surface Water Treatment Technology in Tirana Drinking Water Treatment Plant

    OpenAIRE

    , Tania Floqi; , Aleksandër Trajçe; , Daut Vezi

    2009-01-01

    Tirana’s Bovilla treatment plant was the Şrst of its kind for Albania, which treats surface water. The input water comes from the Bovilla artiŞcial lake, around which, the presence of villages induces pollution in the surface water and therefore affects the efŞciency of treatment plant and consequently the quality of drinking water. The treatment plant is a simple conventional system and includes pre-oxidation, coagulation, şocculation & sedimentation, fast Şltration, post-oxidation. ...

  20. Fluctuations of water near extended hydrophobic and hydrophilic surfaces

    OpenAIRE

    Patel, Amish J.; Chandler, David

    2009-01-01

    We use molecular dynamics simulations of the SPC-E model of liquid water to derive probability distributions for water density fluctuations in probe volumes of different shapes and sizes, both in the bulk as well as near hydrophobic and hydrophilic surfaces. To obtain our results, we introduce a biased sampling of coarse-grained densities, which in turn biases the actual solvent density. The technique is easily combined with molecular dynamics integration algorithms. Our principal result is t...

  1. Variations in stable isotope fractionation of Hg in food webs of Arctic lakes.

    Science.gov (United States)

    Gantner, Nikolaus; Hintelmann, Holger; Zheng, Wang; Muir, Derek C

    2009-12-15

    Biotic and abiotic fractionation of mercury (Hg) isotopes has recently been shown to occur in aquatic environments. We determined isotope ratios (IRs) of Hg in food webs (zooplankton, chironomids, Arctic char) and sediments of 10 Arctic lakes from four regions and investigated the extent of Hg isotope fractionation. Hg IRs were analyzed by multicollector inductively coupled plasma mass spectrometry (MC-ICP/MS). Hg mass independent fractionation (MIF; Delta(199)Hg) and mass dependent fractionation (MDF; delta(202)Hg) were calculated and compared among samples. IRs of Hg in sediment were characterized mainly by MDF and low MIF (Delta(199)Hg -0.37 to 0.74 per thousand). However, all biota showed evidence of MIF, most pronounced in zooplankton (Delta(199)Hg up to 3.40 per thousand) and char (Delta(199)Hg up to 4.87 per thousand). Zooplankton takes up highly fractionated MeHg directly from the water column, while benthic organisms are exposed to sedimentary Hg, which contains less fractionated Hg. As evidenced by delta(13)C measurements, benthic chironomids make up a large proportion of char diet, explaining in part why MIF(char) meteor impact crater lake (Pingualuk) reflects a "pure" atmospheric Hg signature, which is modified only by aqueous in-lake processes. All other lakes are also affected by terrestrial Hg inputs and sediment processes.

  2. Monitoring of endocrine disrupting chemicals in surface water

    CSIR Research Space (South Africa)

    Govender, S

    2008-06-01

    Full Text Available the surface. The chelated Pluronic-DMDDO ligand can be used for affinity purification of histidine tagged proteins. A regeneration formulation based on anionic SDS detergent desorbed pluronic modified polymeric membranes and the possibility of re... ingredients, household products and industrial chemicals. Surface waters are the main sink of said EDCs. Accurate EDC detection is usually via time consuming and costly ex situ LC-MS and GC-MS analysis. An important class of biosensors include those...

  3. Hydrodynamic boundary condition of water on hydrophobic surfaces.

    Science.gov (United States)

    Schaeffel, David; Yordanov, Stoyan; Schmelzeisen, Marcus; Yamamoto, Tetsuya; Kappl, Michael; Schmitz, Roman; Dünweg, Burkhard; Butt, Hans-Jürgen; Koynov, Kaloian

    2013-05-01

    By combining total internal reflection fluorescence cross-correlation spectroscopy with Brownian dynamics simulations, we were able to measure the hydrodynamic boundary condition of water flowing over a smooth solid surface with exceptional accuracy. We analyzed the flow of aqueous electrolytes over glass coated with a layer of poly(dimethylsiloxane) (advancing contact angle Θ = 108°) or perfluorosilane (Θ = 113°). Within an error of better than 10 nm the slip length was indistinguishable from zero on all surfaces.

  4. Nanofiltration in Transforming Surface Water into Healthy Water: Comparison with Reverse Osmosis

    Directory of Open Access Journals (Sweden)

    L. D. Naidu

    2015-01-01

    Full Text Available The natural surface water, especially available through rivers, is the main source of healthy water for the living beings throughout the world from ancient days as it consists of all essential minerals. With the advent of industrialization, gradually even the most prominent rivers have been polluted in all parts of the world. Although there are lots of technologies, nanofiltration (NF has been chosen to transform river water into healthy water due to its unique advantages of retaining optimum TDS (with essential minerals required for human body, consuming of lower energy, and no usage of any chemicals. The prominent parameters of surface water and macro/microminerals of treated water have been analyzed. It is shown that NF is better in producing healthy water with high flux by consuming low energy.

  5. Surface Tension of Ab Initio Liquid Water at the Water-Air Interface

    CERN Document Server

    Nagata, Yuki; Bonn, Mischa; Kühne, Thomas D

    2016-01-01

    We report calculations of the surface tension of the water-air interface using ab initio molecular dynamics (AIMD) simulations. We investigate the simulation cell size dependence of the surface tension of water from force field molecular dynamics (MD) simulations, which show that the calculated surface tension increases with increasing simulation cell size, thereby illustrating that a correction for finite size effects is required for the small system used in the AIMD simulation. The AIMD simulations reveal that the double-{\\xi} basis set overestimates the experimentally measured surface tension due to the Pulay stress, while the triple and quadruple-{\\xi} basis sets give similar results. We further demonstrate that the van der Waals corrections critically affect the surface tension. AIMD simulations without the van der Waals correction substantially underestimate the surface tension, while van der Waals correction with the Grimme's D2 technique results in the value for the surface tension that is too high. T...

  6. Groundwater - surface water interactions in the Ayeyarwady river delta, Myanmar

    Science.gov (United States)

    Miyaoka, K.; Haruyama, S.; Kuzuha, Y.; Kay, T.

    2012-12-01

    Groundwater is widely used as a water resource in the Ayeyarwady River delta. But, Groundwater has some chemical problem in part of the area. To use safety groundwater for health, it is important to make clear the actual conditions of physical and chemical characteristics of groundwater in this delta. Besides, Ayeyarwady River delta has remarkable wet and dry season. Surface water - groundwater interaction is also different in each season, and it is concerned that physical and chemical characteristics of groundwater is affected by the flood and high waves through cyclone or monsoon. So, it is necessary to research a good aquifer distribution for sustainable groundwater resource supply. The purposes of this study are evaluate to seasonal change of groundwater - surface water interactions, and to investigate the more safety aquifer to reduce the healthy risk. Water samples are collected at 49 measurement points of river and groundwater, and are analyzed dissolved major ions and oxygen and hydro-stable isotope compositions. There are some groundwater flow systems and these water qualities are different in each depth. These showed that physical and chemical characteristics of groundwater are closely related to climatological, geomorphogical, geological and land use conditions. At the upper Alluvium, groundwater quality changes to lower concentration in wet season, so Ayeyarwady River water is main recharge water at this layer in the wet season. Besides, in the dry season, water quality is high concentration by artificial activities. Shallower groundwater is affected by land surface conditions such as the river water and land use in this layer. At lower Alluvium, Arakan and Pegu mountains are main recharge area of good water quality aquifers. Oxygen18 value showed a little affected by river water infiltration in the wet season, but keep stable good water quality through the both seasons. In the wet season, the same groundwater exists and water quality changes through

  7. Distribution of tritium in precipitation and surface water in California

    Science.gov (United States)

    Harms, Patrick A.; Visser, Ate; Moran, Jean E.; Esser, Brad K.

    2016-03-01

    The tritium concentration in the surface hydrosphere throughout California was characterized to examine the reasons for spatial variability and to enhance the applicability of tritium in hydrological investigations. Eighteen precipitation samples were analyzed and 148 samples were collected from surface waters across California in the Summer and Fall of 2013, with repeat samples from some locations collected in Winter and Spring of 2014 to examine seasonal variation. The concentration of tritium in present day precipitation varied from 4.0 pCi/L near the California coast to 17.8 pCi/L in the Sierra Nevada Mountains. Concentrations in precipitation increase in spring due to the 'Spring Leak' phenomenon. The average coastal concentration (6.3 ± 1.2 pCi/L) in precipitation matches estimated pre-nuclear levels. Surface water samples show a trend of increasing tritium with inland distance. Superimposed on that trend, elevated tritium concentrations are found in the San Francisco Bay area compared to other coastal areas, resulting from municipal water imported from inland mountain sources and local anthropogenic sources. Tritium concentrations in most surface waters decreased between Summer/Fall 2013 and Winter/Spring 2014 likely due to an increased groundwater signal as a result of drought conditions in 2014. A relationship between tritium and electrical conductivity in surface water was found to be indicative of water provenance and anthropogenic influences such as agricultural runoff. Despite low initial concentrations in precipitation, tritium continues to be a valuable tracer in a post nuclear bomb pulse world.

  8. Water and Carbon Dioxide Adsorption at Olivine Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.

    2013-11-14

    Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

  9. Surface Water Data at Los Alamos National Laboratory 1998 Water Year

    Energy Technology Data Exchange (ETDEWEB)

    D. A. Shaull; M. R. Alexander; R. P. Reynolds; C. T. McLean; R. P. Romero

    1999-02-01

    The principal investigators collected and computed surface water discharge data from 19 stream-gaging stations that cover most of Los Alamos National Laboratory. Also included are discharge data from three springs that flow into Caiion de Vane.

  10. Scaling up ecohydrological processes: role of surface water flow in water-limited landscapes

    CSIR Research Space (South Africa)

    Popp, A

    2009-11-01

    Full Text Available microscale processes like ecohydrological feedback mechanisms and spatial exchange like surface water flow, the authors derive transition probabilities from a fine-scale simulation model. They applied two versions of the landscape model, one that includes...

  11. Theoretical Study of Sodium-Water Surface Reaction Mechanism

    Science.gov (United States)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

  12. Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II binary complexes of l-methionine in 1,2-propanediol-water mixtures

    Directory of Open Access Journals (Sweden)

    M. Padma Latha

    2007-04-01

    Full Text Available Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II complexes of L-methionine in 0.0-60 % v/v 1,2-propanediol-water mixtures maintaining an ionic strength of 0.16 M at 303 K has been studied pH metrically. The active forms of ligand are LH2+, LH and L-. The predominant species detected are ML, MLH, ML2, ML2H, ML2H2 and MLOH. Models containing different numbers of species were refined by using the computer program MINIQUAD 75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces.

  13. IMPROVING CYANOBACTERIA AND CYANOTOXIN MONITORING IN SURFACE WATERS FOR DRINKING WATER SUPPLY

    Directory of Open Access Journals (Sweden)

    Jing Li

    2017-06-01

    Full Text Available Cyanobacteria in fresh water can cause serious threats to drinking water supplies. Managing cyanobacterial blooms particularly at small drinking water treatment plants is challenging. Because large amount of cyanobacteria may cause clogging in the treatment process and various cyanotoxins are hard to remove, while they may cause severe health problems. There is lack of instructions of what cyanobacteria/toxin amount should trigger what kind of actions for drinking water management except for Microcystins. This demands a Cyanobacteria Management Tool (CMT to help regulators/operators to improve cyanobacteria/cyanotoxin monitoring in surface waters for drinking water supply. This project proposes a CMT tool, including selecting proper indicators for quick cyanobacteria monitoring and verifying quick analysis methods for cyanobacteria and cyanotoxin. This tool is suggested for raw water management regarding cyanobacteria monitoring in lakes, especially in boreal forest climate. In addition, it applies to regions that apply international WHO standards for water management. In Swedish context, drinking water producers which use raw water from lakes that experience cyanobacterial blooms, need to create a monitoring routine for cyanobacteria/cyanotoxin and to monitor beyond such as Anatoxins, Cylindrospermopsins and Saxitoxins. Using the proposed CMT tool will increase water safety at surface water treatment plants substantially by introducing three alerting points for actions. CMT design for each local condition should integrate adaptive monitoring program.

  14. Thin Water and Ice Films at Mineral Surfaces

    Science.gov (United States)

    Yeşilbaş, Merve; Boily, Jean-François

    2016-04-01

    Mineral-water and ice interactions play important roles in atmospheric cloud formation. They also affect soil biogeochemistry as well as outer-space processes. In this study, thin water and ice films formed on minerals of varied bulk and surface structure, shape, size and surface roughness were probed by Fourier Transform Infrared Spectroscopy (FTIR) and by Dynamic Vapor Adsorption (DVA). Measurements on several types of iron (oxyhydr)oxides, phyllosilicates, orthosilicates, tectosilicates as well as Arizona Test Dust (ATD) and Icelandic volcanic ash constrained our understanding of the molecular-level nature of mineral surface-water and ice interactions. DVA experiments showed that particle size is the key feature controlling water loadings at 25 ° C. Under this condition, nano-sized particles stabilized the equivalence of no more than ˜6 monolayers of water at the near saturation of water vapor while sub-micron sized particles stabilized several thousand layers. This result can be explained by the greater ability of larger sized particles at driving water condensation reactions. Cryogenic FTIR measurements at -10 and -50 ° C revealed that most minerals acquired the thin ice films with similar hydrogen bonding environments as those formed at room temperature.[1,2] These thin ice films have weaker hydrogen bond environments than hexagonal ice (νOH ≈ 3130 cm-1), a result seen by FTIR through predominant O-H stretching modes at νOH ≈ 3408-3425 cm-1. The water bending region (˜1630 cm-1) also reveals that most thin ice films are rather supercooled forms of water. Only the materials with greatest levels of heterogeneity, namely ATD and volcanic ash, stabilized solid forms of water reminiscent to hexagonal ice. This work thus constrains further our understanding of how interfacial ice is stabilized at mineral surfaces, and opens possibilities for future studies focused on atmospheric gas uptake on mineral- water and ice admixtures. [1] Song, X. and Boily, J

  15. Uranium in US surface, ground, and domestic waters. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Drury, J.S.; Reynolds, S.; Owen, P.T.; Ross, R.H.; Ensminger, J.T.

    1981-04-01

    The report Uranium in US Surface, Ground, and Domestic Waters comprises four volumes. Volumes 2, 3, and 4 contain data characterizing the location, sampling date, type, use, and uranium conentrations of 89,994 individual samples presented in tabular form. The tabular data in volumes 2, 3, and 4 are summarized in volume 1 in narrative form and with maps and histograms.

  16. Surface water and groundwater interaction on a hill island

    DEFF Research Database (Denmark)

    Frederiksen, Rasmus Rumph; Rasmussen, Keld Rømer; Christensen, Steen

    – the hill islands – is relatively unknown. This study aims at providing new information about the rainfall-runoff processes in hill island landscapes where surface water and groundwater interaction is expected to have a dominant role and hill-slope processes not. Through stream flow measurements, field...

  17. The interaction of water and hydrogen with nickel surfaces

    NARCIS (Netherlands)

    Shan, Junjun

    2009-01-01

    As nickel and platinum are in the same group of the periodic table, the Ni(111) and Pt(111) surfaces may be expected to show similar interaction with water and hydrogen. However in this thesis, we show these interactions for Ni(111) are quite different from those of Pt(111). Moreover, our results

  18. Observation of water condensate on hydrophobic micro textured surfaces

    Science.gov (United States)

    Kim, Ki Wook; Do, Sang Cheol; Ko, Jong Soo; Jeong, Ji Hwan

    2013-07-01

    We visually observed that a dropwise condensation occurred initially and later changed into a filmwise condensation on hydrophobic textured surface at atmosphere pressure condition. It was observed that the condensate nucleated on the pillar side walls of the micro structure and the bottom wall adhered to the walls and would not be lifted to form a spherical water droplet using environmental scanning electron microscope.

  19. Zearalenone occurrence in surface waters in central Illinois, USA

    Science.gov (United States)

    Zearalenone (ZEN) is an estrogenic secondary metabolite produced by certain fungi that commonly infest important cereal crops, such as corn and wheat. The ability of ZEN to move from contaminated crops to surface waters has been demonstrated previously. This article reports the development of a meth...

  20. Surface water risk assessment of pesticides in Ethiopia

    NARCIS (Netherlands)

    Teklu, B.M.; Adriaanse, P.I.; Horst, ter M.M.S.; Deneer, J.W.; Brink, van den P.J.

    2015-01-01

    Scenarios for future use in the pesticide registration procedure in Ethiopia were designed for 3 separate Ethiopian locations, which are aimed to be protective for the whole of Ethiopia. The scenarios estimate concentrations in surface water resulting from agricultural use of pesticides for a small

  1. Riparian shrub buffers reduce surface water pollutant loads

    Science.gov (United States)

    W. A. Geyer; C. Barden; K. Mankin; D. Devlin

    2003-01-01

    Surface water resources in Kansas often contain concentrations of pesticides, nutrients, and sediments that are of concern to local citizens. The United States Geological Survey reported in 1999 that 97 percent of streams and 82 percent of lakes in Kansas would not fully support all uses as designated by state statutes (U.S. Geological Survey 1999). Bacteria and...

  2. Modelling the effects of surface water flood pulses on groundwater

    NARCIS (Netherlands)

    Schot, P.P.; Wassen, M.J.

    2010-01-01

    Flood pulses in wetlands steer ecosystem development directly through surface water processes and indirectly through the effects of the flood pulse on groundwater. Direct effects on ecosystems are exerted by e.g. inundation and deposition of sediments containing nutrients. Indirect effects include t

  3. The interaction of water and hydrogen with nickel surfaces

    NARCIS (Netherlands)

    Shan, Junjun

    2009-01-01

    As nickel and platinum are in the same group of the periodic table, the Ni(111) and Pt(111) surfaces may be expected to show similar interaction with water and hydrogen. However in this thesis, we show these interactions for Ni(111) are quite different from those of Pt(111). Moreover, our results sh

  4. Surface water risk assessment of pesticides in Ethiopia

    NARCIS (Netherlands)

    Teklu, B.M.; Adriaanse, P.I.; Horst, ter M.M.S.; Deneer, J.W.; Brink, van den P.J.

    2015-01-01

    Scenarios for future use in the pesticide registration procedure in Ethiopia were designed for 3 separate Ethiopian locations, which are aimed to be protective for the whole of Ethiopia. The scenarios estimate concentrations in surface water resulting from agricultural use of pesticides for a small

  5. An Experimental Study of Planing Surfaces Operating in Shallow Water

    Science.gov (United States)

    1976-09-01

    D C APPROVED FOR PUBLIC RELEASE; (7 DISTRIBUTION UNLIMITED 22 1918 PT CLAIME Ar-Th -L’A THI S DOUETI 7E QUALITLY . AVAIILABIJaTECP FURNSR DTO DTIC...Aerodynamic tares were determined by towing the model just above the water surface at various trims and speeds. Only the drag was greatly affected by air

  6. CONTROLLING STORM WATER RUNOFF WITH TRADABLE CREDITS FOR IMPERVIOUS SURFACES

    Science.gov (United States)

    Storm water flow off impervious surface in a watershed can lead to stream degradation, habitat alteration, low base flows and toxic leading. We show that a properly designed tradable runoff credit (TRC) system creates economic incentives for landowners to employ best management p...

  7. Quality of surface-water supplies in the Triangle area of North Carolina, water year 2008

    Science.gov (United States)

    Giorgino, M.J.; Rasmussen, R.B.; Pfeifle, C.A.

    2012-01-01

    Surface-water supplies are important sources of drinking water for residents in the Triangle area of North Carolina, which is located within the upper Cape Fear and Neuse River Basins. Since 1988, the U.S. Geological Survey and a consortium of governments have tracked water-quality conditions and trends in several of the area's water-supply lakes and streams. This report summarizes data collected through this cooperative effort, known as the Triangle Area Water Supply Monitoring Project, during October 2007 through September 2008. Major findings for this period include:

  8. Index of surface-water stations in Texas, January 1988

    Science.gov (United States)

    Rawson, Jack; Carrillo, E.R.; Buckner, H.D.

    1988-01-01

    As of January 1, 1988, the surface-water data-collection network in Texas included 368 continuous streamflow, 12 continuous or daily reservoir-content, 38 gage height, 15 crest-stage partia 1-record, 4 periodic discharge through range, 32 floodhydrocjraph partial-record, 9 flood-profile partial-record, 36 low-flow partial-record 45 daily chemical-quality, 19 continuous-recording water-quality, 83 periodic biological, 19 lake surveys, 160 periodic organic and (or) nutrient, 3 periodic insecticide, 33 periodic pesticide, 20 automatic sampler, 137 periodic minor elements, 125 periodic chemical-quality, 74 periodic physica1-organic, 24 continuous-recording three- or four-parameter water-quality, 34 periodic sediment, 21 continuous-recording temperature, and 30 national stream-quality accounting network stations. Plate 1 shows the location of surface-water streamflow or reservoir-content and chemicalquality or sediment stations in Texas. Plate 2 shows the location of partial-record surface-water stations.

  9. Surface Water Data at Los Alamos National Laboratory 2000 Water Year

    Energy Technology Data Exchange (ETDEWEB)

    D.A.Shaull; M.R.Alexander; R.P.Reynolds; R.P.Romero; E.T.Riebsomer; C.T.McLean

    2001-06-02

    The principal investigators collected and computed surface water discharge data from 23 stream-gaging stations that cover most of Los Alamos National Laboratory and one at Bandelier National Monument. Also included are discharge data from three springs, two that flow into Canon del Valle and one that flows into Water Canyon.

  10. Surface Water Data at Los Alamos National Laboratory: 2002 Water Year

    Energy Technology Data Exchange (ETDEWEB)

    D.A. Shaull; D. Ortiz; M.R. Alexander; R.P. Romero

    2003-03-03

    The principal investigators collected and computed surface water discharge data from 34 stream-gaging stations that cover most of Los Alamos National Laboratory and one at Bandelier National Monument. Also included are discharge data from three springs--two that flow into Canon de Valle and one that flows into Water Canyon--and peak flow data from 16 stations.

  11. Surface Water Data at Los Alamos National Laboratory: 1999 Water Year

    Energy Technology Data Exchange (ETDEWEB)

    D. A. Shaull; M. R. Alexander; R. P. Reynolds; C. T. McLean; R. P. Romero

    2000-04-01

    The principal investigators collected and computed surface water discharge data from 22 stream-gaging stations that cover most of Los Alamos National Laboratory with one at Bandelier National Monument. Also included are discharge data from three springs that flow into Canon de Valle and nine partial-record storm water stations.

  12. Surface water data at Los Alamos National Laboratory: 2008 water year

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, David; Cata, Betsy; Kuyumjian, Gregory

    2009-09-01

    The principal investigators collected and computed surface water discharge data from 69 stream-gage stations that cover most of Los Alamos National Laboratory and one at Bandelier National Monument. Also included are discharge data from three springs— two that flow into Cañon de Valle and one that flows into Water Canyon.

  13. Surface Water Data at Los Alamos National Laboratory 2006 Water Year

    Energy Technology Data Exchange (ETDEWEB)

    R.P. Romero, D. Ortiz, G. Kuyumjian

    2007-08-01

    The principal investigators collected and computed surface water discharge data from 44 stream-gaging stations that cover most of Los Alamos National Laboratory and one at Bandelier National Monument. Also included are discharge data from three springs--two that flow into Canon de Valle and one that flows into Water Canyon--and peak flow data for 44 stations.

  14. Development of aquatic biomonitoring models for surface waters used for drinking water supply

    NARCIS (Netherlands)

    Penders, E.J.M.

    2011-01-01

    Given the need for continued quality control of surface waters used for the production of drinking water by state-of-the-art bioassays and biological early warning systems, the objective of the present thesis was to validate and improve some of the bioassays and biological early warning systems used

  15. Surface water data at Los Alamos National Laboratory: 2008 water year

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, David; Cata, Betsy; Kuyumjian, Gregory

    2009-09-01

    The principal investigators collected and computed surface water discharge data from 69 stream-gage stations that cover most of Los Alamos National Laboratory and one at Bandelier National Monument. Also included are discharge data from three springs— two that flow into Cañon de Valle and one that flows into Water Canyon.

  16. Surface water data at Los Alamos National Laboratory: 2009 water year

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, David; McCullough, Betsy

    2010-05-01

    The principal investigators collected and computed surface water discharge data from 73 stream-gage stations that cover most of Los Alamos National Laboratory and one at Bandelier National Monument. Also included are discharge data from three springs— two that flow into Cañon de Valle and one that flows into Water Canyon.

  17. Survey of the Mutagenicity of Surface Water, Sediments, and Drinking Water from the Penobscot Indian Nation.

    Science.gov (United States)

    Survey of the Mutagenicity of Surface Water, Sediments, andDrinking Water from the Penobscot Indian NationSarah H. Warren, Larry D. Claxton,1, Thomas J. Hughes,*, Adam Swank,Janet Diliberto, Valerie Marshall, Daniel H. Kusnierz, Robert Hillger, David M. DeMariniNational Health a...

  18. Water level observations from Unmanned Aerial Vehicles for improving estimates of surface water-groundwater interaction

    DEFF Research Database (Denmark)

    Bandini, Filippo; Butts, Michael; Vammen Jacobsen, Torsten

    2017-01-01

    . However, traditional river gauging stations are normally spaced too far apart to capture spatial patterns in the water surface, while spaceborne observations have limited spatial and temporal resolution. UAVs (Unmanned Aerial Vehicles) can retrieve river water level measurements, providing: i) high...

  19. Membranes with Surface-Enhanced Antifouling Properties for Water Purification

    Science.gov (United States)

    Shahkaramipour, Nima; Tran, Thien N.; Ramanan, Sankara; Lin, Haiqing

    2017-01-01

    Membrane technology has emerged as an attractive approach for water purification, while mitigation of fouling is key to lower membrane operating costs. This article reviews various materials with antifouling properties that can be coated or grafted onto the membrane surface to improve the antifouling properties of the membranes and thus, retain high water permeance. These materials can be separated into three categories, hydrophilic materials, such as poly(ethylene glycol), polydopamine and zwitterions, hydrophobic materials, such as fluoropolymers, and amphiphilic materials. The states of water in these materials and the mechanisms for the antifouling properties are discussed. The corresponding approaches to coat or graft these materials on the membrane surface are reviewed, and the materials with promising performance are highlighted. PMID:28273869

  20. Membranes with Surface-Enhanced Antifouling Properties for Water Purification

    Directory of Open Access Journals (Sweden)

    Nima Shahkaramipour

    2017-03-01

    Full Text Available Membrane technology has emerged as an attractive approach for water purification, while mitigation of fouling is key to lower membrane operating costs. This article reviews various materials with antifouling properties that can be coated or grafted onto the membrane surface to improve the antifouling properties of the membranes and thus, retain high water permeance. These materials can be separated into three categories, hydrophilic materials, such as poly(ethylene glycol, polydopamine and zwitterions, hydrophobic materials, such as fluoropolymers, and amphiphilic materials. The states of water in these materials and the mechanisms for the antifouling properties are discussed. The corresponding approaches to coat or graft these materials on the membrane surface are reviewed, and the materials with promising performance are highlighted.

  1. Flow boiling of water on nanocoated surfaces in a microchannel

    CERN Document Server

    Phan, Hai Trieu; Marty, Philippe; Colasson, Stéphane; Gavillet, Jérôme

    2010-01-01

    Experiments were performed to study the effects of surface wettability on flow boiling of water at atmospheric pressure. The test channel is a single rectangular channel 0.5 mm high, 5 mm wide and 180 mm long. The mass flux was set at 100 kg/m2 s and the base heat flux varied from 30 to 80 kW/m2. Water enters the test channel under subcooled conditions. The samples are silicone oxide (SiOx), titanium (Ti), diamond-like carbon (DLC) and carbon-doped silicon oxide (SiOC) surfaces with static contact angles of 26{\\deg}, 49{\\deg}, 63{\\deg} and 103{\\deg}, respectively. The results show significant impacts of surface wettability on heat transfer coefficient.

  2. Evaluation of ATP measurements to detect microbial ingress by wastewater and surface water in drinking water.

    Science.gov (United States)

    Vang, Óluva K; Corfitzen, Charlotte B; Smith, Christian; Albrechtsen, Hans-Jørgen

    2014-11-01

    Fast and reliable methods are required for monitoring of microbial drinking water quality in order to protect public health. Adenosine triphosphate (ATP) was investigated as a potential real-time parameter for detecting microbial ingress in drinking water contaminated with wastewater or surface water. To investigate the ability of the ATP assay in detecting different contamination types, the contaminant was diluted with non-chlorinated drinking water. Wastewater, diluted at 10(4) in drinking water, was detected with the ATP assay, as well as 10(2) to 10(3) times diluted surface water. To improve the performance of the ATP assay in detecting microbial ingress in drinking water, different approaches were investigated, i.e. quantifying microbial ATP or applying reagents of different sensitivities to reduce measurement variations; however, none of these approaches contributed significantly in this respect. Compared to traditional microbiological methods, the ATP assay could detect wastewater and surface water in drinking water to a higher degree than total direct counts (TDCs), while both heterotrophic plate counts (HPC 22 °C and HPC 37 °C) and Colilert-18 (Escherichia coli and coliforms) were more sensitive than the ATP measurements, though with much longer response times. Continuous sampling combined with ATP measurements displays definite monitoring potential for microbial drinking water quality, since microbial ingress in drinking water can be detected in real-time with ATP measurements. The ability of the ATP assay to detect microbial ingress is influenced by both the ATP load from the contaminant itself and the ATP concentration in the specific drinking water. Consequently, a low ATP concentration of the specific drinking water facilitates a better detection of a potential contamination of the water supply with the ATP assay.

  3. Drainage-water travel times as a key factor for surface water contamination

    NARCIS (Netherlands)

    Groenendijk, P.; Eertwegh, van den G.A.P.H.

    2004-01-01

    The importance of the unsaturated zone as an inextricable part of the hydrologic cycle has long been recognized. The root zone and the unsaturated sub-surface domain are chemically and biologically the most active zones. The interrelationships between soil, subsoil and surface waters make it unreali

  4. Cholesterol enhances surface water diffusion of phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chi-Yuan; Kausik, Ravinath; Han, Songi, E-mail: songi@chem.ucsb.edu [Department of Chemistry and Biochemistry and Materials Research Laboratory, University of California, Santa Barbara, California 93106 (United States); Olijve, Luuk L. C. [Laboratory of Macromolecular and Organic Chemistry and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven (Netherlands)

    2014-12-14

    Elucidating the physical effect of cholesterol (Chol) on biological membranes is necessary towards rationalizing their structural and functional role in cell membranes. One of the debated questions is the role of hydration water in Chol-embedding lipid membranes, for which only little direct experimental data are available. Here, we study the hydration dynamics in a series of Chol-rich and depleted bilayer systems using an approach termed {sup 1}H Overhauser dynamic nuclear polarization (ODNP) NMR relaxometry that enables the sensitive and selective determination of water diffusion within 5–10 Å of a nitroxide-based spin label, positioned off the surface of the polar headgroups or within the nonpolar core of lipid membranes. The Chol-rich membrane systems were prepared from mixtures of Chol, dipalmitoyl phosphatidylcholine and/or dioctadecyl phosphatidylcholine lipid that are known to form liquid-ordered, raft-like, domains. Our data reveal that the translational diffusion of local water on the surface and within the hydrocarbon volume of the bilayer is significantly altered, but in opposite directions: accelerated on the membrane surface and dramatically slowed in the bilayer interior with increasing Chol content. Electron paramagnetic resonance (EPR) lineshape analysis shows looser packing of lipid headgroups and concurrently tighter packing in the bilayer core with increasing Chol content, with the effects peaking at lipid compositions reported to form lipid rafts. The complementary capability of ODNP and EPR to site-specifically probe the hydration dynamics and lipid ordering in lipid membrane systems extends the current understanding of how Chol may regulate biological processes. One possible role of Chol is the facilitation of interactions between biological constituents and the lipid membrane through the weakening or disruption of strong hydrogen-bond networks of the surface hydration layers that otherwise exert stronger repulsive forces, as reflected in

  5. Surface water data at Los Alamos National Laboratory: 1995 water year. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Barks, R. [ed.; Shaull, D.A.; Alexander, M.R.; Reynolds, R.P.

    1996-08-01

    The principle investigators collected and computed surface water discharge data from 15 stream-gaging stations that cover most of Los Alamos National Laboratory. The United States Department of Interior Geological Survey, Water Resources Division, operates two of the stations under a subcontract; these are identified in the station manuscripts. Included in this report are data from one seepage run conducted in Los Alamos Canyon during the 1995 water year.

  6. Isotopic Composition of Gaseous Elemental Mercury (Hg0) at Various Sites in Japan

    Science.gov (United States)

    Yamakawa, A.; Moriya, K.; Yoshinaga, J.

    2015-12-01

    Mercury (Hg) is a toxic heavy metal, which exists in various chemical forms in the environmental system. In the atmosphere, Hg exists in three forms (Hg0(g), Hg+2(g), and Hg(p)). Hg0(g) is the dominant species of atmospheric Hg, accounting for >95% of the total Hg in the atmosphere. Because Hg0(g) is highly volatile and has limited solubility in water, it cannot be easily removed by wet or dry deposition processes. Therefore, the residence time of Hg0(g) in the atmosphere is relatively long (1 to 2 years), allowing long-range transport from mercury emission source(s). Conversely, Hg+2(g) and Hg(p) are effectively removed from the atmosphere through wet and dry depositions. The determination of mercury source attribution using quantitative data is challenging because Hg0(g) may be deposited on an area upon oxidation to Hg+2(g) and associated with aerosols and particulates to form Hg(p) while the global cycling of Hg0(g). Over the last decade, the development of analytical methods of highly precise Hg isotopic measurements demonstrated mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) of Hg isotopes in environmental samples. For instance, MDF of Hg isotopes is thought to occur during various natural and industrial Hg transformations. MIF of Hg isotopes is observed during abiotic reduction, photochemical and non-photochemical, and physical and chemical processes. Such processes lead to differences in the Hg isotopic composition of different emission sources, both natural and anthropogenic, and atmospheric processes (i.e., transportation, oxidation/reduction, deposition, and reemission). Therefore, Hg isotopic compositions could be used to trace the sources and processes of atmospheric Hg. For securing the reliability and accuracy of atmospheric Hg isotope data, the methods of collection, pretreatment, and isotopic measurement for Hg0(g) were developed to obtain high recovery yield of samples with no Hg isotopic fractionation during each

  7. How water meets a hydrophobic surface: Reluctantly and with flucuations

    Science.gov (United States)

    Poynor Torigoe, Adele Nichole

    By definition hydrophobic substances hate water. Water placed on a hydrophobic surface will form a drop in order to minimize its contact area. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low density region forms near the surface. This depleted region would have implications in such diverse areas as colloidal self-assembly, and the boundary conditions of fluid flow. However, the literature still remains divided as to whether or not such a depleted region exists. To investigate the existence of this layer, we have employed three surface-sensitive techniques, time-resolved phase-modulated ellipsometry, surface plasmon resonance, and X-ray reflectivity. Both ellipsometry and X-ray reflectivity provide strong evidence for the low-density layer and illuminate unexpected temporal behavior. Using all three techniques, we found surprising fluctuations at the interface with a non-Gaussian distribution and a single characteristic time on the order of tenths of seconds. This information supports the idea that the boundary fluctuates with something akin to capillary waves. We have also investigated the dependence of the static and dynamic properties of the hydrophobic/water interface on variables such as temperature, contact angle, pH, dissolved gasses, and sample quality, among others, in a hope to discover the root of the controversy in the literature. We found that the depletion layer is highly dependent on temperature, contact angle and sample quality. This dependence might explain some of the discrepancies in the literature as different groups often use hydrophobic surfaces with different properties.

  8. Preliminary investigation of radon concentration in surface water and drinking water in Shenzhen City, South China.

    Science.gov (United States)

    Li, Ting; Wang, Nanping; Li, Shijun

    2015-11-01

    A radon survey in surface water and drinking water was conducted using a portable degassing system associated with an ionisation chamber AlphaGUARD (PQ2000) for understanding levels of dissolved radon ((222)Rn) concentration in different types of water sources and risk assessment of radon in drinking water in Shenzhen City (SC) with a population of 10 628 900 in 2013, Guangdong Province of China. The measurements show that arithmetic means ± standard deviations of radon ((222)Rn) concentration are 52.05 ± 6.64, 0.29 ± 0.26, 0.15 ± 0.23 and 0.37 ± 0.42 kBq m(-3) in spring water, surface water, large and small public water supplies, respectively. Only radon concentrations of two water samples collected in mountainous areas are more than 11.10 kBq m(-3), exceeding the limit of radon concentration in drinking water stipulated by the national standard of China (GB5749-2006). The annual effective doses due to radon in drinking water were also calculated. The investigation suggests that there are no risks caused by radon in the drinking water in SC.

  9. Observation of dynamic water microadsorption on Au surface

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiaokang, E-mail: xiaokang.huang@tqs.com; Gupta, Gaurav; Gao, Weixiang; Tran, Van; Nguyen, Bang; McCormick, Eric; Cui, Yongjie; Yang, Yinbao; Hall, Craig; Isom, Harold [TriQuint Semiconductor, Inc., 500 W Renner Road, Richardson, Texas 75080 (United States)

    2014-05-15

    Experimental and theoretical research on water wettability, adsorption, and condensation on solid surfaces has been ongoing for many decades because of the availability of new materials, new detection and measurement techniques, novel applications, and different scales of dimensions. Au is a metal of special interest because it is chemically inert, has a high surface energy, is highly conductive, and has a relatively high melting point. It has wide applications in semiconductor integrated circuitry, microelectromechanical systems, microfluidics, biochips, jewelry, coinage, and even dental restoration. Therefore, its surface condition, wettability, wear resistance, lubrication, and friction attract a lot of attention from both scientists and engineers. In this paper, the authors experimentally investigated Au{sub 2}O{sub 3} growth, wettability, roughness, and adsorption utilizing atomic force microscopy, scanning electron microscopy, reflectance spectrometry, and contact angle measurement. Samples were made using a GaAs substrate. Utilizing a super-hydrophilic Au surface and the proper surface conditions of the surrounding GaAs, dynamic microadsorption of water on the Au surface was observed in a clean room environment. The Au surface area can be as small as 12 μm{sup 2}. The adsorbed water was collected by the GaAs groove structure and then redistributed around the structure. A model was developed to qualitatively describe the dynamic microadsorption process. The effective adsorption rate was estimated by modeling and experimental data. Devices for moisture collection and a liquid channel can be made by properly arranging the wettabilities or contact angles of different materials. These novel devices will be very useful in microfluid applications or biochips.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-07-01

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

  11. Transitions for fipronil quant in surface water, Summary of Current Fipronil Water Data and Water Data for WWTPs

    Data.gov (United States)

    U.S. Environmental Protection Agency — Comparison of fipronil sources in North Carolina surface water and identification of a novel fipronil transformation product in recycled wastewater. This dataset is...

  12. Experimental Study of Water Droplet Vaporization on Nanostructured Surfaces

    Science.gov (United States)

    Padilla, Jorge, Jr.

    This dissertation summarizes results of an experimental exploration of heat transfer during vaporization of a water droplet deposited on a nanostructured surface at a temperature approaching and exceeding the Leidenfrost point for the surface and at lower surface temperatures 10-40 degrees C above the saturated temperature of the water droplet at approximately 101 kPa. The results of these experiments were compared to those performed on bare smooth copper and aluminum surfaces in this and other studies. The nanostructured surfaces were composed of a vast array of zinc oxide (ZnO) nanocrystals grown by hydrothermal synthesis on a smooth copper substrate having an average surface roughness of approximately 0.06 micrometer. Various nanostructured surface array geometries were produced on the copper substrate by performing the hydrothermal synthesis for 4, 10 and 24 hours. The individual nanostructures were randomly-oriented and, depending on hydrothermal synthesis time, had a mean diameter of about 500-700 nm, a mean length of 1.7-3.3 micrometers,and porosities of approximately 0.04-0.58. Surface wetting was characterized by macroscopic measurements of contact angle based on the droplet profile and calculations based on measurements of liquid film spread area. Scanning electron microscope imaging was used to document the nanoscale features of the surface before and after the experiments. The nanostructured surfaces grown by hydrothermal synthesis for 4 and 24 hours exhibited contact angles of approximately 10, whereas the surfaces grown for 10 hours were superhydrophilic, exhibiting contact angles typically less than 3 degrees. In single droplet deposition experiments at 101 kPa, a high-speed video camera was used to document the droplet-surface interaction. Distilled and degassed water droplets ranging in size from 2.5-4.0 mm were deposited onto the surface from heights ranging from approximately 0.2-8.1 cm, such that Weber numbers spanned a range of approximately 0

  13. Evaluation of arsenic and other physico-chemical parameters of surface and ground water of Jamshoro, Pakistan

    Energy Technology Data Exchange (ETDEWEB)

    Baig, Jameel Ahmed, E-mail: jab_mughal@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Kazi, Tasneem Gul, E-mail: tgkazi@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Arain, Muhammad Balal, E-mail: bilal_KU2004@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Afridi, Hassan Imran, E-mail: hassanimranafridi@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Kandhro, Ghulam Abbas, E-mail: gakandhro@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Sarfraz, Raja Adil, E-mail: rajaadilsarfraz@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Jamal, Muhammad Khan, E-mail: mkhanjamali@yahoo.com [Government Degree College Usta Muhammad, Balochistan 08300 (Pakistan); Shah, Abdul Qadir, E-mail: aqshah07@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan)

    2009-07-30

    Arsenic contamination in water has caused severe health problems around the world. The purpose of this study was to evaluate the geological and anthropogenic aspects of As pollution in surface and groundwater resources of Jamshoro Sindh, Pakistan. Hydride generator atomic absorption spectrophotometry (HG-AAS) is employed for the determination of arsenic in water samples, with detection limit of 0.02 {mu}g l{sup -1}. Arsenic concentrations in surface and underground water range from 3.0 to 50.0, and 13 to 106 {mu}g l{sup -1}, respectively. In most of the water samples As levels exceeded the WHO provisional guideline values 10 {mu}g l{sup -1}. The high level of As in under study area may be due to widespread water logging from Indus river irrigation system which causes high saturation of salts in this semi-arid region and lead to enrichment of As in shallow groundwater. Among the physico-chemical parameters, electrical conductivity, Na{sup +}, K{sup +}, and SO{sub 4}{sup 2-} were found to be higher in surface and ground water, while elevated levels of Ca{sup 2+} and Cl{sup -} were detected only in ground water than WHO permissible limit. The high level of iron was observed in ground water, which is a possible source of As enrichment in the study area. The multivariate technique (cluster analysis) was used for the elucidation of high, medium and low As contaminated areas. It may be concluded that As originate from coal combustion at brick factories and power generation plants, and it was mobilized promotionally by the alkaline nature of the understudy groundwater samples.

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

    Science.gov (United States)

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

    2015-08-01

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

  15. Droplet impinging behavior on surfaces: Part II - Water on aluminium and cast iron surfaces

    Science.gov (United States)

    Sangavi, S.; Balaji, S.; Mithran, N.; Venkatesan, M.

    2016-09-01

    Droplet cooling of metal surfaces is an important area of research in industrial applications such as material quenching, nozzle spraying, etc. Fluids (water) act as an excellent agent in heat transfer to remove excess heat in various processes by convection and conduction. Such cooling process varies the material properties. The bubbles formed during droplet impinging on the surface act as heat sink and causes variation of height and spreading radius of the droplet with increase in temperature. In the present work, an experimental study of the droplet impinging behavior on Aluminium and Cast iron surfaces is reported. The water droplets are made to fall on the surface of the specimens from a specific height, which also influences the spreading radius. The effect of temperature on droplet height and droplet spreading radius is detailed.

  16. Ionization dynamics of water dimer on ice surface

    Science.gov (United States)

    Tachikawa, Hiroto

    2016-05-01

    The solid surface provides an effective two-dimensional reaction field because the surface increases the encounter probability of bi-molecular collision reactions. Also, the solid surface stabilizes a reaction intermediate because the excess energy generated by the reaction dissipates into the bath modes of surface. The ice surface in the universe is one of the two dimensional reaction fields. However, it is still unknown how the ice surface affects to the reaction mechanism. In the present study, to elucidate the specific property of the ice surface reaction, ionization dynamics of water dimer adsorbed on the ice surface was theoretically investigated by means of direct ab-initio molecular dynamics (AIMD) method combined with ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) technique, and the result was compared with that of gas phase reaction. It was found that a proton is transferred from H2O+ to H2O within the dimer and the intermediate complex H3O+(OH) is formed in both cases. However, the dynamic features were different from each other. The reaction rate of the proton transfer on the ice surface was three times faster than that in the gas phase. The intermediate complex H3O+(OH) was easily dissociated to H3O+ and OH radical on the ice surface, and the lifetime of the complex was significantly shorter than that of gas phase (100 fs vs. infinite). The reason why the ice surface accelerates the reaction was discussed in the present study.

  17. Pesticide monitoring in surface water and groundwater using passive samplers

    Science.gov (United States)

    Kodes, V.; Grabic, R.

    2009-04-01

    Passive samplers as screening devices have been used within a czech national water quality monitoring network since 2002 (SPMD and DGT samplers for non polar substances and metals). The passive sampler monitoring of surface water was extended to polar substances, in 2005. Pesticide and pharmaceutical POCIS samplers have been exposed in surface water at 21 locations and analysed for polar pesticides, perfluorinated compounds, personal care products and pharmaceuticals. Pesticide POCIS samplers in groundwater were exposed at 5 locations and analysed for polar pesticides. The following active substances of plant protection products were analyzed in surface water and groundwater using LC/MS/MS: 2,4,5-T, 2,4-D, Acetochlor, Alachlor, Atrazine, Atrazine_desethyl, Azoxystrobin, Bentazone, Bromacil, Bromoxynil, Carbofuran, Clopyralid, Cyanazin, Desmetryn, Diazinon, Dicamba, Dichlobenil, Dichlorprop, Dimethoat, Diuron, Ethofumesate, Fenarimol, Fenhexamid, Fipronil, Fluazifop-p-butyl, Hexazinone, Chlorbromuron, Chlorotoluron, Imazethapyr, Isoproturon, Kresoxim-methyl, Linuron, MCPA, MCPP, Metalaxyl, Metamitron, Methabenzthiazuron, Methamidophos, Methidathion, Metobromuron, Metolachlor, Metoxuron, Metribuzin, Monolinuron, Nicosulfuron, Phorate, Phosalone, Phosphamidon, Prometryn, Propiconazole, Propyzamide, Pyridate, Rimsulfuron, Simazine, Tebuconazole, Terbuthylazine, Terbutryn, Thifensulfuron-methyl, Thiophanate-methyl and Tri-allate. The POCIS samplers performed very well being able to provide better picture than grab samples. The results show that polar pesticides and also perfluorinated compounds, personal care products and pharmaceuticals as well occur in hydrosphere of the Czech republic. Acknowledgment: Authors acknowledge the financial support of grant No. 2B06095 by the Ministry of Education, Youth and Sports.

  18. Analysis of water microdroplet condensation on silicon surfaces

    Science.gov (United States)

    Honda, Takuya; Fujimoto, Kenya; Yoshimoto, Yuta; Mogi, Katsuo; Kinefuchi, Ikuya; Sugii, Yasuhiko; Takagi, Shu; Univ. of Tokyo Team; Tokyo Inst. of Tech. Team

    2016-11-01

    We observed the condensation process of water microdroplets on flat silicon (100) surfaces by means of the sequential visualization of the droplets using an environmental scanning electron microscope. As previously reported for nanostructured surfaces, the condensation process of water microdroplets on the flat silicon surfaces also exhibits two modes: the constant base (CB) area mode and the constant contact angle (CCA) mode. In the CB mode, the contact angle increases with time while the base diameter is constant. Subsequently, in the CCA mode, the base diameter increases with time while the contact angle remains constant. The dropwise condensation model regulated by subcooling temperature does not reproduce the experimental results. Because the subcooling temperature is not constant in the case of a slow condensation rate, this model is not applicable to the condensation of the long time scale ( several tens of minutes). The contact angle of water microdroplets ( several μm) tended to be smaller than the macro contact angle. Two hypotheses are proposed as the cause of small contact angles: electrowetting and the coalescence of sub- μm water droplets.

  19. The Character of the Solar Wind, Surface Interactions, and Water

    Science.gov (United States)

    Farrell, William M.

    2011-01-01

    We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

  20. Water contact angles and hysteresis of polyamide surfaces.

    Science.gov (United States)

    Extrand, C W

    2002-04-01

    The wetting behavior of a series of aliphatic polyamides (PAs) has been examined. PAs with varying amide content and polyethylene (PE) were molded against glass to produce surfaces with similar roughness. After cleaning, chemical composition of the surfaces was verified with X-ray photoelectron spectroscopy. Advancing and receding contact angles were measured from small sessile water drops. Contact angles decreased with amide content while hysteresis increased. Hysteresis arose primarily from molecular interactions between the contact liquid and the solid substrates, rather than moisture absorption, variations in crystallinity, surface deformation, roughness, reorientation of amide groups, or surface contamination. Free energies of hysteresis were calculated from contact angles. For PE, which is composed entirely of nonpolar methylene groups, free energies were equivalent to the strength of dispersive van der Waals bonds. For PAs, free energies corresponded to fractional contributions from the dispersive methylene groups and polar amide groups.

  1. Nonlinear Acoustics at the Air-Water Free Surface

    Science.gov (United States)

    Pree, Seth; Naranjo, Brian; Putterman, Seth

    2016-11-01

    According to linear acoustics, airborne sound incident on a water surface transmits only a tenth of a percent of its energy. This difficulty of transmitting energy across the water surface limits the feasibility of standoff ultrasound imaging. We propose to overcome this long standing problem by developing new methods of coupling into the medium at standoff. In particular, we believe that the acoustic nonlinearity of both the air and the medium may yield a range of effects in the vicinity of the surface permitting an efficient transmission of ultrasound from the air into the medium. The recent commercial availability of parametric speakers that deliver modulated 100kHz ultrasound at 135dB to nonlinearly generate music at 95dB provides an interesting platform with which to revisit the transmission of sound across acoustic impedance mismatches. We show results of experimental studies of the behavior of the air-water free surface when subjected to large amplitude acoustic pressures from the air. This work was supported by the ARO STIR program.

  2. 46 CFR 53.01-5 - Scope (modifies HG-100).

    Science.gov (United States)

    2010-10-01

    ... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING HEATING BOILERS General Requirements § 53.01-5 Scope (modifies HG-100). (a) The regulations in this part apply to steam heating boilers, hot water boilers (which include hot water heating boilers and hot water supply...

  3. Sensors and OBIA synergy for operational monitoring of surface water

    Science.gov (United States)

    Masson, Eric; Thenard, Lucas

    2010-05-01

    This contribution will focus on combining Object Based Image Analysis (i.e. OBIA with e-Cognition 8) and recent sensors (i.e. Spot 5 XS, Pan and ALOS Prism, Avnir2, Palsar) to address the technical feasibility for an operational monitoring of surface water. Three cases of river meandering (India), flood mapping (Nepal) and dam's seasonal water level monitoring (Morocco) using recent sensors will present various application of surface water monitoring. The operational aspect will be demonstrated either by sensor properties (i.e. spatial resolution and bandwidth), data acquisition properties (i.e. multi sensor, return period and near real-time acquisition) but also with OBIA algorithms (i.e. fusion of multi sensors / multi resolution data and batch processes). In the first case of river meandering (India) we will address multi sensor and multi date satellite acquisition to monitor the river bed mobility within a floodplain using an ALOS dataset. It will demonstrate the possibility of an operational monitoring system that helps the geomorphologist in the analysis of fluvial dynamic and sediment budget for high energy rivers. In the second case of flood mapping (Nepal) we will address near real time Palsar data acquisition at high spatial resolution to monitor and to map a flood extension. This ALOS sensor takes benefit both from SAR and L band properties (i.e. atmospheric transparency, day/night acquisition, low sensibility to surface wind). It's a real achievement compared to optical imagery or even other high resolution SAR properties (i.e. acquisition swath, bandwidth and data price). These advantages meet the operational needs set by crisis management of hydrological disasters but also for the implementation of flood risk management plans. The last case of dam surface water monitoring (Morocco) will address an important issue of water resource management in countries affected by water scarcity. In such countries water users have to cope with over exploitation

  4. Three-dimensional topographies of water surface dimples formed by superhydrophobic water strider legs

    Science.gov (United States)

    Yin, W.; Zheng, Y. L.; Lu, H. Y.; Zhang, X. J.; Tian, Y.

    2016-10-01

    A water strider has a remarkable capability to stand and walk freely on water. Supporting forces of a water strider and a bionic robot have been calculated from the side view of pressed depth of legs to reconstruct the water surface dimples. However, in situ measurements of the multiple leg forces and significantly small leg/water contact dimples have not been realized yet. In this study, a shadow method was proposed to reconstruct the in situ three-dimensional topographies of leg/water contact dimples and their corresponding supporting forces. Results indicated that the supporting forces were affected by the depth, width, and length of the dimple, and that the maximum dimple depth was not proportional to the supporting forces. The shadow method also has advantages in disclosing tiny supporting force of legs in their subtle actions. These results are helpful for understanding the locomotion principles of water-walking insects and the design of biomimetic aquatic devices.

  5. Presence and risk assessment of pharmaceuticals in surface water and drinking water

    DEFF Research Database (Denmark)

    Sanderson, Hans

    2011-01-01

    Trace amounts of pharmaceuticals have been detected in surface waters in the nano- to microgram per liter range, and in drinking water in the nanogram/L range. The environmental risks of pharmaceuticals in surface waters have been evaluated and generally found to be low if the wastewater is treated...... before release to the environment. The human health risks of trace amounts of pharmaceuticals in drinking water have however not been evaluated in any great depth. Preliminary screening level assessments suggest risk to be low – but the public and decision-makers are concerned and would like the matter...... investigated more thoroughly, especially with regards to mixture effects, chronic long-term effects and sensitive sub-populations. The World Health Organization is currently evaluating the need for credible health based guidance associated with low concentrations of pharmaceuticals in drinking water....

  6. Presence and risk assessment of pharmaceuticals in surface water and drinking water

    DEFF Research Database (Denmark)

    Sanderson, Hans

    2011-01-01

    Trace amounts of pharmaceuticals have been detected in surface waters in the nano- to microgram per liter range, and in drinking water in the nanogram/L range. The environmental risks of pharmaceuticals in surface waters have been evaluated and generally found to be low if the wastewater is treated...... before release to the environment. The human health risks of trace amounts of pharmaceuticals in drinking water have however not been evaluated in any great depth. Preliminary screening level assessments suggest risk to be low – but the public and decision-makers are concerned and would like the matter...... investigated more thoroughly, especially with regards to mixture effects, chronic long-term effects and sensitive sub-populations. The World Health Organization is currently evaluating the need for credible health based guidance associated with low concentrations of pharmaceuticals in drinking water....

  7. A "First Principles" Potential Energy Surface for Liquid Water from VRT Spectroscopy of Water Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, N; Leforestier, C; Saykally, R J

    2004-05-25

    We present results of gas phase cluster and liquid water simulations from the recently determined VRT(ASP-W)III water dimer potential energy surface. VRT(ASP-W)III is shown to not only be a model of high ''spectroscopic'' accuracy for the water dimer, but also makes accurate predictions of vibrational ground-state properties for clusters up through the hexamer. Results of ambient liquid water simulations from VRT(ASP-W)III are compared to those from ab initio Molecular Dynamics, other potentials of ''spectroscopic'' accuracy, and to experiment. The results herein represent the first time that a ''spectroscopic'' potential surface is able to correctly model condensed phase properties of water.

  8. Equations of atrazine transfer from agricultural land to surface water

    Science.gov (United States)

    Cann, C.

    1995-08-01

    As atrazine, the most widely used herbicide in agriculture, makes problems for water supply, the Cemagref study its transfer from lands to surface water. On a small basin of central Brittany, soil and water contents of atrazine have been monitored from 1991 to 1994. Data show that atrazine content of the top layer of soil decreases slowly after spreading. Degradation works more than leaching for this decrease. There is always atrazine in the water of the stream at the outlet of the basin. The concentration of atrazine in water increase sharply in every flood and then decrease slowly. The maximum level of concentration in each flood is very well correlated with the ratio of maximum discharge to the base flow. It means that quick superficial flow of water is the most contaminated water. It brings most of the total flow of atrazine which can be measured in the stream. However, this flow represent only a very small part of the spread atrazine on the basin: less than 1%.

  9. Biological methods used to assess surface water quality

    Directory of Open Access Journals (Sweden)

    Szczerbiñska Natalia

    2015-12-01

    Full Text Available In accordance with the guidelines of the Water Framework Directive 2000/60 (WFD, both ecological and chemical statuses determine the assessment of surface waters. The profile of ecological status is based on the analysis of various biological components, and physicochemical and hydromorphological indicators complement this assessment. The aim of this article is to present the biological methods used in the assessment of water status with a special focus on bioassay, as well as to provide a review of methods of monitoring water status. Biological test methods include both biomonitoring and bioanalytics. Water biomonitoring is used to assess and forecast the status of water. These studies aim to collect data on water pollution and forecast its impact. Biomonitoring uses organisms which are characterized by particular vulnerability to contaminants. Bioindicator organisms are algae, fungi, bacteria, larval invertebrates, cyanobacteria, macroinvertebrates, and fish. Bioanalytics is based on the receptors of contaminants that can be biologically active substances. In bioanalytics, biosensors such as viruses, bacteria, antibodies, enzymes, and biotests are used to assess degrees of pollution.

  10. The impact of land use on microbial surface water pollution.

    Science.gov (United States)

    Schreiber, Christiane; Rechenburg, Andrea; Rind, Esther; Kistemann, Thomas

    2015-03-01

    Our knowledge relating to water contamination from point and diffuse sources has increased in recent years and there have been many studies undertaken focusing on effluent from sewage plants or combined sewer overflows. However, there is still only a limited amount of microbial data on non-point sources leading to diffuse pollution of surface waters. In this study, the concentrations of several indicator micro-organisms and pathogens in the upper reaches of a river system were examined over a period of 16 months. In addition to bacteria, diffuse pollution caused by Giardia lamblia and Cryptosporidium spp. was analysed. A single land use type predestined to cause high concentrations of all microbial parameters could not be identified. The influence of different land use types varies between microbial species. The microbial concentration in river water cannot be explained by stable non-point effluent concentrations from different land use types. There is variation in the ranking of the potential of different land use types resulting in surface water contamination with regard to minimum, median and maximum effects. These differences between median and maximum impact indicate that small-scale events like spreading manure substantially influence the general contamination potential of a land use type and may cause increasing micro-organism concentrations in the river water by mobilisation during the next rainfall event. Copyright © 2014 Elsevier GmbH. All rights reserved.

  11. Algae form brominated organic compounds in surface waters

    Energy Technology Data Exchange (ETDEWEB)

    Huetteroth, A.; Putschew, A.; Jekel, M. [Tech. Univ. Berlin (Germany)

    2004-09-15

    Monitoring of organic halogen compounds, measured as adsorbable organic bromine (AOBr) revealed seasonal high concentrations of organic bromine compounds in a surface water (Lake Tegel, Berlin, Germany). Usually, in late summer, concentrations are up to five times higher than during the rest of the year. The AOBr of the lake inflows (throughout the year less then 6 {mu}g/L) were always lower then those in the lake, which indicates a production of AOBr in the lake. A correlation of the AOBr and chlorophyll-a concentration (1) in the lake provides first evidence for the influence of phototrophic organisms. The knowledge of the natural production of organohalogens is relatively recent. Up to now there are more then 3800 identified natural organohalogen compounds that have been detected in marine plants, animals, and bacteria and also in terrestrial plants, fungi, lichen, bacteria, insects, some higher animals, and humans. Halogenated organic compounds are commonly considered to be of anthropogenic origin; derived from e.g. pharmaceuticals, herbicides, fungicides, insecticides, flame retardants, intermediates in organic synthesis and solvents. Additionally they are also produced as by-products during industrial processes and by waste water and drinking water disinfection. Organohalogen compounds may be toxic, persistent and/or carcinogenic. In order to understand the source and environmental relevance of naturally produced organobromine compounds in surface waters, the mechanism of the formation was investigated using batch tests with lake water and algae cultures.

  12. Surface-Water and Ground-Water Interactions in the Central Everglades, Florida

    Science.gov (United States)

    Harvey, Judson W.; Newlin, Jessica T.; Krest, James M.; Choi, Jungyill; Nemeth, Eric A.; Krupa, Steven L.

    2004-01-01

    Recharge and discharge are hydrological processes that cause Everglades surface water to be exchanged for subsurface water in the peat soil and the underlying sand and limestone aquifer. These interactions are thought to be important to water budgets, water quality, and ecology in the Everglades. Nonetheless, relatively few studies of surface water and ground water interactions have been conducted in the Everglades, especially in its vast interior areas. This report is a product of a cooperative investigation conducted by the USGS and the South Florida Water Management District (SFWMD) aimed at developing and testing techniques that would provide reliable estimates of recharge and discharge in interior areas of WCA-2A (Water Conservation Area 2A) and several other sites in the central Everglades. The new techniques quantified flow from surface water to the subsurface (recharge) and the opposite (discharge) using (1) Darcy-flux calculations based on measured vertical gradients in hydraulic head and hydraulic conductivity of peat; (2) modeling transport through peat and decay of the naturally occurring isotopes 224Ra and 223Ra (with half-lives of 4 and 11 days, respectively); and (3) modeling transport and decay of naturally occurring and 'bomb-pulse' tritium (half-life of 12.4 years) in ground water. Advantages and disadvantages of each method for quantifying recharge and discharge were compared. In addition, spatial and temporal variability of recharge and discharge were evaluated and controlling factors identified. A final goal was to develop appropriately simplified (that is, time averaged) expressions of the results that will be useful in addressing a broad range of hydrological and ecological problems in the Everglades. Results were compared with existing information about water budgets from the South Florida Water Management Model (SFWMM), a principal tool used by the South Florida Water Management District to plan many of the hydrological aspects of the

  13. HgCdTe Surface Study Program

    Science.gov (United States)

    1982-09-01

    Spectroscopy, in: Optical Properties of Solids , Ed. Berlin, 1976). B.O. Seraphin (North-Holland, Amsterdam, 1976). [31 S.P. Kowalczyk and J.T. Cheung, J... Optical Properties of Solids -New Developments, work edited by B. 0. Seraphin (North-Holland, Amsterdam, This work was supported by U. S. Defense Ad

  14. 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.

  15. Input dynamics of pesticide transformation products into surface water

    Science.gov (United States)

    Kern, Susanne; Singer, Heinz; Hollender, Juliane; Schwarzenbach, René P.; Fenner, Kathrin

    2010-05-01

    Some pesticide transformation products have been observed to occur in higher concentrations and more frequently than the parent active pesticide in surface water and groundwater. These products are often more mobile and sometimes more stable than the parent pesticide. If they also represent the major product into which the parent substance is transformed, these transformation products may dominate observed pesticide occurrences in surface water and groundwater. Their potential contribution to the overall risk to the aquatic environment caused by the use of the parent pesticide should therefore not be neglected in chemical risk and water quality assessments. The same is true for transformation products of other compound classes that might reach the soil environment, such as veterinary pharmaceuticals. However, the fate and input pathways of transformation products of soil-applied chemicals into surface water are not yet well understood, which largely prevents their appropriate inclusion into chemical risk and water quality assessments. Here, we studied whether prioritization methods based on available environmental fate data from pesticide registration dossiers in combination with basic fate models could help identify transformation products which can be found in relevant concentrations in surface and groundwater and which should therefore be included into monitoring programs. A three-box steady state model containing air, soil, and surface water compartments was used to predict relative inputs of pesticide transformation products into surface waters based on their physico-chemical and environmental fate properties. The model predictions were compared to monitoring data from a small Swiss river located in an intensely agricultural catchment (90 km2) which was flow-proportionally sampled from May to October 2008 and screened for 74 pesticides as well as 50 corresponding transformation products. Sampling mainly occurred during high discharge, but additional samples

  16. SO2/Hg removal from flue gas by dry FGD

    Institute of Scientific and Technical Information of China (English)

    Wang Fan; Wang Hongmei; Zhang Fan; Zhu Jinwei; Tian Gang; Liu Yu; Mao Jixian

    2012-01-01

    To study the mechanism of SO2 and Hg removal from flue gas,an experimental packed bed reactor was designed to simulate the dry FGD,where a mixture of lime and fly ash in ratio 1∶3 w/w was used as the SO2 and Hg sorbent,and steam at temperature of 100 ℃ was applied for activation of the sorbent,while the activation time set to 20 min.The experimental factors including the SO2/Hg sorbent characteristics,50% breakthrough time for SO2/Hg removal,sorbent packed bed depth and reaction temperature were investigated.The experimental results show that after steam activation,the BET specific surface area and specific pore volume increased from 37.8 to 45.5 m2/g and from 0.42 to 0.51 cm3/g,respectively.With activation of the sorbent by steam,the 50% breakthrough times of SO2 and Hg removal increased from 34 to 42 min and from 23 to 45 min,respectively.When the packed bed depth was increased from 5 to 25 mm,the 50% breakthrough times for Hg and SO2 removal increased from 12 to 52 min and from 6 to 47 min,respectively.With the increase of the reaction temperature,the 50% breakthrough of SO2/Hg removal decreased accordingly.Steam activation can efficiently improve SO2/Hg removal simultaneously.

  17. The Whitham Equation as a Model for Surface Water Waves

    CERN Document Server

    Moldabayev, Daulet; Dutykh, Denys

    2014-01-01

    The Whitham equation was proposed as an alternate model equation for the simplified description of uni-directional wave motion at the surface of an inviscid fluid. As the Whitham equation incorporates the full linear dispersion relation of the water wave problem, it is thought to provide a more faithful description of shorter waves of small amplitude than traditional long wave models such as the KdV equation. In this work, we identify a scaling regime in which the Whitham equation can be derived from the Hamiltonian theory of surface water waves. The Whitham equation is integrated numerically, and it is shown that the equation gives a close approximation of inviscid free surface dynamics as described by the Euler equations. The performance of the Whitham equation as a model for free surface dynamics is also compared to two standard free surface models: the KdV and the BBM equation. It is found that in a wide parameter range of amplitudes and wavelengths, the Whitham equation performs on par with or better tha...

  18. Synthesis of amino functionalized magnetic graphenes composite material and its application to remove Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) from contaminated water

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaoyao [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Du, Bin, E-mail: dubin61@gmail.com [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Wei, Qin, E-mail: sdjndxwq@163.com [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Yang, Jian [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Hu, Lihua [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Yan, Liangguo; Xu, Weiying [School of Resources and Environment, University of Jinan, Jinan 250022 (China)

    2014-08-15

    Highlights: • Graphenes magnetic composite nanoparticles (Fe{sub 3}O{sub 4}-GS) were used to adsorb metal ions. • The adsorption of metal ions onto Fe{sub 3}O{sub 4}-GS could be well interpreted by the Freundlich equation. • The adsorption of metal ions onto Fe{sub 3}O{sub 4}-GS fit pseudo-second order kinetic model. • Thermodynamic studies illustrated that the adsorption process was endothermic and spontaneous in nature. - Abstract: In the present study, a kind of graphenes magnetic material (Fe{sub 3}O{sub 4}-GS) was prepared by compositing graphene sheet with ferroferric oxide, and shown to be effictive for removing Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) ions from aqueous solution. The synthesized sorbent was characterized by SEM, TEM, FTIR, XRD, XPS and BET, respectively. The pH{sub ZPC} value of the sorbent was estimated to be 3.5 by alkaline-titration methods. Fe{sub 3}O{sub 4}-GS can be simply recovered from water with magnetic separation at low magnetic field within one minute. The sorption capacities of the metals were 17.29, 27.95, 23.03, 27.83 and 22.07 mg g{sup −1} for Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II), respectively. Kinetic data showed good correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data of all the heavy metal ions. It was found that the metals sorption was accomplished mainly via chelation or ion exchange. The results of thermodynamic studies illustrate that the adsorption process was endothermic and spontaneous in nature.

  19. Theoretical investigation of water formation on Rh and Pt Surfaces

    Science.gov (United States)

    Wilke, Steffen; Natoli, Vincent; Cohen, Morrel H.

    2000-06-01

    Catalytic water formation from adsorbed H and O adatoms is a fundamental reaction step in a variety of technologically important reactions involving organic molecules. In particular, the water-formation rate determines the selectivity of the catalytic partial oxidation of methane to syngas. In this report we present a theoretical investigation of the potential-energy diagram for water formation from adsorbed O and H species on Rh(111) and Pt(111) surfaces. The study is based on accurate first-principles calculations applying density-functional theory. Our results are compared to the potential-energy diagram for this reaction inferred from experimental data by Hickman and Schmidt [AIChE. J. 39, 1164 (1993)]. The calculations essentially reproduce the scheme of Hickman and Schmidt for water formation on Rh(111) with the important difference that the OH molecule is significantly more stable than assumed by Hickman and Schmidt. On Pt(111) surfaces, however, the calculations predict a barrier to OH formation very similar to that found on Rh(111). In particular, the calculated barrier to OH formation of about 20 kcal/mol seems to contradict the small 2.5 kcal/mol barrier assumed in the Hickman-Schmidt scheme and the observed large rate of water formation on Pt. A possible explanation for the apparent discrepancy between the large calculated barrier for OH formation on Pt and the experimentally observed rapid formation of water even at low temperatures is that the active sites for water formation on Pt are at "defect" sites and not on the ideally flat terraces. A similar conclusion has been reached by Verheij and co-workers [Surf. Sci. 371, 100 (1997); Chem. Phys. Lett. 174, 449 (1990); Surf. Sci. 272, 276 (1991)], who did detailed experimental work on water formation on Pt surfaces. Analyzing our results, we develop an explicit picture of the interaction processes governing the formation of OH groups. This picture rationalizes the calculated weak dependence of OH

  20. Simultaneous Removal of Hg(II and Phenol Using Functionalized Activated Carbon Derived from Areca Nut Waste

    Directory of Open Access Journals (Sweden)

    Lalhmunsiama

    2017-07-01

    Full Text Available Areca nut waste was utilized to obtain high surface area activated carbon (AC, and it was further functionalized with succinic anhydride under microwave irradiation. The surface morphology and surface functional groups of the materials were discussed with the help of scanning electron microscope(SEM images and fourier transform infra-red (FT-IR analysis. The specific surface area of the AC and functionalized-AC was obtained by the Brunauer-Emmett-Teller (BET method, and found to be 367.303 and 308.032 m2/g, respectively. Batch experiments showed that higher pH favoured the removal of Hg(II, whereas the phenol removal was slightly affected by the changes in the solution pH. The kinetic data followed pseudo-first order kinetic model, and intra-particle diffusion played a significant role in the removal of both pollutants. The maximum sorption capacity of Hg(II and phenol were evaluated using Langmuir adsorption isotherms, and found to be 11.23 and 5.37 mg/g, respectively. The removal of Hg(II was significantly suppressed in the presence of chloride ions due to the formation of a HgCl2 species. The phenol was specifically adsorbed, forming the donor–acceptor complexes or π–π electron interactions at the surface of the solid. Further, a fixed-bed column study was conducted for both Hg(II and phenol. The loading capacity of the column was estimated using the nonlinear Thomas equation, and found to be 2.49 and 2.70 mg/g, respectively. Therefore, the study showed that functionalized AC obtained from areca nut waste could be employed as a sustainable adsorbent for the simultaneous removal of Hg(II and phenol from polluted water.

  1. Surface Analysis of Metal Materials After Water Jet Abrasive Machining

    Directory of Open Access Journals (Sweden)

    Pavel Polák

    2015-01-01

    Full Text Available In this article, we deal with a progressive production technology using the water jet cutting technology with the addition of abrasives for material removal. This technology is widely used in cutting various shapes, but also for the technology of machining such as turning, milling, drilling and cutting of threads. The aim of this article was to analyse the surface of selected types of metallic materials after abrasive machining, i.e. by assessing the impact of selected machining parameters on the surface roughness of metallic materials.

  2. Shallow Alluvial Aquifer Ground Water System and Surface Water/Ground Water Interaction, Boulder Creek, Boulder, Colorado

    Science.gov (United States)

    Babcock, K. P.; Ge, S.; Crifasi, R. R.

    2006-12-01

    Water chemistry in Boulder Creek, Colorado, shows significant variation as the Creek flows through the City of Boulder [Barber et al., 2006]. This variation is partially due to ground water inputs, which are not quantitatively understood. The purpose of this study is (1) to understand ground water movement in a shallow alluvial aquifer system and (2) to assess surface water/ground water interaction. The study area, encompassing an area of 1 mi2, is located at the Sawhill and Walden Ponds area in Boulder. This area was reclaimed by the City of Boulder and Boulder County after gravel mining operations ceased in the 1970's. Consequently, ground water has filled in the numerous gravel pits allowing riparian vegetation regrowth and replanting. An integrated approach is used to examine the shallow ground water and surface water of the study area through field measurements, water table mapping, graphical data analysis, and numerical modeling. Collected field data suggest that lateral heterogeneity exists throughout the unconsolidated sediment. Alluvial hydraulic conductivities range from 1 to 24 ft/day and flow rates range from 0.01 to 2 ft/day. Preliminary data analysis suggests that ground water movement parallels surface topography and does not noticeably vary with season. Recharge via infiltrating precipitation is dependent on evapotranspiration (ET) demands and is influenced by preferential flow paths. During the growing season when ET demand exceeds precipitation rates, there is little recharge; however recharge occurs during cooler months when ET demand is insignificant. Preliminary data suggest that the Boulder Creek is gaining ground water as it traverses the study area. Stream flow influences the water table for distances up to 400 feet. The influence of stream flow is reflected in the zones relatively low total dissolved solids concentration. A modeling study is being conducted to synthesize aquifer test data, ground water levels, and stream flow data. The

  3. Gold Nanoparticles-Based Localized Surface Plasmon Resonance Scattering Analysis Method for the Determination of Trace Amounts of Hg(Ⅱ)%利用纳米金局域表面等离子体共振散射方法检测痕量汞(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    郑莉; 朱进; 吴飞; 丛妍斌; 谭克俊

    2014-01-01

    caused widespread interest for ap-plications in biological and chemical analysis and detection. In the present work,the authors took advantage of the aggregation-induced localized surface plasmon resonance (LSPR)light scattering signal change of sodium thioglycolate functionalized AuNPs in aqueous solutions to develop a highly efficient optical sensor for Hg(Ⅱ). The as-modified AuNPs demonstrate that high nega-tive charge densities exist on their surfaces at pH 9. 0 Britton-Robinson (BR)buffer solution.The AuNPs occur aggregate in so-lution through chelation in the presence of Hg(Ⅱ). The scanning electron microscope (SEM)images for the AuNPs display typ-ical shapes of these AuNPs as regular and almost individual spherical particles. The color change of the AuNPs solution was in-duced by the addition of Hg(Ⅱ)and it immediately changed from red to purple due to the aggregation. Under optimum condi-tions,a good linear relationship was obtained from 0. 08 to 0. 8μmol·L-1 with a correlation coefficient of 0. 997 6,and the limit of detection (LOD)was 8. 0 nmol·L-1. PEG20000 was employed as a system stabilizer. The proposed method has an excellent selectivity for Hg(Ⅱ)in aqueous medium over other metal ions. The optimum test of reaction conditions,including the amount of AuNPs,pH value,reaction stability and ionic strength,were also investigated. This method has been used for determination of Hg(Ⅱ)successfully in environmental water sample. This approach manifested several advantages including short analysis time,high sensitivity,low cost,excellent selectivity and ease of operation.

  4. Surface water hydrology and the Greenland Ice Sheet

    Science.gov (United States)

    Smith, L. C.; Yang, K.; Pitcher, L. H.; Overstreet, B. T.; Chu, V. W.; Rennermalm, A. K.; Cooper, M. G.; Gleason, C. J.; Ryan, J.; Hubbard, A.; Tedesco, M.; Behar, A.

    2016-12-01

    Mass loss from the Greenland Ice Sheet now exceeds 260 Gt/year, raising global sea level by >0.7 mm annually. Approximately two-thirds of this total mass loss is now driven by negative ice sheet surface mass balance (SMB), attributed mainly to production and runoff of meltwater from the ice sheet surface. This new dominance of runoff as a driver of GrIS total mass loss will likely persist owing to anticipated further increases in surface melting, reduced meltwater storage in firn, and the waning importance of dynamical mass losses (ice calving) as the ice sheets retreat from their marine-terminating margins. It also creates the need and opportunity for integrative research pairing traditional surface water hydrology approaches with glaciology. As one example, we present a way to measure supraglacial "runoff" (i.e. specific discharge) at the supraglacial catchment scale ( 101-102 km2), using in situ measurements of supraglacial river discharge and high-resolution satellite/drone mapping of upstream catchment area. This approach, which is standard in terrestrial hydrology but novel for ice sheet science, enables independent verification and improvement of modeled SMB runoff estimates used to project sea level rise. Furthermore, because current SMB models do not consider the role of fluvial watershed processes operating on the ice surface, inclusion of even a simple surface routing model materially improves simulations of runoff delivered to moulins, the critical pathways for meltwater entry into the ice sheet. Incorporating principles of surface water hydrology and fluvial geomorphology and into glaciological models will thus aid estimates of Greenland meltwater runoff to the global ocean as well as connections to subglacial hydrology and ice sheet dynamics.

  5. Assessing surface water availability considering human water use and projected climate variability

    Science.gov (United States)

    Ashraf, Batool; AghaKouchak, Amir; Mousavi-Baygi, Mohammd; Moftakhari, Hamed; Anjileli, Hassan

    2017-04-01

    Climate variability along with anthropogenic activities alter the hydrological cycle and local water availability. The overarching goal of this presentation is to demonstrate the compounding interactions between human water use/withdrawals and climate change and variability. We focus on Karkheh River basin and Urmia basin, in western Iran, that have high level of human activity and water use, and suffer from low water productivity. The future of these basins and their growth relies on sustainable water resources and hence, requires a holistic, basin-wide management to cope with water scarcity challenges. In this study, we investigate changes in the hydrology of the basin including human-induced alterations of the system, during the past three decades. Then, we investigate the individual and combined effects of climate variability and human water withdrawals on surface water storage in the 21st century. We use bias-corrected historical simulations and future projections from ensemble mean of eleven General Circulation Models (GCMs) under two climate change scenarios RCP4.5 and RCP8.5. The results show that, hydrology of the studied basins are significantly dominated by human activities over the baseline period (1976 - 2005). Results show that the increased anthropogenic water demand resulting from substantial socio-economic growth in the past three decades have put significant stress on water resources. We evaluate a number of future water demand scenarios and their interactions with future climate projections. Our results show that by the end of the 21st century, the compounding effects of increased irrigation water demand and precipitation variability may lead to severe local water scarcity in these basins. Our study highlights the necessity for understanding and considering the compounding effects of human water use and future climate projections. Such studies would be useful for improving water management and developing adaption plans in water scarce regions.

  6. Integrating remotely sensed surface water extent into continental scale hydrology.

    Science.gov (United States)

    Revilla-Romero, Beatriz; Wanders, Niko; Burek, Peter; Salamon, Peter; de Roo, Ad

    2016-12-01

    In hydrological forecasting, data assimilation techniques are employed to improve estimates of initial conditions to update incorrect model states with observational data. However, the limited availability of continuous and up-to-date ground streamflow data is one of the main constraints for large-scale flood forecasting models. This is the first study that assess the impact of assimilating daily remotely sensed surface water extent at a 0.1° × 0.1° spatial resolution derived from the Global Flood Detection System (GFDS) into a global rainfall-runoff including large ungauged areas at the continental spatial scale in Africa and South America. Surface water extent is observed using a range of passive microwave remote sensors. The methodology uses the brightness temperature as water bodies have a lower emissivity. In a time series, the satellite signal is expected to vary with changes in water surface, and anomalies can be correlated with flood events. The Ensemble Kalman Filter (EnKF) is a Monte-Carlo implementation of data assimilation and used here by applying random sampling perturbations to the precipitation inputs to account for uncertainty obtaining ensemble streamflow simulations from the LISFLOOD model. Results of the updated streamflow simulation are compared to baseline simulations, without assimilation of the satellite-derived surface water extent. Validation is done in over 100 in situ river gauges using daily streamflow observations in the African and South American continent over a one year period. Some of the more commonly used metrics in hydrology were calculated: KGE', NSE, PBIAS%, R(2), RMSE, and VE. Results show that, for example, NSE score improved on 61 out of 101 stations obtaining significant improvements in both the timing and volume of the flow peaks. Whereas the validation at gauges located in lowland jungle obtained poorest performance mainly due to the closed forest influence on the satellite signal retrieval. The conclusion is that

  7. Integrating remotely sensed surface water extent into continental scale hydrology

    Science.gov (United States)

    Revilla-Romero, Beatriz; Wanders, Niko; Burek, Peter; Salamon, Peter; de Roo, Ad

    2016-12-01

    In hydrological forecasting, data assimilation techniques are employed to improve estimates of initial conditions to update incorrect model states with observational data. However, the limited availability of continuous and up-to-date ground streamflow data is one of the main constraints for large-scale flood forecasting models. This is the first study that assess the impact of assimilating daily remotely sensed surface water extent at a 0.1° × 0.1° spatial resolution derived from the Global Flood Detection System (GFDS) into a global rainfall-runoff including large ungauged areas at the continental spatial scale in Africa and South America. Surface water extent is observed using a range of passive microwave remote sensors. The methodology uses the brightness temperature as water bodies have a lower emissivity. In a time series, the satellite signal is expected to vary with changes in water surface, and anomalies can be correlated with flood events. The Ensemble Kalman Filter (EnKF) is a Monte-Carlo implementation of data assimilation and used here by applying random sampling perturbations to the precipitation inputs to account for uncertainty obtaining ensemble streamflow simulations from the LISFLOOD model. Results of the updated streamflow simulation are compared to baseline simulations, without assimilation of the satellite-derived surface water extent. Validation is done in over 100 in situ river gauges using daily streamflow observations in the African and South American continent over a one year period. Some of the more commonly used metrics in hydrology were calculated: KGE', NSE, PBIAS%, R2, RMSE, and VE. Results show that, for example, NSE score improved on 61 out of 101 stations obtaining significant improvements in both the timing and volume of the flow peaks. Whereas the validation at gauges located in lowland jungle obtained poorest performance mainly due to the closed forest influence on the satellite signal retrieval. The conclusion is that

  8. Impact of river restoration on groundwater - surface water - interactions

    Science.gov (United States)

    Kurth, Anne-Marie; Schirmer, Mario

    2014-05-01

    Since the end of the 19th century, flood protection was increasingly based on the construction of impermeable dams and side walls (BWG, 2003). In spite of providing flood protection, these measures also limited the connectivity between the river and the land, restricted the area available for flooding, and hampered the natural flow dynamics of the river. Apart from the debilitating effect on riverine ecosystems due to loss of habitats, these measures also limited bank filtration, inhibited the infiltration of storm water, and affected groundwater-surface water-interactions. This in turn had a profound effect on ecosystem health, as a lack of groundwater-surface water interactions led to decreased cycling of pollutants and nutrients in the hyporheic zone and limited the moderation of the water temperature (EA, 2009). In recent decades, it has become apparent that further damages to riverine ecosystems must be prohibited, as the damages to ecology, economy and society surmount any benefits gained from exploiting them. Nowadays, the restoration of rivers is a globally accepted means to restore ecosystem functioning, protect water resources and amend flood protection (Andrea et al., 2012; Palmer et al., 2005; Wortley et al., 2013). In spite of huge efforts regarding the restoration of rivers over the last 30 years, the question of its effectiveness remains, as river restorations often reconstruct a naturally looking rather than a naturally functioning stream (EA, 2009). We therefore focussed our research on the effectiveness of river restorations, represented by the groundwater-surface water-interactions. Given a sufficiently high groundwater level, a lack of groundwater-surface water-interactions after restoration may indicate that the vertical connectivity in the stream was not fully restored. In order to investigate groundwater-surface water-interactions we determined the thermal signature on the stream bed and in +/- 40 cm depth by using Distributed Temperature

  9. Utilizing an Automated Home-Built Surface Plasmon Resonance Apparatus to Investigate How Water Interacts with a Hydrophobic Surface

    Science.gov (United States)

    Poynor, Adele

    2011-03-01

    By definition hydrophobic substances hate water. Water placed on a hydrophobic surface will form a drop in order to minimize its contact area. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low- density region forms near the surface. We have employed an automated home-built Surface Plasmon Resonance (SPR) apparatus to investigate this boundary.

  10. Towards Physarum robots: computing and manipulating on water surface

    CERN Document Server

    Adamatzky, Andrew

    2008-01-01

    Plasmodium of Physarym polycephalum is an ideal biological substrate for implementing concurrent and parallel computation, including combinatorial geometry and optimization on graphs. We report results of scoping experiments on Physarum computing in conditions of minimal friction, on the water surface. We show that plasmodium of Physarum is capable for computing a basic spanning trees and manipulating of light-weight objects. We speculate that our results pave the pathways towards design and implementation of amorphous biological robots.

  11. Surface water risk assessment of pesticides in Ethiopia.

    Science.gov (United States)

    Teklu, Berhan M; Adriaanse, Paulien I; Ter Horst, Mechteld M S; Deneer, John W; Van den Brink, Paul J

    2015-03-01

    Scenarios for future use in the pesticide registration procedure in Ethiopia were designed for 3 separate Ethiopian locations, which are aimed to be protective for the whole of Ethiopia. The scenarios estimate concentrations in surface water resulting from agricultural use of pesticides for a small stream and for two types of small ponds. Seven selected pesticides were selected since they were estimated to bear the highest risk to humans on the basis of volume of use, application rate and acute and chronic human toxicity, assuming exposure as a result of the consumption of surface water. Potential ecotoxicological risks were not considered as a selection criterion at this stage. Estimates of exposure concentrations in surface water were established using modelling software also applied in the EU registration procedure (PRZM and TOXSWA). Input variables included physico-chemical properties, and data such as crop calendars, irrigation schedules, meteorological information and detailed application data which were specifically tailored to the Ethiopian situation. The results indicate that for all the pesticides investigated the acute human risk resulting from the consumption of surface water is low to negligible, whereas agricultural use of chlorothalonil, deltamethrin, endosulfan and malathion in some crops may result in medium to high risk to aquatic species. The predicted environmental concentration estimates are based on procedures similar to procedures used at the EU level and in the USA. Addition of aquatic macrophytes as an ecotoxicological endpoint may constitute a welcome future addition to the risk assessment procedure. Implementation of the methods used for risk characterization constitutes a good step forward in the pesticide registration procedure in Ethiopia.

  12. Macro-invertebrate decline in surface water polluted with imidacloprid.

    Directory of Open Access Journals (Sweden)

    Tessa C Van Dijk

    Full Text Available Imidacloprid is one of the most widely used insecticides in the world. Its concentration in surface water exceeds the water quality norms in many parts of the Netherlands. Several studies have demonstrated harmful effects of this neonicotinoid to a wide range of non-target species. Therefore we expected that surface water pollution with imidacloprid would negatively impact aquatic ecosystems. Availability of extensive monitoring data on the abundance of aquatic macro-invertebrate species, and on imidacloprid concentrations in surface water in the Netherlands enabled us to test this hypothesis. Our regression analysis showed a significant negative relationship (P<0.001 between macro-invertebrate abundance and imidacloprid concentration for all species pooled. A significant negative relationship was also found for the orders Amphipoda, Basommatophora, Diptera, Ephemeroptera and Isopoda, and for several species separately. The order Odonata had a negative relationship very close to the significance threshold of 0.05 (P = 0.051. However, in accordance with previous research, a positive relationship was found for the order Actinedida. We used the monitoring field data to test whether the existing three water quality norms for imidacloprid in the Netherlands are protective in real conditions. Our data show that macrofauna abundance drops sharply between 13 and 67 ng l(-1. For aquatic ecosystem protection, two of the norms are not protective at all while the strictest norm of 13 ng l(-1 (MTR seems somewhat protective. In addition to the existing experimental evidence on the negative effects of imidacloprid on invertebrate life, our study, based on data from large-scale field monitoring during multiple years, shows that serious concern about the far-reaching consequences of the abundant use of imidacloprid for aquatic ecosystems is justified.

  13. Evaporation kinetics of sessile water droplets on micropillared superhydrophobic surfaces.

    Science.gov (United States)

    Xu, Wei; Leeladhar, Rajesh; Kang, Yong Tae; Choi, Chang-Hwan

    2013-05-21

    Evaporation modes and kinetics of sessile droplets of water on micropillared superhydrophobic surfaces are experimentally investigated. The results show that a constant contact radius (CCR) mode and a constant contact angle (CCA) mode are two dominating evaporation modes during droplet evaporation on the superhydrophobic surfaces. With the decrease in the solid fraction of the superhydrophobic surfaces, the duration of a CCR mode is reduced and that of a CCA mode is increased. Compared to Rowan's kinetic model, which is based on the vapor diffusion across the droplet boundary, the change in a contact angle in a CCR (pinned) mode shows a remarkable deviation, decreasing at a slower rate on the superhydrophobic surfaces with less-solid fractions. In a CCA (receding) mode, the change in a contact radius agrees well with the theoretical expectation, and the receding speed is slower on the superhydrophobic surfaces with lower solid fractions. The discrepancy between experimental results and Rowan's model is attributed to the initial large contact angle of a droplet on superhydrophobic surfaces. The droplet geometry with a large contact angle results in a narrow wedge region of air along the contact boundary, where the liquid-vapor diffusion is significantly restricted. Such an effect becomes minor as the evaporation proceeds with the decrease in a contact angle. In both the CCR and CCA modes, the evaporative mass transfer shows the linear relationship between mass(2/3) and evaporation time. However, the evaporation rate is slower on the superhydrophobic surfaces, which is more significant on the surfaces with lower solid fractions. As a result, the superhydrophobic surfaces slow down the drying process of a sessile droplet on them.

  14. Wavefront modulation of water surface wave by a metasurface

    Science.gov (United States)

    Sun, Hai-Tao; Cheng, Ying; Wang, Jing-Shi; Liu, Xiao-Jun

    2015-10-01

    We design a planar metasurface to modulate the wavefront of a water surface wave (WSW) on a deep sub-wavelength scale. The metasurface is composed of an array of coiling-up-space units with specially designed parameters, and can take on the work of steering the wavefront when it is pierced into water. Like their acoustic counterparts, the modulation of WSW is ascribed to the gradient phase shift of the coiling-up-space units, which can be perfectly tuned by changing the coiling plate length and channel number inside the units. According to the generalized Snell’s law, negative refraction and ‘driven’ surface mode of WSW are also demonstrated at certain incidences. Specially, the transmitted WSW could be efficiently guided out by linking a symmetrically-corrugated channel in ‘driven’ surface mode. This work may have potential applications in water wave energy extraction and coastal protection. Project supported by the National Basic Research Program of China (Grant No. 2012CB921504), the National Natural Science Foundation of China (Grant Nos. 11474162, 11274171, 11274099, and 11204145), and the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant Nos. 20110091120040 and 20120091110001).

  15. Water Protects Graphitic Surface from Airborne Hydrocarbon Contamination.

    Science.gov (United States)

    Li, Zhiting; Kozbial, Andrew; Nioradze, Nikoloz; Parobek, David; Shenoy, Ganesh Jagadeesh; Salim, Muhammad; Amemiya, Shigeru; Li, Lei; Liu, Haitao

    2016-01-26

    The intrinsic wettability of graphitic materials, such as graphene and graphite, can be readily obscured by airborne hydrocarbon within 5-20 min of ambient air exposure. We report a convenient method to effectively preserve a freshly prepared graphitic surface simply through a water treatment technique. This approach significantly inhibits the hydrocarbon adsorption rate by a factor of ca. 20×, thus maintaining the intrinsic wetting behavior for many hours upon air exposure. Follow-up characterization shows that a nanometer-thick ice-like water forms on the graphitic surface, which remains stabilized at room temperature for at least 2-3 h and thus significantly decreases the adsorption of airborne hydrocarbon on the graphitic surface. This method has potential implications in minimizing hydrocarbon contamination during manufacturing, characterization, processing, and storage of graphene/graphite-based devices. As an example, we show that a water-treated graphite electrode maintains a high level of electrochemical activity in air for up to 1 day.

  16. Oil capture from a water surface by a falling sphere

    Science.gov (United States)

    Smolka, Linda; McLaughlin, Clare; Witelski, Thomas

    2015-11-01

    When a spherical particle is dropped from rest into an oil lens that floats on top of a water surface, a portion of the oil adheres to the sphere. Once the sphere comes to rest at the subsurface, the oil forms a pendant drop that remains attached in equilibrium to the sphere effectively removing oil from the water surface. Best fit solutions of the Laplace equation to experimental profiles are used to investigate the parameter dependence of the radius of curvature and the filling and contact angles at the three-phase contact line of the pendant drop for spheres with different wetting properties, densities and radii. The volume of oil captured by a sphere increases with a sphere's mass and diameter. However, lighter and smaller spheres capture more oil relative to their own volume than do heavier and larger spheres (scaling with the sphere mass ~M - 0 . 544) and are thus more efficient at removing oil from a water surface. The authors wish to acknowledge the support of the National Science Foundation Grant Nos. DMS-0707755 and DMS-0968252.

  17. Recovery of energetically overexploited urban aquifers using surface water

    Science.gov (United States)

    García-Gil, Alejandro; Vázquez-Suñé, Enric; Sánchez-Navarro, José Ángel; Mateo Lázaro, Jesús

    2015-12-01

    Shallow aquifers have an important role in reducing greenhouse gases through helping manage the temperature of urban environments. Nevertheless, the uncontrolled rapid use of shallow groundwater resources to heat or cool urban environments can cause thermal pollution that will limit the long term sustainability of the resource. Therefore, there is a need for appropriate mitigation/remediation strategies capable of recovering energetically overexploited aquifers. In this work, a novel remediation strategy based on surface water recharge into aquifers is presented. To evaluate the capabilities of such measures for effective remediation, this strategy is optimized for a management problem raised in the overheated "Urban Alluvial Aquifer of Zaragoza" (Spain). The application of a transient groundwater flow and heat transport model under 512 different mitigation scenarios has enabled to quantify and discuss the magnitude of the remediation effect as a respond to injection rates of surface water, seasonal schedule of the injection and location of injection. The quantification of the relationship between these variables together with the evaluation of the amount of surface water injected per year in each scenario proposed have provided a better understanding of the system processes and an optimal management alternative. This work also makes awareness of the magnitude of the remediation procedure which is in an order of magnitude of tenths of years.

  18. Investigation of the kinetic of air-surface exchange of mercury by means of elected enviromental variables; Aufklaerung der Kinetik des Boden-Luft-Transfers von Hg anhand ausgewaehlter Umweltparameter

    Energy Technology Data Exchange (ETDEWEB)

    Bahlmann, E.

    2004-10-12

    The overall objective of this study was to elucidate the kinetics of mercury soil-atmosphere exchange and to clarify the effect of major environmental variables on the emission of mercury from soils. For this study a laboratory flux chamber system was developed, which allows for simulation and precise control of soil temperature, soil moisture light radiation and atmospheric turbulence which are known to have an overall strong effect on mercury emissions from soils. The emission of mercury from soils is controlled both by thermal and a photochemical mechanism. The results of this work reinforce the hypothesis that the thermal controlled emission of mercury is driven by the interfacial equilibrium of Hg between the soil matrix and the soil gas phase. The effect of soil temperature, soil texture and total mercury concentration in the soils can be expressed in terms of the Arrhenius equation, which is in agreement with the underlying assumptions of the Freundlich Isotherm. Soil moisture has an overall strong effect on the emission of mercury from soils, which is explained in terms of the soil moisture tension. This provides the first well founded hypothesis for the observed decrease of mercury emission fluxes over dry soils. The light induced emission of mercury from soils shows a strong spectral response in the UV-B and is independent of the soil temperature. This reveal clear evidence for photolytical reduction of divalent mercury species at the soil surface. The most probable mechanism includes the reduction of humic bound mercury species. The results of this work have been incorporated into a one-dimensional simulation model, which may provide a cornerstone in up scaling fluxes derived from field measurements and thus in improving estimations of emissions from naturally surfaces on local, global and regional scales. (orig.)

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

    Science.gov (United States)

    Li, Libo; Yu, Bin; You, Tianyan

    2015-12-15

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

  20. An investigation for the HgCdTe cleaning process

    Science.gov (United States)

    Lan, Tian-Yi; Wang, Nili; Zhao, Shuiping; Liu, Shi-Jia; Li, Xiang-Yang

    2014-11-01

    A new cleaning process for HgCdTe was designed - which used the improved SC-1,SC-2 and Br2- C2H5OH solutions as the main cleaning fluid and applied mega sound waves in the cleaning process. By analyzing the test results carried out on the HgCdTe surface, it was found that the material of HgCdTe for the application of new cleaning process was better than the one for the application of conventional cleaning process in the minority carrier lifetime, residual organic contamination, responsivity and specific detectivity.

  1. Water heating solar system using collector with polycarbonate absorber surface

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Luiz Guilherme Meira de; Sodre, Dilton; Cavalcanti, Eduardo Jose Cidade; Souza, Luiz Guilherme Vieira Meira de; Mendes, Jose Ubiragi de Lima [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)], e-mails: lguilherme@dem.ufrn.br, diltonsodre@ifba.edu.br, ubiragi@ct.ufrn.br

    2010-07-01

    It is presented s solar collector to be used in a heating water for bath system, whose main characteristics are low cost and easy fabrication and assembly processes. The collector absorber surface consists of a polycarbonate plate with an area of 1.5 m{sup 2}. The water inlet and outlet are made of PVC 50mm, and were coupled to a 6mm thick polycarbonate plate using fiberglass resin. A 200 liters thermal reservoir will be used. This reservoir is also alternative. The absorber heating system works under thermo-siphon regimen. Thermal parameters will be evaluated to prove the feasibility of the studied solar heating system to obtain bath water for a four people family. (author)

  2. Evaporating behaviors of water droplet on superhydrophobic surface

    Science.gov (United States)

    Hao, PengFei; Lv, CunJing; He, Feng

    2012-12-01

    We investigated the dynamic evaporating behaviors of water droplet on superhydrophobic surfaces with micropillars. Our experimental data showed that receding contact angles of the water droplet increased with the decreasing of the scale of the micropillars during evaporation, even though the solid area fractions of the microstructured substrates remained constant. We also experimentally found that the critical contact diameters of the transition between the Cassie-Baxter and Wenzel states are affected not only by the geometrical parameters of the microstructures, but also by the initial volume of the water droplet. The measured critical pressure is consistent with the theoretical model, which validated the pressure-induced impalement mechanism for the wetting state transition.

  3. Dynamic corona characteristics of water droplets on charged conductor surface

    Science.gov (United States)

    Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

    2017-03-01

    The formation of the Taylor cone of a water droplet on the surface of the conductor in a line-ground electrode system is captured using a high-speed camera, while the corona current is synchronously measured using a current measurement system. Repeated Taylor cone deformation is observed, yielding regular groupings of corona current pulses. The underlying mechanism of this deformation is studied and the correlation between corona discharge characteristics and cone deformation is investigated. Depending on the applied voltage and rate of water supply, the Taylor cone may be stable or unstable and has a significant influence on the characteristics of the corona currents. If the rate of water supply is large enough, the Taylor cone tends to be unstable and generates corona-current pulses of numerous induced current pulses with low amplitudes. In consequence, this difference suggests that large rainfall results in simultaneously lower radio interference and higher corona loss.

  4. Index of surface-water stations in Texas, January 1987

    Science.gov (United States)

    Rawson, Jack; Carrillo, E.R.; Buckner, H.D.

    1987-01-01

    As of January 1, 1987, the surface-water data-collection network in Texas included 376 continuous streamflow, 76 continuous or daily reservoir-content, 34 gage height, 16 crest-stage partial-record, 8 periodic discharge through range, 33 floodhydrograph partial-record, 9 flood-profile partial-record, 36 low-flow partial-record, 46 daily chemical-quality, 19 continuous-recording water-quality, 84 periodic biological, 17 lake surveys, 162 periodic organic and (or) nutrient, 3 periodic insecticide, 42 periodic pesticide, 19 automatic sampler, 141 periodic minor elements, 130 periodic chemical-quality, 78 periodic physical-organic, 22 continuous-recording three- or four-parameter water-quality, 34 periodic sediment, 22 continuous-recording temperature, and 30 national stream-quality accounting network stations. Plate 1 shows the location of surface-water streamflow or reservoir-content and chemical-quality or sediment'stations in Texas. Plate 2 shows the location of partial-record surfacewater stations.

  5. Effective modification of particle surface properties using ultrasonic water mist

    DEFF Research Database (Denmark)

    Genina, Natalja; Räikkönen, Heikki; Heinämäki, Jyrki

    2009-01-01

    The goal of the present study was to design a new technique to modify particle surface properties and, through that, to improve flowability of poorly flowing drug thiamine hydrochloride and pharmaceutical sugar lactose monohydrate of two different grades. The powdered particles were supplied...... properties. It was found that rapid exposition of pharmaceutical materials by water mist resulted in the improvement of powder technical properties. The evident changes in flowability of coarser lactose were obviously due to smoothing of particle surface and decreasing in the level of fines with very slight...... increment in particle size. The changes in thiamine powder flow were mainly due to narrowing in particle size distribution where the tendency for better flow of finer lactose was related to surface and size modifications. The aqueous mist application did not cause any alteration of the crystal structures...

  6. Effective modification of particle surface properties using ultrasonic water mist

    DEFF Research Database (Denmark)

    Genina, Natalja; Räikkönen, Heikki; Heinämäki, Jyrki

    2009-01-01

    increment in particle size. The changes in thiamine powder flow were mainly due to narrowing in particle size distribution where the tendency for better flow of finer lactose was related to surface and size modifications. The aqueous mist application did not cause any alteration of the crystal structures......The goal of the present study was to design a new technique to modify particle surface properties and, through that, to improve flowability of poorly flowing drug thiamine hydrochloride and pharmaceutical sugar lactose monohydrate of two different grades. The powdered particles were supplied...... properties. It was found that rapid exposition of pharmaceutical materials by water mist resulted in the improvement of powder technical properties. The evident changes in flowability of coarser lactose were obviously due to smoothing of particle surface and decreasing in the level of fines with very slight...

  7. Groundwater surface water interaction study using natural isotopes tracer

    Science.gov (United States)

    Yoon, Yoon Yeol; Kim, Yong Chul; Cho, Soo Young; Lee, Kil Yong

    2015-04-01

    Tritium and stable isotopes are a component of the water molecule, they are the most conservative tracer for groundwater study. And also, radon is natural radioactive nuclide and well dissolved in groundwater. Therefore, these isotopes are used natural tracer for the study of surface water and groundwater interaction of water curtain greenhouse area. The study area used groundwater as a water curtain for warming tool of greenhouse during the winter, and is associated with issues of groundwater shortage while being subject to groundwater-river water interaction. During the winter time, these interactions were studied by using Rn-222, stable isotopes and H-3. These interaction was monitored in multi depth well and linear direction well of groundwater flow. And dam effect was also compared. Samples were collected monthly from October 2013 to April 2014. Radon and tritium were analyzed using Quantulus low background liquid scintillation counter and stable isotopes were analyzed using an IRIS (Isotope Ratio Infrared Spectroscopy ; L2120-i, Picarro). During the winter time, radon concentration was varied from 0.07 Bq/L to 8.9 Bq/L and different interaction was showed between dam. Surface water intrusion was severe at February and restored April when greenhouse warming was ended. The stable isotope results showed different trend with depth and ranged from -9.16 ‰ to -7.24 ‰ for δ 18O value, while the δD value was ranged from -57.86 ‰ to -50.98 ‰. The groundwater age as dated by H-3 was ranged 0.23 Bq/L - 0.59 Bq/L with an average value of 0.37 Bq/L.

  8. Iron oxidation kinetics and phosphorus immobilization at the groundwater-surface water interface

    NARCIS (Netherlands)

    van der Grift, Bas; Rozemeijer, Joachim; Griffioen, Jasper; van der Velde, Ype

    2014-01-01

    Eutrophication of freshwater environments following diffuse nutrient loads is a widely recognized water quality problem in catchments. Fluxes of non-point P sources to surface waters originate from surface runoff and flow from soil water and groundwater into surface water. The availability of P in s

  9. Multiple sources of boron in urban surface waters and groundwaters

    Energy Technology Data Exchange (ETDEWEB)

    Hasenmueller, Elizabeth A., E-mail: eahasenm@wustl.edu; Criss, Robert E.

    2013-03-01

    Previous studies attribute abnormal boron (B) levels in streams and groundwaters to wastewater and fertilizer inputs. This study shows that municipal drinking water used for lawn irrigation contributes substantial non-point loads of B and other chemicals (S-species, Li, and Cu) to surface waters and shallow groundwaters in the St. Louis, Missouri, area. Background levels and potential B sources were characterized by analysis of lawn and street runoff, streams, rivers, springs, local rainfall, wastewater influent and effluent, and fertilizers. Urban surface waters and groundwaters are highly enriched in B (to 250 μg/L) compared to background levels found in rain and pristine, carbonate-hosted streams and springs (< 25 μg/L), but have similar concentrations (150 to 259 μg/L) compared to municipal drinking waters derived from the Missouri River. Other data including B/SO{sub 4}{sup 2-}−S and B/Li ratios confirm major contributions from this source. Moreover, sequential samples of runoff collected during storms show that B concentrations decrease with increased discharge, proving that elevated B levels are not primarily derived from combined sewer overflows (CSOs) during flooding. Instead, non-point source B exhibits complex behavior depending on land use. In urban settings B is rapidly mobilized from lawns during “first flush” events, likely representing surficial salt residues from drinking water used to irrigate lawns, and is also associated with the baseflow fraction, likely derived from the shallow groundwater reservoir that over time accumulates B from drinking water that percolates into the subsurface. The opposite occurs in small rural watersheds, where B is leached from soils by recent rainfall and covaries with the event water fraction. Highlights: ► Boron sources and loads differ between urban and rural watersheds. ► Wastewaters are not the major boron source in small St. Louis, MO watersheds. ► Municipal drinking water used for lawn

  10. Characterizing the Interaction between Groundwater and Surface Water in the Boise River for Water Sustainability

    Science.gov (United States)

    Hernandez, J.; Tan, K.; Portugais, B.

    2014-12-01

    Management of water resources has increasingly become aware of the importance of considering groundwater and surface water as an interconnected, single resource. Surface water is commonly hydraulically connected to groundwater, but the interactions are difficult to observe and measure. Such a conjunctive approach has often been left out of water-management considerations because of a lack of understanding of the processes occurring. The goal of this research is to increase the better understanding of the interaction between the surface water and groundwater using the study case of the Treasure Valley Aquifer and the Boise River in Idaho, framed on water sustainability. Water-budgets for the Treasure Valley for the calendar years 1996 and 2000 suggest that the Boise River lost to the shallow aquifer almost 20 Hm3 and 95 Hm3, respectively, along the Lucky Peak to Capitol Bridge reach. Groundwater discharge occurred into the Boise River, along the Capitol Bridge to Parma reach, at about 645 Hm3 and 653 Hm3for the calendar years 1996 and 2000, respectively (USBR). These figures highlight the importance of better understanding of the water flow because of disparity, which would impact groundwater management practices. There is a need of better understanding of the groundwater-surface water interface for predicting responses to natural and human-induced stresses. A groundwater flow model was developed to compute the rates and directions of groundwater movement through aquifer and confining units in the subsurface. The model also provides a representation of the interaction that occurs between the Boise River and the shallow aquifer in the Treasure Valley. Work in progress on the general flow pattern allows assessing of the connectivity between shallow aquifer and river for helping understanding the impacts of groundwater extraction. Quantifying the interaction between the two freshwater sources would be beneficial in proper water management decisions in order to optimize

  11. First Derivative UV Spectra of Surface Water as a Monitor of Chlorination in Drinking Water Treatment

    Directory of Open Access Journals (Sweden)

    V. Zitko

    2001-01-01

    Full Text Available Many countries require the presence of free chlorine at about 0.1 mg/l in their drinking water supplies. For various reasons, such as cast-iron pipes or long residence times in the distribution system, free chlorine may decrease below detection limits. In such cases it is important to know whether or not the water was chlorinated or if nonchlorinated water entered the system by accident. Changes in UV spectra of natural organic matter in lakewater were used to assess qualitatively the degree of chlorination in the treatment to produce drinking water. The changes were more obvious in the first derivative spectra. In lakewater, the derivative spectra have a maximum at about 280 nm. This maximum shifts to longer wavelengths by up to 10 nm, decreases, and eventually disappears with an increasing dose of chlorine. The water treatment system was monitored by this technique for over 1 year and changes in the UV spectra of water samples were compared with experimental samples treated with known amounts of chlorine. The changes of the UV spectra with the concentration of added chlorine are presented. On several occasions, water, which received very little or no chlorination, may have entered the drinking water system. The results show that first derivative spectra are potentially a tool to determine, in the absence of residual chlorine, whether or not surface water was chlorinated during the treatment to produce potable water.

  12. Elemental composition analysis of superconducting Hg0.67Pb0.34Ba2Ca2Cu3O8+δ

    Institute of Scientific and Technical Information of China (English)

    毛福明; 邵力为

    1997-01-01

    The analysis of superconducting sample by using a sputtered neutral particle mass spectrometer demonstrates that Ca and Ba elements are oxidative, Cu is non-oxidative, Hg is mainly in metallic form near the surface and becomes oxidative far from the surface, and Pb is concentrated on the surface. The analysis also reveals that the highly concentrative hydrocarbon and water impurities are mixed into the sample during the preparation and conservation.

  13. Agricultural insecticides threaten surface waters at the global scale

    Science.gov (United States)

    Stehle, Sebastian; Schulz, Ralf

    2015-01-01

    Compared with nutrient levels and habitat degradation, the importance of agricultural pesticides in surface water may have been underestimated due to a lack of comprehensive quantitative analysis. Increasing pesticide contamination results in decreasing regional aquatic biodiversity, i.e., macroinvertebrate family richness is reduced by ∼30% at pesticide concentrations equaling the legally accepted regulatory threshold levels (RTLs). This study provides a comprehensive metaanalysis of 838 peer-reviewed studies (>2,500 sites in 73 countries) that evaluates, for the first time to our knowledge on a global scale, the exposure of surface waters to particularly toxic agricultural insecticides. We tested whether measured insecticide concentrations (MICs; i.e., quantified insecticide concentrations) exceed their RTLs and how risks depend on insecticide development over time and stringency of environmental regulation. Our analysis reveals that MICs occur rarely (i.e., an estimated 97.4% of analyses conducted found no MICs) and there is a complete lack of scientific monitoring data for ∼90% of global cropland. Most importantly, of the 11,300 MICs, 52.4% (5,915 cases; 68.5% of the sites) exceeded the RTL for either surface water (RTLSW) or sediments. Thus, the biological integrity of global water resources is at a substantial risk. RTLSW exceedances depend on the catchment size, sampling regime, and sampling date; are significantly higher for newer-generation insecticides (i.e., pyrethroids); and are high even in countries with stringent environmental regulations. These results suggest the need for worldwide improvements to current pesticide regulations and agricultural pesticide application practices and for intensified research efforts on the presence and effects of pesticides under real-world conditions. PMID:25870271

  14. Forming chemical composition of surface waters in the Arctic as "water - rock" interaction. Case study of lake Inari and river Paz

    Science.gov (United States)

    Mazukhina, Svetlana; Sandimirov, Sergey; Pozhilenko, Vladimir; Ivanov, Stanislav; Maksimova, Viktoriia

    2017-04-01

    Due to the depletion of fresh water supplies and the deterioration of their quality as a result of anthropogenic impact on the Arctic ecosystems, the research questions of forming surface and ground waters, their interactions with the rocks, development of the foundations for their rational use and protection are of great fundamental and practical importance. The aim of the work is to evaluate the influence of the chemical composition of rocks of the northern part of the Fennoscandian (Baltic) shield on forming surface waters chemical composition (Lake Inari, river Paz) using physical-chemical modeling (Chudnenko, 2010, Selector software package). River Paz (Paatsjoki) is the largest river in North Fennoscandia and flows through the territory of three countries - Finland, Russia and Norway. It originates from Lake Inari, which a large number of streams and rivers flow into, coming from the mountain range of the northern Finland (Maanselkä hill). Within the catchment of inflows feeding the lake Inari and river Paz in its upper flow there are mainly diverse early Precambrian metamorphic and intrusive rocks of the Lapland granulite belt and its framing, and to a lesser extent - various gneisses and migmatites with relicts of amphibolites, granitic gneisses, plagioclase and plagio- and plagiomicrocline granites, and quartz diorites of Inari terrane (Meriläinen, 1976, fig 1; Hörmann et al, 1980, fig 1; Geologicalmap, 2001). Basing on the techniques developed earlier (Mazukhina, 2012), and the data of monitoring of the chemical composition of surface waters and investigation of the chemical composition of the rocks, physical-chemical modeling (FCM) (Selector software package) was carried out. FCM includes 34 independent components (Al-B-Br-Ar-He-Ne-C-Ca-Cl-F-Fe-K-Mg-Mn-N-Na-P-S-Si-Sr-Cu-Zn-Ni-Pb-V-Ba-Co-Cr-Hg-As-Cd-H-O-e), 996 dependent components, of them 369 in aqueous solution, 76 in the gas phase, 111 liquid hydrocarbons, and 440 solid phases, organic and mineral

  15. Contamination levels of human pharmaceutical compounds in French surface and drinking water.

    OpenAIRE

    Mompelat, S.; Thomas, Olivier; Le Bot, Barbara

    2011-01-01

    International audience; The occurrence of 20 human pharmaceutical compounds and metabolites from 10 representative therapeutic classes was analysed from resource and drinking water in two catchment basins located in north-west France. 98 samples were analysed from 63 stations (surface water and drinking water produced from surface water). Of the 20 human pharmaceutical compounds selected, 16 were quantified in both the surface water and drinking water, with 22% of the values above the limit o...

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

    Science.gov (United States)

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

    2014-02-24

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

  17. A molecular dynamics study on surface properties of supercooled water

    Institute of Scientific and Technical Information of China (English)

    Lü; Yongjun

    2006-01-01

    [1]Basu J K,Hazra S,Sanyal M K.Growth mechanism of Langmuir-Blodgett films.Phys Rev Lett,1999,82:4675-4678[2]Taylor R S,Shields R L.Molecular-dynamics simulations of the ethanol liquid-vapor interface.J Chem Phys,2003,119:12569-12576[3]Velev O D,Gurkov T D,Ivanov I B,et al.Abnormal thickness and stability of nonequilibrium liquid films.Phys Rev Lett,1995,75:264-267[4]Weng J G,Park S,Lukes J R,et al.Molecular dynamics investigation of thickness effect on liquid films.J Chem Phys,2000,113:5917-5923[5]Zakharov V V,Brodskaya E N,Laaksonen A.Surface tension of water droplets:A molecular dynamics study of model and size dependencies.J Chem Phys,1997,107:10675-10683[6]Wang J Z,Chen M,Guo Z Y.A two-dimensional molecular dynamics simulation of liquid-vapor nucleation.Chin Sci Bull,2003,48(7):623-626[7]Guissani Y,Guillot B.A computer simulation study of the liquid-vapor coexistence curve of water.J Chem Phys,1993,98:8221-8235[8]Wilson M A,Pohorille A,Pratt L R.Surface potential of the water liquid-vapor interface.J Chem Phys,1988,88:3281-3285[9]Alejandre J,Tildesley D J,Chapela G A.Molecular dynamics simulation of the orthobaric densities and surface tension of water.J Chem Phys,1995,102:4574-4583[10]Matsumoto M,Kataoka Y.Study on liquid-vapor interface of water (Ⅰ):Simulational results of thermodynamic properties and orientational structure.J Chem Phys,1988,88:3233-3245[11]Floriano M A,Angell C A.Surface tension and molar surface free energy and entropy of water to-27.2℃.J Phys Chem,1990,94:4199-4202[12]Jorgensen W L,Chandrasekhar J,Madura J D.Comparison of simple potential functions for simulating liquid water.J Chem Phys,1993,79:926-935[13]Berendsen H J C,Grigera J R,Straatsma T P.The missing term in effective pair potentials.J Phys Chem,1987,91:6269-6271[14]Arbuckle B W,Clancy P.Effects of the Ewald sum on the free energy of the extended simple point charge model for water.J Chem Phys,2002,116:5090-5098[15]Tarazona P,Chacon E,Reinaldo-Falagan M,et al

  18. X-Ray Spectroscopy of the Liquid Water Surface

    Science.gov (United States)

    Saykally, Richard

    2004-03-01

    We have developed a new experiment for probing molecular details of liquid-vapor interfaces of volatile substances and their solutions under equilibrium conditions. Electronic and geometric structures of interfacial molecules are probed by EXAFS and NEXAFS methods in the soft X-ray region, using the Advanced Light Source, Berkeley, CA. Liquids are introduced into a high vacuum environment through the use of liquid microjets, which have been characterized independently by Raman spectroscopy. Detection of ions and electrons produced by the Auger avalanche probe the bulk and surface regions of the microjet, respectively, as a result of their different escape depths. Our first efforts involved a comparative study of the interfaces of water and methanol, wherein we detailed the first observation of surface relaxation for a liquid. Analysis of EXAFS data yielded a 6distance at the water interface, whereas a 5was found for methanol. NEXAFS measurements, interpreted in terms of density functional theory simulations, indicate a large population of interfacial water molecules having two free OH bonds ("acceptor only molecules"). This complements the "single donor" species identified in sum frequency generation experiments. These results are supported by recent theoretical calculations. For methanol and other simple alcohols, the data indicate that free alkyl groups extend into the vapor part of the interface. Preliminary results for aqueous solutions, as well as for other pure liquids, have been obtained and are presently under analysis. REFERENCES 1. K.R. Wilson, R.D. Schaller, B.S. Rude, T. Catalano, D.T. Co, J.D. Bozek, and R.J. Saykally, "Surface relaxation in liquid water and methanol studied by X-ray absorption spectroscopy," J. Chem. Phys 117,7738(2002). 2. K.R. Wilson, M. Cavalleri, B.S. Rude, R.D. Schaller, A. Nilsson, L.G.M. Pettersson, N. Goldman, T. Catalano, J.D. Bozek, and R.J. Saykally, "Characterization of hydrogen bond acceptor molecules at the water surface

  19. Development of emergency water quality standards for Cr6+and Hg2+in Liaohe River basin%辽河流域六价铬和无机汞应急水质标准研究

    Institute of Scientific and Technical Information of China (English)

    闫振广; 刘征涛; 孟伟

    2013-01-01

      针对辽河流域的特征污染物六价铬和无机汞,广泛搜集、筛选了水生生物的急性毒性数据,对国际物种敏感度分布(SSD)主流方法的基准计算结果进行了评价.基于评价结果,以澳大利亚和新西兰的SSD技术为基础,初步建立了综合的应急水质标准方法学.将受污染物暴露胁迫的水生生物比例达到5%、15%、30%和50%时对应的生态风险级别分别设定为I级、II级、III级和IV级,且对应于4级应急水质标准.推算了六价铬和无机汞的辽河流域应急水质标准限值,提出了相应的流域风险指示生物.结果表明,六价铬的4级应急水质标准分别为2.85μg/L、21.0μg/L、161μg/L和797μg/L,风险指示生物为溞类(II级)、青虾(III级)和鳙鱼或蝌蚪(IV级);无机汞的4级应急水质标准分别为0.59μg/L、2.32μg/L、6.25μg/L和15.6μg/L,风险指示生物为鲫鱼或溞类(II级)、青虾(III级)、水丝蚓或蟹类(IV级),为突发性水环境污染事故风险分析提供了参考.%The acute toxicity data of Cr6+ and Hg2+ to the aquatic organisms in Liaohe River basin was collected and screened. Calculated results of criteria values of international species sensitivity distribution(SSD) methods were evaluated through data analysis. The comprehensive methodologies of emergency water quality standard(WQS)were established based on the SSD method of Australia and New Zealand according to the eval-uation results. The affected fractions of the aquatic organisms was set to be 5%,15%,30%and 50%,corre-sponding to the risk grades of I,II,III and IV,and four-grade emergency WQS,respectively. The emergency WQS for Cr6+and Hg2+in the Liao River basin were derived and the corresponding risk indicators were also proposed. The results showed that the four-grade emergency WQSs for Cr6+were 2.85μg/L,21.0μg/L,161μg/Land 797μg/L, respectively,and the risk indicators were daphnia(grade II),shrimp(grade III),and the bighead fish or

  20. Synthesis and Cell Imaging of a Near-Infrared Fluorescent Magnetic "CdHgTe-Dextran-Magnetic Layered Double Hydroxide-Fluorouracil" Composite.

    Science.gov (United States)

    Jin, XueQin; Zhang, Min; Gou, GuoJing; Ren, Jie

    2016-05-01

    In this article, a water-soluble near-infrared quantum dots of CdHgTe were prepared and subsequently combined with the drug delivery system "dextran-magnetic layered double hydroxide-fluorouracil" (DMF) to build a new nanostructure platform in form of CdHgTe@DMF, in which the fluorescent probe function of quantum dots and the magnetic targeting transport and slow-release curative effect of DMF were blended availably together. The luminescent property particle size, and internal structure of the composite were characterized using fluorescence spectrophotometer, ultraviolet spectrophotometer, laser particle size distribution, TEM, X-ray diffraction, and Fourier transform infrared. The experimental study on fluorescent tags effect and magnetic targeting performance of the multifunctional platform were performed by fluorescent confocal imaging. The results showed that the CdHgTe could be grafted successfully onto the surface of DMF by electrostatic coupling. The CdHgTe@DMF composite showed super-paramagnetic and photoluminescence property in the near-infrared wavelength range of 575-780 nm. Compared with CdHgTe, the CdHgTe@DMF composite could significantly improve the cell imaging effect, the label intensity increased with the magnetic field intensity, and obeyed the linear relationship Dmean = 1.758 + 0.0075M under the conditions of magnetic field interference. It can be implied that the CdHgTe@DMF may be an effective multifunction tool applying to optical bioimaging and magnetic targeted therapy.

  1. The interplay of snow, surface water, and groundwater reservoirs for integrated water resources management

    Science.gov (United States)

    Rajagopal, S.; Huntington, J.

    2015-12-01

    Changes in climate, growth in population and economy have increased the reliance on groundwater to augment supplies of surface water across the world, and especially the Western United States. Martis Valley, a high altitude, snow dominated watershed in the Sierra Nevada, California has both surface (river/reservoir) and groundwater resources that are utilized to meet demands within the valley. The recent drought and changing precipitation type (less snow, more rain) has stressed the regional surface water supply and has increased the reliance on groundwater pumping. The objective of this paper is to quantify how changes in climate and depletion of snow storage result in decreased groundwater recharge and increased groundwater use, and to assess if increased surface water storage can mitigate impacts to groundwater under historic and future climate conditions. These objectives require knowledge on the spatiotemporal distribution of groundwater recharge, discharge, and surface and groundwater interactions. We use a high resolution, physically-based integrated surface and groundwater model, GSFLOW, to identify key mechanisms that explain recent hydrologic changes in the region. The model was calibrated using a multi-criteria approach to various historical observed hydrologic fluxes (streamflow and groundwater pumping) and states (lake stage, groundwater head, snow cover area). Observations show that while groundwater use in the basin has increased significantly since the 1980's, it still remains a relatively minor component of annual consumptive water use. Model simulations suggest that changes from snow to rain will lead to increases in Hortonian and Dunnian runoff, and decreases in groundwater recharge and discharge to streams, which could have a greater impact on groundwater resources than increased pumping. These findings highlight the necessity of an integrated approach for evaluating natural and anthropogenic impacts on surface and groundwater resources.

  2. A review of heterogeneous photocatalysis for water and surface disinfection.

    Science.gov (United States)

    Byrne, John Anthony; Dunlop, Patrick Stuart Morris; Hamilton, Jeremy William John; Fernández-Ibáñez, Pilar; Polo-López, Inmaculada; Sharma, Preetam Kumar; Vennard, Ashlene Sarah Margaret

    2015-03-30

    Photo-excitation of certain semiconductors can lead to the production of reactive oxygen species that can inactivate microorganisms. The mechanisms involved are reviewed, along with two important applications. The first is the use of photocatalysis to enhance the solar disinfection of water. It is estimated that 750 million people do not have accessed to an improved source for drinking and many more rely on sources that are not safe. If one can utilize photocatalysis to enhance the solar disinfection of water and provide an inexpensive, simple method of water disinfection, then it could help reduce the risk of waterborne disease. The second application is the use of photocatalytic coatings to combat healthcare associated infections. Two challenges are considered, i.e., the use of photocatalytic coatings to give "self-disinfecting" surfaces to reduce the risk of transmission of infection via environmental surfaces, and the use of photocatalytic coatings for the decontamination and disinfection of medical devices. In the final section, the development of novel photocatalytic materials for use in disinfection applications is reviewed, taking account of materials, developed for other photocatalytic applications, but which may be transferable for disinfection purposes.

  3. Surface Towed CSEM Systems for Shallow Water Mapping

    Science.gov (United States)

    Sherman, J.; Constable, S.; Kannberg, P. K.

    2015-12-01

    We have developed a low-power, surface towed electric dipole-dipole system suitable for mapping seafloor geology in shallow water and deployable from small boats. The transmitter is capable of up to 50 amps output using 12 VDC from a 110/240 VAC power supply, and can generate an arbitrary GPS stabilized ternary waveform. Transmitter antennas are typically 50 to 100 m long. Receivers are built around the standard Scripps seafloor electrode, amplifier, and logging systems but housed in floating PVC cases and equipped with GPS timing and positioning, pitch/roll/heading sensors, and accelerometers. Receiver dipoles are 1.5 m long rigid booms held 1 m below the surface. As with the Scripps deep-towed Vulcan system, rigid antennas are used to avoid noise associated with flexible antennas moving across Earth's magnetic field. The tow cable is a simple floating rope up to 1000 m long. Water depth and conductivity are sampled continuously in order to provide constraints for apparent resistivity calculations and inversion, and moored seafloor recorders can be used to extend transmitter/receiver offsets. The entire system can be air freighted and transported in one utility vehicle. We will present results from a study to map permafrost in shallow water off Prudhoe Bay, Alaska.

  4. WATER ICE AT THE SURFACE OF THE HD 100546 DISK

    Energy Technology Data Exchange (ETDEWEB)

    Honda, M. [Department of Physics, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011 (Japan); Kudo, T.; Terada, H.; Takato, N. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, Hawaii 96720 (United States); Takatsuki, S.; Nakamoto, T. [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Inoue, A. K. [College of General Education, Osaka Sangyo University, Daito, Osaka 574-8530 (Japan); Fukagawa, M.; Tamura, M. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-04-10

    We made near-infrared multicolor imaging observations of a disk around Herbig Be star HD 100546 using Gemini/NICI. K (2.2 μm), H{sub 2}O ice (3.06 μm), and L′ (3.8 μm) disk images were obtained and we found a 3.1 μm absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on Oka et al., including the water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by both the disk models with and without the photodesorption effect within the measurement accuracy, but the model with photodesorption effects is slightly more favored, implying that the UV photons play an important role in the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement to the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models.

  5. Global Occurrence and Emission of Rotaviruses to Surface Waters

    Directory of Open Access Journals (Sweden)

    Nicholas M. Kiulia

    2015-05-01

    Full Text Available Group A rotaviruses (RV are the major cause of acute gastroenteritis in infants and young children globally. Waterborne transmission of RV and the presence of RV in water sources are of major public health importance. In this paper, we present the Global Waterborne Pathogen model for RV (GloWPa-Rota model to estimate the global distribution of RV emissions to surface water. To our knowledge, this is the first model to do so. We review the literature to estimate three RV specific variables for the model: incidence, excretion rate and removal during wastewater treatment. We estimate total global RV emissions to be 2 × 1018 viral particles/grid/year, of which 87% is produced by the urban population. Hotspot regions with high RV emissions are urban areas in densely populated parts of the world, such as Bangladesh and Nigeria, while low emissions are found in rural areas in North Russia and the Australian desert. Even for industrialized regions with high population density and without tertiary treatment, such as the UK, substantial emissions are estimated. Modeling exercises like the one presented in this paper provide unique opportunities to further study these emissions to surface water, their sources and scenarios for improved management.

  6. A Review of Heterogeneous Photocatalysis for Water and Surface Disinfection

    Directory of Open Access Journals (Sweden)

    John Anthony Byrne

    2015-03-01

    Full Text Available Photo-excitation of certain semiconductors can lead to the production of reactive oxygen species that can inactivate microorganisms. The mechanisms involved are reviewed, along with two important applications. The first is the use of photocatalysis to enhance the solar disinfection of water. It is estimated that 750 million people do not have accessed to an improved source for drinking and many more rely on sources that are not safe. If one can utilize photocatalysis to enhance the solar disinfection of water and provide an inexpensive, simple method of water disinfection, then it could help reduce the risk of waterborne disease. The second application is the use of photocatalytic coatings to combat healthcare associated infections. Two challenges are considered, i.e., the use of photocatalytic coatings to give “self-disinfecting” surfaces to reduce the risk of transmission of infection via environmental surfaces, and the use of photocatalytic coatings for the decontamination and disinfection of medical devices. In the final section, the development of novel photocatalytic materials for use in disinfection applications is reviewed, taking account of materials, developed for other photocatalytic applications, but which may be transferable for disinfection purposes.

  7. Horizon effects with surface waves on moving water

    CERN Document Server

    Rousseaux, Germain; Mathis, Christian; Coullet, Pierre; Philbin, Thomas G; Leonhardt, Ulf

    2010-01-01

    Surface waves on a stationary flow of water are considered, in a linear model that includes the surface tension of the fluid. The resulting gravity-capillary waves experience a rich array of horizon effects when propagating against the flow. In some cases three horizons (points where the group velocity of the wave reverses) exist for waves with a single laboratory frequency. Some of these effects are familiar in fluid mechanics under the name of wave blocking, but other aspects, in particular waves with negative co-moving frequency and the Hawking effect, were overlooked until surface waves were investigated as examples of analogue gravity [R. Schuetzhold and W. G. Unruh W G, Phys. Rev. D 66 (2002) 044019]. A comprehensive presentation of the various horizon effects for gravity-capillary waves is given, with emphasis on the deep water/long wavelength case kh>>1 where many analytical results can be derived. A similarity of the state space of the waves to that of a thermodynamic system is pointed out.

  8. A Novel Energy efficient Surface water Wireless Sensor Network Algorithm

    Directory of Open Access Journals (Sweden)

    B.Meenakshi

    2012-07-01

    Full Text Available Maintaining the energy of sensors in Wireless Sensor Network (WSN is important in critical applications. It has been a challenge to design wireless sensor networks to enable applications for oceanographicdata collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation and tactical surveillance applications. WSN consists of sensor nodes which sense the physical parameters such as temperature, humidity, pressure and light etc and send them to a fusion center namely Base Station (BS from where one can get the value of physical parameters at any time. Requirement of monitoring the environment might be anywhere, like middle of the sea or under the earth where man cannot go often to recharge the batterieswhich supplies the sensing device, transceiver and memory unit in the sensor node. So the usage of the battery power must be judicious in WSN. Earlier attempts have been made to prolong the network lifetime, but still it is a challenging task. In this paper we propose a Novel Energy efficient Surface water Wireless Sensor Network Algorithm (NES-WSN to optimize the energy consumption by WSN. The present work concentrates on energy saving of sensor nodes when they are deployed in the surface of the sea water. Whenever the sea surface temperature increases there will be a power loss which is reduced by clustering the nodes and by transferring data through multihop routing. Experimental results show that due to increase in temperature there is a definite power loss and it can be minimized by using NES-WSN algorithm definitely.

  9. Engineering Extreme Hydrophobic and Super Slippery Water Shedding Surfaces

    Science.gov (United States)

    McHale, Glen

    2017-04-01

    The intrinsic water repellency of a material is fundamentally determined by its surface chemistry, but alone this does not determine the ability of a surface to shed water. Physical factors such as the surface texture/topography, rigidity/flexibility, granularity/porosity combined with the intrinsic wetting properties of the liquid with the surface and whether it is infused by a lubricating liquid are equally important. In this talk I will outline fundamental, but simple, ideas on the topographic enhancement of surface chemistry to create superhydrophobicity, the adhesion of particles to liquid-air interfaces to create liquid marbles, elastocapillarity to create droplet wrapping, and lubricant impregnated surfaces to create completely mobile droplets [1-3]. I will discuss how these ideas have their origins in natural systems and surfaces, such as Lotus leaves, galling aphids and the Nepenthes pitcher plant. I will show how we have applied these concepts to study the wetting of granular systems, such as sand, to understand extreme soil water repellency. I will argue that relaxing the assumption that a solid substrate is fixed in shape and arrangement, can lead to the formation of liquid marbles, whereby a droplet self-coats in a hydrophobic powder/grains. I will show that the concepts of wetting and porosity blur as liquids penetrate into a porous or granular substrate. I will also discuss how lubricant impregnated super slippery surfaces can be used to study a pure constant contact angle mode of droplet evaporation [4]. Finally, I will show dewetting of a surface is not simply a video reversal of wetting [5], and I will give an example of the use of perfect hydrophobicity using the Leidenfrost effect to create a new type of low friction mechanical and hear engine [6]. References: [1] Shirtcliffe, N. J., et al., An introduction to superhydrophobicity. Advances in Colloid and Interface Science, vol. 161, pp.124-138 (2010). [2] McHale, G. & Newton, M. I. Liquid

  10. Surface water quality in a water run-off canal system: A case study in Jubail Industrial City, Kingdom of Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Zia Mahmood Siddiqi

    2016-06-01

    Full Text Available Water quality in a run-off canal system in an industrial area was evaluated for a range of physical and chemical properties comprising trace metals (including mercury (Hg, chromium (Cr, iron (Fe, manganese (Mn, salinity, pH, turbidity, total dissolved solids, total suspended solids, chemical oxygen demand (COD, and dissolved oxygen. High concentrations of potassium (K (1.260–2.345 mg/l and calcium (Ca (19.170–35510 mg/l demonstrated that the salinity in the water was high, which indicates that industrial effluents from fertilizer manufacturing and Chlor-alkali units are being discharged into the canal system. Almost all the metal concentrations in water and sediment were within the thresholds established by the local regulatory body. Concentrations of Cr (0.0154–0.0184 mg/l, Mn (0.0608–0.199 mg/l, Fe (0.023–0.035 mg/l, COD (807–916 mg/l, and turbidity (633 ± 15–783 ± 22 NTU were high where the canal discharges into the Persian Gulf; these discharges may compromise the health of the aquatic ecosystem. There is concern about the levels of Hg in water (0.00135–0.0084 mg/l, suspended sediment (0.00308–0.0096 mg/l, and bed sediment (0.00172–0.00442 mg/l because of the bio-accumulative nature of Hg. We also compared the total Hg concentrations in fish from Jubail, and two nearby cities. Hg contents were highest in fish tissues from Jubail. This is the first time that heavy metal pollution has been assessed in this water run-off canal system; information about Hg is of particular interest and will form the basis of an Hg database for the area that will be useful for future investigations.

  11. High prevalence of enteric viruses in untreated individual drinking water sources and surface water in Slovenia.

    Science.gov (United States)

    Steyer, Andrej; Torkar, Karmen Godič; Gutiérrez-Aguirre, Ion; Poljšak-Prijatelj, Mateja

    2011-09-01

    Waterborne infections have been shown to be important in outbreaks of gastroenteritis throughout the world. Although improved sanitary conditions are being progressively applied, fecal contaminations remain an emerging problem also in developed countries. The aim of our study was to investigate the prevalence of fecal contaminated water sources in Slovenia, including surface waters and groundwater sources throughout the country. In total, 152 water samples were investigated, of which 72 samples represents groundwater from individual wells, 17 samples from public collection supplies and 63 samples from surface stream waters. Two liters of untreated water samples were collected and concentrated by the adsorption/elution technique with positively charged filters followed by an additional ultracentrifugation step. Group A rotaviruses, noroviruses (genogroups I and II) and astroviruses were detected with real-time RT-PCR method in 69 (45.4%) out of 152 samples collected, of which 31/89 (34.8%) drinking water and 38/63 (60.3%) surface water samples were positive for at least one virus tested. In 30.3% of drinking water samples group A rotaviruses were detected (27/89), followed by noroviruses GI (2.2%; 2/89) and astroviruses (2.2%; 2/89). In drinking groundwater samples group A rotaviruses were detected in 27 out of 72 tested samples (37.5%), genogroup I noroviruses in two (2.8%), and human astroviruses in one (1.4%) samples. In surface water samples norovirus genogroup GII was the most frequently detected (41.3%; 26/63), followed by norovirus GI (33.3%; 21/63), human astrovirus (27.0%; 17/63) and group A rotavirus (17.5%; 11/63). Our study demonstrates relatively high percentage of groundwater contamination in Slovenia and, suggests that raw groundwater used as individual drinking water supply may constitute a possible source of enteric virus infections. In the future, testing for enteric viruses should be applied for drinking water sources in waterborne outbreaks.

  12. Magnetic fields of HgMn stars

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  13. Further Studies, About New Elements Production, by Electrolysis of Cathodic Pd Thin–Long Wires, in Alcohol-Water Solutions (H, D) and Th-Hg Salts. New Procedures to Produce Pd Nano-Structures

    CERN Document Server

    Celani, F; Righi, E; Trenta, G; Catena, C; D’Agostaro, G; Quercia, P; Andreassi, V; Marini, P; Di Stefano, V; Nakamura, M; Mancini, A; Sona, P G; Fontana, F; Gamberale, L; Garbelli, D; Celia, E; Falcioni, F; Marchesini, M; Novaro, E; Mastromatteo, U

    2005-01-01

    Abstract They were continued, at National Institute of Nuclear Physics, Frascati National Laboratories-Italy, the systematic studies about detection of new elements, some even with isotopic composition different from natural one, after prolonged electrolysis of Pd wires. The electrolytic solution adopted is the, unusual, used from our experimental group since 1999. In short, it was a mixture of both heavy ethyl alcohol (C2H5OD at 90-95%) and water (D2O, at 10-5%), with Th salts at micromolar concentration and Hg at even lower concentration (both of spectroscopic purity). The liquid solutions, before use, were carefully vacuum distilled (and on line 100nm filtered) at low temperatures (30-40°C) and analysed by ICP-MS. The pH was kept quite mild (acidic at about 3-4). The cathode is Pd (99.9% purity) in the shape of long (60cm) and thin wires (diameter only 0.05mm). Before use, it is carefully cleaned and oxidised by Joule heating in air following a (complex) procedure from us continuously improved (since 1995...

  14. Water on titanium dioxide surface: a revisiting by reactive molecular dynamics simulations.

    Science.gov (United States)

    Huang, Liangliang; Gubbins, Keith E; Li, Licheng; Lu, Xiaohua

    2014-12-16

    The behavior of surface water, especially the adsorption and dissociation characteristics, is a key to understanding and promoting photocatalytic and biomedical applications of titanium dioxide materials. Using molecular dynamics simulations with the ReaxFF force field, we study the interactions between water and five different TiO2 surfaces that are of interest to both experiments and theoretical calculations. The results show that TiO2 surfaces demonstrate different reactivities for water dissociation [rutile (011) > TiO2-B (100) > anatase (001) > rutile (110)], and there is no water dissociation observed on the TiO2-B (001) surface. The simulations also reveal that the water dissociation and the TiO2 surface chemistry change, and the new surface Ti-OH and O-H functional groups affect the orientation of other near-surface water molecules. On the reactive surface, such as the rutile (110) surface, water dissociated and formed new Ti-OH and O-H bonds on the surface. Those functional groups enhanced the hydrogen bond networking with the near-surface water molecules and their configurations. On the nonreactive TiO2-B (001) surface where no molecular or dissociative water adsorption is observed, near-surface water can also form hydrogen bonds with surface oxygen atoms of TiO2, but their distance to the surface is longer than that on the rutile (011) surface.

  15. Nitrogen surface water retention in the Baltic Sea drainage basin

    Directory of Open Access Journals (Sweden)

    P. Stålnacke

    2014-09-01

    Full Text Available In this paper, we estimate the surface water retention of nitrogen (N in all the 117 drainage basins to the Baltic Sea with the use of a statistical model (MESAW for source apportionment of riverine loads of pollutants. Our results show that the MESAW model was able to estimate the N load at the river mouth of 88 Baltic Sea rivers, for which we had observed data, with a sufficient degree of precision and accuracy. The estimated retention parameters were also statistically significant. Our results show that around 380 000 t of N are annually retained in surface waters draining to the Baltic Sea. The total annual riverine load from the 117 basins to the Baltic Sea was estimated to 570 000 t of N, giving a total surface water N retention of around 40%. In terms of absolute retention values, three major river basins account for 50% of the total retention in the 117 basins; i.e. around 104 000 t of N is retained in Neva, 55 000 t in Vistula and 32 000 t in Oder. The largest retention was found in river basins with a high percentage of lakes as indicated by a strong relationship between N retention (% and share of lake area in the river drainage areas. For example in Göta älv, we estimated a total N retention of 72%, whereof 67% of the retention occurred in the lakes of that drainage area (Lake Vänern primarily. The obtained results will hopefully enable the Helsinki Commission (HELCOM to refine the nutrient load targets in the Baltic Sea Action Plan (BSAP, as well as to better identify cost-efficient measures to reduce nutrient loadings to the Baltic Sea.

  16. Surface water - groundwater interactions at different spatial and temporal scales

    DEFF Research Database (Denmark)

    Sebök, Éva

    in lowland catchments, mainly exploring and assessing Distributed Temperature Sensing (DTS) which by detecting variability in temperatures at the Sediment-Water Interface (SWI) can indirectly map variability in groundwater discharge at several spatial and temporal scales. On the small-scale (...As there is a growing demand for the protection and optimal management of both the surface water and groundwater resources, the understanding of their exchange processes is of great importance. This PhD study aimed at describing the natural spatial and temporal variability of these interactions...... detected large spatial variability in SWI temperatures with scattered high-discharge sites in a stream and also in a lake where discharge fluxes were estimated by vertical temperature profiles and seepage meter measurements. On the kilometre scale DTS indicated less spatial variability in streambed...

  17. Thermodynamics of surface defects at the aspirin/water interface

    Science.gov (United States)

    Schneider, Julian; Zheng, Chen; Reuter, Karsten

    2014-09-01

    We present a simulation scheme to calculate defect formation free energies at a molecular crystal/water interface based on force-field molecular dynamics simulations. To this end, we adopt and modify existing approaches to calculate binding free energies of biological ligand/receptor complexes to be applicable to common surface defects, such as step edges and kink sites. We obtain statistically accurate and reliable free energy values for the aspirin/water interface, which can be applied to estimate the distribution of defects using well-established thermodynamic relations. As a show case we calculate the free energy upon dissolving molecules from kink sites at the interface. This free energy can be related to the solubility concentration and we obtain solubility values in excellent agreement with experimental results.

  18. Embedded water-based surface heating part 2: experimental validation

    DEFF Research Database (Denmark)

    Karlsson, Henrik

    2010-01-01

    : hybrid 3D numerical model. Journal of Building Physics 33: 357-391). The thermal response of the system is tested in both long (16 h) and short (30 min) cycle experiments where the water flow alters between on and off. Temperature distribution, within the floor construction, and the heat exchange process...... are studied throughout the test cycles. The model underestimates the steady-state heat exchange from the pipe loop by 16% when boundary conditions and thermal properties according to the reference case are applied. Temperatures at the floor surface are assessed with good precision while temperatures......The transient operation of an embedded water-based floor heating system has been studied by means of a numerical simulation tool. Prior to this study, Caccavelli and Richard (Caccavelli D, Richard P (1994) Etude portant sur le dimensionnement d'un plancher chauffant a eau chaude en CIC. Rapport n...

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

    Science.gov (United States)

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

    2015-04-01

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

  20. Towards Physarum Robots: Computing and Manipulating on Water Surface

    Institute of Scientific and Technical Information of China (English)

    Andrew Adamatzky; Jeff Jones

    2008-01-01

    Plasmodium of Physarum polycephalum is an ideal biological substrate for implementing concurrent and parallel com-putation, including combinatorial geometry and optimization on graphs. The scoping experiments on Physarum computing in conditions of minimal friction, on the water surface were performed. The laboratory and computer experimental results show that plasmodium of Physarum is capable of computing a basic spanning tree and manipulating of light-weight objects. We speculate that our results pave the pathways towards the design and implementation of amorphous biological robots.

  1. The contribution of rice agriculture to methylmercury in surface waters: A review of data from the Sacramento Valley, California

    Science.gov (United States)

    Tanner, K. Christy; Windham-Myers, Lisamarie; Fleck, Jacob; Tate, Kenneth W.; McCord, Stephen A.; Linquist, Bruce A.

    2017-01-01

    Methylmercury (MeHg) is a bioaccumulative pollutant produced in and exported from flooded soils, including those used for rice (Oriza sativa L.) production. Using unfiltered aqueous MeHg data from MeHg monitoring programs in the Sacramento River watershed from 1996 to 2007, we assessed the MeHg contribution from rice systems to the Sacramento River. Using a mixed-effects regression analysis, we compared MeHg concentrations in agricultural drainage water from rice-dominated regions (AgDrain) to MeHg concentrations in the Sacramento and Feather Rivers, both upstream and downstream of AgDrain inputs. We also calculated MeHg loads from AgDrains and the Sacramento and Feather Rivers. Seasonally, MeHg concentrations were higher during November through May than during June through October, but the differences varied by location. Relative to upstream, November through May AgDrain least-squares mean MeHg concentration (0.18 ng L−1, range 0.15–0.23 ng L−1) was 2.3-fold higher, while June through October AgDrain mean concentration (0.097 ng L−1, range 0.6–1.6 ng L−1) was not significantly different from upstream. June through October AgDrain MeHg loads contributed 10.7 to 14.8% of the total Sacramento River MeHg load. Missing flow data prevented calculation of the percent contribution of AgDrains in November through May. At sites where calculation was possible, November through May loads made up 70 to 90% of the total annual load. Elevated flow and MeHg concentration in November through May both contribute to the majority of the AgDrain MeHg load occurring during this period. Methylmercury reduction efforts should target elevated November through May MeHg concentrations in AgDrains. However, our findings suggest that the contribution and environmental impact of rice is an order of magnitude lower than previous studies in the California Yolo Bypass.

  2. Rapid quantification method for Legionella pneumophila in surface water.

    Science.gov (United States)

    Wunderlich, Anika; Torggler, Carmen; Elsässer, Dennis; Lück, Christian; Niessner, Reinhard; Seidel, Michael

    2016-03-01

    World-wide legionellosis outbreaks caused by evaporative cooling systems have shown that there is a need for rapid screening methods for Legionella pneumophila in water. Antibody-based methods for the quantification of L. pneumophila are rapid, non-laborious, and relatively cheap but not sensitive enough for establishment as a screening method for surface and drinking water. Therefore, preconcentration methods have to be applied in advance to reach the needed sensitivity. In a basic test, monolithic adsorption filtration (MAF) was used as primary preconcentration method that adsorbs L. pneumophila with high efficiency. Ten-liter water samples were concentrated in 10 min and further reduced to 1 mL by centrifugal ultrafiltration (CeUF). The quantification of L. pneumophila strains belonging to the monoclonal subtype Bellingham was performed via flow-based chemiluminescence sandwich microarray immunoassays (CL-SMIA) in 36 min. The whole analysis process takes 90 min. A polyclonal antibody (pAb) against L. pneumophila serogroup 1-12 and a monoclonal antibody (mAb) against L. pneumophila SG 1 strain Bellingham were immobilized on a microarray chip. Without preconcentration, the detection limit was 4.0 × 10(3) and 2.8 × 10(3) CFU/mL determined by pAb and mAb 10/6, respectively. For samples processed by MAF-CeUF prior to SMIA detection, the limit of detection (LOD) could be decreased to 8.7 CFU/mL and 0.39 CFU/mL, respectively. A recovery of 99.8 ± 15.9% was achieved for concentrations between 1-1000 CFU/mL. The established combined analytical method is sensitive for rapid screening of surface and drinking water to allow fast hygiene control of L. pneumophila.

  3. Investigation of natural biofilms formed during the production of drinking water from surface water embankment filtration.

    Science.gov (United States)

    Emtiazi, Farahnaz; Schwartz, Thomas; Marten, Silke Mareike; Krolla-Sidenstein, Peter; Obst, Ursula

    2004-03-01

    Populations of bacteria in biofilms from different sites of a drinking water production system were analysed. Polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) analyses revealed changing DNA band patterns, suggesting a population shift during bank filtration and processing at the waterworks. In addition, common DNA bands that were attributed to ubiquitous bacteria were found. Biofilms even developed directly after UV disinfection (1-2m distance). Their DNA band patterns only partly agreed with those of the biofilms from the downstream distribution system. Opportunistic pathogenic bacteria in biofilms were analysed using PCR and Southern blot hybridisation (SBH). Surface water appeared to have a direct influence on the composition of biofilms in the drinking water distribution system. In spite of preceding filtration and UV disinfection, opportunistic pathogens such as atypical mycobacteria and Legionella spp. were found in biofilms of drinking water, and Pseudomonas aeruginosa was detected sporadically. Enterococci were not found in any biofilm. Bacterial cell counts in the biofilms from surface water to drinking water dropped significantly, and esterase and alanine-aminopeptidase activity decreased. beta-glucosidase activity was not found in the biofilms. Contrary to the results for planktonic bacteria, inhibitory effects were not observed in biofilms. This suggested an increased tolerance of biofilm bacteria against toxic compounds.

  4. Crawling beneath the free surface: Water snail locomotion

    Science.gov (United States)

    Lee, Sungyon; Bush, John W. M.; Hosoi, A. E.; Lauga, Eric

    2008-08-01

    Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small-amplitude interfacial deformations. By assuming the shape of the snail foot to be a traveling sine wave and the mucus to be Newtonian, an evolution equation for the interface shape is obtained and the resulting propulsive force on the snail is calculated. This propulsive force is found to be nonzero for moderate values of the capillary number but vanishes in the limits of high and low capillary number. Physically, this force arises because the snail's foot deforms the free surface, thereby generating curvature pressures and lubrication flows inside the mucus layer that couple to the topography of the foot.

  5. Self-powered sensor for trace Hg2+ detection.

    Science.gov (United States)

    Wen, Dan; Deng, Liu; Guo, Shaojun; Dong, Shaojun

    2011-05-15

    A self-powered electrochemical sensor has been facilely designed for sensitive detection of Hg(2+) based on the inhibition of biocatalysis process of enzymatic biofuel cell (BFC) for the first time. The as-prepared one-compartment BFC, which was consisted of alcohol dehydrogenase supported on single-walled carbon nanohorns-based mediator system as the anode and bilirubin oxidase as the cathodic biocatalyst, generated an open circuit potential (V(oc)) of 636 mV and a maximum power density of 137 μW cm(-2). It was interestingly found that the presence of Hg(2+) would affect the performance of the constructed BFC (e.g., V(oc)). Taking advantage of the inhibitive effect of Hg(2+), a novel self-powered Hg(2+) sensor has been developed, which showed a linear range of 1-500 nM (R(2) = 0.999) with a detection limit of 1 nM at room temperature. In addition, this BFC-type sensor exhibited good selectivity for Hg(2+) against other common environmental metal ions, and the feasibility of the method for Hg(2+) detection in actual water samples (i.e., tap, ground, and lake water) was demonstrated with satisfactory results.

  6. Observation of the vortex ring interacting with free surface of water

    OpenAIRE

    Nagata, Hiroshi; Sugaya, Shuji; 永田 拓; 菅谷 修士

    2002-01-01

    Vortex structures of the vortex rings ejected parallel or perpendicular to a free surface of water were studied by means of flow visualization experiments. The emphasis is on the process of vortex deformation, induction of the flow on the free surface, evolution of surface vortices and interaction between the surface vortices and vortices in the water. Experiments were conducted under the two surface conditions, i.e. a clean surface and a surface contaminated with surfactant droplets. The ele...

  7. Influence of surface polarity on water dynamics at the water/rutile TiO₂(110) interface.

    Science.gov (United States)

    Ohto, Tatsuhiko; Mishra, Ankur; Yoshimune, Seiji; Nakamura, Hisao; Bonn, Mischa; Nagata, Yuki

    2014-06-18

    We report molecular dynamics (MD) simulations of the water/clean rutile TiO2 (110) interface using polarizable and non-surface polarity force field models. The effect of surface polarity on the water dynamics near the TiO2(110) surface is addressed, specifically by calculating the water hydrogen bond and reorientational dynamics. The hydrogen bond lifetime of interfacial water molecules is several times longer than that of bulk water due to the strong water-TiO2 interactions. A comparison of the dynamics simulated with the polarizable and non-surface polarity models shows that, while the hydrogen bond lifetime between the interfacial water and TiO2 surface is insensitive to the surface polarity, the reorientational dynamics around this hydrogen bond axis is significantly influenced by the surface polarity; the surface polarity of the TiO2 increases the water-TiO2 interactions, stabilizing the local structure of the interfacial water molecules and restricting their rotational motion. This reorientation occurs predominantly by rotation around the O-H group hydrogen bonded to the TiO2 surface. Furthermore, we correlate the dynamics of the induced charge on the TiO2 surface with the interfacial water dynamics. Our results show that the timescale of correlations of the atom charges induced by the local electric field in bulk water is influenced by the rotational motion, hydrogen bond rearrangement and translational motion, while the induced charge dynamics of the TiO2 surface is governed primarily by the rotational dynamics of the interfacial water molecules. This study demonstrates that the solid surface polarity has a significant impact on the dynamics of water molecules near TiO2 surfaces.

  8. Drinking Water Sources with Surface Intakes from LDHH source data, Geographic NAD83, LOSCO (1999) [drinking_water_surface_intakes_LDHH_1999

    Data.gov (United States)

    Louisiana Geographic Information Center — This is a point dataset for 87 public drinking water sources with surface intakes. It was derived from a larger statewide general drinking water source dataset...

  9. Quality of surface-water supplies in the Triangle area of North Carolina, water year 2009

    Science.gov (United States)

    Pfeifle, C. A.; Giorgino, M. J.; Rasmussen, R. B.

    2014-01-01

    Surface-water supplies are important sources of drinking water for residents in the Triangle area of North Carolina, which is located within the upper Cape Fear and Neuse River Basins. Since 1988, the U.S. Geological Survey and a consortium of governments have tracked water-quality conditions and trends in several of the area’s water-supply lakes and streams. This report summarizes data collected through this cooperative effort, known as the Triangle Area Water Supply Monitoring Project, during October 2008 through September 2009. Major findings for this period include: - Annual precipitation was approximately 20 percent below the long-term mean (average) annual precipitation. - Streamflow was below the long-term mean at the 10 project streamgages during most of the year. - More than 7,000 individual measurements of water quality were made at a total of 26 sites—15 in the Neuse River Basin and 11 in the Cape Fear River Basin. Forty-seven water-quality properties and constituents were measured. - All observations met North Carolina water-quality standards for water temperature, pH, hardness, chloride, fluoride, sulfate, nitrate, arsenic, cadmium, chromium, lead, nickel, and selenium. - North Carolina water-quality standards were exceeded one or more times for dissolved oxygen, dissolved oxygen percent saturation, chlorophyll a, mercury, copper, iron, manganese, silver, and zinc. Exceedances occurred at 23 sites—13 in the Neuse River Basin and 10 in the Cape Fear River Basin. - Stream samples collected during storm events contained elevated concentrations of 18 water-quality constituents compared to samples collected during non-storm events. - Concentrations of nitrogen and phosphorus were within ranges observed during previous years. - Five reservoirs had chlorophyll a concentrations in excess of 40 micrograms per liter at least once during 2009: Little River Reservoir, Falls Lake, Cane Creek Reservoir, University Lake, and Jordan Lake.

  10. Water adsorption and dissociation on BeO (001) and (100) surfaces

    CERN Document Server

    Gómez, M A; Kress, J D; Pratt, L R; Gomez, Maria A.; Kress, Joel D.; Pratt, Lawrence R.

    2007-01-01

    Plateaus in water adsorption isotherms on hydroxylated BeO surfaces suggest significant differences between the hydroxylated (100) and (001) surface structures and reactivities. Density functional theory structures and energies clarify these differences. Using relaxed surface energies, a Wulff construction yields a prism crystal shape exposing long (100) sides and much smaller (001) faces. This is consistent with the BeO prisms observed when beryllium metal is oxidized. A water oxygen atom binds to a single surface beryllium ion in the preferred adsorption geometry on either surface. The water oxygen/beryllium bonding is stronger on the surface with greater beryllium atom exposure, namely the less-stable (001) surface. Water/beryllium coordination facilitates water dissociation. On the (001) surface, the dissociation products are a hydroxide bridging two beryllium ions and a metal coordinated hydride with some surface charge depletion. On the (100) surface, water dissociates into a hydroxide ligating a Be ato...

  11. Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed wetlands

    Institute of Scientific and Technical Information of China (English)

    Juan WU; Jian ZHANG; Wenlin JIA; Huijun XIE; Bo ZHANG

    2009-01-01

    The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N2O) emissions, together with the relationships between N2O and water quality parameters in free water surface constructed wetlands, were investigated with laboratoryscale systems. N20 emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and the total N2O emission in the system with middle COD influent concentration was the least. The relationships between N2O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N2O flux. The multiple linear regression model against principal components indicated that different water parameters affected N2O flux with different COD concentrations in the influent, but nitrate nitrogen affected N2O flux in all systems.

  12. A land surface scheme for atmospheric and hydrologic models: SEWAB (Surface Energy and Water Balance)

    Energy Technology Data Exchange (ETDEWEB)

    Mengelkamp, H.T.; Warrach, K.; Raschke, E. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

    1997-12-31

    A soil-vegetation-atmosphere-transfer scheme is presented here which solves the coupled system of the Surface Energy and Water Balance (SEWAB) equations considering partly vegetated surfaces. It is based on the one-layer concept for vegetation. In the soil the diffusion equations for heat and moisture are solved on a multi-layer grid. SEWAB has been developed to serve as a land-surface scheme for atmospheric circulation models. Being forced with atmospheric data from either simulations or measurements it calculates surface and subsurface runoff that can serve as input to hydrologic models. The model has been validated with field data from the FIFE experiment and has participated in the PILPS project for intercomparison of land-surface parameterization schemes. From these experiments we feel that SEWAB reasonably well partitions the radiation and precipitation into sensible and latent heat fluxes as well as into runoff and soil moisture Storage. (orig.) [Deutsch] Ein Landoberflaechenschema wird vorgestellt, das den Transport von Waerme und Wasser zwischen dem Erdboden, der Vegetation und der Atmosphaere unter Beruecksichtigung von teilweise bewachsenem Boden beschreibt. Im Erdboden werden die Diffusionsgleichungen fuer Waerme und Feuchte auf einem Gitter mit mehreren Schichten geloest. Das Schema SEWAB (Surface Energy and Water Balance) beschreibt die Landoberflaechenprozesse in atmosphaerischen Modellen und berechnet den Oberflaechenabfluss und den Basisabfluss, die als Eingabedaten fuer hydrologische Modelle genutzt werden koennen. Das Modell wurde mit Daten des FIFE-Experiments kalibriert und hat an Vergleichsexperimenten fuer Landoberflaechen-Schemata im Rahmen des PILPS-Projektes teilgenommen. Dabei hat sich gezeigt, dass die Aufteilung der einfallenden Strahlung und des Niederschlages in den sensiblen und latenten Waermefluss und auch in Abfluss und Speicherung der Bodenfeuchte in SEWAB den beobachteten Daten recht gut entspricht. (orig.)

  13. Highly sensitive optical sensor that detects Hg{sup 2+} and Cu{sup 2+} by immobilizing dicarboxylate 1,5-diphenyl-3-thiocarbazone on surface functionalized PVA microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Xue, E-mail: baixue@hhu.edu.cn; Gu, Haixin; Hua, Zulin; Dai, Zhangyan; Yang, Bei; Li, Yulong

    2015-11-15

    Highlights: • PVA microspheres were chosen as carrier and DDT groups were chosen as chromophores. • The DDT–PVA microspheres could detect Hg{sup 2+} and Cu{sup 2+} simultaneously within 120 s. • The DDT–PVA microspheres had excellent detection for Hg{sup 2+} and Cu{sup 2+} ions. • The DDT–PVA microspheres had preeminent selectivity and reusability. - Abstract: A novel optical sensor to detect Hg{sup 2+} and Cu{sup 2+} is prepared by immobilizing a synthesized dicarboxylate 1,5-diphenyl-3-thiocarbazone (DDT) group on functionalized polyvinyl alcohol (PVA) microspheres. This optical sensor is successfully fabricated by extensive characterization with Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Its colorimetric properties, selectivity, sensitivity, and reversibility are investigated as well. In this sensing system, DDT–PVA selectively recognized multiple heavy metal ions, as indicated by the changes in color from orange to scarlet for Hg{sup 2+} and from orange to gray for Cu{sup 2+}. In particular, this optical sensor exhibits the most apparent color changes at pH levels of 12 and 2. Hence, Hg{sup 2+} and Cu{sup 2+} can be detected in aqueous solution at minimum detection limits of 0.053 and 0.132 μM, respectively, with a UV-vis spectrometer. Furthermore, the sensor can be regenerated by ethylene diamine tetraacetic acid and reused several times. Therefore, the optical sensor can detect Hg{sup 2+} because of its selectivity, sensitivity, and reversibility.

  14. Comparison of fipronil sources in North Carolina surface water ...

    Science.gov (United States)

    Fipronil is a phenylpyrazole insecticide that is widely used in residential and agricultural settings to control ants, roaches, termites, and other pests. Fipronil and its transformation products have been found in a variety of environmental matrices, but the source[s] which makes the greatest contribution to fipronil in surface water has yet to be determined. A sampling effort designed to prioritize known fipronil inputs (golf courses, residential areas, biosolids application sites and wastewater facilities) was conducted in North Carolina to learn more about the origins of fipronil in surface water. High resolution mass spectrometry (HRMS) analysis indicated that fipronil and its known derivatives were routinely present in all samples, but concentrations were substantially elevated near wastewater treatment plant outfalls (range 10–500 ng/L combined), suggesting that they predominate as environmental sources. Corresponding recycled wastewater samples, which were treated with NaOCl for disinfection, showed disappearance of fipronil and all known degradates. HRMS and nuclear magnetic resonance (NMR) analysis techniques were used to determine that all fipronil-related compounds are oxidized to a previously unidentified fipronil sulfone chloramine species in recycled wastewater. The implications of the presence of a new fipronil-related compound in recycled wastewater need to be considered. Journal Article Highlights • The most important sources of fipronil in

  15. Water drop impact onto oil covered solid surfaces

    Science.gov (United States)

    Chen, Ningli; Chen, Huanchen; Amirfazli, Alidad

    2016-11-01

    Droplet impact onto an oily surface can be encountered routinely in industrial applications; e.g., in spray cooling. It is not clear from literature what impact an oil film may have on the impact process. In this work, water drop impact onto both hydrophobic (glass) and hydrophilic (OTS) substrates which were covered by oil films (silicone) of different thickness (5um-50um) and viscosity (5cst-100cst) were performed. The effects of drop impact velocity, film thickness, and viscosity of the oil film and wettability of the substrate were studied. Our results show that when the film viscosity and impact velocity is low, the water drop deformed into the usual disk shape after impact, and rebounded from the surface. Such rebound phenomena disappears, when the viscosity of oil becomes very large. With the increase of the impact velocity, crown and splashing appears in the spreading phase. The crown and splashing behavior appears more easily with the increase of film thickness and decrease of its viscosity. It was also found that the substrate wettability can only affect the impact process in cases which drop has a large Webber number (We = 594), and the film's viscosity and thickness are small. This work was support by National Natural Science Foundation of China and the Project Number is 51506084.

  16. Integrated modeling of groundwater–surface water interactions in a tile-drained agricultural field

    NARCIS (Netherlands)

    Rosemeijer, J.C.; Velde, van der Y.; McLaren, R.G.; Geer, van F.C.; Broers, H.P.; Bierkens, M.F.P.

    2010-01-01

    Understanding the dynamics of groundwater–surface water interaction is needed to evaluate and simulate water and solute transport in catchments. However, direct measurements of the contributions of different flow routes from specific surfaces within a catchment toward the surface water are rarely av

  17. Reducing phosphorus loading of surface water using iron-coated sand

    NARCIS (Netherlands)

    Groenenberg, J.E.; Chardon, W.J.; Koopmans, G.F.

    2013-01-01

    Phosphorus losses from agricultural soils is an important source of P in surface waters leading to surface water quality impairment. In addition to reducing P inputs, mitigation measures are needed to reduce P enrichment of surface waters. Because drainage of agricultural land by pipe drainage is an

  18. Conductivity as an indicator of surface water quality in the proximity ...

    African Journals Online (AJOL)

    2015-10-05

    Oct 5, 2015 ... Conductivity as an indicator of surface water quality in the ... FeCr smelting did not significantly impact surface water quality, but that surface run-off and/or ..... farming-management/soil-water/salinity/measuring-the-salinity-.

  19. Development of Hydrophobic Coatings for Water-Repellent Surfaces Using Hybrid Methodology

    Science.gov (United States)

    2014-04-01

    windows, optical components, protective eyewear, and clothing, this type of surface is desired for the material to be soil repellent and water ...Development of Hydrophobic Coatings for Water - Repellent Surfaces Using Hybrid Methodology by Amanda S. Weerasooriya, Jacqueline Yim, Andres A...Proving Ground, MD 21005-5069 ARL-TR-6898 April 2014 Development of Hydrophobic Coatings for Water - Repellent Surfaces Using Hybrid

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

    Science.gov (United States)

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

    2016-04-01

    Forest harvesting, especially when intensified harvesting method as whole-tree harvesting with stump lifting (WTHs) are used, may increase mercury (Hg) and methylmercury (MeHg) leaching to recipient water courses. The effect can be enhanced if the underlying bedrock and overburden soil contain Hg. The impact of stem-only harvesting (SOH) and WTHs on the concentrations of Hg and MeHg as well as several other variables in the ditch water was studied using a paired catchment approach in eight drained peatland-dominated catchments in Finland (2008-2012). Four of the catchments were on felsic bedrock and four on black schist bedrock containing heavy metals. Although both Hg and MeHg concentrations increased after harvesting in all treated sites according to the randomized intervention analyses (RIAs), there was only a weak indication of a harvest-induced mobilization of Hg and MeHg into the ditches. Furthermore, no clear differences between WTHs and SOH were found, although MeHg showed a nearly significant difference (p = 0.06) between the harvesting regimes. However, there was a clear bedrock effect, since the MeHg concentrations in the ditch water were higher at catchments on black schist than at those on felsic bedrock. The pH, suspended solid matter (SSM), dissolved organic carbon (DOC), and iron (Fe) concentrations increased after harvest while the sulfate (SO4-S) concentration decreased. The highest abundances of sulfate-reducing bacteria (SRB) were found on the sites with high MeHg concentrations. The biggest changes in ditch water concentrations occurred first 2 years after harvesting.

  1. Hydraulic "fracking": are surface water impacts an ecological concern?

    Science.gov (United States)

    Burton, G Allen; Basu, Niladri; Ellis, Brian R; Kapo, Katherine E; Entrekin, Sally; Nadelhoffer, Knute

    2014-08-01

    Use of high-volume hydraulic fracturing (HVHF) in unconventional reservoirs to recover previously inaccessible oil and natural gas is rapidly expanding in North America and elsewhere. Although hydraulic fracturing has been practiced for decades, the advent of more technologically advanced horizontal drilling coupled with improved slickwater chemical formulations has allowed extensive natural gas and oil deposits to be recovered from shale formations. Millions of liters of local groundwaters are utilized to generate extensive fracture networks within these low-permeability reservoirs, allowing extraction of the trapped hydrocarbons. Although the technology is relatively standardized, the geographies and related policies and regulations guiding these operations vary markedly. Some ecosystems are more at risk from these operations than others because of either their sensitivities or the manner in which the HVHF operations are conducted. Generally, the closer geographical proximity of the susceptible ecosystem to a drilling site or a location of related industrial processes, the higher the risk of that ecosystem being impacted by the operation. The associated construction of roads, power grids, pipelines, well pads, and water-extraction systems along with increased truck traffic are common to virtually all HVHF operations. These operations may result in increased erosion and sedimentation, increased risk to aquatic ecosystems from chemical spills or runoff, habitat fragmentation, loss of stream riparian zones, altered biogeochemical cycling, and reduction of available surface and hyporheic water volumes because of withdrawal-induced lowering of local groundwater levels. The potential risks to surface waters from HVHF operations are similar in many ways to those resulting from agriculture, silviculture, mining, and urban development. Indeed, groundwater extraction associated with agriculture is perhaps a larger concern in the long term in some regions. Understanding the

  2. Transport and fate of nitrate at the ground-water/surface-water interface

    Science.gov (United States)

    Puckett, L.J.; Zamora, C.; Essaid, H.; Wilson, J.T.; Johnson, H.M.; Brayton, M.J.; Vogel, J.R.

    2008-01-01

    Although numerous studies of hyporheic exchange and denitrification have been conducted in pristine, high-gradient streams, few studies of this type have been conducted in nutrient-rich, low-gradient streams. This is a particularly important subject given the interest in nitrogen (N) inputs to the Gulf of Mexico and other eutrophic aquatic systems. A combination of hydrologic, mineralogical, chemical, dissolved gas, and isotopic data, were used to determine the processes controlling transport and fate of NO3- in streambeds at five sites across the USA. Water samples were collected from streambeds at depths ranging from 0.3 to 3 m at three to five points across the stream and in two to five separate transects. Residence times of water ranging from 0.28 to 34.7 d m-1 in the streambeds of N-rich watersheds played an important role in allowing denitrification to decrease NO3- concentrations. Where potential electron donors were limited and residence times were short, denitrification was limited. Consequently, in spite of reducing conditions at some sites, NO3- was transported into the stream. At two of the five study sites, NO3- in surface water infiltrated the streambeds and concentrations decreased, supporting current models that NO3- would be retained in N-rich streams. At the other three study sites, hydrogeologic controls limited or prevented infiltration of surface water into the streambed, and ground-water discharge contributed to NO 3- loads. Our results also show that in these low hydrologic-gradient systems, storm and other high-flow events can be important factors for increasing surface-water movement into streambeds. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  3. Numerical study of surface water waves generated by mass movement

    Energy Technology Data Exchange (ETDEWEB)

    Ghozlani, Belgacem; Hafsia, Zouhaier; Maalel, Khlifa, E-mail: ghozlanib@yahoo.fr [Ecole Nationale d' Ingenieurs de Tunis, Laboratoire de Modelisation en ' Hydraulique et Environnement, BP 37, Le Belvedere, 1002 Tunis (Tunisia)

    2013-10-01

    In this paper waves generated by two-dimensional mass movement are simulated using a numerical model based on the full hydrodynamic coupling between rigid-body motion and ambient fluid flow. This approach has the capability to represent the dynamics of the moving rigid body, which avoids the need to prescribe the body velocity based on the data measurements. This model is implemented in the CFX code and uses the Reynolds average Navier-Stokes equations solver coupled to the recently developed immersed solid technique. The latter technique allows us to follow implicitly the motion of the solid block based on the rigid body solver. The volume-of-fluid method is used to track the free surface locations. The accuracy of the present model is firstly examined against the simple physical case of a freely falling rigid body into water reproducing Scott Russell's solitary waves. More complex and realistic simulations of aerial and submarine mass-movement, simulated by a rigid wedge sliding into water along a 45 Degree-Sign slope, are then performed. Simulated results of the aerial mass movement show the complex flow patterns in terms of the velocity fields and free surface profiles. Results are in good agreement with the available experimental data. In addition, the physical processes associated with the generation of water wave by two-dimensional submarine mass-movement are explored. The effects of the initial submergence and specific gravity on the slide mass kinematics and maximum wave amplitude are investigated. The terminal velocity and initial acceleration of the slide mass are well predicted when compared to experimental results. It is found that the initial submergence did not have a significant effect on the initial acceleration of the slide block centre of mass. However, it depends nonlinearly on the specific gravity. The maximum wave amplitude and the time at which it occurred are also presented as a function of the initial submergence and specific gravity

  4. Numerical study of surface water waves generated by mass movement

    Science.gov (United States)

    Ghozlani, Belgacem; Hafsia, Zouhaier; Maalel, Khlifa

    2013-10-01

    In this paper waves generated by two-dimensional mass movement are simulated using a numerical model based on the full hydrodynamic coupling between rigid-body motion and ambient fluid flow. This approach has the capability to represent the dynamics of the moving rigid body, which avoids the need to prescribe the body velocity based on the data measurements. This model is implemented in the CFX code and uses the Reynolds average Navier-Stokes equations solver coupled to the recently developed immersed solid technique. The latter technique allows us to follow implicitly the motion of the solid block based on the rigid body solver. The volume-of-fluid method is used to track the free surface locations. The accuracy of the present model is firstly examined against the simple physical case of a freely falling rigid body into water reproducing Scott Russell's solitary waves. More complex and realistic simulations of aerial and submarine mass-movement, simulated by a rigid wedge sliding into water along a 45° slope, are then performed. Simulated results of the aerial mass movement show the complex flow patterns in terms of the velocity fields and free surface profiles. Results are in good agreement with the available experimental data. In addition, the physical processes associated with the generation of water wave by two-dimensional submarine mass-movement are explored. The effects of the initial submergence and specific gravity on the slide mass kinematics and maximum wave amplitude are investigated. The terminal velocity and initial acceleration of the slide mass are well predicted when compared to experimental results. It is found that the initial submergence did not have a significant effect on the initial acceleration of the slide block centre of mass. However, it depends nonlinearly\\vadjust{\

  5. Microdroplet growth mechanism during water condensation on superhydrophobic surfaces.

    Science.gov (United States)

    Rykaczewski, Konrad

    2012-05-22

    By promoting dropwise condensation of water, nanostructured superhydrophobic coatings have the potential to dramatically increase the heat transfer rate during this phase change process. As a consequence, these coatings may be a facile method of enhancing the efficiency of power generation and water desalination systems. However, the microdroplet growth mechanism on surfaces which evince superhydrophobic characteristics during condensation is not well understood. In this work, the sub-10 μm dynamics of droplet formation on nanostructured superhydrophobic surfaces are studied experimentally and theoretically. A quantitative model for droplet growth in the constant base (CB) area mode is developed. The model is validated using optimized environmental scanning electron microscopy (ESEM) imaging of microdroplet growth on a superhydrophobic surface consisting of immobilized alumina nanoparticles modified with a hydrophobic promoter. The optimized ESEM imaging procedure increases the image acquisition rate by a factor of 10-50 as compared to previous research. With the improved imaging temporal resolution, it is demonstrated that nucleating nanodroplets coalesce to create a wetted flat spot with a diameter of a few micrometers from which the microdroplet emerges in purely CB mode. After the droplet reaches a contact angle of 130-150°, its base diameter increases in a discrete steplike fashion. The droplet height does not change appreciably during this steplike base diameter increase, leading to a small decrease of the contact angle. Subsequently, the drop grows in CB mode until it again reaches the maximum contact angle and increases its base diameter in a steplike fashion. This microscopic stick-and-slip motion can occur up to four times prior to the droplet coalescence with neighboring drops. Lastly, the constant contact angle (CCA) and the CB growth models are used to show that modeling formation of a droplet with a 150° contact angle in the CCA mode rather than in

  6. Hydrogen yields from water on the surface of plutonium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Sims, Howard E., E-mail: howard.e.sims@nnl.co.uk [National Nuclear Laboratory, Harwell Science Park, Didcot, Oxon OX11 0QT (United Kingdom); Webb, Kevin J.; Brown, Jamie [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale CA20 1PG (United Kingdom); Morris, Darrell [Nuclear Decommissioning Authority, Herdus House, Westlakes Science and Technology Park, Moor Row, Cumbria CA24 3HU (United Kingdom); Taylor, Robin J., E-mail: robin.j.taylor@nnl.co.uk [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale CA20 1PG (United Kingdom)

    2013-06-15

    Highlights: ► Hydrogen evolution due to water radiolysis on samples of Sellafield PuO{sub 2}. ► Sharp increase in hydrogen evolution above 75% relative humidity. ► Hydrogen evolution due to radiolytic rather than thermal reaction. ► Analysis of trends from literature data. -- Abstract: The long term storage of separated plutonium dioxide (PuO{sub 2}) in sealed canisters requires an understanding of the processes occurring within the cans. This includes potential mechanisms that lead to can pressurisation, including the radiolysis of adsorbed water forming hydrogen. New measurements of H{sub 2} production rates from three sources of PuO{sub 2} show low rates at low water monolayer coverage but a sharp increase between 75% and 95% relative humidity. This behaviour being quite different to that reported for CeO{sub 2} and UO{sub 2}, which, therefore, cannot be considered as suitable analogues for PuO{sub 2}/H{sub 2}O radiation chemistry. It is concluded that surface recombination reactions are likely to be important in the radiation chemistry and that the H{sub 2} production arises from a radiolytic process and not a thermal reaction, at least in these experiments.

  7. Metagenomes of Microbial Communities in Arsenic- and Pathogen-Contaminated Well and Surface Water from Bangladesh

    OpenAIRE

    Layton, Alice C.; Chauhan, Archana; Williams, Daniel E.; Mailloux, Brian; Knappett, Peter S. K.; Ferguson, Andrew S.; McKay, Larry D.; Alam, M. Jahangir; Matin Ahmed, Kazi; van Geen, Alexander; Sayler, Gary S.

    2014-01-01

    The contamination of drinking water from both arsenic and microbial pathogens occurs in Bangladesh. A general metagenomic survey of well water and surface water provided information on the types of pathogens present and may help elucidate arsenic metabolic pathways and potential assay targets for monitoring surface-to-ground water pathogen transport.

  8. Assessment of Hg contamination and exposure to miners and schoolchildren at a small-scale gold mining and recovery operation in Thailand.

    Science.gov (United States)

    Umbangtalad, S; Parkpian, P; Visvanathan, C; Delaune, R D; Jugsujinda, A

    2007-12-01

    Gold extracted by Hg-amalgamation process, which can cause both health and environmental problems, is widespread in South East Asia including Myanmar, Laos, Cambodia, and Thailand. Small-scale gold mining operations have been carried out since the year 2000 in Phanom Pha District, Phichit Province, Thailand. Since no data is available for evaluating Hg exposure, an investigation of mercury (Hg) contamination and exposure assessment was carried out at this mine site. Environmental monitoring illustrated the total Hg in water was as high as 4 microg/l while Hg in sediment ranged between 102 to 325 microg/kg dry weight. Both Hg deposition from the air (1.28 microg/100 cm(2)/day) and concentration in surface soil (20,960 microg/kg dry weight) were elevated in the area of amalgamation. The potential of Hg exposure to miners as well as to schoolchildren was assessed. The concentrations of Hg in urine of 79 miners who were directly (group I) or indirectly (group II) involved in the gold recovery operation were 32.02 and 20.04 microg/g creatinine, respectively, which did not exceed regulatory limits (35 microg/g creatinine). Hair Hg levels in both groups (group I and group II) also were not significantly higher than the non-exposed group. In terms of risk factors, gender and nature of food preparation and consumption were the two significant variables influencing the concentration of Hg in urine of miners (P < 0.05). A hazard quotient (HQ) was estimated based on the inorganic Hg exposure of individual miners. The HQ values of group I were in a range 16 to 218 times higher than the safety level set as 1. By comparison the group II HQ index was very low (0.03-0.39). The miners in group I who worked and ate food from this area experienced potentially high exposure to Hg associated with the mining process. In a second Hg exposure assessment, a group of 59 schoolchildren who attended an elementary school near the gold mine site was evaluated for Hg exposure. A slightly higher

  9. Crawling beneath the free surface: Water snail locomotion

    CERN Document Server

    Lee, Sungyon; Hosoi, A E; Lauga, Eric

    2008-01-01

    Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small amplitude interfacial deformations. By assuming the shape of the snail foot to be a traveling sine wave and the mucus to be Newtonian, an evolution equation for the interface shape is obtained and the resulting propulsive force on the snail is calculated. This propulsive force is found to be non-zero for moderate values of Capillar...

  10. Detection of heavy metal ions in contaminated water by surface plasmon resonance based optical fibre sensor using conducting polymer and chitosan.

    Science.gov (United States)

    Verma, Roli; Gupta, Banshi D

    2015-01-01

    Optical fibre surface plasmon resonance (SPR) based sensor for the detection of heavy metal ions in the drinking water is designed. Silver (Ag) metal and indium tin oxide (ITO) are used for the fabrication of the SPR probe which is further modified with the coating of pyrrole and chitosan composite. The sensor works on the wavelength interrogation technique and is capable of detecting trace amounts of Cd(2+), Pb(2+), and Hg(2+) heavy metal ions in contaminated water. Four types of sensing probes are fabricated and characterised for heavy metal ions out of these pyrrole/chitosan/ITO/Ag coated probe is found to be highly sensitive among all other probes. Further, the cadmium ions bind strongly to the sensing surface than other ions and due to this the sensor is highly sensitive for Cd(2+) ions. The sensor's performance is best for the low concentrations of heavy metal ions and its sensitivity decreases with the increasing concentration of heavy metal ions.

  11. Groundwater/Surface-Water Interaction in the Context of South African Water Policy

    Science.gov (United States)

    Levy, J.; Xu, Y.

    2010-12-01

    Groundwater/surface-water interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. South Africa’s 1998 National Water Act (NWA) recognized water as a basic human right and its importance for ecological sustainability. Ecological integrity of water resources was considered an important component in redressing past social inequities, eliminating poverty, and encouraging economic development. Under the NWA, groundwater-use licenses are granted only after setting aside the groundwater Reserve, the amount of water needed to supply basic human needs and preserve a minimum degree of ecological integrity. One challenge to successful implementation of the NWA, therefore, is the accurate quantification of groundwater contributions to aquatic ecosystems. This is especially true considering that so many of South Africa’s aquifers are in highly heterogeneous and anisotropic fractured-rock settings. The most common approach taken in South Africa is estimation of average annual flux rates at the regional scale of quaternary catchments with baseflow separation techniques and then applying a water-budget approach, subtracting the groundwater discharge rate from the recharge rate. The water-balance approach might be a good first step, but it ignores spatial and temporal variability, potentially missing the local impacts associated with placement of production boreholes. Identification of discrete areas of groundwater discharge could be achieved with stable-isotopic and geochemical analyses and vegetative mapping. Groundwater-flow modeling should be used where possible as it holistically incorporates available data and can predict impacts of groundwater extraction and development based on the relative positions of boreholes and surface-water bodies. Sustainable development entails recognition of the trade-offs between preservation and development. There will always be scientific uncertainty associated with estimation and

  12. Water repellency on a fluorine-containing polyurethane surface: toward understanding the surface self-cleaning effect.

    Science.gov (United States)

    Wu, Wanling; Zhu, Qingzeng; Qing, Fengling; Han, Charles C

    2009-01-06

    Surface geometrical microstructure and low surface free energy are the two most important factors for a self-cleaning surface. In this study, multiform geometrical microstructured surfaces were fabricated by casting and electrospinning polyurethanes with and without low surface energy segments. The effect of low surface energy on water repellency was evaluated. Low surface energy seems to make a more significant contribution to the static wetting behavior than do dynamic properties such as the improvement of sliding behavior. Sucking disk behavior was brought forward to explain the pinning state of a water droplet on hydrophobic surfaces with high water contact angles (>150 degrees ). A better understanding of the relationship between the static contact angle and the dynamic sliding property was provided.

  13. Hydrological Response to ~30 years of Agricultural Surface Water Management

    Directory of Open Access Journals (Sweden)

    Giulia Sofia

    2017-01-01

    Full Text Available Amongst human practices, agricultural surface-water management systems represent some of the largest integrated engineering works that shaped floodplains during history, directly or indirectly affecting the landscape. As a result of changes in agricultural practices and land use, many drainage networks have changed producing a greater exposure to flooding with a broad range of impacts on society, also because of climate inputs coupling with the human drivers. This research focuses on three main questions: which kind of land use changes related to the agricultural practices have been observed in the most recent years (~30 years? How does the influence on the watershed response to land use and land cover changes depend on the rainfall event characteristics and soil conditions, and what is their related significance? The investigation presented in this work includes modelling the water infiltration due to the soil properties and analysing the distributed water storage offered by the agricultural drainage system in a study area in Veneto (north-eastern Italy. The results show that economic changes control the development of agro-industrial landscapes, with effects on the hydrological response. Key elements that can enhance or reduce differences are the antecedent soil conditions and the climate characteristics. Criticalities should be expected for intense and irregular rainfall events, and for events that recurrently happen. Agricultural areas might be perceived to be of low priority when it comes to public funding of flood protection, compared to the priority given to urban ones. These outcomes highlight the importance of understanding how agricultural practices can be the driver of or can be used to avoid, or at least mitigate, flooding. The proposed methods can be valuable tools in evaluating the costs and benefits of the management of water in agriculture to inform better policy decision-making.

  14. Urban surface water pollution problems arising from misconnections.

    Science.gov (United States)

    Revitt, D Michael; Ellis, J Bryan

    2016-05-01

    The impacts of misconnections on the organic and nutrient loadings to surface waters are assessed using specific household appliance data for two urban sub-catchments located in the London metropolitan region and the city of Swansea. Potential loadings of biochemical oxygen demand (BOD), soluble reactive phosphorus (PO4-P) and ammoniacal nitrogen (NH4-N) due to misconnections are calculated for three different scenarios based on the measured daily flows from specific appliances and either measured daily pollutant concentrations or average pollutant concentrations for relevant greywater and black water sources obtained from an extensive review of the literature. Downstream receiving water concentrations, together with the associated uncertainties, are predicted from derived misconnection discharge concentrations and compared to existing freshwater standards for comparable river types. Consideration of dilution ratios indicates that these would need to be of the order of 50-100:1 to maintain high water quality with respect to BOD and NH4-N following typical misconnection discharges but only poor quality for PO4-P is likely to be achievable. The main pollutant loading contributions to misconnections arise from toilets (NH4-N and BOD), kitchen sinks (BOD and PO4-P) washing machines (PO4-P and BOD) and, to a lesser extent, dishwashers (PO4-P). By completely eliminating toilet misconnections and ensuring misconnections from all other appliances do not exceed 2%, the potential pollution problems due to BOD and NH4-N discharges would be alleviated but this would not be the case for PO4-P. In the event of a treatment option being preferred to solve the misconnection problem, it is shown that for an area the size of metropolitan Greater London, a sewage treatment plant with a Population Equivalent value approaching 900,000 would be required to efficiently remove BOD and NH4-N to safely dischargeable levels but such a plant is unlikely to have the capacity to deal

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

    Science.gov (United States)

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

    2017-01-01

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

  16. Use of chemical and isotopic tracers to characterize the interactions between ground water and surface water in mantled karst

    Science.gov (United States)

    Katz, B.G.; Coplen, T.B.; Bullen, T.D.; Hal, Davis J.

    1997-01-01

    In the mantled karst terrane of northern Florida, the water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface. Chemical and isotopic analyses [18O/16O (??18O), 2H/1H (??D), 13C/12C (??13C), tritium(3H), and strontium-87/strontium-86(87Sr/86Sr)]along with geochemical mass-balance modeling were used to identify the dominant hydrochemical processes that control the composition of ground water as it evolves downgradient in two systems. In one system, surface water enters the Upper Floridan aquifer through a sinkhole located in the Northern Highlands physiographic unit. In the other system, surface water enters the aquifer through a sinkhole lake (Lake Bradford) in the Woodville Karst Plain. Differences in the composition of water isotopes (??18O and ??D) in rainfall, ground water, and surface water were used to develop mixing models of surface water (leakage of water to the Upper Floridan aquifer from a sinkhole lake and a sinkhole) and ground water. Using mass-balance calculations, based on differences in ??18O and ??D, the proportion of lake water that mixed with meteoric water ranged from 7 to 86% in water from wells located in close proximity to Lake Bradford. In deeper parts of the Upper Floridan aquifer, water enriched in 18O and D from five of 12 sampled municipal wells indicated that recharge from a sinkhole (1 to 24%) and surface water with an evaporated isotopic signature (2 to 32%) was mixing with ground water. The solute isotopes, ??13C and 87Sr/86Sr, were used to test the sensitivity of binary and ternary mixing models, and to estimate the amount of mass transfer of carbon and other dissolved species in geochemical reactions. In ground water downgradient from Lake Bradford, the dominant processes controlling carbon cycling in ground water were dissolution of carbonate minerals, aerobic degradation of organic matter, and hydrolysis of silicate minerals. In the deeper parts of the Upper

  17. Polyfluorinated compounds in waste water treatment plant effluents and surface waters along the River Elbe, Germany.

    Science.gov (United States)

    Ahrens, Lutz; Felizeter, Sebastian; Sturm, Renate; Xie, Zhiyong; Ebinghaus, Ralf

    2009-09-01

    Polyfluorinated compounds (PFCs) were investigated in waste water treatment plant (WWTP) effluents and surface waters of the River Elbe from samples collected in 2007. Concentrations of various PFCs, including C(4)-C(8) perfluorinated sulfonates (PFSAs), C(6) and C(8) perfluorinated sulfinates, 6:2 fluorotelomer sulfonate, C(5)-C(13) perfluorinated carboxylic acids (PFCAs), C(4) and C(8) perfluoroalkyl sulfonamides and 6:2, 8:2 and 10:2 unsaturated fluorotelomercarboxylic acids were quantified. Sum PFC concentrations of the river water ranged from 7.6 to 26.4ngL(-1), whereas sum PFC concentrations of WWTP effluents were approximately 5-10 times higher (30.5-266.3ngL(-1)), indicating that WWTPs are potential sources of PFCs in the marine environment. PFC patterns of different WWTP effluents varied depending on the origin of the waste water, whereas the profile of PFC composition in the river water was relatively constant. In both kinds of water samples, perfluorooctanoic acid (PFOA) was the major PFC, whereas perfluorobutane sulfonate (PFBS) was the predominant PFSA.

  18. 77 FR 12227 - Long Term 2 Enhanced Surface Water Treatment Rule: Uncovered Finished Water Reservoirs; Public...

    Science.gov (United States)

    2012-02-29

    ...The Environmental Protection Agency (EPA) is hosting a public meeting on April 24, 2012, concerning information that may inform the regulatory review of the uncovered finished water reservoir requirement in the Long Term 2 Enhanced Surface Water Treatment Rule (LT2 rule). At this meeting, EPA will provide background information on the LT2 rule's uncovered finished water reservoir requirement and the agency's Six Year Review process. EPA also plans to discuss and solicit public input on data and information related to microbial occurrence of Cryptosporidium, Giardia, viruses, and other pathogens/indicators in uncovered finished water reservoirs; public health risks; strategies to control or remove contaminants in uncovered finished water reservoirs; and potential assessment approaches to determine the effectiveness of these control and/or removal strategies. The primary focus of this meeting is to have a scientific and technical discussion related to uncovered finished water reservoirs. EPA will consider the data and/or information discussed at this meeting during the agency's review of the LT2 rule, which the agency announced as part of EPA's Retrospective Review Plan under Executive Order (E.O.) 13563 in August 2011.

  19. Preliminary assessment of heavy metal contamination in surface water and sediments from Honghu Lake,East Central China

    Institute of Scientific and Technical Information of China (English)

    Ying HU; Shihua QI; Chenxi WU; Yanping KE; Jing CHEN; Wei CHEN; Xiangyi GONG

    2012-01-01

    Heavy metal concentrations in surface water and sediments collected from Honghu Lake in Hubei Province,China were analyzed,and ecological risks were evaluated according to the sediment quality guidelines.The results showed that the average concentrations of heavy metals in surface water were ranked as:As > Zn >Cu > Cr > Pb > Ni > Cd > Hg.In comparison with results reported in other rivers and the background values,The Honghu Lake was polluted by As,Cr,Pb,Cu and Ni.Most of metals might be mainly from fertilizers,industrial effluent and domestic wastewater around the lake.Heavy metals concentrations were relatively higher in the inlet area than in other areas.Negative correlations were observed between most heavy metals and pH,while a significant positive correlation was present between Zn,Cd and Pb.In the sediment core,Cu,Zn,Cr and Ni showed a decreasing trend while Cd present an increasing trend.The decrease of As,Cu,Zn,Cr and Ni in the 1990s might due to the flood event in 1998.The analysis of ecological risk assessment based on sediment quality guidelines suggested that heavy metals in most sediments from the Honghu Lake had moderate toxicity,with Cr being the highest priority pollutant.

  20. Protocol for quantitative tracing of surface water with synthetic DNA

    Science.gov (United States)

    Foppen, J. W.; Bogaard, T. A.

    2012-04-01

    Based on experiments we carried out in 2010 with various synthetic single stranded DNA markers with a size of 80 nucleotides (ssDNA; Foppen et al., 2011), we concluded that ssDNA can be used to carry out spatially distributed multi-tracer experiments in the environment. Main advantages are in principle unlimited amount of tracers, environmental friendly and tracer recovery at very high dilution rates (detection limit is very low). However, when ssDNA was injected in headwater streams, we found that at selected downstream locations, the total mass recovery was less than 100%. The exact reason for low mass recovery was unknown. In order to start identifying the cause of the loss of mass in these surface waters, and to increase our knowledge of the behaviour of synthetic ssDNA in the environment, we examined the effect of laboratory and field protocols working with artificial DNA by performing numerous batch experiments. Then, we carried out several field tests in different headwater streams in the Netherlands and in Luxembourg. The laboratory experiments consisted of a batch of water in a vessel with in the order of 10^10 ssDNA molecules injected into the batch. The total duration of each experiment was 10 hour, and, at regular time intervals, 100 µl samples were collected in a 1.5 ml Eppendorf vial for qPCR analyses. The waters we used ranged from milliQ water to river water with an Electrical Conductivity of around 400 μS/cm. The batch experiments were performed in different vessel types: polyethylene bottles, polypropylene copolymer bottles , and glass bottles. In addition, two filter types were tested: 1 µm pore size glass fibre filters and 0.2 µm pore size cellulose acetate filters. Lastly, stream bed sediment was added to the batch experiments to quantify interaction of the DNA with sediment. For each field experiment around 10^15 ssDNA molecules were injected, and water samples were collected 100 - 600 m downstream of the point of injection. Additionally

  1. Surface water quality management using an integrated discharge permit and the reclaimed water market.

    Science.gov (United States)

    Jamshidi, Shervin; Niksokhan, Mohammad Hossein; Ardestani, Mojtaba

    2014-01-01

    Water quality trading is a sustainable framework for surface water quality management. It uses discharge permits to reduce the total treatment costs. For example, the case of Gharesoo River in Iran shows that the nitrogen permit market between point and non-point sources is 37% more economical than the command and control framework. Nevertheless, the cost saving may be reduced to 6% by the end of the study period (2050). This depression may be due to the limited technical support for wastewater treatment plants. Therefore, an integrated market is recommended in which the discharge permits and the reclaimed water are traded simultaneously. In this framework, the allocation of secondary treated domestic wastewater for irrigation can provide capacity for other pollutants to discharge into the surface water. This innovative approach may decrease the total treatment costs by 63% at present, while 65%, may be achieved by the end of the study period. Furthermore, this market is able to determine the environmental penalty, trading permits, and reuse prices. For example, the maximum ratio of the average reuse price to the penalty cost is determined as 1 to 10. It is introduced as an incentive indicator for stakeholders to consider the integrated market. Consequently, the applicability and the efficiency of using this approach are verified long term.

  2. Characteristics of meter-scale surface electrical discharge propagating along water surface at atmospheric pressure

    Science.gov (United States)

    Hoffer, Petr; Sugiyama, Yuki; Hosseini, S. Hamid R.; Akiyama, Hidenori; Lukes, Petr; Akiyama, Masahiro

    2016-10-01

    This paper reports physical characteristics of water surface discharges. Discharges were produced by metal needle-to-water surface geometry, with the needle electrode driven by 47 kV (FWHM) positive voltage pulses of 2 µs duration. Propagation of discharges along the water surface was confined between glass plates with 2 mm separation. This allowed generation of highly reproducible 634 mm-long plasma filaments. Experiments were performed using different atmospheres: air, N2, and O2, each at atmospheric pressure. Time- and spatially-resolved spectroscopic measurements revealed that early spectra of discharges in air and nitrogen atmospheres were dominated by N2 2nd positive system. N2 radiation disappeared after approx. 150 ns, replaced by emissions from atomic hydrogen. Spectra of discharges in O2 atmosphere were dominated by emissions from atomic oxygen. Time- and spatially-resolved emission spectra were used to determine temperatures in plasma. Atomic hydrogen emissions showed excitation temperature of discharges in air to be about 2  ×  104 K. Electron number densities determined by Stark broadening of the hydrogen H β line reached a maximum value of ~1018 cm-3 just after plasma initiation. Electron number densities and temperatures depended only slightly on distance from needle electrode, indicating formation of high conductivity leader channels. Direct observation of discharges by high speed camera showed that the average leader head propagation speed was 412 km · s-1, which is substantially higher value than that observed in experiments with shorter streamers driven by lower voltages.

  3. Density functional theory study of water adsorption at reduced and stoichiometric ceria (111) surfaces.

    Science.gov (United States)

    Kumar, Santosh; Schelling, Patrick K

    2006-11-28

    We study the structure and energetics of water molecules adsorbed at ceria (111) surfaces for 0.5 and 1.0 ML coverages using density functional theory. The results of this study provide a theoretical framework for interpreting recent experimental results on the redox properties of water at ceria (111) surfaces. In particular, we have computed the structure and energetics of various absorption geometries at the stoichiometric ceria (111) surface. We find that single hydrogen bonds between the water and the oxide surface are favored in all cases. At stoichiometric surfaces, the water adsorption energy depends rather weakly on coverage. We predict that the observed coverage dependence of the water adsorption energy at stoichiometric surfaces is likely the result of dipole-dipole interactions between adsorbed water molecules. When oxygen vacancies are introduced in various surface layers, water molecules are attracted more strongly to the surface. We find that it is very slightly energetically favorable for adsorbed water to oxidized the reduced (111) surface with the evolution of H(2). In the event that water does not oxidize the surface, we predict that the effective attractive water-vacancy interaction will result in a significant enhancement of the vacancy concentration at the surface in agreement with experimental observations. Finally, we present our results in the context of recent experimental and theoretical studies of vacancy clustering at the (111) ceria surface.

  4. Particle dry deposition to water surfaces: Processes and consequences

    DEFF Research Database (Denmark)

    Pryor, S.C.; Barthelmie, R.J.

    2000-01-01

    's oceans and seas is most significantly impacted by human activities. More than half of the world's population lives within 100 km of a coast and hence the overwhelming majority of anthropogenic fluxes to aquatic systems occur in the coastal zone. We discuss the particular challenges that arise from...... measurement requirements represent significant barriers to application to measurement of particle dry deposition fluxes although, as discussed, innovative solutions are now becoming available. In the final section, we examine meteorological controls on deposition to the coastal zone. This region of the world...... flux to coastal waters, atmosphere-surface exchange represents a significant component of the total flux and may be particularly critical during the summertime when both the riverine input and ambient nutrient concentrations are often at a minimum. In this chapter, we present an overview...

  5. Stability of shear shallow water flows with free surface

    CERN Document Server

    Chesnokov, Alexander; Gavrilyuk, Sergey; Pavlov, Maxim

    2016-01-01

    Stability of inviscid shear shallow water flows with free surface is studied in the framework of the Benney equations. This is done by investigating the generalized hyperbolicity of the integrodifferential Benney system of equations. It is shown that all shear flows having monotonic convex velocity profiles are stable. The hydrodynamic approximations of the model corresponding to the classes of flows with piecewise linear continuous and discontinuous velocity profiles are derived and studied. It is shown that these approximations possess Hamiltonian structure and a complete system of Riemann invariants, which are found in an explicit form. Sufficient conditions for hyperbolicity of the governing equations for such multilayer flows are formulated. The generalization of the above results to the case of stratified fluid is less obvious, however, it is established that vorticity has a stabilizing effect.

  6. A surface water flooding impact library for flood risk assessment

    Directory of Open Access Journals (Sweden)

    Aldridge Timothy

    2016-01-01

    Full Text Available The growing demand for improved risk-based Surface Water Flooding (SWF warning systems is evident in EU directives and in the UK Government’s Pitt Review of the 2007 summer floods. This paper presents a novel approach for collating receptor and vulnerability datasets via the concept of an Impact Library, developed by the Health and Safety Laboratory as a depository of pre-calculated impact information on SWF risk for use in a real-time SWF Hazard Impact Model (HIM. This has potential benefits for the Flood Forecasting Centre (FFC as the organisation responsible for the issuing of flood guidance information for England and Wales. The SWF HIM takes a pixel-based approach to link probabilistic surface water runoff forecasts produced by CEH’s Grid-to-Grid hydrological model with Impact Library information to generate impact assessments. These are combined to estimate flood risk as a combination of impact severity and forecast likelihood, at 1km pixel level, and summarised for counties and local authorities. The SWF HIM takes advantage of recent advances in operational ensemble forecasting of rainfall by the Met Office and of SWF by the Environment Agency and CEH working together through the FFC. Results are presented for a case study event which affected the North East of England during 2012. The work has been developed through the UK’s Natural Hazards Partnership (NHP, a group of organisations gathered to provide information, research and analysis on natural hazards for civil contingencies, government and responders across the UK.

  7. Ground-Water, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona - 2006-07

    Science.gov (United States)

    Truini, Margot; Macy, J.P.

    2008-01-01

    The N aquifer is the major source of water in the 5,400 square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use and the needs of a growing population. Precipitation in the Black Mesa area is typically about 6 to 14 inches per year. The water-monitoring program in the Black Mesa area began in 1971 and is designed to provide information about the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected for the monitoring program in the Black Mesa area from January 2006 to September 2007. The monitoring program includes measurements of (1) ground-water withdrawals, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, and (5) ground-water chemistry. Periodic testing of ground-water withdrawal meters is completed every 4 to 5 years. The Navajo Tribal Utility Authority (NTUA) yearly totals for the ground-water metered withdrawal data were unavailable in 2006 due to an up-grade within the NTUA computer network. Because NTUA data is often combined with Bureau of Indian Affairs data for the total withdrawals in a well system, withdrawals will not be published in this year's annual report. From 2006 to 2007, annually measured water levels in the Black Mesa area declined in 3 of 11 wells measured in the unconfined areas of the N aquifer, and the median change was 0.0 feet. Measurements indicated that water levels declined in 8 of 17 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was 0.2 feet. From the prestress period (prior to 1965) to 2007, the medi